Direct Coal Liquefaction Residue Nature And Application Of Exploratory Research

With the smoothly and stably running of Shenhua direct coal liquefaction (DCL) project, direct coal liquefaction residue (DCLR), one kind of byproducts in coal to oil process, has restricted the economic benefit of DCL. The amount of DCLR accounts for 30% of the raw coal, and has not been fully utilized for its chemical complication. According to this purpose, this work discussed the thermal properties through thermogravimetric analyzer, the modification ability to paving asphalt, and de-ashing properties of DCLR.The proximate analysis showed DCLR having high volatility and ash content but low moisture. On the basis of proximate analysis, a general ignition characteristic index-FZ number for judgement of ignition and combustion stability for pulverized coal was introduced into DCLR. The FZ number of DCLR is 7.1. According to the categorization of FZ, we know that DCLR ignites readily and flames steadily.The influence of heating rate on pyrolysis and combustion was also tested. Critical heating rate (between 40℃·min-1 and 50℃·min-1) was observed in pyrolysis and combustion process. DCLR was pyrolyzed in different mechanisms, when heating rate is lower or higher than the critical heating rate. In pyrolysis process, more than 90% of DCLR are volatilized in higher heating rate when heated to 1200℃. DCLR is combusted more readily and stably in lower heating rate than in higher heating rate.This paper studied the modification ability of DCLR to paving asphalt. The influencing factors, such as the blending temperature, high speed shear, and the percentage of DCLR to asphalt, were tested. The compatability and selectivity of DCLR and paving asphalt were also discussed.In the study of DCLR de-ashing, the author classified the DCLR components using solubility parameterδ/(cal·cm-3)1/2, which would be a separation standard. The influence of solvent's composition and properties to the yield and components of extraction were also studied. Hydrocarbon solvents keep original structure of DCLR, but with lower yield. Nitrogenous and oxygenous solvents have higer yield, but with DCLR structure destroyed. The mixture of two kinds of solvents can take full advantages of both solvents:The extract yield of dimethylbenzene and ethylenediamine mixture is more than 70%. The ash content of extraction is lower than 0.7%, and sulphur content is lower than 0.1%. The elementary analysis of extraction is close to the UINTAITE Mastic Asphalt.