| Coal is the most abundant fossil energy in our country, which determines that consumption structure of energy relying mainly on coal can not be changed in quite a long time. The direct coal liquefaction technology is one of the key technologies to ensure national energy security and find alternative energy sources. The process of coal direct liquefaction produce quite amount of residue. The quantity can reach about 30% of the raw coal. If this part of residue can not be utilized scientifically, it will restrict the whole coal direct liquefaction process of the economic and environmental benefits. So, it has important theoretical and practical research value that use liquefied residue efficiently and cleanly.Liquefaction residue is a kind of high carbon, high ash and high sulfur substance, And it is composed of unreacted coal, mineral matters and the catalyst needed in the reaction process. Because sulfur content of the direct coal liquefaction residue is relatively high, it will bring many hidden dangers in the process of use. The article use Shenhua direct coal liquefaction residue as raw material to study. After processing the original sample, I did the pyrolysis experiment, then tested their pyrolysis products and the dynamics calculation. Through the above of exploratory research, which can provide basic data and theoretical guidance for the clean utilization of residue.Do the analysis of element and industrial analysis and ash on liquefaction residue, determine the content of elements in the residue and other components; according to the national standard method by using Soxhlet extractor for four component extraction experiment on residue, four groups were divided into heavy oil, asphaltene, preasphaltene and tetrahydrofuran Insolubles (HS, A, PA and THFI), their contents were 14.3%,29.7%,6.6% and 49.4%. The residue, ash removal of residues and four components at different heating rates (10℃/min,20℃/min,30℃/min) and different atmosphere (N2 and CO2) using thermogravimetric analyzer for pyrolysis experiment, The analysis found:pyrolysis under N2 atmosphere, the reason of weightlessness liquefaction residue mainly organic decomposition, in the high temperature section also has a small weight loss peaks are caused by mineral decomposition, The weightlessness under CO2 atmosphere is similar to N2 atmosphere, And the effect of heating rate on the weight loss is very small, as the heating rate increase will have a certain thermal hysteresis phenomenon. Most of the minerals were removed in residue ash removal, and it weightlessness in different atmosphere is similar to DCLR, But it has no peaks at high temperature and the weight loss increased finally. Heavy oil, asphaltene and preasphaltene (HS, A, PA) are tetrahydrofuran soluble, the molecular weight of heavy oil is the lowest and structure is simple, the largest molecular weight structure of asphaltene is the most complex, So the HS weightlessness first, All their weightlessness rate is big. THFI is hard to decompose, weight loss temperature is higher and the weight loss is the least. Made the gasification experiments of DCLR,THFI and ash removal residue with high speed furnace in CO2 atmosphere, The erperiment show that the DCLR and ash removal residue has two obvious peaks, low temperature section is caused by the thermal reaction and high temperature section is caused by gasification reactiono. The gasification reaction makes THFI peaks increases obviously.The experiment showed that by FTIR:Under the N2 and CO2 atmosphere, residue after pyrolysis generate sulfide mainly H2S and SO2, So we focus on the product gas of H2S and SO2 at different heating rates (10℃/min,20℃/min,30℃/min), The organic sulfur in the residue of fat and some unstable sulfide can easily occur decomposition reaction at a relatively low temperature and escape some sulfide, And then the mineral pyrite sulfur will produce sulfide gas. The H2S and SO2 from DCLR is decomposition of organic sulfur and inorganic sulfur, which is given priority to with H2S. Removing ash residue is mainly caused by the decomposition of organic sulfur. HS,A and PA are organic compounds, and they decomposition of H2S and SO2, which is based on H2S. Sulfide in THFI are mainly pyrite sulfur, after heat decomposition for elemental S and with H atoms combined with the formation of H2S, and oxygen radical combined with SO2. The effect of heating rate is very small.SEM-EDX experiments show that:The surface of the DCLR and THFI are uneven, The distribution of organic matter and inorganic matter according to the ratio of S/Fe, we know that the removal of ash residue mostly is organic matter, so the ratio of S/Fe is much larger than the DCLR.At the same time the ratio of S/Fe in THFI surface is smaller.BET shows that: The specific surface area and pore volume of ash removal of residue is greatly increased compared to DCLR. The pore structure of THFI can also change.According to the pyrolysis with different heating rate (10℃/min,20℃/min and 30℃ /min), Selected by DAEM method take dynamics calculation on DCLR and ash removal of residues and four component, We can calculate the pyrolysis reaction activation energy and pre exponential factor, conversion rate, and the activation energy distribution function changes the relationship is consistent... |
PDF Full Text Request