Simulation Research On An Entrained-flow Pulverized Coal Partial Gasifier And Its Directional Control

Coal is not only a kind of energy but a resource,and the coal gasification multi-generation can achieve the realization of clean utilization of coal grading conversion.To achieve this goal,partial gasification of pulverized coal in the entrained-flow gasifier is put forward,based on coal pyrolysis and gasification.The core problem is how to achieve partial gasification of coal powder at high efficiency and low cost and to control the syngas product directionally.Focusing on the core problem of partial gasification of pulverized coal in the entrained-flow gasifier,this paper takes numerical simulation as the main methodology and conducts the basic research on the partial gasification directional control of pulverized coal in an entrained-flow gasifier.The research object is a 75kg/h entrained-flow pulverized coal partial gasifier.Firstly,the finite probability eddy dissipation model and component transport model of FLUENT software are compared.The experimental data of the gasifier verify the accuracy of the species transport model,while the probability density model?PDF model?fail to predict the concentrations of the species and the carbon conversion rate.Therefore,PDF model is not competent for the prediction of this gasifier.Secondly,the species transport model is used to analyze the operating characteristics of the gasifier under various operation conditions,including various coal/oxygen ratios?equiva le nt ratio?,various added steam?the gasifying agent?ratios,and the segmental oxygen supply.Influences of these conditions on operating characteristics of the gasifier and characteristics of the syngas will be revealed.Results show that the rise of the equivalent ratio is beneficial to increase the mixability in the gasifier.With the decrease of the equivalent ratio,the CO concentration in the dry syngas increases monotonously,concentrations of H₂ and CO₂ decrease monotonously,as well as the cold gas efficiency increases monotonously.The research on operation parameters,such as the accretion rate,the CO concentration and the furnace wall temperature,reveals that the furnace wall is vulnerable to coking when the equivalent ratio ranging from 3.96 to 4.46.The addition of H₂O gasifying agent will reduce the CO concentration in the syngas,but the effect on the H₂ concentration in the dry gas is ignorable,and the cold gas efficiency and carbon conversion rate of the gasifier are reduced.When the oxygen is supplied segmentally,the efficiency of the gasifier will be affected as the O₂ concentration in the middle of the gasifier increases,but it is beneficial to achieve the uniformity of the wall temperature and reduce the possibility of coking on the wal.