Abstract: The impurity removal method removes impurities in an exhaust gas and includes forming a froth layer in a tank, by blowing the exhaust gas into an absorbing liquid contained in the tank via a gas dispersion pipe, wherein, given that a proportion of the gas occupying the froth layer is defined as a gas holdup, impurities such as soot dust included in a gas such as an exhaust gas is removed efficiently and at a low cost by setting a gas holdup in the froth layer to be 0.4˜0.9, setting a height of the froth layer to be 0.2˜1.8 m, and setting a gas-liquid contact area per unit volume of the froth layer to be 1500˜2500 m2/m3.

Abstract: The impurity removal method removes impurities in an exhaust gas and includes forming a froth layer in a tank, by blowing the exhaust gas into an absorbing liquid contained in the tank via a gas dispersion pipe, wherein, given that a proportion of the gas occupying the froth layer is defined as a gas holdup, impurities such as soot dust included in a gas such as an exhaust gas is removed efficiently and at a low cost by setting a gas holdup in the froth layer to be 0.4˜0.9, setting a height of the froth layer to be 0.2˜1.8 m, and setting a gas-liquid contact area per unit volume of the froth layer to be 1500˜2500 m2/m3.

Abstract: Provided is a desulfurization method for sulfur oxide gas that includes: bringing a first sulfur oxide gas into contact with a humidifying liquid to obtain a second gas; separating at least part of the humidifying liquid from the second gas to obtain a third gas; contacting the third gas with an alkaline agent-containing liquid and oxygen to remove sulfur oxide from the third gas; using the alkaline agent-containing liquid as the humidifying liquid to be brought into contact with the first gas in the humidifying liquid contact step; acquiring at least part of the humidifying liquid separated from the second gas; removing gas from the humidifying liquid; and recovering a by-product, the alkaline agent-containing liquid, and oxygen from the humidifying liquid from which the gas has been removed in the gas removal step, the by-product recovery step being performed only downstream of the humidifying liquid acquisition step.

Abstract: To provide a method for predicting a deactivation phenomenon in a flue-gas desulfurization unit to prevent the occurrence of the deactivation phenomenon before it happens. There is provided a method for preventing the occurrence of a deactivation phenomenon in a flue-gas desulfurization unit that treats flue gas of a coal-fired boiler, the method includes calculating a deactivation potential as an index of the deactivation phenomenon based on alkaline components such as Na, Ca, Mg, and K contained in ash in the flue gas, and performing an operation management, such as adjustment of set value of a pH control system, on the flue-gas desulfurization unit depending on change of the deactivation potential.

Abstract: This desulfurization device is for desulfurizing a discharge gas which contains sulfur oxides and which was discharged from a device for sulfuric acid production that includes a concentrated-sulfuric-acid production step in which sulfur trioxide gas obtained by oxidizing sulfur dioxide gas is absorbed in an aqueous sulfuric acid solution while supplying water thereto to thereby produce sulfuric acid having a concentration as high as 90 wt % or more but less than 99 wt %, the desulfurization device comprising: a desulfurization tower in which the sulfur oxides are removed from the discharge gas and, simultaneously therewith, dilute sulfuric acid is formed from the sulfur oxides; and a dilute sulfuric acid mixer which, in the concentrated-sulfuric-acid production step, mixes the dilute sulfuric acid with the aqueous sulfuric acid solution.

Abstract: Provided is a desulfurization method for sulfur oxide gas that includes: bringing a first sulfur oxide gas into contact with a humidifying liquid to obtain a second gas; separating at least part of the humidifying liquid from the second gas to obtain a third gas; contacting the third gas with an alkaline agent-containing liquid and oxygen to remove sulfur oxide from the third gas; using the alkaline agent-containing liquid as the humidifying liquid to be brought into contact with the first gas in the humidifying liquid contact step; acquiring at least part of the humidifying liquid separated from the second gas; removing gas from the humidifying liquid; and recovering a by-product, the alkaline agent-containing liquid, and oxygen from the humidifying liquid from which the gas has been removed in the gas removal step, the by-product recovery step being performed only downstream of the humidifying liquid acquisition step.

Abstract: This desulfurization device is for desulfurizing a discharge gas which contains sulfur oxides and which was discharged from a device for sulfuric acid production that includes a concentrated-sulfuric-acid production step in which sulfur trioxide gas obtained by oxidizing sulfur dioxide gas is absorbed in an aqueous sulfuric acid solution while supplying water thereto to thereby produce sulfuric acid having a concentration as high as 90 wt % or more but less than 99 wt %, the desulfurization device comprising: a desulfurization tower in which the sulfur oxides are removed from the discharge gas and, simultaneously therewith, dilute sulfuric acid is formed from the sulfur oxides; and a dilute sulfuric acid mixer which, in the concentrated-sulfuric-acid production step, mixes the dilute sulfuric acid with the aqueous sulfuric acid solution.

Abstract: To provide a method for predicting a deactivation phenomenon in a flue-gas desulfurization unit to prevent the occurrence of the deactivation phenomenon before it happens. There is provided a method for preventing the occurrence of a deactivation phenomenon in a flue-gas desulfurization unit that treats flue gas of a coal-fired boiler, the method includes calculating a deactivation potential as an index of the deactivation phenomenon based on alkaline components such as Na, Ca, Mg, and K contained in ash in the flue gas, and performing an operation management, such as adjustment of set value of a pH control system, on the flue-gas desulfurization unit depending on change of the deactivation potential.

Abstract: The exhaust gas treatment apparatus has a sealed vessel which is vertically partitioned into two spaces by a partition. A portion of the sealed vessel lower than the partition is an absorbing liquid storage portion, and a portion of the sealed vessel upper than the partition is an exhaust gas introducing portion. The partition is provided with a large number of sparger pipes so that the sparger pipes reach inside an absorbing liquid stored in the absorbing liquid storage portion. The partition is provided with a single gas riser in communication with a space upper than the absorbing liquid in the absorbing liquid storage portion. An upper end of the gas riser passes through a top plate portion of the sealed vessel and protrudes upward.

Abstract: The exhaust gas treatment apparatus has a sealed vessel which is vertically partitioned into two spaces by a partition. The partition is provided with a gas riser for deriving treated exhaust gas from an upper space of the absorbing liquid storage portion. A large number of sparger pipes are provided in a effective region, so as to reach inside an absorbing liquid stored in the absorbing liquid storage portion. A non-jet region is provided in the effective region. The froth layer is not formed in the non-jet region, and the absorbing liquid in a foamed state flows down from the froth layer therearound to circulate the absorbing liquid.

Abstract: The exhaust gas treatment apparatus has a sealed vessel which is vertically partitioned into two spaces by a partition. The partition is provided with a gas riser for deriving treated exhaust gas from an upper space of the absorbing liquid storage portion. A large number of sparger pipes are provided in a effective region, so as to reach inside an absorbing liquid stored in the absorbing liquid storage portion. A non-jet region is provided in the effective region. The froth layer is not formed in the non-jet region, and the absorbing liquid in a foamed state flows down from the froth layer therearound to circulate the absorbing liquid.

Abstract: The exhaust gas treatment apparatus has a sealed vessel which is vertically partitioned into two spaces by a partition. A portion of the sealed vessel lower than the partition is an absorbing liquid storage portion, and a portion of the sealed vessel upper than the partition is an exhaust gas introducing portion. The partition is provided with a large number of sparger pipes so that the sparger pipes reach inside an absorbing liquid stored in the absorbing liquid storage portion. The partition is provided with a single gas riser in communication with a space upper than the absorbing liquid in the absorbing liquid storage portion. An upper end of the gas riser passes through a top plate portion of the sealed vessel and protrudes upward.