A heating device for an SCR denitration urea pyrolysis system
Patent Information
- Application Number
- CN202522571011.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-03
- Publication Date
- 2026-10-27
- Estimated Expiration
- 2035-12-03
AI Technical Summary
1.本实用新型通过优化锅炉热风在空气加热器内的热接触均匀性、提升气气换热效率，借助换热盘管和C字形流通腔对锅炉热风实现内、外侧的同时换热，不仅实现了后续尿素在热解炉内的充分热解，且该均匀化气气换热装置还能有效降低热解炉系统的运行成本；
Smart Images
Figure CN224905297U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of urea pyrolysis equipment technology, and in particular to a heating device for an SCR denitrification urea pyrolysis system. Background Technology
[0002] The SCR denitrification urea pyrolysis system employs selective catalytic reduction (SCR) technology. The basic principle of this technology is to inject ammonia (NH3) into the flue gas as a reducing agent, and under the action of a catalyst, remove nitrogen oxides (NOx) from the flue gas. x The nitrogen and water are reduced to nitrogen. This technology typically uses 2-3 catalyst layers with one layer as a backup. The denitrification efficiency can reach 90-95%, and the NOx emission concentration can be completely controlled below 50 mg / Nm3. There are generally three types of denitrification device layouts: high temperature and high dust, high temperature and low dust, and low temperature and low dust. This project adopts the high temperature and high dust layout. The advantage of this layout is that the flue gas temperature entering the reactor reaches 300-450℃. Most catalysts have sufficient activity within this temperature range, and the flue gas can achieve good denitrification effect without further heating.
[0003] However, in the current SCR denitrification urea pyrolysis system with high temperature and high dust arrangement, after urea is pyrolyzed in the pyrolysis furnace, it enters the SCR inlet ammonia injection grid together with hot air and mixes with the flue gas. The quality of this mixing is closely related to the urea pyrolysis efficiency. How to improve the pyrolysis efficiency of urea in the pyrolysis furnace, and thus enhance the sufficiency of subsequent mixing with the flue gas, has become a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content
[0004] This device provides a heating apparatus for an SCR denitrification urea pyrolysis system, and the specific implementation method is as follows: A heating device for an SCR denitrification urea pyrolysis system, comprising: The air heater and electric heater are interconnected. The front end of the air heater is connected in parallel with a boiler hot air inlet, and each branch is connected in series with a hot air fan. A pyrolysis furnace connected to an air heater, and the outlet of the pyrolysis furnace connected to an ammonia injection grid; The air heater includes an outer shell and an inner shell that are nested together. The inner shell has an axially arranged heat exchange coil for introducing the first heat exchange gas. The inner side of the inner shell and the outer side of the heat exchange coil form an axial flow channel for boiler hot air. The outer side of the inner shell and the inner side of the outer shell form a flow space for the second heat exchange gas. The flow space is formed into a C-shaped flow cavity by a partition. The gas inlet and outlet of the second heat exchange gas are both located on the same side of the end face of the outer shell. The boiler hot air in the axial flow channel is subjected to the combined action of the two heat exchange gases, one inside and one outside, to improve the gas-to-gas heat exchange efficiency.
[0005] Preferably, the device also includes a controller, a second pressure gauge at the front end of the air heater, a first thermometer at the rear end of the electric heater, a second thermometer and a third thermometer connected to the inside and outside of the pyrolysis furnace respectively, and a first pressure gauge connected to the front end of the ammonia injection grid; each sensor is electrically connected to the signal input terminal of the controller, and the signal output terminal of the controller is electrically connected to the pyrolysis furnace, the hot air blower, the air heater and the electric heater.
[0006] Based on the above technical solutions, by improving the uniformity of thermal contact and gas-to-gas heat exchange efficiency of boiler hot air in the air heater, the complete pyrolysis of urea in the pyrolysis furnace is achieved. At the same time, the uniform gas-to-gas heat exchange device can reduce the operating cost of the pyrolysis furnace system. The first and second heat exchange gases are both conventional heat exchange media in the operation of the air heater, mostly industrial clean air or preheated auxiliary air. Through the combined action of these two heat exchange gases from the heat exchange coil and the C-shaped flow cavity, efficient heat exchange of boiler hot air in the axial flow channel is achieved. In this application, the pyrolysis furnace is made of 304 stainless steel and is used to evaporate and pyrolyze urea solution into ammonia.
[0007] The system is equipped with two hot air blowers for dilution, and one set of air heater and electric heater. Preferably, the two ends of the C-shaped flow cavity are respectively provided with an air inlet cover and an air outlet cover, and the end of the partition has an air guide grille that connects the upper and lower parts.
[0008] Preferably, the two ends of the heat exchange coil are respectively set as an air inlet and an air outlet, and both extend outward from the two ends of the outer casing.
[0009] Based on the above technical solutions, the air inlet cover and air outlet cover are uniformly located on the same side of the C-shaped flow cavity. This not only greatly simplifies equipment maintenance operations and improves maintenance convenience, but also reduces the flow cross-sectional area of the second heat exchange gas by optimizing the flow path of the second heat exchange gas. The reasonable reduction of the flow cross-sectional area can directly increase the flow velocity of the second heat exchange gas in the C-shaped cavity, strengthen the scouring force between the gas and the heat exchange components on the outer side of the inner shell, avoid the formation of heat exchange dead zones due to local gas stagnation, and make the heat exchange contact more sufficient.
[0010] Preferably, the inner shell is a cylindrical structure, which is alternately provided with a number of wide diameter sections and narrow diameter sections along the axial direction, and the joint between the wide diameter sections and the narrow diameter sections is provided as a variable diameter inclined surface.
[0011] Preferably, the heat exchange coil is arranged in a cylindrical structure along its circumference, and a flow guiding and fixing shaft is provided on its inner side along the axial direction. The flow guiding and fixing shaft is alternately arranged as a large-diameter shaft and a small-diameter shaft along the axial direction. The outer contour of the large-diameter shaft matches the inner contour of the wide-diameter part and is symmetrical. The two form an annular variable-diameter channel along the circumference.
[0012] Based on the above technical solutions, by setting a variable-diameter inner shell and a variable-diameter guide fixed shaft, the inner shell can independently realize the variable-diameter flow of boiler hot air. The two can also be combined to form a circumferential uniform inner variable-diameter flow path. With the help of the variable-diameter transport of boiler hot air, the fluid disturbance can be effectively enhanced, the heat transfer effect and heat exchange efficiency can be significantly improved, and the heat exchange synergy between heat exchange gas and boiler hot air can be further enhanced.
[0013] Preferably, a plurality of heat exchange elements are equidistantly arranged on the outer circumferential surface of the inner shell. The heat exchange elements include alternating first heat exchange elements and second heat exchange elements, both of which are conical structures with opposite cone directions.
[0014] Preferably, the first heat exchanger has a conical structure, with its front end inserted into the inner side of the inner shell and a square first guide groove radially provided; the second heat exchanger has a Y-shaped structure, with its front end inserted into the inner side of the inner shell and a V-shaped second guide groove formed.
[0015] Preferably, the first heat exchanger has a first cavity with an end opening, and the second heat exchanger has a second cavity with an end opening.
[0016] Based on the above technical solution, by setting a first heat exchanger and a second heat exchanger with the same slope, several flow ports can be uniformly formed circumferentially on the cross-section of the boiler hot air flow, thereby significantly improving the uniformity of boiler hot air flow and heat exchange. The heat exchanger can be internally implemented to achieve heat exchange through contact, and a cavity for the introduction of the second heat exchange gas can also be left inside the heat exchanger, which can further improve the heat exchange area and efficiency. Moreover, after the cross-sectional area of the second heat exchange gas becomes smaller, the flowability of the second heat exchange gas in the cavity is enhanced, and gas stagnation in the cavity is also avoided.
[0017] In summary, this application includes the following beneficial technical effects: 1. This utility model optimizes the uniformity of heat contact between boiler hot air and air heater, improves gas-to-gas heat exchange efficiency, and achieves simultaneous heat exchange between the inner and outer sides of boiler hot air by means of heat exchange coil and C-shaped flow cavity. This not only enables the full pyrolysis of urea in the pyrolysis furnace, but also effectively reduces the operating cost of the pyrolysis furnace system. 2. This utility model has a simple structure. By setting a variable diameter inner shell and a variable diameter guide fixing shaft, the inner shell can independently realize the variable diameter flow of boiler hot air, and the two can also be combined to form a circumferential uniform inner variable diameter flow path. Through the variable diameter delivery of boiler hot air, fluid disturbance can be effectively enhanced, greatly enhancing the heat transfer effect and heat exchange efficiency, and further improving the heat exchange synergy between heat exchange gas and boiler hot air. 3. By setting up a first heat exchanger and a second heat exchanger with the same slope, this utility model forms several flow ports evenly along the circumferential direction on the cross-section of the boiler hot air flow, which further improves the uniformity of boiler hot air flow and heat exchange. Attached Figure Description
[0018] Figure 1 This is a flowchart illustrating the present invention. Figure 2 This is a schematic diagram of the structure of this utility model; Figure 3 This is a cross-sectional view of the side structure of this utility model; Figure 4 This is an exploded structural diagram of the present invention; Figure 5 This is a cross-sectional view of the front structure of this utility model; Figure 6 This is a schematic diagram of the heat exchange coil in this utility model; Figure 7 This is a cross-sectional view of the right side structure of this utility model; Figure 8 This is a cross-sectional view of the structure of the second heat exchanger in this utility model; Figure 9 This is a schematic diagram of the structure of the first heat exchanger in this utility model.
[0019] Explanation of reference numerals in the attached figures: 1. Outer shell, 2. Heat exchange coil, 3. Inner shell, 4. First heat exchanger, 5. Flow guide fixing shaft, 6. Second heat exchanger. 10. Ammonia injection grid; 11. Controller; 12. Pyrolysis furnace; 13. Hot air blower; 14. Air heater; 15. Electric heater; 16. First thermometer; 17. Second thermometer; 18. Third thermometer; 19. First pressure gauge; 20. Second pressure gauge. 101. Intake cover, 102. Exhaust cover, 103. C-shaped flow chamber, 104. Air guide grille. 105. Partition, 201. Air inlet; 202. Air outlet. 301. Wide diameter section; 302. Narrow diameter section. 401, First cavity; 402, First guide groove; 501, large diameter shaft; 502, small diameter shaft. 601, Second cavity; 602, Second guide groove. Detailed Implementation
[0020] The specific embodiments of this utility model are described below with reference to the accompanying drawings and examples: It should be noted that the structures, proportions, sizes, etc. shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which the present invention can be implemented. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.
[0021] Meanwhile, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in this specification are only for clarity of description and are not intended to limit the scope of implementation of this utility model. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered as within the scope of implementation of this utility model.
[0022] The following is in conjunction with the appendix Figure 1-9 This application will be described in further detail.
[0023] This application discloses a heating device for an SCR denitrification urea pyrolysis system.
[0024] Example 1 Reference Figures 1 to 6 This embodiment discloses a heating device for an SCR denitrification urea pyrolysis system, including a controller 11, an air heater 14 and an electric heater 15 connected to each other, and a pyrolysis furnace 12 connected to the air heater 14. The front end of the air heater 14 is provided with a boiler hot air inlet in parallel, and each branch is connected in series with a hot air fan 13. The outlet of the pyrolysis furnace 12 is connected to an ammonia injection grid 10.
[0025] The air heater 14 includes an outer shell 1 and an inner shell 3 nested together. The inner shell 3 has an axially arranged heat exchange coil 2 for introducing the first heat exchange gas. The inner side of the inner shell 3 and the outer side of the heat exchange coil 2 form an axial flow channel for boiler hot air. The outer side of the inner shell 3 and the inner side of the outer shell 1 form a flow space for the second heat exchange gas. The flow space is formed by a partition 105 to form a C-shaped flow cavity 103. The gas inlet and outlet of the second heat exchange gas are both arranged on the same side of the end face of the outer shell 1. The boiler hot air in the axial flow channel is subjected to the combined action of the two heat exchange gases inside and outside, so as to improve the gas-to-gas heat exchange efficiency.
[0026] The air heater 14 is equipped with a second pressure gauge 20 at its front end, the electric heater 15 is equipped with a first thermometer 16 at its rear end, the pyrolysis furnace 12 is equipped with a second thermometer 17 and a third thermometer 18 on its inner and outer sides respectively, and the ammonia injection grid 10 is equipped with a first pressure gauge 19 at its front end. In this structure, all sensors are electrically connected to the signal input terminal of the controller 11, and the signal output terminal of the controller 11 is electrically connected to the pyrolysis furnace 12, the hot air blower 13, the air heater 14 and the electric heater 15.
[0027] The C-shaped flow cavity 103 is provided with an air inlet cover 101 and an air outlet cover 102 at both ends, and the end of the partition 105 is provided with an air guide grille 104 that connects the upper and lower parts. The two ends of the heat exchange coil 2 are respectively provided with an air inlet 201 and an air outlet 202, and both of them extend outward from the two ends of the outer shell 1.
[0028] The inner shell 3 is a cylindrical structure, which is alternately configured with several wide diameter sections 301 and narrow diameter sections 302 along the axial direction. The joint between the wide diameter sections 301 and narrow diameter sections 302 is configured as a variable diameter inclined surface. The alternation of the wide diameter sections 301 and narrow diameter sections 302 realizes the enhancement of the activity of the boiler hot air.
[0029] The specific implementation process is as follows: the high-temperature flue gas from the boiler at about 100°C is drawn out by the hot air blower 13, and the primary air is reheated to about 300°C by the air heater 14; the heated hot air is then reheated to about 350-650°C by the electric heater 15 as needed and enters the pyrolysis furnace 12. After the urea is completely pyrolyzed in the pyrolysis furnace 12, it enters the ammonia injection grid 10 at the SCR inlet together with the hot air and mixes thoroughly with the flue gas.
[0030] Example 2 Reference Figures 1 to 5 This embodiment discloses a heating device for an SCR denitrification urea pyrolysis system. The heat exchange coil 2 is arranged in a cylindrical structure along its circumference, and a flow guiding and fixing shaft 5 is provided on its inner side along the axial direction. The flow guiding and fixing shaft 5 is alternately arranged as a large diameter shaft 501 and a small diameter shaft 502 along the axial direction. The outer contour of the large diameter shaft 501 matches the inner contour of the wide diameter part 301 and is symmetrical. The two form an annular diameter-changing channel along the circumference. That is, the wide diameter part 301 has an isosceles trapezoidal shape, and the position of the small diameter shaft 502 is also an isosceles trapezoidal shape with the same slope. In this structure, the axial length of the trapezoid of the small diameter shaft 502 can be shorter than the axial length of the trapezoid of the wide diameter part 301, thereby forming a covering effect of the large trapezoid of the wide diameter part 301 on the small trapezoid of the small diameter shaft 502. That is, the boiler hot air undergoes a gas convergence at the rear end of the diameter change of the small diameter shaft 502 before entering the next diameter change disturbance of the boiler hot air.
[0031] Example 3 Reference Figures 1 to 9 This embodiment discloses a heating device for an SCR denitrification urea pyrolysis system. A plurality of heat exchange elements are equidistantly arranged on the outer circumferential surface of the inner shell 3. The heat exchange elements include alternating first heat exchange elements 4 and second heat exchange elements 6. Both are conical structures with opposite cone directions. In this structure, the first heat exchange elements 4 and second heat exchange elements 6 are alternately arranged in the same circumferential direction. The first heat exchange elements 4 and second heat exchange elements 6 can also be alternately arranged in adjacent axial directions.
[0032] The first heat exchanger 4 has a conical structure, with its front end penetrating into the inner shell 3 and having a square first guide groove 402 radially therein; the second heat exchanger 6 has a Y-shaped structure, with its front end penetrating into the inner shell 3 and having a V-shaped second guide groove 602. In this structure, the first heat exchanger 4 has a first cavity 401 with an open end, and the second heat exchanger 6 has a second cavity 601 with an open end.
[0033] The specific implementation process of the air heater 14 is as follows: heat exchanger coil 2 and C-shaped flow cavity 103 both introduce heat exchange gas; boiler hot air is introduced from the axial flow channel between the inner shell 3 and the heat exchanger coil 2, and the boiler hot air exchanges heat synchronously with the heat exchange gas on the inner and outer sides; during the flow of boiler hot air, the boiler hot air passes through the variable diameter structure between the inner shell 3 and the guide fixed shaft 5 in sequence, realizing the heat exchange disturbance of the boiler hot air itself; the disturbed boiler hot air is uniformly transported forward through the flow channel between the first heat exchanger 4 and the second heat exchanger 6, ensuring the uniformity of the overall heat exchange after the boiler hot air disturbance.
[0034] Many other changes and modifications can be made without departing from the concept and scope of this utility model. It should be understood that this utility model is not limited to the specific embodiments, and the scope of this utility model is defined by the appended claims.
Claims
1. A heating device for an SCR denitrification urea pyrolysis system, characterized in that, include: An air heater (14) and an electric heater (15) are connected to each other. The front end of the air heater (14) is provided with a boiler hot air inlet, and each branch is connected in series with a hot air fan (13). A pyrolysis furnace (12) is connected to the air heater (14), and the outlet of the pyrolysis furnace (12) is connected to the ammonia injection grid (10). The air heater (14) includes an outer shell (1) and an inner shell (3) nested together. The inner shell (3) is axially provided with a heat exchange coil (2) for introducing the first heat exchange gas. The inner side of the inner shell (3) and the outer side of the heat exchange coil (2) form an axial flow channel for boiler hot air. The outer side of the inner shell (3) and the inner side of the outer shell (1) form a flow space for the second heat exchange gas. The flow space is formed by a partition (105) to form a C-shaped flow cavity (103). The gas inlet and outlet of the second heat exchange gas are both arranged on the same side of the end face of the outer shell (1). The boiler hot air in the axial flow channel is subjected to the combined action of the two heat exchange gases inside and outside to improve the gas-to-gas heat exchange efficiency.
2. The heating device for an SCR denitrification urea pyrolysis system according to claim 1, characterized in that, It also includes a controller (11), a second pressure gauge (20) is provided at the front end of the air heater (14), a first thermometer (16) is provided at the rear end of the electric heater (15), a second thermometer (17) and a third thermometer (18) are respectively connected to the inside and outside of the pyrolysis furnace (12), and a first pressure gauge (19) is connected to the front end of the ammonia injection grid (10). Each sensor is electrically connected to the signal input terminal of the controller (11), and the signal output terminal of the controller (11) is electrically connected to the pyrolysis furnace (12), the hot air blower (13), the air heater (14), and the electric heater (15).
3. A heating device for an SCR denitrification urea pyrolysis system according to claim 2, characterized in that, The C-shaped flow cavity (103) is provided with an air inlet cover (101) and an air outlet cover (102) at both ends, and the end of the partition (105) is provided with an air guide grille (104) that connects the upper and lower parts.
4. A heating device for an SCR denitrification urea pyrolysis system according to claim 3, characterized in that, The two ends of the heat exchange coil (2) are respectively set as an air inlet (201) and an air outlet (202), and both extend outward from the two ends of the outer shell (1).
5. A heating device for an SCR denitrification urea pyrolysis system according to claim 4, characterized in that, The inner shell (3) is a cylindrical structure, which is alternately provided with a number of wide diameter sections (301) and narrow diameter sections (302) along the axial direction, and the joint of the wide diameter section (301) and the narrow diameter section (302) is provided as a variable diameter inclined surface.
6. A heating device for an SCR denitrification urea pyrolysis system according to claim 5, characterized in that, The heat exchange coil (2) is arranged in a cylindrical structure along its circumference, and a flow guiding and fixing shaft (5) is provided on its inner side along the axial direction. The flow guiding and fixing shaft (5) is alternately arranged as a large diameter shaft (501) and a small diameter shaft (502) along the axial direction. The outer contour of the large-diameter shaft (501) matches and is symmetrical with the inner contour of the wide-diameter portion (301), and the two form an annular variable-diameter channel along the circumference.
7. A heating device for an SCR denitrification urea pyrolysis system according to claim 6, characterized in that, The outer circumferential surface of the inner shell (3) is provided with a number of heat exchange elements at equal intervals. The heat exchange elements include a first heat exchange element (4) and a second heat exchange element (6) arranged alternately. Both of them are conical structures with opposite cone directions.
8. A heating device for an SCR denitrification urea pyrolysis system according to claim 7, characterized in that, The first heat exchanger (4) has a conical structure, with its front end inserted into the inner side of the inner shell (3) and a square first guide groove (402) radially provided. The second heat exchanger (6) has a Y-shaped structure, with its front end inserted into the inner side of the inner shell (3) and forming a V-shaped second guide groove (602).
9. A heating device for an SCR denitrification urea pyrolysis system according to claim 8, characterized in that, The first heat exchanger (4) has a first cavity (401) with an end opening, and the second heat exchanger (6) has a second cavity (601) with an end opening.