Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: There is disclosed a fly ash utilization system and process for the removal of sulfur dioxide from the flue gas of coal fired boilers. The principal features of the invention are the maintaining of high ionic concentration in a closed loop, water balanced system which is operated at a low pH, i.e. less than 4 and preferably less than 3. The ionic concentration of the scrubber slurry is maintained at at least 5,000 parts per million of alkali metal cations, preferably over 10,000 parts per million, at least a substantial portion of which has been leached from fly ash.The ionic concentration of the scrubber slurry is maintained at a high level by either providing small diked areas in a waste pond for settling of undissolved solids wherein the returned supernatant has a high ionic concentration. A thickener and filter system may also be used to recover high ionic concentration supernatant for return to the scrubber.

Abstract: A process for steam stripping sulfur dioxide from a buffered aqueous solution in which it is absorbed in a flue gas desulfurization process is carried out at pressure greater than atmospheric. The process of pressure stripping of sulfur dioxide surprisingly results in increased steam economy as compared to stripping at atmospheric pressure and yields sulfur dioxide vapor which can be directly condensed to a liquid product with ordinary cooling water, eliminating the need for drying, refrigeration or compression operations. The high temperatures corresponding to high steam pressures enable economical use of stripping vessel overheads for preheating operations also. Stripping at pressures of 50 to 65 psig results in steam requirements which are only one-third to one-half of that at atmospheric pressure stripping. At the high pressures lower gas flow rates permit the use of more compact stripping equipment.