Foster Wheeler Pyropower Inc. has supplied a 73.7 kg/s bubbling fluidized bed boiler to MacMillan Bloedel's Powell River paper mill (now Pacifica Paper). The BFB boiler was designed to fire a fuel mixture of a mill effluent sludge and a hog fuel (bark) that is contaminated with seawater. Due to its very high alkali content and low ash content, the fuel is prone to cause problems such as agglomeration in the fluidized bed. Foster Wheeler and MacMillan Bloedel took a proactive approach to quantify likely problems and to identify solutions. A 200 hour-long test program was carried out at Foster Wheeler Development Corporation in Livingston, New Jersey with the Powell River feedstock. This paper provides the project background, an outline of the test facility, test matrix, fuel and bed material characteristics, followed by a test process overview. A summary of fuel alkali related agglomeration mechanism in fluidized bed is also included. The paper offers further observations on in-bed alkali accumulation as well as examinations of different types of bed material agglomerates found during the tests. A recommended boiler operating strategy for preventing agglomeration in the BFB boiler developed based on the test results is described. These recommendations have been successfully implemented during the start up of the boiler. The boiler has been in operation since November 1997. Boiler performance tests completed in April 1998 have demonstrated all guaranteed process conditions.
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