Abstract: Flue gas is treated for the presence of SO.sub.3, without resorting to ammonia injection, by adding a powder into the flue gas and subsequently bringing the flue gas into gas-liquid contact with an absorbing fluid, whereby the SO.sub.2 present in the flue gas is removed by absorption into the absorbing fluid. The treatment process may also include introducing the flue gas into a dust collector, whereby dust, including the powder present in the flue gas, is collected, and/or recovering heat from the flue gas by means of a heat exchanger, whereby the flue gas is cooled. A system for treating flue gas is also provided.

Abstract: An exhaust gas desulfurization system includes a spray pipe which is provided with a plurality of nozzles in the lengthwise direction and whose one end is closed and arranged horizontally in an absorption tower through which the exhaust gas passes vertically. Absorbent slurry is fed from the other end of the spray pipe and is injected upward from the nozzles, by which absorbent slurry is brought into contact with the exhaust gas to perform treatment in the absorption tower. The flow passage on the closed end side of the pipe is present in a shape such that the flow passage cross-sectional area decreases toward the closed end.

Abstract: There is provided a method for flue gas desulfurization which is capable of conducting minute control of oxidation and which is capable of maintaining the concentration of sulfurous acid in an absorbent liquid within a proper range in a highly reliable and efficient manner, even in the case where an abrupt change occurs in the operational conditions of the system. In the method for controlling the oxidation in flue gas desulfurization, the value of proportional sensitivity K in the feed back control process, which is based primarily on the oxidation-reduction potential, is increased depending on the deviation .epsilon. in a region where the detected oxidation reduction potential value PN is below the target oxidation reduction potential value SN in correspondence with the characteristic change of the oxidation-reduction potential against the concentration of sulfurous acid.

Abstract: A process for the treatment of sewage to provide effective removal of selenium (especially the 6-valent selenium) to meet required standards for the dissolved amount of selenium, and the like, at a low cost are developed. The process and apparatus reduces selenium from the 6-valent selenium using microbiological treatment to obtain 4-valent selenium and/or simple selenium, and then provide a solid-liquid separation.

Abstract: A flue gas treatment system is provided for which is capable of easily treating Se contained in flue gas, comprising an extractor 13 for extracting soluble components in the dust removed by a dry-type dust precipitator 5 into water to slurry the dust; insolubilizer supply 16 for supplying an insolubilizer for insolubilizing at least tetravalent Se to the dust slurry which has been slurried from the dust by the extractor 13; adsorbent supply 14 for supplying an adsorbent composed of an organism material for adsorbing at least hexavalent Se in the dust slurry; and separator 15 for solid-liquid separating the dust slurry to which the insolubilizer and the adsorbent have been supplied by said supplies.

Abstract: A solid-liquid separator comprising a first roller disposed on one side of a tank containing a slurry subjected to solid-liquid separation at such a height that the lower part thereof is immersed in the slurry, and driven rotationally in a direction which enables the slurry attached to its surface to be lifted up and discharged to the outside of the tank; and a second roller disposed above the first roller facing the first roller so that the second roller comes into pressure contact with the slurry attached to the first roller and lifted up so as to remove the liquid from the slurry; as well as a wet flue gas desulfurization apparatus using this solid-liquid separator.

Abstract: A gas-liquid contacting apparatus in which spray nozzles for spraying slurry solution upward are arranged in a tower body through which gas passes, wherein a liquid inlet portion of the spray nozzle is of a bell shape having a radius of curvature of 0.

Abstract: A gas-liquid contacting apparatus in which spray nozzles for spraying slurry solution upward are arranged in a tower body through which gas passes, wherein a liquid inlet portion of the spray nozzle is of a bell shape having a radius of curvature of 0.

Abstract: A flue gas desulfurization process which comprises the steps of absorbing and separating sulfur oxides from a combustion waste gas using a Ca compound and, as an absorption auxiliary agent, an organic acid which has carboxyl groups at opposite ends of a straight-chain hydrocarbon containing from 1 to 4 carbon atoms in a flue gas desulfurization apparatus, separating the waste water discharged from the desulfurization apparatus in an electrodialyzer which comprises an alternate array of univalent selective anion-exchange membranes and cation-exchange membranes into two solutions: a concentrated solution in which metallic and chlorine ions are concentrated and a dilute solution in which the metallic and chlorine ions are diluted and the organic acid is left behind, and then recycling the dilute solution as an absorbent to the flue gas desulfurization apparatus.

Abstract: A method of producing solid molding products from a slurry which has undergone absorption in wet-limestone gypsum desulfurization of flue gas includes the steps of concentrating the gypsum-containing absorption slurry, mixing and kneading the solid concentrated slurry with flyash and quicklime or slaked lime, molding the mixture into a given shape using a mold and then curing a resulting molding product in a reaction chamber wherein a part of desulfurized gas is passed. The method also includes solidifying a molded product by drying with water-saturated hot air produced with heat recovered from the flue gas and with water added into a heat recovery process.

Abstract: A slurry sampling device (3) for sampling a slurry in which solid particles are dispersed has upper and lower blocks (105, 109), and a rotator (102) for collection which is rotatably held between the blocks and has a plurality of through holes (111) each having a volume corresponding to the amount of sample to be collected. The upper and lower blocks are provided with slurry conduits (101, 108) and carrier fluid conduits (107, 110) which can be communicated with the through holes so that slurry and carrier fluid can flow therethrough. Arc-shaped long grooves (113, 114) are provided on portions of the upper and lower blocks where ends of the slurry conduits (101, 108) come into contact with, or are adjacent to, the rotator, so that at least one of the through holes is thereby constantly in contact with the long grooves.

Abstract: A method for desulfurizing an exhaust gas containing SO.sub.2 and NO.sub.x in accordance with a wet lime process, the aforesaid desulfurizing method being characterized by comprising the steps of drawing a part of an absorbing slurry, subjecting a filtrate obtained by the solid-liquid separation of the drawn absorbing slurry to an electrolysis treatment in the presence of chlorine ions, or after adjusting the filtrate to pH 3-4, mixing a hydrochlorite with the filtrate, and then refeeding the filtrate as a make-up water to an absorbing tower.

Abstract: A flue gas desulfurization process for treating flue gases containing SO.sub.2, NO.sub.x, and halogen gases by the wet lime method, in which part of the absorbent liquid is extracted, freed from iodine, and recycled as makeup water to the absorption column.

Abstract: A desulfurization process which comprises the steps of bringing a combustion exhaust gas into contact with a gypsum slurry containing 1% or less of calcium carbonate in a first absorption tower, and then bringing the combustion exhaust gas into contact with a gypsum slurry containing 1% or more of calcium carbonate in a second absorption tower. SO.sub.x can be removed from a combustion exhaust gas with a high efficiency in accordance with a wet lime/gypsum method.

Abstract: A wet exhaust gas desulfurization apparatus includes a housing, an absorbing solution (3, B) stored in the lower portion of the housing, a flue (1, 2, 11, 12, 21, 25) above the surface of the absorbing solution, and a partition plate (4, 15, 25) for dividing the flue into gas inlet and outlet portions. Exhaust gas is introduced as an untreated combustion gas from a space above an absorbing solution (3) divided by a partition plate (4) into the wet exhaust gas desulfurization apparatus, the lower edge (5) of the partition plate is immersed in the solution, pressure of the exhaust gas lowers the upper level (6) of the solution on the upper side of the plate to a level (6') through which the gas passes and flows under the partition plate in contact with the solution leaving the solution on the other side of the plate and then discharges through a space above the absorbing solution on the other side of the partition plate.

Abstract: A wet-type exhaust gas desulfurization system comprises a reservoir for trapping an absorbing solution which has absorbed SO.sub.2 from exhaust gas; an absorbing solution circulating tank disposed directly under the reservoir; a plurality of bottom pipes which are installed at the bottom of reservoir and extend downward into the absorbing solution in the circulating tank and whose lower end is open, or drop pipes which depend into the absorbing solution and whose lower ends are open; and air supply pipe at least one end of which is open to the atmosphere; a pipe for discharging the air above the surface of absorbing solution onto the surface of solution in the reservoir; and a pipe for supplying the absorbing solution in the circulating tank to a spray nozzle at the upper part of the absorbing tower.

Abstract: For the purposes of solving a problem due to a fly ash and HF in an exhaust gas, maintaining the activity of calcium carbonate as an absorbent, and recovering a high-purity gypsum, there is here provided a method for desulfurizing an exhaust smoke which comprises the steps of leading the exhaust gas containing the fly ash to a gas absorbing step, removing SO.sub.2 and the fly ash from the exhaust gas by the use of an absorbing solution slurry containing calcium carbonate as an absorbent in the gas absorbing step, and blowing air into the absorbing solution slurry circulating through the gas absorbing step to oxidize it and to thereby produce the gypsum, the aforesaid method being characterized by drawing a portion of the absorbing solution slurry therefrom, leading it to a magnetic field to separate and recover the fly ash from the absorbing solution slurry, and then returning, to the gas absorbing step, a portion or all of the absorbing solution slurry from which the fly ash has been separated.

Abstract: An austenitic stainless steel for use for high temperature concentrated sulfuric acid which comprises, on weight basis, 0.04% or less of C, 5-7% of Si, 2% or less of Mn, 15-25% of Cr, 4-24% of Ni, 0.01-1.07% of Pd and the rest consisting of Fe and unavoidable contaminant materials. By the incorporation of small amount of palladium in a basal austenitic stainless steel containing the essential three elements of Cr, Ni and Si, a superior corrosion resistance against highly concentrated high temperature sulfuric acid is attained.

Abstract: In a wet lime desulfurization of exhaust gases containing SO.sub.2 and fly ash, a method and apparatus for treating absorbent solution slurry-containing fly ash includes diverting at least a part of the absorbent solution slurry containing fly ash particles, separating the diverted absorbent solution slurry by centrifugal separation into the solid gypsum component and a liquid component of a suspension containing fine fly ash particles, adjusting the pH value of the suspension containing fine fly ash particles remaining in a filtrate to 6 to 9 by adding an alkali, supplying the pH adjusted suspension to a thickener, removing concentrated sludge from the thickener, passing overflow H.sub.2 O from the thickener to a limestone slurry tank, and passing slurry from the limestone slurry tank to the absorbent solution slurry as make-up feed. Ill effects caused by fly ash and HF in exhaust gases are avoided, the activity of CaCo.sub.3 in the absorbent slurry is maintained, and highly pure gypsum is recovered.

Abstract: A method of treating an exhaust gas containing SO.sub.2 and HF which is characterized by using an absorbing liquid containing CaCO.sub.3 and Ca(OH).sub.2 as absorbents to be fed to an absorption tower for the exhaust gas, circulating the absorbing liquid from a second slurry tank to the absorption tower, from the absorption tower to a first slurry tank, and from the first flurry tank to the second slurry tank, introducing Ca(OH).sub.2 into the second slurry tank to keep the pH value of the absorbing liquid in the second slurry tank in the range of 5.5-7.0, and blowing air into the absorbing liquid in the first slurry tank.