Study On Characteristics Of Rapid Pyrolysis And Gasification Reactivity Of Coal And Petroleum Coke In A DTF Reactor

In this paper, three coals with different ranks and two petroleum cokes were chosen as experimental material. Their characteristics of rapid pyrolysis were investigated in a drop tube furnace (DTF) reactor. In addition, gasification characteristics of coal char under high temperature, high heating rate were studied in it. The gasification reactivity of rapid pyrolysis char and petroleum coke were examined using TGA (thermogravimetric analyzer), as well as CO2 and steam gasification reaction kinetics of rapid pyrolysis char.Based on analysis of structure and gasification reactivity of rapid pyrolysis char, it is found that there is not good correlation between specific surface area and gasification reactivity of chars, however, the change of gasification reactivity of three chars with increasing pyrolysis temperature is in accordance with the development of carbon crystallite structure of chars which reflect graphitization progress of chars. This proves that the change of carbon crystallite structure of rapid pyrolysis char has a more essential influence on the change of its gasification reactivity. It comes to the same conclusion based on analysis of structure and gasification reactivity of rapid pyrolysis petroleum coke.Modified random pore model can fit various CO2 or steam gasification data well including different coals, pyrolysis temperatures. It remedies shortage of random pore model. Various gasification data could be unified with a master curve when conversion is plotted against normalized time t/t0.5 regardless of coal type, pyrolysis and gasification conditions, which indicates that t0.5 can be used as a reaction index for coal char gasification.Gasification experiment of SF char in DTF shows that, in high temperature diffusion control region, initial gasification rate of char obtained from DTF is about 10 times acquired from TGA. It proves that diffusion effect on gasification of char in DTF is fairly lower than in TGA when gasification temperature is high. Therefore, it can be concluded that DTF reactor is more appropriate to be used for investigating high temperature gasification reactivity of coal char.