Flue gas denitration device and method

Abstract

The invention discloses a flue gas denitration device and method, the device is suitable for an SCR flue gas denitration process of ultralow-temperature flue gas, and the device comprises a plurality of catalyst modules which are fixedly arranged on the cross section of a flue in rows and columns and used for adsorbing NOx in the ultralow-temperature flue gas and NH3 in ammonia-air mixed gas in a non-heating state, nOx and NH3 are subjected to a denitration reaction when the flue gas is heated to the temperature of a flue gas denitration window; the catalyst adopts a heat storage material as a matrix; the heat medium heating assembly is arranged above the catalyst module in the flue; the heat medium heating assembly comprises a horizontally moving injection unit which is used for carrying out regional injection heating on each catalyst module row by row or column by column, and after the heated region finishes denitration reaction and the catalyst is regenerated, the injection unit is moved to the next region for heating. According to the invention, the catalyst module can be gradually heated in different areas, so that the area of the catalyst module is rapidly heated to the temperature of a flue gas denitration window, and the catalyst regeneration process is rapidly completed.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas denitrification, and particularly to a device and method for ultra-low temperature flue gas denitrification. Background Technique

[0002] Nitrogen Oxides are one of the main gaseous pollutants in the atmosphere. Nitrogen oxides NOx not only endanger human health, but also are important substances that damage the environment, form acid rain and photochemical smog. The main sources of NOx are the combustion of fossil fuels, including coal-fired power plants, industrial boilers, vehicle exhaust, etc. At present, the emission standards of NOx are constantly improving. Commonly used flue gas denitrification technologies mainly include selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR), ozone oxidation absorption method, etc. Among them, the most widely used is SCR. The process principle of SCR is: injecting an amino reducing agent into the flue gas containing NOx, and under the action of a catalyst, NH3 and NOx undergo a catalytic reduction reaction, and the reaction products are N2 and H2O. The reaction temperature of the traditional SCR process is 300 - 450 °C. Within this temperature range, the catalyst has the highest activity and the longest service life.

[0003] Since the flue gas generally contains SO2, SO3, O2 and water vapor, when ammonia is in excess in the reaction zone (ammonia slip), it will react with SO3 to form ammonium salts. The formed ammonium salt (NH4HSO4) is in a liquid state at a temperature of 180 - 240 °C and has viscosity. It will adsorb on the surface of the catalyst, reducing the catalyst activity. At the same time, it will also adhere to the heat exchange tubes of the economizer, a downstream device of the SCR denitrification reactor, bonding the dust in the flue gas, causing fouling, blockage and corrosion of the heat exchange tube layer, and affecting the operation cycle of the device. The deposition of NH4HSO4 is an important bottleneck restricting the application of SCR denitrification under low temperature conditions.

[0004] In the prior art, most methods use heating the flue gas to raise the flue gas temperature to reach the denitrification reaction temperature window, so a heat exchanger needs to be set. However, for ultra-low temperature flue gas, if the flue gas is heated to raise its temperature for a conventional SCR reaction, the equipment will be very large, and too much energy will be consumed during the flue gas heating process.

[0005] In the prior art, there is also a method of using a microwave source to heat a catalyst to complete flue gas denitrification. For example, Chinese Patent Application CN105727745A discloses a microwave reaction system device for SCR denitrification, which includes a reactor main body, a gas distributor, a device insulation layer, a microwave generating device, a temperature measuring unit, a catalyst module, an ammonia injection system device, etc. The temperature of the catalyst itself can be achieved by adjusting the input power of the microwave generator. The reaction system and device involved in this solution have the advantages of wide application range, energy conservation and environmental protection, simple operation, etc., and have good economic efficiency and potential industrial application value. However, the microwave source of this type of solution is arranged on the outer wall of the reactor main body and is statically set, and the denitrification effect on ultra-low temperature flue gas is poor. Even if the number of microwave sources is increased to cover the microwave radiation range in the reactor, the flue gas denitrification window temperature required in the flue can be satisfied, but the microwave energy consumption will increase greatly.

[0006] Therefore, there is an urgent need for a flue gas denitrification device and method that can rapidly heat the catalyst module in a divided area so that it can still quickly reach the flue gas denitrification window temperature when facing ultra-low temperature flue gas, and the energy consumption can be significantly reduced.

[0007] The information disclosed in this background art section is only intended to increase the understanding of the overall background of the present invention, and should not be regarded as an admission or any form of suggestion that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0008] The object of the present invention is to provide a flue gas denitrification device and method, which are particularly suitable for the SCR denitrification process of ultra-low temperature flue gas. Through the modular design of the catalyst, the selection of heat storage materials for the catalyst matrix, and the built-in and movable heat medium heating source, the catalyst module can be gradually heated in a divided area, so as to rapidly raise the temperature of the catalyst module in the area to the flue gas denitrification window temperature and quickly complete the catalyst regeneration process.

[0009] To achieve the above object, according to the first aspect of the present invention, the present invention provides a flue gas denitrification device, which is suitable for the SCR flue gas denitrification process of ultra-low temperature flue gas, and includes: a catalyst module, the number of which is multiple and is fixedly arranged in rows and columns on the cross-section of the flue, and is used for adsorbing NO in the ultra-low temperature flue gas x and NH3 in the ammonia-air mixture, and causing NO x to react with NH3 for denitrification when heated to the flue gas denitrification window temperature; the catalyst uses a heat storage material as the matrix; a heat medium heating component, which is arranged above the catalyst module in the flue; the heat medium heating component includes a horizontally movable injection unit, which is used for injecting and heating each catalyst module in a divided area row by row or column by column. When the denitrification reaction is completed in the heated area and the catalyst is regenerated, the injection unit moves to the next area for heating.

[0010] Further, in the above technical solution, the heat medium heating assembly may further include: a sealed housing, which is a hollow cavity for accommodating the injection unit and restricting the injection coverage area within the area of the sealed housing. The width of the sealed housing is adapted to the width of the catalyst module.

[0011] Further, in the above technical solution, the injection unit may further include: an injection main pipe, which is a hollow pipe and is connected to the heat medium; the injection main pipe also serves as the driving rod of the injection unit for connecting to a controller outside the flue and driving the entire heat medium heating assembly to move; injection branch pipes, which are communicated with the injection main pipe and are provided with nozzles on the branch pipes for injecting the heat medium to corresponding positions of the catalyst module.

[0012] Further, in the above technical solution, according to the first embodiment of the injection unit, the injection branch pipes may be vertically arranged relative to the injection main pipe, the nozzles extend vertically downward along the injection branch pipes, and a plurality of nozzles are evenly spaced and the injection coverage area corresponds to the size of the catalyst module.

[0013] Further, in the above technical solution, rollers may be provided on the side wall of the sealed housing, and the rollers can roll along a slide rail fixed in the flue to enable the entire heat medium heating assembly to move horizontally.

[0014] Further, in the above technical solution, the catalyst module may include: a wire mesh, which is a cuboid structure enclosed by side walls and a bottom, and hollow columns are provided at four edges of the cuboid; openings are provided on the inner wall surfaces of the hollow columns at different heights; a catalyst, which is in a honeycomb shape or granular shape and is filled in the cuboid structure.

[0015] Further, in the above technical solution, the matrix of the catalyst may be made of a ceramic material; the active components of the catalyst are immersed into the matrix pores.

[0016] Further, in the above technical solution, according to the second embodiment of the injection unit, the nozzles may also be arranged at the ends of the injection branch pipes and the arrangement positions correspond to the hollow columns, and the heat medium ejected from the nozzles directly enters the hollow columns and is introduced into the catalyst module through the openings on the columns.

[0017] Further, in the above technical solution, the openings may be arranged in layers, and preferably three openings are arranged in each layer and are evenly spaced.

[0018] Further, in the above technical solution, the horizontal movement of the injection unit is preferably a reciprocating movement in the cross-section of the flue.

[0019] To achieve the above object, according to the second aspect of the present invention, the present invention provides a flue gas denitrification method, which uses the device of any one of the foregoing, and includes the following steps: A. Mix the ultra-low temperature flue gas with the ammonia-air mixture in the flue; B. When the mixed gas flows through the catalyst module, NO x and NH3 in the mixed gas are adsorbed on the substrate of the catalyst; C. Drive the heat medium heating assembly to reciprocate horizontally in the flue, so that the ejected heat medium gradually covers each row or column of catalyst modules, and stays above each catalyst module for the same preset time. Through the heat storage of the catalyst substrate, the heating of the catalyst module, the denitrification reaction of NO x and NH3 and the catalyst regeneration are completed within the preset time.

[0020] Further, in the above technical solution, the heat medium gradually covering can be specifically: directly spraying the heat medium onto the top of the corresponding catalyst module, or spraying the heat medium into the hollow column of the corresponding catalyst module and then introducing it into the catalyst module through the openings on the column.

[0021] Further, in the above technical solution, the temperature of the ultra-low temperature flue gas refers to the flue gas at 50-120°C.

[0022] Further, in the above technical solution, the catalyst substrate filled in the catalyst module can be made of ceramic material; the catalyst active components can be oxides of V, oxides of Ti, oxides of W, and oxides of Mo. The active components are calculated as oxides, and the mass ratio is as follows: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

[0023] Further, in the above technical solution, the preset time in step C can be 8s-10s; the heating temperature of the catalyst module can be controlled at 200-450°C.

[0024] Further, in the above technical solution, one or more layers can be provided in the height direction of the catalyst module. One or more layers of catalyst modules form a catalyst bed layer, and multiple catalyst bed layers can be provided in the flue.

[0025] Further, in the above technical solution, the temperature of the catalyst bed layer can be adjusted according to the flue gas composition: when the SO2 content in the flue gas is low, the temperature of the catalyst bed layer can be controlled below 300°C; when the SO2 content in the flue gas is high, the temperature of the catalyst bed layer can be controlled between 320-450°C.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1) The present invention adopts a modular filling arrangement for the denitration catalyst and heats the catalyst module until the denitration reaction temperature window is reached. Since the built-in heat medium heating method is used and each module of the catalyst is heated section by section in different regions, the regional heating speed is fast and the time is short, having the advantages of simple process, low energy consumption, wide application range, etc.;

[0028] 2) The present invention is particularly applicable to the SCR flue gas denitration process for ultra-low temperature flue gas. Here, the ultra-low temperature flue gas refers to the flue gas with a temperature of 50 - 120 °C. Experiments have proved that the device has a better denitration treatment effect on the flue gas with a temperature of 50 - 60 °C; the device and method of the present invention can also be applicable to flue gas with a higher temperature and are applicable to the flue gas with a temperature of 50 °C - 450 °C to achieve the required denitration effect;

[0029] 3) The present invention only needs to heat the catalyst, and the energy consumption is greatly reduced compared with heating the flue gas; through the modular design of the catalyst and the movable heat medium heating component, row-by-row or column-by-column heating of the module can be realized. With a smaller number of injection units, each module can be centrally heated, and the injection range is more concentrated, which can effectively shorten the regional heating time. The heated module can reach the denitration window temperature in a shorter time, enabling NO x to react with NH3 for denitration. The reacted gas quickly escapes and moves downward, thereby simultaneously completing the regeneration of the catalyst in this module;

[0030] 4) For other catalyst modules other than the heated catalyst module in the present invention, the adsorption of NO x and NH3 in the flue gas can be carried out simultaneously. When the heat medium heating component moves to this area, the processes of heating - denitration reaction - catalyst regeneration are carried out; the horizontal reciprocating movement of the heat medium heating component can realize the complete process of adsorption - heating - reaction - regeneration for each catalyst module periodically;

[0031] 5) By the way that the heat medium is evenly sprayed on the top of the catalyst module in the present invention, the heat medium can gradually penetrate downward for heat transfer. And since the catalyst matrix adopts a heat storage material, the overall heated catalyst module can obtain the required denitration window temperature in a shorter time, so that the denitration reaction and catalyst regeneration can be quickly completed during the heating process of this module; due to the heat storage function of the catalyst matrix, within a period of time after the injection unit is removed, this module can still continue to carry out the denitration reaction and catalyst regeneration;

[0032] 6) By injecting the heat medium from the side parts at different heights of the catalyst module, the heat medium can quickly penetrate into the module for heat transfer, with a shorter penetration distance. Since the catalyst matrix uses a heat storage material, the overall heated catalyst module can obtain the required denitration window temperature in a shorter time. And due to the heat storage function of the catalyst matrix, the module can still continue the denitration reaction and catalyst regeneration for a period of time after the injection unit is removed.

[0033] 7) Through the structural arrangement of the heat medium heating component, when it moves above a certain catalyst module, a closed space can be formed, and the flue gas cannot flow through here. After the denitration reaction is completed, the catalyst module can be regenerated. The heat medium heating component continues to move above the adjacent catalyst module to regenerate the catalyst one by one, with a more sufficient denitration reaction and a higher catalyst regeneration efficiency.

[0034] 8) The present invention can control the movement process of the heat medium heating component by measuring the temperature in the catalyst module area in real time, that is, the heat medium heating component can control the residence time on each module according to the heating temperature requirement and the flue gas composition. The catalyst bed temperature can be adjusted according to the flue gas composition: when the SO2 content in the flue gas is low, the catalyst bed temperature is controlled below 300°C; when the SO2 content in the flue gas is high, the catalyst bed temperature is controlled between 320 - 450°C (ammonium salts generated at this temperature can decompose to ensure the catalyst activity). Therefore, the present invention has no limitation on the flue gas composition.

[0035] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and be able to implement it according to the content of the specification, and at the same time to make the above and other objects, technical features and advantages of the present invention more understandable, one or more preferred embodiments are listed below and described in detail with the accompanying drawings as follows. Brief Description of the Drawings

[0036] Figure 1 is the layout schematic diagram of the flue gas denitration device of the present invention in the flue.

[0037] Figure 2 is the schematic diagram of the first embodiment of the flue gas denitration device of the present invention in the flue (where Figure 2-A is the top view schematic diagram; Figure 2-B is the side view schematic diagram).

[0038] Figure 3 is the structural schematic diagram of the first embodiment of the heat medium heating component in the flue gas denitration device of the present invention (where Figure 3-A is the internal structure cross-sectional view schematic diagram; Figure 3-B is Figure 3-A the side view of Figure 3-C ; Figure 3-A is the top view of

[0039] Figure 4 It is a schematic three - dimensional structure diagram of the first embodiment of the heat - medium heating component in the flue gas denitration device of the present invention.

[0040] Figure 5 is a schematic diagram of the second embodiment of the flue gas denitration device of the present invention in the flue (where Figure 5-A is a top - view schematic diagram; Figure 5-B is a side - view schematic diagram).

[0041] Figure 6 It is a top - view schematic diagram of the catalyst module in the flue gas denitration device of the present invention.

[0042] Figure 7 It is a schematic three - dimensional structure diagram of the catalyst module in the flue gas denitration device of the present invention (in the state without filling the catalyst).

[0043] Figure 8 is a schematic structure diagram of the second embodiment of the heat - medium heating component in the flue gas denitration device of the present invention (where Figure 8-A is a schematic cross - sectional view of the internal structure; Figure 8-B is Figure 8-A the side - view of; Figure 8-C is Figure 8-A the top - view of).

[0044] Figure 9 It is a schematic three - dimensional structure diagram of the second embodiment of the heat - medium heating component in the flue gas denitration device of the present invention.

[0045] Main reference numerals description:

[0046] 1 - catalyst module, 11 - wire mesh, 12 - solid catalyst, 13 - hollow column, 131 - opening, 2 - heat - medium heating component, 21 - sealed housing, 22 - injection main pipe, 23 - injection branch pipe, 24 - nozzle, 25 - roller, 3 - ammonia injection element, 4 - ammonia mixing element, 100 - flue, 101 - slide rail. Specific embodiments

[0047] The following combines the accompanying drawings to describe the specific embodiments of the present invention in detail, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0048] Unless otherwise clearly stated, in the whole specification and claims, the term "comprise" or its variations such as "comprising" or "including" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0049] In this document, for convenience of description, spatial relative terms such as "below", "beneath", "lower", "above", "upper", etc. may be used to describe the relationship of one element or feature to another element or feature in the drawings. It should be understood that spatial relative terms are intended to encompass different orientations of the object in use or operation in addition to the orientation depicted in the figures. For example, if the object in the figure is flipped, an element described as "below" or "beneath" another element or feature will be oriented "above" the element or feature. Thus, the exemplary term "below" can encompass both the directions of below and above. The object may also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0050] In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, and are not used to define a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. may also be interchanged with each other.

[0051] The technical concept of the present invention is to modularize the filling of the denitration catalyst and heat the catalyst module until the denitration reaction temperature window is reached. Since heat medium (such as water vapor) injection heating is adopted and each catalyst module is heated section by section in different regions, the regional heating speed is fast and the time is short, and it has the advantages of simple process, low energy consumption, wide application range, etc.

[0052] As Figure 1 shown in FIG. 2, the present invention provides a flue gas denitration device, which is particularly suitable for the SCR flue gas denitration process of ultra-low temperature flue gas. The ultra-low temperature flue gas of the present invention refers to flue gas with a temperature of 50 - 120°C, and the device has a better denitration treatment effect on flue gas with a temperature of 50 - 60°C. The device is arranged in the flue 100. An ammonia injection element 3 and an ammonia mixing element 4 are provided upstream of the flue gas at the location of the device. The ammonia-air mixture enters the ammonia injection element 3 radially from the flue 100 and is ejected in the same direction as the flue gas. The ejected ammonia-air mixture is mixed with the flue gas in the ammonia mixing element 4, and the mixture enters the flue gas denitration device of the present invention. The device at least includes a catalyst module 1 and a heat medium heating assembly 2. Among them, the number of catalyst modules 1 is multiple and they are fixedly arranged in rows and columns on the cross-section of the flue 100 (covering the entire cross-section of the flue), and are used to adsorb NO in the ultra-low temperature flue gas in the non-heated state x and NH3 in the ammonia-air mixture, and make NO when heated to the flue gas denitration window temperature xIt undergoes a denitration reaction with NH3. The catalyst uses a heat storage material as the substrate (preferably ceramics, etc.). The heat medium heating assembly 2 is arranged in the flue 100 and above the catalyst module 1. The heat medium heating assembly 2 includes a horizontally movable injection unit (refer to FIGS. 3, 4, 8, and 9), which is used to heat each catalyst module 1 in a sub-region row by row or column by column. After the denitration reaction is completed in the heated region and the catalyst is regenerated, the injection unit moves to the next region for heating.

[0053] The device of the present invention adopts the above technical solution. Through the modular design of the catalyst and the heating of each row or column of the module by the movable heat medium heating assembly, a small number of injection units can be used to centrally heat each module, and the injection range is more concentrated, which can effectively shorten the regional heating time. Moreover, since the substrate of the catalyst is made of a heat storage material, the heated module can reach the denitration window temperature in a short time. Therefore, the module can make NO adsorbed on the catalyst substrate x undergo a denitration reaction with NH3 in a short time, and the reacted gas (generating N2 and H2O) rapidly escapes and moves downward, thereby simultaneously completing the regeneration of the catalyst of this module; in the regions outside the heated catalyst module (i.e., other catalyst modules), the adsorption of NO in the flue gas x with NH3 is carried out simultaneously, and the process of heating - denitration reaction - catalyst regeneration is awaited when the heat medium heating assembly moves to this region. The horizontal movement of the heat medium heating assembly is preferably a reciprocating movement on the cross-section of the flue, which can realize the complete process of adsorption - heating - reaction - regeneration of each catalyst module periodically.

[0054] Further, as shown in FIGS. 3, 4, 8, and 9, the heat medium heating assembly 2 may include a sealed housing 21 and the aforementioned injection unit. The sealed housing 21 is a hollow cavity for accommodating the injection unit and restricting the injection coverage area within the sealed housing 21. The width of the sealed housing may be adapted to the width of the catalyst module (preferably the same setting for row-by-row or column-by-column full coverage of the module). The number of injection units may be selected according to the diameter of the flue 100, the size of the catalyst module, the temperature of the flue gas to be denitrified, etc. The injection unit may further include an injection main pipe 22 and injection branch pipes 23. The injection main pipe 22 is a hollow pipe through which the heat medium passes. The injection main pipe 22 can also serve as the driving rod of the injection unit for connecting to a controller outside the flue (not shown in the figure) and driving the overall movement of the heat medium heating assembly 2. A temperature sensor (not shown in the figure) may be provided in the bed where the catalyst module 1 is located to control the injection main pipe 22 serving as the driving rod in real time by measuring the temperature in the catalyst module area in real time, and further drive the heat medium heating assembly 2 to control the residence time on each module according to the heating temperature requirement and the flue gas composition. The injection branch pipes 23 are connected to the injection main pipe 22 and nozzles 24 are provided on the branch pipes for injecting the heat medium to corresponding positions of the catalyst module 1.

[0055] Further referring to FIGS. 3 and Figure 4 , in the first embodiment of the injection unit, the injection branch pipes 23 are perpendicularly arranged relative to the injection main pipe 22, and the nozzles 24 extend vertically downward along the injection branch pipes 23. A plurality of nozzles 24 are evenly spaced and the injection coverage area corresponds to the size of the catalyst module (i.e., in the first embodiment, the heat medium is directly sprayed onto the top of the catalyst module to be heated). Through such a setting, the heat medium can be evenly sprayed onto the top of the catalyst module 1 and gradually penetrate downward for heat transfer. Since the catalyst matrix uses a heat storage material, the overall heated catalyst module can obtain the required denitrification window temperature in a relatively short time, so that the denitrification reaction and catalyst regeneration can be quickly completed during the heating process of the module; and due to the heat storage function of the catalyst matrix, the module can still continue to carry out the denitrification reaction and catalyst regeneration for a period of time after the injection unit is removed.

[0056] Further, as shown in FIGS. 8 and 9, in the second embodiment of the injection unit, the injection branch pipes 23 can be extended by means of elbows, and the nozzles 24 are provided at the ends of the injection branch pipes 23, and the setting positions of the nozzles 24 correspond to the hollow columns 13 at the four edges of the catalyst module 1 (that is, one catalyst module corresponds to four nozzles 24). Through such a setting, the heat medium ejected from the nozzles 24 directly enters the hollow columns 13 and is introduced into the catalyst module 1 through the openings 131 on the columns (refer to Figure 6 、 Figure 7)。With such a setting method, the heat medium can be sprayed into the side parts of different heights of the catalyst module 1 and quickly penetrate into the module for heat transfer (the penetration distance is shorter). Moreover, since the catalyst matrix uses a heat storage material, the overall heated catalyst module can obtain the required denitration window temperature in a shorter time (compared with the first embodiment), so that the denitration reaction and catalyst regeneration can be quickly completed during the heating process of the module. And due to the heat storage function of the catalyst matrix, within a certain period of time after the spraying unit is removed, the module can still continue to carry out the denitration reaction and catalyst regeneration.

[0057] Further, as shown in FIGS. 3 and 8, in order to realize the horizontal reciprocating movement of the heat medium heating assembly 2, the present invention adopts a combination of rollers and slide rails, that is, rollers 25 are provided on the side wall of the sealed housing 21, and the rollers 25 roll along the slide rails 101 fixed in the flue 100, so that the whole heat medium heating assembly 2 can realize horizontal reciprocating movement.

[0058] Further, as shown in FIGS. 2 and 5, for the arrangement of the heat medium heating assembly 2, in the first embodiment shown in FIG. 2, two heat medium heating assemblies 2 are provided, and each heat medium heating assembly covers four rows of catalyst modules. In the second embodiment shown in FIG. 5, four heat medium heating assemblies 2 are provided, and each heat medium heating assembly covers two rows of catalyst modules, which can be selected according to needs in the present invention. Through the above structural setting, when the heat medium heating assembly 2 moves to the upper part of a certain catalyst module 1, a closed space can be formed, and the flue gas cannot flow through here. After the denitration reaction is completed, the catalyst module can be regenerated. The heat medium heating assembly 2 continues to move to the upper part of the adjacent catalyst module 1 to regenerate the catalyst one by one.

[0059] Further as Figure 6 、 7 shown, preferably but not limitedly, the catalyst module 1 may include a wire mesh 11 and a solid catalyst 12. Among them, the wire mesh 11 is a cuboid structure enclosed by side walls and a bottom (no wire mesh is provided at the top), and hollow columns 13 are provided at four edges of the cuboid. Openings 131 are provided on the inner wall surfaces of the hollow columns 13 at different heights. The openings 131 are preferably arranged in layers, Figure 7 and three are arranged in each layer and evenly spaced. The catalyst 12 can be in a honeycomb shape or granular and filled in a cubic structure. The matrix of the catalyst can be made of a heat storage material with an adsorption function (for adsorbing NO x and NH3); the active component of the catalyst is immersed in the matrix pores.

[0060] The present invention also provides a flue gas denitration method, which uses the aforementioned device and includes the following steps:

[0061] Step S101, mix ultra-low temperature flue gas with ammonia-air mixture in the flue (the temperature of the ultra-low temperature flue gas can be 50 - 120°C);

[0062] Step S102, when the mixed gas flows through catalyst module 1, NO in the mixed gas x and NH3 are adsorbed on the substrate of the catalyst. Specifically, the catalyst substrate filled in catalyst module 1 can be made of heat storage materials such as ceramics; the catalyst active components can be oxides of V, oxides of Ti, oxides of W, and oxides of Mo. Calculated as oxides, the mass ratios are as follows: V is 0.01wt%, Ti is 99wt%, W is 0.1wt%, and Mo is 0.02wt%.

[0063] Step S103, drive the heat medium heating component 2 to reciprocate horizontally in the flue 100, so that the ejected heat medium gradually covers each row or column of catalyst modules 1, and stays at the top of each catalyst module 1 for the same preset time (preferably 8s - 10s). Through the heat storage of the catalyst substrate, the heating of the catalyst module, the denitration reaction of NO x and NH3, and the regeneration of the catalyst are completed within this preset time. The heated temperature of the catalyst module can be controlled at 200 - 450°C.

[0064] Further, preferably but not restrictively, when the heat medium gradually covers each row or column of catalyst modules 1, the heat medium can be directly sprayed onto the top of the corresponding catalyst module 1, or the heat medium can be sprayed into the hollow column 13 of the corresponding catalyst module 1 and then introduced into the catalyst module 1 through the openings 131 on the column.

[0065] Further, preferably but not restrictively, catalyst module 1 can be arranged in multiple layers in the height direction. Multiple layers of catalyst modules can form a catalyst bed, and multiple catalyst beds can be arranged in the flue according to process requirements. The temperature of the catalyst bed can be adjusted according to the flue gas composition: when the SO2 content in the flue gas is low, the temperature of the catalyst bed is controlled below 300°C; when the SO2 content in the flue gas is high, the temperature of the catalyst bed is controlled between 320 - 450°C.

[0066] The following is a detailed description with two specific embodiments:

[0067] Example 1

[0068] Flue gas to be treated: The flue gas volume is 55,000 Nm 3 / h, the temperature is 60°C, the pressure is 10 kPa, and the NO x concentration is 600 mg / Nm 3 , the SO2 concentration is 100 mg / Nm 3 , the SO3 concentration is 10 mg / Nm3 , the dust content is 200 mg / Nm 3 .

[0069] NO x The emission standard is 100 mg / Nm 3 . The flow rate of the ammonia-air mixture is 800 Nm 3 / h, and the volume fraction of ammonia gas is 3%. The flue gas cross-section is 1240×2480 mm

[0070] In this embodiment, the catalyst uses a honeycomb denitration catalyst, the matrix uses honeycomb ceramics, and the active components of the catalyst are oxides of V, oxides of Ti, oxides of W, and oxides of Mo. Calculated as oxides, the mass ratio is as follows: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%. The catalyst is provided with a total of one layer, which is composed of catalyst modules of 150 mm×150 mm. The height of the catalyst module is 700 mm, and the number is 128

[0071] The ammonia-air mixture is injected into the flue by an ammonia injection element, and after mixing with the flue gas at 60°C through a ammonia mixing element, it enters the SCR flue gas denitration device of the present invention. A total of 2 heat medium heating components are provided. The injection unit is provided with 36 nozzles. Medium-pressure steam is used as the heat medium to heat the catalyst module, and the temperature of the heated catalyst module is controlled at 250°C. The injection unit stays above the catalyst module for 10 s and then moves to the adjacent catalyst module. The heat medium heating components circulate to heat each catalyst module

[0072] After experimental verification, after the catalyst module is regenerated, the content of NO in the purified flue gas discharged x is less than 50 mg / Nm 3 , meeting the emission requirements

[0073] Example 2

[0074] Flue gas to be treated: The flue gas volume is 35,000 Nm 3 / h, the temperature is 120°C, the pressure is 10 kPa, NO x concentration is 200 mg / Nm 3 , the SO2 concentration is 1000 mg / Nm 3 , the SO3 concentration is 20 mg / Nm 3 , the dust content is 200 mg / Nm 3 .

[0075] NO x The emission standard is 50 mg / Nm 3 . The flow rate of the ammonia-air mixture is 170 Nm 3 / h, where the volume fraction of ammonia gas is 3%. The flue gas cross-section is 1240×2480 mm.

[0076] In this embodiment, the catalyst used is a granular denitration catalyst, and the matrix is made of regenerative ceramic balls. The active components of the catalyst particles are oxides of V, oxides of Ti, oxides of W, and oxides of Mo. Calculated as oxides, the mass ratios are as follows: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%. The catalyst is spherical, with a particle size of 5 mm; the bulk density is 0.68 g / cm 3 , and the specific surface area is 80 m 2 / g, and the pore volume is 0.57 cm 3 / g. The catalyst module consists of a metal mesh, catalyst particles, and hollow risers. Among them, each hollow riser has 24 holes with a diameter of 3 mm, and the bottom of the hollow riser is blocked. The cross-sectional size of the catalyst module is 150 mm×150 mm, the module height is 400 mm, and a total of one layer is set, with a quantity of 128.

[0077] The ammonia-air mixture is injected into the flue by the ammonia injection element, and after being mixed with the flue gas at 120°C through the ammonia mixing element, it enters the SCR flue gas denitration device of the present invention. A total of 4 heat medium heating components are set, and the injection unit is provided with 8 nozzles. The positions of the nozzles correspond to the hollow risers of the catalyst module. Medium-pressure steam is used as the heat medium to heat the catalyst module, and the temperature of the heated catalyst module is controlled at 350°C. When the injection unit moves above the catalyst module, the nozzles are docked with the hollow risers of the catalyst module, and the steam enters the risers and is sprayed from the openings of the risers onto the catalyst particles to regenerate them. After the injection unit stays for 10 s, it moves to the adjacent catalyst module. The heat medium heating components cycle to heat each catalyst module.

[0078] After experimental verification, after the regeneration of the catalyst module, the content of NO x in the discharged purified flue gas is less than 50 mg / Nm 3 , meeting the emission requirements.

[0079] The foregoing description of the specific exemplary embodiments of the present invention is for the purposes of illustration and exemplification. These descriptions are not intended to limit the present invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the present invention, as well as various different selections and changes. Any simple modifications, equivalent variations, and embellishments made to the above exemplary embodiments shall fall within the protection scope of the present invention.

Claims

1. A flue gas denitration device, characterized in that, The SCR flue gas denitrification process applicable to ultra-low temperature flue gas includes: A catalyst module, with a plurality of them arranged in rows and columns and fixedly arranged on the cross-section of the flue, is used to adsorb NO in the ultra-low temperature flue gas in a non-heated state x and NH3 in the ammonia-air mixture, and when heated to the flue gas denitration window temperature, make NO x react with NH3 to carry out denitration reaction; the catalyst uses a heat storage material as the matrix; A heat medium heating component, which is arranged above the catalyst module in the flue; the heat medium heating component includes a horizontally moving injection unit for injecting and heating each catalyst module in sub-regions row by row or column by column. After the denitrification reaction is completed in the heated region and the catalyst is regenerated, the injection unit moves to the next region for heating.

2. The flue gas denitration device according to claim 1, wherein The heat medium heating component further includes: A sealed housing, which is a hollow cavity for accommodating the injection unit and restricting the injection coverage within the area of the sealed housing. The width of the sealed housing is adapted to the width of the catalyst module.

3. The flue gas denitration device according to claim 1, wherein The injection unit further includes: An injection main pipe, which is a hollow pipe through which the heat medium passes; the injection main pipe also serves as the driving rod of the injection unit for connecting to a controller outside the flue and driving the overall movement of the heat medium heating component. Injection branch pipes, which are connected to the injection main pipe and are provided with nozzles on the branch pipes for injecting the heat medium to corresponding positions of the catalyst module.

4. The flue gas denitration device according to claim 3, characterized in that The injection branch pipes are vertically arranged relative to the injection main pipe, the nozzles extend vertically downward along the injection branch pipes, and a plurality of nozzles are arranged at uniform intervals and the injection coverage area corresponds to the size of the catalyst module.

5. The flue gas denitration device according to claim 2, characterized in that, Rollers are provided on the side wall of the sealed housing, and the rollers roll along a slide rail fixed in the flue to enable the overall horizontal movement of the heat medium heating component.

6. The flue gas denitrification device according to claim 3, wherein The catalyst module includes: A metal wire mesh, which is a cuboid structure enclosed by side walls and a bottom, and hollow columns are provided at four edges of the cuboid; openings are provided on the inner wall surfaces of the hollow columns at different heights. A catalyst, which is in a honeycomb or granular shape and is filled in the cuboid structure.

7. The flue gas denitration device according to claim 6, characterized in that, The matrix of the catalyst is made of a ceramic material; the active components of the catalyst are immersed into the matrix pores.

8. The flue gas denitrification device according to claim 6, characterized in that, The nozzles are arranged at the ends of the injection branch pipes and the arrangement positions correspond to the hollow columns. The heat medium ejected by the nozzles directly enters the hollow columns and is introduced into the catalyst module through the openings on the columns.

9. The flue gas denitration device according to claim 8, characterized in that, The openings are arranged in layers, with three openings in each layer and evenly spaced.

10. The flue gas denitration device according to claim 1, characterized in that, The horizontal movement is a reciprocating movement in the cross-section of the flue.

11. A flue gas denitrification method, characterized in that, Applying the device according to any one of claims 1 to 10, includes the following steps: A. Mix the ultra-low temperature flue gas with ammonia-air mixture in the flue; B. When the mixed gas flows through the catalyst module, NO in the mixed gas x and NH3 are adsorbed on the substrate of the catalyst; C. Drive the heat medium heating assembly to reciprocate horizontally in the flue, so that the sprayed heat medium gradually covers each row or column of catalyst modules, and stays above each catalyst module for the same preset time. Through the heat storage of the catalyst matrix, the heating of the catalyst module, the denitration reaction of NO x and NH3, and the regeneration of the catalyst are completed within the preset time.

12. The flue gas denitrification method according to claim 11, wherein The step of gradually covering the heat medium specifically is: spraying the heat medium directly onto the top of the corresponding catalyst module, or spraying the heat medium into the hollow columns of the corresponding catalyst module and then introducing it into the catalyst module through the openings on the columns.

13. The flue gas denitration method according to claim 11, characterized in that, The temperature of the ultra-low temperature flue gas is 50 - 120 °C.

14. The flue gas denitration method according to claim 11, wherein, The matrix of the catalyst filled in the catalyst module is made of a ceramic material; the active components of the catalyst are oxides of V, oxides of Ti, oxides of W, and oxides of Mo. Calculated as oxides, the mass ratio is as follows: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

15. The flue gas denitration method according to claim 11, wherein, The preset time in step C is 8 s - 10 s; the heated temperature of the catalyst module is controlled at 200 - 450 °C.

16. The flue gas denitration method according to claim 11, wherein One or more layers of the catalyst modules are arranged in the height direction, and one or more layers of catalyst modules form a catalyst bed, and a plurality of the catalyst beds are arranged in the flue.

17. The flue gas denitrification method according to claim 16, wherein The temperature of the catalyst bed is adjusted according to the flue gas composition: when the SO2 content in the flue gas is low, the temperature of the catalyst bed is controlled below 300 °C; when the SO2 content in the flue gas is high, the temperature of the catalyst bed is controlled between 320 °C and 450 °C.

Images