MANUFACTURE OF FORMALDEHYDE
FROM METHANOL
A PROJECT REPORT
Submitted by
S. GAYATHRI (41501203005)
G. MUTHAMILARASI (41501203014)
in partial fulfillment for the award of the degree
of
BACHELOR OF TECHNOLOGY
in
CHEMICAL ENGINEERING
S.R.M. ENGINEERING COLLEGE,
KATTANKULATHUR-603 203, KANCHEEPURAM DISTRICT.
ANNA UNIVERSITY : CHENNAI - 600 025
MAY 2005
iii
BONAFIDE CERTIFICATE
Certified that this project report "MANUFACTURE OF FORMALDEHYDE FROM
METHANOL" is the bonafide work of "S. GAYATHRI (41501203005) and G.
MUTHAMILARASI (41501203014)" who carried out the project work under my
supervision.
Prof. Dr. R. KARTHIKEYAN
Prof. Dr. R. KARTHIKEYAN
HEAD OF THE DEPARTMENT
SUPERVISOR
CHEMICAL ENGINEERING
PROFESSOR & HEAD
S.R.M.Engineering College
CHEMICAL ENGINEERING
Kattankulathur - 603 203
S.R.M.Engineering College
Kancheepuram District
Kattankulathur - 603 203
Kancheepuram District
iv
ACKNOWLEDGEMENT
Our heart felt thanks to the Director, Dr.T.P.Ganesan, and our Principal, Prof.
R.Venkatramani,M.Tech,F.I.E, for allowing us to carryout our project.
We express our profound gratitude to
Dr.R.Karthikeyan, Head of the
Department, Chemical engineering, who guided us in the right direction through the
course of our project.
We also thank our project co-ordinater Mrs.K.Kasturi,B.Tech, for her valuable
advice and encouragement.
Our special thanks to the members of the DTP section and library for their cooperation
v
ABSTRACT
Formaldehyde, one of the important industrial chemicals, finds its applications
in polymeric resins like phenol formaldehyde, adhesives, alkali resins for paints and
coatings etc…Manufacture of formaldehyde (as formalin) is done by oxidation of
methanol, mainly by metal oxide process involving Fe/Mo catalyst with 95-99mol%
conversion of methanol. This project is aimed at designing plant producing 37 wt%
formalin and checking for feasibility of production.
vi
TABLE OF CONTENTS
CHAPTERS
TITLE
PAGE NO
iv
ABSTRACT
vii
LIST OF TABLES
viii
LIST OF FIGURES
LIST OF SYMBOLS
ix
1
INTRODUCTION
1
2
PROPERTIES
2.1 PHYSICAL PROPERTIES
2.2 THERMAL PROPERTIES
2.3 CHEMICAL PROPERTIES
3
3
3
4
3
ANALYSIS AND SPECIFICATIONS
7
4
COMMERCIAL USES OF FORMALIN
8
5
LITERATURE REVIEW
5.1 SELECTION OF PROCESS
10
11
6
PROCESS DESCRIPTION
6.1 FLOW SHEET
12
14
7
MATERIAL BALANCE
15
8
ENERGY BALANCE
19
9
DESIGN
23
10
PLANT LAYOUT
29
11
MATERIALS OF CONSTRUCTION
11.1 METALS
11.2 NON-METALS
39
39
40
12
INSTRUMENTATION AND CONTROL
41
vii
13
STORAGE AND TRANSPORTATION
46
14
HEALTH AND SAFETY CONSIDERATIONS
47
15
COST ESTIMATION
49
16
CONCLUSION
56
REFERENCES
57
LIST OF TABLES
Table
Number
Description
Page No
1
Heat transfer data
19
2
Storage temperatures
46
3
Dose-response relationship
47
4
Delivered cost of equipments
49
5
Direct cost factor
50
6
Indirect cost factor
50
7
Auxillary cost factor
52
viii
LIST OF FIGURES
Page No
FIGURE 6.1
FLOW SHEET
14
FIGURE 7.1
REACTOR BALANCE
17
FIGURE 7.2
ABSORBER BALANCE
18
FIGURE 8.1
ENERGY BALANCE FOR
METHANOL VAPORIZER
19
FIGURE 8.2
ENERGY BALANCE FOR REACTOR
20
FIGURE 8.3
ENERGY BALANCE FOR HEAT
EXCHANGER 1
21
FIGURE 8.4
ENERGY BALANCE FOR HEAT
EXCHANGER 2
21
FIGURE 8.5
ENERGY BALANCE FOR
ABSORBER(BOTTOM)
21
FIGURE 8.6
ENERGY BALANCE FOR
ABSORBER (TOP)
22
FIGURE 10.1
PLANT LAYOUT
38
ix
LIST OF SYMBOLS
A
Area (m2)
D,d
Diameter (m)
L
Length (m)
m
Mass (Kg)
Nu
Nusselt number
n
Number of tubes
P
Pressure (atm)
Pr
Prandtl number
Re
Reynolds number
V
Volume(m3)
T
Temperature(K)
U
Overall heat transfer
coefficient(W/ m2.oC)
Z
Height (m)
GREEK LETTERS
∆T
Temperature difference (oC)
∆TL
Logarithmic mean temperature difference (oC)
µL
Viscosity of liquid
ρ
Density (Kg/m3)
x
1. INTRODUCTION
Formaldehyde occurs in nature and it is formed from organic material by
photochemical processes in the atmosphere. Formaldehyde is an important metabolic
product in plants and animals (including humans), where it occurs in low but
measurable concentrations. It has a pungent odour and is an irritant to the eye, nose
and throat even at low concentrations.
However, Formaldehyde does not cause any chronic damage to human health.
Formaldehyde is also formed when organic material is incompletely combusted.
Formaldehyde is an important industrial chemical and is employed in the manufacture
of many industrial products and consumer articles.
Formaldehyde was first synthesized in 1859, when BUTLEROV hydrolyzed
methylene acetate and noted the characteristic odour of the resulting solution. In
1867,HOFMANN conclusively identified formaldehyde, which he prepared by
passing methanol vapour and air over a heated platinum spiral. This method, but with
other catalyst, still constitutes the principal method of manufacture.
Industrial production of formaldehyde became possible in 1882,when
TOLLENS discovered a method of regulating the methanol vapour: air ratio and
affecting the yield of the reaction. In 1886 LOEW replaced the platinum spiral
catalyst by more efficient copper gauze. A German firm, Hugo Blank, patented the
first use of a silver catalyst in 1910.In 1905,Badische Anilin and Soda-Fabrik started
to manufacture formaldehyde by a continous process employing a crystalline catalyst.
Formaldehyde output was 30 kg/day in the form of an aqueous 30 wt% solution. The
methanol required for the production of formaldehyde was initially obtained from the
timber industry by carbonizing wood. The development of high-pressure synthesis of
methanol by Badische Anilin and Soda-Fabrik in 1925 allowed the production of
formaldehyde on a true industrial scale
11
2. PROPERTIES
2.1 PHYSICAL PROPERTIES
Formaldehyde is a colorless gas at ambient temperature that has a pungent,
suffocating odor. At ordinary temperatures formaldehyde gas is readily soluble in
water, alcohols and other polar solvents. It has following physical properties:
Boiling point at 101.3 kPa = -19.2oC
Melting point = -118oC
Density at –80oC = 0.9151g/cm3
At –20oC = 0 .8153 g/cm3
Vapor density relative to air = 1.04
Critical temperature = 137.2 – 141.2 (oC)
Critical pressure = 6.784 – 6.637 Mpa
Cubic expansion coefficient = 2.83 x 10–3 K-1
2.2 THERMAL PROPERTIES
Heat of formation at 25oC = -115.9 + 6.3 kJ/mol
Heat of combustion at 25oC = 561.5 kJ/mol
Heat of vapourisation at –19.2oC = 23.32 kJ/mol
Specific heat capacity at 25oC = 35.425 J/mol K
Heat of solution at 23oC
In water = 62 kJ/mol
In methanol= 62.8 kJ/mol
In 1-propanal = 59.5 kJ/mol
In 1-butanol = 62.4 kJ/mol
Entropy at 25oC= 218.8 + 0.4 kJ/mol K
2.3 CHEMICAL PROPERTIES
Formaldehyde is one of the most reactive organic compounds known. The
various chemical properties are as follows:
Decomposition
At 150oC formaldehyde undergoes heterogeneous decomposition to form
methanol and CO2 mainly. Above 350oC it tends to decompose in to CO and H2.
12
Polymerization
Gaseous formaldehyde polymerizes slowly at temperatures below 100oC,
polymerization accelerated by traces of polar impurities such as acids, alkalis or
water. In water solution formaldehyde hydrates to methylene glycol
H
H2C=O + H2O
HO
C
OH
H
Which in turn polymerizes to polymethylene glycols, HO (CH2O)nH, also
called polyoxy methylenes.
Reduction and Oxidation
Formaldehyde is readily reduced to methanol with hydrogen over many metal
and metal oxide catalysts. It is oxidized to formic acid or CO2 and H2O.
In the presence of strong alkalis or when heated in the presence of acids
formaldehyde undergoes cannizzaro reaction with formation of methanol and formic
acid. In presence of aluminum or magnesium methylate, paraformaldehyde reacts to
form methyl formate (Tishchenko reaction)
2HCHO
HCOOCH3
Addition reactions
The formation of sparingly water-soluble formaldehyde bisulphite is an
important addition reaction. Hydrocyanic acid reacts with formaldehyde to give
glyconitrile.
HCHO + HCN
HOCH2 - C ≡ N
Formaldehyde undergoes acid catalyzed Prins reaction in which it forms α-Hydroxymethylated adducts with olefins. Acetylene undergoes a Reppe addition reaction with
formaldehyde to form 2- butyne-1,4- diol.
13
2 HCHO + HC ≡CH
HOCH2≡CCH2OH
Strong alkalis or calcium hydroxide convert formaldehyde to a mixture of sugars in
particular hexoses, by a multiple aldol condensation, which probably involves a
glycolaldehyde intermediate. Acetaldehyde, for example reacts with formaldehyde to
give pentaerythritol, C (CH2OH)4
Condensation reactions
Important condensation reactions are the reaction of formaldehyde with amino
groups to give schiff’s bases, as well as the Mannich reaction.
CH3COCH3
+
(CH3)
2NH.HCl
+
HCHO
CH3COCH2CH2N(CH3) 2.HCl + H2O
Formaldehyde reacts with ammonia to give hexamethylene teteramine and
with
ammonium
chloride
to
give
monomethylamine,
dimethylamine,
or
trimethylamine and formic acid, depending upon reaction conditions.
Aromatic compounds such as benzene, aniline, and toluidine combine with
formaldehyde to produce the corresponding diphenyl methanes. In the presence of
hydrochloric acid and formaldehyde, benzene is chloromethylated to form benzyl
chloride. Formaldehyde reacts with hydroxylamine, hydrazines, or semicardazide to
produce formaldehyde oxime, the corresponding hydrazones, and semicarbazone,
respectively.
Resin formation
Formaldehyde condenses with urea, melamine, urethanes, cyanamide,
aromatic sulfonamides and amines, and phenols to give wide range of resins.
14
3. ANALYSIS AND SPECIFICATIONS
Qualitative Methods:
Qualitative detection of formaldehyde is primarily by colorimetric methods.
Schiff’s fuchsin-bisulfite reagent is the general reagent used for detecting aldehydes.
In the presence of strong acids, it reacts with formaldehyde to form a specific bluish
violet dye.
Quantitative Methods:
Physical Methods: Quantitative determination of pure aqueous solutions of
formaldehyde can be carried out rapidly by measuring their specific gravity. Gas
chromatography and high-pressure liquid chromatography can also be used for direct
determination.
Chemical Methods:
The most important chemical method for determining formaldehyde is the
sodium sulfite method. It is based on the quantitative liberation of sodium hydroxide
when formaldehyde reacts with excess sodium sulfite.
CH2O + Na2SO3 + H2O
HOCH2SO3Na + NaOH
The stoichiometrically formed sodium hydroxide is determined by titration
with an acid.
Formaldehyde in air can be determined with the aid of gas sampling apparatus.
In this procedure formaldehyde is absorbed from a definite volume of air by a wash
liquid and is determined quantitatively by a suitable method like pararosanline
method.
Formaldehyde is sold in aqueous solutions with concentrations ranging from
25 – 56 wt% HCHO. Formaldehyde is sold as low methanol (uninhibited) and high
methanol (inhibited) grades. Formaldehyde solutions contain 0.5-12 wt% methanol or
other added stabilizers. They have a pH of 2.5 –3.5,the acid reaction being due to the
presence of formic acid.
4. COMMERCIAL USES OF FORMALDEHYDE
Formaldehyde resins are one of the major applications of formaldehyde. Some
of the derivatives are given below.
Urea-formaldehyde resins are produced by the controlled reaction of urea and
formaldehyde. Their major uses are as adhesives for particleboard, fiberboard and
15
plywood. They are also used for compression molded plastic parts, as wet-strength
additives for paper treating, and as bonders for glass fiber roofing materials.
Phenol formaldehyde is produced by the condensation of phenol with
formaldehyde. The use of these resins is as an adhesive in waterproof plywood. These
resins are also used for binding glass fiber insulation.
Acetylenic chemical uses of formaldehyde involve the reaction with acetylene
to form butynediol, which in turn can be converted to butanediol, butyrolactone and
pyrrolidones. Their major applications are as specialty solvent and extractive
distillation agents.
Polyacetyl resins are produced from the anionic polymerization of
formaldehyde. These resins are used in plumbing materials and automobile
components.
Pentaerythritol is formed by the reaction of formaldehyde, acetaldehyde and
sodium hydroxide. Its largest use is in the manufacture of alkyd resins for paints and
other protective coatings.
Hexamethylene tetramine is formed by the reaction between formaldehyde
and ammonia. It is used as a partial replacement for phosphates as a detergent builder
and as a chelating agent.
Urea-formaldehyde concentrates are used as controlled release nitrogen
fertilizers.
Melamine resins are thermosetting resins produced from melamine and
formaldehyde and are primarily used for surface coatings.
The direct use of formaldehyde is to impart wrinkle resistance in fabrics.
16
5. LITERATURE SURVEY
Most of the world’s commercial formaldehyde is manufactured from methanol
and air either by a process using a silver catalyst or one using a metal oxide catalyst.
SILVER CATALYST PROCESS
The silver catalyst processes for converting methanol to formaldehyde are
generally carried out at an atmospheric pressure and at 600 – 720°C .The reaction
temperature depends on the excess of methanol in the methanol-air mixture. The
composition of mixture must lie outside the explosive limits. The amount of air used
is also determined by the catalytic quality of the silver surface. The following
reactions take place
CH3OH + ½ O2
HCHO + H2O
CH3OH
HCHO + H2
Methanol conversion is 65 – 75% per pass.
METAL OXIDE PROCESS
In this process formaldehyde is formed by oxidation process only. The
reactions are
CH3OH + ½ O2
HCHO + H2O
HCHO + ½ O2
CO + H2O
The reactions occur over a mixed oxide catalyst containing molybdenum oxide
and iron oxide in a ratio 1.5 to 3.The reaction is carried out at 250 –350 oC and
essentially at atmospheric pressure. Methanol conversion is 95 – 98% per pass.
5.1 SELECTION OF PROCESS
It is estimated that nearly 70% of commercial formaldehyde is produced by
metal oxide process. This process has a very low reaction temperature, which permits
high catalyst selectivity, and the very simple method of steam generation. The
conversion is around 95-98% per pass, which is greater than silver oxide process.
17
6. PROCESS DESCRIPTION
Metal oxide process: Vaporized methanol is mixed with air and optionally recycled
tail gas is passed through catalyst filled tubes in a heat exchanger reactor. The
following reactions take place in the reactor.
CH3OH+ ½ O2
HCHO + ½ O2
HCHO +H2O +37 Kcal/g-mol
CO+H2O+51 Kcal/g-mol
The temperature inside the reactor is maintained at 250-350°C.
The heat released by the exothermic reaction is removed by vaporization of a
high boiling heat transfer fluid on outside of the tubes. Steam is normally produced by
condensing the heat transfer fluid. The catalyst is granular or spherical supported
Fe/Mo and has an effective life of 12 –18 months. A typical reactor has short tubes of
1-1.5m and a large shell diameter of 2.5 m or more. The exit gases from the reactor
pass through a heat exchanger where the temperature is reduced to 110oC and then to
the absorption column where water is used as the scrubbing medium.
The absorber can be either of packed or tray type. It is necessary to remove the
heat of solution plus the residual sensible heat of the feed gases, and this is done by
circulating down flow liquid through external heat exchangers and in some cases by
the use of cooling coils. The bottom stream from the absorber represents the final
product. Formaldehyde concentration in the product is adjusted by controlling the
amount of water added to the top of the absorber. Formic acid is removed by ion
exchange. A large portion of the absorber overhead gas is recycled back to the feed
system. The methanol conversion ranges from 95-99mol% and depends on the
selectivity, activity and spot temperature of the catalyst, the later being influenced by
the heat transfer rate. The overall plant yield of formaldehyde is 88-95 mol%.
18
The final product contains up to 55wt% formaldehyde and 0.5-1.5 wt%
methanol.
PURGE GAS
RECYCLE GAS
WATER
St
2
BFW
BLOWER
AIR
1
`
St
R
E
A
C
T
O
R
A
B
S
O
R
B
E
R
CW
CW
St
3
BFW
F
O
R
M
A
L
I
N
METHANOL
1. METHANOL VAPORIZER
2. HEAT EXCHANGER 1
3. HEAT EXCHANGER 2
DEIONISER
19
FIG 6.1 FLOW SHEET
7. MATERIAL BALANCE
Basis: 100 kmoles of methanol in fresh feed per hour
Molecular weight of methanol = 32 kg/kmole
Weight of methanol in feed = 3200 kg
CH3OH + ½ O2
HCHO + H2O
Assume methanol conversion is 97 %.
Hence methanol reacted = 97 kmoles
= 3104 kg
Assume that 1% of methanol reacts to form formic acid.
HCHO + ½ O2
CO + H2O
Actual O2 required = 51.925 kmoles = 1661.60 kg
Actual O2 supplied (250% excess) = 181.738 kmoles = 5815.62 kg
Excess O2 = 181.738 – 51.925
= 129.813 kmoles =4154.02 kg
Assume that 57% of oxygen requirement comes from recycle stream and 43% comes
from fresh feed.
O2 from fresh feed = 181.738 x 0.43
= 78.147 kmoles = 2500.70 kg
Corresponding N2= 78.147 x (79/21)
= 298.982 kmoles = 8371.50 kg
Assume that the percentage composition of recycle stream is
O2 - 7.78%
20
N2 - 88.3%
H2O - 3.89%
O2 from recycle stream = 103.590 kmoles =3314.88 kg
N2 in recycle stream = 1175.910 kmoles =32925.48 kg
H20 in recycle stream = 51.795 kmoles =932.31 kg
Reactor outlet:
Unreacted methanol = 2 kmoles=64 kg
HCHO formed = 92.15 kmoles=2764.50 kg
H2O formed = 154.64 kmoles=2783.52 kg
CO formed = 4.85 kmoles= 135.8 kg
Nitrogen =1484.185 kmoles=41157.20 kg
Unreacted oxygen =129.813 kmoles =4154.02 kg
HCOOH formed = 1 kmole = 46 kg
O2= 3314.82 kg
N2 = 32925.48 kg
H20 = 932.31 kg
Methanol =3200kg
REACTOR
CH3OH = 64 kg
O2=4153.92 kg
N2=41157.20kg
H20 = 2783.4 kg
HCHO=2764.5 kg
CO=135.8 kg
HCOOH=46 kg
Air
O2=2500.71kg
N2 =8231.50 kg
TOTAL INPUT =51104.82 kg
TOTAL OUTPUT =51104.82 kg
FIG 7.1
21
ABSORBER
Gms (Ya-Yb) = Lms (Xa- Xb)
Gms =molar flow rate of gas on solute free basis
Lms =molar flow rate of liquid on solute free basis
Xa =% of solute in liquid at inlet
Xb =% of solute in liquid at outlet
Ya =fraction of solute in gas at inlet
Yb =fraction of solute in gas at outlet
Gas flow rate = Gms= 1653.645 kmoles/hr
M= 0.0678 (VLE data)
M= (Lms) min
Gms
(Lms) min = 112.117 kmoles
Yb = 5/95 = 0.0526
Ya = 3.14 X10–4
Xa = 0
Xb =0.7758
Assume Lms = 1.4 (Lms) min
Lms = 157.71 kmoles
22
FROM REACTOR
CH3OH = 64 kg
O2=4153.92 kg
N2=41157.20kg
H20 = 2783.4 kg
RECYCLE STREAM
H20=1165.39 kg
O2=4153.92 kg
N2=41156.64 kg
PRODUCT
STREAM
HCHO=2764.5 kg
H20=4593.02 kg
ABSORBER
HCHO=2764.5 kg
CO =135.8 kg
HCOOH=46 kg
CH3OH=64 kg
HCOOH=46 kg
SOLVENT
H20=2838.78 kg
TOTAL INPUT = 53943.46 kg
TOTAL OUTPUT = 53943.46 kg
FIG 7.2
8. ENERGY BALANCE
DATA TABLE 1:
Methanol
O2
N2
H2 O
CO
HCOOH
HCHO
Oil
Specific heat capacity
Cp(KJ/Kg oC)
Latent heat of
vaporization,λ
(KJ/Kg)
1099.90 (at 64.7 oC)
2255(at 100 oC)
3278.20 (at 400 oC)
2228.69(at 110 oC)
-
2.513
0.928
1.04
1.88
1.13
0.6
0.5
1.75
1) Methanol vaporizer
RECYCLE AIR (25oC)
O2 :3314.8 Kg
N2: 32925 Kg
H20:932.31 Kg
H20 (400 oC)
CH3OH = 3200 Kg
Methanol
Vaporizer
23
AIR(285 oC)
METHANOL
FRESH AIR
O2: 2500 Kg
N2: 8231.5Kg
(400 oC)
SUPERHEATED
STEAM
FIG 8.1
mCp ∆T(inlet stream) = mλ (steam)
(m Cp (recycle) + m Cp (air) +m Cp (methanol liq)+mλ(methanol) +m Cp (methanol gas) )(285-25) =
18.08x105 = m x 3278.20
Steam required m = 551.52 Kg
2)Reactor
CH3OH = 3200 Kg
O2 = 5815.6 Kg
N2 = 41157.2 Kg
H20 = 932.31 Kg
o
(285 C)
Isothermal
Reactor
CH3OH = 64 Kg
O2 = 4153.92 Kg
N2 = 41157.20 Kg
H20 = 2783.61 Kg
CO = 135.80 Kg
HCOOH = 46 Kg
HCHO = 2764.50 Kg
FIG 8.2
Reactions:
CH3OH + 1/2 O2
HCHO + H20 ∆ Ho = -4839 KJ/Kg
HCHO + 1/2 O2
CO + H20
∆Ho = -7115.35 KJ/Kg
For an isothermal reaction:
Σ ∆H(products) + Σ ∆Ho - Σ ∆H(reactants) =∆H
(∆H = m CP∆ T)
(∆T=285-25=260)
Substituting values from table 1,
∆H = 13.8687x106 KJ
∆H (reactor) = m Cp∆T(cooling oil)
13.8687x106 = m x 1.75x 110
Oil required m = 72045.058 Kg
24
3) Heat exchanger 1:
Oil (120 oC)
H20 (25 oC)
Steam (100 oC)
Oil (230 oC)
FIG 8.3
mCp ∆T(cooling oil) = mCP ∆T(H20) + mλ (steam)
13.8687x106 = m x 1.88 x 75 + m x 2255
Water required m = 5144.19 Kg
4) Heat exchanger 2:
Steam (100 oC)
Reactor outlet
(285 oC)
(110 oC)
H20 (25 oC)
FIG 8.4
mCp ∆T(products) = m Cp∆T(H20) + mλ (steam)
9.1815x106 = m x 1.88 x 75 + m x 2255
Water required m = 3405.60 Kg
5)Absorber:
Water (50 oC)
Bottom:
H20 (liquid)
Products (gases)
(110 oC)
(110 oC)
Water (25 oC)
FIG 8.5
mCp ∆T(cooling H20) = mλ (condensing water)
m x 1.88 x 25 = 2783.61 x 2228.7
Cooling water required m = 13996.121 Kg
Top:
Water (50 oC)
25
Products (gases)
Products (gases)
(110 oC)
(30 oC)
Water(25 oC)
FIG. 8.6
mCp∆T(cooling H20) = mCp∆T (product gases)
m x 1.88 x 25 = mCp (110-30)
Cooling water required m = 81457.60 Kg
26
9. DESIGN
HEAT EXCHANGER 1
U0A0∆TL = (m CP∆T) OIL
Where U0 = Overall heat transfer co-efficient (KW/m2 oC)
A0= Outside tube area (m2)
∆TL = Logarithmic mean temperature (oC)
∆TL = (230 – 100) – (30 -25)
ln (130/5)
= 38.3659 oC
U0x 2Π x R x L x n x∆ TL = 3852.409
U0 =
1
1/h0 + (A0/Ai) ( 1/hi)
Nu =0 .023 (Re)0.8 (Pr)0.3
Assume that d0 = ¾ “ BWG NO = 16
d0= 0.0191 m
di = 0.0157 m
m = AV ρ
V=m/Aρ
=
(72045.05 /3600)
Π x (0.0157/2)2 x 864.9939
= 119.56 m/s
Nu = 0.023 x (120262.0154) (1.9989)
= 5504.1158
hi = 44.87 kW/ m2 oC
Assume ho = 1.7201 kW/ m2 oC
27
1
Uo =
(1/1.7021) + (1.216/44.87)
Uo = 1.6270 kW/ m2 oC
Assume L = 2.7432 m
1.6270 x 3.14 x 0.0191x111 x 2.7432 x n = 3852.409
n = 147 tubes
HEAT EXCHANGER 2
U0A0 ∆TL = (m CP∆T) PRODUCTS
∆TL = (285 – 100) – ( 110 -25)
ln (185/85)
= 128.584 oC
U0x 2 Πx R x L x n x ∆TL = 2550.4324
U0 =
1
1/h0 + (A0/Ai) (1/hi)
Nu =0 .023 (Re)0.8 (Pr)0.3
Assume that d0 = ¾ “ BWG NO = 16
d0= 0.0191 m
di = 0.0157 m
m = AV ρ
V=m/Aρ =
(51105.03/3600)
Π x (0.0157/2)2 x 900
= 81.517m/s
28
Nu = 0.023 x (138695.051) (0.6795)
= 21676.058
hi = 181.714 kW/ m2 oC
Assume ho = 1.7201 kW/ m2 oC
1
Uo =
(1/1.7021) + (1.216/181.714)
Uo = 1.682kW/ m2 oC
Assume L = 3.048 m
1.682 x 3.14 x 0.0191x128.5842 x 3.048x n = 2550.4324
n = 65 tubes
REACTOR DESIGN
Specification: Packed multiple tubular reactor
Assumption:
Shell diameter of each reactor =39”
= 0.99 m
Tube specifications: 1 1/2" BWG (No 16)
Corresponding number of tubes = 307
Volume of one tube:
ID = 0.03479 m
L = 1.5 m
Volume =Π R2L = Πx0.01742 x 1.5=1.426 x10-3 m3
Volume of 307 tubes =0.4379 m3
Void fraction = 0.4 (assumption)
Volume occupied by catalyst/reactor = 0.4379 x 0.6
= 0.2627 m3
Space velocity = 5 m3 of gas charged to the reactor
(at NTP)
(assumption)
hr- m3 of catalyst per tube
Space velocity for 307 tubes = 1535 m3 of gas charged to the reactor
29
hr- m3 of catalyst
Volumetric flow rate: (at NTP)
No of moles entering the reactor/hr = 1803.43 Kmol/hr
Pressure = 1.1 atm; Temperature = 298 K
R = 0.08206 atm m3 / Kmol K
PV= nRT
V = 1803.43 x 0.08206 x 298
= 40,091.70 m3 of gas/hr
1.1
Volumetric flow rate
= 26.1183 m3
Volume of catalyst =
Space velocity
Number of reactors required = volume of catalyst
Volume occupied by
Catalyst per reactor
= 26.1183/0.2627
= 99.42 ~ 100 reactors
ABSORBER DESIGN
Absorber height Z =Noy x Hoy
Noy = yb - ya
; ∆YL =
∆ YL
(yb-yb *)- ( ya-ya * )
ln ((yb-yb *)/ ( ya-ya * ))
Hoy = Gms / Kya ; where Gms = mass flow rate of gases (Kg/s)
K ya = overall mass transfer coefficient based on
gas phase (Kmol/m3 s )
Calculation of Noy:
ya = 3.13 x 10 –4
xa = 0
yb = 0.0499
xb = 0.4368
30
Kya = 0.4 Kmol/m3s
(assumption)
Gms (ya-yb) =1.32 Lms (xb-xa )
(x,y are mole fractions of HCHO in
liquid and gas phase resp)
xb = 0.5877
yb * = 0.067 xb *
(equilibrium data)
yb * = 0.039
substituting the above values,
∆YL = 0.00298
Noy = 16.69 ~ 17 transfer units
Calculation of Hoy:
Gms = 2764.50 Kg/hr = 0.7679 Kg/ s
Gas density at 110oC = 0.90 Kg/m3
Liquid density = 1000 Kg/m3
Viscosity = 0.0009 Kg/ms
K4 = 0.9;
FP = 1
Mass flow rate per unit area V =
(Kg/m2s )
0.5
K4 ρv (ρl - ρv )
13.1 FP (µ l /ρl )0.1
Substituting the values,
V = 1.4616 Kg/m2s
Column area = Gms/V =0.5252 m2
Column diameter =(0.5252 x 4/∏)0.5 = 0.8179 m
Hoy = Gma/Kya=Gms/(column area x Kya )
= 0.19 m
Calculation of height: (for the top of the absorber)
Z = 17 x 0.19
Z= 3.33m
31
10. PLANT LAYOUT
INTRODUCTION
The economic construction and efficient operation of a process unit will
depend upon how well the plant and equipment specified on the process flowsheet is
laid out and on the profitability of the project with its scope for future expansion.
Plant location and site selection should be made before the plant layout.
Plant location and site selection:
The location of the plant has a crucial effect on the profitability of the project.
The important factors that are to be considered while selecting a site are:
1. Location, with respect to market area
2. Raw material supply
3. Transport facilities
4. Availability of Labour
5. Availability of utilities
6. Availability of suitable land
7. Environmental impact and effluent disposal
8. Local community considerations
9. Climate
10. Political and strategic considerations
1. Marketing area
For materials that are produced in bulk quantities, such as cement, mineral
acids, and fertilizers where the cost of product per tone is relatively low and the cost
of transport a significant fraction of the sales price, the plant should be located close
to the primary product. This consideration will be less important for low volume
production, high-priced products, such as pharmaceutical.
2. Raw materials
The availability and price of suitable raw materials will often determine the
site location. Plants producing bulk chemicals are best located close to the source of
32
major raw material, where this is also close to the marketing area. For the production
of formaldehyde the site should be preferably near a methanol plant.
3. Transport
Transport of raw materials and products is an important factor to be
considered. Transport of products can be in any of the four modes of transport.
4. Availability of labour
Labour will be needed for construction of the plant and its operation. Skilled
construction workers will usually be brought in from outside the site area, but there
should be an adequate pool of unskilled labours available locally; and labour suitable
for training to operate the plant. Skilled tradesman will be needed for plant
maintenance. Local trade union customs and restrictive practices will have to be
considered when assessing the availability and suitability of the local labour for
recruitment and training.
5. Environmental impact and effluent disposal
All industrial processes produce waste products, and full consideration must
be given to the difficulties and cost of their disposal. The disposal of toxic and
harmful effluents will be covered by the local regulations and the appropriate
authorities must be consulted during the initial survey to determine the standards that
must be met.
6. Local community consideration
The proposed plant must fit n with and be acceptable to the local community.
Full consideration must be given to the safe location of the plant so that it does not
impose a significant additional risk to the community on a new site, the local
community must be able to provide adequate facilities for the plant personnel.
7. Land
Sufficient suitable land must be available for the proposed plant and for future
expansion. The land should ideally be flat, well drained and have suitable loadbearing characteristics full site evaluation should be made to determine the need for
piling or other special foundations.
8. Climate
33
Adverse climatic conditions, at a site will increase costs. Abnormally low
temperatures will require the provision of additional insulation and special heating for
equipment and pipe runs.
9. Political and strategic considerations
Capital grants, tax concessions and other inducements are often given by
governments to direct new investment to preferred locations; such as areas of high
unemployment. The availability of such grants can be overriding consideration in the
site selection.
After considering the location of the site the plant layout is completed. It
involves placing of equipment so that the following are minimized:
1.
Damage to persons and property in case of fire explosion or toxic release
2.
Maintenance costs
3.
Number of people required to operate the plant.
4.
Construction costs
5.
Cost of planned expansion.
In plant layout first thing that should be done is to determine the direction of the
prevailing wind. Wind direction will decide the location of the plant.
List of items that should be placed upwind and downwind of the plant is given down.
Items that should be located upwind of the plant.
Laboratories
Fire station
Offices building
Canteen and Change house
Storehouse
Medical facilities
Electrical substation
Water treatment plant
Water pumps
Workshops
34
Items that should be located downwind of the plant
Blowdown tanks
Settling tanks
Burning flares
The various units that should be laid out include
1. Main processing unit
2. Storage for raw materials and products
3. Maintenance workshops
4. Laboratories for process control
5. Fire stations and other emergency services
6. Utilities: steam boilers, compressed air, power generation, refrigeration
7. Effluent disposal plant
8. Offices for general administration
9. Canteens and other amenity buildings,such as medical centers
10. Car parks
1. Processing area
Processing area also known as plant area is the main part of the plant where
the actual production takes place. There are two ways of laying out the processing
area
1.) Grouped layout
2.) Flowline layout
Grouped layout
Grouped layout places all similar pieces of equipment adjacent. This provides
for ease of operation and switching from one unit to another. This is suitable for all
plants.
35
Flowline layout
Flowline layout uses the line system, which locates all the equipment in the
order in which it occurs on the flowsheet. This minimizes the length of transfer lines
and therefore reduces the energy needed to transport materials. This is used mainly for
small volume products.
2. Storage house
The main stage areas should be placed between the loading and unloading
facilities and the process they serve. The amount of space required for storage is
determined from how much is to be stored in what containers. In raw material storage,
liquids are stored in small containers or in a pile on the ground. Automatic storage and
retrieving equipment can be substantially cut down storage
3. Laboratories
Quality control laboratories are a necessary part of any plant and must be
included in all cost estimates. Adequate space must be provided in them for
performing all tests, and for clearing and storing laboratory sampling and testing
containers.
4. Transport
The transport of materials and products to and from the plant will be an
overriding consideration in site selection. If practicable, a site should be selected that
is close to at least two major forms of transport: road, rail, waterway or a seaport.
Rail transport will be cheaper for long distance transport of bulk chemicals.
Road transport is being increasingly used and is suitable for local distribution. Road
area also used for fire fighting equipment and other emergency vehicles and for
maintenance equipment. This means that there should be a road around the perimeter
of the site. No roads should be a dead end. All major traffic should be kept away form
the processing areas. It is wise to locate all loading and unloading facilities ,as well as
plant offices, personnel facilities near the main road to minimize traffic congestion
within the plant and to reduce danger.
5. Utilities
36
The word “Utilities” is now generally used for ancillary services needed in the
operation of any production process. These services will normally be supplied from a
central site facility and will include:
•
Electricity
•
Steam for process heating
•
Cooling water
•
Water for general use
•
Inert gas supplies
Electricity
Electrical power will be needed at all the sites. Electrochemical processes that
require large quantities of power need to be located close to a cheap source of power.
Transformers will be used to step down the supply voltage to the voltages used on the
purpose.
Steam for process heating
The steam for process heating is usually generated in water tube boilers using the
most economical fuel available. The process temperature can be obtained with lowpressure steam. A competitively priced fuel must be available on site for steam
generation.
Cooling water
Chemical processes invariably require large quantities of water for cooling. The
cooling water required can be taken from a river or lake or from the sea.
Water for general use
Water is needed in large quantities for general purpose and the plant must be
located near the sources of water of suitable quality, process water may be drawn
from river from wells or purchased from a local authority.
Offices
The location of this building should be arranged so as to minimize the time
spent by personnel in travelling between buildings. Administration offices in which a
37
relatively large number of people working should be located well from potentially
hazardous process.
Canteen
Canteen should be spacious and large enough for the workers with good and hygienic
food.
Fire station
Fire station should be located adjacent to the plant area, so that in case of fire or
emergency, the service can be put into action
Medical facilities
Medical facilities should be provided with at least basic facilities giving first aid
to the injured workers. Provision must be made for the environmentally acceptable
disposal of effluent.
The layout of the plant can be made effective by
1. Adopting the shortest run of connecting pipe between equipments and the least
amount of structural steel work and thereby reducing the cost.
2. Equipment that need frequent operator attention should be located convenient to
control rooms.
3. Locating the vessels that require frequent replacement of packing or catalyst
outside the building
4. Providing at least two escape routes for operators from each level in process
buildings.
5. Convenient location of the equipment so that it can be tied with any future
expansion of the process.
38
EXTENSION AREA
RAW
MATERIAL
STORAGE
PROCESSING
AREA
C
A
C
N
A
N
T
T
E
E
E
E
N
SAFETY HEALTH
DEPT
CENTER
W
W
O
O
R
R
K
K
S
S
H
H
O
O
P
ADMINISTRATIVE
OFFICE
FINISHED
PRODUCT
STORAGE
SECURITY
OFFICE
MAIN ROAD
FIG 10.1 PLANTENTRY
LAYOUT
39
EXIT
11. MATERIALS OF CONSTRUCTION
Materials of construction may be divided into two general classifications of
metals and non-metals.
11.1 Metals
Pure metals and metallic alloys are included under this classification. Some
commonly used metals are discussed in the following section.
Iron and steel
Although many materials have greater corrosion resistance than iron and steel,
cost aspects favor the use of iron and steel. As a result, they are often used as
materials of construction when it is known that some corrosion will occur.
In general, cast iron and carbon steel exhibit about the same corrosion
resistance. They are not suitable with dilute acids, but can be used with strong acids,
since a protective coating composed of corrosion products forms on the metal surface.
Carbon steel plates for reactor vessels are a good example. This application
generally requires a minimum level of mechanical properties, weldability, formability,
and toughness as well as some assurance that these properties will be uniform
throughout.
Stainless steel
There are more than 100 different types of stainless steels. These materials are
high chromium or high nickel-chromium alloys of iron containing small amounts of
other essential constituents. They have excellent corrosion-resistance and heat
resistance properties.
The addition of molybdenum to the alloy increases the corrosion resistance
and high – temperature strength. If nickel is not included, the low –temperature
brittleness of the material is increased and the ductility and pit type corrosion
resistance are reduced. The presence of chromium in the alloy gives resistance to
oxidizing agents.
Aluminum
40
The lightness and relative ease of fabrication of aluminum and its alloys are
factors favoring the use of these materials. Aluminum resists attack by acids because a
surface film of inert hydrated by aluminum oxide is formed. This film adheres to the
surface and offers good protection unless materials, which can remove the oxide, such
as halogen acids or alkalis, are present.
11.2 Non-metals
Plastics
In comparison with metallic materials, the use of plastics is limited to
relatively moderate temperature and pressures.generally,plastics have excellent
resistance to weak mineral acids and are unaffected by inorganic salt solutions-areas
where metals are not entirely suitable. One of the most chemical resistant plastics
commercially available today is tetrefluoroethylene.This thermoplastic is practically
unaffected by all alkalis and acids except fluorine and chlorine gas at elevated
temperatures and molten metals.
Epoxies reinforced with fiberglass have very high strengths and resistance to
heat. Chemical resistance of the epoxy resin is excellent in non-oxidizing and weak
acids not good against strong acids.
12. INSTRUMENTATION AND CONTROL
Instruments are provided to monitor key process variable during plant
operation. It is desirable that the process variable to be monitored be measured
directly; often however this is impractical and some dependent variable, that is easier
to measure, is monitored in its place. The temperature instrument may form part of a
control loop controlling, say, reflux flow; with the composition of the overheads
checked frequently by sampling and laboratory analysis.
Objectives
The primary objectives of the designer when specifying instrumentation and
control schemes are:
1) Safe plant operation:
41
To keep the process variables within known safe operating limits.
To detect dangerous situations as they develop and to provide alarms and automatic
shut down systems.
To provide interlocks and alarms to prevent dangerous operating procedures.
2) Production rate:
To achieve the design product output
3) Product quality:
To maintain the product composition within the specified quality standards.
4) Cost:
To operate at the lowest production cost, commensurate with the other objectives.
In a typical chemical processing plant these objectives are achieved by a
combination of automatic control, manual monitoring and laboratory analysis.
Guide rules:
The following procedure can be used when drawing up preliminary piping and
instrumentation diagrams.
1.
Identify and draw in those control loops that are obviously needed for steady
plant operation, such as:
Level controls
Flow controls
Pressure controls
Temperature controls
2.
Identify the key process variables that need to be controlled to achieve the
specified product quality. Include control loops using direct measurement of
the controlled variable, where possible, if not practicable, select a suitable
dependent variable.
3.
Identify and include those additional control loops required for safe operation,
not already covered in steps 1 & 2
42
4.
Decide & show those ancillary instruments needed for monitoring of the plant
operation by the operators; and for trouble-shooting and plant development. it
is well worthwhile including additional connections for instruments, which
may be needed for future troubleshooting and development ,even if the
instruments are not installed permanently. This would include extra thermo
wells, pressure tapings, orifice flanges, and extra sample points.
5.
Decide on the location of sample points.
6.
Decide on the need for recorders and the location of the readout points, local
or control room. This step would be done in conjunction with step 1 to 4
7.
Decide on the alarms and interlocks need, this would be done in conjunction
with step 3.
Typical control Systems
Level control
In any equipment where an interface exists between two phases some means
of maintaining the interface at the required level must be provided. This may be
incorporated in the design of the equipment. The control valve should be placed on
the discharge line from the pump.
Pressure control
Pressure control will be necessary for most systems handling vapor or gas.
The method of control will depend on the nature of process.
Flow control
Flow control is usually associated with inventory control in a storage tank or
other equipment. There must be a reservoir to take up the changes in flow rate. To
provide flow control on a compression or pump running at a fixed speed and
supplying a near constant volume output, a by-pass would be used.
Heat Exchangers
Here, the temperature can be controlled by varying the flow of the cooling or
heating medium. If the exchange is between two process streams whose flows are
fixed, by-pass control will have to be used.
43
Cascade control
With this arrangement, the output of one controller is used to adjust the set
point of another. Cascade control a give smoother control in situations where direct
control of variable would lead to unstable operation. The “slave” controller can be
used to compensate for any short-term variations in, say, a service stream flow, which
would upset the controlled variable, the primary controller and long term variations.
Reactor control
The schemes used for reactor control depend on the process and type of
reactor. If a reliable on-line analyzer is available and the reactor dynamics are
suitable, the product composition can be monitored continuously and the reactor
conditions and feed flows controlled automatically to maintain the desired product
composition and yield. More often, the operation is the final link in the control loop,
adjusting the controller set points to maintain the product within specification, based
on periodic laboratory analyzer.
Reactor temperature will normally be controlled by regulating the flow of the
heating or cooling medium. Pressure is usually held constant. Material balance control
will be necessary to maintain the correct flow of reactants to the reactor and flow of
product and unreacted materials from the reactor.
Alarms and safety trips, and interlocks
Alarms are used to alert operators of serious and potentially hazardous,
deviations in process conditions. Key instruments are fitted with switches and relays
to operate audible and visual alarms on the control panels. Where delay or lack of
response from the operator may lead to a hazardous situation, the instrument would be
fitted with trip system to take action automatically to avert the hazard. Interlocks are
included to prevent operations departing from the required sequence. They may be
incorporated in the control system design, as pneumatic or mechanical locks.
44
13. STORAGE AND TRANSPORTATION
Formaldehyde solutions can be stored and transported in containers made of
stainless steel, aluminum, enamel or polyester resins. Iron containers lined with
epoxide resin or plastic may also be used, although stainless steel containers are
preferred, especially for higher formaldehyde concentrations. Unprotected vessels of
iron, copper, nickel and zinc alloys must not be used.
With a decrease in temperature and/or increase in concentration, aqueous
formaldehyde solutions tend to precipitate paraformaldehyde. On other hand, as the
temperature increases, so does the tendency to form formic acid. Trace metallic
impurities such as iron can boost the rate of formation of formic acid. Therefore, an
appropriate storage temperature must be maintained. Stabilizers can also be added to
prevent polymerization. Methanol is generally used as a stabilizer. Other compounds
used as a stabilizer for formaldehyde are ethanol, propanol, urea, melamine, hydrazine
hydrate and bismelamines.
Table 2 Storage temperatures for commercial formaldehyde solutions
Formaldehyde content,wt%
Methanol content,wt%
Storage
temperature,oC
30
7-10
≤1
37
<1
35
37
7
21
37
10-12
6-7
50
1-2
60-65
50
1-2
45
14. HEALTH AND SAFETY CONSIDERATIONS
Sources of human exposure to formaldehyde are engine exhaust, tobacco
smoke, natural gas, fossil fuels, waste incineration, and oil refineries. It is an essential
intermediate in cell metabolism in mammals and humans. All tissues contain
measurable amounts of formaldehyde, e.g., human blood 2-3 ppm.
Formaldehyde causes eye, upper respiratory tract, and skin irritation and is
skin sensitizer. Although sensory irritation, e.g., eye irritation, has been reported at
concentrations as low as 0.1 ppm in uncontrolled studies, significant eye/nose/throat
45
irritation does not generally occur until concentrations of 1 ppm, based on controlled
human chamber studies.
Table 3 Dose – response relationship following human exposure to gaseous
formaldehyde
Exposure level,ppm
Effect
Odor threshold
0.05 – 1.0
Irritation threshold in eyes ,nose, or throat
0.2 – 1.6
Stronger
irritation
of
upper
respiratory
3-6
tract,coughing,lacrimination,extreme
discomfort
Immediate dyspnea,burning in nose and throat,
10- 50
heavy coughing and lacrimation
Necrosis
of
mucous
membranes,
>50
laryngospasm,pulmonary edema
Formaldehyde is classified as a probable human carcinogen by the
International Agency for Research on Cancer(IARC).Lifetime inhalation studies with
rodents have shown nasal cancer at formaldehyde concentrations that are
overwhelmed cellular defense mechanisms,ie,6 to 15 ppm.No nasal cancer was seen
at 2 ppm or lower levels.
Available data do not indicate that formaldehyde produces mutagenic,
tetrogenic, embryo toxic effects in man at concentrations which humans are exposed
to or can tolerate.
46
15. COST ESTIMATION
ESTIMATION OF THE TOTAL CAPITAL INVESTMENT
The total capital investment “I” involves the following:
A: FIXED CAPITAL INVESTMENT IN THE PROCESS AREA, IF
B: THE CAPITAL INVESTMENT IN THE AUXILLARY
SERVICES,IA
C: THE CAPITAL INVESTMENT AS WORKING CAPITAL, IW
i.e., I=IF+IA+W
A. FIXED CAPITAL INVESTMENT IN THE PROCESS AREA, IF
This is the investment in all processing equipment within the processing area.
Fixed capital investment in the process area, IF= Direct plant cost + Indirect plant cost
The approximate delivered cost of major equipments used in the proposed
Formaldehyde manufacturing plant are furnished below:
(Table 4)
S.NO
EQUIPMENT
Cost in Lakhs
3
Cost in Lakhs
/Unit
20
100
3.85
385
UNITS
1
Heat Exchanger
60
2
Reactors
3
Absorption column
1
50
50
4
Deionizer
1
1
1
5
Pumps
3
0.3
0.9
6
Blower
1
0.1
0.1
7
Storage tank sealed
1
1.5
1.5
8
Miscellaneous
1
Total
47
500
DIRECT COST FACTOR (Table 5)
S.No
Items
Direct Cost Factor
1
Delivered cost of major equipments
100
2
Equipment installations
15
3
Insulation
15
4
Instrumentation
15
5
Piping
75
6
Land and building
30
7
Foundation
10
8
Electrical
15
9
Clean up
5
Total direct cost factor
280
Direct plant cost = (Delivered cost of major equipments)
X (Total direct cost factor)/100
Direct plant cost = (500 x 280)/100
= 1400 lakhs
INDIRECT COST FACTOR (Table 6)
S.NO
ITEMS
INDIRECT COST FACTOR
1
Over head contractor etc
30
2
Engineering fee
13
3
Contingency
13
Total indirect cost factor
56
Indirect plant cost = (Direct plant cost) x (Total indirect cost factor)/100
= (1400 x 56)/100
= 784 lakhs
Fixed capital investment in process area, IF = Direct plant cost
+ Indirect plant cost
= 1400 + 784
= 2184 lakhs
48
B.THE CAPITAL INVESTMENT IN THE AUXILLARY SERVICES,IA
Such items like steam generators, fuel stations and fire protection facilities are
commonly stationed outside the process area and serve the system under
consideration.
Table 7:
S.No
Items
Auxillary Service Cost Factor
1
Auxiliary buildings
5
2
Water supply
2
3
Electric main substation
4
Process waste system
1
5
Raw material storage
1
6
Fire protection system
0.7
7
Roads
0.5
8
Sanitary and waste disposal
0.2
9
Communication
0.2
10
Yard and fence lighting
0.2
1.5
Total
12.3
Capital investment in the auxillary services = (Fixed capital investment in process
area) x (Auxiliary services cost )/100
= (2184 x 12.3)/100
= 268.632 lakhs
Installed cost = Fixed capital investment in the process area
+ Capital investment in the auxiliary services
= 2184 + 268.632
= 2452.632 lakhs
49
C.THE CAPITAL INVESTMENT AS WORKING CAPITAL, IW
This is the capital invested in the form of cash to meet day-to-day operational
expenses, inventories of raw materials and products. The working capital may be
assumed as 15% of the total capital investment made in the plant (I)
Capital investment as working capital, IW = ((2184 + 268.632) X 15) /85
= 432.817 lakhs
Total capital investment, I = IF+ IA + IW
= 2184 + 268.632 + 432.817
= 2885.449 lakhs
ESTIMATION OF MANUFACTURING COST
The manufacturing cost may be divided into three items, as follows
A. Cost proportional to total investment
B. Cost proportional to production rate
C. Cost proportional to labour requirement
A. COST PROPORTIONAL TO TOTAL INVESTMENT
This includes the factors, which are independent of production rate and
proportional to the fixed investment such as
-
Maintenance- labour and material
-
Property taxes
-
Insurance
-
Safety expenses
-
Protection, security and first aid
-
General services, laboratory, roads, etc.
-
Administrative services
For all this purpose we shall charge 15% of the installed cost of the plant
=( Installed cost x 0.15)
= 2452.632 x 0.15
= 367.894 lakhs
B. COST PROPORTIONAL TO PRODUCTION RATE
The factors proportional to production rate are
-
Raw material costs
-
Utilities cost-power, fuel, water, steam, etc.
-
Maintenance cost
-
Chemical,warehouse,shipping expenses
50
Assuming that the cost proportional to production rate is nearly 60% of total capital
investment,
Cost proportional to production rate = (Total capital investment x 0.6)
= 2885.449 x 0.6
= 1732.269 lakhs
C. COST PROPORTIONAL TO LABOUR REQUIREMENT
The cost proportional to labour requirement might amount 10% of total
manufacturing cost.
Cost proportional to labour requirement = (367.894 + 1731.269) x
(0.1)/(0.9)
= 233.240 lakhs
Therefore, manufacturing cost = (364.894 + 1731.269 + 233.240)
= 2332.403 lakhs
SALES PRICE OF PRODUCT
Market price of Formaldehyde = Rs.15 /kg
Production rate
= 21196.8 TPA
Total sales income
= 3179.52 lakhs
PROFITABILITY ANALYSIS
A.DEPRICIATION
According to sinking fund method: R= (V- VS) I/ (1+I)n
R = Uniform annual payments made at the end of each year
V = Installed cost of the plant
VS = Salvage value
N = Life period (assumed to be 15 years)
I
= Annual interest rate (taken as 15%)
R
= (2452.632 x 0.15) / ((1+ 0.15)15 -1)
= 51.547 lakhs
B.GROSS PROFIT
Gross profit = Total sales income – Manufacturing cost
= 3179.52 – 2332.40
= 847.117 lakhs
51
C.NET PROFIT
It is defined as the annual return on the investment made after deducting
depreciation and taxes. Tax rate is assumed to be 40%
Net profit = Gross profit – Depreciation – (Gross profit x Tax rate)
= 847.117- 51.547-(847.117x 0.4)
= 456.723 lakhs
D.ANNUAL RATE OF RETURN
RATE OF RETURN = (100 x Net profit) /Installed cost
= (100 x 456.723)/2452.632
= 18.619%
E.PAYOUT PERIOD
Payout period = Depreciable fixed investment /(Profit + Depreciation)
= 2452.632 / (456.723 + 51.547)
= 4.825 years
16. CONCLUSION
The metal oxide process was selected for the manufacture of formaldehyde.
From mass balance and energy balance, the various equipments were designed
and cost estimation was made. The payout period was found to be 5 years. Hence the
project is feasible .
52
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