Efficient use of "waste plastic" by rajat yadav

8/10/2019 Efficient use of "waste plastic" by rajat yadav

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Chapter 1

_______________________________________ INTRODUCTION

1.1 Introduction

For many years, various methods are tried and tested for

processing of waste plastic. The plastic materials are recycled

and low value products are prepared. Plastic materials which

cannot be recycled are usually dumped into undesirable landfill.

Worldwide almost 20% of the waste stream is plastic, most of

which still ends up in landfill or at worst it is incinerated.

This is a terrible waste of a valuable resource containing a high

level of latent energy, in recent year this practice has become

less and less desirable due to opposition from Government and

environmentally conscious community groups. The value of plastics

going to landfill is showing a marginal reduction despite

extensive community awareness and education programs. Research

Centre for Carbon components Generation (RCFG) has conducted 300

successful pilot trials and commercial trials for conversion of

waste plastic materials into high grade industrial carbonaceous

materials. The system uses liquefaction, pyrolysis and the

catalytic breakdown of plastic materials and conversion into

industrial carbonaseous materials. The system can handle the

majority of plastic materials that are currently being sent to

landfill or which have a low recycle value. Catalytic conversion

of waste plastic into high value product is a superior method of

reusing this valuable resource. Economic growth and changing

consumption and production patterns are resulting into rapid

increase in generation of waste plastics in the world. In Asia

and the Pacific, as well as many other developing regions,

plastic consumption has increased much more than the world

average due to rapid urbanization and economic development, this

implies that on one hand more resources are being used to meet

the increased demand of plastic, and on the other hand, moreplastic waste is being generated due to the increase in


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generation, waste plastics are becoming a major stream in solid

waste. After food waste and paper waste, plastic waste is the

major constitute of municipal and industrial waste in cities.

Even the cities with low economic growth have started producing

more plastic waste due to plastic packaging, plastic shopping

bags, PET bottles and other goods/appliances using plastic as the

major component. This increase has turned into a major challenge

for local authorities, responsible for solid waste management and

sanitation. Due to lack of integrated solid waste management,

most of the plastic waste is neither collected properly nor

disposed of in appropriate manner to avoid its negative impacts

on environment and public health and waste plastics are causing

littering and chocking of sewage systems. On the other hand,

plastic waste recycling can provide an opportunity to collect and

dispose of plastic waste in the most environmental friendly way

and it can be converted into a resource. In most of the

situations, plastic waste recycling could also be economically

viable, as it generates resources, which are in high demand. To

raise the awareness and to build the capacity of localstakeholders, UNEP has started to promote Integrated Solid Waste

Management (ISWM) system based on 3R (reduce, reuse and recycle)

principle. This covers all the waste streams and all the stages

of waste management chain, viz.: source segregation, collection

and transportation, treatment and material/energy recovery and

final disposal. It has been shown that with appropriate

segregation and recycling system significant quantity of waste

can be diverted from landfills and converted into resource. As

plastics are mass produced and inexpensive, they are readily

discarded thereby creating a vast solid waste and pollution

issue, contaminating land and coastal waters. Recycling efforts

in past years have attempted to alleviate this problem, but as

recycled plastics are generally devalued products the economics

of this practice do not always work out. Although the recycling

rate in the U.S. went from approximately 6% to 33% of all


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municipal solid waste (MSW) over the past 50 years, a further

increase of recycling is not only desirable but, rather essential

due to continuously decreasing landfill space available. However,

it has been limited by a dramatic slump of the recycling market

with the recent global economic downturn. For instance, prices of

used plastic bottles have been falling from 25 cent/lb to 2

cent/lb over the last years. This threatens to erode the

recycling markets, the associated infrastructure and, perhaps

eventually, the publics mindset for recycling. Therefore,

creation of a new market for recycled plastics, particularly

leading to high value products, would be beneficial. Generating

high-end value products, such as combustion-generated-carbon-

nanofibers (CGCF), specifically, carbon nanotubes (CNT) and

carbon nanofibers (CNF) , from recycled waste plastics may reverse

this trend and restore, even enhance, the motives for recycling.

The major barrier to the industrial application of either CNT or

CNF, on the other hand, lies on the cost of their carbonaceous

precursors. Even those facilities with large-scale production

ability, two decades after the discovery of CNT, still have torely on large volume, high-purity light hydrocarbons as carbon

source, such as methane, ethane, ethylene, etc. However, such

chemicals are of high demand by many diverse industries and are,

thus costly. Considering their high carbon and hydrogen content,

as well as their high energy content, waste plastics present a

distinct alternative to the aforementioned carbon sources. The

use of such relatively inexpensive feedstock for the manufacture

of well-defined CGCF, could lower prices of nanostructured

carbonaceous materials and accelerate their large scale use in an

increasing number of commercial products, such as batteries or

composites. This work utilized waste polyethylene (PE) as a

feedstock. Other waste plastics are currently being examined.

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Chapter 2

__________________________PRODUCTS TO BE MANUFACTURED

2.1 Products generated

Following products shall be manufactured from waste plastic

1) Crude oil

2) Petroleum Gases

3) Activated carbon

4) Carbon nano tubes

2.2 Market Potential

There is great market potential for these carbon componentss,

as these can be sold at about 25% less prices. The potential

buyers shall be as under:

1) Industries having Boilers.

2) Industries having electric generators.

3) Hotels and Resorts having electric generators and dieselstoves.

4) Construction companies having heavy machinery.

5) Farmers using diesel pumps.

6) Indian Oil Corporation

7) Bharat Petroleum

8) Hindustan Petroleum

9) Indian Railways

10) Shops having electric generators

11) Domestic people having electric generators

12) Establishments having electric generators


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13) State transport corporations

14) Local / City transports corporations

15) Logistics companies.

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Chapter 3

__________________ _ RAW MATERIALS

3.1 Raw Materials to be used

The raw materials include the following:

1) Polyethylene: Buckets, drums, Chapels, sandal, bottles,

plastic parts, carry bags etc.

2) Polypropylene: Pipe fitting, filter cloths etc.

3) Polyamide: Nylon ropes

4) Polyvinyl Chloride (PVC): PVC pipes and fittings

5) Polystyrene: Cloths and fibers

6) Rubber: Tires, automobile parts

7) Polyurethane (PUR)

8) Phenol resin (PF)

9) Polyvinylidene chloride (PVDC)

3.2 Target Waste Plastics

Waste plastics are one of the most promising resources for

cabon components production because of its high heat of

combustion and due to the increasing availability in local

communities. Unlike paper and wood, plastics do not absorb

much moisture and the water content of plastics is far lower

than the water content of biomass such as crops and kitchen

wastes. The conversion methods of waste plastics into cabon

components depends on the types of plastics to be targeted and

the properties of other wastes that might be used in the


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process. Additionally the effective conversion requires

appropriate technologies to be selected according to local

economic, environmental, social and technical characteristics.

In general, the conversion of waste plastic into carbon

components requires feedstocks which are non-hazardous and

combustible. In particular each type of waste plastic

conversion method has its own suitable feedstock. The

composition of the plastics used as feedstock may be very

different and some plastic articles might contain undesirable

substances (e.g. additives such as flame-retardants containing

bromine and antimony compounds or plastics containing

nitrogen, halogens, sulfur or any other hazardous substances)

which pose potential risks to humans and to the environment.

The types of plastics and their composition will condition the

conversion process and will determine the pretreatment

requirements, the combustion temperature for the conversion

and therefore the energy consumption required, the carbon

components quality output, the flue gas composition (e.g.

formation of hazardous flue gases such as NOx and HCl), thefly ash and bottom ash composition, and the potential of

chemical corrosion of the equipment

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Standardization technical specification (CEN/TS 15359:2006).On

the other hand RPF is prepared from used paper, waste plastics

and other dry feed stocks. Within the plastics, the

thermoplastics play a key role as a binder for the other

components such as thermosetting plastics and other combustible

wastes, which cannot form pellets or briquettes without a binding

component. Approximately 15wt% of thermoplastics is the minimum

required to be used as a binder to solidify the other components;

however excessive amounts, higher than 50wt%, would cause a

failure in the pellet preparation. The components of RPFs are

mainly sorted from industrial wastes and are sometimes also

obtained from well-separated municipal waste. This type of solid

carbon components is set to be standardized in the Japanese

Industrial Standards (JIS). In both cases, the plastic contents

can be varied (within a range) to meet the needs of carbon

components users. The shape of the carbon components will vary

according to the production equipment (e.g. a screw extruder is

often used to create cylindrical-shaped carbon components with a

variable diameter and length). In the production of solid carboncomponents, the contamination of the targeted plastics with other

plastics containing nitrogen, halogens (Cl, Br, F), sulphur and

other hazardous substances may cause air and soil pollution by

the flu gas emission and the incineration ash disposal (e.g.

inorganic components such as aluminium in multilayer film of food

packages produces fly ash and bottom ash). Other contaminants

such as hydrogen chloride might cause serious damage to the

boiler by corrosion.

4.2 Production method

The solid carbon components production process usually involves

two steps, pre treatment and pellet production:

Pre treatment includes coarse shredding and removal of non-

combustible materials.


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Pellet production comprises secondary shredding and

pelletization (


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Figure 4.2.1: Schematic diagram of pretreatment process

Source: Japan RPF Association


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Figure 4.2.2: Example of pre treatment process (3 ton/h

capacity)



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After pre treatment, a suitable mixture of paper and plasticsare further processed in a secondary crusher and sorting

process (conveyor and magnetic separator) and the resulting

mixture is pelletized to produce solid carbon components. The

resulting solid carbon components is cooled in an air-cooling

system to prevent natural ignition during storage and it is

further stored for shipping. The output of the process is

usually solid carbon components pellets of dimensions between 6

to 60 mm in diameter and 10 to 100 mm in length. The heating

value of the pellets will change depending on the content of

the plastics. A mixture of paper and plastics of a 1:1 weight

ratio gives a heating value of approximately 7,000 kcal/kg or

higher. Figure 4.2.3 shows a pelletizing process and Figure

4.2.4 shows a typical pelletizing process facility with a 1

ton/h capacity.


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Figure 4.2.3: Schematic diagram of a pelletizing process



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Figure 4.2.4: Typical pelletizing process facility (1

ton/h line)



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4.2.2 Small-scale model (150 kg/hour)

This small-scale model is a system for solid carbon components

production with a 150-kg/h capacity. In this case the facilitydoes not have a pre treatment process, (as aforementioned, a

sorting process is not required if properly segregated waste canbe collected) so the combustible wood, paper and plastic waste isdirectly fed into the crusher of the facility. This is carried

out by using a handling machine as shown in Figure 4.2.2.2 wherethe operator must control and feed into the crusher a suitable

ratio of each type of waste in order to maintain the carbon

components qualities such as the heating value. After crushing the materials, they are transported through a pipe conveyor and

are introduced into a twin-screw pelletizer. Figure 4.2.2.1 showsthe entire process (the crusher, the pipe conveyor and the

pelletizer).


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Figure 4.2.2.1: Smaller RPF production facility



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Figure 4.2.2.2: Heavy duty machine to feed wastes

(150 kg/h capacity)

Figure 4.2.2.2: Heavy duty machine to feed wastes



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4.3 Product and by product

Heating value is an important characteristic of solid carbon

components. Some examples of heating values of several types of

waste and solid carbon components are listed in Table 4.3.

Table 4.3: Heating values of various carbon components

and wastes

Carbon components or waste Typical heating value

(kcal/kgRDF 4000 5000

RPF 6000 8000

Coal 6000 8000

Heavy oil 9500

Wood/paper 4300

Plastics (polyethylene) 11000

Typical municipal wastes 1000 1500

The heating values of solid RDFs and RPFs may vary depending on

the composition of the materials they contain. Especially in RDF,

fluctuations in the heating values are often observed due to

changes in the composition of the municipal waste (which is

difficult to control) and according to the degree of drying of

the municipal waste used in the production process. RPF heating

values can usually be controlled easily due to the use of dry and

sorted plastics, paper and other combustible waste, which have

been collected from companies. Other important features of the

solid carbon componentss are its content of ash, moisture and the

content of potential hazardous substances like nitrogen,

chlorine, sulfur and heavy metals. Carbon components suppliers

should have an agreement with carbon components users regardingthe solid carbon components qualities. Special attention is


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required in order to avoid self-ignition and methane evolution

during the RDF storage.

4.3.1 Carbon Nanotube Properties and Applications

Carbon nanotubes (CNT) including single-wall carbon nanotubes

(SWNT) are a category of fullerenic materials and their

increasing use in commercial products is part of the beginning

nano-technological revolution. The ability to produce CNT of

specified characteristics in large quantities and low prices is

therefore of major importance for continuous growth and

competivity of the national economy. The appealing properties of

CNT fall essentially in three categories:

4.3.1.1 Electrical: semiconducting or metallic behaviour.

4.3.1.2 Mechanical: very high tensile strength (100 steel), high

thermal stability and thermal conductivity

4.3.1.3 Chemical: extremely high surface area, biological

interface affinity. Properties of nanotubes depend in many

cases on their detailed structure. For instance, chirality

of single-wall nanotubes determines their metallic orsemi-

metallic properties. In recent years literature describing

potential applications of nanotubes has become

overwhelmingly large, major fields of interest can be

divided as follows:

a) Actuators: Conversion of electrical energy to

mechanical energy and vice versa. Potential use in

robotics, optical fiber switches and displays, prosthetic

devices etc., has been explored.

b) Sensors: Correlations between adsorption of gases such

as oxygen and conductance and thermoelectric power have

been observed.

c) Composites: Employing nanotubes as additive to polymer

composites can give improved strength performance. The


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challenge of anchoring nanotubes to polymeric structures

has been addressed by functionalizing nanotube walls.

d) Biological: Due to their physicaldimensions similar to

that of biologically active macromolecules such as

proteins, and DNA, carbon nanotubes are finding increasing

utility in biology related applications including sensors,

drug delivery, enzyme immobilization and DNA transfection.

For instance, single-wall nanotubes (SWNT) have been shown

to be ideal probe tips for atomic-force microscopy (AFM)

imaging of bio macromolecules.

e) Electronics: Significant research efforts have

investigated numerous applications taking advantage of

electronic properties. Depending on structural

characteristics, carbon nanotubes are metallic or

semiconducting. Sizes of transistors and logic devices can

be reduced significantly, e.g., a logic devices made of a

single nanotube with a transition between chiralities along

its length has been reported. The potential use of highly-

ordered carbon nanotube arrays for a variety of electronicsapplication ranging from data storage, displays, and

sensors to smaller computing devices has been described.

Commercial application of carbon nanotubes in the area of

flat panel displays (FPD) is expected in the near future.

Vertically grown arrays of nanotubes serve as field

emitters that project electrons onto phosphorescent pixels.

Prototypes of nanotube-based field emission displays (FED)

have been presented and, taking into account the 18.5

billion dollars in sales of FPD in 1999, the market

potential is significant.

f) Hydrogen storage: Single wall nanotubes are potentially

suitable for hydrogen storage systems necessary in

hydrogen-powered vehicles allowing for a reduction of the

nations dependence on foreign oil, lower greenhouse gas

emissions and the improvement of regional air quality.


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Significant hydrogen storage capacities have been observed,

but depend strongly on sample characteristics and

preparation. Other applications for CNT are in catalyst

supports, and optical limiters.

4.4 Advantages of the manufacturing process

1) Problem of disposal of waste plastic is solved.

2) Waste plastic is converted into high value carbon components.

3) Environmental pollution is controlled.

4) Industrial and automobile carbon components requirement shall

be fulfilled to some extent at lower price.

5) No pollutants are created during cracking of plastics.

6) Any type of plastic or rubber can be proceed and converted

into carbon components.

7) The crude oil and the gas can be used for generation ofelectricity.

Table 4.5: Production cost per kilograms of activated

carbon

Raw material: 80 kilograms

(carbon black as by-product)

NIL

Chemicals cost 80

Processing cost (electrical) NIL

Carbon components cost NIL

Total Production cost for 50

kilograms activated

Carbon

80

Production cost per kilograms 01.60


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5.1 SUMMARY

Based on the knowledge gained by the study the following

summary and conclusion are drawn.

Plastic wastes generated in the surroundings are used to

produce carbonaceous materials.

Plastic waste recycling can provide an opportunity to

collect and dispose of plastic waste in the most

environmental friendly way and it can be converted into a

resource

Carbon nanotube is very useful compound that is commercially

used by the industries.

This demonstration provides a sustainable solution to both

plastic waste utilization, and carbon nano materials mass

production.

5.2 CONCLUSION

This Seminar report presents all the information about

process methodology of the plant according to the equipments

individually their process condition, temperature, pressure

and operating condition all the necessary guidance for the

preparation of the report is taken from the website of the

Japan RPF association.

Although this report does not give all the technical andengineering details like optimization, simulation and

designing yet it is enough for us as we are beginner in the

industry.


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BIBLIOGRAPHY

1) http://www.jfe-steel.co.jp

2) http://www.nsc.co.jp

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http://www.nsc.co.jp/http://www.nsc.co.jp/

Efficient use of "waste plastic" by rajat yadav

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