Study of the Conversion of Municipal Solid Waste (MSW) into Liquid Fuel

Transcription

1 Study of the Conversion of Municipal Solid Waste (MSW) into Liquid Fuel *Corresponding Author: DOI: 0.08/nijesr Afsheen Mujtiba*, Shahid Raza Malik Department of Chemical Engineering, NFC Institute of Engineering and Fertilizer Research, Faisalabad, Pakistan Abstract Due to energy crises and limited oil sources, we should switch over to alternate energy resources for meeting the future energy demands. Burning of MSW can produce energy and at the same time reducing the volume of waste by up to 70, which is an environmental benefit and the gases obtained from this can also be collected as they are combustible. An investigation was conducted on different technologies and processes that can be utilized to convert the municipal solid waste into useful energy (liquid fuel). The investigation includes the design of pyrolysis reactor and its future prospects in Pakistan. The process under present investigation comprises of pyrolysis reactor, condenser for condensable gas, gas holder (for non- condensable gas). The feedstock used in the pyrolysis reactor is the municipal solid waste (which includes kitchen waste, papers etc). The yield of the pyrolysis was Pyro oil, pyrogas and char. So municipal solid waste can use completely to produce valuable fuel products. products. Waste composition varies from one country to another []. There are five categories of MSW which are given in Table -. Example of household hazardous waste and chemicals which they contain are described in the domestic hazardous waste. In addition to hazardous waste several volatile organic compounds present, many of which were thought to be byproduct of microbiological activity or component of non hazardous packaging materials. Once the volatile organic compounds enter in the MSW stream, they may be release to environment by number of ways [, ]. Keywords Renewable energy, Municipal Solid Waste (MSW), Garbage, Pyrolysis, Volume reduction, Pyrolytic oil, Char. I. INTRODUCTION Alarming energy crises and rapid rise in oil prices internationally has its impact on Pakistan as well. In anticipation, Pakistan has to switch over to alternate energy resources for meeting its future energy demands. Pakistan has huge reserves of coal in Thar but it is of low grade having significant percentages of Sulphur and Nitrogen. Using it for power production may be associated with potential hazards of emitting environment pollutants such as SO X and NO X. Because of this problem of coal, Pakistan has to switch on different renewable energy resources; one of them is the production of liquid fuel from burning of Municipal Solid Waste (MSW). Burning of MSW can produce energy and at the same time reducing the volume of waste by up to 70, which is an environmental benefit and gases obtained from this can also be collected as they are combustible, which further helps in reducing the global warming. Municipal Solid Waste (MSW) is also known as trash or garbage, especially waste is sometimes added to commercial waste. A typical mixture of garbage can be seen in Fig. - []. They are solid or partially solid and normally without industrial hazardous wastes. This word refers to the source of waste, including not separated by a left or recycling household Fig.. Typical Municipal Solid Waste Municipal Solid Waste (MSW) is usually garbage gathered by local government, and it may include household waste with some commercial and industrial wastes. Historically, the amount of municipal waste has increased compared with the previous year, which local governments have big challenge. Amount of waste also affected by change in lifestyles, as use of disposable materials and too much packaging is increasing. Solid waste management is today a worldwide problem. As there are number of issues related to solid waste management and public services in major cities. The problem is not limited to land, it contains water and air, as well. The waste management has two extreme options in Europe and UK. First is recycling part (furniture, recycled glass or compost organic waste recycling) and energy from waste (for example, can burn or production of bio-digestion of biodegradable waste into useful gas or liquid fuel).

2 Some of physical properties of MSW have fundamental role in its utilization these includes density, moisture content and particle size and distribution. National schemes are now being developing in many countries, but a need of effective implementation of environmental policies is a major issue [8]. TABLE : CATEGORIES OF MUNICIPAL SOLID WASTE S.No Waste Categories Example Biodegradable Waste Food and kitchen waste, green waste paper etc Recycle Material Paper, glass, bottles, cans metals, certain plastics etc Inert Waste Construction and destruction waste, dirt, rocks, debris. II. PROCESS AND EXPERIMENATAL PROCEDURE The equipment consisted of a pyrolytic reactor which was placed in the furnace, a gas holder and the receiver for condensable liquid as shown in Figure -. The mild steel was used for the construction of Pyrolytic reactor. The condensing unit was connected through copper pipes for good heat transfer. A 00 o C range thermocouples were used for temperature measurement. The lagging was done on the copper pipes to avoid heat loss. The household refuse was used as feedstock in my experiment. Composite Waste Waste clothes, Tetra packs, waste plastic e.g. toys 5 Domestic Hazardous Waste medicines, paints, chemicals, light bulbs, e waste, spray cans, fertilizers, shoe polish and batteries etc. In 990 numerous non-hazardous waste incinerators was working on energy recovery in US and have effectively controlled the emissions to environment by installing pollution control system. New threats from such kind of industry also had been identified e.g. by dioxin and mercury emissions, the Environmental Protection Agency (EPA) introduced the regulations in the 990s Maximum Achievable Control Technology (MACT). As a result, existing facilities had to improve air pollution control systems or be shut down [5]. EPA recommends that there are four parts of an integrated approach to waste management hierarchy consisting of: resource conservation, recycling, incineration and landfill. This inclusive methodology reports serious stages in the manufacturing, use and disposal of products and materials to minimize wastefulness and exploit value. [6] Now three new approaches to converting trash into energy so-called waste-to-energy (WTE) technologies look to leave mass-burn incineration behind by transforming how we think about MSW in the United States. Supporters of these developing approaches gasification, plasma gasification, and pyrolysis assurance cleaner discharges and more flexibility in terms of energy production, plus in some cases the effective elimination of landfilling. Conversion technologies are further distinguished from conventional MSW incineration by the production of synthesis gas (or syngas) composed mainly of hydrogen and carbon monoxide, a product of the thermal reactions that take place during the processes. The syngas can then be burned in a boiler system to generate electricity. It can also be processed into fuel for an efficient, low-emissions natural gas generator or refined into other valuable products. On paper, these differences make conversion technologies cleaner, more efficient, and more valuable. [7] Fig.. Process flow diagram for conversion of municipal waste to liquid fuel Error! Reference source not found. The feedstock (MSW) was collected from hostel mess and waste dumpsite available and also the garden waste. The samples were collected before these are gathered at a single site. The MSW were dried in a hot air dryer for a period of hours at a temperature of 05 O C to decrease its moisture. The moisture content of the dried wastes was about 8-0. Pulverization was done to reduce the particle size up to.5 to.0 mm. The feed injected in the shredder for the size reduction of municipal solid waste to liquid fuel consists of kitchen waste, paper & card board, plastic and rubber, garden waste and saw dust [0]. TABLE : FEED INJECTED COMPOSITION FOR SIZE REDUCTION SR. NO Components Weight Kitchen Waste 85 Paper and Cardboard 500 Plastic and Rubber 5 Garden waste 00 5 Saw dust 700 The reactor was filled every time with approximately. kg MSW after drying and operates it for hours at a temperature from 500 o C-700 o C []. After Pyrolytic reactor the whole

3 products pass though the condenser where condensable material liquefy and uncondensed material go further. The product from pyrolytic reactor was cooled in a container surrounded in an ice container. We repeated the same procedure 7 times by differing the composition of feed and checked by analysis either we can get Liquid fuel from MSW. Table - shows the components of Feed stock and typical quantity taken in each run. III. RESULTS AND DISCUSSION Results of the pyrolysis of waste samples with varying composition are given below: TABLE - COMPONENTS OF FEED STOCK (EXPERIMENT DONE SEVEN TIMES) SR. NO Components Weight Kitchen Waste Paper and Cardboard Plastic and Rubber Garden waste Saw dust Table - shows the components taken for the experiment and their weight taken in grams for different runs. Total 7 experiments performed by varying weight of components. Size reduction of MSW was done for the better thermochmeical reactions. Products from the experiment are presented in Table - at 700 o C. From the table, it was observed that the products of the pyrolysis were Pyro oil, pyrogas and char in different proportions. The yield of Pyro oil varies as the organic portion of MSW varies. TABLE - PRODUCTS OF MSW PYROLYSIS Exp. No. MSW Char Pyro oil Char yield Tar yield Average As can be seen from Table -, the yield of char obtained from the pyrolysis of MSW expressed as a percentage of feedstock was 9.97, Pyro oil yield is 5.0 and remaining uncondensed gas obtained is also combustible. It means that every product obtained by MSW can be used as an energy source. A Comparison with Different Fuels Table - shows the energy contents in the tar oil. It is observed that energy content in the tar oil is,70 KJ/kg. This shows that the tar oil produced from MSW can be used more efficiently as energy if distilled it can yield some useful petroleum products. TABLE : ENERGY CONTENT IN TAR OIL Exp. No Net Calorific Value in Tar Oil (KJ/kg) Gross Calorific Value in Tar Oil (KJ/kg) 0,0 0,90,80,60,0, Figure - shows a comparison of different fuels with Pyro oil obtained from pyrolysis of municipal solid waste. MSW pyrolysis oils can also be used as a fuel oil alternate. Tests of Combustion show that this oil burns successfully. However, some problems are there in the combustion while burning without up gradation. They have very high water content that is detrimental for ignition. Fig. - Comparison of calorific value of different fuels with Pyro oil B Volume Reduction Waste volume reduction is the main advantage of pyrolysis technique. At high temperatures, pyrolysis reduces volume

4 significantly, but also removes the original odor of source. This can be observed in Table -. Approximately up to 70 of waste volume decrease in all experiments as discussed in the literature. Considerable MSW weight reduction can be achieved through pyrolysis and by this MSW management is done in effective manner. There are several uses for pyrolysis char. It can be converted into activated carbon. Char can be compressed into charcoal briquettes or used to make gunpowder. "The activated carbon market is very big. It is used for water treatment and in agriculture, which has a potentially very big market. C. Analysis of Pyrolysis Oil The liquid is found to have high carbon content. The energy content in terms of higher heating value of the Pyro oil is about,70 KJ/kg due to the presence of high percentage of carbon. The elemental compositions of carbon, hydrogen and nitrogen are given in table -5 for different runs. TABLE : MSW VOLUME REDUCTION AFTER PYROLYSIS Exp. No. MSW Char Pyro oil Volume Reduction Average 70.0 Elem ents C H N IV. CONCLUSION AND FUTURE RECOMMENDATIONS The outcome of this study has generated some fundamental data and information essential for waste characterization. MSW can generally be composed of carbon, hydrogen, oxygen and nitrogen where sulphur is also present in less proportion. Due to the lower contents of sulfur and nitrogen utilization of the derived energy does not add sulfur dioxide, nitrogen oxides and no net carbon dioxide, which are greenhouse gases to the atmospheric environment, in contrast to fossil fuels. Major proportions of MSW are kitchen and paper waste, in which the main components are cellulose, hemicelluloses, starch and lignin. The average yields of Pyro oil and char from MSW were 5.5 and 9.97 respectively, which tells us that MSW can be completely converted into useful fuel products. Average waste volume reduction of about 70 was achieved through the pyrolysis of the MSW. This provides an advantage over dumping the waste in land fill sites. It could provide a cost-effective supply of sustainable fuels for future energy generation. The design of the experimental setup used for the pyrolysis of MSW was developed and studied by varying the composition of MSW and further the samples were analyzed from CNS analyzer. The uses of the overall products are as follows: Bio-oil/pyrolysis oil can be used in boilers, furnaces, ship engines, train engines and turbines. After minor up gradation of bio-oil, several organic chemicals are found which can be used in chemical industry, laboratory and in pharmaceutical industry, etc. Char can be used for activated carbon production, reinforcing fillers in plastic and rubber goods and in ceramic brick industry. Gaseous products can be used in generator to produce electricity. Thus a problematic waste is converted into a total usable product and can solve the energy crisis of the country and of the world in a significant amount. Areas where research and development has contributed to enhanced MSW combustion include The use of gas reburning to control NOx and reduce emission of organic compounds, Practical ways for removing organic compounds and mercury from MSW flue gas. REFERENCES [] page=biomass_waste_to_energy [] Sindh Coal Authority, Harnessing of coal resources of Sindh province, Dec 00. URL: [] J. Peirce, R. F. Weiner and P. A. Vesilind, Environmental Pollution and Control, th Edition, Butterworth-Heinemann, USA, 998. [] S. Yaman, Pyrolsis of biomass to produce fuels and chemical feedstocks, Energy Conversion and Management, vol. 5, pp 65 67, 00. [5] [6] Centre for Sustainable Systems, Municipal Solid Waste Factsheet, University Michigan, 0 church street, Ann Arbor, May 009. URL:

5 [7] [8] Pakistan Environmental Protection Act 997, The Gazatte of Pakistan, Environmental Pollution Act 997, Islamabad. [9] M. Islam, M. R. Alam and M. R. Islam, Pyrolytic oil from fixed bed pyrolysis of municipal solid waste and its characterization, Renewable Energy, vol.0, pp - 0, 005. [0] S. J. Ojolo and A. I. Bamgboye, Thermochemical conversion of municipal solid waste to produce, Agriculture Engineering International, vol. VII. ManuscriptEE ,