POTENTIAL ENERGY SOURCE THROUGH THERMAL DEGRADATION OF REFUSE DERIVED FUEL FROM MUNICIPAL SOLID WASTE

Abstract

Islamic Republic of Pakistan is a developing country and Ratifier of International Protocols. Especially, when it comes to Kyoto Protocol (1997) and reduction of greenhouse gases emissions. Landfill gas (CH4) is a potent greenhouse gas that can be cut down substantially by diverting the waste from the landfill. Open burning of solid waste contributes towards elevated CO2 emissions. It is also one of the major reasons behind production of Smog in Lahore. Utilizing waste into resource does not only control Global Warming and Smog but can also be used for waste to energy (WtE) purposes and overcome the energy crises. In the current Scenario, Municipal Solid Waste (MSW) from Ravi Town, Lahore was segregated into combustibles and other waste. The combustible fraction of MSW was feasible for Refuse Derived Fuel (RDF) processing; projected as 162.14 tons/day. The combustible laboratory samples were paper and cardboard (PC), shopping bags (SB), polyethylene terephthalate bottles (PET), other plastic composed of polystyrene (OP), food and drinks tetra-pack packaging made with a mixture of low density polyethylene, cardboard and aluminium (TP), textiles (TX) in the form of rags (mixture of cellulosic material and synthetic polymers) and toffee/chips wrappers (a blend of polypropylene and aluminium foil) represented as others. The RDF pellets were found in accordance with the European use for responsible incineration and treatment of special waste (EURITS) RDF standards. Thermogravimetric analysis (TGA) along with derivative thermal gravimetric (DTG) profile and chemical kinetics were performed on the samples to optimize the batch type pyrolysis unit design and operating conditions. Incineration of plastics constituents has been very controversial due to the release of dioxins at the elevated temperatures. On the other hand, the current study suggests that the pyrolysis is carried out in the controlled conditions using nitrogen as a purge gas. The effect of heating rates (10 oC min-1, 20 oC min-1 and 30 oC min-1) rates was significant on the decomposition patterns. The decomposition temperature of the RDF samples under consideration was optimized as upto 500 oC at the heating rate of 10 oC min-1. Kinetics study included estimation of activation energy, pre-exponential factor and regression analysis. The values of the activation energy indicated the need of an auxiliary fuel to initiate the decomposition reaction, pre-exponential values were in the favour of fast reactions and regression analysis suggested both simple and complex reactions happening during the pyrolysis of the RDF samples. Thus, a heating source and two outlets were added in the design of the pyrolysis unit. The RDF samples were run to obtain seven oil samples. The oil samples were tested by Fourier Transform Infrared Spectroscopy (FTIR). The hydrocarbon functional group of alkanes was very dominant among the results showing feasibility.