Preliminary study of ultrafiltration of the waste char stream for coal gasification processes

Bench studies of four tubular membranes from Abcor Inc. and Union Carbide Corp. with water or simulated coal gasification excess condensate water containing 0-15Vertical Bar3< by wt of char established temperature and differential pressure limits and showed adverse effects of phenol above 500 mg/l. concentrations and of ammonium bicarbonate above 8800 mg/l. on membrane flux rates. Life tests in process at a Hygas coal gasification plant with an Abcor Inc. proprietary membrane and the Union Carbide Sand Log filter of modified cellulose acetate showed slight decreases in flux rate, depending on the particular membrane, to a constant value of at least 370 gal/sq ft/day. An economic analysis of a design for a commercial Hygas plant recovering 700 gpm showed that an average differential pressure of 200 psi, a temperature of 100/sup 0/F, and an inlet slurry concentration of 15Vertical Bar3< by wt give the lowest investment and operating costs, $8,445,880 and $2,332,900/yr, 22Vertical Bar3< and 25Vertical Bar3< lower, respectively, than for conventional filtration.