Mitsubishi Jukogyo Kabushiki Kaisha

Mitsubishi Heavy Industries Limited

Taku Shimizu

Atsushi Tatani

Susumu Okino

Naohiko Ukawa

Toru Takashina

Kazuaki Kimura

Kiyoshi Okazoe

Masao Hino

Naoharu Shinoda

Takashi Haruki

Masakazu Onizuka

Eiji Ochi

Koichiro Iwashita

Kenji Inoue

Yoshikazu Endo

Makoto Susaki

Toshikuni Sera

Kenichi Yoneda

Masumi Atsukawa

Hiroshi Fujita

Masato Kaneko

Satoru Sugita

Setsuo Omoto

Koosoo Tao

Tsuyoshi Ohishi

Masato Miyake

Kouichiro Iwashita

Kenzo Muramatsu

Hidehiko Otani

Hideki Kamiyoshi

Mamoru Yokose

Toshiaki Kinomoto

Yasuyuki Ogushi

Morikata Nishida

Hiroshi Baba

Masaharu Yoshimi

A gas refining method for adsorbing a reducing gas obtained by pressure gasification of coal or oil comprises introducing a reducing gas stream into an adsorbing and removing zone where it contacts an adsorbent. Sulfur-containing compounds are adsorbed onto the adsorbent and a first oxygen-containing gas stream is introduced into the adsorbing and removing zone in order to form a regeneration gas containing sulfur dioxide. The regeneration gas is contacted with a second oxygen-containing stream and a calcium-containing liquid slurry to effect absorption of sulfur dioxide by the slurry and precipitation of a gypsum compound. The temperature of the slurry is varied to cause selective precipitation of 60 -gypsum hemihydrate or gypsum dihydrate.

Gas refining system

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

The present invention relates to a process for the treatment of arsenic-containing sludge obtained by adjusting arsenic-containing waste water to a PH of 12 or greater by the addition of a calcium compound and subjecting the waste water to solid-liquid separation, the process comprising the steps of adding a calcium compound to the arsenic-containing sludge slurry obtained by the solid-liquid separation, dewatering the resulting sludge, drying the dewatered sludge, and calcining the dried sludge. According to the present invention, arsenic-containing sludge obtained by treating waste water to precipitate arsenic present therein can be calcined to yield a calcined product which involves no risk of arsenic redissolution when it is dumped. Moreover, there is no possibility that arsenic compounds may be volatilized during calcination.

Process for the treatment of arsenic-containing sludge

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.

A method of treatment of an arsenic sludge obtained from a solid-liquid separation step on arsenic waste water by adjusting the value of pH to 12 or higher by adding a calcium compound is disclosed. The method is characterized by addition of hydrated lime and calcining the sludge.

Method of treating sludge containing arsenic

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 gas refining system for adsorbing a reducing gas includes a reduced gas stream, a section for adsorbing and removing sulfur-containing compounds in the reducing gas, an adsorbent which contacts the reduced gas stream, an oxygen-gas containing stream which enters the adsorbing and removing section, a calcium-compound containing stream, and a reactor which receives the above streams and allows for the adsorption of sulfur dioxide and precipitation of a gypsum compound.

The present invention relates to a slurry thickening tank comprising a tank body disposed below the surface of a slurry within a slurry tank, a slurry inlet provided in the upper part of the tank body, a thickened slurry outlet provided in the lower part of the tank body, and supernatant liquid withdrawal means provided in the upper part of the tank body, whereby the slurry introduced into the tank body through the slurry inlet is thickened by sedimentation in the tank body and the resulting thickened slurry is discharged from the tank body through the slurry outlet, wherein the surface of the structural member of the tank body extending from the slurry inlet to the thickened slurry outlet has an angle of inclination greater than the angle of repose for the thickened slurry, and to an absorption tower for use in flue gas desulfurization systems which is equipped with such a slurry thickening tank. This slurry thickening tank can maintain satisfactory operating conditions for a long period of time without developing any trouble such as a blockage of the thickened slurry outlet.

Slurry thickening tank and absorption tower for use in wet flue gas

A solid-liquid separator comprising a first roller disposed on one side of a tank containing a slurry subjected to solid-liquid separation at such a height that the lower part thereof is immersed in the slurry, and driven rotationally in a direction which enables the slurry attached to its surface to be lifted up and discharged to the outside of the tank; and a second roller disposed above the first roller facing the first roller so that the second roller comes into pressure contact with the slurry attached to the first roller and lifted up so as to remove the liquid from the slurry; as well as a wet flue gas desulfurization apparatus using this solid-liquid separator.

Solid-liquid separator and wet flue gas desulfurization apparatus

This invention is related to a slurry filtration device and the wet lime-gypsum flue-gas desulfurization system comprising a slurry filtration device for the separation (concentration) of gypsum. The slurry filtration device comprises tank that has a slurry supply pipe at its upper part and a filtrate-drain hole at its bottom, a layer of filter sand lying on its bottom, a slurry accumulator arranged on the layer of filter sand, and a vibrator set in said slurry accumulator for vibrating the slurry. The present invention not only improves the solid-liquid separability remarkably but also saves cost and space.

Slurry filtration device and flue-gas desulfurization system

A wet type flue gas desulfurization apparatus in which desulfurization of flue gas is carried out through gas/liquid phase contact of flue gas with an absorbent slurry. More particularly, disclosed in a combined absorption tower comprising an absorbent slurry liquid tank, a thickening tank serving for concentration by settling of a reaction product slurry formed through the reaction of the absorbent and SO.sub.2 present in flue gas, an absorption section situated above said liquid tank for the gas/liquid contact of flue gas and the absorbent slurry as well as for carrying out the desulfurization reaction, and a stack section situated above said absorption section serving for the dispersion of the treated flue gas into the atmosphere, wherein the absorption section is provided with nozzles for upward spraying of the absorbent slurry, and flue gas introduced at the bottom of said absorption section and absorbent slurry sprayed through the nozzles are subjected to gas/liquid contact, and a unreacted portion of the absorbent slurry and a reaction product slurry descend into said liquid tank, and the reaction product slurry from said liquid a tank is introduced into said thickening tank.

Wet type flue gas desulfurization apparatus

A flue gas desulfurization process for treating flue gases containing SO.sub.2, NO.sub.x, and halogen gases by the wet lime method, in which part of the absorbent liquid is extracted, freed from iodine, and recycled as makeup water to the absorption column.

Flue gas desulfurization process

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Tokyo, Japan

Taku Shimizu