Preliminary study on the conversion of different waste plastics into fuel oil

Table of contents

Acknowledgement

List of figures

List of tables

Abstract

Abbreviations

Overview

1. Introduction
1.1 Background
1 .2 Property of HDPE and LDPE
1.3 Sources and properties of plastic wastes

2. Literature review
2.1 Social and environmental impact of waste plastic
2.2 Plastic Waste management system
2.2.1 Recycling
2.2.2 Land filling
2.2.3 Incineration
2.2.4 Thermal cracking as a waste management option
2.3 Liquid Fuel Production
2.3.1 Thermal and catalytic recycling of waste plastic into crude oil
2.3.2 Thermal cracking
2.3.3 Catalytic cracking
2.4 Effect of major Operating Conditions
2.5 Statement of the problem
2.6 Objective

3. Methodology
3.1 Materials and chemicals needed
3.2 Experimental set up and description
3.3 Experiments

4. Result and discussion
4.1 Effect of temperature on the yield of crude oil from LDPE
4.2 Effect of temperature on crude oil from HDPE
4.3 Effect of temperature on crude oil from polystyrene

5. Product characterization
5.1 Determination of density
5.2 Determination of viscosity
5.3 Determination of flash point

6 Conclusion and Recommendation

References

List of figures

Fig 1: Structure of polymer

Fig 2: Equipment set up of the thermal degradation of the waste plastic

Fig 3: Effect of temperature on the residue and gas produced for LDPE

Fig 4: Effect of temperature on the amount of oil produced from LDPE

Fig 5: effect of temperature on the production of crude oil from HDPE

Fig 6: temperature effect on the distribution of residue and gas produced

Fig 7: Effect of temperature on crude oil production from polystyrene

Fig 8: Temperature effect on the residue left and gas produced

Fig 9: hydrometer set up

Fig 10: vesco-meter

Fig 11: flash point set up.

List of tables

Table1: properties of HDPE and LDPE

Table2: plastic types with their corresponding common uses

Table 3: plastic types and health effects

Table 4: Polymer as feed stock for fuel production

Table 5: Factors affecting product distribution

Table 6: product distribution of the different fraction at different temperature for LDPE

Table7: product distribution of the different fraction at different temperature for HDPE

Table 8: product distribution of the different fraction at different temperature for polystyrene

Table 9: Standard parameters of diesel oil obtained from petroleum

Table10: Temperature correction of hydrometer

Abstract

Waste plastics are the most commonly known types of waste discharged to water bodies and land which in turn causes series environmental pollution. Most plastic wastes are either of the following type; polypropylene, low density polyethylene, high density polyethylene, polystyrene.

Plastic are those substances which can take long periods of time to decompose if disposed off simply to the environment. Therefore, waste plastic should be changed into usable resources.

There are a number of methods by which plastic wastes can be managed such as incineration, recycling, land filling, and thermal cracking. But this thesis work focus on thermal cracking of waste plastic to change them into usable resources, because in this method there is almost no emission of hazardous gases to the environment. This means we can change all the waste in to useful resources. But the other methods are with some undesirable effects. The different waste plastics were thermally cracked at different temperature and then it was tried to measure the residue left after the reaction is completed, the gas produced, and the oil produced. Then it was compared that which types of plastics can yield higher amount of oil. Finally, some of the basic properties of crude oil produced were characterized and compared with the diesel oil obtained from the petroleum refinery.

Key words: waste plastic, waste management system, thermal cracking, characterization

Abbreviations

illustration not visible in this excerpt

Overview

The first chapter of the thesis work is about the introduction of waste plastic including the background of the waste plastic, short summary of the plastics, some common uses, and sources of plastic wastes.

Chapter two is dealing with literature review. In the literature review we can see the plastic waste management system, challenges of waste plastic management systems, how the liquid oil production is achieved, thermal cracking of the waste plastic, and effects of major operating parameters.

Chapter three shows the detail explanation of the methodologies used to achieve the final goal of the thesis. In this chapter it was tried to explain more on the materials and the chemical used for the thesis, the experimental set up, and the process description of the laboratory work.

Chapter four deals with the results and discussion of the experiments Conducted. In this chapter the effect of temperature on the yield of crude oil obtained from different waste plastic had been shown on the graph.

Chapter five deals with the characterization of the produced oil including the density, viscosity, and flash point. Finally, values of parameters determined for crude oil produced from waste plastics were compared with standard petroleum diesel oil.

The final chapter deals with the recommendation and conclusion of the work accomplished.

1. Introduction

1.1 Background

Plastic waste is regarded as a potentially cheap source of chemicals and energy. Lots of us have encountered a variety of products that use plastic materials today. As a result of the increasing level of private consumption of these plastic materials huge amount of wastes are discharged to the environment. Plastic materials are a type of material that cannot be decomposed easily in a short period of time. Substantial quantities of plastic have accumulated in the natural environment and in landfills. Those wastes can be classified as industrial and municipal according to their origins; these groups have different qualities and properties and are subjected to different management strategies [1]. Huge amounts of plastic wastes arise as a by-product or defective product in industry and agriculture. The main components of municipal solid waste (MSW) are food waste, wood, paper, cardboard, plastics, rubbers, fabrics, and metals. On the other words, more than half of the municipal solid waste components are organic species mainly thermoplastics, which can be used as energy sources. The traditional MSW disposal method is landfill. Because of the longevity of plastics, disposal to landfill may simply be storing problems for the future. For example, plasticizers and other additive chemicals have been shown to leach from landfills. The extent of this varies according to conditions, particularly pH and organic content. Recently, the conception of energy recovery from MSW has been a very hot topic. It is also undesirable to dispose of waste plastics by landfill due to poor biodegradability. An alternative strategy is that of chemical recycling, known as feedstock recycling or tertiary recycling, which has attracted much interest recently with the aim of converting waste plastics into basic petrochemicals to be used as chemical feedstock or fuels for a variety of downstream processes.

The two main chemical recycling routes are the thermal and catalytic degradation of waste plastics. The pyrolysis or thermal cracking of waste plastics is the thermal decomposition in the absence of oxygen and is carried out in vessels. Rapid urbanization and industrial diversification has led to generation of considerable quantities of municipal plastic waste. Improper disposal of waste often results in causing diseases and contamination of water bodies and soil. The impacts of this waste on the economy cannot be ignored and managing them has become a major problem. Used plastic often gets mixed with municipal solid waste reduces the composting efficiency by decreasing water permeability as well as air circulation. Plastics pose unique problem in municipal solid waste management due to the considerable amount of time required for degradation.

Plastics are synthetic organic materials produced by polymerization process. They are typically of high molecular mass, and may contain other substances like nitrogen, sulfur and chlorine besides polymers to improve performance and/or reduce costs [2]. These polymers are made of a series of repeating units known as monomers. Linear polymers (a single linear chain of monomers) and branched polymers (linear with side chains) are thermoplastic that is they soften when heated. Cross-linked polymers (two or more chains joined by side chains) are thermosetting, that is, they harden when heated.

illustration not visible in this excerpt

Linear polymer branched polymer cross linked polymer

Fig 1: Structure of polymer

There are two main types of plastics: thermoplastics and thermosetting polymers [3].

Thermoplastics can repeatedly soften and melt if enough heat is applied and hardened on cooling, so that they can be made into new plastics products. Thermoplastics make up 80% of the plastics produced today.

1 .2 Property of HDPE and LDPE

illustration not visible in this excerpt

Table1: properties of HDPE and LDPE

Table2: plastic types with their corresponding common uses

illustration not visible in this excerpt

In general there are about 50 different groups of plastics, with hundreds of different varieties. All types of plastic are recyclable. Before recycling, plastics are sorted according to their resin identification. The type of plastics and their most common uses are given in table 1:

Thermosets make up the remaining 20% of plastics produced. They are hardened by curing and cannot be re-melted or re-molded. Many of our favorite products and containers are made from plastic. However, when we throw these plastics away they can often build up and cause some harmful effects. Most negative effects associated with plastic waste come from chemicals that leach from the plastic into the environment. Plastic has the potential to transfer toxic substances to the food chain if ingested.

Table 3: plastic types and health effects

illustration not visible in this excerpt

Utilization of waste plastic is an effort to suppress the plastic waste to minimum and within specified limits. Among the alternative available waste management options are source reduction, reuse, recycle and recovery of inherent energy value through waste-to- energy incineration and processed fuel application, production of liquid fuel would be a better alternative as the caloric value of plastic is comparable to that of fossil fuel [4].

1.3 Sources and properties of plastic wastes

Plastic wastes can be classified as industrial and municipal plastic wastes according to their origins; these groups have different qualities and properties and are subjected to different management strategies. Plastic wastes represent a considerable part of municipal wastes; furthermore a huge amount of plastic waste arises as a byproduct or defected product in industry. Of the total plastic waste, large amounts corresponds to thermoplastics and the remaining to thermosetting. The various sources of MSW plastics includes domestic items(food containers, packaging foam, disposable cups, electronic equipments cases, drainage pipe, carbonated drinks bottles, CD and cassette boxes, surface coatings, flooring cushioning foams, thermal insulation foams, etc. The MSW collected plastics wastes are mixed one with major components of polyethylene, polypropylene, polystyrene, polyvinylchloride, and polyethylene terephthalate. The percentage of plastics in MSW has increased significantly in the recent years

In order to recycle municipal plastic wastes, separation of plastics from other household wastes is required. For mixed plastics we can use some mechanical separation method. For example using wet separation process mixed plastics can be separated into two groups: those with a density greater than water such as polystyrene and polyvinyl chloride, and those with density lower than that of water such as polypropylene, polyethylene and expanded polystyrene. Municipal plastic wastes are heterogeneous, where as industrial plastics wastes are homogeneous in most times. Most of industrial plastic wastes have relatively good physical characteristics i.e. sufficiently clean and free of contamination and are available in fairly large quantities.

2. Literature review

The continuous increase of waste plastic disposal is generating environmental problems worldwide. The present rate of economic growth is unimaginable without saving of fossil energy like crude oil, natural gas or coal. Suitable waste management is another important aspect of sustainable development. Plastic wastes represent a considerable part of municipal wastes; furthermore huge amounts of plastic waste arise as a by-product or defective product in industry and agriculture. The amount of plastic waste generated is still considerably less than that of plastics produced: in numerous applications (building, furniture, appliances) plastics meet long-term requirements before their disposal and therefore do not yet occur in the waste stream in big quantities. The majority of plastic wastes are found in municipal solid waste (MSW), as well as in waste streams arising in distribution, agriculture, construction, furniture and household ware, automotive, electronic and electrical, or medical applications. Use of plastics in consumer electronics and electrical equipment &construction are growing very rapidly.

Pre-consumer plastic wastes are generated during the manufacture of virgin plastics from raw materials (oil, natural gas, salt, etc.) and from the conversion of plastics into plastic products.

Waste management policy focuses on waste hierarchy, giving great priority to waste prevention or reduction followed by re-use, recycling, recovery and residual management. Such a strategy includes an integrated approach to waste management with emphasis on material recycling that is preferred over energy recovery.

[...]