Abstract: A gas combustion treatment method for the combustion treatment of an ammonia-containing gas and a hydrogen sulfide-containing gas, the method comprising a first combustion treatment step in which the ammonia-containing gas, together with a fuel, is introduced and burned; a nitrogen oxide reduction step downstream of the first combustion treatment step, in which a portion of the hydrogen sulfide-containing gas or the ammonia-containing gas is introduced and the nitrogen oxides produced in the first combustion treatment step are reduced in a reducing atmosphere; and a second combustion treatment step downstream of the nitrogen oxide reduction step, in which the remaining hydrogen sulfide-containing gas, together with air, is introduced and burned. The present invention provides a combustion apparatus suitable for use as a combustion furnace for off-gases resulting from the wet purification of coal gasification gas.

Abstract: The present invention provides a method for the treatment of mercury present in exhaust gas wherein, after a chlorinating agent is added to exhaust gas containing nitrogen oxides, sulfur oxides and mercury, the exhaust gas is subjected to a reductive denitration treatment in the presence of a solid catalyst and then to wet desulfurization using an alkaline absorbing fluid, the method being characterized by measuring the mercury concentration in the exhaust gas after the wet desulfurization; calculating a predicted value of the inlet mercury concentration before the reductive denitration treatment on the basis of the measured mercury concentration; and controlling the feed rate of the chlorinating agent added prior to the reductive denitration treatment, according to the deviation of the predicted value from a reference inlet mercury concentration, as well as a system for the treatment of exhaust gas.

Abstract: The present invention provides an exhaust gas treatment method including oxidation treatment for converting metallic mercury contained in combustion exhaust gas into mercury chloride; and mercury removal treatment for removing mercury from the combustion exhaust gas by dissolving the mercury chloride in water, wherein a plurality of oxidation catalysts for performing the oxidation treatment are provided, and during the time when the oxidation treatment is performed, at least one of the oxidation catalysts performs catalyst performance restoration treatment without performing oxidation treatment. According to the present invention, the deterioration in mercury removal performance can be restrained even in continuous operation on condition that mercury is oxidized in a low temperature region not higher than 300° C.

Abstract: Provided is an exhaust gas treating tower in which exhaust gas flow velocity is increased more than a prior art case so that exhaust gas treating efficiency can be enhanced or the exhaust gas treating tower can be made compact if equivalent performance is to be maintained. Also, an exhaust gas treating tower ensuring a liquid recovery is provided. In an exhaust gas treating tower 10A, liquid columns C are generated and also a liquid drop generating member 20 is provided to thereby generate liquid drops M therearound to be floated. Also, liquid is spouted from spray nozzles to thereby generate liquid films F in area different from the liquid columns C. In an exhaust gas treating tower 110, a liquid drop eliminator 120 is provided upstream of a mist eliminator 118. Interval P1 of collecting plates 121 of the liquid drop eliminator 120 is made larger than interval P2 of collecting plates 119 of the mist eliminator 118.

Abstract: The present invention provides a system for removing mercury in exhaust gas, in which mercury is removed from exhaust gas of a boiler, characterized in that between a denitrification apparatus and a wet type desulfurization apparatus, an NH3 decomposition catalyst and a mercury oxidation catalyst are provided, and mercury having been oxidized into mercury chloride is removed by the wet type desulfurization apparatus. Also, it provides a method for removing mercury in exhaust gas, characterized in that the mercury removing method includes an NH3 decomposition process and a mercury oxidation process, which are provided between the denitrification process and a wet desulfurization process, and mercury having been oxidized into mercury chloride is removed in the wet desulfurization process.

Abstract: The present invention provides a method for removing mercury in exhaust gas, in which mercury in exhaust gas discharged from combustion equipment is removed, characterized by including a mercury oxidation process in which mercury in the exhaust gas is converted to mercury chloride in the presence of a catalyst; a contact process in which the exhaust gas is brought into contact with an absorbing solution in a scrubber to absorb and remove mercury components from the exhaust gas; and a control process in which blowing of air or addition of an oxidizing agent into the scrubber is accomplished, and the amount of blown air or the added amount of oxidizing agent is regulated to control the oxidation-reduction potential of the absorbing agent, and a system for removing mercury in exhaust gas. According to the mercury removing method in accordance with the present invention, a phenomenon that mercury chloride is reduced into metallic mercury by SO2 etc.

Abstract: The present invention provides a mercury removal method which can effectively remove very small amounts of mercury components present in a gas during wet gas purification such as coal or heavy oil gasification gas purification and petroleum refining. A mercury removal method for the removal of mercury present in a gas, the method comprising the steps of bringing a gas containing at least mercury and not less than 10 ppm of hydrogen sulfide into gas-liquid contact with an absorbing fluid under pressurized conditions so as to cause mercury to pass into the absorbing fluid; flashing the mercury-containing absorbing fluid under lower-pressure conditions to separate it into gaseous components and liquid components; and removing the mercury contained in the separated gaseous components by adsorption to an adsorbent.

Abstract: The present invention provides a method for the treatment of mercury present in exhaust gas wherein, after a chlorinating agent is added to exhaust gas containing nitrogen oxides, sulfur oxides and mercury, the exhaust gas is subjected to a reductive denitration treatment in the presence of a solid catalyst and then to wet desulfurization using an alkaline absorbing fluid, the method being characterized by measuring the mercury concentration in the exhaust gas after the wet desulfurization; calculating a predicted value of the inlet mercury concentration before the reductive denitration treatment on the basis of the measured mercury concentration; and controlling the feed rate of the chlorinating agent added prior to the reductive denitration treatment, according to the deviation of the predicted value from a reference inlet mercury concentration, as well as a system for the treatment of exhaust gas.

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.

Abstract: An apparatus for removing mercury from a waste gas comprises a catalytic oxidizing apparatus in which the metal mercury in a combustion waste gas containing SOx and mercury is oxidized into mercury chloride under the reaction temperature not higher than 300° C. in the presence of a solid catalyst, a wet desulfurizing apparatus for removing mercury by using an alkaline absorbing solution, and a temperature control apparatus for controlling the reaction temperature in oxidizing the metal mercury into mercury chloride.

Abstract: A gas combustion treatment method for the combustion treatment of an ammonia-containing gas and a hydrogen sulfide-containing gas, the method comprising a first combustion treatment step in which the ammonia-containing gas, together with a fuel, is introduced and burned; a nitrogen oxide reduction step downstream of the first combustion treatment step, in which a portion of the hydrogen sulfide-containing gas or the ammonia-containing gas is introduced and the nitrogen oxides produced in the first combustion treatment step are reduced in a reducing atmosphere; and a second combustion treatment step downstream of the nitrogen oxide reduction step, in which the remaining hydrogen sulfide-containing gas, together with air, is introduced and burned. The present invention provides a combustion apparatus suitable for use as a combustion furnace for off-gases resulting from the wet purification of coal gasification gas.

Abstract: The present invention provides a mercury removal method which can effectively remove very small amounts of mercury components present in a gas during wet gas purification such as coal or heavy oil gasification gas purification and petroleum refining. A mercury removal method for the removal of mercury present in a gas, the method comprising the steps of bringing a gas containing at least mercury and not less than 10 ppm of hydrogen sulfide into gas-liquid contact with an absorbing fluid under pressurized conditions so as to cause mercury to pass into the absorbing fluid; flashing the mercury-containing absorbing fluid under lower-pressure conditions to separate it into gaseous components and liquid components; and removing the mercury contained in the separated gaseous components by adsorption to an adsorbent.

Abstract: The present invention provides an exhaust gas treatment process wherein exhaust gas containing mercury and sulfur dioxide is subjected to a desulfurization treatment in a desulfurizing absorption tower and then passed through a mist eliminator for removing and recovering mist from the desulfurized exhaust gas, the process including the step of removing mercury from the desulfurized exhaust gas by feeding thereto an oxidizing agent such as sodium hypochlorite and an antioxidant such as methanol unreactive with the oxidizing agent at a position upstream of the aforesaid mist eliminator.

Abstract: The present invention provides an exhaust gas treatment process wherein exhaust gas containing mercury and sulfur dioxide is subjected to a desulfurization treatment in a desulfurizing absorption tower and then passed through a mist eliminator for removing and recovering mist from the desulfurized exhaust gas, the process including the step of removing mercury from the desulfurized exhaust gas by feeding thereto an oxidizing agent and an antioxidant unreactive with the oxidizing agent at a position upstream of the aforesaid mist eliminator. The process of the present invention makes it possible to remove mercury, particularly metallic mercury vapor, effectively from a large-volume gas (e.g., exhaust gas from an electric power plant) and to reduce the operating cost of an exhaust gas treatment system significantly.