Flue gas denitration device and method

Abstract

The application discloses a flue gas denitration device and method, which is suitable for the SCR flue gas denitration process of ultra-low temperature flue gas, and comprises a catalyst module. x The catalyst module is arranged in multiple rows on the cross section of the flue duct and is used for adsorbing NH3 in the ultra-low temperature flue gas and the ammonia-air mixture in a non-heating state and making NO x and NH3 in the ultra-low temperature flue gas and the ammonia-air mixture occur denitration reaction when being heated to the flue gas denitration window temperature; the catalyst adopts a heat storage material as a base body; a heat medium heating assembly is arranged above the catalyst module in the flue duct; the heat medium heating assembly comprises horizontally moving spraying units, which are used for regionally spraying and heating each catalyst module row by row or column by column; when the heated region completes the denitration reaction and the catalyst is regenerated, the spraying units are moved to the next region for heating. The catalyst module can be regionally and gradually heated, the regional rapid heating of the catalyst module to the flue gas denitration window temperature is realized, and the catalyst regeneration process is rapidly completed.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, and in particular to a device and method for ultra-low temperature flue gas denitrification. Background Technology

[0002] Nitrogen oxides (NOx) are among the major gaseous pollutants in the atmosphere. NOx not only harms human health but is also a significant contributor to environmental damage, acid rain, and photochemical smog. The primary sources of NOx are the combustion of fossil fuels, including coal-fired power plants, industrial boilers, and vehicle exhaust. NOx emission standards are constantly being tightened. Commonly used flue gas denitrification technologies include selective non-catalytic reduction (SNCR), selective catalytic reduction (SCR), and ozone oxidation absorption. Among these, SCR is the most widely used. The principle of SCR is as follows: an ammonia-based reducing agent is injected into the NOx-containing flue gas. Under the action of a catalyst, NH3 reacts with NOx in a catalytic reduction reaction, producing N2 and H2O as reaction products. The traditional SCR process operates at a reaction temperature of 300–450℃; within this temperature range, the catalyst activity is highest and its lifespan is longest.

[0003] Since flue gas typically contains SO2, SO3, O2, and water vapor, when there is excess ammonia in the reaction zone (ammonia escape), it reacts with SO3 to form ammonium salts. These ammonium salts (NH4HSO4) are liquid and viscous at temperatures between 180 and 240°C. They adsorb onto the catalyst surface, reducing catalyst activity. Simultaneously, they adhere to the heat exchange tubes of the economizer downstream of the SCR denitrification reactor, attracting dust from the flue gas and causing scaling, blockage, and corrosion of the heat exchange tubes, thus affecting the unit's operating cycle. NH4HSO4 deposition is a significant bottleneck restricting the application of SCR denitrification under low-temperature conditions.

[0004] Most existing technologies use heating the flue gas to raise its temperature to the denitrification reaction temperature window, thus requiring a heat exchanger. However, for ultra-low temperature flue gas, heating the flue gas to raise its temperature for conventional SCR reactions would result in very large equipment and excessive energy consumption during the heating process.

[0005] Existing technologies also include methods that use microwave sources to heat catalysts to achieve flue gas denitrification. For example, Chinese patent application CN105727745A discloses a microwave reaction system for SCR denitrification, comprising a reactor body, a gas distributor, a device insulation layer, a microwave generator, a temperature measuring unit, a catalyst module, and an ammonia injection system. The temperature of the catalyst itself can be adjusted by regulating the input power of the microwave generator. This reaction system and device have advantages such as wide applicability, energy saving and environmental protection, and simple operation, and possess good economic benefits and potential industrial application value. However, the microwave source in this type of solution is arranged on the outer wall of the reactor body and is statically set, resulting in poor denitrification effect for ultra-low temperature flue gas. Even if the number of microwave sources is increased to cover the microwave radiation range within the reactor, meeting the required flue gas denitrification window temperature in the flue, microwave energy consumption will increase significantly.

[0006] Therefore, there is an urgent need for a flue gas denitrification device and method that can rapidly heat the catalyst module in sections, enabling it to quickly reach the window temperature for flue gas denitrification even when facing ultra-low temperature flue gas, while significantly reducing energy consumption.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The purpose of this invention is to provide a flue gas denitrification device and method, which is particularly suitable for 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 transfer medium heating source, the catalyst module can be heated in sections and gradually, so as to achieve rapid temperature rise of the catalyst module to the flue gas denitrification window temperature and quickly complete the catalyst regeneration process.

[0009] To achieve the above objectives, according to a first aspect of the present invention, a flue gas denitrification device is provided, suitable for SCR flue gas denitrification process of ultra-low temperature flue gas, comprising: multiple catalyst modules arranged in rows and columns fixedly disposed on the cross-section of the flue, for adsorbing NO in the ultra-low temperature flue gas in a non-heated state. x The NH3 in the ammonia-air mixture, and the NO when heated to the flue gas denitrification window temperature. x The catalyst undergoes a denitrification reaction with NH3; the catalyst uses a heat storage material as a matrix; a heat medium heating assembly is installed above the catalyst module in the flue; the heat medium heating assembly includes a horizontally moving injection unit for injecting heat into each catalyst module in rows or columns in a regional manner. When the heated area completes the denitrification reaction and the catalyst is regenerated, the injection unit moves to the next area for heating.

[0010] Furthermore, in the above technical solution, the heat medium heating component may also include: a sealed housing, which is a hollow cavity, used to accommodate the injection unit and limit the injection coverage area within the sealed housing, the width of the sealed housing being adapted to the width of the catalyst module.

[0011] Furthermore, in the above technical solution, the injection unit may further include: an injection main pipe, which is a hollow pipe through which a heat medium is introduced; the injection main pipe also serves as a driving rod of the injection unit, used to connect with a controller outside the flue and drive the heat medium heating assembly to move as a whole; and an injection branch pipe, which is connected to the injection main pipe and has nozzles on it, used to inject heat medium into the corresponding position of the catalyst module.

[0012] Furthermore, in the above technical solution, according to the first embodiment of the injection unit, the injection branch pipe can be set vertically relative to the injection main pipe, the nozzle extends vertically downward along the injection branch pipe, and multiple nozzles are evenly spaced and the injection coverage area corresponds to the size of the catalyst module.

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

[0014] Furthermore, in the above technical solution, the catalyst module may include: a metal wire mesh, which is a cuboid structure formed by the side walls and bottom, with hollow pillars at the four edges of the cuboid; openings are provided on the inner wall surface of the hollow pillars at different heights; and a catalyst, which is honeycomb-shaped or granular and filled in the cuboid structure.

[0015] Furthermore, in the above technical solution, the catalyst matrix can be made of ceramic material; the active component of the catalyst is immersed into the matrix pores.

[0016] Furthermore, in the above technical solution, according to the second embodiment of the injection unit, the nozzle can also be set at the end of the injection branch pipe and the setting position corresponds to the hollow column. The hot medium sprayed from the nozzle directly enters the hollow column and is introduced into the catalyst module through the opening on the column.

[0017] Furthermore, in the above technical solution, the openings can be set in layers, with three openings preferably set in each layer and evenly spaced.

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

[0019] To achieve the above objectives, according to a second aspect of the present invention, the present invention provides a flue gas denitrification method, using the apparatus of any one of the foregoing claims, comprising the following steps: A. mixing ultra-low temperature flue gas with an ammonia-air mixture in a flue; B. when the mixed gas flows through a catalyst module, NO in the mixed gas... x NH3 is adsorbed onto the catalyst matrix; C. The driving heat medium heating component moves horizontally back and forth within the flue, causing the sprayed heat medium to cover each row or column of catalyst modules in stages, and stay above each catalyst module for the same preset time. Through the heat storage of the catalyst matrix, the heating of the catalyst module is completed within the preset time. x The denitrification reaction with NH3 and catalyst regeneration.

[0020] Furthermore, in the above technical solution, the heat medium covering in stages can be specifically: spraying the heat medium directly 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 opening on the column.

[0021] Furthermore, in the above technical solution, the ultra-low temperature flue gas temperature refers to flue gas with a temperature of 50–120°C.

[0022] Furthermore, in the above technical solution, the catalyst matrix filled in the catalyst module can be made of ceramic material; the active components of the catalyst can be oxides of V, Ti, W, and Mo, and the active components are in the following mass ratios based on oxides: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

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

[0024] Furthermore, in the above technical solution, the catalyst module can be set with one or more layers in the height direction, and one or more catalyst modules can form a catalyst bed. Multiple catalyst beds can be set in the flue.

[0025] Furthermore, in the above technical solution, 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 can be controlled below 300℃; when the SO2 content in the flue gas is high, the catalyst bed temperature can be controlled between 320℃ and 450℃.

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

[0027] 1) This invention adopts a modular approach to the filling of the denitrification catalyst and heats the catalyst module until the denitrification reaction temperature window is reached. Because it uses a built-in heat medium heating method and heats each catalyst module in sections by area, the regional heating speed is fast and the time is short. It has the advantages of simple process, low energy consumption and wide applicability.

[0028] 2) This invention is particularly applicable to the SCR flue gas denitrification process for ultra-low temperature flue gas, where ultra-low temperature flue gas refers to flue gas with a temperature of 50-120℃. Tests have shown that the device has a better denitrification effect on flue gas with a temperature of 50-60℃. The device and method of this invention can also be applied to flue gas with higher temperatures, and can be applied to flue gas with a temperature of 50℃-450℃ to achieve the desired denitrification effect.

[0029] 3) This invention only requires heating the catalyst, significantly reducing energy consumption compared to heating flue gas. Through the modular design of the catalyst and the movable heat transfer medium heating components, heating of modules row by row or column by column can be achieved. A smaller number of injection units are needed to centrally heat each module, resulting in a more concentrated injection range that effectively shortens the regional heating time. The heated modules can reach the denitrification window temperature in a shorter time, allowing the NO adsorbed on the catalyst matrix to be effectively heated. x It undergoes a denitrification reaction with NH3, and the gas after the reaction is rapidly released and moved downwards, thereby simultaneously completing the catalyst regeneration of this module;

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

[0031] 5) This invention uses a method where the heat medium is uniformly sprayed onto the top of the catalyst module, allowing the heat medium to gradually penetrate downwards for heat transfer. Furthermore, because the catalyst matrix uses a heat storage material, the heated catalyst module as a whole can obtain the required denitrification window temperature in a short time, thereby rapidly completing the denitrification reaction and catalyst regeneration during the heating process. Due to the heat storage function of the catalyst matrix, the module can continue to carry out the denitrification reaction and catalyst regeneration for a period of time after the spraying unit is removed.

[0032] 6) This invention uses a method of injecting heat medium from the sides of the catalyst module at different heights, which allows the heat medium to quickly penetrate and transfer heat into the module. The penetration distance is shorter, and because the catalyst matrix uses a heat storage material, the heated catalyst module as a whole can obtain the required denitrification window temperature in a shorter time. Furthermore, due to the heat storage function of the catalyst matrix, the module can still continue to carry out denitrification reaction and catalyst regeneration for a period of time after the injection unit is removed.

[0033] 7) The present invention, through the structural arrangement of the heat medium heating component, can form a closed space when it moves above a certain catalyst module, so that flue gas cannot flow through this space. After the denitrification reaction is completed, the catalyst module can be regenerated. The heat medium heating component continues to move above the adjacent catalyst modules, and the catalyst can be regenerated one by one, so that the denitrification reaction is more complete and the catalyst regeneration efficiency is higher.

[0034] 8) This invention can control the movement of the heat transfer medium heating component in real time by measuring the temperature of the catalyst module area. That is, the residence time of the heat transfer medium heating component on each module can be controlled according to the heating temperature requirement and the composition of the flue gas. The catalyst bed temperature can be adjusted according to the composition of the flue gas: 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°C and 450°C (at this temperature, the ammonium salt generated can decompose, and the catalyst activity is guaranteed). Therefore, this invention has no restrictions on the composition of the flue gas.

[0035] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it according to the contents of the specification, and to make the above and other objects, technical features and advantages of the present invention easier to understand, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the arrangement of the flue gas denitrification device of the present invention in the flue.

[0037] Figure 2 is a schematic diagram of the first embodiment of the flue gas denitrification device of the present invention in a flue (wherein, Figure 2-A This is a top-down view; Figure 2-B (This is a side view diagram).

[0038] Figure 3 is a schematic diagram of the heat transfer heating component in the flue gas denitrification device of the present invention in a first embodiment (wherein) Figure 3-A This is a cross-sectional view of the internal structure. Figure 3-B for Figure 3-A Side view; Figure 3-C for Figure 3-A (Top view).

[0039] Figure 4 This is a three-dimensional structural schematic diagram of the heat transfer medium heating component in the flue gas denitrification device of the present invention.

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

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

[0042] Figure 7 This is a three-dimensional structural diagram of the catalyst module in the flue gas denitrification device of the present invention (in the state of not being filled with catalyst).

[0043] Figure 8 is a structural schematic diagram of the second embodiment of the heat medium heating component in the flue gas denitrification device of the present invention (wherein) Figure 8-A This is a cross-sectional view of the internal structure. Figure 8-B for Figure 8-A Side view; Figure 8-C for Figure 8-A (Top view).

[0044] Figure 9 This is a three-dimensional structural schematic diagram of the heat transfer medium heating component in the flue gas denitrification device of the present invention.

[0045] Explanation of key figure labels:

[0046] 1-Catalyst module, 11-Metal 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-Mixed ammonia element, 100-Flue, 101-Slide rail. Detailed Implementation

[0047] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0048] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0049] In this document, for ease of description, spatial relative terms such as “below,” “under,” “down,” “above,” “above,” “upper,” etc., are used to describe the relationship of one element or feature to another element or feature in the accompanying drawings. It should be understood that spatial relative terms are intended to encompass different orientations of an object in use or operation, in addition to those depicted in the figures. For example, if an object in the figure is flipped, an element described as “below” or “under” another element or feature would be oriented “above” that element or feature. Thus, the exemplary term “below” can encompass both the downward and upward orientations. An 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 specific positions or relative relationships. In other words, in some embodiments, the terms "first," "second," etc., can also be used interchangeably.

[0051] The technical concept of this invention is to modularize the filling of the denitrification catalyst and heat the catalyst modules until the denitrification reaction temperature window is reached. Because the heating is carried out by jet heating of the heat medium (such as steam) and the catalyst modules are heated in sections by section, the regional heating speed is fast and the time is short. It has the advantages of simple process, low energy consumption and wide applicability.

[0052] like Figure 1 As shown in Figure 2, this invention provides a flue gas denitrification device, particularly suitable for SCR flue gas denitrification processes using ultra-low temperature flue gas. The ultra-low temperature flue gas of this invention refers to flue gas with a temperature of 50–120°C. This device is more effective at denitrifying flue gas with a temperature of 50–60°C. The device is installed within a flue duct 100. An ammonia injection element 3 and an ammonia mixing element 4 are located upstream of the device. An ammonia-air mixture enters the ammonia injection element 3 radially from the flue duct 100 and is ejected in the same direction as the flue gas. The ejected ammonia-air mixture mixes with the flue gas in the ammonia mixing element 4, and the mixture enters the flue gas denitrification device of this invention. The device includes at least a catalyst module 1 and a heat transfer medium heating assembly 2. Multiple catalyst modules 1 are arranged in rows and columns fixedly on the cross-section of the flue duct 100 (fully covering the cross-section of the flue duct), used to adsorb NO from the ultra-low temperature flue gas in a non-heated state. x The NH3 in the ammonia-air mixture, and the NO when heated to the flue gas denitrification window temperature. xThe catalyst undergoes a denitrification reaction with NH3. A heat storage material (preferably ceramic) serves as the substrate for the catalyst. The heat transfer medium heating assembly 2 is located within the flue 100 and above the catalyst module 1. The heat transfer medium heating assembly 2 includes horizontally movable injection units (refer to Figures 3, 4, 8, and 9), used to heat each catalyst module 1 in sections, row by row or column by column. Once the heated section has completed the denitrification reaction and the catalyst has been regenerated, the injection unit moves to the next section for heating.

[0053] The device of this invention adopts the above-described technical solution. Through the modular design of the catalyst and the movable heat transfer medium heating component, the modules are heated row by row or column by column. A smaller number of injection units can be used to centrally heat each module, resulting in a more concentrated injection range and effectively shortening the regional heating time. Furthermore, since the catalyst matrix is ​​made of a heat storage material, the heated module can reach the denitrification window temperature in a shorter time. Therefore, this module can cause NO adsorbed on the catalyst matrix to dissolve in a shorter time. x The catalyst undergoes a denitrification reaction with NH3, and the resulting gases (N2 and H2O) rapidly escape and descend, thus simultaneously regenerating the catalyst in this module. In areas outside the heated catalyst module (i.e., other catalyst modules), the denitrification of NO in the flue gas also occurs simultaneously. x The catalyst undergoes adsorption with NH3, followed by a heating-denitrification reaction-catalyst regeneration process as the heating medium module moves to the designated area. The horizontal movement of the heating medium module is preferably a reciprocating motion across the flue gas duct cross-section, enabling each catalyst module to periodically complete the entire process of adsorption-heating-reaction-regeneration.

[0054] As further shown in Figures 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 used to house the injection unit and limit the injection coverage area within the sealed housing 21. The width of the sealed housing can be adapted to the width of the catalyst module (preferably both are the same, forming a row-by-row or column-by-column full coverage of the module). The number of injection units can be selected according to the diameter of the flue 100, the size of the catalyst module, and the temperature of the flue gas to be denitrified. The injection unit may further include a main injection pipe 22 and injection branch pipes 23. The main injection pipe 22 is a hollow pipe through which the heat medium flows. The main injection pipe 22 can also serve as a driving rod for the injection unit, used to connect to a controller (not shown in the figure) outside the flue and drive the overall movement of the heat medium heating assembly 2. A temperature sensor (not shown in the figure) can be installed in the bed where the catalyst module 1 is located. By measuring the temperature of the catalyst module area in real time, the injection main pipe 22, which acts as a drive rod, can be controlled in real time. This, in turn, drives the heat medium heating assembly 2 to control the residence time in each module according to the heating temperature requirements and the composition of the flue gas. The injection branch pipe 23 is connected to the injection main pipe 22 and is equipped with nozzles 24 for injecting heat medium into the corresponding positions of the catalyst module 1.

[0055] Further refer to Figure 3 and Figure 4 In the first embodiment of the injection unit, the injection branch pipe 23 is vertically arranged relative to the injection main pipe 22, and the nozzles 24 extend vertically downward along the injection branch pipe 23. Multiple nozzles 24 are evenly spaced, and the spray 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 heated catalyst module). With this arrangement, the heat medium can be evenly sprayed onto the top of the catalyst module 1 and gradually penetrate downwards for heat transfer. Since the catalyst matrix uses a heat storage material, the heated catalyst module as a whole can obtain the required denitrification window temperature in a short time, thereby rapidly completing the denitrification reaction and catalyst regeneration during the heating process of the module. Furthermore, due to the heat storage function of the catalyst matrix, the module can continue to carry out denitrification reaction and catalyst regeneration for a period of time after the injection unit is removed.

[0056] Further, as shown in Figures 8 and 9, in the second embodiment of the injection unit, the injection branch pipe 23 can be extended by means of an elbow, and the nozzle 24 is set at the end of the injection branch pipe 23, such that the setting position of the nozzle 24 corresponds to the hollow column 13 at the four edges of the catalyst module 1 (that is, one catalyst module corresponds to four nozzles 24). With this arrangement, the heat medium sprayed from the nozzle 24 directly enters the hollow column 13 and is introduced into the catalyst module 1 through the opening 131 on the column (see reference). Figure 6 , Figure 7With this configuration, the heat transfer medium can be injected from the sides of the catalyst module 1 at different heights and quickly penetrate into the module for heat transfer (shorter penetration distance). Since the catalyst matrix uses a heat storage material, the heated catalyst module as a whole can obtain the required denitrification window temperature in a shorter time (compared to the first embodiment), thereby rapidly completing the denitrification reaction and catalyst regeneration during the heating process of the module. Furthermore, due to the heat storage function of the catalyst matrix, the module can continue to carry out denitrification reaction and catalyst regeneration for a period of time after the injection unit is removed.

[0057] As shown in Figures 3 and 8, in order to realize the horizontal reciprocating movement of the heat medium heating component 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 heat medium heating component 2 as a whole can realize horizontal reciprocating movement.

[0058] Further, as shown in Figures 2 and 5, regarding the arrangement of the heat transfer medium heating components 2, in the first embodiment shown in Figure 2, two heat transfer medium heating components 2 are set, each covering four rows of catalyst modules. In the second embodiment shown in Figure 5, four heat transfer medium heating components 2 are set, each covering two rows of catalyst modules. The present invention can select the appropriate method as needed. With the above structural arrangement, when the heat transfer medium heating component 2 moves above a certain catalyst module 1, it can form a closed space, preventing flue gas from flowing through it. After the denitrification reaction is completed, the catalyst module can be regenerated. The heat transfer medium heating component 2 can continue to move above adjacent catalyst modules 1 to regenerate the catalysts one by one.

[0059] Further as Figure 6 , 7 As shown, preferably but not limitingly, the catalyst module 1 may include a metal mesh 11 and a solid catalyst 12. The metal mesh 11 is a cuboid structure formed by sidewalls and a bottom (without mesh at the top). Hollow pillars 13 are provided at the four edges of the cuboid, and openings 131 are provided on the inner-facing walls of the hollow pillars 13 at different heights. The openings 131 are preferably arranged in layers. Figure 7 Three catalysts are arranged evenly spaced in each layer. The catalyst 12 can be honeycomb-shaped or granular and filled within a cubic structure. The catalyst matrix can be made of materials with adsorption capabilities (for adsorbing NO). x It is made of heat storage material (NH3); the active component of the catalyst is immersed in the matrix pores.

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

[0061] Step S101: Mix the ultra-low temperature flue gas with the ammonia-air mixture in the flue (the temperature of the ultra-low temperature flue gas can be 50-120℃).

[0062] In step S102, when the mixed gas stream passes through catalyst module 1, the NO in the mixed gas... x The NH3 is adsorbed onto the catalyst matrix. Specifically, the catalyst matrix filled in catalyst module 1 can be made of heat storage materials such as ceramics; the active components of the catalyst can be oxides of V, Ti, W, and Mo, and the mass ratio of the active components, based on oxides, is as follows: V is 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

[0063] Step S103: Drive the heat transfer medium heating component 2 to reciprocate horizontally within the flue 100, so that the sprayed heat transfer medium gradually covers each row or column of catalyst modules 1, and stays above each catalyst module 1 for the same preset time (preferably 8s to 10s). Through the heat storage of the catalyst matrix, the heating of the catalyst module and the NO removal are completed within the preset time. x The catalyst undergoes a denitrification reaction with NH3 and undergoes catalyst regeneration. The heating temperature of the catalyst module can be controlled between 200 and 450°C.

[0064] Furthermore, preferably but not limitingly, when the heat medium covers each row or column of catalyst modules 1 in stages, the heat medium can be sprayed directly 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 opening 131 on the column.

[0065] Furthermore, preferably but not limitingly, the catalyst module 1 can be configured with multiple layers in the height direction. These multiple catalyst modules can construct a catalyst bed, and multiple catalyst beds can be arranged within the flue gas duct according to process requirements. 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℃; when the SO2 content in the flue gas is high, the catalyst bed temperature is controlled between 320℃ and 450℃.

[0066] The following two specific embodiments will be used to illustrate the details:

[0067] Example 1

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

[0069] NO x The emission standard is 100 mg / Nm³. 3 The flow rate of the ammonia-air mixture is 800 Nm³. 3 / h, of which ammonia gas accounts for 3%. The flue cross-section is 1240×2480mm.

[0070] In this embodiment, a honeycomb denitration catalyst is used, with a honeycomb ceramic matrix. The active components of the catalyst are oxides of V, Ti, W, and Mo. The mass ratios of the active components, based on oxides, are as follows: V 0.01 wt%, Ti 99 wt%, W 0.1 wt%, and Mo 0.02 wt%. The catalyst consists of a single layer, composed of 128 catalyst modules, each 150 mm × 150 mm in height, with a total module height of 700 mm.

[0071] Ammonia-air mixture is injected into the flue gas duct by an ammonia injection element. After mixing with the 60°C flue gas through the ammonia mixing element, it enters the SCR flue gas denitrification device of this invention. Two heat transfer medium heating components are provided, and the injection unit has 36 nozzles. Medium-pressure steam is used as the heat transfer medium to heat the catalyst modules, controlling the temperature of the heated catalyst modules at 250°C. The injection unit stays above the catalyst module for 10 seconds before moving to an adjacent catalyst module. The heat transfer medium heating components circulate and heat each catalyst module.

[0072] Experiments have verified that after the catalyst module is regenerated, the NO in the emitted flue gas is reduced. x Content less than 50 mg / Nm 3 It meets emission requirements.

[0073] Example 2

[0074] Flue gas to be treated: Flue gas volume is 35,000 Nm³ 3 / h, temperature 120℃, pressure 10kPa, NO x Concentration of 200 mg / Nm 3 The SO2 concentration is 1000 mg / Nm³. 3 The SO3 concentration is 20 mg / Nm³. 3 The dust content is 200 mg / Nm³. 3 .

[0075] NO x The emission standard is 50 mg / Nm³. 3 The flow rate of the ammonia-air mixture is 170 Nm³. 3 / h, of which ammonia gas accounts for 3%. The flue cross-section is 1240×2480mm.

[0076] In this embodiment, a granular denitrification catalyst is used, with a heat-storing ceramic sphere matrix. The active components of the catalyst particles are oxides of V, Ti, W, and Mo. The mass ratios of the active components (based on oxides) are as follows: V 0.01 wt%, Ti 99 wt%, W 0.1 wt%, and Mo 0.02 wt%. The catalyst is spherical with a particle size of 5 mm and a bulk density of 0.68 g / cm³. 3 Specific surface area is 80m² 2 / g, pore volume is 0.57cm 3 / g. The catalyst module consists of a metal mesh, catalyst particles, and hollow risers. Each hollow riser has 24 holes with a diameter of 3mm, and the bottom of the hollow riser is sealed. The catalyst module has a cross-sectional dimension of 150mm × 150mm and a module height of 400mm. There is one layer of the module, with a total of 128 modules.

[0077] Ammonia-air mixture is injected into the flue gas duct by an ammonia injection element. After mixing with the 120°C flue gas through the ammonia mixing element, it enters the SCR flue gas denitrification device of this invention. A total of four heat transfer medium heating components are installed, and the injection unit is equipped with eight nozzles. The nozzle positions correspond to the hollow risers of the catalyst modules. Medium-pressure steam is used as the heat transfer medium to heat the catalyst modules, controlling the temperature of the heated catalyst modules at 350°C. When the injection unit moves above the catalyst modules, the nozzles align with the hollow risers of the catalyst modules, and steam enters the risers and is sprayed onto the catalyst particles through the riser openings to regenerate them. The injection unit stays for 10 seconds and then moves to the adjacent catalyst module. The heat transfer medium heating components circulate and heat each catalyst module.

[0078] Experiments have verified that after the catalyst module is regenerated, the NO in the emitted flue gas is reduced. x Content less than 50 mg / Nm 3 It meets emission requirements.

[0079] The foregoing description of specific exemplary embodiments of the present invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. Any simple modifications, equivalent changes, and alterations made to the foregoing exemplary embodiments should fall within the scope of protection of the present invention.

Claims

1. A flue gas denitrification device, characterized in that, An SCR flue gas denitrification process suitable for ultra-low temperature flue gas, where ultra-low temperature flue gas refers to flue gas with a temperature of 50~120℃; the device includes: Multiple catalyst modules, arranged in rows and columns, are fixedly installed on the cross-section of the flue gas to adsorb NO from the ultra-low temperature flue gas in a non-heated state. x The NH3 in the ammonia-air mixture, and the NO when heated to the flue gas denitrification window temperature. x The catalyst undergoes a denitrification reaction with NH3; the catalyst uses a heat storage material as a matrix; the catalyst module includes: a metal wire mesh, which is a cuboid structure enclosed by side walls and bottom, with hollow pillars at the four edges of the cuboid; the hollow pillars have openings on the inner wall surface at different heights; the catalyst is in the form of a honeycomb or granular shape and is filled in the cuboid structure; A heat transfer medium heating assembly is disposed above the catalyst module within the flue. This assembly includes horizontally moving injection units for sequentially injecting heat into each catalyst module in rows or columns, heating the area as needed. After the heated area completes the denitrification reaction and the catalyst is regenerated, the injection unit moves to the next area for heating. The assembly also includes a sealed housing, a hollow cavity, for housing the injection unit and limiting the injection coverage area within the sealed housing. The width of the sealed housing is adapted to the width of the catalyst module. The injection unit further includes: a main injection pipe, a hollow pipe through which heat transfer medium flows; the main injection pipe also serves as a driving rod for the injection unit, connecting to a controller outside the flue and driving the overall movement of the heat transfer medium heating assembly; and an injection branch pipe, connected to the main injection pipe and equipped with nozzles for injecting heat transfer medium into corresponding positions on the catalyst module. The nozzles are located at the ends of the injection branch pipes and their positions correspond to the hollow column. The heat transfer medium ejected from the nozzles directly enters the hollow column and is introduced into the catalyst module through the openings on the column.

2. The flue gas denitrification device according to claim 1, characterized in that, The injection branch pipe is set vertically relative to the injection main pipe, and the nozzle extends vertically downward along the injection branch pipe. Multiple nozzles are evenly spaced and the injection coverage area corresponds to the size of the catalyst module.

3. The flue gas denitrification device according to claim 1, characterized in that, The side wall of the sealed housing is provided with rollers, which roll along the slide rail fixed in the flue, so that the heat medium heating assembly moves horizontally as a whole.

4. The flue gas denitrification device according to claim 1, characterized in that, The catalyst matrix is ​​made of ceramic material; the active component of the catalyst is immersed in the matrix pores.

5. The flue gas denitrification device according to claim 1, characterized in that, The openings are arranged in layers, with three openings in each layer and evenly spaced apart.

6. The flue gas denitrification device according to claim 1, characterized in that, The horizontal movement is a reciprocating motion on the cross-section of the flue.

7. A method for flue gas denitrification, characterized in that, Using the apparatus as described in any one of claims 1 to 6, the method includes the following steps: A. Mix ultra-low temperature flue gas with ammonia-air mixture in the flue; B. When the mixed gas flows through the catalyst module, the NO in the mixed gas... x NH3 is adsorbed onto the catalyst matrix; C. The driving heat medium heating component moves horizontally back and forth within the flue, causing the sprayed heat medium to cover each row or column of catalyst modules in stages, 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 is completed within the preset time. x The denitrification reaction with NH3 and catalyst regeneration.

8. The flue gas denitrification method according to claim 7, characterized in that, The catalyst matrix filled in the catalyst module is made of ceramic material.

9. The flue gas denitrification method according to claim 7, characterized in that, The preset time in step C is 8s~10s; the heating temperature of the catalyst module is controlled at 200~450℃.

10. The flue gas denitrification method according to claim 7, characterized in that, The catalyst module is arranged in one or more layers in the height direction, and one or more catalyst modules form a catalyst bed. Multiple catalyst beds are arranged in the flue.

11. The flue gas denitrification method according to claim 10, characterized in that, The catalyst bed temperature is 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℃; when the SO2 content in the flue gas is high, the catalyst bed temperature is controlled between 320 and 450℃.

Images