Study on the Stability of High Pressure Pneumatic Transport of the Mixture of Pulverized Coal and Extraction Residue of Direct Coal Liquefaction Residue

Abstract

The use of direct liquefaction residue of coal has been the focus of attention. Due to the liquefaction residue contains more organic compounds, it is necessary to recover these organic compounds by extraction, and then the extraction residue is considered as a feedstock, which mixed with coal into a powder and enter a dry-fed entrained flow coal gasifier for gasification. However, the stability of high pressure pneumatic transport of the mixture of pulverized coal and extraction residue is crucial to the safe and stable operation of dry-fed entrained flow coal gasifiers. In this paper, A set of up to 6.0 MPag high pressure dense phase transport experiments was built, and high pressure pneumatic conveying experiments were carried out using a high-volatile bituminous coal and its mixture with 20 wt% extraction residue of direct coal liquefaction residue (DCLR) in pipes with diameters of 25 mm and 15 mm, respectively, and at back pressures of 1.0–4.0 MPag. By comparing and calculating the relative standard deviations (RSDs) of different signals on the transport stability, the RSD of solid flow rate was selected as an indicator for conveying stability. The result show that the RSDs of both transport stability signals of coal and its mixture with 20 wt% extraction residue of DCLR is less than 4%, which indicated that good stability was found in both the coal and its mixture with 20 wt% extraction residue of DCLR.