Denitration catalyst sytucture
Patent Information
- Authority / Receiving Office
- TW · TW
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2021-01-28
- Publication Date
- 2021-09-16
Smart Images
Figure TWG2TA000826111_001 
Figure TWG2TA000826111_002 
Figure TWG2TA000826111_003
Abstract
Description
[Technical Field]
[0001] This invention relates to a denitrification catalyst unit. More specifically, this invention relates to a denitrification catalyst unit that can achieve a high denitrification rate with lower pressure loss, which can help reduce initial operating costs. [Previous Technology]
[0002] In the presence of a denitrification catalyst, nitrogen oxides in the gases discharged from the furnaces of boilers in thermal power plants, various factories, and waste incinerators are decomposed, thus purifying the exhaust gas. Various denitrification catalyst structures or denitrification catalyst units have been proposed for the purpose of efficiently decomposing nitrogen oxides in exhaust gas.
[0003] For example, the catalyst structure of Patent Document 1 is composed of a plurality of plate-shaped catalyst elements stacked together. The plurality of stacked catalyst elements are composed of catalyst components with catalyst activity carried on the surface, and the protruding parts composed of strip-shaped protrusions and flat parts are alternately and intermittently arranged. The protruding parts of each catalyst element are arranged in a direction that continuously or partially intercepts the gas flow in the gas flow direction.
[0004] The catalyst structure of Patent Document 2 is composed of multiple plate-shaped catalyst elements stacked together. The plate-shaped catalyst elements have catalyst components on their surfaces and have alternating parallel protrusions and flat portions. The protrusions are stacked in a manner that blocks the gas flow. The protrusions are alternately adjacent to the front and back of the plate-shaped catalyst elements and each has two or more of the same number of protrusions. The plate-shaped catalyst elements, in which the protrusions are arranged with respect to the gas flow direction at 0 < θ ≦ 90° (but θ is the tilt angle of the protrusions with respect to the gas flow direction), are stacked sequentially with their front and back alternately reversed.
[0005] Patent Document 3, in its embodiment 14, involves stacking 46 catalyst substrates (150mm × 250mm in size, 2mm in height) with wavy lines inclined at approximately 30° to the long side and spaced 30mm apart at the short side) within a catalyst frame to create a 150mm × 150mm × 250mm catalyst carrier unit. This unit is then immersed in catalyst slurry, dried, and fired to prepare a unit-shaped catalyst. [Prior Art Documents] [Patent Documents]
[0006] [Patent Document 1] WO96 / 014920A1 [Patent Document 2] Japanese Patent Application Publication No. 2000-117120 [Patent Document 3] Japanese Patent Application Publication No. 2002-361092 [Summary of the Invention]
[0007] [The problem the invention aims to solve]
[0008] In the prior art catalyst structure, as shown in Figure 12, when the heat during operation drifts to the plate-shaped catalyst element, the edge portion of the plate-shaped catalyst element located on the gas inflow side will bend, and the width d of the flow path will be narrowed, becoming irregular, which will lead to an increase in pressure loss and a decrease in the denitrification rate.
[0009] The objective of this invention is to provide a denitrification catalyst unit that can achieve a high denitrification rate with lower pressure loss, thereby contributing to the reduction of initial operating costs such as fan power. [Technical means for solving the problem]
[0010] In order to solve the above-mentioned problems, the present invention, which includes the following form, was completed based on the results of the review.
[0011] [1] A denitrification catalyst unit is formed by stacking a plurality of plate-shaped catalyst elements having an edge on the gas inflow side, an edge on the gas outflow side, and edges on both sides, such that the edge on the gas inflow side and the edges on both sides are respectively aligned. Each plate-shaped catalyst element has a plurality of: a flat plate-shaped portion and a plate-shaped portion with protrusions on the top and bottom, and each protrusion is inclined at an angle θ of 50° to 85° and arranged parallel to each other with respect to the extending direction of the edge on the gas inflow side of the plate-shaped catalyst element. The ridge line of the protrusion on the top of one plate-shaped catalyst element and the ridge line of the protrusion on the bottom of another adjacent plate-shaped catalyst element are arranged in cross contact. At least one of the points of intersection exists in a range x of more than 0 mm and less than 25 mm from the edge on the gas inflow side of the plate-shaped catalyst element toward the inward side.
[0012] [2] As in [1], the denitrification catalyst unit, wherein each plate-shaped catalyst element contains: a plate-shaped substrate and the catalyst component it carries.
[0013] [3] A plate-shaped catalyst element has an edge on the gas inflow side and an edge on the gas outflow side, and edges on both sides. The plate-shaped catalyst element is each alternately having a plurality of: a planar plate-shaped flat portion and a plate-shaped concave and convex portion having parallel ridges on the top and bottom, and each ridge is inclined at an angle θ of 50° to 85° and arranged parallel to each other with respect to the extending direction of the edge on the gas inflow side of the plate-shaped catalyst element. When a plurality of plate-shaped catalyst elements are stacked such that the edge on the gas inflow side and the edges on both sides are respectively aligned, and the ridge line of ...
[0014] [4] The plate-shaped catalyst element as described in [3] comprises: a plate-shaped substrate and a catalyst component carried thereon. [Effects of the Invention]
[0015] According to the present invention, a higher denitrification rate can be achieved with lower pressure loss, which can help reduce initial operating costs. The present invention is optimal for removing nitrogen oxides (NOx) contained in the exhaust gas of gas plants.
Implementation Method
[0016] Embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, the scope of the present invention is not limited to the following embodiments.
[0017] The denitrification catalyst unit of the present invention is composed of a plurality of plate-shaped catalyst elements.
[0018] Each plate-shaped catalyst element preferably contains: a plate-shaped substrate and a catalyst component held on its surface. The plate-shaped catalyst element is manufactured, for example, by impregnating or coating a plate-shaped substrate such as a metal mesh, inorganic fiber woven fabric or non-woven fabric with a catalyst component, thereby holding the catalyst component on the plate-shaped substrate, and then subjecting it to a stamping process or the like.
[0019] The catalyst composition is not particularly limited as long as it has a denitrification catalyst effect. Examples include: those formed by containing oxides of titanium, molybdenum and / or tungsten, and oxides of vanadium (titanium-based catalysts); those formed by aluminum silicate mainly containing zeolites supported by metals such as Cu and Fe (zeolite-based catalysts); and those formed by a mixture of titanium-based and zeolite-based catalysts. Among these, titanium-based catalysts are preferred.
[0020] Examples of titanium-based catalysts include Ti-VW catalysts, Ti-V-Mo catalysts, and Ti-VW-Mo catalysts. The weight percentage of V to Ti, i.e., V₂O₅ / TiO₂, is preferably 2% by weight or less, more preferably 1% by weight or less. When molybdenum oxide and tungsten oxide are used together, the weight percentage of (MoO₃+WO₃) / TiO₂ is preferably 10% by weight or less, more preferably 5% by weight or less.
[0021] In the preparation of titanium-based catalysts, the raw material for titanium oxide can be titanium oxide powder or titanium oxide precursor. Examples of titanium oxide precursors include titanium oxide slurry, titanium oxide sol, titanium sulfate, titanium tetrachloride, titanates, titanium alkoxides, etc. In this invention, it is preferable to use titanium oxide that forms anatase-type titanium oxide as the raw material. The raw material for vanadium oxide can be vanadium compounds such as vanadium pentoxide, ammonium metavanadate, and vanadium oxysulfate. The raw material for tungsten oxide can be ammonium paratungstate, ammonium methyltungstate, tungsten trioxide, tungsten chloride, etc. The raw material for molybdenum oxide can be ammonium molybdate, molybdenum trioxide, etc.
[0022] In the catalyst components used in this invention, the co-catalyst or additive may also include: 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. When used in catalyst preparation, these may be in the form of powder, sol, slurry, fiber, etc.
[0023] The denitrification catalyst unit of the present invention, as shown in Figure 4, preferably has a plurality of plate-shaped catalyst elements housed in a frame 5.
[0024] Each plate-shaped catalyst element is formed into a plate shape and has an edge located on the gas inflow side, an edge located on the gas outflow side, and edges located on both sides. The overall shape of each plate-shaped catalyst element is preferably square or rectangular. Furthermore, in the denitrification catalyst unit of the present invention, the plate-shaped catalyst elements are stacked such that the edge located on the gas inflow side and the edges located on both sides are aligned.
[0025] Each plate-shaped catalyst element has a plurality of flat portions 1 and concave-convex portions 2 in an alternating manner. The flat portion 1 is a plate forming a plane. The concave-convex portion 2 is a plate forming parallel ridges 3 and 3' on the upper and lower surfaces respectively. The ridges 3 and 3' may be curved, but it is preferable to be substantially straight as shown in Figure 1, etc. The height h and the width w of the ridges 3 and 3' can be appropriately set. The width of the concave-convex portion 2 is 2w. Furthermore, the width w2 of the ridge cross-section on the edge located on the gas inflow side or gas outflow side is w / (sin(90°-θ)). The front and back surfaces of each ridge 3' and 3' are preferably concave ridges 4 and 4' corresponding to the shape of the ridge. Each concave-convex portion is preferably zig-shaped or S-shaped in cross-section by the ridges located on the upper and lower surfaces. Furthermore, in the uneven portion 2 shown in the figure, the thin lines represent the ridges of the raised strips, and the thick lines represent the valleys of the recessed strips. Moreover, the ratio h / w of height h to width w tends to result in a higher denitrification rate as the ratio h / w increases, and a lower ratio h / w tends to result in a lower pressure loss. While the plate thickness t in the flat portion and the uneven portion is not particularly limited, it is preferably 0.1 to 0.5 mm.
[0026] Each convex strip is inclined at an angle θ to the extending direction of the edge of the plate-shaped catalyst element on the gas inflow side, and is arranged parallel to each other. The lower limit of angle θ is 50°, preferably 55°, more preferably 65°, and even more preferably 70°, and the upper limit is 85°, preferably 83°, and more preferably 80°. A smaller angle θ tends to result in a higher denitrification rate. A larger angle θ tends to result in a higher pressure loss reduction effect. It is preferable that the convex strips arranged parallel to each other on the same surface are equally spaced. The distance p between the edges of the convex strips arranged parallel to each other on the same surface can be appropriately set. Furthermore, the width p0 is p-2w or w1sin(90°-θ). The plate-shaped catalyst element of the present invention tends to have a higher pressure loss as the angle θ increases, and a higher denitrification rate as the width p0 decreases.
[0027] In the denitrification catalyst unit of the present invention, the ridge line of the upper protrusion 3 of a plate-shaped catalyst element and the ridge line of the lower protrusion 3' of an adjacent plate-shaped catalyst element are arranged in a cross-contact configuration. The inferior angle θ1 formed by the two ridge lines at the intersection point is preferably 10° to 80°, more preferably 20° to 70°, and even more preferably 20° to 65°. By the cross-contact configuration of the ridge lines, the average distance between the upper surface of the flat portion of the plate-shaped catalyst element and the lower surface of the flat portion of the adjacent plate-shaped catalyst element is limited to a lower limit by the height of the aforementioned protrusions 3 and 3'.
[0028] In the denitrification catalyst unit of the present invention, at least one of the aforementioned intersecting points 6 and 6' is in the range x from the edge of the plate-shaped catalyst element on the gas inflow side toward the inward side (gas outflow side), which is more than 0 mm and less than 25 mm, preferably more than 4 mm and less than 20 mm, and more preferably more than 7 mm and less than 16 mm.
[0029] An example of the state of the intersection points 6 and 6' within this range x is shown below. The plate-shaped catalyst element B shown in Figure 2 is a plate-shaped catalyst element A shown in Figure 1 with its front and back sides reversed. When reversed in this way, the cross-section of the uneven portion on the front (gas inflow) side edge of the plate-shaped catalyst element A becomes a Z-shaped waveform, and the cross-section of the uneven portion on the front (gas inflow) side edge of the plate-shaped catalyst element B forms an inverted Z-shaped waveform. As shown in Figures 3, 5, and 6, the point 6 (Figure 5) where the ridge line of the upper ridge of the plate-shaped catalyst element A and the ridge line of the lower ridge of the plate-shaped catalyst element B intersect, and the point 6' (Figure 6) where the ridge line of the lower ridge of the plate-shaped catalyst element A and the ridge line of the upper ridge of the plate-shaped catalyst element B intersect, are arranged to move left and right alternately from positions at almost the same distance from the edge on the gas inflow side. In the case where plate-shaped catalyst elements A and B are used by flipping one plate-shaped element backwards, since at least one intersection point exists in the range x, the difference between W3 and W4 is preferably 2x / (tanθ).
[0030] The plate-shaped catalyst element C shown in Figure 6 is a plate-shaped catalyst element A shown in Figure 1 with its left and right sides reversed. When flipped in this way, the cross-section of the uneven portion on the front (gas inflow) side edge of the plate-shaped catalyst element A and the cross-section of the uneven portion on the front (gas inflow) side edge of the plate-shaped catalyst element B both form a Z-shaped waveform. As shown in Figures 8, 9 and 10, the point 6 where the ridge line of the upper ridge of the plate-shaped catalyst element A and the ridge line of the lower ridge of the plate-shaped catalyst element C intersect, and the point 6' where the ridge line of the lower ridge of the plate-shaped catalyst element A and the ridge line of the upper ridge of the plate-shaped catalyst element C intersect, are arranged in an alternating back-and-forth manner at positions that are almost equal in distance from the edges of both sides. In the case where a plate-shaped catalyst element A and a plate-shaped catalyst element C are used by flipping a plate-shaped element left and right, since at least one intersection point exists in the range x, the edge of the ridge is located at the midpoint of the width of the ridge. In this case, the difference between W3 and W4 is 2x / (tanθ)-1.5W2.
[0031] The intersecting points 6 and 6' are located within range x, so even when the plate-shaped catalyst element wobbles, it can remain within the edge on the gas inflow side, and the distance d between the upper surface of the flat portion of the plate-shaped catalyst element and the lower surface of the flat portion of the adjacent plate-shaped catalyst element can be prevented from becoming uneven (Figure 11). Therefore, because the denitrification catalyst unit of the present invention can achieve a high denitrification rate with lower pressure loss, it can help reduce initial operating costs such as fan power.
[0032] The following examples illustrate the effects of the denitrification catalyst unit of the present invention.
[0033] Comparative Example: The positions of points 6 and 6' where plate-shaped catalyst elements with an angle θ of 75° and p0 of 30 mm overlap and intersect are arranged such that the distance from the edge on the gas inflow side is 30 mm. Simulated combustion exhaust flow is applied here, and pressure loss and denitrification rate are measured.
[0034] In this embodiment, the plate-shaped catalyst element A with an angle θ of 75° and p0 of 30 mm is arranged such that the points 6 and 6' of the plate overlap and intersect as shown in Figures 3 to 6, so that the denitrification catalyst unit is assembled at a distance of 10 mm from the edge located on the gas inflow side. Simulated combustion exhaust flow is applied here, and the pressure loss and denitrification rate are measured.
[0035] The pressure loss of the denitrification catalyst unit in the embodiment is about 30% lower than that of the denitrification catalyst unit in the comparative example. The denitrification rate of the denitrification catalyst unit in the embodiment is higher than that of the denitrification catalyst unit in the comparative example. [Simplified Explanation of the Diagram]
[0037] [Figure 1] shows a three-view (front, top, and right side) view of the plate-shaped catalyst element A used in this invention. [Figure 2] shows a three-view (front, top, and right side) view of the plate-shaped catalyst element B used in this invention. [Figure 3] shows a front view of an example of the denitrification catalyst unit of this invention. [Figure 4] shows a perspective view of an example of the denitrification catalyst unit of this invention. [Figure 5] shows the arrangement (top perspective) of the points where the ridge lines of the upper convex strip of the plate-shaped catalyst element A and the ridge lines of the lower convex strip of the plate-shaped catalyst element B intersect. [Figure 6] shows the arrangement (top perspective) of the points where the ridge lines of the lower convex strip of the plate-shaped catalyst element A and the ridge lines of the upper convex strip of the plate-shaped catalyst element B intersect. [Figure 7] shows a three-view (front, top, and right side) view of the plate-shaped catalyst element C used in this invention. [Figure 8] shows a front view of an example of the denitrification catalyst unit of this invention. [Figure 9] A top-view diagram showing the arrangement of the points where the ridges of the upper ridge of the plate-shaped catalyst element A and the ridges of the lower ridge of the plate-shaped catalyst element C intersect. [Figure 10] A top-view diagram showing the arrangement of the points where the ridges of the lower ridge of the plate-shaped catalyst element A and the ridges of the upper ridge of the plate-shaped catalyst element C intersect. [Figure 11] An example of the state of the edge located on the gas inflow side in the denitrification catalyst unit of the present invention. [Figure 12] An example of the state of the edge located on the gas inflow side in a prior art denitrification catalyst unit.
Claims
1. A denitrification catalyst unit is formed by stacking a plurality of plate-shaped catalyst elements having an edge on a gas inflow side, an edge on a gas outflow side, and edges on both sides, such that the edge on the gas inflow side and the edges on both sides are respectively aligned. Each plate-shaped catalyst element has a plurality of: a flat plate-shaped portion and plate-shaped portions with raised strips on the top and bottom, and each raised strip is inclined at an angle of 50° to 85° and arranged parallel to each other with respect to the extending direction of the edge on the gas inflow side of the plate-shaped catalyst element. The ridge line of the raised strip on the top of one plate-shaped catalyst element and the ridge line of the raised strip on the bottom of another adjacent plate-shaped catalyst element are arranged in cross contact, and at least one of the intersection points exists in a range of more than 0 mm and less than 25 mm from the edge on the gas inflow side of the plate-shaped catalyst element toward the inward side.
2. As in request item 1, the denitrification catalyst unit, wherein, Each plate-shaped catalyst element contains: a plate-shaped substrate and catalyst components carried thereon.
3. A plate-shaped catalyst element having an edge on a gas inflow side, an edge on a gas outflow side, and edges on both sides, wherein each plate-shaped catalyst element has, in an alternating manner, a plurality of: a planar plate-shaped flat portion and plate-shaped uneven portions having ridges on the top and bottom, wherein each ridge is inclined at an angle of 50° to 85° and arranged parallel to each other with respect to the extending direction of the edge on the gas inflow side of the plate-shaped catalyst element. When a plurality of plate-shaped catalyst elements are stacked such that the edges on the gas inflow side and the edges on both sides are respectively aligned, and the ridges of the ridges of the ridges on the top of one plate-shaped catalyst element and the ridges of the ridges of the ridges on the bottom of another adjacent plate-shaped catalyst element are arranged in a cross-contact manner, at least one of the cross points exists in a range of more than 0 mm and less than 25 mm from the edge on the gas inflow side of the plate-shaped catalyst element toward the inward side.
4. The plate-shaped catalyst element as described in claim 3, wherein, It contains: a plate-shaped substrate and a catalyst component carried thereon.