Flash pyrolysis coal liquefaction process development. Final report, July 1976-June 1978

Abstract

This is the final report of the work performed by Occidental Research Corporation (ORC) on Flash Pyrolysis Coal Liquefaction Process Development. In this program, a specially-designed, proprietary, caking coal reactor was demonstrated to process caking coals without oxidative pretreatment. Tar yields of about 35 wt % MAF were achieved in a 3 ton-per-day process development unit (PDU) from Western Kentucky No. 9 seam bituminous coal, and tar yields of about 22 wt % MAF were achieved from Wyoming Monarch seam subbituminous coal at a reactor residence time of about 1.5 seconds and a temperature of about 1200/sup 0/F. These tar yields were about twice that obtainable for the same coals by Fischer Assay testing or by the fluidized bed pyrolysis processes (such as COED) with long residence times. The hydrorefining processability of the pyrolysis tar was demonstrated using a continuous hydrotreater. Two major technical problems were encountered and solved during this program: (1) the initial PDU tar yield results were low compared to projections from the bench scale reactor (BSR), and (2) poor char rate control severely limited the PDU reactor operability. Tar cracking on the excessively active surfaces of the recycle char was identified as the cause for themore » lower tar yield in the PDU. By using reactive char transport gases such as CO/sub 2/ and H/sub 2/O rather than N/sub 2/, the tar yield from PDU was increased to the same level as BSR. The tar yield was also increased by using less reactive solid heat carriers such as nonporous alumina or petroleum fluid coke. The char rate control problem was solved by the development and the use of a novel lift-tube char feeder in the place of a mechanical screw feeder.« less