Study On The Effect Of Steam Gasification Of Shengli Lignite Char Catalyzed By Alkaline Earth Calcium

Lignite reserves are abundant in our country. For its large water content, high volatile, low heat and poor thermal stability, it is more suitable to use it efficiently and cleanly by coal gasification technology. Low temperature catalytic steam gasification of lignite has many advantages, such as, reducing the initial temperature of lignite gasification, producing hydrogen-rich synthesis gas, saving energy and processing consumption. In this paper, the influence of pyrolysis temperature, kinds of calcium and its addition method, amount of calcium oxide on the steam gasification performance of Shengli lignite are investigated with XRD, and FTIR.By preparing raw char, pickling char and minerals- char in different pyrolysis temperatures(500, 700, 900 and 1100 ℃), it indicates that as a result of the addition of calcium oxide in the mineral- char, its gasification performance has been significantly improved than the pickling char, and some samples are even better than the raw char. Meanwhile, with increasing the pyrolysis temperature, this trend is particularly evident.Through adding calcium in different ways(mechanical method and impregnation method) and different coking sequence(minerals-char and char-minerals) to prepare high temperature char, it suggests that the gasification performance of char samples prepared by impregnation method is overall superior than the samples prepared by the mechanical method, and minerals-char’s steam gasification performance is significantly better than the char-minerals. On the other hand, to the two addition methods, the effects of different kinds of calcium(Ca O、Ca(NO3)2、Ca Cl2、Ca(Ac)2) are diverse. For the samples which are obtained by impregnation method, the performance ranks are as following: SL+-ACI-J>SL+-OI-J>SL+-NO3I-J>SL+-ClI-J;while for mechanical method, the orders are SL+-OM-J>SL+-AcM-J>SL+-NO3M-J>SL+-ClM-J.The gasification performance of high-temperature pyrolysis char with different addition amount(0%, 2%, 3%, 5%, 10% and 20%) of calcium oxide shows that, alkaline earth calcium has good catalytic effect on the steam gasification performance of Shengli lignite char, and with increasing addition amount of calcium oxide, the gasification performance is gradually increased. However, when the addition amount of calcium oxid exceeds 10%, its steam gasification performance degrades.