Modelling of Refuse-Derived Fuel Gasification Reactor

Abstract

Landfilled municipal solid waste (MSW) emits significant quantities of greenhouse gases (GHG). The gasification process can reduce not only the amount of deposited waste, but also the amount of methane (CH4) emitted by landfills. With development of gasification processes, it is possible to chemically convert the waste into useful products, synthesis gas. This energy carrier can be used to generate electricity and produce other valuable materials such as hydrogen, methanol, etc. The raw material of gasification technology is the refused-derived fuel (RDF), which is the non-recyclable part of the MSW. Pyrolytic, oxidation and reduction processes can be separated in the downdraft moving bed reactor type. The aim of this work is to study the model and the reactions of the pyrolysis and oxidation zone and to investigate whether the model of oxidation zone can be integrated into the model of pyrolysis zone to reduce the computational capacity requirements. RDF pellet sample was milled, and representative samples were studied by thermogravimetric (TG). The kinetic parameters of the reactions were identified. The applied kinetic model can be used to calculate the mass of the produced gas, and a model suitable for determining the gas composition was added. The gas composition was estimated based on the mass balance of the elements. In the first approach, the composition and amount of gas obtained during the simulation of the pyrolysis zone was the raw material of the oxidation zone, then the composition of gas was calculated based on partial oxidation reactions. In the other approach, the gas composition was determined in one step. Both methods provided close to identical composition while the time of computation was almost the same. The biggest relative error in mass balance of the elements was 11.19 % in case of Approach 1 and it was less than 3 % in case of Approach 2.