This report covers work conducted by Rockwell International under Amendment 5 to Subcontract STR/DOE-12 of Cooperative Agreement DE-AC-05-80CS40341 between St. Regis Corporation (now Champion International) and the Department of Energy (DOE). The work has been designated Phase 2D of the overall program to differentiate it from prior work under the same subcontract. The overall program is aimed at demonstrating the feasibility of and providing design data for the Rockwell process for gasifying Kraft black liquor. In this process, concentrated black liquor is converted into low-Btu fuel gas and reduced melt by reaction with air in a specially designed gasification reactor.
This project, conducted under The United States Department of Energy (DOE) Cooperative Agreement DE-FC36-94GO10002/A002, was part of a multiple-phase effort to develop technologies that improve the energy efficiency and economics of chemical process recovery in the pulp and paper industry. The approach taken was to consider two major alternatives in two phases. Phase I, conducted previously, considered means to improve pulp mill recovery boilers using high-solids advanced combustion of black liquor; while this project, Phase la, considered means to recover kraft pulping mill process chemicals by low-temperature black liquor gasification. The principal steps previously proposed in this program were: (1) Evaluate these two technologies, high-solids advanced combustion and gasification, and then select a path forward using the more promising of these two options for future work. (2) Design and construct a pilot-scale unit based on the selected technology, and using that unit, develop the precompetitive data necessary to make commercialization attractive. (3) Develop and deploy a first-of-a-kind (FOAK) commercial unit in a kraft pulp mill. Phase I, which evaluated the high-solids advanced combustion option, was concluded in 1995. Results of that project phase were reported previously. This report describes the work conducted in Phase Ia. The work is described in Sections 1 through 4 and six appendices provide additional detail.
Black Liquor Gasification (BLG) is a first of its kind to guide chemical engineers, students, operators of paper plants, technocrats, and entrepreneurs on practical guidelines and a holistic techno-enviro-economic perspective applicable to their future or existing projects based on the treatment of black liquor for energy production. BLG describes the gasification process as a more efficient alternative to current processes for the conversion of black liquor biomass into energy. BLG operates largely in sync with other methods to improve pulp-making efficiency. This book explains how BLG offers a way to generate electricity and to reclaim pulping chemicals from black liquor, and why BLG would replace the Tomlinson recovery boiler for the recovery of spent chemicals and energy. Describes the utilization of black liquor as a source of energy Provides a detailed account of black liquor gasification processes for the production of energy and chemicals from black liquor Provides guidelines to chemical engineers for the treatment of black liquor
This project phase addresses the following workscope: Conduct bench-scale tests of a low temperature, partial combustion gasifier; Prepare a gasifier pilot-plant preliminary design and cost estimate and prepare a budgetary cost estimate of the balance of the program; Outline a test program to evaluate gasification; Prepare an economic/market analysis of gasification and solicit pulp and paper industry support for subsequent phases; and Prepare a final report and conduct a project review prior to commencement of work leading to construction of any pilot scale components or facilities. The primary accomplishments included completion of installation of the bench-scale black liquor gasifier and supporting systems, preparing test plans and related safety procedures and detailed operating procedures, defining the functional design requirements and outlining the test plans for the pilot-scale gasifier, and preparing a preliminary economic assessment of the black liquor gasifier. This work accomplished under Phase 1a during this period is further described by task.
Pyrolysis is an endothermic process. The heat of reaction is provided either by partial combustion of the waste or by heat transfer from an external combustion process. In one proposed system black liquor is pyrolized in a fluidized bed to which heat is added through a series of pulse combustor tail pipes submerged in the bed material. This system appears promising because of the relatively high heat transfer in pulse combustors and in fluidized beds. Other advantages of pulse combustors are discussed elsewhere. The process is, however, only economically viable if a part of the pyrolysis products can be used to fire the pulse combustors. The overall goals of this study were to determine: (1) which is the limiting heat transfer rate in the process of transferring heat from the hot combustion products to the pipe, through the pipe, from the tail pipe to the bed and through the bed; i.e., whether increased heat transfer within the pulse combustor will significantly increase the overall heat transfer rate; (2) whether the heat transfer benefits of the pulse combustor can be utilized while maintaining the temperature in the bed within the narrow temperature range required by the process without generating hot spots in the bed; and (3) whether the fuel gas produced during the gasification process can be used to efficiently fire the pulse combustor.
