Flue gas dedusting and denitration device

Abstract

The application provides a flue gas dedusting and denitration device, wherein the dust outlet of the air channel of the flue gas dedusting and denitration device is close to the flue gas outlet, that is, the deposition direction of the dust in the air channel is the same as the air flow direction, the dust deposition does not affect the flue gas flow, the secondary flying phenomenon is eliminated, the dust deposition efficiency in the flue gas is relatively high, and the suction force of the negative pressure generated by the suction component is used to clean the dust in the air channel and the filter screen, so that the dust hardening phenomenon on the surface of the filter screen is greatly reduced, and the problem of the temperature reduction of the high-temperature flue gas caused by the dust removal process of the filter screen is alleviated.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment technology, and in particular to a flue gas dust removal and denitrification device. Background Technology

[0002] To address the issues of alkali metals and heavy metals in flue gas from industries such as cement, non-ferrous metals, and chemicals, which can easily lead to catalyst blockage, poisoning, and failure, a dust collector is first used to purify the dust-laden raw flue gas under conditions where the flue gas temperature is between 280℃ and 420℃ and contains a large amount of dust. Then, the dust-free, high-temperature flue gas enters the SCR denitrification reactor for denitrification, ensuring that the SCR catalyst operates in a relatively clean flue gas environment. High-temperature, low-dust denitrification can reduce catalyst wear, extend catalyst lifespan, reduce flue gas operating resistance, and ensure long-term stable operation of the unit.

[0003] Currently, flue gas treatment devices typically have an exhaust gas inlet at the bottom and an exhaust gas outlet at the top. The casing contains a dry filter bag area and a denitrification zone. The exhaust gas first passes through the dry filter bag area and then through the denitrification zone. The opening of the dry filter bag faces the exhaust gas inlet. After a period of use, the dry filter bag needs to be cleaned. Currently, the cleaning method is pulse-jet cleaning, using ambient temperature compressed air. Continuously blowing in cool compressed air causes ash to clump on the filter bag, making it difficult to remove and also lowering the temperature of the high-temperature flue gas, affecting the efficiency of the denitrification reaction. The bottom of the equipment needs to have an ash collection component to collect the fallen ash, meaning the airflow can only enter the dust removal zone from the periphery of the equipment, resulting in poor airflow uniformity. The direction of ash falling is opposite to the airflow direction, causing secondary ash re-entrainment and affecting ash removal efficiency. The filter bag arrangement can only be vertical; a horizontal arrangement cannot be used to reduce the equipment height or optimize the airflow direction, preventing straight-in-straight-out airflow. The dry filter bag is cylindrical, resulting in high airflow resistance.

[0004] Overcoming at least one of the aforementioned technical defects is a technical problem that those skilled in the art need to solve. Summary of the Invention

[0005] The purpose of this invention is to provide a flue gas dust removal and denitrification device with high dust removal efficiency and to alleviate filter screen surface caking.

[0006] This invention provides a flue gas dust removal and denitrification device, comprising a housing having a flue gas inlet and a flue gas outlet, wherein the housing has a dust removal and denitrification zone, the dust removal and denitrification zone comprising a plurality of air ducts surrounded by a filter screen, the air ducts being arranged at intervals, the dust removal and denitrification zone further comprising a denitrification catalyst unit disposed between adjacent air ducts, the air ducts extending along the direction from the flue gas inlet to the flue gas outlet, and each end of the air duct having a first opening and a second opening respectively, the first opening facing the flue gas inlet and having an open structure, the second opening being close to the flue gas outlet, and the second opening being selectively openable or closed;

[0007] It also includes a suction component for providing suction power to extract dust from the airway;

[0008] When the denitrification process is in operation, the second port is closed, and the flue gas enters the denitrification catalyst unit through the filter screen, and then flows to the flue gas outlet through the denitrification catalyst unit;

[0009] When cleaning is in progress, the second port is connected to the suction component to generate suction on the inside of the air passage and the surface of the filter screen.

[0010] The flue gas dust removal and denitrification device provided by this invention has a dust outlet in the air duct close to the flue gas outlet, meaning that the dust deposition direction in the air duct is the same as the airflow direction. Dust deposition will not affect the flue gas flow, eliminating secondary re-entrainment. Furthermore, the dust deposition efficiency in the flue gas is relatively high. In addition, this invention uses the negative pressure suction force generated by the suction component to clean the air duct and filter screen. Negative pressure cleaning greatly reduces the occurrence of dust caking on the filter screen surface, thereby mitigating the problem of high-temperature flue gas temperature drop during filter screen dust removal.

[0011] Optionally, the filter screen is fixed to the denitrification catalyst unit, and the denitrification catalyst unit has at least its gas passing surface covered by the filter screen.

[0012] Optionally, a predetermined gap exists between the filter screen and the denitrification catalyst unit;

[0013] Alternatively / and, the first end face of the denitrification catalyst unit near the flue gas inlet is a closed face, and the sidewall of the denitrification catalyst unit and the second end face near the flue gas outlet allow flue gas to pass through.

[0014] Optionally, the housing further includes an injection zone, which is equipped with a first injection component for injecting a denitrification reducing agent into the flue gas; the injection zone is located upstream of the dust removal and denitrification zone.

[0015] Alternatively, the housing may further include an injection zone, which is provided with a first injection component and a second injection component. The first injection component is used to inject a denitrification reducing agent into the flue gas. The injection zone is located upstream of the dust removal and denitrification zone. The second injection component is used to inject a desulfurizing agent into the flue gas. The second injection component is located downstream of the first injection component.

[0016] Optionally, the housing is vertically arranged, and the flue gas inlet is located above the flue gas outlet.

[0017] Optionally, the airway is a Venturi structure airway, with a smaller size in the middle and a larger size closer to both ends.

[0018] Optionally, a dust collection trough is provided at the second opening of each of the air passages, and the flue gas dust removal and denitrification device also has a dust conveying pipe, which can be connected to each of the dust collection troughs, and the suction component extracts dust from the inside of each of the dust collection troughs through the dust conveying pipe.

[0019] Optionally, a heat recovery component is also included, disposed outside the housing; the heat recovery component is connected to the ash outlet of the suction component, and the heat recovery component is used to recover part of the heat of the dust flowing through it;

[0020] Alternatively / and, the ash conveying pipe is inclined, and the height of the ash conveying pipe gradually decreases along the direction of dust flow in the ash conveying pipe.

[0021] Optionally, it also includes a heat exchange pipeline located in the high-temperature flue gas pipe area of ​​the shell, the high-temperature flue gas pipe area being located downstream of the dust removal and denitrification zone; after the dust has been heated by the heat recovery component, it returns to the heat recovery component after exchanging heat with the flue gas flowing through the high-temperature flue gas pipe area via the heat exchange pipeline.

[0022] Or / and, it also includes a high-temperature ash storage tank, disposed on the connecting pipeline between the heat recovery component and the suction component.

[0023] Optionally, a cryogenic ash storage tank is also included, which is located on the connecting pipe between the dust outlet of the heat recovery component and the heat exchange pipeline and is located outside the shell. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of a flue gas dust removal and denitrification device in a specific embodiment of the present invention;

[0025] Figure 2 for Figure 1 A magnified view of a portion of point A in the middle;

[0026] Figure 3This is a top view schematic diagram of the combination of the denitrification catalyst unit and the gas channel in a specific embodiment of the present invention;

[0027] Figure 4 This is a top view schematic diagram of the combination of the denitrification catalyst unit and the gas channel in another specific embodiment of the present invention.

[0028] Figures 1 to 4 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0029] 1-Shell, 1a-Flue gas inlet, 1b-Flue gas outlet, 2-Ammonia injection device, 21-First spray component, 31-Second spray component, 3-Desulfurizing agent injection device, 4a-Gas duct; 4a1-First port, 4a2-Second port, 4-Filter screen, 5-Denitrification catalyst unit, 6-Ash collection tank, 7-Ash conveying pipe, 8-Suction component, 9-High temperature ash storage tank, 10-Flow control valve, 11-Heat recovery component, 12-Low temperature ash storage tank, 13-Discharge port, 14-Transfer pump, 15-Heat exchange pipeline. Detailed Implementation

[0030] The features and exemplary embodiments of various aspects of this application will now be described in detail. In order to make the purpose, technical solution and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] The terms "first" and "second" used in this article are used only for the convenience of describing two or more structures or components that are identical or similar in structure and / or function, and do not indicate any special limitation on order and / or importance.

[0032] Please refer to Figures 1 to 4 , Figure 1 This is a cross-sectional view of a flue gas dust removal and denitrification device in a specific embodiment of the present invention; Figure 2 for Figure 1 A magnified view of a portion of point A in the middle; Figure 3 This is a top view schematic diagram of the combination of the denitrification catalyst unit and the gas channel in a specific embodiment of the present invention; Figure 4 This is a top view schematic diagram of the combination of the denitrification catalyst unit and the gas channel in another specific embodiment of the present invention.

[0033] This invention provides a flue gas dust removal and denitrification device, comprising a housing 1, which has a flue gas inlet 1a and a flue gas outlet 1b. The flue gas inlet 1a is used to connect to the main flue gas pipeline of a boiler or other flue gas generating component, and the flue gas generated by the flue gas generating component can enter the interior of the housing 1 along the main flue gas pipeline. The flue gas outlet 1b of the housing 1 can be connected to a downstream flue gas pipeline through a pipe, that is, the flue gas entering the interior of the housing 1 from the flue gas inlet 1a is treated and can be discharged from the flue gas outlet 1b of the housing 1 to a pipeline or the atmosphere outside the housing 1. The size of the flue gas inlet 1a and the flue gas outlet 1b of the housing 1 can be determined according to the specific product.

[0034] In this invention, the high-temperature flue gas has a dust removal and denitrification zone inside the casing 1. This zone includes several air ducts 4a enclosed by filter screens 4. Each air duct 4a extends approximately from the flue gas inlet 1a to the flue gas outlet 1b. The size and shape of each air duct 4a can be approximately the same, or they can be different. The air ducts 4a can be parallel to each other. For example… Figure 1 Each airway 4a extends vertically, and the cross-section of each airway 4a is approximately the same. Figure 3 The text provides a specific example of an airway 4a having a long, narrow cross-section. Figure 4 A specific example of a square cross-section for the airway 4a is shown. However, those skilled in the art may also arrange a non-linear airway 4a.

[0035] In this invention, the gas ducts 4a are arranged at intervals. The dust removal and denitrification zone also includes a denitrification catalyst unit disposed between adjacent gas ducts 4a. The gas ducts 4a extend along the direction from the flue gas inlet 1a to the flue gas outlet 1b, and the gas ducts 4a have a first port 4a1 and a second port 4a2. The first port 4a1 faces the side of the flue gas inlet 1a and is an open structure. The second port 4a2 is close to the side of the flue gas outlet 1b. The second port 4a2 can be selectively opened or closed. The opening or closing of the second port 4a2 can be achieved by a switching valve. There are various types of switching valves, which will not be described in detail in this article.

[0036] The dust removal and denitrification zone also includes a denitrification catalyst module 5 set between adjacent air ducts 4a. The catalyst in the denitrification catalyst module 5 can be composed of spherical catalysts connected together. The reaction flue gas can react through the gaps of the spherical catalyst elements, which greatly increases the contact area and contact time between the flue gas and the catalyst, thereby improving the reaction efficiency.

[0037] The flue gas dust removal and denitrification device of the present invention also includes a suction component 8, which is used to provide suction power to extract dust from the air duct 4a; when the dust removal is in operation, the second port 4a2 is connected to the suction component 8 to generate suction on the air duct 4a and the surface of the filter screen 4, so that the dust inside the air duct 4a and the surface of the filter screen 4 will be sucked out of the housing 1.

[0038] The suction component 8 can be a pump, which can be centrifugal, axial, or cross-flow type. When the filter screen 4 forming the air passage 4a needs to be cleaned, the second port 4a2 can be opened and the suction component 8 can be activated. This will create a negative pressure inside the air passage 4a, and the dust deposited inside the air passage 4a and the dust attached to the surface of the filter screen 4 will be sucked away.

[0039] When the denitrification is in operation, the second port 4a2 is closed, and the flue gas enters the denitrification catalyst module 5 through the filter screen 4, and flows to the flue gas outlet 1b through the denitrification catalyst module 5.

[0040] In the above embodiments, the filter screen 4 can be fixed to the denitrification catalyst module 5, and the denitrification catalyst module 5 is provided with the filter screen 4 at least on the outer surface of the air inlet. That is, the end of the denitrification catalyst module 5 facing the flue gas inlet 1a is a closed structure, while the end facing the flue gas outlet 1b allows flue gas to pass through.

[0041] The flue gas dust removal and denitrification device provided by this invention has a dust outlet of air duct 4a close to the flue gas outlet 1b, meaning that the dust deposition direction in air duct 4a is the same as the airflow direction. Dust deposition will not affect the flue gas flow, eliminating secondary re-entrainment. Furthermore, the dust deposition efficiency in the flue gas is relatively high. In addition, this invention uses the negative pressure suction force generated by the suction component 8 to clean the air duct 4a and the filter screen 4. Negative pressure cleaning greatly reduces the occurrence of dust caking on the surface of the filter screen 4, thereby mitigating the problem of high-temperature flue gas temperature drop during the dust removal process of the filter screen 4.

[0042] In one specific example, the filter screen 4 can be fixed to the denitrification catalyst module 5. At least the gas-passing surface of the denitrification catalyst module 5 is covered by the filter screen 4. Of course, to facilitate the fixing of the filter screen 4, it can also cover the non-gas-passing surface of the denitrification catalyst module 5, for example, at the closed end of the denitrification catalyst module 5 or on the side adjacent to the housing 1. A predetermined gap exists between the filter screen 4 and the denitrification catalyst module 5, which prevents friction and damage between the filter screen 4 and the catalyst. Simultaneously, the filter screen 4 serves as a protective mesh for the denitrification catalyst module 5, preventing catalyst blockage, poisoning, and failure. The two are integrated, and their installation and replacement can be performed as a whole module, reducing workload.

[0043] There are various ways to fix the filter screen 4 and the denitrification catalyst module 5, such as welding, bolting or riveting.

[0044] The first end face 52 of the denitrification catalyst module 5 near the flue gas inlet 1a is a closed surface. The side wall of the denitrification catalyst module 5 and the second end face 51 near the flue gas outlet 1b allow flue gas to pass through. The side wall is opposite to the air passage 4a formed by the filter screen 4. The flue gas in the air passage 4a enters the interior of the denitrification catalyst through the side wall of the denitrification catalyst and finally flows out of the denitrification catalyst module 5 from the second end face 51.

[0045] Beams and columns can be installed inside the shell 1, and the denitrification catalyst module 5 can be placed on the beams and columns. The beams and columns are welded or snapped to the shell 1 for easy installation.

[0046] Normally, before passing through the catalyst, the flue gas needs to be injected with a denitrification reducing agent. In order to improve the flue gas denitrification efficiency and the integration of the equipment, the casing 1 of the flue gas dust removal and denitrification device in this invention also integrates an injection zone. The injection zone is equipped with a first injection component 21 for injecting the denitrification reducing agent into the flue gas. The injection zone is located upstream of the dust removal and denitrification zone. The first injection component 21 can be a spray pipe or nozzle arranged according to a predetermined design. The ammonia injection device 2 connected to the first injection component 21 can be set outside the casing 1. The casing 1 can be relatively small in size, which is beneficial for arrangement in a small space environment and has high flexibility of use.

[0047] To enable the device to remove more harmful substances from the flue gas, a second injection component 31 can be provided in the injection zone inside the housing 1. The second injection component 31 is used to inject desulfurizing agent into the flue gas; the second injection component 31 is located downstream of the first injection component 21. Similarly, the sulfur injection device connected to the second injection component 31 can also be located outside the housing 1 to improve the flexibility of use and installation.

[0048] In this invention, the housing 1 can be vertically arranged, with the flue gas inlet 1a located above the flue gas outlet 1b. This results in higher ash removal efficiency in the flue gas.

[0049] Of course, housing 1 can also be set horizontally.

[0050] In the above embodiments, the air passage 4a is a Venturi structure air passage 4a, with a smaller size in the middle and a larger size closer to both ends. This embodiment utilizes the principle of the Venturi structure to achieve rapid dust removal and improve dust removal efficiency.

[0051] Of course, the shape of airway 4a can also be cylindrical, or a simpler structure such as a polygonal column.

[0052] In one specific example, a dust collection trough 6 is provided at the second opening 4a2 of each air passage 4a, and the flue gas dust removal and denitrification device also has a dust conveying pipe 7, which can be connected to each dust collection trough 6. The suction component 8 extracts the dust inside each dust collection trough 6 through the dust conveying pipe 7.

[0053] In this embodiment, when the device is working normally (denitrification), the dust in the air duct 4a can be temporarily stored in the dust collection tank 6 of the air duct 4a. During the dust removal operation, the dust on the dust collection tank 6, air duct 4a, and filter screen 4 is sucked to the outside by the suction component 8. This structure does not require a dust hopper to be set inside the shell 1, and the volume of the shell 1 is further reduced.

[0054] The ash conveying pipe 7 is inclined, and its height gradually decreases along the flow direction of the dust to facilitate the outflow of dust.

[0055] To reduce heat loss, the device of the present invention may further include a heat recovery component 11 disposed outside the housing 1; the heat recovery component 11 is connected to the ash outlet of the suction component 8, and the heat recovery component 11 is used to recover part of the heat of the dust flowing through it. In this way, part of the heat of the dust can be recovered and reused, reducing energy loss.

[0056] Furthermore, the flue gas dust removal and denitrification device of the present invention is further provided with a heat exchange pipeline located in the high-temperature flue gas pipe area of ​​the shell 1, which is downstream of the dust removal and denitrification zone; the dust after heat exchange with the heat recovery component 11 returns to the heat recovery component 11 after heat exchange with the flue gas flowing through the high-temperature flue gas pipe area through the heat exchange pipeline. In order to improve the fluidity of the dust, a pump 14 can be further added to the circulation loop formed by the heat exchange pipeline and the heat recovery component 11.

[0057] In this way, the dust can further absorb the heat from the purified flue gas, and the heat-absorbing dust re-enters the heat recovery component 11 for heat exchange, further reducing system energy consumption.

[0058] In one example, the present invention includes a high-temperature ash storage tank 9, which is disposed on the connecting pipeline between the heat recovery component 11 and the suction component 8.

[0059] Furthermore, the present invention also includes a low-temperature ash storage tank 12, which is located on the connecting pipe between the dust outlet of the heat recovery component 11 and the heat exchange pipeline and is located outside the shell 1, thereby improving the overall stability of the system operation. The low-temperature ash storage tank 12 may also be provided with an ash discharge port 13, through which some of the dust inside can be discharged to the outside.

[0060] Flow control valves can also be installed on each section of the pipeline. The figure shows a flow control valve 10 installed on the connecting pipeline between the high-temperature ash storage tank 9 and the heat recovery component 11 to control the opening of the pipeline.

[0061] The flue gas dust removal and denitrification device provided by the present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A flue gas dedusting and denitration device, characterized in that, The device includes a housing with a flue gas inlet and a flue gas outlet. The housing has a dust removal and denitrification zone inside. The dust removal and denitrification zone includes a plurality of air ducts surrounded by a filter screen. The air ducts are arranged at intervals. The dust removal and denitrification zone also includes a denitrification catalyst unit disposed between adjacent air ducts. The air ducts extend along the direction from the flue gas inlet to the flue gas outlet. Each end of the air duct has a first opening and a second opening. The first opening faces the flue gas inlet and is open. The second opening is close to the flue gas outlet and can be selectively opened or closed. It also includes a suction component for providing suction power to remove dust from the airway; When the denitrification process is in operation, the second port is closed, and the flue gas enters the denitrification catalyst unit through the filter screen, and then flows to the flue gas outlet through the denitrification catalyst unit; When cleaning is in progress, the second port is connected to the suction component to generate suction on the inside of the air passage and the surface of the filter screen.

2. The flue gas dust removal and denitrification device as described in claim 1, characterized in that, The filter screen is fixed to the denitrification catalyst unit, and the denitrification catalyst unit has at least its gas passing surface covered by the filter screen.

3. The flue gas dust removal and denitrification device as described in claim 2, characterized in that, There is a predetermined gap between the filter screen and the denitrification catalyst unit; Alternatively / and, the first end face of the denitrification catalyst unit near the flue gas inlet is a closed face, and the sidewall of the denitrification catalyst unit and the second end face near the flue gas outlet allow flue gas to pass through.

4. The flue gas dust removal and denitrification device as described in claim 1, characterized in that, The housing also includes an injection zone, which is equipped with a first injection component for injecting a denitrification reducing agent into the flue gas; the injection zone is located upstream of the dust removal and denitrification zone. Alternatively, the housing may further include an injection zone, which is provided with a first injection component and a second injection component. The first injection component is used to inject a denitrification reducing agent into the flue gas. The injection zone is located upstream of the dust removal and denitrification zone. The second injection component is used to inject a desulfurizing agent into the flue gas. The second injection component is located downstream of the first injection component.

5. The flue gas dust removal and denitrification device as described in claim 1, characterized in that, The housing is vertically arranged, and the flue gas inlet is located above the flue gas outlet.

6. The flue gas dust removal and denitrification device according to any one of claims 1 to 5, characterized in that, The airway is a Venturi structure airway, with a smaller size in the middle and a larger size closer to both ends.

7. The flue gas dust removal and denitrification device according to any one of claims 1 to 5, characterized in that, Each of the air passages is provided with a dust collection trough at its second opening. The flue gas dust removal and denitrification device also has a dust conveying pipe, which can be connected to each of the dust collection troughs. The suction component extracts dust from the inside of each of the dust collection troughs through the dust conveying pipe.

8. The flue gas dust removal and denitrification device as described in claim 7, characterized in that, It also includes a heat recovery component, which is disposed outside the housing; the heat recovery component is connected to the ash outlet of the suction component, and the heat recovery component is used to recover part of the heat of the dust flowing through it; Alternatively / and, the ash conveying pipe is inclined, and the height of the ash conveying pipe gradually decreases along the direction of dust flow in the ash conveying pipe.

9. The flue gas dust removal and denitrification device as described in claim 8, characterized in that, It also includes a heat exchange pipeline located in the high-temperature flue gas pipe area of ​​the shell, which is located downstream of the dust removal and denitrification zone; after the dust has been heated by the heat recovery component, it returns to the heat recovery component after exchanging heat with the flue gas flowing through the high-temperature flue gas pipe area through the heat exchange pipeline. Or / and, it also includes a high-temperature ash storage tank, disposed on the connecting pipeline between the heat recovery component and the suction component.

10. The flue gas dust removal and denitrification device as described in claim 9, characterized in that, It also includes a low-temperature ash storage tank, which is located on the connecting pipe between the dust outlet of the heat recovery component and the heat exchange pipeline and is located outside the shell.

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