Abstract: Gas streams containing non-condensible gases (NCG's) including reduced sulfur compounds, such as hydrogen sulfide, dimethyl sulfide, dimethyl disulfide and mercaptans, are treated to remove the NCG's from the gas stream. Following an optional initial gas-liquid contact to cool the gas stream to its adiabatic dewpoint and to remove particulates, the gas stream is subjected to an intimate gas-liquid contact with aqueous chlorine dioxide, in one or more contact stages, to oxidize the reduced sulfur compounds and other oxidizable compounds present in the gas stream, and then the gas stream is passed through an entrainment separator to remove entrained liquid droplets.

Abstract: A process for producing ammonium thiosulfate by contacting a feed gas containing hydrogen sulfide and ammonia with an aqueous absorbing stream containing ammonium sulfite and ammonium bisulfite to form an ammonium thiosulfate-containing solution; the absorption being controlled by monitoring the oxidation reduction potential of the absorbing stream and varying the feed rates in response to the oxidation reduction potential measurements. An ammonium bisulfide-containing aqueous stream is contacted with and absorbs sulfur dioxide to form an aqueous stream containing the ammonium sulfite and ammonium bisulfite reagents. This sulfite/bisulfite-containing stream is combined with the ammonium thiosulfate-containing solution in a vessel to produce a combined solution. A portion of the combined solution is recycled back to contact the feed gas and ammonium thiosulfate is recovered from the remaining portion of the combined solution.

Abstract: A flue gas mixture containing sulfur oxides is scrubbed in a countercurrent spray tower absorber with a spray of ammonium sulfate liquor and the scrubbed gas stream containing ammonia aerosols, sulfur trioxide aerosols and ammonia slip is passed to a wet electrostatic precipitator for the removal of the aerosols and slip. The ammonium sulfate liquor in the absorber system is passed into a separate reaction tank where ammonia and air are injected. The ammonia and sulfur oxides react in the separate reaction tank to form ammonium sulfite which is oxidized to the sulfate by the air. The gases and vapors from the separate reaction tank are separately scrubbed and the gases then returned to the absorber.

Abstract: A nozzle 11 is provided whose discharge port 12 is in absorption liquid b of a liquid reservoir 2 which reserves the absorption liquid b containing the absorbent a and which is arranged below of an absorption tower 1 into which combustion exhaust gas d containing sulphur dioxide is introduced. A reduction section 14 is provided on the downstream side from a pipe 15 which is connected to the discharging side of the pump 13 which circulatively supplies the absorption liquid b to the nozzle 11, and an air suction pipe 17 is provided to have an opening 18 on the downstream side from the reduction section 14. The effective cross section of the reduction section 14 is narrower than the effective cross section of the nozzle 11 on the downstream side from the opening 18. The wide and narrow relation of such an effective cross section forms a negative pressure region on the downstream side from the reduction section 14.

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: 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: Nitrate-containing (contaminated) solutions are reduced with SO2 gas in the presence of an at least equimolar amount of NH4+ or ammonium salt.

Abstract: The invention is directed to a process for oxidizing gaseous pollutants in a flue gas stream composed of flue gases, water vapour and one or more gaseous pollutants selected from the group consisting of SO2, NO, NO2, H2S, and mercury vapour, the oxidized form of the pollutants being more readily removable from the flue gas stream by water absorption than the non-oxidized form thereof, comprising: (a) injecting sufficient chlorine in a gaseous form, a liquid form, or as a chlorine water solution, into the flue gas stream while the flue gas stream is at a temperature greater than 100° C.

Abstract: An apparatus and method for sulfur recovery uses a scrubber tower with a plurality of vertically spaced scrubber trays in the tower. Sulfide-lean liquor is supplied to each of the trays and an acid gas is supplied to the tower below the trays. A downcomer extends in the tower and through the trays for accumulating liquid from the trays and moving the liquid to the bottom of the tower. The sulfide-lean liquor and acid gas are selected to form a sulfite-rich or sulfide-rich liquor in each of the trays which are brought to the bottom of the tower through the downcomer for removal from the tower.

Abstract: The invention disclosed relates to a process for removing hydrogen sulfide from a gas stream, such as sour natural gas, with the formation of elemental sulfur as a by-product. By controlling the reaction conditions, the conversion of hydrogen sulfide is maximized, and the sulfur dioxide selectivity is controlled. Specifically, the sulfuric acid concentration and the reaction temperature may be balanced, depending on the desired product mix.

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 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: Gas streams containing non-condensible gases (NCG's) including reduced sulfur compounds, such as hydrogen sulfide, dimethyl sulfide, dimethyl disulfide and mercaptans, are treated to remove the NCG's from the gas stream. Following an optional initial gas-liquid contact to cool the gas stream to its adiabatic dewpoint and to remove particulates, the gas stream is subjected to an intimate gas-liquid contact with aqueous chlorine dioxide, in one or more contact stages, to oxidize the reduced sulfur compounds and other oxidizable compounds present in The gas stream and then the gas stream is passed through an entrainment separator to remove entrained liquid droplets. Acidic gases produced in the oxidization stage and residual chlorine dioxide generally are removed from the gas steam by intimate gas-liquid contact of the gas stream with an aqueous neutralizing and reducing solution, in one or more contact stages, and ten the gas stream is passed through an entrainment separator to remove entrained liquid droplets.

Abstract: A heat recovery and pollution abatement process with stackless operation for removing the products of combustion from hot boiler flue gas (45) comprising the steps of passing said hot boiler flue gas through a cloud of steam or mist (46), cooling the hot moist flue gas and recovering the heat therefrom (47), passing the partly cooled hot moist flue gas through a second cloud of mist comprised of cold water to total saturation (48), collecting the resulting stream of acid water, forcing the treated flue gas, mixing the treated flue gas with outside air, directing the forced treated air to atmosphere, shutting off the process in the absence of boiler flue gas.

Abstract: Methods for removing carbonyl sulfide (COS) from a synthesis gas stream are disclosed. The method entails raising the water level of a wet scrubber so that hydrolysis of the COS may occur in the scrubber itself instead of a COS reduction chamber and no additional catalysts other than those naturally occurring in the production of the synthesis gas need be introduced into the scrubber. The water is raised, in one example, to a level such that water within an inner tube of the wet scrubber flows over an upper end of the inner tube. Raising the water level in the scrubber ensures intimate and vigorous interaction between the water, the COS, and the naturally occurring catalyst, and promotes the hydrolysis of the COS. In one example, the naturally occurring catalyst (e.g., alumina oxide) is present in the coal ash produced when coal is the fuel gasified that creates the synthesis gas stream.

Abstract: A method for removing high boiling point volatile organic compounds from an exhaust gas and an apparatus for performing such operation are described. In the method, a wet scrubber is provided which is equipped with a spent water reservoir at the bottom of the scrubber for collecting spent water that contains the volatile organic compounds dissolved in water used to wash the exhaust gas. An ozone gas at a preset concentration is then flown into the spent water to oxidize the dissolved volatile organic compounds contained in the water. The exhaust gas after being washed in the wet scrubber can be released to the atmosphere together with carbon dioxide generated in the oxidation reaction. In the apparatus, an ozone detector is further provided on the exhaust gas outlet in the wet scrubber chamber to verify a content of ozone in the released exhaust gas which is an indication that all the volatile organic compounds have been oxidized in the spent water reservoir.

Abstract: An apparatus and process for removing acidic gases, such as sulfur dioxide, hydrogen chloride and hydrogen fluoride, from flue gases produced by processing operations of the type carried out in utility and industrial plants. The apparatus is generally a gas-liquid contactor whose operation uses an ammonium sulfate-containing scrubbing solution to absorb acidic gases from flue gases, and into which oxygen and ammonia are then injected to react with the absorbed sulfur dioxide to produce ammonium sulfate as a valuable byproduct. The oxygen and ammonia are not introduced together into the scrubbing solution, but instead are introduced sequentially and in a manner so that the oxidation first occurs in a relatively low pH solution as a result of the absorbed acidic gases. The ammonia is then added to the solution in a manner that inhibits or prevents intermixing of the ammonia with the majority of the solution, but is present in the solution when recycled for further absorption of acidic gases.

Abstract: Disclosed is a process for the treatment of a plant fluid effluent containing odor compounds including an alkyl mercaptan or an alkyl thiol, an amine compound, ammonia, hydrogen sulfide and mixtures thereof by contacting the plant effluent in either a counterflow or cocurrent flow process. In the process, the effluent is contacted with an aqueous solution comprising a peroxyacid compound and one or more essential oils. When contacted with the peroxyacid, odor compounds in the effluent are oxidized and converted from the gaseous phase into a chemically modified highly aqueous soluble phase in the aqueous treatment. In this way, odor removal from the gas is preferred and odor compounds are efficiently transferred into the aqueous treatment solution. The use of such a process produces a significant improvement in odor quality index as measured by a conventional process using an expert panel when compared to conventional treatment methods.

Abstract: A waste gas treatment system treats waste gases of the type produced during the manufacture of semiconductor devices and therefore having different chemical characteristics. Based on the size of the particles of the waste gases, a gas separation unit discriminates waste gas that is best-suited for wet treatment from waste gas best-suited for dry treatment. A wet treatment unit is connected to one outlet of the gas separation unit, and a dry treatment unit is connected to another outlet of the gas separation unit. On the other hand, both the wet treatment unit and the dry treatment unit are connected to a water spray unit. The water spray unit treats the waste gases, which have passed through either the wet treatment unit or the dry treatment unit, so as to treat the waste gas for untreated water-soluble components.

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: This invention provides a wet flue gas desulfurizer wherein the slurry oxidation tank is equipped with a return pipeline for returning a portion of the slurry to a position at or near the bottom of the slurry oxidation tank, and an oxygen-containing gas is blown in at the discharge end of the return pipeline so as to divide the oxygen-containing gas finely by the action of the slurry returned through the return pipeline, and an oxygen-containing gas blowing device for use in a wet flue gas desulfurizer wherein a fluid reservoir for an absorbing fluid is equipped with a delivery pipe for discharging the absorbing fluid so that its discharge end is open in the fluid reservoir, and an oxygen feed nozzle for injecting an oxygen-containing gas is disposed in the area of the discharged stream in the neighborhood of the discharge end of the delivery pipe.

Abstract: A wet flue gas desulfurization process for removing sulfur dioxide from flue gases. The process utilizes an ammonium sulfate scrubbing solution containing free dissolved ammonia as the reagent for the desulfurization process to produce ammonium sulfate as a valuable byproduct. The scrubbing solution contacts the flue gases and absorbs sulfur dioxide within an absorber of a flue gas scrubbing apparatus, and is then accumulated in a tank where the absorbed sulfur dioxide is reacted with oxygen and ammonia to produce ammonium sulfate. The scrubbing solution has a concentration of greater than 46% ammonium sulfate so as to have suspended solids of ammonium sulfate precipitate, preferably 1% to 20% suspended solids.

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: Membrane gas adsorption is conducted wherein the gas phase contains mercury in the gaseous state and the liquid phase containing at least one oxidizing agent for mercury such that the mercury in the gaseous state is absorbed into the liquid phase, and an oxidation/reduction reaction between the mercury and the oxidizing agent takes place in one step.

Abstract: In order to remove the methanesulphonyl chloride entrained by the gaseous HCl by-product, an amount of water ranging from 0.01 to 20%, relative to the mass of HCl to be treated, is injected into the HCl gas flow and the temperature is lowered to a value below or equal to 15° C.

Abstract: This invention provides a flue gas treating process for removing sulfur oxides and dust from exhaust gas containing sulfur oxides and dust by using an absorption tower into which an absorbing fluid containing an alkaline agent is sprayed, comprising the steps of equipping the absorption tower with integrally formed dust collection means comprising dust collecting plates and discharge electrodes, and with dust separation means for sweeping off the dust collected by the dust collection means; and treating the exhaust gas in the dust collection means and subsequently cleaning the exhaust gas in the absorption tower, whereby desulfurization and dust removal are effected while sweeping off the collected dust by the dust separation means. Thus, desulfurization and dust removal can be effected in a simple manner, and the capacity of an electrostatic precipitator installed on the upstream side can be reduced.

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: Substances to be processed and a hydrogen peroxide aqueous solution are enclosed in a process vessel, and a the process vessel is enclosed in an autoclave together with water. Oxidation processing of the substances is performed by changing the state in the autoclave and the process vessel to a supercritical state which is realized by heating an outer wall of the autoclave with a heater. Further, even if the substances leak from the process vessel, by oxidizing the leaking substances in the autoclave the leaking of the substances to the outside of an oxidation processing apparatus is prevented.