Urea pyrolysis device based on SCR denitration system

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By using a urea pyrolysis device in the SCR denitrification system, the high-temperature flue gas from the boiler is mixed with urea solution and pyrolyzed into an NH3-based mixture, which provides a reducing agent for the SCR denitrification reaction. This solves the problems of difficult transportation and storage management of NH3 systems and limited sources, and achieves ultra-low emissions of nitrogen oxides from boiler flue gas.

CN224485487UActive Publication Date: 2026-07-14ANHUI JINSENYUAN ENVIRONMENTAL PROTECTION ENG CO LTD

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Patent Information

Authority / Receiving Office: CN · China
Patent Type: Utility models(China)
Current Assignee / Owner: ANHUI JINSENYUAN ENVIRONMENTAL PROTECTION ENG CO LTD
Filing Date: 2025-06-05
Publication Date: 2026-07-14

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Abstract

The utility model provides a kind of urea pyrolysis device based on SCR denitration system, comprising: air inlet pipe, one end of air inlet pipe is fixedly installed with spraying device, one end of spraying device is fixedly installed with pyrolysis device, one end of pyrolysis device is fixedly installed with air outlet pipe, one end of air outlet pipe is fixedly installed with inlet pipe, the surface of inlet pipe is fixedly installed with inlet valve, one end of air outlet pipe is fixedly installed with reactor.The utility model provides a kind of urea pyrolysis device based on SCR denitration system, by air inlet pipe cooperation spraying device, pyrolysis device, air outlet pipe, inlet pipe, inlet valve, reactor, first layer catalyst, second layer catalyst, third layer catalyst, outlet valve and heat exchange device, boiler high-temperature flue gas is sent to urea pyrolysis device, makes urea solution pyrolysis vaporization as NH base mixture, provides reducing agent for SCR denitration reaction, guarantee chemical reaction to carry out, boiler flue gas nitrogen oxide reaches ultra-low emission requirement.

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Description

Technical Field

[0001] This utility model relates to the field of flue gas denitrification, and in particular to a urea pyrolysis device based on an SCR denitrification system. Background Technology

[0002] There are two main types of flue gas denitrification technology: dry and wet. Compared with wet flue gas denitrification technology, the main advantages of dry flue gas denitrification technology are: lower basic investment, simpler equipment and process, higher NOx removal efficiency, no wastewater or waste treatment, and less likelihood of causing secondary pollution.

[0003] Currently, various boiler flue gas requires denitrification. Due to the limitations of on-site safety management in the SCR denitrification system's reducing agent supply system, the transportation and storage of the reducing agent NH3 system are too difficult to manage, and the source of reducing agent NH3 is restricted, which affects the flue gas denitrification process.

[0004] Therefore, it is necessary to provide a urea pyrolysis device based on an SCR denitrification system to solve the above-mentioned technical problems. Utility Model Content

[0005] This invention provides a urea pyrolysis device based on an SCR denitrification system, which solves the problems of the current NH3 reducing agent system, such as the difficulty in transportation and storage management, and the limited source of NH3 reducing agent, which affect the flue gas denitrification process.

[0006] To solve the above-mentioned technical problems, this utility model provides a urea pyrolysis device based on an SCR denitrification system, comprising:

[0007] An air inlet pipe is provided, with a spraying device fixedly installed at one end, a pyrolysis device fixedly installed at one end of the spraying device, an air outlet pipe fixedly installed at one end of the pyrolysis device, an inlet pipe fixedly installed at one end of the air outlet pipe, an inlet valve fixedly installed on the surface of the inlet pipe, a reactor fixedly installed at one end of the air outlet pipe, a first layer of catalyst, a second layer of catalyst, and a third layer of catalyst disposed inside the reactor, a heat exchange device fixedly installed at one end of the reactor, and an outlet valve disposed at one end of the reactor.

[0008] Preferably, one end of the reactor is connected to the heat exchange device via a pipe, and the outlet valve is fixedly installed on the surface of the pipe.

[0009] Preferably, a mixing pipe is fixedly installed at one end of the air intake pipe, and a delivery pipe is fixedly connected to one end of the mixing pipe.

[0010] Preferably, the mixing tube is rotatably connected to the inside of a rotating tube, and the rotating tube is threadedly connected to a threaded sleeve inside.

[0011] Preferably, a sealing sleeve is slidably connected inside the rotating tube, and a connecting tube is fixedly connected inside the sealing sleeve.

[0012] Preferably, the threaded sleeve is also fixedly installed on the surface of the connecting pipe.

[0013] Preferably, a diversion pipe is fixedly installed at one end of the connecting pipe, a plurality of nozzles are fixedly installed on the surface of the diversion pipe, and telescopic rods are fixedly installed at both ends of the diversion pipe.

[0014] Compared with related technologies, the urea pyrolysis device based on an SCR denitrification system provided by this utility model has the following beneficial effects:

[0015] This invention provides a urea pyrolysis device based on an SCR denitrification system. The device consists of an inlet pipe, a spraying device, a pyrolysis unit, an outlet pipe, an inlet pipe, an inlet valve, a reactor, a first layer catalyst, a second layer catalyst, a third layer catalyst, an outlet valve, and a heat exchanger. High-temperature flue gas from the boiler is then sent to the urea pyrolysis unit, where the urea solution is pyrolyzed and vaporized into an NH-based mixture. This mixture provides a reducing agent for the SCR denitrification reaction, ensuring the chemical reaction proceeds and achieving ultra-low nitrogen oxide emissions from the boiler flue gas. Attached Figure Description

[0016] Figure 1 A schematic diagram of the structure of a first embodiment of a urea pyrolysis device based on an SCR denitrification system provided by this utility model;

[0017] Figure 2 A schematic diagram of the structure of a second embodiment of a urea pyrolysis device based on an SCR denitrification system provided by this utility model;

[0018] Figure 3 for Figure 2 A cross-sectional structural schematic diagram of the mixing tube shown;

[0019] Figure 4 for Figure 3 The enlarged schematic diagram of part A shown below;

[0020] Figure 5 for Figure 3 The enlarged schematic diagram of part B is shown.

[0021] The diagram is labeled as follows: 1. Inlet pipe; 2. Spraying device; 3. Pyrolysis device; 4. Outlet pipe; 5. Inlet pipe; 6. Inlet valve; 7. Reactor; 8. First layer catalyst; 9. Second layer catalyst; 10. Third layer catalyst; 11. Outlet valve; 12. Heat exchanger.

[0022] 13. Mixing pipe, 14. Conveying pipe, 15. Rotating pipe, 16. Sealing sleeve, 17. Threaded sleeve, 18. Connecting pipe, 19. Diverting pipe, 20. Nozzle, 21. Telescopic rod. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0024] First Embodiment

[0025] Please refer to the following: Figure 1 ,in, Figure 1 A schematic diagram of the structure of a first embodiment of a urea pyrolysis device based on an SCR denitrification system provided by this utility model. A urea pyrolysis device based on an SCR denitrification system includes:

[0026] An air inlet pipe 1 is provided, with a spraying device 2 fixedly installed at one end of the air inlet pipe 1, a pyrolysis device 3 fixedly installed at one end of the spraying device 2, an air outlet pipe 4 fixedly installed at one end of the pyrolysis device 3, an inlet pipe 5 fixedly installed at one end of the air outlet pipe 4, an inlet valve 6 fixedly installed on the surface of the inlet pipe 5, a reactor 7 fixedly installed at one end of the air outlet pipe 4, a first catalyst layer 8, a second catalyst layer 9, and a third catalyst layer 10 disposed inside the reactor 7, a heat exchange device 12 fixedly installed at one end of the reactor 7, and an outlet valve 11 disposed at one end of the reactor 7.

[0027] One end of the reactor 7 is connected to the heat exchange device 12 via a pipe, and the outlet valve 11 is fixedly installed on the surface of the pipe.

[0028] About 40% of the urea solution is purchased externally or prepared by dissolving it, because the transportation, storage and management of urea are relatively safe and the sources are wide.

[0029] This ensures that the NOx emissions from the flue gas discharged from the heat exchange device 12 are ≤50mg / Nm3, meeting the ultra-low emission standards for boiler (kiln) flue gas.

[0030] Principle of urea pyrolysis reaction: pyrolysis of CO(NH2)2 → NH3 + HCNO

[0031] In the SCR reactor, NO is reduced through the following reaction:

[0032] 4NO + 4NH3 + O2 → 3N2 + 6H2O

[0033] 6NO + 4NH3 → 5N2 + 6H2O

[0034] When oxygen is present in the flue gas, the first reaction proceeds preferentially; therefore, there is a one-to-one relationship between ammonia consumption and NO reduction. In boiler (kiln) flue gas, NO2 typically accounts for about 5% of the total NOx concentration. The reactions involving NO2 are as follows:

[0035] 2NO2 + 4NH3 + O2 → 3N2 + 6H2O

[0036] 6NO2 + 8NH3 → 7N2 + 12H2O

[0037] After preliminary purification, the high-temperature flue gas from various boilers enters the urea pyrolysis unit 3. The urea solution is pyrolyzed into an NH3-based mixture by utilizing the high temperature of the flue gas. This mixture is then mixed with the flue gas from the inlet of the SCR denitrification reactor and enters the denitrification reactor to undergo a series of chemical reduction reactions. This reduces the nitrogen oxides in the flue gas into harmless N2 and H2O, achieving the purpose of denitrification.

[0038] The working principle of the urea pyrolysis device based on the SCR denitrification system provided by this utility model is as follows:

[0039] During operation, high-temperature flue gas from the boiler at approximately 550°C enters through the inlet pipe 1 and mixes with approximately 40% urea solution injected 2 before entering the urea pyrolysis device 3. After pyrolysis, the ammonia-containing mixture mixes through the outlet pipe 4 with the boiler flue gas inlet pipe 5, and then enters the SCR denitrification reactor 7 through the electrically operated inlet valve 6. It then sequentially enters the first catalyst layer 8, the second catalyst layer 9, and the third catalyst layer 10. After the denitrification reaction, the purified flue gas enters the purified flue gas heat exchange device 12 through the electrically operated outlet valve 11, completing the SCR denitrification chemical reaction and achieving the denitrification purpose.

[0040] Compared with related technologies, the urea pyrolysis device based on an SCR denitrification system provided by this utility model has the following beneficial effects:

[0041] This utility model provides a urea pyrolysis device based on an SCR denitrification system. The device consists of an inlet pipe 1, a spraying device 2, a pyrolysis device 3, an outlet pipe 4, an inlet pipe 5, an inlet valve 6, a reactor 7, a first-layer catalyst 8, a second-layer catalyst 9, a third-layer catalyst 10, an outlet valve 11, and a heat exchange device 12. The device delivers high-temperature flue gas from the boiler to the urea pyrolysis device, causing the urea solution to pyrolyze and vaporize into an NH3-based mixture. This mixture provides a reducing agent for the SCR denitrification reaction, ensuring the chemical reaction proceeds and achieving ultra-low emission requirements for nitrogen oxides in the boiler flue gas.

[0042] Second Embodiment

[0043] Please refer to the following: Figure 2 , Figure 3 , Figure 4 and Figure 5Based on the first embodiment of this application, which provides a urea pyrolysis device based on an SCR denitrification system, the second embodiment of this application proposes another urea pyrolysis device based on an SCR denitrification system. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.

[0044] Specifically, the second embodiment of this application provides a urea pyrolysis device based on an SCR denitrification system, wherein a mixing pipe 13 is fixedly installed at one end of the air inlet pipe 1, and a conveying pipe 14 is fixedly connected to one end of the mixing pipe 13.

[0045] The mixing tube 13 is rotatably connected to a rotating tube 15, and the rotating tube 15 is threadedly connected to a threaded sleeve 17.

[0046] A sealing sleeve 16 is slidably connected inside the rotating tube 15, and a connecting tube 18 is fixedly connected inside the sealing sleeve 16.

[0047] The sealing sleeve 16 is used to seal the space between the rotating tube 15 and the connecting tube 18.

[0048] The upper half of the rotating tube 15 has a thread that matches the threaded sleeve 17. When the rotating tube 15 rotates to one side, the threaded sleeve 17 moves inside the rotating tube 15, thereby driving the connecting tube 18 to move.

[0049] The threaded sleeve 17 is also fixedly installed on the surface of the connecting pipe 18.

[0050] Both the mixing pipe 13 and the conveying pipe 14 are rotatably connected to a rotating pipe 15. Both rotating pipes 15 are threadedly connected to a threaded sleeve 17 and slidably connected to a sealing sleeve 16. Both threaded sleeves 17 are fixedly connected to a connecting pipe 18. One end of both connecting pipes 18 is fixedly installed with a diverter pipe 19. Multiple nozzles 20 are fixedly installed on the surface of both diverter pipes 19.

[0051] Telescopic rods 21 are fixedly installed at both ends of the two diversion pipes 19, and the two ends of the multiple telescopic rods 21 are respectively fixedly installed on the inner wall surfaces of the mixing pipe 13 and the conveying pipe 14.

[0052] A diversion pipe 19 is fixedly installed at one end of the connecting pipe 18. Multiple nozzles 20 are fixedly installed on the surface of the diversion pipe 19. Telescopic rods 21 are fixedly installed at both ends of the diversion pipe 19.

[0053] One end of the connecting pipe 18 is connected to an external delivery pump to deliver urea solution into the inside of the diversion pipe 19, which is then sprayed out through multiple nozzles 20, all of which are atomizing nozzles.

[0054] As the cross-sectional area of the delivery pipe 14 gradually decreases, the flow velocity of the flue gas gradually increases. The high-speed flow of the flue gas will have a stronger entrainment effect on the water mist, allowing the urea solution to penetrate deeper into the flue gas and expanding the mixing area between the urea solution and the flue gas. The acceleration process of the flue gas in the converging pipe will also cause pressure changes inside the flue gas, resulting in complex flow phenomena such as vortices. These flow phenomena help to disperse the water mist into the flue gas and improve the mixing effect.

[0055] The flue gas discharged from the intake pipe 1 enters the mixing pipe 13. As the cross-sectional area of the pipe gradually increases, the flow velocity of the flue gas gradually decreases. The decrease in flow velocity prolongs the residence time of the flue gas in the pipe, increasing the contact time between the flue gas and the water mist. At the same time, the change in flow velocity will cause the flue gas flow state to change, which is prone to generating turbulence. Turbulence will continuously renew the interface between the flue gas and the water mist, enhancing the material exchange and mixing effect between the two.

[0056] The working principle of the urea pyrolysis device based on the SCR denitrification system provided by this utility model is as follows:

[0057] In use, the connecting pipe 18 delivers urea solution into the interior of the diversion pipe 19 through an externally connected delivery pump. The solution is then sprayed out through multiple nozzles 20. After the flue gas discharged from the inlet pipe 1 enters the mixing pipe 13, the cross-sectional area of the pipe gradually increases, and the flow rate of the flue gas gradually decreases. The decrease in flow rate prolongs the residence time of the flue gas in the pipe, increasing the contact time between the flue gas and the water mist.

[0058] Meanwhile, as the cross-sectional area of the delivery pipe 14 gradually decreases, the flow velocity of the flue gas gradually increases. The high-speed flue gas will have a stronger entrainment effect on the water mist, allowing the urea solution to penetrate deeper into the flue gas and expanding the mixing area between the urea solution and the flue gas. The acceleration process of the flue gas in the converging pipe will also cause pressure changes inside the flue gas, resulting in complex flow phenomena such as vortices. These flow phenomena help to disperse the water mist into the flue gas and improve the mixing effect.

[0059] When the height of the nozzle 20 needs to be adjusted, the rotating tube 15 is rotated to one side, causing the threaded sleeve 17 to move inside the rotating tube 15, thereby driving the connecting tube 18 to move. When the connecting tube 18 moves, it pushes the diverter tube 19, which is connected to the two telescopic rods 21, to move and extend.

[0060] At the same time, when the connecting pipe 18 moves, it causes the sealing sleeve 16 to move inside the rotating pipe 15.

[0061] Compared with related technologies, the urea pyrolysis device based on an SCR denitrification system provided by this utility model has the following beneficial effects:

[0062] This invention provides a urea pyrolysis device based on an SCR denitrification system. The flue gas discharged from the inlet pipe 1 enters the mixing pipe 13, where the cross-sectional area gradually increases, and the flue gas velocity gradually decreases. This decrease in velocity prolongs the residence time of the flue gas within the pipe, increasing the contact time between the flue gas and water mist, thereby enhancing the mixing effect. Simultaneously, the cross-sectional area of the delivery pipe 14 gradually decreases, and the flue gas velocity gradually increases. The high-speed flue gas exerts a stronger entrainment effect on the water mist, allowing the urea solution to penetrate deeper into the flue gas, expanding the mixing area between the urea solution and the flue gas. The acceleration process of the flue gas in the converging pipe also causes pressure changes within the flue gas, resulting in complex flow phenomena such as vortices. These flow phenomena help disperse the water mist into the flue gas, improving the mixing effect.

[0063] The above description is merely an embodiment of this utility model and does not limit the patent scope of this utility model. Any equivalent structural or procedural transformations made based on the content of this utility model specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this utility model.

Claims

1. A urea pyrolysis device based on an SCR denitrification system, characterized in that, include: An air inlet pipe is provided, with a spraying device fixedly installed at one end, a pyrolysis device fixedly installed at one end of the spraying device, an air outlet pipe fixedly installed at one end of the pyrolysis device, an inlet pipe fixedly installed at one end of the air outlet pipe, an inlet valve fixedly installed on the surface of the inlet pipe, a reactor fixedly installed at one end of the air outlet pipe, a first layer of catalyst, a second layer of catalyst, and a third layer of catalyst disposed inside the reactor, a heat exchange device fixedly installed at one end of the reactor, and an outlet valve disposed at one end of the reactor.

2. The urea pyrolysis device based on an SCR denitrification system according to claim 1, characterized in that, One end of the reactor is connected to the heat exchange device via a pipe, and the outlet valve is fixedly installed on the surface of the pipe.

3. The urea pyrolysis device based on an SCR denitrification system according to claim 1, characterized in that, A mixing pipe is fixedly installed at one end of the air intake pipe, and a delivery pipe is fixedly connected to one end of the mixing pipe.

4. The urea pyrolysis device based on an SCR denitrification system according to claim 3, characterized in that, The mixing tube is internally rotatably connected to a rotating tube, and the rotating tube is internally threadedly connected to a threaded sleeve.

5. A urea pyrolysis device based on an SCR denitrification system according to claim 4, characterized in that, The rotating tube is slidably connected to a sealing sleeve, and the sealing sleeve is fixedly connected to a connecting tube.

6. A urea pyrolysis device based on an SCR denitrification system according to claim 5, characterized in that, The threaded sleeve is also fixedly installed on the surface of the connecting pipe.

7. A urea pyrolysis device based on an SCR denitrification system according to claim 6, characterized in that, A diversion pipe is fixedly installed at one end of the connecting pipe, and multiple nozzles are fixedly installed on the surface of the diversion pipe. Telescopic rods are fixedly installed at both ends of the diversion pipe.