Mitsubishi Jukogyo Kabushiki Kaisha

Mitsubishi Heavy Industries Limited

Kiyoshi Okazoe

Toru Takashina

Susumu Okino

Naohiko Ukawa

Eiji Ochi

Atsushi Tatani

Taku Shimizu

Masao Hino

Kazuaki Kimura

Takashi Haruki

Koichiro Iwashita

Masakazu Onizuka

Yoshio Nakayama

Toyoshi Nakagawa

Makiichi Ishihara

Yasuyuki Ogushi

Kenichi Sato

Hiroyuki Nemoto

Tatsuto Nagayasu

Takeo Shinoda

Shigeo Hasegawa

Hiroshi Suzumura

Shinichiro Kotake

Masato Kaneko

Hiroyuki Katayama

Koosoo Tao

Tamotsu Higuchi

Yoichi Shiga

Kenichiro Kawamichi

Kyozo Suyama

Nobuo Kojima

Masaharu Yoshimi

Five combustion exhaust gas treatment systems capable of removing dust and selenium (Se) in combustion exhaust gas and making harmless are proposed: (1) combustion exhaust gas is cooled to 350&deg; C. or less, dust is separated, Se is transformed into insoluble compound, and Se is separated; (2) combustion exhaust gas is cooled to 350&deg; C. or less, dust is separated, Se elution preventive agent is added, and dust is formed into scale; (3) dust in combustion exhaust gas is collected by dust collector, dust is formed into slurry by making use of part of circulation liquid in desulfurization apparatus, and tetravalent Se in dust slurry is transformed into insoluble compound, which is separated into solid and liquid; (4) dust is separated from combustion exhaust gas by dust collector, and it is heated to gasify Se, and is led into desulfurization apparatus, etc., and formed into slurry, and Se is made into insoluble compound; and (5) a treating agent for making tetravalent Se insoluble is added to part of circulation liquid in desulfurization apparatus, and it is sprayed into combustion exhaust gas to make Se insoluble.

Combustion exhaust gas treatment system

This invention provides a flue gas treating process for removing sulfur oxides and dust from exhaust gas containing sulfur oxides and dust by using an absorption tower into which an absorbing fluid containing an alkaline agent is sprayed, comprising the steps of equipping the absorption tower with integrally formed dust collection means comprising dust collecting plates and discharge electrodes, and with dust separation means for sweeping off the dust collected by the dust collection means; and treating the exhaust gas in the dust collection means and subsequently cleaning the exhaust gas in the absorption tower, whereby desulfurization and dust removal are effected while sweeping off the collected dust by the dust separation means. Thus, desulfurization and dust removal can be effected in a simple manner, and the capacity of an electrostatic precipitator installed on the upstream side can be reduced.

Flue gas treating process and apparatus

Five combustion exhaust gas treatment systems capable of removing dust and selenium (Se) in combustion exhaust gas and making harmless are proposed: (1) combustion exhaust gas is cooled to 350.degree. C. or less, dust is separated, Se is transformed into insoluble compound, and Se is separated; (2) combustion exhaust gas is cooled to 350.degree. C. or less, dust is separated, Se elution preventive agent is added, and dust is formed into scale; (3) dust in combustion exhaust gas is collected by dust collector, dust is formed into slurry by making use of part of circulation liquid in desulfurization apparatus, and tetravalent Se in dust slurry is transformed into insoluble compound, which is separated into solid and liquid; (4) dust is separated from combustion exhaust gas by dust collector, and it is heated to gasify Se, and is led into desulfurization apparatus, etc., and formed into slurry, and Se is made into insoluble compound; and (5) a treating agent for making tetravalent Se insoluble is added to part of circulation liquid in desulfurization apparatus, and it is sprayed into combustion exhaust gas to make Se insoluble.

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.

Flue gas treating process and system

This invention provides a flue gas treating system which, though having a basic construction using a small-sized and high-performance gas-liquid contact apparatus comprising the combination of a parallel-flow absorption tower and a counterflow absorption tower, can reduce the ammonia concentration in the treated flue gas to a low level. This system includes a tank (21) for holding an absorbing fluid fed thereto; an inlet side absorption tower (22) of the counterflow type which extends upward from one lateral part of the tank (21) and in which untreated flue gas (A) is introduced from its lower end and brought into gas-liquid contact with the absorbing fluid within the tank (21); and an outlet side absorption tower (23) of the parallel-flow type which extends upward from another lateral part of the tank (21) and in which the flue gas leaving the inlet side absorption tower (22) is introduced from its upper end and brought into gas-liquid contact with the absorbing fluid within the tank (21).

Flue gas treating system and process

An exhaust gas treatment apparatus for the removal of at least a sulfur dioxide gas and ammonia from an exhaust gas by bringing the exhaust gas into vapor-liquid contact with an absorbing liquid comprises an introduction-side tank to which the absorbing liquid is supplied, a parallel-flow type absorption tower positioned above the introduction-side tank; an ejection side tank positioned adjacent the introduction side tank; a counter-flow type absorbing tower positioned above the ejection side tank; a mist eliminator for removing splash mist from the exhaust gas; and a controller for controlling the pH of the absorbing liquid in one of the introduction-side absorption tower and the ejection-side absorption tower.

Exhaust gas treatment apparatus and method

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.

Sewage treatment process

A corrosion preventive method and an apparatus for preventing corrosion of stainless steel components in an exhaust gas desulfurizing apparatus of an exhaust gas treatment system comprising the exhaust gas desulfurizing apparatus for removing at least sulfur dioxide by bringing exhaust gas into contact with absorbing solution, wherein specific means is employed to maintain the Cl.sup.- concentration and SO.sub.4.sup.2- concentration at a corrosion preventive side of the corrosion resisting limit of stainless steel.

Method and apparatus for preventing corrosion of exhaust gas treatment

This invention provides a flue gas treating system and process which include a counterflow absorption tower and which can reduce the ammonia concentration in the treated flue gas to a low level. This system includes an absorbing fluid tank (21) which is installed separately from an absorption tower tank (1) and into which the absorbing fluid after coming into gas-liquid contact with untreated flue gas in an absorption tower (2) and before flowing down into the absorption tower tank (1) is introduced; first injection means for injecting the absorbing fluid within the absorption tower tank (1) into the absorption tower (2) at a first position above the flue gas inlet section (3) thereof so as to bring this absorbing fluid into gas-liquid contact with the untreated flue gas; and second injection means for injecting the absorbing fluid within the absorbing fluid tank (21) into the absorption tower (2) at a second position above the first position so as to bring this absorbing fluid into gas-liquid contact with the untreated flue gas prior to the absorbing fluid within the absorption tower tank (1).

A wet flue gas desulfurization system for removing sulfur dioxide present in flue gas by absorption into an absorbent slurry includes an absorption tower having at a bottom thereof a tank for holding an absorbent slurry; a circulating pump for feeding the absorbent slurry within the tank to a flue gas inlet section in an upper part of the absorption tower and bringing the absorbent slurry into contact with flue gas; and a slurry preparation compartment provided on one side of the tank of the absorption tower and separated from a flue gas passage section by a partition wall having its lower end submerged below a surface of the absorbent slurry, whereby an absorbent and water constituting the absorbent slurry are directly introduced into the slurry preparation compartment.

Wet flue gas desulfurization system

A flue gas treating system for removing sulfur dioxide and dust present in flue gas by gas-liquid contact with an absorbing fluid and has an inlet side absorption tower of the liquid column type and an outlet side absorption tower of the liquid column type, each of which has a uniform cross-section over the area of gas-liquid contact, and the cross-section of flue gas in the inlet side absorption tower is smaller than the cross section of flue gas in the outlet side absorption tower. The inlet side absorption tower is constructed in the form of a parallel-flow absorption tower wherein the flue gas flows downward for favorable collection of dust and absorption of sulfur dioxide. The outlet side absorption tower is constructed in the form of a counter-flow adsorption tower wherein the flue gas flows upward for favorable absorption of sulfur dioxide. The absorbing fluid within a tank is injected upward from a plurality of spray pipes.

This invention relates to a flue gas treating system including a desulfurization apparatus for bringing flue gas into contact with a calcium compound-containing slurry so as to cause sulfur dioxide present in the flue gas to be absorbed into the slurry, oxidizing the slurry having undergone contact with flue gas, and subjecting the oxidized slurry to solid-liquid separation so as to obtain gypsum as a by-product; a waste water treating apparatus for treating part of a first filtrate produced during solid-liquid separation of the slurry having undergone contact with flue gas in the desulfurization apparatus; and solid-liquid separation device for subjecting sludge produced in the waste water treating apparatus to solid-liquid separation independently of the slurry having undergone contact with flue gas, wherein a solid material separated from the sludge by the solid-liquid separation device is incorporated into the gypsum and all of a second filtrate produced during solid-liquid separation of the sludge by the solid-liquid separation device is introduced into the waste water treating apparatus together with part of the first filtrate. In this system, the dumping disposal of sludge produced in the waste water treating apparatus is not required and the concentration of impurities in the absorbent slurry within the desulfurization apparatus can be kept on a low level.

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Tokyo, Japan

Kiyoshi Okazoe