Development and Evaluation of a Low-Temperature Gasification Process for Chemical Recovery from Kraft Black Liquor, 1998 International Chemical Recovery Conference Proceedings

A bench-scale test program was conducted by McDermott Technology, Inc. (MTI, formerly the Research and Development Division of Babcock & Wilcox) to obtain proof-of-concept data for B&W’s low-temperature black liquor gasifier design. The test program verified that black liquor gasification (BLG) was possible in a low-temperature, bubbling bed mode. To address incomplete carbon conversion, a novel gasification concept was developed wherein char and tar byproduct combustion is integrated with low-temperature BLG. This process could potentially achieve complete carbon conversion; however, there are significant challenges associated with thermal and physical integration of the processes. Results of a comparative economic analysis indicated that the low-temperature black liquor gasifier design was competitive with conventional technology for incremental capacity increases over a wide range of cost scenarios. Whether a stand alone gasifier or combined cycle system, the resulting energy output would be delivered as fuel gas or electricity instead of high pressure steam. This is expected to better address the energy needs of the future pulp and paper mill. Pressurized, oxygen-blown BLG technology is expected to offer more benefits as a recovery boiler replacement technology. A significant pilot-scale test program is required to address the technical concerns associated with oxygen-blown BLG and demonstrate commercial readiness of the technology.