The Research Of Physic-chemical Properties And Heating Blowing Process Of Direct Coal Liquefaction Residue

Direct coal liquefaction residue(DLR) is the by-product in the process of direct coal liquefaction, it usually accounts for about 30% of the raw coal. It is important for the environmental protection and sustainable economy to study the process of direct coal liquefaction. In this paper, the physic-chemical properties and the heating blowing process of DLR was studied; the comprehensive dates were obtained from the experiments, meanwhile it preliminary explains the heating blowing process. Main research work and results in this paper are as follows:The properties of direct coal liquefaction residue under pressure filtration process were studied. Firstly, N-hexane soluble content obtained from DLR through soxhlet was separated into four parts which were characterized by GC/MS. Secondly, the distillate from DLR was analyzed to obtain the date of boiling range. Finally thermogravimetric analyzer was used to invested the pyrolysis process of DLR. The results show that direct coal liquefaction residue has the characteristics of the low moisture (Mad:0.01%), high volatile(Vdaf:66.07%), and ash content(Ad:18.26%).In addition, the N-hexane soluble content is up to 49.49%. What’s more, the N-hexane soluble content of DLR mainly contains one to four rings alkylation aromatics, heteroatomic compound, however the saturated hydrocarbon content was rather low. The distillate content via reduced distillation from DLR reaches 63.6% on the dry and ash free basis and the distillate mainly ranges from 170℃ to 360℃. Besides, the activation energy ranges from 36～42 kJ/mol.The heating blowing process of DLR treated by pressure filtration process was studied in the heating blowing device. The flow rate, temperature and time was investigated, meanwhile the gas product, liquid product and the semicoke were analyzed, respectively. Finally, the effect of the addition of hydrogen-donor solvent on the distribution of the products. It turns out that the pyrolysis of DLR has already occurred in the reaction kettle during the heating blowing process. The degree of pyrolysis deepens with the temperature rising and the time extending. The carboxyl compounds of DLR containing carboxyl functional groups decomposes rapidly in 10 min, in addition the pyrolysis rate of structure of alkyl groups reaches maximum in 30min-40min. the pyrolysis process obviously happens and the yield of oil product is higher than the oil of DLR when the heating blowing temperature is over 375℃. Last but not least, the addition of hydrogen-donor solvent improved the pyrolysis process to a certain extent.The kinetic of heating blowing process was investigated and the kinetic model was built preliminarily. First, the DLR was divided into active reaction part and non-active reaciton part; then the kinetic parameters were calculated at different temperature; finally, the activation energy of the heating blowing process was obtained. The results show that the active reaction part converted into the gas product and liquid product during the heating blowing process. The heating blowing process activiation energy which is lower than the pyrolysis activition energy is 33.45 kJ/mol.