| Environment pollution problem has already become the focus attention around the world in today’s society,coal in Chinese energy consumption will occupy a high proportion at long term,therefore vigorously to develop the clean coal utilization and conversion technology is the important for Chinese energy development.This paper based on the 2000 t/d GSP entrained flow gasification process in the base,with the CFD numerical simulation method,investigates the feedstock gasification coal properties,acquires velocity flow field and optimized devolatilization parameters of GSP gasifier.The gasifier geometry model is built according to its industrial structure and size data.For the symmetry property of the gasifier,1/4 of which is chosen to be the calculation zone and its hexahedral structure mesh profile is gained with the ICEM CFD software.Based on ANSYS/Fluent software,using coal analysis data in a Ningdong factory and it’s actual operation conditions,Euler-Lagrangian method is used to simulate the gas-solid flow,its phase turbulent model is Realizable k-epsilon,DPM methods are adopted to simulate the coal particles move,radiation heat transfer between gas-solid two-phase uses P1 model,chemical reaction,chemical reaction and turbulent coupling components using transport model and the eddy dissipation concept(EDC)model,to take off the volatile using two competing rates model,the GSP gasification process are simulated.And the results show velocity flow field is divided into external recirculation zone,swirl jet zone,internal recirculation zone as well as plug flow zone.The mole fraction of H2 and CO along the gasifier height(h)increases to its maximum 22.6%and 66.3%.The temperature,which arrive at its maximum 2700 K at h=1.2 m,increases first and then decreases to stable level.Meanwhile,as the given volatile model kinetic parameters of Fluent software cannot meet the all coal,this study also do the research optimization of devolatilization model by gasification coal in a Ningdong factory,then do simulation by the optimized kinetic parameters.Results show H2 mole fraction at gasifier exit increases by heating rate,respectively 22.0%,22.5%and 22.6%;CO mole fraction is 67.6%,66.0%and 66.2%.The devolatilization model was optimized by changing the kinetic parameters.It was found that the kinetic parameters obtained by different heating rates have a significant influence on the temperature distribution in the gasifier.Therefore,the devolatilization model in the coal gasification process can be further explored by changing the heating rate to make the devolatilization model parameters closer to the actual working conditions,so as to guide the actual production of the enterprise. |
