Study On Pyrolysis Characteristics Of Coal And Liquefaction Residue

The present situation of energy in China is lean oil and less gas, but relatively rich in coal. In order to meet the urgent demand of energy for national economic development, It has been draw researchers’close attention to achieve coal clean and efficient utilization and reduce costs through the transformation of coal resources cascade. In this paper, Hulun Buir lignite(Inner Mongolia) and Shenhua direct coal liquefaction residue have been selected as the research object, The experimental and theoretical research that Hulun Buir lignite and Shenhua direct coal liquefaction residue separate pyrolysis and co-pyrolysis characteristics and the properties of the product (char, tar, gas) have been studied by using TG-FTIR spectrometer and Powder-Particle fluidized bed pyrolysis experimental installation.TG-FTIR was used to analyzed the Hulun Buir lignite and Shenhua direct coal liquefaction residue separate pyrolysis and co-pyrolysis weightless process and gas product evolution rule. And the kinetic parameters were calculated. The results indicates that the weight loss of Hulun Buir lignite and Shenhua direct coal liquefaction residue under N2 atmosphere are 33.22% and 34.45%,repectively.There is a synergistic effect between the Hulun Buir lignite and Shenhua direct coal liquefaction residue in the prolysis temperature ranging from 250 to 450℃. And the synergistic effect increases first and then decreases with addition of Shenhua direct coal liquefaction residue increasing. There is apparent synergistic effect when the addition proportion of Shenhua direct coal liquefaction residue was 20%.The main pyrolysis region of Hulunbeier lignite and Shenhua direct coal liquefaction residue separate pyrolysis and co-pyrolysis can be divided into one or two consecutive first-order reactions. The activation energy of Hulunbeier lignite and Shenhua direct coal liquefaction residue are 34.38 kJ/mol and 61 kJ/mol,repectively. And the activation energy of co-pyrolysis differs with addition of Shenhua direct coal liquefaction residue ranging, whose activation energy is close to that of Hulun Buir lignite when addition of Shenhua direct coal liquefaction residue is small.The effect of prolysis temperature and superficial gas velocity on Hulun Buir lignite fast pyrolysis product distribution and its properties has been investigated by using Powder-Particle fluidized bed pyrolysis experimental installation. The results indicates that with prolysis temperature increasing, char yield decreases, the tar yield increases first and then decreases, reaching the maximum 7.30% at 600℃, gas and BTX yield increases monotonically. With the superficial gas velocity increasing, char yield increases, tar yield increases first and then decreases,and reaches the maximum when the gas velocity is 0.3m/s.The properties of Hulun Buir lignite and its pyrolysis chars, including weight loss, surface structure, pore structure and surface morphology have been studied by using TG-FTIR spectrometer, FTIR, physical and chemical adsorption devices and scanning electron microscope. The results indicates that the weight loss of chars decreases with temperature increasing, but is lower than that of coal, the surface area and pore volume of char are higher than coal.The effect of blending ratio and pyrolysis temperature on Hulun Buir lignite and Shenhua direct coal liquefaction co-pyrolysis product distribution and its properties has been investigated by using Powder-Particle fluidized bed pyrolysis experimental installation. With the addition of Shenhua direct coal liquefaction residue increasing, the tar yield increases, char yield decreases, tar yield of HL+10% SHR pyrolysis is the largest and 1.75 times as high as that of Hulun Buir at the same temperature. In the prolysis temperature ranging from 500 to 750℃, char yield of HL+10% SHR pyrolysis shows a gradual decreasing trend, and less than that of Hulunbeier lignite prolysis alone; the tar yield increases first and then decreases and is higher than tar yield of Hulun Buir lignite at the same temperature, obtains the maximum tar yield,12.75% at 600℃.