Study on the variation of pore structure parameter of coal char at high temperature and its effect on gasification rate

In this paper, the variation of pore structure of three typical coal chars with the gasification temperature and its effect on subsequent gasification reaction were studied by means of drop tube furnace (DTF) and thermogravimetric analyzer (TG). The results show that the pore structure parameter of coal char increases with the increase of temperature, which characterizes the shrinkage and closure of pores at high temperature. The local decrease of pore structure parameter near the ash melting point indicates the blockage and cover of pore structure caused by ash melting at high temperature. The growth ratio is defined as the ratio of the difference between the maximum gasification reaction rate and the initial reaction rate to the initial reaction rate. When the pore structure parameter is greater than 2, there is a linear relationship between the growth ratio and the pore structure parameter, and the growth ratio increases with the increase of the pore structure parameter. When the pore structure parameter is less than 2, the relationship between the growth ratio and the pore structure parameter is not obvious. The experimental results also show that the high content of alkali metals has a great effect on the gasification rate, which makes it difficult to accurately fit the experimental data curve with the existing model, and the value of the growth ratio can not be affected by it. It is feasible to couple the growth ratio to the gasification model to improve the robustness of the model.