Kinetics Study On Plasma Coal Gasification

An arc plasma is a kind of hot jet with high temperature and great deal of active species. Its heavy species and electrons own the nearly same temperature, which is up to 104K. Coal gasification aided by plasma is a complicated reaction system. Many free radicals contribute to the reaction process. In the thesis experiments were carried out in terms of gasification effective factors, kinetics analysis, temperature in the reactor, computer modeling on active energy of main product gases, catalysis effect of mineral matter on plasma coal gasification. In order to investigate the characters of plasma coal gasification through the equipment on an industry scale which was manufactured by Tsinghua University, Dalian University of Technology and Taiyuan University of Technology, effecting factors, yielding gas change with time and affection of different addictives on product gases constitutes etc were researched experimentally. Based on these results, kinetics analyses are executed. To detect the temperature distributions in the reactor, the moving characters of coal particles, mechanism on reaction and kinetics, computer modeling was carried out.Experimental study on influencing factors was done, it found the optimal processing condition, as follow,Feeding rate is 150 gram per minute, feeding gas(air or oxygen) volume is 18 normal cubic meter per hour, output power of plasma generator is 100kilowatt, steam output pressure is 0.3 million Pascal.Firstly, by Classical kinetics analysis on the complicated reaction system being performed, elementary reactions were confirmed. Secondly, introduction of linear algebra method made the reaction system simplify. That is also to say, most linear independent group of coefficient matrix is required, linear correlation vectors are denoted by independent ones. Using the method, linear independent components was determined. Finally, the reaction system was simplified by pseudo-static method. Based on them, velocity equations of main product gases H2, CO and CO2 were deducted.Through the calculation of heat in the reactor, temperature in the first part of reactor is deducted, which is too high to measure by common scaling component. Using the function of office 2000, LINEST(known_y's,known_x's, const,stats), overall reaction rate equations and velocity constant of main product gases were fitted. Additionally their yielding active energies were calculated. Results were so, for H2, CO and CO2, they were respectively 68.42 kJ/mol, 48.482kJ/mol and 14.38kJ /mol. Compared with the routine coal gasification data reported, they were smaller. It demonstrated that the introduction of plasma contributed to coal gasification because of the deceasing active energy.Owing to non-linear character of plasma coal gasification reaction equation, Jill method was applied to computer model. Rules on the relationship between contents of main products and time were derived from the program modeling. At the same time, they were compared with experimental results. It showed that they could be in good agreement.At last, some addictive substances, namely, CaCO3 and CaO on plasma coal gasification were investigated in the thesis. The experiments testified that catalysis effect of CaO is more important than the deoxidization of CO2.