Abstract: A process for the removal of hydrogen sulfide and mercaptans from a gas stream containing a high ratio of mercaptans to hydrogen sulfide, wherein the first step removes hydrogen sulfide by washing the gas stream with an aqueous washing solution comprising water, a physical solvent and a chemical solvent. The first removal step is followed by a second removal step by which mercaptans are removed from the washed gas stream by means of molecular sieves.

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: SO2 and/or NOx are removed from gaseous CO2 at elevated pressure(s) in the presence of molecular oxygen and water and, when SO2 is to be removed, NOx, to convert SO2 to sulfuric acid and/or NOx to nitric acid. The sulfuric acid and/or nitric acid is/are then removed from the gaseous carbon dioxide to produce SO2-free, NOx-lean carbon dioxide gas. The invention has particular application in the removal of SO2 and/or NOx from carbon dioxide flue gas produced in an oxyfuel combustion process, for example, in a pulverized coal fired power station.

Abstract: The invention relates to a method for removing sulfur dioxide from a dry gas stream which comprises following steps: (a) adding a hydrogen-peroxide-comprising liquid to the gas stream, sulfuric acid forming from the hydrogen peroxide and the sulfur dioxide and (b) condensing, absorbing or aerosol precipitation of the sulfuric acid formed. The admixed hydrogen-peroxide-comprising liquid is mixed with the dry gas stream in the course of less than 0.3 s in such a manner that the admixed liquid is essentially homogeneously distributed in the gas stream. Furthermore, the invention relates to an apparatus for removing sulfur dioxide from a dry gas stream which comprises at least one atomizing nozzle for adding the hydrogen-peroxide-comprising liquid and a filter or aerosol separator, arranged downstream, in the direction of flow of the gas stream, of the at least one atomizing nozzle, in each case at least one atomizing nozzle being arranged on a cross sectional area of 300 to 350 cm2.

Abstract: A method for enlarging the particle diameters of sulfuric acid mists in waste gas and collecting the sulfuric acid mists in high efficiency is provided. A process for disposing waste gas containing sulfur oxides that introduces the waste gas in dry type electrostatic precipitator to remove dusts and then introduces the waste gas in a wet desulfurization apparatus to carry out desulfurization, wherein outside air with a flow rate at which the waste gas introduced in the wet desulfurization apparatus is the dew point of acid is taken in from an introducing tube to mix the outside air in the waste gas.

Abstract: Methods and apparatus utilizing hydrogen peroxide are useful to reduce NOx, SOx and mercury (or other heavy metal) emissions from combustion flue gas streams. Continuous concentration of hydrogen peroxide to levels approaching or exceeding propellant-grade hydrogen peroxide facilitates increased system efficiency. In this manner, combustion flue gas streams can be treated for the removal of NOx, SOx and heavy metals, while isolating useful by-products streams of sulfuric acid and nitric acid as well as solids for the recovery of the heavy metals.

Abstract: The invention provides a process for the removal of polysulfanes from gas streams formed during H2S synthesis.

Abstract: The present disclosure sets forth an effluent treatment composition, system, and method for the comprehensive treatment of odiferous or noxious effluent formed as a result of an industrial process. The treatment composition includes an oxidant, a biocide, a scale inhibitor, and an anti-foulant agent. The oxidant may be a permanganate composition. A gas absorption system may be used to apply the treatment composition to an odorous effluent to remove primary and secondary odor components from the industrial process.

Abstract: Provided are methods of producing anhydrous hydrogen fluoride comprising: providing a mixture comprising hydrogen fluoride and at least one halogenated hydrocarbon; and extracting hydrogen fluoride from the mixture by contacting the mixture with a solution of less than about 93 wt. % sulfuric acid solution in water.

Abstract: A method for removing impurities accumulated in a scrubbing fluid in a flue gas scrubber and effluents from the scrubber. The flue gases are scrubbed with a scrubbing fluid that includes a calcium-containing absorbent. The scrubbing fluid containing gypsum and other impurities and produced in the scrubber is discharged from the scrubber. The gypsum is separated from the scrubbing fluid. To the scrubbing fluid is added an auxiliary agent, by the effect of which the impurities accumulated in the scrubbing fluid are removed with the gypsum and the moisture content of the gypsum to be separated from the scrubbing fluid is increased.

Abstract: Selective, irreversible removal of hydrogen sulfide (H2S) and other sulfhydryl compounds from a gas stream, such as sour natural gas and sour hydrocarbon liquids is achieved with a scavenging agent having hydroxyalkyl functionality and alkylamine functionality. This scavenger possesses a higher capacity for H2S removal compared with a scavenger having only hydroxyalkyl functionality. The scavenging agent is made by reacting at least one alkanolamine and at least one alkyl amine with an aldehyde, such as formaldehyde.

Abstract: The removal of particulates and acidic gases from the effluent from a fluid catalytic cracking process regenerator. The effluent is treated in two contacting stages with an effective amount of both a caustic solution as well as ammonia and the composition of the contacting solutions in the two stages is independently controlled.

Abstract: A method and an equipment for reducing sulphur dioxide emissions of a marine engine, wherein flue gases are scrubbed with a scrubbing solution in a scrubber. Fresh water with added sulphur removal reagent is used as the scrubbing solution.

Abstract: NOx and SO3 emissions from combustion of a sulfur containing carbonaceous fuel are reduced simultaneously. The combustion gases comprising NOx and SO2 are mixed with a NOx control agent into the combustion gases at a point upstream of a selective catalytic reduction catalyst for reduction of NOx. Following an SCR catalyst or other equipment that can oxidize SO2 to SO3 and prior to contact with an air heater for heating incoming combustion air, magnesium hydroxide is introduced in amounts and with droplet sizes and concentrations effective to form nano-sized particles in the effluent and reduce SO3 caused by the oxidation of SO2 in the catalyst. Computational fluid dynamics is employed to determine flow rates and select reagent introduction rates, reagent introduction location(s), reagent concentration, reagent droplet size and/or reagent momentum.

Abstract: A method for removing H2S from H2S-containing gaseous streams in which an H2S-containing gaseous stream is introduced into a flow channel and at least one liquid chemical H2S scavenging agent is also introduced into the flow channel. Directly within the flow channel, liquid chemical H2S scavenging agent is transformed into a plurality of H2S scavenging agent droplets, which plurality of H2S scavenging agent droplets are contacted with the H2S-containing gaseous stream, whereby at least a portion of the H2S is absorbed by the plurality of H2S scavenging agent droplets. In accordance with one embodiment, transformation of the liquid chemical H2S scavenging agent is carried out in an inclined flow channel and in accordance with another embodiment, the transformation is carried out using ultrasonic atomization.

Abstract: A process reduces SOx emissions in a flue gas stream by adding a wet collector plate section to an existing electrostatic precipitator (ESP) or by converting the last field of an existing ESP to wet operation. To achieve the conversion, the last field or fields of an existing dry ESP are removed and replaced with components made from materials suitable for operation in a wet environment. After the ESP contains wet operation, ammonia is added to the flue gas stream while it is progressing through the collection plates in the ESP.

Abstract: The present invention provides for a method and apparatus for removing contaminants from a gas stream such as a flue gas stream from an industrial process. The process utilizes a prescrubber to contact the gas stream before the gas stream contacts an oxidizer in an oxidizer zone. The oxidized gas is then treated to either a first and second scrubber operation or just a single scrubber operation.

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 invention relates to a method and an installation for separating sulphur dioxide from exhaust gas, wherein sea water is added to the exhaust gas in an absorption column and the sea water charged with sulphur compounds is extracted from the liquid sump of the absorption column and fresh sea water is added thereto. In order to omit the very expensive and large secondary reaction basis according to the state of the art, it is proposed to extract the liquid, which contains the bisulphates, from the liquid sump of the absorption column and to mix it with fresh sea water in a pipeline for the purpose of sulphate formation and pH adjustment (neutralization). The invention is based upon the finding that the sulphate formation and pH adjustment are completed after a reaction time comprised between 1 and 2 minutes. Thus, the large and expensive secondary reaction basin can be omitted.

Abstract: A new method for the removal of environmental compounds from gaseous streams, in particular, flue gas streams. The new method involves first oxidizing some or all of the acid anhydrides contained in the gas stream such as sulfur dioxide (SO2) and nitric oxide (NO) and nitrous oxide (N2O) to sulfur trioxide (SO3) and nitrogen dioxide (NO2). The gas stream is subsequently treated with aqua ammonia or ammonium hydroxide which captures the compounds via chemical absorption through acid-base or neutralization reactions. The products of the reactions can be collected as slurries, dewatered, and dried for use as fertilizers, or once the slurries have been dewatered, used directly as fertilizers. The ammonium hydroxide can be regenerated and recycled for use via thermal decomposition of ammonium bicarbonate, one of the products formed. There are alternative embodiments which entail stoichiometric scrubbing of nitrogen oxides and sulfur oxides with subsequent separate scrubbing of carbon dioxide.

Abstract: A process to regenerate wet flue gas scrubber purge liquid into NaOH caustic suitable for make-up caustic for the scrubber is disclosed. Further, sulfur is removed from waste effluent in the form of gypsum with the process described herein. Lime is added to the spent, sodium sulfate-containing purge liquid to result in the formation of gypsum and sodium hydroxide.

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: This invention relates to a process for cleaning gas, in particular hydrocarbonaceous gas such as e.g. natural gas, which is contaminated with sulfur in the form of H2S and mercaptans as well as CO2. To remove the undesired sulfur-containing substances in the form of H2S and mercaptan from crude gas, it is proposed in accordance with the invention that the crude gas is introduced into an absorption and regeneration column and washed therein, three gas streams being withdrawn from this absorption and regeneration column, a first exhaust gas stream being introduced into a Claus plant, a second sour gas stream with a low H2S concentration being introduced into another absorption plant, and a third gas stream, the valuable gas with the mercaptans, being cooled and supplied to an adsorption plant, that from this adsorption plant a cleaned valuable gas is withdrawn, and a mercaptan-containing gas stream is subjected to washing, that this concentrated mercaptan-containing gas is supplied to the Claus plant.

Abstract: A device (1) for separating sulphur dioxide from a gas (4) by means of an absorption liquid has an inlet (2) for gas (4) containing sulphur dioxide, an outlet (18) for gas (16), from which sulphur dioxide has been separated, and as essentially horizontal apertured plate (8), which is arranged to allow passage from below of sulphur dioxide containing gas (4) and to carry, on its upper side (12), a flowing layer (14) of the absorption liquid. An outlet box (20) beside the apertured plate (8) is arranged to be passed by liquid, which is distributed in the gas (4) coming from the inlet (2). A first pumping means is arranged to feed a coolant flow to the outlet box (20) and a second pumping means is arranged to feed an absorption liquid flow, which is essentially independent of the coolant flow, to the apertured plate (8) to form the flowing layer (14). In a method of separating sulphur dioxide, the above-described device (1) can be used.

Abstract: A hydrogen generator including a raw material supplying unit supplying a raw material containing a sulfur component and composed of an organic compound, a water supplying unit supplying water, a reformer producing hydrogen gas, the reformer provided with a reforming catalyst to make the raw material and water undergo a reaction, and a carbon monoxide removing unit reducing the content of carbon monoxide in hydrogen gas produced in the reformer, wherein the reforming catalyst is constituted by a carrier composed of platinum and a metal oxide is provided.

Abstract: Process for purifying the hydrochloric acid obtained as by-product in the synthesis of MSA, characterized in that the gaseous flow of hydrogen chloride evacuated from the top of the synthesis reactor is placed in contact in a treatment column, counter-currentwise, with a flow consisting of an aqueous solution of an acid chosen from methanesulfonic acid, hydrochloric acid or a mixture of these two acids, at a temperature of between 80 and 130° C.

Abstract: A device (1) for separating sulphur dioxide from a gas has an inlet (2) for the gas (4) and an outlet (42) for gas (40), from which sulphur dioxide has been separated. An apertured plate (20) is arranged between the inlet (2) and the outlet (42) and allows the gas (4) to pass from below. On its upper side (22), the apertured plate supports a flowing layer (24) of absorption liquid. An inlet duct (12) connects a container (6) for absorption liquid to the upper side (22) of the apertured plate (20). A means (10) conveys the absorption liquid (8) from the container (6), through the inlet duct (12), to the upper side (22) of the apertured plate (20) and along the apertured plate (20).

Abstract: A water stream containing hardness minerals is subjected to a water treatment process using an alkali agent to precipitate the hardness minerals and to produce a softened water stream is used to create an integrated water treatment and flue gas desulfurization process. Thereafter, the softened, alkaline water stream is utilized in a scrubber to scrub a flue gas containing sulfur dioxide to produce a sulfur-lean flue gas. The invention may be applied to a steam-based bitumen recovery operation where bitumen, sour produced gas or other sulfur containing fuels are burned for producing steam for bitumen recovery. More specifically, the associated produced water from the bitumen recovery process may be softened for re-use and for utilization as a scrubbing agent for high-sulfur containing flue gas arising from the steam generators. The process provides an economically favorable process while minimizing waste disposal requirements.

Abstract: Method and apparatus are provided for removing contaminants from a hydrogen processor feed stream, as in a fuel cell power plant (110). Inlet oxidant (38), typically air, required by a catalytic hydrogen processor (34) in a fuel processor (14) for a fuel cell stack assembly (12) in the power plant (110), may contain contaminants such as SO2 and the like. A cleansing arrangement, which includes an accumulator/degasifier (142, 46) acting as a scrubber, and possibly also a water transfer device (118), receives the inlet oxidant and provides the desired cleansing of contaminants. Water in the water transfer device and in the accumulator/degasifier serves to dissolve the water-soluble contaminants and cleanse them from the oxidant stream. The cleansed oxidant stream (138?) is then delivered to the hydrogen processor and to the fuel cell assembly, with minimal inclusion of detrimental contaminants such as sulfur.

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 multiple-field precipitator, flue-gas treating device, in accordance with the principles of the invention, includes a first section having a dual-function, sensible-cooling heat exchanger/electrostatic precipitator, a second section having a wet electrostatic precipitator, and a middle section fluidly connecting the first and second sections. In the first section, the exchanger/precipitator sensibly cools the flue gas and collects most of the dust from the flue gas. In the middle section, the dust-reduced flue gas is combined with an alkaline material, thereby forming reaction products. These reaction products and several other pollutants are captured by the wet electrostatic precipitator, in the form of a pollutant-laden liquid. The pollutant-laden liquid is directed to a series of heat exchangers and settling tanks, where various pollutants such as SOx, metals, NOx, and chlorides are removed in different stages.

Abstract: Method and apparatus are provided for removing contaminants from a hydrogen processor feed stream, as in a fuel cell power plant (110). Inlet oxidant (38), typically air, required by a catalytic hydrogen processor (34) in a fuel processor (14) for a fuel cell stack assembly (12) in the power plant (110), may contain contaminants such as SO2 and the like. A cleansing arrangement, which includes an accumulator/degasifier (142, 46) acting as a scrubber, and possibly also a water transfer device (118), receives the inlet oxidant and provides the desired cleansing of contaminants. Water in the water transfer device and in the accumulator/degasifier serves to dissolve the water-soluble contaminants and cleanse them from the oxidant stream. The cleansed oxidant stream (138?) is then delivered to the hydrogen processor and to the fuel cell assembly, with minimal inclusion of detrimental contaminants such as sulfur.

Abstract: A wet type exhaust gas desulfurization method includes sucking liquid in a liquid reservoir containing a sulphur compound formed from sulphur dioxide contained in exhaust gas so as to form a flow of the liquid, reducing the flow of the liquid in diameter to form a depressurized region in the flow, the reducing including passing the liquid through a reduction section which includes a reduction section plate having a reduction section hole and a peripheral portion surrounding the reduction section hole, the peripheral portion protruding toward the upstream side of the flow, introducing air into the depressurized region so as to generate a mixture stream of the air and the liquid, and spouting the mixture stream into the liquid reservoir. The reducing includes forming cavities in the flow, the forming cavities includes shearing the flow, and the shearing includes bringing the flow into contact with the peripheral portion.

Abstract: A method for removing acidic gases from waste gases is disclosed. The invention relates to a method for removing acid gases, in particular from SO2 and NOx, by contacting the waste gas with an emulsion of water in organic sulfoxides, in particular of water in oil-derived-sulfoxides. The organic sulfoxide phase can be regenerated after the emulsion is loaded with polluants, by letting the emulsion to settle down and separate into two phases. The aqueous phase obtained after the separation contains sulfate and nitrate ions which can be collected and used as valuable chemicals.

Abstract: A system for removal of Hydrogen Sulfide (H2S) and/or Carbon Dioxide (CO2) from natural gas via absorption and disassociation utilizing a sea water contact system. In the preferred embodiment of the present invention, a series of counter current scrubber stages is provided, each configured to remove via absorption/disassociation a portion of the impurities, each stage having less pressure than the predecessor, each stage redirecting the purified gas to the preceding stage, until the contaminant level in the hydrocarbon gas stream has been reduced to an acceptable level. The hydrogen sulfide/carbon dioxide contaminants are thereby sequestered in the sea water utilized in the scrubber, which sea water may be further processed and/or re-introduced into the deep of a body of water, where the contaminants will remain isolated for hundreds of years. The present invention further contemplates and energy recovery system for greatly enhancing the efficiency of the system.

Abstract: In a flue gas treating system, an absorption tower (21), a reheating section (22) and a fan (23) are arranged in line on a vertical axis so as to function as at least a part of a stack for emitting the treated flue gas into the atmosphere. Moreover, in a flue gas treating process, the amount of ammonia injected in the denitration step (a denitrator (2)) and/or the amount of ammonia at a point downstream of the denitration step are determined so as to be on such an excessive level that ammonia or ammonium salt will remain in the flue gas introduced into the desulfurization step (absorption tower (21)). Thus, the size and cost of the equipment can be reduced.

Abstract: Method and apparatus are provided for removing contaminants from a hydrogen processor feed stream, as in a fuel cell power plant (110). Inlet oxidant (38), typically air, required by a catalytic hydrogen processor (34) in a fuel processor (14) for a fuel cell stack assembly (12) in the power plant (110), may contain contaminants such as SO2 and the like. A cleansing arrangement, which includes an accumulator/degasifier (142, 46) acting as a scrubber, and possibly also a water transfer device (118), receives the inlet oxidant and provides the desired cleansing of contaminants. Water in the water transfer device and in the accumulator/degasifier serves to dissolve the water-soluble contaminants and cleanse them from the oxidant stream. The cleansed oxidant stream (138′) is then delivered to the hydrogen processor and to the fuel cell assembly, with minimal inclusion of detrimental contaminants such as sulfur.

Abstract: A wet type exhaust gas desulfurization method including sucking liquid in a liquid reservoir containing chemical substance as an oxidation object so as to form a flow of the liquid, reducing the flow of the liquid in diameter, introducing air into a negative pressure region generated by the reducing so as to generate a mixture stream of air and the liquid, and spouting the mixture stream into the liquid reservoir.

Abstract: A device (1) for separating sulphur dioxide from a gas has an inlet (2) for the gas (4) and an outlet (42) for gas (40), from which sulphur dioxide has been separated. An apertured plate (20) is arranged between the inlet (2) and the outlet (42) and allows the gas (4) to pass from below. On its upper side (22), the apertured plate supports a flowing layer (24) of absorption liquid. An inlet duct (12) connects a container (6) for absorption liquid to the upper side (22) of the apertured plate (20). A means (10) conveys the absorption liquid (8) from the container (6), through the inlet duct (12), to the upper side (22) of the apertured plate (20) and along the apertured plate (20).

Abstract: The present invention relates to a process for removing nitrogen oxides, sulfur oxides, mercury and mercuric oxide from gas streams such as furnace or utility boiler flue gas streams, particularly those derived from coal-fired utility boilers, or from a gas stream from another pollutant abatement process. Ozone will react with the impurities in the gas stream to form mercuric oxide and higher oxides of nitrogen which can be removed by scrubber means. Additionally, and alternatively, the present invention provides for the use of ozone and ultraviolet radiation to remove nitrogen oxides, sulfur oxides and mercury from gas streams.

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: A method for removing an acidic component such as sulfite gas (SO2) contained in an exhaust gas comprising by using a system comprising (a) a gas-liquid contact apparatus composed of an absorption column provided internally with at least one perforated plate at the top, bottom, or both top and bottom of the absorption column packed with at least one type of fillers, (b) an apparatus for introducing raw seawater to the absorption column, (c) an apparatus for oxidizing the seawater after gas-liquid contact, and (d) an apparatus for mixing raw seawater with the contact seawater after oxidation, whereby the exhaust gas containing an acidic component is brought into gas-liquid contact with the seawater.

Abstract: The liquid cooling spray in a gas conditioning chamber is modified by the addition of an alkali to scrub sulfuir dioxide and other acid forming gases and a separation unit to remove particles that may contain either unreacted alkali or salts of the acid forming gases. A slurry of fine particles of hydrated lime is injected into the liquid coolant under conditions that result in kernels of controllable size that contain the alkali or salts from reactions with the acid forming gases. The modified cooling liquid provides for a high sulfur dioxide collection efficiency at a low molar ratio of alkali to sulfur, while the specified kernel size range allows fbr efficient removal of the kernels from the gas.

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: The invention relates to a process for removal of sulfur compounds from wastewater, which process provides recovery of elemental sulfur. The process is carried out in two separate anaerobic reactors. In the first reactor organic compounds are converted to acid compounds and sulfur compounds are converted to sulfide compounds. The sulfide compounds are stripped from said first reactor with a stripping gas. Subsequently, the effluent of the first reactor is fed to a second anaerobic reactor, in which organic compounds, such as the acid compounds, are converted to produce biogas, while any unconverted sulfur compounds from the previous step are converted to sulfide compounds as well. Finally, the sulfide compounds are removed from the second reactor in a stripping system, and converted to elemental sulfur in an adsorber.

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 invention provides an exhaust gas treatment agent characterized in that it comprises calcium silicate hydrate particles having a mean particle diameter of 0.2 to 4 &mgr;m and a specific surface area of not less than 60 m2/g and calcium hydroxide particles having a mean particle diameter of not more than 4 &mgr;m and the content of calcium hydroxide particles in both particle components is within the range of 20 to 60% by weight; a method of producing the exhaust gas treatment agent; and a process for the treatment of exhaust gases and soot and dust which uses the exhaust gas treatment agent.

Abstract: A process for reducing NOx concentrations in waste gas streams. More particularly, the present invention relates to contacting a NOx-containing waste gas stream with an effective amount of sodium chlorite under conditions such that at least a fraction of the oxidizable NOx species present in the waste gas stream is oxidized to higher nitrogen oxides.

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: 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.