Study of thermal destruction of municipal solid waste based on ASPEN PLUS modeling

A pressing issue of our time that requires immediate solution is the disposal and neutralization of municipal solid waste (MSW), the volumes of which are increasing annually. Pyrolysis is a promising environmentally friendly method of processing municipal solid waste. It allows obtaining a combination of solid, liquid and gaseous products in various proportions by changing the operating parameters of the process. In practice two main pyrolysis methods are used, they are “dry” and oxidative. Their organization and nature determine the reduction of waste volumes and greenhouse gas emissions, the characteristics and cost of the product gas, etc. A number of factors such as the temperature level of the process, the oxygen content in the gas entering the reactor, moisture and morphological composition of the feedstock affect the pyrolysis process and, consequently, the operating mode of the pyrolysis unit. Mathematical modeling methods allow assessing the degree of impact on the process and the mutual influence of these factors. The aim of this study is to predict the yield and heat of combustion of MSW pyrolysis products of average morphological composition depending on the initial moisture content of MSW and the process temperature based on mathematical modeling. The method of simulation mathematical modeling using the Aspen Plus software environment has been chosen as the research method. A simulation model of “dry” and oxidative pyrolysis of average morphological composition municipal solid waste has been developed. It allows assessing the influence of the specific heat absorption of raw materials during the pyrolysis process and the initial moisture content of municipal solid waste on the process parameters: composition, specific yield, heat of combustion and temperature of the pyrolysis gas. It has been established that as a result of “dry” pyrolysis of MSW of average morphological composition, the most calorific gas with a combustion heat of 8133 kJ/m3 is formed at a temperature of 300 °C and a feedstock moisture content of 0 %, and the lowest calorific gas (Qрн = 3092 kJ/m3) but with the highest specific yield, is obtained at a temperature of 600 °C and a MSW moisture content of 60 %. As a result of oxidative pyrolysis, the most calorific gas with a combustion heat of 4141 kJ/m3 is formed at a temperature of 600 °C and a feedstock moisture content of 0 %, and the lowest calorific gas with Qрн = 490 kJ/m3 corresponds to a temperature of 600 °C and a feedstock moisture content of 60 %. The highest specific gas yield corresponds to a moisture content of 40 % and a temperature of 600 °C. The developed simulation model of “dry” and oxidative pyrolysis of municipal solid waste has shown the inexpediency of MSV of the studied composition at an initial moisture content above 40 %.