PRODUCTION OF ACETALDEHYDE
SUBMITTED IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
Bachelor of Technology
In
Chemical Engineering
By
SUSHMITA SHARMA (091431)
VINAY JAISWAL (091434)
I
UNDER THE GUIDENCE OF
Dr.K. N. Gupta
SR.LECTURER
MAY, 2013
SUBMITTED TO
DEPARTMENT OF CHEMICAL ENGINEERING
JAYPEE UNIVERSITY OF ENGINEERING AND TECHNOLOGY,A.B.
ROAD, RAGHOGARH, DIST. GUNA -473226, M.P., INDIA2011-2012
i
JAYPEE UNIVERSITY OF ENGINEERING AND TECHNOLOGY
A.B. ROAD, P.B. No. 1, RAGHOGARH, DIST. GUNA (M.P.) INDIA
Phone: -7544 267051, 267310 – 14, Fax : 07544267011
This is to certify that the project work titled “PRODUCTION OF
ACETALDEHYDE”submitted by SUSHMITA SHARMA (ER. No. 091431) and VINAY
JAISWAL(ER. No. 091434)” in the partial fulfillment for the award of degree of B.Tech.in
Chemical Engineering, by Jaypee University of Engineering and Technology, Raghogarh,
Guna, M.P., has been carried out under my supervision at JUET Guna campus. This work has
not been submitted partially or wholly to any other university or institute for the award of any
other degree or diploma.
Signature of Guide
Dr. K. N. Gupta
Sr.Lecturer
Department of Chemical Engineering
Place: Guna
Date
ii
ACKNOWLEDGEMENT
We wish to express deep sense of gratitude and sincere thanks to our project supervisor Dr.
K.N.Gupta – Assistant Professor, Department of Chemical Engineering & Chemical
Technology for his valuable guidance, encouragement, suggestions, and moral support
throughout the period of this project work.
We express our thanks to Professor N. J. Rao – Vice Chancellor of Jaypee University for his
valuable suggestions. We would like to thank Professor K. K. Tiwari, who is associated with
JUET after his retirement from ICT Mumbai for his guidance and suggestions during this
project work.
We would like to thank Dr. G. K. Agrawal for his suggestions during this work. Our special
thank to Dr. Hari Mahalingam –Head of Chemical Engineering Department for providing all
the necessary facilities to complete this work.
We would like to thank Dr. B.K.Nandi, Dr. K.N.Gupta, Dr. Rajkumar Arya and other faculty
members as well, of Chemical Engineering Department for their support during this
work..We would also like to extend our thanks to Library staff for their continuous support
and all theinformation providers on the internet.
Finally we would like to thank our batch mates and family for the motivation and support
they haveprovided us.
Signature of students
Name of Students
Date
Sushmita Sharma
iii
Vinay Jaiswal
EXECUTIVE SUMMARY
The project deals with the production of Acetaldehyde. It is an organic compound with the
chemical formula CH3CHO.Acetaldehyde is a colorless, mobile liquid having a pungent
suffocating odor that is somewhat fruity and pleasant in dilute concentrations The process
technologies used for the production of Acetaldehyde is given below.
Process technologies:




Oxidation of ethylene
Oxidation of ethyl alcohol
Hydration of Acetylene
From saturated hydrocarbon
The economics of the various processes for the manufacture of acetaldehyde are strongly
dependent on the price of the feedstock used. Since 1960, the liquid-phase oxidation of
ethylene has been the process of choice. However, there is still commercial production by
the partial oxidation of ethyl alcohol, dehydrogenation of ethyl alcohol and the hydration
of acetylene. Acetaldehyde is also formed as a co product with ethyl alcohol and acetic
acid.
Process selected
Oxidation of Ethylene is selected for the production of acetaldehyde because currently, the
Wacker-Hoechst process accounts for 85 % of the worldwide production capacity for
acetaldehyde. Acetaldehyde yield almost equal (about 95%).Lower investment costs in the
single stageprocess, because of the need of only one reactor with conversion per pass: 35 45%
This method is technically simple, smooth in reaction, and high in selectivity. The favorable
economics of the process are due to the abundance of ethylene. It is regarded as the most
economic industrial process route, and has been widely used in many countries
Process Discription
There are two variations for the production of acetaldehyde by the oxidation of ethylene; the
two – stage process developed by Wacker – Chemie and the one – stage process developed
by Farbwerke Hoechst.
The single-stage manufacture of acetaldehyde by direct oxidation of ethylene in the gaseous
phase in the presence of palladium chloride and water is known. The process is generally
carried out in the following manner on an industrial scale: Ethylene is oxidized in a bubble
column reactor containing an aqueous solution of CuCl2, CuCl and PdCl2, with oxygen, in a
cyclic process at 400K. under a pressure of 3 bars (absolute pressure), By the term "singlestage manufacture" there is to be understood that the oxidation of the ethylene yielding
acetaldehyde and the reoxidation of the palladium chloride reduced in this process
(reoxidation being effected by CuCl2 which is converted into CuCl, the latter in its turn is
reoxidized by the oxygen) are carried out in one reactor. The gas current leaving the reactor
and containing steam, acetaldehyde, ethylene and small amounts of oxygen, carbon dioxide,
acetic acid, crotonaldehyde and chlorinated compounds (such as methyl chloride, ethyl
iv
chloride and chloroacetaldehydes) is cooled in a condenser to about 80° to 130° C., about.
The condensate formed thereby substantially consisting of water, small amounts of
acetaldehyde and acetic acid is generally recycled to the reactor. Small amounts of copper
oxalate and high molecular byproducts likewise formed remain persistent in the catalyst
solution whereas the volatile by-products in conjunction with the acetaldehyde and the
unreacted starting compounds leave the reactor. In order to avoid an accumulation of these
by-products a small amount of the liquid phase is withdrawn continuously from the reactor.
Next, this portion is released from pressure, whereby the dissolved low-boiling compounds
such as acetaldehyde, ethylene and carbon dioxide flash and are removed. The degassed
solution is conveyed to a regeneration vessel, where it is heated to a temperature from about
165° to 180° C.,. The regenerated solution is recycled to the reactor. The gas current leaving
the reactor, after having been cooled in the condenser, is generally cooled further to about 30°
to 80° C., in heat exchangers. Next, the acetaldehyde is washed out from the gas current in a
scrubber. The residual gas mainly consisting of ethylene, oxygen, carbon dioxide and inert
gas is recycled to the reactor, after having removed part of this gas (in order to avoid an
accumulation of carbon dioxide and inert gas) and after having added fresh ethylene. The
condensate formed in the heat exchangers and the aqueous acetaldehyde solution formed in
the scrubberare combined in a collecting vessel. This mixture designated as "crude aldehyde"
is conveyed to a two-stage distillation process. In this process the low-boiling compounds
(methyl chloride, ethyl chloride), and the dissolved gases such as ethylene and carbon dioxide
are obtained as the overhead in a first step by extractive distillation using water as an
extraction agent. The bottom product is passed to the second distillation step, where pure
acetaldehyde is obtained as the overhead product. A fraction containing mainly
crotonaldehyde is withdrawn as a sidestream. The high-boiling by-products (in particular
acetic acid and chloroacetaldehydes) and the water are withdrawn from the bottom. The
removed mixture is designated as "waste water".
v
INDEX
CONTENTS
Title page---------------------------------------------------------------------------------------------------i
Certificate-------------------------------------------------------------------------------------------------ii
Acknowledgment-------------------------------------- -------------------------------------------------iii
Executive Summary------------------------------------------------------------------------------------iv
CHAPTER 1: HISTORICAL PROFILE-----------------------------------------------------------1-2
1.1-History of acetaldehyde-----------------------------------------------------------------------------1
1.2-Natural occurrence-------------------------- --------------------------------------------------------2
CHAPTER 2: APPLICATIONS------------------------------------------------------------------------3
2.1-Traditional Applications-----------------------------------------------------------------------------3
2.2-Current Applications---------------------------------------------------------------------------------3
2.3-Acetaldehyde Grades--------------------------------------------------------------------------------3
CHAPTER 3: ECONOMIC SCENARIO----------------------------------------------------------4-7
3.1- Economic Aspect------------------------------------------------------------------------------------4
3.2-Demand and supply--------------------------------------------------------------------------------5-6
3.3-Manufacturers-----------------------------------------------------------------------------------------7
CHAPTER 4: PROPERTIES------------------------------------------------------------------------8-13
4.11-Physical properties----------------------------------------------------------------------------------8
4.2-Chemical properties------------------------------------------------------------------------------9-10
4.3-Environmental effects-----------------------------------------------------------------------------11
4.4-Health effects--------------------------------------------------------------------------------------12
4.5-Acute /fatal effects---------------------------------------------------------------------------------13
CHAPTER 5: MANUFACTURING PROCESSES -------------------------------------------14-20
5.1-Oxidation of Ethylene: ------------------------------------------------------------------------14-16
5.2-From Ethyl Alcohol----------------------------------------------------------------------------16-17
5.3-From Acetylene: --------------------------------------------------------------------------------17-18
5.4-From Saturated Hydrocarbons----------------------------------------------------------------18-19
5.5-Specifications, Analytical, and Test Methods---------------------------------------------------20
CHAPTER 6: PROCESS SELECTION-------------------------------------------------------------21
CHAPTER 7: MATERIAL AND ENERGY BALANCE------------------------------------22-38
7.1 Material balance---------------------------------------------------------------------------------22-30
7.2 Energy balance--------------------------------------------------- ------------------------------31-37
vi
7.3 Control strategy ---------------------------------------------------------------------------------38-39
CHAPTER 8: DETAILED EQUIPMENT DESIGN---------------------------------------------------------------40-51
8.1 Process Design Of Reactor ---------------------------------------------------------------------40
8.1.1Mechanical Design Of Reactor ------------------------------------------------------------40-42
8.3 Process design of Distillation column--------------------------------------------------------42-50
8.4 Process design of scrubber-------------------------------------------------------------------------51
8.4.1 Mechanical Design of Scrubber-----------------------------------------------------------------52
CHAPTER 9 : CAPITAL COST ESTIMATION--------------------------------------------------------------------53-64
9.1.1Cost of Reactor-------------------------------------------------------------------------------------53
9.1.2Cost of Absorber-------------------------------------------------------------------------------53-54
9.1.3 Cost of Distillation Column I-------------------------------------------------------------------54
9.1.4Cost of Distillation Column II------------------------------------------------------------------54
9.1.5 Cost of ethylene storage vessel-----------------------------------------------------------------55
9.1.6Cost of heat exchanger----------------------------------------------------------------------------55
9.2 Estimation of Capital Investment-------------------------------------------------------------55-56
9.2.1Estimation of Total Product Cost------------------------------------------------------------56-57
9.2.2 Direct Production cost----------------------------------------------------------------------------57
9.2.3 Plant overhead cost-----------------------------------------------------------------------------58
9.2.4 General Expenses-----------------------------------------------------------------------------58-59
9.2.5 Gross Earning Income---------------------------------------------------------------------------59
9.3 Hazop analysis of reactor----------------------------------------------------------------------60-62
9.4 Plant layout --------------------------------------------------------------------------------------63-64
10. Conclusion & Recommendation----------------------------------------------------------------65
References-----------------------------------------------------------------------------------------------66
Appendix-1------------------------------------------------------------------------------------------67-73
vii
CHAPTER-1
HISTORICAL PROFILE
1.1-History of acetaldehyde:
Ethanal is one of the oldest known aldehydes and was first made in 1774 by Swedish chemist
Carl Wilhelm Scheele by the action of manganese dioxide and sulfuric acid on ethanol.
Its structure was not completely understood until 60 years later, when Justus von Liebig
determined the constitution of ethanal, described its preparation from ethanol, and gave the name
of aldehydes to the chemical group. The formation of acetaldehyde by the addition of water to
acetylene was observed by Kutscherow in 1881.
Acetaldehyde was first used extensively during World War I as an intermediate for making
acetone from acetic acid. Ethanal (acetaldehyde) is the name of the shortest carbon chain
aldehyde. It has a central carbon atom that has a double bond to an oxygen atom (the carbonyl
group), a single bond to a hydrogen atom, and a single bond to another carbon atom connected to
three hydrogen atoms (methyl group). Its chemical formula is written as CH3CHO. [1]
Acetaldehyde
1.2-Natural occurrence:
Acetaldehyde is a simple, naturally-occurring, organic chemical present in many ripe
fruits,apples, grapes, and citrus fruits (up to 230 ppm). It is produced during the fermentation of
sugar to alcohol, and is a natural constituent of butter, olives, frozen vegetables, and cheese. It
forms in wine and other alcoholic beverages after exposure to air (up to 140 ppm). It even
occurs as an intermediate in the metabolism of sugars in the body and hence can be found in
human blood.
Acetaldehyde is listed as an approved food additive and is used to enhance citrus flavours,
helping to create natural, fruity tastes and fragrances. As a flavour ingredient, it can be found in
ice creams, sweets, baked goods, chocolates, rum, and wine.
1
In nature acetaldehyde is found in oak and tobacco leaves, in the fruity aromas of apple,
raspberry, strawberry, pear and pineapple. It is also found in the distillation waters of orris,
cumin, chenopodium, essential oils of Magnolia grandijlora, rosemary, clary sage, daffodil, bitter
orange, camphor angelica, fennel mustard, whiskey, rose wine and rum.
Acetaldehyde is a natural component of, broccoli, coffee, grapefruit, grapes, lemons,
mushrooms, onions, oranges, peaches, pears, pineapples, raspberries, and strawberries. It has
been detected in the essential oils of alfalfa, rosemary, balm, clary sage, daffodil, bitter orange,
camphor, angelica, fennel, mustard, and peppermint.
Acetaldehyde (systematically ethanal) is an organic chemical compound with the formula
CH3CHO, sometimes abbreviated by chemists as MeCHO (Me = methyl). It is one of the most
important aldehydes, occurring widely in nature and being produced on a large scale industrially.
Acetaldehyde occurs naturally in coffee and bread and is produced by plants as part of their
normal metabolism. It is also produced by oxidation of ethylene and is popularly believed to be a
cause of hangovers from alcohol consumption through drinking spirits. Pathways of exposure
include air, water, land or groundwater as well as drink and smoke. [2]
2
CHAPTER- 2
APPLICATIONS
2.1-Traditional application:
Traditionally, acetaldehyde was mainly used as a precursor to acetic acid. This application has
declined because acetic acid is made more efficiently from methanol by the Monsanto and Cativa
processes. In terms of condensation reactions, acetaldehyde is an important precursor to pyridine
derivatives, pentaerythritol, and crotonaldehyde. Urea and acetaldehyde combine to give a useful
resin. Acetic anhydride reacts with acetaldehyde to give ethylidene diacetate, a precursor to vinyl
acetate, which is used to produce polyvinyl acetate.
2.2-Current application:




Acetaldehyde is used as an intermediate in the production of acetic acid, acetic
anhydride, cellulose acetate, vinyl acetate resins, acetate esters, pentaerythritol, synthetic
pyridine derivatives, terephthalic acid and peracetic acid.
Other uses of Acetaldehyde include: in the silvering of mirrors; in leather tanning; as a
denaturant for alcohol; in fuel mixtures; as a hardener for gelatin fibres; in glue and
casein products; as a preservative for fish and fruit; in the paper industry; as a synthetic
flavouring agent; and in the manufacture of cosmetics, aniline dyes, plastics and synthetic
rubber (SCCNFP 2004).
Acetaldehyde is an ingredient contained used in many fragrance and flavour compounds.
It may be found in fragrances used in decorative cosmetics, fine fragrances, shampoos,
toilet soaps and other toiletries, in flavours of oral care products as well as in noncosmetic products such as household cleaners and detergents. Low levels of
Acetaldehyde are reported to occur in several essential oils.[3]
2.3- Acetaldehyde grade[4]
Table 2.1-Acetaldehyde grade
Grade
00070Acetaldehyde
Purity
anhydrous, ≥99.5% (GC)
00071Acetaldehyde
ReagentPlus, ≥99.0% (GC
W200336Acetaldehyde
natural, ≥99%, FCC, FG
W200301Acetaldehyde
≥99%, FCC
3
CHAPTER 3
ECONOMIC SCENARIO
3.1- World Economic Aspect
Acetaldehyde is produced throughout the world primarily from ethylene, although some is still
derived from ethanol and acetylene. Demand for acetaldehyde worldwide has continued to
decrease primarily as a result of less consumption for acetic acid manufacture, as the industry
continues to move toward the more efficient and lower-overall-cost carbonylation-of-methanol
process. For example, all manufacture of acetic acid from acetaldehyde in North America has
been discontinued and in Europe significant capacity for this process has been permanently shut
down. Acetaldehyde use for acetic acid manufacture in Asia continues but is under pressure from
the ongoing establishment of methanol carbonylation technology.
Demand has also significantly declined in the production of plasticizer alcohols, which has
totally switched to oxo processes. As a result of these process replacements, acetaldehyde
capacity has been shut down in Western Europe and in other areas, such as Mexico. In addition
to the disappearance of use for acetic acid and plasticizer alcohols, acetaldehyde demand has also
declined in the last few years because of mature end-use markets and the effects of the economic
downturn on these acetaldehyde-derived products. There has also been continued substitution for
acetaldehyde-based chemistries with other materials, which has further contributed to the drop in
acetaldehyde use.
The following pie chart shows world consumption of acetaldehyde:
Figure shows that China consumed 30% , Europe and Japan 20% each and Indian and rest of
world 15% a piece of the total acetaldehyde produced in year 2009.
4
Consumption in China is expected to grow over 5% annually in the next five years.
Acetaldehyde use for acetic acid production will increase, although this will be more of a
recovery back to the pre-2009 level. Actual growth might be limited because of acetic acid
production from the methanol carbonylation process. Strong growth of over 6% annually will
actually occur in pyridine production and there will be moderate growth for use in
pentaerythritol, as alkyd resin enamel and varnish production goes up. Other uses are generally
mature, such as sorbic acid production.
Indian consumption is anticipated to have moderate growth of over 3% annually in the next
several years. Acetaldehyde demand for acetic acid production will grow 3–4% per year, while
consumption for pyridines is expected to return to the 2008 level. Other uses for acetaldehyde
will also increase 3–4% annually.
Overall, the global market for acetaldehyde is expected to grow 2–3% annually during 2009–
2014. However, some of this growth is actually a recovery from the significant decline
experienced in 2009 (for example, China's use in the acetic acid market). Major regions
including Japan, Western Europe and the United States will have low growth because of no use
or no growth for acetic acid production, minimal growth in other acetaldehyde-consuming
products, or continued product replacement of materials that consume acetaldehyde. [5]
3.2-Demand and Supply
World acetaldehyde market will reach 1.26 million tons by 2012, according to new report by
global industry analysts.
With acetic acid manufacturing processes migrating from acetaldehyde based production
techniques towards carbonylation-of-methanol, the world acetaldehyde market is projected to
witness a steady deterioration in consumption. Global consumption of acetaldehyde is projected
to average to 1.26 million tons by the year 2012. Exacerbating the decline in demand and
consumption is the lack of new high-volume applications of acetaldehyde, and closures of aceticacid-from-acetaldehyde operations across the world.
The downturn in the acetic acid industry, the largest end-use market for acetaldehyde, coupled
with the phasing out of acetic acid production from acetaldehyde, is expected to result in huge
declines in consumption. In North America, acetic acid manufacturers have shut down their
operations, while in Europe; significant reductions in capacities are underway. Scaling back of
production activities is expected in Latin America and Asia Pacific in the upcoming years.
Presently however, Asia-Pacific represents the largest market for acetaldehyde with growth
stemming from the use of acetaldehyde in producing synthetic pyridines, pentaerythritol,
glyoxal/glyoxalin acid, penta-erithryte, and crotonaldehyde. Within Asia, China has emerged
into the largest consumer of acetaldehyde in the world, with the country representing the only
market where new acetaldehyde capacity installations have occurred in the recent past.
5
As stated by the recent report published by Global IndustryAnalysts, Inc., world acetaldehyde
market is dominated by Asia-Pacific, and Europe, with a combined share of 68.4% estimated in
the year 2008.
World consumption of acetaldehyde in acetane hydride end-use market, and acetic ether end-use
markets, is projected to decline by 2%, and 1.3% respectively during the period 2001 to 2010.
Positive growth is expected to stem from 1,3 butanediol end-use market , with world
consumption slated to rise of 2.7% during the period 2011 to 2015. In Asia-Pacific, consumption
of acetaldehyde in crotonaldehyde end-use market is projected to grow in excess of 3.7% over
the period 2011 through 2015.
In Europe, Germany ranks as the largest market for acetaldehyde with a 30.9% share estimated
in the year 2008, followed by France, United Kingdom and Italy. [6]
Table-3.1-Important producers and their production capacities (103 t) are listed in the
following [7]
Year
1990
1995
2000
2003
USA
283
111
155
142
W.Europ
603
668
370
212
Mexico
190
271
113
57
Japan
384
395
401
362
China
Total
1460
1845
1439
1273
400
400
500
3.3-Manufacturers
Acetaldehyde is produced by 3 companies in Germany, 2 companies in Spain & 1 company each
in France, Italy, & Switzerland. Total acetaldehyde production in western Europe on January 1,
1983 was more than 0.5 million tons, & production capacity is estimated to have been nearly 1
million tons. Most of this was based on the catalytic oxidation of ethylene; less than 10% was
based on partial oxidation of ethanol, & a very small percentage was based on the hydration of
acetylene. ... /It/ is produced (by oxidation of ethylene) by 7 companies in Japan. Their combined
production is est to have been 278,000 tons in 1982, down from an est 323,000 tons in 1981.
Japanese imports & exports of acetaldehyde are negligible.
Table-3.2-Manufacturers of Acetaldehyde in india
PRODUCT
COMPANY NAME
Ashok Organic Inds. Ltd. Ankleshwar Gujarat
Unit-II.
King Chemicals Ltd. Madras
Trichy Distilleries & Chemicals Ltd., Trichy.
Ashok Organic Inds. Ltd., Ankleshwar, Gujarat
Unit-III.
6
Acetaldehyde
CAPACITY
(TPA)
3600
Acetaldehyde
Acetaldehyde
Acetaldehyde
6000
6000
5400
Ashok Organics India Ltd. Ankleshwar, Unit-I.
Cellulose Products of India Ltd., Ankleshwar.
EID Parry (India) Ltd. Madras.
Gujchem Distillers Ltd. Ankleshwar, Gujarat.
Indian Drugs & Pharmaceuticals Ltd., Muzafarpur,
Bihar.
Indian Organics Ltd. Khopoli (M.S.)
Industrial Organics Ltd. Ludhiana.
Kapchem Ltd. Bangalore.
Laxmi Organic Industries Ltd., Maharashtra.
Pentokey Organy (India) Pvt. Ltd. Maharashtra
Polychem Ltd., Nira, Pune.
Sahakar Maharshi Shankarrao Mohite-Patil
Sahakari Sakhar Karkhana Ltd., Shankarnagar,
Akluj, Maharashtra.
Southern Organic Inds. Ltd. Bangalore.
7
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
2400
3000
9000
3000
7500
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
Acetaldehyde
3000
3600
3500
4800
3600
6000
6000
Acetaldehyde
2400
CHAPTER 4
PROPERTIES
4.1-Physical properties:
Acetaldehyde is a colorless, mobile liquid having a pungent suffocating odor that
is somewhat fruity and pleasant in dilute concentrations. Some physical properties of
Acetaldehyde is given in Table 2.
Table-4.1 Physical properties [8]
Molecular formula
Chemical Structure
Physical State
Molecular Weight
Melting Point
Boiling Point
Water Solubility
Density
Vapor Density (air = 1)
Vapor Pressure
Reactivity
Flash Point
Surface tension at 20 °C,mN/ma
Coefficient of expansion per °C (0-30
°C)
Latent heat of vaporization, kJ/mol
Heat of combustion of liquid at constant
pressure, kJ/mol c
C2H4O
CH3-CHO
colorless liquid
44.05
-123.5øC
21øC at 760 mm Hg
miscible
d16/4, 0.788
1.52
740 mm Hg @ 20øC
highly reactive
-36øF (-38øC)
21.2
0.00169
Heat of formation at 273 K, kJ/mol c
Critical temperature, °C
Critical pressure, MΡa (atm)
Ignition temperature in air, °C
Explosive limits of mixtures with air, vol
%
Acetaldehyde
-165.48
181.5
6.40(63.2)
165
4.5 – 60.5
25.71
11867.9
8
 4.2 Chemical properties: [9]
Acetaldehyde is a highly reactive compound exhibiting the general reactions ofaldehydes; under
suitable conditions, the oxygen or any hydrogen can be replaced.Acetaldehyde undergoes
numerous condensation, addition, and polymerization reactions.
 4.2.1 Decomposition:
Acetaldehyde decomposes at temperatures above 400°C, forming principally methane and
carbon monoxide. The activation energy of the pyrolysis reaction is 97.7 kJ/mol (408.8
kcal/mol). There have been many investigations of the photolytic and radical – induced
decomposition of acetaldehyde and deuterated acetaldehydes.
 4.2.2 The Hydrate and Enol Form:
In aqueous solutions, acetaldehyde exists in equilibrium with the hydrate,CH3CH(OH)2. The
degree of hydration can be computed from an equation derived by Bell and Clunie. The mean
heat of hydration is –21.34 kJ/mol(89.29kcal/mol); hydration has been attributed to hyper
conjugation. The enol form, vinyl alcohol (CH2 = CHOH) exists in equilibrium with
acetaldehyde to the extent of approximately one molecule per 30,000. Acetaldehyde enol has
been acetylated with ketene to form vinyl acetate.
 4.2.3 Oxidation:
Acetaldehyde is readily oxidized with oxygen or air to acetic acid, acetic anhydride, and
peracetic acid (see Acetic acid and derivatives). The principal product isolated depends on
reaction conditions. Acetic acid is produced commercially by the liquid – phase oxidation of
acetaldehyde at 65°C with cobalt or manganese acetate dissolved in acetic acid as a catalyst.
Liquid – phase oxidation of acetaldehyde in the presence of mixed acetates of copper and cobalt
yields acetic anhydride.
 4.2.4 Reduction:
Acetaldehyde is readily reduced to ethanol. Suitable catalysts for vapor-phase hydrogenation are
supported nickel and copper oxide. Oldenberg and Rose have studied the kinetics of the
hydrogenation of acetaldehyde over a commercial nickel catalyst.
 4.2.5 Polymerization:
Paraldehyde,2,4,6- trimethyl – 1,3,5 – trioxan, a cyclic trimer of acetaldehyde is formed when a
mineral acid, such as sulfuric, phosphoric, or hydrochloric acid, is added to acetaldehyde.
9
Paraldehyde can also be formed continuously by feeding acetaldehyde as a liquid at 15 - 20°C
over an acid ion – exchange resin. Depolymerization of paraldehyde occurs in the presence of
acid catalysts. After neutralization with sodium acetate, acetaldehyde and paraldehyde are
recovered by distillation. Paraldehyde is a colorless liquid, boiling at 125.35 °C at 101 kPa (1
atm).
 4.2.6 Reactions with aldehydes and ketones:
The base catalyzed condensation of acetaldehyde leads to the dimmer, acetaldol, which can be
hydrogenated to form 1,3 butandiol or dehydrated to form crotonaldehyde. Crotonaldehyde can
also be made directly by the vapor-phase condensation of acetaldehyde over a catalyst.
Crotonaldehyde was formerly an important intermediate in the production of butyraldehyde,
butanol, and 2-ethylhexanol. However it has been replaced completely with butyraldehyde from
the oxo process. A small amount of crotonaldehyde is still required for the production of
crotonic acid. Acetaldehyde forms aldols with other carbonyl compounds containing active
hydrogen atoms.
 4.2.7 Reactions with Ammonia and Amines:
Acetaldehyde readily adds ammonia to form acetaldehyde ammonia. Diethyl amine is obtained
when acetaldehyde is added to a saturated aqueous or alcoholic solution of ammonia and the
mixture is heated to 50-750C in the presence of a nickel catalyst and hydrogen at 1.2 MPa
(12atm). Pyridine and pyridine derivates are made from paraldehyde and aqueous ammonia in
the presence of a catalyst at elevated temperatures; acetaldehyde may also be used by the yields
of pyridine are generally lower than when paraldehyde is the staring material. Levy and Othmer
have studied the vapor- phase reaction of formaldehyde, acetaldehyde, and ammonia at 3600C
over oxide catalysts; a 49% yield of pyridine and picolines was obtained using an activated
silica-alumina catalyst. Brown polymers result when acetaldehyde reacts with ammonia or
amines at a PH of 6-7 and temperature of 3-250C. With acetaldehyde, a primary amines can be
condensed to Schiff bases: CH3CH=NR, the schiff base rivets to the starting materials in the
presence of acids.
 4.2.8 Reactions with Alcohols and Phenols:
Alcohols add readily to acetaldehyde in the presence of a trace of mineral acid to form acetals;
eg, ethanol and acetaldehyde form diethyl acetal. Similarly, cyclic acetals are formed by the
reactions with glycols and other polyhydroxy compounds; eg, the reaction of ethylene glycol and
acetaldehyde gives 2 – methyl – 1,3 – dioxolane.
 4.2.9 Reactions with Halogens and Halogen compounds:
Halogens readily replace the hydrogen atoms of the methyl group: eg, chlorine reacts with
acetaldehyde or paraldehyde at room temperature to give chloroacetaldehyde; increasing the
temperature to 700-8000C gives dichloroacetaldehyde; and at a temperature of 80-900C chloral is
formed. The catalytic chlorination with an antimony powder or aluminum chloride ferric
chloride has been described.
10
4.3 Environmental effects: [10]
 4.3.1 Environmental Release:
Acetaldehyde is released into air or wastewater from facilities producing or using the
chemical. Acetaldehyde is also released to the environment from the combustion and photooxidation of hydrocarbons. Acetaldehyde is an intermediate product of respiration in higher
plants and occurs naturally in many foods, such as ripe fruits that have tart tastes before
ripening, and coffee. Acetaldehyde is a component of cigarette smoke.
In 1992, releases of acetaldehyde to environmental media, as reported to the Toxic
Chemical Release Inventory by certain types of U.S. industries, totaled about 8.4 million pounds:
6.42 million pounds to the atmosphere; 1.9 million pounds to underground injection sites;
77,188 pounds to surface water discharges; and 289 pounds to land.
Concentrations of acetaldehyde measured in air samples taken from different locations vary,
depending on several conditions, including weather. The chemical has been detected in ice fog,
rain, cloud mist, and fog.
 4.3.2 Transformation/Persistence:
4.3.2.1 Air
In air (at 25øC), acetaldehyde reacts with OH radicals, NO3, singlet oxygen, and NO2 The
estimated half-life for the reaction of acetaldehyde with OH produced by UV light is 6.2
hours; the products of this reaction include peroxyacetylnitrate (PAN), methyl nitrate,
methyl nitrite, and nitric acid . Acetaldehyde absorbs UV light at wavelengths of 290 to
342 nm, indicating some potential for photolysis. The photolytic half-lives for acetaldehyde
are about 34 hours in the summer and 296 hours in winter at 55ø c
4.3.2.2 Soil
Acetaldehyde will volatilize rapidly in near surface and surface soils or leach into the ground, or
undergo microbial degradation. Acetaldehyde is not expected to adsorb to soils, other than
those containing montmorillonite clay.
4.3.2.3 Water
If released to water, acetaldehyde will rapidly biodegrade or volatilize (for a typical river, the
half-life is 9.3 hours). Laboratory tests demonstrate that acetaldehyde is easily biodegraded (1)
by acclimated sludge and sewage with theoretical biological oxygen demand (BOD)
11
4.4 Health effects:
Acetaldehyde is the major metabolite of ethanol. Many of the adverse effects of ethanol are
attributed to acetaldehyde. Direct administration of acetaldehyde to rats has established alcohol
dependency.
Pharmacokinetics:
4.4.1 Absorption –
Acetaldehyde is rapidly absorbed by oral and respiratory routes. Estimated half-lives of
acetaldehyde in circulating blood have been reported as <15 minutes and 3.1 minutes.
4.4.2 Distribution –
Experimental studies indicate that, following inhalation or oral exposure, sufficient first-pass
metabolism occurs in the liver and respiratory tract to limit acetaldehyde access to the systemic
circulation. However, acetaldehyde was detectable in the liver, blood, kidney, spleen, heart, and
bone of rats exposed to the 20 mM vapor for 1 hour and in maternal and embryonic tissues
following administration (route unspecified) of >5 g/kg ethanol to pregnant mice
4.4.3 Metabolism –
Acetaldehyde is metabolized (mainly in mammalian liver) to acetic acid by aldehyde
dehydrogenase. The rate of metabolism to acetic acid varies, but it is generally considered to be
rapid. Acetic acid enters the metabolic pool of intermediary metabolism and is used in the
production of carbon dioxide and water or in cellular synthesis of cholesterol, fatty acids, and
other tissue constituents. In vitro, acetaldehyde formed adducts with cytosine- and purinecontaining nucleotides.
4.4.4 Excretion –
Because the major metabolite of acetaldehyde enters into intermediary metabolism, the excretion
of the parent compound or its metabolites may be limited. Acetaldehyde has been detected in
expired air (usually no more than 5%) but only its metabolites have been detected in the urine
.
4.5-Acute /fatal effects:
Humans exposed acutely to moderate concentrations of acetaldehyde experience irritation of the
eyes and respiratory tract and altered respiratory function. Animals exposed to moderate to high
concentrations exhibit skin and eye irritation.
4.5.1 Humans –
12
The acute irritation of acetaldehyde is characterized by the following: eye irritation in sensitive
individuals, at 25 ppm for 15 minutes; eye irritation, at 50 ppm for 15 minutes; irritation of
respiratory tract, at 134 ppm for 30 minutes.
4.5.2 Animals –
The oral LD50 value for the rat is 1.93 g/kg .The inhalation LC50 for rats exposed for 30
minutes was 20,000 ppm . Acetaldehyde elicited mild skin irritation (open test) and severe eye
irritation in rabbits.
4.6 Handling storage and shipping information: [11]
Acetaldehyde should be stored in the dark in tightly closed containers, under cool and fireproof
conditions with the addition of an inhibitor. It must be stored away from substances with which it
can react, such as halogens, oxidative substances, amines, organic substances, caustic solutions,
concentrated sulfuric acid.
It is suggested that the photo-induced atmospheric removal of acetaldehyde occurs
predominantly via radical formation. Photolysis is expected to contribute another substantial
fraction to the removal process. Both processes cause a reported daily loss of about 80% of
atmospheric acetaldehyde emissions. Reported half-lives of acetaldehyde in water and air are 1.9
h and 10-60 h, respectively.
During transport, storage and fur-ther processing, Acetaldehyde must be blanketed with
protective gas (nitrogen). It is transported in pressure containers (rail tankers). Acetaldehyde is
stored in pressure containers or at zero pressure in refrigerated containers. Acetaldehyde may be
stable in storage under these conditions.
Around 80% of the total production of acetaldehyde is made by liquid-phase oxidation of
ethylene using a catalytic solution of palladium and copper chlorides. The remainder is produced
by the oxidation of ethanol and the hydration of acetylene. Intercompartmental transport of
acetaldehyde is expected to be limited because of its high reactivity. However, some transfer of
acetaldehyde to air from water and soil is expected, because of its high vapour pressure and low
sorption coefficient.
13
CHAPTER - 5
MANUFACTURING PROCESSES
Manufacturing processes




Oxidation of ethylene
Oxidation of ethyl alcohol
Hydration of Acetylene
From saturated hydrocarbon
The economics of the various processes for the manufacture of acetaldehyde are strongly
dependent on the price of the feedstock used. Since 1960, the liquid-phase oxidation of ethylene
has been the process of choice. However, there is still commercial production by the partial
oxidation of ethyl alcohol, dehydrogenation of ethyl alcohol and the hydration of acetylene.
Acetaldehyde is also formed as a co product with ethyl alcohol and acetic acid.
5.1 Oxidation of Ethylene: [12]
5.1.1 Raw material:In this process ethylene and oxygen used as raw material. Where Ethylene is obtained from
petrochemical industry and oxygen is taken from air.
Wacker – Chemie and Farbwerke Hoechst, developed the direct liquid phase oxidation of
ethylene in 1957 – 1959. The catalyst is an aqueous solution of PdCl2 and CuCl2. In 1894, F.C.
Phillips observed the reaction of ethylene with an aqueous palladium chloride solution to form
acetaldehyde.
C2H4+PdCl2 + H2O  CH3CHO +Pd +2HCl
The metallic palladium is reoxidized to PdCl2 with CuCl2 and the cuprous chloride formed is
reoxidized with oxygen or air.
Pd + 2CuCl2  PdCl2 +2CuCl
14
2CuCl+1/2 O2 + 2HCl  2CuCl2 + H2O
The net result is a process in which ethylene is oxidized continuously through a series of
oxidation – reduction reactions.
C2H4 + ½ O2  CH3CHO
∆H = -244 kJ(-57.84 kcal/kmol)
5.1.2 Process Description.
There are two variations for the production of acetaldehyde by the oxidation of ethylene; the two
– stage process developed by Wacker – Chemie and the one – stage process developed by
Farbwerke Hoechst.
The single-stage manufacture of acetaldehyde by direct oxidation of ethylene in the gaseous
phase in the presence of palladium chloride and water is known (cf. Jira, Blau, Grimm;
Hydrocarbon Processing, March 1976, pages 97 to 100). The process is generally carried out in
the following manner on an industrial scale: Ethylene is oxidized in a bubble column reactor
containing an aqueous solution of CuCl2, CuCl and PdCl2, with oxygen, in a cyclic process at
400K. under a pressure of 3 bars (absolute pressure), By the term "single-stage manufacture"
there is to be understood that the oxidation of the ethylene yielding acetaldehyde and the
reoxidation of the palladium chloride reduced in this process (reoxidation being effected by
CuCl2 which is converted into CuCl, the latter in its turn is reoxidized by the oxygen) are carried
out in one reactor. The gas current leaving the reactor and containing steam, acetaldehyde,
ethylene and small amounts of oxygen, carbon dioxide, acetic acid, crotonaldehyde and
chlorinated compounds (such as methyl chloride, ethyl chloride and chloroacetaldehydes) is
cooled in a condenser to about 80° to 130° C., about. The condensate formed thereby
substantially consisting of water, small amounts of acetaldehyde and acetic acid is generally
recycled to the reactor. Small amounts of copper oxalate and high molecular byproducts likewise
formed remain persistent in the catalyst solution whereas the volatile by-products in conjunction
with the acetaldehyde and the unreacted starting compounds leave the reactor. In order to avoid
an accumulation of these by-products a small amount of the liquid phase is withdrawn
continuously from the reactor. Next, this portion is released from pressure, whereby the
dissolved low-boiling compounds such as acetaldehyde, ethylene and carbon dioxide flash and
are removed. The degassed solution is conveyed to a regeneration vessel, where it is heated to a
temperature from about 165° to 180° C.,. The regenerated solution is recycled to the reactor. The
gas current leaving the reactor, after having been cooled in the condenser, is generally cooled
further to about 30° to 80° C., in heat exchangers. Next, the acetaldehyde is washed out from the
gas current in a scrubber. The residual gas mainly consisting of ethylene, oxygen, carbon dioxide
and inert gas is recycled to the reactor, after having removed part of this gas (in order to avoid an
accumulation of carbon dioxide and inert gas) and after having added fresh ethylene. The
condensate formed in the heat exchangers and the aqueous acetaldehyde solution formed in the
scrubberare combined in a collecting vessel. This mixture designated as "crude aldehyde" is
15
conveyed to a two-stage distillation process. In this process the low-boiling compounds (methyl
chloride, ethyl chloride), and the dissolved gases such as ethylene and carbon dioxide are
obtained as the overhead in a first step by extractive distillation using water as an extraction
agent. The bottom product is passed to the second distillation step, where pure acetaldehyde is
obtained as the overhead product. A fraction containing mainly crotonaldehyde is withdrawn as a
sidestream. The high-boiling by-products (in particular acetic acid and chloroacetaldehydes) and
the water are withdrawn from the bottom. The removed mixture is designated as "waste water".
In the two – stage process ethylene and oxygen (air) react in the liquid phase in two stages. In the
first stage ethylene is almost completely converted to acetaldehyde in one pass in a tubular plugflow reactor made of titanium. The reaction is conducted at 125-1300C and 1.13 Mpa (150 psig)
palladium and cupric chloride catalysts. Acetaldehyde produced in the first reactor is removed
from the reaction loop by adiabatic flashing in a tower. The flash step also removes the heat of
reaction. The catalyst solution is recycled from the flash – tower base to the second stage (or
oxidation) reactor where the cuprous salt is oxidized to the cupric state with air. The high
pressure off – gas from the oxidation reactor, mostly nitrogen, is separated from the liquid –
catalyst solution and scrubbed to remove acetaldehyde before venting. A small portion of the
catalyst stream is heated in the catalyst regenerator to destroy undesirable copper oxalate. The
flasher overhead is fed to a distillation system where water is removed for recycle to the reactor
system and organic impurities, including chlorinated aldehydes, are separated from the purified
acetaldehyde product.
While according to the two-stage method, the ethylene reaction and the oxidation reaction
proceed in separate reactors. However, this two-stage variant of the method requires a catalyst
circulation entailing high energy consumption and has technically been less frequently realized
than the single-stage variant.
This method is technically simple, smooth in reaction, and high in selectivity. The favorable
economics of the process are due to the abundance of ethylene. It is regarded as the most
economic industrial process route, and has been widely used in many countries.
Flow sheet-5.1- Production of acetaldehyde from oxidation of ethylene
16
5.2 From Ethyl Alcohol: [13]
Acetaldehyde is produced commercially by the catalytic oxidation of ethyl alcohol. Passing
alcohol vapors and preheated air over a silver catalyst at 4800C carries out the oxidation.
CH3CH2OH + ½ O2  CH3CHO + H2O, ∆H = 242 kj/mol (57.84 kcal / mol)
With a multitubular reactor, conversions of 74-82% per pass can be obtained while generating
steam to be used elsewhere in the process.
Acetaldehyde also, produced commercially by the dehydrogenation of ethyl alcohol.
Reaction:
C2H5OH CH3CHO + H2
Catalyst: Cu -Co-Cr2O3
Temperature: 280 – 3500 C.
5.2.1-Process Description:
The following section will describe a silver process for acetaldehyde production from ethanol
.Air and preheated ethanol goes into a saturator. The air leaving is saturated with ethanol and
overheated before entering the reactor. The main reactions that take place are:
C2H5OH + ½ O2 → CH3CHO + H2O
C2H5OH → CH3CHO + H2
The by-products are formed according to following reactions:
C2H5OH + O2 → CH3COOH + H2O
C2H5OH + ½ O2 → CH4 + CO + H2O
C2H5OH + 2 O2 → 2 CO2 + 3 H2O
Ethanol is mixed with air and passed over a silver catalyst at 500 – 650 ◦C in the reactor .The
high temperature gas (acetaldehyde and unconverted alcohol) from the outlet of oxidizer is
cooled and condensed, then sent to scrubber to absorb acetaldehyde and unconverted ethanol.
Nitrogen hydrogen, methane, carbon monoxide and carbondioxide gas and other inert gases are
discharged from the top of the tower.. The diluted acetaldehyde solution at the bottom of the
scrubber, which contains acetaldehyde, alcohol, acetic acid, and water, is sent to the distillation
tower after heating, the gas phase fraction from the tower top, after condensation, is partly
collected, which is 99% acetaldehyde and the most portion is refluxed back.The ethanol and
water solution discharged from the bottom of the distillation tower is pressed into ethanol
recovery tower. where ethanol is separated from butanol, ethyl acetate, and most of the water.
These impurities exit in bottom Stream and are sent to waste treatment. The distillate consists of
an 85-wt.% solution of ethanol, which is then recycled back in the feed.
17
Flowsheet-5.2 for Acetaldehyde production from oxidation of Ethanol
5.3 From Acetylene:
[14]
Acetylene used as raw material for producing acetaldehyde in petrochemical industries.
In theory, there are two methods for this process to take place.
.Using solid catalyst in vapour phase system for acetylene hydration.
.by using a mercury-ion(liquid) catalyst in liquid phase for hydration of acetylene.
In fact, acetaldehyde is also manufacture from vinyl ethers, ethyl alcohol and ethylene.Industrial
process of producing acetaldehyde by hydration of acetylene using mercury-iron catalyst in
liquid phase is much simpler in construction and handling the operation.
5.3.1 Process Description:
A special designed hydrator converts acetylene to acetaldehyde by managing following chemical
reactions.
C2H2 + H2O → CH3CHO + 151 KCal
The hydrator is operated at 1.5 to 2.5 atm pressure and 80-100 oC temperature. Acetylene is fed
continuously through the liquid catalyst. The temperature is maintained by steam, it is injected
at the bottom of the column. The hydrator is made of stainless steel or with ferrosilicon. The top
stream of the hydrator is sent to a cooler. All the water vapour is condensed and recycled. The
second cooler takes the outlet from the first one. Acetaldehyde is condensed along with trace of
water. Unreacted acetylene and non-condensable vapour is feed to a water scrubber. The water
scrubber is operated at temperature of 10 oC. Traces of acetaldehyde and water-soluble
compounds are scrubbed down. Remaining gases are used as fuel or recycled to the dehydrator.
18
The liquid catalyst is a solution made of mercury (II) sulphate dispersed in sulphuric acid. As
acetaldehyde is good reducing agent it reduces Hg(II) to Hg(I) and finally reducing Hg(I) to Hg.
2Hg2SO4 + H2O + CH3CHO → Hg2SO4 + H2SO4 + CH3COOH
Hg2SO4 + H2O + CH3CHO → 2Hg + H2SO4 + CH3COOH
Fluidized bed type equipment is used as hydrator. Even zinc oxide, magnesium oxide and iron
oxide are used in place of mercury.
In general, calculations 680 kg of acetylene, 0.1 kg of mercury are consumed to produce one ton
of acetaldehyde. The conversion of this process is about 50-60% per pass. Catalyst is regenerated
through the process.
Flow sheet-5.3 Production of acetaldehyde by liquid phase reaction of acetylene
5.4 From Saturated Hydrocarbons: [15]
Acetaldehyde is formed as a co product in the vapor – phase oxidation of saturated
hydrocarbons, such as butane or mixtures containing butane, with air or, in higher yield, oxygen.
Oxidation of butane yields acetaldehyde, formaldehyde, methanol, acetone, and mixed solvents
as major products; other aldehydes, alcohols, ketones, glycols, acetals, epoxides, and organic
acids are formed in smaller concentrations. This is of historic interest. Unlike the acetylene route,
it has almost no chance to be used as a major process. From synthesis Gas: A rhodium-catalyzed
process capable of converting synthesis gas directly into acetaldehyde in a single step was
reported in 1974 (84-85).
CO + H2  CH3CHO + other products.
19
The process comprises passing synthesis gas over 5% rhodium on SiO2 at 3000C and 2.0 Mpa
(20 atm). The principal co products are acetaldehyde, 24% acetic acid, 20%; and ethanol, 16%.
In the years 1980 and beyond, if there will be a substantial degree of coal gasification, the
interest in the use of synthesis gas as a raw material for acetaldehyde production will increase.
5.5 Specifications, Analytical, and Test Methods: [16]
Commercial acetaldehyde has the following typical specifications: assay, 99% min; color, waterwhite; acidity, 0.5% max (acetic acid); specific gravity, 0.790 at 200C; bp, 20.8 at 101.3 kPa (1
atm). Acetaldehyde is shipped in steel drums and tank cars bearing the ICC red label. IN the
liquid state, it is noncorrosive to most metals; however, it oxidizes readily, particularly in the
vapor state, to acetic acid. Precautions to be observed in the handling of acetaldehyde have been
published by the manufacturing chemists association.
Analytical methods based on many of the reactions common to aldehydes have been developed
for the determination of acetaldehyde. In the absence of other aldehydes, it can be detected by
the formation of a mirror from an alkaline silver nitrate solution (Tollens’ reagent) and by the
reduction of Fehling’s solution.
It can be determined quantitatively by fuchsin-sulfiur dioxide solution (Schiff’s reagent) or by
the reaction with sodium bisulfite, the excess bisulfite being estimated iodometrically.
Acetaldehyde present in mixtures with other carbonyl compounds, organic acids, etc. can be
determined by paper chromatography of 2,4 – dinitrophenylhydrazones polarographic analysis
either of the untreated mixture or of the semicarbazones, the color reaction with thymol blue on
silica gel (detector tube method) mercurimetric oxidation, argent metric titration, microscopic
and spectrophotometric methods, and gas – liquid chromatographic analysis.
With the advent of gas – liquid chromatographic techniques, this method has superseded most
chemical tests for routine analysis. Acetaldehyde can be isolated and identified by the crystalline
compounds of characteristic melting points formed with hydrazines, semicasrbazides, etc.; these
derivatives of aldehydes can be separated by paper and column chromatography.
Acetaldehyde has been separated quantitatively from other carbonyl compounds on an ion
exchange resin in the bisulfite form; the aldehyde is eluted from the column with a solution of
sodium chloride. In larger quantities, it may be isolated by passing the vapor into ether and
saturating the ether with dry ammonia; the product, acetaldehyde – ammonia, crystallizes from
the ether solution. The reactions of acetaldehyde with bisulfite, hydrazine’s, oximes,
semicarbazones, and 5, 5–dimethyl – 1, 3 cyclohexanedione (dimedone) have been used to
isolate acetaldehyde from solutions.
20
CHAPTER-6
SELECTION OF PROCESS
Table- 6.1 Comparison between most likely used method and other method
Parameters
Cost
Conversion
Environmental effect
By
oxidation
ethylene
Cost effective
of By
oxidation
of
ethanol
Comparatively
less
cost effective
35-45%
25%
Ethylene is produced No harmful effect on
in the petrochemical environment
industry and is hence
not classified as a
green product
From acetylene
High cost
50-50%
The production of
acetaldehyde
from
acetylene includes a
catalyst
containing
mercury which is
toxic
So, Oxidation of Ethylene is selected for the production of acetaldehyde because currently, the
Wacker-Hoechst process accounts for 85 % of the worldwide production capacity for
acetaldehyde. Acetaldehyde yield almost equal (about 95%).Lower investment costs in the single
stageprocess, because of the need of only one reactor with conversion per pass: 35 - 45%
This method is technically simple, smooth in reaction, and high in selectivity. The favorable
economics of the process are due to the abundance of ethylene. It is regarded as the most
economic industrial process route, and has been widely used in many countries
In both processes the aqueous crude aldehyde is concentrated and byproducts such as acetic acid
crotonaldehyde and chlorine-containing compounds are removed in a two-step distillation. The
selectivities are almost equal (94%).
other remaining process can not be selected because While passing ethyl alcohol over a copper
or silver gauze catalyst about a 25 percent conversion to acetaldehyde and The production of
acetaldehyde from acetylene includes a catalyst containing mercury, as mercuric complex which
is a toxic material hence this method is discarded
21
CHAPTER-7
MATERIAL & ENERGY BALANCE
7.1 MATERIAL BALANCE
The amount of Acetaldehyde to be produced = 2500 ton/year
Basis: 2500 tons of Acetaldehyde per annum.
Working day=300days
Total acetaldehyde to be produced=2500 TPD
=347.22 kg/hr
=7.89kmol/hr
7.1.1Material Balance across reactor
We haveSelectivity=94%
Conversion=35%
Total weight of Acetaldehyde is to be produced=347.22 kg/hr
Assuming 1.34% of acetaldehyde is lost during production
Total acetaldehyde to be produced=351.56 kg/hr=7.99694kmol/hr
Selectivity = (Moles of desired product formed)/(Moles of reactant reacted)
0.94 = 7.99694 kmol/hr/Moles of C2H4 reacted
Moles of C2H4 reacted=7.99694 kmol/hr/0.94 = 8.5073
Conversion = (Moles of C2H4 reacted)/(Moles of C2H4 fed)
0.35=8.5073/(Moles of C2H4 fed)
Moles of C2H4 fed=8.5073/0.35=24.3 kmol/hr=680.568kg/hr
Moles of C2H4 reacted to produce acetaldehyde=7.99 kmol/hr
Remaining moles = 8.5073-7.99694=0.51036 kmol/hr
Chemical reactions:Main reaction:1.C2H4+1/2O2CH3CHO
Side Reactions:2.C2H4+3O22CO2+2H2O
3. C2H4+ O2CH3COOH
4.2CH3CHOCH3CH=CHCHO
5. C2H4+HClC2H5Cl
6.C2H4+HCl+1/2O2CH3Cl+H2O
From the data we have the moles of 22
Acetic acid=0.0907 kmol/hr=5.4456 kg/hr
Methyl chloride=0.0709 kmol/hr=3.545 kg/hr
Ethyl chloride=0.0549 kmol/hr= 3.5136 kg/hr
Crotonaldehyde=0.05349 kmol/hr =3.7443 kg/hr
From reactions1 mole of C2H4 reacted=2 mol of CO2 produced
=1/2*0.5876 = 0.2398 kmol/hr
1Mole of C2H4 reacted=1Mole of CH3COOH produced
=1*0.09076=0.09076 kmol/hr
1Mole of C2H4 reacted = 1Mole of CH3Cl produced
=1*0.0709 = 0.0709 kmol/hr
1Mole of C2H4 reacted= 1Mole of C2H5Cl produced
=1*0.0549 =0.0549 kmol/hr
Total C2H4 reacted =7.99694+0.2398+0.09076+0.0709+0.0549 = 8.5073
Now, O2 reactedFrom (1) reaction7.99694/2 = 3.99847 kmol/hr
From (2) reaction3/2*0.5876 =0.8814 kmol/hr
From (3) reaction1*0.09076=0.09076 kmol/hr
From (6) reaction1/2*0.0709 =0.03545 kmol/hr
Total O2 reacted= 3.99847+0.8814+0.09076+0.03545 = 5.00608 kmol/hr=160kg/hr
HCl reactedFrom (5) reaction1Mole of HCl reacted = 1Mole of CH3Cl produced
=0.0709 kmol/hr
From (6) reaction
1Mole of HCl reacted = 1Mole of C2H5Cl produced
=0.0549 kmol/hr
Total HCl reacted = 0.0709+0.0549=0.1258 kmol/hr=4.5917 kg/hr
H2O producedFrom (2) reaction= 0.5876 kmol/hr
From (4) reaction= 0.05349 kmol/hr
From (6) reaction= 0.0709 kmol/hr
Total H2O produced = 0.5876+0.05349+0.0709 = 0.71199 kmol/hr=12.81582 kg/hr
From reaction (4)2 moles of Acetaldehyde reacted = 1mole of crotonaldehyde produced
23
= 2*0.05349=0.10698 kmol/hr
Acetaldehyde reacted = 7.99694-0.10698 = 7.88996 kmol/hr=347.15 kg /hr
If 20% excess O2
Then, O2 required in kmol = 160.19*1.20 = 192.228 kg/hr
Moles of air = 192.228/0.21 = 915.37 kg/hr
Moles of N2=915.37*0.79=723.16 kg/hr
O2 unreacted= O2 fed-O2 reacted = 192.228-160.19=32.038 kg/hr
C2H4 unreacted = C2H4 fed-C2H4 reacted=680.568-238.2044 = 442.36 kg/hr
Input to the reactor in kg/hr
C2H4 = 680.568kg/hr
O2 = 192.228 kg/hr
HCl = 4.5917 kg/hr
N2 = 723.16 kg/hr
Total=1600.53
Output from the Reactor
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Water=12.81852 kg/hr
Total =1599.628 kg/hr
Input=Output
24
Outlet
Kg/hr
InletKg/hr
C2H4 =
680.568kg/hr
O2 = 192.228 kg/hr
HCl = 4.5917 kg/hr
N2 = 723.16 kg/hr
REACTOR
Total =1600.53
kg/hr
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Water=12.81852 kg/hr
Total =1599.628
kg/hr
Fig-7.1.1 Material balance around reactor
7.1.2 Material Balance around condenser
Input to the condenser in kg/hr
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Water=12.81852 kg/hr
Total =1599.628 kg/hr
All water is condensed
Condensate= Water=12.81852 kg/hr
Non condensateCH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
25
Crotonaldehyde =3.7443 kg/hr
Total=1587.71 kg/hr
Feed = Condensate+ non condensate
1599.628=12.81852 +1587.71
1599.628=1599.628
Input=Output
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Water=12.81852 kg/hr
Condenser
Non condensateCH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Total=1587.71 kg/hr
Condensate=
Water=12.81852
kg/hr
Fig-7.1.2 Material balance around condenser
7.1.3 Material Balance on Scrubber
Input to the Scrubber in kg/hr
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Total=1586.8
The solubility of Acetaldehyde in water is infinity. So the amount of water
required for the absorption of Acetaldehyde is the equal amount of water.
Water used for absorption = 347.15*1.10 = 381.865 kg/hr
(10 % of extra water is used to scrub all the EO produced.)
Total Acetaldehyde scrubbed = 347.15 Kg/ hr
Solubility data:
Component Solubility (Kgs/ Kgs of water)
Nitrogen- 1.3462 X 10^-5
26
Carbon dioxide -1.379 X 10^-3
Oxygen- 2.87 X 10^ -5
Ethylene -1.482 X 10^-2
CH3COOH -1.42*10^-2
CH3Cl- 9.28*10^-3
C2H5Cl- 9*10^-3
Crotonaldehyde-9.8*10^-3
CO2 absorbed = (1.379*10^-3)*(381.865) = 0.52659 kg/hr
C2H4 absorbed = (1.482*10^-2)*(381.865) = 5.6592 kg/hr
CH3COOH absorbed = (1.42*10^-2)*(381.865) = 5.4456 kg/hr
CH3Cl absorbed = (9.28*10^-3)*(381.865) = 3.545 kg/hr
C2H5Cl absorbed =( 9*10^-3) *(381.865)= 3.5136 kg/hr
Crotonaldehyde absorbed = (9.8*10^-3)*(381.865)=3.7443 kg/hr
C2H4 recycle = 442.36-5.65592=436.70 kg/hr
O2 recycle =32.038 kg/hr
N2 purged=723.16 kg/hr
CO2 purged=25.32781
Water out=381.856 kg/hr
Input to the Scrubber in kg/hr
CH3CHO=347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443 kg/hr
Water in=381.856 kg/hr
Total=1968.668 kg/hr
Output from the Scrubber
Acetaldehyde absorbed=347,15 kg/hr
CO2 absorbed = 0.52659 kg/hr
C2H4 absorbed = 5.6592 kg/hr
CH3COOH absorbed = 5.4456 kg/hr
CH3Cl absorbed = 3.545 kg/hr
C2H5Cl absorbed = 3.5136 kg/hr
Crotonaldehyde absorbed = 3.7443 kg/hr
C2H4 recycle = 442.36-5.65592=436.70 kg/hr
O2 recycle =32.038 kg/hr
N2 purged=723.16 kg/hr
CO2 purged=25.32781
Water out=381.856 kg/hr
Total=1968.668 kg/hr
Input = Output
27
C2H4 recycle = 436.70 kg/hr
O2 recycle =32.038 kg/hr
N2 purged=723.16 kg/hr
CO2 purged=25.32781
Outlet
Kg/hr
InletKg/hr
SCRUBBER
CH3CHO =347.15 kg/hr
O2 unreacted=32.038 kg/hr
C2H4 unreacted= 442.36 kg/hr
Acetic acid =5.4456 kg/hr
Methyl chloride =3.545 kg/hr
Ethyl chloride= 3.5136 kg/hr
Crotonaldehyde =3.7443
kg/hr
Water in=381.856 kg/hr
Acetaldehyde absorbed=347,15 kg/hr
CO2 absorbed = 0.52659 kg/hr
C2H4 absorbed = 5.6592 kg/hr
CH3COOH absorbed = 5.4456 kg/hr
CH3Cl absorbed = 3.545 kg/hr
C2H5Cl absorbed = 3.5136 kg/hr
Crotonaldehyde absorbed = 3.7443
kg/hr
Total=1968.668 kg/hr
Total=1968.668
kg/hr
Fig-7.1.3 Material balance around Scrubber
7.1.4Material Balance on Distillation Column
Input to the Distillation Column in kg/hr
Acetaldehyde =347.15 kg/hr
CO2 = 0.52659 kg/hr
C2H4 = 5.6592 kg/hr
CH3COOH = 5.4456 kg/hr
CH3Cl = 3.545 kg/hr
C2H5Cl = 3.5136 kg/hr
Crotonaldehyde = 3.7443 kg/hr
Water =381.856 kg/hr
Total Feed = 751.44 kg/hr
Overhead contain:C2H5Cl=3.5136 kg/hr
C2H5Cl = 3.5136 kg/hr
CO2 = 0.52659 kg/hr
C2H4 = 5.6592 kg/hr
Total Overhead=13.24439 kg/hr
Bottom Contain
CH3COOH = 5.4456 kg/hr
28
Crotonaldehyde = 3.7443 kg/hr
Water =381.856 kg/hr
Acetaldehyde =347.15 kg/hr
Total bottom=738.19 kg/hr
Feed=Overhead+Bottom
751.44 kg/hr =13.24439+738.19
751.44 kg/h = 751.44 kg/h
Input = Output
C2H5Cl=3.5136 kg/hr
CH3Cl = 3.545 kg/hr
CO2 = 0.52659 kg/hr
C2H4 = 5.6592 kg/hr
Total=13.24439 kg/hr
Inlet-Kg/hr
Acetaldehyde =347.15 kg/hr
CO2 = 0.52659 kg/hr
C2H4 = 5.6592 kg/hr
CH3COOH = 5.4456 kg/hr
CH3Cl = 3.545 kg/hr
C2H5Cl = 3.5136 kg/hr
Crotonaldehyde = 3.7443
kg/hr
Water =381.856 kg/hr
Outlet
Kg/hr
DISTILLATION
COLUMN
TOTAL= 751.44 kg/hr
CH3COOH = 5.4456 kg/hr
Crotonaldehyde = 3.7443 kg/hr
Water =381.856 kg/hr
Acetaldehyde=347.15 kg/hr
Total=738.19 kg/hr
Fig-7.1.4 Material balance around Distillation column
7.1.5Material Balance around Distillation Column
Input to the Distillation Column in kg/hr
Acetaldehyde =347.15 kg/hr=7.8897 kmol/hr
CH3COOH = 5.4456 kg/hr = 0.09076 kmol/hr
Crotonaldehyde = 3.7443 kg/hr = 0.05349
Water =381.856 kg/hr = 21.21 kmol/hr
Total Feed=738.19 kg/hr=29.24 kmol/hr
For DistillateDistillate contain CH3CHO (99.88%),CH3COOH (0.1%),H2O
Distiilate347.15*0.9988 = 346.7 kg/hr=7.879 kmol/hr
346.7*(0.02/100) = 0.069 kg/hr = 3.83*10^-3 kmol/hr
346.7*(0.1/100) = 5.76*10^-3 kmol/hr
Total distillate=347.115 kg/hr = 7.8885 kmol/hr
F=D+W
29
W=F-D
W=29.24-7.8885 = 21.35 kmol/hr=391.075 kg/hr
FXf = DXd+WXw
xF = mole fraction for Acetaldehyde in feed
xF=7.8897/29.24=0.2698
xD = mole fraction of ethylene oxide in the distillate.(commercial grade
Acetaldehyde)
xD =0.9988
29.24*0.2698=7.8885*0.9988+21.35*Xw
Xw=4.64*10^-4
Acetaldehyde = 346.7 kg/hr
Water= 0.069 kg/hr
Acetic acid =0.346 kg/hr
Total distillate=347.115 kg/hr = 7.8885 kmol/hr
Inlet-Kg/hr
Outlet
Kg/hr
Total=738.19 kg/hr
CH3COOH = 5.4456 kg/hr
Crotonaldehyde = 3.7443
kg/hr
Water =381.856 kg/hr
Acetaldehyde=347.15
kg/hr
DISTILLATION
COLUMN
Crotonaldehyde =
3.7443 kg/hr
Total=738.19 kg/hr
CH3COOH = 5.4456 kg/hr
Water =381.856 kg/hr
Fig-7.1.5 Material balance around distillation column
30
7.2ENERGY BALANCE:
7.2.1Energy balance around reactor
Empirical heat capacity equation
C=a+bT+cT2+dT3;
C= heat capacity in J/Mole*K
T= absolute temp in K
S.No. COMPONENT A
B
C
D
15.69*10^-2
-8.318*10^-5
17.55*10^-9
1.
Ethylene
3.806
2.
Oxygen
28.106 -3.68*10^-6
17.459*10^-6 -1.06*10^-8
3.
Carbon Dioxide
19.795 71.43*10^-3
-5.602*10^-5
17.153*10^-9
4.
Methyl Chloride 13.875 10.140*10^-2 -3.889*10^-5
25.66*10^-10
5.
Acetaldehyde
7.716
18.22*10^-2
-1.007*10^-4
23.80*10^-9
6.
Ethyl Chloride
-.553
26.06*10^-2
-1.840*10^-4
55.475*10^-9
7.
Nitrogen
31.150 -1.357*10^-2
26.796*10^-6 1.168*10^-8
8.
Acetic Acid
4.840
-1.756*10^-4
49.48*10^-9
9.
Water
32.243 19.23*10^-4
10.55*10^-6
-3.59*10^-9
25.48*10^-2
Q= -HR+Hp+∆HR
H=m*CP*∆t
Consider feed to enter at 25oC
Tref =25oC
(m*Cp*∆T)reactants = 0
Heat capacity data for product and unreacted components at 400 K
Component
Cp*dT
J/Mole*K
6118.352
5010.481
Acetaldehyde
Unreacted
31
;
Ethylene
Unreacted
Oxygen
Nitrogen
Acetic acid
Methyl Chloride
Ethyl chloride
Carbon Dioxide
Water
3037.96
3081.16
7589.8
4549.7
7192.09
6479.6
3473.3
(m*Cp*dT)products = (6118.352*7.889*10^3) + (5010.48*15.7985*10^3) + (1.001*10^3*3037.96)
+ (0.5876*10^3*6479.6) + (0.09076*10^3*7589.8) + (25.827*10^3*3081.16) +
(0.0709*10^3*4549.7) + (0.0549*10^3*7192.09) + (0.7119*10^3*3473.3)
(m*Cp*dT)products = 2.35*10^8 J/hr = 65.27 KW
∆HR = -57.84 Kcal./Kmole = 571.87 KW
Q= -HR+Hp+∆HR = 0 - 571.87 + 65.27 = -506.53 KW
Q = (m*Cp*∆T)water ; ∆T = 35oC-25oC = 10oC
m = 506.53/4.184*10 = 12.106 Kg
7.2.2 Energy Balance of Condenser
Heat capacity data for product and unreacted components
Component
Acetaldehyde
Unreacted
Ethylene
Unreacted
Oxygen
Nitrogen
Acetic acid
Methyl Chloride
Ethyl chloride
Carbon Dioxide
Water
(m*Cp*∆T)noncondensate
(1.001*10^3*1410.47)
=
+
Cp
*dT;
J/Mole*K
2974.9
2442.602
1410.47
1477.31
3691.37
2139.47
3497.6
1863.82
1610.78
(2974.3*7.889*10^3)
+
(2442.602*15.7985*10^3)
(0.5876*10^3*1863.82)
+
(0.09076*10^3*3691.37)
32
+
+
(25.827*10^3*1477.31)
(0.7119*10^3*1610.78)
+
(0.0709*10^3*2193.47)
+
(0.0549*10^3*3497.6)
+
(m*Cp*dT)products =1.028*10^8 J/hr. = 28.57 KW
Heat given out by water which is condensate
Q=(m*Cp*T)Water = (12.81852*4184*50)
Q = 2681634.384J/hr= 0.744 KW
Therefore heat removed in the condenser = 28.57+0.744 = 29.314 KW
Utility require
Q = m*Cp*∆T where ∆T=10oC
29.314 = m*4.814*10
M=0.60 kg/s
7.2.3 Energy Balance around Heat Exchanger
Heat capacity data for product and unreacted components:
Component
Acetaldehyde
Unreacted
Ethylene
Unreacted
Oxygen
Nitrogen
Acetic acid
Methyl Chloride
Ethyl chloride
Carbon Dioxide
Cp
J/Mole*K
2873.38
2344.7
;
1482.42
1500.12
3563.71
2151.65
3352.95
1889.72
(m*Cp*∆T)products = (2873.38*7.889*10^3) + (2344.7*15.7985*10^3) + (1.001*10^3*1480.42) +
(0.5876*10^3*1889.72)
+
(0.09076*10^3*3563.71)
+
(25.827*10^3*1500.12)
+
(0.0709*10^3*2151.65) + (0.0549*10^3*3352.95)
(m*Cp*∆T)products =1.01*10^8 J/hr. = 28.2 KW
Heat entering = 29.314 KW
Therefore heat removed in heat exchanger = 29.314-28.2=1.114KW
7.2.4 Energy Balance around Absorber
33
In the absorber acetaldehyde, acetic acid, methyl chloride, and ethyl chloride are completely
absorbed in water at 25 degree C. The only energy lost is from gases which are not absorbed in
the absorbing liquid.
Heat entering in the absorber = 1.114 KW
Heat capacity data for recycled and purged streams at 25 degree C
Component
Cp
J/Mole*K
183.332
219.46
Carbon Dioxide
Unreacted
Ethylene
Unreacted
Oxygen
Nitrogen
;
146.96
148.72
Energy lost from the absorber is = (0.5756*10^3*183.332) + (15.53*10^3*219.46) +
(1.001*10^3*146.96) + (25.827*10^3*148.72)
= 7.51*10^6 J/hr. = 2.086 KW
Therefore, energy leaving the absorber with the products= 1.114 KW-2.086 KW=-0.972KW
34
Energy balance around Distillation column
Antoine equation[22]
1. P=(A−(B/(T+C))
2. P=vapor pressure(mmHg)
o
3. T = temperature( C)
TABLE-8
component
Acetaldehyde
Acetic acid
Water
A
8.00552
7.18807
8.10765
B
1600.017
1416.7
1750.286
Crotonaldehyde
7.28193
1460.08
C
291.809
225
235
227.632
Dew point –
For dew point calculation
[(Yacetaldehyde*760)/p*acetaldehyde]+ [(Yacetic acid*760)/p*acetic acid]+ [(Ywater*760)/p*water]-1=0
Yacetaldehyde=0.998
Yacetic acid =7.30*10^-4
Ywater=4.85*10^-4
And calculate ( p*components) at different temperature
And then check [Xacetaldehyde+Xacetic acid+Xwater]=1
By trial and error method we got dew point at 21.45o C (294.45K)
Bubble point calculation
(X acetic acid*p acetic acid) +(X water*p water)+ [(X crotonaldehyde * p crotonaldehyde)+]-760mmHg = 0
X acetic acid = 3.98*10^-3
X water = 0.993
X crotonaldehyde =2.507*10^-3
And calculate ( p*components) at different temperature
And then check [Y acetaldehyde +Y acetic acid +Y water]=1
By trial and error method we got bubble point at 99.89 o C (372.89K)
Latent Heat of Vaporization of Acetaldehyde at dew pt. (294.45)=566.04 KJ/kg =24.90 J/mol
Latent Heat of Vaporization of Acetic acid at dew pt. (294.45) =467.38KJ/kg=28.04 J/mol
Latent Heat of Vaporization of Water at dew pt. (294.45)=2485.15KJ/kg = 44.73 J/mol
Molar flow rate of Acetaldehyde=7.8897Kmol/hr
Molar flow rate of Acetic acid =0.09076 Kmol/hr
Molar flow rate of crotonaldehyde= 0.05349 Kmol/hr
Molar flow rate of water =21.21 Kmol/hr
Total feed=29.24 Kmol/hr
35
Molar flow rate of Acetaldehyde=7.879Kmol/hr
Molar flow rate of Acetic acid =5.76*10^-3Kmol/hr
Molar flow rate of water = 3.83*10^-3 Kmol/hr
Total Distillate =7.8885 Kmol/hr
HG= [L+ (Cp*dT)]acetaldehyde+[ L+(Cp*dT)]acetic acid+[m*L+(m*Cp*dT)]water
(Cp*dT)acetaldehyde=7.716*(294.45-283)+(18.22*10^-2/2)*(294.45^2-283^2)4)/3*(294.45^3-283^3)+(23.80*10^-9/4)*(294.45^4-283^4)
Cp*dT= 607.18 J/mol
(1.007*10^-
(Cp*dT)acetic
=
4.840*(294.45-283)+25.48*10^-2/2*(294.45^2-283^2)-1.756*10^acid
4/3*(294.45^3-283^3)+49.48*10^-9/4*(294.45^4-283^4) = 743.76.98 J/mol
(Cp*dT)water
Cp*dt=32.243*(294.45-283)+(19.23*10^-4/2)*(294.45^2-283^2)+(10.55*10^-6)/3*(294.45^3283^3)+(3.59*10^-9/4)*(294.45-283)=386.59 J/mol
Qc= Yacetaldehyde [L+ (Cp*dT)]acetaldehyde+ Yacetic acid [ L+(Cp*dT)]acetic acid+ Ywater [L+(Cp*dT)]water
HG=0.998[24.90+607.18]+ 7.30*10^-4[28.04+743.76]+ 4.85*10^-4[44.73+386.59]
HG = 631.58 J/mol
HD= (Cp*dT) Acetaldehyde+( Cp*dT) Acetic acid (Cp*dT)water
For acetaldehyde
Cp*dT=7.716*(293.45-283)+(18.22*10^-2/2)*(293.45^2-283^2)283^3)+23.80*10^-9*(293.45^4-283^4) = 547.93
(1.007*10^-4)/3*(293.45^3-
For acetic acid
Cp*dT=4.840*(293.45-283)+25.48*10^-2/2*(293.45^2-283^2)-1.756*10^-4/3*(293.45^3283^3)+49.48*10^-9/4*(293.45^4-283^4)
Cp*dT =677.95
For Water
(Cp*dT)water
Cp*dt=32.243*(293.45-283)+(19.23*10^-4/2)*(293.45^2-283^2)+(10.55*10^-6)/3*(293.45^3283^3)+(3.59*10^-9/4)*(293.45-283)=352.78 J/mol
HD=[547.93+677.95+352.78] = 1578.66 J/hr =HL0
Reflux ratio assumed = 3.5
Lo/D = 3.5
Lo = 27.60 Kmol/hr
V=Lo+D = 35.49 Kmol/hr
Qc= V*HG - D*HD - L*HL0
36
Qc= 35.49*10^3*631.58 -7.8885*10^3*1578.66-27.60*10^3*1578.66 = -33609501.21 J/hr =
-9.39 KW
Reboiler duty
Hw= ( m * Cp*dT) Acetic acid (m*Cp*∆T)water+(m*Cp*dT)crotonaldehyd
Qacetic acid = 0.085*10^3*[4.840*(372.89-283)+25.48*10^-2/2*(372.89^2-283^2)-1.756*10^4/3*(372.89^3-283^3)+49.48*10^-9/4*(372.89^4-283^4)]
Qacetic acid = 6397.8 J/hr = 1.7^10^-3 KW
Qcrotonaldehyde = 0.05349*10^3*148.6*(372.89-283) = 714500.9 J/hr= 0.198 KW
Qwater
(Cp*dT)water
Cp*dt=32.243*(372..89-283)+(19.23*10^-4/2)*(372.89^2-283^2)+(10.55*10^-6)/3*(372.89^3283^3)+(3.59*10^-9/4)*(372.89-283)=1069.17 J/mol
Qwater = 21.20*10^3*1069.17 = 22666521.17 = 6.29 KW
Hw= 6.49KW
Qb = W*Hw+DHD+Qc-FHF
HF = 52946.49 J/hr
QB= 21.35*10^3*23387419.8+7.8885*10^3*1578.66-33609501.21-29.24*10^3*52946.49
QB=5.08*10^11 J/hr = 1.39*10^5 KW
37
7.3 Control Strategy
Fig-7.4 Control strategy of Distillation column
Discription:A Process control system consists:•Process
•Measuring element
•Controller
•Final Control Element
In a process control system controlling is done by•Level Control
•Pressure Control
•Temperature Control
•Flow Control Element
38
7.3.1 Temperature Controller
It is desired to maintain the temperature by means of the controller. If the measured temperature
differs from the desired temperature, the controller senses the difference or error and changes the
flow of Jacketed water.
7.3.2 Pressure controller
Pressure in the reactor is maintained by means of controller. If pressure in the reactor is
increased then the reactor stream is purge out to blow down vessel.
7.3.3 Flow controller
A flow controller is a device used to measure and control the flow of fluids and gases. A mass
flow controller is designed and calibrated to control a specific type of fluid or gas at a particular
range of flow rates. The FC can be given a set point from 0 to 100% of its full scale range but is
typically operated in the 10 to 90% of full scale where the best accuracy is achieved. The device
will then control the rate of flow to the given set point. FCs can be either analog or digital a
digital flow controller is usually able to control more than one type of fluid or gas whereas an
analog controller is limited to the fluid (or gas) for which it was calibrated.
7.3.4 Level controller: Level in the tank or the reservoir is maintained by means of controllers.
If level in the tank of reservoir is increased or decreased the effluent is added or drained out
automatically using the level control elements etc
39
CHAPTER 8
DETAILED EQUIPMENT DESIGN
8.1 - Process Design of Reactor
Operating conditionRector temperature -130oc
Pressure - 400kpa = 4 atm
C2H4 + ½ O2  CH3CHO
∆H = -244 kJ(-57.84 kcal/kmol)
Working volume of reactor
Bubble column reactor can be assumed as ideal mixed flow reactor
Conversion – 35%
zero order reaction
Rate constant, k – 2.77*10^-5 s-1
.Performance Equation:
V/FAo= XA /-rA
V/FAo= XA /k
Molar flow rate of ethylene at inlet
FAo = 24.306 kmol/hr = 680.568 kg/hr
Density of ethylene at 130 oc =567.92 kg/m^3
V = FAo*XA/k = 680.568*0.35/(2.77*10^-3*3600*567.92)
V=4.206 m3
For superficial velocity of gas
Let Sg =1cm/s =0.01m/s
Mass flow rate of oxyzen at inlet
mo2=192.228 kg/hr
ρo2 = P*M/R*T = 4*32/(273+130)*0.08314 =3.82 kg/m3
Volumatric flow rate of oxygen Qv = 192.228/3.82 = 50.32 m3/hr = 0.0139m3/s
π/4*Di2 = Qv/Sg = 0.0139/0.01
Di=1.33 m
Let hL=Height of liquid during rection
V= π/4*Di2*hL
4.206 = π/4*(1.33)2*hL
hL=4 m
8.1.1 Mechanical Design of Continues Stirred Tank Reactor
Vessel shell internal diameter =1330 mm
Jacket internal dia=1660 mm
Jacket length=1700 mm
Thickness of the shell
40
a ) Internal Pressure
t= PDi /(2fj-P)+C
Working Pressure=0.4 N/mm2
Design Pressure=10% more than the maximum working pressure
So, P=0.44N/mm2
Joint efficiency, J=0.85
f=98N/mm2
C=Corrosion allowance=1.5mm
Di=1.33m=1330mm
t=3.52+C
t=5mm
External pressure
External design pressure = 1.1x.35= 0.385 N/mm2
Outside diameter of the shell, D0=Di+2*t= 1338mm
Crtical buckling pressure Pc= (2.42*E*(t/Do)^2.5)/((1-meu^2)^.75)*(L/Do-.45*(t/Do)^.5)
Where t = thickness calculated above without corrosion allowance = 3.52
L=effective jacket length=jacket length +1/3 dished end length 1700+60(st. portion) + 1/3 *360
L=1900 mm
Do= External dia=Di+2t=1338
Meu= poisons ratio=0.3
E=modulus of elasticity= 190*10^3 N/mm2
Pc=0.155 N/mm2
Critical stress= Pc*Do/2t= 29.45N/mm2=fc
Fa=fc/4= 7.36 N/mm2
Which is far less than the given allowable stress i.e. 98N/mm2
The other approach is to have an allowable pressure Pa=Pc/4=0.38 N/mm^2, Which is far less
than the design pressure i.e Pi= .385n/mm^2
It is therefore concluded that computed thickness 3.4 is acceptable based on external pressure
hence let’s try thickness t=16 mm for which Pc=2N/mm^2
Therefore Pa=.5n/mm^2
So the design pressure 0.385N/mm2 is less than allowable pressure 0.5N/mm2
Therefore thickness of 16mm is acceptable based on external pressure
Thickness of Jacket:
tj =[PDi /(2fj –P)] + C
Here P = 0.385N/mm2
Di = 1660 mm
f = 98N/mm2
j = 0.85
C = 1.5
Hence, tj = 6 mm
Head Thickness:
Crown Radius (Rc) = Di (where Di =1330 mm)
Knuckle Radius (R1) = 0.06 Di
R1 = 80 mm
There is no external pressure acting on the top dished end.
i.)
Top head (Internal pressure only)
41
Stress intensification factor, W is given by;
W = [3 + (Rc /R1)0.5]/4
W = 1.77
Thickness of Top Head (th ) =[(Pi×Rc ×W)/(2×f×j)] + C
th = 8mm
Bottom dished end ( Torispherical)
As the rule of thumb in section 5.8.2.2 item(ii) Torispherical head we use the design pressure
a.) Pi = 1.67*0.385=0.643 n/mm2
th=0.643*1330*1.77/2*98*.85+C=9.08+C=11mm
(b) by considering the buckling pressure 2 times the design external pressure we calculate
Th=a*RC*(3*(1-µ2)1/4)*(0.385/2*190*103)0.5=8mm
Therefore plate thickness 11mm is adequate
8.2-Process design of sieve tray distillation column
Feed (at bubble point) Temperature =55.45oc
Top Temperature (from Dew point calculation) = 21.45 oc
Bottom temperature (from bubble point calculation) = 99.89 oc
Feed Components in kmol/hrAcetaldehyde-7.8897
Acetic acid-0.09076
Crotonaldehyde-0.05349
Water-21.21
Total Feed=29.24 kmol/hr
Distillate Components in kmol/hrAcetaldehyde-7.879
Acetic acid-5.76*10^-3
Crotonaldehyde-4.95*10^-4
Water-3.83*10^-3
Total Distillate = 7.889 kmol/hr
Bottom Components in kmol/hrAcetaldehyde-0.0107
Acetic acid-0.085
Crotonaldehyde-0.052995
Water-21.2
Total Bottom = 21.33 kmol/hr
Component
Acetaldehyde
Feed(Xf)
0.269
Composition, mole %
Distillate(Xd)
Bottom (Xb)
0.998
5.016*10^-4
42
Acetic acid
Crotonaldehyde
water
3.10*10^-3
1.82*10^-3
0.72
7.3*10^-4
4.85*10^-4
6.274*10^-5
3.98*10^-3
2.507*10^-3
0.993
Antoine equation
4. P=(A−(B/(T+C))
5. P=vapor pressure(mmHg)
o
6. T = temperature( C)
TABLE-8.2.1
Component
Acetaldehyde
Acetic acid
Water
A
8.00552
7.18807
8.10765
B
1600.017
1416.7
1750.286
7.28193
Crotonaldehyde
C
291.809
225
235
1460.08
227.632
TABLE 8.2.2 – Vapour pressure in mm Hg
Top temp. at 21.45oc
790.44
135.6
26.30
19.16
Component
Acetaldehyde
Acetic acid
Crotonaldehyde
Water
Bottom temperature at 99.89oc
8331.19
3312.4
666.76
760.67
Heavy key component= water
Light key component= Acetaldehyde
Rrlative Volatility calculation- α =PAV/PBV
TABLE-8.1.3
Components
Acetaldehyde (LK)
Acetic acid
Crotonaldehyde
Water (HK)
αtop
41.25
7.077
1.37
1
αbottom
10.95
4.35
0.87
1
43
αav
21.25
5.54
1.09
1
Using Fenskey ‘ s equation to find minimum number of theoretical stages
Nm = log [(XLK /XHK)d/ (XHK /XLK)b]/logαLk
Nm = Minimum no. of trays,
α Lk = 21.25 (Avg relative volatility with respect to heavy key
(XHK)d = mole fraction of heavy key component in distillate = 4.85*10^-4
(XLK)d= mole fraction of light key component in distillate = 0.998
(XLK)b=mole fraction of light key component in bottom = 5.016*10-3
(XHK)b = mole fraction of heavy key component in bottom = 0.993
Nm = log[(0.998/4.85*10-3)*(0.993/5.016*10-3)]/log (21.25) = 4.97 =5
Underwood ‘s method
Σ(αi*Xif)/( αi- ) = 1-q
As feed is entering as saturated liquid so, q=1
(0.269*21.25)/(21.25-)+(3.10*10^-3*5.5)/(5.5-)+(1.82*10^-3*1.09)/(1.09-)+(0.72*1)/(1-) =
1-1 = 0
By trial,  = 3.25
Σ(αi*Xid)/( αi- ) = Rm+1
On putting ’ s value
(21.25*0.998)/(21.25-3.25)+(7.3*10^-4*5.5)/(5.5-3.25)+(4.84*10^-4*1)/(1-3.25)+ (6.274*10^5*1.09)/(1.09-3.25) = Rm+1
Rm=0.179
Gillilands Co-relation:- f(N) = N – Nm /N +1 = 1 – exp[(1+54.4 )/(11+117.2Ψ)])[(Ψ-1)/ Ψ*0.5)]
Ψ= (Rm)/(R+1)
R=3 for which N = 6
Let Tray efficiency = 0.5
Actual No. of Trays = 6/0.5 = 12
Tower diameter required at top
Operating pressure at top of column = 1 atm = 101.325 kpa
Molar flow rate of vapour and liquid at top in enriching section
L=R*D = 3*7.889 = 23.66 kmol/hr
V = (R+1)*D = 4*7.889 = 31.556 kmol/hr
L/V = Lw/Vw = 23.66/31.556 = 0.749
Mavg =ΣXiMi =0.998*44+7.3*10^-4*60+4.85*10^-4*18+6.27*10^-5*70 = 43.96
T = 21.45 0C(dew point)
ρ
v = PMavg/RT = (1*43.96)/(0.08312*294.45) = 1.818 kg/m3
Density of liquid at top
Density of acetaldehyde at 21.45 0C = 783 kg/m3
Density of acetic acid 21.45 0C = 1049 kg/m3
Density of crotonaldehyde at 21.45 0C = 851 kg/m3
Density of water at 21.45 0C = 998 kg/m3
1/ ΣWi/ρi = 1/(0.998*783)+(9.96*10^-4)/1049+(1.98*10^-4/998)+(9.9*10^-5/851)
= 784.15 kg/m3
FLv = Lw /Vw*(ρV/ ρL)^0.5= 0.036
44
Assuming tray spacing = 0.3m From the fig 8.16 page no-444 (Bhatt and Thakore),
Cf = 0.052
Vf =Flooding velocity
Vf = (Cf )*(σ/0.02)^0.2* ((ρL–ρV)/ ρV)0.5
Surface tension of acetic acid at 21.45 0C
σAA1/4 = [p]*( ρ’L- ρ’v)
ρ’
L = 1049*10^-3/60 = 0.0174 mol/cm3
ρ’
v = PM/RT = 4.13*10^-5 mol/cm3
[p]AA = 129
σAA =25.14 dyn/cm = 25.14*10^-3 N/m
similarly, σacetaldehyde=21.2*10^-3 N/m
σcrotonaldehyde =23*10^-3 N/m
σwater = 58*10^-3 N/m
σ = Σ σi*Xi =(0.998*21.2*10^-3+(7.3*10^-4*25.14*10^-3+(58*10^-3*4.85*10^-4+6.27*10^5*23*10^03) = 0.0212 N/m
after putting all value, we get
Vf = 1.09m/s
Actual velocity = 0.85* Vf
V=0.927 m/s
Volumetric flow rate of vapour at the top
Qv= (V *Mav)/(ρV) = (31.556*43.9)/(1.818*3600) = 0.2119m3/sec
An=Net area required at the top
An= Qv / V = 0.2119/0.927 = 0.228 m2
Let down comer area Ad = 0.12 Ac
An= Ac – Ad = Ac – 0.12 Ac = 0.88 Ac
Ac= inside cross sectional area of tower
0.88 Ac = 0.228
Ac = 0.259 m2
inside diameter of column required at the top Di = 0.57 m
Tower diameter required at bottom
Operating pressure at the base of column = operating pressure at top + ∆Pt
Where, ∆Pt
= Total pressure drop in sieve tray tower
Ht = 120 mm WC
∆Pt = Actual no. of trays *ρ*g*Ht =12*1000*9.81*120*10^-3 = 14.112 kpa
Operating pressure at the base =Pt+∆Pt = 101.325+14.112 = 115.437kpa = 1.13 atm
Molar flow rate of vapour and liquid at bottom in stripping section
L’ =L+F*q = 23.66+29.24 = 52.9 kmol/hr
V’ =F(q-1)+V = 31.566 kmol/hr
At base,
L’/V’ = 52.9/31.566 = 1.67
Mavg =ΣXiMi =5.016*10^-4*44+3.98*10^-3*60+0.993*18+2.507*10^-3*70 = 18.310
45
T = 99.89 0C(bubble point)
ρ
v = PMavg/RT = (1.13*18.310)/(0.08314*372.89) = 0.681 kg/m3
L=958 kg/m3
ρ
FLv = Lw /Vw*(ρV/ ρL)^0.5= 0.044
Assuming tray spacing = 0.3m From the fig 8.16 page no-444 (Bhatt and Thakore),
Cf = 0.051
Vf =Flooding velocity
Vf = (Cf )*(σ/0.02)^0.2* ((ρL–ρV)/ ρV)0.5
σ = Σ σi*Xi = 0.05759 N/m
after putting all value, we get
Vf = 0.215
Actual velocity = 0.85* Vf
V=0.18275 m/s
Volumetric flow rate of vapour at the top
Qv= (V *Mav)/(ρV) = (31.556*18.310)/(0.681*3600) = 0.235m3/sec
An=Net area required at the top
An= Qv / V = 0.235/0.18275 = 1.28 m2
Let down comer area Ad = 0.12 Ac
An= Ac – Ad = Ac – 0.12 Ac = 0.88 Ac
Ac= inside cross sectional area of tower
0.88 Ac = 1.28
Ac = 1.46 m2
inside diameter of column required at the top Di = 1.36 m
at the top Volumetric flow of liquids QL= L/ ρ L= 23.66*43.96/784.15 = 1.326 m3/sec
at the top Volumetric flow of liquids QL= L/ ρ L= 52.9*18.310/958 = 1.011 m3/sec
Check for weeping,
Minimum velocity of vapours through holes to avoid the weeping is given by
Vhmin= K – 0.9*(25.4 - dh)/ ρv^0.5
Vhmin=Minimum velocity of vapours through holes
K = constant can be obtained from fig 8.19
AssumeWeir height hw= 50 mm(for both section)
Hole diameter dh= 5 mm(for both section)
Plate thickness t = 5 mm(for both section)
For enriching sectionHeight of liquid crest over the weir
how= 750*(Lm / (ρL*lw))^2/3
Lm= (0.7) *L *Mav= 0.7*23.66*43.96 = 738.06 kg/hr = 0.20 kg/s
(minimum)ρL= 784.15 kg/m3
From table 8.34 page no-449 (Bhatt and Thakore) [54]For Ad/ Ac= 0.12 , lw /Di = 0.775
46
lw= length of weir = 0.775*0.57= 0.44175 m
Minimum how= 750*(0.20/(784.15*0.44175))^(2/3) = 5.2mm
At minimum rate
hw+ how= 50+5.2 = 55.2 mm
From fig 8.19 page no-449 , k = 30.2
Vhmin= 30.2 – 0.9*(25.4 - 5)/(1.818).5= 8.78 m/s
Vha =0.7*Qv/Ah
Vha= Actual vapour velocity through holes at minimum vapour flow rate
,Ah= hole area = 8% of Aa
Aa= actual area = Ac-2*Ad
Ad= downcomer area=0.12*Ac
Aa=Ac-2*Ad
Aa=(0.245)-(2*0.12*0.245) m2
Aa=0.1952 m2
Ah=8 % of Aa=0.0156m2
Vha= (0.7*0.2119)/0.0156 = 10.02 m/s
Vha> Vmin
Thus in the top minimum operating rate is well above weep point Vha> Vmin
For stripping sectionHeight of liquid crest over the weir
how= 750*(Lm / (ρL*lw))^2/3
Lm= (0.7) *L *Mav= 0.7*52.9*18.310 = 678.019 kg/hr = 0.18 kg/s
(minimum)ρL= 958 kg/m3
From table 8.34 page no-449 (Bhatt and Thakore) [54]For Ad/ Ac= 0.12 , lw /Di = 0.715
lw= length of weir = 0.715*1.36= 0.9724 m
Minimum how= 750*(0.20/(784.15*0.44175))^(2/3) = 5.2mm
At minimum rate
hw+ how= 50+5.2 = 55.2 mm
From fig 8.19 page no-449 , k = 30.2
Vhmin= 30.2 – 0.9*(25.4 - 5)/(1.011).5= 11.77 m/s
Vha =0.7*Qv/Ah
Vha= Actual vapour velocity through holes at minimum vapour flow rate
,Ah= hole area = 8% of Aa
Aa= actual area = Ac-2*Ad
Ad= downcomer area=0.12*Ac
Aa=Ac-2*Ad
Aa=(1.36)-(2*0.12*1.46) m2
Aa=1.012 m2
Ah=8 % of Aa=0.08096m2
Vha= (0.7*1.011/0.08096= 12.48 m/s
Vha> Vmin
Thus in the bottom, also minimum operating rate is well above weep point
Tray pressure drop for enriching section:47
Dry plate pressure drop
hd= 51*( Vh /C0)^2 *(ρ V/ ρL)
Vh=Maximum velocity of vapors through hole
Vh= Q V/A h (maximum)
Vh = 0.2119/0.0158 = 14.3
ρV= 1.818 kg/m3 ,
ρL= 784.15 kg/m3
From fig 8.20 pg no-450 ( Bhatt and Thakore)
For, plate thickness/ hole diameter = 1
Ah/ Ap= Ah /Aa=(0.0156 /0.1952) = 0.079 C0= 0.82
Ap= perforated area
After putting all value
hd = 51*(14.3/0.82)^2*(1.818/784.15)
hd=35.95 mm LC
hw= 50 mm Lc
Maximum height of liquid crest over the weir
Maximum Lmax= Lm /.7 =0.20/7= 0.28kg/sec
lw=0.44175 m
Maximum how = 750*(Lmax/(ρL* lw))(2/3) = 6.596 mm
Residual pressure drop
hr= (12.5*103)/784.15 = 15.91 mm
Total pressure drop per plate
ht= hd+ ( hw+ how) + hr =35.95+50+6.596+15.91
= 108.459 mm LC
Tray pressure drop for stripping section:Dry plate pressure drop
hd= 51*( Vh /C0)^2 *(ρ V/ ρL)
Vh=Maximum velocity of vapors through hole
Vh= Q V/A h (maximum)
Vh= 0.235/0.08096 = 2.90
ρV= 0.681 kg/m3 ,
ρL= 958 kg/m3
From fig 8.20 pg no-450 ( Bhatt and Thakore)
For, plate thickness/ hole diameter = 1
Ah/ Ap= Ah /Aa=(0.08096 /1.012) = 0.08 C0= 0.82
Ap= perforated area
After putting all value
Hd = 51*(2.90/0.82)^2*(0.681/958)
hd=0.453mm LC
hw= 50 mm Lc
Maximum height of liquid crest over the weir
Maximum Lmax= Lm /.7 =0.18/7= 0.257kg/sec
lw=0.9724 m
Maximum how = 750*(Lmax/(ρL* lw))(2/3) = 3.17 mm
48
Residual pressure drop
hr= (12.5*103)/958 = 13.04 mm
Total pressure drop per plate
ht= hd+ ( hw+ how) + hr =0.453+50+3.17+13.04
= 66.66 mm LC
Checking of downcomer design
For enriching section
hdc= 166(Lmd/ ρL*Am)2
Lmd= liquid flow rate through down comer
Lmd= L *Mav= 23.66*43.96/3600 = 0.288kg/s
ρL= 784.15 kg/m3
Am= Ad or Aap whichever is smaller
Aap= Perforated area
Ad= 0.12 Ac = 0.12*0.245= 0.0294m2
hap= hw – 10 = 50-10 = 40 mm = 0.04m
Aap= hap*lw= 0.04*0.44175
Aap= 0.01767m2
Aap<Ad
Therefore take Am= Aap
Am= Aap = 0.01767m2
After putting all value in hdc equation
hdc=166{L/(Am*ρL)}hdc
= 166{0.288/(0.01767*784.15)}2 = 0.0717 mm
hb= Liquid back up in down comer
hb= hw+ how+ ht+ hdc = 50+6.59+108.45+0.0717 = 165.12 mm
165.12 < (Lt+ hw) /2
Lt=Tray spacing=300mm
Residence time in down comer
Tr = Ad* hbc*ρL /(Lmd)
Tr= 0.0294*0.16512*784.15/0.288 = 16.08 seconds
Tr> 3 sec
Hence,downcomer area and tray spacing are acceptable
For stripping section
hdc= 166(Lmd/ ρL*Am)2
Lmd= liquid flow rate through down comer
Lmd= L *Mav= 52.9*18.310/3600 = 0.131kg/s
ρL= 958 kg/m3
Am= Ad or Aap whichever is smaller
Aap= Perforated area
Ad= 0.12 Ac = 0.12*1.46= 0.1752m2
hap= hw – 10 = 50-10 = 40 mm = 0.04m
Aap= hap*lw= 0.04*0.9724
49
Aap= 0.038896m2
Aap<Ad
Therefore take Am= Aap
Am= Aap = 0.038896m2
After putting all value in hdc equation
hdc=166{L/(Am*ρL)}hdc
= 166{0.131/(0.038896*958)}2 = 2.05*10^-3 mm
hb= Liquid back up in down comer
hb= hw+ how+ ht+ hdc = 50+3.17+66.66+2.05*10^-3 = 119.76 mm
119.76 < (Lt+ hw) /2
Lt=Tray spacing=300mm
Residence time in down comer
Tr = Ad* hbc*ρL /(Lmd)
Tr= 0.1752*0.119*958/0.131 = 152.46 seconds
Tr> 3 sec
Hence,downcomer area and tray spacing are acceptable
Checking of entrainment
For enriching section
Vapour velocity based on net area,Vn=Q/An
Vn= 0.2119 /0.228= 0.929 m/s
% of flooding = Vn/Vf = 0.929/1.09= 0.852*100 = 85% FLv =0.040 ,
Ψ=0.32 (from fig 8.18 pg no 447 B I Bhatt)% entrainment = 32% which is greater then 10%
For stripping section
Vapour velocity based on net area,Vn=Q/An
Vn= 0.235 /1.28= 0.1835m/s
% of flooding = Vn/Vf = 0.1835/0.215= 0.853*100 = 85% FLv =0.040 ,
Ψ=0.32 (from fig 8.18 pg no 447 B I Bhatt)% entrainment = 32% which is greater then 10%
Height of Distillation Column
Height of column Hc= (Nact-1) Hs+ ∆H+ plates thickness
Actual No. of plates =12
Tray spacing Hs = 0.30 m
∆H= 0.5 meter each for liquid hold up and vapor disengagement ∆H=1 m
Total thickness of trays = 0.005*12 = 0.06 m
So,
Height of column = (12-1)*0.30+ 1+0.06
= 5 meter
50
8.3-Process design of scrubber
Molar flow rate of fresh water entering scrubber at top
L2 = Ls = 381.856 kg/hr =21.21kmol/hr
L1 = Molar flow rate of solution leaving scrubber = 29.58 kmol/hr
x2 = mole fraction of solute in incoming solvent =0
X2=x2/1-x2 =0
G1 = molar flow rate incoming air vapour mixure = 51.307 kmol/hr
G2 =molar flow rate of gas at exit of scrubber from top = 42.96 kmol/hr
Mole fraction of vapour in outgoing air vapour mixture
Let concentration of acetaldehyde in outgoing mixture =110ppm
Let a mixture of vapour incoming containing 7% by volume of acetaldehyde
y1=0.07%(mole % = Volume %)
Y1=y1/1-y1 = 0.075
Srubber is required to absorb 98% of acetaldehyde
y2 =0.02*0.075 =1.5*10^-3
Y2=y2/1-y2 =0.00015
Tower diameter required at top
FLG = Lw /Gw*(ρg/ ρL)^0.5= 0.036
Lw=mass velocity of liquid in kg/m2*s
Lw =(381.856/3600)/ π/4*D2 = 0.106 kg/m2*s
Mav =ΣyiMi =28.2572
Gw = mass velocity of gas in kg/m2*s =G2*Mav/ π/4*D2
= (42.907*28.2512/3600)/ π/4*D2 =0.33kg/m2*s
Density of vapour mixture at top
ρ
g =P*Mav/R*T =1*28.2512/(0.082*(270+25)
1.14 kg/m3
ρ
L =1/ ΣWi/ρi =4193.3kg/m3
after putting all value
FLG = 5.29*10^-3
From fig 9.3 of ( Bhatt and Thakore) kf = 0.18
let actual velocity of gas =66% 0f flooding velocity
(K/kf)^0.5*100 =66%
K==0.66^2*0.18 =0.078
Pressure drop/m of packing height =76 mm H2O/m of packing
Mass velocity of gas through tower
Gw = (K* ρg* ρL*g/Fp* Ψ*meu^0.2)^0.5
Ψ =Density of liquid/Density of water =1491/1000=1.491
Viscosity of water at 25oc =1cp=10^-3kg/m*s
Packing factor Fp=170m-1
After putting all value
51
Gw =2.26 kg/m2*s
Toewr area required at top =Mass flow rate of gas vapour mixture/Gw
π/4*D2 =(42.907*28.2512/3600)/2.26 = 0..135m2
D=0.41 m
Mechanical Design of Scrubber
Material of construction: CS
Thickness of shell,
Internal dia.= .41m=410 mm
t=p*di/(2*f*j-p)
J=.85 (joint efficiency)
F=permissible stress=95 N/mm^2
P=0.1, taking 10% extra
Design pressure =0.1*1.1=0.11
t= 0.11*410(2*95*0.85-0.11)
=1.47mm.
Considering thickness =2mm
head thickness :
the head used will be torispherical head; the thickness of the head is given by:
th = p*Rc*W/(2*f*j)+c
head thickness :
torispherical head;
the thickness of the head is given by:
th = p*Rc*W/(2*f*j)+c
where,
W=(1/4)[3+(Rc/R1)]
Rc=crown radius=410mm
R1=6% of Rc=0.06*410= 24.6mm
W=( ¼)[3+(410/24.6)]
W=1.77
th = p*Rc*W/(2*f*j) = 0.11*410*1.77/(2*95*0.85)+c
th = .49+c =.49+1.5
th=2mm
52
CHAPTER 9
COST ESTIAMTION AND ECONOMICS
9.1 COST ESTIMATION
Cost of Acetaldehyde plant of capacity 2500 TPA
Chemical Engineering Plant Cost Index:
Cost index in 2002= 396
Cost index in 2013=585
 ESTIMATION OF CAPITAL COST ESTIMATION
Purchased equipment cost
9.1.1 Cost of reactor
Type Bubble column Reactor
Height of reactor =4m
Diameter of reactor= 1.33 m
Material of construction Carbon steel
Density of carbon steel = 7850 kg/m^3
On basis of capacity of reactor
Cost of vertical column in 2002 = 10000 $ (From chapter-15, graph.15.11 from Plant design
and economics for chemical engineers, Petersand Timmerhaus)
Using CHEMICAL ENGINEERING PLANT COST INDEX (CEPCI)
Value in present time
C=C0*ci/ci0
Where,C = present cost
Co = cost in the base year (in our case its 2002)
Ci = Plant cost index of the present year = 585
Cio = Plant cost index in base year = 396
Cost of reactor in present = $103550.2=Rs5.6*10^6
(The present rate of US Dollar is Rs 54.38)
9.1.2 Cost of Absorption column
Diameter = 0.41 m Height = 4 m Volume=0.527m^3
Purchased cost of vertical column from graph 15-11 (plant design and economics for chemical
engineers,Peters and Timmerhaus) C0= $ 8000 (as in 2002)
53
Current cost = C=C0*ci/ci0 =$11818.18 =Rs6.42*10^5
Where,C = present cost
C0 = cost in the base year (in our case its 2002)
Ci = Plant cost index of the present year = 585
Cio = Plant cost index in base year = 396
Purchased cost of packed column including installation and auxiliaries from graph 15-16(plant
design and economics for chemicalengineers,Peters and Timmerhaus,Cost)
C0 = 6000 $/m of height = $ 24000 (as in 2002)
Current cost = C=C0*ci/ci0 = $35544.3 =Rs 1.93*10^6
Cost of packing =75%of volume of reactor =0.39 m^3
Log10Cp = K1+K2log10A+K3[Log10(A)]^2
Where A =0.527
K1=2.4493
K2=0.9744
K3 = 0.0055
Cp=Rs 112.65 (as in 2001)
Value in present time
C=C0*ci/ci0
Where,C = present cost
C0 = cost in the base year (in our case its 2002)
Ci = Plant cost index of the present year = 585
Cio = Plant cost index in base year = 394.4
Present Cost =Rs 167.1
Total cost = Rs2.57*10^6
9.1.3 Cost of distillation column 1
Diameter = 0.56 m Height = 5 m No of trays = 12
Purchased cost of trays in tray column. Price includes tray deck, bubble cap, riser, downcomer
andstructural steel parts from ch 15, graph 15-13 (plant design and economics for chemical
engineers,Petersand Timmerhaus,
C0= $ 300 per tray
C0= $ 300*12 = $3600(as in 2002)
Present year cost= C=C0*ci/ci0 =5318.18 =Rs2.89*10^5
Purchased cost of distillation colum installation and auxiliaries from graph 15-15(plant design
and economics for chemicalengineers,Peters and Timmerhaus)
C0 =$1300 per tray =1300*12 =$15600 (as in 2002)
Present year cost= C=C0*ci/ci0 =23045.45 =Rs1.25*10^6
Total cost =Rs 1.54*10^6
9.1.4 Cost of distillation column 2
Diameter = 0.33mHeight = 7 m No of trays = 9
54
Purchased cost of trays in tray column. Price includes tray deck, bubble cap, riser, downcomer
andstructural steel parts from ch 15, graph 15-13 (plant design and economics for chemical
engineers,Petersand Timmerhaus,
C= $ 300*9 = $2700
Present year cost= $ 3988.6
Total cost of distillation column = $ 3988.6 =Rs2.16*10^5
Purchased cost of distillation colum installation and auxiliaries from graph 15-15(plant design
and economics for chemicalengineers,Peters and Timmerhaus)
C0 =$1000 per tray =1000*9 =$9000 (as in 2002)
Present year cost= C=C0*ci/ci0 =$13295.45 =Rs7.23*10^5
Total cost =Rs 9.39*10^5
9.1.5 Cost of storage vessel
Diameter = 2m Height = 5 m
Purchased cost of storage tank from graph 12-52 (plant design and economics for
chemicalengineers,Peters and Timmerhaus)
C0 = 1.8*10^5 (as in 2002)
Present year cost= C=C0*ci/ci0 =$265909.09 = Rs1.4*10^7
9.1.6 Cost of Heat Exchanger
Heat Exchanger for surface area of 20m^2
(Plant design and economics for chemical engineers,Peters and Timmerhaus,ch 14, fig.-1415)Cost of Heat Exchanger in 2002 = $ 1.3*10^3
Present Cost = C=C0*ci/ci0 =$1920.45 = Rs1.05*10^5
material of construction is carbon steel
Total purchased equipment cost =Rs 2.47*10^7
9.2 Total Capital Investment
Table-9.2.1 for calculation of Total Capital Investment
Fraction of
equipment
Fixed capital Investment
Direct Cost
Purchased equipment cost (PEC)
(a)onsite cost
Land 15000 m2 (Rs. 550/ m2)
Delivery, % of purchased Equipments
Subtotal: Delivered Equipment cost (DEC)
Purchased equipment Installation
Instrumentation and control
Piping
Electrical system
(b)Offsite cost
Delivered Cost (Rs.)
2.47*10^7
0.10 *PEC
0.35*DEC
0.26*DEC
0.32*DEC
0.11*DEC
55
8.25*10^6
2.47*10^6
2.71*10^7
9485000
7046000
8672000
298100
Building (including services)
Yard improvement
Service facilities
Total direct cost (TDC)
Indirect cost
Engineering and supervision
Construction expenses
Legal expenses
Contractors fee
Contingency
Total Indirect cost (TIC)
0.18*DEC
0.10*DEC
0.60*DEC
4878000
2710000
16260000
89852000
0.33*DEC
0.41*DEC
0.04*DEC
0.22*DEC
0.35*DEC
8943000
11111000
1084000
5962000
9485000
36585000
FIXED CAPITAL INVESTMENT(A)
= Direct Cost + Indirect Cost
0.85*DEC
(B)Working capital
0.1*FCI
(c) start up
TOTAL CAPITAL INVESTMENT=
(A) + (B)+(C)
126437000
23035000
12643700
1.62*10^8
9.2.1 ESTIMATION OF TOTAL PRODUCT COST:
 Manufacturing Cost
Manufacturing cost is the sum of Direct Production Cost, Fixed Charges and Plant
Overhead Cost.
 Fixed Charges (FC):
RANGE = 10-20% Total Product Cost
 Depreciation (DC):
RANGE = Depends on life period, Salvage Value
and method of calculation-about 10% of FCI for Machinery & Equipment, 2-3%
for Building Value for Buildings.
Let us consider Depreciation Cost = 10% of Fixed Capital Investment for
Machinery & Equipment and 2.5 % for Building Value
for Buildings.
DC = 16211870 + 121950
= Rs. 16333820
 Local Taxes (LT):
RANGE = 1-4% of Fixed Capital Investment
Let the local taxes = 2% of Fixed Capital Investment
LT = 2% of 126437000
= Rs. 2528740
56
 Insurance (InC):
RANGE = 0.4-1% of Fixed Capital Investment
Let the Insurance Cost = 0.6% of Fixed Capital Investment
InC = 0.6% x Rs. 126437000
= Rs. 758622
Then, Total Fixed Charges = Rs 19621182.
Fixed Charges (FC):
RANGE = 10-20% of Total Product Cost
Let the fixed charges = 15% of Total Product Cost
Then Total Product Cost = Rs. 130807880
9.2.2 DIRECT PRODUCTION COST:
 Raw Materials (RMC):
RANGE = 10-50% of Total Product Cost
Let the cost of raw materials = 40% of Total Product Cost
RMC = 40% x Rs. 130807880
= Rs. 52323152
 Operating Labour (OLC):
RANGE = 10-20% of Total Product Cost
Let the cost of operating labour = 12% of Total Product Cost
OLC = 12% x Rs. 130807880
= Rs. 15696945.6
 Direct Supervisory and Clerical Labour (DS & CLC):
RANGE = 10-25% of Operating Labour
Let the above mentioned cost = 15% of Operating Labour
DS & CLC = 15% x Rs. 15696945.6
= Rs. 2354541.84
 Utilities (UC):
RANGE = 10-20% of Total Product Cost
Let the Cost of Utilities = 14% of Total Product Cost
UC = 14% x Rs. 130807880
= Rs. 18313103.2
 Maintenance and Repairs (M & RC):
RANGE = 2-10% of Fixed Capital Investment
Let the Maintenance and Repair Cost = 5% of Fixed Capital Investment
M & RC = 5% x Rs. 126437000
= Rs. 6321850.
 Operating Supplies (OSC):
RANGE = 10-20% of Maintenance & Repairs
Let the Cost of Operating Supplies = 13% of Maintenance & Repairs
OSC = 13% x Rs. 6321850.
= Rs. 821840.45
 Laboratory Charges (LCC):
RANGE = 10-20% of Operating Labour Charges
57
Let the Laboratory charges = 15% of Operating Labour Charges
LCC = 15% x Rs. 15696945.6
= Rs. 2354541.84.
 Patent and Royalties (P & RC):
RANGE = 0-6% of Total Product Cost
Let the cost of Patent and royalties = 3% of Total Product Cost
P & RC = 3% x Rs. 130807880
= Rs. 3924236.4
Thus, Total Direct Production Cost = Rs. 335209853.5
9.2.3 PLANT OVER-HEAD COST (POHC):
RANGE = 50-70% of the Operating labour, supervision, maintenance
or 5-15% of total product cost; includes for the following:
general plant upkeep and overhead, payroll overhead,
packaging, medical services, safety and protection,
restaurants, recreation, salvage, laboratories, and storage
facilities.
Let the plant overhead cost = 10% Total direct Production Cost
POHC = 10% of Rs. 335209853.5
= Rs. 33520985.35
Thus,
Manufacturing Cost = Direct Production cost + Fixed charges + Plant Overhead cost
= Rs 388352020.9
9.2.4 GENERAL EXPENSES:
General Expenses is the sum of Administrative Costs, Distribution and Selling Cost and
Research and Development Costs.
 Administrative costs (AC):
RANGE = 2-6% of Total Product Cost
Let the Administrative costs = 4% of Total Product Cost
AC = 4% x Rs. 130807880
= Rs. 5232315.2
 Distribution and Selling Costs (D & SC):
RANGE = 2-20% of Total Product Cost which includes costs for sales
offices, salesmen, shipping, and advertising.
Let the Distribution and selling costs = 15% of Total Product Cost
D & SC = 15% of Rs. 130807880= Rs. 19621182
 Research and Development costs (R & DC):
RANGE = 5% of Total Product Cost
Let the Research and development costs = 5% of Total Product Cost
R & DC = 5% of Rs. 130807880
= Rs. 17005024.4
 Financing (interest) (FC):
RANGE = 0-10% of Total Capital Investment
58
Let the interest = 6% of Total Capital Investment
FC = 6% x Rs 162118700
= Rs. 9727122
Thus, Total General Expenses = Rs 51585643.6
Total Product cost = Manufacturing Cost + Total General Expenses
= Rs. 439937664
9.2.5 GROSS EARNING INCOME:
Wholesale Selling Price of acetaldehyde per kg = £ 2.0
Let 1£ = Rs. 70.00
Hence Selling Price of acetaldehyde per kg = 2.0 * 70 = Rs. 140
Total Income = Selling price * Quantity of product manufactured
= 140 * (2500tonn/year)
Total Income = Rs. 5.5* 10^8
Gross Income = Total Income – Total Product Cost
= Rs. 110062336
As available in the literature that the Tax rate is generally taken as 45%
Taxes = 45% of Gross Income
= 45% of 110062336
= 49528051.2
Net Profit = [Gross income – Taxes]
= Rs. 60534284.8
 Rate of Return:
Rate of Return = [Net profit*100]/Total Capital Investment
= Rs. [{60534284.8 * 100}/ Rs1.62*10^8
37.33
 Pay Back Period:
Cost Price of acetaldehyde = T P C/ Total Production of H2SO4 in (Kg/Annum)
= 439937664/2500*10^3
= Rs. 176
Assuming a profit margin of 25% = Rs. 220
Gross annual Earning = Total annual earning – total annual production cost
= 44 * 2500*10^3 = 11 crore.
Net Annual Earning = 11 – 45% of 11
= 6.05 crore.
Payback Period = TCI/Net annual Earning
= 16/6.05
= 2.6 = 3Years (approx.)
59
9.3 HAZOP Evaluation of the Reactor
This reaction is exothermic, and a cooling system is provided to remove the excess energy of
reaction. If the cooling flow is interrupted, the reactor temperature increases, leading to an
increase in the reaction rate and the heat generation rate. The result could be a runaway reaction
with a subsequent increase in the vessel pressure possibly leading to a rupture of the vessel. The
temperature within the reactor is measured and is used to control the cooling water flow rate by a
control valve.
Performing a HAZOP on this process with the assigned task of considering runaway reaction
episodes would lead to a completed form such as that shown in the Figure. The process is already
small enough to be considered a single section. Four study nodes are cooling water line, stirring
motor, monomer feed line, and reactor vessel.
The HAZOP analysis would reveal the following potential process modifications:
1. Installation of a cooling water flow meter and low flow alarm to provide an immediate
indication of cooling loss.
2. Installation of a high temperature alarm to alert the operator in the event of cooling
function loss.
3. Installation of a high temperature shutdown system, that would automatically shutdown
the process in the event of a high reactor temperature. The shutdown temperature would
be higher than the alarm temperature to provide the operator with the opportunity to
restore cooling before the reactor is shutdown.
4. Installation of a check valve in the cooling line to prevent reverse flow. A check valve
could be installed both before and after the reactor to prevent the reactor contents from
flowing upstream and to prevent the backflow in the event of a leak in the coils.
5. Periodic inspections and maintenance of the cooling coil to insure its integrity.
6. Evaluation of the cooling water source to consider any possible interruption and
contamination of the supply.
In the event that the cooling water system fails (regardless of the source of the failure), the high
temperature alarm and emergency shutdown system prevents a runaway. The review committee
performing the HAZOP decided that the installation of a back-up controller and control valve
60
was not essential. The high temperature alarm and shutdown system prevents a runaway in this
event.
Similarly, a loss of cooling water source or a plugged cooling line would be detected by either
the alarm or emergency shutdown system. The review committee suggested that all cooling
water failures be properly reported. In the event that a particular cause occurs repeatedly then
additional process modifications are warranted.
Table-9.3.1
Equipment
reference
and
operating
condition
Deviations
from
operating
condition
Reactor
Level
Less
What event
could cause
this
deviation
Consequences of
this deviation on
item of
equipment
under
consideration
Additional
implimentati
on of this
Consequence
s
1.Reator runs
dry
Pump cavitates
Damage to
pump
Reagent released
2. Rupture in.
Discharge
Potential fire
Reagent released
3. Vent open
or broken
Potential fire
Reagent released
Potential fire
More
4. Reactor
rupture
6. Unload too
much
No
7. Reverse
flow from
process
Tank overfills
Reagent
released
Tank overfills
Reagent
released
Same as less
Composition
Other than
8. Wrong
reagent
Possible reaction
As well as
9. Impurity in
reagent
volatile, possible
overpressure
61
Possible
reactor
rapture
Pressure
Less
10. Break lin. line to
flare or l-in.
nitrogen line
11. Lose
nitrogen
closed
Reagent released
Potential fire
Tank implodes
Reagent
released
More
Tank overfills
12. Overfill
tank
13.
Temperature
of inlet is
hotter
than normal
No
14. High
pressure
in flare
header
Tank rupture
Reagent released
Tank rupture
Reagent released
Tank rupture
Reagent released
Tank rupture
15. Volatile
impurity
Same as less
Temperature
Less
16.Temperatu
re of inlet is
colder than
normal
Possible vacuum
Reagent released
&Tank implodes
17.Low
reactor
pressure
Thermal
stress on
reactor
Thermal
stress on
reactor
Reagent released
More
18.Temperatu
re of inlet is
Reactor fails
62
Thermal
stress on
reactor
hotter than
normal
Reagent
released
19.External
fire
9.4 The Plant Layout Keywords:
1. Raw material Storage
2. Product Storage
3. Process Site
4. Laboratories
5. Workshop
6. Canteen & Change house
7. Fire Brigade
8. Central Control Room
9. Security office
10. Administrative Building
11. Site for Expansion Project.
12. Effluent treatment plant
13. Power house
14. Emergency water storage
15. Plant utilities
A detailed plant layout is drawn and submitted with this thesis report. This plant layout is
just a reference plant layout. There may be a lot of changes in actual plant layout
63
64
CHAPTER 10
CONCLUSIONS AND RECOMMENDATIONS
Acetaldehyde is a colorless, mobile liquid having a pungent suffocating odor that is somewhat
fruity and pleasant in dilute concentrations.Acetaldehyde is a simple, naturally-occurring,
organic chemical present in many ripe fruits,apples, grapes, and citrus fruits (up to 230 ppm). It
is produced during the fermentation of sugar to alcohol, and is a natural constituent of butter,
olives, frozen vegetables, and cheese. It forms in wine and other alcoholic beverages after
exposure to air (up to 140 ppm). It even occurs as an intermediate in the metabolism of sugars
in the body and hence can be found in human blood. Acetaldehyde is used as an intermediate in
the production of acetic acid, acetic anhydride, cellulose acetate, vinyl acetate resins, acetate
esters, pentaerythritol, synthetic pyridine derivatives, terephthalic acid and peracetic acid.
Acetaldehyde is produced throughout the world primarily from ethylene, although some is still
derived from ethanol and acetylene.
Demand for acetaldehyde worldwide has continued to decrease primarily as a result of less
consumption for acetic acid manufacture, as the industry continues to move toward the more
efficient and lower-overall-cost carbonylation-of-methanol process.
Overall, the global market for acetaldehyde is expected to grow 2–3% annually during 2009–
2014.
Ethylene which is important raw material for the production of acetaldehyde is a petrochemical
product ,soit is a safe step to install the plant with a capacity of 2500tons per annum in Gujrat
We have designed a plant of 2500TPA, with techno-economic feasibility report which is stated
withneed, demand & supply analysis and by going through a process of mass, energy balance
with detailedequipment design in the process.
The payback period (3 years) and rate of return suggests the plant to be economic viable and a
profitableventure to invest, in the interest of the stakeholders for an already existing group or a
newcomer in themarket.
65
References:1. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.87
2. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.88
3. http://en.wikipedia.org/wiki/Acetaldehyde
4. www.carolina.com/specialty...a/acetaldehyde...grade.../841271.pr
5. www.reportlinker.com/p098302/World-Acetaldehyde-Market.html
6. Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 pg no. 104
7. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.99
8. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.88
9. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.90
10. www.inchem.org/documents/ehc/ehc/ehc167.htm
11. Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 pg no. 105
12. Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 pg no. 107
13. ULLMANN’S, an ULLMANN'S Encyclopedia of Industrial Organic Chemistry
7, Page no.92
14. www.scribd.com/.../Acetaldehyde-Methods-2520of-2520-Production
15. Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 pg no. 108
16. Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 pg no. 106
17. Joshi’s process equipment design by Mahajani V.V & Umarji S. B 4th Edition
Edition
Edition
Edition
Edition
Edition
Edition
18. Joshi’s process equipment design by Mahajani V.V & Umarji S. B 4th Edition
19. Ulrich, Gael D., “A Guide to chemical Engineering Process Design and economics”, John
Wiley & sons, New York, USA (1984)
20.Introduction to process engineering and design by S B Thakore & B I Bhat
21.Design of Process Equipment, 2nd Ed. by Kanti K. Mahajan
22.Plant design and economics for chemical engineers, Peters and Timmerhaus.
23. Analysis synthesis and design of chemical engineerimg 2nd edition,Richard Turton.
24.. Chemical process safety , Danel A Crowl
25. www.sciencelab.com/msds.php?msdsId=9922768
66
APPENDIX-1
MATERIAL SAFTEY & DATA SHEET
Acetaldehyde
1: Product Identification
Product Name: Acetaldehyde
Catalog Codes: SLA1309
CAS#: 75-07-0
RTECS: AB1925000
TSCA: TSCA 8(b) inventory: Acetaldehyde
CI#: Not applicable.
Synonym: Ethyl Aldehyde; Ethanal; Acetic Aldehyde
Chemical Name: Acetaldehyde
Chemical Formula: CH3CHO
2: Composition and Information on Ingredients
Composition:
Name
Acetaldehyde
CAS #
75-07-0
% by Weight
100
Toxicological Data on Ingredients: Acetaldehyde: ORAL (LD50): Acute: 661 mg/kg [Rat.].
900 mg/kg [Mouse]. DERMAL
(LD50): Acute: 3540 mg/kg [Rabbit]. VAPOR (LC50): Acute: 13300 ppm 4 hours [Rat]. 23000
mg/m 4 hours [Mouse].
3: Hazards Identification
Potential Acute Health Effects:
Hazardous in case of eye contact (irritant), of ingestion, of inhalation (lung irritant). Slightly
hazardous in case of skin contact (irritant, permeator).
Potential Chronic Health Effects:
Hazardous in case of skin contact (irritant). Slightly hazardous in case of skin contact
(sensitizer). CARCINOGENIC
EFFECTS: Classified 2B (Possible for human.) by IARC. MUTAGENIC EFFECTS: Mutagenic
for mammalian somatic cells.
Mutagenic for bacteria and/or yeast. TERATOGENIC EFFECTS: Classified POSSIBLE for
human. DEVELOPMENTAL
TOXICITY: Not available. The substance may be toxic to liver. Repeated or prolonged exposure
to the substance can produce target organs damage.
4: First Aid Measures
67
Eye Contact:
Check for and remove any contact lenses. Immediately flush eyes with running water for at least
15 minutes, keeping eyelids open. Cold water may be used. Get medical attention.
Skin Contact:
In case of contact, immediately flush skin with plenty of water. Cover the irritated skin with an
emollient. Remove contaminated clothing and shoes. Cold water may be used.Wash clothing
before reuse. Thoroughly clean shoes before reuse. Get medical attention.
Inhalation:
If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult,
give oxygen. Get medical attention.
Serious Inhalation:
Evacuate the victim to a safe area as soon as possible. Loosen tight clothing such as a collar, tie,
belt or waistband. If breathing is difficult, administer oxygen. If the victim is not breathing,
perform mouth-to-mouth resuscitation. Seek medical attention.
Ingestion:
Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by
mouth to an unconscious person. If large quantities of this material are swallowed, call a
physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.
5: Fire and Explosion Data
Flammability of the Product: Flammable.
Auto-Ignition Temperature: 175°C (347°F) Flash Points:
CLOSED CUP: -38°C (-36.4°F)
OPEN CUP: -40°C (-40°F) (Lewis, 1997; ACGIH, 1996 (Cleveland).
Flammable Limits:
LOWER: 4% UPPER: 55% (Clayton; Patty's Industrial Hygiene and Toxicology); 57%
(American Conference of Govermental Industrial Hygiensts); 60% (National Fire Protection
Association)
Products of Combustion: These products are carbon oxides (CO, CO2).
Fire Hazards in Presence of Various Substances:
Extremely flammable in presence of open flames and sparks, of heat. Non-flammable in
presence of shocks.
Explosion Hazards in Presence of Various Substances:
Risks of explosion of the product in presence of static discharge: Not available. Explosive in
presence of heat, of acids, of alkalis. Non-explosive in presence of shocks.
Fire Fighting Media and Instructions:
Flammable liquid, soluble or dispersed in water. SMALL FIRE: Use DRY chemical powder.
LARGE FIRE: Use alcohol foam, water spray or fog. Cool containing vessels with water jet in
order to prevent pressure build-up, autoignition or explosion.
Special Remarks on Fire Hazards: When heated to decomposition it emits acrid smoke and
fumes.
Special Remarks on Explosion Hazards:
Hazardous or explosive polymerization may occur with acids, alkaline materials, heat, strong
bases, trace metals. Forms explosive peroxides on exposure to air, heat or sunlight.
68
6: Accidental Release Measures
Small Spill:
Dilute with water and mop up, or absorb with an inert dry material and place in an appropriate
waste disposal container.
Large Spill:
Flammable liquid. Keep away from heat. Keep away from sources of ignition. Stop leak if
without risk. Absorb with DRY earth, sand or other non-combustible material. Do not touch
spilled material. Prevent entry into sewers, basements or confined areas; dike if needed. Be
careful that the product is not present at a concentration level above TLV. Check TLV on the
MSDS and with local authorities.
Section 7: Handling and Storage
Precautions:
Keep locked up.. Keep away from heat. Keep away from sources of ignition. Ground all
equipment containing material. Do not ingest. Do not breathe gas/fumes/ vapor/spray. Avoid
contact with eyes. Wear suitable protective clothing. In case of insufficient ventilation, wear
suitable respiratory equipment. If ingested, seek medical advice immediately and show the
container or the label. Keep away from incompatibles such as oxidizing agents, combustible
materials, organic materials, metals, acids, alkalis.
Storage:
Store in a segregated and approved area. Keep container in a cool, well-ventilated area. Keep
container tightly closed and sealed until ready for use. Avoid all possible sources of ignition
(spark or flame).
8: Exposure Controls/Personal Protection
Engineering Controls:
Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of
vapors below their respective threshold limit value. Ensure that eyewash stations and safety
showers are proximal to the work-station location.
Personal Protection:
Splash goggles. Lab coat. Vapor respirator. Be sure to use an approved/certified respirator or
equivalent. Gloves (impervious).
Personal Protection in Case of a Large Spill:
Splash goggles. Full suit. Vapor respirator. Boots. Gloves. A self contained breathing apparatus
should be used to avoid inhalation of the product. Suggested protective clothing might not be
sufficient; consult a specialist BEFORE handling this product.
Exposure Limits:
TWA: 25 (ppm) from ACGIH (TLV) [United States] TWA: 200 STEL: 150 (ppm) from OSHA
(PEL) [United States] TWA: 360
STEL: 270 (mg/m3) from OSHA (PEL) [United States] Consult local authorities for acceptable
exposure limits.
9: Physical and Chemical Properties
Physical state and appearance: Liquid. (Fuming liquid.)
69
Odor: Fruity. Pungent. (Strong.)
Taste: Leafy green
Molecular Weight: 44.05 g/mole
Color: Colorless.
pH (1% soln/water): Not available.
Boiling Point: 21°C (69.8°F)
Melting Point: -123.5°C (-190.3°F)
Critical Temperature: 188°C (370.4°F)
p. 4
Specific Gravity: 0.78 (Water = 1)
Vapor Pressure: 101.3 kPa (@ 20°C)
Vapor Density: 1.52 (Air = 1)
Volatility: Not available.
Odor Threshold: 0.21 ppm
Dispersion Properties: See solubility in water, diethyl ether, acetone.
Solubility:
Easily soluble in cold water, hot water. Soluble in diethyl ether, acetone. Miscible with benzene,
gasoline, solvent naphtha, toluene, xylene, turpentine. Solubility in water: 1000 g/l @ 25 deg. C.
10: Stability and Reactivity Data
Stability: The product is stable.
Conditions of Instability: Heat, igition sources (flames, sparks), incompatible materials
Incompatibility with various substances:
Highly reactive with metals, acids, alkalis. Reactive with oxidizing agents, combustible
materials, organic materials.
Corrosivity: Non-corrosive in presence of glass.
Special Remarks on Reactivity:
Reacts with oxidizing materials, halogens, amines, strong alkalies (bases), and acids, cobalt
acetate, phenols, ketones, ammonia, hydrogen cyanide, hydrogen sulfide, hydrogen peroxide,
mercury (II) salts (chlorate or perchlorate), acid anhydrides, alcohols, iodine, isocyanates,
phosphorus, phosphorus isocyanate, tris(2-chlorobutyl)amine. It can slowly polymerize to
paraldehyde. Polymerization may occur in presence of acid traces causing exothermic reaction,
increased vessel pressure, fire, and explosion. Impure material polymerizes readily in presence of
traces of metals (iron) or acids. Acetaldehyde is polymerized violently by concentrated sulfuric
acid. Acetaldehyde can dissolve rubber.
11: Toxicological Information
Routes of Entry: Absorbed through skin. Eye contact. Inhalation. Ingestion.
Toxicity to Animals:
WARNING: THE LC50 VALUES HEREUNDER ARE ESTIMATED ON THE BASIS OF A
4-HOUR EXPOSURE. Acute oral
toxicity (LD50): 661 mg/kg [Rat.]. Acute dermal toxicity (LD50): 3540 mg/kg [Rabbit]. Acute
toxicity of the vapor (LC50): 23000
mg/m3 4 hours [Mouse].
70
Chronic Effects on Humans:
CARCINOGENIC EFFECTS: Classified 2B (Possible for human.) by IARC. MUTAGENIC
EFFECTS: Mutagenic for mammalian somatic cells. Mutagenic for bacteria and/or yeast.
TERATOGENIC EFFECTS: Classified POSSIBLE for human.May cause damage to the
following organs: liver.
Other Toxic Effects on Humans:
Hazardous in case of ingestion, of inhalation (lung irritant). Slightly hazardous in case of skin
contact (irritant, permeator)..
Special Remarks on Chronic Effects on Humans:
May cause adverse reproductive effects and birth defects(teratogenic) based on animal test data
May affect genetic material
(mutagenic). May cause cancer based on animal test data
Special Remarks on other Toxic Effects on Humans:
Acute Potential Health Effects: Skin: Causes mild skin irritation. It can be absorbed through
intact skin. Eyes: Causes severe eye irritation. Eye splashes produce painful but superficial
corneal injuries which heal rapidly. Inhalation: It causes upper respiratory tract and mucous
membrane irritation. It decreases the amount of pulmonary macrophages. It may cause
bronchitis. It may cause pulmonary edema, often the cause of delayed death. It may affec
respiration (dyspnea) and respiratory arrest and death may occur. It may affect behavior/central
nervous and cause central nervous system depression. Iirritation usually prevents voluntary
exposure to airborne concentrations high enough to cause CNS depression, although this effect
has occurred in experimental animals. It may also affect the peripheral nervous system and
cardiovascular system (hypotension or hypertension, tachycardia, bradycardia), kidneys
(albuminuria) Chronic Potential Health Effects: Skin: Prolonged direct skin contact causes
erythema and burns. Repeated exposure may cause dermatitis secondary to primary irritation or
sensitization. Ingestion: Symptoms of chronic Acetaldehyde exposure may resemble those of
chronic alcoholism.
Acetaldehyde is the a metabolite of ethanol in humans and has been implicated as the active
agent damaging the liver in ethanol-induced liver disease.
12: Ecological Information
Ecotoxicity: Not available.
BOD5 and COD: Not available.
Products of Biodegradation:
Possibly hazardous short term degradation products are not likely. However, long term
degradation products may arise.
Toxicity of the Products of Biodegradation: The products of degradation are less toxic than the
product itself.
13: Disposal Considerations
Waste Disposal:
Waste must be disposed of in accordance with federal, state and local environmental control
regulations.
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14: Transport Information
DOT Classification: CLASS 3: Flammable liquid.
Identification: : Acetaldehyde UNNA: 1089 PG: I
Special Provisions for Transport: Marine Pollutant
15: Other Regulatory Information
Federal and State Regulations:
California prop. 65: This product contains the following ingredients for which the State of
California has found to cause cancer, birth defects or other reproductive harm, which would
require a warning under the statute: Acetaldehyde California prop. 65 (no significant risk level):
Acetaldehyde: 0.09 mg/day (value) California prop. 65: This product contains the following
ingredients for which the State of California has found to cause cancer which would require a
warning under the statute: Acetaldehyde Connecticut hazardous material survey.: Acetaldehyde
Illinois toxic substances disclosure to employee act: Acetaldehyde Illinois chemical safety act:
Acetaldehyde New York release reporting list: Acetaldehyde Rhode Island RTK hazardous
substances: Acetaldehyde Pennsylvania RTK: Acetaldehyde Minnesota: Acetaldehyde
Massachusetts RTK: Acetaldehyde Massachusetts spill list: Acetaldehyde New Jersey:
Acetaldehyde New Jersey spill list: Acetaldehyde New Jersey toxic catastrophe prevention act:
Acetaldehyde Louisiana spill reporting: Acetaldehyde California Director's List of Hazardous
Substances: Acetaldehyde TSCA 8(b) inventory: Acetaldehyde SARA 313 toxic chemical
notification and release reporting: Acetaldehyde CERCLA: Hazardous substances.:
Acetaldehyde: 1000 lbs. (453.6 kg).
Other Regulations:
OSHA: Hazardous by definition of Hazard Communication Standard (29 CFR 1910.1200).
EINECS: This product is on the European Inventory of Existing Commercial Chemical
Substances.
Other Classifications:
WHMIS (Canada):
CLASS B-2: Flammable liquid with a flash point lower than 37.8°C (100°F). CLASS D-2A:
Material causing other toxic effects
(VERY TOXIC).
DSCL (EEC):
R12- Extremely flammable. R36/37/38- Irritating to eyes, respiratory system and skin. R40Possible risks of irreversible effects. S16- Keep away from sources of ignition - No smoking.
S33- Take precautionary measures against static discharges.
S36/37/39- Wear suitable protective clothing, gloves and eye/face protection.
HMIS (U.S.A.):
Health Hazard: 2
Fire Hazard: 4
Reactivity: 0
Personal Protection: j
National Fire Protection Association (U.S.A.):
Health: 3
Flammability: 4
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Reactivity: 2
Specific hazard:
Protective Equipment:
Gloves (impervious). Lab coat. Vapor respirator. Be sure to use an approved/certified respirator
or equivalent. Wear appropriate respirator when ventilation is inadequate. Splash goggles.
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