Partial liquefaction of coal by flash hydropyrolysis. Final technical report

This report summarizes 4-2/3 years of work at Rockwell International for the US Department of Energy on research and development for partial liquefaction of coal by flash hydropyrolysis in an entrained-flow, short-residence-time reactor system. The program comprised three distinct phases of work. In Phase I, a reliable method for feeding pulverized coal to the reactor in dense phase was developed, and the mixing behavior of candidate injectors was investigated. Phase II was reactor development testing, first at a coal feed rate of 1/4 ton/h and later at 1 ton/h. Coal conversions and liquid hydrocarbon recoveries were sufficiently promising that the 1-ton/h reactor development facility was upgraded to a PDU in Phase III. Routine reactor operation with caking western Kentucky bituminous coals was established. Overall carbon conversions typically were in the 55 to 65% range. Carbon conversion to liquid hydrocarbons ranged between 30 and 40%, typically, with as much as 11% carbon conversion to BTX aromatics. Good progress was made toward characterizing the quality and properties of the liquid product. Most of the remaining converted carbon was high-value gases (e.g., CH/sub 4/, CO, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/) useful as pipeline SNG and chemical plant feed stocks. The unconverted carbonmore » was collected as a fine granular dry char suitable for direct feeding to a partial-oxidation coal/char gasifier for hydrogen production. The commercial potential of flash hydroliquefaction was assessed by Scietific Design Company, Inc., as part of Phase III. Based on a grass-roots, mine-mouth plant producing an energy equivalent of 100,000 bbl/day of crude oil, they estimated 74% potential overall thermal efficiency and an average product selling price lower than those estimated for several competing coal liquefaction processes.« less