Denitrification catalyst grinding device

Abstract

The present invention provides a denitration catalyst abrasion method and a denitration catalyst abrasion device with which the denitration catalyst abrasion efficiency can be improved.　A denitration catalyst abrasion device 1 allows an abrasive A and air to flow through through holes C1 in a denitration catalyst C provided with the plurality of through holes C1 extending in a longitudinal direction to abrade the inner surfaces of the through holes C1. The denitration catalyst abrasion device 1 includes: a mixing part 10 that is provided on the upstream side of the denitration catalyst C and mixes the abrasive A and the air; a suction fan 70 that is provided on the downstream side of the denitration catalyst C and sucks the abrasive A and the air; and a first classifying part 41 and a second classifying part 42 that classify the abrasive A after abrasing the denitration catalyst C. Second abrasive grains A2 classified by the first classifying part 41 and first abrasive grains A1 classified by the second classifying part 42 are supplied to the mixing part 10.

Description

[Technical field]

[0001] The present invention relates to a denitration catalyst polishing device for polishing a denitration catalyst. [Background technology]

[0002] At thermal power plants, nitrogen oxides are generated when coal is burned. To protect the environment, it is necessary to keep nitrogen oxide emissions below a certain level. For this reason, thermal power plants are equipped with denitration equipment filled with denitration catalysts to reduce nitrogen oxides. The performance of denitration catalysts deteriorates with continued use. One technique for regenerating denitration catalysts with reduced performance is polishing regeneration. Polishing regeneration is a technique that restores catalytic performance by polishing the surface of denitration catalysts with reduced performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2014 / 155628 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 discloses a technique for regenerating a denitration catalyst, in which a mixture of an abrasive (grinding material) and gas is passed through the through-holes of the denitration catalyst to grind the inner walls of the through-holes. An upstream fixed member having an expanded portion with a cross-sectional area larger than the cross-sectional area of ​​the member to be ground, which is made of a denitration catalyst, is connected to one end of the member to be ground. A screen member is disposed in the expanded portion. Within such an expanded portion, the flow rate of the mixture of the abrasive and gas is reduced and dispersed, enabling uniform grinding of the inner walls of the through-holes.

[0005] The technology described in Patent Document 1 is capable of uniformly polishing the through-holes by reducing the flow rate of the mixture of the abrasive and the gas in the expanding section and dispersing it, but there is a problem that the polishing efficiency decreases when the flow rate of the abrasive is reduced. However, there are cases where simply increasing the flow rate of the abrasive in order to improve the polishing efficiency does not necessarily lead to an improvement in the polishing efficiency.

[0006] The present invention has been made in view of the above, and relates to a method and apparatus for polishing a denitration catalyst that can improve the efficiency of polishing a denitration catalyst. [Means for solving the problem]

[0007] The present invention relates to a denitration catalyst polishing device that polishes the inner surfaces of a denitration catalyst having a plurality of through holes extending in the longitudinal direction by circulating an abrasive together with air through the through holes, the denitration catalyst having a plurality of through holes extending in the longitudinal direction, the denitration catalyst polishing device having a mixing section that is arranged upstream of the denitration catalyst and mixes the abrasive with air, a suction section that is arranged downstream of the denitration catalyst and sucks in the abrasive together with air, and a first classification section and a second classification section that classify the abrasive after polishing the denitration catalyst, and the abrasive supplied to the mixing section includes second abrasive grains classified in the first classification section and first abrasive grains classified in the second classification section.

[0008] It is preferable that the first classification section classifies the second abrasive grains, and the first abrasive grains and third abrasive grains having a grain size larger than that of the second abrasive grains, and the second classification section classifies the first abrasive grains and the third abrasive grains having a grain size smaller than that of the first abrasive grains, and the abrasive consisting of the first abrasive grains and the second abrasive grains is supplied to the mixing section.

[0009] It is preferable that the grinding machine has a first storage section for storing the first abrasive grains and a second storage section for storing the second abrasive grains, the first storage section having a first supply section capable of adjusting the amount of the first abrasive grains supplied to the mixing section, and the second storage section having a second supply section capable of adjusting the amount of the second abrasive grains supplied to the mixing section.

[0010] It is preferable that the first abrasive grains have an average particle size D1 of 1.65 to 2.16 mm, and the second abrasive grains have an average particle size D2 of 0.30 to 0.45 mm.

[0011] The first abrasive grains are preferably contained in an amount of 5 to 15% by weight in the abrasive supplied to the mixing section. Effect of the Invention

[0012] The present invention can provide a method and apparatus for polishing a Denitration catalyst that can improve the efficiency of polishing a Denitration catalyst. [Brief description of the drawings]

[0013] [Figure 1] 1 is a configuration diagram of a thermal power plant in which a denitration catalyst according to an embodiment of the present invention is used. [Diagram 2] FIG. 1 is a diagram showing an example of the configuration of a denitrification device in a thermal power generation facility. [Diagram 3] 1 is a schematic configuration diagram of a denitration catalyst polishing apparatus according to an embodiment of the present invention. [Figure 4] 2 is a schematic diagram showing a classification unit of the denitration catalyst polishing apparatus according to the embodiment of the present invention. FIG. [Diagram 5] FIG. 2 is a schematic diagram showing a polishing state by the denitration catalyst polishing apparatus according to the embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described. The denitration catalyst to be polished by the denitration catalyst polishing method and denitration catalyst polishing apparatus according to the embodiment of the present invention is, for example, a denitration catalyst C that has been used for a certain period of time in a coal-fired power plant 100 described below and has deteriorated in performance.

[0015] [Coal-fired power generation facilities] As shown in FIG. 1, the coal-fired power generation facility 100 includes a coal bunker 110, a coal feeder 115, a coal pulverizer 120, a pulverized coal supply pipe 130, a combustion boiler 140, an exhaust passage 150 provided downstream of the combustion boiler 140, a denitration device 160 provided in the exhaust passage 150, an air preheater 170, a heat recovery gas heater 180, an electrostatic precipitator 190, an induced draft fan 210, a wet desulfurization device 220, a reheat gas heater 230, a desulfurization fan 240, and a chimney 250.

[0016] The coal bunker 110 stores coal supplied from a coal silo (not shown) by a coal transportation facility. The coal feeder 115 supplies the coal supplied from the coal bunker 110 to the coal pulverizer 120 at a predetermined supply speed. The coal pulverizer 120 produces pulverized coal by pulverizing the coal supplied from the coal feeder 115 to an average particle size of 60 μm to 80 μm. As the coal pulverizer 120, a roller mill, a tube mill, a bora mill, a beater mill, an impeller mill, or the like is used.

[0017] The combustion boiler 140 burns the pulverized coal supplied from the pulverized coal supply pipe 130 with forcibly supplied air by the pulverized coal burner b. Combustion of the pulverized coal produces coal ash such as clinker ash and fly ash, and generates exhaust gas. The clinker ash refers to the coal ash in the form of lumps that fall to the bottom of the combustion boiler 140. The fly ash refers to the coal ash with a small particle size (particle size of about 200 μm or less) that flows into the exhaust passage 150 side together with the exhaust gas. The exhaust passage 150 is disposed downstream of the combustion boiler 140 and allows the exhaust gas and coal ash generated in the combustion boiler 140 to flow therethrough.

[0018] The denitration device 160 removes nitrogen oxides from the exhaust gas. The denitration device 160 removes nitrogen oxides from the exhaust gas, for example, by a dry ammonia catalytic reduction method. The dry ammonia catalytic reduction method is a method in which ammonia gas is injected as a reducing agent into exhaust gas at a relatively high temperature (300°C to 400°C), and the nitrogen oxides in the exhaust gas are decomposed into nitrogen and water vapor by the action of a denitration catalyst.

[0019] 2, the denitration device 160 includes a denitration reactor 161 in which a denitration reaction takes place, and a plurality of denitration catalyst layers 162 disposed inside the denitration reactor 161. The denitration catalyst layers 162 are composed of a plurality of casings 163. The casings 163 house a plurality of denitration catalysts C. The denitration catalyst C is an elongated (rectangular) catalyst having a honeycomb structure with a plurality of through holes C1 extending in the longitudinal direction. The denitration catalysts C are arranged such that the extension direction of the through holes C1 is aligned with the flow path of the exhaust gas.

[0020] The air preheater 170 is disposed downstream of the denitration device 160 in the exhaust passage 150. The air preheater 170 exchanges heat between the exhaust gas that has passed through the denitration device 160 and the combustion air, thereby cooling the exhaust gas and heating the combustion air. The heated combustion air is supplied to the boiler 140 by a forced draft fan 175.

[0021] The heat recovery gas heater 180 is disposed downstream of the air preheater 170 in the exhaust passage 150. The heat recovery gas heater 180 is supplied with the exhaust gas from which heat has been recovered in the air preheater 170. The heat recovery gas heater 180 further recovers heat from the exhaust gas.

[0022] The electrostatic precipitator 190 is disposed downstream of the heat recovery gas heater 180 in the exhaust passage 150. Exhaust gas from which heat has been recovered in the heat recovery gas heater 180 is supplied to the electrostatic precipitator 190. The electrostatic precipitator 190 is a device that collects (captures) coal ash (fly ash) in the exhaust gas by applying a voltage to electrodes. The fly ash collected (captured) in the electrostatic precipitator 190 is collected in a fly ash recovery device 191.

[0023] The induced draft fan 210 is disposed downstream of the electrostatic precipitator 190 in the exhaust passage 150. The induced draft fan 210 takes in the exhaust gas from which fly ash has been removed in the electrostatic precipitator 190 from the primary side and sends it out to the secondary side.

[0024] The desulfurization device 220 is disposed downstream of the induced draft fan 210 in the exhaust passage 150. The desulfurization device 220 is supplied with the flue gas sent out from the induced draft fan 210. The desulfurization device 220 removes sulfur oxides in the flue gas, for example, by a wet lime-gypsum method. The wet lime-gypsum method is a method in which a mixed liquid of limestone and water is sprayed onto the flue gas, causing the sulfur oxides contained in the flue gas to be absorbed into the mixed liquid to generate a desulfurized gypsum slurry, thereby removing the sulfur oxides in the flue gas. Wastewater containing trace substances such as boron and selenium generated during this process is treated by a wastewater treatment device 221.

[0025] The reheating gas heater 230 is disposed downstream of the desulfurization device 220 in the exhaust passage 150. Exhaust gas from which sulfur oxides have been removed in the desulfurization device 220 is supplied to the reheating gas heater 230. The reheating gas heater 230 heats the exhaust gas. The heat recovery gas heater 180 and the reheating gas heater 230 may be configured as a gas-gas heater that performs heat exchange between the exhaust gas flowing between the air preheater 170 and the electrostatic precipitator 190 in the exhaust passage 150 and the exhaust gas flowing between the desulfurization device 220 and the desulfurization fan 240.

[0026] The desulfurization fan 240 is disposed downstream of the reheat gas heater 230 in the exhaust passage 150. The desulfurization fan 240 takes in the exhaust gas heated in the reheat gas heater 230 from the primary side and sends it out to the secondary side.

[0027] The chimney 250 is disposed downstream of the desulfurization fan 240 in the exhaust passage 150. Exhaust gas heated by the reheat gas heater 230 is introduced into the chimney 250. The chimney 250 discharges the exhaust gas.

[0028] [Denitrification catalyst polishing equipment] The denitration catalyst C used in the above-described coal-fired power plant 100 loses its denitration performance with continued use due to thermal deterioration such as sintering, chemical deterioration due to poisoning of the catalyst components, and physical deterioration due to soot coating the catalyst surface, etc. The denitration performance of the denitration catalyst C with reduced denitration performance can be restored by polishing the inner surface of the through-hole C1, which is the catalyst surface, and removing any attached matter on the surface. Hereinafter, a description will be given of a Denitration catalyst polishing device 1 that polishes the inner surface of the through-hole C1 of a Denitration catalyst C whose denitration performance has deteriorated, thereby recovering the denitration performance.

[0029] The denitration catalyst polishing apparatus 1 according to this embodiment is an apparatus for polishing the inner surface of the through-hole C1 of the denitration catalyst C by circulating the abrasive A together with air through the through-hole C1. As shown in FIG. 3, the denitration catalyst polishing apparatus 1 includes a mixer 10, an inlet 20, an outlet 30, a cyclone 40, a first classifying section 41 and a second classifying section 42, a compressor 50, a bag filter 60, and a suction fan 70. The denitration catalyst C to be polished by the denitration catalyst polishing apparatus 1 is sandwiched between an upstream fixing member 22 in the inlet 20 and a downstream fixing member 32 in the outlet 30. The denitration catalyst C is fixed so that the flow direction of the through-hole C1 of the denitration catalyst C is approximately perpendicular to a horizontal plane.

[0030] The mixing section 10 mixes the air and the abrasive A, and supplies the abrasive A mixed with the air to the denitration catalyst C through the inflow path 20. For example, the mixing section 10 is provided with a blast gun 11, a funnel section 12, and a cabinet 13 that accommodates them. The blast gun 11 is connected to a compressor 50 through an air hose 51, and can inject compressed air. A plurality of blast guns 11 may be provided. The blast gun 11 is connected to an abrasive supply path 33, which will be described later. When compressed air is injected from the blast gun 11, an ejector effect occurs, and the abrasive A is supplied into the blast gun 11 through the abrasive supply path 33. Then, the abrasive A and the compressed air are mixed inside the blast gun 11, and are injected into the funnel section 12. The injected abrasive A flows into the inflow path 20 through the funnel section 12 in a state where it is uniformly mixed with the air.

[0031] Instead of the above-mentioned configuration having the blast gun 11, the funnel portion 12, and the cabinet 13, the mixing portion 10 may be configured to have a storage portion for storing the abrasive A below the upstream fixing member 22. The abrasive A is sucked vertically from the storage portion together with air and flows from the bottom to the top of the through-hole C1 of the DeNOx catalyst C through the inflow passage 20, whereby the inside of the through-hole C1 can be uniformly polished.

[0032] The inflow passage 20 is a passage on the upstream side of the denitration catalyst C, and is a passage through which the abrasive A mixed with air flows in from below the denitration catalyst C. The inflow passage 20 is composed of an upstream flow passage 21 and an upstream fixing member 22. The upstream flow passage 21 is, for example, a flow passage having a bent portion, and the upstream side is connected to the funnel portion 12, and the downstream side is connected to the upstream fixing member 22. The upstream fixing member 22 has a straight flow passage, and the downstream side is connected to the lower end (upstream end) of the denitration catalyst C to fix the denitration catalyst C. The abrasive A mixed with air flows into the through hole C1 of the denitration catalyst C through the upstream fixing member 22. The configuration of the abrasive A flowing into the through hole C1 of the denitration catalyst C will be described in detail later. In addition, when the mixing section 10 is configured to have the above-mentioned storage section, the upstream flow path 21 does not have a bent section and consists of a flow path extending in the vertical direction, with the upstream side connected to the above-mentioned storage section and the downstream side connected to the upstream fixing member 22.

[0033] The outflow path 30 is a flow path downstream of the denitration catalyst C. The outflow path 30 is a flow path through which the abrasive A and the object to be polished generated by polishing the surface of the denitration catalyst C flow. The abrasive A and the object to be polished are sucked together with air by a suction fan 70 serving as a suction section. A cyclone 40 is provided midway through the outflow path 30, and the abrasive A and the object to be polished are separated.

[0034] The outflow path 30 has a downstream fixing member 32 that is connected to the upper end (downstream end) of the denitration catalyst C to fix the denitration catalyst C, a downstream flow path 31 that connects the downstream fixing member 32 to the cyclone 40, and an abrasive supply path 33 that connects the cyclone 40 to the mixing section 10.

[0035] The cyclone 40 is a known cyclone classifier and is disposed at a higher position than the mixing section 10. The upstream end of the cyclone 40 is connected to the downstream flow path 31. The abrasive supply path 33 is connected to the lower part of the cyclone 40, and the abrasive A separated by the cyclone 40 falls by gravity through the abrasive supply path 33 and is supplied to the mixing section 10 via the first classification section 41 and the second classification section 42. The downstream end of the cyclone 40 is connected to a conveying pipe 44, and the downstream end of the conveying pipe 44 is connected to a bag filter 60. The object to be polished separated by the cyclone 40 flows into the bag filter 60 through the conveying pipe 44 together with air. At this time, a part of the abrasive A having a small particle size also flows into the bag filter 60 together with the object to be polished.

[0036] The bag filter 60 is a known dust collecting device. The bag filter 60 captures dust in the air, including the object to be polished of the denitration catalyst C and the abrasive A having a small particle size. The captured dust is stored in a storage unit (not shown) provided at the bottom of the bag filter 60, and is collected at a desired timing. The downstream end of the bag filter 60 is connected to a connecting pipe 61. The downstream end of the connecting pipe 61 is connected to a suction fan 70 as a suction unit. The clean air from which dust has been removed by passing through the bag filter 60 is sucked in by the suction fan 70 and discharged into the atmosphere by an exhaust duct 71.

[0037] Next, the details of the configurations of the abrasive A and the first and second classifying sections 41 and 42 according to this embodiment will be described below with reference to the drawings.

[0038] <Abrasive A (abrasive grains A1 to A4)> The first classification section 41 and the second classification section 42 classify the abrasive A after polishing the denitration catalyst C separated by the cyclone 40 into a first abrasive grain A1, a second abrasive grain A2, and a third abrasive grain A3 having specific average particle diameters (hereinafter, they may be simply referred to as "abrasive grain A1", "abrasive grain A2", and "abrasive grain A3"). FIG. 4 is a schematic diagram showing the flow of the abrasive A classified by the first classification section 41 and the second classification section 42. The abrasive grain A1, the abrasive grain A2, and the abrasive grain A3 have average particle diameters D1, D2, and D3, respectively. The average particle diameters D1, D2, and D3 can be expressed as particle diameters at the 50% point of the cumulative height, and have a relationship of D1>D3>D2. Among them, the abrasive grain A1 having the average particle diameter D1 and the abrasive grain A2 having the average particle diameter D2 are used for polishing the denitration catalyst C. As shown in Fig. 4, the abrasive grains A4, which have an average particle size smaller than that of the abrasive grains A2, are separated from the abrasive grains A1 to A3 by the cyclone 40 and flow into the bag filter 60 together with the workpiece. The abrasive grains A3 are classified in the second classifying section 42 and then discarded.

[0039] 5, the denitration catalyst C according to this embodiment is arranged and fixed so that the flow direction of the multiple through holes C1 is approximately perpendicular to the horizontal plane. Abrasive A, which is made of abrasive grains A1 and A2 mixed with air, flows from below to above the multiple through holes C1 through an upstream fixing member 22 connected to the lower side of the denitration catalyst C, to polish the inner surface of the through holes C1.

[0040] Since the abrasive grains A1 and A2 have different average particle diameters, they flow through the through hole C1 at different speeds. The abrasive grains A1, which have a larger particle diameter, have a larger mass than the abrasive grains A2. Therefore, when the abrasive grains A1 and A2 flow through the through hole C1 from bottom to top together with the air, the gravity acting on the abrasive grains A1 is greater than that on the abrasive grains A2, so the flow speed of the abrasive grains A1 is slower than the flow speed of the abrasive grains A2. Then, the abrasive grains A2 collide with the abrasive grains A1, and the abrasive grains A2 are scattered in the through hole C1. As a result, the proportion of the abrasive grains A2 that collide with the inner surface of the through hole C1 increases, and the polishing efficiency of the denitration catalyst C is improved.

[0041] If the flow speed of the abrasive grains contained in the abrasive A is the same, the collision described above is unlikely to occur. In this case, when the flow speed of the abrasive A is increased, the ratio of the abrasive grains that do not collide with the inner surface of the through hole C1 and slip through the through hole C1 increases. Therefore, even if the flow speed of the abrasive A is increased, there are cases where the polishing efficiency is not improved accordingly. In this embodiment, the polishing efficiency of the denitration catalyst C can be improved by using two types of abrasive grains A1 and A2 with different flow speeds for polishing the denitration catalyst C.

[0042] In order to improve the polishing efficiency, the abrasive grains A1 preferably have a grain size of F7 to F14, more preferably F8 to F12, and even more preferably F10, as specified in JIS R6001. Similarly, the average grain size of the abrasive grains A2 preferably has a grain size of F36 to F60, more preferably F40 to F54, and even more preferably F46, as specified in JIS R6001. The average grain size of the abrasive grains A1 at the 50% point of the cumulative height is preferably 1.65 to 2.16 mm. The average grain size of the abrasive grains A2 at the 50% point of the cumulative height is preferably 0.30 to 0.45 mm.

[0043] The ratio of the abrasive grains A1 in the polishing material A is preferably 5 to 15% by weight. If the ratio of the abrasive grains A1 is too low relative to the above range, the polishing efficiency cannot be sufficiently improved. If the ratio of the abrasive grains A1 is too high relative to the above range, the denitration catalyst C cannot be polished uniformly, resulting in some areas that are insufficiently polished and others that are over-polished. In addition, the denitration catalyst C may be damaged.

[0044] The material of the abrasive A is not particularly limited, but examples thereof include diamond, CBN (cubic boron nitride), B4C (boron carbide), silicon carbide, silica, ceria, alumina, white alumina, zirconia, titania, manganese oxide, barium carbonate, chromium oxide, and iron oxide.

[0045] In the denitration catalyst polishing device 1 according to this embodiment, the abrasive A after polishing the denitration catalyst C is separated from the object to be polished by the cyclone 40, recovered, and can be used again to polish the denitration catalyst C. This reduces the consumption of the abrasive A and the amount of waste. However, as the polishing of the denitration catalyst C is continued by reusing the abrasive A, the ratio of the abrasive A1 to the abrasive A changes because the abrasive grains A1 with a large grain size are easily broken. Therefore, there is a risk that the polishing of the denitration catalyst C cannot be performed sufficiently and uniformly. The first classification section 41 and the second classification section 42 according to this embodiment can make the ratio of the abrasive grains A1 to the abrasive A constant. Therefore, the polishing of the denitration catalyst C can be performed sufficiently and uniformly.

[0046] Furthermore, as the polishing of the denitration catalyst C continues, abrasive grains A3 having an average particle size intermediate between the average particle sizes of the abrasive grains A1 and A2 are generated. Such abrasive grains A3 have a small speed difference with the abrasive grains A1 and A2 when flowing through the through holes C1, so the effect of improving the polishing efficiency by colliding the abrasive grains with each other is low. Since the denitration catalyst polishing device 1 according to this embodiment is capable of classifying and discarding the abrasive grains A3, only the abrasive grains A1 and A2, which have a large speed difference when flowing through the through holes C1, can be used for polishing the denitration catalyst C, and high polishing efficiency can be maintained.

[0047] <1st classification section and 2nd classification section> The first classification section 41 classifies the abrasive grains A2 and the abrasive grains A1 and A3, which have a larger grain size than the abrasive grains A2. For example, the first classification section 41 may be a sieve having a mesh member through which the abrasive grains A2 can pass and through which the abrasive grains A1 and A3 cannot pass. The mesh member is not particularly limited, but may be, for example, a wire mesh having a predetermined mesh size, an expanded metal formed by expanding a metal plate with slits, or a punched metal formed by punching holes in a metal plate with a press or the like. In this embodiment, the mesh member is used as the first classification section 41, and the first classification section 41 is installed at a predetermined angle inclined to the horizontal direction. This is preferable because classification can be performed without requiring power.

[0048] The sieve having the above-mentioned mesh member as the first classification section 41 is an example of a classifier that uses gravity, and in addition to the above-mentioned classifier, any known classifier such as a classifier that uses inertial force or a classifier that uses centrifugal force may also be used as the first classification section 41.

[0049] The second classifying section 42 is provided after the first classifying section 41, and classifies the abrasive grains A1 and A3 classified by the first classifying section 41 into abrasive grains A1 and A3. The second classifying section 42 has a similar configuration to the first classifying section 41, except that the particle size of the abrasive grains that can pass through it is different.

[0050] The abrasive grains A2 classified by the first classifier 41 are stored in the second storage section 411. The second storage section 411 is disposed above the mixing section 10 and is connected to the mixing section 10 by the abrasive supply path 33a, and has a second supply section 411a capable of adjusting the supply amount of the abrasive grains A2 supplied to the mixing section 10. The configuration of the second supply section 411a is not particularly limited, but for example, the second supply section 411a is composed of a hole portion formed at the bottom of the second storage section 411 and capable of changing the hole diameter. Then, by changing the hole diameter of the second supply section 411a, the supply amount of the abrasive grains A2 supplied from the second storage section 411 to the mixing section 10 can be adjusted. According to the above configuration, the supply amount of the abrasive grains A2 can be easily adjusted without having a complicated configuration. The abrasive grains A1 and A3 classified by the first classifier 41 are supplied to the second classifier 42.

[0051] The abrasive grains A1 classified by the second classifying section 42 are stored in a first storage section 421. Similar to the second storage section 411, the first storage section 421 is disposed above the mixing section 10 and is connected to the mixing section 10 via an abrasive supply path 33b, and has a first supply section 421a capable of adjusting the supply amount of the abrasive grains A1 supplied to the mixing section 10. Similar to the second supply section 411a, the first supply section 421a is composed of a hole section whose hole diameter is changeable and is formed, for example, in the bottom of the first storage section 421.

[0052] The abrasive grains A3 classified by the second classifying section 42 are stored in the third storage section 43. The abrasive grains A3 stored in the third storage section 43 are collected and discarded at a predetermined timing.

[0053] (Polishing regeneration method) Next, a method for polishing and regenerating the DeNOx catalyst C using the DeNOx catalyst polishing apparatus 1 will be described. The denitration catalyst C with reduced denitration performance, which is the object to be polished by the denitration catalyst polishing apparatus 1, is removed from the denitration device 160 of the coal-fired power plant 100. At this time, the through-holes C1 of the denitration catalyst C may be clogged with coal ash or the like, so the clogged matter is removed by air blowing, water washing, or the like as appropriate. Next, the denitration catalyst C is sandwiched between the upstream fixing member 22 and the downstream fixing member 32 to fix the denitration catalyst C. At this time, for example, the side of the denitration catalyst C with more deposits, which was the inlet end of the exhaust gas inlet of the denitration device 160, may be arranged and fixed so that it is located downstream, where the flow rate of the abrasive A is high.

[0054] When the operation of the denitration catalyst polishing device 1 is started, the suction fan 70 and the compressor 50 start to operate, and the abrasive A mixed with air in the mixer 10 is sucked upstream. The abrasive A flows into the through hole C1 of the denitration catalyst C via the upstream flow path 21 and the upstream fixing member 22. The abrasive A flowing into the through hole C1 is composed of abrasive grains A1 and A2, and for example, the abrasive grains A1 have a larger average particle diameter than the abrasive grains A2, and the flow rate in the through hole C1 is smaller than that of the abrasive grains A2. Therefore, the abrasive grains A2 collide with the abrasive grains A1 and scatter, and thus tend to collide with the inner surface of the through hole C1. The inner surface of the through hole C1 is efficiently polished by such abrasive grains A1 and A2.

[0055] After polishing the inner surface of the through hole C1, the abrasive A flows out from the downstream fixed member 32. At this time, as shown in FIG. 4, the abrasive grains A1 and A2 are used to polish the through hole C1, or the abrasive grains collide with each other, causing cracks or chipping, and abrasive grains A3 having an average particle diameter D3 intermediate between the abrasive grains A1 and A2, and abrasive grains A4 having an average particle diameter smaller than that of the abrasive grains A2 are generated. The abrasive A and the object to be polished are sucked together with air by the suction fan 70, and flow into the cyclone 40 via the downstream flow path 31. In the cyclone 40, the abrasive grains A1 to A3 are separated from the abrasive grains A4 and the object to be polished.

[0056] The abrasive grains A1 to A3 separated by the cyclone 40 flow into the first classifying section 41. The first classifying section 41 is installed at a predetermined angle with respect to the horizontal plane. The first classifying section 41 has a mesh member with a predetermined mesh size, and the abrasive grains A2 that pass through the mesh member are stored in the second storage section 411. The abrasive grains A1 and A3 that cannot pass through the mesh member roll under their own weight from the upper surface of the mesh member, which is installed at an angle, and flow into the second classifying section 42.

[0057] The abrasive grains A1 and A3 classified in the first classifying section 41 flow into the second classifying section 42. The second classifying section 42 is installed at a predetermined angle with respect to the horizontal plane. The second classifying section 42 has a mesh member, and the abrasive grains A3 that pass through the mesh member are stored in the third storage section 43 and then discarded. The abrasive grains A1 that cannot pass through the mesh member roll under their own weight from the upper surface of the mesh member, which is installed at an angle, and are stored in the first storage section 421.

[0058] The abrasive grains A1 stored in the first storage section 421 and the abrasive grains A2 stored in the second storage section 411 are supplied to the mixer 10 at a predetermined supply amount by the first supply section 421a and the second supply section 411a, respectively. For example, the ratio of the abrasive grains A1 to the total amount of the abrasive grains A1 and A2 is adjusted to 5 to 15% by weight and supplied to the mixer 10. As a result, the polishing material A circulates in the denitration catalyst polishing device 1. The abrasive grains A4 and the object to be polished separated in the cyclone 40 are sucked by the suction fan 70, and flow into the bag filter 60 through the conveying pipe 44 and are collected. The air after the object to be polished is collected is discharged to the outside through the exhaust duct 71. The operation of the denitration catalyst polishing device 1 is continued for a predetermined time, the inner surface of the through hole C1 of the denitration catalyst C is polished, and the deposits and the like attached to the inner surface of the through hole C1 are removed to regenerate the denitration catalyst C.

[0059] The method for polishing and regenerating the denitration catalyst C according to this embodiment includes a step of replenishing the abrasive A. When the denitration catalyst C is polished for a predetermined time, the abrasive A cracks or chips, generating abrasive grains A3 and A4, which are discarded, and the amount of the abrasive A circulating in the device decreases. For this reason, the abrasive A is replenished by the step of replenishing the abrasive A. The replenishing step can be performed by replenishing the abrasive A from the upstream side of the first classification section 41 while the denitration catalyst polishing device 1 is stopped or while the denitration catalyst C is being polished. Note that the amount of reduction due to cracks or chips of the abrasive grains A1 is greater than that of the abrasive grains A2, so that the mass ratio of the abrasive grains A1 in the replenishing abrasive A is preferably greater than 5 to 15 mass%, which is the preferred mass ratio of the abrasive grains A1 when used to polish the denitration catalyst C.

[0060] The abrasive A replenished in the replenishing step is classified by the first classifying section 41 and the second classifying section 42, and the abrasive grains A1 and A2 are adjusted to a predetermined supply amount by the first supply section 421a and the second supply section 411a and supplied to the mixing section 10. Therefore, the abrasive A can be simply replenished without the need to strictly measure the mass ratio of the abrasive grains A1 and A2 in the replenishing step.

[0061] The present invention is not limited to the above-described embodiment, and can be modified as appropriate.

[0062] The denitration catalyst polishing apparatus 1 according to the above embodiment has been described as having only the first classifying section 41 and the second classifying section 42 as the classifying section. However, this is not limited to the above. As the classifying section, in addition to the above, a classifying section that removes foreign matter having a particle size larger than the first abrasive grains A1 may be provided after the second classifying section 42. Furthermore, the cyclone 40 may be configured to include the functions of the first classifying section 41 and the second classifying section 42. [Explanation of symbols]

[0063] 1 Denitration catalyst polishing equipment 10 Mixing section 41 1st Classification Division 42 2nd Classification Division 421 First Storage Section 421a 1st supply section 411 Second Storage Section 411a 2nd supply section 70 Suction fan (suction section) C Denitrification catalyst C1 through hole A Abrasive material A1 First Abrasive A2 Second Abrasive A3 The third abrasive grain

Claims

1. A denitration catalyst polishing apparatus for polishing an inner surface of a denitration catalyst having a plurality of through holes extending in a longitudinal direction, the apparatus comprising: a mixing section disposed upstream of the denitration catalyst and configured to mix the abrasive with air; a suction section that is disposed downstream of the denitration catalyst and that sucks the abrasive together with air; a first classification unit and a second classification unit for classifying the abrasive after polishing the denitration catalyst; the abrasive supplied to the mixing section includes the second abrasive grains classified in the first classification section and the first abrasive grains classified in the second classification section, The first abrasive grains have an average particle diameter D1 of 1.65 to 2.16 mm, and the second abrasive grains have an average particle diameter D2 of 0.30 to 0.45 mm.

2. The first classifying unit classifies the second abrasive grains, and the first abrasive grains and third abrasive grains having a grain size larger than that of the second abrasive grains, The second classifying unit classifies the first abrasive grains and the third abrasive grains having a grain size smaller than that of the first abrasive grains, 2. The apparatus for polishing a denitration catalyst according to claim 1, wherein the polishing material consisting of the first abrasive grains and the second abrasive grains is supplied to the mixing section.

3. a first storage section for storing the first abrasive grains and a second storage section for storing the second abrasive grains; the first storage section has a first supply section capable of adjusting a supply amount of the first abrasive grains to the mixing section, 3. The apparatus for polishing a denitration catalyst according to claim 1, wherein the second storage section has a second supply section capable of adjusting an amount of the second abrasive grains supplied to the mixing section.

4. 4. The apparatus for polishing a denitration catalyst according to claim 1, wherein the first abrasive grains are contained in the abrasive supplied to the mixing section in an amount of 5 to 15% by weight.

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