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 L.sub.13 which returns, to a main flue L.sub.11, 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 L.sub.21, 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 L.sub.21, 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.

A method for the reduction and prevention of mercury emissions into the environment from combusted fossil fuels or off-gases having mercury with the use of hypoiodite is disclosed. The hypoiodite is used for the capture of mercury from the resulting flue gases using a flue gas desulfurization system or scrubber. The method uses hypoiodite in conjunction with a scrubber to capture mercury and lower its emission and/or re-emission with stack gases. The method allows the use of coal as a cleaner and environmentally friendlier fuel source as well as capturing mercury from other processing systems.

Provided are an absorbing column in which flue gas containing sulfur oxides is desulfurized by seawater and a reactor vessel in which alkali earth metal or alkali metal is added to the seawater having absorbed the sulfur oxides from the flue gas in the absorbing column to produce a compound which is stable like minerals.

A hydrated lime product exhibiting superior reactivity towards HCl and SO.sub.2 in air pollution control applications. Also disclosed is a method of providing highly reactive hydrated lime and the resultant lime hydrate where an initial lime feed comprising calcium and impurities is first ground to a particle-size distribution with relatively course particles. Smaller particles are then removed from this ground lime and the smaller particles are hydrated and flash dried to form a hydrated lime, which is then milled to a significantly smaller particle size than that of the relatively course particles. The resultant lime hydrate product has available CaOH of greater than 92%, a citric acid reactivity of less than 20 seconds, a BET surface area greater than 18, a D90 less than 10 m, a D50 less than 4 m, a D90/D50 less than 3, and a large pore volume of greater than 0.2 BJH.

The invention is a device and method for purifying sulfur dioxide and nitrogen oxide in flue gas with an electrolysis-chemical advanced oxidation enhanced ammonia method. The device includes a thermal activation reactor, ammonium hydroxide storage tank, absorption tower, electrolytic bath and crystallization separator. The method takes raw material part of an ammonium sulfate solution that is a reaction product of ammonia and sulfur oxide in flue gas, and an ammonium persulfate solution prepared by electrolysis of an electrolytic bath as an oxidant to enhance the efficiency of purifying sulfur dioxide and nitrogen oxide in the flue gas with an ammonia method. A thermal activation reactor activates an ammonium persulfate containing solution to generate a strong oxidizing SO4.sup., so that NO.sub.x and SO.sub.2 in the flue gas may be more efficiently converted into a product having higher solubleness for enhanced removal of sulfur dioxide and nitrogen oxide in the flue gas.

The invention is directed to a process and a system for removing sulfur dioxide from a feed gas stream. In the process the feed gas pre-scrubbed. Then SO2 is absorbed from the gas with an absorbing medium. The spent absorbing medium is regenerated. These process steps are interchanged with a caustic treatment in the pre-scrubbing zone in case of a very high SO2 content in the feed gas stream. The system comprises a pre-scrubbing unit, an absorption unit, and a regeneration unit. The system is characterized in that the pre-scrubber unit comprises an inlet for an aqueous solution comprising a strong base. These are a simple, cost-efficient and reliable process and facility for processing gas with a varying SO2 content.

A processing unit for a liquid washing medium contaminated with sulphur oxides and/or nitrogen oxides, has an evaporation stage for concentrating the active components of the washing medium by an evaporator and/or by a heat exchanger, and has a collecting tank connected to the evaporator and/or to the heat exchanger. The collecting tank is configured as a crystallizer for removing sulfur oxides from the washing medium by crystallization of a sulphate, in particular of potassium sulphate. A separating device for carbon dioxide has a corresponding processing unit, and a method for processing a washing medium contaminated with sulphur oxides and/or nitrogen oxides uses a corresponding processing unit.

The removal of acid gases (e.g., non-carbon dioxide acid gases) using sorbents that include salts in molten form, and related systems and methods, are generally described.

Methods and systems for control and adjustment of the feed rate of mercury reemission control additives (MECA) to a wet flue gas desulfurization system. Predetermined sulfite concentration values are compared to actual sulfite concentrations measured in the scrubber liquid. The MECA feed to the recirculating scrubber liquor is then adjusted and regulated as a result of such comparisons.

The present invention discloses a resource recovery method and a resource recovery system of desulfurized ash. The resource recovery method comprises: washing desulfurized ash with water, and performing solid-liquid separation to obtain solid residues rich in calcium sulfite and calcium sulfate and a solution rich in calcium hydroxide; preparing the solution into desulfurized slurry; and roasting the solid residues under the action of a reducing agent to obtain flue gas rich in sulfur dioxide and residues rich in calcium oxide. Therefore, the recovery of sulfur and calcium in the desulfurized ash is realized, and no solid waste, liquid waste, gas waste, etc. are produced in the process.