Documentan

2013

Submitted by

Aman Agrawal

Ankesh Kumar Singh

Pratik Chaplot

Rahul Gupta

Raju Mishra

Sachin Goel

1/5/2013

Acrylonitrile by Propylene

Ammoxidation

Guided by

Dr. R.G.Pala

1 | Acrylonitrile by Propene Ammoxidation

1 Introduction ................................................................................................................................... 2

2 Price and Demand ......................................................................................................................... 3

3 Health Effects ................................................................................................................................. 3

3.1.1 Sources and Potential Exposure ................................................................................... 4

3.1.2 Assessing Personal Exposure ....................................................................................... 4

4 Sohio Process ................................................................................................................................. 7

Reactor ............................................................................................................................................... 8

Effect of different variables on Conversion ..................................................................................... 9

5 Aspen Simulation ......................................................................................................................... 12

Reactor ............................................................................................................................................. 12

Quencher .......................................................................................................................................... 13

Absorber........................................................................................................................................... 15

Recovery Unit (Re-boiled Stripper) ............................................................................................... 17

Overall .............................................................................................................................................. 19

6 Plant Wide Control System Design ............................................................................................ 21

Pressure Driven Overall Flow Sheet .............................................................................................. 21

Dynamic Stripper: ........................................................................................................................... 22

Dynamic Absorber and Stripper: ................................................................................................... 22

7 Liquid Separation Scheme .......................................................................................................... 23

Materials to be recovered ............................................................................................................... 23

Development of Separation Sequence ........................................................................................... 23

Simplifying Assumptions ................................................................................................................ 26

Simulation of Separation Steps and Equipment Sizing ................................................................ 26

Distillation Columns .................................................................................................................... 28

Overall Process Balance .............................................................................................................. 28

Water Recovery ........................................................................................................................... 29

8 Pollutants And Their Control ...................................................................................................... 30

9 Modifications to Design .............................................................................................................. 31

Quench Column (Acidic) ................................................................................................................. 31

10 Plant Location .......................................................................................................................... 36

11 References ................................................................................................................................ 43

12 Appendix .................................................................................................................................. 44

Table of Contents


1 Introduction Acrylonitrile is a chemical compound with the formula C3H3N. This colourless liquid often appears yellow due to impurities. It is an important monomer for the manufacture of useful plastics such as polyacrylonitrile. In terms of its molecular structure, it consists of a vinyl group linked to a nitrile.

FIGURE 1: Lewis Structure.

Acrylonitrile (AN) is commercially produced by a reaction of propylene and ammonia in the presence

of a catalyst. Having both olefinic (C=C) and nitrile (C-N) groups permits a large variety of reactions

and makes ANa versatile chemical intermediate. The nitrile group can undergo hydrolysis,

hydrogenation, esterification and reduction. Reactions of the carbon double bond include

polymerization, copolymerization, cyanoethylation, cyclization and halogenation. One of the

reasons for the versatility of acrylonitrile is that it can form copolymers with other unsaturated

compounds, such as styrene and butadiene, for example a raw material for acrylic acid, acrylic

esters, acrylic amide in the synthesis of compounds used for the production of adhesives, anti-

oxidants, binders and emulsifiers. In its liquid state, acrylonitrile has a tendency to polymerize, which

is prevented by the addition of phenolic or amine-based stabilizers and small quantities of water.

Most industrial acrylonitrile is produced by catalytic ammoxidation of propene:

2CH3-CH=CH2 + 2NH3 + 3O2 CH=CH-CN + 6H2O TABLE 1: Chemical properties of Acrylonitrile

Chemical Name Acrylonitrile Regulatory Name 2-Propenenitrile, Acrylonitrile Molecular formula C3H3N Molecular weight 53.1 g/mol Density 0.81 g/cm3 at 25oC Boiling point 77.3oC Melting point -82oC Vapor pressure 100 torr at 23oC Solubility Soluble in isopropanol, ethanol, ether, acetone, and benzene Conversion factor 1 ppm = 2.17 mg/m3 at 25C DOT Label Flammable Liquid

Acrylonitrile (AN), also known as vinyl cyanide (CH2=CH-CN), is a high volume commodity chemical with worldwide production of more than 10 billion pounds per year. It contributes billions annually to the U.S. economy. Acrylonitrile is used as a monomer in the production of acrylic and modacrylic fibers, which accounts for approximately 50% of its global use.


Acrylic fiber is used for clothing, carpeting and other fabrics and in the production of rugged plastics for automotive components, computers, and appliances. Acrylic fiber is also used in the manufacture of polyacrylonitrile (PAN)-base carbon fibers; which are increasingly important materials for lightweight, high-strength applications in aeronautics, automotive, engineering, etc. Acrylonitrile is used as a co-monomer the production of acrylonitrile, butadiene, styrene (ABS) and styrene acrylonitrile (SAN) polymers, which accounts for an additional 31% of use. These polymers are used in a wide range of oil- and chemical-resistant nitrile rubber for industrial hoses, gaskets and seals. Acrylonitrile is also used as an intermediate in the production of other industrial chemicals, such as adiponitrile and acrylamide.

2 Price and Demand

FIGURE 2: Price of Acrylonitrile (ACN Highlights from 01-15, Feb 2013) In the first half of the last fortnight, selling offers for ACN went up at slow and steady pace. In the early first half of the last fortnight, ACN prices firm up in Asian market due to rise in feedstock rates, which supported the price rise. Prices were stable in European market due to poor energy market. In the early second half of the last fortnight, ACN prices surged in Asian market due to increase in feedstock value coupled with improved demand from the downstream market. It is produced in very large amounts (2.5 billion pounds in 1993) by five companies in the United States. U.S. demand is likely to increase 2 to 3 percent per year for the next several years. The largest users of acrylonitrile are companies that make acrylic and modacrylic fibers. Companies also use AN to make: high impact acrylonitrile-butadiene-styrene (ABS) plastics used in business machines, luggage, and construction material; styrene-acrylonitrile (SAN) plastics used in automotives and household goods and in packaging material; adiponitrile, a chemical used to make nylon; and dyes, drugs, and pesticides.

3 Health Effects

FIGURE 3: MSDS Label

Chemicals can be released to the environment as a result of their manufacture, processing, and use. EPA has developed information summaries on selected chemicals to describe how you might be exposed to these chemicals, how exposure to them might affect you and the environment, what happens to them in


the environment, who regulates them, and whom to contact for additional information. EPA is committed to reducing environmental releases of chemicals through source reduction and other practices that reduce creation of pollutants. Acrylonitrile is highly flammable & toxic. It undergoes explosive polymerization. The burning material releases fumes of hydrogen cyanide and oxides of nitrogen. It is classified as a Class 2B carcinogen (possibly carcinogenic) by the International Agency for Research on Cancer (IARC), and workers exposed to high levels of airborne acrylonitrile are diagnosed more frequently with lung cancer than the rest of the population. Exposure to acrylonitrile can occur in the workplace or in the environment following releases to air, water, land, or groundwater. Exposure can also occur when people smoke cigarettes or breathe automobile exhaust. Acrylonitrile enters the body when people breathe air or consume water or food contaminated with AN. It can also be absorbed through skin contact. It does not remain in the body due to its breakdown and removal. There are two main excretion processes of acrylonitrile. The primary method is excretion in urine when acrylonitrile is metabolized by being directly conjugated to glutathione. The other method is when acrylonitrile is metabolized with 2-cyanoethylene oxide to produce cyanide end products that ultimately forms thiocyanate, which is excreted via urine, or carbon dioxide and eliminated through the lungs.

Acrylonitrile evaporates when exposed to air. It dissolves when mixed with water. Most releases of acrylonitrile to the environment are to underground sites or to air. Acrylonitrile evaporates from water and soil exposed to air. Once in air, AN breaks down to other chemicals. Microorganisms living in water and in soil can also break down AN. Because it is a liquid that does not bind well to soil, acrylonitrile that makes its way into the ground can move through the ground and enter groundwater. Plants and animals are not likely to store acrylonitrile.

Exposure to acrylonitrile is primarily occupational. It is used in the manufacture of acrylic acid and modacrylic fibers. Acute (short-term) exposure of workers to acrylonitrile has been observed to cause mucous membrane irritation, headaches, dizziness, and nausea. No information is available on the reproductive or developmental effects of acrylonitrile in humans. Based on limited evidence in humans and evidence in rats, EPA has classified acrylonitrile as a probable human carcinogen (Group B1).

[The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS),

which contains information on inhalation chronic toxicity of acrylonitrile and the RfC and the

carcinogenic effects of acrylonitrile including the unit cancer risk for inhalation exposure, EPA's Health

Effects Assessment for Acrylonitrile, and the Agency for Toxic Substances and Disease Registry's

(ATSDR's) Toxicological Profile for Acrylonitrile.]

3.1.1 Sources and Potential Exposure Human exposure to acrylonitrile appears to be primarily occupational, via inhalation. Acrylonitrile may be released to the ambient air during its manufacture and use. 3.1.2 Assessing Personal Exposure Acrylonitrile can be detected in the blood to determine whether or not exposure has occurred. Metabolites may be detected in the urine, but some breakdown products are not specific to

acrylonitrile.

Acute Effects

Workers exposed via inhalation to high levels of acrylonitrile for less than an hour experienced mucous membrane irritation, headaches, nausea, feelings of apprehension and nervous irritability; low grade anaemia, leukocytosis, kidney irritation, and mild jaundice were also observed in the workers, with these effects subsiding with the ending of exposure. Symptoms associated with acrylonitrile poisoning include limb weakness, laboured and irregular breathing, dizziness and impaired judgment, cyanosis, nausea, collapse, and convulsions. A child died after being exposed to acrylonitrile by inhalation, suffering from respiratory malfunction, lip cyanosis, and tachycardia before death. Several adults exposed to the same concentration of acrylonitrile exhibited eye irritation, but no toxic effects.


Acute dermal exposure may cause severe burns to the skin in humans. Acute animal tests in rats, mice, rabbits, and guinea pigs have demonstrated acrylonitrile to have high acute toxicity from inhalation and high to extreme acute toxicity from oral or dermal exposure.

Chronic Effects (Non-Cancer) In one study, headaches, fatigue, nausea, and weakness were frequently reported in chronically

(long-term) exposed workers. In rats chronically exposed by inhalation, degenerative and inflammatory changes in the respiratory epithelium of the nasal turbinates and effects on brain cells have been observed. The Reference Concentration (RfC) for acrylonitrile is 0.002 milligrams per cubic meter (mg/m3) based on degeneration and inflammation of nasal respiratory epithelium in rats. The RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the RfC, the potential for adverse health effects increases. Lifetime exposure above the RfC does not imply that an adverse health effect would necessarily occur. EPA has medium confidence in the study on which the RfC was based because, although it was a well-conducted chronic study in an appropriate number of animals, it was performed on only one species, did not identify a no-observed-adverse-effect level (NOAEL), was confounded by the early sacrifice of rats with large mammary gland tumors and the target organ (nasal turbinates) was examined only at the end of the study in relatively few animals; medium to low confidence in the database because of the lack of chronic or subchronic inhalation data in a second species, the lack of reproductive data by the inhalation route and the existence of an oral study showing reproductive effects; and, consequently, medium to low confidence in the RfC. EPA has calculated a provisional Reference Dose (RfD) of 0.001 milligrams per kilogram body weight per day (mg/kg/d) for acrylonitrile based on decreased sperm counts in mice. The provisional RfD is a value that has had some form of Agency review, but it does not appear on IRIS.

Reproductive/Developmental Effects No information is available on the reproductive or developmental effects of acrylonitrile in

humans. Fetal malformations (including short tail, missing vertebrae, short trunk, omphalocele, and hemivertebra) have been reported in rats exposed to acrylonitrile by inhalation. In mice orally exposed to acrylonitrile, degenerative changes in testicular tubules and decreased sperm count were observed.

Cancer Risk A statistically significant increase in the incidence of lung cancer has been reported in several

studies of chronically exposed workers. However, some of these studies contain deficiencies such as lack of exposure information, short follow up, and confounding factors. In several studies, an increased incidence of tumors has been observed in rats exposed by inhalation, drinking water, and gavage. Astrocytomas in the brain and spinal cord and tumors of the Zymbal gland (in the ear canal) have been most frequently reported, as well as tumors of the stomach, tongue, small intestine in males and females, and mammary gland in females. EPA has classified acrylonitrile as a Group B1, probable human carcinogen (cancer-causing agent). EPA uses mathematical models, based on human and animal studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA calculated an inhalation unit risk estimate of 6.8 10-5 (g/m3)-1. EPA estimates that, if an individual were to continuously breathe air containing acrylonitrile at an average of 0.01 g/m3 (1 x 10-5 mg/m3), over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA estimates that breathing


air containing 0.1 g/m3 (1 x 10-4mg/m3) would result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air containing 1.0 g/m3 (1 x 10-3 mg/m3) would result in not greater than a one-in-ten thousand increased chance of developing cancer. For a detailed discussion of confidence in the potency estimates, please see IRIS. EPA has calculated an oral cancer slope factor of 0.54 (mg/kg/d)-1.

Hence, In conclusion the effects of acrylonitrile on human health and the environment depend on how much acrylonitrile is present and the length and frequency of exposure. Effects also depend on the health of a person or the condition of the environment when exposure occurs. Breathing acrylonitrile for short periods of time adversely affects the nervous system, the blood, the kidneys, and the liver. These effects subside when exposure stops. Nervous system effects of AN range from headaches and dizziness to irritability, rapid heartbeat, and death. Symptoms of acrylonitrile poisoning may occur quickly after exposure or after levels of breakdown products like cyanide build up in the body. Direct contact with acrylonitrile liquid severely damages the skin. Acrylonitrile liquid or vapor irritates the eyes, the nose, and the throat. These effects are not likely to occur at levels of acrylonitrile that are normally found in the environment. There are several health effects case studies of acrylonitrile workers. The methods used in these studies limit conclusions that can be made from the results. These studies show that workers repeatedly breathing small amounts of acrylonitrile over long periods of time may develop cancer. Cancer occurs primarily in the respiratory tract. Laboratory studies show that repeated exposure to acrylonitrile in air or in drinking water over a lifetime also causes cancer in animals. Studies also show that repeated exposure to acrylonitrile adversely affects the respiratory and central nervous systems and causes developmental toxicity in laboratory animals. Acrylonitrile has moderate toxicity to aquatic life. By itself it is not likely to cause environmental harm at levels normally found in the environment. Acrylonitrile can contribute to the formation of photochemical smog when it reacts with other volatile substances in air.

FIGURE 4: Health Data from Inhalation Exposure


ACGIH TLV--American Conference of Governmental and Industrial Hygienists' threshold limit value

expressed as a time-weighted average; the concentration of a substance to which most workers can be

exposed without adverse effect.

AIHA ERPG--American Industrial Hygiene Association's emergency response planning guidelines. ERPG 1

is the maximum airborne concentration below which it is believed nearly all individuals could be exposed

up to one hour without experiencing other than mild transient adverse health effects or perceiving a

clearly defined objectionable odour; ERPG 2 is the maximum airborne concentration below which it is

believed nearly all individuals could be exposed up to one hour without experiencing or developing

irreversible or other serious health effects that could impair their abilities to take protective action.

LC50 (Lethal Concentration50)--A calculated concentration of a chemical in air to which exposure for a

specific length of time is expected to cause death in 50% of a defined experimental animal population.

LOAEL--Lowest-observed-adverse-effect level.

NIOSH IDLH--National Institute of Occupational Safety and Health's immediately dangerous to life or

health limit; NIOSH recommended exposure limit to ensure that a worker can escape from an exposure

condition that is likely to cause death or immediate or delayed permanent adverse health effects or

prevent escape from the environment.

NIOSH REL--NIOSH's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-

h time-weighted-average exposure and/or ceiling.

OSHA PEL--Occupational Safety and Health Administration's permissible exposure limit expressed as a

time-weighted average; the concentration of a substance to which most workers can be exposed without

adverse effect averaged over a normal 8-h workday or a 40-h workweek.

The health and regulatory values cited in this factsheet were obtained in December 1999.

a. Health numbers are toxicological numbers from animal testing or risk assessment values developed by

EPA.

b. Regulatory numbers are values that have been incorporated in Government regulations, while advisory

numbers are non-regulatory values provided by the Government or other groups as advice. OSHA

numbers are regulatory, whereas NIOSH, ACGIH, and AIHA numbers are advisory.

c. The LOAEL is from the critical study used as the basis for the EPA RfC.

4 Sohio Process It is the most famous method used by industries in order to produce Acrylonitrile by Propylene.

Propylene and ammonia are reacted in the presence of air at almost stoichiometric quantities at 30 psia

and a temperature of 662F - 1112F. The catalysts used in the process are mostly based on mixed metal

oxides such as bismuth-molybdenum oxide, iron-antimony oxide, uranium-antimony oxide, tellurium -

molybdenum oxide etc. The reactor product is cooled by quenching with water and is neutralized using

sulphuric acid to remove unconverted ammonia. Acrylonitrile is removed by extractive distillation, while

crude acetonitrile and hydrogen cyanide are separated from the bottom products. Hydrogen cyanide is

then removed by distillation.

Some of the wastes that are generated from the process are processed as follows:


Ammonium sulphate that is produced as the bottoms product from the neutralizer can be used as a fertilizer. Unconverted ammonia is vented to the atmosphere. Aqueous wastes containing cyanides, sulphates etc., are disposed of either incinerated, deep well injection or by biological treatment.

Reactor

The reactor is a large-diameter cylindrical vessel provided with a gas -distribution grid for supporting the

fluid bed, as well as with injection devices for feeding the gaseous reactants. The optimal catalyst particles

size is in the range 40 to 100 m, in which the presence of a certain amount of fines is necessary for ensuring homogeneous fluidization. The gas velocity is slightly above the minimum, in general between

0.4 to 0.5 m/s. Trays or screens, usually between 5 and 15, can be placed transversally in order to reduce

the negative effect of back mixing. This modification gives much better performance in term of

acrylonitrile yield. Because of the highly exothermal reaction cooling coils are immersed in the fluid bed.

Since the temperature of reaction is around 420 450 C high pressure steam of 30 to 40 bar can be raised.

The feeding strategy of reactants should take into account the reaction mechanism. Usually, the oxygen

(air) is introduced below the bottom grid, with the mixed propylene and ammonia through spiders positioned above the grid. The catalyst plays an important role in preserving the safety as scavenger for

oxygen radicals. No explosion was ever encountered over decades of operation.

Figure 5: Sketch of the fluid - bed reactor for acrylonitrile synthesis.

The operating pressure should be as low as possible to prevent the formation of by-products. On the other side higher pressure would be preferable for quenching and scrubbing of gases. Overpressures of 0.5 to 2 bar are preferable. Almost complete conversion of propylene may be seen and selectivity around 80% in acrylonitrile can be obtained. The data are representative for modern catalysts. The residence time in the reactor is between 2 and 20 s, with an optimal range from 5 to 10 s. longer residence time gives more by-products. A more sophisticated design of the fluid - bed reactor requires advanced modelling and simulation capabilities. The main reactions and the side reactions of the process occur in reactor as follows:

CH2=CH-CH3 + NH3 + 3/2 02 C3H3N + 3 H20 Propylene Ammonia Oxygen Acrylonitrile Water Apart from the above main reaction there are the following side reactions:

CH2=CH-CH3 + O2 CH2=CH-CHO + H20 Acrolein Water


CH3=CH-CH3 + NH3 + 9/4 O2 CH3-CN + 1/2 C02 + 1/2 CO + H20 Acetonitrile

CH2=CH-CHO + NH3 + 1/2 02 CH2=CH-CN + 2H2O

CH3-CN + 3/2 02 CO2 + HCN +H2O

Kinetic data for the above reactions are given in Table 1 (Hopper, 1992).

TABLE 4.2

KINETIC DATA FOR THE ACRYLONITRILE PROCESS

Reaction Number Activation Energy, Ei (cal/mol)

Rate Constant, ki(sec-1) At 662 F

1 19000 0.40556

2 19000 0.00973

3 7000 0.01744

4 7000 6.81341

5 7000 0.073

The rate equations for the acrylonitrile process are:

(-r1)=k1CC3H6

(-r2)=k2CC3H6

(-r3)=k3CC3H6

(-r4)=k4CCH2CHCHO

(-r5)=k5CCH3CN

The rate constants, expressed in kj's, are expressed in the Arrhenius form as

ki,T1=ki,T2 * exp [-(E/R){(1/T1)-(1/T2)}]

Where:

k = Rate constant,

E =Activation energy,

T1 and T2 = Temperatures.

R = Gas constant.

On conversion of the above parameters (as shown in Appendix), the equations become:

(-r1)=1.57089 * 105 * exp(-19000/RT)

(-r2)=3.768 * 103 * exp(-19000/RT)

(-r3)=1.99 * exp(-7000/RT)

(-r4)=780.07 * exp(-7000/RT)

(-r5)=8.357 * exp(-7000/RT)

Effect of different variables on Conversion

1. Effect of Residence Time: The residence time of the inlet particles in the reactor is related to the

volume of the reactor as per equation


= Where is the residence time. V is the volume of reactor

Q is the flow rate of feed

Therefore, varying the reactor volume effectively varied the residence time.

Figure 6: Effect of residence time on conversion

2. Effect of Reaction Temperature

The conversion of the key inlet component in the PFR and the CSTR schemes increases as the

temperature increases. The conversion increases from 11 % to 63% for CSTR for a temperature range of

700F to 1000F. The conversion increases from 12% to 71 % when the reactor used is a PFR for the

same temperature range.

Figure 7: Effect of Reaction Temperature on Conversion.

3. Effect of Reaction Pressure

The conversion in a PFR scheme varies from 14% to 53%. The conversion increases for a CSTR too within the same pressure range from 13.5% to 43 .8%. It can also be seen from the trend in figure given below that the conversion increases at a much higher rate for the PFR rather than a CSTR.


Figure 8: Effect of reaction pressure on conversion.

4. Effect of Catalyst

The catalysts used in the process are mostly based on mixed metal oxides such as bismuth-molybdenum

oxide, iron-antimony oxide, uranium-antimony oxide, tellurium - molybdenum oxide etc. Conversion of

Propylene various with different composition of metals in catalyst.

Mechanism proposed is appended below:


I) Reactor 2) Neutralizer 3) Absorber 4) Recovery 5) HCN Column 6) Extractive Distillation Column 7) Acetonitrile Purification Column 8) Acrylonitrile Purification Columns

Figure 9: Process flow diagram of the Acrylonitrile Process

5 Aspen Simulation

Reactor Industrially Fluidized Catalytic Cracker is used as a reactor and since most of the reaction (nearly 80%) occurs in the riser of FCC unit so we can approximate that with PFR (Plug

flow reactor) which is available there in Aspen Plus. Property Method used in simulation: NRTL

B11

2


Quencher

It is used to remove ammonia from the reactor effluent and low down its temperature using

sulphuric acid. It produces ammonium sulphate salt ((NH4)2SO4) at bottom which is used as a

fertilizer and the top effluent is sent to absorber.

Simulation of quencher is done using RadFrac model.

Property Method used : UNIQUAC

No. of Stages : 10

Sulphuric acid: 30% concentrated H2SO4

React or Design

Stream ID 1 2T emperature K 623.1 685.1Pressure atm 2.20 2.20Vapor Frac 1.000 1.000Mole Flow kmol/hr 4008.000 4123.149Mass Flow kg/hr 114854.402 114854.402Volume Flow l/min 1.55259E+6 1.75611E+6Ent halpy MMBtu/hr 26.062 -77.890Mole Flow kmol/hr AMMONIA 408.000 177.703 O2 646.000 295.512 H2O 30.000 725.933 PROP Y-01 340.000 104.662 ACRYL-01 230.296 ACROL-01 5.041 CO2 0.001 CO 0.001 ACET O-01 0.001 HYDRO-01 N2 2584.000 2584.000

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0 0.5 1 1.5 2 2.5

Conversion

Along the length of the reactor, m


Bottom stream coming out of quencher mainly consists of ammonium sulphate. This stream is

further passed into Crystallizer where crystals of ammonium sulphate are produced which is

used as fertilizer.

Quencher DesignStream ID 3 4 5 6Temperature K 513.0 601.1 308.7 405.7Pressure atm 1.00 2.00 4.00 3.00

Vapor Frac 0.932 1.000 0.000 1.000Mole Flow kmol/hr 300.000 4123.149 980.761 3264.685Mass Flow kg/hr 12610.362 114854.402 33917.221 93547.543Volum e Flow l/m in 196081.905 1.69469E+6 739.243 603747.856Enthalpy MMBtu/hr -108.716 -90.515 -171.056 -28.174Mole Flow kmol/hr

PROPY-01 104.662 8.658 96.004

OXYGEN 295.512 0.560 294.952 AMMONIA 177.703 trace trace

CARBO-01 0.001 < 0.001 0.001

HYDRO-01

ACRYL-01 230.296 163.867 66.429 ACROL-01 5.041 2.546 2.495 ACETO-01 0.001 0.001 < 0.001

WATER 210.000 725.933 712.387 223.546 SULFU-01 90.000 0.187 0.961 AMMON-01 88.851 trace CO 0.001 trace 0.001

N2 2584.000 3.703 2580.297


Absorber

Function of Absorber is to remove the residual gases, containing unconverted propylene, CO2

and other VOC.

Simulation is done using RateFrac model

Property method used: UNIQUAC

Random Packing: 5 segments of Raschig rings made up of ceramic, diameter=0.375in

Height of each packing segment=10ft

Column Diameter=5ft

Columns with random packing are best suited for liquid flows at high velocity.

For feeding liquid into the absorber, orifice type distributor is used. Since the depth of

packing>20ft, a distributor is needed for liquid.


Absorber Des ign

Stream ID 7 8 9 10

Temperature K 303.1 278.1 278.7 288.2

Pressure atm 2.00 1.00 2.00 2.20

Vapor Frac 0.950 0.000 1.000 0.000Mole Flow kmol/hr 3264.685 10122.870 2940.477 10447.079Mass Flow kg/hr 93547.543 182366.337 84437.083 191476.797Volume Flow l/min 643255.296 3001.633 560282.200 3219.146

Enthalpy MMBtu/hr -44.938 -2754.141 -2.686 -2796.394Mole Flow kmol/hr

PROPY-01 96.004 65.706 30.298 OXYGEN 294.952 292.418 2.533 AMMONIA trace

CARBO-01 0.001 0.001 < 0.001

HYDRO-01

ACRYL-01 66.429 3.970 62.459 ACROL-01 2.495 0.151 2.344 ACETO-01 < 0.001 trace < 0.001

WATER 223.546 10122.870 12.932 10333.484 SULFU-01 0.961 trace 0.961

AMMON-01 trace

CO 0.001 0.001 trace

N2 2580.297 2565.298 14.999

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 20 40 60 80 100 120

ACN Recovery

Feed Temp (C)


Recovery Unit (Re-boiled Stripper)

Idea is to recover the useful components from the aqueous solution like ACN, AN etc.

Simulation is done using Radfrac packed stripper column

Property method used: UNIQUAC

No. of stages: 10

Boil up ratio: 1

Random Packing: Saddles made up of ceramic, diameter=0.5in

Total tower height=40ft

Column diameter=5ft

Air cooled heat exchanger: Forced daft, Aluminium fins, 0.5in fin height, 7 fins/linear

inch, axial flow fans

Decanter: Plate contactor

0.95

0.955

0.96

0.965

0.97

0.975

0.98

0.985

0.99

0.995

1

0.2 0.3 0.4 0.5 0.6 0.7

ACN Recovery

Packing diameter (in)


Recovery column Des ign

Stream ID 10 15 13 16Temperature K 288.2 287.9 300.0 378.4

Pressure atm 2.20 1.20 1.20 1.20Vapor Frac 0.000 0.000 0.000 0.000

Mole Flow kmol/hr 10447.079 7334.782 114.226 10332.857Mass Flow kg/hr 191476.814 132138.154 5250.614 186226.267Volume Flow l/min 3219.146 2194.977 134.460 3401.570Enthalpy MMBtu/hr -2796.394 -1990.986 8.414 -2739.310Mole Flow kmol/hr

PROPY-01 30.298 30.298 trace

OXYGEN 2.533 2.533 trace AMMONIA

CARBO-01 < 0.001 < 0.001 trace HYDRO-01

ACRYL-01 62.459 62.459 trace ACROL-01 2.344 2.344 trace

ACETO-01 < 0.001 < 0.001 trace

WATER 10333.485 7334.782 1.593 10331.895 SULFU-01 0.961 < 0.001 0.961

AMMON-01

CO trace trace trace

N2 14.999 14.999 trace

0.98

0.982

0.984

0.986

0.988

0.99

0.992

0.994

0.996

0.998

1

0.2 1.2 2.2 3.2 4.2 5.2 6.2

AN Recovery

Boil up ratio


Overall

6

789

3

5

B4B5

B7

1

B1

B24

B3

B6

B8

B9

10

1112

13

14

15

16


Overall DesignStream ID 1 3 5 8 9 13 16Temperature K 623.1 513.0 308.7 278.1 278.7 300.0 378.4Pressure atm 2.20 1.00 4.00 1.00 2.00 1.20 1.20Vapor Frac 1.000 0.932 0.000 0.000 1.000 0.000 0.000Mole Flow kmol/hr 4008.000 300.000 980.760 10122.870 2940.477 114.226 10332.857Mass Flow kg/hr 114854.402 12610.362 33917.204 182366.337 84437.082 5250.614 186226.267Volume Flow l/min 1.55259E+6 196081.905 739.243 3001.633 560282.193 134.460 3401.570Enthalpy MMBtu/hr 26.062 -108.716 -171.056 -2754.141 -2.686 8.414 -2739.310Mole Flow kmol/hr PROPY-01 340.000 8.658 65.706 30.298 trace OXYGEN 646.000 0.560 292.418 2.533 trace AMMONIA 408.000 CARBO-01 < 0.001 0.001 < 0.001 trace HYDRO-01 ACRYL-01 163.867 3.970 62.459 trace ACROL-01 2.546 0.151 2.344 trace ACETO-01 0.001 trace < 0.001 trace WATER 30.000 210.000 712.387 10122.870 12.932 1.593 10331.895 SULFU-01 90.000 0.187 trace < 0.001 0.961 AMMON-01 88.851 CO trace 0.001 trace trace N2 2584.000 3.703 2565.298 14.999 trace


6 Plant Wide Control System Design

Pressure Driven Overall Flow Sheet

In order to put controllers in plant, first, whole plant is made pressure driven using pumps,

compressors and valves etc. Pressure driven overall flow sheet is appended below:


Dynamic Stripper:

Dynamic Absorber and Stripper:

B 1 4

B 1 5

B 1 7

B 1 8

B 1 9

P C 1

L C2

1 5

1 6

1 7

1 8

1 9

2 0

2 12 2

B 1 1

B 1 3

B 1 4

B 1 5

B 1 6

P C 1

L C2

B 1 7

B 1 8

B 1 9

P C 3

L C4

B 2 0

B 2 1

1 31 8

2 0

2 1

2 2

2 5

2 8

2 9

3 0

3 1

3 2 3 3

3 4

3 5


7 Liquid Separation Scheme

Materials to be recovered

The raw acrylonitrile stream contains approximately 85% acrylonitrile and 5% water, the rest being

organic impurities, namely HCN, Acrolein and acetonitrile. This section will handle the treatment of the

raw acrylonitrile stream recovered by absorption-stripping as described previously. The dissolved gases

from stripping column are neglected. Also, for the purposes of simulation, heavies present in raw

acrylonitrile product are neglected. In practice they are separated as bottom streams along with cyano-

acrolein, which is produced in HCN separation column.

Development of Separation Sequence

T-xy for ACRYL-01/HYDRO-01

Liquid/Vapor Molefrac ACRYL-01

Tem

pera

ture

C

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

2530

3540

4550

5560

6570

7580

T-x 1.0133 barT-y 1.0133 bar

From the binary distillation curve of AN and HCN, it is evident that both streams can be obtained as pure

species. However, since the composition of stream is far from equimolar, therefore in a single column

with reasonable number of trays and condenser duty, large amount of AN also goes into the top stream.

Therefore, a second column at lower pressure is used to recover AN from the top stream. Net AN

Recovery is close to 99.9%, however, some of HCN is lost due to reaction with Acrolein. This reaction is

important for removal of Acrolein in the form of heavies. CH = CH CH HC C CH CH CH CH = CH C HC C CH CH C HCN and Acrolein are both toxic. Also, HCN is most easily separated component. By using heuristics for

design, these 2 components are removed first.


T-xy for ACRYL-01/ACETO-01


Tem

pera

ture

C

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

7878

.5

7979

.5

8080

.5

8181

.5

T-x 1.0133 barT-y 1.0133 bar

After removing HCN, AN and ACN are valuable components that can be recovered from bottom streams.

However, the binary distillation curve for AN-ACN mixture suggests that separation by ordinary

distillation is extremely difficult. In such a scenario, changing column pressure may be considered. It is

observed that changing the pressure does not have a great effect on relative volatilities. Therefore this

option is ruled out. Addition of another component to change the relative volatilities is considered next.

An ideal extracting fluid must:

Sufficiently change relative volatility Be easily separated from two components Water is used as an extracting fluid because it is readily available and non-toxic. Residue curve of water-

AN-ACN system shows that a large amount of water is required to ensure efficient separation. Water to

feed ratio for extractive distillation is 10:1. AN is obtained as a top product whereas ACN is obtained as a

side stream. The bottom product consists of heavies (such as cyano-acrolein and is sent to wastewater

treatment section).


Residue curve for ACRYL-01/WATER/ACETO-01

Molefrac ACRYL-01

Mole

frac

ACET

O-01 M

olefrac W

ATER

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0.90.8

0.70.6

0.50.4

0.30.2

0.1

Extractive distillation step leads to 2 product streams with water present in them. From the binary

distillation curves of AN-water and ACN-water, following features of the separation scheme are

immediate:

Acylonitrile may be obtained as a pure component if AN conc. in the input stream is high. This can be achieved if less water is entrained in the top stream of extractive distillation. This achieved by

using a decantor for phase separation. Side stream contains large amount of water, whereas the amount of valuable ACN is very small. From the binary distillation curve it is evident that at best the azeotropic point can be reached.

However, this should be good enough a concentration because amount of ACN is anyway small (5

moles for 100 moles of raw-AN). Therefore a small amount of water can be separated by

advanced drying techniques.

T-xy for ACRYL-01/WATER


Tem

pera

ture

C

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9 0.95 1

6570

7580

8590

9510

010

5

T-x 1.0133 barT-y 1.0133 bar


Extractive distillation is defined as distillation in the presence of a miscible, high boiling, relatively non-volatile component, the solvent, that forms no azeotrope with the other components in the mixture. The method is used for mixtures having a low value of relative volatility, nearing unity. Such mixtures cannot be separated by simple distillation, because the volatility of the two components in the mixture is nearly the same, causing them to evaporate at nearly the same temperature at a similar rate, making normal distillation impractical. The solvent interacts differently with the components of the mixture thereby causing their relative volatilities to change. This enables the new three-part mixture to be separated by normal distillation.

T-xy for ACETO-01/WATER

Liquid/Vapor Molefrac ACETO-01

Tem

pera

ture

C

0 0.2 0.4 0.6 0.8 1

6065

7075

8085

T-x 0.5 barT-y 0.5 bar

Simplifying Assumptions Gases present in raw acrylonitrile are neglected and therefore not accounted for in simulation steps. In practice, they are vented out in phase separators. In case of distillation columns, equilibrium separations are assumed for the base case design.

Simulation of Separation Steps and Equipment Sizing

The simulated process flow sheet is shown below. It consists of 5 fractionation columns and 2 decanters.

LS1 Column to separate HCN from Raw acrylonitrile

LS2 Column to recover AN and ACN from vapor stream of HCN

LS4 Extractive Distillation of AN and ACN using water

LS7 Separate the side stream from extractive distillation to remove water from acetonitrile

LS8 Separate top stream from extractive distillation to obtain pure acrylonitrile

LS5 Decanter to separate and recycle water from the top stream of extractive distillation

LS9 Decanter to phase separate water and acrylonitrile to further purify product stream

A steady state simulation is carried out to fit the flow sheet, so as to obtain following design parameters.

Reasonable initial guesses are taken considering typical industrial columns used for similar separation

factors. The design parameters are thereby optimized to obtain maximum product recovery as well as

minimum or negligible side products in the final product stream.


Distillation Columns

Column LS1 LS2 LS4 LS7 LS9

Stages

40 F=10

30 F=10

40 F=20 ExtW=1 R=20

20 F=5

30 F=15 R=15

Pressure (bar) 1.1 1 1.22 0.5 1.1

Reflux ratio 2 5.35 0.2

Boilup ratio 3 8.5 0.1 1

Distillate to feed ratio 0.18 0.006

Top Temp (oC) 61.83 30.40 85.22 56.37 73.59

Bottom Temp (oC) 80.04 71.00 105.40 80.97 74.81

Condenser type Total Total Total Total Total

Q cond (MW) 0.4915 0.1719 1.4898 0.8740

Q reboiler (MW) 0.5198 0.1726 2.2250 1.0524 0.9164

Tray type Sieve Sieve Sieve Sieve

Tray Spacing (m) 0.5 0.6 0.8 0.6

Packing type Ceramic

Raschig ring

Packed HETP (m) 0.5

Packing void fraction 0.73

Packing surface area (cm2/cm3) 1.95

Column diameter (m) 0.648 0.340 2.035 1.167 0.7684

Overall Process Balance

Input Product Streams Wastewater

Streams RAW-AN EXTW T-LS2 B-LS8 T-LS7 B-LS4 B-LS7 D-LS9

Temperature oC

65 75 30.4 74.8 56.4 105.4 81 60

Pressure bar

1.1 1.22 1 1.1 0.5 1.22 0.5 1.1

Vapor Frac 0 0 0 0 0 0 0 0

Mole Flow kmol/hr

100 946.5 5.35 98.866 5.447 23.236 902.393 10.708

Mass Flow kg/hr

4948.376 17051.46 158.679 4718.7 193.088 424.317 16299.78 205.28

Volume Flow m3/hr

6.703 18.065 0.227 6.513 0.267 0.466 17.407 0.223

Enthalpy MMkcal/hr

2.972 -63.767 0.123 2.115 -0.05 -1.547 -60.62 -0.687

Mole Flow kmol/hr

AN 85 0 0.616 83.677 0.355 0 0 0.352

HCN 5 0 4.498 0 0.002 0 0 0

ACN 4.5 0 0.008 0.211 3.581 0 0.698 0.002

Acrolein 0.5 0 0 0 0 0 0 0

Water 5 946.5 0.228 14.978 1.509 23.149 901.283 10.354

Heavies 0 0 0 0 0 0.088 0.412 0

Product

HCN AN ACN

Recovery (%)

89.96 98.43 79.58

Mol frac. 0.8407 0.8464 0.6574

Wt frac. 0.7654 0.9397 0.7607

It can be seen that the process gives reasonable recoveries for all the products. The main product of this

process, acrylonitrile is recovered up to 98.43%. However, the purity of product streams is not very high.


Most of them contain entrained water and therefore additional separation steps may be required to

remove water depending on the application.

Water Recovery

For extractive distillation, large amount of water is required. Therefore the process results in large

amount of wastewater. This mostly consists of heavies and small amount AN and ACN that could not be

recovered. It is therefore desirable to separate pure water from this stream, so that it can be recycled for

extractive distillation. Also, the remaining effluent can be further treated to recover remaining valuable

products depending on product and operating costs. Pure water is recovered from wastewater in WT1.

The process leads to recovery of 98.73% recovery of water used for extractive distillation and can be

recycled to reduce the overall water requirement for the process.


8 Pollutants And Their Control Air Pollution

Absorber Vent Gas. The absorber vent gas stream contains nitrogen, oxygen, unreacted propylene ,

hydrocarbon impurities from the propylene feed stream, CO, CO2, water vapour, and small quantities of

ACN, acetonitrile, and hydrogen cyanide. Two control methods are used to treat this stream: thermal

incineration and catalytic oxidation.

The thermal incineration units have demonstrated VOC destruction efficiencies of 99.9% or greater, while

most catalytic units can achieve destruction efficiencies only in the 95-97% range. Destruction efficiencies

in the 99% and greater range can be achieved with catalytic oxidizers, but these are not achieved on a

long-term basis because of deactivation of the catalyst by a number of causes. The advantage of catalytic

oxidation is low fuel usage, but emissions of NOx formed in the reactors and not destroyed across the

catalyst can pose problems.

Column Waste Purge Gas. Waste gas releases from the recovery column, light-ends column, product

column, and the acetonitrile column are frequently tied together and vented to a flare. The estimated VOC

destruction efficiency of the flare is 98-99% for all streams with a heat content of 300 Btu/scf or greater.

The use of a flare is ideally suited for streams that are intermittent and having heating values of 300

Btu/scf.

Fugitive emissions. Fugitive emissions from piping, valves, pumps, and compressors are controlled by

periodic monitoring by leak checking with a VOC detector and a directed maintenance program.

Incinerator Stack Gas. Staged combustion and ammonia injection are used to control the emissions of NOx

from the incinerator that treats the absorber off-gas vent, the crude acetonitrile waste gas stream, and the

by-product liquid HCN stream. Staged combustion suppresses the formation of NOx by operating under

fuel-rich conditions in the flame zone where most of the NOx is formed and oxygen-rich conditions

downstream at lower temperatures where NOx is not appreciably formed.

Ammonia injection reduces NOx by selectively reacting ammonia with NOx. The reaction occurs at

temperatures in the range of 870-980C (1600-1800F) and, as such, the ammonia must be injected in the

postflame zone of the combustion chamber. Residence times of 0.5-1.0 second are required for NOx

destruction efficiencies in the range of 80%, which is compatible with the residence time required for

VOC destruction.

Deep Well/Pond Emissions. Emissions of acrolein and other odorous components in vents from

wastewater treatment steps are controlled with water scrubbers. In some cases, pond emissions are

controlled by adding a layer of a low-vapor-pressure oil on the surface of the pond to limit volatilization.

Storage Tank Emissions. Product storage tank emissions are controlled with double-seal floating roofs or,

in some cases, water scrubbers. Field experience indicates that a removal efficiency of 99% can be

achieved with water scrubbing.

Product Transport Loading. Emissions from product transport loading vents are gathered and sent to a

flare or incinerator for VOC control. Destruction efficiencies of 98-99% are achieved using the flare and

greater than 99% using incineration.

Solid/Liquid Waste

Wastes include salts of hydrogen cyanide, metal cyanide complexes, and organic cyanides (cyanohydrins)

as solutions or solids. The wastewater from the wastewater column contains ammonium sulphate and

heavy hydrocarbons, while the wastewater from the acetonitrile column mainly contains heavy bottoms.

The wastewater from both these columns is typically dis-charged to a deep well pond. Other methods of

waste treatment include alkaline chlorination in a recycle lagoon system, and incineration.


9 Modifications to Design

Quench Column (Acidic)

Quench column is used to cool the reactor outlet to 30oC, as well as remove ammonia as sulphate. The

feed gas is quenched with 30-40% sulphuric acid. Recycled water is added to compensate for

vaporization losses.

Equipment:

The quenching is carried out in a packed column in order to increase the heat transfer area as well as area

for dissolution of ammonia. Since sulphuric acid is highly corrosive, ceramic packing in the form Raschig

rings are used. Random packing is used due to high flow rates. (Similar packing is used in manufacture of

sulphuric acid, in SO3 absorption to form oleum.) In order to prevent corrosion of column walls, it is lined

with glass. The ring diameter in packing is large (1in) in order to prevent clogging due to tiny catalyst

particles.

Associated Problem:

Modelling a quench column is particularly difficult because of 5 main processes that take place in a single

transfer unit: Transfer of NH3 into the liquid phase Reaction b/w NH3 and H2SO4 in the bulk liquid phase Vaporization of water from liquid phase Heat transfer Clogging of catalyst particles into packing To simplify the problem, clogging can be ignored. However, on simulation in aspen, the model failed to

give a satisfactory result.

Semi Quantitative Analysis using CFD in Comsol Multiphysics

Balance for a Differential element:

AL : Acid (liquid phase)

NL and NG : Ammonia in liquid and gas phase respectively

WL and WG : Water in liquid and gas (vapour) phase respectively


SL : Ammonium sulphate dissolved in liquid phase

BG : Gases that are sparingly soluble and hence ignored in mass transfer (ACN, HCN, AN, propylene etc)

dN : Transfer of ammonia from gas to liquid

dW : Vaporization of water

r : Rate of reaction for dissolution of ammonia in sulphuric acid

a : Effective area

Use of CFD

In order to obtain a better insight into the problem, CFD simulations are carried out using COMSOL

Multiphysics. The motivation is to model a smallest repeated transfer unit of the column for all the above

factors. The following assumptions are made for developing a basic model:

1. Radial variations in the column are neglected unless there is a different stream. That is, both

liquid and gas streams are radially uniform and vary only along the length of the column.

2. The channelled flow through the packing can be assumed to be a flow through a cylinder of

radius same as the Raschig ring.

3. The gas is assumed to bubble through the liquid inside the flow domain. Further, concentration of

NH3 inside a single bubble is uniform.

4. The dissolution of NH3 follows first order kinetics. This is a fair assumption since sulphuric acid

is in a large amount (for cooling requirements).

The assumptions stated above lead to the following geometry.

Methodology:

Initially fluid flow in the geometry is used as a base model. Later transport of diluted species (with

reaction) and heat transfer are added and coupled with the initial physics. To keep the model simple,

vaporization is ignored for the time being.

Simulation results in velocity profiles, concentration profiles and heat transfer. In 2D axisymmetric

domain, the line integral of concentration along the radius multiplied with velocity gives the total species

transfer. Such units can be taken as an array to build the entire column.

Simulation Results:

Velocity Concentration (NH3) Temperature


With a steady state model in place, it has to be used now for actual equipment design. For this purpose

another simplifying assumption is made. For each Raschig ring, we assume pseudo steady state. Which

means, a single Raschig ring can be analysed for steady state model. However, two different rings may be

at different steady states. With steady state simulation as a base model, time dependent steady is carried

out.

The actual process of quenching operates at steady state. The time dependent analysis actually simulates the spatial motion of a gas bubble across the column through different rings. For example t=0, is the state when gas enters the column and t=tR is the state when gas leaves the column. Therefore the final result of this analysis would provide the required residence time.

Since sulphuric acid is used in excess for cooling the gas and ammonia reacts to form salt in liquid phase,

the concentration of ammonia is neglect at each ring inlet.

Initial concentration of NH3 (assuming ideal gas mixture) is 0.0347 mol/m3. Final product should have

atleast 99% of ammonia removed. By transient analysis we plot the volume averaged concentration in gas

bubble vs time.

At about t=15s, the conc decreases below required value. Hence, the required residence time for the

reactor considering ammonia absorption is 15s.

However, for considering heat transfer, more careful analysis is needed because the ring inlet

temperature of liquid also changes across the length of column. The approach followed here is to use the

residence time obtained by mass transfer considerations and find the temperature change for various


values of ring inlet temperature ( ). Since the operation is like a counter current heat exchanger, temperature of gas is taken as . The transient temperature profile is normalized with .

It is observed that tR = 15s is sufficient for heat transfer operations also. Hence, this is the required

residence time.


Economy Optimization: Economy ptimization is simulated in Haskell. Code is appended below:

data Unit = Unit { pid :: String,

inp :: [Stream],

otp :: [Stream],

util :: [Utility]

} deriving (Show)

data Stream = Stream { sid :: String,

comp :: [(String, Double)],

flow :: Double

} deriving (Show)

data Utility = Utility { uid :: String,

val :: Double

} deriving (Show)

type CostTable = [(String, Double)]

lookUp :: CostTable -> String -> Double

lookUp [] x = 0

lookUp ((a,b) : ls ) x | (a==x) = b

| otherwise = lookUp ls x

costStr :: CostTable -> Stream -> Double

costStr cT a = (flow a) * sum (map (mult cT) (comp a))

mult :: CostTable -> (String, Double) -> Double

mult cT x = snd(x) * lookUp cT (fst x)

costUtil :: CostTable -> Utility -> Double

costUtil cT a = val a * lookUp cT (uid a)

margin :: CostTable -> Unit -> Double

margin cT a = sum (map (costStr cT) (otp a)) +

sum (map (costUtil cT) (util a)) -

sum (map (costStr cT) (inp a))

costTab :: CostTable

costTab = [("HCN", 100),

("AN", 500),

("ACN", 200),

("lp-steam", 15),

("mp-steam", 20),

("hp-steam", 40),

("C3H6", 70),

("air", 0),

("Cool-water", 5)

]


10 Plant Location

Naturally to obtain the plant location we had to look at a number of aspects primarily Availability of raw materials Industrialized Hub Market Demand for the Products Transportation and Port Access Skilled Workforce

Ammonia :

Taking a closer look at these aspects for Ammonia we found the major producing regions of Ammonia

being :

1. GSFC (Baroda) 1350

2. Nagarjuna Fertilizers (Kakinada) 900

3. Tata Chemicals Ltd. 1350

4. IFFCO (Kalol) 1160

5. GNFC (Bharuch) 1350

6. Shriram Fertilizers (Kota) 600

7. KRIBHCO (Hazira) 2600

8. National Fertilizers (Panipat) 900

The numbers indicate production.

Fig 1: Ammonia Price

Ref:http://www.agr.gc.ca/pol/maddam/index_e.php?s1=pubs&s2=rmar&s3=php&page=rmar_01_0

3_2009-07-10

Most of the ammonia plants set up in India until 1968 were on a turnkey basis. In 1966, the Government

of India decided to set up a series of single stream 600 TPD ammonia plants. Ammonia plants at

Durgapur, Barauni and Cochin were set up through foreign aid which also included supply of

equipment.Some of these plants have not performed well due to improper equipmentselection. Over a

period of time, the performance got worse and some of theseplants have been shut down. Subsequently,

Indian fertilizer companies selected reliable technology andproper equipment on the basis of competitive

bidding. With the discovery oflarge reserves of offshore gas, a number of 1350 TPD ammonia plants

arebeing installed based on technology supplied by Haldor Topsoe and M. W.

The 36% to 94% for naphtha based plants, 56% to 81 %for fuel oil-based plants, 44% to 92% for gas

based plants and only 20% to 42% for coal based plants. Specific energy consumption also showed wide


deviations with reference to the process, the feedstock and the year ofinstallation. The best performance

was recorded by the gas-based plant of 1FFCO, Kalol with 8.98 Kcal/tonne of ammonia. The source of

hydrogen was then changed over to fuel oil and finally to natural gas and naphtha. Natural gasis an ideal

feedstock, which is cheap, easily transportable by pipelines and relatively pure.capacity utilisation

(averaged over last five years) of the ammonia plantsvaried from plant to plant.

DISTRIBUTION OF AMMONIA CAPACITY:

Amongst the operating plants, maximum ammonia capacity exists in Gujarat (21.9% of total installed

capacity), followed by Maharashtra (15.6%). Maximum operating capacity exists in the public sector

(56%) followed by the the private sector (27%) and the co-operative sector (17%). However,

amongplants under implementation, 60% of the capacity lies in the private sector,resulting in public

sector's share as 49% followed by the private sector with 35% and the co-operaive sector with 16%.

Fig 2: Ammonia Feedstocks

Ref : http://www.dsir.gov.in/reports/techreps/tsr019.pdf


Fig 3 : Current and Propoed Gas Pipelines in India

Refhttp://www.tribuneindia.com/2004/20040304/science.htm

Propylene

In India total ethylene capacity is expected to reach 4987 KTA by 2016-17 and Reliance Industries Ltd has

planned capacity expansion to2898 KTA by 2016-17 followed by IOC at 565 KTA, HMEL at 450, HPL

Halida at 345 KTA, ONGC OPAL at 340 KTA, and BPCL at 170 KTA.

Meanwhile, Propylene prices have increasingly become volatile from 500 $/tonne (Spot CFR NE Asia) in

April 2002 it has touched close to 1500 $/tonne in recently in March 2012 and currently at 1150 $/tonne

in June 2012. (Source ICIS)


Fig : Current and Future Share of Major Propylene Producers Ref : http://cpmaindia.com/propylene_about.php

Table : Projected and Current Propylene Production in India

Capacity (kt) Actual Projected

2011-12 2012-13 2013-14 2014-15 2015-16 2016-17

RIL Group 2778 2728 2728 2728 2898 2898

GAIL, Auraiya 35 35 70 70 70 70

HPL, Haldia 345 345 345 345 345 345

HPCL Vizag 54 54 54 54 54 54

HMEL, Bhatinda 225 450 450 450 450 450

BPCL 130 170 230 230 230 230

IOC 565 565 565 565 565 565

OPAL 340 340 340

Others 75 35 35 35 35 35

Total 4117 4382 4477 4817 4987 4987


Propylene Derivatives 2010-11 2011-12 % Share Growth Rate

2011-12 (%)

PP 3004 3796 95% 26%

2-EH/Oxo-Alcohol 73 74 2% 1%

Phenol 40 40 1% 0%

Acrylonitriile 42 44 1% 5%

Propylene Oxide 23 23 1% 0%

IPA 0 0 0%

Epichlorohydrin 7 7 0% 0%

n-Butanol 15 15 0% 0%

EPDM 0 0 0%

Total 3203 3999


Gujarat is Indias Petro Capital State with % of Petrochemicals, % Chemicals and Pharmaceuticals business. Ranking on top in Marine Production, Fisheries and Ports, the state has manufacturing Indias 90% soda ash, 70% salt and 20% caustic soda. Petroleum and chemicals and Petroleum Investment

Region (PCPIR) is being set up at Dahej which may further add to strengthen the sector base. Gujarat has the distinction of being the rst state to enact the Special Economic Zone SEZ Act, . Special Economic Zones (SEZs) are growth engines that can boost manufacturing, augment exports and

generate employment. The Government has introduced the scheme of SEZs in order to provide a hassle

free operational regime and encompassing state of the art infrastructure and support services.

Special Economic Zone (SEZ) is a specifically delineated duty free enclave and shall be deemed to be


foreign territory for the purpose of trade and operations and duty and tariffs. SEZ units may be set up for

manufacture of goods and for rendering of services public, private or joint sector or by the State Government.

SEZs, cover industrial and labour aspects, including flexible labour laws and exit options. The Gujarat SEZ

Act, 2004 has made key provisions with respect to the appointment and termination of labour for units

established in SEZs.

he concept of Fixed erm Employment introduced by the SEZ Act has helped in accounting for the least manpower days lost due to labour strife, among comparable industrial states.

SEZs in Gujarat approved by the MoCI, New Delhi as on 30/09/2008

Formal approval to SEZs Land recommendation by GOG for SEZs (in hectare)

Total

Functional SEZs before enactment of Act 506.54 03 *Notified and Functional * 9808.62 07 Notified SEZs 6114.17 15 Formal approval to SEZs 7733.09 24 In-principle approval to SEZs 5231.41 11 Total 29423.83 60

Gujarat, the state which pioneered the concept of the Special Investment Region (SIR), will establish 12

new industrial hubs in the next 5-6 years and expects the private sector to play a leading role in

facilitating the process.Gujarat passed an act for the SIRs and set up the first such hub -- Petroleum

Chemical and Petrochemical Investment Region (PCPIR) spread across 4.53 lakh square hectare-- in

Bharuch recently.The state government now plans to set up the SIRs to act as industrial hubs for various

sectors including auto ancillaries, chemicals, healthcare, electronics and so on.

Investment worth over Rs 70,000 crore has already gone into PCPIR and the official said similar

expenditure is likely to be incurred in other SIRs as well.

From the point of view of investement , Pro Industry Policies and other factors aforesaid BHARUCH ,

GUJARAT would be an ideal location for the plant based on our preliminary research.


11 References

1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for Acrylonitrile. Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1990.

2. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans: Some Monomers, Plastics and Synthetic Elastomers, and Acrolein. Volume 19. World Health Organization, Lyon. 1979.

3. U.S. Environmental Protection Agency. Health Assessment Document for Acrylonitrile (Revised Draft). EPA/600/8-82-007. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Research Triangle Park, NC. 1982.

4. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on Acrylonitrile, National Center for Environmental Assessment, Office of Research and Development, Washington, D.C. 1999.

5. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

6. U.S. Environmental Protection Agency. Health Effects Assessment for Acrylonitrile. EPA/600/8-88/014. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1988.

7. U.S. Environmental Protection Agency. Health Effects Assessment Summary Tables. FY 1997 Update. Solid Waste and Emergency Response, Office of Emergency and Remedial Response, Cincinnati, OH. EPA/540/R-97-036. 1997.

8. U.S. Environmental Protection Agency. Health and Environmental Effects Profile for Acrylonitrile. EPA/600/x-85/372. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1985.

9. Occupational Safety and Health Administration (OSHA). Occupational Safety and Health Standards, Toxic and Hazardous Substances. Code of Federal Regulations. 29 CFR 1910.1045. 1998.

10. American Conference of Governmental Industrial Hygienists (ACGIH). 1999 TLVs and BEIs. Threshold Limit Values for Chemical Substances and Physical Agents, Biological Exposure Indices. Cincinnati, OH. 1999.

11. National Institute for Occupational Safety and Health (NIOSH). Pocket Guide to Chemical Hazards. U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention. Cincinnati, OH. 1997.

12. American Industrial Hygiene Association (AIHA). The AIHA1998 Emergency Response Planning Guidelines and Workplace Environmental Exposure Level Guides Handbook. 1998.


12 Appendix

Pinch Analysis:

Pinch analysis is a procedure that evolved during the energy crisis of 1970, from a necessity to increase the energy savings, especially when using heat exchanger networks which resulted in optimization of heat integration. Significance of Pinch:

1. No heat is transferred across the pinch at minimum utilities. 2. Two heat exchanger networks are designed on either side of the pinch. 3. Energy is added on one side of the pinch and removed on the other side. 4. At the pinch all the hot streams are hotter than cold streams by min .

Methodology for pinch Analysis

a) Development of Composite Curves: The entire process is represented on a temperature enthalpy diagram by composite curves which represent the cumulative heat sources and sinks within the process. These composite curves are arrived at from stream data derived from a process heat and material balance. These allow prediction of hot and cold targets ahead of design.

b) Grid Diagram Development: This is a diagram which helps in developing heat recovery networking. The hot streams run from left to right while cold streams run counter-current at the bottom.

c) Pinch Identification: A grand composite curve is drawn which is composed of the composite curves for all the streams and the equipment are "appropriately placed". Appropriate placement can be done for equipment that can be represented in terms of heat sources and sinks. This implies that this can be used for heat pumps, distillation columns, evaporators, heat engines, etc. From this grand composite curve, the pinch temperature can be determined.

Stream T1(C) T2(C) mCp Q

C1 25 210 0.0384 7.1

C2 111.7 117.8 4.3 26.3

C3 82.7 82.8 25.4 2.54

C4 111.3 111.4 130 13

C5 128.3 128.4 21 2.1

C6 81.9 82 30.2 3.02

H1 420 120 0.039 11.8

H2 104.5 70 0.635 22.1

H3 38.9 38.8 26.9 2.69

H4 87.1 87 53 5.3

H5 56.5 56.4 17 1.7

H6 70.6 70.5 27.4 2.74

Temperature Interval Method

Adjusted Temperatures

Streams T1 T2 Symbol C1 25 25 T23

210 210 T1

C2 111.7 111.7 T5

117.8 117.8 T4

C3 82.7 82.7 T11

82.8 82.8 T10

C4 111.3 111.3 T7

111.4 111.4 T6

C5 128.3 128.3 T3

128.4 128.4 T2

C6 81.9 81.9 T13


82 82 T12

H1 420 410 T0

120 110 T8

H2 104.8 94.8 T9

70 60 T18

H3 38.9 28.9 T21

38.8 28.8 T22

H4 87.1 77.1 T14

87 77 T15

H5 56.5 46.5 T19

56.4 46.4 T20

H6 70.6 60.6 T16

70.5 60.5 T17

Interval Ti-1-Ti Ch-CC H 1 410-210 0.039 7.8

2 210-128.4 0.0006 0.04896

3 128.4-128.3 -20.9994 -2.09994

4 128.3-117.8 0.0006 0.0063

5 117.8-111.7 -4.2994 -26.2263

6 111.7-111.4 0.0006 0.00018

7 111.4-111.3 -129.999 -12.9999

8 111.3-110 0.0006 0.00078

9 110-94.8 -0.0384 -0.58368

10 94.8-82.8 0.5966 7.1592

11 82.8-82.7 -24.8034 -2.48034

12 82.7-82 0.5966 0.41762

13 82-81.9 -29.6034 -2.96034

14 81.9-77.1 0.5966 2.86368

15 77.1-77 53.5966 5.35966

16 77-60.6 0.5966 9.78424

17 60.6-60.5 27.9966 2.79966

18 60.5-60 0.5966 0.2983

19 60-46.5 -0.0384 -0.5184

20 46.5-46.4 16.9616 1.69616

21 46.4-28.9 -0.0384 -0.672

22 28.9-28.8 26.8616 2.68616

23 28.8-25 -0.0384 -0.14592


7.8

0.04896

-2.09994

0.0063

-26.2263

0.00018

-12.9999

0.00078

-0.58368

7.1592

-2.48034

0.41762

-2.96034

2.86368

5.35966

9.78424

2.79966

0.2983

-0.5184

1.69616

-0.672

2.68616

-0.14592

Qsteam

QCW

To=410

To=410

T2=128.

4

To=410 T3=128.3

To=410

T4=117.8

To=410

T5=111.7

To=410

T6=111.4

To=410

T7=111.3

To=410

T8=110

To=410

T9=94.8

To=410

T10=82.8

To=410

T11=82.7

T12=82

T13=81.9

To=410

T14=77.1

To=410

T15=77

T16=60.6

T17=60.5

To=410

T18=60

To=410

T19=46.5

To=410

T20=46.4

To=410

T21=28.9

To=410

T22=28.8

To=410

T23=25

To=410

T1=210

To=410

Pinch = 94.8 C (Cold) 104.8 C (Hot)

Qsteam = 41.85

QCW = 26.2877

7.8 41.8537

7.84896 41.90266

5.74902 39.80272

5.75532 39.80902

-20.471 13.58268

-20.4708 13.58286

-33.4708 0.58292

-33.47 0.5837

-34.0537 0

-26.8945 7.15922

-29.3748 4.67888

-28.9572 5.0965

-31.9175 2.13616

-29.0539 4.99984

-23.6942 10.3595

-13.91 20.14374

-11.1103 22.9434

-10.812 23.2417

-11.3304 22.7233

-9.63424 24.41946

-10.3062 23.74746

-7.62008 26.43362

-7.766 26.2877


Evaluation of Rate Equations:


We know that ki,t1 = ki,t0

R = 1.987 ca1/mole K

to =470C = 743K Using data from table 4.2,

k1 = 0.40556 . = 0.40556 . =1.57498E+05 Similarly,

k2 = 0.00973 . =3.778E+03

k3 = 0.00973 . = 1.99

k4 = 6.81341 . = 780.82

k5 = 0.073 . = 8.3658

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