Fluidized bed denitration process

Abstract

The invention discloses a fluidized bed denitration process, and relates to the technical field of industrial flue gas treatment, in particular to a process method for removing NOx in flue gas by adopting a powder normal-temperature denitration catalyst, applying a fluidized bed for reaction, recycling the catalyst in a bag-type dust collector and realizing circular catalytic decomposition. Reaction conditions are mild, and the process is safe; and the generated substances are N2 and O2 which leave along with the flue gas. The device has the beneficial effects that the fluidized bed is used as a catalytic reaction main body section, and a powder catalyst rolls up and down in the fluidized bed and is in good contact with flue gas; due to the arrangement of the expansion section, most of catalyst powder can be refluxed, and the load of a rear bag-type dust collector is reduced; the catalyst bin is provided with a heating and heat preservation device, so that the polluted catalyst can be regenerated on line, and the service life of the catalyst is prolonged; the fluidized bed denitration system is high in automation degree, low in maintenance cost and high in adaptability.

Description

Technical Field

[0001] The invention relates to the technical field of industrial flue gas treatment, in particular to a fluidized bed denitrification process. Background Art

[0002] Nitrogen oxides (NOx) are one of the main sources of air pollution. The causes of NOx can be divided into two aspects: natural sources and man-made sources. Among them, the NOx emissions from fixed sources such as thermal power plants, iron and steel plants, chemical plants, mobile sources such as cars, and intermediate products produced in industrial processes account for more than 90% of the total man-made emissions. Industrial NOx emissions account for 60% of the total emissions, and the situation of industrial source NOx control is still very severe.

[0003] Selective catalytic reduction technology (SCR technology) is the most widely used flue gas denitrification technology in the world. Its principle is that the reducing gas reacts with NOx to reduce it to N2. Among them, NH3 is the reducing agent with the best application effect and the widest application range. One of the application characteristics of this method is to contact the flue gas with the catalyst fixed in the denitrification reactor. During the contact between the flue gas and the catalyst, the catalyst catalyzes the flue gas. Since the activity of the catalyst gradually decreases during use, but the method cannot achieve online regeneration of the catalyst during application, the flue gas treatment efficiency of this method is gradually reduced during use, and the flue gas treatment effect is unstable, which affects the flue gas treatment effect; the catalyst position is fixed, resulting in fixed contact area and contact position with the flue gas, and the contact frequency between the flue gas and the catalyst is low, which further affects the flue gas treatment effect; and another application feature of this method is that it needs to reach a certain temperature, but due to the characteristics of the production process, the non-electric industry does not apply the temperature zone required for SCR denitrification. These non-electric industries use SCR denitrification technology and need to heat up and exchange heat, resulting in high investment costs, high energy consumption, and extended processes.

[0004] Therefore, designing a fluidized bed denitrification process to achieve the purpose of catalytic decomposition denitrification and achieve the effects of low system investment, low operating cost, stable and reliable operation, and high flue gas treatment efficiency has become an urgent problem to be solved in this field. Summary of the invention

[0005] In view of the shortcomings of large investment and high operating cost of SCR denitrification process in non-electric industry, the present invention proposes a fluidized bed denitrification process to achieve the purpose of catalytic decomposition denitrification, and achieve the effects of low system investment, low operating cost, stable and reliable operation, and high flue gas treatment efficiency.

[0006] The present invention provides the following technical solution: a fluidized bed denitration process, the device used in the process includes a catalyst silo, a fluidized bed reactor, a dust removal and recovery structure, a chimney, a pneumatic conveying device 1, a pneumatic conveying device 2, a pneumatic conveying device 3 and a pneumatic conveying device 4, the catalyst silo stores normal temperature denitration catalyst powder, the feed end of the catalyst silo is provided with a pneumatic conveying device 1, the normal temperature denitration catalyst powder is transported to the catalyst silo via the pneumatic conveying device 1, the discharge end of the catalyst silo is connected to the fluidized bed reactor via the pneumatic conveying device 2, and the catalyst silo is provided with a heating and heat preservation device;

[0007] The fluidized bed reactor is provided with an air intake section, a venturi tube section, a main reaction section of the fluidized bed reactor and an expansion section in sequence from bottom to top; a catalyst nozzle is provided at the bottom of the main reaction section of the fluidized bed reactor, the discharge end of the second pneumatic conveying device is connected to the feed end of the catalyst nozzle, and a discharge port is provided at the bottom of the fluidized bed reactor, and the normal temperature denitration catalyst powder falling through the discharge port is refluxed to the catalyst silo via the third pneumatic conveying device;

[0008] The top of the fluidized bed reactor is provided with a flue gas outlet, which is connected to the air inlet end of the dust removal and recovery structure. The dust removal and recovery structure filters the denitration gas and recovers the normal temperature denitration catalyst powder. The recovered normal temperature denitration catalyst powder eventually flows back to the catalyst silo. The air outlet end of the dust removal and recovery structure is connected to the chimney through an induced draft fan.

[0009] The fluidized bed denitrification process includes the following process flow:

[0010] S1, the normal temperature denitration catalyst powder is delivered to the catalyst silo by air through the pneumatic conveying device 1, the material in the catalyst silo falls into the gas conveying pipeline through the star-shaped ash discharge valve, and the powdered catalyst is delivered to the main reaction section of the fluidized bed reactor through the pneumatic conveying device 2;

[0011] S2. The flue gas is introduced into the bottom air inlet section of the fluidized bed reactor, and then sent to the main reaction section of the fluidized bed reactor through the Venturi tube section for catalytic decomposition reaction to decompose NOx in the flue gas into N2 and O2. The gas after the reaction is introduced into the dust removal and recovery structure after the expansion section. The dust removal and recovery structure recovers the catalyst to realize the recycling of the catalyst. The dust-removed gas is sent to the chimney through the induced draft fan to meet the emission standards.

[0012] Preferably, the dust collection and recovery structure comprises a bag filter, the air inlet end of the bag filter is connected to the flue gas outlet of the fluidized bed reactor, and the air outlet end of the bag filter is connected to the induced draft fan.

[0013] Preferably, the dust removal and recovery structure includes a cyclone dust collector and a bag dust collector, the air inlet end of the cyclone dust collector is connected to the flue gas outlet of the fluidized bed reactor, the air outlet end of the cyclone dust collector is connected to the air inlet end of the bag dust collector, the air outlet end of the bag dust collector is connected to the induced draft fan, and the room-temperature denitrification catalyst powder separated by the cyclone dust collector is directly refluxed to the main reaction section of the fluidized bed reactor through its bottom discharge port.

[0014] Preferably, the cyclone dust collector is located above the catalyst nozzle, and the room-temperature denitration catalyst powder separated by the cyclone dust collector directly flows back to the bottom of the inner cavity of the main reaction section of the fluidized bed reactor under the action of gravity.

[0015] Preferably, a screw conveyor is fixed to the discharge end of the bag dust collector, and discharge ports are provided at the bottom of both ends of the screw conveyor. An intermediate hopper is provided below one discharge port, and a pneumatic conveying device 4 is provided at the bottom of the intermediate hopper. An output hopper is provided below the other discharge port, and the discharge end of the bag dust collector is located between the two discharge ports.

[0016] Preferably, a backflush assembly is provided in the bag-type dust collector, and the bag-type dust collector is a pulse bag-type dust collector.

[0017] Preferably, the pneumatic conveying device four is connected in series with the pneumatic conveying device three, and the wind source enters the pneumatic conveying device three through the pneumatic conveying device four.

[0018] Preferably, a baffle structure is provided in the expansion section, and the baffle structure is used to intercept the normal temperature denitration catalyst powder.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The catalyst is in powder form, and the catalyst active surface is large, which is conducive to the catalytic reaction. The catalyst uses a room temperature denitration catalyst, and the catalytic denitration can be carried out at room temperature without heating or heat exchange, saving a lot of energy and investment, and having low operating costs;

[0021] (2) A fluidized bed is used as the main section of the catalytic reaction. The powdered catalyst rolls up and down in the fluidized bed, making good contact with the flue gas and improving the flue gas treatment efficiency;

[0022] (3) An expansion section is set on the upper part of the fluidized bed to enable most of the catalyst powder to reflux and reduce the load of the bag filter behind;

[0023] (4) The catalyst powder is recovered by pulse bag dust collector, and the equipment cost is low;

[0024] (5) The catalyst silo is equipped with a heating and heat preservation device so that the contaminated catalyst can be regenerated online, extending the service life of the catalyst and making the process run stably and reliably to ensure the flue gas treatment effect;

[0025] (6) The fluidized bed denitrification system has a high degree of automation, low maintenance cost and strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the process flow of Example 1 of the present invention;

[0027] Figure 2 This is a schematic diagram of the process flow of Example 2 of the present invention.

[0028] In the figure: 1. catalyst silo; 2. fluidized bed reactor; 3. bag filter; 4. induced draft fan; 5. chimney; 6. pneumatic conveying device 1; 7. pneumatic conveying device 2; 8. pneumatic conveying device 3; 9. pneumatic conveying device 4; 10. cyclone dust collector; 11. heating and heat preservation device; 21. air intake section; 22. venturi tube section; 23. catalyst nozzle; 24. main reaction section of fluidized bed reactor; 25. expansion section; 31. screw conveyor; 32. intermediate hopper; 33. output hopper; A. flue gas; B1. Roots blower wind 1; B2. Roots blower wind 2; B3. Roots blower wind 3; C. room temperature denitrification catalyst powder; D. purified flue gas. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a fluidized bed denitrification process, and the device used in the process includes a catalyst silo 1, a fluidized bed reactor 2, a dust removal and recovery structure, a chimney 5, a pneumatic conveying device 1 6, a pneumatic conveying device 2 7, a pneumatic conveying device 3 8 and a pneumatic conveying device 4 9. The catalyst silo 1 stores normal temperature denitrification catalyst powder, and the feed end of the catalyst silo 1 is provided with a pneumatic conveying device 1 6. When the device is in use, the normal temperature denitrification catalyst powder is transported to the catalyst silo 1 via the pneumatic conveying device 1 6, and the discharge end of the catalyst silo 1 is connected to the fluidized bed reactor 2 via the pneumatic conveying device 2 7. The catalyst silo 1 is provided with a heating and heat preservation device 11. By setting the heating and heat preservation device 11, when the heating and heat preservation device 11 is working, the contaminated catalyst can be regenerated online, thereby extending the service life of the catalyst.

[0031] The fluidized bed reactor 2 is provided with an air inlet section 21, a venturi section 22, a fluidized bed reactor main reaction section 24 and an expansion section 25 from bottom to top, and a flue gas outlet is provided at the top of the fluidized bed reactor 2. A baffle structure is provided in the expansion section 25, and the baffle structure is used to intercept the normal temperature denitration catalyst powder, so that most of the catalyst powder can be refluxed, reducing the load of the dust removal and recovery structure. The baffle structure can be a baffle plate.

[0032] A catalyst nozzle 23 is provided at the bottom end of the main reaction section 24 of the fluidized bed reactor, and the discharge end of the pneumatic conveying device 27 is connected to the feed end of the catalyst nozzle 23. The room temperature denitration catalyst powder can be evenly sprayed into the main reaction section 24 of the fluidized bed reactor through the catalyst nozzle 23. A discharge port is provided at the bottom of the fluidized bed reactor 2, and the room temperature denitration catalyst powder falling through the discharge port is refluxed to the catalyst silo 1 via the pneumatic conveying device 3 8; when the device is in use, the flue gas to be denitrated enters the fluidized bed reactor 2 through the air intake section 21, and enters the main reaction section 24 of the fluidized bed reactor through the venturi tube section 22. The flue gas is fully mixed with the catalyst powder in the main reaction section 24 of the fluidized bed reactor to achieve catalytic decomposition of the flue gas. The treated gas passes through the expansion section and is finally discharged through the flue gas outlet.

[0033] The reaction equation for the catalytic decomposition reaction is as follows:

[0034] 2NO=N2+O2 or 2NO2=N2+2O2.

[0035] The flue gas outlet is connected to the air inlet end of the dust removal and recovery structure. The dust removal and recovery structure filters the denitrification gas and recovers the room temperature denitrification catalyst powder. The air outlet end of the dust removal and recovery structure is connected to the chimney 5 through the induced draft fan 4. The dust removal gas enters the chimney 5 through the induced draft fan 4 to achieve standard gas emission.

[0036] In Example 1, the dust collection and recovery structure includes a bag filter 3, which is a pulse bag filter with a simple structure and low cost. The air inlet of the bag filter 3 is connected to the flue gas outlet of the fluidized bed reactor 2, and the air outlet of the bag filter 3 is connected to the induced draft fan 4. A backflush assembly is provided in the bag filter 3, and a discharge end is provided at the bottom of the bag filter 3. The normal temperature denitration catalyst powder intercepted by the bag filter 3 can be discharged through the discharge end.

[0037] A screw conveyor 31 is fixed to the discharge end of the bag-type dust collector 3, and discharge ports are arranged at the bottom of both ends of the screw conveyor 31. An intermediate bin 32 is arranged below one discharge port, and a pneumatic conveying device 49 is arranged at the bottom of the intermediate bin 32. An output bin 33 is arranged below the other discharge port. The discharge end of the bag-type dust collector 3 is located between the two discharge ports. Through the setting of the screw conveyor 31, the operation of the screw conveyor 31 can transport the room temperature denitration catalyst powder intercepted by the bag-type dust collector 3 to the intermediate bin 32 or the output bin 33, so as to realize the recovery of the room temperature denitration catalyst powder.

[0038] In Example 2, the dust removal and recovery structure includes a cyclone dust collector 10 and a bag dust collector 3. The air inlet end of the cyclone dust collector 10 is connected to the flue gas outlet of the fluidized bed reactor 2. The cyclone dust collector 10 is located above the catalyst nozzle 23. The room-temperature denitration catalyst powder separated by the cyclone dust collector 10 directly flows back to the bottom of the inner cavity of the main reaction section 24 of the fluidized bed reactor under the action of gravity, thereby realizing the recycling of the room-temperature denitration catalyst powder, and making this part of the room-temperature denitration catalyst powder flow back to the catalyst silo 1 through the pneumatic conveying device 3 8.

[0039] The air outlet end of the cyclone dust collector 10 is connected to the air inlet end of the bag dust collector 3, and the air outlet end of the bag dust collector 3 is connected to the induced draft fan 4. The bag dust collector 3 in Example 2 has the same structure as the bag dust collector 3 in Example 1. The bag dust collector 3 can be used to recover the room temperature denitrification catalyst powder.

[0040] The pneumatic conveying device four 9 is connected in series with the pneumatic conveying device three 8, and the wind source enters the pneumatic conveying device three 8 through the pneumatic conveying device four 9, so as to realize the recycling of the denitration catalyst powder at room temperature.

[0041] From the above description, it can be seen that during the use of the device, the room temperature denitrification catalyst powder can fully contact with the flue gas in the fluidized bed reactor 2, and the frequency of contact between the flue gas and the catalyst is high, which is beneficial to the catalytic reaction and improves the flue gas treatment efficiency; and the dust removal and recovery structure can be used to recover the room temperature denitrification catalyst powder, so that the room temperature denitrification catalyst powder can be recycled to save resources, and the room temperature denitrification catalyst powder can be regenerated online, so that the device can operate stably and ensure the flue gas treatment effect.

[0042] The specific process flow of denitrification of industrial flue gas using the above device is as follows:

[0043] S1, the normal temperature denitration catalyst powder is delivered to the catalyst silo 1 by air through the pneumatic conveying device 1 6, the material in the catalyst silo 1 falls into the gas conveying pipeline through the star-shaped ash discharge valve, and the powdered catalyst is delivered to the main reaction section 24 of the fluidized bed reactor by the pneumatic conveying device 2 7;

[0044] S2, the flue gas is introduced into the bottom air inlet section 21 of the fluidized bed reactor 2, and is sent to the main reaction section 24 of the fluidized bed reactor through the venturi tube section 22 for catalytic decomposition reaction, so as to decompose the NOx in the flue gas into N2 and O2. After the reaction, the gas is introduced into the dust removal and recovery structure after passing through the expansion section 25, and the dust removal and recovery structure recovers the catalyst to realize the recycling of the catalyst. The dust-removed gas is sent to the chimney 5 through the induced draft fan 4 to meet the emission standards.

[0045] The present invention is further described below through two embodiments of the present invention.

[0046] Example 1

[0047] The dust collection and recovery structure adopted in Example 1 is a bag dust collector 3 . The process flow of this embodiment is as follows: the normal temperature denitration catalyst powder C transported by truck enters the pneumatic conveying device 6, the Roots blower wind B2 delivers the normal temperature denitration catalyst powder C to the catalyst silo 1 under the wind pressure of the Roots blower, the material in the catalyst silo 1 falls into the pneumatic conveying device 7, the Roots blower wind B1 delivers the normal temperature denitration catalyst powder C to the fluidized bed reactor 2 by pneumatic conveying under the wind pressure of the Roots blower, the 100°C lime kiln flue gas A is introduced into the bottom air intake section 21, and is delivered to the main reaction section 24 of the fluidized bed reactor through the venturi section 22, and at the same time, the normal temperature denitration catalyst powder C delivered to the fluidized bed reactor 2 is blown into the main reaction section 24 of the fluidized bed reactor through the catalyst nozzle 23, the flue gas and the catalyst are intensely mixed and contacted in this section to react, and the post-reaction gas is passed through the expansion section 25 and then passed into the bag filter 3; the flue gas after the bag filter is sent to the chimney 5 for discharge through the induced draft fan 4 Purify flue gas D; the bag filter 3 is provided with backblowing, and the powder falling into the bottom of the bag filter is collected into the intermediate bin 32 through the screw conveyor 31, and then passed through the pneumatic conveying device four 9, which is connected in series with the pneumatic conveying device three 8. The powder in the pneumatic conveying device three 8 comes from the falling part of the fluidized bed reactor 2. The Roots blower wind three B3 sends the refluxed powdered catalyst to the catalyst silo 1 through the pneumatic conveying device four 9 and the pneumatic conveying device three 8 connected in series under the wind pressure of the Roots blower, so as to realize the circulation of the denitration catalyst powder C at room temperature; during the operation, the supplementary material is sent to the catalyst silo 1 through the catalyst powder inlet wind, and the material replacement process is to fall into the powder at the bottom of the bag filter, collect it into the output bin 33 through the reverse screw conveyor 31, and output the catalyst; the catalyst silo is provided with a heating and heat preservation device 11, and this function can be turned on as needed, so that the polluted catalyst powder C can be regenerated online.

[0048] Implementation effect: Denitrification rate ≥ 95%.

[0049] Example 2

[0050] The dust collection and recovery structure adopted in Example 2 is a cyclone dust collector 10 and a bag dust collector 3. The process flow of this embodiment is as follows: the normal temperature denitration catalyst powder C transported by truck enters the pneumatic conveying device 1 6, the Roots blower wind 2 B2 delivers the normal temperature denitration catalyst powder C to the catalyst silo 1 under the wind pressure of the Roots blower, and the material in the catalyst silo falls into the pneumatic conveying device 2 7, the Roots blower wind 1 B1 delivers the normal temperature denitration catalyst powder C to the fluidized bed reactor 2 by pneumatic conveying under the wind pressure of the Roots blower, and the 150°C coal-fired flue gas A is introduced into the bottom air inlet section 21, according to the text The chirpipe section 22 is sent to the main reaction section 24 of the fluidized bed reactor. At the same time, the normal temperature denitration catalyst powder C sent to the fluidized bed reactor 2 is blown into the main reaction section 24 of the fluidized bed reactor through the catalyst nozzle 23. The flue gas and the catalyst are intensely mixed and contacted in this section to react. After the reaction, the gas passes through the expansion section 25 and then passes through the cyclone dust collector 10. The catalyst collected by the cyclone dust collector is directly returned to the main reaction section 24 of the fluidized bed reactor. After the cyclone dust removal, the flue gas is then passed into the bag dust collector. 3; after bag dust removal, the flue gas is sent to the chimney 5 through the induced draft fan 4 to discharge the purified flue gas D; the bag dust collector 3 is provided with backblowing, and the powder falling into the bottom of the bag dust collector 3 is collected into the intermediate bin 32 through the screw conveyor 31, and then passed through the pneumatic conveying device four 9, which is connected in series with the pneumatic conveying device three 8. The powder in the pneumatic conveying device three 8 comes from the falling part of the fluidized bed reactor 2, and the Roots blower wind three B3 passes through the pneumatic conveying device four 9 and the pneumatic conveying device three 8 connected in series under the wind pressure of the Roots blower to send the refluxed powdered catalyst to the catalyst silo 1, so as to realize the recycling of the denitration catalyst powder C at room temperature; during the operation, the supplementary material is sent to the catalyst silo through the catalyst powder inlet wind, and the material replacement process is to fall into the powder at the bottom of the bag dust collector, collect it into the output bin 33 through the reverse screw conveyor 31, and output the catalyst; the catalyst silo is provided with a heating and heat preservation device 11, which can be turned on as needed, so that the polluted catalyst powder C can be regenerated online.

[0051] Implementation effect: Denitrification rate ≥ 95%.

[0052] From the above description, it can be seen that the fluidized bed denitrification process proposed by the present invention adopts a powdered denitrification catalyst at room temperature, uses a fluidized bed to react, recovers the catalyst in a bag filter and realizes a cyclic catalytic decomposition method to remove NOx in the flue gas. What occurs to NOx is a catalytic decomposition reaction, the reaction conditions are mild, and the process is safe; the substances produced are N2 and O2, which leave with the flue gas.

[0053] The standard parts used in the present invention can all be purchased from the market, and special-shaped parts can be customized according to the description in the specification and the drawings. The specific connection methods of each part adopt conventional means such as mature bolts, rivets, welding, etc. in the prior art. Machinery, parts and equipment all adopt conventional models in the prior art and will not be described in detail here. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field. Although the embodiments of the present invention have been shown and described, it can be understood by ordinary technicians in this field that various changes, modifications, substitutions and modifications can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the attached claims and their equivalents.

Claims

1. A fluidized bed denitration process, the device used in the process comprises a catalyst silo (1), a fluidized bed reactor (2), a dust removal and recovery structure, a chimney (5), a pneumatic conveying device 1 (6), a pneumatic conveying device 2 (7), a pneumatic conveying device 3 (8) and a pneumatic conveying device 4 (9), characterized in that: The catalyst silo (1) stores room temperature denitration catalyst powder, a pneumatic conveying device (1) is provided at the feed end of the catalyst silo (1), the room temperature denitration catalyst powder is conveyed into the catalyst silo (1) via the pneumatic conveying device (6), the discharge end of the catalyst silo (1) is connected to the fluidized bed reactor (2) via the pneumatic conveying device (7), and a heating and heat preservation device (11) is provided on the catalyst silo (1); The fluidized bed reactor (2) is provided with an air inlet section (21), a venturi tube section (22), a fluidized bed reactor main reaction section (24) and an expansion section (25) in order from bottom to top; a catalyst nozzle (23) is provided at the bottom end of the fluidized bed reactor main reaction section (24); the discharge end of the pneumatic conveying device (2) is connected to the feed end of the catalyst nozzle (23); a discharge port is provided at the bottom of the fluidized bed reactor (2); and the normal temperature denitration catalyst powder dropped through the discharge port is refluxed to the catalyst silo (1) via the pneumatic conveying device (3); The top of the fluidized bed reactor (2) is provided with a flue gas outlet, which is connected to the air inlet end of a dust removal and recovery structure. The dust removal and recovery structure filters the denitration gas and recovers the normal temperature denitration catalyst powder. The recovered normal temperature denitration catalyst powder eventually flows back to the catalyst silo (1). The air outlet end of the dust removal and recovery structure is connected to a chimney (5) via an induced draft fan (4); The fluidized bed denitrification process includes the following process flow: S1, the normal temperature denitration catalyst powder is delivered to the catalyst silo (1) by air through the pneumatic conveying device 1 (6), the material in the catalyst silo (1) falls into the gas conveying pipeline through the star-shaped ash discharge valve, and the powdered catalyst is delivered to the main reaction section (24) of the fluidized bed reactor through the pneumatic conveying device 2 (7); S2, the flue gas is introduced into the bottom air inlet section (21) of the fluidized bed reactor (2), and is sent to the main reaction section (24) of the fluidized bed reactor through the venturi section (22) for catalytic decomposition reaction, thereby decomposing NOx in the flue gas into N2 and O2. After the reaction, the gas is introduced into the dust removal and recovery structure after passing through the expansion section (25). The dust removal and recovery structure recovers the catalyst to realize the recycling of the catalyst. The dust-removed gas is sent to the chimney (5) through the induced draft fan (4) to meet the emission standards.

2. A fluidized bed denitrification process according to claim 1, characterized in that: The dust removal and recovery structure comprises a bag filter (3), the air inlet end of the bag filter (3) is connected to the smoke outlet of the fluidized bed reactor (2), and the air outlet end of the bag filter (3) is connected to the induced draft fan (4).

3. A fluidized bed denitrification process according to claim 1, characterized in that: The dust removal and recovery structure comprises a cyclone dust collector (10) and a bag dust collector (3); the air inlet end of the cyclone dust collector (10) is connected to the flue gas outlet of the fluidized bed reactor (2); the air outlet end of the cyclone dust collector (10) is connected to the air inlet end of the bag dust collector (3); the air outlet end of the bag dust collector (3) is connected to the induced draft fan (4); the room temperature denitration catalyst powder separated by the cyclone dust collector (10) is directly refluxed to the main reaction section (24) of the fluidized bed reactor via its bottom discharge port.

4. A fluidized bed denitration process according to claim 3, characterized in that: The cyclone dust collector (10) is located above the catalyst nozzle (23), and the room temperature denitration catalyst powder separated by the cyclone dust collector (10) directly flows back to the bottom of the inner cavity of the main reaction section (24) of the fluidized bed reactor under the action of gravity.

5. A fluidized bed denitration process according to claim 2 or 4, characterized in that: A screw conveyor (31) is fixed to the discharge end of the bag dust collector (3), and discharge ports are provided at the bottom of both ends of the screw conveyor (31). An intermediate hopper (32) is provided below one of the discharge ports, and a pneumatic conveying device (9) is provided at the bottom of the intermediate hopper (32). An output hopper (33) is provided below the other discharge port, and the discharge end of the bag dust collector (3) is located between the two discharge ports.

6. A fluidized bed denitration process according to claim 5, characterized in that: A backflush assembly is provided in the bag dust collector (3), and the bag dust collector (3) is a pulse bag dust collector.

7. A fluidized bed denitration process according to claim 6, characterized in that: The pneumatic conveying device four (9) is connected in series with the pneumatic conveying device three (8), and the wind source enters the pneumatic conveying device three (8) through the pneumatic conveying device four (9).

8. A fluidized bed denitration process according to claim 6, characterized in that: A baffle structure is provided in the expansion section (25), and the baffle structure is used to intercept the normal temperature denitration catalyst powder.

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