Babcock-hitachi Kabushiki Kaisha

Mitsubishi Hitachi Power Systems, Ltd.

Hiroyuki Nosaka

Hiroshi Takezaki

Hirofumi Kikkawa

Takanori Nakamoto

Hiroshi Ishizaka

Kazuki Kobayashi

Toshio Katsube

Jun Shimamura

Naoki Oda

Atsushi Katagawa

Kouji Muramoto

Takuro Ueda

Takayuki Saitou

Tomoyuki Konishi

Goki Sasaki

Yoshinori Taguchi

In an absorbing tower including an absorption unit of relatively small diameter capable of absorption and removal by an absorbent slurry for exhaust gas purification and a tank unit of relatively large diameter for temporarily storing the absorbent slurry flowing down from the absorption unit, the tank unit and the absorption unit are joined together by a conical member. By disposing an entrance flue at the conical member, a distance from an upper portion of the conical member to a spray header is shortened, and a height of the absorbing tower can be reduced accordingly. By extending a front end of the entrance flue to the absorption unit into which droplets of the absorbent slurry fall, a high-temperature exhaust gas from a boiler, etc., that has passed through the entrance flue, is made to pass through a circumference of the conical member so that an inexpensive material can be used in the conical member.

Wet flue-gas desulfurization equipment

After adjusting an exhaust gas temperature at an exit of a heat recovery unit () of an exhaust gas treating apparatus to not more than a dew point temperature of sulfur trioxide (SO), a heavy metal adsorbent is supplied from a heavy metal adsorbent supply unit () disposed in an exhaust gas at an entrance of a precipitator () or an intermediate position within the precipitator (), and the exhaust gas containing the heavy metal adsorbent is supplied into the precipitator (). Preferably at this stage, the heavy metal adsorbent is supplied into the exhaust gas at the entrance of the precipitator () 0.1 seconds after the exhaust gas temperature at the exit of the heat recovery unit () has been adjusted to not more than the dew point temperature of SO. Further preferably, in order to prevent acid corrosion of equipment, the heavy metal adsorbent is supplied after spraying an alkali into the exhaust gas at the entrance or exit of the heat recovery unit () and adjusting the exhaust gas temperature at the exit of the heat recovery unit to not more than the dew point temperature of SO. Accordingly, even when coal with a high sulfur content is used as fuel, heavy metals in the exhaust gas can be removed effectively.

Exhaust gas treating method and apparatus

A system is provided that prevents inhibition of adsorption of Hg and other heavy metals by activated carbon or other heavy metal adsorbent due to prior adsorption of sulfur trioxide (SO) in an exhaust gas containing SO. As it has been found that while SOis adsorbed, the adsorption of SOprecedes the adsorption of Hg and other heavy metals onto activated carbon, a basic substance injection system is disposed along an exhaust gas flow channel at an upstream side of an activated carbon injection system, thereby attaining effective removal of Hg and other heavy metals from the exhaust gas by adsorption thereof onto surface pores of the activated carbon. The SOconcentration after removal by basic substance conversion is computed from the SOconcentration before removal, and the activated carbon injection rate can be controlled based on the concentration after removal.

Exhaust gas purifying method and apparatus

A method and apparatus for treating an exhaust gas comprising heavy metals, wherein the apparatus comprises a heat recovery unit, recovering exhaust gas heat at an exit of the air preheater; a precipitator, collecting soot/dust contained in an exhaust gas at an exit of the heat recovery unit; a wet flue gas desulfurizer, removing sulfur oxides contained in the exhaust gas at the exit of the precipitator; and a reheater, heating the exhaust gas at the exit of the wet flue gas desulfurizer. Each of the heat recovery unit and the reheater has a heat exchanger tube, and a circulation line is disposed to connect the heat exchanger tubes. A sulfur trioxide (SO) removing agent is supplied to the upstream side of the heat recovery unit, and the temperature of the exhaust gas at the exit of the heat recovery unit is adjusted to not more than a dew point of sulfur trioxide.

Method and apparatus for treating discharge gas

Flue gas of boiler is introduced through gas inlet part of flue-gas desulfurization apparatus, and absorbent liquid sprayed from spray nozzle is trapped in recirculation tank. There, agitation is performed by oxidation agitator to thereby oxidize SOabsorbed from the flue gas into gypsum. In the tank, oxidation air is fed from posterior air pipe and anterior air pipe behind and ahead of liquid propulsion by the propeller. Thus, even when the amount of oxidation air must be increased in accordance with an increase of boiler load, the oxidation efficiency can be enhanced without increasing the number of agitators. Then the apparatus with which even when the amount of oxidation air fed to the liquid trapping section is increased, highly efficient oxidation can be performed without increasing the number of agitators installed and the operating cost.

Wet flue-gas desulfurization apparatus and method of wet flue-gas desulfurization

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Hiroshima, Japan

Hiroyuki Nosaka