Methods, apparatus, and compositions for cleaning gas. The use of segmented multistage ammonia-based liquid spray with different oxidation potentials to remove sulfur compounds from gas. The use of different oxidation potentials may reduce unwanted ammonia slip.

Systems and methods for the use of highly reactive hydrated lime (HRH) in circulating dry scrubbers (CDS) to remove sulfur dioxide (SO.sub.2) and other acid gases from the flue gas.

A hydrated lime product exhibiting superior reactivity towards HCl and SO.sub.2 in air pollution control applications. Also disclosed is a method of providing highly reactive hydrated lime and the resultant lime hydrate where an initial lime feed comprising calcium and impurities is first ground to a particle-size distribution with relatively course particles. Smaller particles are then removed from this ground lime and the smaller particles are hydrated and flash dried to form a hydrated lime, which is then milled to a significantly smaller particle size than that of the relatively course particles. The resultant lime hydrate product has available CaOH of greater than 92%, a citric acid reactivity of less than 20 seconds, a BET surface area greater than 18, a D90 less than 10 m, a D50 less than 4 m, a D90/D50 less than 3, and a large pore volume of greater than 0.2 BJH.

A dust collecting module for reducing vibration by maintaining a distance between electrodes includes an arrangement of discharge electrodes and dust collecting electrodes alternately disposed and spaced apart from each other, the discharge electrodes configured to be charged to a predetermined voltage for generating a corona discharge between the discharge electrodes and the dust collecting electrodes, at least one dust collecting electrode of the dust collecting electrodes having a first hole; a first hole jig received in the first hole and fixed to the at least one dust collecting electrode, the first hole jig having a larger thickness than the at least one dust collecting electrode; a first tie rod coupled to the discharge electrodes and configured to pass through and fix the discharge electrodes by being fitted into the first hole jig; and a second tie rod coupled to the dust collecting electrodes to fix the dust collecting electrodes.

A dust collecting module of a desulfurizing apparatus for removing sulfur oxides is easily installed and facilitates the application of a high voltage to discharge electrodes. The dust collecting module includes an arrangement of discharge electrodes and dust collecting electrodes alternately disposed and spaced apart from each other, the discharge electrodes configured to be charged to a predetermined voltage for generating a corona discharge between the discharge electrodes and the dust collecting electrodes; a first setting beam having a plurality of lower slots into which the discharge electrodes are securely inserted; and a lower frame extending in a stacking direction of the discharge electrodes to support the discharge electrodes, wherein the predetermined voltage is applied to the discharge electrodes through the lower frame and the first setting beam. The dust collecting module may further include an insulating connecting member from which the lower frame is suspended.

A desulfurization apparatus employing the limestone-gypsum method has: a desulfurization unit where an absorbing liquid containing a calcium compound contacts with an exhaust gas to remove a sulfur oxide from the exhaust gas; a removal unit for removing gypsum, generated from the sulfur oxide, from the absorbing liquid; and a cleaning unit for cleaning the exhaust gas after contacting, using a cleaning liquid, thereby removing calcium-containing particles from the exhaust gas. In the removal unit, the gypsum is separated into larger gypsum particles and smaller gypsum particles using a cyclone separator, and the absorbing liquid containing the larger gypsum particles is filtrated and the filtrate is supplied to the cleaning unit as the cleaning liquid. An exhaust gas processing system has the desulfurization apparatus, a denitration apparatus and a carbon dioxide recovery apparatus. A post-recovery gas is partially supplied to the desulfurization apparatus as an oxygen source.

Methods and systems for control and adjustment of the feed rate of mercury reemission control additives (MECA) to a wet flue gas desulfurization system. Predetermined sulfite concentration values are compared to actual sulfite concentrations measured in the scrubber liquid. The MECA feed to the recirculating scrubber liquor is then adjusted and regulated as a result of such comparisons.

Systems, apparatuses, and processes for controlling free ammonia in wet flue gas desulfurization processes in which an ammonia-containing scrubbing solution is used to produce ammonium sulfate. Such an apparatus includes an absorber having a contactor region through which a flue gas comprising sulfur dioxide is able to flow and a reaction tank containing a scrubbing solution containing ammonium sulfate. The tank has a sidewall and bottom wall that define the perimeter and bottom of the tank. Lance-agitator units are distributed around the perimeter of the tank, each having a lance that injects a mixture of oxygen and a dilute ammonia-containing fluid toward the bottom of the tank and an agitator that agitates the mixture and propels the mixture toward the bottom of the tank. The apparatus includes a source of the mixture of oxygen and dilute ammonia-containing fluid, and recirculates the scrubbing solution from the tank to the contactor region.

A spray pipe is disclosed, which includes: a pipe portion, having a cylindrical shape, and configured to extend along an axis in the horizontal direction, a distal end portion of the pipe portion being closed; a plurality of nozzle portions configured to guide an absorbing liquid, flowing through the pipe portion in the horizontal direction, upward in a vertical direction, the plurality of nozzle portions being arranged at a plurality of positions on an upper end portion of the pipe portion in the vertical direction; and a leg portion disposed on a lower end portion of the pipe portion in the vertical direction, and having an installation surface along the horizontal direction, wherein the leg portion-is disposed in a state where the installation surface is made to oppositely face a support surface of a pipe support installed on the absorption tower, the support surface extending along the horizontal direction.

The present invention relates to a process for concurrently removing CO.sub.2 and SO.sub.2 from flue gas produced by a combustion process, comprising: (a) performing a combustion process by combusting a fuel and air in a combustion apparatus, thereby creating an exhaust stream comprising CO.sub.2 and SO.sub.2; (b) compressing the exhaust stream in a first compression step, thereby producing a first compressed gas stream; (c) providing a first membrane having a feed side and a permeate side, and being selectively permeable to CO.sub.2 and SO.sub.2 over nitrogen and to CO.sub.2 and SO.sub.2 over oxygen; (d) passing at least a portion of the first compressed gas stream across the feed side; (e) withdrawing from the feed side a CO.sub.2- and SO.sub.2-depleted residue stream; (f) withdrawing from the permeate side at a lower pressure than the first compressed gas stream, a first permeate stream enriched in CO.sub.2 and SO.sub.2; (g) passing the first permeate stream to a separation process that produces a stream enriched in CO.sub.2 and a stream enriched in SO.sub.2.