Low-temperature catalytic gasification of wet industrial wastes. FY 1993--1994 interim report

Abstract

SummaryProcess development research is continuing at Pacific Northwest Laboratory on a low-temperature, catalytic gasification system that has been demonstrated to convert organics in water (dilute or concentrated) to useful and environmentally safe gases. The system, licensed under the trade name Thermochemical Environmental Energy System (TEESa), treats a wide variety of feedstocks ranging from hazardous organics in water to waste sludges from food processing. The current research program is focused on the use of continuous-feed, tubular reactors systems for testing catalysts and feedstocks in the process. A range of catalysts have been tested, including nickel and other base metals, as well as ruthenium and other precious metals.Results of extensive testing show that feedstocks, ranging from 2% para-cresol in water to potato waste and spent grain, can be processed to > 99% reduction of chemical oxygen demand (COD). The estimated residence time is about 10 min at 350°C and 21 MPa, not including about 3 min required in the preheating zone of the reactor. The liquid hourly space velocity varies from 1.0 to 4.8 L feedstocWL catalystlhr, depending on the feedstock. The product fuel gas contains from 40% up to 75 % methane, depending on the feedstock. The balance of the gas is mostly carbon dioxide with < 5 % hydrogen and usually < 1 % ethane and higher hydrocarbons. The byproduct water stream carries residual organics from 10 to 1000 mg1L COD, depending on the feedstock.

Chemical Processing in High-Pressure Aqueous Environments. 6. Demonstration of Catalytic Gasification for Chemical Manufacturing Wastewater Cleanup in Industrial Plants

“…The steady operation correlates with reduced chloride in the feedstock following removal of chloride from the ion-exchange resin bed. Bench-scale testing (without the chloride contamination problem) have shown high, stable catalytic activity throughout a 17 day period . Pressure variations in the reactor system resulting from control valve instability also may have contributed to the higher effluent levels and the higher-than-expected hydrogen level in the product gas.…”

“…Bench-scale testing (without the chloride contamination problem) have shown high, stable catalytic activity throughout a 17 day period. 13 Pressure variations in the reactor system resulting from control valve instability also may have contributed to the higher effluent levels and the higherthan-expected hydrogen level in the product gas. On the last day of the test, the system was shut down, cooled, and restarted to evaluate the robustness of the operating system and the catalyst.…”

Low-temperature catalytic gasification of food processing wastes. 1995 topical report

“…The bench-scale unit, described in detail in an earlier report [8], consisted of a 6 ft long x 1 in. I.D.…”

Chemical Processing in High-Pressure Aqueous Environments. 5. New Processing Concepts

“…Wet biomass feedstocks that have been processed in the bench-scale tubular reactor system include spent grain (4 wt % dry solids), rum vinasse (5 wt % dry solids), and potato crumbs (14 wt % dry solids) (Elliott et al, 1995). Greater than 98% reduction of chemical oxidation demand (COD) was achieved for the spent grain at liquid hourly space velocities up to 3.5 h -1 .…”

“…The development of suitable catalysts has been critical to enabling such benefits as lower temperature operation, lower cost materials, highly efficient heat recovery, desirable carbon conversions, and gas product yields and eliminating oxygen feedstock requirements. A wide range of catalysts have been evaluated for this process (Elliott et al, 1993(Elliott et al, , 1995. Both commerciallyavailable catalysts and special formulations have been tested.…”