Experimental And Model Study On The Process Of Char Particle Gasification With Carbon Dioxide

Coal is the most abundant fossil energy in reserves in the world at present. China is a great energy power taking coal as the main energy resources, and the total amount of discharge of carbon dioxide is quite large next to USA in the world, so how to solve the problem of carbon dioxide discharge effectively and how to highly efficient use of coal resources has been a major issue in energy and environment areas. In recent years, it has been found that char gasification with carbon dioxide can get high concentration of carbon monoxide. Using carbon dioxide to gasify char is an important way in reducing carbon dioxide emission, as well as with double practical significance.This paper focuses on the process of char particle gasification with carbon dioxide reduction reaction and sets up mathematical dynamic model of this process. because the gasification reaction between char particle and carbon dioxide involves many aspects such as carbon dioxide diffuses to the inside of the particle, gasification reaction on the inner surface of the particle and the influence on reaction from evolution of pore structure, These are also the basis for the establishment of dynamic model, So the work of the full text mainly reflects in several following respects:The effect of pore structure and its evolution on char particle gasification behavior were studied, a new structural factor which reflects surface area evolution of char particle during gasification process was deduced in this paper; it reveals that initial porosity has great importance on the surface area evolution; the specific surface area can reach a maximum or reduce with conversion due to different initial porosity, which has the similar character as that of Random Pore Model(RPM), the structural factor here is not only in simple form but also definitude in physical sense with good precision by comparing it with RPM. It has certain universality as a sub-model to the whole dynamic model.On the fixed bed gasification experimental furnace, the reactivity of different particle size was studied through experiment. The dynamic behavior of gasification were also studied under temperature 1080℃,1170℃and 1220℃, influencing factors of reactivity and gasification rate were analyzed based on the experiment results.In the last, the integral char particle gasification dynamic model was established. The integral char particle gasification dynamic model was established. This model includes diffusion mass transfer of carbon dioxide and carbon monoxide in the char particle structure, solid heat conduction, as well as the heterogeneous reaction on the particle surface. During the gasification process the peripheral fragmentation was neglected, the diameter of the particle was considered unchanged in a wide conversion range, the feature of the model is that it is unessential to consider which control region the gasification is in, the model is applicable to the whole control regions.MATLAB programming was used to solve the partial differential equations, by means of the model, the char particle gasification was quantitatively studied.