Design of a Process Plant for the Production of 10,000

liters/day of Fuel Oil from Plastic Wastes

 CHAPTER ONE
1.1. INTRODUCTION

Plastics are indispensable material used in present world. Plastics are non-biodegradable material
which contains carbon, hydrogen and few other elements such as chlorine, nitrogen etc. plastics
have properties such as light weight, durability, energy efficiency, coupled with a faster rate of
production and design flexibility, these plastics are employed greater importance in industrial and
domestic areas. The major problem in worldwide is increasing commodity waste plastics with the
increasing in the population. The main origin of the waste plastic is from industrial and domestic
wastes due to non-biodegradable nature. Production of plastic is growing increasingly which is
more than 200MT worldwide. Due to lack of integrated solid waste management, most of the
plastic neither collected nor disposed in a good manner which creates negative impact in the
present world.

Plastic waste recycling is done to convert into some useful resources where the plastics are
collected and disposed in environment friendly manner. Waste plastic is the one of the prominent
sources for converting into fuel production because of its high calorific value and high heat of
combustion rate. Plastics have different conversion methods which are based on different kinds of
plastic.

1.1.1 Low density polyethylene (LDPE)

Low density polyethylene (LDPE) is a thermoplastic made from the petroleum. It was the first
grade of polyethylene produced by imperial industries (ICI) using a high-pressure process via free
radical polymerization. LDPE is commonly recycled and has the number ‘4’ as it’s recycled
symbol. Despite competition from more modern polymers, it contains to be an important plastic
grade. LDPE contains the chemical elements carbon and hydrogen. It is defined by a density range
of 0.91-0.94 g/cm3.

Its low density resembles the presence of small amount of branching in the chain (on about 2% of
the carbon atoms) and this is more open structure. LDPE is most commonly used plastic in daily
life like plastic covers, bottles etc.
1.2. Problem Statement
Two important problems are found for conversion of plastics i.e., scarcity of fossil fuels and solid
waste management. Scarcity of resources indicated due to its economic growth is unsustainable
without saving fossil fuels like crude oil, natural gas or coal. According to the reports of
international energy outlook says that world consumption of fossil fuels such as petroleum and
diesel grows from 86.1 million barrels per day in 2007 to 92.1 million barrels per day in 2020,
103.9 million barrels per day in 2030 and 110.6 million barrels per day in 2035 and natural gas
consumption increases from 108 trillion cubic feet in 2007 to 156 trillion cubic feet in 2035. The
similar way of consumption goes into scarcity of fuels for further hundred years. Conversion of
waste plastic to liquid fuel helps in alternate path can contribute to depletion of fossil fuel.

Solid waste management is another important aspect for sustainable development. Plastic is the
one of important aspect involved in the solid waste management. Due to the increasing in the use
of plastic, which is a non-biodegradable material, due to versatility and relatively low cost. Waste
plastic is mostly obtained from the industrial and domestic uses. Advanced research has been done
on the waste plastic which can been converted into liquid fuels using different chemical process.
Production of liquid fuel is a better alternative as the calorific value of the plastics is comparable
to the liquid fuels, around 40MJ/kg and it is carried out by pyrolysis process, occur in the absence
of the oxygen at hog temperatures.

1.3 Aim and Objectives

The overall aim of the project is to design a plant for conversion of waste plastic mainly low-
density polyethylene into fuel oil by thermal pyrolysis process. The specific objectives are:

• To study the thermal pyrolysis of waste plastic (low density polyethylene (LDPE)) into liquid
fuel.

• To design the plant for conversion of waste plastic (LDPE) to produce 10000 Liters of fuel oil
per day.

1.4 Scope of the Design

The scope of this work is restricted to the paper design of the conversion process of waste plastic
into fuel oil by thermal pyrolysis. The design report is based on data available from previous
researches as there is no new research done.
1.5. Relevance of the Design
The use of plastics for fabrication of various items of domestic and industrial purposes has
increased over the years for reasons including; the durability and lightweight of plastics. Additives
such as stabilizers and anti- oxidants are added to the base materials of plastics to enhance their
plastic properties. Improper disposal of plastic waste has a negative impact on the environment
due to the presence of these stabilizers and anti-oxidants in plastics. Conversion of plastic wastes
to fuel oil would can change the narrative of the negative impact on the environment, remediating
our immediate environment and producing fuel which can be used for multiple purposes.

Figure 1: Different types of waste plastic

 CHAPTER TWO

LITERURE REVIEW
2.1 Plastics
In today's world, plastics are a necessary substance. Plastic is a polymeric class of artificial or
organic materials with a preponderance of carbon components. Plastics are a broad category of
materials made of combinations of oxygen, hydrogen, nitrogen, and other organic or inorganic
materials that may be heated and molded into any shape. By adding a single monomer repeatedly
using different chemical processes, plastics are built into polymers. Due to plastic's versatility and
affordability, its use has increased over the past few decades. Plastics are lightweight, simple to
use, and require little upkeep.

Plastics are generalized into two groups like thermoplastics and thermoset plastics. Thermoplastics
are linear chain macromolecules in which the atoms and molecules are combined end to end into
long series. Formation of linear molecules from vinyl monomers can be achieved by opening the
double bond and processes by radial polymerization like polyethylene, polypropylene etc.
thermoset plastics are different set plastics are formed step by step polymerization under suitable
conditions allowing molecules to condensate the intermolecularity with small by products such as
H2O, HCl etc.at every step.

2.1.1 Low density polyethylene (LDPE)

Petroleum is used to create the thermoplastic known as low density polyethylene (LDPE). Imperial
Industries (ICI) used a high-pressure technique and free radical polymerization to create the first
grade of polyethylene. The recycle symbol for LDPE is the number 4, and it is frequently recycled.
It continues to be a significant plastic grade in spite of competition from more contemporary
polymers. Carbon and hydrogen are chemical components of LDPE. Its density ranges from 0.91
to 0.94 g/cm3.
FIGURE 2.1 Recycle number for LDPE.

Up until 1950, only low-density plastic (polyethylene) was made. Imperial Industries began
manufacturing LDPE in 1933. The moniker "LDPE" refers to the material's low density and
varying concentrations of branches that prevent crystallization. The two primary chemical
branches in low density polyethylene are ethyl and butyl groups. The degree of branching involved
in LDPE and HDPE differs. In the presence of oxide initiators, ethylene is used as the monomer
to create LDPE at extremely high pressures of about 350 mega Pascal and higher temperatures of
around 350 'C. Both long and short branches of polymer are produced using this method. The
melting point of LDPE, a flexible polymer, is around 110oC.

2.1.1.1 Structure and physical chemistry of LDPE

Ethylene (C2H4) is a gaseous hydrocarbon produced commonly by cracking ethane, which
constituent of natural gas or distilled from petroleum. Ethylene molecules consist of two methylene
groups linked together by double bond between the carbon atoms. Under the guidance of
polymerization catalyst, double bond is broken and an extra bond single molecule is connected
leading to formation of polymer of multiple units. The simple structure repeats hundred times of a
single molecule which is key to properties of the polyethylene. The long chain like molecules in
which hydrogen atoms are connected to a carbon backbone can be produced in linear or branched
forms which are known as low density polyethylene. The structure of LDPE is linear, branched
and network system. Branched polymer molecules cannot pack together as closely as linear
molecules can and hence the intermolecular forces binding these polymers together tend to be
much weaker. This is the reason why the highly branched LDPE is very flexible and finds use as
packaging film, while the linear HDPE is tough enough to be shaped into such objects as bottles
or toys.
FIGURE 2.2 Structure of LDPE, HDPE and LLDPE.

TABLE 2.1 Physical properties of LDPE

Tensile strength 0.2-.14N/mm2

Notched impact strength No break

Thermal coefficient of expansion 100-200x10^-6

Max. content use temperature 65’c

Density 0.917-0.93g/cm^3

LDPE is resistant to chemicals like dilute acid, dilute alkalis, oil and greases, aliphatic
hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons and alcohols. LDPE are mi-
rigid, translucent, very tough, weatherproof, good chemical resistance, low water absorption,
easily processed by most methods, low cost.

2.1.1.2 Uses of LDPE

LDPE is widely used in many applications like containers, dispensing bottles, tubing, and plastic
bags for computers components, wash bottles and in various packing covers for equipment. LDPE
is used in different trays and general-purpose containers, corrosion- resistant work surfaces, parts
that need to be weld able and machinable, parts that require flexibility, very soft and pliable parts
such as snap on lids, six pack rings, juice and milk cartons are made of liquid packing board,
laminate of paperboard and LDPE (as the water proof inner and outer layer), and often with of a
layer of aluminum foil (thus becoming aseptic packaging), packaging for computer hardware, such
as hard disk drives, screen cards and optical disc drives, playground slides, plastic wraps and etc.

2.1.1.3 Demand for LDPE

The demand for LDPE is highest in Asia and followed by Europe. The increasing demand has been
increased with population and Asian demand by volume for LDPE in 2009 was 5.9 million MT.
Asia and Europe are the leading users for LDPE around the world but whereas china maintains
stable requirements of plastic. The future growth of LDPE provides a depth analysis of the global
low-density polyethylene (LDPE). Major economic and market trends are affected by the LDPE
markets in all regions of world as per the research. The global demand for LDPE is expected to
grow at a CAGR of around 2% from 2009 to 2020 according to the GBI research. Over few
decades, as per the market LDPE remained applications has begun to stabilize in the very large
world scale LDPE equipment. Wiling investors in Iran, the gulf countries, and china have driven
a number of new large LDPE projects, which began coming on stream during 2008-10. In the next
few years new investments will be made on the North America, Middle East and china.

2.2 Plastic waste recycling

Usage of plastic material has growing in proportion of the both municipal and industrial waste
decompose into land. Huge amount of waste plastics and environmental pressures results in
recycling of plastics has become an important role in today plastic industry. In today’s plastic,
waste plastic became a major problem and reuse and recycling process are carried out which are
cost effective. The recycling and reuse of plastics make in decreasing of the quality of products
which can used in other normal purposes. The recycling is divided into four processes which are;

2.2.1 Primary recycling

This type of recycling considered about the materials that are clean and uncontaminated. After the
use of the material, the material has been recycled which are comparable with the original plastic
or mixed with different kind of plastic for quality. This type of recycling is simple, effective and
least cost.
2.2.2 Secondary recycling
This type of recycling is considered as conversion of waste plastics into lower fewer demanding
plastics of lower demand. This type of recycling has two approaches where one approach is to
separate the contaminants and been carried out by the primary recycling.

Another approach is to separate from contaminants and re-melt them as a mixture without
segregation. This type plastics areu undergone different processes cleaning, drying and
compounding.

2.2.3 Tertiary recycling

This type of recycling is considered chemical recycling. The terms chemical recycling and
feedstock recycling are collectively considered as advanced technology recycling. In this type,
plastics are converted into smaller molecules as chemical intermediates through chemical and heat
treatment/ plastics are converted into liquids and solids. Different processes are

2.2.3.1 Chemolysis
This process led to conversion of plastic back into monomers by depolymerization with the help
of different catalyst. Chemolysis processes include range of such as glycolysis, hydrolysis,
methanolysis and alcoholysis.

2.2.3.1.1 Hydrolysis
Hydrolysis process led to reaction of water molecules at the linkage points of the starting materials.
Hydrolysis plastics such as polyamides. Polysters, polycarbonates. Polyureas and polyurethanes
which are resistant to hydrolysis. Outstanding products are yielded with this process where 100%
of the polyether and 90%of amine can be recovered.

2.2.3.1.2 Alcoholysis
By this process, polyurethanes are degraded to give polyhydroxy alcohol and small urethane
fragments. Carbon dioxide is not at all formed I this type reaction. In this diol is used for then
ureathes are also contains terminal hydroxyl groups. This forms polyurethane foam from
polyhydroxy following isocyanides addition and varying in proportions.
2.2.3.1.3 Glycolysis and methanolysis
By this process, degradation takes place in presence of glycol such as ethylene glycol or diethylene
glycol and degradation of polymers in the presence of methanol is known as methanloysis.

2.2.3.2 Gasification or partial oxidation

polymeric waste which has good calorific value and this is due to noxious substances like sulfur
oxides, dioxins, hydrocarbons and NOx. A waste gasification and smelting system using iron or
steel making technologies to produce a dioxin free and purified high calorific gas. In this process,
60-70% hydrogen is recovered back from partial oxidation.

2.2.3.3. Cracking
2.2.3.3.1 Thermal cracking
Thermal pyrolysis is a process of degradation of polymeric materials heating in absence of oxygen.
Usually, this process is conducted at around 500-800’c temperatures resulting formation char,
liquid formation and resulting non-condensable high calorific gas. This process involves
intermediate and intramolecular reactions for the initial degradation into secondary products.
These reactions depend on the temperature and residence of products and nature of reaction. Here
reactor design plays an important role in thermal pyrolysis.

2.2.3.3.2 Catalytic degradation

Many researches have processed on the thermal cracking for obtaining greater yield of product
and reduction of temperature. In this process, degradation takes place with the help catalyst which
helps in above reductions. The laboratory experimental set up mostly takes flow reactor. It may
distinguish between two mode contacts i.e., liquid phase contact and vapor phase contact. Polymer
degrades into lower molecular chains.

2.2.3.3.3 Hydrocracking
This process takes place under high pressure conditions, hydrocarbon molecules are broken into
simpler molecules such as gasoline or kerosene by addition of hydrogen molecules in presence of
catalyst. This process takes normally in batch autoclave at moderate temperatures and pressure
such as 423-673 k and 3-10 Mpa hydrogen. Hydrocracking gives higher yield of products and
higher quality from a wide range of feeds. Catalysts used are Pt, Ni, Mo, Fe supported on acid
solids.
2.2.4 Quaternary recycling
Quaternary recycling is the process involves recovery of the energy content of plastics. This
method undergoes combustion process for the recovery of energy which is most effective method
for reduction of volume of organic material. This may then dispose to landfill. Plastics either
thermoplastics or thermoset actually yield high energy sources.

2.3 Pyrolysis of LDPE

LDPE pyrolysis have been studied by many researchers for degradation of waste plastic into
different products like liquid, gas and solid change depending on various factors such as catalyst,
temperature, pressure, nature of reaction, type of reactor used.

2.3.1 Thermal and catalytic pyrolysis

The type on reactor and the effect of temperature on the pyrolysis of LDPE have been studied and
results are revised. Previous works are done on the conversion of waste LDPE into useful products
such as liquid fuel and further separated into diesel and carbon compounds which have high
calorific value. The material is mainly industrial and domestic area. Thermal Pyrolysis is the
process involves the degradation of the polymeric material by heating on the absence of oxygen.
It is the process in which breakage of higher molecular weight compounds into lower molecular
compounds. Thermal pyrolysis is the process in which heated up to higher degree temperatures
and polymeric materials converted into lower molecular compounds.

Procedure: some amount of waste plastic is heated in reactor and the reactor is placed inside the
furnace. The heated material is converted into gases from 450 to 650’c and different yields of gases
products are obtained. The gaseous product is then condensed into liquid products and gaseous
products. The maximum yield of liquid product is at 550.c. The catalytic pyrolysis involved with
different ratios of catalyst to feed involved for increasing the yield of liquid product. Compositions
of liquid product are done by FTIR spectroscopy and gas chromatography- mass spectroscopy.
The composition of liquid products are alkanes, alkenes and different carbon compounds.

2.4. Mechanics and kinetics of pyrolysis

Degradation of polymers usually taken different on the basis of the carried-out reaction: thermal
degradation, thermos catalytic degradation, oxidative degradation, heat and oxygen, radiation and
photoxidative degradation and chemical degradation. This type of reaction are irreversible
reactions and changes of structure are irreversible. As the major waste plastics are polyethylene
and polypropylene so experiments carried only on these plastics. The decomposition of plastic
results in decreasing of molecular weight and physical changes caused. Chemical reactions and
recycling are two different methods caused by the chemicals.

The kinetics and mechanism of these reactions have been studied by different techniques.

2.4.1 Investigative methods for polymer degradation

Three extreme categories of pyrolysis behavior have been carried over and each is different
investigation;

1) Cross linking or other reactions in the polymer leading to the formation of Infusible resins, or
maybe coke/char precursors.

2) Chain scissions and other processes leading to decrease in the typical molecular weight with the
sample.

3) Your formation of major yields of little molecular weight materials, which may be monomeric,
oligomeric, or that might originate from substituents on the chain backbone.

2.4.2 Reactions mechanism of polymer degradation

Reactions takes place by cracking of c-c bonds that is done by thermal and catalytic effects of
thermos degradation. Thermal and catalytic reactions are not separate from each other therefore in
discussing thermos catalytic process which touches both the thermal and catalytic process.
Thermal cracking occurs by radial mechanism by initiating radicals are formed by effect of heat.
Instability of the macromolecules is due to its presence of weak links of polymer.
FIGURE 2.3 Reaction mechanism of polymer degradation.

2.4.3 Reaction kinetics of polymer degradation

Decomposition reactions are the degradation which is quite difficult due to its complex in chemical
structure. Difference is present in the thermal degradation of waste plastic in absence and presence
of catalyst, but type of reactor is also important. Degradation in presence of catalyst is thermo-
catalytic degradation. Cracking takes place in batch reactors which results 95% degradation studies
(Seo YH et al. 2003, Miskolczi N et al. 2004, Kim JS et al. 2003, Masuda T et al. 1999, Uddin MA
et al. 1997, Seddegi ZS et al. 2002, Sakata Y et al. 1997, Grieken RV et al. 2001, Jalil PA 2002,
Hwang EY et al. 2002) connected with different techniques for e.g., TG, DTG. TG-MS etc. some
kinetic models for thermal degradation were proposed and commonly used approach is first order
kinetics for investigating degradation. Different objectives have been proposed for determination
of activation energy and kinetic parameters.

2.5 Performance and emission analysis of waste plastics oil in CI engine

Many researchers have been worked and proposed that properties of waste plastic oil had
comparable properties with the used fuel in compression ignition engines. Results shown with
mixed heavy oils with plastic oils reduces the viscosity significantly and improves performance of
the engine. Mani et al. studied about the plastic oil in DI engine and studied the performance,
emission and combustion characteristics of single cylinder, four stroke, air cooled DI diesel engine.
With this oil shows stable performance with thermal brake efficiency similar to that diesel. Due to
its carbon monoxide emission from waste plastic oil was higher compared to diesel and smoke
reduced by 40-50% in waste plastic oil.

2.6 Design of reactor

Reactor design for the mixed flow reactor: Here the procedure is a molar feed A is sent into the
mixed flow reactor and waited till reaction occurs and then output product is taken out. The
performance equation for the mixed are obtained which makes an accounting makes an accounting
of a given component within an element of volume throughout. Taking equation,

Input = output + disappearance by reaction + accumulation

As the accumulation taken as zero and molar feed rate of component are considered. Then
considering the reactor design equation are

Where t = residence time. V= volume of reactor.

v= volume flow rate of a.

𝑐𝑎0= intial concentration of A.

𝑐𝑎=final concentration of A.

𝑟𝑎= rate of reaction.

𝑋𝑎= conversion of A.
 CHAPTER THREE

PROCESS DESCRIPTION AND FLOW DIAGRAM

3.1 Feed stock for the plant
Raw Materials are collected are waste plastic (low density polyethylene) collected for municipal
waste or the industrial waste. The waste plastics collected are collected mainly LDPE in the form
plastic disposal glasses or etc. Skilled Labor are allotted for the collecting only LDPE based on
their daily wage. Different kinds of waste plastic (LDPE) are such as plastic bags, laptop covers
and normal domestic used plastic which are of lighter density. Most of the raw material is occurred
from industries are of less contaminants mixed rather than the domestic use.

3.1.1 Preparation of feedstock

Feed stocks collected are either manually or through automatically cut into small pieces with the
equipment. This was done to increase the surface area of contact during melting process. Labor is
allotted to do this process according to the daily basis.

3.2 Flow diagram for the plant

3.2.1 Design layout of plant

Figure 3. 1: Simple Plant Layout

3.2.2. Schematic Diagram of the Plant

Figure 3. 2: Process diagram of the plant

3.3. Description of the procedure

Raw material (LDPE) obtained are first cut into smaller pieces and then entered into the jacketed
vessel at room temperature (32°c) and then heated to around 115°c which is melting point of the
LDPE. The LDPE are converted into liquid form at 115°c and then passed into the continuous
stirred flow reactor and the reaction takes place at optimum temperature 550°c at which the yield
is maximum. Product obtained from the reactor is gaseous product which then sent back to the
vessel jacket and then gaseous product at 550°c are condensed to liquid and gaseous product. The
liquid produced is of 5 tons/day and the gaseous product is sent back and used for heating purpose
for the reactor.

Reactants = solid product + liquid product + gaseous product at 550°c.

Figure 3. 3: The Process Flowsheet
Figure 3. 4: Simulated 3D View 1

Figure 3. 5: Simulated 3D view 2

Figure 3. 6: Aspen Hysys snapshot of the process
 CHAPTER FOUR

MATERIAL AND ENERGY BALANCE

Figure 4. 1: Block diagram for overall mass balance

MASS BALANCE: -

Raw materials of the waste plastic (LDPE) = Solid product + Liquid product + Gaseous product.
For finding the raw material of the waste plastic (LDPE) which is calculated. From the Table 4.1,
maximum yield of liquid product produced at 550°c which is an optimum temperature.

Mass balance: -

Converting Liters/day to tons/day for easier calculative figures

Input: - Mass of the raw materials = 6.48 tons/day.

Output: - Mass of the solid product = 0.108 tons/day.

Mass of the gaseous product = 1.37 tons/day.

Mass of the liquid product = 5 tons/day.

Total output = 6.478tons/day.

TABLE 4.1 Liquid product produced at different temperatures.

Thermal Weight of liquid Weight of solid Weight of Total time for

Pyrolysis of 15 products products gaseous obtained thermal
grams of LDPE obtained (grams obtained (grams) by pyrolysis(mins)
sample AT ) difference(grams)
following
temp(c)

475 7.1 0.2 7.7 146

500 9.48 0.15 5.37 80

525 10.48 0.37 4.15 65

550 11.56 0.25 3.19 57

575 11.3 0.09 3.61 41

600 10.12 0.55 4.33 37

Figure 4. 2: Observations of liquid product at different temperatures.

Rate of accumulation is zero because it is a steady state and output is equal to the input and mass
is balanced.

TABLE 4.2 properties of LDPE and Liquid product.

Property Low density Liquid fuel (Product)

Polyethylene (LDPE)
Thermal 0.33 0.15

conductivity(k) ( 𝑊 )
𝑚∗𝐾

Viscosity(𝜇) 3.97*10−4 3.97*10−4

Specific heat (𝐶 ) ( 𝐽 ) 2000 1750

𝑝 𝐾𝑔.𝐾

Density (kg/m^3) 940 832

HEAT BALANCE: -

Figure 4. 3: Block diagram for overall heat balance

Heat input by raw materials (Q1) = m1*𝐶𝑝1*T1 = 6.48*1000*2000*305/24*3600 = 45750J/s.

Where 𝐶𝑝1= Specific heat of raw materials.

T1= temperature of the raw material at input. m1= mass flow rate of raw materials.

Heat output by liquid product (Q2) = m2*𝐶𝑝2*T1 = 5*1000*1750*648/24*3600 = 65625J/s

Where 𝐶𝑝 = specific heat of liquid product.
T2 = temperature of the liquid product.

m2 = mass flow rate of liquid product.

Above block diagram indicates that input heat and output heat balance equation at steady state and
output involves three products but due to unknown composition and properties of liquid and gases
and hence neglected.

External heat (Q) = Q2-Q1 = 65625-45750 = 19875J/s.

4.2. Mass and Heat balance in Reactor

Figure 4. 4: Block diagram for Reactor mass balance

Mass Balance: -

Input: - Mass of the raw materials = 6.48 tons/day.

Output: - Mass of the solid product = 0.108 tons/day.

Mass of the gaseous product = 1.37 tons/day.

Mass of the liquid product = 5 tons/day.

Total output = 6.478tons/day.

Rate of accumulation is zero because it is a steady state and output is equal to the input and mass
is balanced.
Figure 4. 5: Block diagram for Reactor heat balance

Heat Balance: -

Input heat: -

Heat required inside the reactor (Q1) = m1*𝐶𝑝1*T1 = 6.48*1000*2220*388/ (24*3600) =

64602W

Heat from the output of the reactor (Q2) = m2*𝐶𝑝2*T2 = 5*1000*1750*823/ (24*3600) =
83347.8W

Heat given from outside (Q) = Q2-Q1 = 18745.8W.

Reactor is processed at steady state and heat is balanced equating the input and output and the heat
given from outside of the reactor is 18745.8W.

4.3 Mass and Heat balance in Jacketed Vessel

Figure 4. 6: Block diagram for Vessel mass balance

Mass Balance: -

Input: - Mass of the raw materials = 6.48tons. Mass of the liquid product = 5tons. Total input =
6.48 + 5 =11.48tons.
Output: - Mass of the raw materials = 6.48tons.

Mass of the liquid product = 5tons.

Total Output = 6.48 + 5 =11.48tons.

Rate of accumulation is zero because it is a steady state and output is equal to the input and mass
is balanced and using heat balances and solved the temperatures below.

HEAT BALANCE:

Figure 4. 7: Block diagram for vessel heat balance

Using heat balance for the jacketed vessel,

a) Determination of temperature of the product released from vessel.

Temperature is obtained from the vessel using heat balances of the vessel. Input heat contains two
forms of heat one by latent heat another by sensible heat due to changing of phase of raw material.
In the jacket, only sensible heat is considered because no change in phase.

Heat supplied for input = m1*(𝑐𝑝1 ∗ (𝑇2 − 𝑇1) + 𝛾) Heat released through output= m2*(𝑐𝑝2 ∗ (𝑇4
− 𝑇3))

Required information is

m1= mass flow rate of raw materials. = 6.48 tons per day.

m2= mass flow rate of products. = 5 tons per day.

𝑐𝑝1= specific heat of plastic. = 2300 J/kg.K

𝑐𝑝2 = specific heat of liquid fuel = 2220 J/kg K

𝛾 = heat of fusion = 26 kcal/ kg K

T1= heat of raw material at inlet. = 32’c

T2= heat of raw material at output. = 115’c

T3= heat of liquid fuel at inlet. = 550

T4 = heat of liquid fuel at outlet

Considering the heat balance for the vessel and finding out the outlet temperature.

m1*(𝑐𝑝1 ∗ (𝑇2 − 𝑇1) + 𝛾) = m2*(𝑐𝑝2 ∗ (𝑇3 − 𝑇4))

6.48* (2300*(115-32) + 26*4.186*1000) = 5 *(2220*(550- T4))

We get the value of T3 is 375.014°c.

 CHAPTER FIVE
DESIGN AND SPECIFICATION OF UNIT PROCESS
5.1. Design of the reactor
Reactants → solid product + liquid product + gaseous product.

a) For raw material needed: -

we get 11.56g of liquid product from the 15 g of the raw material.

For 5 tons per day liquid product, we need

Raw materials required are 6.48 tons/ day of waste plastic (low density polyethylene).

b) For reactor volume: -

Residence time of the reaction is fount out to be 57 min from the research project. Using the
equation

Where VR = volume of the reactor,

Vo = volumetric flow rate of raw materials for calculating the volumetric flow rate,

Mass flow of the raw materials (𝑚𝑜) = 6.48 tons /day

= 4.5 kg / min (1ton = 1000 kg and 1day = 1440 min)

Density of the low-density polyethylene (d) = 0.94 g/cm3

= 940 kg/m3
Volumetric flow rate = 4.5/940 = 0.00478 m3/s.

Volume of the reactor = 57 * 0.00478 = 0.272 m3.

= 272 liters

The volume of the reactor is found to be 272 liters but due to presence of gases during heating in
the reactor. So, volume of the reactor is to be considered more than the actual volume needed. The
volume reactor is found out to be double the actual volume.

Volume of the reactor = 2* 272 liters = 544 liters = 0.544 m3.

c) Optimum diameter and length of the reactor.

Using optimum conditions, calculating surface area

Where D = Diameter of the reactor,

L = length of the reactor,

A = Surface area,

V = Volume of the reactor

By differentiating the function of the diameter, we get

For calculating the diameter reactor, we get

𝐷 = (4 ∗ 0.544/𝑝𝑖)1/3= 0.884𝑚3,

For calculating the length of the reactor, we get

𝐿 = (4 ∗ 0.544/𝑝𝑖)1/3= 0.884𝑚3

The length and diameter of the reactor obtained to be 0.884𝑚3.

5.1.1 Material of construction for the reactor

The reactor is constructed with stainless steel material which has diameter and the length are
obtained to be 0.884𝑚. stainless steel – GRADE 304(UNS S30400). Stainless Steel is used because
of its property’s high tensile strength, highly resistant towards oxides, acids, bases and organic
compounds.

5.2 Design of jacketed vessel

Two process takes places in the vessel primary one is the melting of LDPE into liquid by supplying
heat at 115’c from 32’c. Secondary is the cooling process which is obtained from the reactor at
550’c. Initially heating is supplied through the outside for heating of raw material for easy flow
into the reactor.

5.2.1 Determination of length, diameter and volume for jacketed vessel

a) Calculation of inner individual heat transfer coefficient.

Heat transfer takes place with phase change into liquid phase and form a film type condensation.
The resistance to the flow of heat is that offered by the layer of condensate flowing downward in
laminar flow under the action of gravity. For calculating the inner individual heat transfer
coefficient,
Where 𝑘𝑓 = thermal conductivity of the fluid,

𝑑𝑓 = density of the fluid,

𝜇 = viscosity of the fluid,

g = gravity due to acceleration = 9.8m/s^2,

Re = Reynolds number = (4∗𝑚/ 𝜋∗𝐷∗𝜇),

ℎ𝑖 = individual heat transfer coefficient, M =mass flow rate of the raw materials, D = inner diameter
of the jacketed vessel,

Taking diameter as D = 4m, calculating Reynolds number

b) Calculating the outer individual heat transfer coefficient.

Heat transfer takes places without phase change and fluid contains is the liquid product. Heat
transfer takes place by convection without the phase change and flow is laminar flow. For
calculating the outer individual heat transfer coefficient,
𝜇𝑓= viscosity of the fluid,

ℎ𝑜 = outside individual heat transfer coefficient.

Taking Reynold number (1000) and calculating the equivalent diameter,

 b) Calculating the overall heat transfer coefficient (Ui)

For calculating the overall heat transfer coefficient, overall heat transfer involves heat transfer
inside the vessel, heat transfer outside the vessel and the heat transfer through the wall by
conduction. Here the heat transfer involved by both conduction and convection and heat transfer
through conduction is negligible because of lower thickness and high conductivity and taking the
last coefficient of the equation below = 0.
∆𝑡 = thickness of the outer side,

Now for calculating the overall heat transfer coefficient.

∆𝑇1= 375-32 = 343’K,

∆𝑇2= 550-115 = 435’K,

𝑈𝑖 ∗ 𝐴𝑖 = 58.067,

𝑈𝑖 ∗ 𝐿 = 2.31------------------------------------------------- (4)

From equating 1, 2, 3 and 4 and we found that value of L is 4m and the thickness is found to be ∆𝑡
= 0.116 from the equation 1 and the outer diameter is found to be 4.226m.

5.2.2 Material of construction for the jacketed vessel

The reactor is constructed with stainless steel material which has inner diameter and the length are
obtained to be 4m and the outer diameter is 4.226m. Stainless steel – GRADE 304(UNS S30400).
Stainless Steel is used because of its property’s high tensile strength, highly resistant towards
oxides, acids, bases and organic compounds.

5.3 Nominal pipe sizes

By calculating the velocity of liquid flown we can calculate sizes of the pipe by Hagen Poiseuille
equation, i.e.

Where 𝜇 = viscosity of the liquid,

∆𝑝 = pressure difference between the pipe, L= length of the pipe,

Q volumetric flow rate,

From the table of the nominal pipe size, the value of pipe size is found out to be ¾” (inches).
 CHAPTER SIX

ECONOMIC ANALYSIS
6.1 Cost estimation of the plant
Cost estimation is calculated from considering only input raw material and the output raw material.
The input raw material obtained can be calculated either by giving daily labor wage or from
purchasing from the recycling industries. Output cost involves are only the price of the liquid fuel
and there is deduction of initial heat supplied to the equipment for heating.

COST OF INPUT MATERIALS: -

Cost of the raw materials = Rs.15/Kg.

Total amount of raw materials = 6.48 tons/day = 6480Kg/day.

Total cost of the raw materials = 6480*15 = Rs.97200/day.

Assuming working days =340 days.

Total cost of the raw materials per annum = 97200*340 = Rs.33048000 = $ 517750.27 (1$=
Rs.63.83).

COST OF OUTPUT MATERIALS: -

Cost of the liquid product = Rs.35/Kg.

Total amount of liquid product = 5tons/day = 5000Kg/day.

Total cost of the liquid product = 5000*35 = Rs.175000/day.

Total cost of the liquid product per annum = 175000*340 = Rs.59500000 = $932.163.55.

COST OF WORKERS: -

Workers involved are 4 unskilled and 2 skilled workers and the cost of the workers are involved.
Cost of the workers per day = 4*200 + 2*240 = Rs.1280/day.

Cost of the workers per annum = 1280*365 = Rs.467200 per annum. = $7319.44 per annum.
ESTIMATION OF THE CAPTIAL INVESTMNET: -

For estimation of the cost of the capital investment, the method of percentage pf delivered
equipment cost is involved. For calculating the

cost of the equipment and first we have to calculate the surface area and cost of both the jacketed
vessel and the reactor.

Surface area of the reactor = 𝜋*(𝐷2+D*L) = 𝜋 ∗ ((0.884)2 + 0.884 ∗ 0.884) = 4.91𝑚2.

Surface area of the jacketed vessel = 𝜋*Di*L+𝜋*𝐷𝑖2+2*(L*∆𝑡) =

3.14*4*4+3.14*16+2*(0.113*4) = 101.43𝑚2.

Cost of stainless steel for 5mm of thickness = $38.297/𝑚2.

Total cost of material of the equipment = 38.297*(101.43+4.91) = $4027.5.

Total cost of equipment including the making cost = 1.3 *4027.5 = $5235.75. (Assuming the
making cost is 30%).

Total fixed cost is obtained from both the direct cost and the indirect cost. Now calculating the
fixed capital investment by the percentage equipment cost we get

TABLE 6.1 Determination of fixed capital investment.

COMPONENTS COST ($)

Purchased equipment(delivered), E $5235.75
Purchased equipment installation,39% E 2041.94
Instrumentation(installed),28% E 1466.01
Piping(installed),31% E 1623.08
Electrical (installed),10% E 523.57
Building (including services), 22% E 1151.86
Yard improvements, 10%E 523.57
Service facilities (installed), 55% E 2879.66
Land, 6% E 314.45
Total direct plant cost D $ 15759.89
Engineering and supervision, 32% E 1657.44
 Construction expenses, 34% E 1780.15
Total direct and indirect cost (D+I) $ 19197.48
Contractor’s fee, 5%(D+I) 959.874

For installation of the plant, we should take loan in the banks at the interest of 14% and the method
is simple interest.

Total amount = $22077.102 + = $ 517750.27 = $539827.372.

For calculating the simple interest

Where P = principal amount,

R= rate of interest = 14%,

T = time period = 10 years.

Total amount paid for the year = $53982.7372 + $75575.832 = $129558.562 Insurance for every
year is (Assuming 1% per year) = $220.77.

For calculating the depreciation using straight line method, Total time = 10 years. Salvage value
=0

Depreciation cost of the equipment = (equipment cost – salvage value)/total time =5235.75-
0/10=$523.575.

Net profit involves both the direct cost, indirect cost and the other costs.

Net profit = cost of output materials – cost of input materials – insurance cost – depreciation cost-
labor cost – interest per year,
Net profit = $932163.55-$517750.27-$7319.44 -$129558.562-$523.575-$220.77 = $276790.933.

Gross profit is calculated by after paying the income taxes and the income tax percentage is 34%.
Gross profit per year = (1-0.34) *276790.933 = $182662.21= Rs.1,16,59,329.23 per year.
 CHAPTER SEVEN

PLANT LAYOUT

FIGURE 7.1. Plant design with instrumentation.

7.1 Valves
Two valves of gate valves are used because of low pressure difference. Valves are used for control
the flow of the liquid and the gases product obtained. Gate are generally used during straight line
flow of fluids and minimum restriction. Gate are mostly used in petroleum industries because of
their ability to cut through liquids.

SPECIFICATIONS: -

Type: Gate Valve

Pipe Size (Inch): ¾

End Connections: FNPT x FNPT

Material: Brass Disc Style Solid Wedge

WOG rating (psi): 200

WSP Rating (psi) 1

Bonnet Style: Bolted Class 200

Special Item Information: Lead-Free.

7.2 Pumps and Rotameters

Pumps used are centrifugal pumps which are used to lift upto certain height of 10m. Two pumps
are used one is pumping liquid raw material of lower temperatures and another is used for pumping
product at higher temperatures.

Pump1 Specifications:

Flow Rate (min): 1 L/min (0.26 gpm)

Flow Rate (max): 27 L/min (7.1 gpm)

Head (max): 14 Meters H2O (26 ft.)

System Pressure (max): 13.8 bar (200psi)

Viscosity Range: 0.2 to 100 cP

Weight: 0.75 lbs

Standard Ports: 3/8"-18 NPT (F) Inlet; 1/4"-18 NPT (F) Outlet

Recommended Max Speed: 10,000 RPM

Pump2 Specifications:

Ship Weight 14.0 lbs

Flow (GPH) 720

Volts 110

Amps 2.75 HP 1/2

Max. Total Head (ft.) 110

Max. Suction Lift (ft.) 20

Max. PSI 55

Suction Port (in.) 1

Discharge Port (in.) 1

Self-Priming No Pump

Housing Cast iron

Impeller Shaft Cast brass

Dimensions L x W x H (in.) 10 1/4 x 5 5/8 x 6 1/8

Rotameters used are should be in the range from 1- 10 l/min and two Rota meters are used to
measure the flow rate of the liquids. Two rotameters are used one is pumping liquid raw material
and anther is for pumping product.
 CHAPTER EIGHT

CONCLUSION
Pyrolysis of LDPE takes long enough to react and observed the yield of product at different
temperatures and found maximum yield of the product is obtained at 550°C which is 77.07%.
From the yield of the liquid product determined the number of raw materials i.e., 6.48 tons/day,
amount of liquid product i.e., 5 tons/day, amount of solid product i.e., 0.108tons/day and amount
of liquid product i.e., 1.37tons/day. Simple layout of plant and process plant design of the plant
and plant consists of different sections office, process layout and storage and process layout consist
of office, process layout and storage.

Reactor design is done using the reactor design equations and found volume to be 277 liters due
to the presence of gaseous volume is doubled i.e., 544litres. The dimensions of the reactor if found
to be 0.884m in both length and diameter using optimum conditions.

Design of jacketed vessel are designed with heat transfer inside the vessel is taken with phase
change and heat transfer outside the vessel without phase change. Calculating the individual heat
transfer coefficient of both outside and inside the vessel and heat transfer through the conduction
and solved by different iterations and found the inner diameter i.e., 4m and outer diameter i.e.,
4.226 and length found to be 4m.

Cost estimation is done using the method of percentage of equipment delivered by initially
calculating the surface area and taking thickness of 5mm and found total cost of equipment

$5235.75 and found the fixed capital investment to be $22077.102. Net profit is calculated by
taking all the loan cost, deprecation cost, labor cost and input materials and insurance i.e.

$276790.933 per year and gross profit found after paying taxes which is 34% i.e.,
Rs.1,16,59,329.23 per year ($182662.21)
 REFERENCES
1) Achilias, D. S., Roupakias, C., Megalokonomos, P., Lappas, A. A., & Antonakou, Ε. V.
(2007). Chemical recycling of plastic wastes made from polyethylene (LDPE and HDPE) and
polypropylene (PP). Journal of Hazardous Materials, 149(3), 536-542.

2) Akao, M. (1989). U.S. Patent No. 4,844,961. Washington, DC: U.S. Patent and Trademark
Office.

3) Lee, K. H., Noh, N. S., Shin, D. H., & Seo, Y. (2002). Comparison of plastic types for
catalytic degradation of waste plastics into liquid product with spent FCC catalyst. Polymer
Degradation and Stability, 78(3), 539-544.

4) Panda, A. K., Singh, R. K., & Mishra, D. K. (2010). Thermolysis of waste plastics to liquid
fuel: A suitable method for plastic waste management and manufacture of value added products—
A world prospective. Renewable and Sustainable Energy Reviews, 14(1), 233-248.

5) Peacock, A. (2000). Handbook of polyethylene: structures: properties, and applications.

CRC Press.

6) Peckner, D., & Bernstein, I. M. (1977). Handbook of stainless steels (pp. 19-3). New York,
NY: McGraw-Hill.

7) Popper, H. (1970). Modern cost-engineering techniques: an economic-analysis and cost-

estimation manual, with comprehensive data on plant and equipment costs in the process
industries. McGraw-Hill.

8) Scheirs, J., & Kaminsky, W. (Eds.). (2006). Feedstock recycling and pyrolysis of waste
plastics. John Wiley & Sons.

9) Scotp, D. S., Majerski, P., Piskorz, J., Radlein, D., & Barnickel, M. (1999). Production of
liquid fuels from waste plastics. The Canadian journal of chemical engineering, 77(5), 1021-1027.

10) Uddin, M. A., Koizumi, K., Murata, K., & Sakata, Y. (1997). Thermal and catalytic
degradation of structurally different types of polyethylene into fuel oil.Polymer degradation and
stability, 56(1), 37-44.
11) Timmerhaus, K. D., Peters, M. S., & West, R. E. (1991). Plant design and economics for
chemical engineers. Chemical Engineering Series.

12) Mani, M., Subash, C., & Nagarajan, G. (2009). Performance, emission and combustion
characteristics of a DI diesel engine using waste plastic oil.Applied Thermal Engineering, 29(13),
2738-2744.

13) https://en.wikipedia.org/wiki/Low-density_polyethylene.

14) http://www.plasticmoulding.ca/polymers/polyethylene.htm.

15) http://www.engineeringtoolbox.com/specific-heat-fluids-d_151.html