Research-cottrell

Research-cottrel, Inc.

Robert J Gleason

Paul L Feldman

Paul E Cooke

Chin T Sui

Mark Richman

A method for reduced temperature operation of flue gas collectors is disclosed wherein the benefits of low temperature operation are made possible by avoidance of the acid dewpoint limit. The process increases the specific collecting area of the collector, results in lower pressure drop through the collector and, where the collector is an electrostatic precipitator, allows improved collection efficiency through higher electric field strength and reduced particulate resistivity.

Method for reduced temperature operation of flue gas collectors

A process uses limestone injection into a combustion boiler burning pulverized coal or liquid hydrogen fuel. Effluent gas from the boiler is humidified and cooled to below 200.degree. F. During the humidifying and cooling step, sulfur dioxide removal occurs in addition to that which takes place in the combustion zone of the boiler. The effluent gas and unreacted alkali is then fed into an electron beam irradiation chamber which produces energetic conditions for rapid reaction of sulfur dioxide and nitrogen oxides in the presence of water vapor. The remaining unreacted alkali reacts rapidly and in-situ with the sulfuric acid and nitric acid formed in the electron beam chamber.

Process for treating flue gas with alkali injection and electron beam

Some flue gas desulfurization processes applied to fuels containing high chloride concentrations are utilizing, or plan to utilize, by-product gypsum from the process stream. The utilization of such a process results in a calcium chloride buildup in the flue gas desulfurization system from fuels or water resource containing significant chlorides which interferes with the absorption and utilization of the lime or limestone reagent. In this invention, a method is used to convert the calcium chloride to a dry material by utilizing flue gas at elevated temperatures, normally found before an air preheater on steam generators used to produce power or any other conventional large size steam boilers. The monohydrate is produced at temperatures above 350.degree. F. By applying this drying process with a power plant system, energy consumed for this drying operation is very efficient.

Process for drying calcium chloride generated in high chloride flue gas

Sulfur dioxide is scrubbed from boiler flue gases in a double-loop alkali scrubber, one a quencher loop and the other an absorption loop. The reagent flow of the two loops is isolated so that none of the reagent from the quencher loop is cycled to the absorber loop and a portion of the make-up water for the quencher loop is received from the absorber loop. By controlling recycled water from a dewatering system and selective utilization of high and low solids streams from the absorber system, the quencher slurry concentration may be controlled and the requirement for new make-up water reduced. The two loop process isolates the main absorber system including the demisters, which are prone to scaling and corrosion, from the evaporative quencher portion of the process. All the recycled water is returned to the evaporative quencher loop and none to the loop controlling the demisters and the primary absorber sections. However, under varying SO.sub.2 feed rates, the recycled water to the quencher loop may be in excess or insufficient for the evaporative material balance of the quencher loop. To compensate for either imbalance, it is necessary to utilize a separator and flow control between the two loops to decrease or increase the water balance flow to the quencher loop while maintaining the absorber loop at the proper operating balance.

SO.sub.2 Scrubbing system for flue gas desulfurization

An impingement or rebound separator for removing mist from a flow of gas consists of a first series of spaced eliminator blades each having at least one of its ends connected to an end plate with the transverse axis of each blade sloping at an angle of about 20.degree. to about 30.degree. to the direction of flow of gas and a second series of spaced eliminator blades each having at least one of its ends connected to an end plate and with the transverse axis of each blade sloping at an angle of about 20.degree. to about 30.degree. to the direction of flow of gas but pitched in the opposite direction to the pitch of the first series of blades. The first and second series of blades defining a separator unit having a plurality of zig-zag or chevron shaped gas flow channels with the longitudinal axes of the blades tilted at an angle of about 30.degree. to about 45.degree. to the direction of flow of the gas stream so that liquid removed from the gas stream will be channeled downstream along the edges of each blade to collection means which may comprise the lower end plates.

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Somerville, NJ, United States of America

Robert J Gleason