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 microwave assembly is arranged above the catalyst module in the flue; the microwave assembly comprises a horizontally moving microwave generator which is used for heating each catalyst module in different areas row by row or column by column, and after the heated area finishes denitration reaction and the catalyst is regenerated, the microwave generator is moved to the next area for heating. Through the modular design of the catalyst and the built-in and movable microwave source, the catalyst module can be gradually heated in different areas, 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 relates to an ultra-low temperature flue gas denitrification device and method. Background Art

[0002] Nitrogen Oxides are one of the main gaseous pollutants in the atmosphere. Nitrogen oxides NOx not only endanger human health, but are also 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 exhausts, etc. At present, the emission standards of NOx are constantly increasing. 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 is viscous, which 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 up. 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 in 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 and the built-in and movable microwave source, the catalyst module can be gradually heated in a divided area, so as to realize the rapid temperature rise 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 applicable to 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 enabling NO x to react with NH3 to carry out denitrification reaction when heated to the flue gas denitrification window temperature; a microwave assembly, which is arranged above the catalyst module in the flue; the microwave assembly includes a horizontally movable microwave generator, which is used for heating each catalyst module in a divided area row by row or column by column. After the denitrification reaction is completed in the heated area and the catalyst is regenerated, the microwave generator moves to the next area for heating.

[0010] Further, in the above technical solution, the microwave component may further include: a metal enclosure cavity, which is a hollow cavity and is arranged directly below the microwave generator, and is used to limit the microwave radiation range within the area of the metal enclosure cavity; a wave-transmitting material plate, which is arranged at the bottom of the metal enclosure cavity and is used to support the microwave window constructed by the wave-transmitting material.

[0011] Further, in the above technical solution, rollers are provided on the side wall of the metal enclosure cavity, and the rollers roll along the slide rail fixed in the flue to enable the overall horizontal movement of the microwave component.

[0012] Further, in the above technical solution, the width of the metal enclosure cavity can be adapted to the width of the catalyst module.

[0013] Further, in the above technical solution, a driving rod can be provided on the microwave component, which is used to connect with a controller outside the flue and drive the overall movement of the microwave component, and the driving rod can be fixed on the outer wall surface of the metal enclosure cavity.

[0014] Further, in the above technical solution, the number of microwave windows constructed by the wave-transmitting material can be multiple, and they can be evenly spaced on the wave-transmitting material plate.

[0015] Further, in the above technical solution, the number of microwave generators can be multiple, and they can be evenly spaced on the top of the metal enclosure cavity.

[0016] Further, in the above technical solution, the catalyst module may include: a metal wire mesh, which is a cubic structure enclosed by side walls and a bottom, and columns are provided at four edges of the cube; the metal wire mesh is made of non-wave-transmitting material. A catalyst, which is in a honeycomb or granular shape and is filled in the cubic structure.

[0017] Further, in the above technical solution, the matrix of the catalyst can be made of a wave-absorbing material with an adsorption function; the active components of the catalyst are immersed into the pores of the matrix.

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

[0019] According to the second aspect of the present invention, the present invention provides a flue gas denitration method, which applies the device of any one of the foregoing, and includes the following steps: A. Mix the ultra-low temperature flue gas and the 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 matrix of the catalyst; C. Drive the microwave component to reciprocate horizontally in the flue, so that the microwave radiation gradually covers each row or column of catalyst modules, and stays above each catalyst module for the same preset time, and within this preset time, complete the heating of the catalyst module, the denitration reaction of NO x and NH3, and the regeneration of the catalyst.

[0020] Further, in the above technical solution, the ultra-low temperature flue gas of the present invention refers to flue gas with a temperature of 50 to 120 °C, and this method is particularly applicable to flue gas with a temperature of 50 to 60 °C.

[0021] Further, in the above technical solution, the catalyst matrix filled in the catalyst module can be activated carbon; 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 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

[0022] Further, in the above technical solution, the maximum power of each microwave generator in the microwave component can be 6×10 5 W / m 3 ; the preset time in step C is preferably 2 s to 3 s; the heated temperature of the catalyst module is preferably controlled at 200 to 450 °C.

[0023] Further, in the above technical solution, the catalyst module can be provided with multiple layers in the height direction, and multiple catalyst modules can form a catalyst bed layer, and multiple catalyst bed layers can be provided in the flue.

[0024] 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 and 450 °C.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) The present invention adopts a modular filling of the denitration catalyst and heats the catalyst module until the denitration reaction temperature window is reached. Since microwave heating 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.;

[0027] 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 flue gas with a temperature of 50 to 120 °C. Experiments have proved that the device has a better denitration treatment effect on flue gas with a temperature of 50 to 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 flue gas with a temperature of 50 °C to 450 °C to achieve the required denitration effect;

[0028] 3) The present invention only needs to heat the catalyst, resulting in a significant reduction in energy consumption compared to heating the flue gas; through the modular design of the catalyst and the movable microwave components, row-by-row or column-by-column heating of the modules can be achieved. With a smaller number of microwave sources, centralized heating of each module can be realized. The microwave radiation range is more concentrated, effectively shortening the regional heating time. The heated module can reach the denitration window temperature instantaneously, and NO adsorbed on the catalyst matrix can x react with NH3 for denitration reaction. After the reaction, the gas quickly escapes and moves downward, thus simultaneously completing the regeneration of the catalyst in this module;

[0029] 4) For other catalyst modules other than the heated catalyst module in the present invention, the adsorption of NO and NH3 in the flue gas can be carried out simultaneously, waiting for the microwave components to move to this area for the process of heating - denitration reaction - catalyst regeneration; the horizontal reciprocating movement of the microwave components can realize the periodic adsorption - heating - reaction - regeneration of each catalyst module; x

[0030] 5) The catalyst matrix of the present invention is made of wave-absorbing material, and the microwave source has high heating efficiency for it, so that very little energy is required to heat the flue gas to reach the required denitration window temperature, thus achieving the effect of energy saving;

[0031] 6) Through the structural setting of the microwave components in the present invention, 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 is regenerated. The microwave components continue to move above the adjacent catalyst module, and the catalysts can be regenerated one by one, the denitration reaction is more complete, and the catalyst regeneration efficiency is higher;

[0032] 7) The present invention can control the movement process of the microwave components in real time by measuring the temperature in the catalyst module area in real time, that is, the microwave components 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, and the catalyst activity can be guaranteed). Therefore, the present invention has no restrictions on the composition of the flue gas.

[0033] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and be able to implement it according to the content of the specification, and at the same time to make the above and other purposes, technical features and advantages of the present invention more understandable, one or more preferred embodiments are listed below and described in detail in conjunction with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS ​

[0034] Figure 1 It is a schematic layout diagram of the flue gas denitration device of the present invention in the flue.

[0035] Figure 2 It is a top view schematic diagram of the first implementation manner of the flue gas denitration device of the present invention in the flue.

[0036] Figure 3 It is a side view schematic diagram of the first implementation manner of the flue gas denitration device of the present invention in the flue.

[0037] Figure 4 is a schematic structural diagram of the microwave component in the flue gas denitration device of the present invention (where Figure 4-A is a schematic cross-sectional view of the internal structure; Figure 4-B is Figure 4-A side view of; Figure 4-C is Figure 4-A top view of; Figure 4-D is Figure 4-A A-A cross-sectional view of).

[0038] Figure 5 It is a top view schematic diagram of the second implementation manner of the flue gas denitration device of the present invention in the flue.

[0039] Figure 6 It is a side view schematic diagram of the second implementation manner of the flue gas denitration device of the present invention in the flue.

[0040] Figure 7 It is a top view schematic diagram of the catalyst module in the flue gas denitration device of the present invention.

[0041] Main reference numeral description:

[0042] 1 - catalyst module, 11 - metal wire mesh, 12 - solid catalyst, 13 - column, 2 - microwave component, 21 - microwave generator, 22 - metal closed cavity, 23 - roller, 24 - wave-transparent material plate, 241 - microwave window, 25 - driving rod, 3 - ammonia injection element, 4 - ammonia mixing element, 100 - flue, 101 - slide rail. Specific embodiments

[0043] The following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0044] Unless otherwise clearly stated, throughout the specification and claims, the term "comprise" or its variations such as "comprises" or "comprising" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0045] In this document, for convenience of description, spatial relative terms such as "below", "beneath", "under", "above", "over", "on", 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 the 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 "under" 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.

[0046] 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.

[0047] 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 microwave heating 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, which has the advantages of simple process, low energy consumption, wide application range, etc.

[0048] As Figures 1 to 3 shown, 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. Upstream of the flue gas at the location of the device, there are an ammonia injection element 3 and an ammonia mixing element 4. 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 microwave component 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 x in the ultra-low temperature flue gas and NH3 in the ammonia-air mixture in the non-heating state, and cause NO x to react with NH3 in the denitration reaction when heated to the denitration window temperature of the flue gas. The microwave component 2 is arranged in the flue 100 and is located above the catalyst module 1. The microwave component 2 includes a horizontally movable microwave generator 21 (refer to Figures 2 to 6) It is used to heat each catalyst module 1 region by region row by row or column by column. After the denitrification reaction is completed in the heated region and the catalyst is regenerated, the microwave generator moves to the next region for heating.

[0049] 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 microwave component, a smaller number of microwave sources can be used to centrally heat each module. The microwave radiation range is more concentrated, which can effectively shorten the regional heating time. The heated module can reach the denitrification window temperature instantaneously. Therefore, the module can make NO adsorbed on the catalyst matrix x react with NH3 in an extremely short time. The reacted gas (generating N2 and H2O) quickly 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 and NH3 is carried out simultaneously, waiting for the microwave component to move to this region for the process of heating-denitrification reaction-catalyst regeneration. The horizontal movement of the microwave component 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.

[0050] Furthermore, as Figures 4-A to 4-D shown, preferably but not restrictively, in addition to the microwave generator 21, the microwave component 2 of the present invention may further include a metal enclosure 22, rollers 23, a wave-transmitting material plate 24, a driving rod 25, etc. Among them, the metal enclosure 22 is a hollow cavity and is arranged directly below the microwave generator 21, used to limit the microwave radiation range within the region of this metal enclosure. The wave-transmitting material plate 24 is arranged at the bottom of the metal enclosure 22, used to support the microwave window 241 constructed by the wave-transmitting material (refer to Figure 4-D ). The number of microwave generators 21 can be selected according to the size of the flue 100, the size of the catalyst module, and the temperature of the flue gas to be denitrified, etc. Multiple microwave generators 21 can be evenly spaced and arranged on the top of the metal enclosure 22. Four microwave generators 21 are arranged in Fig. 4. In order to realize the horizontal reciprocating movement of the microwave component 2, the present invention adopts a combination of rollers and slide rails, that is, rollers 23 are arranged on the side wall of the metal enclosure 22, and the rollers 23 can roll along the slide rail 101 fixed in the flue (refer to Figure 2 ) to make the overall horizontal movement of the microwave component 2. In order to make the microwave radiation better cover each catalyst module 1, the width of the metal enclosure 22 can be adapted to the width of the catalyst module (the two are preferably set the same to form a full coverage row by row or column by column of the module). In Figure 2 the first embodiment shown, two microwave components 2 are provided, and each microwave component covers four rows of catalyst modules. In Figure 5In the second embodiment shown, four microwave components 2 are provided, and each microwave component covers two rows of catalyst modules, which can be selected according to needs in the present invention. Further, as Figure 4-D shown, the number of microwave windows 241 constructed of wave-transparent material is multiple, and they are uniformly arranged at intervals on the wave-transparent material plate 24, and it is only necessary to ensure that the microwave radiation can effectively cover the catalyst module 1 below it. Through the above structural arrangement, when the microwave component 2 moves above 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. Then the microwave component 2 continues to move above the adjacent catalyst module 1 to regenerate the catalyst one by one.

[0051] Further, a driving rod 25 is provided on the microwave component 2 for connecting with a controller (not shown in the figure) outside the flue 100 and driving the overall movement of the microwave component 2. The driving rod 25 can be fixed on the outer wall surface of the metal closed cavity 22. A temperature sensor (not shown in the figure) can be provided on the bed layer where the catalyst module is located, and the driving rod 25 is controlled in real time by measuring the temperature of the catalyst module area in real time, so as to drive the microwave component 2 to control the residence time on each module according to the heating temperature requirement and the flue gas composition.

[0052] Further, as Figure 7 shown, preferably but not restrictively, the catalyst module 1 may include a metal wire mesh 11 and a solid catalyst 12. Among them, the metal wire mesh 11 is a cubic structure enclosed by side walls and a bottom (no wire mesh is provided at the top), and columns 13 are provided at four edges of the cube. The metal wire mesh 11 is made of non-wave-transparent material. The catalyst 12 can be in a honeycomb shape or granular and filled in the cubic structure. The matrix of the catalyst can be made of a wave-absorbing material with an adsorption function (for adsorbing NO x and NH3) (which can improve the heating efficiency); the active component of the catalyst is immersed in the pores of the matrix.

[0053] The present invention also provides a flue gas denitration method, which uses the aforementioned device and includes the following steps:

[0054] Step S101, mixing ultra-low temperature flue gas and ammonia-air mixture in the flue (the temperature of the ultra-low temperature flue gas can be 50-120 °C);

[0055] Step S102, when the mixed gas flows through the catalyst module 1, NO in the mixed gas xNH3 is adsorbed on the catalyst matrix. Specifically, the catalyst matrix filled in the catalyst module 1 can be activated carbon, etc.; 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 0.01 wt%, Ti is 99 wt%, W is 0.1 wt%, and Mo is 0.02 wt%.

[0056] Step S103, drive the microwave component 2 to reciprocate horizontally in the flue 100, so that the microwave radiation (the maximum power of the microwave generator is preferably 6×10 5 W / m 3 ) gradually covers each row or column of catalyst modules 1 and stays above each catalyst module 1 for the same preset time (preferably 2 s to 3 s). During this preset time, heating of the catalyst module, the denitration reaction of NO x and NH3, and catalyst regeneration are completed. The heated temperature of the catalyst module can be controlled at 200 - 450°C.

[0057] Furthermore, preferably but not restrictively, the catalyst modules 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.

[0058] The following is a detailed description with two specific embodiments:

[0059] Example 1

[0060] Flue gas to be denitrified: The flue gas volume is 55,000 Nm 3 / h, the temperature is 60°C, the pressure is 10 kPa, the NO x concentration is 600 mg / Nm 3 , the SO2 concentration is 100 mg / Nm 3 , the SO3 concentration is 10 mg / Nm 3 , and the dust content is 200 mg / Nm 3 .

[0061] The NO x emission standard is 100 mg / Nm 3 . The flow rate of the ammonia-air mixture used is 800 Nm 3 / h, and the volume fraction of ammonia gas is 3%. The cross-section of the flue is 1240×2480 mm.

[0062] The catalyst in this embodiment uses a honeycomb carbon-based denitration catalyst. The active components of the catalyst are oxides of V, Ti, W, and 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 module is provided with five layers, consisting of catalyst modules with a size of 150 mm × 150 mm. The height of the catalyst module is 200 mm, and the number of catalyst modules in each layer is 128.

[0063] The ammonia-air mixture is injected into the flue by an ammonia injection element and enters the SCR flue gas denitration device of the present invention after being mixed with the 60°C flue gas through a ammonia mixing element. The device is provided with 2 microwave components, and each microwave component is provided with 4 microwave generators. The maximum microwave power is 6×10 5 W / m 3 . The temperature of the heated catalyst module is controlled at 250°C. The microwave component stays above the catalyst module for 2 s and then moves to the adjacent catalyst module. The microwave component reciprocates horizontally and circularly heats each catalyst module. After the catalyst module is regenerated, the NO content in the discharged purified flue gas is less than 50 mg / Nm x , meeting the emission requirements. 3

[0064] Example 2

[0065] The flue gas to be denitrified: The flue gas volume is 35,000 Nm 3 / h, the temperature is 120°C, the pressure is 10 kPa, the NO x concentration is 200 mg / Nm 3 , the SO2 concentration is 1000 mg / Nm 3 , the SO3 concentration is 20 mg / Nm 3 , and the dust content is 200 mg / Nm 3 .

[0066] The NO x emission standard is 50 mg / Nm 3 . The flow rate of the ammonia-air mixture used is 170 Nm 3 / h, and the volume fraction of ammonia gas is 3%. The cross-section of the flue is 1240×2480 mm.

[0067] The catalyst in this embodiment uses a granular carbon-based denitration catalyst. The active components of the catalyst particles are oxides of V, Ti, W, and 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, the particle size is 5 mm; the bulk density is 0.68 g / cm 3, with a specific surface area of 80 m 2 / g and a pore volume of 0.57 cm 3 / g. The granular catalyst module is composed of a wire mesh, catalyst particles and columns, with a cross-sectional size of 150 mm × 150 mm, a module height of 150 mm, and a total of four layers. The number of catalyst modules in each layer is 128.

[0068] The ammonia-air mixture is injected into the flue by an ammonia injection element, and after being mixed with the 120 °C flue gas through a ammonia mixing element, it enters the SCR flue gas denitration device of the present invention. The device is provided with a total of 4 microwave components, each microwave component is provided with 2 microwave generators, and the maximum microwave power is 6×10 5 W / m 3 . The microwave generator is the same as that in Example 1, and the heating method is also the same. The temperature of the heated catalyst module is controlled at 350 °C. After the microwave component stays above the catalyst module for 2 s, it moves to the adjacent catalyst module. The microwave component reciprocates horizontally and heats each catalyst module in a cycle. After the catalyst module is regenerated, the NO x content in the discharged purified flue gas is less than 50 mg / Nm 3 , meeting the emission requirements.

[0069] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and it is apparent that many changes and variations are possible in light of the above teaching. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, so that those skilled in the art can implement and utilize various different exemplary embodiments of the invention, as well as various different selections and changes. Any simple modification, equivalent change and modification 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 disposed 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 causes NO x to react with NH3 in a denitration reaction when heated to the flue gas denitration window temperature; A microwave assembly is arranged above the catalyst module in the flue; the microwave assembly includes a horizontally movable microwave generator for heating each catalyst module in a row or column manner. When the denitrification reaction is completed in the heated area and the catalyst is regenerated, the microwave generator moves to the next area for heating.

2. The flue gas denitrification device according to claim 1, wherein The microwave assembly further comprises: A metal closed cavity, which is a hollow cavity and is arranged directly below the microwave generator, and is used to limit the microwave radiation range to the area within the metal closed cavity; The wave-transparent material plate is arranged at the bottom of the metal closed cavity and is used to support the microwave window constructed of the wave-transparent material.

3. The flue gas denitrification device according to claim 2, characterized in that, A roller is provided on the side wall of the metal closed cavity, and the roller rolls along a slide rail fixed in the flue so that the microwave assembly as a whole moves horizontally.

4. The flue gas denitration device according to claim 2, characterized in that, The width of the metal enclosed cavity is adapted to the width of the catalyst module.

5. The flue gas denitration device according to claim 3, characterized in that The microwave assembly is provided with a driving rod for connecting with a controller outside the flue and driving the microwave assembly to move as a whole. The driving rod is fixed on the outer wall of the metal closed cavity.

6. The flue gas denitration device according to claim 2, wherein There are multiple microwave windows constructed by the wave-transparent material, and the microwave windows are evenly spaced and arranged on the wave-transparent material plate.

7. The flue gas denitration device according to claim 2, characterized in that, There are multiple microwave generators, which are evenly spaced and arranged on the top of the metal closed cavity.

8. The flue gas denitration device according to claim 1, wherein, The catalyst module comprises: The metal mesh is a cubic structure formed by side walls and a bottom, with pillars provided at the four edges of the cube; the metal mesh is made of a non-wave-transparent material; The catalyst is in honeycomb or granular form and is filled in the cubic structure.

9. The flue gas denitrification device according to claim 8, characterized in that: The matrix of the catalyst is made of a wave-absorbing material with an adsorption function; the active components of the catalyst are immersed in the pores of the matrix.

10. 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.

11. A flue gas denitration method, characterized in that, Using the device according to any one of claims 1 to 10, comprising the following steps: A. Mixing 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 microwave component to reciprocate horizontally in the flue gas duct, so that the microwave radiation gradually covers each row or each column of catalyst modules, and stays above each catalyst module for the same preset time. During this preset time, complete the heating of the catalyst module, the denitration reaction of the NO x and NH3, as well as the catalyst regeneration.

12. The flue gas denitrification method according to claim 11, wherein, The temperature of the ultra-low temperature flue gas is 50-120°C.

13. The flue gas denitration method according to claim 11, characterized in that The catalyst matrix filled in the catalyst module is activated carbon; the active components of the catalyst are V oxide, Ti oxide, W oxide and Mo oxide, and the mass proportions of the active components, calculated as oxides, are as follows: V is 0.01wt%, Ti is 99wt%, W is 0.1wt% and Mo is 0.02wt%.

14. The flue gas denitration method according to claim 11, wherein The maximum power of each microwave generator in the microwave assembly is 6×10 5 W / m 3 ; The preset time in step C is 2s to 3s; the heating temperature of the catalyst module is controlled to be 200 to 450°C.

15. The flue gas denitration method according to claim 14, wherein The catalyst modules are arranged in multiple layers in the height direction, and the multiple layers of catalyst modules form a catalyst bed. A plurality of the catalyst beds are arranged in the flue.

16. The flue gas denitrification method according to claim 15, 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°C; when the SO2 content in the flue gas is high, the catalyst bed temperature is controlled between 320 and 450°C.

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