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Abstract

A method of removing particulates and sulfur oxides from a hot gas by controllably contacting the hot gas in a first spray-dryer zone with a selected chemically reactive absorbent for the sulfur oxides and then sequentially contacting the hot gas with the absorbent in a second fabric filter zone. The preferred absorbents are calcium oxide, calcium hydroxide, sodium carbonate, sodium bicarbonate and sodium hydroxide. The selected absorbent dissolved or dispersed in an aqueous medium is controllably introduced into the spray dryer, together with the hot gas, in an amount and at a rate to react in the spray dryer with only a portion of the sulfur oxides in the hot gas to produce a dry particulate reaction product consisting of calcium or sodium sulfites and sulfates, together with sufficient unreacted absorbent of enhanced reactivity for subsequent reaction in the second zone with the remaining sulfur oxides, all being entrained in a substantially water-unsaturated gas of reduced sulfur oxide content. This resultant gas containing the dry particulate reaction product and unreacted absorbent is transferred into the second zone where it is directly impinged upon an upstream surface of a gas-permeable porous fabric so that a substantially uniform coating of the dry particulate product and unreacted absorbent is formed and maintained, under steady-state conditions, on the upstream surface of the fabric. Further reaction occurs in this second fabric filter zone between the absorbent, which has enhanced reactivity, and the sulfur oxides present in the gas passing through the fabric filter so that the gas exiting from the downstream surface of the fabric is substantially free of particulate matter and has a substantially reduced sulfur oxide content.

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First Claim