A super high temperature and high pressure bayonet tube heat exchanger

Abstract

The present invention relates to the field of heat exchangers, and specifically to an ultra-high temperature and high pressure bayonet tube heat exchanger. In order to develop a heat exchange device that is simple, efficient, cost-saving and can operate safely and stably, in this solution, the end cover, tube box, tube sheet and shell are sequentially connected from left to right. The outlet header is inside the tube box, and the outlet pipe of the outlet header is inside the tube side outlet at the top of the tube box. There is a tube side inlet at the bottom of the tube box. A number of bayonet tube inner tubes connected to the outlet header are respectively arranged inside a bayonet tube outer tube. There is a gap between the bayonet tube outer tube and the bayonet tube inner tube. The bayonet tube outer tube is inserted on the tube sheet, and the space inside the bayonet tube outer tube is communicated with the space inside the tube box. The right end of the bayonet tube outer tube is sealed and arranged inside the shell. The shell jacket is inside the shell. The inlet pipe of the shell jacket is inside the shell side inlet at the bottom of the shell. There is a shell side outlet at the top of the shell. The shell jacket is arranged outside a number of bayonet tube outer tubes. There is an outlet left on the left side of the shell jacket. This solution improves the heat exchange efficiency.

Description

Technical Field

[0001] The present invention relates to the field of heat exchangers, in particular to an ultra-high temperature and high pressure bayonet tube heat exchanger, and especially a novel bayonet tube structure heat exchanger suitable for ultra-high temperature and high pressure media with strong corrosiveness. Background Art

[0002] The deterioration of the environment and the shortage of energy have further led to the development of process industries such as power generation, petroleum, and chemical industries towards high temperature, high pressure, and large scale, so as to improve the efficiency of the device and the energy utilization efficiency, and at the same time put forward higher requirements for the safety and reliability of the equipment. In the petrochemical field, the highest design temperature of the furnace tubes of ethylene cracking furnaces reaches 1150 °C, the design temperature of the furnace tubes of ammonia synthesis hydrogen production reformers is 900 °C, and the temperature of the hydrogenation reaction device reaches 565 °C, and the pressure reaches 28 MPa.

[0003] In the power generation field, the operating parameters of the ultra-supercritical thermal power units developed by the US Department of Energy can reach 35 Mpa and 760 °C. The outlet temperature of the core of the new high-temperature gas-cooled reactor nuclear power plant is above 1000 °C.

[0004] Generally, the equipment needs to operate stably for a long time at a high temperature above 900 °C and a pressure greater than 20 Mpa, transfer heat to the cold-side working fluid, and both the hot-side medium inlet and the cold-side medium outlet are at a high temperature above 850 °C. At this time, the heating surface material of the heat exchanger may withstand a high temperature above 800 °C. Since the equipment has a high-temperature heat exchange condition of 920 °C to 850 °C, and the working pressures of the hot and cold fluids are both as high as 25 MPa, and the maximum temperature difference reaches 495 °C, the relatively high working pressure difference and temperature difference between the hot and cold fluids pose a challenge to how the unit equipment operates smoothly.

[0005] In new power generation systems, more and more research and development adopt supercritical media to improve the cycle power generation efficiency of the unit. The operating conditions of supercritical media are all high temperature and high pressure, and supercritical media have extremely strong corrosiveness to castables. The main failure modes include: shell failure under high pressure, corrosion failure of the shell at high temperature, leakage failure under high temperature and high pressure, and high-temperature creep failure. Obviously, high temperature and high pressure are the main challenges faced by modern process industries. The realization of these high parameters depends on the design, manufacture, use, and maintenance of high-temperature equipment. Conventional shell-and-tube heat exchangers cannot achieve long-term stable and safe operation of the unit in terms of material selection, structural design, and strength calculation.

[0006] Therefore, developing a heat exchange device that is simple, efficient, cost-saving, and can operate safely and stably has very significant practical significance. At the same time, this type of structure can also be used in the high-temperature and high-pressure waste heat recovery systems in large gas turbines and the petrochemical field. Summary of the Invention

[0007] Objective of the Invention: In order to develop a heat exchange device that is simple, efficient, cost-saving and can operate safely and stably, the present invention proposes an ultra-high temperature and high pressure bayonet tube heat exchanger.

[0008] The present invention is implemented through the following scheme: An ultra-high temperature and high pressure bayonet tube heat exchanger, which includes an end cover, a tube box, an outlet header, a bayonet tube inner tube, a tube sheet, a bayonet tube outer tube, a shell casing and a shell;

[0009] The end cover, the tube box, the tube sheet and the shell are sequentially connected from left to right. A tube side outlet is provided at the top of the tube box, and a tube side inlet is provided at the bottom of the tube box. The outlet header is arranged in the area surrounded by the end cover, the tube box and the tube sheet. The outlet pipe of the outlet header is arranged in the tube side outlet. The right end of the outlet header is communicated with a plurality of bayonet tube inner tubes. Each bayonet tube outer tube is arranged outside a bayonet tube inner tube, and a gap is left between each bayonet tube outer tube and the bayonet tube inner tube inside the bayonet tube outer tube. The bayonet tube outer tube is inserted into the tube sheet. The left end of the bayonet tube outer tube is communicated with the space inside the tube box. The right end of the bayonet tube outer tube is arranged inside the shell, and the right end of the bayonet tube outer tube is sealed. A shell side outlet is provided at the top of the shell, and a shell side inlet is provided at the bottom of the shell. The shell casing is arranged in the area surrounded by the tube sheet and the shell. The inlet pipe of the shell casing is arranged in the shell side inlet. The shell casing is arranged outside a plurality of bayonet tube outer tubes, and an outlet is left on the left side of the shell casing.

[0010] Further, a cladding interlayer is provided inside the shell wall of the shell casing.

[0011] Still further, an inner tube interlayer is provided inside the tube wall of the bayonet tube inner tube.

[0012] Further, a plurality of limiting depressions are provided on the outer wall of the bayonet tube inner tube, and the cross-sectional area of the inner tube interlayer at the limiting depressions is smaller than that of other parts of the inner tube interlayer.

[0013] Still further, the left end of the inner tube interlayer is communicated with the bayonet tube inner tube to form a working medium inlet.

[0014] Further, an arc-shaped groove provided on the outlet header is arranged at the connection between the outlet header and the bayonet tube inner tube, and the working medium inlet is arranged in the arc-shaped groove.

[0015] Still further, the right end pipe orifice of the bayonet tube inner tube is gradually contracted.

[0016] Further, a flow limiting joint is sleeved outside the tube wall of the bayonet tube inner tube, and the outer wall of the flow limiting joint is contracted from left to right.

[0017] Still further, Wood seals are adopted between the end cover and the tube box, between the tube box and the tube sheet, and between the tube sheet and the shell.

[0018] Furthermore, heat-insulating materials are filled between the outlet pipe of the outlet header and the inner part of the tube-side outlet, and also between the inlet pipe of the housing cladding and the shell-side inlet.

[0019] Beneficial effects:

[0020] 1. This solution adds a new adiabatic cladding structure (a housing cladding is arranged inside the housing), innovates the flow mode inside the bayonet tube, realizes pure countercurrent flow, and improves the heat transfer efficiency. In the new type of bayonet tube heat exchanger, the cold side enters from the outer tube of the tube side, and the hot side enters the newly added adiabatic cladding on the shell side, which raises the temperature limit that the hot side housing can bear, thereby realizing pure countercurrent heat transfer. The present invention has high heat transfer efficiency, can withstand ultra-high temperatures of 900 °C, can simultaneously withstand high pressures above 30 Mpa, large temperature differences, and strong corrosive media, and has high safety and low costs.

[0021] 2. In traditional bayonet tube heat exchangers, the hot-side medium flows through the inner tube of the tube side to avoid material selection problems. However, due to the currently excessive hot-side temperature, the requirements for the heat exchange tube material are extremely high. Therefore, it is chosen to enter the shell side first. The outer tube of the heat exchange tube is made of nickel-based alloy, the inner tube and the casing are made of stainless steel, and a section of the housing cladding is made of nickel-based alloy, and the rest is made of stainless steel, saving costs to the greatest extent.

[0022] 3. Using a liquid-phase medium to balance the pressure inside the bayonet tube is more adaptable to the flexibility of system regulation compared to filling a gas-phase medium such as nitrogen in a constant-pressure housing, so as to ensure the safety and reliability of the equipment under various working conditions.

[0023] 4. The manufacturing and processing process is simple, the equipment runs stably and reliably, and the thermal expansion of the heat exchange elements is not restricted. Description of the drawings

[0024] Figure 1 is a schematic diagram of a super-high temperature and high pressure bayonet tube heat exchanger of the present invention;

[0025] Figure 2 is a schematic diagram of the housing of a super-high temperature and high pressure bayonet tube heat exchanger of the present invention;

[0026] Figure 3 is an internal enlarged view of the present invention.

[0027] Reference numerals: 1. end cover; 2. tube box; 3. outlet header; 4. inner bayonet tube; 5. inner tube interlayer; 6. tube sheet; 7. outer bayonet tube; 8. housing cladding; 9. housing; 10. cladding interlayer; 11. flow-limiting joint; N1. tube-side outlet; N2. tube-side inlet; N3. shell-side outlet; N4. shell-side inlet. Detailed implementation manners

[0028] Combined with Figure 1-2 to illustrate this detailed implementation manner.

[0029] Embodiment 1: A super-high temperature and high-pressure bayonet tube heat exchanger, which includes an end cover 1, a tube box 2, an outlet header 3, a bayonet tube inner tube 4, a tube sheet 6, a bayonet tube outer tube 7, a shell cladding 8 and a shell 9;

[0030] The end cover 1, the tube box 2, the tube sheet 6 and the shell 9 are sequentially connected from left to right. A tube side outlet N1 is provided at the top of the tube box 2, and a tube side inlet N2 is provided at the bottom of the tube box 2. The outlet header 3 is arranged in the area surrounded by the end cover 1, the tube box 2 and the tube sheet 6. The outlet pipe of the outlet header 3 is arranged in the tube side outlet N1. The right end of the outlet header 3 is communicated with a plurality of bayonet tube inner tubes 4. Each bayonet tube outer tube 7 is arranged outside a bayonet tube inner tube 4, and a gap is left between each bayonet tube outer tube 7 and the bayonet tube inner tube 4 inside the bayonet tube outer tube 7. The bayonet tube outer tube 7 is inserted on the tube sheet 6. The left end of the bayonet tube outer tube 7 is communicated with the space inside the tube box 2. The right end of the bayonet tube outer tube 7 is arranged inside the shell 9, and the right end of the bayonet tube outer tube 7 is sealed. A shell side outlet N3 is provided at the top of the shell 9, and a shell side inlet N4 is provided at the bottom of the shell 9. The shell cladding 8 is arranged in the area surrounded by the tube sheet 6 and the shell 9. The inlet pipe of the shell cladding 8 is arranged in the shell side inlet N4. The shell cladding 8 is arranged outside a plurality of bayonet tube outer tubes 7, and an outlet is left on the left side of the shell cladding 8.

[0031] In this embodiment: The temperature of the shell side medium in the shell 9 is the highest. First, it enters the inside of the shell cladding 8 from the shell side inlet N4 and exchanges heat with the bayonet tube outer tube 7 in a pure countercurrent manner, and the temperature drops rapidly. Then it flows out from the left side of the shell cladding 8, flows into the gap between the shell cladding 8 and the shell 9, and flows out from the shell side outlet N3 of the shell 9. The tube side of the tube box 2 enters from the tube side inlet N2 and enters the bayonet tube outer tube 7 from the tube sheet. After completing the heat exchange with the highest temperature on the shell side, it enters the bayonet tube inner tube 4 and the dead zone of the inner tube sandwich 5 of the bayonet tube inner tube 4, flows out from the inner tube and then enters the 3 headers, and flows out from the tube box outlet.

[0032] Embodiment 2: A super-high temperature and high-pressure bayonet tube heat exchanger, and a cladding sandwich 10 is provided inside the shell wall of the shell cladding 8.

[0033] In this embodiment: A cladding sandwich 10 is provided inside the shell wall of the shell cladding 8, which can play a role in heat preservation and insulation and enhancing the heat exchange effect.

[0034] Other embodiments are the same as Embodiment 1.

[0035] Embodiment 3: A super-high temperature and high-pressure bayonet tube heat exchanger, and an inner tube sandwich 5 is provided inside the tube wall of the bayonet tube inner tube 4.

[0036] In this embodiment: An inner tube sandwich 5 is provided inside the tube wall of the inner tube 4, which can play a role in heat preservation and insulation and enhancing the heat exchange effect.

[0037] Other embodiments are the same as those of the first specific embodiment.

[0038] Specific embodiment four: A super high temperature and high pressure bayonet tube heat exchanger, on the outer wall of the inner tube 4 of the bayonet tube, there are a plurality of restricted depression areas, and the cross-sectional area of the inner tube sandwich layer 5 at the restricted depression areas is smaller than that of the inner tube sandwich layer 5 at other parts.

[0039] Other embodiments are the same as those of the third specific embodiment.

[0040] Specific embodiment five: A super high temperature and high pressure bayonet tube heat exchanger, the left end of the inner tube sandwich layer 5 is connected to the inner tube 4 of the bayonet tube to form a working medium inlet.

[0041] In this embodiment: At the inner tube sandwich layer 5, there is only a working medium inlet and no working medium outlet. The working medium only enters and does not exit, playing a role in heat preservation and insulation.

[0042] Other embodiments are the same as those of the third specific embodiment.

[0043] Specific embodiment six: A super high temperature and high pressure bayonet tube heat exchanger, at the connection between the outlet header 3 and the inner tube 4 of the bayonet tube, there is an arc-shaped groove provided on the outlet header 3, and the working medium inlet is arranged in the arc-shaped groove.

[0044] In this embodiment: With such a setting, the length of the inner tube sandwich layer is slightly shorter than the length of the inner tube 4 of the bayonet tube. The longer inner tube sandwich layer can better form heat preservation and insulation for the working medium in the inner tube 4 of the bayonet tube.

[0045] Other embodiments are the same as those of the fifth specific embodiment.

[0046] Specific embodiment seven: A super high temperature and high pressure bayonet tube heat exchanger, the right end pipe orifice of the inner tube 4 of the bayonet tube is arranged to gradually contract.

[0047] Other embodiments are the same as those of the first specific embodiment.

[0048] Specific embodiment eight: A super high temperature and high pressure bayonet tube heat exchanger, a flow limiting joint 11 is sleeved outside the tube wall of the inner tube 4 of the bayonet tube, and the outer wall of the flow limiting joint 11 is arranged to contract from left to right.

[0049] In this embodiment: In this embodiment, the flow limiting joint on the one hand supports the inner tube 4 of the bayonet tube in the outer tube 7 of the bayonet tube, and on the other hand, can reduce the flow rate of the working medium to avoid the working medium flowing too fast.

[0050] Other embodiments are the same as those of the first specific embodiment.

[0051] Specific embodiment nine: A super high temperature and high pressure bayonet tube heat exchanger, Wood seals are used between the end cover 1 and the tube box 2, between the tube box 2 and the tube sheet 6, and between the tube sheet 6 and the shell 9.

[0052] In this embodiment: Wood seals are used between the end cover 1 and the tube sheet 2, between the tube sheet 2 and the tube plate 6, and between the tube plate 6 and the shell 9, providing good sealing effect.

[0053] Other embodiments are the same as the first specific embodiment.

[0054] Tenth specific embodiment: A super high temperature and high pressure bayonet tube heat exchanger, characterized in that: heat insulating materials are filled between the outlet pipe of the outlet header 3 and the tube side outlet N1, and also between the inlet pipe of the shell casing 8 and the shell side inlet N4, which can ensure the temperature of the working fluid and avoid the over-temperature of the metal temperature of the equipment.

[0055] In this embodiment:

[0056] Other embodiments are the same as the first specific embodiment.

[0057] Working principle:

[0058] The temperature of the medium at the outlet of the tube sheet of this equipment is as high as 850°C. To avoid the high-temperature medium directly contacting the tube plate and the cylinder body of the tube sheet, an outlet header is set, and bayonet type heat exchange tubes are used. Heat insulating materials are set at the tube side inlet. After the high-temperature medium exchanges heat through the inner tube and the outer tube of the bayonet tube, it returns to the cold end of the tube side (entering the outlet header). In terms of the details of the structural design, due to the high temperature and pressure, a fully self-tight Wood seal is adopted for sealing in this solution. The tube side inlet and the tube side outlet are respectively connected to the high-temperature inlet nozzle and the high-temperature outlet nozzle. Cooling water jackets are arranged outside the high-temperature inlet nozzle and the high-temperature outlet nozzle to reduce the metal temperature. Expansion joints are arranged between the high-temperature inlet nozzle and the high-temperature outlet nozzle and the tube sheet, which can better expand at high temperature at the outlet.

[0059] The temperature of the medium on the shell side of the shell is the highest. It first enters the interior of the shell casing on the shell side and exchanges heat with the heat exchange tubes in a pure countercurrent manner, and the temperature drops rapidly. Then it flows out from the other side of the shell casing, flows into the dead zone of the casing sandwich and the gap between the casing and the shell, and flows out from the shell side outlet. By setting the casing and the casing sandwich, the heat transfer efficiency can be improved, the shell can be prevented from directly contacting the high-temperature medium, and the temperature limit that the hot side shell can bear can be directly increased.

[0060] The medium on the tube side of the tube sheet enters from the tube side inlet, then enters the outer tube of the bayonet tube at the tube plate, completes the heat exchange with the highest temperature on the shell side of the shell, enters the inner tube of the bayonet tube, flows out from the inner tube of the bayonet tube and then enters the outlet header, and flows out from the outlet of the tube sheet of the tube side outlet. There is only an inlet and no outlet for the medium in the dead zone of the inner tube sandwich of the inner tube of the bayonet tube, so there is no flow. At the same time, the temperature of the medium in the inner tube sandwich is relatively high, which has a heat preservation effect on the fluid in the inner tube of the bayonet tube and improves the heat exchange efficiency.

Claims

1. A super high temperature and high pressure bayonet tube heat exchanger, characterized in that: It includes an end cover (1), a tube box (2), an outlet header (3), a bayonet tube inner tube (4), a tube sheet (6), a bayonet tube outer tube (7), a shell cladding (8) and a shell (9); The end cover (1), the tube box (2), the tube sheet (6) and the shell (9) are sequentially connected from left to right. A tube side outlet (N1) is provided at the top of the tube box (2), and a tube side inlet (N2) is provided at the bottom of the tube box (2). The outlet header (3) is arranged in the area surrounded by the end cover (1), the tube box (2) and the tube sheet (6). The outlet pipe of the outlet header (3) is arranged in the tube side outlet (N1). The right end of the outlet header (3) is communicated with a plurality of bayonet tube inner tubes (4). Each bayonet tube outer tube (7) is arranged outside a bayonet tube inner tube (4), and a gap is left between each bayonet tube outer tube (7) and the bayonet tube inner tube (4) inside the bayonet tube outer tube (7). The bayonet tube outer tube (7) is inserted into the tube sheet (6). The left end of the bayonet tube outer tube (7) is communicated with the space inside the tube box (2). The right end of the bayonet tube outer tube (7) is arranged inside the shell (9), and the right end of the bayonet tube outer tube (7) is sealed. A shell side outlet (N3) is provided at the top of the shell (9), and a shell side inlet (N4) is provided at the bottom of the shell (9). The shell cladding (8) is arranged in the area surrounded by the tube sheet (6) and the shell (9). The inlet pipe of the shell cladding (8) is arranged in the shell side inlet (N4). The shell cladding (8) is arranged outside a plurality of bayonet tube outer tubes (7), and the shell cladding (8) has an outlet; An inner tube interlayer (5) is arranged inside the tube wall of the bayonet tube inner tube (4); A plurality of limiting depressions are arranged on the outer wall of the bayonet tube inner tube (4), and the cross-sectional area of the inner tube interlayer (5) at the limiting depression is smaller than the cross-sectional area of the inner tube interlayer (5) at other parts; The left end of the inner tube interlayer (5) is communicated with the bayonet tube inner tube (4) to form a working medium inlet.

2. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, wherein: A cladding interlayer (10) is arranged inside the shell wall of the shell cladding (8).

3. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, characterized in that: An arc-shaped groove provided on the outlet header (3) is arranged at the connection between the outlet header (3) and the bayonet tube inner tube (4), and the working medium inlet is arranged in the arc-shaped groove.

4. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, characterized in that: The right end pipe orifice of the bayonet tube inner tube (4) is arranged to gradually contract.

5. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, characterized in that: A flow-limiting joint (11) is sleeved outside the tube wall of the bayonet tube inner tube (4), and the outer wall of the flow-limiting joint (11) is arranged to contract from left to right.

6. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, wherein: Wood seals are adopted between the end cover (1) and the tube box (2), between the tube box (2) and the tube sheet (6), and between the tube sheet (6) and the shell (9).

7. The ultra-high temperature and high pressure bayonet tube heat exchanger according to claim 1, characterized in that: Heat-insulating materials are filled between the outlet pipe of the outlet header (3) and the tube side outlet (N1), and heat-insulating materials are also filled between the inlet pipe of the shell cladding (8) and the shell side inlet (N4).

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