Study On Pyrolysis And Incineration Of Municipal Solid Waste Using The Recycled Bed Material Of CFB As Heat Carrier

Incineration can reduce the weight and volume furthest. However, there exists serious second pollution in waste incineration, such as high temperature erosion, heavy metal and PCDD/Fs pollution. These problems restrict the waste management and energy utilization process in China. As the present study indicated, the removal of chlorine is the key point to solving the second pollution in waste incineration. Two-stage waste combustion groups with the pyrolysis and incineration. The pyrolysis process uses the recycled bed material as heat resources. Two-stage waste combustion process can realize HC1 removal before waste goes into the CFB(circled fluidized bed ) combustor. After cleaning system, the produced gas without HC1 is introduced into combustor and burning out with the pyrolysis residue. The CFB combustor can burn the fuel with low volatile content effectively. The heat during combustion is used to produce steam which can be introduced into the turbine to generate electricity.Biomass and PVC is the typical constituent of MSW. In this paper, biomass and PVC were selected as the thermo-gravimetric analysis samples. By the thermo-gravimetric analysis, the pyrolysis characteristics were obtained. The kinetic parameters of biomass pyrolysis were determined with the theory of DAEM(distributed activated energy model). The distribution of activated energy of different biomass was compared.Based on the experiment data and DAEM, a numerical modeling for pyrolysis of biomass particle in the fluidized bed of heat carrier was conducted. A set of equation reflecting the heat transfer and pyrolysis reaction of biomass particle in the fluidized bed of heat carrier was established. The temperature profile in the biomass particle against time was obtained. Also the influence of the radius of heat carrier and biomass particle, the bed temperature and the fluidized velocity on the pyrolysis against time was discussed. On the platform of Aspen Plus, the thermodynamic equilibrium analysis of waste incineration system was performed to reveal the trend of distribution of chlorine in the equilibrium product under different temperature and excessive air coefficient. Also the influence of calcium-based sorbent addition on the distribution of chlorine in the equilibrium product was analyzed. The process simulation of two-stage combustion and conventional incineration was conducted. The material and energy balance of the system was obtained. The two processes were compared in the aspect of technique and environment protection.