Semester

Fall

Date of Graduation

1998

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Eric K. Johnson.

Abstract

When coal undergoes combustion, not all the carbon in the coal may be consumed. This is due to improper mixing of reactants, proximity of cold surfaces and the desire to operate combustors at lower temperatures. Depending on the type of coal and the operating conditions of the combustor, there may be about 4--6% of unburned carbon in the refuse. This unburned carbon is carried along in the flow of gases and ash. If the combustion gas products are to pass through a high temperature gas filtration system, ash and unburned carbon are deposited on the wall of a candle filter. Today, candle filters are employed for gas cleanup at temperatures of the order of about 1500°F.;During surface regeneration operation using air, the amount of oxygen available for reaction is at least two orders of magnitude greater than that available in the combustion products. This oxygen, combined with the prevalent temperatures will cause burning of the previously unburned carbon. The heat generated will result in a significant local rise in temperature of the deposits where the oxygen is consumed. These temperatures may lead to local sintering which may then lead to formation of the residual ash.;The present research involves: (1) Estimating the carbon concentration in the ash deposit; (2) Developing a simple combustion model to estimate the volumetric heat generation rate; (3) Developing a numerical model to obtain the temperature profile in the ash deposit, during regular filtration and during surface regeneration; (4) Determining if sintering occurs in the ash deposit.

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