Semester

Summer

Date of Graduation

2000

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

M. Ferer.

Abstract

Rigid ceramic filter media are used for removing particulate matter from gas streams at high temperatures. As the particulate matter (dust cake) collects on the surface of the filter, the filtration pressure increases; to maintain an economical operation the dust cake must be removed periodically by back-pulse cleaning. Often the dust cake is not removed completely by the back-pulse pressure and the resulting patchy cleaning affects operation.;The thesis presents the results from a fine scale modeling of the removal of a layer of filter cake by a time dependent pressure pulse. In this model the filter cake is grid in 16,000 imaginary blocks on a filter, of area 160 cm2. The cleaning of the filter is simulated through 10 consecutive cleaning cycles. The model includes both adhesive forces between the blocks of the filter cake and the filter, as well as cohesive forces between neighboring blocks of filter cake.;The evolution of the cleaning from one cycle to the next is studied. The results show that for each cycle, cohesive forces lower the pressures required for cleaning because they increase the stress near broken adhesive bonds. They also cause thicker cakes to be removed more efficiently. An interesting observation is that there are regions where the filter cake is lifted up but not removed during one cycle; many of these regions are removed during the next cycle. The model enables a detailed quantitative investigation of way this effect depends on the filter cake thickness and the strength of the applied pressure pulse.

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