CONTENT
&No
Title
Page No
Introduction
History ofthe compound
Properties ofthe compound
Uses
Chemistry ofthe processl
11
Process description
15
Flow sheet ofthe process
23
Material balance
24
9
Energy balance
30
10
Design of an equipment
37
11
Materials of construction
42
12
Cost ofthe equipments
45
13
Instrumentation and process control
49
14
Health and safety factors
53
15
Bibtiography
-
INTRODUCTION
N-Alkylated anilines
These are stronger bases than aniline.
N-ethylaniline is a stronger
base than N-methylaniline. This cannot
be explained on the basis of +1
effect of alkyl groups resulting in
increased re§onance of the lone pair
with the ring, since that would to make
N-al lanilines weaker bases
than aniline. It is considered to be due to
the steric effect, which inhibits
resonance of the lone pair on nitrogen and
makes it more available for
motonation. Ethyl group being bigger than
methyl has more steric
effect, so N-ethyl aniline is stronger base
thaiii N-methylaniline. PK3
Values ofsome of these are given below for refer
Base PhNH2 P
pKa
4.58
ncel:purposes,
PhNHEt
PhNMe2
PhNEt2
5.11
5.06
6.56
4.85
Alkylation of Aromatic Compounds:
The catalytic alkylation of aromatic 1
hydrocarbons is
substitution reaction wherein one or more of the
,
hydrogen
atoms on the
ring or on a side chain is replaced by an alkyl
group. Both substituted
•
and unsubstantiated aromatic structures may be so
lated. In general,
the following overall reaction occurs:
A.Ailkw-t;
RTH =
1
CH
1
CH R”
R
catalyst
These reacrtions can occur through elec#iophilic (acid
-catalyzed),
rwcleophilic (base-catalyzed), or free radical
nlechanisms. The catalyst
used dictates the mechanism by which the reaction
As an
occurs.
industrially important proc ss for the manufacture of
useful raw materials for organic syntheses and intermediates,
aniline
methylation has been studied on a number of catalysts. The
products
were found to be N-rnethylaniline (NMA),
N,N--diamthylaniline
(NNDMA) and toluidines. Up till now, however, the reaction
was
3
studied almost exclusively by analyzing the product distribution
in the
gas phase using gas chromatography. No direct observation
of the
working catalyst has so far been activated. Based on in situ
continuous
flow (CF) MAS NMR spectroscopy, we introduced recently a new
"stopped flow"(SF) technique(2,3) which possesses a high potential
for
determining intermediates and calculating here mechanisms of a
broad
variety of heterogeneously catalyzed reactions. The main feature of
this
method is a consecutive in situ MAS NIVIR investigation of the
working
catalyst under flow conditions, stopping the react at flow and
observing
3
the
further
transformation
of adsorbed
compounds
temperatures. In the present work, this
method is
alteration
tgilized for the in situ
investigation of aniline methylation on
acidic zOolite H-Y and new
mechanism was thus proposed.
Runge (1834) demonstrated its presence in
coal-tar. In 1840
4 Fritzsche obtained aniline by the distillation of
indigo wit concentrated
alkali, found its formula to be C H2N and gave
it the name aniline
(Sanskrit, nila=indigo).
Steam distillation to recover,aniline from the reaction
mixture. In
the laboratory aniline is prepared by the reduction of
nitrobenzene with
tin and hydrochloric acid. Actually the aniline is
produced as a complex
salt, phenyl ammonium chlorostannate, from which it
is liberated with
sodium hydroxide.
,
'HISTORY OF THE COMPOUND
Aniline was first produced by Unverdorben in 1982 by dry distiMation
of indigo. in 1840, Fritashe obtained the same oily liquid by heating indigo
with potash, and gave it the name aniline. Hofmann proved the structure in
1843, by showing that ir is obtained by reduction of introbezene. Aniline
occurs in small quantities in coal tar and may also be obtained by
anunonolysis of clilorobenzene, cyclobexanol, or phenol. at present it is
manufactured mainly by catalytic reduction of introbezene obtained aniline by
the distillation of indigo with concertrated alkali, found its formula to be
I-17N,and gave it the name aniline (Sanskrit, nila = indigo).
r
C6-
PROPERTIES OF THE COMPOUND
fllysical properties:
Aniline is miscible with acetone, alcohol, benzene, and ether and is
,oluble in most other organic solvents. Physical properties are given in Table
1 vapor pressures in Table 2, solubility in water is given below.
5
Temperature, C
Parts aniline per 100
parts water
Parts water per 100
parts aniline
25
3.5
5.0
90
6.4
9.9
Physical properties of N-Methyl Aniline
Property
Value
boiling point,'C
196
101.3 k Pa(760 mm Hg)
184.4
4.4 k Pa(33mm Hg)
92
1.2 k Pa(9mm Hg)
71
melting
point,°C
-57
density, d
0.989
at 20/4°C
1.02173
at 15/15°C
1.0268
at 20/20'C
1.029
refractive index, n,
°
1.58545 (2); t.5863
vissociation at 20°C, m Pa-s(cP)
4.423-4.435
••••••
dissociation constant, pK
at 20°C
4.60
at 40°C
7.6
at 60°C
8.88
••
enthalpy of
(kcal/mol)
dissociation,
ki/mol
'
21.7(5.19)
heat of combustion, kjtmol (keal /
3389.72(810.55)
mol)
ionization potential, eV
7.70
4ielectric constant, c at 25°C
6.987
dipole moment at.25°C (called).,am x
5.20(1.56)
10-3°(debye)
'specific heat, 20-25°C
atent of vaporization,
0.518
cal/g)
476.3(113.9)
Iflash point,(closed-cup),'C
78
'Purity
99%
I Formula weight
107.16
“Chemical Properties
Aromatic amines are usually weaker bases than aliphatic amines but
resemble them in many reaction. Heterocyclic compounds are formed by
simultaneous substitutions at the ,amino group and on the arene ring, a
characteristic difference between aromatic and aliphatiO primary amines is the
behaviour towards nitrous acid.
Primary aromatic amines give diazo
compounds which are important intermediates(see Azol dyes).
Addition compounds and complexes are forrbed between aromatic
primary amines and many inorganic substances, such z,ts zinc chloride, copper
chloride, uranimum tetrachloride, or boron trifluoride. Metals react with the
amino group to give metal anilides which are useful intOnediates.
curreptly
About 300 chemical products and intermediates are
buy a dingle process; many
manufactured from aniline. Some are produced
require
others, especially dyes/and pharamaceuticals,
several steps.
agricultural, and
The major uses of =line are in the polymer, rubber,
has decreased markedly in the
i dye in dustries. Demand in the dye industry
increased use of
"United states in the 1970 because of the
sunthetic fabrics and
lists 174 dyes made from
stricter controls by FDA. The colour index *48)
aniline and over 700 dyes prepared .from aniline
/• are now produced in commercially significant
derivatives, very few of these
quantities.
aniline is
About 45% of the total united styates production of
by the rubber industry in the manufacture of antioxidants,
vulcanization
accelerators,
mercaptobenzothiazoles,
such
as
diphenylfuandinF,
untilized
antidegradants, and
thiazoles,
in
particular
difthenylthiourea,
and
condensation products of aniline with various aldehyde.
as antiknock
Important agricultural uses for aniline derivaties include
compounds find use as
compounds in leaded gasolines. Mercaptobezothiazold,
additives to
corrosion inhibitors). Aniline salts are used as moror fuel
prevent
carburetor icing and as rust inhibitors.
manufacture
In the pharamaceutical industry, aniline is needed in the
'controversial sunthetic
of sulfadrugs, aceranilide (antifebrin) and the
eetening agents derved from 2-nitroatiiline in selib,, ral steps with Nt)
cal compounding as
pharmaceut
in
ysed
widely
also
chloride
tylsulfanily1
e
antipyretic and analgesis(see Analgesics).
stimated united states uses of aniline (1975)
Production,%
Use
rethane polymers
1
fubber chemicals
gricultural products
10
iscellaneous
Since the iron-muriatic acid process was specified for the production of
the aniline, the choice between processes was limited to the method of
treatment oif the aniline water, and the optimum temper&tures and pressures of
operation. The treatment of the aniline water by distiOtion is recommended.
This treatment may be carried our in the same still used for the final
distillation.
The daily cost in materials of the nitrobenzene ctraction is $1.87, and
the daily cost in materials of the distillation is $0.3 , as is shown in the
calculations. The labor costs of the two processes ar6 approximately equal,
,
4
9
an, the investment costs, using the same still for the aniliike water treatement
1 alternative exists
arilf for the final distillation, will not differ appreciably. An
!giving
the aniline water no treatment. This would cd8t $24 in materials
ddily, but would involve no investment and no labour costs.
The optimum tempprature of the steam distillation was determined by
plotting a curve of the ratio of vapor pressures against temperature. This curve
goes through a maximum between 90 and 100°C steam distillation at
atmospheric pressure, corresponding to 99°C gives the beat separation possible
arid involves no additional investment for vacuum equipment. These
conditions are also best for the distillation of aniline water.
The final distillation must be carried out at reduced pressures to permit
hezat transfer, since the only steam available has a cond'insation temperature
of 320°F and the final distillation temperature under at4losphere pressure is
365°F. inspection of Fig •8. reveals that at low temperatires the separation of
water in the final distillation is nearly quantitative.
The purity of the aniline from the final distrillatiOln was not specified.
The freezing point is an important criterion of the purl ; therefore the mole
fraction of water that would produce a freezing point 141wering of 0.1T was
Calculated. The value calculated corresponds to anili e containing 0.04%
water by weight.
Although there are other impurities present in the still pot during the
final distillation, they were neglected in the calculations of the final
(
•.•
10
istillation. After an 8-h reaction period with an excess of iron, very little
litrobenzene could be left [1]. The 99% of the theroretical, as obtained biT Mr.
avics in his report on laboratory methods represents of the formation of
-econdary reaction products of the general type
N =N
These azo compounds are solids withour appreciable vapor presseare
at the temperature ofthe final distillation.
The optimum temperature of the separation of the aniline oil and
aniline water in the settling tank was chosen by inspection of the plot that
decreasing the temperature below 40°C does not appreciably change the
compositions of the aniline oil or the aniline water, and does produce a rapid
increase in the time required for the layers to separate.
Differential economic balances of the steam cost versus aniline value
were used to calculate the points to which the steam distillation and the
distillation of the aniline water should be carried. Doubling reducer capacity
and the length of the time cycle, with the consequen increase in instrument
and labor costs, would result in recovery of anilin0 worth $24.00 without
uneconomical steam
consumption. Such additional capacity
is
not
recommended in view of the necessity for immediate production at low
investment cost.
10Jgripligkrfloorwripviq
11
CHEMISTRY OF PROCESS
sulphuric acid
1. By heating aniline and methyl alcohol together with some
under pressure.
H2SO4
1
C61-15-NH-CH3+ H20
C6H5-N-H + HO-CH3
A, pressure N-methylaniline
and reducing the
2. By condensing aniline with formaldehyde C142-0
product with zinc and NaOH.
2H
-H20
C H5-NH2 + 0—CH2
lo-C6145-NH-CH3
C6I-1 -N—CH2
inirNaOH N-methylaniline
N-methylaniline is a colourless liquid, bp 194°C. it is a some what
stronger base (K = 7.1 x 10.10) owing to partial aliphatic character. Its
reactions are those typical of aliphatic secondary amines excepr the
substitution reaction in 0-and p-positions of the benzene ring. It react with
nitrous acid to form a pale-yellow nitrosoamine which gives liebermann
nitroso reaction.
C6H5
\\N-H + HO-NO
CH3 /
N-methylaniline
C6H5,
-NO + H20
CH3 A
N- nitrosomethylaniline
7',
12
When its hydrochloride is heated the methyl group pligrates to the para
position ofthe ring, forming p-toluidine hydrochloride.
NH-CH3.1-10
CH3rearanges
NH2E0
P-toluidine hydrochloride
N-methvlaniline hydrochloride
N Methylaniline is used for making certain dyes.
Mechanism of meth:Oat-ion of aniline on acidic zeolite WY
K3
K2
I PhNH_%r Or
LOU 1
N H2CR.%t
(39
MINI.CH*031 CrE
(58 ppm)
LOH
K4
aniline
(gas phase)
--.
1-111"TrA
C'p.;)2
(48*PO
P hN
•
NM
(gas phase)
NNI*V1 A
(gas pPsase)
N-Alkylation:
A wide variety of methods are available for *paring N- alkyl and
the
N,N-dialkyl derivatives of aniline. Several are used cd)mmercially (1). In
trifluoride,
presence of a catalyst, such as copper-alumina, nigkel, boron
transition metal zeolite, or sulfruric acid (2-5) methanol gives yields of Nmethylaniline as high as 96% (6). The N,N-dimethyl compound is prepared by
(7) or
heating aniline with excess methanol and a catalyst such as sulfuric
13
yields Nosphoric acid at high pressure, under similar conditions, thanol
ylaniline and N,N-diethylaniline (7-8). Low — pressure, vapor-phase
alkylation
lations with other catalysts have been studied (9). Some ring
f
bcurs concurrently with N-alkylation.
alkylated
Alkyl halides sulfates, sulfites, and phosphates also yield
only.Long-chain
imilines. Most of these reactions are of acadarnic interest
kyl halides, oleyl, and
cetyl bromides, eg, from only monoalkylated
(10), sometimes
Oerivatives. Alkyl dihalides, eg, a, a' — dibromo-0-xylene
give ring closure.
aniline with
N-alkyl derivatives can also be obtained by treating
pressure to
- metallic sodium (11). Followed by reaction with an olefin at high
(100 atm)
form eg, N-ethyl or N,N-diethylaniline, at pressures below 10Mpa
, the monosubstituted product predominates.
fractional
Mixtures of N-alkylanilines can usually be " parated by
separated by
distillation. The methyl and ethyl derivatives have been
product with pconverting the monoalkyl compound to a nonvolatile reaction
toluenesulfonic acid (12)r phthatic anhydride (13).
'
, • 01,
4,4t
•
- 14
pressure and at a
Passing aniline vapor over activated alumina under
Ammonium chloride.or
terperature abover 450°C gives diphenylamine (14).
4-,•••
are recommended as
alumina impregnated with ammonium fluoride (15)
cat,alysts (see alkylation).
Alkylation:
For example, 2-Ring substitution occurs under certain conditions.
ettwlaniline [103-69-5], 2,6-diethylaniline [579-66-8], or
mixtures of the two
N-ethyl derivative is heated
are obtained in high yield when aniline or its
the prosence of aluminum
withethylene at 200-300°C under high pressure in
aniline (16).
the
Mixture of N-and P-alkyl anilines are usually
ajor products of the
hexenes'4 in the presence of
reaction of aniline with butanes penetenes and
at 210-270T (17).
aniline hydrocholoride or aniline — cobalt salt complexes
:
,
and small amounts
Ring suostitution predominates, unless an excess of anilirlle
of catalyst are employed.
N-Alkylanilines rearrange to C-alkyl isomers; higher alkyl groups
[589-16migrate more readily than lower. N-ethylaniline gives P-Ohylaniline
2] at 200-300°C in the presence of aniline hydrohalides(Hofmann — martius
rearrangement) or the metal salt complexes (Reit4ty — Hickinbottom
rearrangement).
linommimmESIMMIEINESIMINENSWAIMAIOi? COTS,•••••
•
1- 5
OCESS DISCRIPTION
ig ne of process
:
••
•
action of
Nitrobenzene is reduced to aniline in the liquid phase by the
•
•
•
in :0 and ferrous chloride in aqueous solution.
iron sludge by
Most of the aniline is then separated from the
sludge is Iremoved by steam
decantation and the aniline remaining in the
into twk3 phases-an queous
distillation, the condensate from which separates
called
phase, called "aniline water", and an oil phase,
"aniline layer". Here by
methylation of aniline and there it
the addition of methanol, it under goes
forms methyl aniline.
aver from
Methyl aniline remaining in the excess water left
extraction with
oi)erations may be removed by distillation or by
all process
nitrobenzene.
The crude aniline is refined by distillation.
Apparatus and Raw Material Used
The laboratory reductions were carried out in a ,small insulated iron
reducer of 1500 cc capacity equipped with stirrer and ja ker for heating. The
top was closed with the exception of necessity outlets* for a vented reflux
condenser, iron
addition, nitrobenzene
addition, thermometer
well,
decantation, etc., Nitrobenzene was added from a glassii charing flume • The
crude aniline layer was decanted by suction.
,•
•
- 16
carried • out in the reducer and
Steam distillation of the residue was
resulting
ditillation of the aniline water from the
1 000 cc round bottom glass flasks
glass Erlenmeyer flask receivers.
distillate was carried out in
equipped with suitable glass condensers and
Alternative handling of such aniline water by
out in
e)itraction with nitrobenzene was carried
1000 cc separatory funnels.
carried out in a 1000-cc glass
Distillation of the crude aniline was
condenser and
distillation flask quipped with suitable
receiver.
cast iron indicate that they are
Tests made on copper monel metal and
all sufficiently resistant to the reduction
so that their life would be determined
action. Besides the
more by mechanical than chemical
metals mentioned steel
subsequent operations. Cuprous alloys cause
was found to be suitable for all
discoloration of aniline.
,
Nitrobenzene, iron boring and lime of the same quality as
proposed for
large-scale operations:were employed.
commercial grade
Reagent grade concentrated HCI was used as no
reason to anticpate that
material was immediately available. There is no
commercial
variation in behaviour would be caused by use of
quality acid.
Properties of raw materials:
5.7C, boiling
Nitrobenzene. Light yellow liquid crystallizing point
essentially 100% l'Auriatic
point 210.0°C at 760cm flash point 77°C, assay
MOM
••
• • •••
•
• • • ••
• •,•
••
,• ,
,r15%,
17
specific gravity at
Acid 18°C Be. Light yellow liquid, assay 27.92% liel,
15 C=1.1417.
4,
Iron Borings:
and also free
Appearance-clean cast iron borings free from large lumps
form oil and grease. Packed in 100ib cloth bags.
Findings
10 mesh
None
40 mesh
90%
80 mesh
90% minimum
Hydrated line:
gross contaminant.
Good commercial grade free from sand and other
Packed in 50 lb paper bags.
Experimental Reductions:
From the expthimental charges run in the laboratory, the following
procedure is recommended for large scale application.
To the 1500 cc iron reducer 390 g of aniline -water recovered from
previous reduction charge are introduced. The ferrous cNoride catalyst is then
made up by adding with stirring 90 g fresh iron boring together with 60 g of
iron recovered from a previous reduction and treating :with 32.0 cc of HCI
having a specific gravity of 1.1885 at 15.6°C. The mixture is then heated with
Steam
continued stirring until evolution of hydrogen ceases arid reflux starts.
18
is
is them turned off the reducer jacked and continuous nitrobenzene feed
stwrted at such a rate that 500g are added over a period of4 h. 450 g more iron
aie added in 12 g portions every portions every 5 min starting
simultaneously
wIth the addition of nitrobenzene. At the end of the nitrobenzene addition
the
reaction is 90% complete.
After the conversion we get aniline, which is then added with a
the presence of
successive amount of methanol which forms methyl aniline in
H2SO4
finishing Reductions
at
After the addition of nitrobenzene has been corrIpleted a reflux of
least 88 cc h at a vapor temperature between 95 and 100*c
must be maintained
reduction
continuously in order to finish the reduction in 3h. comlleteness of
may be judged by testing purity of the methyl aniline in
sample with drawn
from the reducer using color and solubility in dilute HCI criteria.
When finishing the mass is neutralized with 5 g of hydrated lime. It is
then allowed to settle for 1 h at a temperature not less th
75°C. a supernatant
crude methyl aniline layer containing 80% of the aniline produced separates
practically free of sludge. This methyl aniline layer is dcanted and set aside
for refining.
Reductions were made with as little as 390 g and as much as 600 g of
aniline water in all cases obtained a decantable layer.
3
'1111111011011S0,40CL gik
•
19
The yield in the reduction stage is 99% of theory.
It was particularly noticeable that whenever the reduction reaction was
. 1.-uggish in the early stages due to low temperature, poor agitation, or
1
deficiency of catalyst there was a tendency for unreduced nitrobenzene to
accumulate in the reducer. Later in the cycle of these sluggish charges a rapid
acceleration of reaction took, place in some cases creating enough pressure in
the reducer to blow out one of the stoppers and forcibly eject much of the
'contents.
Recovery of Residual N- Methyl Aniline from the Reducer Sludge:
N- Methyl aniline remaining in the sludge may be recovered in several
ways, all of which are described in the literature. The recommended method is
simple steam distillation. While laboratory measurements, of the steam
* distillate volumes were made from several typical experiments, it would be
impracticable to base the economics of plant design upon this data. It should
rather be derived from theoretical considerations.
Up to the solubility limit of N-Methyl aniline in water the partial
pressure of water follows Raoult's law and that of N-methyl aniline, Henry's
law. Up to the solubility limit of water in N-methyl aniline the partial pressure
of N-methyl aniline follows Raoult's law and that of water, Henry's law.
„
In this connection the setting rate of N-methyl aniline from mixtures
obtained by such steam distillation was noted. An aniline and water mixture
* containing a large excess of aniline was steam distilled and samples of
0:1
20
distillate were caught in a cylindrical vessel to a depth of 16 in. by varying the
••••
temperature ofthe distillate the following data were obtained.
Distillate temperature(C)
Time Required to settle into district layers (s)
55
139
2800
After the steam distillation is complete the spe4t sludge is poured into
a 100-cc beaker from which it overflows to the dram. The un reacted iron
settles to the bottom of the beaker and is washed by swirling a water hose
down, in the beaker close to the surface of the settled iron until salts, iron
oxide, etc., are washed away. The iron recovered is used in a subsequent
reducer charge.
Recovery of N- Methyl Aniline from the aniline water
Two alternative methods for recovering anitin0 from the aniline water
were investigated, namely, distillation and extractio# with nitrobenzene. As
both methods were employed quite successfully in thetlaboratory, choice must
be made between them for plant application.
21
The apparent distribution coefficient for N- methyl aniline in the
1,
iystem nitrobenzene-water between 25 and 55*C was found to be 18 assuming
o dissociation of aniline in either layer.
Refining of Crude N- Methyl Aniline
Crude aniline obtained from the three steps in the process just decribed
was combined and distilled in glass. Pure NMA was collected after first
removing water and wet aniline. An end fraction of impure NMA was finally
separated.
Distillations were carried out at atmospheric pressure and at reduced
pressure. Boiling points of NMA at the various pressures were in substantial
agreement with the data in the literature covering aniline and water.
The first experiments were carried out using direct distillation with no
fractionation. Under these conditions it was found that the distilled NMA was
appreciably colored and its crystallizing point was slightly low unless unduly
large foreruns and end fractions were separated. A small fractionating column
'
packed with glass helices (calculated to be equivalent to three theoretical
plates) was then used and a large proportion of NMA of satisfactory quality
was obtained. A reflux of half the forward flow was maintained while the pure
aniline was being distilled. Fractions were separated as nearly as possible by
boiling point and color of distillate. It is suggested that on the plant scale these
fractions can be more accurately controlled and separated by crystallizing
point while giving proper consideration to color.
,
22
It was found possible to carry the pure NMA fraction to a point
where
still. At this point distillation- was
Only 5% of the charge was left in the
removing the residue.
opped and a fresh charge of crude was added without
residue
14.fter some five successive charges has been run the
was stripped, by-
passing the fractionating column. A quantity of colored impure
bbtained amounting to 1% of the total crude charged.
NMA was thus
This material should be
ladded to a reducer charge because of unreduced materiali
present.
The nonvolatile residue was dry powdery material
consisting largely of
NMA charged. The net
iron oxide and amounting to 0.25% of the crude
charOd.
distillation loss was found to be 2% of the NMA
Laboratory data on
of water is not considered
the size of fractions taken off for elimination
preferably,be
reliable for use in plant design which should
'values.
based on calculated
TEMA",BALANCE
1 mole of Nitro benzene reacts with Hydrogen to give 1 mole of
tune.
X moles of Nitrobenzene reacts with Hydrogen to give 8.9605 Kg
moles of Aniline.
bC = 8.9605 Kg moles of Nitrobenzene.
3 rtioles of Hydrogen reacts with Nitrobenzene to give 1 mole of Aniline.
b-. k moles of Hydrogen reacts with Nitrobenzene to give Y moles of Aniline.
8.9605 Kg moles of Aniline.
X
=3Y
= 3(8.9605)
= 26.8815Kg moles of Hydrogen
Wtight of Hydrogen
Kg moles of Hydroge0 x Molecular
Weight
cc
26.8815 x 2
53.765 Kg/hr.
Weight of Nitrobenzene
Kg moles of Nitrobet4ene x Molecular
weight
8.9605 x 123
1 102.1415 Kg
'v.
,401Shfig610,0
25
ater
1 mole of Nitrobenzene reacts with Hydrogen to give 2 moles of m;ater.
i, X moles of Nitrobenzene reacts with Hydrogen to give Y moles of water
SoY=2xX
8•9605Kg moles of nitrobenzene
2 x 8.9605
17.921 Kg of water.
ethanol
1 mole of Methanol reacts with aniline to give 1 mole of Methyl
• • X = 8.9605 Kg moles of Methanol.
Weight of methano
K,moles of Methanol x Mplecular Weight
8.9605 x 35
2286.76 Kg
Reactor
In reactor vapour phase reduction of Nitrobenzeno takes place with the
litwsAp of catalyst.
•
1102•14Kg/hr NB
833.3Kg/hr Aniline
53.7 Kg/hr H2
322.5! Kg/hr Water
6428 Kg/hr CuCO3
6428 Kg/hr CUCO3
Reaction Tank
Here we add Methanol in the presence of H2SO4 at 500°K
and also
arried out at some pressure. Methylation of aniline takes place in
this tank.
286.76Kgthr Methanol
954.3317kg/hr Methyl Aniline
833.33Kg/hr Aniline
487.4981K
322.5 Water Kg/hr H2
6428 Kg/hr CuCO3
Water
6428 Kg/hr CuCO3
Evaporator
Excess benzene is evaporated and required amount of Nitro benzene is
obtained. 1350 Kg/hr of Nitro benzene is reduced to 1102.1415Kg/hr. Liquid
stream in 13500 and output is 13748Kg/hr.
i
1 10 1415 Kg/hr NB
1350 Kg/hr NB
3.76 Kg/hr H2
—OW EVAPORATOR
13500 Kg/hr Liquid
stream
Compound
53.76 Kg/fir H2
13748 Kg/hr Liquid
stream
Input(Kg/hr)
Output(Kg/hr)
Nitrobenzene
1350
1 102.1415
Hydrogen
53.76
53.763
Liquid Stream
13500
13748
27
Heat exchanger
No specific change of mass takes place and so the materials that go
in'ide will come out as the same. Steam added is 10000kg/hr. Liquid stream
is'cooled and are get 14060.43 Kg/hr.
954.33Kg/hr Methyl
aniline
)054.33 Kg/hr Methyl Aniline
HEAT
10000Kg/hr Steam
0.10000 Kg/hr Steam
EXCHANGER
14060.43Kg/hr I420
O 14060.43 Kg/hr H20
10 Kg/hrI-12(hot)
0,10 Kg/hr 1-12(hot)
Compound
Input(Kg/hr)
Methyl aniline
utput(Kg/hr)
954.33
954.33
Steam
10000
10000
Water
14060.43
14060.43
•
H (hot)
10
Condenser
Cooling water nearly 5000Kg/hr is circulated throu h the condenser to
cool the products. No specific change of mass occurs here.
954.33Kg/hr Methyl
aniline
14060.43Kg/hr H20
954.33 K
Methyl Aniline
-So-14060.43 Kikthr H20
10 Kg/hr H2(hot)
10 Kg/hr H2(hot)
5000 Kg/hr Coolant
(water)
5000 Kelt Coolant
(water)
28
, 954.33
Methyl aniline
Water
H2(hot)
Coolant(water)
,
•
Output(Kg/hr)
Input(Kg/hr)
Compound
954.33
14060.43
14060.43
10
10
5000
5000
Cooler
This behaves same as that of the condenser and,so there will be no
change in the materials or mass that goes in.
954.33 Kg/hr Methyl Aniline
954.33Kg/hr Methyl O.
aniline
14060.43Kg/hr H20 to.
COOLER
14060.43 <.g,/hr H20
10 Kg/hr
10 Kg/hr H2(hot)
5000 Kg/hr Coolant
•
(water)
Compound
Methyl aniline
Water
H2(hot)
Coolant(water)
-0- 5000 K
10.
(hot)
Coolant
(water)
Input(Kg/hr)
Output(Kg/hr)
954.33
954.33
14060.43
14060.43
10
10
5000
5000
Distillation column
954.33 Kg/hr Methyl
aniline
14060.33 Kg/hr H20
10 Kg/hr H2
954.* K
DISTILLATION
COLUMN
•
Methyl
aniline
14066.33 Kg/hr H20
10 Kg/hr H2
WI, WM fg
29
Compound
Methyl aniline
Water
Input(Kg/hr)
Output(K
954.33
954.33
14060.43
14060.43
H2(hot)
10
Extraction column
4
Here Methyl aniline is extracted and solvents are added. We get water
and Nitro Benzene about 21060.43Kg/hr.
954.33 Kg/hr Methyl —4.
aniline
1406033 Kg/hr H20
DISTILLATION
COLUMN
-
954.33 Kg/hr Methyl
aniline
21060.93 Kg/hr Nitro
benzene 6id water
7000 Kg/hr Nitro
benzene
Compound
Methyl aniline
Water
Input(Kgihr)
04tput(Kg/hr)
954.33
954.33
14060.43
.21060.93
Nitrobenzene
7000
30
ENERGY BALANCE
Datum temperature
25°C
Specific heat of hydrogen
6.62 + 0.0081 T
Q
=
m Cp AT
where
Q is heat required in Kcal.
m is the mass material in Kg/hr.
Cp is specific heat in Kcal / Kg K.
AT is temperature difference in degree Kelvin.
So Q is to be calculated for every compound that enters.
Q
=
m x
where
ms is the mass in kilograms
Xs is latent heat of vapourization.
EVAPORATOR BALANCE
Heat Input
Compound
Mass
Specific
Heat
•
Nitrobenzene
1350
0.365
Water
13500
rn 2= 1300 x 657.5 x 0J56 493519
Hydrogen
53.763
3.2961
2463.75
105
18606.86
Total
4956 65.764
Heat Output
Mass
compound
Nitrobenzene
1102
Water
13748
Specific
Heat
AT
0.475
Q
91603.75
ms Xs ----
13.748 x 763.3.5 x
5834579.71
175
31654.239
Total
59578373
0.556
Hydrogen
53.763
Heat liberated =
3.364
1001571.936 Kcal
HEAT EXCHANGER
Heat Input
Mass
Compound
Specific
Heat
AT
225
Methyl
Aniline
954.33
0.512
Water
14060.43
ms
Hydrogen
10
3.3845
Steam
10000
m A= 10000 x 166.5
x 0.5 6
= 14060 x 3 x 589.9
x 0.5.56
225
Total
95999.616
5781897.57
925740
925740
6811252.254
32
Heat Output
Mass
Compound
Specific
Heat
AT
225
100266.2651
:---- 14060 x 3 x 714.028
x 0.556
5584112.214
Methyl
Anilinç
954.33
0.512
Water
14060.43
ms-
Hydrogen
10
3.3845
Steam
10000
7962.975
25
10000x 589.9
x 0.5 6
8972185.455
Total
Heat liberated
3279844
2160933.201 Kcal
CONDENSER
Heat Input
•••••••,
Specific
Heat
Mass
Compound
AT
235
954.33
0.512
Water
14060.43::
in
Hydrogen
10
3.3885
Coolant
5000
ms
Coolant
5000
1.013
100266.26
Aniline
= 14060.43 x 714.028
x 0.556
235
= 5000 x 1044.96
x 0.556
5584112.214
7962.975
2906692.95
5
25307.5
Total
8624341.89
Heat Output
Mass
toinpoimd
Specific
Heat
AT
Q
40374.83
85
Mehl
Aniline
954.33
0.57
Water
14060.43
ms k,= 14060 x 958.76
x 0.556
Hydrogen
10
3.328
Coolant
5000
ms
7495279.39
2828.8
85
1985754
'---- 5000x 763.3
x 0.556
9524237.201
Total
Heat liberated = 899895.1255 Kcal
COOLER
Heai Input
Mass
Compound
Specific
Heat
AT
Mehyl
Aniline
954.33
0.57
Water
14060.43
m X,= 14060 x 958.76
x 0.556
7495279.39
Hydrogen
10
3.328
2828.8
Coolant
5000
ms
Coolant
5000
1.013
85
85
---- 5000x 1044.96
x 0.556
40374.83
2906690
25307.5
Total
10470480.52
34
Heat Output
•
Specific
Heat
Mass
Compound
Mehyl
Aniline
954.33
0.495
Water
14060.43
in
Hydrogen
10
3.329
Coolant
5000
ms
Coolant
5000
1.013
Q
AT
5
2062.4917
14060x 958.76
x 0.556
8173863.99
5
164.8
'----- 5000 x958.76
x 0.556
2665380
71166.88
10912638.16
Total
Heat liberated = 442157.6433 Kcal
DISTILATION COLUMN
Heat Input
Mass
Compound
Specific
Heat
AT
2062.4917
M6hyl
AnIline
954.33
0.495
Water
14060.43
ms
Hydrogen
10
3.328
5
164.8
Water
14060.43
1.013
5
71166.88
Total
8247258.172
= 14060 x.1044.96
x 0.556
8173863.99
35
Heat Output
Compound
Mass
Specific
Heat
AT
Mehyl
Aniline
954.33
0.495
Water
14060.43
ms s = 14060 x 1044.96
x 0.556
8173863.99
Hydrogen
10
3.328
5
164.8
Water
14060.43
1.013
5
71166.88
Total
8247258.172
Heatliberated = 0 Kcal
EXTRACTION COLUMN
Heat Input
ompound
Mass
Specific
Heat
Mehl
Aniline
954.33
0.495
Water
14060.43
ms
Solvent
7000
036
Water
14060.43
1.013
AT
2062.4917
= 14060 x 1044.96
x 0.556
5
To
8173863.99
Cif
Heat Output
Mehyl
Aniline
954.33
Water
14060.43
Solvent
Water
14060.43
2062.4917
'--- 14060x 1044.96
x 0.556
0.365
12775
1.013
71166.88
Total
Heat liberated =0 Kcal
8173863.99
8260458.91
,
37
DESIGN OF SINGLE EFFECT EVAPORATOR
Evaporator:
The evaporator used in the process is a single effect cup. So the
step in designing the single effect evaporator is to find the area and
1st
diameter.
= 13,500 kg/hr
= 18606.92 Kcal
R.
= 53.763 kg/hr
Sks
=11.A All
=(1350013600)X 103 x 1529.5448
= 800xAx
280 — 200
(280'\
in
2,00i
A
=
30.155
Area
=
30.155 m2
Area
=
(7t/4) D2
30.155
=
( /4)D2
0
=
6.1963m
Diameter of
drum
No. of Tubes:
A
tDe LN
=5
ft
=1.524m
•••
4„0,'''1001111
38
Di
=2"
=0.0508 m
4. 30.15523
= 7C X 0.0508 x 1.524 N
=123.98
124
Steam Inlet diameter:
Mass flow fate ofsteam = 13500 kg/hr
Vol. Flow fate = Mass flow rate/density
13,500 / 3600
928.05
= 4.0407 x l0 m3/Sec
Area = volumetric flow rate / velocity
= 4.0407 x
/ 15
= 2.6938 x 10-4 m
D
= 0.01851m
Steam Inlet Diameter =0.01851 m
Feed Inlet Diameter:
Volumetric flow rate = mass flow rate / density
= 1350 / 3600
1205
= 3.112x 10-2
Area = volumetric flow rate / velocity
3.112 x 10 -4/ 2.4
Diameter
Feed Inlet diameter
= 0.01138 m
= 0.01138 m
39
Product outlet Diameter:
Volumetric flow rate =mass flow rate / density
— 1102/3600
1205
= 2.5403 x104 H13 /Sec.
Area =volumetric flow rate /velocity
= 2.5403 x 104
2.4
= 1.0584 x 104 m2
Diameter = 0.0116 m
Product outlet diameter ----- 0.0116 m
Vapour outlet diameter:
Voltunetric flow rate =mass flow rate / density
= 53.7613600
0.969
= 0.2149 x 104 I113 /Sec.
Area = volumetric flow rate /velocity
= 0.2149 x 104
30
= 7.1647 x i0-3 m2
Diameter = 0.0955 m
vapour outlet diameter = 0.0955 m
•
40
Assumption:
Vent diameter
= 0.025 m
Height ofthe drum
= 10m
4,
Dimensions:
, Diameter of drum
=6 m
Height of drum
= 10m
Feed inlet diameter
= 0.0113 m
Steam inlet diameter
= 0.01851 m
Vapour outlet diameter
= 0.0955 m
Product outlet diameter
= 0.0016 m
Vent diameter
= 0.002 m
•
--ti*Vapour -output
diameter
Steam inlet)
diameter
Condensate+-----(
Feed inlet
diameter-÷(
--1-* Product output
diameter
•
•
•
•
•
••
•
•
•
42
MATERIAL OF CONSTRUCTION
-In selection of material of construction for a particular 4 ystem it is
important first to take into consideration "CHARACTERISTId8 OF THE
SYSTEM The "MATERIAL" from which the system is to be fAricated are
second important consideration.
On designing and fabricating the equipment, pipelines, ractors etc. a
,•
to the material of constructibn. Some of
i
i should be given
good consideraton
the consideration is given below:
1. The material should be able to withstand the corrosion resistance(i.e)
from fluid corrosion.
,•
2. The material must be withstood in the parameter of temperature,
pressure, velocity and concentration.
3. In selecting the materials for construction the service life pf material is
important.
4. When considering the pipelines, it should be leakage proof.
5. The material used in constructing bolts,joints etc. must avoid galvanic
•
corrosion.
6. The materials used for construction should withstand t high & low
temperature i.e. from rain and heat,
by
7. In information on resistance of Metals and alloys, icorrosion
butylenes in its various forms.
43
Reactors:
The reactor are encountered in process. There reactors are operates at
high temperature. So proper consideration should be made while slecting
material pf construction of reactors. Consideration must be given not only to
strength & mechanical properties but also to resistance of corrosi n.
For this regard carbon steel can well used up to 650°C. Above this
temperature scaling rate increases. So to, improve the quantity this carbon
steel we can add chromium to it.
Piping:
To handle the fluid at high temperature from reactor & absorption in
plants, cast iron pipes are used. Insulation is provided using glass wool are
used. Insulation is provided using glass wool, which is furthe!r, covered by
concrete,
For general transport purpose cast iron or stainless steel pipes may be
used. Care should be taken when joints are to be made with 1)(110 or flanges or
butts. While giving joints,, materials used should be closed:members of piping
metal in Galvanic series occurs.
Generally carbon steel is suitable for most plant equipmentprocessing
butylenes or similar hydrocarbons. Special construction materials may be
essential in certain other circumstances. N-butance hydrogeilation vessel,
surface are exposed to high temperature & steam.
ZSV irrrflVt,',F:Y14
44
Nickel steels are said also to be responsible for coke
formation in nbutane dehydrogenation. High chrome alloys steel are used tor
construction Of
(
catalyst grides in a houdry process cermic cataluyst supportI,
n place of steel
are also recommended to prevent carbon deposition. Most of
solvents used are
relatively non-corrosive with exception of furfural foi;
which special
inhibition have been used together with staineless steels ip
particular plant
areas carbon steel is suitable too in a cuptous ammonium cetate
extraction
plant but brass, copper or bronze alloys must be avoided.
4
45
COST OF EQUIPMENTS
1.,Tank Unit
a. Steel tanks without agitators, per pound of metal in shell heads and jacket.
500 gal
$0.20
5000 gal
0.17
15000 gal
0.14
b. For additional features multiply the above base figure by the following
factors and add to the base figure.
Rubber-lined steel
0.8
Copper or bronze
1.5
Havg
2.0
In place of steel
Glass enameled, stainless steel (18-8),
Nickel or monel Metal
2.5
For agitator and motor drive
1.0
1. Cast iron flat bottom reducers including agitator and motor idrive
For 10 ib/in2 internal operating pressure, bottom and lo'wek portion of side
wall Jacketed for 50 ibiin2 operating pressure. All reducers are 'equipped with a
6-in discharge outlet extending through the jacket at the bo om of the side
wall and they may be equipped with any specified number of, cover openings
consistent with the size ofthe cover.
• - •-• "',(1_ • •
Ii
Nominal size
1000 gal
1500 gal
2000 gal
Tank diq x
'3" x 6'6"
depth
5'9" x 7'6"
6'6" x 8'0"
Jacketed
height
'10"
3'3"
3'6"
Installed
value
$4500
$6000
$7000
7'0" 8'6"
$7806
2. Pump units made of cast iron with motor, installed
Capacity 5,0 gal/min
$600.00 each
Capacity 200 gal/min
700.00 each
Capacity 500 gal/min
800.00 each
For alloy construction such as bronze monel and nickel mulPply by
2.0.
3. Instruments
For temperature, pressure, or depth:
Per point of use
Glass factory thermometers and
indicating pressure gauges
$20.00
Distant indication oftemperature,
depth or pressure
100400
Recording and control instruments
150.00
Flow meters, reeording type
400.00
47
4. Ventilating equipment with motor, installed
Installed cost per ft3/min of air moved:
5.
1000 ft3
$0.25
5000 ft3
0.10
20000 ft3
0.06
Vacuum pumps
The following standard starn jet exhausters are,available having,:capacities
as indicated in ft3 free air (atmospheric pressure, 60°F)/mm, exhausted from a
system at indicated absolute pressure operating with 75 ib steam presIsure.
a. Single stage in 3 Sizes. Price, $250.00 each any size.
Capacity at
Size
6.
Steam
consumption
80mm
100mm
100mm
275 lb/h
1.5 ft3
7.5
20.d
190 lb/h
0.5
3.0
13.0
95 lb/h
0.4
1.5
6.0
Heat exchangers, steel shell and tube type
On the basis oftubular heat exchange surface:
100 ft3
$5.00/ft2
250 ft3
3.00/112
500'ft3
2.50/ft2
48
7. For steel pipe coil heating surface in tanks, etc-$4.00/ft2
Factors for other metals as under heat exchangers.
8. Fractionating Columns steel
2' diam
3' diam
4' diam
5
'diam
Bubble cap units, per
$150.00
plate
$240.00
$350.00
$450.00
Packed
1 column
units, per ft of 80.00
packing height
150.00
220.00
300.00
9.
Filter presses; cast iron
100 ft2
$10.00/ ft2filtering area
300 ft2
7.00/ ft2 filtering area
500 ft2 4.00/ ft2 filtering area
,41001:4",t3
INSTRUMENTATION AND PROCESS CONTROL
One of the basic concept in chemical engineering is the existence of
steady state for a flow system. This impiles that if all input all opOrating and
environment factor's are held constant for a long enough period of thine.
Some factors change continually such as temperature of ilibient ait
and the temperature of cooling water. Besides the environrnent41 changes
these are usually changes in the feed composition when raw m terials are
obtained from different sources they will vary considerably. Even those
obtained from the same source. will differ,from batch of batch. Anotiler type of
abrupt upsei!occurs when there is a failure ofsame utility or machir4.
The purpose of process control is to ensure whatever possibl ,the plant
can contain!io operate safely efficiently and profitable regardless of'iwhat upset
occurs.
Oftett the through pup at various processes steps in a plan different,
even though on paper they were designed to be the same. The could tresult in
an inadequate amount offeed to one unit while the another unit the teed rate is
too great to be handled property.
Manual or automatic control
Most system can be controlled manually as automatically. The modem
trend to automate the process a s mysch as possible is that automatic controller
always repond the some way to chanes whereas non are erratic. Controller
A
50
may work for!years with only minor maintenance whereas a man fOtigue is
easy. This means that while controller may not producea better prodlict than
an alert man they came in the long run produce a more uniform proolict with
less waste ad fewer accidents.
Product quality
The scope has specified the quality of the product. To obtain this
quality certaini 'items must be accurately controlled. The process engineer must
look at the pt'Ocess and determine. The process engineer must look at the
process and ddtermine what step control what qualities.
Initially the rzteaction is carried at high temperature and td ensure
purity temperature musty be reduced accurately and economically.
Product quantities
Besides the quality of various streams their quantity rrmst be
controlled. If the product bins ar nearly full the production rate triust be
slowed down. Later after a number of shipments to customers have ben made
the rate may be increased. This is called material balance control.
Variable to be measured
The ideal variable to 'measure in one that can be maintainea easily,
1
o'
inexpensively quickly and accurately. In maintenance of Butylene variables to
measured are
,
51
1. Temperature
2. Composition
3. Final control element
Manipulating
variable the element that makes that changes in the van:able is
called ' the final control elements. The use of controller mauy also reduce
overall expenses.
,f
Some plants can be operated essentially without any people. However
for safety prop9se there are two employees per shift. This impiles ihat the
plant can be over operated.
Control .ystein
A control system consists offour stages. First the item to be co#trolled
and must be measured. This reading must then be compared with same desired
value called the set point depending on the result of this comparison a 6cision
must be made whether some variable in the process should be change4. Then
if a change is indicated the amount of change required must be determined and
it must be institated.
Material balanced control
The amount of product sold may vary occasionally or random
The
usual way to adjust for this I to increase or decrease the feed tate to the
system; according to expected demand for the product size of the woduct.
inventory. The altering of the rate increases the feed to each of the succ'teding
units and outputs is changed.
52
Temperature heat transfer
The clriving force in any heat exchanger is the temperature difference.
Changing this difference can quickly change the ratge of heat trarl4fer. A
tempered system is designed too quickly and can accurately conttol the
temprature of an input stream. This system requires the source of feed, one
must be above the desired temperature and the other below it. Theses are
mixed together to obtained the desired temperature.
,•
t.
This carrhe done using a ratio controller.
•;'
•
•••
'411, cAr4
HEALTH AND SAIITY FACTORS
The cherrfical and physical situations that can result when operating
with hazardous materials should be understood so these materials may be
handled safety.
When organic chemical are involved in the reaction. The care should
be taken to avoid hazardous in the process during the reaction.
Safety:
Safety is rapidly emerging from a modest chrysalis of inji4ry
prevention to become a profit spinner supreme in the guise of damage and
to be
total loss control. tiandling hazards of butylenes are not considered
concentration. Its
serious. However butylenes has an effect at high
may vary
physiological effect at high concentration. Its physiological effect
respiratOry
with individual. It has an irritating effeOt on skin eyes & upper
allowable
passage and any cause nausea. The ,recommended maximum
/
volu0e.
concentration of butylenes for an 8-hour exposure is 1000 PPM by
air
Butylene is extremely flammable & potentially explosive when mixed with
explosive limiting being 2-11.5% by volume. •
Butylenes forms peroxide when in contact with air for example 1120
°in
PPM of peroxide was/ formed in Butylene saturated with jar at r
develOped
temperature. Over a period of 24-hr peroxide content of 460 PPM
when temperatureS concentration increased to 500 C. Peroxide formation is
prevented by exclusive of air or is minimized by use of inhibitor.
Fire and explosion hazards:
Butylenes is highly flammable & consequently must be handled &
stored with normal appropriate precautions including adequate ventilation,
elimination of naked lights & sparks and provision of correct fire fighting
equipment.
• • •.,
•
'
t•
.",,Arrww,itntk,
55
BIBLIOGRAPHY
1. Encyclopedia of chemical Tech. Vol.2
2. Choply and Hick, Hand book of Chemical Engineering Calculation
McGraw Hills.
3. Chemical Engineering Hand book, Don Perry
4. Industrial Chemicals. Faith.
5. Process calculations and principles. Hougen, Walson and Ragatz Vol
IL
6. Unit operations of Chemical Engineering — McCabe and Smith
7. P.H. Grokgins, Unit process in Organic Synthesis 5th edition McGraw
Hills.
8. Ind. Engineering Chemicals Production Research Development. A.K.
Bhattacharyya and D.K. Naudi.
9. Organic Chemistry. P.L.Soni.
10. Organic Chemistry. Arun Bahr and K.S. Bahl.
1 1. Hougen and Watson. Industrial chemical calculations.
12. Fuson, ar anic chemistry.
*OHM07.,
• Mr.,