(Texaco Gasification Process)
The Texaco Gasification Process (TGP) is an entrained-bed, noncatalytic, partial oxidation process in which carbonaceous substances react at elevated temperatures and pressures, producing a gas containing mainly carbon monoxide and hydrogen (see figure below). This product, called synthesis gas, can be used to produce other chemicals or can be burned as fuel. Inorganic materials in the feed melt are removed as a glass-like slag.
This technology has operated commercially for over 40 years with feedstocks such as natural gas, heavy oil, coal, and petroleum coke. The TGP processes waste feedstocks at pressures above 20 atmospheres and temperatures between 2,200 and 2,800 °F.
Slurried wastes are pumped to a specially designed injector mounted at the top of the refractory-lined gasifier. The waste feed, oxygen, and an auxiliary fuel such as coal react and flow downward through the gasifier to a quench chamber that collects the slag. The slag is eventually removed through a lockhopper. A scrubber further cools and cleans the synthesis gas. Fine particulate matter removed by the scrubber may be recycled to the gasifier; a sulfur recovery system may also be added.
After the TGP converts organic materials into synthesis gas, the cooled, water-scrubbed product gas, consisting mainly of hydrogen and carbon monoxide, essentially contains no hydrocarbons heavier than methane. Metals and other ash constituents become part of the glassy slag.
Texaco is designing a transportable system to process about 100 tons of hazardous waste per day. This system would produce about 6 million standard cubic feet of usable synthesis gas per day with a heating value of approximately 250 British thermal units per standard cubic foot.
The TGP can treat the following wastes:
Solids in the feed are ground and pumped in a slurry containing 40 to 70 percent solids by weight and 30 to 60 percent liquid, usually water.
Texaco has demonstrated gasification of coal liquefaction residues, petroleum production tank bottoms, municipal sewage sludge, and surrogate contaminated soil. Texaco is operating a gasification facility at its El Dorado, Kansas refinery that will convert up to 170 tons per day of petroleum coke and Resource Conservation and Recovery Act-listed refinery wastes into usable synthesis gas.
The TGP was accepted into the SITE Demonstration Program in July 1991. A demonstration was conducted in January 1994 at Texaco's Montebello Research Laboratory in California using a mixture of clean soil, coal, and soil from the Purity Oil Sales Superfund site, located in Fresno, California. The mixture was slurried and spiked with lead, barium, and chlorobenzene. Forty tons of slurry was gasified during three demonstration runs. The Demonstration Bulletin (EPA/540/MR-95/514), Technology Capsule (EPA/540/R-94/514a), and Innovative Technology Evaluation Report (EPA/540/R-94/514) are available from EPA.
Findings from the SITE demonstration are summarized below:
EPA PROJECT MANAGER:
Marta K. Richards
U.S. EPA
National Risk Management Research Laboratory
26 West Martin Luther King Drive
Cincinnati, OH 45268
513-569-7692
Fax: 513-569-7676
TECHNOLOGY DEVELOPER CONTACT:
John Winter
Alternate Energy Department
Texaco Inc.
329 N. Durfee Avenue
S. El Monte, CA 91733
310-908-7387
Fax: 310-699-7408