final review polystyrene
TRANSCRIPT
1. INTRODUCTION
Styrene, C6H5CH = CH2, is an unsaturated aromatic monomer, which
polymerizes to give polystyrene. Though, it was discovered way backin 1786, its
commercial production and applications were developed in the nineteen thirties. Post world
war period witnessed a boom instyrene demand due to its application in the manufacture of
synthetic rubber. This led to a dramatic increase in styrene capacity. Since then demand
and capacity have grown continuously.Polystyrene is manufactured by the addition
polymerization of styrene monomer unit. Dow Chemical is the world's largest producer
with a total capacity of 1.8 million metric tonne in the USA, Canada, and Europe.
Polystyrene is a versatile thermoplastic available in a wide range of
formulations, from crystal and impact grades to highly specializedresins for foam
moulding and extrusion, and resins that offer ignition -retardant properties.The wide range
in physical properties and relative ease of processing, makes polystyrene an extremely
attractivematerial, capable of competing favorably with more expensive resins in a number
of demanding applications.
Polystyrene: Indian Industry ScenarioPolystyrene is a first generation plastic. Its major advantages of cost, low density
and easy mouldability over the conventional materials have made it quite a success.
Consumption increased from 19,700 MT in 1984-85 to about 42,600 MT in 1990-91
registering a Cumulative Average Rate of Growth (CARG) of about 19%.
There are only two manufacturers of polystyrene in India. They are:
1. Polychem Ltd, Bombay
2. Hindustan Polymers (now, LG Polymers Pvt. Ltd), Visakhapatnam
(A unit of McDowell & Co. Ltd)
These two companies together, have catered to approximately 60% of the country's
needs of polystyrene in the Seventh Plan. Imports of PS have increased over six fold in the
Seventh Plan, from a mere 3700 T in 1984-85 to about 23,000 T in 1989-90 and 19,000 in
1990-91. (1990-91 registered low consumption because of the Gulf War). The major
sectors in India which consume general purpose PS & HIPS are the refrigerator sector,
consumer electronic goods (including audio and video cassettes), packaging, the
1
automotive sector and household articles and miscellaneous uses which includes :
novelties, stationery items, toys, ball pens, beads, toothbrushes, building materials and
sanitary wares, structural foam, crystal ware, wall clocks and the defence sector. EPS
production in the country in 1990-91 was close to 3500 T with LG polymers producing
1300 T and the balance being produced by BASF Ltd.
Demand Projections:The table below summarizes the demand projections for PS in the various sectors upto the
year 2000 A.D.
Table 1: Projected Demand for Polystyrene upto 1999-2000
Sector
(year)
Refrigerator
s
Consumer
electronic
Cassette
s
Packaging Others Total
(tonne)
1990-91 6000 9600 14100 4600 8000 42300
1994-95 9500 15100 29200 9500 16600 79900
1999-
2000
14000 22200 47100 19200 33400 135900
Polystyrene Supply Scenario:The table below gives the expected indigenous supply of PS upto 2000 A.D.
Table 2: Polystyrene Indigenous Supply Scenario
Year Polychem McDowe
ll
Suprem
e
Reliance Total
(tonne)
1994-95 14,400 19,800 24,000 _ 58,000
1995-96 24,000 24,000 30,000 _ 78,000
1996-97 30,000 30,000 36,000 24,000 120,000
1997-98 36,000 36,000 36,000 30,000 138,000
1998-99 36,000 36,000 36,000 36,000 144,000
1999-2000 36,000 36,000 36,000 36,000 144,000
2
Demand Supply Gap:The demand supply gap up to the year 2000 A.D. has been worked out as follows:
Table 3: Polystyrene: Estimated Demand - Supply Gap
Year Demand Indigenous
supply
Demand – supply
gap/excess()
1991-92 42,300 34,200 8,100
1994-95 79,900 58,200 21,700
1999-2000 135,900 144,000 8,100
Technology Selection by Indian Companies:The table below summarizes the technology selection by the Indian manufacturers.
Table 4: Technology Selection by Indian Companies
S.no Company’s name Collaborator Type Remarks
1. Polychem Ltd
Polychem Ltd
DOW chemical,
USA
Huntsman
chemical corpn.
USA
Technical
and
finance
Collaboration
expired
Collaboration for
their new PS
capacity of 40000
TPA
2. LG polymers
LG polymers
BX-plastic, UK
Atochem,
france
Technical
Technical
Collaboration
was for the
existing plant
Expansion of PS
capacity to 40000
TPA
3. Reliance industries Hunstan
chemical corpn.
Technical New capacity of
40,000 TPA
4. Supreme
petrochemicals
Hunstan
chemical corpn
Technical New capacity of
40,000 TPA
3
Polystyrene: International ScenarioGlobal consumption of Polystyrene has been increasing at a steady rate of
approximately 5% p.a. Consumption, which stood at 6.6 million tons in 1985 has increased
to about 8.5 million tons in 1990. However, there was only a marginal rise in consumption
between 1990 and 1991, with the developed countries showing a slight decrease.
Both General Purpose Polystyrene and High Impact Polystyrene have had an equal
share in the total consumption of Polystyrene. Manufacturing capacity has increased by 2
million tons from 8.5 million in 1985 to about 10.5 million in 1990. The below figure
shows the world consumption of polystyrene in 2010.
Taiwan Canada
Rep. of korea mexico Oceania
South America
Japan china
others
Africa Western Europe
Central Europe
United states
Figure 1: World Consumption of Polystyrene in 2010
4
2. PROPERTIES AND USES OF POLYSTYRENE
2.1. Physical Properties:
Table 5: Physical Properties of Polystyrene
Appearance White crystalline solid
Density 0.96-1.04
Molecular formula (C8H8)n
Melting point ~ 240 0C
Thermal conductivity 0.033 W/Mk
Refractive index 1.6
2.2.Processing Properties:Flow properties may be the most important properties of polystyrene processes.
There are two widely accepted industry methods for the measurement of processing
properties. These include the melt flow index and the solution viscosity.
The melt flow index is measured by ASTM method as a measure of the melt
viscosity at 200 0C and a 5kg load. The melt flow index of polystyrene is generally
controlled by adjustment of the molecular weight of the material and by the addition of
such lubricants as mineral oil. Polystyrenes are commercially produced with melt flow
ranges of less than 1 to greater than 50, although the most widely available gradesgenerally
have melt flows between 2.0 and 20g per 10min.
Solution viscosity is another method for measuring the molecular structure of the
polystyrene. Solution viscosity can be measured as an 8% solution in toluene and increases
with increasing molecular weight.Polystyrene is a non-Newtonian fluid with viscoelastic
properties. The viscosity of polystyrene melts or solutions is defined as the ratio of shear
stress to shear rate. Generally, as the molecular weight of the polymer is increased or
mineral oil is decreased, melt viscosity increases.
2.3. Mechanical Properties:Crystal polystyrenes have very low impact strengths of less than 0.5ft-lb.
Commercially available impact polystyrene grades can be obtained with values of 1.0 - 4.0
ft-lb. Generally, polystyrenes are not produced with greater than 15% total rubber because
5
of polymerization processing constraints. Nevertheless,impact properties can be increased
substantially without additional rubber by the proper control of rubber particle size,
percentage of grafting, cross-linking, and percentage of gel.
Tensile and flexural properties are also important representation of the strength of
polystyrenes. Increasing the rubber modification of polystyrene generally leads to lower
tensile strength, crystal grades being stiff and brittle. Tensile strength is also decreased by
the addition of lubricants, such as mineral oil. Flexural strengths for polystyrenes can be
obtained from 5000 to 18000psi and are also decreased by the addition of rubber and other
additives to the polystyrene. Elongations can be obtained from 1% for crystal polystyrene
to 100% for some impact polystyrene grades.
2.4. Thermal Properties:Annealed heat distortion is one popular method for measuring the resistance to
deformation under heat for polystyrenes. The heat distortion temperature is decreased by
the addition of rubber, mineral oil, or other additives to polystyrene. The glass transition
temperature for unmodified polystyrene is 373 K, and the glass transition temperatures for
poly butadienes are 161-205 K, subject to the cis, trans and vinyl content.
2.5. Chemical Properties:Solvent crazing of polystyrene is a commercially important phenomenon. High
impact polystyrenes are susceptible to solvent crazing at the interface between the rubber
particles and the polystyrene phase. The resistance of polystyrene to this crazing is referred
to as environmental stress crack resistance (ESCR).
For food-packaging applications, such as butter tubs and delicate containers,
polystyrene with high ESCR properties are desirable. Increasing the percentage of gel,
percentage grafting, and rubber particle size can increase stress crack resistance.
Residual levels of low molecular weight materials are also important topolystyrene
performance. Some of the chemical impurities in the polystyrene are styrene monomer and
ethyl benzene solvent. Residual levels of styrene below 200 ppm and ethyl benzene levels
below 30 ppm are obtainable for very specialized applications.
6
2.6. USES:1. Extruded foam sheet of polystyrene can be thermoformed into such parts as egg cartons
or carryout food containers. These are also used in crafts and model building, in particular
architectural models.
2. Crystal polystyrene materials have excellent thermal and electrical properties which
make them useful as low cost insulating materials,envelope windows, cap layers for glossy
sheet, orthermoforming into food packaging applications.
3. Another type of polystyrene foam is that produced from expandable polystyrenebeads.
These beads can be molded to produce hot drink cups, ice chests, disposable trays, plates,
bowls, calm shells(food packaging) and cushioned or foampackaging.
4. Also, the expandable beads can be molded in very large blocks that can then be cut into
sheets for thermal insulation. These are supplied as compound with blowing agent and
other additives.
5. High Impact Polystyrene is often specified for low strength structural applications when
impact resistance, machineability and low cost are required.
6.Natural HIPS is complaint for use in food processing applications. Stero regular poly
butadiene elastomers are used for impact modifications. It can be processed easily by all
conventional thermoplastic fabricating techniques which include film, sheet and profile
extrusion, thermoforming, injection moulding, injection blow moulding and structural
blow moulding.
7. Optical property of polystyrene is used in manufacture of unbreakable glasses for
gauges, windows and lenses, as well as in countless specialties and novelties and also for
edge lighting for the edge lighting of indicators and dials.
8. Solid or liquid pigments and dies color high impact and crystal polystyrenes. This can be
accomplished in both extrusion and injection moulding processes. These colorants are
added and mixed during the melting stage of both the processes. Also, polystyrene parts
are amenable to high quality printing. Labels can beprinted directly on the polystyrene part
to produce attractive containers.
9.Polystyrenes are also used in furniture, packaging, appliances, automobiles,construction,
radios, televisions, toys, house ware items, and luggage.
7
3. LITERATURE SURVEY OF DIFFERENT PROCESSES
The different methods available for styrene polymerization are:
3.1. Bulk polymerization.
3.2. Solution polymerization.
3.3. Emulsion polymerization.
3.4. Suspension polymerization.
3.1. Bulk Polymerization:Solution (bulk) polymerization is commonly referred to as mass polymerization in
the industry. The vast majority of all polystyrene produced today is produced via this
technology. The common solvents used in this process are the styrene monomer itself and
ethyl benzene. The two types of mass polymerization are batch and continuous, of which
continuous mass is by far the most popular.
Bulk addition polymerization is a homogeneous process which uses an organic
initiator. The higher the temperature, the lower the molecular weight of the polymer
produced. At higher temperatures, the initiator decomposes to form radicals at a faster rate,
then for a given amount of monomer with more radicals present more polymer chains will
be started (initiated), and the resulting polymers will have a lower molecular weight.
We can have continuous polymerization at very low temperatures if we use light toconvert
the initiator molecules to radicals (which will start the polymerization).
8
Figure 2: Polystyrene Manufacture by Bulk Polymerization
3.2. Solution Polymerization
Solution polymerization is a method of industrial polymerization. In this procedure,
monomer is dissolved in a non-reactive solvent that contains a catalyst. The reaction results
in a polymer which is also soluble in the chosen solvent(either water or an organic
solvent). E.g: polystyrene in toluenemonomer is soluble and the polymer is insoluble in the
diluent, acrylonitrile in chloroform. Heat released by the reaction is absorbed by the
solvent, and so the reaction rate is reduced. Once the maximum or desired conversion is
reached, excess solvent has to be removed in order to obtain the pure polymer.
3.3.Emulsion Polymerization:Emulsion polymerization is generally used for polymerization of styrene with other
monomers or polymers. It is not a generally commercially accepted method of producing
crystal polystyrene or high impactpolystyrene(HIPS). Emulsion polymerization is carried
out similarly to suspension polymerization except that the monomer droplets are
microscopic in size. Emulsion polymerization is also a heterogeneous polymerization with
water as the continuous phase. In this system, however, monomer droplets are dispersed in
water using surfactants or emulsifying agents, and a stable emulsion is produced.
Emulsion systems are characterized by substantially smaller particle sizes than
suspension polymerizations, with particles in the range of 0.05 to 0.2 μm. Additionally, a
water soluble initiator rather than monomer-soluble initiator is employed, and very
different kinetic features are observed. The end product of an emulsion polymerization is a
stablelatex, an emulsion of polymer in water.
3.4. Suspension Polymerization:This is also called pearl polymerization. It has proved highly efficient for large
scale production of polymers of high average molecular weight. By variation of the
polymerization condition it is possible to produce a range of polymers with different
properties and processing characteristics so that a number of grades are offered by the
manufacturers to meet the differing requirements of the conversion process and the final
product.
There are many different ways of making polystyrene using suspension process.
Most producers use a batch process, although there is no technical reasons why a
9
continuous process could not work. In the suspension process a number of small styrene
drops 0.15-0.50mm in diameter are suspended in water. The reaction occurs within these
drops. To aid in the formation of proper size drops a suspending agent is used, and to keep
them at that size a stabilizing agent is added. A catalyst is used to control the reaction rate.
Table 6: Polymerization Systems Comparison
Type of polymerization Advantages Disadvantages
Bulk Low impurity levels
No solvent removal
Thermal control difficult
Side reactions, “hot spots”
Thermal degradation
Explosion risk
Solution Thermal control
Easy mixing due to lower
viscosity
Improved initiation
efficiency
Difficult to remove solvent and
other ingredients
Cost of solvent recovery
Solvent environmental impact
Potential chain transfer to
solvent
Suspension Thermal control
Low viscosity throughout
reaction
High purity product
Simple polymer isolation
Agitation control
Particle size difficult to control
Possible contamination by
dispersing agents
polymer may require washing
and drying.
Emulsion Thermal control
Low viscosity throughout
reaction.
Latex may be directly
usable.
High MW at high rates
with relatively narrower
MWD.
Small particle size
product.
Difficult to remove surfactants,
emulsifiers, coagulants.
Residuals may degrade polymer
properties.
Polymer may require washing
and drying.
10
4. SELECTION OF THE PROCESS
Among the above 4 processes suspension polymerization offers considerable
advantages over the single phase techniques in so far that heat removal control is no longer
a problem and a high purity product is obtained, but there are disadvantages such as the
need to use a dispersing agent. Bulk polymerization process is generally used to produce
large amounts of expandable polystyrene and highly thermal control process. In solution
and emulsion processes solvent should be recovered and residues are formed which is not a
problem in suspension polymerization. Finally, based on the above considerations
suspension polymerization for the manufacture of polystyrene is selected.
It is used only in free radical type processes. The monomer is mechanically
dispersed in a media, usually water. There are cases where an organic media is used in
which neither the polymer nor the monomer are soluble in the organic media. The initiator
used can be water soluble or organic soluble (benzoyl peroxide, AIBN, or (NH4)2(SxO4)y).
Usually the initiator is organic soluble. There are two separate phases throughout the whole
process. The droplets must be kept far apart. This requires agitation: consistent, efficient,
andcontrolled. A suspending agent can be used. Polyvinyl alcoholdissolved in the
aqueousphase is a typical suspending agent. The rate of suspension polymerization is
similar to the rate of bulk polymerization, but the heat transfer is much better. Examples
include the polymerization of MMA, and vinyl chloride. The medium to monomer ratio is
10:1. Particle size is affect by the following four factors:
• Stirring rate
• Ratio of reactants
• Suspension agent
• Temperature
If the particle size gets to large, the particle will absorb too much heat. Particle size
may be 0.01 to 0.5 cm, or as low as 1 micron. A suspension agentis a material that gives a
surface activation that keeps droplets from become larger (droplets coming together to
form larger droplets is called coalescence). Suspension polymerization is similar to bulk
polymerization, and it could be considered "bulk polymerization within a droplet."
11
5. PROCESS DETAILS
Suspension polymerization is a batch system popular for special grades of
polystyrene. It can be used to produce either crystal or high impact grades. In impact
production, the styrene and rubber solution is bulk polymerized beyond phase inversion
and is then suspended in water to create oil in water suspension utilizing soaps and
suspending agents. The suspended droplets are then polymerized to completion, utilizing
initiator and a staged heating profile. The water phase is used as a heat sink and heat
transfer medium to a temperature controlled jacket. For the production of crystal
polystyrene the styrene monomer itself is suspended and polymerized via the same
mechanism.
Reaction conditions:The reaction mixture consists of two phases, a liquid matrix and monomer droplets.
The monomer and initiator are insoluble in the liquid phase, so they form drops within the
liquid matrix. A suspension agent is usually added to stabilize the monomer droplets and
hinder monomer drops from coming together. The reaction mixture usually has a volume
ratio of monomer to liquid phase of 0.1 to 0.5. The liquid phase acts as a heat transfer
agent, enabling high rates of polymerization with little change in the temperature of the
polymerizing solution.
The reactions are usually done in a stirred tank reactor that continuously mixes the
solution using turbulent pressure or viscous shear forces. The stirring action helps to keep
the monomer droplets separated and creates a more uniform suspension, which leads to a
more narrow size distribution of the final polymer beads. The polymerization is usually
carried to completion.The kinetics of the polymerization within an individual bead are
similar to those of typical radical polymerization.
Particle properties:Suspension polymerization is divided into two main types, depending on the
morphology of the particles that result. In bead polymerization, the polymer is soluble in
its monomer and the result is a smooth, translucent bead. In powder polymerization, the
polymer is not soluble in its monomer and the resultant bead will be porous and irregular.
12
The morphology of the polymer can be changed by adding a monomer diluent, an
inert liquid that is insoluble with the liquid matrix. The diluentschanges the solubility of
the polymer in the monomer and gives a measure of control over the porosity of the
resulting polymer.
The polymer beads that result can range in size from 100 nm to 5 mm. The size is
controlled by the stirring speed, the volume fraction of monomer, the concentration and
identity of the stabilizers used, and the viscosities of the different components. The
following equation derived empirically summarizes some of these interactions:
d = k (Dv*R*vm*Є) /(Ds*N*vt*Cs)
where, d is the average particle size, k includes parameters related to the reaction
vessel design, Dv is the reaction vessel diameter, Ds is the diameter of the stirrer, R is the
volume ratio of the monomer to the liquid matrix, N is the stirring speed, νm and νl are the
viscosity of the monomer phase and liquid matrix respectively, ε is the interfacial tension
of the two phases, and Cs is the concentration of stabilizer. The most common way to
control the particle size is to change the stirring speed.
The requirements of polymerization are:
a. Initiator
b. Suspending agent
c. Stabilizing agent
d. Catalyst
e. Polymerization temperature
a. Initiators: The initiators generally used are benzoyl peroxide and t-butyl hydro
peroxide.
b. Suspending agent: To aid in the formation of the proper size drops a suspending agent
is added. Some typical suspending agents are methylcellulose, ethyl cellulose and
polyacrylic acids. Their concentration in the suspension is between 0.01-0.5% of monomer
charged.
c. Stabilizing agent: To keep the drops at proper size, a stabilizing agent is added. The
stabilizing agents are often insoluble inorganic such as calcium carbonate, calcium
phosphates or bentonite clay. They are present in small amount than the suspending agents.
13
d. Catalyst: A catalyst is used to control the reaction rate. The catalysts are usually
peroxides. The most common ones are benzoyl, diacetyl, lauroyl, caproyl and tert-butyl.
Their concentration varies from 0.1-0.5% of the monomer charged.The ratio of monomer
to dispersing medium is between 10 and 40%.
e. Polymerization temperature:Polymerization of styrene occurs at temperature range of
90-950C.
Process description: The main manufacturing route to styrene is the direct catalytic dehydrogenation of
ethyl benzene:
CH3 CH2 catalyst CH2 CH + H2
Ethyl benzene styrene
The reaction shown above has a heat of reaction of -121 kJ/mol (endothermic).
The suspension method is carried out in large reactors equipped with agitators, the
styrene monomer being maintained in the aqueous phase as droplets with a diameter
varying between 0.4-1mm by use of a dispersing agent such as partially hydrolyzed
polyvinyl acetate, inorganic phosphates or magnesium silicates.
To reduce the cycle time of the reactors, the entering water and styrene will be
preheated. The temperatures of the input streams will be sent so as to obtain the desired
reaction temperature. The water entering the reactor will be heated to 950C. The bulk of the
styrene is to be heated to 850C before being charged. This is done in a vertical doublepipe
heat exchanger, which is directly above the reactor. To prevent the polymerizationfrom
occurring in the heat exchanger or piping system, there are to be no obstructions between
this heat exchanger and the reactor.
Nearly 65% of all styrene is used to produce polystyrene. The overall reaction
describing the styrene polymerization is:
14
initiator
X CH2 CH CH2 CH
X
Styrene Polystyrene
This reaction is carried out in an inert organic solvent environment, which provides
the reaction medium for this cationic polymerization reaction. The catalyst, rubber
stabilizer, and suspending agent are premixed in styrene and discharged by gravity into the
reactor. This mixture will not be preheated, since it might polymerize. Typical water to
monomer ratios is 1:1 to 3:1. A combination of two or moreinitiators is used with a
programmed reaction temperature to reduce the polymerization time to a minimum for a
given amount of residual styrene.
Purification Steps and Extrusion:If the water can be removed using physical separation processes, then the styrene
and the other impurities dissolved in it will also be discharged. A centrifuge with a
washing step will be used to do this. The material leaving the centrifuge has 1-5%
water.The final purification step is drying.
The polystyrene leaving this unit must meet the specifications set (0.03% water).
Then it is passed through a devolatization extruder to remove the volatile residues and to
convert the polymer into pellets.It was assumed that 3% of polystyrene would be removed
from the process in airvying, drying, centrifuging, transferring, or as bad as bad product.
At least 95% of that which is lost in processing must be intercepted before it leaves the
plant. Most of it can be removed and sold as off-grade material. This waste is split among
the various streams leaving the processing area.
15
Figure 3: Flow sheet of suspension polymerization
16
Reactor
6. MATERIAL BALANCE
Basis:Amount of polystyrene produced per day = 250 TPD
= 250*103/24
= 10416.67Kg/hr
Assumptions:
1. It will be assumed that 99.8% of the styrene is reacted and this can be accomplished by
using an average of the temperatures and cycle time given.
2. Temperature of reaction = 90-95C
3. Cycle time of reactor=5.5hrs.
Reactor:Dodecyl benzene benzoyl peroxide +
sulphonate miscellaneous
styrene(1.032 kg/kg PS)
polystyrene
water + tricalcium
phosphate styrene
water miscellaneous
Figure 4: Material Balance over reactor
Input to the reactor:Styrene = 1.032 kg styrene/kg polystyrene
= 1.032*10416.67
= 10750kg
Water = 2.0 kg water/kg polystyrene
= 2.0*10416.67
= 20833.34kg.
Tricalcium phosphate = 0.005 kg tricalcium phosphate/kg polystyrene
= 0.005*10416.67
= 52.083kg.
Dodecyl benzene sulphonate = 0.00006 kg dodecyl benzene sulphonate/kg PS
17
= 0.00006*10416.67
= 0.625kg.
Benzoyl peroxide = 0.0025 kg benzoyl peroxide/kg polystyrene
= 0.0025*10416.67
= 26.042kg.
Miscellaneous = 0.004
= 0.004*10416.67
= 41.67kg.
Total input to reactor = 31703.75kg.
Output from the rector:Polystyrene =1.030 kg polystyrene / kg of polystyrene
= 1.030*10416.67
= 10729.17kg.
Styrene = 0.002 kg styrene/kg polystyrene
= 0.002*10416.67
= 20.83kg
Water = 2.0 kg water/kg polystyrene
= 2.0*10416.67
= 20833.34kg.
Miscellaneous = 0.01156 kg /kg polystyrene
= 0.01156*10416.67
= 120.41 kg.
Total output from reactor = 31703.75 kg.
Table 7: Reactor Material Balance
Components input(kg/kg PS) output(kg/ks PS)
Styrene 1.032 0.002
Polystyrene - 1.030
Water 2 2
tri calcium phosphate 0.005 -
dodecyl benzene sulphonate 0.00006 -
benzoyl peroxide 0.0025 -
Miscellaneous 0.004 -
Total 3.04356 3.04356
18
Wash tank
Wash tank: output from the reactor
3.04356 kg/kg of PS
2.0 kg of water/kg of PS
0.004 kg of HCl/kg of PS
1.030 polystyrene (unit ratio)
0.002 styrene (unit ratio)
4.0 water
0.0156 miscellaneous
Figure 5: Material Balance over Wash tank
Input to wash tank:Output from reactor = 3.04356*10416.67
= 31703.76kg.
Water =2.0 kg water/ kg polystyrene
= 2.0*10416.67
=20833.34kg.
Hydrochloric acid = 0.004 kg HCl/ kg polystyrene
= 0.004*10416.67
= 41.67 kg.
Total input to wash tank =31703.75 + 20833.34 + 41.67
= 52578.75kg.
Output from wash tank:Polystyrene = 1.030 kg polystyrene/ kg polystyrene desired
=1.030*10416.67
= 10729.17kg
Styrene = 0.002 kg styrene/kg polystyrene
= 0.002*10416.67
= 20.83kg.
Water = 4.0 kg water/ kg polystyrene
19
Centrifuge
= 4.0*10416.67
= 41666.68kg.
Miscellaneous = 0.01556 kg/kg of polystyrene
= 0.0156*10416.67
= 162.08kg
Total output from wash tank = 10729.17+ 20.83+41666.68+162.08
= 52578.75 kg
Table 8: Wash Tank Material Balance
Components input(kg/kg PS) output(kg/kg PS)
Polystyrene 1.030 1.030
Styrene 0.002 0.002
Water 4 4
Miscellaneous 0.01156 0.01556
HCl 0.004 -
Total 5.04756 5.04756
Centrifuge:Output from wash tank
0.01 kg of PS/kg of PS
0.002 kg of styrene/kg of PS
1.0 kg of water/kg of PS 4.95 kg of H2O/kg of PS
0.01546 misc./kg of PS
(desired)
1.02 kg of PS / kg of PS
0.05 kg of water/ kg of PS
0.0001 kg of misc./kg of PS
Figure 6: Material Balance over Centrifuge
Input to the centrifuge:Output from wash tank = 52578.75 kg
Water =1.0 kg water/kg polystyrene
=10416.67 kg water.
20
Output from centrifuge:The output from centrifuge comprises of two layers. One is the desired and theother is bad
product.
Desired product composition:
Polystyrene = 1.02 kg polystyrene/kg of desired polystyrene
= 1.02*10416.67
= 10625kg
Water = 0.05 kg water/ kg polystyrene
= 0.05*10416.67
= 520.83kg
Miscellaneous = 0.0001 kg/ kg polystyrene
= 0.0001*10416.67
=1.041667 kg
Undesired product composition:
Polystyrene = 0.01kg polystyrene/kg polystyrene
= 0.01*10416.67
=104.1667 kg
Styrene = 0.002 kg styrene /kg polystyrene
= 0.002*10416.67
=20.83kg
Water = 4.95 kg water / kg polystyrene
= 4.95*10416.67 = 51562.51kg
Miscellaneous = 0.01546 kg/ kg polystyrene
=0.0155*10416.67
=161.042 kg.
Table 9: Centrifuge Material Balance
components input(kg/kg
PS)
Desiredoutput(kg/kgPS) undesired output(kg/kg
PS)
polystyrene 1.030 1.02 0.01
styrene 0.002 - 0.002
water 5 0.05 4.95
miscellaneous 0.01556 0.0001 0.01546
total 6.04756 1.0701 4.97746
21
Dryer
Dryer:Air (1.3486 kg/ kg PS) + outputfrom centrifuge
0.015 kg of PS/kg of PS 0.005 kg of PS/ kg of PS
(bad product) 1.39851 kg of moist air/ kg of PS
(desired product)
1.0 kg of PS/kg of PS
0.0001 kg of water/ kg of PS
Figure 7: Material Balance over Dryer
Input to the dryer:Output from the centrifuge = 10625 + 520.83 + 1.041667
= 11146.87kg
Air = 1.3486 kg / kg PS
= 1.3486*10416.67
= 14048 kg
Output from the dryer:Output from dryer comprises of three parts
1. Desired polystyrene with composition:
Polystyrene =1.0 kg/kg polystyrene
= 10416.67 kg of polystyrene
Water = 0.0001 kg/kg polystyrene
= 0.0001*10416.67
= 1.041667kg
2. Undesired Product with Polystyrene = 0.005 kg/kg polystyrene
= 0.005*10416.67
= 52.083kg
Moist air = 1.39851 kg/kg polystyrene
= 1.39851*10416.67
= 14567.82 kg
22
Extruder
3. Bad product obtained has a composition of polystyrene
= 0.015 kg/kg polystyrene
= 0.015*10416.67
= 156.25kg
Table 10: Dryer Material Balance
components input(kg/kg PS) desired output(kg/kg PS) undesired output(kg/kg PS)
polystyrene 1.02 1.0 0.02
water 0.05 0.0001 -
miscellaneous 0.0001 -
Air 1.348 -
moist air - - 1.398
Total 2.4181 1.0001 1.418
Extruder:
output from dryer
1.0 kg of Polystyrene
0.0001 kg water/ kg PS
Figure 8: Material Balance over Extruder
Input to extruder =output from dryer = 10416.67 + 1.0417667
= 10417.712 kg
Output from extruder = 10417.712 kg
23
7. ENERGY BALANCE
Assumptions:1. Assume 2kg of styrene are to be used to carry each kg of additive into the reactor.
2. Steam at 150 psi is used as heating medium.
3. The reaction is taking place in a batch reactor.
4. Assume heat losses of about 10%.
5. Cycle time of the reactor = 5.5 hrs.
6. Assume 9 reactors were used.
Styrene heat exchanger:Temperatures Inlet Outlet
Styrene 30oC 93oC
The additive feed tank must be large enough to handle all additive plus a carrier solution of
styrene. The amount of dodecyl benzene sulphonate, tricalcium phosphate and benzoyl
peroxide used per batch are:
= (0.005 + 0.00006 + 2 * 0.0025) * 10416.67 * 5.5 / 9
=64.039 kg.
For 2 kg of styrene used = 64.039 * 2 (assumption 1)
= 128.078kg.
When GPPS is made, all but 128.078kg of styrene are heated to 93C. For theother
products less is used. Qs = msCpsTs
where, Qs is the rate of heat transfer
ms is the flow rate of styrene through exchanger
= ((1.032 kg styrene/kg PS)*10416.67 kg PS *5.5hrs/9 – 128.078 kg styrene) / (5min/60)
= 77296.4 kg/hr.
Cps= heat capacity of styrene = 0.43 Btu/ lboF = 1.799 kJ/ kgoC
Ts= temperature difference of styrene entering at 30oC and leaving exchanger at 93oC
= 93 – 30 = 63oC
Qs = 77296.4*1.799*63
= 8760.54*103kJ/hr.
At 150 psi, Ts=182oC. (assumption)
= latent heat of vaporization = 1995.98kJ/hr.
Qs =msCpsTs = m *
Therefore, mass flow rate of steam required, m = 8760.54*103/1995.98
24
= 4389.09kg/hr.
Air heat exchanger:Temperatures Inlet Outlet
air 30oC 150oC
The air is to be heated to 150C using 150psi steam.
The amount of energy required = Qa= ma. Cp. T = m
Where,
ma= flow rate of air used in dryer
= 14048 kg/hr
Cp= heat capacity of air entering and leaving the exchanger
= 1.0468 kJ/kg C
T = temperature difference of air entering at 30oC and leaving the exchanger at 150oC
= 150 – 30 = 120C.
= latent heat of vaporization = 1995.98kJ/hr.
Qa= 14048*1.0468*120
= 1.76465*106kJ/hr.
Amount of steam required, m = Qa / = (1.76465*106) / 1995.98
= 884.1kg/hr.
Reactor cooling system:From equation (2), (8) of reactor design,
Diameter, D = 2.479m
Average energy removed per hour= 77.989*103 D3kJ/hr.
= 77.989*103*(2.479)3.
= 118.813*104 kJ/hr
= 330.036kJ/s.
Inlet temperature of cooling water = 30C.
Outlet temperature of cooling water = 68C.
Specific heat of cooling water, Cp=4.187kJ/kg oC
Let mw be the amount of cooling water required to remove the heat.
Heat released in the reaction = heat gained by the cooling water
Q = mw. Cp. T.
mw *4.187*(68-30) = 330.036 kJ/s
mw = 2.0743 kg/s in each reactor.
25
Therefore amount of water required in total for 9 reactors = 2.0743*9
=18.668 kg/s.
Dryer:Temperatures Inlet Outlet
Polystyrene 30C. 80C.
Air 150C. 85C.
Specific heat of polystyrene, Capps=1.337kJ/kg oC
Heat required to raise polystyrene product entering the dryer to discharge temperature,
= m* Cpps*T
= 10625kg/hr*1.337*103*(80-30)/3600s
= 1.97300*105 W
Specific heat of water, Cpw = 4.187 kJ/kg oC
Heat required for removing water entering the dryer,
= m*Cpw*T
= 520.83kg/hr*4.187*103*(80-30)/3600s
= 0.302877*105W.
Therefore total heat required,
= 7.1028*105+ 1.09035*105W.
= 8.19315*105W.
The amount of air required is determined by the amount of energy 150C. Airmust supply
to remove the moisture from the polystyrene.
m = Qt/( Cp.T).
Where, Cp= heat capacity of air = 0.237 Btu/ lboC = 0.9923 J/kg oC.
T = difference in air temperature entering and leaving dryer, C.
Qt = heat transferred in dryer =8.20803*105W.
m = mass flow rate of air.
m = (8.19315*105) /(0.9923*(150-85))*3600
= 12702.656kg/hr.
The amount of air is adequate. Add 10% to account for possible heat losses. (assumption 4)
Therefore mass flow rate = 1.1* 12702.656
= 13972.922 kg/hr.
8. SPECIFIC EQUIPMENT DESIGN
26
Assumptions:1. Heat of the reaction = 300 BTU/lb.
2. Assume 90% of the reactor is full and height of the reactor is 2 times of its
diameter
3. Density of the mixture is 1/3 of the way between water and styrene.
4. Assume maximum reaction rate is nearly twice the average rate.
5. Assume cycle time for GPPS is 5.5 hrs and it takes 0.5 hrs for MPPS and 1.0 hrs
for HIPS longer than GPPS and time taken for charge and discharge is 1hr and
0.5hr to initiate the reaction.
6. The reaction is taking place in a batch reactor.
Process design of the reactor:The polymerization of styrene is an exothermic reaction. The amount of energy
released at any time is dependent on the volume of the reactor, and the rate of removal of
that heat is dependent on the surface area. Unless the heat is removed, the temperature will
rise and the reaction rate will increase. The result will be an uncontrolled reaction that not
only may ruin the batch but could also damage the reactor and might cause fire or
explosion to occur. Therefore there is a maximum size of the reactor for each set of
reaction condition which will be calculated. The maximum rate of heat production will be
first calculated.
The heat of polymerization = 300 Btu/ lb (assumption 1)
= 300*1.055/0.4536
= 697.79 kJ/kg.
Mass fraction of the styrene = 1.032/(1.032+2)
= 1.032/3.032
= 0.34037
The weight of styrene in the reactor = ρ*V* mass fraction of styrene (1)
Where, ρ = Density of mixture (assumption 4)
= 929.086 kg/m3
V = volume of reactor=area*length = πD2/4 *L
Where, D = diameter of reactor
L = length of reactor.
Therefore equation (1) becomes,
27
Weight of styrene in the reactor = 0.9*929.086*0.34037*π*D2 / 4*(2*D) (assumption 2)
= 447.063*D3 kg.
Therefore the energy released by polymerization
= Weight of styrene in reactor*heat of polymerization
= 447.063*D3 * 697.79
= 311.956*103*D3 kJ
All this energy must be removed as it is formed.
The cycle time for GPPS = 5.5 hrs (assumption 5)
If the time taken for charge and discharge = 1 hr
And time taken to initiate the reaction = 0.5hr
Then all the energy released must be removed in 5.5-1-0.5 = 4.0hr.
Therefore average energy produced per hour = 311.956*103*D3 / 4
= 77.989*103D3 kJ/hr. (2)
However, the reaction rate is not uniform. The maximum reaction rate must be known to
calculate the area needed for heat exchange.
The maximum heat produced per hour = 2* average energy produced/hr.(assumption 4)
= 2*77.989*103*D3 kJ/hr
= 155.978*103*D3*103 J/3600 s
= 43327.22 D3 J/s (3)
The rate of heat removed,
Q = U.A.ΔTο (4)
Where, U = overall heat transfer coefficient.
A = area of heat transfer.
ΔTο = average temperature driving force between coolant and suspension.
Since 95% of the time, the air temperature is below 30οC. It will be assumed that inlet
cooling water temperature never exceeds 30οC.
The reaction temperature = 93οC.
Assume the maximum cooling water outlet temperature rise is5οC.
Therefore outlet temperature of cooling water =35οC
Therefore the average temperature of cooling water =(30+35)/2 = 32.5οC.
ΔTο= 93-32.5 = 60.5οC.
Overall heat transfer coefficient at 60.5oC = 50Btu/hr.ft2K =283.9 W/m2K
The area of heat transfer is thearea covered by the suspension. This can be estimatedto be
the bottom surface are + 90% of the sides. ( assumption 2)
28
Area, A = 0.9πDL + πD2 /4
= 6.44D2
Substituting values of A, ΔTο and U in equation (3), we get,
Q = 283.9*6.44D2 *60.5 (5)
Comparing equation (3) and equation (5), we get,
43327.22*D3 = 283.9*6.44D2 *60.5
D = 283.9*6.44*60.5/ 43327.22
= 2.553 m.
As, L = 2D (assumption 2)
= 2*2.553
= 5.106 m.
And, V = πD2L/ 4
= π*(2.553)2*5.106/4
= 26.138 m3
= 6904.93 gal.
In ‘encyclopedia of polymer technology and science’, the following statement appears:
“In a suspension polymerization of styrene in a 5000 gal reactor, the lowest coolant
temperature required is 120°F (49° C)”.
Hence now the average coolant temperature is taken as 49°C instead of 32.5°C.
Outlet temperature of cooling water, T = 68°C.
And, average temperature = (68 + 30)/2 = 49°C.
ΔTο= 93 - 49 = 44°C.
Also ‘U’ at ΔTο=44oC is 60 BTU/ hr.ft2.°F =341.22 W/m2 K and a maximum reaction rate
of 1.8 times theaverage would be better estimates.
Taking maximum heat released per hour = 1.8 times average value.
(equation2,assumption 4)
= 1.8*77.989 *D3*106/ 3600
= 38994*D3 J/s (6)
Rate of heat removed Q =U.A.ΔTο
= 341.22*6.44*D2*44 (7)
Heat released in the reactor = heat gained by cooling water
From equations (6),(7)
38994*D3 = 60*5.687*6.44D2*44
29
D = 341.22*6.44*44/38994 = 2.479m (8)
L = 2*D =2*2.479 = 4.96m
V = πD2L/ 4
= π*(2.479)2*4.96/4
= 23.94 m3
Equation (1) becomes
Amount of styrene produced per reactor per hour
= (0.9*ρ *V*mass fraction)/cycle time
= (0.9*929.086*23.94*0.34037)/5.5 (assumption 2,5)
= 1238.83 kg/hr.
Number of GPPS reactors required for 60% conversion is:
= (10416.67kg PS*1.032 kg styrene/kg PS* % of conversion)/amount of styrene
produced per reactor = (10416.67*1.032*0.6)/1238.83
= 5.206 rectors.
All the above calculations have been done using GPPS. It will be assumed that the same
conditions apply to MPPS and HIPS except that the reaction times are different. For
economic purpose, the same size reactor will be used for each product.
For MPPS the reaction takes 0.5hrs longer = 5.5+0.5 =6hrs.
For HIPS the reaction takes 1.0 hrs longer = 5.5+1 = 6.5 hrs.
Number of MPPS reactors required for 20% conversion = (5.206*0.2* 6)/(0.6*5.5)
= 1.893 reactors.
Number of HIPS reactors required for 20% conversion = (5.206*0.2*6.5)/(0.6*5.5)
= 2.05 reactors.
Therefore together we need 4 reactors for MPPS, HIPS and 5 reactors for GPPS making a
total of 9reactors needed. A 10th reactor will be installed as a spare. This will allow full
production to continue if cleaning out the reactors becomes more of a problem
thanexpected.
Mechanical design:Data from literature:
Design pressure for the reactor = 220psi = 16.47 kg/cm2.
30
Design pressure for jacket = 75psi = 6.27 kg/cm2.
Permissible stress of reactor = 950kg/cm2.
Shell internal diameter = 2.486m.
Agitator horse power for 5000gal = 50hp
Diameter of agitator = 1035mm.
Speed = 200rpm.
Agitator blades (flat) = 6
Width of blade =75mm.
Thickness of blades =8mm.
Shaft material – commercial cold rolled steel.
Permissible shear stress in shaft = 550kg/cm2.
Elastic limit in tension = 2460kg/cm2.
Modulus of elasticity =19.5*105kg/cm2.
Permissible stresses for key (carbon steel)
Shear = 650kg/cm2.
Crushing = 1300kg/cm2.
Stuffing box (carbon steel)
Permissible stress = 950kg/cm2.
Studs and bolts (hot rolled carbon steel)
Permissible stress = 587kg/cm2.
Joint efficiency = 0.85.
Poisons ratio = 0.3.
9. MATERIALS OF CONSTRUCTION
31
The choice of construction material for a polymerization reactor will depend on a
variety of factors, most importantly the specific polymerization to be performed. Stainless
steel construction offers a lot more options and has many things to consider. The particular
alloy of stainless steel to be used involves a balance of economics, corrosion engineering,
and pressure vessel mechanical design. Process heat transfer issues may also enter the
decision. Type 304 has a higher allowable stress than 316 but a somewhat narrower
spectrum of corrosion resistance. It is also a little less expensive material. So it may be
indicated for plants that require large, higher pressure reactors. However if there is a
component of the polymerization that is corrosive to 304 then 316 might be preferred.
Material Properties:
AC408 gives consideration to maximum replacement volume, and maximum size
and density of synthetic particles that will be recognized in the evaluation report. AC408
requires synthetic particle properties, including maximum diameter and gradation, bulk
density, and water absorption to be tested in accordance with ASTM C 136, ASTM C 29
and ASTM C 128, respectively. A series of tests is also required by AC408 to determine
density and compressive strength of concrete that is to be evaluated under AC408.
Concrete compressive strength measurement is to be in accordance with ASTM C 39.
ASTM C 567 and ASTM C 138 are used to measure the equilibrium concrete density and
unit weight, respectively. These properties are measured and reported to be used for
flexural strength, splitting tensile strength and modulus of elasticity calculations.
Mechanical Properties:
As required by AC408, concrete flexural strength is to be determined using ASTM
C78, and average test results are to be equal to or higher than the value obtained from
7.5√fc, where fc is the measured compressive strength of the concrete in accordance with
ASTM C 39.
Fire-resistance and Combustibility:
AC408 also contains two optional tests: noncombustible building material
evaluation by testing in accordance with ASTM E 136 to show that concrete with
lightweight synthetic particles can be classified as noncombustible material and fire-
resistance-rated construction tests conducted in accordance with ASTM E 119 to determine
32
the fire-resistance ratings of assemblies with concrete containing the light weight synthetic
particles in the concrete mixture.
Acceptance Criteria Statements:
If a product demonstrates through tests that it satisfies all requirements of AC408,
an evaluation report is issued verifying that the product can be used as an alternative to
building code-specified materials.
1) Evaluation reports must state the maximum replacement amount of the light weight
synthetic particles that was utilized during the qualification tests, along with particle
density and maximum water absorption values.
2) To maintain product consistency, AC408 requires third-party follow-up inspections
by an approved inspection agency for the manufacture of the light weight synthetic
particles. This is required so that the manufacturer will continue to produce the same
product used during the qualification tests.
3) For structural design purposes, concrete containing light weight synthetic particles
must be considered as structural lightweight concrete. This requires use of ACI 318
parameters and design coefficients specified for structural light weight concrete. Because
the density of concrete produced using light weight synthetic particles as aggregate
replacement may vary, implementing light weight concrete coefficients and parameters is
considered to be a conservative approach for design of reduced-weight concrete with
synthetic light weight particles.
4) In addition to the items of ASTM C 94, the delivery ticket from the ready- mix plant
must include the type and amount of lightweight synthetic particles added to the concrete
mixture.
5) Because of the presence of compressible EPS beads in the concrete mixture, the creep
of the concrete was of concern. Therefore, for applications where computed deflections
contain long-term deflections due to sustained loads, creep effects based on creep test
results must be considered in design, which must be submitted to the code official for
approval.
6) Chloride content of EPS beads was of concern for corrosion of reinforcement.
10. HEALTH, SAFETY AND ENVIRONMENTAL ASPECTS
33
Waste products:Polystyrene manufacture is a relatively clean process. Small volumes of liquidand
gaseous wastes are generated and these are treated within the plants. Waste polystyrene
generated during production is reprocessed or sent to a recycler. Polystyrene manufacture
is a relatively clean process. Small volumes of liquid and gaseous wastes are generated and
these are treated within the plants. Waste polystyrene generated during production is
reprocessed or sent to a recycler. This is a Most Energy-EfficientPackaging Material.
Polystyrene is Safe, Hygienic Polystyrene and the Enemy ofBacteria.
Ease of disposal:According to the U.S. Environmental Protection Agency (EPA) in the 1999 update
of the"Characterization of Municipal Solid Waste in the U.S." report, less than one
percent(about 0.6 percent) of solid waste disposed of in the U.S. is polystyrene packaging -
including both food service packaging (cups, plates, bowls, trays, clam shells, meat trays,
egg cartons, yogurt and cottage cheese containers, and cutlery) and protective
packaging(shaped end pieces used to ship electronic goods and loose fill "peanuts").
The disposal of polystyrene is managed safely and effectively through the
integrated system advocated by the U.S. EPA, which includes: Source Reduction, Reuse,
Recycling, Waste-to-Energy Recovery, and Landfilling.
Polystyrene safe to use in contact with food:For more than 40 years, polystyrene has been in wide spread use as a hygienic
material for protecting and preserving food. In fact, one-reason polystyrene single use food
containers are so widely used in hospitals and other sensitive environment is that they are
significantly more hygienic than the alternatives. Polystyrene does not harbor bacteria,
which is a major concern among health specialists.
A recent American study shows that 1 in 7 reusable dishes harbor a level of
bacteria which exceeds US health standards. In contrast, no disposable food service items
exceeded the standards.
Foam Polystyrene – Presence of CFC’s:
34
Extruded foam polystyrene produced in for meat, chicken and vegetable trays and
take away food containers, does not use CFC blowing agents. Producers converted
awayfrom CFC's in 1989 and now operate on recycled carbon dioxide or hydrocarbon
gases.Expandable or bead polystyrene (EPS) such as in produce boxes has always used a
hydrocarbon blowing agent.
Reuse:Reuse, the practice of utilizing polystyrene products in the same form, is important
notonly because it delays the final disposal of a product, but also because it reduces
themanufacture and purchase of new products. As a result, reuse prevents waste. Nearly
30percent of polystyrene loose fill (sometimes called "peanuts" because of its shape)
isused again, making it one of the most commonly reused packaging materials in
someretail locations. For mailing services, the reuse rate of loose fill is as high as 50
percent.
The successful application of reused loose fill polystyrene reduced the demand for
virgin polystyrene by 25 percent in 1997 alone and, to this day, continues to directly
reduce waste.Other packaging and disposables commonly reused by the polystyrene
industry include:pallets, insulated shipping boxes, test tube trays, auto part trays, ice chests
and coolers.
Recycling:The recycling of polystyrene protective packaging and non-packaging polystyrene
materials, (such as audio/visual cassettes and agricultural nursery trays/containers) has
increased dramatically during the last decade and there has been a decrease in the amount
of polystyrene food service packaging recycled during this period. Non-food
servicepackaging is not contaminated with food and other wastes as is food service
polystyrene packaging, and therefore is more cost-effective to recycle. Presently, food
service polystyrene packaging is generally not recycled because it is not economically
sustainable. It is important to note that because of unfavorable economics, no other post
consumer food service disposable material, including paper and paperboard, is recycled in
a measurable way.
Before 1988, there was essentially no recovery of post-consumer polystyrene for
recycling, but as of 2000, just twelve years later, more than 397 million pounds of
35
polystyrene packaging were recycled. A portion of this material came from durable
polystyrene products such as coat hangers, compact disc "jewel cases," single-use cameras
and agricultural nursery trays.
Some companies that make protective packaging are collecting it back forrecycling
through the Alliance of Foam Packaging Recyclers. In addition, some makes of loose fill
"peanuts" have set up a network of collection sites for reuse and recycling of their
polystyrene products. Products that have incorporated recycled-content polystyrene
include: foam eggcartons, lunch trays, transport packaging, audio and videocassette cases,
office supplies and building materials.
Waste-to-Energy Recovery:In many overseas countries polystyrene is recycled through incineration of
municipal waste for energy recovery. The burning of polystyrene is no more hazardous
than combustion of many natural organic materials.
Polystyrene consists solely of carbonand hydrogen. When combustion is complete,
water and carbon dioxide are given off, leaving trace levels of ash, the same combustion
products as from paper or wood. While some polystyrene in medical an municipal wastes
is currently incinerated in Australia, the energy recovery option has not yet been
implemented.
When incinerated, polystyrene produces energy, which compares favorably
withcoal and oil. Because of its high fuel value, polystyrene in properly designed
incineratorshelps to burn wet garbage more efficiently, and maintain the high burning
temperaturesnecessary for safe combustion.The incineration of plastics can also generate
energy and this potential is alreadybeing harnessed in some overseas countries, particularly
in Western Europe, The UnitedStated and Japan.
36
Land filling:While recycling and reuse continue to grow in popularity, most of the waste in this
country still goes to landfills. People assume the waste inside a land fill biodegrades. But
the fact is that very little - not paper, not polystyrene, not even food waste - degrades in a
meaningful way.
Polystyrene is effectively and safely disposed of in landfills. Modern landfills are
designed to protect the environment from the liquids and gases produced during the very
slow breakdown by reducing the exposure of garbage to air, water and sunlight -conditions
needed for degradation. Therefore, by design, modern landfills greatly retardthe
degradation process to reduce the by-products that might otherwise contaminate
groundwater and the air.
Preventing Litter:The polystyrene industry cares about the environment. A widely held
misconception is that litter is a problem caused by specific materials themselves rather than
aberrant consumer behavior. The reality is that some people improperly dispose of
materials by littering. Littering is a matter of behavior, people who discard materials into
theenvironment usually do so because they don't think or don't care. Attributing the litter
issue to one particular packaging material does not solve the problem because another type
of packaging will take its place as litter unless behavior changes.
MSDS SHEETMSDS Name: Polystyrene
Chemical Family: Polymer.
Hazards Identification:Physical State
Appearance
Emergency Overview
Routes of Entry
Potential Acute Health
Solid
Pellets
Irritating vapors to respiratory system and eyes may
form when polymer is processed at high temperatures.
Molten or heated material in skin contact can cause
severe burns.
For Hot Material: skin contact, eye contact, and
inhalation.
37
Effects:
Eyes
Skin
Inhalation
Ingestion
First Aid Measures:
Eye Contact
Skin Contact
Inhalation
Ingestion
Fire Fighting Measures:
Flammability of the Product
Auto-ignition Temperature
Flash Points
Flammable Limits
Products of Combustion
Explosion Hazards in
Presence of Various
Substances
Dust may cause mechanical irritation to eye.
Heated Polymer: Eye contact can cause serious
thermal burns.
Vapours formed when polymer is heated may be
irritating to the eye.
No known acute effects of this product resulting from
skin contact at room temperature.
Negligible at room temperature. Nuisance dusts can be
irritating to the upper respiratory tract.
Irritating vapors may form when the polymer is
processed at high temperatures.
No effects are expected for ingestion of small amounts.
May be a choking hazard.
Rinse with water for a few minutes. Seek medical
attention if necessary.
Polymer: NO known effect on skin contact, rinse with
water for few minutes.
Heated Polymer:For serious burns from heated
polymer, get medical attention. In case of skin contact,
immediately immerse in or flush with clean, cold water.
Allow the victim to rest in a well-ventilated area.
No First Aid procedures are needed.
May be combustible at high temperature.
440°C (824°F)
>200°C (>392°F)
Not available
Carbon oxides (CO, CO2) and soot.
Risks of explosion of the product in presence of
mechanical impact: Not expected.
Risks of explosion of the product in presence of static
38
Fire Fighting Media and
Instructions
Protective Clothing (Fire)
Special Remarks on
FireHazards
Special Remarks on
Explosion Hazards
Handling and Storage:
Handling
discharge: Possible.
Risk of explosion from dust accumulation of this
product is possible.
SMALL FIRE: Dry chemical extinguisher (ABC or
AB). Use water spray or fog.
LARGE FIRE: Use water spray or fog. Do not use
water jet.
May re-ignite itself after fire is extinguished.
Wear MSHA/NIOSH approved self-contained
breathing apparatus or equivalent and full protective
gear.
Fire may produce irritating gases and dense smoke.
Flowing material may produce static discharge, igniting
dust accumulations.
Processing or material handling equipment may
generate dust of sufficiently small particlesize, that
when suspended in air may be explosive.
Avoid Temperatures of 600°F (316°C) or above.
Handling of plastic may form nuisance dust. Protect
personnel.
Pneumatic material handling and processing equipment
may generate dust of sufficiently small particle size
that, when suspended in air, may be explosive. Dust
accumulations should be controlled through a
comprehensive dust control program that includes, but
is not limited to,source capture, inspection and repair of
leaking equipment, routine housekeeping and employee
training in hazards.
When handled in bulk quantities, this product and its
associated packaging may present a crushing hazard
due to the large masses involved, possibly resulting in
severe injury or death.
Keep container dry. Keep in a cool place. Ground all
39
Storage
Personal Protection:
Eyes
Body
Respiratory
Hands
Feet
Stability and Reactivity:
Stability and Reactivity
Incompatibility with
Various Substances
Hazardous Decomposition
Products
Hazardous
Polymerization
equipment containing material. Keepcontainer tightly
closed. Keep in a cool, well-ventilated place.
Combustible materials shouldbe stored away from
extreme heat and away from strong oxidizing agents.
Safety glasses
Coveralls.
Ventilation is normally required when handling this
product at high temperatures. Wear appropriate
respirator when ventilation is inadequate.
Thermally insulated gloves required when handling hot
material.
Shoes.
The product is stable. Avoid Temperatures of 600°F
(316°C) or above.
Reactive with strong oxidizing agents.
Hazardous decomposition products are carbon
monoxide, carbon dioxide, dense smoke, and various
hydrocarbons. Exposure of polystyrene to extremely
high temperatures (600oF orhigher) may cause partial
decomposition. Chemicals that may be released include
styrenemonomer, benzene, and other hydrocarbons.
No.
11. PLANT LOCATION AND LAYOUT
Plant Location
40
The geographical 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, and of the plant on studying many factors Visakhapatnam in
Andhra Pradesh is selected as the best place. The principal factors to be considered are:
Marketing area.
Raw material supply.
Transport facilities.
Availability of labour.
Availability of utilities: water, fuel, power.
Availability of suitable land.
Environmental impact, and effluent disposal.
Local community considerations.
Climate.
Political strategic considerations.
Marketing Area
For materials that are produced in bulk quantities: such as cement, mineral acids
and fertilizers, where the cost of the product per ton is relatively low and the cost of
transport a significant fraction of the sales price, the plant should be located close to the
primary market. This consideration will be less important for low volume production, high-
priced products; such as pharmaceuticals. In an international market, there may be an
advantage to be gained by locating the plant within an area with preferential tariff.
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. Soda ash plant should be
located near the salt lakes or near sea, where sodium chloride is available abundantly.
Transport
The transport of materials and products to and from plant will be an over riding
consideration in site selection. If practicable, a site should be selected that is close at least
41
two major forms of transport: road, rail, waterway or a seaport. 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.
Availability of Labor
Labor will be needed for construction of the plant and its operation. Skilled
construction workers will usually be brought in from outside the site, but there should be
an adequate pool of unskilled labor available locally and labor suitable for training to
operate the plant. Skilled trades men will be needed for plant maintenance. Local trade
union customs and restrictive practices will have to be considered when assessing the
availability and suitability of the labor for recruitment and training.
Utilities (services)
The word “utilities” is now generally used for the auxiliary services needed in the
operation of any production process. These services will normally be supplied from a
central facility and will include:
• Electricity - Power required for electrochemical processes, motors, lightings and general
use.
• Steam for process heating - The steams required for the process are generated in the tube
boilers using most economic fuel.
• Cooling water - Natural and forced draft cooling towers are generally used to provide the
cooling water required on site.
• Water for general use - The water required for the general purpose will be taken from
local water supplies like rivers, lakes and seas. Because of this reason all the plants located
on the banks of river.
• Dematerialized water - Dematerialized water, from which all the minerals have been
removed by ion-exchange is used where pure water is needed for the process use, in boiler
feed water.
• Refrigeration - Refrigeration is needed for the processes, which require temperatures
below that are provided by the cooling water.
• Inert-gas supplies.
42
• Compressed air - In a polystyrene plant compressed air is one of the raw materials. It is
also needed for pneumatic controllers etc.
• Effluent disposal facilities - Facilities must be provided for the effective disposal of the
effluent without any public nuisance.
Environmental Impact and Effluent Disposal
All industrial processes produce waste products, and full consideration must be
given to the difficulties and coat 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.
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. Land (site considerations) sufficient suitable
land must be available for the proposed plant and future expansion. The land should be
ideally flat, well drained and have load-bearing characteristics. A full site evaluation
should be made to determine the need for piling or other foundations.
Climate
Adverse climatic conditions at site will increase costs. Abnormally low
temperatures will require the provision of additional insulation and special heating for
equipment and piping. Stronger locations will be needed at locations subject to high wind
loads 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 the overriding consideration in site
selection.
Plant Lay Out
43
The economic construction and efficient operation of a process unit will depend on
how well the plant and equipment specified on the process flow sheet is laid out. The
principal factors are considered are:
Economic considerations: construction and operating costs.
The process requirements.
Convenience of operation.
Convenience of maintenance.
Safety.
Future expansion.
Modular construction.
Costs
The cost of construction can be minimized by adopting a layout that gives the
shortest run of connecting pipe between equipment, and at least amount of structural steel
work. However, this will not necessarily be the best arrangement for operation and
maintenance.
Process Requirements
An example of the need to take into account process consideration is the need to
elevate the base of columns to provide the necessary net positive suction head to a pump or
the operating head for a thermo siphon reboiler.
Operations
Equipment that needs to have frequent attention should be located convenient to the
control room. Valves, sample points, and instruments should be located at convenient
positions and heights. Sufficient working space and headroom must be provided to allow
easy access to equipment.
Maintenance
Heat exchangers need to be sited so that the tube bundles can be easily with drawn
for cleaning and tube replacement. Vessels that require frequent replacement of catalyst or
packing should be located on the outsideof buildings. Equipment that requires dismantling
for maintenance, such as compressors and large pumps, should be places under cover.
44
Safety
Blast walls may be needed to isolate potentially hazardous equipment, and confine
the effects of an explosion. At least two escape routes for operators must be provided from
each level in process buildings.
Plant expansion
Equipment should be located so that it can be conveniently tied in with any future
expansion of the process. Space should be left on pipe alleys for future needs, and service
pipes over-sized to allow for future requirements.
Modular construction
In recent years there has been a move to assemble sections of plant at the plant
manufacturer’s site. These modules will include the equipment, structural steel, piping and
instrumentation. The modules are then transported to the plant site, by road or sea.
The advantages of modular construction are:
Improved quality control.
Reduced construction cost.
Less need for skilled labour on site.
Some of the disadvantages are:
Higher design costs & more structural steel work.
More flanged constructions & possible problems with assembly, on site.
The Plant Layout Key Words1. Raw material Storage
2. Product Storage
3. Process Site
4. Laboratories
5. Workshop
6. Canteen & Change house
7. Fire Brigade
8. Central Control Room
9. Security office
45
10. Administrative Building
11. Site for Expansion Project.
12. Effluent treatment plant
13. Power house
14. Emergency water storage
15. Plant utilities
A detailed plant layout is drawn and some general considerations that influenced the plans
follow:
1. Space was set aside for a whole new train.
2. The prevailing wind in the summer comes from the northwest and in the winter comes
from the west.
3. The blow down tank is located on the south side of the plant where winds will
notgenerally carry any spills over the plant.
4. The utilities and the waste treatment areas are located on the north side of theplant
where they will be upwind of the plant.
5. The styrene storage will be located on the south side of the plant 300ft from the river
and the dock. It will be 300ft from the processing area.
6. The warehouse and the bulk storage will be located on the west side, upwind from the
plant and styrene storage. They will be at least 250ft from reactor area.
7. The reactor and the feed preparation area will be on the east side of the plant 200ft from
the river.
8. The other processing areas will be between the reactor area and the warehouse. They
will be over 200ft from the reactor area.
Some specific considerations follow:
1. There must be enough headroom above the reactor to remove the agitator.
2. There must be enough room to remove the screw from the extruder.
3.Gravity feed is to be used for charging additives to the reactor, for discharging the
reactor to the hold tanks, and for feeding the dryer.
4. Each of the styrene storage tanks will have a dike around it that is capable of containing
the tank’s contents when it is full.
46
Figure: 9 plant layout
12. COST ESTIMATION
47
Calculation of fixed capital cost:The Chemical Engineering Plant cost Index (CEPI):
In 1969, CI1 = 119.0
In 2013, CI2 = 685.0
Let us assume that the plant is running for 325 days a year.
From literature, the capital cost for the proposed plant should range between $124 and
$253 per annual ton.
Let us take value of 1$ = Rs 50.
Let us take capital cost = $200 per annual ton.
i.e., C1= Rs 10000 per annual ton.
Total tones of polystyrene produced every year = 325 * 250
= 81250tones /year.
Therefore the capital cost for proposed plant in 1969 is = 81250*10000
= Rs.8.125*108
From, William's six-tenth rule,
CI1/ CI2= C1/C2
C2 = C1 * (CI2/CI1)
The fixed capital cost for the proposed plant in 2013 = 8.125*108*685/119
i.e., C2 = Rs 467.69*107
= Rs 467.69crores.
Estimation of Capital Investment Cost:
I. Direct Costs: material and labor involved in actual installation of
completefacility (70-90% of fixed-capital investment).
a. Equipment + installation + instrumentation + piping + electrical + insulation +
painting(50-60% of Fixed-capital investment).
1. Purchased equipment cost (PEC):(15-40% of Fixed-capital investment)
Consider purchased equipment cost = 30% of Fixed-capital investment
i.e., PEC = 30% of 467.69*107
= 0.30 * 467.69*107
= Rs. 140.31*107
2. Installation, including insulation and painting:(25-55% of purchased
equipment cost.)
48
Consider the Installation cost = 35% of Purchased equipment cost
= 35% of 140.31*107
= 0.35 *140.31*107
= Rs.49.11*107
3. Instrumentation and controls, installed:(6-30% of Purchased equipment
cost.)
Consider the installation cost = 15% of Purchased equipment cost
= 15% of *140.31*107
= 0.15 *140.31*107
= Rs.21.05*107
4. Piping installed:(10-80% of Purchased equipment cost)
Consider the piping cost = 35% Purchased equipment cost
= 35% of Purchased equipment cost
= 0.35 *140.31*107
= Rs. 49.11*107
5. Electrical, installed:(10-40% of Purchased equipment cost)
Consider Electrical cost = 25% of Purchased equipment cost
= 25% of 140.31*107
= 0.25 *140.31*107
= Rs.35.0775*107
b. Buildings, process and Auxiliary: (10-70% of Purchased equipment cost)
Consider Buildings, process and auxiliary cost= 30% of PEC
= 30% of 140.31*107
= 0.30 *140.31*107
= Rs.42.093*107
c.Service facilities and yard improvements:(40-100% of Purchased equipment
cost)
Consider the cost of service facilities and yard improvement= 50% of PEC
= 50% of 140.31*107
= 0.50 *140.31*107
= Rs 70.155*107
d. Land:(1-2% of fixed capital investment or 4-8% of Purchased equipment cost)
Consider the cost of land = 6% PEC
49
= 6% of 140.31*107
= 0.06 *140.31*107
= Rs. 8.42*107
Thus, Direct cost = Rs.415.325*107 ----- (88.80% of FCI)
II. Indirect costs: Expenses which are not directly involved with material and
labor of actual installation of complete facility (15-30% of Fixed-capital investment).
a. Engineering and Supervision:(5-30% of Fixed-capital investment)
Consider the cost of engineering and supervision = 10% of direct cost
= 10% of 415.325*107
= 0.1*415.325 *107
= Rs 41.5325*107
b. Construction Expense and Contractor’s fee: (6-30% of Fixed-capital
investment)
Consider the construction expense and contractor’s fee = 10% of Direct costs
= 10% of 415.325*107
= 0.1* 415.325 *107
= Rs 41.5325*107
c. Contingency:(5-15% of Fixed-capital investment)
Consider the contingency cost = 10% of Fixed-capital investment
= 10% of 415.325 *107
=Rs.41.5325*107
Thus, Indirect Costs = Rs. 124.5975*107 --- (26.64% of FCI)
III. Fixed Capital Investment:Fixed capital investment = Direct costs + Indirect costs
= (415.325 *107) + (124.5975*107)
i.e., Fixed capital investment = Rs. 539.92*107
IV. Working Capital:(10-20% of Fixed-capital investment)
Consider the Working Capital = 15% of Fixed-capital investment
50
i.e., Working capital = 15% of 539.92*107
= 0.15 * 539.92*107
= Rs. 80.988*107
V. Total Capital Investment (TCI):Total capital investment = Fixed capital investment + Working capital
= (539.92*107) + (80.988*107)
i.e., Total capital investment = Rs. 620.908*107.
Estimation of Total Product cost:
I. Manufacturing Cost = Direct production cost + Fixed charges + Plant
overhead cost.
a. Fixed Charges:(10-20% total product cost)
i. Depreciation: (depends on life period, salvage value and method of calculation-about
13% of FCI for machinery and equipment and 2-3%for Building Value for Buildings).
Consider depreciation = 12%of FCI for machinery and equipment and 4%for building
Value for Buildings)
i.e., Depreciation = (0.12*140.31*107)+ (0.04*42.093*107)
= Rs. 18.521*107 (from straight line depreciation)
ii. Local Taxes: (1-4% of fixed capital investment)
Consider the local taxes = 3% of fixed capital investment
i.e., Local Taxes = 0.03*539.92*107
= Rs. 16.1976*107
iii. Insurances: (0.4-1% of fixed capital investment)
Consider the Insurance = 0.6% of fixed capital investment
i.e., Insurance = 0.006*539.92*107
= Rs. 3.24*107
iv. Rent: (8-12% of value of rented land and buildings)
Consider rent = 10% of value of rented land and buildings
= 10% of ((8.42*107) + (42.093*107))
= 0.10* ((8.42*107) + (42.093*107))
Rent = Rs. 50.513*107
Thus, Fixed Charges = Rs. 88.472*107
51
b. Direct Production Cost: (about 60% of total product cost)
Now we have Fixed charges = 10-20% of total product charges – (given)
Consider the Fixed charges = 15% of total product cost
Total product charge = fixed charges/15%
Total product charge = 88.472*107/15%
Total product charge = 88.472*107/0.15
Total product charge (TPC) = Rs. 589.82*107
i. Raw Materials: (10-50% of total product cost)
Consider the cost of raw materials = 25% of total product cost
Raw material cost = 25% of 589.82*107
= 0.25*589.82*107
Raw material cost = Rs. 147.45*107
ii. Operating Labor (OL): (10-20% of total product cost)
Consider the cost of operating labor = 15% of total product cost
Operating labor cost = 15% of 589.82x107
= 0.15*589.82*107
Operating labor cost = Rs. 88.473*107
iii. Direct Supervisory and Clerical Labor (DS & CL): (10-25% of OL)
Consider the cost for Direct supervisory and clerical labor = 12% of OL
Direct supervisory and clerical labor cost = 12% of 88.473*107
= 0.12*88.473*107
Direct supervisory and clerical labor cost = Rs. 10.61676*107
iv. Utilities: (10-20% of total product cost)
Consider the cost of Utilities = 12% of total product cost
Utilities cost= 12% of 589.82*107
= 0.12*589.82*107
Utilities cost = Rs. 70.7784*107
v. Maintenance and repairs (M & R): (2-10% of fixed capital investment)
Consider the maintenance and repair cost = 5% of fixed capital investment
i.e., Maintenance and repair cost = 0.05*539.92*107
= Rs. 26.996*107
vi. Operating Supplies: (10-20% of M & R or 0.5-1% of FCI)
Consider the cost of Operating supplies = 15% of M & R
52
i.e., Operating supplies cost = 15% of 26.996*107
= 0.15 *26.996*107
Operating supplies cost = Rs. 4.094*107
vii. Laboratory Charges: (10-20% of OL)
Consider the Laboratory charges = 15% of OL
i.e., Laboratory charges = 15% of 88.473*107
= 0.15*88.473*107
Laboratory charges = Rs. 13.271*107
viii. Patent and Royalties: (0-6% of total product cost)
Consider the cost of Patent and royalties = 4% of total product cost
i.e.,Patent and Royalties= 4% of 589.82*107
= 0.04*589.82*107
Patent and Royalties cost = Rs 23.593*107
Thus, Direct Production Cost = Rs. 385.272*107 ----- (65.32% of TPC)
c. Plant overhead Costs (50-70% of Operating labour, supervision, and
maintenance or5-15% of total product cost); includes for the following: general plant
up keep and over head, payroll overhead, packaging, medical services, safety and
protection, restaurants, recreation, salvage, laboratories, and storage facilities.
Consider the plant overhead cost = 60% of OL, DS & CL, and M & R
Plant overhead cost = 60% of ((88.473*107) + (10.61676*107) + (26.996*107))
Plant overhead cost = 0.60 * ((88.473*107) + (10.61676*107) + (26.996*107))
Plant overhead cost = Rs. 75.651*107
Thus, Manufacture cost = Direct production cost + Fixed charges + Plant overheadcosts.
Manufacture cost = (385.272*107) + (88.472*107) + (75.651*107)
Manufacture cost = Rs. 549.395*107
II. General Expenses = Administrative costs + distribution and selling costs +
research and development costs + financing.
a. Administrative costs:(2-6% of total product cost)
Consider the Administrative costs = 5% of total product cost
i.e.,Administrative costs = 0.05 * 589.82*107
= Rs. 29.491*107
b. Distribution and Selling costs: (2-20% of total product cost): includes
costs forsales offices, salesmen, shipping, and advertising.
53
Consider the Distribution and selling costs = 15% of total product cost
i.e.,Distribution and selling costs = 15% of 589.82*107
= 0.15 *589.82*107
= Rs. 88.473*107
c. Research and Development costs: (about 5% of total product cost)
Consider the Research and development costs = 5% of total product cost
i.e., Research and Development costs = 5% of 589.82*107
= 0.05 *589.82*107
= Rs. 29.491*107
d. Financing (interest):(0-10% of total capital investment)
Consider interest = 5% of total capital investment
i.e., interest = 5% of 620.908*107
= 0.05*620.908*107
Interest = Rs. 31.0454*107
Thus, General Expenses = Rs. 178.5004*107
III. Total product cost= Manufacture cost + General Expenses
= (549.395*107) + (178.5004*107)
Total product cost = Rs. 727.8954*107
IV. Gross Earnings/Income:Wholesale Selling Price of Polystyrene per ton = $ 2000 (USD)
Let 1 USD = Rs. 50.00
Hence Wholesale Selling Price of Polystyrene per tonne = 2000 *50 = Rs. 100000
Total Income = Selling price * Quantity of product manufactured
= 100000 * (250 T/day) * (325days/year)
Total Income = Rs.8.125x109
Gross income = Total Income – Total Product Cost
= (8.125*109) – (727.8954*107)
Gross Income = Rs. 846.046*106
Let the Tax rate be 45% (common)
Taxes = 40% of Gross income
= 40% of 846.046*106
= 0.40*937.84*106
54
Taxes = Rs. 338.4184 *106
Net Profit = Gross income - Taxes
Net profit = (846.046*106) – (338.4184 *106)
= Rs. 507.6276*106
Rate of Return:Rate of return = Net profit*100/Total Capital Investment
= 507.6276*106*100/ (620.908*107)
Rate of Return = 8.1755%
Break-even Analysis:Data available:
Annual Direct Production Cost = Rs.385.272*107
Annual Fixed charges, overhead and general expenses = Rs. 3.85272*109
Total Annual sales = Rs. 8.125* 109
Wholesale Selling Price of polystyrene per tonne = Rs. 100000
Direct production cost per ton of polystyrene = (385.272*107)/ (8.125 x 109/100000)
= Rs. 47418.09 per ton
Let ‘n’ TPA be the break even production rate.
Number of tons needed for a break-even point is given by
(3.85272*109) + (47418.09 *n) = (100000*n)
i.e., n = 73270.83 tons/year
n = 225.45 tons/day = 225.45 TPD
Hence, the break-even production rate is 225.45TPD or 48.20% of the considered plant
capacity.
12. BIBLIOGRAPHY
55
1. ID Mall, Petrochemical Process Technology, Macmillan India Ltd., New Delhi,
2007.
2. E.E Ludwig, Applied Process Design For Chemical & Petro Chemical Plants,
Vol-1,2&3, Gulf Professional Publishing, 3rdEdition, Elsevier,2001.
3. Max Peters, Klaus D. Timmerhaus, Ronald West, Plant Design & Economics For
Chemical Engineers, 5th Edition, Tata McGraw-Hill, 2011.
4. Gael D.Ulrich, A Guide to Chemical Engineering Process Design & Economics,
Process Publishing, 1984.
5. P. Trambouze, Petroleum Refining: Materials and Equipment, Editions Technip,
2000.
6. Daniel A. Crowl, Joseph F. Louvar, Chemical Process Safety: Fundamentals with
Applications, 3rd Edition, Prentice Hall, 2011.
7. E.BruceNauman, Chemical Reactor Design, Optimization and Scale Up, McGraw-
Hill Publications.
8. James B. Rawlings, Job 6. Ekerdt, Chemical Reactor Analysis And Design
Fundamentals, Nob Hill Publishing, Madison, Wisconsin.
9. Nicholas P Chopey, Hand Book of Chemical Engineering Calculations, 3rd
Edition.10. Perry’s,Chemical Engineers Hand Book.
11. M.V.Joshi,Production of Polystyrene.
12. McCabe, Smith, Peter Harriot, Unit Operations of chemical engineering, 5th
edition, McGraw-Hill Publications.
13. Donald Q. Kern, Process Heat Transfer, International edition, 1965.
14. International Critical Tables, Vol.3.
Web Links:
1. www.freepatentsonline.com
2. www.indianprocessgeneral.com
3. www.docstoc.com
4. www.springerlink.com
5. www.sciencedirect.com
6. http://en.wikipedia.org
7. http://www.chemicalbook.com
56