Mitsubishi Jukogyo Kabushiki Kaisha

Mitsubishi Heavy Industries Limited

Other

Mitsubishi Petrochemical Company Limited

Nichias Corporation

Mitsubishi Jukogyo K.k.

Mitsubishi Jukogyo Kaisha

Catalysts & Chemical Co., Ltd.

Atsushi Morii

Osamu Naito

Toshiyuki Onishi

Norihisa Kobayashi

Kozo Iida

Satoru Serizawa

Yoshiaki Obayashi

Shigeru Nojima

Kouzo Iida

Toshio Koyanagi

Shigeyuki Nishijima

Shigeaki Mitsuoka

Shozo Kaneko

Hiromu Takatsuka

Hitoshi Nakamura

Makoto Imanari

Jun Tanabe

Toru Seto

Touru Seto

Morio Fukuda

Masayuki Hanada

Akira Hattori

Takeo Koshikawa

Akihiro Yamauchi

Kiyoshi Nagano

Katsuo Hashizaki

Hiroaki Rikimaru

Shuya Nagayama

Masaaki Taniguchi

Teruko Shimada

Masaki Miyazawa

Kouzou Iida

Toshihiko Imamoto

Masanori Demoto

Kiyoaki Imoto

Kouhei Suyama

The present invention provides a method of denitrating exhaust gas, which can control the NOx removal efficiency of exhaust gas at 90% or higher while suppressing the release of unreacted ammonia to 0.1 ppm or less. The method carries out denitration of exhaust gas for removing nitrogen oxides with catalytic reduction by introducing a nitrogen-oxide-containing gas into a catalyst-filled reaction chamber and adding ammonia as reducing agent in an excessive amount to the same chamber. The method comprises the steps of: introducing exhaust gas and ammonia into a first denitrating catalyst layer disposed on the most upstream side in the gas stream to remove nitrogen oxides; supplying the gas into a first ammonia decomposing catalyst layer disposed on the downstream side of the first denitrating catalyst layer to control the ammonia content to be suitable for the subsequent denitrating process, the first ammonia decomposing catalyst layer having ability to oxidatively decompose unreacted ammonia into nitrogen and nitrogen oxides; then supplying the gas into a second denitrating catalyst layer disposed on the downstream side of the first ammonia decomposing catalyst layer; thereafter supplying the gas into a second ammonia decomposing catalyst layer disposed on the most downstream side to remove the residual ammonia, the second ammonia decomposing catalyst layer being provided with a catalyst which can oxidatively decompose the residual ammonia into nitrogen and nitrogen oxides or a catalyst which can oxidatively decompose the residual ammonia into nitrogen oxides.

Method of denitrating exhaust gas

There are provided a honeycomb catalyst in which irregularities are formed on a catalyst inside wall in a honeycomb hole, and a manufacturing method for a honeycomb catalyst by using an extrusion molding method, in which extrusion molding is effected by using a mold having a means for providing irregularities to a catalyst inside wall of a honeycomb hole.

Honeycomb catalyst and manufacturing method therefor

The present invention provides a denitration catalyst which is designed to show a drop of the mechanical strength of the carrier to an acceptable extent even when used with an exhaust gas containing sulfur oxides while making the use of excellent water resistance or electrical insulating properties inherent to glass fibers and a process therefor. The denitration catalyst comprises a catalytically active component supported on a structure comprising a glass fiber free of B.sub.2 O.sub.3, an inorganic filler and an inorganic binder.

Catalyst and process for the production thereof

Disclosed are (1) a method for the regeneration of a denitration catalyst wherein, in order to regenerate a denitration catalyst having reduced denitration power, the catalyst is cleaned with a cleaning fluid having a hydrofluoric acid concentration of 0.3 to 3% by weight and maintained at a temperature of 20 to 80.degree. C., and (2) a method for the regeneration of a denitration catalyst which comprises the steps of cleaning a denitration catalyst having reduced denitration power under the conditions described in (1) above, drying the cleaned catalyst, and impregnating the catalyst with a catalytically active component so as to support it on the catalyst.

Method for the regeneration of a denitration catalyst

Disclosed is an ammonia adsorption apparatus for removing ammonia contained in a treated gas discharged from a denitrator for decomposing nitrogen oxides present in exhaust gas using ammonia as a reducing agent, comprising at least two adsorption towers into which ammonia-containing exhaust gas is introduced in a vertical direction for removing the ammonia by adsorption, wherein, during regeneration of each adsorption tower, hot gas used for desorption purposes flows from a top toward a bottom of the adsorption tower and cooling gas flows from the bottom toward the top of the adsorption tower.

Ammonia adsorption apparatus

This invention effectively utilizes a solid type honeycomb-shaped NO.sub.x removal catalyst which has been used in a catalytic ammonia reduction process and hence reduced in NO.sub.x removal power, and thereby provides an inexpensive catalyst having NO.sub.x removal power equal to that of a fresh catalyst. The nitrogen oxide removal catalyst of this invention, which is useful in a process wherein ammonia is added to exhaust gas and nitrogen oxides present in the exhaust gas are catalytically reduced, has a two-layer structure composed of a lower layer comprising a spent solid type nitrogen oxide removal catalyst and an upper layer comprising a fresh TiO.sub.2 -WO.sub.3 -V.sub.2 O.sub.5 ternary or TiO.sub.2 -WO.sub.3 binary catalyst powder which has been applied to the lower layer so as to give a coating thickness of 100 to 250 .mu.m. Moreover, the catalyst power constituting the upper layer is a catalyst powder obtained by pulverizing a spent solid type nitrogen oxide removal catalyst.

Nitrogen oxide removal catalyst

The object of the present invention is to provide a device to make flow uniform in a denitrification system, which can achieve a predetermined flow regulation effect with low pressure loss independently of the gas flow rate. According to the present invention, the device installed on the upstream side of a chemical injection means for the denitrification system is composed of at least one perforated plate 11, and the perforated plate 11 can be turned by a rotating shaft 10 or 10a from the closed position where the gas flow path is closed to the open position where the gas flow path is opened or vice versa.

Denitrification system

An apparatus installed between a fuel economizer and an air preheater for the denitration of exhaust gas from a coal-fired boiler includes at least one vertical flue situated upstream of a reactor containing a denitration catalyst to cause an upward flow of the gas, A hopper is located below the vertical flue for collecting ash separated from the gas, A baffle is preferably provided in the flue to ensure the still more effective separation of ash from a gas.

Denitration apparatus for a caol-fired boiler

A high-performance rectifying device promotes the diffusion of energy, temperature and concentration in a fluid stream with a small pressure loss. The device is a lattice type rectifying device provided within a fluid flow passageway for equalizing the flow velocity distribution of the same fluid. Lattice elements each consist of two triangular plates disposed so as to form two opposed surfaces of a pyramid having its apex on the downstream side of the fluid flow and two other triangular plates forming two opposed surfaces of another pyramid having its apex jointed with the first-mentioned apex and having its bottom surface positioned on the downstream side of the fluid flow. The latter two opposed surfaces have their orientations deviated by 90 degrees from the two opposed surfaces on the upstream side. The lattice elements are arrayed in juxtaposition in directions perpendicular to the fluid flow with the orientation of adjacent lattice elements deviated by 90 degrees from each other and are connected in such a manner that the bottom surfaces of the above-mentioned pyramids may form a lattice. Furthermore the ratio of the length, in a direction parallel to the flow, of the lattice element to the breadth, in the direction perpendicular to the flow, of the lattice element should be kept in a range of 1.5-2.0. The lattice element may also be formed of a rectangular plate twisted by 90 degrees in the direction along the direction of the fluid flow.

Rectifying device

A method for recovering an ammonia adsorbent which comprises streaming an NO.sub.x -containing gas at 300.degree.-600.degree. C. through an ammonia adsorbent layer which adsorbs ammonia and which is saturated with ammonia.

Method for recovering ammonia adsorbent

This invention relates to a catalyst for purifying an exhaust gas, which has a denitrification property in the lean atmosphere and good durability and is hardly deteriorated even in a high temperature rich atmosphere. The feature thereof consists in a catalyst for purifying an exhaust gas, comprising a crystalline silicate having the specified X-ray diffraction pattern and a chemical composition represented by the following chemical formula in the term of mole ratios of oxides under dehydrated state,

Catalyst for purifying an exhaust gas

A method for treating ammonia in an exhaust gas on the downstream side of a dry denitration device using ammonia as a reducing agent comprises the step of alternately carrying out ammonia adsorption and ammonia desorption/decomposition to continuously treat ammonia in the exhaust gas in a plurality of constitutional units parallelly connected on an exhaust gas line, the aforesaid constitutional units being constituted so as to carry out the steps of adsorbing/removing ammonia in an ammonia adsorbent-filling tower disposed at a position, where an exhaust gas temperature is 200.degree. C. or less, on the downstream side of the dry denitration device; heating, up to a temperature of 300.degree. C. or more, the ammonia adsorbent-filling tower on which ammonia is adsorbed in a saturated state, to desorb ammonia; and decomposing ammonia in an ammonia decomposition catalyst-filling tower disposed on a desorption ammonia gas line.

Method for treating ammonia

A method for the denitration of exhaust gas from a gas turbine or an internal combustion engine which comprises (a) reducing a part of the NO.sub.2 constituting NO.sub.x contained in the exhaust gas to NO by means of a reduction catalyst bed for reducing NO.sub.2 to NO, the reduction catalyst bed being installed in flow communication with the exhaust gas outlet of the gas turbine or internal combustion engine, and (b) injecting NH.sub.3 into the exhaust gas within an exhaust heat recovery unit and then decomposing and removing NO.sub.x contained in the exhaust gas and now composed chiefly of NO, by means a denitration catalyst bed installed within the exhaust heat recovery unit to effect the catalytic reduction of NO.sub.x with NH.sub.3.

Method for the denitration of exhaust gas

A method for denitrating an exhaust gas is disclosed which comprises the steps of injecting ammonia from an ammonia injection device into a high-temperature exhaust gas containing nitrogen oxides in a temperature range of 480.degree. C. or more, and then bringing a mixture of ammonia and the high-temperature exhaust gas into contact with a denitration catalyst to reduce the mixture, said method being characterized in that ammonia is injected through the ammonia injection device in which at least an inner surface is subjected to an aluminizing treatment, whereby ammonia is prevented from decomposing; and an apparatus for denitrating an exhaust gas is also disclosed.

Prevention of ammonia decomposition

A new method for denitration by ammonia of exhaust gas containing arsenic compounds which degrades a denitrating catalyst used is disclosed as well as a method and an apparatus, based on the same principle as the above method, for regenerating an already degraded catalyst. These effects are achieved, without taking the catalyst out of the system, by adjusting the humidity and temperature of the atmosphere surrounding the catalyst filled in the denitration reactor with simple and economical means so that arsenic compounds accumulated on the catalyst surface will diffuse into the catalyst reducing their concentration on the surface, which is important for the catalytic action.

Growing community of inventors

Nagasaki, Japan

Atsushi Morii