Bed material agglomeration during fluidized bed combustion. Technical progress report, August 1, 1994--December 31, 1994

摘要

During this quarter, further tests were conducted to determine the effect of localized reducing conditions on bed material agglomeration and deposit formation. Combustion tests were also performed to determine the relationship between defluidization and bed agglomeration. Additionally, tests were conducted to determine the effect of bed material (sand or limestone) on agglomeration. The results from tests conducted this quarter indicate that partial defluidization of the bed does not lead to bed agglomeration. After termination of these tests and examination of the bed material the authors found that agglomerates did not form in the defluidized portion of the bed. Based on examination of the bed, defluidization began as larger (+8 mesh) mineral-rich particles from the coal segregated in the lower portion of the bed, settling on the distributor plate. In the tests at 120% theoretical air, even though defluidization was indicated, no agglomerates were formed. In the tests at 50% theoretical air, agglomerates were formed in the fluidized portion of the bed, due to reducing conditions. Defluidization did not lead to temperature excursions. Also during this quarter, a method was developed to monitor and predict the formation of agglomerates in a fluidized bed. This method is based on measurements of bed pressure fluctuations, using a modified moving average analyses of the pressure data, and provides an effective method to predict agglomerate formation.