Pore Network Simulation Of Ca-Based Sorbent During Calcination

摘要

Calcium sorbents (mainly limestone) are widely used often for dry desulfurization in coal-fired boiler. The CaCO_3 is calcined to CO_2 and CaO with high specific surface area and becomes the mesoporous sorbents. In the course of the calcinations of the limestone particle, the different pore structure is formed in the nascent CaO. The CaCO_3 calcines to CaO of different pore network when the calcinations conditions are changed. Monte-Carlo (MC) method was used to simulate the network of the limestone particle during the limestone's calcinations, which was combined nucleation mechanisms and the mathematical model of the calcinations and sintering mechanisms in the paper. The micro-characteristic and the topology information of simulated pore structure could be ascertained. The research showed that the irregular degree of pore network was reduced depending on the degree of decomposition of the limestone particle. The calcinations conditions had an important influence on the porous structure too. The higher CO_2 concentration and the higher calcinations temperature made the porous CaO tend to more regular. The Pixel-covering method is used to computing the fractal dimension.