JP7195094B2 - Exhaust gas purification catalyst structure - Google Patents

Description

TECHNICAL FIELD The present invention relates to an exhaust gas purifying plate-like catalyst element and an exhaust gas purifying catalyst unit. More specifically, the present invention relates to an exhaust gas purifying plate-like catalyst element having low pressure loss and high denitrification efficiency, and an exhaust gas purifying catalyst unit formed by stacking the elements so as to secure a gas flow path.

2. Description of the Related Art In the presence of a denitrification catalyst, nitrogen oxides in gas emitted from furnaces such as boilers in thermal power plants and various factories are decomposed to purify exhaust gas. Various denitrification catalyst structures have been proposed to decompose nitrogen oxides in exhaust gas with high efficiency.

For example, in Patent Document 1, in a flue gas denitrification device used in a facility for generating exhaust gas containing sulfur oxides by combustion, at least one of a plurality of catalyst layers installed in the gas flow direction A catalyst structure obtained by stacking a plurality of catalyst elements having strip-shaped projections and flat plate portions alternately at predetermined intervals so that the ridges of adjacent catalyst elements are perpendicular to each other. disclosed.

Patent Document 2 discloses a catalyst structure formed by laminating a large number of flat catalyst elements each having a flat plate on which spacer portions each having a mountain-like portion and a valley-like portion are formed in the form of filaments at regular intervals in the direction of gas flow, Concave portions are formed at predetermined intervals in the peak-shaped portion and the valley-shaped portion, and a rod-shaped gas stirrer is arranged in the concave portion so as to be positioned at the center of the flow path formed between the spacers. and a catalyst structure for exhaust gas purification.

Patent document 3 discloses a catalyst structure for purifying exhaust gas which is arranged in a frame suitable for an exhaust gas flow path, and the catalyst structure is formed by bending flat catalysts alternately in opposite directions at predetermined intervals. Exhaust gas consisting of alternately layered plate-shaped catalysts having a large number of protrusions or peaks and valleys and gas dispersion bodies made of metal, ceramic or glass nets having a large number of holes penetrating from front to back. A purification catalyst structure is disclosed.

Patent Document 4 discloses a flat plate-like catalyst element composed of a flat portion, which is a main component, and a linear spacer portion composed of ridges and grooves. wherein the flat portion comprises a leg plate erected at a height lower than the height of the spacer portion with respect to the flat portion, and an upper side of the leg plate Disclosed is a catalyst structure for purifying exhaust gas, which has at least one baffle part consisting of a flat part and a top plate installed substantially parallel to the flat part, and the baffle part can disturb the gas flowing in the gas flow path. there is

JP-A-9-239243 JP 2013-107046 A WO00/13775A1 WO2014/076938A1 (Japanese Unexamined Patent Application Publication No. 2014-97438)

An object of the present invention is to provide an exhaust gas purifying plate-like catalyst element having low pressure loss and high denitrification efficiency, and an exhaust gas purifying catalyst unit formed by stacking the elements so as to secure a gas flow path. is.

As a result of studies to solve the above problems, the present invention including the following aspects was completed.

[1] A plate-shaped catalyst in which flat portions and spacer portions composed of ridges are alternately arranged, and a height level lower than the height of the ridges based on the flat portions and not parallel to the ridges has a strip-shaped baffle part stretched over the flat part in the direction,
A plate-shaped catalyst element for purifying exhaust gas , wherein the baffle portion is formed of a strip member having a portion bent so as to receive a ridge on the plate-shaped catalyst.
[2] The exhaust gas purifying device according to [1 ], wherein the baffle portion is made of a stainless steel plate or a catalyst-supported stainless steel plate, or a stainless steel expanded metal or a catalyst-supported stainless steel plate. Plate-shaped catalyst element.

[ 3 ] A catalyst unit for exhaust gas purification, comprising at least two of the plate-shaped catalyst elements for exhaust gas purification according to [1] or [2] , which are stacked so as to secure a gas flow path.

The exhaust gas purifying plate catalyst element and the exhaust gas purifying catalyst unit of the present invention have a low pressure loss, are resistant to dust accumulation, and can efficiently disturb the gas flow. high rate.
The exhaust gas purifying plate catalyst element and the exhaust gas purifying catalyst unit of the present invention have higher denitrification performance than conventional products with the same amount of catalyst, so that the amount of catalyst used can be greatly reduced. In addition, since it is possible to arbitrarily change the installation conditions of the baffle part according to the exhaust gas treatment conditions of the actual machine, it is possible to deal with a wide range of exhaust gases. The exhaust gas purifying plate-shaped catalyst element and the exhaust gas purifying catalyst unit of the present invention can be preferably used particularly for treating gas containing a relatively large amount of dust discharged from a coal-fired boiler.

1 is a perspective view showing an example of a plate-like catalyst element for purifying exhaust gas of the present invention; FIG. 2 is a perspective view showing a baffle portion 4 that constitutes the plate-like catalyst element for purifying exhaust gas shown in FIG. 1. FIG. 2 is a perspective view showing a plate-like catalyst 1 that constitutes the plate-like catalyst element for purifying exhaust gas shown in FIG. 1. FIG. FIG. 2 is a perspective view for explaining the positional relationship of superimposition of the exhaust gas purifying plate-like catalyst elements shown in FIG. 1 ; FIG. 2 is a cross-sectional view showing a state in which the plate-like catalyst elements for purifying exhaust gas shown in FIG. 1 are superimposed; 1 is a perspective view showing an example of an exhaust gas purifying catalyst unit of the present invention; FIG. FIG. 3 is a conceptual diagram showing a state of gas flow between superimposed plate-like catalyst elements for purifying exhaust gas.

An embodiment of the present invention will be specifically described based on the drawings. In addition, the scope of the present invention is not limited by the following embodiments.

[Plate catalyst element for purification of exhaust gas]
The plate-like catalyst element for purifying exhaust gas of the present invention has a plate-like catalyst 1 and a baffle portion 4 . The plate-like catalyst 1 is formed by alternately arranging spacer portions 2 and flat portions 3 as shown in FIG.

A catalyst is supported on the flat portion 3 and the spacer portion 2 . The catalyst is not particularly limited as long as it is used for the denitration reaction. For example, catalysts containing catalyst components containing elements such as Ti, Mo, W, and V; catalysts containing zeolite or aluminosilicate on which noble metal elements such as Cu and base metal elements such as Fe may be supported; A mixed catalyst of a catalyst containing a catalyst component containing an element such as Ti and a catalyst containing the zeolite or aluminosilicate can be mentioned. Examples of substrates for supporting the catalyst include planar substrates such as flat metal plates, woven wire meshes, punched metals, expanded metals (also known as lath metals and metal laths), wire meshes, woven glass fabrics, and non-woven glass fabrics. Stainless steel is preferably used for the base material. The planar base material can be easily shaped into flat portions and spacer portions by die bending (press bending) or the like. Although the thickness of the planar substrate on which the catalyst is supported is not particularly limited, it is preferably 0.1 mm to 0.3 mm.

Supporting of the catalyst on the base material can be carried out, for example, by placing a paste-like composition containing a catalyst component (hereinafter referred to as catalyst paste) on one surface of a flat plate-like lath metal base material, sandwiching it under pressure with rolls or the like, and then drying. a catalyst paste is applied to one side of a flat substrate made of a woven glass fiber cloth, another flat substrate made of a woven glass fiber cloth is placed on the coated surface, and the The catalyst paste is layered so as to be sandwiched between two substrates, and if necessary, the catalyst paste is applied to both sides of the layered substrates, and then strongly crushed with a roll or the like to allow the catalyst paste to permeate into the substrates. It can be carried out by a method including drying, followed by drying and, if necessary, baking. In this way, catalyst layers are laminated on both sides of the flat substrate. It is preferable that the spaces between the meshes of the substrate are also filled with the catalyst paste. The thickness of the catalyst supported on the substrate is not particularly limited, but is preferably 0.2 to 2 mm.

The spacer portion serves as a spacer for securing a space through which gas can pass between the stacked plate-shaped catalyst elements for purifying exhaust gas, that is, a gas flow path. The spacer portion is composed of ridges on which a catalyst is supported. The cross-sectional shape of the ridges is not particularly limited. For example, a spacer portion having a chevron-shaped cross section composed of upward ridges, and a spacer portion 2 having a wavy cross-section composed of upward ridges and downward ridges can be used. When plate-like catalyst elements having a spacer part 2 with a corrugated cross-section consisting of upward ridges and downward ridges are superimposed, the upward ridges of the underlying plate-like catalyst element for purifying exhaust gas and the upper ridges of the exhaust gas Since the flat portion 3 of the plate-shaped catalyst element for exhaust gas purification is sandwiched between the downward ridges of the plate-shaped catalyst element for purification, the rigidity in the overlapping direction can be increased, and furthermore, the frame body By fixing the horizontal direction by , it is possible to maintain the structure in which the exhaust gas purifying plate-like catalyst elements are stably superimposed in the exhaust gas purifying catalyst unit. The spacer portion 2 can be formed by bending a planar substrate. The distance between the ridges is preferably 20-200 mm. The width of one ridge is preferably 10 to 20 mm. The total width of the downward ridges and upward ridges in the spacer portion 2 shown in FIG. 1 is preferably 20 to 40 mm. The height of the ridge with respect to the flat portion is preferably 4 to 10 mm.

The baffle portion 4 is made of a belt member. The strip is stretched over the flat portion at a height level lower than the height of the ridge relative to the flat portion and in a non-parallel orientation, preferably at right angles to the ridge. It is preferable that the height level of the baffle portion is 2/5 to 3/5 of the height of the ridge with respect to the flat portion. The thickness of the baffle portion is preferably 0.2-2 mm.

By arranging the surface of the baffle portion 4 substantially parallel to the flat portion, the area with which the gas flow collides can be reduced to the thickness of the belt member. By arranging the baffle portion 4 in the central portion of the gas flow path formed by stacking the plate-like catalysts, a flow as indicated by the arrows in FIG. 7 is generated. Since the central portion of the gas flow path is away from the plate-like catalyst, the denitrification reaction is more difficult to proceed than in the vicinity of the plate-like catalyst, and the NOx concentration is high. A baffle portion arranged in the central portion of the gas flow path disturbs the flow of gas with a high NOx concentration, making it easier for NOx to come into contact with the plate-like catalyst. The turbulent gas flow is rectified only by flowing through a thin gas channel for ten and several centimeters to several tens of centimeters. By further arranging the baffle part 4 at a position before the turbulent gas flow is rectified, the turbulence of the gas flow can be maintained and the contact frequency of NOx with the plate-like catalyst can be increased.

The baffle portion may be made of a belt member having a portion bent so as to receive the ridges present on the plate-like catalyst element for purifying exhaust gas. The shape of the bent portion is not particularly limited as long as it can accommodate the ridges. For example, in the baffle portion 4 shown in FIG. 2, the bent portion 5 capable of receiving the upward ridges is bent in the same shape as the top portion of the upward ridges, and is bent to receive the downward ridges. The portion 6 is bent into a rectangle with a width larger than the width of the ridge. The width of the folded portion 6 in FIG. 2 is preferably 10-20 mm. By bending into a rectangle with such a width, it is possible to deal with deviations in the positions of the ridges due to manufacturing variations. The length of the flat portion 7 of the baffle portion 4 can be appropriately selected according to the width of the gas flow path formed when the exhaust gas purifying plate catalyst elements are superimposed.

The belt member can be composed of a flat metal plate, a woven wire mesh, a punching metal, an expanded metal (another name: lath metal, metal lath), a wire mesh, a woven glass cloth, a non-woven glass cloth, or the like. A catalyst may be carried on the belt member. The supported catalyst may be the same as listed for the catalyst supported on the plateaus or spacers. The baffle portion is preferably made of a stainless steel plate or a catalyst-supported material, or stainless steel expanded metal or a catalyst-supported material. The baffle part preferably has a band width D of 10 to 30 mm.

The first baffle part is preferably 100 to 300 mm, more preferably 150 to 200 mm away from the front edge of the plate-shaped catalyst element for purifying exhaust gas, and the second baffle part is installed behind the first baffle part. , preferably 30 to 200 mm away. Furthermore, the third and subsequent baffle portions may be provided preferably at intervals of 30 to 200 mm.
The baffle portion of one exhaust gas purifying plate-shaped catalyst element is located at the same position as the baffle portion of the adjacent exhaust gas purifying plate-shaped catalyst element when viewed from the normal direction of the flat portion when superimposed. You may install it, and you may install it in a different position.

The forming method of the spacer portion and the baffle portion of the exhaust gas purifying plate-shaped catalyst element is not particularly limited, and can be formed, for example, as follows. A plate-like catalyst 1 having spacer portions with a corrugated cross-section can be formed by press-bending a flat planar substrate on which a catalyst paste is supported. On the other hand, it is possible to form a strip member having a bent portion so as to receive the ridges of the spacer portion by press-bending a flat strip-shaped base material on which the catalyst paste is carried. By fitting the belt member 4 to the plate-like catalyst 1 as shown in FIG. 1, the plate-like catalyst element for exhaust gas purification of the present invention can be obtained. The exhaust gas purifying plate-like catalyst element obtained by such a method can be appropriately cut into a size that can be accommodated in the frame 10 .

[Catalyst unit for purifying exhaust gas]
The exhaust gas purifying catalyst unit of the present invention is formed by stacking at least two of the exhaust gas purifying plate catalyst elements of the present invention so as to secure a gas flow path. In order to prevent the overlapped exhaust gas purifying plate-like catalyst elements from collapsing, they can be accommodated in the frame 10 . The stacking method of the exhaust gas purifying plate-like catalyst elements is not particularly limited as long as it is possible to secure a space through which gas can pass between the exhaust gas purifying plate-like catalyst elements. The spacer portions having corrugated cross-sections may be stacked parallel to each other, may be stacked perpendicular to each other, or may be stacked at an angle intermediate between parallel and right angles. In the present invention, as shown in FIG. 4, it is preferable to stack the spacer portions so that they are parallel to each other. Moreover, it is possible to stack the spacer portions so that they do not fit together, that is, to stack the spacer portions of one exhaust gas-purifying plate-like catalyst element so that they are in contact with the flat portion of the adjacent exhaust gas-purifying plate-like catalyst element. It is preferable from the viewpoint of obtaining a high aperture ratio and high denitrification efficiency. The number of sheets to be stacked can be appropriately set according to the size of the frame and the size of the plate-like catalyst element for purification of exhaust gas. Usually, about 20 to 40 plate catalyst elements for purifying exhaust gas are stacked. The frame body is not particularly limited as long as it has a structure capable of guiding gas between the stacked plate-like catalyst elements for purifying exhaust gas. For example, the frame 10 may have a rectangular tubular shape made up of four metal flat plates.

EXAMPLES Next, the present invention will be described in more detail with reference to examples. However, the present invention is by no means limited by these examples.

Example 1
10 kg of titanium oxide, 2 kg of ammonium molybdate tetrahydrate, 1 kg of ammonium metavanadate, and 1 kg of oxalic acid were mixed and kneaded with a kneader for 1 hour while adding water to form a paste. To this, 2 kg of silica-alumina inorganic fibers were added and kneaded for another 30 minutes to obtain a catalyst paste with a water content of about 30%.
Using a pair of rolling rollers, this catalyst paste was pressed against the surface and between the laths of a long planar substrate made of SUS430 stainless steel expanded metal with a width of 500 mm to form a long strip with a thickness of 0.7 mm. A flat plate catalyst was obtained. This long flat plate catalyst was subjected to die bending using a pressing machine to form a spacer portion having a corrugated cross section (the height of the ridges based on the flat portion=7 mm). After that, it was cut to a length of 600 mm to obtain a plate-like catalyst 1 having flat portions 3 and spacer portions 2 .
On the other hand, a band member made of SUS430 stainless steel plate having a thickness of 1 mm, a length of 500 mm, and a width (D) of 10 mm was subjected to die bending using a pressing machine to form a bent portion 6 . Next, the two belt members were oriented substantially perpendicularly to the ridges so that the bent portion 6 was positioned approximately in the center of the flat portion of the plate-shaped catalyst 1 and at positions 200 mm and 400 mm apart from the front edge of the plate-shaped catalyst 1 . Then, using a pressing machine, the bent portion 5 was formed by forming the bent portion 5, and at the same time, the upward protruding strip of the plate-like catalyst 1 was crimped to obtain a plate-like catalyst element a having the baffle portion 4. The baffle part 4 was stretched over the flat part at a height level of 3.5 mm on the basis of the flat part.
The plate-like catalyst elements a were superimposed and held by a frame 10 as shown in FIG. This was air-dried for 24 hours and then calcined in the air at 500° C. for 2 hours to obtain a catalyst unit A.

Example 2
A plate-like catalyst element b and a catalyst unit B were obtained in the same manner as in Example 1, except that the thickness of the strip member made of SUS430 stainless steel plate was changed to 0.5 mm.

Example 3
A plate-like catalyst element c and a catalyst unit C were obtained in the same manner as in Example 1, except that the thickness of the strip member made of SUS430 stainless steel plate was changed to 2 mm.

Example 4
A plate-like catalyst element d and a catalyst unit D were obtained in the same manner as in Example 1, except that the width (D) of the strip member made of SUS430 stainless steel plate was changed to 20 mm.

Example 5
A plate-like catalyst element e and a catalyst unit E were obtained in the same manner as in Example 1, except that the strip member made of SUS430 stainless steel plate was changed to a strip member made of SUS430 stainless steel expanded metal.

Example 6
The catalyst paste obtained in Example 1 was pressed against a belt member made of SUS430 stainless steel expanded metal with a roller to obtain a belt member (thickness: 0.7 mm) supporting the catalyst.
A plate-like catalyst element f and a catalyst unit F were obtained in the same manner as in Example 1, except that the belt member made of SUS430 stainless steel plate was changed to a catalyst-supported belt member.

Comparative example 1
A catalyst unit G was obtained in the same manner as in Example 1, except that the plate-like catalyst 1 obtained in Example 1 was used instead of the plate-like catalyst element.

For the catalyst units A to G, the denitrification reaction was performed under the conditions shown in Table 1, and the reaction rate ratio and pressure loss were measured. Table 2 shows the results.
As can be seen from Table 2, catalyst units A to F obtained by laminating plate-shaped catalyst elements a to f of the present invention have higher denitration performance than catalyst unit G. From the results of catalyst units A to D, it can be seen that the greater the thickness and width (D) of the baffle portion, the higher the denitration performance. It can be seen that the greater the thickness or width (D) of the baffle portion, the higher the pressure loss, but the increase is small. The denitrification efficiency is further enhanced by providing a baffle section on which a catalyst is supported. The catalyst unit of the present invention has a low pressure loss, and even if the exhaust gas contains dust, it is difficult for dust to accumulate. It is suitable for purifying exhaust gas containing a large amount of dust discharged from coal-fired boilers, etc., and can greatly reduce the environmental load compared to conventional catalyst units.

1: Plate-shaped catalyst 2: Spacer portion 3: Flat portion 4: Baffle portion 5: Bent portion for receiving upward ridges of baffle portion 6: Bent portion for receiving downward ridges of baffle portion 7: Flat portion of baffle portion 8: exhaust gas 9: catalyst unit 10: frame

Claims (3)

A plate-like catalyst in which flat portions and spacer portions composed of ridges are alternately arranged; Having a strip-shaped baffle part stretched over the flat part ,
A plate-shaped catalyst element for purifying exhaust gas , wherein the baffle portion is formed of a strip member having a portion bent so as to receive a ridge on the plate-shaped catalyst. 2. The plate-like catalyst element for purifying exhaust gas according to claim 1 , wherein the baffle portion is made of a stainless steel plate or a catalyst-supported stainless steel plate, or a stainless steel expanded metal or a catalyst-supported stainless steel plate. . 3. A catalytic unit for purifying exhaust gas, comprising at least two plate-like catalyst elements for purifying exhaust gas according to claim 1 or 2 , which are stacked so as to secure a gas flow path.

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