Radial tube core heat pipe heat exchanger for flue gas waste heat recovery

Abstract

The application provides a radial-tube-core heat pipe heat exchanger for flue gas waste heat recovery, which is provided with single or multiple heat pipe heat exchange modules in the direction of flue gas flow, the heat pipe heat exchange modules are provided with single or multiple heat exchange units, the heat exchange units comprise several groups of heat pipe bundle groups arranged side by side in the direction of flue gas flow, adjacent heat pipe bundle groups are connected through connecting elbows to form serpentine pipelines in series, the heat pipe bundle group comprises at least one column of radial-tube-core heat pipes arranged from top to bottom in sequence, the radial-tube-core heat pipe comprises an outer tube and an inner tube arranged from outside to inside in sequence, a vacuum clamping cavity is arranged between the outer tube and the inner tube, a working medium is arranged in the vacuum clamping cavity, and heat medium water is arranged in the inner tube. Acid dew point corrosion of the radial-tube-core heat pipe only occurs on the outer tube, and the inner tube does not have any corrosion phenomenon, so that the heat medium water leakage problem caused by flue gas abrasion and acid dew point corrosion can be greatly relieved, and the service life of the heat exchanger is prolonged.

Description

[Technical Field]

[0001] This invention relates to the technical field of heat exchangers, and in particular to a radial heat pipe heat exchanger with a core for flue gas waste heat recovery. [Background Technology]

[0002] Flue gas loss is the most significant energy loss during boiler operation. Effectively utilizing waste heat from flue gas is crucial for power plants to achieve energy conservation, emission reduction, and environmental protection. In the power industry, heat exchangers are often installed after the boiler's tail flue and before the electrostatic precipitator, or after the electrostatic precipitator and before the desulfurization tower, to achieve deep utilization of waste heat from flue gas.

[0003] Existing heat exchangers generally employ finned heat exchangers, which enhance heat transfer by adding fins to ordinary base tubes. Condensate flows through the steel tubes, and the heat from the flue gas is transferred to the internal condensate through the fins tightly wound around the steel tubes. Cooled flue gas reduces the energy consumption of electrostatic precipitators and desulfurization towers, while heated condensate is used in equipment such as reheaters. However, during boiler operation, the high concentration of fly ash and the high flue gas velocity cause high-speed erosion of the heat exchange tubes, resulting in wear, reduced strength of the heat exchange tube assembly, and increased susceptibility to leaks. Simultaneously, uneven surface temperature of the heat exchange tubes can lead to acid dew point corrosion in practical applications, and also reduces flue gas velocity, easily causing ash blockage. These problems severely affect the service life of the heat exchanger equipment and the normal operation of the heat exchange system. [Summary of the Invention]

[0004] The purpose of this invention is to solve the problems in the prior art and propose a radial heat pipe heat exchanger with a core for flue gas waste heat recovery, which can alleviate the problem of heat transfer fluid leakage caused by flue gas wear and acid dew point corrosion, and extend the service life of the heat exchanger.

[0005] To achieve the above objectives, this invention proposes a radially cored heat pipe heat exchanger for flue gas waste heat recovery. It comprises one or more heat pipe heat exchange modules arranged along the flue gas flow direction. Each heat pipe heat exchange module has one or more heat exchange units. Each heat exchange unit includes several groups of heat pipe bundles arranged side-by-side along the flue gas flow direction. Adjacent heat pipe bundles are connected in series via connecting elbows to form a serpentine pipeline. Each heat pipe bundle includes at least one row of radially cored heat pipes arranged sequentially from top to bottom. Each radially cored heat pipe includes an outer tube and an inner tube arranged sequentially from the outside to the inside. A vacuum cavity exists between the outer tube and the inner tube, containing a working fluid. The inner tube contains water as a heat transfer medium.

[0006] Preferably, the heat exchange unit further includes an inlet water header and an outlet water header, with the inlet end of the heat exchange unit connected to the inlet water header and the outlet end connected to the outlet water header.

[0007] Preferably, the heat exchange unit further includes a module intermediate support plate and module end plates disposed on both sides of the module intermediate support plate, wherein the radially cored heat pipes are installed on the module end plates on both sides and pass through the intermediate support plate.

[0008] Preferably, the outer tube is a finned tube.

[0009] Preferably, the inner tube is a light tube.

[0010] Preferably, the radially ferrule heat pipe is arranged horizontally.

[0011] Preferably, the inner wall of the outer tube also has a liquid-absorbing core.

[0012] Preferably, the heat pipe heat exchange module is in multiple groups, and two adjacent heat pipe heat exchange modules are connected in series through module connecting pipes to form a circulation pipeline.

[0013] Preferably, a connecting flue is provided between two adjacent heat pipe heat exchange modules, and the connecting flue is sealed to the heat pipe heat exchange module.

[0014] Preferably, both ends of the connecting flue are equipped with a soot blowing system.

[0015] The beneficial effects of this invention are:

[0016] 1. Radial core heat pipes consist of an inner tube and an outer tube. Wear first occurs on the outer tube (finned tube), while the inner tube (plain tube) will not show any signs of wear. Furthermore, acid dew point corrosion of radial core heat pipes only occurs on the outer tube (finned tube), while the inner tube (plain tube) will not show any corrosion. This can greatly alleviate the problem of heat transfer fluid leakage caused by flue gas wear and acid dew point corrosion, and extend the service life of the heat exchanger.

[0017] 2. Compared to ordinary finned tubes, radial heat pipes with cores have a larger contact area with flue gas (because heat pipes with cores consist of an inner tube and an outer tube; if the inner tube diameter is too small, heat exchange cannot be effective; therefore, in the case of an inner tube, the outer tube diameter will be larger than that of a conventional heat exchange tube, thus resulting in a larger contact area with flue gas). After being heated, the vapor and liquid in the jacket continuously alternate, giving the heat pipe a higher heat exchange efficiency.

[0018] 3. Compared to traditional heat exchange tubes, the inner tube (plain tube) of radial heat pipes with cores does not directly contact the flue gas, and the material requirements of the inner tube (plain tube) can be appropriately reduced.

[0019] 4. Compared to conventional vertically arranged gravity heat pipe heat exchangers (where the fins and heat exchange tubes are perpendicular to each other, and when the heat exchange tubes are arranged vertically, the fins are horizontal, and fly ash will accumulate between the fins and is not easy to fall off), radial heat pipe heat exchangers with tube cores adopt the traditional horizontal arrangement, which can more effectively reduce ash accumulation.

[0020] 5. Compared with ordinary finned tube heat exchangers, radial heat pipe heat exchangers with tube cores are vapor-liquid phase change heat exchangers, which greatly improves heat exchange efficiency.

[0021] 6. Radial heat pipe heat exchangers with tube cores can have a lower requirement for the temperature of the heat transfer medium compared to traditional heat exchangers (because heat pipes with tube cores have advantages such as low thermal resistance and fast heat transfer. When the inlet heat transfer medium temperature is appropriately reduced, the outlet heat transfer medium temperature can also reach the required temperature). Under the same operating conditions, the heat exchange efficiency is better.

[0022] 7. Radial heat pipe heat exchangers with tube cores, compared to traditional heat exchangers, use water in a vacuum within the jacket as the heat exchange medium. They can also achieve efficient heat exchange when the temperature difference between the flue gas and the heat transfer medium water is small.

[0023] The features and advantages of the present invention will be described in detail through embodiments and in conjunction with the accompanying drawings. [Attached Image Description]

[0024] Figure 1 This is a schematic diagram of a radial heat pipe heat exchanger with a core for flue gas waste heat recovery according to the present invention.

[0025] Figure 2 This is a schematic diagram of the heat exchange unit of the present invention;

[0026] Figure 3 This is a schematic diagram of the radial heat pipe with a core according to the present invention;

[0027] Figure 4 yes Figure 3 AA-direction cross-section.

Detailed Implementation Methods

[0028] See Figures 1 to 2This invention discloses a radially cored heat pipe heat exchanger for flue gas waste heat recovery. It comprises one or more heat pipe heat exchange modules 1 arranged along the flue gas flow direction. Each heat pipe heat exchange module 1 has one or more heat exchange units 100. In this embodiment, the heat pipe heat exchange module 1 has several heat exchange units 100 arranged sequentially from top to bottom on the flue gas contact surface. Each heat exchange unit 100 includes several groups of heat pipe bundles arranged side-by-side along the flue gas flow direction. Adjacent heat pipe bundles are connected in series via connecting elbows 104 to form a serpentine pipeline. Each heat pipe bundle includes... At least one row of radially coiled heat pipes 101 arranged from top to bottom, each comprising an outer tube 1011 and an inner tube 1012 arranged from the outside to the inside, with a vacuum cavity between the outer tube 1011 and the inner tube 1012. The vacuum cavity contains a working fluid (generally distilled water), and the inner tube 1012 contains a heat transfer medium (water). The outer tube 1011 is located outside the inner tube 1012, forming an inner-outer structure. A leak-proof vacuum is maintained between the outer tube 1011 and the inner tube 1012. The structural arrangement is as follows: Figure 2 As shown.

[0029] Further, see Figures 1 to 2 The heat exchange unit 100 further includes an inlet water header 105 and an outlet water header 106. The inlet end of the heat exchange unit 100 is connected to the inlet water header 105, and the outlet end is connected to the outlet water header 106. When there are multiple heat pipe heat exchange modules 1, the outlet water header 106 of one heat pipe heat exchange module 1 is connected in series with the inlet water header 105 of another heat pipe heat exchange module 1 through the module connecting pipe 4.

[0030] Further, see Figures 1 to 2 The heat exchange unit 100 also includes a module intermediate support plate 102 and module end plates 103 disposed on both sides of the module intermediate support plate 102. The radially cored heat pipe 101 is installed on the module end plates 103 on both sides and passes through the intermediate support plate 102.

[0031] Further, see Figure 3 and Figure 4 The outer tube 1011 is a finned tube, and the inner tube 1012 is a plain tube. In this embodiment, the outer tube 1011 is made of ND steel or a material of the same or higher grade that is resistant to acid dew point corrosion. The outer tube can be made of conventional untreated outer surface or enamel outer surface. The outer tube 1011 is a high-frequency welded finned tube or an integrally rolled finned tube. The inner tube can be made of a lower grade material, such as 20 or 20G.

[0032] Further, see Figure 1 and Figure 2The radially cored heat pipe 101 is arranged horizontally, which can effectively reduce dust accumulation. The processing quality of the radially cored heat pipe 101 can be adjusted according to different operating conditions. Before being assembled into a heat pipe heat exchange module, the radially cored heat pipe 101 is a heat pipe that has been filled with working fluid, vacuum treated and heat exchange efficiency tested.

[0033] Further, see Figure 4 The inner wall of the outer tube 1011 also has a liquid-absorbing core 1013. Common liquid-absorbing cores 1013 include metal wound wire mesh liquid-absorbing cores, axial channel liquid-absorbing cores, sintered metal liquid-absorbing cores, etc. The liquid-absorbing cores are distributed on the inner wall of the outer tube, so that the working fluid water wets the inner wall of the outer tube, thereby reducing the temperature of the outer wall of the outer tube, accelerating the phase change heat transfer inside the tube, and thus enhancing the heat transfer capacity of the heat pipe.

[0034] Furthermore, the heat pipe heat exchange module 1 is in multiple sets, and adjacent heat pipe heat exchange modules 1 are connected in series through module connecting pipes 4 to form a circulation pipeline. Specifically, in this embodiment, the heat pipe heat exchange module 1 is in two sets.

[0035] Furthermore, a connecting flue 3 is provided between two adjacent heat pipe heat exchange modules 1, and the connecting flue 3 is sealed to the heat pipe heat exchange module 1. A soot blowing system 2 is provided at both ends of the connecting flue 3, and the soot blowing system 2 is a steam soot blowing system or an acoustic soot blowing system.

[0036] Working process of this invention:

[0037] See Figure 1 When there are multiple heat pipe heat exchange modules 1, each module is connected in series using module connecting pipe 4. When the flue gas flows from left to right, the heat transfer medium water is ensured to enter from the right and exit from the left, and enter from the bottom and exit from the top. When the radial heat pipe heat exchanger with tube core comes into contact with the flue gas, the flue gas contacts the surface of the outer tube 1011 (finned tube), realizing the first heat exchange and transferring the heat to the working medium inside the tube. The working medium then undergoes a second heat exchange with the inner tube 1012 (bare tube), heating the heat transfer medium water inside the inner tube 1012 and re-liquefying it. By repeating the above two-phase gas-liquid cycle, efficient waste heat recovery and utilization of the flue gas is achieved. At the same time, the flue gas contacts the outer tube 1011 of the radial heat pipe with tube core 101, rather than directly contacting the inner tube 1012 containing the heat transfer medium water, which enables the radial heat pipe heat exchanger with tube core to achieve long-term and efficient operation.

[0038] The above embodiments are illustrative of the present invention and are not intended to limit the present invention. Any simple modifications to the present invention are within the scope of protection of the present invention.

Claims

1. A radial-tube-core heat pipe heat exchanger for flue gas waste heat recovery, characterized by: Single or multiple heat pipe heat exchange modules (1) are arranged along the direction of flue gas flow, the heat pipe heat exchange module (1) is provided with single or multiple heat exchange units (100), the heat exchange unit (100) comprises a plurality of heat pipe bundle groups arranged side by side along the direction of flue gas flow, adjacent heat pipe bundle groups are connected through connecting elbows (104) to form a serpentine pipe in series, the heat pipe bundle group comprises at least one column of radial heat pipes (101) arranged from top to bottom in sequence, the radial heat pipe (101) comprises an outer tube (1011) and an inner tube (1012) arranged in sequence from outside to inside, the outer tube (1011) and the inner tube (1012) have a vacuum clamping cavity, the vacuum clamping cavity is provided with a working medium, the inner tube (1012) is provided with heat medium water, the heat exchange unit (100) further comprises a water inlet header (105) and a water outlet header (106), the water inlet end of the heat exchange unit (100) is connected with the water inlet header (105), and the water outlet end is connected with the water outlet header (106), the heat exchange unit (100) further comprises a module intermediate support plate (102) and a module end plate (103) arranged on both sides of the module intermediate support plate (102), the radial heat pipe (101) is installed on the module end plate (103) on both sides and passes through the intermediate support plate (102), the heat pipe heat exchange module (1) is multiple, two adjacent heat pipe heat exchange modules (1) are connected in series to form a circulating pipe through a module connecting pipe (4), a connecting flue (3) is arranged between two adjacent heat pipe heat exchange modules (1), the connecting flue (3) is sealed with the heat pipe heat exchange module (1), and a soot blowing system (2) is arranged at both ends of the connecting flue (3).

2. A radial-tube-core heat pipe heat exchanger for flue gas waste heat recovery as claimed in claim 1, characterized in that: The outer tube (1011) is a finned tube.

3. A radial-finned-tube heat pipe heat exchanger for flue gas heat recovery as claimed in claim 1, wherein: The inner tube (1012) is a light tube.

4. A radial-finned-tube heat pipe heat exchanger for flue gas heat recovery as claimed in claim 1, wherein: The radial heat pipe (101) is arranged horizontally.

5. A radial-finned-tube heat pipe heat exchanger for flue gas heat recovery as claimed in claim 1, wherein: The inner wall of the outer tube (1011) further has a liquid absorbing core (1013).

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