Masters Theses

Date of Award

3-1981

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

H. J. Wilkerson

Committee Members

R. J. Krane, A. J. Edmondson, R. L. Maxwell

Abstract

Coal feeders for fluidized bed combustors must provide a uniform, regulated supply of coal to the combusting bed for efficient operation. Many of the fluidized bed coal feeders used in the past have suffered from plugging, maldistribution, and other problems. Thus, further coal feeder development work is necessary before the fluidized bed combustion process can become a viable alternative for power production. A project has been initiated for the development and evaluation of coal feeders which combine the fluidization and coal feeding functions. The combination of these two functions can potentially solve several of the problems experienced with past coal feeder designs.

An experimental ambient temperature atmospheric fluidized bed test facility has been designed and constructed for the evaluation of the combined function coal feeders. Methods were selected and developed to evaluate both the fluidization and coal feeding performance of the feeders. Fluidization evaluation was accomplished by measuring the expansion of the fluidized bed and the magnitude and frequency of the pressure drop fluctuations through it. The coal feeding distribution measurement system utilized a magnetically susceptible imitation coal material as a tracer. Specially designed sample probes were used to collect bed material samples during coal feeding tests. The samples were analyzed to determine the imitation coal distribution within the bed.

Basic performance tests were conducted on the experimental facility with a perforated plate air distributor. The fluidization produced by the distributor was characterized by large bubbles or slugs of air which caused significant displacements of the bed material as they rose through it. An in-bed pipe grid combined coal feeder and air distributor was designed and tested. The initial configuration of this feeder did not give uniform fluidization, but a revised configuration did give uniform fluidization. Both feeder configurations distributed coal to all portions of the bed. Although the local coal concentrations varied from position to position within the bed and from test to test, the average variations were within reasonable limits.

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