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: 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 gas-liquid contacting method which using a gas-liquid contacting facility comprised with a tower having a reservoir for a gas absorbing liquid at the bottom part and a space for the flow of a gas to be treated in the upper part, a header pipe installed in the tower, a pump for feeding the gas absorbing liquid to the header pipe from the reservoir of the gas absorbing liquid, a throat pipe attached to the header pipe, a discharge pipe with cross-sectional area greater than the cross-sectional area of the throat pipe, and a diffuser pipe that connects the throat pipe and the discharge pipe, whereby the gas absorbing liquid boils under low pressure, by making the cross-sectional area of the throat pipe to be sufficiently smaller than the cross-sectional area of the discharge pipe, then squirting the gas absorbing liquid into the gas to be treated from the discharge pipe.

Abstract: An apparatus for treating a slurry by gas-liquid contact, said apparatus comprising a hollow rotary shaft, stirring rods fixed to the lower end of said shaft, and gas supply pipes to supply a gas to the negative-pressure region which is formed behind the stirring rods as they rotate, said gas supply pipes having their openings fixed to the back of said stirring rods, and said stirring rod being provided on the top thereof with a plate to stabilize the negative-pressure region, said plate extending in the direction opposite to the rotating direction of the stirring rod.

Abstract: The present invention relates to an apparatus for treating a solution or a slurry solution and its improved types. The apparatus of the present invention comprises a hollow rotating shaft having a sealing mechanism and a rotating mechanism at upper portions thereof, the apparatus being characterized by comprising a plurality of stirring branch pipes attached to the lower end of the hollow rotating shaft vertically downward extending into the solution in a storage tank, and a plurality of gas jet pipes disposed under the respective branch pipes, the gas jet pipes extending vertically downward and being opened at the lower ends thereof, whereby the shaft and the stirring branch pipes are rotated, while a gas is jetted from openings of the gas jet pipes through the sealing mechanism, the hollow rotating shaft and the branch pipes.

Abstract: The present invention is concerned with a method for desulfurizing smoke which includes an absorbing procedure of cleaning a combustion exhaust gas with a limestone slurry; an oxidizing procedure of blowing air into the slurry coming from the absorbing process to oxidize calcium sulfite in the slurry to gypsum; a circulating process of circulating, through the absorbing procedure, the slurry coming from the oxidizing procedure; and a separating procedure of drawing a part of the slurry from the circulating procedure, separating and recovering gypsum therefrom, and returning the remaining slurry to the circulating system. The method is characterized in that a separator for separating the fed slurry into an over flow and an under flow is used, and the fed slurry is irradiated with ultrasonic waves to accelerate the separation of gypsum particles from limestone particles, whereby the limestone particles and the gypsum particles are transferred to the over flow and the under flow, respectively.

Abstract: Here is disclosed a method for treating SO.sub.2, SO.sub.3 and a dust simultaneously which comprises causing an exhaust gas containing at least SO.sub.2, SO.sub.3 and the dust to pass through a dry dust collector in order to remove most of the dust therefrom, delivering the exhaust gas to a gas absorbing device, and using at least one of calcium hydroxide and calcium carbonate as an absorbent in the gas absorbing device to remove SO.sub.

Abstract: Here are disclosed a method for desulfurizing an exhaust gas which is characterized by comprising a gas absorbing section in which an absorbing solution absorbs SO.sub.2 in the exhaust gas in order to become an acid solution containing a sulfite; an oxidizing section in which the sulfite is oxidized; a neutralizing section in which the absorbing solution is neutralized by adding an SO.sub.2 absorbent; and a closed circulating circuit for delivering the solution drawn out from the gas absorbing section to the oxidizing section, delivering the solution drawn out from the oxidizing section to the neutralizing section, and delivering the solution drawn out from the neutralizing section to the gas absorbing section; and a method for simultaneously treating SO.sub.2 and HCl which the abovementioned exhaust gas contains.

Abstract: A method for continuously measuring the concentration of CaCO.sub.3 in slurries comprising CaCO.sub.3 is described. The method comprises continuously sampling a given amount of the slurry, feeding the sampled slurry into an agitated continuous reactor container which is isolated from the outside air, keeping the slurry in the reactor container at a temperature of at least 50.degree. C., adding sulfuric acid or hydrochloric acid to adjust the pH to below 4, blowing a known flow rate of air into the slurry, withdrawing from the reactor container CO.sub.2, produced by the reaction between CaCO.sub.3 and the acid, by entrainment with the air, further mixing the withdrawn gas with air for dilution while controlling a flow rate of the dilution air so that the concentration of CO.sub.2 in the mixed gas is maintained constant, and calculating the concentration of CaCO.sub.3 in the slurry from the concentration of CO.sub.2 in the mixed gas, the flow rate of the mixed gas and the amount of the sampled slurry.

Abstract: A method for continuously measuring the concentration of CaCO.sub.3 and/or CaSO.sub.3 in slurries comprising CaCO.sub.3 and/or CaSO.sub.3 is described. The method comprises continuouly sampling a given amount of the slurry, feeding the slurry into an agitated continuous reactor container which is isolated from the outside air and in which the slurry is kept at a temperature not lower than 70.degree. C., adding sulfuric acid or hydrochloric acid to the slurry to make the pH below 3, blowing air or nitrogen gas into the slurry in the reactor container, withdrawing from the container CO.sub.2 and/or SO.sub.2 produced by reaction of CaCO.sub.3 and/or CaSO.sub.3 with the acid by entrainment with the air or nitrogen gas, and calculating the concentration of CaCO.sub.3 and/or CaSO.sub.3 from the concentration of CO.sub.2 and/or SO.sub.2 in the withdrawn gas, the flow rate of the sampled slurry and the flow rate of the blown air or nitrogen gas.

Abstract: A method for continuously measuring the concentration of CaCO.sub.3 in slurries comprising CaCO.sub.3 is described. The method comprises continuously sampling a given amount of the slurry, feeding the sampled slurry into an agitated continuous reactor container which is isolated from the outside air, keeping the slurry in the reactor container at a temperature of at least 50.degree. C., adding sulfuric acid or hydrochloric acid to adjust the pH to below 4, blowing air into the slurry in the reactor container, withdrawing from the reactor container CO.sub.2, produced by the reaction between CaCO.sub.3 and the acid, by entrainment with the air, and calculating the concentration of CaCO.sub.3 in the slurry from the concentration of CO.sub.2 in the withdrawn gas, the amount of the sampled slurry and the flow rate of the blown air.

Abstract: In treating exhaust gases containing SO.sub.2, HCl and HF, there is disclosed a method of treating such exhaust gas which comprises detecting the amounts of HCl and HF in the exhaust gas and supplying an amount of a magnesium compound commensurate with a stoichiometric amount to become at least MgCl.sub.2 and MgF.sub.2 in an exhaust-gas treating tower and a calcium compound as a SO.sub.2 solvent into the exhaust-gas treating tower.The aforesaid method of treating an exhaust gas comprises a method of causing Mn ion to coexist in an absorbing solution in contact with the exhaust gas.

Abstract: A solution or slurry containing a carbonate or sulfite, or both is continuously supplied into a tightly closed vessel, while any excess of the liquid is allowed to overflow the vessel. Sulfuric acid is supplied into the vessel to maintain the pH level of the liquid in the vessel at a value not exceeding 3. Air is supplied into the vessel as a carrier gas for CO.sub.2 or SO.sub.2 or both formed by the reaction of the carbonate or sulfite or both in the liquid with the sulfuric acid. The carrier gas is collected from the vessel, and the concentration of CO.sub.2 or SO.sub.2 or both in the carrier gas is determined. The concentration of the carbonate or sulfite or both in the liquid is obtained by calculations from the concentration of CO.sub.2 or SO.sub.2 or both, the flow rate of the liquid and the flow rate of the carrier gas.

Abstract: The present invention is directed to a method for treating a waste gas to separate and recover gypsum and a dust therein, characterized by comprising the steps of causing the waste gas to pass through a dry dust collector; introducing the gas into a gas absorber, in which a slurry containing at least one of calcium hydroxide or calcium carbonate as an absorbent is employed to remove SO.sub.2 and the dust passed through the dry dust collector from the waste gas; blowing air into the resultant absorbing liquid in the gas absorber to oxidize the absorbing liquid and to thereby produce gypsum; delivering them to an absorbing liquid tank, in which the slurry mainly containing the gypsum grains is separated from the other slurry mainly containing the dust by partition walls disposed therein; and directly taking out the respective slurries separately from the absorbing liquid tank.