Abstract: An apparatus is disclosed including a desulfurization device which removes sulfur oxides contained in boiler flue gas, a spray drying device which sprays desulfurization waste water discharged from the desulfurization device and which dries the waste water by introducing a drying gas, a flue gas supplying line L13 which returns, to a main flue L11, flue gas obtained after the desulfurization waste water is evaporated and dried, an alkaline agent supplying unit which adds an alkaline agent to a desulfurization waste water line L21, and a pH meter which measures the pH in the desulfurization waste water at locations before and after the alkaline agent supplying unit in the desulfurization waste water line L21, wherein the alkaline agent is added in accordance with a measurement result of a measured pH to cause the desulfurization waste water added with the alkaline agent to have a pH fall within a predetermined pH.

Abstract: The present invention relates to a method for recovering acid gas from an absorbent rich on gaseous acid gas, in which the energy used for separation of absorbent and acid in a stripping column is reduced by recycling heat transfer fluid from the stripper off gas in an energy efficient manner. The invention further relates to a plant suitable for carrying out said method.

Abstract: This invention relates to processes for the selective removal of contaminants from effluent gases. More particularly, various embodiments of the present invention relate to selective removal and recovery of sulfur dioxide from effluent gases in a regenerative sulfur dioxide absorption/desorption process that achieves favorable energy efficiency. Energy is recovered from a wet stripper overhead gas stream produced in the desorption cycle by indirect transfer of heat from the stripper gas to a cooling medium and used to generate steam for use in stripping contaminants from the absorption liquor. The absorption zone may optionally be cooled to enhance the capacity of the absorption medium for absorption of a contaminant gas, thereby lowering the volume of absorption medium and contaminant-enriched absorption liquor that must be pumped, handled, heated and cooled in the absorption/desorption cycle.

Abstract: The invention relates to a CO2 y SO2 capture method comprising the following steps consisting in: a) introducing an aqueous stream of a hydroxide of an alkali or alkaline-earth metal and another gas stream of CO2 into a bubble column purifier/reactor, in order to form a carbonate of the alkali or alkaline-earth metal; b) introducing the carbonate of the alkali or alkaline-earth metal into a bubble column purifier/reactor, into which a stream of a gas mixture of CO2 and SO2 is introduced in order to form sulphite of an alkali or alkaline-earth metal and carbon dioxide; c) transforming the sulphite from step (b) into sulphate of said metal by means of oxidation with air; and d) re-circulating the unreacted CO2 produced during step (b) by reacting the slurry with the SO2, in the reactor from step (a).

Abstract: To include a boiler 11 that burns fuel F, an air heater 13 that recovers heat of flue gas 18 from the boiler 11, a first precipitator 14 that reduces dust in the flue gas 18 after heat recovery, a desulfurizer 15 that reduces sulfur oxides in the flue gas 18 after dust reduction by an absorbent, a dewaterer 32 that reduces gypsum 31 from desulfurization discharged water 30 discharged from the desulfurizer 15, a spray drying device 34 including an atomizer that atomizes a dewatering filtration fluid 33 discharged from the dewaterer 32, and a flue-gas introducing line L11 that introduces a part of the flue gas 18 into the spray drying device 34.

Abstract: A contaminant gas is removed from a feed gas in two absorption and stripping circuits operated in tandem. The gas is first passed through a rich gas absorber producing a rich absorption liquor from which contaminant gas is stripped in a rich liquor stripper. A lean gas exiting the rich gas absorber is passed through a lean gas absorber, producing a lean absorption liquor from which contaminant gas is stripper in a lean liquor stripper. Regenerated absorption media exiting the respective strippers are recirculated to the respective absorbers.

Abstract: The present invention provides a method of treating an off-gas stream (80) comprising NH3 and H2S to provide a sulphate stream (910), the method comprising the steps of: (i) providing a first off-gas stream (80) comprising NH3, H2S, CO2 and optionally one or more of HCN, COS and CS2; (ii) passing the first off-gas stream (80) to an incinerator (300) to oxidize NH3, H2S, and optionally one or more of HCN, COS and CS2 to provide a second off-gas stream (310) comprising N2, H2O, SO2 and CO2; (iii) scrubbing the second off-gas stream (310) with a first aqueous alkaline stream (380, 876a) in a caustic scrubber (350) to separate SO2 and a part of the CO2 from the second off-gas stream to provide a spent caustic stream (360) comprising carbonate and one or both of sulphite and bisulphite and a caustic scrubber off-gas stream (370) comprising N2 and CO2; and (iv) passing the spent caustic stream (360) to an aerator (900) comprising sulphur-oxidizing bacteria in the presence of oxygen to biologically oxidize sulphite

Abstract: A wet scrubber (8) for cleaning a process gas containing sulphur dioxide comprises an absorption vessel (40) operative for bringing the process gas into contact with an absorption liquid to absorb sulphur dioxide from the process gas. The wet scrubber (8) further comprises an acidification system (90) operative for mixing absorption liquid that has absorbed sulphur dioxide from the process gas with a carbon dioxide containing gas, an absorbent dissolution tank (54) operative for adding an absorbent material to at least a portion of the absorption liquid, and a return pipe (104) operative for returning to the absorption vessel (40) at least a portion of the absorption liquid that has been mixed with the carbon dioxide containing gas.

Abstract: A method of scrubbing flue gas includes introducing flue gas comprising an acidic gas through an inlet into a tower; spraying an acid-absorptive fluid into the tower such that the acid-absorptive fluid contacts the flue gas; accumulating the acid-absorptive fluid in a recycle tank portion of the tower; and introducing an oxygen-containing gas into the acid-absorptive fluid in the recycle tank portion of the tower, wherein the oxygen-containing gas is introduced through at least one opening of an aerator, each of the at least one openings are positioned to release the oxygen-containing gas at least at a distance greater than or equal to a predetermined radial distance from the flue gas inlet, the predetermined radial distance being equal to at least 10% of a diameter of the recycle tank portion of the tower.

Abstract: Processes for recovering ammonia from an ammonium sulfate stream include reacting the ammonia sulfate stream with a lime slurry to form a slurry comprising calcium sulfate and ammonia; providing the slurry comprising calcium sulfate and ammonia to a stripper configured to recover the ammonia from the slurry; utilizing a heat source from a chilled ammonia process to the stripper; and extracting an ammonia vapor stream from the stripper. Also disclosed are systems for performing the processes.

Abstract: This invention provides novel processes utilizing compositions comprising substituted polyamines as acid gas scrubbing solutions and methods of using the compositions in an industrial system. The invention relates to the use of such polyamine compounds in industrial processes to remove acidic contaminants from natural and industrial fluid streams, such as natural gas, combustion gas, natural gas, synthesis gas, biogas, and other industrial fluid streams. The compositions and methods of the invention are useful for removal, absorption, or sequestration of acidic contaminants and sulfide contaminants including CO2, H2S, RSH, CS2, COS, and SO2.

Abstract: This invention provides novel compositions comprising substituted polyamines as acid gas scrubbing solutions and methods of using the compositions in an industrial system. The invention relates to the use of such polyamine compounds in industrial processes to remove acidic contaminants from natural and industrial fluid streams, such as natural gas, combustion gas, natural gas, synthesis gas, biogas, and other industrial fluid streams. The compositions and methods of the invention are useful for removal, absorption, or sequestration of acidic contaminants and sulfide contaminants including CO2, H2S, RSH, CS2, COS, and SO2.

Abstract: An apparatus 100 for scrubbing flue gas 122, the apparatus 100 including a tower 140 having an inlet 120 receiving a flow of flue gas 122 and a recycle tank portion 142; a fluid 162 disposed in the recycle tank portion 142; and an aerator 150 having at least one opening 152 for introduction of an oxygen-containing gas 154 into the fluid 162, wherein the at least one opening 152 is positioned to release the oxygen-containing gas 154 at least at a distance greater than or equal to a predetermined radial distance F from the inlet 120, the predetermined radial distance F being equal to at least 10% of a diameter of the recycle tank portion 142.

Abstract: An air pollution control system 10A according to the present invention includes: a boiler 11 that burns fuel; NOx removal equipment 12 that decomposes nitrogen oxides in flue gas 25 discharged from the boiler 11; a desulfurizer 15 that causes sulfur oxides in the flue gas 25 having passed through the NOx removal equipment 12 to be absorbed by an absorbent, thereby reducing sulfur oxides in the flue gas 25, a waste-water treatment device 16 including a solid-liquid separating unit 31 that separates desulfurized waste water 28 discharged from the desulfurizer 15 into a solid fraction and a liquid fraction, and a mercury removing unit 32 that removes mercury in the desulfurized waste water 28; and a treated waste-water returning unit (a makeup water line) 17 that returns at least a part of treated waste water 40 treated by the waste-water treatment device 16 to the desulfurizer 15.

Abstract: An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

Abstract: An process for efficiently deacidizing a gaseous mixture is described. The process utilizes a self-concentrating absorbent that absorbs an acid gas at reduced overall energy costs for the deacidizing operation.

Abstract: An improved process for deacidizing a gaseous mixture using phase enhanced gas-liquid absorption is described. The process utilizes a multiphasic absorbent that absorbs an acid gas at increased rate and leads to reduced overall energy costs for the deacidizing operation.

Abstract: The present invention is directed to an improved method and system for separating and purifying gas using gas-liquid absorption. According to this invention, the method is carried out in an absorber, where a liquid absorbent, a gas mixture containing a gas to be absorbed were introduced from an inlet. During absorption, the second liquid phase was separated out from the absorbent. The absorbed gas was accumulated in one of liquid phases. After absorption, two liquid phases were separated. One of the liquids with rich absorbed gas was forward to regenerator. After regeneration, the liquid was cycled back to absorber. The liquid phase with lean absorbed gas was back to absorber directly to complete the cycle.

Abstract: The gaseous effluent flowing in through line 1 is contacted in absorption zone ZA with the liquid absorbent solution flowing in through line 9. The gaseous effluent depleted in acid compounds is discharged through line 2. The absorbent solution laden with acid compounds is discharged through line 3. The absorbent solution once laden with acid compounds comprises two phases: a first phase poor in acid compounds and a second phase rich in acid compounds. The two phases are separated in zone ZS. The first phase is recycled through lines 5 and 9 to absorption zone ZA. The second phase is fed through line 4 into regeneration zone ZR. In zone ZR, the acid compounds are separated from the absorbent solution. The acid compounds are discharged through line 7. The regenerated absorbent solution is recycled through lines 6 and 9 to zone ZA.

Abstract: A method and system for controlling one or more emissions includes introducing ammonia to react with at least a portion of sulfur trioxides in an exhaust emission and result in at least one or more ammoniated compounds. At least a portion of fly ash particles and the ammoniated compounds in the exhaust emission are precipitated. At least a portion of the ammonia from the precipitated ammoniated compounds is recovered with heat from the exhaust emission and the recovered ammonia is reused.

Abstract: Sulphur dioxide is removed from gas streams by contacting the gas stream with an absorbing medium containing an amine capable of forming an amine salt, heat stable salt and sulfite. The level of heat stable salt is selected such that during the regeneration process of the sulphur dioxide rich amine, the pH of the absorbing medium is at a selected level or below when the level of sulfite in the absorbing medium has been reduced to a specified value. The amine that absorbs the sulphur dioxide has a pKa less than that of sulfite. If the absorbent includes a diamine, then the spent absorbing medium is regenerated under conditions such that at least one amine group remains in salt form.

Abstract: The present invention provides methods and apparatus for treating flue gas containing sulfur dioxide using a scrubber, and more particularly relates to recovering gypsum and magnesium hydroxide products from the scrubber blowdown. The gypsum and magnesium hydroxide products are created using two separate precipitation reactions. Gypsum is crystallized when magnesium sulfate reacts with calcium chloride. Magnesium hydroxide is precipitated when magnesium chloride from the gypsum crystallization process reacts with calcium hydroxide. The process produces a high quality gypsum with a controllable pH and particle size distribution, as well as high quality magnesium hydroxide.

Abstract: At least one of the multiple process parameters (MPPs) is a controllable process parameter (CTPP) and one is a targeted process parameter (TPP). The process also has a defined target limit (DTV) representing a first limit on an actual average value (AAV) of the TPP. A first logical controller predicts future average values (FAVs) of the TPP based on the AAVs of the TPP over a first prior time period and the DTV. A second logical controller establishes a further target limit (FTV) representing a second limit on the AAV of the TPP based on one or more of the predicted FAVs, and also determines a target set point for each CTPP based on the AAVs of the TPP over a prior time period and the FTV. The second logical controller directs control of each CTPP in accordance with the determined target set point.

Abstract: A controller directs performance of a process having multiple process parameters (MPPs), including a controllable process parameter (CTPP), a targeted process parameter (TPP), a defined target value (DTV) representing a limit on an actual average value (AAV) of the TPP over a defined moving time period of length TPLAAV. A storage device stores historical data representing the AVs of the TPP at various times over a prior time period (PTP) having a length of at least TPLAAV. A processor predicts future average values (FAVs) of the TPP over a future time period (FTP) based on the stored historical data and the current values of the MPPs. The processor also determines a target set point for each CTPP based on the predicted FAVs, the current values of the MPPs and the DTV, and directs control of each CTPP in accordance with the determined target set point for that CTPP.

Abstract: A process and apparatus for removing SO2, NO, and NO2 from a gas stream having the steps of oxidizing a portion of the NO in the flue gas stream to NO2, scrubbing the SO2, NO, and NO2 with an alkali scrubbing solution, and removing any alkali aerosols generated by the scrubbing in a wet electrostatic precipitator. The process can also remove Hg by oxidizing it to oxidized mercury and removing it in the scrubbing solution and wet electrostatic precipitator. Alkali sulfates, which are valuable fertilizers, can be withdrawn from the rubbing solution.

Abstract: A process and apparatus for removing SO2, NO, and NO2 from a gas stream having the steps of oxidizing a portion of the NO in the flue gas stream to NO2, scrubbing the SO2, NO, and NO2 with an ammonia, ammonium hydroxide, alkali hydroxide or carbonate scrubbing solution, regenerating the scrubbing solution with limestone, and removing any particulate matter and aerosols generated by the scrubbing step in a wet electrostatic precipitator. The process can also remove Hg by oxidizing it to oxidized Hg and removing it in the wet electrostatic precipitator. The scrubbing solution is preferably regenerated with limestone or magnesium, and results in a Group II sulfite or sulfate that can be recovered and sold, or landfilled.

Abstract: A process for the production of sulphuric acid from a sulphur dioxide containing feed gas with concentration of SO2 fluctuating between 0 and 100 mole % SO2 comprising the steps of contacting the feed gas with an aqueous solution comprising 0–50% by weight H2SO4 at a temperature between the freezing point of said aqueous solution and 80° C.; and during the contact of the feed gas with the aqueous solution absorbing at least a part of SO2 in the feed gas in the aqueous solution or desorbing at least a part of SO2 from the aqueous solution, wherein the at least a part of SO2 is desorbed by stripping the aqueous solution with the feed gas and passing at least part of the thus treated feed gas to a sulphuric acid plant.

Abstract: A process and apparatus for removing SO2, NO, and NO2 from a gas stream having the steps of oxidizing a portion of the NO in the flue gas stream to NO2, scrubbing the SO2, NO, and NO2 with an ammonia scrubbing solution, and removing any ammonia aerosols generated by the scrubbing in a wet electrostatic precipitator. The process can also remove Hg by oxidizing it to HgO and removing it in the wet electrostatic precipitator. Ammonium sulfate, a valuable fertilizer, can be withdrawn from the scrubbing solution.

Abstract: A process and apparatus for removing SO2, O, and NO2 from a gas stream having the steps of oxidizing a portion of the NO in the flue gas stream to NO2, scrubbing the SO2, NO, and NO2 with an ammonia scrubbing solution, and removing any ammonia aerosols generated by the scrubbing in a wet electrostatic precipitator. The process can also remove Hg by oxidizing it to HgO and removing it in the wet electrostatic precipitator. Ammonium sulfate, a valuable fertilizer, can be withdrawn from the scrubbing solution.

Abstract: A scoop is used to collect a liquid slurry upstream of an internal collection tank. The scoop is in fluid communication with a downcomer, which receives at least part of the collected slurry, thereby maintaining a continuous flow of liquid slurry through the scoop to prevent plugging. Collected slurry can be removed for treatment from the scoop or the downcomer. In an application to a wet flue gas desulfurization (FGD) scrubber, the scoop collects an effluent slurry of partially reacted liquid scrubbing reagent and scrubbing byproducts before they drain into an internal reaction tank. Partially reacted liquid scrubbing reagent and scrubbing byproducts can therefore be withdrawn for treatment before the addition of fresh reagent alters the pH of the treatment stream.

Abstract: The present invention relates to the improvement of a replenishment method of a magnesium-based compound and to the improvement of a double decomposition method, which can be used in a magnesium hydroxide desulfurization method. In the improved replenishment method, the magnesium-based compound is supplemented with water and the ratio of Mg/H2O is adjusted to the total Mg/H2O in the desulfurization system. In the improved double decomposition method, a tank for use is provided with an inner cylinder which partitions the tank into an inner part and an outer part, but does not reach the bottom of the tank, and a part of the slurry drawn through the bottom of the tank is fed to the outer upper position in the tank.

Abstract: Sulfurous gas streams comprising hydrogen sulfide and carbon disulfide, such as produced as a by-product of the rayon-forming process, are processed to recover the components in a useable form. The gas stream first is contacted with an aqueous sodium hydroxide to dissolve out hydrogen sulfide and some of the carbon disulfide. The dissolved carbon disulfide is driven off from the solution and condensed as a liquid concentrate. Carbon disulfide remaining the gas stream is recovered, such as by condensation. The aqueous sodium sulfide solution which remains from removal of carbon disulfide is concentrated and the pH is adjusted, as necessary, to a value at which the sodium sulfide is predominantly in the form of sodium bisulfide. The concentrated sodium bisulfide solution is capable of reuse in the rayon-forming process along with the liquid concentrate of carbon disulfide.

Abstract: A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Abstract: A process is provided for the removal of mercury and sulfur dioxide out a flue gas from, for example, power stations, smelters, waste incineration plants and crematories, by washing the flue gas with an oxidized, chloride-containing washing water, which may be sea water, which has been oxidized by either adding an oxidizing agent, such as sodium hypochlorite, or by passing an electric current through the washing water (which converts the chloride values into chlorine) so that the gaseous mercury is sorbed into the washing water and is converted into mercury (II) chloride complexes and the gaseous sulfur dioxide is sorbed into the washing water and converted into sulfuric acid, and subsequently passing the resulting mercury (II) chloride and sulfuric acid-containing washing water and the flue gas through a bed of calcium carbonate where the sulfuric acid and the calcium carbonate react to form calcium sulfate which is washed off the bed into the washing water.