Optimization Of Two-stage Combined Gasifier And Process Simulation

Firstly, the effects of temperature, additive type and reaction atmosphere on carbon dioxide gasification of coal char from Shanghai Jiaohua Company were investigated on a fixed-bed reactor. The results showed that the potassium carbon could promote the gasification rate by carbon dioxide when the temperature was higher than 850℃.The order of promoting effect was K2CO3>KOH>Na2CO3>NaOH>Ca(NO3)2.4H2O. CO existing in the gasification system would decrease the gasification reactivity. And using the random pore model could simulate the reaction process well under the condition of different reaction atmosphere. K2CO3 had a more obvious effect on the products generating rate of lignite coal and Shanxi non-sticky coal, compared with Jinyou coal and Qujing coal. It could increase the generating rate of H2, and decrease the generating rate of CO and CH4. The gasification reactivity order of different coal char was lignite char> Shanxi non-sticky char> Jinyou coal char> Qujin coal char. Besides, Jinyou coal chars with different loadings of K and Ca were analyzed by an energy-dispersive X-ray analyzer (EDX), N2 adsorption at 77K and X-ray diffraction (XRD). The result showed the adding of K and Ca had an obvious effect on the surface morphology, specific surface area and microcrystalline compositions of the coal char.Secondly, the effects of coal char particle size and K2CO3 adding amount to the second stage on the gasification process were also investigated on a hot-model experiment device of two stage combined gasification. The experimental results showed that the suitable coal char particle size adding to the second stage was 10～15mm. The increase of K2CO3 adding to the second stage could increase the syngas heat value, carbon conversion, CO2 conversion and H2+CO concentration of the second outlet syngas. It could improve the reaction rate when the amount of K(K2CO3) was more than 5%.Ultimately, new process of two stage combined gasification was simulated by Aspen Plus software, with a characteristic of adding pulverized coal to the second stage. The simulation result showed that the suitable feeding ratio of the second stage was 8%～10% when the carbon conversion was more than 70%. The suitable feeding ratio of the second stage was less than 8% when the carbon conversion was less than 70%. It provided certain reference to the experiment operation of the next following new gasifier.