Influence of Cohesive Zone Shape on Solid Flow in COREX Melter Gasifier by Discrete Element Method

Based on the principle of discrete element method （DEM）, a 2D slot model of a COREX melter gasifier was established to analyze the influence of cohesive zone shape on solid flow, including mass distribution, velocity distribution, normal force distribution and porosity distribution at a microscopic level. The results show that the co- hesive zone shape almost does not affect the particle movement in the upper shaft and deadman shape. The particles in the lower central bottom experience large normal force to support the particles above them, while particles around the raceway and in the fast flow zone exhibit weak force network. The porosity distribution was also examined under three kinds of cohesive zones. Like the velocity distribution, the whole packed bed can be divided into four main re- gions. With the increase of cohesive zone position, the low porosity region located in the root of cohesive zone increa- ses. And the porosity distribution becomes asymmetric in the case of biased cohesive zone.

Effects of coke charging pattern on burden movement in COREX melter gasifier based on physical simulation

A three-dimensional semicircle cold model of COREX melter gasifier(MG)was established,and the effects of coke charging pattern on burden movement were investigated by adopting this model.The burden flow pattern of packed bed was measured with different coke charging amounts,coke charging positions,and coke sizes.The results show that the solid flow pattern presents a change from straight line type to reverse U type and finally to W type in MG with traditional coke charging,while the burden flow pattern experiences the change from straight line type to W type with platform and finally W type under center coke charging,and the solid flow pattern presents a change from straight line type to W type with platform and finally W type under intermediate coke charging.The difference demonstrates that coke charging pattern affects the uniform descending in MG to some degree.The burden in the coke charging zone keeps a straight line descending.No matter what kind of coke charging pattern is adopted,the burden residence time is shortened with the increase in coke charging amount,and the vertex of deadman decreases obviously,which is conducive to the renewal of the deadman.The appropriate coke charging amount and coke size should be well controlled at 8.7%and 5 mm,respectively.The results are useful not only in developing further understanding of solid flow in MG but also in verifying different mathematical models,particularly the coupled discrete element method with computational fluid dynamics simulation which has been increasingly used in the literature.