Vinyl Chloride

Laxminarayan Institute of Technology 2015

CHAPTER ONE: INTRODUCTION

[1,2]

Vinyl Chloride is an organochemical with the formula CH2CHCl that is also called as Vinyl Chloride Monomer (VCM) or Chloroethene. It is one of the world’s most important commodity chemicals. Chlorinating hydrocarbons is the basic idea behind the production of vinyl chloride monomer (VCM).Chlorinated hydrocarbons (CHCs) is much more resilient to biodegradation, unlike simple hydrocarbons. This is due mainly to the inherent strength of the C-Cl bond. Consequently, man-made CHCs are beginning to accumulate in the environment. However, production of VCM is essential to the production of polyvinyl chloride (PVC). Construction materials made of PVC are light, low-maintenance, and long lasting. About 13 billion kilograms of VCM are produced annually. About 25% of the world’s total chlorine production is required for its production. VCM is among the top twenty largest petrochemicals (petroleum-derived chemicals) in world production. The United States currently remains the largest VCM manufacturing region. China is also a large manufacturer and one of the largest consumers of VCM. VCM is an OSHA regulated material. Chloroethylene is a colourless gas at normal temperature and pressure. Industrially it is handled as liquid with boiling point 259.6K. No Human contact with the material is allowed as it is highly toxic, flammable, and carcinogenic. It can also be formed in the environment naturally when soil organisms break down chlorinated solvents.

HISTORY The early history of vinyl chloride has been documented by Justus von Liebig and his student Henri Victor Regnault at the university of Giessen, Germany and Justus won the distinction of being the first person to synthesis vinyl chloride. In the 1830s, he reacted the so-called oil of the Dutch chemists, dichloroethane with alcoholic potash to make vinyl chloride. Victor confirmed his discovery and was allowed to publish it as sole author in 1835. Vinyl Chloride Monomer

Page 1


In 1872, E. Baumann observed that white flakes precipitated from vinyl chloride upon prolonged exposure to sunlight in a sealed tube. This material was further investigated in the early 1900s by Ivan Ostromislensky, who named it Kauprenchlorid. (cauprene chloride), and gave it the empirical formula (C 2H3Cl)16. However, vinyl chloride was of little commercial interest until Waldo Semon’s work with plasticized PVC for the B. F. Goodrich Company beginning in 1926. Some years earlier, Fritz Klatte had developed the first practical route to vinyl chloride while looking to find uses for acetylene for Chemische Fabrik Griesheim-Elektron. This process, in which hydrogen chloride is added to acetylene over a mercuric chloride catalyst, was patented in 1912, By 1926, Griesheim Elektron had concluded that the patent held no commercial value and allowed it to lapse. Klatte’s process eventually formed the basis of the vinyl chloride industry for many years from its beginnings in the 1930s. From 1940-1950 on, acetylene could be replaced by ethylene, from which vinyl chloride was produced by direct chlorination to 1,2 dichloroethane and subsequent thermal cracking.

Vinyl Chloride Monomer

Page 2


In 1872, E. Baumann observed that white flakes precipitated from vinyl chloride upon prolonged exposure to sunlight in a sealed tube. This material was further investigated in the early 1900s by Ivan Ostromislensky, who named it Kauprenchlorid. (cauprene chloride), and gave it the empirical formula (C 2H3Cl)16. However, vinyl chloride was of little commercial interest until Waldo Semon’s work with plasticized PVC for the B. F. Goodrich Company beginning in 1926. Some years earlier, Fritz Klatte had developed the first practical route to vinyl chloride while looking to find uses for acetylene for Chemische Fabrik Griesheim-Elektron. This process, in which hydrogen chloride is added to acetylene over a mercuric chloride catalyst, was patented in 1912, By 1926, Griesheim Elektron had concluded that the patent held no commercial value and allowed it to lapse. Klatte’s process eventually formed the basis of the vinyl chloride industry for many years from its beginnings in the 1930s. From 1940-1950 on, acetylene could be replaced by ethylene, from which vinyl chloride was produced by direct chlorination to 1,2 dichloroethane and subsequent thermal cracking.


Page 2


CHAPTER TWO: HEALTH AND SAFETY FACTORS & PROPERTIES

[1]

HEALTH AND SAFETY FACTORS 1) OSHA lists vinyl chloride as a Class IA Flammable Liquid. Because of its low boiling point, liquid VCM will undergo flash evaporation upon its release to atmospheric pressure. It has a wide flammability range from 3.6 to 33% by volume in air. As a gas mixed with air, VCM is a fire and explosion hazard on o n standing VCM can form peroxides, which may then explode. explode. 2) Contact with liquid vinyl chloride can cause frostbite. Chronic exposure to vinyl chloride at concentrations of 100 ppm or more is reported to have produced Raynaud’s syndrome. Chronic exposure has also reported to have produced a rare cancer of liver (angiosarcoma) in a small number of workers after continued exposure for many years to large amounts of vinyl chloride gas. 3) Short term exposure is limited limited to 5 ppm averaged over any 15 min period. period. Contact with liquid vinyl chloride is prohibited. Where concentrations cannot be lowered below the 1 ppm, the employer must establish a regulated area with controlled access. 4) Vinyl chloride also poses a significant fire and hazard explosion. Large fires of compound are very difficult to extinguish, while vapours represent a severe explosion hazard. 5) Because hazardous peroxide can form on standing vinyl chloride in air, especially in the presence of iron impurities, vinyl chloride should be handled and transported under an inert atmosphere. The presence of peroxide from vinyl chloride and air can initiate polymerization of stored vinyl chloride. 6) Vapours of vinyl chloride are more than twice as dense as air and tend to collect in low lying areas, increasing the risk of fire. Workers entering these low lying areas risks suffocation, which can occur at levels above 18,000 ppm. The mild, sweet odour of vinyl chloride becomes detectable around 250 ppm.


Page 3

Laxminarayan Institute of Technology 2015 USES AND ECONOMIC ASPECTS

(1) Vinyl Chloride has gained worldwide importance because of its industrial use as the precursor to PVC. It is also used in a wide variety of copolymers. The inherent flame retardant properties, wide range of plasticized compounds and low cost of polymers from vinyl chloride have made it a major industrial chemical. (2) About 95% of current vinyl chloride production worldwide ends up in polymer or copolymer applications. (3) Vinyl chloride also serves as starting material for the synthesis of a variety of industrial compounds, as suggested by the number of reaction in which it can participate, although none of these applications will likely ever come anywhere near PVC in terms of volume. (4) The primary nonpolymeric uses of vinyl chloride are in the manufacture of vinylidene chloride, vinyl stearate and tetrachloroethylene.


Page 4


PHYSICAL AND CHEMICAL PROPERTIES OF VINYL CHLORIDE : PROPERTY

VALUE

Molecular weight

62.4985

Melting point (1atm), K

119.36

Boiling point (1atm), K

259.25

Heat capacity at constant pressure, J/(mol.K) 0 Vapour at 20 C 0 Liquid at 20 C

53.1 84.3

Critical Temperature, K Critical Pressure, MPa

432 5.67

Critical Volume, cm3/mol

1.79

Critical compressibility Autoignition temperature, K

0.283 745

Acentric factor

0.100107

Dipole moment, C-m

4.84E-30

Enthalpy of fusion (melting point), kJ/mol. Enthalpy of vapourisation (298.15), kJ/mol.

4.744 20.11

Enthalpy of formation (298.15K), kJ/mol.

41.95

Explosive limit in air, vol% Lower limit Upper limit

3.6 33

Gibbs energy of formation (298.15K), kJ/mol Vapour pressure, kPa 0 -30 C 0 -20 C 0 -10 C 0 0C Viscosity, mPa.s 0 -40 C 0 -30 C -200C 0 -10 C Explosive limit in air, vol%

49.3 78.4 119 175 0.345 0.305 0.272 0.244 4-22

Table no: 1 Physical and chemical properties of vinyl chloride.


Page 5


IMPORT DATA OF VINYL CHLORIDE

[3]

SR.NO

YEAR

QUANTITY(TONNES)

1

2007

114988

2

2008

120303

2

2009

154636

4

2012

180202

5

2013

189036

Table No: 2 Import data of Vinyl Chloride. 350000

300000 y = 12654x - 3E+07 R² = 0.9435

250000 s n o t n i y t i t n a u q

200000

150000

100000

50000

0 2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

Year

Figure no.1: Projected Increase in Demand of Vinyl Chloride


Page 6


MAJOR PRODUCERS OF VINYL CHLORIDE IN INDIA. Sr.no.

Industries

Design capacity(TPA)

1.

IPCL, Vadodara

57300

2.

IPCL, Dahej

170000

3.

NOCIL,

30,000

4.

RIL, Hazira

270000

5.

Finolex Pipes Limited, Ratnagiri

240000

6.

DCW Ltd.

100000(MT)

Table no.3: Major Producers of Vinyl Chloride in India.


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CHAPTER THREE: MANUFACTURING PROCESSES

[2]

Early the Industrial production of vinyl chloride is based on only two reactions: (1) Hydrochlorination of acetylene:

C2H2 + HCl

ᵒ

CH2 = CHCl , ΔH = -99.2 KJ/mol

(2) Thermal cracking of 1, 2-dichloroethane:

CH2CH2 + Cl2

Cl-CH2 –CH2-Cl

Cl-CH2 –CH2-Cl

CH2 = CHCl + HCl , ΔH =100.2 KJ/mol

ᵒ

Acetylene hydrochlorination was mainly used in the past, when acetylene produced via calcium carbide from coal, was one of the most important basic feedstock for the chemical industry. However with time and large scale production of ethylene-derived polymers, such as polyethylene and polystyrene and the general trend toward natural gas, naphtha and gas oil as basic feedstocks. The cracker capacity increased substantially and ethylene became readily available at very competitive prices. Besides the economical disadvantage of the higher priced hydrocarbon feed, the acetylene hydrochlorination has the drawback of not being balanced on the chloride as a chlorine source. With increasing demand for vinyl chloride and technical progress, the first balanced processes were established in the 1940s and 1950s, when acetylene was partially replaced by ethylene, which was converted to 1,2-dichloroethane and subsequent thermal cracking. The hydrogen chloride from cracking could then be used for acetylene hydrochlorination:

C2H4 + Cl2

C2H4 Cl2

C2H4 Cl2

CH2 = CHCl + HCl


Page 8


C2H2 + HCl

CH2 = CHCl

C2H2 + C2H4 + Cl2

2CH2 = CHCl

By direct use of crack gas, without separation of ethylene and acetylene, this process still pursued with some modifications. With the introduction of the first large scale oxy-EDC p lant by The Dow chemical in 1958, a balanced process based only on inexpensive ethylene became available and found rapid acceptance within the chemical industry. In this direct chlorination of ethylene, pyrolysis of EDC and oxychlorination of ethylene are combined for the production of VCM, with no net consumption or production of HCl.

Direct chlorination: CH2 = CH2 + Cl2

EDC pyrolysis: CH2 = CH2 + 2HCl + ½ O2

C2H4Cl2

C2H4Cl2 + H2O

Oxychlorination: 2C2H4 Cl2

2CH2 = CHCl + 2HCl

Overall Reaction: 2CH2 = CH2 + ½ O2 + Cl2

2CH2 = CHCl + H2O


Page 9


SELECTION OF PROCESS

[1, 4]

The normal method of producing acetylene was from calcium carbide. The high-energy requirement for carbide production was a serious drawback to the continuing mass production of vinyl chloride by this method. Along with that, the major issue with this process is that fact that the catalyst used, mercuric chloride, is a very volatile compound which causes environmental problem. The relative inexpensiveness of ethane has lead to many attempts to develop a process that will use ethane to directly produce vinyl chloride. In this processes oxychlorination is required. Although possible, this process has not progressed beyond the conceptual stage. This is due to the fact that the oxychlorination reactor design presents a severe challenge in terms of materials of construction because o

the reaction temperature may go up to 500 C. At this temperature chlorine becomes very aggressive to most construction materials. Along with it, the major problem associated with the use of ethane is its molecular symmetry. In particular, the addition of chlorine to ethane gives rise to a wide product spectrum. Ethylene can be converted to vinyl chloride in a single stage, i.e., without isolating the intermediate ethylene dichloride by either chlorination or oxychlorination routes, as is the case with the balanced ethylene route. Direct chlorination routes require a high temperature and a large excess of ethylene to minimize soot formation. The common problems with the direct routes of production are poor selectivities to vinyl chloride and substantial production of chlorinated by-products, many of which have no direct commercial utility. Hence commercially mainly the balanced method is used.


Page 10


CHAPTER FOUR: PROCESS DESCRIPTION

[1, 4]

The process chosen for vinyl chloride production is a combination of three processes, direct chlorination, EDC pyrolysis and oxychlorination. This process is referred to as the balanced process. Direct chlorination by itself is a process that operates at lower temperatures and produces fewer by-products when compared to oxychlorination. Oxychlorination process uses all the HCl produced during EDC pyrolysis in vinyl chloride production.

(1) Direct Chlorination: CH2 = CH2 + Cl2

C2H4 Cl2

(2) EDC Pyrolysis: CH2 = CH2 + HCl + ½ O2

(3) Oxychlorination: C2H4 Cl2 Overall:

C2H4 Cl2 + H2O

2CH2 = CHCl + HCl

2CH2 = CH2 + ½ O2 + Cl2

2CH2 = CHCl + H2O

On this basis, EDC production is about evenly split between direct chlorination and oxychlorination, and there is no net production or consumption of HCl.

4.1 DIRECT CHLORINATION: Ethylene and chlorine combine in a homogeneous catalytic reaction to form EDC. Normally, the reaction rate is controlled by mass transfer, with absorption of ethylene as the limiting factor. Due to high selectivity, ferric chloride is the common catalyst of choice for chlorination of ethylene. The catalytic reaction utilizes an electrophilic addition mechanism. The catalyst polarizes chlorine and then the polarized chlorine molecule acts as an electrophilic -

reagent to add Cl to the double bond of Ethylene. EQUATIONS: 1. FeCl3 + Cl2 -

2. FeCl4 - Cl+ + CH2=CH2


+

FeCl4-Cl

FeCl3 + ClCH2CH2Cl

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e t d l i r c u y o d l n i h o r V C p

n m u l o c g n i t a r e p e S e d i r o l h c l y n i V s d n e t h g i L

n m u l o c g n i t a r e p e s l C H

) C 7 ( h c n e u Q 0 0 s i s y l o r y p C D E

) n m u l o C . n t s i D ( n m u l o C g n i t a r a p e s d n e t h g i L

r e t a w e t s a W

C ) D C 0 E 0 7 e ( d r u e r t C n a t e c e W D

s e s a G t n e V

e l c y c e r C D E

) s K i s 3 y l 2 o 7 ( r y e p c a C r n D u E F

r o t a r e p e S s d n e y v a e H h c n e u Q

) K 3 0 5 ( r o t c a e R n o i t a n i r o l h c y x O n e g y x o

e n e l y h t e

) K 3 5 3 ( r o t c a e R n o i t a n i r o l h c t c e r i D l C H

e n e l y h t E

e n i r o l h c

FIG.2: TYPICAL (GEON) BALANCED VINYL CHLORIDE PROCESS WITH OXYGEN BASED OXYCHLORINATION.


Page 12

Laxminarayan Institute of Technology 2015 Conversion of the limiting component is essentially 100% and selectivity to EDC is greater than 99%.The direct chlorination reaction is very exothermic and requires heat removal for temperature control. Early direct chlorination reactors were operated at moderate temperatures of 0

50-65 C to take advantage of lower by product formation, and utilized conventional water cooling for heat of reaction were devised. A widely used method involves operating the reactor at boiling point of EDC, allowing the pure product to vaporize and then recovering heat from the condensing vapour or replacing one or more EDC fractionation column reboilers with the reactor itself.

4.2 OXYCHLORINATION OF ETHYLENE : When compared with direct chlorination, the oxychlorination process is characterized by higher capital investment, higher operating costs, and slightly less pure EDC product. However, use of the oxychlorination process is dictated by the need to consume the HCl generated in EDC pyrolysis. In oxychlorination, ethylene reacts with dry HCl and either air or pure oxygen to produce EDC and water. Various commercial oxychlorination processes differ from o ne another to some extent, but in each case but in each case the reaction is carried out in the vapour phase in either a fixed or fluidized bed reactor containing a modified Deacon catalyst . Oxychlorination catalyst typically contains cupric chloride as the primary active ingredient, impregnated on a porous support. CuCl2 is widely recognized as the active chlorinating agent. The CuCl produced during the ethylene chlorination step is rapidly reconverted to CuCl is thought to be advantageous because it readily complexes with ethylene, bringing it into contact with CuCl 2 under reaction conditions, and the presence of some CuCl is thought to be advantageous because it readily complexes with ethylene, bringing it into contact with CuCl2 long enough for chlorination to occur. A very simple represented of this heterogeneous catalytic cycle. EQUATION: 1.

CH2=CH2 + 2CuCl2

2.

½ O2 + 2CuCl

3.

2HCl + CuOCuCl2


2CuCl + ClCH2CH2Cl CuOCuCl2 2CuCl2 + H2O

Page 13

Laxminarayan Institute of Technology 2015 Usually fixed bed multitubular reactor is used for oxychlorination.

Fixed- vertical

tubes held in a tubesheet at top and bottom. Uniform packing of catalyst within the tube is important to ensure uniform pressure drop, flow and residence time through each tube. Reaction heat can be removed by the generation of steam on the shell side of the reactor or by some other heat transfer fluid. Fixed bed oxychlorination generally operates at higher temperature (2300

300 C) and pressure (150-1400 KPa). In the air-based oxychlorination process with either a fluidized or fixed bed reactor, ethylene air are fed in slight excess of stoichiometric requirements to ensure high conversion of HCl and to minimize losses of excess ethylene that remains in the vent gas after product condensation. Under these conditions, typical feedstock conversion are 9499% for ethylene and 98-99.5% for HCl.bed reactors resembles multitube heat exchangers, with the catalyst packed in. The use of oxygen instead of air in the oxychlorination process with either a fixed or fluidized bed reactor, permits operation at lower temperatures and results in improved operating efficiency and product yield.

4.3 PURIFICATION OF ETHYLENE DICHLORIDE FOR PYROLYSIS: EDC used for pyrolysis to vinyl chloride must be high purity, typically greater than 99.5% because the cracking process is highly susceptible to inhibition and fouling by trace quantities of impurities. It must also be dry to prevent excessive corrosion downstream. Direct chlorination usually produces EDC with purity greater than 99.5%, so that except for removal of the FeCl3, little further purification is necessary. Ferric chloride can be removed by adsorption of a solid or the EDC can be distilled from the FeCl3 in a boiling reactor as noted above. EDC from the oxychlorination process is less pure than EDC from direct chlorination and requires purification by distillation. It is usually first washed with water and then with caustic solution to remove chloral and other water extractable impurities. Subsequently, water and low boiling impurities are taken overhead in a first distillation co lumn and finally pure dry EDC is taken overhead in a second column


Page 14


4.4 ETHYLENE DICHLORIDE PYROLYSIS: Thermal pyrolysis or cracking of EDC to vinyl chloride and HCl occurs as a homogeneous, first order, free radical chain reaction. The accepted general mechanism involves the four steps as follow:

(1) Initiation:

ClCH2CH2Cl

(2) Propagation: Cl + ClCH2CH2Cl

ClCH2C.HCl (3) Termination: Cl + ClCH2CH2

ClCH2CH2 + Cl

ClCH2CHCl + HCl

CH2 = CHCl + Cl CH2 = CHCl + HCl

The endothermic cracking of EDC is relatively clean at atmospheric pressure and at 0

temperatures of 425-550 C. Commercial pyrolysis units, however, generally operate at pressure of 1.4-3 MPa and at temperature of 475-5250C to provide for better transfer. EDC conversion per pass through the pyrolysis reactor is normally maintained at 53-63%, with the residence time of 2-30s. Quenching of pyrolysis reactor effluent quickly minimizes coke formation. Substantial yield losses to heavy ends and tars can occur if cooling is done too slowly. Therefore the hot effluent gases are normally quenched and partially condensed by direct contact with cold EDC in a quench tower. Alternatively the pyrolysis effluent gases can first be cooled by heat exchange with cold liquid EDC furnace feed in a transfer line exchanger prior to quenching in the quench tower. Although there are minor differences in the HCl-vinyl chloride recovery section from one vinyl chloride producer to another, in general the quench column effluent is distilled to remove first HCl and then vinyl chloride. The vinyl chloride is usually further treated to produce specification product, recovered HCl is sent to the oxychlorination process and unconverted EDC is purified for removal of light and heavy ends before it is recycled to the cracking furnace. The light and heavy ends are either further processed, disposed of by incineration or other


Page 15

Laxminarayan Institute of Technology 2015 methods or completely recycled by catalytic oxidation with heat recovery followed by chlorine recovery as EDC.


Page 16


CHAPTER FIVE: THERMODYNAMICS The

science

of

thermodynamics

deals

with

energy

and

its

[5]

transformation.

Thermodynamics finds extensive application in chemical engineering. In chemical processes like synthesis ammonia from mixture of nitrogen and hydrogen, thermodynamics enables us to determine the maximum yield of ammonia obtained under given condition of temperature and pressure. Thermodynamics also helps to lay down the criteria for predicting feasibility or spontaneity of a process, including a chemical reaction, under a given set of conditions. It also helps to determine the extent to which a process, including a chemical reaction, can proceed before attainment of equilibrium. From the values of standard free energy change, we formulate an approximate criterion for the feasibility of chemical reaction, which will be useful in preliminary exploratory work. It would be worthwhile to have some idea about whether or not the equilibrium is favourable, before we search for catalyst and other condition necessary to cause the reaction. If the react ion is not thermodynamically feasible, there is no point in pursuing a long and expensive experimental investigation on improving the rate of equation. Therefore, to determine the feasibility of a chemical reaction Gibb’s free energy change of chemical reaction is determine and the conditions for the feasibility of a chemical reaction are mentioned below: o

ΔG < 0, the reaction is promising.(543) 0 < ΔGo < 40,000 kJ/kmol, the reaction may or may not be possible and needs further study. o

ΔG > 40,000 kJ/kmol, the reaction is very unfavorable. o

ΔG = 0 (reaction is in a state of equilibrium), reaction proceeds t considerable extent before equilibrium is reached. Reactions: 1) CH2=CH2 + Cl2 2) CH2=CH2 + 2 HCl + ½ O2 1) Cl CH2-CH2 Cl


Cl CH2-CH2 Cl Cl CH2-CH2 Cl + H2O CH2=CH Cl + HCl

Page 17

Laxminarayan Institute of Technology 2015 Data: Enthalpy and free energy of various compounds at standard temperature.

COMPONENT

H

o

298

(

Ethylene

 

o

)

G

298

(

54.19

 

)

50.7

Hydrogen chloride

-22.063

-22.769

Ethylene dichloride

-39.44

-19.506

8.4

12.31

-68.311

-56.689

Vinyl chloride Water

Now, ΔH

o

T

 ΔH

T

o

T1

  CP dT T1

 ΔH o T  ΔαT  T1  

Δβ

1

 ΔH o T  ΔH '  ΔαT 


Δβ 2

T2 

 3

2 3

T

2

 T1   2

T .......(1) , where

 3

(T 3  T 1 ) 3

ΔH '  constant

Page 18


POLYNOMIAL CONSTANTS FOR VARIOUS COMPONENTS

COMPONENT

ALPHA

BETA

GAMMA

Chlorine

0.2914E-5

0.0918 E-5

0.949E-3

Oxygen

0.291 E-5

0.1004 E-5

2.526 E-3

Water

0.3336 E-5

0.2679 E-5

2.6105 E-3

Ethylene

0.3338 E-5

0.9479 E-5

1.596 E-3

Hydrogen chloride

0.2916 E-5

0.0905 E-5

2.0938 E-3

Vinyl chloride

0.4236 E-5

0.8735 E-5

1.6492 E-3

Hydrogen

0.2762 E-5

0.0956 E-5

2.466 E-3

Carbon monoxide

0.2911 E-5

0.0877 E-5

3.0851 E-3

Carbon dioxide

0.2937 E-5

0.3454 E-5

1.428 E-3

Ethylene dichloride

37.275

0.14362

1.04 E-5

[6]

Now,

∆∝

Reaction

∆

∆

Direct chlorination

37.27499

0.1436

-2.5346E-3

Oxychorination

37.279

0.1435

-4.426E-3

Pyrolysis

-37.2749

-0.1436

3.723E-3

Enthalpy and free energy of reaction is given by H

o 298

=

G

o 298

=

∑∆ ∑∆ ∑∆ ∑∆


-

-

Page 19


∆

REACTIONS

Direct Chlorination

H

o

(

298



∆

)

-391.91E6

G

o

298

(



)

-293.86E6

Oxychlorination

-493.176 E6

-340.54 E6

Pyrolysis

107.897 E6

37.868 E6



For Direct Chlorination:

Put T = 298 K

∆



∆ ∴ ∆ − ∗    ∴ ∆ −   ′

′

=

= 391.9 10 ′

Since,

dlnK dT

−



0.1436× 298 0.1436× 298 + 37.2749 ×298+ + 2 3

391900

=



/

ΔH o

RT ..........................(1)

This gives,

lnK  Also, ΔG

o

298

 ΔH' RT



Δα R

lnT 

Δβ

TA 2R

 RTlnK

∆  ∆ − ∆− ∆  − ∆  −   −   − =

+

………… (2)

At T = 298K

293.86× 10

= +

×298

391.9 × 10

2.5346× 10 6


×298

 −

37.2749× 298 298



.1436×298 2

Page 20


 ∆ −



= 329.152 × 10

Putting D in eqn (2), At T = 353K

 ⁄ 

= 293.861 × 10

.

As the free energy is negative, therefore the reaction is feasible. 2) Oxychlorination

Similarily,

∴∴ ∆ −   ⁄  ∆ − ′

= 493154

/ kmolK.

= 512.272


= 492.937 × 10

.

As the free energy is negative, therefore the reaction is feasible. 3) Pyrolysis

Similarily, We get,

∆

∴ ∆ −

′

=

 

= 126949.91


 ⁄ 

= 30.87× 10

.

As the free energy is negative, therefore the reaction is feasible.


Page 21


CHAPTER SIX: MATERIAL BALANCE

[7]

Production capacity of vinyl chloride is 100 tonnes/day. Molecular weight of vinyl chloride is 62.5. Thus production capacity is 66.66 kmoles/hr. Basis : 1 hour of operation.

∴  ℎ = 100

= 100×1000×

 .

= 4166.667 Kg/hr. = 66.666 Kmoles Now, the conversion of EDC after pyrolysis is 58%.

∴ ℎℎ

=

  . .

= 114.9425 kmol/hr

= 11379.31 Kg/hr. 50% of Ethylene dichloride is formed from oxychlorination and rest from direct chlorination.

MASS BALANCE ON DIRECT CHLORINATION REACTOR: Ethylene and chlorine dissolve in the liquid phase and combine in homogeneous catalytic reaction to form Ethylene dichloride. The limiting reactant is ethylene with 100% co nversion.

∴

Ethylenerequired =

= 57.47126

ℎ

114.9425 2

.

Chlorine is taken in 3.5% excess.

∴

Chlorine required = 57.47126 × 1.035


Page 22

Laxminarayan Institute of Technology 2015 = 59.4268 Kmol/hr.

∴ ℎ − ∴ ℎℎ = 59.4268

57.47126

= 2.011494 Kmol/hr.

= 57.47126

 ℎ /

Now taking mass balance on the reactor :

REACTANTS IN:

COMPONENT

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Ethylene

57.47126

28

1609.195

Chlorine

59.4268

71

4223.276

TOTAL

116.954

5832.471

PRODUCTS LEAVING:

COMPONENT

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Ethylene dichloride

57.47126

99

5689.655

Chlorine

2.011494

71

142.8161

TOTAL 59.48276 Therefore mass in = mass out

5832.471

MASS BALANCE ON OXYCHLORINATOR REACTOR:

∴

Ethylenedichloride obtained =

114.9425 = 57.4716 2

 ℎ /

The conversion for ethylene is 96% and for Hydrogen chloride is 98%

∴

Amount of Ethylene required =


57.47126 0.96 Page 23


= 59.8659

∴

Amount of Hydrogen chloride required =

 ℎ /

57.47126 ×2 = 117.2883 0.98

 ℎ /

Pure O2 is taken as reactant and it is taken in 20% excess

∴ ∴ ∴

Amount of Oxygen required =

57.47126× 1.2 = 34.48276 2

−

 ℎ  ℎ /

HCl remained unconverted = 117.2883 114.9425 = 2.345766

Amount of Heavies formed = 59.8659

−

/

57.47126

= 2.39464

 ℎ /

REACTANTS ENTERING: COMPONENTS

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Ethylene

59.8659

28

1676.245

HCl

117.2883

36.5

4281.023

Oxygen

34.48276

32

1103.448

TOTAL

211.637

7060.716

PRODUCTS LEAVING: COMPONENTS

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Ethylene dichloride

57.47126

99

5689.655

Water

57.47126

18

1034.483

Byproducts

2.394636

133.5

319.6839

Therefore, mass in = mass out Vinyl Chloride Monomer

Page 24


MATERIAL BALANCE ON WET CRUDE EDC DECANTER: From literature, it is given that for 1Kg of vinyl chloride formed, vent gases out are CO2 out = 0.0116 Kg CO out = 0.0032 Kg H2O out = 0..07Kg O 2 out = 0.04 Kg

∴ 

4166.667

ℎ ℎ

CO2 out = 48.33333 Kg

= 1.09848485 Kmol.

CO out = 13.33333 Kg

=

0.47619048 Kmol.

H2O out = 291.1667Kg

=

16.230 Kmol.

O 2 out = 166.6666 Kg

= 5.20833 Kmol.

EDC coming in = EDC coming out = 57.47126 kmol/hr

REACTANTS ENTERING DECANTER: COMPONENTS

KMOLES

MASS (KG)

57.47126

MOLECULAR WEIGHT 99

Ethylene dichloride Water

57.47126

18

1034.483

Byproducts

2.394636

133.5

319.6839

TOTAL

117.3372


5689.655

7043.822

Page 25


PROCUCTS LEAVING THE DECANTER: COMPONENTS

KMOLES

MASS (KG)

57.4712644

MOLECULAR WEIGHT 99

Ethylene dichloride Water

47.4482759

18

854.069

Carbon dioxide

1.09848485

44

48.33333

Carbon monoxide

0.47619048

28

13.33333

Water vapours

16.2037037

18

291.6667

Light ends

0.1872

133.5

24.9912

Oxygen

5.20833

32

166.6666

TOTAL

128.093449

5689.655

7088.715

Therefore, mass in = mass out

MATERIAL BALANCE ON LIGHT END DISTILLATION COLUMN: Light end mainly consists of ethyl chloride. 99.8% Light ends are separated from the top of the distillation column, while 99.6% EDC is separated from the bottom of the distillation column. For a distillation column, F=D +W F xf = D xd + W xw For this distillation column; xd = 0.9968, xw = 0.002 Taking overall balance over distillation column. 57.65846= D

+W


..............(1) Page 26

Laxminarayan Institute of Technology 2015 Now taking balance on ethylene dichloride 57.47126 = 0.9968 × D + 0.002 W

..............(2)

Solving equation 1 and 2 simultaneously, we get D = 57.47126 Kmol/hr W = 0.1872 Kmol/hr

FEED ENTERING THE DISTILLATION COLUMN : COMPONENTS

KMOLES

MASS (KG)

57.47126

MOLECULAR WEIGHT 99

Ethylene dichloride Light ends

.18272

64.5

12.0744

TOTAL

57.65846

5689.655

5701.73

TOP PRODUCT FROM DISTILLATION COLUMN: COMPONENTS

KMOLES

MASS (KG)

0.229885

MOLECULAR WEIGHT 99

Ethylene dichloride Light products

0.186826

64.5

12.05025

TOTAL

.416711

22.75862

34.80887

BOTTOM PRODUCTS FROM DISTILLATION COLUMN: COMPONENTS

KMOLES

MASS (KG)

57.24138

MOLECULAR WEIGHT 99

Ethylene dichloride Light products

0.000374

64.5

0.024149

TOTAL

57.24175


5666.897

5666.921149

Page 27

Laxminarayan Institute of Technology 2015 Total mass out = Top product from stripping column + bottom pro duct from stripping column Therefore mass in = mass out.

MATERIAL BALANCE OVER HEAVY END SEPERATOR: Assuming 100% conversion in heavy end separator. The heavy ends mainly consists of 1,1,2-trichloroethane (molecular wt. =133.5). Total EDC entering the separator = 57.47126 + 57.47126 = 114.9425 kmol/hr FEED ENTERING THE SEPERATING COLUMN: COMPONENTS

KMOLES

MASS (KG)

114.9425

MOLECULAR WEIGHT 99

Ethylene dichloride Chlorine

2.011494

71

142.8161

Heavy ends

0.58

133.5

77.43

11379.31

TOP PRODUCT FROM SEPERATING COLUMN : COMPONENTS

KMOLES

MOLECULAR

MASS (KG)

WEIGHT

Ethylene dichloride

114.9425

99

11379.31

Chlorine

2.011494

71

142.8161

TOTAL

116.95399


11522.1261

Page 28


BOTTOM PRODUCTS FROM SEPERATING COLUMN: COMPONENTS

KMOLES

MOLECULAR

MASS (KG)

WEIGHT

Heavy ends

0.58

133.5

77.43

MATERIAL BALANCE OVER EDC PYROLYSIS FURNACE: Conversion for EDC in pyrolysis furnace is 58%.

∴

Vinyl chloride obtained = 0.58 × 114.9425

= 66.666Kmol/hr.

∴

∴

HCl obtained = 66.666

 ℎ /

Ethylenedichloride unconverted = 114.9425

−

66.666

= 48.27586 Kmol/hr

FEED TO THE PYROLYSIS FURNACE: COMPONENTS

KMOLES

MASS (KG)

114.9425

MOLECULAR WEIGHT 99

Ethylene dichloride Chlorine

2.011494

71

142.8161

TOTAL

116.95399


11379.31

11522.1261

Page 29


PRODUCT FROM PYROLYSIS FURNACE: COMPONENTS

KMOLES

MASS (KG)

66.666

MOLECULAR WEIGHT 62.5

Vinyl chloride HCl

66.666

36.5

2433.333

Ethylene dichloride

48.27586

99

4779.31

Chlorine

2.011494

71

142.8161

TOTAL

183.6207

4166.667

11522.13

Therefore, mass in = mass out

MATERIAL BALANCE OVER PYROLYSIS QUENCH: The converted products from pyrolysis furnace are cooled by direct quenching into the liquid. So the total mass coming in is equal to the total mass coming out.

MATERIAL BALANCE OVER HCl SEPERATING COLUMN: Products from pyrolysis quench consist mainly of vinyl chloride, Ethylene dichloride and HCl. Considering 100% conversion in separating column. Total HCl and Cl2 separated from the top of separating column.

FEED TO THE HCl SEPERATING COLUMN: COMPONENTS

KMOLES

MASS (KG)

66.666


Vinyl chloride HCl

66.666

36.5

2433.333

Ethylene dichloride

48.27586

99

4779.31

Chlorine

2.011494

71

142.8161

TOTAL

183.6207


4166.667

11522.13

Page 30


TOP PRODUCT FROM HCl SEPERATING COLUMN: COMPONENTS

KMOLES

MASS (KG)

66.666


HCl Chlorine

2.011494

71

142.8161

TOTAL

68.677494

2433.333

2576.149

BOTTOM PRODUCTS FROM SEPERATING COLUMN: COMPONENTS

KMOLES

MASS (KG)

66.666


Vinyl chloride Ethylene dichloride

48.27586

99

4779.31

TOTAL

114.94186

4166.667

8945.977

Total mass out = Top product from separating column + bottom product from separating column Therefore mass in = mass out.

TOTAL RECYCLE: Now the top product from the seperating column is co mbined along with the Hydrogen gas to convert unconverted chlorine to HCl. This combined stream is returned to the reactor as a recycle stream. This total recycle stream is joined along with the make up streams of the reactants and this combined stream is fed to the reactor.


Page 31


MATERIAL BALANCE OVER VINYL CHLORIDE SEPERATOR (DISTILLATION COLUMN): 99.5% Vinyl chloride as MVC is separated from the top of the distillation column, while 99.8% Ethylene dichloride is separated from the bottom of the distillation column. For a distillation column, F=D + W F xf = D xd + W xw For this distillation column; xd = 0.995, xw = 0.0002, xf = 0.58 Taking overall balance over distillation column. 114.94186 = D

+ W

..............(1)

Now taking balance on vinyl chloride 66.666= 0.9968 × D + 0.002 W

..............(2)

Solving equation 1 and 2 simultaneously, we get D = 66.66667

Kmol/hr

W = 48.27586 Kmol/hr

FEED ENTERING THE DISTILLATION COLUMN: COMPONENTS

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Vinyl chloride

66.666

62.5

4166.667

Ethylene dichloride

48.27586

99

4779.31

TOTAL

114.94186


8945.977

Page 32


TOP PRODUCT FROM DISTILLATION COLUMN: COMPONENTS

KMOLES

MOLECULAR WEIGHT

MASS (KG)

Vinyl chloride

66.33333

62.5

4145.833

Ethylene dichloride

0.096552

99

9.558621

TOTAL

66.42989

4155.392

BOTTOM PRODUCTS FROM DISTILLATION COLUMN: COMPONENTS

KMOLES

MOLECULAR

MASS (KG)

WEIGHT

Vinyl chloride

48.17931

62.5

4769.752

Ethylene dichloride

0.333333

99

20.83333

TOTAL

48.51264

4790.585

Therefore mass in = mass out.


Page 33


CHAPTER SEVEN: ENERGY BALANCE

[9]

POLYNOMIAL GAS CONSTANTS FOR ALL THE COMPONENTS

[6,8]:

COMPONENT

A

B

C

Chlorine

0.2914E-5

0.0918 E-5

0.949E-3

Oxygen

0.291 E-5

0.1004 E-5

2.526 E-3

Water

0.3336 E-5

0.2679 E-5

2.6105 E-3

Ethylene

0.3338 E-5

0.9479 E-5

1.596 E-3

Hydrogen chloride

0.2916 E-5

0.0905 E-5

2.0938 E-3

Vinyl chloride

0.4236 E-5

0.8735 E-5

1.6492 E-3

Hydrogen

0.2762 E-5

0.0956 E-5

2.466 E-3

Carbon monoxide

0.2911 E-5

0.0877 E-5

3.0851 E-3

Carbon dioxide

0.2937 E-5

0.3454 E-5

1.428 E-3

Ethylene dichloride

37.275

0.14362

1.04 E-5

Ethyl Chloride

0.456 E-5

1.2962 E-5

1.5992 E-3

1,1,2 trichloroethane

34.934

.8505

-2.3306 E-3

Table No. 4: Polynomial constants for the components The enthalpy is calculated as follows:

 ∫              ∫    =

=

×

×

= 34.48276

×

( +

.

× +

(0.291

×

)

.

+ 0.1004

+ 2.526

)dT

= 79176.40872 J/hr. = 79.176408 kJ/hr.


Page 34


HEAT BALANCE ON OXYCHLORINATION REACTOR: Oxygen and ethylene enters the reactor at 308K, while the recycle HCl enters the reactor at 343K. An exothermic reaction takes place in the reactor, during which a lot of heat is evolved. This heat has to be removed from the reactor .

HEAT ENTERING THE REACTOR:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Oxygen

34.48276

79.17641

Ethylene

59.8659

86.85221

HCl

117.2883

902.4308

TOTAL

1068.459

HEAT LEAVING THE REACTOR:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

57.47126437

1136.71732

Water

57.47126437

4990.56532

Oxygen

5.20833

437.62937

Ethylene

2.394636015

127.131438

HCl

2.345765893

163.378356

TOTAL

6855.42181

Now the heat of reaction can be given as follows:

∆ − − =

=

   

493.304 × 10 /

493.304 × 10


/

Page 35

Laxminarayan Institute of Technology 2015 For 28.732 kmol/hr of Ethylene dichloride formed

 ∆ −  ℎ −  −  − ∆ =

493.304 × 10 ×57.47126437

=

28350.80442× 10

/

Total heat to be removed from the reactor can be calculated as follows:

=



= 6855.42181 - 1068.459 + 28350.80442× 10

 ℎ

= 28356.591 × 10

/

This heat can be removed with the help of cooling water. C p = 4.186 kJ/kg,

 ∆

0

∆T = 20 C.

=



28356.591× 10 =



×4.186 ×20

m = 94.130 kg/s of cooling water will be required.


Page 36


HEAT BALANCE ON THE OXYCHLORINATION QUENCH: Products from oxychlorination reactor are cooled quickly by quenching with water. Products from oxychlorinator reactor enters the quench tower at 503K And leaves at 329.8K.

HEAT ENTERING THE QUENCH:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

57.47126437

1136.71732

Water

57.47126437

4990.56532

Oxygen

5.20833

437.62937

Ethylene

2.394636015

127.131438

HCl

2.345765893

163.378356

TOTAL

6855.42181

HEAT LEAVING THE QUENCH:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

57.47126437

218.184194

Water

57.47126437

687.689687

Oxygen

5.20833

60.3044058

Ethylene

2.394636015

17.5185104

HCl

2.345765893

22.513194

TOTAL Therefore, total heat removed by water = Hin - Hout

1006.20999

= 6855.42181 – 1006.20999 Vinyl Chloride Monomer

Page 37

Laxminarayan Institute of Technology 2015 = 5849.21191 0 As, Quenching is carried in water C p = 4.184 kJ/kg. ∆T = 40 C

 ∆  =

5849.21191 =

×4.186×40

m = 34.9498 kg/hr of cooling water will be required. Therefore, 34.9498 kg of quenching water required.

HEAT BALANCE OVER EDC DECANTER: Since, the temperature change in the decanter is zero, therefore the heat added or heat removed from the decanter is zero. Therefore there is no need to determine heat balance over the decanter .

HEAT BALANCE OVER LIGHT END SEPARATING COLUMN: Total feed entering to column = 57.47126 + 0.1872 = 57.65846 kmol/hr. Mol fraction of Ethylene dichloride = 57.65846 / 57.47126 = 0.996 Therefore, Temperature of feed

= 355.67K

HEAT ENTERING THE SEPARATING COLUMN: COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

57.47126

282.7743

Ethyl chloride

0.1872

1.830573

TOTAL


284.6049

Page 38

Laxminarayan Institute of Technology 2015 Temperature of the top product is 296.8K .

HEAT LEAVING THE SEPARATING COLUMN FROM TOP:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

0.229885

-1.15341

Ethyl chloride

0.186826

-1.85831

TOTAL Temperature of the bottom product is 356.5K.

-3.01172

Bottom product mainly consists of Ethylene dichloride Therefore, heat leaving from bottom product = 4.2675 kJ/hr. The heat balance over distillation column is F . hf + Qr = D . hd + W . hw + Qc 0

For R = 30 and 5 C water for condensing vapour.

  ℷ      ℎ    ℎ =

.

= ( + 1).

=673448.28

284.6049 +

/

= -3.01172+4.2675+673448.28

= 673164.92

/

This much amount of heat is supplied to the reboiler by condensing steam in the reboiler at 0

100 C

ℷ   ∴   ℷ = 2676

=

/

.


Page 39




∴

=

673164.92 2676.0

= 0.06988

  /

Therefore, 0.06988kg/sec steam is required in reboiler

BALANCE OVER DIRECT CHLORINATION REACTOR: Chlorine and ethylene enters the reactor at 308K. Ethylene dichloride and chlorine leaves the reactor at 503K. An exothermic reaction takes place in the reactor, during which a lot of heat is evolved. This heat has to be removed from the reactor with the help of coolent.

HEAT ENTERING THE REACTOR:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene

57.47126

83.37812

Chlorine

59.48276

51.35576

TOTAL

134.7339

HEAT LEAVING THE REACTOR:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

57.47126437

230.136082

Chlorine

2.011494253

18.8686657

TOTAL

∆ − ∆ − =

249.004748

 

391.84×10

/

Therefore, for 28.732 kmol/hr Ethylene dichloride formed

=



391.84×10 × 57.47126


Page 40


=

 ℎ −  −  − ∆   ℎ 22516.692×10

/

Total heat to be removed from the reactor can be calculated as follows:

=

= 249.004 – 134.7339 + 22516.692E3

= 22516.806 3

/

This heat can be removed with the help of cooling water. C p = 4.186 kJ/kg,

 ∆ =

22516806 =



0

∆T = 20 C.

×4186 × 20

m = 269.08kg/hr of cooling water will be required.

HEAT BALANCE OVER LIGHT END SEPARATING COLUMN: Total feed entering to column = 172.1839 +2.011494 + 0.58 = 174.775kmol/hr. Therefore, Temperature of feed mixture = 353 × 0.3466 + 356.59 × 0.637 +238.4 × 0.012 + 347 × 0.0035 = 353.57 K Temperature of top product mixture

= 356.59×0.987 + 347×0.0035 = 354.57


Page 41


HEAT ENTERING THE SEPARATING COLUMN:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

172.1839

814.8298

Chlorine

2.011494

11.18269

1,1,2-trichloroethane

0.58

2.144423

TOTAL

828.1569

HEAT LEAVING THE SEPARATING COLUMN AS TOP PRODUCT:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

172.1839

834.84996

Chlorine

2.011494

11.49121

TOTAL

846.3409

Temperature of product leaving from the botto m = 347.195K

HEAT

LEAVING

THE

SEPARATING

COLUMN

AS

BOTTOM

PRODUCT:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

1,1,2-trichloroethane

0.58

2.179632

Ethylene dichloride

1.3774713

6.6788

TOTAL


8.858432

Page 42

Laxminarayan Institute of Technology 2015 The heat balance over distillation column is F . hf + Qr = D . hd + W . hw + Qc

0

For R = 30 and 5 C water for condensing vapour.

 ℷ      ℎ    ℎ



=

.

= ( + 1).

= 2025.081 /

828.1569 +

= 846.3409+8.854 + 2025.081

= 2052.839 /


100 C

ℷ   ∴   ℷ ∴   ℎ = 2676

=

=

/

.

2052.839 2676.0

= 0.7571

/

Therefore, .7571kg/hr steam is required in reboiler.


Page 43


ENERGY BALANCE OVER THE PYROLYSIS FURNACE: Ethylene dichloride and chlorine enters the furnace at 354.83K, while the products from furnace leaves at temperature 723K. The reaction is endothermic and heat is supplied by condensing steam.

HEAT ENTERING THE PYROLYSIS FURNACE:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

114.9425

557.3097

chlorine

2.011494

11.49121

TOTAL

568.8009

HEAT LEAVING THE PYROLYSIS FURNACE:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

12752.28

Chlorine

2.011494253

221.5939

HCl

66.66666667

16189.96

Ethylene dichloride

48.27586207

2327.296

TOTAL

∆ ∆

31491.13

 

= 107.507× 10

/

Therefore, for 33.33 kmol/hr Ethylene dichloride formed



= 107.507× 10 × 66.66

  ℎ

= 7166.416 3 /


Page 44

Laxminarayan Institute of Technology 2015 Total heat to be supplied to the reactor can be calculated as follows:

 −  ∆   ℎ ℷ   ∴   ℷ ∴    =

+

= 34491.13-568.8009+ 3583208.31

= 7200.3389 3

/

0

This heat will be supplied bysteam at 4 bar condensing at 143 C

= 2737.6

/

Therefore, amount of steam required is

=

=

.

7200338.9 2737.6

= 0.7306

/

Therefore, 0.7306 kg/s steam is required in reboiler.

HEAT BALANCE ON THE OXYCHLORINATION QUENCH: Products from pyrolysis furnace are cooled quickly by quenching with water. Products from pyrolysis furnace enters the quench tower at 723K And leaves at 343K.

HEAT ENTERING THE QUENCH: COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

12752.28

Chlorine

2.011494253

221.5939

HCl

66.66666667

16189.96

Ethylene dichloride

48.27586207

2327.296

TOTAL Vinyl Chloride Monomer

31491.13 Page 45


HEAT ENTERING THE QUENCH:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

503.9714916

Chlorine

2.011494253

8.757366433

HCl

66.66666667

639.8249739

Ethylene dichloride

48.27586207

183.2747232

TOTAL

1335.828555

Therefore, total heat removed by water = Hin - Hout = 31491.13– 1335.82 = 30155.31 kJ/hr As, Quenching is carried in water 0

C p = 4.184 kJ/kg. ∆T = 40 C

 ∆  =

30155.31 =

× 4.186× 40

m = 0.04668 kg/sec of cooling water will be required. Therefore, 0.04668 kg/sec of quenching water required .


Page 46


ENERGY BALANCE OVER COOLER: The product mixture from quenching are cooled to 259K with the help of coolant and then distilled .

HEAT ENTERING THE COOLER:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

503.9714916

Chlorine

2.011494253

8.757366433

HCl

66.66666667

639.8249739

Ethylene dichloride

48.27586207

183.2747232

TOTAL

1335.828555

HEAT LEAVING THE COOLER:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

-328.703417

Chlorine

2.011494253

-5.71177223

HCl

66.66666667

-417.309656

Ethylene dichloride

48.27586207

-146.448353

TOTAL

-898.173198

Total heat that must be removed is:

=

 −   ℎ

= 1355.82 + 898.173

= 2253.993 /


Page 47

Laxminarayan Institute of Technology 2015 This heat will be removed by refrigerant vapourising in cooler. Therefore, amount of refrigerant required is

∴   ℷ ∴   ℎ =

=

.

2253.993 380.1

= 5.93

/

Therefore, 0.00163 kg/s refrigerant is required.

HEAT BALANCE OVER LIGHT END SEPARATING COLUMN: Temperature of feed mixture = 259.15K Temperature of top product mixture is 189.5K and Temperature of bottom product mixture is 301.14 K

HEAT ENTERING THE HCl SEPARATING COLUMN:

COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Vinyl chloride

66.66666667

-328.703417

Chlorine

2.011494253

-5.71177223

HCl

66.66666667

-417.309656

Ethylene dichloride

48.27586207

-146.448353

TOTAL


-898.173198

Page 48


HEAT LEAVING THE HCl SEPARATING COLUMN AS TOP PRODUCT: COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

HCl

66.66666667

-384.5732

Chlorine

2.011494253

-6.682579

TOTAL

-391.255768

HEAT LEAVING THE HCl SEPARATING COLUMN AS BOTTOM PRODUCT: COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

66.66666667

456.25092

Vinyl chloride

48.27586207

158.76068

TOTAL

615.01159

The heat from top gases can be removed by refrigerant at T = 170K

ℷ   ℷ      ℎ = 504.5kJ/kg

For R = 30

=

.

= ( + 1).

= 17179.92

/

The heat balance over distillation column is F . hf + Qr = D . hd + W . hw + Qc

−    ℎ 898.173+

= -399.255+ 615.01159+ 17179928

= 18301.87 /


Page 49

Laxminarayan Institute of Technology 2015 This much amount of heat is supplied to the reboiler by condensing steam in the reboiler at 0

100 C

ℷ   ∴   ℷ ∴    = 2676

=

=

/

.

18301.87 2676.0

= 6.839

/

Therefore, 6.839 kg/s steam is required in reboiler .

ENERGY

BALANCE

OVER

VINYL

CHLORIDE

DISTILLATION

COLUMN: HEAT ENTERING THE VINYL CHLORIDE DISTILLATION COLUMN COMPONENT

KMOLES/HR

ENTHALPY (KJ/HR)

Ethylene dichloride

66.66666667

456.25092

Vinyl chloride

48.27586207

158.76068

TOTAL

615.01159

TOTAL HEAT LEAVING FROM THE TOP OF THE DISTILLATION COLUMN

=-

197073.4 kJ/hr TOTAL HEAT LEAVING FROM THE BOTTOM OF THE DISTILLATION COLUMN

= 239.95 kJ/hr The heat from top gases can be removed by refrigerant at T = 170K

ℷ

= 504.5kJ/kg

For R = 30 Vinyl Chloride Monomer

Page 50


  ℷ    ℎ  =

.

= ( + 1).

= 45871279.08

The heat balance over distillation column is F . hf + Qr = D . hd + W . hw + Qc

615.01159 +





= -197073.4 + 239.95 +45871279.08

= 45665399

 ℎ /


100 C

ℷ   ∴   ℷ ∴    = 2676

=

=

/

.

45665399 2676.0

= 4.74

/

Therefore, 4.74 kg/s steam is required in reboiler.


Page 51


CHAPTER EIGHT: DESIGN OF REACTOR

[10,11,12,13]

AIM:- TO DESIGN FIXED BED MULTITUBULAR REACTOR

Figure no.3: Diagram of Multitubular reactor. REACTION OCCURING: CH2=CH2 + 2 HCl + ½ O2

Cl CH2-CH2 Cl + H2O

CONDITIONS:1) Reaction temperature 2) Reactor pressure

= 2300C = 6 atm

3) Catalyst: Deacon Catalyst with higher loading of CuCl2


Page 52

Laxminarayan Institute of Technology 2015 (1) VOLUME OF REACTOR:

The design equation is given as:

 − =

The rate expression for the given oxychlorination reaction is given by:

C2H4 Cl2

2CH2 = CHCl + HCl

r = k [C2H4 Cl2] Activation Energy= 58kcal/mol

   −   −  −  −    −           =

(1

0.67

0.52

)

0.14 (1 ) . 2( + 2) + 3.13

0.67( + 2)

+ 0.71

+

Where,

= {( + 2) + 3.13( + 2) + 1.23 }

W = weight of catalyst F = flow rate of ethylene For synthesis of ethylene dichloride diluted with inert gas Constants d = 8.78 P = 6 atm.

 −  −  −   −  − −  

5.04(1 ) = 21.74 22.56 + 362.936 =

21.74

22.56 + 362.936 5.04(1 )



For conversion of 99%, x = 0.99 Therefore, Integrating equation between 0 to 0.99


Page 53


 

  −  .

=

 − − 

21.74

22.56 + 362.936 5.04(1 )



  ℎ

= 4225

/

/

Flow rate of ethylene = F = 59.8659 kmol/hr

∴

= 4225× 59.8659



= 252933.4275 There are two reactors in parallel.

∴ ℎ

=

252933.4275 2



= 126466.71 3

As density = 3054 kg/m

∴ 

.=

12466.7 3054

= 41.410 m3

(2) TUBE DIAMETER AND LENGTH: Internal diameter = 3” =7.62 cms = 0.0762 m Tube thickness

= 3 mm = 0.003 m.

∴    =

+2×

=7.62 + 2(0.3) = 8.22 cm = 0.0822 m. Considering length of each tube = L = 5 m Vinyl Chloride Monomer

Page 54


(3) NUMBER OF TUBES:

ℎ

3.14 × = 4

  ×

Where, Di = Internal diameter of tube L = length of each tube

ℎ



3.14 × 0.0762 = ×5 4 3

= 0.0228 m



=

41.410 0.0228

= 1826 tubes

(4) SHELL DIAMETER: We take triangular spacing, therefore the area occupied by e ach tube is given by

 

  

= 0.866 ×

Where, s is pitch of tubes

= (1.25 ×

)

Therefore, Area required for N number of tubes

=



× 0.866×



To provide pass partition, the actual area of the tube sheet, for locating the tubes will be greater than the area given by the above equation, so we have to divide it by proportionality factor, B = 0.95. This area corresponds to the area of the shell

∴

=

       .

×

=

× .


×

Page 55


  



4 ×1826 × 0.866× (1.25 × 0.0762) = 3.14 ×0.95 = 19.1431

D = 4.37m Thus diameter of shell is 4.37 meters.

(4) COOLING ARRANGEMENT: Water is used for cooling. The inlet for it is at the bottom and outlet at the top. (i) Heat to be removed (from energy balance)

 ℎ ∴ 

= 28356591.56 / About 10% of this heat is lost

 ℎ   ℎ  ℎ

= 2.35659× 10 /

∴ ℎ

= 25520.9324 ×

10 / 2

= 12760.4662× 10 / This amount of heat is removed by cooling water C p = 4.186 kJ/kg

∆  ∴  ∆   ∴    = 20° =

12760.4662 ×10 = = 42.3384

× 4.186× 20

/

Therefore, water flow rate to reactor is 42.3385 kg/s.


Page 56


(ii) Area available for heat transfer: For single tube = 3.14DoL Therefore, total area for heat transfer from 1826 tubes

= 1826 × 3.14 × 0.0762 × 5



= 2184.51 m (iii) Determination of overall heat transfer coefficient: The gas side heat transfer coefficient is given by

ℎ

= 0.813 ×

 −      × exp

6×

×

×

.

Where, D p = Diameter of catalyst particals k g = Thermal conductivity of gas mixture G = mass flow rate of gas mixture



= viscosity of gas mixture

Now, for a fixed bed with



= 0.16

2

And G = 0.0024 gm/cm

K = 0.02 Cal/sec.m.K Putting these values in equation for hi , we have 2

hi = 0.1593 cal/s.m .K 2

hi = 0.6665W/m .K Since, the internal heat transfer co efficient is controlling factor we take 2

hi = U = 0.6665W/m .K


Page 57

Laxminarayan Institute of Technology 2015 Q = U. A.(∆T)lm 0

Temperature in reactor

= 230 C

Temperature of inlet water

= 30 C

0

0

Temperature of outlet water = 50 C

∴ ∆  − −  − ∴ ∆   ∴   ∆    ∴   ∴   (230

(

)

=

(

)

= 189.82

30)

(230 200 ln 180

50)

Therefore, minimum area required for heat transfer

=

,

=

.(

)

25520932.4 2 × 3600

= 3544.5739× 10 / = 2085

This area is less than the available area therefore cooling is possible.


Page 58


MECHANICAL DESIGN: (1) SHELL THICKNESS

Pressure = 1atm + static head 2

2

= 1 kg/cm + 0.5 kg/cm 2

= 1.5 kg/cm

2

Considering the stresses due to support we will overdesign it for pressure of 2.5kg/cm

∴ ℎ ℎ  −   =

=

+

2

2

Where, f is allowable stress of material = 1210 kg/cm J is joint efficiency = 0.85



=

2.5 × 473 2 × 1210 ×0.85

−

2.5

+ .3

= ..875cm = 9 mm. 2) CONICAL BOTTOM:

For better distribution of gasses conical bottom is used. It consists of a gas inlet at its apex.

     =

.

2

+

P = Design pressure = 1.1 × working pressure = 1.1 × 6


Page 59

Laxminarayan Institute of Technology 2015 = 6.6 kg/cm2 Z = factor depending on apex angle = 3.2 0

We will have apex angle as 60



=

6.6 ×473×3.2 + .3 2 × 1210 ×0.85

= 50 mm. (3) TOP HEAD (TORISPHERICAL HEAD):

Here, t is thickness of head R i is internal crown radius r i is internal knuckle radius ho is height of head Sf is straight flange portion = 3t Crown radius = Do =outside diameter of shell So we have crown radius = R i =473 + 2(0.1) = 473.2 cm Knuckle radius = 6% Di = 0.06 × 4.73 = 0.2838 m Now,



=



+



Where w = stress intensity factor

=

    3+


Page 60


=

  

1 4.73 3+ 4 .2838

=1.77

∴ ∴

=

6.6 × 473× 1.77 + .3 2 ×1210 × 0.85

=30 mm

Sf = 3t = 3× 30 = 90 mm

 

ho =

  ∴

r = r + t = .2838 + 30 h = 31.38cm

(4) TUBE SHEET:

It is a flat plate having provision for making a gasketed joint around the periphery. A large number of holes are drilled in the tube sheet according to the pitch requirements of the tubes. The common method of fixing the tube in these holes consists of expanding the ends of the tubes. The relation giving effective tube sheet thickness is

    =

.

Where, F is constant which varies according to the type heat exchanger. G is mean gasket diameter P is design pressure

And

   =


Page 61

Laxminarayan Institute of Technology 2015 For k = 0.055 F = 0.9

     −−  = 0.9 × 473

0.25× 6.6 1210

= 15

(5) GASKET DESIGN:

d y Pm = d y P(m+1) Where, P is internal design pressure Y is minimum design yield stress = 260 kg/cm2 m = 2.75 The thickness of gasket is taken as = 2mm

−−

 

d 260 6.6 × 2.75 = d 260 6.6(2.75+ 1) = 1.028

∴

d = 1.028× 4.73 = 4.862 m.

Mean gasket diameter = G =

   .

.

G = 4.79m Minimum gasket width =

   .

.

= 0.066 m.


Page 62

Laxminarayan Institute of Technology 2015 (6) BOLT AND FLANGES:

Diameter of bolt selected = 20 mm Bolt spacing = 2.5× d = 2.5× 20 = 50 mm. Bolt circle diameter = outer diameter of gasket + 2 × diameter of bolt + 0.015 = 4.862 +2 × 0.02 +0.015 = 4.9 m

∴ ℎ    5

=

3.14 5



3.14 × 4.9 × 10 = 5 = 307 bolts Flange thickness:

    ℎ =

=

P K.f

1 1.5 . 0.3 + .

Where, W is total bolt load h is radial distance from gasket load reaction to bolt circle. H is total hydrostatic end force f is permissible stress As, K = 4.4


Page 63


∴   ∴   ∴       = 479

6.6 4.4 ×1210

= 16.86

=

+ 2(

)

= 4.73 + 2 × 0.02 = 47.7 cm = 18 inch

(8) NOZZLE DESIGN: (a) Water nozzle Flow rate of water = 9 kg/s 2

Density of water = 998 kg/cm So, the selected nozzle size is

Nominal diameter = 10.16 cm Outside diameter = 11.36cm

 −  =

2

Thickness = 15 mm Height of nozzle = 15.24 cm


Page 64


CHAPTER NINE: COST ESTIMATION AND ECONOMICS

[14]

DETERMINING PURCHASED EQUIPMENT COST (PEC):Cost index of 2007-2008 = 582 Cost index of 2015 = 1024 Fixed Capital Investment for that year: 9.46E+07 Rs Hence, Fixed Capital Investment for 2015: (1024 × 9.46E+07)/ 582 = 1.66E+08 Rs Estimation of total investment cost: 1. Direct cost: 

Purchased equipment cost(PEC) = 15-40% FCI

= 5.82E+07 Rs 

Installation cost (IC) = 35-45% PEC

= 2.33E+07 Rs 

Instrument and control installed (I&CI) = 6-30% PEC

= 1.75E+07 Rs 

Piping installation cost (PIC) = 10-75% PEC

= 3.49E+07 Rs 

Electrical installation cost (EIC) = 10-40% PEC

= 2.33E+07 Rs 

Building process and auxiliary (BP&A) = 10-65% PEC = 3.49E+07 Rs


Page 65

Laxminarayan Institute of Technology 2015 

Service facilities (SF) = 30-75% PEC

= 4.08E+07 Rs 

Yard improvement (YI) = 10-15% PEC

= 8.74E+06 Rs 

Land (L) = 4-8% PEC

= 4.66E+06 Rs TOTAL DIRECT COST (TDC): 2.46E+08 Rs 2. Indirect cost:

Expenses which are not directly involved with material and labour of actual installation or complete facility. 

Engineering and supervision (E&S) = 5-30% DC = 7.39E+07 Rs



Construction expenses (CE) = 10% DC = 2.46E+07 Rs



Contractor's fee (CF) = 2-7% DC = 1.72E+07 Rs



Contingency (Cntg.) = 8-20% DC = 4.93E+07 Rs



TOTAL INDIRECT COST (TIC): 1.65E+08 Rs

3. Fixed capital investment: 

TCI = FCI + WCI = 4.11E+08 Rs

4. Working capital investment ( WCI) WCI) : 10-20% FCI= 6.17E+07 Rs 5. Total capital investment(TCI): investment(TCI) : FCI + WCI = 4.73E+08 Rs


Page 66

Laxminarayan Institute of Technology 2015 Estimation of total product cost (TPC): 1) Fixed charge: 

Depreciation: 10% FCI (machinery) = 4.11E+07 Rs



Insurances : 0.4-1% of FCI = 4.11E+06 Rs



Local taxes (LT) = 3-4% FCI = 1.65E+07 Rs



TOTAL FIXED CHARGES (TFC): 1.11E+08 Rs

But, Fixed charges = 10-20% TPC 

TOTAL PRODUCT COST: 1.11E+09 Rs 2) Direct production:



Raw material (RM) = 10-50% TPC = 3.33E+08 Rs



Maintenance: 2-10% of FCI = 2.47E+07 Rs



Operating labour (OL) = 10-20% TPC = 1.67E+08 Rs Direct supervisory & electric labour (DS&EL) = 10-25% OL = 2.50E+07 Rs Laboratory charges (LC) = 10-20% OL = 2.50E+07 Rs

 



Utilities = 10-20% TPC = 1.67E+08 Rs



Patent and royalties (P&R) = 2-6% TPC = 4.44E+07 Rs



Operating supplies (OS) = 10-20% of Maintainance = 3.70E+06 Rs



PLANT OVERHEAD COST (POC) = 50-70% (OL+OS+M) = 1.17E+08 Rs


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TOTAL DIRECT COST = 7.89E+08 Rs 3) General expenses:



Administration cost (AC) = 40-60% OL = 9.16E+07 Rs



Research and development cost( R&DC) = 3% TPC =3.33E+07 Rs



Distribution and selling price (D&SP) = 2-30% TPC =1.67E+08 Rs

GENERAL EXPENSES (GE): 2.92E+08 Rs

Therefore, Manufacturing cost = Total Direct Cost + TFC + POC MC = 1.02E+09 Rs

Therefore, Total production cost = MC + GE T ProC = 1.31E+09 Rs Gross earning and rate of return: The plant is working for say: 300 days SP = 50 Rs/kg Total income (Rs) = Capacity × No. Of working Days × Capacity

= 1.50E+09 Rs Gross income = Total income – TPC GI= 1.91E+08 Rs Tax (%) = 45 Net profit= GI – GI × Tax = 1.05E+08 Rs Rate of Return= Net Profit ×100 / Total Capital Investment =22.22% Payback Period = 1/ rate of return = 4.50 years Vinyl Chloride Monomer

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CHAPTER TEN: PROCESS CONTROL AND INSTRUMENTATION

[15,16}

:

The process information segment such as temperature, flow rate etc are communicated between process plant and PLC control Unit. Sr. No

Control Equipment

SENSOR

INFORMATION COMMUNICATED

1

Oxychlorination Reactor

(i)Thermocouple (ii)composition measurement

(i) measuring temperature of ethylene dichloride.

(i) Thermocouple (ii)composition measurement

(i) measuring temperature of ethylene dichloride.

(i)Thermocouple

(i)For measuring Temperature of Ethylene dichloride.

2

3

Direct chlorination reactor

Quench

(ii)Flowmeter

(ii)For measuring composition of feed stream.

(ii)For measuring composition of feed stream.

(ii)for measuring flow rate of the outlet. 4

Distillation column

(i)Flowmeter (ii)composition measurent

(i)for measuring flow rate of the outlet. (ii)For measuring composition of feed.

5

EDC Still


i)for measuring flow rate of the feed. (ii)For measuring composition of feed.

6

Tubular pyrolysis furnace

(i)Thermocouple (ii)Flowmeter (iii)composition measurent

(i)For measuring Temperature of Ethylene dichloride. (ii)for measuring flow rate of the outlet. (ii)For measuring composition of product stream.


Page 69


7

Heat exchanger

(i)Thermocouple (ii)Flowmeter

(i)For measuring Temperature of Ethylene dichloride. (ii)for measuring flow rate of the water.

8

Quench

(i)Thermocouple (ii)Flowmeter

(i)For measuring Temperature of vinyl chloride. (ii)for measuring flow rate of the outlet stream.

9

HCL separator

(i)Flowmeter

(Distillation column)

(ii)composition measurent

(i)for measuring flow rate of the feed stream. (ii)For measuring composition of feed stream.

10

Vinyl chloride separator (Distillation column)


(i)for measuring flow rate of the feed stream.

(ii)For measuring composition of feed stream. Table No.: 5 Process Information communicated between process plant and PLU control unit.

DIRECT DIGITAL FEEDFORWARD FEEDBACK CONTROL OF DIRECT CHLORINATION REACTOR FOR EXOTHERMIC REACTION: The direct digital control for direct chlorination reaction is given in fig. shown below. The Temperature and composition of feed to the reactor is c ontrolled and monitored by feedforward controller which is monitored by computer.This controller measures the readings and compare it with set point and minimizes error and feed flow and temperature is controlled. The temperature of reaction mixture and coolant is measured by thermocouple and compared with set point through feedback controller monitored by computer. The error is generated which is minimized by controller and controller gives signals to the transducer which regulate the flow rate of coolant and temperature of both reaction mixture and coolant is determined.


Page 70


Fig.4: Direct digital control feedforward feedback co ntrol of direct chlorination reactor for exothermic reaction


Page 71


CHAPTER ELEVEN:PLANT LAYOUT AND SITE SELECTION

[17]

:

The location of the plant can have a crucial effect on the profitability of a project, and the scope for future expansion. Many factors must be considered when selecting a suitable site, the principal factors to consider are: 1. Location, with respect to the marketing area. 2. Raw material supply. 3. Transport facilities. 4. Availability of labour. 5. Availability of utilities: water, fuel, power. 6. Availability of suitable land. 7. Environmental impact, and effluent disposal. 8. Local community considerations. 9. Climate. 10. Political and strategic considerations.


Page 72


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 the major raw material; where this is also close to the marketing area. 

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 (canal or river), or a sea port. Road transport is being increasingly used, and is suitable for local distribution from a central warehouse. Rail transport will be cheaper for the long-distance transport of bulk chemicals. Air transport is convenient and efficient for the movement of personnel and essential equipment and supplies, and the proximity of the site to a major airport should be considered. 

UTILITIES (SERVICES):

Chemical processes invariably require large quantities of water for cooling and general process use, and the plant must be located near a source of water of suitable quality. Process water may be drawn from a river, from wells, or purchased from a local authority. At some sites, the cooling water required can be taken from a river or lake, or from the sea; at other locations cooling towers will be needed. Electrical power will be needed at all sites.It is suitable get steam supply from common boiler such type of facility is available in gujrat G.I.D.C ank leshwar. 

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 local regulations, and the appropriate authorities must be consulted during the initial site survey to determine the standards that must be met. An environmental impact assessment should be made for each new project, or major modification or addition to an existing process.


Page 73


LOCAL COMMUNITY CONSIDERATIONS:

The proposed plant must fit in 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: schools, banks, housing, and recreational and cultural facilities. VCM is mostly required for production of PVC so plant must be situated near PVC manufacturing plant. Such type of industries mostly found in Gujarat. 

LAND (SITE CONSIDERATIONS):

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 load-bearing characteristics. A full site evaluation should be made to determine the need for piling or ot her special foundations. 

CLIMATE:

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. Stronger structures will be needed at locations subject to high winds (cyclone/hurricane areas) or earthquakes. 

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 t he overriding consideration in site selection.


Page 74


Scrap Future

Utilities

Yard

ExpaGenera-

ETP

nsion

Main Plant

Storage Control

Cooling towers

Building

Room Tank Yard

Mainten-

Fire Station

W. B.

ance Building

Wash and Changing

Quality

Med-

Research

Room

Control

ical

and

Laboratory

Cent-

Develo-

re

pment

Cante-

Centre

en Administration Building Parking

Training Centre

Space

Sec-

Power Station

Green Belt

urity

Fig 5: General Plant Layout for a Chemical Industry.


Page 75


STORAGE AND TRANSPORTATION

[18]

:

Vinyl chloride is stored as a liquid at -14°C to -22°C. The presently accepted upper limit of safety as a health hazard is 500 ppm. Often, the storage containers for the product vinyl chloride are high capacity spheres with 56 ppm of hydroquinone stabilizer. The spheres have an inside sphere and an outside sphere. Several inches of empty space separate the inside sphere from the outside sphere. This void area between the spheres is purged with an inert gas such as nitrogen. As the nitrogen purge gas exits the void space it passes through an analyzer that is designed to detect if any vinyl chloride is leaking from the internal sphere. If vinyl chloride starts to leak from the internal sphere or if a fire is detected on the outside of the sphere then the contents of the sphere are automatically dumped into an emergency underground storage container. Transporting VCM presents the same risks as transporting other flammable gases such as propane, butane (LPG) or natural gas (for which the same safety regulations apply).The equipment used for VCM transport is specially designed to be impact and corrosion resistant.Vinyl Chloride may contain acetylene as impurity hence contact with copper, magnesium, silver, etc. Any contact with any ignition source or heat is avoided. A distance from oxidizing agents, caustic soda and reactive metals is kept. Goggles, self-contained breathing apparatus and rubber over clothing are to be worn while contacting with it. VCM stabilized liquid is shipped in spherical refrigerated steel tanks. Between loads, the vessel tank must be carefully dried, then purged with nitrogen. VCM in a gaseous form must be controlled carefully under refrigeration. Vinyl chloride tends to acquire an electrostatic charge during movement and, therefore, as a safeguard all pipe work and equipment in transfer system need to be grounded and earthed. Safety valves should be provided only on bulk containers and tank cars to avoid build up of excessive pressure. In an area where vinyl chloride monomer is handled, all the electrical equipments and fittings must be flame proof type. In an area where vinyl chloride monomer is handled, all the electrical equipments and fittings must be flame proof type.


Page 76


ENVIRONMENT EFFECTS

[18,19]

:

If released to soil, VCM is expected to have high mobility. Volatilization from moist soil surfaces is expected to be an important fate process based on its vapor pressure. If VCM is released into water, it is not expected to adsorb to suspended solids and sediment in the water. The biodegradation half-life of vinyl chloride in aerobic and anaerobic waters was reported as 28 and 110 days, respectively. Volatilization from water surfaces is expected to be an important fate process. The estimated volatilization half-lives for a model river and model lake are 1 hour and 3 days, respectively. VCM is practically non-toxic to fish on an acute basis. If released to air, VCM will exist solely as a gas in the ambient atmosphere. It will be degraded in the atmosphere by reaction with photochemically produced hydroxyl radicals.

MARKING AND LABELLING

[19]

:

All containers of vinyl chloride shall bear an identifying label as depicted in IS: 1260 (Part I)–1973*. Containers of vinyl chloride shall labelled as follows: VINYL CHLORIDE

DANGER

EXTREMELY FLAMMABLE AND TOXIC LIQUID AND GAS UNDER PRESS URE KEEP THE CONTAINER CLOSED IN A COOL PLACE. KEEP AWAY FROM HEAT, SPARKS, FLAME AND OXIDIZING AGENTS. INJURIOUS TO HEALTH—AVOID CONTACT. AVOID CONTACT WITH SKIN AND PROLONGED BREATHING OF THE VAPOUR. USE WITH ADEQUATE VENTILATION. GROUND THE CONTAINER WHEN EMPTYING.


Page 77


REFERENCES: (1) “ Encyclopedia of chemical technology, Fifth edition, vol. 25”, Kirk Othmer, Page no. 628-651 (2) “Ulman’s Encyclopedia of Industrial Chemistry, Vol.8”, U lman, Page no. 56-57 (3) “Encyclopedia of Chemical processing & Design”, John J. Mcketta. Page no. 313-320 (4) Chemical Weekly, February 22, 2011, pageno-253-254 (5) “Physical chemistry”, Puri Sharma and Pathania (6) “Perrys Chemical Engineering handbook”, Robert H. Perry, D W Green and J O Maloney. (7) “Handbook of chemistry and physics”, Yawns (8) “Stichiometry”, Bhutt and Vora. (9) “Transport Processes and Separation Process Principles, Fourth Edition”, Christie John Geankoplis, Page no. 61, 291, 706. (10) “Process Equipment Design”, M.V. Joshi, Page no. 139, 236. (11) “Chemical Engineers Handbook”, Page no. 4-25. (12) “Chemical Equipment Design”, B C Bhattacharya, Page no. 35, 49, 103 (13) “Chemical Reaction Engineering, Third Edition”, Octave Levenspiel. (14) “Plant design & economics for chemical engineers”, Max Peters & Klaus Timmerhaus. (15) “Process Automation and modelling”, R. P. Vyas, Page no. 365 (16) “Process control and Instrumentation”, R. P. Vyas, Page no. 229. (17) Industrial Engineering & Management by, O.P.Khanna & A. Sarup, Ganpatrai Pub. Page no. 4.1-4.30 Vinyl Chloride Monomer

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Vinyl Chloride

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