De-NOx catalyst structure

Abstract

The denitration catalyst structure includes: a rectangular frame having a gas inlet and a gas outlet; a plurality of plate-shaped catalyst elements having edges present on the gas inlet side, edges present on the gas outlet side, and edges present on both side portions, respectively, and containing a catalyst component; and a plate-shaped gas flow barrier having edges present on the gas inlet side, edges present on the gas outlet side, and edges present on both side portions, respectively, the plate-shaped catalyst elements being housed in the frame in a manner in which the edges present on both side portions are aligned, respectively, there being gaps between the stacked plate-shaped catalyst elements and between the inner surface of the frame and the edges present on the side portions of each plate-shaped catalyst element through which gas can pass from the gas inlet to the gas outlet, the plate-shaped gas flow barrier being housed between the inner surface of the frame and the edges present on the side portions of each plate-shaped catalyst element in a manner in which the plate surface of the plate-shaped gas flow barrier faces the inner surface of the frame, and having a mechanism that can impede the flow of gas passing between the inner surface of the frame and the edges present on the side portions of each plate-shaped element without stopping the flow of the gas.

Description

Technical Field

[0001] This invention relates to a denitrification catalyst structure. More specifically, this invention relates to a denitrification catalyst structure capable of improving contact efficiency with catalyst components and thereby achieving a high denitrification rate by impeding the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements present on the sides without stopping the flow of gas. Background Technology

[0002] Nitrogen oxides in gases emitted from thermal power plants, boilers in various factories, and waste incinerators are decomposed in the presence of denitrification catalysts to purify waste gases. Various denitrification catalyst structures have been proposed for efficient decomposition of nitrogen oxides in waste gases.

[0003] For example, Patent Document 1 discloses a catalyst holder that is sandwiched between a carrier carrying a catalyst for exhaust gas purification and an exhaust pipe surrounding the carrier to hold the carrier. The catalyst holder is characterized by comprising: an inorganic fiber pad for heat dissipation, which is disposed at a portion in contact with the middle part of the carrier along the flow direction of the exhaust gas, and is mixed with a material with a higher thermal conductivity than inorganic fibers; and an inorganic fiber pad for preventing exhaust gas leakage, which is disposed on the upstream or downstream side of the heat dissipation pad, and is not mixed with the material, the material being exposed on the outer peripheral surface of the heat dissipation pad, and the pressure on the contact surface between the heat dissipation pad and the exhaust pipe increases as the temperature rises.

[0004] Patent document 2 discloses a catalyst support module comprising: a tank formed of a square tube having an inlet and an outlet; a chamber forming body formed by alternately stacking corrugated plates and flat plates coated with catalyst to form a plurality of hollow chambers and inserted into the tank; and a fixing unit provided at the inlet and outlet of the tank to prevent the chamber forming body from detaching from the tank.

[0005] Patent document 3 discloses a denitrification reaction device, which has a plate-shaped catalyst arranged parallel to the flow of exhaust gas and in the direction of gravity, a catalyst unit that houses multiple plates of the catalyst, and multiple catalyst units, wherein the device is configured such that an inwardly inclined slope at the horizontal part of the exhaust gas inlet and outlet of the catalyst unit abuts against the end of the plate-shaped catalyst for support.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2014-105683

[0009] Patent Document 2: Japanese Patent Publication No. 2019-511953

[0010] Patent Document 3: Japanese Patent Application Publication No. 8-187434 Summary of the Invention

[0011] The problem that the invention aims to solve

[0012] To impede the flow of gas between the inner surface of the frame and the edges of the plate-shaped catalyst elements, it was considered to completely fill this area with certain components. However, this would significantly increase ventilation losses due to the reduced cross-sectional area of ​​the passage. Asbestos and other fibrous blocks have low elasticity; therefore, when the gaps are filled with fibrous blocks, the plate-shaped catalyst elements tend to shift to one side within the frame after assembling the denitrification catalyst structure. If they shift to one side, the gap on the other side widens.

[0013] The objective of this invention is to provide a denitrification catalyst structure that can impede the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements present on the sides, thereby improving the contact efficiency with the catalyst components and achieving a high denitrification rate.

[0014] Methods for solving problems

[0015] Research was conducted to address the aforementioned issues, resulting in the completion of this invention, which includes the following solutions.

[0016] [1] A denitrification catalyst structure, wherein,

[0017] The denitrification catalyst structure includes:

[0018] A rectangular frame with a gas inlet and a gas outlet;

[0019] Multiple plate-shaped catalyst elements, each having an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides, and containing catalyst components; and

[0020] A plate-shaped draft stopper has an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides.

[0021] Multiple plate-shaped catalyst elements are stacked in a frame with their edges aligned on both sides. Gaps exist between the stacked plate-shaped catalyst elements and between the inner surface of the frame and the edges of each plate-shaped catalyst element on its sides, allowing gas to pass through from the gas inlet to the gas outlet.

[0022] The plate-shaped airflow obstructor is housed between the inner surface of the frame and the edges of the plate-shaped catalyst elements located on the sides, with the plate surface of the plate-shaped airflow obstructor along the inner surface of the frame. It has a mechanism that can obstruct the flow of gas without stopping the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements located on the sides.

[0023] [2] According to the denitrification catalyst structure described in [1], the plate-shaped airflow blocking element contains catalyst components.

[0024] [3] According to the denitrification catalyst structure described in [1] or [2], the mechanism that can impede the flow of gas without stopping the flow of gas is a ridge provided on the plate surface of the plate-shaped airflow blocking member and arranged non-parallel to the gas flow direction.

[0025] Invention Effects

[0026] The denitrification catalyst structure of the present invention can impede the flow of gas without stopping the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements present on the sides, thereby improving the contact efficiency with the catalyst components and achieving a high denitrification rate. The denitrification catalyst structure of the present invention is suitable for removing nitrogen oxides generated during the combustion of coal fuel, gaseous fuel, ammonia fuel, etc.

[0027] The denitrification catalyst structure of the present invention includes a plate-shaped airflow obstruction mechanism disposed on the plate surface that obstructs the flow of gas without stopping the gas flow. This mechanism obstructs the flow of gas passing between the inner surface of the frame and the edges of each plate-shaped catalyst element present on the sides, thus reducing the amount of gas passing through without contacting the plate-shaped catalyst elements. The plate-shaped airflow obstruction does not completely fill the gaps, therefore the reduction in the frontal area for gas inflow is smaller, and the increase in ventilation loss is lower. When the plate-shaped airflow obstruction contains catalyst components, the denitrification reaction can occur on its surface. When the plate-shaped airflow obstruction has sufficient elasticity, it can prevent the plate-shaped catalyst elements from shifting to one side within the frame. Attached Figure Description

[0028] Figure 1 This is a perspective view showing an example of the denitrification catalyst structure of the present invention.

[0029] Figure 2 This is a perspective view showing an example of a frame.

[0030] Figure 3 This is a perspective view showing an example of a plate-shaped catalyst element.

[0031] Figure 4This is a perspective view showing an example of a plate-shaped catalyst element.

[0032] Figure 5 This is a perspective view showing an example of a plate-shaped airflow obstruction.

[0033] Figure 6 This is a perspective view showing an example of a plate-shaped airflow obstruction.

[0034] Figure 7 This is a perspective view showing an example of the assembly of plate-shaped catalyst elements A and B and plate-shaped airflow obstruction elements C and D within the frame.

[0035] Figure 8 yes Figure 4 The top view, front view, and side view of the plate-shaped catalyst element are shown.

[0036] Figure 9 These are top views, front views, and side views showing an example of a plate-shaped catalyst element.

[0037] Figure 10 These are top views, front views, and side views showing an example of a plate-shaped catalyst element.

[0038] Figure 11 This is a top perspective view showing an example of the assembly of the frame 5, plate-shaped catalyst elements A1 and B1, and plate-shaped airflow blocking elements C and D. Detailed Implementation

[0039] The embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the scope of the present invention is not limited to the following embodiments.

[0040] One embodiment of the denitrification catalyst structure of the present invention includes a frame 5, multiple plate-shaped catalyst elements A and B, and plate-shaped airflow blocking elements C and D. It should be noted that, in Figure 1 In the middle, the plate-shaped airflow blocking component D is hidden behind the right side of the frame 5.

[0041] The frame is rectangular in shape and has a gas inlet and a gas outlet. The upper surface, lower surface, right side, and left side of the frame are preferably structures that prevent the incoming gas from leaking out (e.g., in…). Figure 2 (The middle part is a flat plate). From the viewpoints of heat resistance and mechanical strength, the frame is preferably made of metal. The edges of the inlet and / or outlet of the frame are preferably edge-treated. Examples of edge treatments include folding back (bending), rolling, L-shaped bending (flange forming, etc.). Edge treatment can improve the strength of the frame. Figure 2The frame 5 shown has hemmings 5b on the edges of its upper and lower surfaces, and flanges 5a on its right and left edges. The flanges 5a are curved inwards. By designing the size of the flanges to correspond to the size of the gap formed between the inner surface (right or left side) of the frame and the edges of the plate-shaped catalyst elements present on the sides, it is expected to partially impede the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements present on the sides.

[0042] The plate-shaped catalyst element is plate-shaped, having an edge on the gas inlet side, an edge on the gas outlet side, and edges on both sides. The plate-shaped catalyst element is preferably square or rectangular in shape.

[0043] The plate-shaped catalyst element contains a catalyst component. The method of containing the catalyst component is not particularly limited. For example, the plate-shaped catalyst element preferably includes a plate-shaped substrate and a catalyst component supported on its surface. Examples of plate-shaped substrates include slabs, inorganic fiber fabrics, and inorganic fiber nonwoven fabrics. Examples of slabs include expanded alloys, perforated metals, and metal mesh. The catalyst component can be supported by impregnation, coating, pressing, or other processing methods. Preferably, the catalyst component is supported on the plate-shaped substrate by blocking the mesh of the plate-shaped substrate, such as expanded alloys.

[0044] There are no particular restrictions on the catalyst composition as long as it has the effect of denitrification catalysis. For example, catalysts containing oxides of titanium, molybdenum and / or tungsten, and oxides of vanadium (titanium-based catalysts) can be cited; catalysts mainly containing aluminosilicates such as zeolites supported on metals such as Cu and Fe (zeolite-based catalysts); and catalysts formed by mixing titanium-based catalysts and zeolite-based catalysts. Among these, titanium-based catalysts are preferred.

[0045] Examples of titanium-based catalysts include Ti-VW catalysts, Ti-V-Mo catalysts, and Ti-VW-Mo catalysts.

[0046] The ratio of V to Ti, in terms of the weight percentage of V₂O₅ / TiO₂, is preferably 9% by weight or less, more preferably 3% by weight or less. The ratio of Mo and / or W to Ti, when both molybdenum oxide and tungsten oxide are used together, is preferably 20% by weight or less, more preferably 5% by weight or less, in terms of the weight percentage of (MoO₃ + WO₃) / TiO₂.

[0047] In the preparation of titanium-based catalysts, titanium oxide powder or titanium oxide precursors can be used as raw materials for titanium oxides. Examples of titanium oxide precursors include titanium oxide slurry, titanium oxide sol, titanium sulfate, titanium tetrachloride, titanates, and titanium alkoxides. In this invention, raw materials that form anatase-type titanium oxide are preferably used as raw materials for titanium oxides.

[0048] Vanadium compounds such as vanadium pentoxide, ammonium metavanadate, and vanadium oxysulfate can be used as raw materials for vanadium oxides.

[0049] Ammonium paratungstate, ammonium metatungstate, tungsten trioxide, tungsten chloride, etc. can be used as raw materials for tungsten oxides.

[0050] Ammonium molybdate, molybdenum trioxide, etc. can be used as raw materials for molybdenum oxides.

[0051] The catalyst components used in this invention may contain, as co-catalysts or additives, oxides of P, oxides of S, oxides of Al (e.g., alumina), oxides of Si (e.g., glass fiber), oxides of Zr (e.g., zirconium oxide), gypsum (e.g., gypsum dihydrate), zeolite, etc. These can be used in the catalyst preparation process in the form of powder, sol, slurry, fiber, etc.

[0052] In the denitrification catalyst structure of the present invention, a plurality of plate-shaped catalyst elements are housed in the frame 5. Furthermore, in the denitrification catalyst structure of the present invention, the plurality of plate-shaped catalyst elements are stacked in such a manner that the edges present on both sides are aligned.

[0053] The plate-shaped catalyst elements are preferably stacked in a way that ensures sufficient gaps for the passage of incoming gas. For example, this can be achieved by alternately stacking flat plate-shaped catalyst elements and corrugated plate-shaped catalyst elements, or by alternately stacking them. Figure 3 and Figure 4 The plate-shaped catalyst element shown is designed to ensure the gap through which the incoming gas can pass.

[0054] Figure 3 or Figure 4 The plate-shaped catalyst elements A and B shown alternately have multiple flat portions 1 and uneven portions 2. The flat portions 1 are flat plates. The uneven portions 2 are plates with parallel ridges 3 and 3' on the upper and lower surfaces, respectively. The ridges 3 and 3' can be bent, but are preferably shaped as follows: Figure 3 As shown, they are essentially straight. The height h and width w of the protrusions 3 and 3' can be set appropriately (refer to...). Figure 8The width of the protrusion / concave portion 2 is 2w. Preferably, the front and back sides of each protrusion 3, 3' are formed with concave portions 4', 4' in shapes corresponding to the shape of the protrusion. Preferably, the cross-section of each protrusion / concave portion is Z-shaped or S-shaped due to the protrusion present on the upper surface and the protrusion present on the lower surface. The plate thickness t of the flat portion and the protrusion / concave portion of the plate-shaped catalyst element is not particularly limited, but is preferably 0.3 to 1.0 mm.

[0055] Preferably, the length direction of each ridge in the plate-shaped catalyst element is arranged at a right angle or at an angle relative to the extension direction of the edge of the plate-shaped catalyst element present on the gas inflow side. Figure 8 , 9 (and 10). The angle θ between the length direction of the ridge and the extension direction of the edge present on the gas inflow side is 50 degrees or more and 90 degrees or less, preferably 55 degrees or more and 90 degrees or less, more preferably 65 degrees or more and 90 degrees or less, and even more preferably 70 degrees or more and 90 degrees or less. There is a tendency that the smaller the angle θ, the greater the effect of increasing the denitrification rate. There is a tendency that the larger the angle θ, the greater the effect of reducing pressure loss. Parallel ridges located on the same surface are preferably arranged at equal intervals. The distance p between the edges of parallel ridges located on the same surface can be appropriately set. In plate-shaped catalyst elements, there is a tendency that the smaller the distance p, the higher the denitrification rate.

[0056] In the denitrification catalyst structure of the present invention, such as Figure 11 As shown, the ridge line of the ridge line 3 on the upper surface of a plate-shaped catalyst element can be configured to intersect and contact the ridge line of the ridge line 3' on the lower surface of an adjacent plate-shaped catalyst element, as shown. Figure 7 As shown, the ridges of the protrusions 3 on the upper surface or the protrusions 3' on the lower surface of a plate-shaped catalyst element can also be configured to contact the flat portion of an adjacent plate-shaped catalyst element. In the case of intersection, the angle θ1 formed by the two ridges at the intersection point is preferably 10 degrees or more and 80 degrees or less, more preferably 20 degrees or more and 70 degrees or less, and even more preferably 20 degrees or more and 65 degrees or less (see reference). Figure 11 ).

[0057] Thus, when plate-shaped catalyst elements are configured and stacked and housed in a frame, gaps are ensured between the stacked plate-shaped catalyst elements and between the inner surface of the frame and the edges of the frame where each plate-shaped catalyst element exists, allowing gas to pass from the gas inlet to the gas outlet. A denitrification reaction occurs on the plate-shaped catalyst elements by contacting the gas containing nitrogen oxides with the catalyst components contained therein. In this denitrification reaction, a denitrification agent such as ammonia can also be added to the gas containing nitrogen oxides.

[0058] A plate-shaped airflow obstructor is a plate-shaped component having an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides. The plate-shaped airflow obstructor is preferably square or rectangular in shape overall.

[0059] The plate-shaped airflow baffle is housed along the inner surface (right or left side) of the frame, between the inner surface (right or left side) of the frame and the edges of the plate-shaped catalyst elements located on the sides. The plate-shaped airflow baffle can be housed within the frame, provided it has a height (distance between the edges on both sides) corresponding to the height of the frame (distance between the upper and lower surfaces), without particular limitation. The plate-shaped airflow baffle can have a width corresponding to the length from the inlet to the outlet of the frame (distance between the edge on the gas inlet side and the edge on the gas outlet side), or it can have a width shorter than the length from the inlet to the outlet of the frame.

[0060] The plate-shaped airflow obstructor has a mechanism that impedes the flow of gas without stopping the flow of gas passing between the inner surface of the frame and the edges of each plate-shaped catalyst element located on the sides. Examples of mechanisms that impede the flow of gas without stopping the gas flow, provided on the plate surface of the plate-shaped airflow obstructor, include protrusions (dot-like protrusions) or concave points (dot-like depressions) provided on the plate surface, baffles provided on the plate surface, convex or concave strips with a rectangular or sinusoidal cross-section formed by bending the plate, and other structures formed by bending the plate. Figure 5 The cross-section shown has S-shaped or Z-shaped convex or concave strips, etc.

[0061] Figure 5 The plate-shaped airflow blocking members C and D shown in Figure 6 alternately have multiple flat portions 1' and concave-convex portions 2'. The flat portions 1' are flat and plate-shaped. The concave-convex portions 2' are plate-shaped with parallel ridges 6, 6' on the right and left sides, respectively. The ridges 6, 6' can be bent, but are preferably substantially straight as shown. The height h and width w of the ridges 6, 6' can be appropriately set. The front and back sides of each ridge 6, 6' preferably form concave ridges 7', 7 with shapes corresponding to the shape of the ridge. The cross-section of each concave-convex portion preferably forms a Z-shape or S-shape with the ridge present on the right or left side and the ridge present on the left or right side. The plate-shaped airflow blocking member tends to have a greater obstruction of gas flow as the ratio h / w of height h to width w increases. The plate thickness t at the flat portions and concave-convex portions of the plate-shaped airflow blocking member is not particularly limited, but is preferably 0.3 to 1.0 mm.

[0062] By designing the maximum height difference 2h of the uneven portion 2' of the plate-shaped airflow obstructor to correspond to the width of the gap formed between the inner surface (right side or left side) of the frame and the edge of each plate-shaped catalyst element present on the side, it is expected to improve the effect of partially obstructing the flow of gas passing between the inner surface of the frame and the edge of each plate-shaped catalyst element present on the side. With sufficient elasticity in the uneven portion 2' of the plate-shaped airflow obstructor, the movement of the plate-shaped catalyst elements within the frame can be restricted, preventing problems such as the plate-shaped catalyst elements deviating to one side.

[0063] The protrusions in the plate-shaped airflow baffle are preferably configured to be parallel or inclined relative to the extending direction of the edge of the plate-shaped airflow baffle on the gas inflow side. The angle between the length direction of the protrusion and the extending direction of the edge on the gas inflow side is 0 degrees or more and 40 degrees or less, preferably 0 degrees or more and 35 degrees or less, more preferably 0 degrees or more and 25 degrees or less, and even more preferably 0 degrees or more and 20 degrees or less. In this way, when the plate-shaped airflow baffle is housed in the frame, it can obstruct a portion of the gas flow passing between the inner surface of the frame and the edge of each plate-shaped catalyst element on the side, and can reduce the proportion of gas flowing out of the catalyst structure without ever contacting the plate-shaped catalyst element.

[0064] The plate-shaped airflow barrier may also contain a catalyst component. The method of containing the catalyst component is not particularly limited. It can be contained using the same method as the plate-shaped catalyst element. For example, the plate-shaped airflow barrier preferably includes a plate-shaped substrate and a catalyst component supported on its surface. Examples of plate-shaped substrates include slatted boards, inorganic fiber fabrics, and non-woven fabrics. Examples of slatted boards include expanded alloys, perforated metals, and metal mesh. The catalyst component can be supported by impregnation, coating, pressing, or other processing methods. The catalyst component is preferably supported on the plate-shaped substrate in a way that blocks the mesh of the plate-shaped substrate, such as expanded alloys. Examples of catalyst components contained in the plate-shaped airflow barrier are the same as those included in plate-shaped catalyst elements. By containing a catalyst component in the plate-shaped airflow barrier, nitrogen oxide-containing gases passing between the inner surface (right side or left side) of the frame and the edges of each plate-shaped catalyst element present on the sides come into contact with the catalyst component contained in the plate-shaped airflow barrier, and a denitrification reaction can also occur on the plate-shaped airflow barrier.

[0065] In the figure, a plate-shaped airflow obstruction is provided between the inner surface of the frame and the edge of each plate-shaped catalyst element on the side. However, multiple plate-shaped airflow obstructions can also be provided as in the case of the plate-shaped catalyst element, for example, 2 to 3 plates can be overlapped.

[0066] The denitrification catalyst structure of the present invention can be modified in terms of structure, shape, configuration, etc. without violating the spirit of the present invention. In addition, components, mechanisms, etc. used in the prior art can be added. It is understood that the scheme with such modifications or additions falls within the technical scope of the present invention.

[0067] Explanation of reference numerals in the attached figures:

[0068] 9: Catalyst Structure

[0069] 1, 1': Flat part

[0070] 2, 2': Concave and convex parts

[0071] 3: Raised strips on the upper surface

[0072] 4: The recessed strip on the lower surface

[0073] 3': The raised strip on the lower surface

[0074] 4': Recessed strip on the upper surface

[0075] 5: Frame

[0076] 5a: Flange

[0077] 5b: Folded edge

[0078] 6: The raised strip on the left

[0079] 7: The recessed strip on the right

[0080] 6': The raised strip on the right

[0081] 7': The concave strip on the left

[0082] A, A1: Plate-shaped catalyst elements

[0083] B, B1: Plate-shaped catalyst elements

[0084] C: Plate-shaped airflow obstruction component

[0085] D: Plate-shaped airflow obstruction component

[0086] Gi: Inflowing gas

[0087] Go: Gas flows out.

Claims

1. A denitrification catalyst structure, wherein, The denitrification catalyst structure includes: A rectangular frame with a gas inlet and a gas outlet; Multiple plate-shaped catalyst elements, each having an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides, and containing catalyst components; and A plate-shaped airflow obstructor has an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides. Multiple plate-shaped catalyst elements are stacked in a frame with their edges aligned on both sides. Gaps exist between the stacked plate-shaped catalyst elements and between the inner surface of the frame and the edges of each plate-shaped catalyst element on its sides, allowing gas to pass through from the gas inlet to the gas outlet. The plate-shaped airflow obstructor is housed between the inner surface of the frame and the edges of the plate-shaped catalyst elements located on the sides, with the plate surface of the obstructor running along the inner surface of the frame. It also has a mechanism capable of obstructing the flow of gas without stopping the flow of gas passing between the inner surface of the frame and the edges of the plate-shaped catalyst elements located on the sides. The mechanism consists of raised or recessed strips disposed on the surface of the plate-shaped airflow obstructor and arranged non-parallel to the direction of gas flow.

2. The denitrification catalyst structure according to claim 1, wherein, The plate-shaped airflow barrier contains a catalyst component.

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