Methods and systems for inhibiting buildup of crystalline materials in a flue gas desulfurization (FGD) unit. Crystalline materials can accumulate in FGD units as a byproduct of chemical desulfurization processes and can adversely impact FGD unit function. The systems described in the present application include an FGD unit with one or more selected bacterial strains disposed therein. It is believed that the bacteria may form a biofilm on the surfaces in the FGD and/or form a biosurfactant to inhibit or prevent buildup of crystalline materials in the FGD unit. Methods include inoculating an FGD unit with one or more selected bacteria that inhibit or prevent buildup of crystalline materials in the FGD unit. Methods may include periodic reinoculation of the FGD unit.

Processes and systems for producing potassium sulfate as a byproduct of a desulfurization process. Sulfur dioxide is absorbed from a flue gas using an ammonia-containing solution to produce an ammonium sulfate solution that contains dissolved ammonium sulfate. At least a first portion of the ammonium sulfate solution is heated before dissolving potassium chloride therein to form a slurry that contains potassium sulfate crystals and an ammonium chloride solution. The slurry is then cooled to precipitate additional potassium sulfate crystals, after which the potassium sulfate crystals are removed to yield a residual ammonium chloride solution that contains dissolved ammonium chloride and residual dissolved potassium sulfate. Ammonia is then absorbed into the residual ammonium chloride solution to further precipitate potassium sulfate crystals, which are removed to yield a residual ammonium chloride solution that is substantially free of dissolved potassium sulfate.

A method for preparing hydrogen sulfide from sulfur dioxide by electrochemical reduction includes electrochemically reducing sulfur dioxide absorbed in an aqueous solution into gaseous hydrogen sulfide with a membrane electrode, resulting in efficient and selective conversion of the sulfur dioxide absorbed in the aqueous solution into the hydrogen sulfide to avoid a deactivation of a cathode due to colloidal sulfur produced on the cathode and adhesion onto a surface of the cathode, wherein the method is carried out at ambient temperature and normal pressure without addition of a reducing agent, having no waste salts produced, and is simple in operation, and is convenient for large-scale application.

The invention relates to a process for preparing potassium thiosulfate, potassium sulfite or potassium bisulfite comprising the following steps: Step (1a): providing a potassium hydroxide or potassium carbonate solution for neutralizing acid forming components such as dissolving SO.sub.2 or H.sub.2S; Step (1b): providing an SO.sub.2 contacting solution, containing at least some potassium sulfite or potassium bisulfite or potassium thiosulfate; Step (2): providing SO.sub.2 gas; Step (3): reacting these to absorb the SO.sub.2 gas and to form an intermediate reaction mixture comprising potassium sulfite, or potassium bisulfite or a mixture thereof, and optionally recovering the potassium sulfite, or potassium bisulfite or a mixture thereof, and/or optionally using steps 4 and 5; Step (4): adding sulfur or sulfide containing compound containing sulfur having the oxidation state of 0, ?2 or of between 0 and ?2 to the reaction mixture and optionally potassium hydroxide or potassium carbonate, and reacting the mixture under suitable conditions to form potassium thiosulfate; and Step (5): recovering the potassium thiosulfate, and optionally concentrating the potassium thiosulfate.

A fossil fuel fired power plant exhaust gas clean-up and recovery system is provided to remove detrimental compounds/elements from the exhaust gas emitting from the power plant to protect the environment and to recover useful products from the cleaning solution. This is accomplished by directing the exhaust gas from the fossil fuel fired power plant through a single wet scrubber having a cleaning solution of a predetermined pH. The cleaning solution is composed of calcium carbonate and water. A recovery process is attached thereto to reclaim calcium carbonate, calcium sulfate, and carbon dioxide for reuse in the process and/or for commercial use.

A process for cleaning non-condensable pollutant fumes, produced by a combustion; said system comprises: concentrating the non-condensable polluting fumes; mix the contaminating fumes with an alkaline mixture and water vapor; injecting the above mixture into a post-combustion furnace; incinerating said mixture into the oven; conducting the resulting combustion flow by means of a reaction duct without heat, wherein the solid particles will be joined to the solid particles of the alkaline mixture, leaving the air free; separating the formed agglomerates from the gaseous part; and recovering the precipitated agglomerates.

Apparatuses, systems, and methods for removing acid gases from a gas stream are provided. Gas streams include waste gas streams or natural gas streams. The methods include obtaining a hypochlorite and a carbonate or bicarbonate in an aqueous mixture, and mixing the aqueous mixture with the gas stream to produce sulfates or nitrates from sulfur-based and nitrogen-based acidic gases. Some embodiments of the present disclosure are directed to produce the carbonate and/or bicarbonate scrubbing reagent from CO.sub.2 in the gas stream. Still others are disclosed.

A marine exhaust gas scrubbing device including an enclosure having a first end and a second end, an exhaust gas inlet, at least one quencher, at least one pre-treater, at least one venturi component including a venturi inlet and a venturi outlet, an impingement basket, at least one demister, an exhaust gas outlet, and a receiver, and a process for scrubbing a marine exhaust gas including cooling the exhaust gas, pre-treating the exhaust gas, washing the exhaust gas, mixing the exhaust gas and exhausting the scrubbed exhaust gas.

A high-efficiency method for removing sulfur and mercury of coal-fired flue gas, and an apparatus thereof. The method comprises: activating, by using water vapor, lime or Ca(OH).sub.2 used as a sulfur removal and mercury removal absorbent and mixing the lime or Ca(OH).sub.2 with flue gas; conveying, by using water vapor, part of a by-product to a top of a reaction tower and mixing the part of the by-product with the flue gas, so as to strengthen the sulfur removal and mercury removal effect; the flue gas entering a bag type or electric bag compound dust remover after sulfur removal and mercury removal in the reaction tower, and conveying part of the collected by-product to the reaction tower for cycle use.

A high solids magnesium hydroxide slurry may be provided. The slurry may include a magnesium hydroxide compound and a carbohydrate-based viscosity control agent. The slurry may further include sea water as at least a portion of the liquid component. The high solids magnesium hydroxide slurry may be utilized in connection with exhaust scrubber systems for removing SOx and NOx compounds from exhaust gas emissions.