High-temperature air preheater structure suitable for PDH boiler
By setting a non-metallic expansion joint between the pipe plate and the partition of the high-temperature air preheater to form a flexible connection, the problem of pipe plate failure at high temperature is solved, and thermal stress relief and equipment reliability are improved.
Patent Information
- Application Number
- CN202421956136.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-13
- Publication Date
- 2025-06-13
- Estimated Expiration
- 2034-08-13
AI Technical Summary
Existing high-temperature air preheaters are prone to tube plate failure under the action of high temperature and thermal stress circulation, resulting in reduced equipment reliability, shortened maintenance cycles and increased energy consumption.
A high-temperature air preheater structure suitable for PDH boilers is designed. By setting non-metallic expansion joints between the pipe plate and the partition plate, a flexible connection is formed to absorb the expansion or contraction of the pipe caused by temperature changes, and the thermal stress is reduced.
It effectively reduces the thermal stress of the pipe sheet, reduces the risks of creep, fatigue and brittle fracture, extends the service life of the equipment, improves operating reliability, and reduces maintenance costs.
Smart Images
Figure CN222978167U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of high-temperature air preheaters, in particular to a high-temperature air preheater structure applicable to a PDH boiler. Background Art
[0002] A PDH boiler generally refers to a boiler used in the propylene dehydrogenation process. Such boilers are used to provide steam in chemical production to meet the heat required when propylene is converted into acrylonitrile or other chemicals. In the PDH process, a high-temperature air preheater is mainly used to improve the combustion efficiency, reduce energy consumption, and is also one of the key equipment for reducing emissions. A high-temperature air preheater is a device that uses the waste heat of high-temperature flue gas in the process to heat the process air, so that the outlet temperature of the process air is higher than 800 °C to meet the energy recovery requirements.
[0003] The essence of a high-temperature air preheater is a shell-and-tube heat exchanger. The high-temperature flue gas flows through the shell side, and the air flows through the tube side. The two fluids form a countercurrent to complete the heat exchange. During the heat exchange process between the high-temperature flue gas and the air, the temperature gradient between the high-temperature flue gas and the air to be heated is relatively large, generating a large internal stress on the tube sheet of the air preheater, which is prone to strength failure at high temperatures, especially at the end connection of the air preheater, where tube sheet failure is extremely likely to occur. Under the continuous high temperature and repeated thermal stress cycles, even if high-temperature-resistant materials are used, the tube sheet may still be at risk of creep, fatigue, and brittle fracture. The degradation of these material properties will reduce the overall reliability of the equipment. Tube sheet failure usually manifests as the generation and expansion of cracks, which may ultimately lead to leakage or structural damage, not only affecting the thermal efficiency of the equipment but also causing safety problems. Moreover, frequent tube sheet failure means a shortened maintenance cycle of the equipment and an increase in maintenance costs. At the same time, due to the decrease in thermal efficiency, energy consumption will also increase, affecting the overall economic benefits.
[0004] Therefore, it is necessary to design a high-temperature air preheater structure applicable to a PDH boiler to avoid the problem of tube sheet failure at the end of the air preheater caused by thermal stress. Summary of the Utility Model
[0005] The purpose of the utility model is to solve the deficiencies existing in the prior art and propose a high-temperature air preheater structure applicable to a PDH boiler.
[0006] To achieve the above purpose, the utility model adopts the following technical solutions:
[0007] A high-temperature air preheater structure applicable to a PDH boiler, comprising a high-temperature air preheater tube pass and a high-temperature air preheater shell pass. The high-temperature air preheater tube pass includes an inlet connection assembly, an outlet connection assembly, and a plurality of tube passes. The inlet connection assembly and the outlet connection assembly are symmetrically arranged. The high-temperature air preheater shell pass includes a flue gas flow connection assembly and a shell pass. The inlet connection assembly and the outlet connection assembly are respectively arranged at opposite ends of the shell pass, and the tube passes are located inside the shell pass.
[0008] As a preferred technical solution of the present invention, the inlet connection assembly includes an air inlet channel. An air inlet branch is communicated with the air inlet channel. An air inlet square-round interface is communicated with the air inlet branch. An air inlet side tube sheet is fixed on the side wall of the air inlet square-round interface. An air inlet side end partition is arranged on the side wall of the air inlet side tube sheet. One end of the tube pass respectively penetrates through the side walls of the air inlet side end partition and the air inlet side tube sheet, and the tube pass is communicated with the air inlet square-round interface. The tube pass is fixedly connected with the air inlet side tube sheet, and the tube pass is slidably connected with the air inlet side end partition. An air inlet side non-metallic expansion joint is jointly arranged between the air inlet side tube sheet and the air inlet side end partition;
[0009] The outlet connection assembly includes an air outlet channel. An air outlet branch is communicated with the air outlet channel. An air outlet square-round interface is communicated with the air outlet branch. An air outlet side tube sheet and an air outlet side end partition are arranged on the side wall of the air outlet square-round interface. The air outlet square-round interface is fixed to the side wall of the air outlet side tube sheet. The other end of the tube pass sequentially penetrates through the side walls of the air outlet side end partition and the air outlet side tube sheet, and the tube pass is communicated with the air outlet square-round interface. The tube pass is fixed to the air outlet side tube sheet, and the tube pass is slidably connected with the air outlet side end partition. An air outlet side non-metallic expansion joint is jointly arranged between the air outlet side end partition and the air outlet side tube sheet;
[0010] Both ends of the shell pass are open, and the air outlet side end partition and the air inlet side end partition are respectively fixed to the two open ends of the shell pass.
[0011] As a preferred technical solution of the present utility model, the flue gas flow connection assembly includes an inner tube sheet on the flue gas inlet side and an inner tube sheet on the flue gas outlet side. The inner tube sheet on the flue gas inlet side and the inner tube sheet on the flue gas outlet side are respectively fixedly connected to the bottom and top of the shell side. An outer tube sheet on the flue gas inlet side is provided at the bottom of the inner tube sheet on the flue gas inlet side, and an outer tube sheet on the flue gas outlet side is provided above the inner tube sheet on the flue gas outlet side. A non-metallic expansion joint on the flue gas inlet side is provided between the inner tube sheet on the flue gas inlet side and the outer tube sheet on the flue gas inlet side, and a non-metallic expansion joint on the flue gas outlet side is jointly provided between the inner tube sheet on the flue gas outlet side and the outer tube sheet on the flue gas outlet side. Through holes for flue gas flow are provided on the inner tube sheet on the flue gas inlet side, the inner tube sheet on the flue gas outlet side, the inner tube sheet on the flue gas inlet side, and the outer tube sheet on the flue gas inlet side.
[0012] As a preferred technical solution of the present utility model, the tube passes are equally spaced.
[0013] As a preferred technical solution of the present utility model, both ends of the tube passes are fixed to the air inlet side tube sheet and the air outlet side tube sheet respectively by welding.
[0014] As a preferred technical solution of the present utility model, the tube passes are made of nickel-based alloy material.
[0015] The present utility model has the following beneficial effects:
[0016] 1. Thermal stress relief: By setting non-metallic expansion joints between the tube sheet and the partition plate, a flexible connection is formed, effectively absorbing the expansion or contraction of the pipeline caused by temperature changes, significantly reducing the thermal stress on the tube sheet. The reduction of thermal stress helps to reduce the risks of creep, fatigue, and brittle fracture of the tube sheet, ensures the stability of the device structure, extends the service life of the high-temperature air preheater, and improves the reliability of equipment operation.
[0017] 2. Reduction of maintenance cost: This design reduces the influence of thermal stress, reduces the loss and maintenance cost of the device, reduces the maintenance frequency, avoids the downtime and production interruption caused by equipment failure, and this design has a simple structure, low maintenance cost and operation difficulty. Description of the Drawings
[0018] Figure 1 It is a schematic structural diagram of a high-temperature air preheater structure applicable to a PDH boiler proposed by the present utility model;
[0019] Figure 2 It is a schematic structural diagram of the shell side of the high-temperature air preheater;
[0020] Figure 3 It is a schematic structural diagram of the non-metallic expansion joint on the air inlet side;
[0021] Figure 4 It is a schematic structural diagram of a non-metallic expansion joint on the flue gas inlet side.
[0022] In the figure: 1 Tube pass of high-temperature air preheater, 101 Air inlet channel, 102 Air inlet branch, 103 Square-round interface of air inlet, 104 Tube sheet on the air inlet side, 105 End partition on the air inlet side, 106 Tube pass, 107 End partition on the air outlet side, 108 Tube sheet on the air outlet side, 109 Square-round interface of air outlet, 110 Air outlet branch, 111 Air outlet channel, 2 Shell pass of high-temperature air preheater, 201 External tube sheet on the flue gas inlet side, 202 Internal tube sheet on the flue gas inlet side, 203 Shell pass, 204 Internal tube sheet on the flue gas outlet side, 205 External tube sheet on the flue gas outlet side, 301 Non-metallic expansion joint on the air inlet side, 302 Non-metallic expansion joint on the air outlet side, 401 Non-metallic expansion joint on the flue gas inlet side, 402 Non-metallic expansion joint on the flue gas outlet side. Specific embodiments
[0023] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments.
[0024] Referring to Figures 1-4 , a high-temperature air preheater structure applicable to a PDH boiler includes a tube pass 1 of a high-temperature air preheater and a shell pass 2 of a high-temperature air preheater. The tube pass 1 of the high-temperature air preheater includes an inlet connection assembly, an outlet connection assembly, and a plurality of tube passes 106. The tube passes 106 are made of nickel-based alloy materials. Since the boilers in propane dehydrogenation plants usually involve high-temperature and corrosive environments, the selection of nickel-based alloy has excellent heat resistance and oxidation resistance, and has good creep resistance and anti-fission ability at high temperatures, reducing the influence of the device by thermal stress. The tube passes 106 are evenly spaced, which enables the tube passes 106 to fully contact the flue gas, ensuring the efficiency of heat transfer in the flue gas and thus improving the heat exchange rate. Secondly, by setting a plurality of tube passes 106, the air at the inlet can be dispersed, increasing the heat exchange area between the air and the flue gas. The inlet connection assembly and the outlet connection assembly are symmetrically arranged. The shell pass 2 of the high-temperature air preheater includes a flue gas flow connection assembly and a shell pass 203. The inlet connection assembly and the outlet connection assembly are respectively arranged at opposite ends of the shell pass 203, and the tube passes 106 are located inside the shell pass 203.
[0025] Referring to Figure 1 and Figure 3, the inlet connection assembly includes an air inlet channel 101, an air inlet branch 102 is communicatively provided on the air inlet channel 101, an air inlet square-round interface 103 is communicatively provided on the air inlet branch 102, an air inlet side tube sheet 104 is fixed to the side wall of the air inlet square-round interface 103, an air inlet side end partition 105 is provided on the side wall of the air inlet side tube sheet 104, one end of the tube pass 106 respectively penetrates through the side walls of the air inlet side end partition 105 and the air inlet side tube sheet 104, and the tube pass 106 is communicatively connected with the air inlet square-round interface 103. The tube pass 106 is fixedly connected with the air inlet side tube sheet 104, the tube pass 106 is slidably connected with the air inlet side end partition 105, and an air inlet side non-metallic expansion joint 301 is jointly provided between the air inlet side tube sheet 104 and the air inlet side end partition 105;
[0026] The outlet connection assembly includes an air outlet channel 111, an air outlet branch 110 is communicatively provided on the air outlet channel 111, an air outlet square-round interface 109 is communicatively provided on the air outlet branch 110, an air outlet side tube sheet 108 and an air outlet side end partition 107 are provided on the side wall of the air outlet square-round interface 109. The air outlet square-round interface 109 is fixed to the side wall of the air outlet side tube sheet 108. The other end of the tube pass 106 sequentially penetrates through the side walls of the air outlet side end partition 107 and the air outlet side tube sheet 108, and the tube pass 106 is communicatively connected with the air outlet square-round interface 109. The tube pass 106 is fixed to the air outlet side tube sheet 108, the tube pass 106 is slidably connected with the air outlet side end partition 107, and an air outlet side non-metallic expansion joint 302 is jointly provided between the air outlet side end partition 107 and the air outlet side tube sheet 108;
[0027] Both ends of the shell pass 203 are open. The air outlet side end partition 107 and the air inlet side end partition 105 are respectively fixed to the two open ends of the shell pass 203. Under the action of the air outlet side non-metallic expansion joint 302 and the air inlet side non-metallic expansion joint 301, a flexible connection is formed between the shell pass 203 and the air inlet side tube sheet 104 and the air outlet side tube sheet 108 respectively. Both ends of the tube pass 106 are fixed to the air inlet side tube sheet 104 and the air outlet side tube sheet 108 by welding respectively, ensuring the stability of the connection between the tube pass 106 and the two tube sheets. The cross-section of one side where the air inlet square-round interface 103 is connected to the air inlet branch 102 is circular, and the cross-section of one side where the air inlet square-round interface 103 is connected to the air inlet side tube sheet 104 is square. All the tube passes 106 are distributed in a rectangular shape as a whole. In this way, when the flue gas passes through the tube pass 106, the surface of the tube pass 106 can uniformly contact the flue gas. The shape of the air outlet square-round interface 109 is the same as above.
[0028] Refer to Figure 2 and Figure 4, the flue gas flow connection assembly includes an inner tube sheet 202 on the flue gas inlet side and an inner tube sheet 204 on the flue gas outlet side. The inner tube sheet 202 on the flue gas inlet side and the inner tube sheet 204 on the flue gas outlet side are respectively fixedly connected to the bottom and top of the shell side 203. An outer tube sheet 201 on the flue gas inlet side is provided at the bottom of the inner tube sheet 202 on the flue gas inlet side, and an outer tube sheet 205 on the flue gas outlet side is provided above the inner tube sheet 204 on the flue gas outlet side. A non-metallic expansion joint 401 on the flue gas inlet side is provided between the inner tube sheet 202 on the flue gas inlet side and the outer tube sheet 201 on the flue gas inlet side, and a non-metallic expansion joint 402 on the flue gas outlet side is jointly provided between the inner tube sheet 204 on the flue gas outlet side and the outer tube sheet 205 on the flue gas outlet side. Through holes for flue gas flow are provided on the inner tube sheet 202 on the flue gas inlet side, the inner tube sheet 204 on the flue gas outlet side, the inner tube sheet 202 on the flue gas inlet side, and the outer tube sheet 201 on the flue gas inlet side. The non-metallic expansion joints are all made of glass fiber coated rubber material, combining the strength of glass fiber and the elasticity of rubber, and can provide good sealing performance and temperature resistance, while reducing the influence of thermal stress on the device and ensuring the structural stability of the device.
[0029] The specific working principle of the present utility model is as follows:
[0030] For the air side, the process air with a lower temperature enters the high-temperature air preheater from the air inlet channel 101, and successively passes through the air inlet branch 102 and the air inlet square-round interface 103 to enter the tube side 106. Subsequently, it flows out successively from the air outlet square-round interface 109, the air outlet branch 110, and the air outlet channel 111. After the air exchanges heat with the high-temperature flue gas, the outlet temperature can reach above 800 °C. During the process of the air from the inlet to the outlet, the internal heat gradually increases, that is, the thermal stress of the air outlet side tube sheet 108 is significantly greater than that of the air inlet side tube sheet 104. In order to avoid the failure of the high-temperature air preheater components, a non-metallic expansion joint 301 on the air inlet side is provided between the air inlet side tube sheet 104 and the air inlet side end partition 105, and a non-metallic expansion joint 302 on the air outlet side is provided between the air outlet side tube sheet 108 and the air outlet side end partition 107, so as to form a flexible connection between the pipeline and the partition and the tube sheet. In this way, even when the pipeline expands or contracts due to temperature changes, the non-metallic expansion joint can absorb this part of the change through its own deformation, thereby reducing the stress on the tube sheet and preventing the component from failing.
[0031] For the flue gas side, the high-temperature process flue gas enters the shell side 203 from the external tube sheet 201 on the flue gas inlet side and the internal tube sheet 202 on the flue gas inlet side, and is discharged through the internal tube sheet 204 on the flue gas outlet side and the external tube sheet 205 on the flue gas outlet side after passing through the shell side 203. The non-metallic expansion joint 401 on the flue gas inlet side forms a flexible connection between the external tube sheet 201 on the flue gas inlet side and the internal tube sheet 202 on the flue gas inlet side, while the non-metallic expansion joint 402 on the flue gas outlet side forms a flexible connection between the external tube sheet 205 on the flue gas outlet side and the internal tube sheet 204 on the flue gas outlet side, thereby effectively eliminating the stress deformation of the tube sheet at the end of the shell side 203 caused by the high-temperature flue gas.
[0032] As described above, it is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered within the protection scope of the present invention.
Claims
1. A high temperature air preheater structure suitable for a PDH boiler, comprising a high temperature air preheater tube side (1) and a high temperature air preheater shell side (2), characterized in that: The high-temperature air preheater tube side (1) comprises an inlet connection assembly, an outlet connection assembly and a plurality of tube sides (106), wherein the inlet connection assembly and the outlet connection assembly are symmetrically arranged, and the high-temperature air preheater shell side (2) comprises a flue gas flow connection assembly and a shell side (203), wherein the inlet connection assembly and the outlet connection assembly are respectively arranged at opposite ends of the shell side (203), and the tube side (106) is located inside the shell side (203).
2. A high temperature air preheater structure suitable for a PDH boiler according to claim 1, characterized in that: The inlet connection assembly comprises an air inlet channel (101), the air inlet channel (101) is connected to an air inlet branch (102), the air inlet branch (102) is connected to an air inlet square and round interface (103), an air inlet side tube sheet (104) is fixed to the side wall of the air inlet square and round interface (103), an air inlet side end partition (105) is provided on the side wall of the air inlet side tube sheet (104), and one end of the tube path (106) is respectively penetrated The air inlet side end baffle (105) and the side wall of the air inlet side tube sheet (104) are penetrated, and the tube side (106) is connected to the air inlet square and round interface (103), the tube side (106) is fixedly connected to the air inlet side tube sheet (104), the tube side (106) is slidably connected to the air inlet side end baffle (105), and an air inlet side non-metallic expansion joint (301) is provided between the air inlet side tube sheet (104) and the air inlet side end baffle (105); The outlet connection assembly comprises an air outlet channel (111), the air outlet channel (111) is connected to an air outlet branch (110), the air outlet branch (110) is connected to an air outlet square and round interface (109), the side wall of the air outlet square and round interface (109) is provided with an air outlet side tube sheet (108) and an air outlet side end partition (107), the air outlet square and round interface (109) is fixed to the side wall of the air outlet side tube sheet (108), the tube path (106 ) penetrates through the side walls of the air outlet side end baffle (107) and the air outlet side tube sheet (108) in sequence, and the tube side (106) is connected to the air outlet square and round interface (109), the tube side (106) is fixed to the air outlet side tube sheet (108), the tube side (106) is slidably connected to the air outlet side end baffle (107), and an air outlet side non-metallic expansion joint (302) is provided between the air outlet side end baffle (107) and the air outlet side tube sheet (108); Both ends of the shell side (203) are open, and the air outlet side end baffle (107) and the air inlet side end baffle (105) are respectively fixed to the two open ends of the shell side (203).
3. A high temperature air preheater structure suitable for a PDH boiler according to claim 1, characterized in that: The smoke flow connection assembly comprises a smoke inlet side internal tube sheet (202) and a smoke outlet side internal tube sheet (204), wherein the smoke inlet side internal tube sheet (202) and the smoke outlet side internal tube sheet (204) are respectively fixedly connected to the bottom and the top of the shell side (203), a smoke inlet side external tube sheet (201) is arranged at the bottom of the smoke inlet side internal tube sheet (202), a smoke outlet side external tube sheet (205) is arranged above the smoke outlet side internal tube sheet (204), and the smoke inlet side internal tube sheet (202) is fixedly connected to the bottom of the shell side (203) and the top of the shell side (203) and the top of the shell side (203) are fixedly connected to the bottom of the shell side (203), and a smoke inlet side external tube sheet (201) is arranged at the bottom of the smoke inlet side internal tube sheet (202), and a smoke outlet side external tube sheet (205) is arranged above the smoke outlet side internal tube sheet (204). A non-metallic expansion joint (401) on the smoke inlet side is provided between the tube sheet (202) and the external tube sheet (201) on the smoke inlet side, and a non-metallic expansion joint (402) on the smoke outlet side is provided between the internal tube sheet (204) on the smoke outlet side and the external tube sheet (205) on the smoke outlet side. Through openings for smoke circulation are provided on the internal tube sheet (202) on the smoke inlet side, the internal tube sheet (204) on the smoke outlet side, the internal tube sheet (202) on the smoke inlet side, and the external tube sheet (201) on the smoke inlet side.
4. A high temperature air preheater structure suitable for a PDH boiler according to claim 1, characterized in that: The tube passes (106) are distributed at equal intervals.
5. A high temperature air preheater structure suitable for a PDH boiler according to claim 4, characterized in that: The two ends of the tube pass (106) are respectively fixed to the air inlet side tube plate (104) and the air outlet side tube plate (108) by welding.
6. A high temperature air preheater structure suitable for a PDH boiler according to claim 5, characterized in that: The tube side (106) is made of nickel-based alloy material.