The applicability of soda ash manufacturing wastes to flue gas desulfurization
Scroggins, James Edwin
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The objectives of this study were two-fold: 1) to determine the efficacy of low grade sodium alkalies in wet SO2 scrubber applications and 2) to use a simplified method for comparing the costs of sodium alkali SO2 scrubbing systems and limestone scrubbing systems. The materials tested were waste streams produced in the manufacturing of soda ash. Experiments were conducted on full scale industrial SO2scrubbers to determine optimum scrubber operating conditions for each of the streams that were tested. All the materials tested performed well in the test scrubber removing up to 97 per cent of the SO2 from the gas stream. Crystallizer purge liquor was found to cause silica scale in the test scrubber which could be controlled by chemical treatment. A standardized method of cost estimation was used to obtain relative costs for sodium alkali and limestone scrubbers. The tests which were conducted showed that capital, operating and maintenance costs of sodium alkali scrubbers should be less than a limestone scrubber of the same size and type. The availability of the test scrubber was higher than the availability given in the literature for a limestone scrubber. This information was then used to develop generalized descriptions of S2 scrubbing applications where sodium carbonate chemicals were more cost effective than limestone systems. It was found that sodium alkalies could be competitive with limestone in applications where the sulfur content of the coal is 3 per cent and the cost of the sodium alkali was less than $75/ton.