Preposed heat pipe heat exchanger

Abstract

The utility model provides a preposed heat pipe heat exchanger which is installed at an outlet of an air pre-heater, the heat exchanger comprises a heat exchanger shell and a heat exchange module, the heat exchange module is installed in the heat exchanger shell, the heat exchange module comprises a vacuum heat pipe and fins, the vacuum heat pipe comprises an evaporation section, a heat insulation section and a condensation section, and the fins are installed in the heat exchanger shell. The air pre-heater has the advantages that the heat exchanger is simple in structure and installed at an outlet of the air pre-heater, the comprehensive temperature of the cold end of the air pre-heater is improved, gas-gas heat exchange is achieved through the high heat transfer efficiency of the vacuum heat pipes, and circulating systems such as external water media are not needed; cold primary air and cold secondary air can be heated at the same time; a vacuum valve is arranged at the top of the heat pipe, so that non-condensable gas can be eliminated, and a working medium can also be filled to recover the failed heat pipe; the heat exchange tubes and the fins are in a low-resistance form, the direction of the fins is consistent with the flow direction of flue gas, the flue gas side resistance of equipment can be reduced, and therefore the problem of blockage of ammonium bisulfate at the cold end is relieved.

Description

Technical Field

[0001] This utility model relates to the field of heat exchanger technology, and in particular to a pre-heat pipe heat exchanger. Background Technology

[0002] During combustion, most of the sulfur in boiler fuel is converted to SO2, but 1% to 5% is converted to SO3. When the wall temperature of the heat exchange elements is lower than the acid dew point temperature, sulfuric acid vapor condenses on the wall surface, corroding the heat exchange elements and continuously adhering to fly ash, clogging the channels, reducing the heat exchange efficiency and service life of the heat exchange elements, and affecting the safe and economical operation of the air preheater. In addition, ammonia escaping after denitrification comes into contact with SO3 to form NH4HSO4 and (NH4)2SO4. These compounds are highly adhesive liquid substances at 150–230°C, which will deposit in the medium-temperature section and cold end of the air preheater, adsorbing particulate matter in the flue gas, causing a large amount of ash to adhere to the metal surface and interlayer of the heat exchanger, causing blockage of the heat exchange elements.

[0003] As the operating time of water-based heat exchangers increases, pipe leaks gradually become more frequent. The methods for handling leaks in water-based heat exchangers are limited; pipe replacement and leak location are extremely difficult, and individual pipe repairs and replacements are not feasible. After a leak, the entire module must be isolated and inspected during unit maintenance. This module-based outage due to leaks results in a low and declining operational rate for water-based heat exchangers. Utility Model Content

[0004] To overcome the aforementioned problems in the prior art, this utility model provides a preheating heat pipe heat exchanger suitable for increasing the overall temperature of the cold end of an air preheater and alleviating the blockage of ammonium bisulfate at the cold end.

[0005] This utility model discloses a preheating heat pipe heat exchanger installed at the outlet of an air preheater. The heat exchanger includes a heat exchanger shell and a heat exchange module. The heat exchange module is installed inside the heat exchanger shell and includes a vacuum heat pipe and fins. The vacuum heat pipe includes an evaporation section, an insulation section, and a condensation section. The heat exchange module includes a flue gas side and an air side. An insulation section partition is provided between the flue gas side and the air side, and the insulation section partition divides the tube bundle of the vacuum heat pipe into an evaporation section and a condensation section.

[0006] Based on this, the heat exchange module is installed at an angle ranging from 8 to 10 degrees.

[0007] Based on this, the cross-sectional area of ​​the heat exchange module is 20-40m². 2 The length of the heat exchange tube is 5-10m.

[0008] Based on this, the vacuum heat pipe adopts a circular or elliptical tube, the fins adopt spiral fins or toothed fins, the fin direction is consistent with the flue gas flow direction, and fins are installed on both the flue gas side and the air side. The flue gas side adopts carbon steel fins, and the air side adopts aluminum fins.

[0009] Based on this, the vacuum heat pipe uses steel pipes produced by precision rolling and undergoes degreasing, acid washing, and alkali washing. The working fluid inside the vacuum heat pipe is demineralized water, with added corrosion inhibitors and hydrogen absorbers.

[0010] Based on this, a vacuum valve is installed on the top of the vacuum heat pipe.

[0011] Based on this, the heat exchanger is equipped with one or more of the heat exchange modules.

[0012] Based on this, a connecting flue is provided between the heat exchanger and the air preheater. The air-side flue is provided with cold primary air and secondary air inlets, cold primary air and secondary air inlet reducers, hot primary air and secondary air outlet reducers, and hot primary air and secondary air outlets. The flue gas-side flue is provided with a flue gas inlet, a flue gas inlet reducer, a flue gas outlet reducer, and a flue gas outlet. The heat exchanger is installed between the hot primary air and secondary air outlet reducers and the cold primary air and secondary air inlet reducers, as well as between the flue gas inlet reducer and the flue gas outlet reducer.

[0013] Based on this, temperature sensors are installed at the positions of the flue gas inlet reducer, hot primary air reducer, secondary air outlet reducer, cold primary air reducer, secondary air inlet reducer, and flue gas outlet reducer.

[0014] Based on this, the flue gas inlet reducer, hot primary air reducer, secondary air outlet reducer, heat exchanger shell, cold primary air reducer, secondary air inlet reducer, and flue gas outlet reducer are all wrapped with insulation material and insulation outer protective plate.

[0015] Compared with the prior art, the beneficial effects of this utility model are as follows: This heat exchanger has a simple structure and is installed at the outlet of the air preheater, which improves the overall temperature of the cold end of the air preheater. It utilizes the high heat transfer efficiency of the vacuum heat pipe to achieve gas-to-gas heat exchange without the need for an external water medium or other circulation system; it can simultaneously heat the cold primary air and the cold secondary air; the top of the heat pipe is equipped with a vacuum valve, which can remove non-condensable gases or fill the working fluid to restore the failed heat pipe; the heat exchange tube and fin are selected in a low-resistance form, and the fin direction is consistent with the flue gas flow direction, which can reduce the resistance on the flue gas side of the equipment, thereby alleviating the problem of ammonium bisulfate blockage at the cold end. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the front heat pipe heat exchanger of this utility model;

[0017] In the diagram: 1. Hot primary air and secondary air outlets; 2. Flue gas inlet; 3. Rotary air preheater; 4. Flue gas inlet reducer; 5. Primary air and secondary air outlet reducers; 6. Heat exchanger shell; 7. Heat exchange module; 8. Insulation section baffle; 9. Cold primary air and secondary air inlet reducers; 10. Flue gas outlet reducer; 11. Cold primary air and secondary air inlets; 12. Flue gas outlet. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0019] This utility model discloses a preheating heat pipe heat exchanger, including a heat exchanger shell 6 and a heat exchange module 7. The heat exchange module 7 is installed inside the heat exchanger shell 6 and includes a vacuum heat pipe and fins. The vacuum heat pipe includes an evaporation section, an insulation section and a condensation section. The heat exchange module 7 includes a flue gas side and an air side. An insulation section partition 8 is provided between the flue gas side and the air side to prevent flue gas leakage. The insulation section partition 8 divides the tube bundle of the vacuum heat pipe into an evaporation section and a condensation section. The flue gas side is the evaporation section, and the primary and secondary air sides are the condensation sections.

[0020] In actual operation, the heat exchanger is installed at the outlet of the air preheater 3 and connected to the connecting flue. The air-side flue is equipped with a cold primary air and secondary air inlet 11, a cold primary air and secondary air inlet reducer 9, a hot primary air and secondary air outlet reducer 5, and a hot primary air and secondary air outlet 1. The flue gas-side flue is equipped with a flue gas inlet 2, a flue gas inlet reducer 4, a flue gas outlet reducer 10, and a flue gas outlet 12. The heat exchanger is installed between the hot primary air and secondary air outlet reducer 5 and the cold primary air and secondary air inlet reducer 9, and between the flue gas inlet reducer 4 and the flue gas outlet reducer 10.

[0021] The heat exchange module 7 is installed at an angle ranging from 8 to 10 degrees in order to maintain a high heat exchange efficiency of the vacuum heat pipe; in this embodiment, the angle is set to 10 degrees.

[0022] Vacuum heat pipes use round or elliptical tubes with spiral or toothed fins. The fin direction is aligned with the flue gas flow direction to reduce flue gas side resistance. The vacuum heat pipes are made of precision-rolled steel pipes that have undergone degreasing, acid washing, and alkali cleaning. The working fluid inside the vacuum heat pipe is demineralized water with added corrosion inhibitors and hydrogen absorbers. Fins are installed on both the flue gas and air sides; the flue gas side uses carbon steel fins, and the air side uses aluminum fins. A vacuum valve is installed at the top of the vacuum heat pipe to ensure vacuum during normal operation. In case of failure, it can remove non-condensable gases or be filled with working fluid to restore the heat exchange performance of the failed vacuum heat pipe.

[0023] The cross-sectional area of ​​heat exchange module 7 can be designed according to the flue gas volume, primary air volume, and secondary air volume of different capacity units, ranging from 20-40m². 2 The unit range is 300MW-1000MW, ensuring the flow velocity between vacuum heat pipes is 9-10m / s, and the length can be determined according to the required heat exchange capacity, set to 5-10m;

[0024] Temperature sensors are installed at the following locations: flue gas inlet reducer 4, hot primary air and secondary air outlet reducer 5, cold primary air and secondary air inlet reducer 9, and flue gas outlet reducer 10. All of these locations, including flue gas inlet reducer 4, hot primary air and secondary air outlet reducer 5, heat exchanger shell 6, cold primary air and secondary air inlet reducer 9, and flue gas outlet reducer 10, are covered with insulation material and insulation outer protective panels.

[0025] When high-temperature flue gas enters the flue gas side of heat exchange module 7 from flue gas inlet 2, it heats the vacuum heat pipe in the evaporation section, causing the working fluid inside the vacuum heat pipe to change from a liquid state to a gaseous state and enter the air side. When the primary and secondary air enter the air side of heat exchange module 7 from the primary and secondary air inlet 11, the condensation section absorbs heat, causing the working fluid inside the vacuum heat pipe to change from a gaseous state to a liquid state and return to the evaporation section. This cycle repeats, transferring heat from the flue gas side to the air side, increasing the overall temperature of the cold end of the air preheater, and alleviating the problem of ammonium bisulfate blockage at the cold end.

[0026] Depending on the actual working conditions, one or more heat exchange modules 7 can be installed.

[0027] In the description of this utility model, it should be understood that the terms "coaxial", "bottom", "one end", "top", "middle", "other end", "upper", "side", "top", "inner", "front", "center", "both ends", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0028] In this utility model, unless otherwise explicitly specified and limited, the terms "installation", "setting", "connection", "fixing", "screw connection", "pad", etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0029] The foregoing description illustrates and describes preferred embodiments of the present invention. As previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or related technical or knowledge. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A front heat pipe heat exchanger, characterized by: The heat exchanger is installed at the outlet of the air preheater (3), and comprises a heat exchanger shell (6), a heat exchange module (7) and an adiabatic section partition plate (8). The heat exchange module (7) is installed in the heat exchanger shell (6), and comprises vacuum heat pipes and fins. The vacuum heat pipes comprise an evaporation section, an adiabatic section and a condensation section. The heat exchange module (7) comprises a flue gas side and an air side, and the adiabatic section partition plate (8) is arranged between the flue gas side and the air side, and divides the tube bundle of the vacuum heat pipes into the evaporation section and the condensation section.

2. The pre-heat exchanger heat pipe as claimed in claim 1, wherein: The heat exchange module (7) is installed at an inclination, and the installation angle ranges from 8 to 10 degrees.

3. The pre-heat exchanger heat pipe as claimed in claim 1, wherein: The cross-sectional area of the heat exchange module (7) is 20-40 m 2 , and the length of the heat exchange tube is 5-10 m.

4. The pre-heat exchanger heat pipe of claim 1, wherein: The vacuum heat pipes are round tubes or oval tubes, and the fins are spiral fins or toothed fins. The fins are arranged in the same direction as the flue gas flow direction. The flue gas side and the air side are both provided with fins. The flue gas side is provided with carbon steel toothed fins, and the air side is provided with aluminum spiral fins.

5. The preheat heat pipe exchanger of claim 3, wherein: The vacuum heat pipes are steel pipes manufactured by a finish rolling process, and are subjected to oil removal pickling and alkaline washing. The working medium in the vacuum heat pipes is desalted water, and corrosion inhibitors and hydrogen absorbers are added.

6. The preheat heat pipe exchanger of claim 5, wherein: A vacuum valve is installed at the top of the vacuum heat pipes.

7. The preheat heat pipe exchanger of claim 3, wherein: The heat exchanger is provided with one or more heat exchange modules (7).

8. The pre-heat exchanger heat pipe of claim 1, wherein: A connecting flue is arranged between the heat exchanger and the air preheater (3). The air side flue is provided with a cold primary air and secondary air inlet (11), a cold primary air and secondary air inlet reducer (9), a hot primary air and secondary air outlet reducer (5) and a hot primary air and secondary air outlet (1). The flue gas side flue is provided with a flue gas inlet (2), a flue gas inlet reducer (4), a flue gas outlet reducer (10) and a flue gas outlet (12). The heat exchanger is installed between the hot primary air and secondary air outlet reducer (5) and the cold primary air and secondary air inlet reducer (9), and between the flue gas inlet reducer (4) and the flue gas outlet reducer (10).

9. The preheat heat pipe exchanger of claim 8, wherein: Temperature sensors are arranged at the positions of the flue gas inlet reducer (4), the hot primary air and secondary air outlet reducer (5), the cold primary air and secondary air inlet reducer (9) and the flue gas outlet reducer (10).

10. The preheat heat pipe exchanger of claim 9, wherein: The flue gas inlet reducer (4), the hot primary air and secondary air outlet reducer (5), the heat exchanger shell (6), the cold primary air and secondary air inlet reducer (9) and the flue gas outlet reducer (10) are all wrapped with heat insulation materials and heat insulation outer plates.

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