A Comparison of Gasification and Incineration of Hazardous Wastes

Gasification is a technology that has been widely used in commercial applications for more than 50 years in the production of fuels and chemicals. Current trends in the chemical manufacturing and petroleum refinery industries indicate that use of gasification facilities to produce synthesis gas (“syngas”) will continue to increase. Attractive features of the technology include: 1) the ability to produce a consistent, high-quality syngas product that can be used for energy production or as a building block for other chemical manufacturing processes; and 2) the ability to accommodate a wide variety of gaseous, liquid, and solid feedstocks. Conventional fuels such as coal and oil, as well as low- or negative-value materials and wastes such as petroleum coke, heavy refinery residuals, secondary oil-bearing refinery materials, municipal sewage sludge, hydrocarbon contaminated soils, and chlorinated hydrocarbon byproducts have all been used successfully in gasification operations. Gasification of these materials has many potential benefits when compared with conventional options such combustion or disposal by incineration. Recently, the U.S. Environmental Protection Agency (EPA) announced that the Agency is considering an exclusion from the Resource Conservation and Recovery Act (RCRA) for listed secondary oil-bearing refinery materials when processed in a gasification system, an exclusion analogous to the one granted for insertion of RCRA listed refinery wastes into the coking process at refineries. In addition, representatives of the gasification industry have asked EPA to consider a broader exclusion that would include gasification of any carbonaceous material, including hazardous wastes from other industrial sectors (e.g., chemical manufacturing) in modern, high-temperature slagging gasifiers. The purpose of this report is to provide an independent, third-party description of waste gasification and to present information that clearly defines the differences between the modern gasification and incineration technologies. The primary focus of this document is the currently proposed exemption for gasification of secondary oil-bearing materials in refineries. The objectives of this report are to: Compare and contrast the process unit operations and chemical reaction mechanisms of gasification and incineration; Cite environmental and regulatory concerns currently applicable to hazardous waste incineration processes and relate them to gasification processes; and Provide a summary of existing process stream characterization data for gasification including information on the data quality, sampling/analytical method applicability, and method development needs.