Date of Award


Document Type


Degree Name

Master of Science (MS)


Chemical Engineering


The absorption of sulfur dioxide from a synthetic flue gas by fly ash was investigatedo Tests were made by passing a flue gas mixture of known composition over various samples of lignite fly ash and then analyzing the samples by means of x~ray fluorescence

The significance of time, temperature, partial pressure of sulfur dioxide in the flue gas, and the composition of the ash was determined by statistical analysis„ Analysis of variance indicated that the four variables studied all had a significant effect on the amount of sulfur dioxide absorbed by the fly ash at the 99o5 percent confidence level,, Five of the six two-way interactions and two of the four three-way interactions were also significant

At 1,600° F there was approximately a 20 percent increase in the sulfur content (as SO3) of certain fly ash samples investigated after 17-1/2 hours of exposure time0 Other samples of different initial composition absorbed less S02„ This investigation did indicate that a high initial sodium or calcium content increases the amount of SO2 that fly ash will absorb

Comparison tests were made using alkalized alumina at 625° F and 1,100° Fo Alkalized alumina absorbed sulfur dioxide more readily than fly ash at 625° Fc Fly ash was a better absorbent during the first 10 hours of exposure at 1,100° F„ At 1,600° F the fly ash absorbed SO2 as well as the alkalized alumina did at 625° F0 Whether the alkalized alumina was in pellet form or crushed, the amount of SO2 absorbed remained approximately the same over the time intervals studied

The high temperatures necessary for appreciable absorption of S02 by lignite fly ash are such that use in equipment auxiliary to a boiler would not be feasible, but reinjection directly into the boiler may be feasible if the additional ash load can be tolerated