Demonstration of Steam Reforming Black Liquor Gasification, 1999 Pulping Conference Proceedings

Robert DeCarrera & Mike Ohl

Georgia-Pacific Corporation

The recovery process is an essential component of a pulp and paper mill operation from both an economic and an environmental aspect. Chemicals used in the pulping process are recovered and spent liquor organic solids are converted to energy (typically process steam). The Tomlinson recovery boiler has been the predominant technology; however, fluidized bed combustors have also been used successfully in some segments of the industry. Both technologies have inherent deficiencies including low thermal efficiencies, high capital and maintenance costs, and various operational problems. The Tomlinson unit has the additional potential for smelt-water explosions.

Gasification of black liquor represents a new and better approach for the chemical recovery process and eliminates many of the deficiencies of the Tomlinson and fluid bed combustion technologies. Gasification benefits include increased efficiency in energy conversion and chemical recovery, elimination of the smelt-water explosion hazard, reduced maintenance costs, and significantly lower environmental emissions including particulate, TRS, Nox, VOC, and greenhouse gases. The benefits are particularly attractive to semi-chemical non-sulfur processes that require higher cost auxiliary fuel to sustain combustion of the black liquor, but are also applicable to other spent liquors such as Kraft and sulfite.

The steam reforming technology is ideally suited to the conversion of a variety of variable moisture content organic feedstocks, such as black liquor. MTCI has developed a PulseEnhancedä Steam Reformer technology that is unlike the other gasification processes currently available. MTCI has carried out studies of spent liquor reforming in a 0.5 ton per day black liquor solids pilot unit since 1990. Small scale demonstration units have been run on sludge and Kraft black liquor. Georgia-Pacific in partnership with StoneChem and the U.S. Department of Energy is proposing to build a full scale demonstration unit rated at 200 ton per day in Georgia-Pacific's mill in Big Island, Virginia. This unit would provide the entire chemical recovery needed for the plant in addition to producing process steam.

This paper will describe the MTCI process and the proposed project. This paper will also describe and quantify the expected benefits of the technology including inproved safety, environmental and energy performance.