Characterization and Heating value Prediction of Municipal solid waste
Abstract
There is an increasing trend of using municipal solid waste as an alternative energy resource, burning and converting it into energy in the form of heat or steam or electricity. The aim of this study is to predict energy value of MSW using compositional and proximate-based analysis of solid waste and compare the reliability of models in predicting the energy recovery potentials from different solid waste components. Physical characterization showed that food, yard, textile, leather, rubber, wood scrap, yard, metal, plastic and paper waste were the constituents of all waste samples in the study area, but in varying proportions. The energy content of combustible solid waste was estimated to be 17.50 MJ/kg for gross heating value, and 9.54 MJ/kg for net heating value, which revealed the suitability of solid waste as energy recovery option. In this study several proposed composition and proximate-based mathematical models have been used to estimate the HHV of municipal solid waste. The average high heating values estimated from some models were found to be 16.27 ± 0.90 MJ/kg (Model II), 16.45 ± 0.43 MJ/kg (Model III), 18.97 ± 0.03 MJ/kg (Model XVIII), and 16.60 ± 0.32 MJ/kg (Model XXIV) which were closely match the value with experimentally determined calorific value as 17.50 ± 0.68 MJ/kg. Therefore, it is concluded that the quantity of energy obtainable from a known amount and composition of mixed solid waste can be estimated using already developed models without conducting calorimetric experiments.
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Introduction
Municipal solid wastes, collected from cities, have recently thought as one of the important renewable energy resources. Recovering energy by means of a number of energy generation processes such as combustion, pyrolysis and gasification from municipal solid waste is feasible [1]. This method will reduce the quantity of incoming solid waste to dumping site and also open opportunities for new technologies in treating MSW. The first step to understand the feasibility of design energy conversion (incineration plan) is to obtain the basic data regarding to quantity and quality of generated MSW [2]. This research study was primarily motivated by the lack of laboratory facilities in calorific value and ultimate analysis in Ethiopia and this article is a continuation of Fetene et al., [3] and aims to determine the reliability of models in predicting the energy recovery potentials from different solid waste components at Jimma city households. Researchers have developed many empirical models. The mathematic models for the evaluation of heating value from physical and chemical properties have been developed by several researchers, and have reviewed several of these models based on physical composition and proximate and ultimate analysis [4]–[9]. However, given the determination of ultimate analysis data is relatively expensive, therefore, for the practice purpose correlation based on proximate analysis data will be more profitable. This data is the easiest and most widely used in the characterization of fuels mainly solid fuel.
Conclusion
Physical characterization showed that a high combustible matter and organic waste consisting of food, yard, paper, plastic, wood scrap, and textile waste comprised 91.24% of the total waste of Jimma city household solid waste, suggesting concerting the waste to some economic and environmental characteristics. Estimates of the energy content of Jimma city'shousehold solid waste were made based on Experimental heating and mathematical models developed based on physical composition and proximate analysis. Experimental values led to an estimation of 17.5 MJ/kg for gross heating value, and 9.54 MJ/kg for net heating value which fit the minimum level value required for incineration projects. Generally the heating value of Jimma city household solid waste make it attractive feeds for clean energy production instead of fossil-based solid fuels and can be alternative to the conventional fuels partially due to their high calorific value. The high heating values estimated from selected models were found to be closely matched the value determined experimentally. Therefore, it is concluded that the quantity of energy obtainable from a known amount and composition of solid waste can be estimated without conducting laboratory calorimetric experiments.
