Heat Pipe Economizer System, Heat Pipe Heat Exchanger and Heat Pipe Manufacturing Vacuum, Regeneration and Repair Processes

Abstract

The present invention discloses a heat pipe economizer system, a heat pipe heat exchanger, and a vacuum process, a regeneration process, and a repair process for manufacturing heat pipes thereof. The exhaust port of the heat pipe body of the heat pipe heat exchanger is located above the cooling water chamber; a plurality of exhaust heads are respectively arranged at the exhaust ports of the plurality of heat pipe bodies, and each exhaust head has a sealing body that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body. On this basis, through scheme optimization, the present solution effectively utilizes the flue gas waste heat of the actual project system for heat pipe manufacturing, which can shorten the production cycle, reduce the production and manufacturing costs, and the system operation costs.

Description

Technical Field

[0001] The present invention relates to the technical field of heat recovery utilization of the hot tail gas of a boiler unit, and particularly relates to a heat pipe economizer system, a heat pipe heat exchanger, and a vacuum manufacturing process, a regeneration process, and a repair process for heat pipes thereof. Background Art

[0002] As a good heat exchange element, heat pipes are widely used in industries, electronics, and other fields. The traditional process for manufacturing heat pipes by boiling exhaust method is as follows: the heat pipe shell is pickled and passivated in the production workshop, then filled with working fluid, and temporarily sealed with a head; then, the temporarily sealed heat pipe is vertically placed into a pit equipped with a heating furnace in the production workshop, and the heat pipe is heated by the heating furnace until the working fluid pre-filled inside the heat pipe absorbs heat and evaporates, driving the non-condensable gas in the pipe to be discharged into the atmosphere through the top gas pipe; after the non-condensable gas is exhausted, the exhaust port of the heat pipe is welded and permanently sealed, and a certain vacuum degree is formed inside the pipe after cooling.

[0003] Limited by the process characteristics with high requirements for heating equipment and site, the traditional boiling exhaust method has defects of long production cycle and high production cost. In addition, when a heat exchanger is composed of single independent heat pipes after production, if the heat exchange effect is reduced due to the generation of non-condensable gas during industrial operation, the whole heat exchanger needs to be replaced and cannot be reused.

[0004] In view of this, it is urgent to optimize the design of the heat pipe manufacturing process to overcome the above defects. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a heat pipe economizer system, a heat pipe heat exchanger, and a vacuum manufacturing process, a regeneration process, and a repair process for heat pipes thereof. By optimizing the solution, the production cycle can be shortened, and the production manufacturing cost and the system operation cost can be reduced.

[0006] The heat pipe heat exchanger provided by the present invention includes a shell, a plurality of correspondingly arranged heat pipe bodies, and exhaust heads; wherein, the inner cavity of the shell is divided into an upper and a lower part to form a cooling water chamber and a flue gas chamber, and the flue gas chamber has a flue gas inlet and a flue gas outlet for communicating with a flue; a plurality of heat pipe bodies are respectively inserted into the shell, and each heat pipe body is configured such that its evaporation section is located in the flue gas chamber, its condensation section is located in the cooling water chamber, and its exhaust port is located above the cooling water chamber; a plurality of exhaust heads are respectively arranged at the exhaust ports of the plurality of heat pipe bodies, and each exhaust head has a sealing body that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body.

[0007] Preferably, the exhaust head includes a head portion and a top cover; wherein, the head portion has a central through hole, one end of the through hole is communicated with the exhaust port of the heat pipe body, and the other end has a sealing portion adapted to the sealing body; the top cover is threadedly connected to the head portion to form an acting force for constructing a sealing pair between the sealing body and the sealing portion along the axial direction; an inner cavity for accommodating the sealing body is formed between the top cover and the head portion, and a through hole communicating with the inner cavity is opened on the body of the top cover.

[0008] Preferably, the head portion is integrally formed with the pipe end of the corresponding heat pipe body.

[0009] Preferably, the head portion is fixedly sealed and welded to the pipe end of the corresponding heat pipe body.

[0010] The present invention also provides a heat pipe economizer system, including a boiler, a heat pipe low-temperature economizer arranged on the boiler outlet flue, and a cooling water circuit for establishing a cooling water circulation with the heat pipe low-temperature economizer; the heat pipe low-temperature economizer adopts the heat pipe heat exchanger as described above, and the flue gas waste heat in the boiler outlet flue can be used as a heat source for establishing the vacuum degree of the heat pipe body of the heat pipe heat exchanger.

[0011] Preferably, it further includes an air preheater communicated with the outlet of the boiler, and the heat pipe low-temperature economizer is arranged on the downstream side of the air preheater.

[0012] Preferably, it further includes a dust collector, and the dust collector is arranged between the air preheater and the heat pipe low-temperature economizer, or on the downstream side of the heat pipe low-temperature economizer.

[0013] The present invention also provides a heat pipe vacuum production process based on the heat pipe economizer system as described above, including the following steps:

[0014] Pre-assembly: Pre-assemble the heat pipe low-temperature economizer on the boiler outlet flue of the heat pipe economizer system;

[0015] Filling medium: Inject the working medium into the heat pipe body;

[0016] Pressurization and exhaust: Seal the exhaust head and heat the heat pipe body with flue gas to perform in-pipe pressurization; when the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head to perform exhaust;

[0017] Sealing: After the air in the heat pipe body is exhausted, seal the exhaust head to seal the exhaust port of the heat pipe body.

[0018] Preferably, the pressurization and exhaust step includes at least three pressurization and exhaust cycles:

[0019] The first pressurized exhaust cycle, taking the exhaust gas of the heat pipe body mainly being steam as the judgment condition, executes the second pressurized exhaust cycle;

[0020] The second pressurized exhaust cycle, when the temperature of the heat pipe body drops to the first temperature threshold during the exhaust gas process, executes the third pressurized exhaust cycle;

[0021] The third pressurized exhaust cycle, when the temperature of the heat pipe body drops to the second temperature threshold during the exhaust gas process, executes the sealing step;

[0022] Wherein, both the first temperature threshold and the second temperature threshold are higher than the boiling point temperature of the working medium, and the second temperature threshold is higher than the first temperature threshold.

[0023] Preferably, before the filling medium step, it further includes discharging oil and gas: opening the exhaust head and heating the heat pipe body with flue gas until the temperature of the heat pipe body reaches the oil and gas discharge temperature.

[0024] Preferably, the third heating temperature of the heat pipe body in the third pressurized exhaust cycle is higher than the first heating temperature of the heat pipe body in the first pressurized exhaust cycle and the second heating temperature of the heat pipe body in the second pressurized exhaust cycle.

[0025] The present invention also provides a heat pipe regeneration process based on the heat pipe economizer system as described above. The vacuum degree of the heat pipe body of the heat pipe economizer system is established by the heat pipe manufacturing vacuum process as described above; the heat pipe regeneration process includes the following steps:

[0026] Suspend the cooling water circulation: Drain the cooling water in the cooling water chamber of the heat pipe heat exchanger;

[0027] Pressurized exhaust: Heat the heat pipe body with flue gas to perform in-tube pressurization; after the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head and perform exhaust;

[0028] Sealing: After the air in the heat pipe body is exhausted, close the exhaust head and seal the exhaust port of the heat pipe body.

[0029] The present invention also provides a heat pipe repair process based on the heat pipe economizer system as described above. The vacuum degree of the heat pipe body of the heat pipe economizer system is established by the heat pipe manufacturing vacuum process as described above; when the exhaust head is damaged, the following steps are adopted:

[0030] Replace the damaged exhaust head;

[0031] Suspend the cooling water circulation: Drain the cooling water in the cooling water chamber of the heat pipe heat exchanger;

[0032] Supplementary working medium: Open the exhaust head, evaporate and drain all the original working medium in the heat pipe body, and then refill the working medium into the heat pipe body.

[0033] Pressurized exhaust: Seal the exhaust head and heat the heat pipe body with flue gas to increase the pressure inside the pipe; when the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head to exhaust.

[0034] Sealing: After the air in the heat pipe body is exhausted, seal the exhaust head to seal the exhaust port of the heat pipe body.

[0035] Compared with the prior art, the present invention creatively proposes a solution for manufacturing a vacuum heat pipe by utilizing the waste heat of flue gas. Specifically, for a heat pipe device applied to a flue gas waste heat utilization system, a heat pipe heat exchanger is innovatively proposed. The exhaust port of its heat pipe body is provided with an exhaust head that can be switched between a closed working state and an exhaust working state, and each exhaust head has a sealing body that can be switched between a closed working position and an exhaust working position to establish the vacuum degree of the corresponding heat pipe body. With such a setting, the exhaust head of the heat pipe in the heat pipe heat exchanger can be switched according to needs, so that it can be in a non-vacuum state of the heat pipe when assembled in the system flue gas channel. That is to say, the exhaust port is not sealed during pre-assembly, and the inside of the heat pipe body is at normal pressure. On this basis, a vacuum heat pipe can be manufactured by utilizing the waste heat of flue gas. Compared with the traditional boiling exhaust method, this solution has the following beneficial technical effects:

[0036] First of all, this solution effectively utilizes the waste heat of the flue gas in its actual project system to manufacture the heat pipe. There is no need to build the vacuum degree of the heat pipe in the heat pipe manufacturing workshop. After pre-assembly, the flue gas passage is connected, and operations such as heating, pressurizing, and exhausting can be performed based on the boiling exhaust mechanism. Compared with other vacuum manufacturing methods by thermal exhaust, this solution completes the two processes of manufacturing the main structure of the heat pipe heat exchanger and building the vacuum of the heat pipe in different stages; among them, the manufacturing of the heat exchanger main body is completed in the production workshop, and after the manufactured heat pipe heat exchanger is constructed at the project site, the vacuum of the heat pipe is then manufactured. On the one hand, it saves the operator from operating with a heating furnace, and on the other hand, it can avoid the transfer and transportation between different production links during the manufacturing of the heat exchanger main body and the process of making the vacuum, greatly shortening the production cycle of the heat pipe heat exchanger.

[0037] Secondly, this solution uses the waste heat of the flue gas in the project system to heat, exhaust, and vacuum the heat pipe. Compared with manufacturing the heat pipe by the heating furnace heating method in the production workshop, it saves a large amount of energy consumption; at the same time, using the system flue gas for vacuum manufacturing does not require configuring a heating furnace and related facilities in the manufacturing workshop, with less production investment and effectively reducing the manufacturing cost, providing good technical support for improving the product competitiveness.

[0038] Again, the exhaust header of this solution is in a structural form with a switchable conduction state, such as but not limited to a detachable type, which further provides a technical basis for the heat pipe regeneration by reusing the flue gas waste heat at the project site. When the heat transfer performance of the heat pipe decreases, on-line heat pipe regeneration can be realized. Compared with the overall replacement or the heat pipe regeneration by returning it to the factory, this solution has the characteristics of low implementation cost, and the overall service life of the equipment can be effectively extended, thus minimizing the project operation cost to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of the overall structure of the heat pipe low-temperature economizer described in Embodiment 1;

[0040] Figure 2 is a schematic diagram of the structure of the header described in the specific implementation manner;

[0041] Figure 3 is a schematic diagram of the principle of the heat pipe economizer system described in Embodiment 2;

[0042] Figure 4 is a schematic diagram of the principle of the heat pipe economizer system described in Embodiment 3;

[0043] Figure 5 is a flowchart of the vacuum process for manufacturing the heat pipe described in Embodiment 4;

[0044] Figure 6 is a flowchart of the heat pipe regeneration process described in Embodiment 5;

[0045] Figure 7 is a flowchart of the heat pipe repair process described in Embodiment 6.

[0046] In the figure:

[0047] housing 1, flue gas inlet 11, flue gas outlet 12, heat pipe body 2, fins 21, exhaust header 3, seal 31, header part 32, through hole 321, seal part 322, top cover 33, through hole 331;

[0048] heat pipe low-temperature economizer 10, boiler 20, air preheater 30, chimney 40, desulfurization tower 50, dust collector 60. SPECIFIC IMPLEMENTATION MANNER

[0049] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] Embodiment 1:

[0051] Without loss of generality, this embodiment takes Figure 1The heat pipe low-temperature economizer shown in the figure is taken as the description subject, and the structural optimization scheme for the heat pipe heat exchanger is described in detail. It should be understood that as a typical heat pipe heat exchanger, the self-functional structure of the heat pipe low-temperature economizer does not constitute a substantial limitation to the heat exchanger claimed in this application.

[0052] Please refer to Figure 1 , which shows the overall structural schematic diagram of the heat pipe low-temperature economizer.

[0053] In the inner cavity of the shell 1 of the heat pipe low-temperature economizer 10, it is divided into an upper and a lower part to form a cooling water chamber A and a flue gas chamber B. The flue gas chamber B has a flue gas inlet 11 and a flue gas outlet 12 for communicating with the flue. As shown in the figure, a physical space is sealed and isolated between the two by a middle partition plate, so that the flue gas on the flue gas side and the cooling water on the cooling water side are independent of each other without leakage.

[0054] Among them, a plurality of heat pipe bodies 2 are respectively inserted into the shell 1. Each heat pipe body 2 is configured such that its evaporation section (with heat exchange fins 21 provided on the outer surface) is located in the flue gas chamber B, and its condensation section is located in the cooling water chamber A. Of course, the cooling water chamber A can be configured with a cooling water inlet and a cooling water outlet for communicating with the cooling water path to establish a cooling water circulation that makes full use of the waste heat of the flue gas.

[0055] During the working process, the working medium absorbs the heat of the flowing flue gas in the flue gas chamber B in the evaporation section of the heat pipe, changes from liquid to steam, and generates latent heat of vaporization; under the action of the pressure difference in each heat pipe body 2, the steam moves up to the condensation section. The working medium steam meets the cold wall surface and the flowing cooling water in the cooling water chamber A, condenses into liquid working medium, and at the same time releases the latent heat of vaporization, and transfers it to the external cooling water through the pipe wall. The condensed working medium flows back to the evaporation section under the action of gravity and evaporates again. In this way, the heat transfer and exchange between the heat of the flue gas and the two media of the cooling water path are realized.

[0056] In this solution, the exhaust port at the end of the heat pipe body 2 is located above the cooling water chamber A, and an exhaust head 3 is respectively configured corresponding to the exhaust port of each heat pipe body 2 for switching the conduction state of the end of the heat pipe body 2. Specifically, each exhaust head 3 has a sealing body 31 that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body 2.

[0057] In this way, the exhaust head 3 of the heat pipe can be switched according to needs, so that the heat pipe is in a non-vacuum state when it is assembled in the system flue gas channel. That is to say, when the heat pipe low-temperature economizer is pre-assembled in the project system, the exhaust port of the heat pipe body 2 is not closed, and the inside of the heat pipe body is in an atmospheric pressure state. On this basis, the heat pipe vacuum degree can be established by using the waste heat of the system flue gas, for example, but not limited to, the process stages of making vacuum heat pipes and regenerative heat pipes, etc.

[0058] In this solution, the heat pipe body 2 is arranged vertically or obliquely at a certain angle in the heat exchanger, and the top of the condensation section of the heat pipe body 2 extends out of the shell roof of the cooling water chamber A. Preferably, the heat pipe body 2 can be sealed with the water-side shell roof; that is, except for the cooling water inlet and outlet (not shown in the figure), the cooling water chamber A forms a closed space.

[0059] It can be understood that the exhaust head 3 that switches between the closed and exhaust working states can adopt different structural forms. For example, but not limited to, it can be realized by using a threaded fastening method. Please refer to Figure 2 This figure shows the main components of an exhaust head 3.

[0060] Figure 2 As shown, the exhaust head 3 includes a sealing body 31, a head part 32, and a top cover 33. The top cover 33 is threadedly connected to the head part 32, and an inner cavity for accommodating the sealing body 31 is formed between the top cover 33 and the head part 32. The working position of the sealing body 31 is switched by rotating the top cover 33.

[0061] Among them, the head part 32 has a central through hole 321. One end of the through hole 321 is communicated with the exhaust port of the heat pipe body 2, and the other end has a sealing part 322 adapted to the sealing body 31; the top cover 33 can form an acting force for the sealing body 31 and the sealing part 322 to form a sealing pair along the axial direction. When the top cover 33 is tightened to push the sealing body 31 to press against the sealing part 322, it is switched to the closed working position of blocking the through hole 321; when the top cover 33 is loosened in the reverse direction, under the action of the pressure gas in the pipe body, the sealing body 31 disengages from the sealing part 322, and the gas discharged from the heat pipe body 2 can be discharged through the through hole 331 opened on the body of the top cover 32.

[0062] Here, the through hole 331 shown in the figure is communicated with the inner cavity for accommodating the sealing body 31 to establish an exhaust path. In fact, the threaded mating structure between the top cover 33 and the head part 32 is not limited to the structure shown in the figure, and the through hole for final discharge can also be opened on the top cover 33 and the head part 32 and communicated in sequence, or only opened on the head part 32 (not shown in the figure). As long as it meets the functional requirements of connecting the inner cavity to establish an exhaust path, it is within the scope of protection claimed in this application.

[0063] In addition, the head part 32 can be integrally formed with the pipe end of the corresponding heat pipe body 2 (not shown in the figure), or can be welded and fixed to the pipe end of the corresponding heat pipe body 2 as shown in the figure. That is, after the head part 32 is independently processed, it is then welded to the exhaust port of the pipe end of the heat pipe body 2. Comparatively speaking, the design shown independent of the heat pipe body 2 in the figure has better processing technology.

[0064] Embodiment 2:

[0065] Please refer to Figure 3, which is the schematic diagram of the heat pipe economizer system described in this solution.

[0066] The heat pipe economizer system includes a boiler 20 and the heat pipe low-temperature economizer 10 described in Embodiment 1. As shown in the figure, the heat pipe low-temperature economizer 10 is arranged on the outlet flue of the boiler 20; specifically, the flue gas inlet 11 and the flue gas outlet 12 of the heat pipe low-temperature economizer 10 are respectively connected to the pipelines on the outlet flue, and the waste heat of the flue gas in the boiler outlet flue can be used as the heat source for establishing the vacuum degree of the heat pipe body of the heat pipe low-temperature economizer 10 (heat pipe heat exchanger). To simplify the illustration, Figure 3 only the flue gas flow path is shown, and the cooling water path that establishes a cooling water circulation with the heat pipe low-temperature economizer 10 in this system is not shown in the figure.

[0067] In this solution, the heat pipe low-temperature economizer 10 is arranged on the downstream side of the air preheater 30 to utilize the waste heat of the flue gas with a continuous and stable temperature discharged from the air preheater 30. It should be understood that the waste heat of the flue gas above 100 °C at the tail of the boiler unit can be used as a stable and continuous heat source for the manufacturing process of making a vacuum for the heat pipes of the pre-installed heat pipe low-temperature economizer 10 by the heat discharge method.

[0068] In addition, a desulfurization tower 50 is configured at the upstream end of the chimney 40 to perform desulfurization treatment before the flue gas is discharged into the atmosphere to meet relevant environmental protection regulations. In addition, in order to further meet the flue gas emission requirements, a dust collector 60 can also be configured on the upstream side of the desulfurization tower 50.

[0069] It can be understood that for flue gas emission projects without an air preheater 30, the heat pipe low-temperature economizer 10 can be directly connected to the flue gas outlet of the boiler 20. In fact, the specific layout method of the heat pipe low-temperature economizer 10 on the flue can be flexibly adjusted according to actual needs.

[0070] Embodiment 3:

[0071] The heat pipe economizer system described in this solution has the same main functional components as those in Embodiment 2, the difference being that: the heat pipe low-temperature economizer 10 is arranged on the flue between the dust collector 60 and the desulfurization tower 50. Please refer to Figure 4 , which shows the schematic diagram of the heat pipe economizer system described in this solution.

[0072] To clearly show the differences and connections between this solution and Embodiment 2, the same functional components are indicated by the same marks in the figure.

[0073] It should be noted that the air preheater 30, desulfurization tower 50 and dust collector 60 of the heat pipe economizer systems described in Embodiment 2 and Embodiment 3 are not the core inventive points of this application and can be realized by those skilled in the art based on the prior art, so they will not be elaborated herein.

[0074] Embodiment 4:

[0075] Based on the heat pipe economizer system described in Embodiment 3 or Embodiment 4, this solution proposes a vacuum process for manufacturing heat pipes on-site at the project site. Please refer to Figure 5 , which is the flow chart of the vacuum process for manufacturing heat pipes described in this solution.

[0076] This vacuum process for manufacturing heat pipes includes the following steps:

[0077] S51. Pre-assembly: Pre-assemble the heat pipe low-temperature economizer 10 on the Figure 3 or Figure 4 the boiler outlet flue of the heat pipe economizer system shown.

[0078] During pre-assembly, the exhaust head 3 is not assembled or not switched to the closed working position. The heat pipe body 2 has not undergone vacuum production and its interior is in an atmospheric pressure state. At the same time, cooling water shall not be passed through the cooling water side of the heat pipe low-temperature economizer 10 to ensure rapid heating inside the heat pipe during the establishment of the vacuum degree.

[0079] S52. Filling the medium: Inject the working medium into the heat pipe body.

[0080] Before injecting the working medium, it is necessary to calibrate the exhaust gas volume of the heat pipe to confirm the final filling volume of the working medium inside the heat pipe. Specifically, a quantitative tooling device can be used to inject a certain amount of working medium into the heat pipe body.

[0081] For the heat pipe body that has not been pickled and passivated, before the step S52 of filling the medium, it also includes:

[0082] S052. Exhausting grease gas: Open the exhaust head and heat the heat pipe body with flue gas, and perform dry burning of the heat pipe during this process; until the wall of the heat pipe body reaches the grease gas emission temperature, the grease gas in the heat pipe gap is squeezed into the inner cavity of the pipe by high temperature and then discharged together with the hot air in the pipe through the exhaust head to complete the grease gas emission.

[0083] The "grease gas emission temperature" here refers to the wall temperature that can meet the gasification and discharge of grease after heating for a certain period of time, that is, before the vacuum exhaust is made, the heat pipe body is subjected to a long-period dry burning until all the grease in the main material of the heat pipe is gasified, and the exhaust head 3 is used to exhaust to the exhaust state to exhaust the grease gas. Of course, this process can be extended according to the degree of exhaustion of the grease gas. After the grease is exhausted, a quantitative working medium is injected into the heat pipe. Thus, it is ensured that the interior of the heat pipe body has good cleanliness before the working medium is injected.

[0084] S53. Pressurizing and exhausting: Seal the exhaust head and heat the heat pipe body with flue gas to increase the pressure inside the pipe; when the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head to exhaust.

[0085] The "exhaust pressure" here refers to the pressure inside the pipe that can meet the requirement of discharging non-condensable gases after heating for a certain period of time. During this process, the closed exhaust head is temporarily sealed. The heat pipe body is heated by the system flue gas, and the working fluid inside the heat pipe body begins to evaporate. In theory, hot flue gas above 100 °C can be used for vacuum production of all heat pipe bodies 2 by the thermal exhaust method. The pressure inside the pipe gradually increases as the working fluid evaporates. For example, but not limited to, the evaporation situation of the working fluid inside the heat pipe body can be judged according to the wall temperature. When the evaporation reaches a certain time, the internal pressure is established, and the exhaust head 3 is opened for exhaust.

[0086] During the exhaust process, it is possible to judge whether the heat pipe has been completely exhausted according to the form of the gas discharged from the exhaust port of the heat pipe. Specifically, it can be judged by the naked eye in combination with the empirical form during the experimental process. Preferably, an infrared temperature gun or an infrared imager can also be used for judgment, with higher accuracy.

[0087] For example, but not limited to, the pressurized exhaust step includes three pressurized exhaust cycles executed in sequence:

[0088] In the first pressurized exhaust cycle, the second pressurized exhaust cycle is executed on the condition that the gas discharged from the heat pipe body is mainly steam. Specifically, when the gas discharged from the heat pipe is initially mainly hot air + steam, continuous exhaust is required at this time. When the gas discharged from the heat pipe is mainly steam, the second pressurized exhaust cycle is entered, and the exhaust head is temporarily sealed again.

[0089] In the second pressurized exhaust cycle, the third pressurized exhaust cycle is executed when the temperature of the heat pipe body drops to the first temperature threshold during the gas discharge process. Specifically, the flue gas continues to heat the flue gas side of the heat pipe for a certain time, and the evaporation degree of the working fluid inside the heat pipe is judged again through the wall temperature of the heat pipe. When the evaporation of the working fluid inside the heat pipe reaches a certain time, the head is opened incompletely for the second time for exhaust; at this time, the amount of hot air during the heat pipe exhaust process is less obvious, and the visible exhaust form to the naked eye is mainly steam, and it can be judged whether the exhaust is complete through the degree of decrease in the wall temperature. When the wall temperature drops to 1 - 2 °C above the boiling point of the working fluid inside the pipe (the first temperature threshold), the third pressurized exhaust cycle is entered, and the exhaust head is temporarily sealed three times.

[0090] In the third pressurized exhaust cycle, the sealing step S54 is executed when the temperature of the heat pipe body drops to the second temperature threshold during the gas discharge process. Specifically, the flue gas is heated again for a certain time. At this time, the air inside the heat pipe has been preliminarily exhausted, and exhaust is carried out after heating with the flue gas; when the wall temperature drops to 3 °C above the boiling point of the working fluid inside the pipe (the second temperature threshold), the sealing of the heat pipe exhaust head can be completed.

[0091] In this scheme, the heating temperature is required to be higher than the boiling point of the working fluid during the exhaust of grease, air and steam, and the exhaust of air and steam requires that the tube wall temperature is still higher than the boiling point of the working fluid after the staged exhaust of air and steam. In order to ensure that the air inside the heat pipe is completely discharged, the heat pipe can be heated to a higher tube wall temperature. That is to say, the third heating temperature of the heat pipe body in the third supercharged exhaust cycle is higher than the first heating temperature of the heat pipe body in the first supercharged exhaust cycle and the second heating temperature of the heat pipe body in the second supercharged exhaust cycle, which can effectively avoid convection inside and outside the tube, that is, the air outside the tube may enter the tube, causing the vacuum inside the tube to drop.

[0092] Wherein, the first temperature threshold and the second temperature threshold are both higher than the boiling point temperature of the working medium, and the working medium in the tube is in a boiling state in the above-mentioned pressurized exhaust cycle and is kept in an external exhaust state. And preferably, the second temperature threshold is higher than the first temperature threshold, and when the exhaust of the heat pipe is completed while ensuring the exhaust time, the wall temperature of the end of the heat pipe is still above the boiling point temperature, thereby ensuring the vacuum degree in the tube.

[0093] S54. Sealing: After the air in the heat pipe body is exhausted, the exhaust head is closed, the exhaust port of the heat pipe body is sealed, and the vacuum degree of the heat pipe is established.

[0094] In essence, the heat pipe low-temperature economizer is formally heated and exhausted to create a vacuum. The basic method of on-site heating and exhaust of the heat pipe is: "holding pressure, exhausting, and sealing".

[0095] "Pressure holding" refers to the process of heating and pressure holding during the process of heating the exhaust gas to create a vacuum in the heat pipe low-temperature economizer, in order to increase the exhaust pressure in the pipe and exhaust as much air as possible from the heat pipe. The length of each pressure holding time is determined by the heat flux density in the flue gas.

[0096] "Exhaust" means that during the process of heating and exhausting the heat pipe low-temperature economizer to create a vacuum, a complete exhaust is required after each pressure holding process to ensure that the air in the pipe is discharged and a vacuum is formed.

[0097] "Sealing" means that after the heat pipe low-temperature economizer completes the last exhaust by heating the exhaust gas and creating a vacuum, the exhaust head needs to be completely sealed at one time to finally complete the production of the vacuum heat pipe. Of course, compared with the temporary sealing of the exhaust process, the standard of sealing the exhaust head at this time can be appropriately improved, so that the heat pipe with good heat exchange effect can maintain stable heat exchange performance.

[0098] Embodiment five:

[0099] Based on the heat pipe coal saving system described in Example 3 or Example 4, this solution proposes a heat pipe regeneration process to be carried out on site. Figure 6, which is a flow chart of the heat pipe regeneration process described in this scheme.

[0100] After the heat pipe low-temperature economizer 10 has been running for a period of time, due to the generation of non-condensable gas in the heat pipe, and as the running time increases, the non-condensable gas will gradually increase. Usually, the amount of non-condensable gas in the pipe will reach a peak after a period of initial use. The presence of non-condensable gas inside the heat pipe will result in the heat pipe being unable to introduce heat from the evaporation section into the area where the non-condensable gas gathers, resulting in a significant decrease in the heat transfer efficiency of the heat pipe. At this time, the heat pipe regeneration process can be performed without stopping the boiler unit. The heat pipe regeneration process includes the following steps:

[0101] S61. Suspending cooling water circulation: draining the cooling water in the cooling water chamber of the heat pipe heat exchanger.

[0102] When the boiler unit is not shut down, the flue gas passes through the flue gas side of the low-temperature economizer normally, the cooling water supply to the cooling water side of the low-temperature economizer is suspended, and the cooling water in the shell of the cooling water side is drained; thereby, the regeneration preparation work is completed.

[0103] S62. Pressurized exhaust: Use flue gas to heat the heat pipe body and increase the pressure inside the pipe; when the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head and exhaust.

[0104] The hot flue gas heats the heat pipe, and the vacuum degree is determined and established according to the pipe wall temperature. The specific process is the same as the pressurized exhaust step S53 in the fourth embodiment, and will not be described again here.

[0105] When the working fluid inside the heat pipe has boiled, it can continue to be heated for a period of time to increase the working fluid temperature inside the heat pipe, thereby increasing the steam pressure, squeezing the non-condensable gas to the exhaust head, and then opening the detachable exhaust head for online exhaust. In general, the non-condensable gas is first discharged through the head, and after the non-condensable gas is exhausted, the working fluid steam in the pipe begins to be discharged. Since the non-condensable gas is colorless when it is discharged, the working fluid steam will quickly cool down and form white water mist when it is discharged from the head. Therefore, when white water mist appears at the head outlet, it means that the non-condensable gas has been exhausted.

[0106] S63. Sealing: After the air in the heat pipe body is exhausted, the exhaust sealing head is closed to seal the exhaust port of the heat pipe body.

[0107] When the non-condensable gas is completely removed, the heat pipe can be sealed. The regenerated heat pipe has a good heat exchange effect. At this point, the equipment can be restored to normal operation with cooling water.

[0108] Specifically, when the regeneration treatment of the heat pipe needs to be started, the heat exchanger performance of the heat pipe heat exchanger can be screened by region first, and the heat exchange modules with a relatively large decrease in the heat transfer performance of the heat pipe low-temperature economizer are confirmed. Then, the heat pipes in this module region are checked one by one using temperature measuring elements, and finally, the heat pipes that need to be regenerated are located and marked. Then, according to the located and marked heat pipes, the above operation steps are followed to exhaust the heat pipes. After the exhaust is completed, the regenerated heat pipes are inspected using temperature measuring elements. If the inspection is qualified, it can be judged that the regeneration of the heat pipes is successful.

[0109] Embodiment Six:

[0110] Based on the heat pipe economizer system described in Embodiment Three or Embodiment Four, in view of the possible damage to the exhaust head during operation, this solution proposes a heat pipe repair process carried out on-site at the project. Please refer to Figure 7 , which is the flow chart of the heat pipe repair process described in this solution.

[0111] After the heat pipe low-temperature economizer 10 has been operating for some time, when the exhaust head is damaged and the corresponding heat pipe body loses vacuum, it will directly affect the overall heat exchange effect. At this time, the heat pipe repair treatment can be carried out without stopping the boiler unit. The heat pipe repair process includes the following steps:

[0112] S71. Replace the damaged exhaust head; replace the intact exhaust head, for example, but not limited to, the head part and the mating top cover, etc.

[0113] S72. Pause the cooling water circulation: Drain the cooling water in the cooling water chamber of the heat pipe heat exchanger.

[0114] Without stopping the boiler unit, the flue gas normally passes through the flue gas side of the low-temperature economizer, the cooling water supply to the cooling water side of the low-temperature economizer is paused, and the cooling water in the cooling water side shell is drained; thus, the repair preparation work is completed.

[0115] S73. Supplement the working medium: Open the exhaust head, evaporate and drain all the original working medium in the heat pipe body, and then re-inject the working medium into the heat pipe body to ensure the cleanliness of the working medium in the pipe. The specific operation can refer to step S52.

[0116] S74. Pressurize and exhaust: Close the exhaust head and use the flue gas to heat the heat pipe body to increase the pressure inside the pipe; when the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head to exhaust.

[0117] The heat pipe is heated by the hot flue gas, and the vacuum is established according to the wall temperature judgment. Specifically, it is the same as the pressurize and exhaust step S53 in Embodiment Four, and will not be elaborated here.

[0118] S75. Sealing: After the air in the heat pipe body is discharged, seal the exhaust head and seal the exhaust port of the heat pipe body. Thus, the heat pipe vacuum degree is re-formed after the repair is completed.

[0119] In summary, for the process of manufacturing a vacuum heat pipe using flue gas waste heat provided by this solution, compared with other vacuum manufacturing methods by heat discharge, in this method, the two processes of manufacturing the heat pipe heat exchanger shell and forming a vacuum in the heat pipe are completed in different stages. The manufacturing of the heat exchanger main body is completed in the production workshop, and after the heat pipe heat exchanger is manufactured, the vacuum production of the heat pipe is carried out after the construction at the project site is completed, avoiding the transfer between different production links in the manufacturing of the heat exchanger main body and the process of making a vacuum, and greatly shortening the production cycle of the heat pipe heat exchanger; this method uses the waste heat of the flue gas at the tail of the coal-fired boiler to heat and exhaust the heat pipe to make a vacuum. Compared with manufacturing the heat pipe by the heating furnace heating method in the production workshop, a large amount of energy consumption is saved; by adopting this method, the heat pipe low-temperature economizer uses the hot flue gas of the boiler unit to make a vacuum, without the need to configure a heating furnace and related facilities in the manufacturing workshop, with less production investment and low cost, which is beneficial to improving the product competitiveness. For the heat pipe low-temperature economizer adopting this method, since the head is a detachable structure with a switchable working state, the hot flue gas of the boiler at the project site can be reused to make a vacuum for the heat pipe by the heat discharge method. Compared with the heat pipe being returned to the factory for regeneration, this method can realize on-line heat pipe regeneration, with low implementation cost and long overall equipment life.

[0120] It should be noted that the core design concept of manufacturing a vacuum for a heat pipe using flue gas waste heat in this embodiment is applicable not only to the field of using the waste heat of boiler flue gas described in this article, but also to the application occasions of other kilns.

[0121] The above is only the preferred embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. Vacuum process for manufacturing heat pipes in a heat pipe economizer system for boilers Characterized in that The heat pipe economizer system for boilers includes a boiler, a heat pipe low-temperature economizer arranged on the flue gas outlet of the boiler, and a cooling water circuit that establishes a cooling water circulation with the heat pipe low-temperature economizer; The heat pipe low-temperature economizer includes a heat pipe heat exchanger, and the heat pipe heat exchanger includes: A housing, the inner cavity of which is divided into an upper and a lower part to form a cooling water chamber and a flue gas chamber. The flue gas chamber has a flue gas inlet and a flue gas outlet for communicating with the flue; A plurality of heat pipe bodies, which are respectively inserted into the housing. Each heat pipe body is configured such that its evaporation section is located in the flue gas chamber, its condensation section is located in the cooling water chamber, and its exhaust port is located above the cooling water chamber; A plurality of exhaust end caps, which are respectively arranged at the exhaust ports of the plurality of heat pipe bodies. Each exhaust end cap has a spherical sealing body that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body; Among them, the exhaust end cap includes: A head part, having a through hole in the middle. One end of the through hole communicates with the exhaust port of the heat pipe body, and the other end has a sealing part adapted to the sealing body; A top cover, which is threadedly connected to the head part to form an axial acting force for the sealing body and the sealing part to form a sealing pair; an inner cavity for accommodating the sealing body is formed between the top cover and the head part, and a through hole communicating with the inner cavity is opened on the body of the top cover; The waste heat of the flue gas in the boiler outlet flue is used as the heat source for establishing the vacuum degree of the heat pipe body of the heat pipe heat exchanger; the vacuum process for manufacturing heat pipes includes the following steps: Pre-assembly: Pre-assemble the heat pipe low-temperature economizer on the boiler outlet flue of the heat pipe economizer system; Filling with medium: Inject the working medium into the heat pipe body; Pressurizing and exhausting: Close the exhaust end cap and heat the heat pipe body with flue gas for in-pipe pressurization; after the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust end cap for exhausting; Sealing: After the air in the heat pipe body is exhausted, close the exhaust end cap to seal the exhaust port of the heat pipe body.

2. The vacuum process for manufacturing heat pipes according to claim 1, Characterized in that The pressurizing and exhausting step includes at least three pressurizing and exhausting cycles: The first pressurizing and exhausting cycle, with the discharged gas from the heat pipe body being mainly steam as the judgment condition, execute the second pressurizing and exhausting cycle; The second pressurizing and exhausting cycle, when the temperature of the heat pipe body drops to the first temperature threshold during the gas discharging process, execute the third pressurizing and exhausting cycle; The third pressurizing and exhausting cycle, when the temperature of the heat pipe body drops to the second temperature threshold during the gas discharging process, execute the sealing step; Among them, both the first temperature threshold and the second temperature threshold are higher than the boiling point temperature of the working medium, and the second temperature threshold is higher than the first temperature threshold.

3. The vacuum process for manufacturing heat pipes according to claim 1 or 2, Characterized in that Before the step of filling with medium, it further includes: Discharging oil and gas: Open the exhaust end cap and heat the heat pipe body with flue gas until the temperature of the heat pipe body reaches the oil and gas discharge temperature.

4. The vacuum process for manufacturing a heat pipe according to claim 2, characterized in that, the third heating temperature of the heat pipe body in the third pressurization and exhaust cycle is higher than the first heating temperature of the heat pipe body in the first pressurization and exhaust cycle and the second heating temperature of the heat pipe body in the second pressurization and exhaust cycle.

5. The heat pipe regeneration process based on a heat pipe economizer system, characterized in that, the heat pipe economizer system includes a boiler and a heat pipe low-temperature economizer arranged on the flue gas outlet duct of the boiler, and a cooling water circuit for establishing a cooling water circulation with the heat pipe low-temperature economizer; the heat pipe low-temperature economizer includes a heat pipe heat exchanger, and the heat pipe heat exchanger includes: a housing, the inner cavity of which is divided into an upper and a lower part to form a cooling water cavity and a flue gas cavity, and the flue gas cavity has a flue gas inlet and a flue gas outlet for communicating with the flue duct; a plurality of heat pipe bodies respectively inserted into the housing, and each heat pipe body is configured such that its evaporation section is located in the flue gas cavity, its condensation section is located in the cooling water cavity, and its exhaust port is located above the cooling water cavity; a plurality of exhaust heads respectively arranged at the exhaust ports of the plurality of heat pipe bodies, and each exhaust head has a spherical sealing body that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body; wherein, the exhaust head includes: a head part having a through hole in the middle, one end of the through hole communicates with the exhaust port of the heat pipe body, and the other end has a sealing part adapted to the sealing body; a top cover threadedly connected to the head part to form an axial acting force for the sealing body and the sealing part to form a sealing pair; an inner cavity for accommodating the sealing body is formed between the top cover and the head part, and a through hole communicating with the inner cavity is opened on the body of the top cover; the waste heat of the flue gas in the boiler outlet flue duct is used as the heat source for establishing the vacuum degree of the heat pipe body of the heat pipe heat exchanger; the heat pipe regeneration process includes the following steps: Suspend the cooling water circulation: Drain the cooling water in the cooling water cavity of the heat pipe heat exchanger; Pressurize and exhaust: Heat the heat pipe body with flue gas to increase the pressure inside the pipe; after the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head to exhaust; Seal: After the air inside the heat pipe body is exhausted, close the exhaust head to seal the exhaust port of the heat pipe body.

6. The heat pipe repair process based on a heat pipe economizer system, characterized in that, the heat pipe economizer system includes a boiler and a heat pipe low-temperature economizer arranged on the flue gas outlet duct of the boiler, and a cooling water circuit for establishing a cooling water circulation with the heat pipe low-temperature economizer; the heat pipe low-temperature economizer includes a heat pipe heat exchanger, and the heat pipe heat exchanger includes: a housing, the inner cavity of which is divided into an upper and a lower part to form a cooling water cavity and a flue gas cavity, and the flue gas cavity has a flue gas inlet and a flue gas outlet for communicating with the flue duct; a plurality of heat pipe bodies respectively inserted into the housing, and each heat pipe body is configured such that its evaporation section is located in the flue gas cavity, its condensation section is located in the cooling water cavity, and its exhaust port is located above the cooling water cavity; Multiple exhaust heads are respectively arranged at the exhaust ports of the multiple heat pipe bodies. Each exhaust head has a spherical sealing body that can be switched between a closed working position and an exhaust working position for establishing the vacuum degree of the corresponding heat pipe body. Among them, the exhaust head includes: A head part having a central through hole. One end of the through hole is communicated with the exhaust port of the heat pipe body, and the other end has a sealing part adapted to the sealing body. A top cover threadedly connected to the head part to form an axial acting force for the sealing body and the sealing part to form a sealing pair. An inner cavity for accommodating the sealing body is formed between the top cover and the head part, and a through hole communicating with the inner cavity is opened on the body of the top cover. The waste heat of the flue gas in the boiler outlet flue is used as the heat source for establishing the vacuum degree of the heat pipe body of the heat pipe heat exchanger. When the exhaust head is damaged, the following steps are adopted: Replace the damaged exhaust head. Suspend the cooling water circulation: Drain the cooling water in the cooling water cavity of the heat pipe heat exchanger. Supplement the working medium: Open the exhaust head, evaporate and exhaust all the original working medium in the heat pipe body, and then re-inject the working medium into the heat pipe body. Pressurize and exhaust: Close the exhaust head and heat the heat pipe body with flue gas to increase the pressure inside the pipe. After the internal pressure of the heat pipe body reaches the exhaust pressure, open the exhaust head for exhaust. Seal: After the air in the heat pipe body is exhausted, close the exhaust head to seal the exhaust port of the heat pipe body.

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