Abstract: A method and system for desulfurizing flue gas in which desulfurization is effected by bringing absorbent slurry containing limestone into contact with flue gas. The method classifies absorbent slurry extracted from a desulfurization absorber, returns a fine-side fluid to the desulfurization absorber, and sends a coarse-side fluid to a solid-liquid separator. Supplied limestone powder is mixed to yield limestone slurry by a solid-liquid mixer, and the limestone slurry is classified, sending the small-particle fluid component thereof to the desulfurization absorber, and sending the large-particle fluid component thereof to a limestone fine grinder. And, limestone contained in the large-particle fluid component is finely ground by the limestone fine grinder and the finely ground limestone is sent to the desulfurization absorber.

Abstract: A process for treating an exhaust gas contaminated with dust, Hg, NOx, and SOx is provided by adding a mercury chlorinating agent, such as, for example, HCl, NH4Cl, or Cl2, and ammonia to the exhaust gas so that the mercury in the exhaust gas is converted to HgCl2. The dust, HgCl2, NOx, NH3, and SOx containing the exhaust gas may then be passed through a reactor containing a catalyst such as, for example, V2O5 and/or MoO3 supported on TiO2, which promotes the reaction between the NOx and NH3 to result in the formation of N2 and H2O. The HgCl2 and SOx containing exhaust gas is then passed through a scrubbing tower where the gas is scrubbed with aqueous solutions of absorbents such as CaCO3 and Ca(OH)2, so that HgCl2 and SOx are removed from the exhaust gas. The cleaned exhaust gas is discharged through a stack.

Abstract: A flue gas desulfurization process is disclosed. Specifically the use of carboxylic acids to modify gypsum crystal habit in limestone forced oxidation. The technique is also applicable to other technologies where gypsum is produced as for example in phosphate fertilizer or paper industry.

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: Sulfur dioxide is removed from a gaseous stream using an aqueous scrubbing slurry of magnesium and calcium scrubbing components where the process is carried out where lime and magnesium hydroxide are blended to give a molar ratio of between about 1.0 to 2.0, so as to provide a solids content in the aqueous scrubbing slurry of between about 12 to 20 percent, which includes about 10 to 15 percent suspended solids and 2 to 5 percent dissolved solids, and a dissolved sulfite content of about 13,000 to 20,000 ppm and a pH of between about 5.8-6.0.

Abstract: A method and apparatus for wet flue gas desulfurization in a two-circuit washer having two washers for an absorption agent based on suspensions containing calcium compounds, a sump for supplying the absorption agent to the first washer, and a container for at least partial recovery of the absorption agent from the second washer. The absorption agent, while being returned to the container, is actively brought into contact with oxygen to oxidize calcium sulfite to calcium sulfate. The return line has apparatus for actively blowing in oxygen with only a relatively slight overpressure necessary to blow the air into the absorption agent. The absorption agent to be oxidized is already moving because the difference in elevation along the return line from the recovery apparatus to the container, whereby the absorption agent then arrives more or less completely oxidized.

Abstract: The present invention includes methods and apparatus useful in the removal of air pollutants. More specifically, this invention relates to methods and apparatus useful in mitigating major air pollutants (SOx and NOx) and trace toxins from coal-fired combustors. Using a method or apparatus of the present invention, a coal-fired combustor may be retrofitted to accommodate combined SOx/NOx removal technology for solid waste reduction and environmentally responsible utilization of dry flue gas (FGD) desulfurization product. The combined SOx/NOx control technology may integrate enhanced removal of SO2 at high to medium temperatures using a desulfurization process of the present invention with selective catalytic reduction technology for NOx. The reactivation of spent sorbent and dry FGD product may result in a more complete utilization of the ash and sorbent in the reduction of SO2 emissions, thereby reducing significantly the amount of sorbent used and the volume of by-product generated.

Abstract: Malodorous gases such as amines, organosulfur compounds, hydrogen sulfide, styrene and aldehydes are economically and efficiently treated at ambient temperature and pressure by a catalytic absorption and oxidation process comprising: (a) bringing the malodorous gases into contact with a scrubbing water containing a heterogeneous catalyst to absorb the malodorous components catalytically, and (b) subjecting the resulting solution containing the malodorous components to a catalytic oxidation by contacting it with an oxidizing agent such as hydrogen peroxide, ozone, oxygen, air, nitrogen oxides, and NaOCl in the presence of the catalyst at a temperature ranging from 0 to 100 □ under an ambient pressure, the heterogeneous catalyst comprising an active metal element selected from alkali, alkaline earth and transition metals, and an oxide support material.

Abstract: The present invention provides a method for desulfurizing flue gas in which desulfurization is effected by bringing absorbent slurry containing limestone into contact with flue gas, comprising the steps of classifying absorbent slurry extracted from a desulfurization absorber, returning a fine-side fluid to the desulfurization absorber, and sending a coarse-side fluid to a solid-liquid separator; mixing supplied limestone powder to yield limestone slurry by a solid-liquid mixer; classifying the limestone slurry, sending the small-particle fluid component thereof to the desulfurization absorber, and sending the large-particle fluid component thereof to a limestone fine grinder; and finely grinding limestone contained in the large-particle fluid component by the limestone fine grinder and sending the finely ground limestone to the desulfurization absorber, and a system for carrying out the above-described method.

Abstract: A pollution control apparatus and method to scrub sulfur dioxide uses a lime slurry consisting of small diameter hydrated lime particles injected into the cooling water of a gas cooling tower. The diameter of the lime slurry particles is selected to be less than about 25 microns so that the lime particles substantially dissolve during the evaporative lifetime of the spray droplets. A preferred embodiment of the pollution control apparatus uses an in-line wet grinder and classifier to produce slurry as required.

Abstract: A method for filtering and cleaning high temperature combustible gases, such as synthetic gas produced by a gasifier. The method involves introducing reactive lime to the hot combustible gas that has been previously cooled to less than approximately thirteen hundred (1,300) degrees Fahrenheit, and then filtering the gas through ceramic fiber filters to remove any particulate matter and the calcium salts resulting from the reaction of the lime with the chemical pollutants present within the gas. Optionally, reactive lime may also be introduced into the biomass feed as it travels to the gasifier.

Abstract: Sulfur dioxide is removed from a gaseous stream using an aqueous scrubbing slurry of magnesium and calcium scrubbing components where the process is carried out where lime and magnesium hydroxide are blended to give a molar ratio of between about 1.0 to 2.0, so as to provide a solids content in the aqueous scrubbing slurry of between about 12 to 20 percent, which includes about 10 to 15 percent suspended solids and 2 to 5 percent dissolved solids, and a dissolved sulfite content of about 13,000 to 20,000 ppm and a pH of between about 5.8-6.0.

Abstract: A scrubber system is provided which enables a substantially horizontal flow path for the gas which is being subjected to scrubbing. Among other advantages, this permits operation of the absorber with a differential pressure of zero or less. Scrubber composition spray means are positioned in the horizontal gas flow path for spraying an aqueous scrubber composition in a direction which is generally cocurrent with said gas flow. The system is free of means which spray the scrubber composition in directions countercurrent to said gas flow.

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: A method is provided for cleaning a combustion exhaust gas containing impurities, such as sulfur oxides and hydrochloric acid, with an additive, such as calcium hydroxide, in a reactor. The combustion gas is passed into a wetting zone where water is injected into the gas. The wet combustion gas is then passed through additive injection zone where the additive is co-currently injected into the combustion gas at a location near the bottom of the injection zone. The additive injection zone is connected to the top of the wetting zone and expands conically outward from the gas discharge outlet of the wetting zone so that as the combustion gas (and additive) travel upward through the additive injection zone the velocity of the combustion gas (and additive) is decreased. The combustion gas and additive are then passed through a cylindrical section having a uniform diameter of a given height and connected to the top of the additive injection zone.

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 process for cleaning flue gases containing ash and sulfur dioxide produced by burning sulfur-containing coal in the combustion chamber of a circulating fluidized-bed firing system includes delivering a particulate SO2 sorbent into the combustion chamber. A mixture including portions of the ash, the reaction product produced in the reaction of the SO2 sorbent with the sulfur dioxide, and unreacted SO2 sorbent is fed from the combustion chamber to a mixing unit. In the mixing unit, water or an aqueous sodium-containing solution is mixed with this mixture and the unreacted SO2 sorbent is converted into a hydration product at a reaction temperature of 60° to 100° and at atmospheric pressure. The ash, the reaction product, and the hydration product is returned from the mixing unit into the combustion chamber, and the hydration product is reactivated to an SO2 sorbent at a combustion-chamber temperature of 700° to 950° C.

Abstract: A method for the combined reduction of sulfur dioxide, SO2, and nitrogen oxides, NOx, in the gas stream of a furnace from the combustion of fossil fuels is disclosed. In a narrow gas temperature zone in a furnace, NOx is converted to nitrogen by reaction with a reducing agent such as urea or ammonia with negligible residual ammonia and other reaction pollutants. In about this same temperature zone, SO2 will react with calcium oxide particles, derived from the calcination of lime, Ca(OH)2, or limestone, CaCO3, to form CaSO4 particles. A wide size distribution of aqueous droplets, containing dispersed lime or very fine limestone particles and dissolved urea or ammonia, is injected at the outer edge of the furnace gas zone at which the SO2 and NOx reduction reaction are effective.

Abstract: A method for purifyiing flue gas derived form incinerators burning refuse, wood, or sludge, in which the flue gas is cooled in a spray drier. A dust remover removes the dust from the flue gas. The flue gas is filtered through a filter-bed adsorber having filtering surfaces and packed with an adsorbent containing calcium hydroxide. The filter-bed adsorber is cleaned at intervals for removing adsorbate from the filtering surfaces. An aqueous suspension is prepared from at least some of the adsorbate that is removed from the filtering surfaces, and the flue gas is brought into contact with the suspension in at least one location upstream of the filter-bed adsorber for further separation of contaminates. The aqueous suspension is supplied to the spray drier for improving the purification of the flue gas.

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 and system for reducing the concentration of odorous contaminants, primarily hydrogen sulfide, in the vapor spaces of sewage handling and treatment systems, primarily the vapor spaces of sewage trunk lines, by injecting a fine spray, mist or fog of a dilute solution of hydrogen peroxide and a base selected from a group consisting of sodium hydroxide, potassium hydroxide, ammonium hydroxide and sodium carbonate to mix intimately with the vapor flow. The peroxide and base solutions may be pre-mixed and diluted with water and injected through atomizing nozzles utilizing compressed air as an atomizing fluid. The system may also provide for separate storage of the peroxide and base solutions, mixing of the peroxide and base solutions with dilution water with in-line mixing devices and direct injection with or without compressed air atomization into the vapor space.

Abstract: A method for removing sulfur dioxide out of a gas is provided. The sulfur dioxide contaminated gas is contacted with an aqueous solution or slurry that contains a reagent, such as sodium carbonate or sodium bicarbonate, in a reactor that may be a spray drier or a quench reactor and a gas having a diminished quantity of sulfur dioxide; unreacted reagent; sulfate reaction product, and which is at a temperature in the range of about 130 to 200 ° F. and a humidity in the range of 10 to 70 percent is produced. Particulate calcium hydroxide is blown into this gas through a device, such as dry venturi. The dry venturi removes aerosols out of the gas and helps ensure that the downstream filter cake is porous and non-tacky. The gas is then passed through a filtering device so that solids in the gas accumulate on the filter device, thus forming a filter cake. At least a portion of the sulfur dioxide in the gas is removed via passage of the gas through this filter cake.

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.

Abstract: The method and apparatus of the present invention are directed to conditioning particulate-containing gas streams using novel additives. The additive is an organometallic salt, preferably of a carboxylic acid, that decomposes in the gas stream to produce mobile metal compounds that significantly reduce the resistivity of the particles. The additive is particularly effective under hot-side conditions when used to condition particles to be collected by an electrostatic precipitator.

Abstract: A method of producing calcium sulfate with a flue gas scrubbing facility having a gas-liquid contactor that uses a calcium-based slurry to absorb sulfur dioxide from a flue gas containing acidic gases, wherein a byproduct containing calcium sulfite precipitate is produced that is accumulated in a reservoir, such as a pond, apart from the gas-liquid contactor. Such a facility is modified to produce calcium sulfate by installing an acidifier vessel and an oxidation receptacle in series between a source of the flue gas and the gas-liquid contactor. The flue gas containing the acidic gases is caused to flow through the acidifier vessel, into which the byproduct is delivered from the reservoir so that some of the acidic gases of the flue gas are absorbed by the byproduct and the pH of the byproduct is sufficiently lowered to allow the calcium sulfite precipitate to dissolve in the byproduct.

Abstract: An inline, high-shear mixer is provided in a cracked gas stream upstream of a caustic tower in an ethylene production unit. Spent caustic is withdrawn from the bottom of the caustic tower and pumped to the mixer, where the spent caustic mixes with and absorbs acid gas components from the cracked gas stream. The spent caustic is separated from the cracked gas, forming a partially treated cracked gas stream. The partially treated cracked gas stream is then fed to the caustic tower. Polymer deposition in the caustic tower is reduced because polymeric material is formed when the cracked gas stream is mixed with the spent caustic and is removed before the cracked gas stream is fed to the caustic tower.

Abstract: Sulfur dioxide and other sulfur compounds are removed from various waste gas streams including those from incineration, refinery sulfur processing, coal burning, or metal smelting operations. The process for sulfur compound removal comprises, in an adsorption vessel, the quenching and subsequent adsorption of the gas with a suitable adsorbent such as an aqueous basic solution (e.g. sodium hydroxide). Sulfur compounds are thus adsorbed into a liquid scrubbing solution predominantly in the form of partially oxidized species (i.e. sulfites, bisulfites, thiosulfites, sulfides, and bisulfides). In a separate heterogeneous catalytic oxidation step, these partially oxidized sulfur compounds are more completely oxidized so that the chemical oxygen demand of the effluent from the oxidation reactor is substantially reduced.

Abstract: Magnesium hydroxide of high purity, having a fine particle size suitable for use in flame retardants and other high-end uses, is produced by utilizing flue gas desulfurization system process slurry as feedstock; the production process is absent energy-intensive steps as well as high-cost chemical usage.

Abstract: A method is provided for removing sulfur dioxide and carbon dioxide out of gases from, for example, the combustion of sulfur containing fossil fuels. The sulfur dioxide and carbon dioxide contaminated gas is first contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein the aqueous solution is at an acidic pH, for example, at a pH of from about 2 to about less than 7, so that the sulfur dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal sulfates and alkaline earth metal sulfites. The gas is then contacted with an aqueous solution containing dimethyl sulfoxide and alkaline earth metal ions, wherein this aqueous solution is at a pH that is greater than 7 so that the carbon dioxide in the gas is dissolved in the aqueous solution and, subsequently, reacts with the alkaline earth metal ions to form alkaline earth metal carbonates.

Abstract: A method for removing contaminants, such as sulfur dioxide, mercury and hydrochloric acid, out of flue gases is provided, said method including the steps of: treating the flue gases with a reagent, such as sodium carbonate, sodium bicarbonate and ammonium salts or mixtures thereof; selectively dissolving the sodium phosphates produced thereby in water; separating out the solids remaining in suspension in the solution; and crystallizing the purified sodium sulphate present in the above-mentioned solution. The sodium sulfate can be upgraded in glass working furnaces. The reagent can be obtained by heating an intermediate solution containing sodium bicarbonate; sodium carbonate; ammonium bicarbonate and ammonium carbonate, which was obtained from the Solvay process for manufacturing sodium carbonate.

Abstract: A process for recovery of substantially all the sulfur in a spent lead-acid battery as Na2SO4 is disclosed. The process comprises (a) breaking the batteries to remove the acid, (b) separating the plastic from the lead bearing materials, (c) smelting the lead bearing materials in a reverberatory furnace in an oxidizing atmosphere to volatilize most of the sulfur in the feed as SO2, (d) scrubbing the SO2 from the off gas stream using a soluble alkaline material such as NaOH, Na2CO3, or KOH to produce a soluble sulfite solution, (e) oxidizing the sulfite solution to sulfate, preferably by turbulent mixing of the solution with air, (f) adjusting the pH by adding the sulfuric acid separated from the batteries, (g) removing the contained heavy metals, (h) crystallizing the sulfate as Na2SO4 or K2SO4, (i) separating a bleed stream from the crystallizer and removing the contained chlorides as a mixed sulfate-chloride product by evaporation of the bleed stream in another crystallizer.