Peabody Process Systems, Inc.

Flakt, Inc.

Abb Environmental Systems, Division of Abb Flakt, Inc.

Even Bakke

Howard P Willett

Gerald E Bresowar

Jonas S Klingspor

Otto Sarmiento

Sulfur oxides (SO.sub.x) are scrubbed from combustion effluents with aqueous limestone slurries with greater efficiency and with economies in capital and operating costs. In the preferred embodiment of a single-loop, open-tower countercurrent limestone wet scrubber, effluent flow rates are greatly increased while L/G values and reaction tank residence times are decreased. Improved entrainment eliminator design, novel nozzle placement and spacing, and the use of a hydrocyclone to separate and recycle smaller particles of limestone from the byproduct gypsum, facilitate these advantages. The limestone is reduced to very fine particles, e.g. about 8.mu. or less with more than 99% of the particle by weight less than 44.mu., and introduced into a scrubbing slurry which is contacted with SO.sub.x -laden effluent.

Wet scrubbing method and apparatus for removing sulfur oxides from

A mist eliminator module, comprising a plurality of smooth parallel mist eliminator blades, preferably formed from a fiber reinforced polymeric material is disclosed. Each blade has in a captive edge portion at least one aperture, which is aligned with apertures in adjacent blades. At least one support rod extends through the apertures, with a plurality of resilient tubular spacers fitted onto the rod between the blades. At least one rigid spacer bar, having a plurality of slots in one face for receiving the free blade edge portions is attached to the other blade edges. A water spray may be directed onto the blades to form a film of water on the blades. The blades may be cleaned in place by removing the spacer bar and separating each blade from an adjacent blade, and manually cleaning each side of each blade. The blades may also be cleaned by operating the tower with the water spray running and the support bar removed so that the blades flex sufficiently to flake off any accumulated solids.

Mist eliminator module and a method for self-cleaning of the same

A flue gas dry scrubbing system achieves higher sulfur dioxide removal efficiency with a better utilization of alkali reagent chemicals as well as increased dry product recovery performance using a combination of spray drying with an alkali reagent slurry and with a recycled stream comprising a mixture of unreacted alkali, sulfite and sulfate reaction products and flyash which directly contacts the sulfur dioxide-containing flue gas. Preferably the recycled mixture contacts the flue gas in the spray dryer. The invention utilizes a splitting method and a splitter apparatus wherein the particle product powder is separated into two fractions for recycling and for product disposal. The rate of splitting is fully adjustable over a wide range.

System for dry scrubbing of flue gas

There is disclosed an electrostatic precipitator with a discharge electrode having dimensional and configuration characteristics which provide high field strength and high current density particularly in a wet electrostatic precipitator. The round cylindrical collector tube of length (L) and with an inner diameter (D) has a coaxially positioned discharge electrode having an electrode supporting mast of a diameter from 0.25 to 0.40 D with an electrically conducting closed screw flight secured to the mast. The screw flight has an overall diameter (d) of from 0.33 to 0.67 D with a pitch of from D-d/2 to D-d and an overall length of from one screw revolution to L-(D-d), preferably one-half L or less and most preferably one to two revolutions. The short screw flight is economical and readily adjusted. The screw flight has a thickness of from about 0.05 to 0.15 inch and has a symmetrically curved outer edge. The collector tube is flared at its lower end to direct water away from the electrode mast as the water is discharged from the tube. The discharge electrode is supported from above and centered by means of adjustable tie rods at its lower end.

Electrostatic precipitator having high strength discharge electrode

A system and process for flue gas processing to remove both gaseous contaminants such as sulfur dioxide and particulate matter such as flyash integrates spray scrubbing apparatus and wet electrostatic precipitation apparatus and provides for the advantageous extraction and utilization of heat present in the flue gas which is being processed. The integrated system and process utilizes a spray scrubbing tower into which the flue gas is introduced and into which aqueous alkali slurry is introduced as spray for sulfur dioxide removal therein. The flue gas leaves the tower moisture laden and enters a wet electrostatic precipitator which includes a heat exchanger where flyash and entrained droplets in the flue gas are removed by electrostatic precipitation and heat is removed from the flue gas. The cleaned flue gas exits from the precipitator and discharges into a stack. The heat removed from the flue gas finds use in the system or otherwise in the steam generation plant. The wet electrostatic precipitator of the integrated system and process includes a portion constructed as a cross flow heat exchanger with flue gas saturated with water vapor moving vertically upwards inside tubes arranged in a staggered pattern and ambient air being pulled horizontally across the outside of those tubes to cool the tube walls and thereby remove heat from the flue gas and cause condensation of water vapor on the inside wall surfaces. The condensate washes the electrostatically collected flyash particles down from the inside tube walls. The heat that is extracted from the saturated flue gas in the wet electrostatic precipitator heat exchanger may be utilized in several different ways, including: (1) for flue gas reheat after the wet electrostatic precipitator; (2) for preheating of combustion air to the steam generator boiler; and, (3) for heating of buildings. The integrated flue gas processing system and process of this invention provides many advantages resulting in increased efficiency and improved economy of flue gas cleaning and wide application of use.

Integrated flue gas processing method

A flue gas dry scrubbing process and system achieves higher sulfur dioxide removal efficiency with a better utilization of alkali reagent chemicals as well as increased dry product recovery performance using a combination of spray drying with an alkali reagent slurry and with a recycled stream comprising a mixture of unreacted alkali, sulfite and sulfate reaction products and flyash which directly contacts the sulfur dioxide-containing flue gas. Preferably the recycled mixture contacts the flue gas in the spray dryer. The invention utilizes a splitting method and a splitter apparatus wherein the particle product powder is separated into two fractions for recycling and for product disposal. The rate of splitting is fully adjustable over a wide range.

Process for dry scrubbing of flue gas

A system for processing hot flue gas to remove both gaseous contaminants such as sulfur dioxide and particulate matter such as flyash integrates spray scrubbing apparatus and wet electrostatic precipitation apparatus and provides for the advantageous extraction and utilization of heat present in the flue gas. The integrated system utilizes a spray scrubbing tower and a wet electrostatic precipitator which includes a portion constructed as a cross flow heat exchanger with flue gas saturated with water vapor moving vertically upwards inside tubes arranged in a staggered pattern and ambient air being pulled horizontally across the outside of those tubes to cool the tube walls and thereby remove heat from the flue gas and cause condensation of water vapor on the inside wall surfaces. The condensate washes the electrostatically collected flyash particles down from the inside tube walls. The heat that is extracted from the saturated flue gas may be utilized for flue gas reheat after the wet electrostatic precipitator or for preheating of combustion air to the steam generator boiler.

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Stamford, CT, United States of America

Even Bakke