Study On Combustion Characteristics Of Dongfeng Lignite Char

The resources of lignite in our country are very rich, because of the high moisture, high volatile characteristics, it can be pyrolyzed at low temperature and obtain gas, liquid products and char, the char can get futher use to improve its utilization.In this paper, Dongfeng lignite is chosed as material and done fixed-bed experiment. The results show that:In the selected temperature range, with the increasing of pyrolysis temperature, the tar yield increase firstly and then decrease, the maximun tar yield is 11.46% (d) at 520℃, while the char yield is deccreased from 65.84%(d) to 55.39%(d). With the increase of pyrolysis temperature, the ash of char is increased from 18.08%(d) to 22.11%(d), the volatile is decreased from 40.09% to 25.06%, H/C atomic ratio is decreased from 0.66 to 0.42.Thermogravimetric analyzer is used to investigate the combustion characteristics of Dongfeng lignite char on the condition of different heating rate, different oxygen concentration and mixed different coal rank. The results show that:With the increase of heating rate, the T;, Tm and Tf increase; with the increase of oxygen concentration, the Ti, Tm and Tf decrease; the Ti, Tm and Tf increased with the increase of Dongfeng lignite char proportion increase in char and lignite mixed samples; the T;, Tm and Tf decreased with the increase of Dongfeng lignite char proportion increase in char and Shenmu bituminous/Taixi anthracite mixed samples. On the condition of each factor being investigated, the dynamic machanism of char is generally follow Mampel Power Law, the reaction order is 1/2, only when the oxygen concentration is equal to or higher than 50%, consistent with Reaction Order Law, the reaction order is 2, and consistent with Avrami-Erofeev equation at low temperature stage of Dongfeng lignite char and Taixi anthracite mixed samples. In the process of char combustion at O2/N2 atmosphere, with the increase of oxygen concentration, the maximum concentration and total amount of SO2 and NO is increased; the maximum concentration and total amount of SO2 and NO is increased with the increase of Dongfeng lignite proportion increase in char and Dongfeng lignite mixed samples; the maximum concentration and total amount of SO2 is decreased, the maximum concentration and total amount of NO is increased with the increase of Dongfeng lignite char proportion increase in char and bituminous mixed samples; the change of char and Taixi anthracite mixed samples is the same with char and Shenmu bituminous mixed samples. In 02/Ar atmosphere, the emission and total amount of NO is the same with O2/N2 atmosphere, indicating that the generation of NO is mainly come from the nitrogen of Dongfeng char.