On-line vacuumizing method and on-line vacuumizing device for heat pipe air pre-heater

Abstract

According to the online vacuumizing method and device for the heat pipe air pre-heater, the online vacuumizing method for the heat pipe air pre-heater is improved, on the premise that a cold source is not cut off, air exhaust operation is conducted on the heat pipe air pre-heater, and the phenomenon that when air exhaust operation is conducted on the heat pipe air pre-heater, the heat pipe air pre-heater is subjected to vacuum pumping operation is avoided. And normal operation of upstream and downstream equipment of the heat pipe air pre-heater is influenced. The heat pipe air pre-heater is applied to a boiler system, and the on-line vacuumizing method of the heat pipe air pre-heater comprises the steps that firstly, on the condition that the normal operation condition of the boiler system is kept, on-line air exhaust operation is conducted on a to-be-vacuumized pipe; and step SC, checking whether the vacuum degree of the to-be-vacuumized pipe is qualified or not, and if so, packaging the to-be-vacuumized pipe.

Description

Technical Field

[0001] The invention relates to the technical field of heat pipe air preheaters, and in particular to an online vacuuming method and an online vacuuming device for a heat pipe air preheater. Background Art

[0002] As an efficient heat exchange element, heat pipes have been widely used in many fields such as industrial cooling systems and electronic equipment heat dissipation due to their excellent heat transfer performance. The working principle of heat pipes is based on the phase change process of the working fluid inside them. The working fluid absorbs heat and evaporates in the evaporation section, and releases heat and condenses in the condensation section, thereby achieving efficient heat transfer. However, during long-term use, non-condensable gases will gradually be generated inside the heat pipe. Since these non-condensable gases do not participate in the phase change heat transfer process of the heat pipe, they will gradually gather in the upper part of the heat pipe to form a "gas column".

[0003] The existence of the "gas column" has a significant adverse effect on the heat transfer performance of the heat pipe. Since the heat transfer coefficient of the "gas column" is extremely low, it basically does not participate in the heat transfer process of the heat pipe, resulting in a decrease in the effective heat exchange area of ​​the upper part of the heat pipe and a poorer heat transfer effect. As the operation time of the heat pipe increases, the amount of non-condensable gas in the pipe gradually increases, and the length of the "gas column" also increases, further exacerbating the decline in the heat transfer effect of the heat pipe.

[0004] For traditional heat pipe heat exchangers, when non-condensable gases accumulate to a certain extent, the cold source of the heat exchanger can be cut off, and the heat exchange medium in the heat pipe can be heated by the on-site heat source for a period of time, so that the medium boils and produces steam. Subsequently, the head of the heat pipe is opened at an appropriate time, and the non-condensable gas is taken out of the heat pipe by the flushing effect of steam, thereby achieving the removal of the non-condensable gas, that is, vacuuming the heat pipe. However, the cold source of the heat pipe air preheater is air, and its air channel downstream is usually connected to combustion equipment such as boilers. Fluctuations in air flow will have a direct impact on the combustion stability of downstream equipment, and may even lead to serious consequences such as unstable combustion or flameout. Summary of the invention

[0005] The purpose of the present invention is to provide an online vacuum pumping method and an online vacuum pumping device for a heat pipe air preheater. By improving the online vacuum pumping method for a heat pipe air preheater, the heat pipe air preheater can be vacuumed without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater is affected when the heat pipe air preheater is vacuumed.

[0006] To achieve the above-mentioned object, the present invention provides a method for online vacuuming of a heat pipe air preheater, wherein the heat pipe air preheater is applied to a boiler system, and the method for online vacuuming of the heat pipe air preheater comprises: step SA, performing online vacuuming operation on the vacuum tube to be vacuumed while maintaining the normal operating condition of the boiler system; step SC, checking whether the vacuum degree of the vacuum tube to be vacuumed is qualified, and if the result is yes, performing packaging operation on the vacuum tube to be vacuumed.

[0007] By adopting the technical solution of the present application, the vacuum tube to be evacuated is evacuated, thereby forming a negative pressure in the vacuum tube to be evacuated. In this way, under the heating effect of the flue gas, the heat exchange medium in the vacuum tube to be evacuated can boil and vaporize, so that in the process of evacuation, the non-condensable gas in the heat pipe is evacuated together, thereby completing the evacuation operation of the heat pipe. In this process, there is no need to turn off the cold source, and the heat pipe can be boiled at a lower temperature by adjusting the pressure in the heat pipe, thereby completing the online evacuation operation of the heat pipe, and realizing the evacuation operation of the heat pipe air preheater without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater is affected when the heat pipe air preheater is evacuated.

[0008] Optionally, in the step SA, the online air extraction operation further comprises:

[0009] Step SA1: perform a first-stage evacuation operation on the vacuum tube to be evacuated according to the first-stage operation parameters, wherein the first-stage operation parameters include a first-stage evacuation rate S 1 ;

[0010] Step SA2: judging whether the vacuum tube to be evacuated has completed the first-stage exhaust operation according to the first judgment condition; after the vacuum tube to be evacuated satisfies the first judgment condition, performing the second-stage exhaust operation on the vacuum tube to be evacuated according to the second-stage operation parameters, wherein the second-stage operation parameters include the second-stage exhaust rate S 2 ; Wherein, the first stage of the pumping rate S 1 Greater than the second stage pumping rate S 2 ;

[0011] Step SA3: judging whether the vacuum tube to be evacuated has completed the two-stage exhaust operation according to the second judgment condition; after the vacuum tube to be evacuated satisfies the second judgment condition, performing step SC.

[0012] By adopting the one-stage vacuum operation and the two-stage vacuum operation, the occurrence of boiling of the heat pipe during the vacuum operation of the heat pipe can be avoided, thereby improving the vacuum stability and controllability of the heat pipe.

[0013] Optionally, before step SA1, step SA1e is also included;

[0014] Step SA1 e: The number of the vacuum tubes to be evacuated is K, and the ambient flue gas temperature corresponding to each of the K vacuum tubes to be evacuated is obtained as the actual ambient temperature T k , {T k}={T 1 , T 2 ……T k}, according to the actual ambient temperature T k Calculate the pumping rate S of the first stage 1 and the second stage pumping rate S 2 ;in,

[0015] Among them, T in is the flue gas inlet temperature of the heat pipe air preheater, T out is the flue gas outlet temperature of the heat pipe air preheater, i 1 is the number of rows of the single vacuum tube to be evacuated in the direction of smoke flow, and n is the number of effective heat pipes.

[0016] Optionally, before step SA, the method further includes:

[0017] Step SE1 a. Select a vacuum tube at any position as a test tube, and obtain the flue gas environment temperature corresponding to the test tube as the reference environment temperature T std , calculate the first-stage exhaust rate S according to the reference ambient temperature 1 and the second stage pumping rate S 2 ;in,

[0018]

[0019] T instd is the flue gas inlet temperature of the heat pipe air preheater, T outstd is the flue gas outlet temperature of the heat pipe air preheater, i std is the number of rows of the experimental tubes in the direction of smoke flow, and n is the number of effective heat pipes.

[0020] Optionally, according to the reference ambient temperature T std and the actual ambient temperature T k Calculate the pumping rate S of the first stage 1 :

[0021]

[0022] Among them, T max For {T k}, A 1 is the pumping rate S of the first stage 1 Flue gas temperature correction factor, T stdis the reference ambient temperature, S 1std It is the reference pumping rate of the stage obtained before the online pumping operation.

[0023] Optionally, the first judgment condition includes whether the time for the vacuum tube to be evacuated to perform the first stage of evacuation operation has completed the first stage of evacuation time t 1k If the result is yes, it is determined that the vacuum tube to be evacuated has completed the one-stage evacuation operation.

[0024] Optionally, according to the actual ambient temperature T k and the reference ambient temperature T std Calculate the vacuum time t of each of the K vacuum tubes to be evacuated in one stage 1k , {t 1k}={t 11 , t 12 ……t 1k};in,

[0025]

[0026] Among them, B 1 is the pumping time t of the first stage 1k Flue gas temperature correction factor, t 1std The reference pumping time for the said stage.

[0027] Optionally, according to the reference extraction time t of the first stage 1std Get the corresponding reference pumping rate S of the stage 1std .

[0028] Optionally, the step SA1 includes:

[0029] Step SA11: according to the first stage of the pumping rate S 1 Performing the one-stage vacuuming operation on K tubes to be vacuumed simultaneously;

[0030] Step SA13: When each of the K vacuum tubes to be evacuated completes the first stage of evacuation operation, calculate the first stage of new evacuation rate S′ 1 ;

[0031] Step SA14: adopt the new exhaust rate S′ of the first stage 1 The remaining vacuum tubes to be evacuated are evacuated, and step SA13 is repeated until the K vacuum tubes to be evacuated have completed the first stage of evacuation operation; wherein,

[0032] The new pumping rate S' of the first stage is calculated according to the following formula 1 :

[0033]

[0034] x1 is the number of heat pipes that have completed one stage of exhaust operation.

[0035] Optionally, according to the reference ambient temperature T std and the actual ambient temperature T k Calculate the two-stage pumping rate S 2 :

[0036]

[0037] Among them, A 2 is the flue gas temperature correction coefficient of the second stage extraction rate, T min For {T k}, T std is the reference ambient temperature, S 2std It is the second-stage reference pumping rate obtained before the online pumping operation.

[0038] Optionally, the actual ambient temperature T k and the reference ambient temperature T std Calculate the second-stage vacuuming time t of each of the K vacuum tubes to be evacuated 2k , {t 2k}={t 21 , t 22 ……t 2k};in,

[0039]

[0040] Among them, B 2 is the second stage pumping time t 2k Flue gas temperature correction factor, t 2std It is the second-stage reference pumping time obtained prior to the online pumping operation.

[0041] Optionally, according to the second stage reference pumping time t 2std Get the corresponding second-stage reference pumping rate S 2std .

[0042] Optionally, the second judgment condition includes judging whether the time for the vacuum tube to be evacuated to perform the second-stage evacuation operation has completed the second-stage evacuation time t 2k If the result is yes, it is determined that the vacuum tube to be evacuated has completed the two-stage evacuation operation.

[0043] Optionally, the step SA2 further includes:

[0044] Step SA21: according to the second stage exhaust rate S 2Performing the two-stage vacuuming operation on K tubes to be vacuumed simultaneously;

[0045] Step SA23: among the K vacuum tubes to be evacuated, each time one of the vacuum tubes to be evacuated completes the second-stage evacuation operation, calculate the second-stage new evacuation rate S′ 2 , the second-stage new pumping rate S′ is calculated according to the following formula 2 :in,

[0046]

[0047] x2 is the number of vacuum tubes to be evacuated that have completed the two-stage evacuation operation

[0048] Step SA24: adopt the second-stage new exhaust rate S′ 2 The remaining vacuum tubes to be evacuated are evacuated, and step SA23 is repeated until the K vacuum tubes to be evacuated have completed the second-stage evacuation operation.

[0049] Optionally, before step SA1, step SA1 s is also included;

[0050] Step SA1: Pour a mass of m into the vacuum tube to be evacuated. 0 The heat transfer medium, where m 0 =m 1 +m 2 , m 1 is the reference pumping rate s of the experimental tube at the stage 1std The first stage is carried out with reference to the pumping time t 1std The mass of the heat exchange medium extracted after the pumping operation, m2 is the reference pumping rate s of the experimental tube in the second stage 2std The second stage is carried out with reference to the pumping time t 2std The mass of the heat exchange medium extracted after the pumping operation.

[0051] Optionally, before step SA, the method further includes:

[0052] Step SE, performing a vacuum test before step SA, step SE comprises:

[0053] Step SE1: Perform a first-stage air extraction experiment on the experimental tube to obtain the reference ambient temperature T std At the moment when the heat exchange medium starts to boil, the reference pumping rate S 1std , the first stage refers to the pumping time t 1std , and the mass m of the heat exchange medium discharged from the experimental tube 1 ;

[0054] Step SE2: Perform a two-stage exhaust experiment on the experimental tube to obtain the two-stage reference exhaust rate S when the heat exchange medium is in a continuous boiling state. 2std , the corresponding two-stage reference pumping time t 2std And the mass m of the heat exchange medium discharged from the experimental tube 2 .

[0055] An online vacuum pumping device for a heat pipe air preheater, the heat pipe air preheater comprising a plurality of pipe rows distributed along a first direction, each of the heat pipe rows being provided with a plurality of heat pipes, and a heat exchange medium being contained in the heat pipes;

[0056] The heat pipe air preheater further comprises a flue gas channel and an air channel, one side of each heat pipe is located in the flue gas channel, and the other side is located in the air channel;

[0057] The first end of the heat pipe extends from a side of the air passage away from the smoke passage;

[0058] It also includes a vacuum pump, a condenser and a liquid collecting device. The inlet of the condenser is connected to the head end of the tube body, the gas outlet of the condenser is connected to the vacuum pump, and the liquid outlet of the condenser is connected to the liquid collecting device.

[0059] By adopting the technical solution of the present application, through mechanical vacuum operation on the heat pipe and combining it with flue gas heating, it is achieved that the heat pipe of the heat pipe air preheater can be vacuumed online, and the heat pipe air preheater can be vacuumed without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater is affected when the heat pipe air preheater is vacuumed.

[0060] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0062] Figure 1 2 is a schematic structural diagram of an online vacuum pumping device for a heat pipe air preheater according to an embodiment of the present invention;

[0063] Figure 2 This is one of the flow charts of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention;

[0064] Figure 3 This is the second flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention;

[0065] Figure 4This is the third flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention;

[0066] Figure 5 This is the fourth flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention;

[0067] Figure 6 This is the fifth flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention.

[0068] Reference numerals:

[0069] 1-heat pipe air preheater; 1.1-heat pipe; 1.2-middle partition; 1.3-flue gas inlet temperature measuring point; 1.4-flue gas outlet temperature measuring point; 1.5-temperature collection component; 2-heat exchange medium injection system; 2.1-heat exchange medium injection control console; 2.2-heat exchange medium storage tank; 2.3-heat exchange medium injection valve; 3-vacuum generation system; 3.1-vacuum control console; 3.2-vacuum pump; 3.3-vacuum valve; 3.4-liquid collecting device; 3.5-heat exchange medium collecting valve; 3.6-condenser; 3.7-flow meter. DETAILED DESCRIPTION

[0070] The present invention provides an online vacuum pumping method for a heat pipe air preheater and a heat pipe air preheater. By improving the online vacuum pumping method for the heat pipe air preheater, the heat pipe air preheater can be vacuumed without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater is affected when the heat pipe air preheater is vacuumed.

[0071] In order to enable those skilled in the art to better understand the solution of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0072] Relational terms such as “first” and “second” and the like are merely used to distinguish one component from another having the same name, but do not necessarily require or imply any such actual relationship or order between these components.

[0073] In traditional technical solutions, heat exhaust is usually used to evacuate heat pipes. Specifically, the heat exchange medium in the pipe is fully heated by partially or completely cutting off the cold source of the heat exchanger. However, this method has a certain impact on the upstream and downstream equipment of the heat exchanger during the heat pipe exhaust operation. In addition, the boiling rate of the heat exchange medium in the heat pipe depends entirely on the flue gas temperature corresponding to the heat pipe, and the evacuation of the heat pipe can only be controlled by adjusting the exhaust time.

[0074] Another method is to close the corresponding heat pipe air preheater vacuum door panel for the partition of the heat pipe air preheater that needs to be evacuated, first fill a sufficient amount of heat medium inside the heat pipe air preheater, and then close the corresponding heat pipe air preheater vacuum door panel for the partition of the heat pipe air preheater that needs to be evacuated, while the first part of the heat pipe air preheater in the corresponding partition where the door panel of the heat pipe air preheater is not closed can still circulate air. At this time, the area corresponding to the closed heat pipe air preheater vacuum door panel has no cold air for cooling, and the heat medium injected inside the heat pipe air preheater continues to be in a boiling state, and finally the exhaust device at the end of the heat pipe air preheater is opened to perform the exhaust operation. When the vacuum process of a heat pipe air preheater partition has been completed, the corresponding partition heat pipe air preheater door panel is opened, and the next partition heat pipe air preheater vacuum door panel of the heat pipe air preheater partition that needs to be evacuated is closed in turn. At this time, the heat pipe that has completed the vacuumization can be quickly put into operation, the exhaust gas temperature in the corresponding partition is reduced, and the boiler efficiency is improved.

[0075] However, this method also has some disadvantages. For example, during the heat exchanger's heat pipe vacuum operation, the air channel of the heat pipe air preheater needs to be partially or completely closed to allow the heat exchange medium in the pipe to continue to boil. The opening and closing of the air channel can easily cause large fluctuations in the air flow through the heat exchanger, resulting in instability in the air flow entering the boiler, affecting the normal operation of the boiler. In addition, each time the method performs a vacuum operation, all heat pipes in the same area must be shut down. For situations where only a small number of heat pipes need to be vacuumed, the amount of operations and the range of operations involved in this solution are too large. In addition, this method uses a heat exhaust method for vacuuming, and the boiling rate of the heat exchange medium in the heat pipe depends entirely on the flue gas temperature corresponding to the heat pipe, and the vacuuming of the heat pipe can only be controlled by adjusting the exhaust time.

[0076] like Figures 1 to 5 As shown, Figure 1 2 is a schematic structural diagram of an online vacuum pumping device for a heat pipe air preheater according to an embodiment of the present invention; Figure 2 This is one of the flow charts of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention; Figure 3 This is the second flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention; Figure 4 This is the third flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention; Figure 5 This is the fourth flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention. Figure 6 This is the fifth flow chart of the method for online vacuuming of a heat pipe air preheater in an embodiment of the present invention.

[0077] In order to solve at least one technical problem in the prior art, the present invention provides an online vacuum pumping device for a heat pipe air preheater 1, a heat pipe air preheater 1 (such as Figure 1The portion shown in the dashed box in the middle) includes a plurality of tube rows distributed along the first direction, each tube row is provided with a plurality of heat pipes 1.1, and the heat pipes 1.1 contain heat exchange medium. Among them, the first direction is the flow direction of the flue gas, which is Figure 1 Specifically, Figure 1 In the example shown in , a middle partition 1.2 is provided in the heat pipe air preheater to separate the flue gas channel and the air channel. One side of each heat pipe 1.1 is located in the flue gas channel, and the other side is located in the air channel. The head end of the heat pipe 1.1 extends from the side of the air channel away from the flue gas channel. The flue gas channel is provided with a flue gas inlet temperature measuring point 1.3 and a flue gas outlet temperature measuring point 1.4, and a temperature collecting component 1.5 is provided at the head end of the pipe body.

[0078] In the example shown in the figure, 4 tube rows are arranged in the direction of smoke flow. This number is only for illustration to show the distribution state of the tube rows in the direction of smoke flow, and is not intended to limit the technical solution of the present application. Those skilled in the art can set the number of tube rows to any value as needed. It is understandable that Figure 1 It is a side view of an online vacuum pumping device. Each tube row includes a plurality of heat pipes 1.1. In the figure, only a single heat pipe 1.1 in the flue gas flow direction is shown.

[0079] In order to realize online vacuuming of the heat pipe 1.1, the online vacuuming device of the heat pipe air preheater 1 also includes a vacuum generating system 3 (such as Figure 1 The vacuum generating system 3 is used to mechanically evacuate the heat pipe 1.1. Specifically, it includes a vacuum pump 3.2, a condenser 3.6 and a liquid collecting device 3.4. The inlet of the condenser 3.6 (this inlet is the inlet of the gas-liquid mixture) is connected to the head end of the pipe body. After the condenser 3.6 separates the gas-liquid mixture, the separated gas is discharged through the gas outlet, which is connected to the vacuum pump 3.2. The liquid separated by the condenser 3.6 is discharged through the liquid outlet, which is connected to the liquid collecting device 3.4.

[0080] The vacuum generating system 3 also includes an exhaust pipe, through which the vacuum pump 3.2 is connected to the head end of the tube body, and the exhaust pipe is also connected to a condenser 3.6.

[0081] Under the action of the vacuum pump 3.2, the gas-liquid mixture entering the condenser 3.6 from the head end of the heat pipe 1.1 through a part of the exhaust pipe is separated under the action of the condenser 3.6, and the separated gas flows out through the gas outlet of the condenser 3.6 and is discharged to the vacuum pump 3.2 through another part of the exhaust pipe, and the liquid is collected in the liquid collecting device 3.4 through the liquid collecting pipe.

[0082] By adopting the technical solution of the present application, the heat pipe 1.1 is mechanically evacuated and combined with flue gas heating, so that the heat pipe 1.1 of the heat pipe air preheater can be evacuated online, and the heat pipe air preheater 1 can be evacuated without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater 1 is affected when the heat pipe air preheater 1 is evacuated.

[0083] As an optional solution, the online vacuum pumping device of the heat pipe air preheater 1 also includes a heat exchange medium injection system 2 ( Figure 1 The heat exchange medium injection system 2 also includes an injection pipeline, which is also connected to the head end of the pipe body. Specifically, the injection pipeline and the exhaust pipeline are connected through the head end of the pipe body. The head can be a head with double connection channels, and the size of each channel can be adapted to the corresponding injection pipeline and exhaust pipeline, and technicians in this field can choose it.

[0084] The heat exchange medium filling system 2 comprises a heat exchange medium filling control console 2.1, a heat exchange medium storage tank 2.2, and a plurality of heat exchange medium filling valves 2.3 so as to simultaneously fill a plurality of heat pipes 1.1.

[0085] It can be understood that the aforementioned vacuum generation system 3 also includes multiple vacuum valves 3.3, heat exchange medium collection valves 3.5, multiple condensers 3.6 with gas-water separation function and flow meters 3.7, so as to be able to adapt to multiple heat pipes 1.1 and perform online vacuuming on multiple heat pipes 1.1. The number of heat exchange medium injection valves 2.3, vacuum valves 3.3 and condensers 3.6 is determined according to the number of connected tubes to be vacuumed.

[0086] In order to solve at least one technical problem in the prior art, another aspect of the present application provides a method for online vacuuming of a heat pipe air preheater 1, such as Figures 2 to 6 As shown, the method is adapted to the aforementioned at least partially online vacuum pumping device, and the method comprises:

[0087] Step SA: while maintaining the normal operation of the boiler system, perform online vacuuming operation on the vacuum tube to be evacuated; in this step, a vacuum pump is used to evacuate the vacuum tube to be evacuated.

[0088] Step SC, check whether the vacuum degree of the vacuum tube to be evacuated is qualified (this inspection method is described in detail in the procedure). If the result is yes, the vacuum tube to be evacuated is packaged.

[0089] By adopting the technical solution of the present application, the vacuum tube to be evacuated is evacuated, thereby forming a negative pressure in the vacuum tube to be evacuated. In this way, the heat exchange medium in the vacuum tube to be evacuated can boil and vaporize under the heating of the flue gas, so that in the process of evacuation, the non-condensable gas in the heat pipe 1.1 is extracted together, thereby completing the evacuation operation of the heat pipe 1.1. In this process, there is no need to turn off the cold source, and the pressure in the heat pipe 1.1 can be adjusted to make the heat pipe 1.1 boil at a lower temperature, thereby completing the online evacuation operation of the heat pipe 1.1, and realizing the evacuation operation of the heat pipe air preheater 1 without cutting off the cold source, thereby avoiding the situation where the normal operation of the upstream and downstream equipment of the heat pipe air preheater 1 is affected when the heat pipe air preheater 1 is evacuated.

[0090] Specifically, in step SA, the online air extraction operation further includes:

[0091] Step SA1: perform a first-stage evacuation operation on the vacuum tube to be evacuated according to the first-stage operation parameters, wherein the first-stage operation parameters include a first-stage evacuation rate S 1 ;

[0092] Step SA2: judging whether the vacuum tube to be evacuated has completed the first stage of the evacuation operation according to the first judgment condition; after the vacuum tube to be evacuated satisfies the first judgment condition, performing the second stage of the evacuation operation on the vacuum tube according to the second stage operation parameters; the second stage operation parameters include the second stage evacuation rate S 2 ; Among them, the first stage of the pumping rate S 1 Greater than the second stage pumping rate S 2 In this way, the vacuuming process is divided into two stages, each stage adopts a different stage vacuuming rate, and the vacuuming rate of the second stage is lower than that of the first stage, thereby preventing the heat pipe from boiling during the vacuuming process.

[0093] Among them, the first stage of pumping rate S 1 The heat pipe 1.1 is evacuated so that the heat exchange medium therein gradually boils from the liquid state. Then the first stage evacuation operation is stopped and the second stage evacuation rate S is adopted. 2 The heat pipe 1.1 is further evacuated. At this time, the heat exchange medium has boiled. The heat exchange medium is evacuated at a lower evacuation rate to keep the heat exchange medium in a state of continuous boiling, so that all the non-condensable gases in the heat pipe 1.1 can be taken out, so that the vacuum degree in the heat pipe 1.1 meets the requirements.

[0094] The first judgment condition and the second judgment condition here may be based on the state of the heat exchange medium, or may be based on the pre-acquired boiling time of the heat exchange medium. The specific first judgment condition and the second judgment condition will be described in detail later.

[0095] Furthermore, in step SA3, it is determined whether the vacuum tube to be evacuated has completed the second stage of the vacuuming operation according to the second determination condition. After the vacuum tube to be evacuated satisfies the second determination condition, step SC is performed.

[0096] By adopting the one-stage vacuum operation and the two-stage vacuum operation, the occurrence of boiling of the heat pipe during the vacuum operation of the heat pipe can be avoided, thereby improving the vacuum stability and controllability of the heat pipe.

[0097] In the aforementioned technical solution, in order to ensure the controllability and accuracy of vacuum extraction, experimental operations are carried out before step SA to evaluate the first-stage reference vacuuming rate, first-stage reference vacuuming time, second-stage reference vacuuming rate, and second-stage reference vacuuming time of the heat exchange medium in the heat pipe at the beginning of boiling and continuous boiling.

[0098] Before the experimental operation, select any position of the vacuum tube as the experimental tube, and perform the vacuum operation on the experimental tube. During the vacuuming process, the flue gas still heats the experimental tube. Therefore, in the process of obtaining the first-stage operation parameters and the second-stage operation parameters, the position of the experimental tube in the flue gas flow direction needs to be considered to obtain the flue gas ambient temperature at that position. The flue gas ambient temperature of the experimental tubes at different tube row positions is different because heat will be exchanged with the effective tubes in the flow direction of the flue gas. The number of effective tubes is different, and the temperature of the flue gas flowing through the experimental tube is also different.

[0099] In order to obtain the ambient temperature of the experimental tube, the online vacuuming method further includes step SE1a, obtaining the flue gas ambient temperature corresponding to the experimental tube as a reference ambient temperature T std , calculate the first-stage pumping rate S according to the reference ambient temperature 1 and the second stage pumping rate S 2 ;in,

[0100]

[0101] T instd is the flue gas inlet temperature of the heat pipe air preheater, T outstd is the flue gas outlet temperature of the heat pipe air preheater, i std is the number of rows of experimental tubes in the direction of smoke flow, and n is the number of effective heat pipes.

[0102] In addition to the method in this application to obtain the reference ambient temperature T std Other methods can also be used for calculation or collection, and technicians in this field can adjust them according to their needs. For example, a temperature collection device is provided on the wall of each vacuum tube to obtain the flue gas environment temperature at the location of the vacuum tube or the experimental tube.

[0103] In this way, the smoke environment temperature of any experimental tube 1.1 in the direction of smoke flow is obtained according to the relationship between the smoke inlet temperature, the smoke outlet temperature and the smoke heat absorbed by the effective heat pipe 1.1, thereby obtaining the heating temperature of the experimental tube 1.1 by the smoke.

[0104] In this step, any heat pipe 1.1 is selected as the experimental pipe 1.1 to perform a first-stage exhaust experiment. After the experimental heat pipe 1.1 completes the first-stage exhaust experiment, the heat pipe 1.1 is subjected to a second-stage exhaust experiment. In this step, when the flue gas flows through the heat exchanger, after heat exchange with the effective heat pipe 1.1, the flue gas will be cooled. The more effective heat pipes 1.1 flow through, the lower the flue gas temperature. Therefore, the flue gas temperatures of the experimental pipes 1.1 at different positions are different. Through this embodiment, the accurate ambient flue gas temperature T of the experimental pipe 1.1 can be obtained. std The effective heat pipe 1.1 refers to the heat pipe that has completed the exhaust operation and can normally exchange heat with the gas in the smoke channel and the air channel. In addition, n=0 refers to the case where the number of effective heat pipes 1.1 is 0.

[0105] T instd is the flue gas inlet temperature measured at the flue gas inlet temperature measuring point 1.3 during the first stage of the exhaust experiment, T outstd It is the flue gas temperature at the heat pipe air preheater outlet measured at the flue gas outlet temperature measuring point 1.4 during the first stage of exhaust experiment.

[0106] In order to further accurately control the vacuum operation, after obtaining the reference ambient temperature T std That is to say, before the online pumping operation, the first stage and second stage pumping experiments are carried out. The specific methods of the two stages of the pumping experiments are described below.

[0107] After step SE1 a, the method further includes step SE1, performing a first-stage exhaust experiment on the experimental tube 1.1 to obtain a first-stage operation parameter;

[0108] Step SE1 also includes:

[0109] Step SE11, obtain the reference ambient temperature T corresponding to the experimental tube 1.1 std Under this condition, the first stage when the heat transfer medium starts to boil is referred to as the pumping rate S 1std , the corresponding stage reference pumping time t 1std And the mass of heat exchange medium discharged from the experimental tube 1.1 is m 1 .

[0110] Thus, the reference extraction rate S at the stage when the heat exchange medium starts to boil can be obtained. 1std , the reference pumping time t at this rate1std , and the mass of the heat exchange medium at this stage is m1.

[0111] The vacuum control console 3.1 starts the vacuum pump 3.2, opens the vacuum valve 3.3 of the experimental tube 1.1, and the air in the experimental tube 1.1 is pumped out, and the pressure in the tube drops. When the pressure in the tube drops to a low enough level, the working medium steam in the tube cannot condense on the air side tube wall, and rushes out of the heat pipe 1.1 at the end of the heat pipe 1.1. The reason for the failure to condense is that the air pressure in the tube is reduced, and the temperature point of the working medium vaporization is correspondingly reduced, so that even on the air cold end side, it will not condense, but remain in a vaporized state.

[0112] When the heat exchange medium vapor is observed to condense into liquid heat exchange medium in the condenser 3.6, the heat exchange medium begins to boil, and the reference pumping rate S at this stage is recorded. 1std , the corresponding stage reference pumping time t 1std .

[0113] As an optional implementation, the first stage reference pumping time t 1std Should satisfy t min ≤t 1std ≤t max , if t min >t 1std , then it means that the reference pumping rate S in the first stage 1std Select too large; in this case, boiling is likely to occur in the heat pipe 1.1. 1std ≥t max , then it means that the reference pumping rate S in the first stage 1std If the value is too small, the heat pipe 1.1 will take too long to evacuate air, and the efficiency will be too low. At this time, the vacuum control console 3.1 issues a command to open the vacuum valve 3.3, and air re-enters the heat pipe 1.1. Repeat the above experiment until the reference evacuation time of the first stage meets t min ≤t 1std ≤t max , record the corresponding S at this time 1std Through this operation mode, the appropriate reference pumping rate S for one stage is obtained without the heat exchange medium boiling. 1std .

[0114] After the first stage of the exhaust experiment of the experimental heat pipe 1.1 is completed, a second stage of the exhaust experiment is carried out to obtain continuous boiling of the heat exchange medium in the experimental tube 1.1 so as to push out the original non-condensable gas in the experimental tube 1.1.

[0115] Specifically, step SE2, performing a two-stage gas extraction experiment on the experimental tube 1.1 to obtain the two-stage operating parameters;

[0116] Step SE2 includes:

[0117] Step SE21: Obtain the second-stage reference pumping rate S under the continuous boiling state of the heat exchange medium 2std , the corresponding second stage reference pumping time t 2std And the heat exchange medium m discharged from the experimental tube 1.1 2 .

[0118] During the experiment, the heat exchange medium collecting valve 3.5 is opened, and the vacuum control console 3.1 adjusts the vacuum pump 3.2's pumping rate to the minimum gear, and observes the steam situation in the condenser 3.6 at this time. If liquid heat exchange medium continues to be produced in the condenser 3.6, it is determined that the heat exchange medium in the tube is continuously boiling at this time, and the remaining non-condensable gas is discharged from the heat pipe 1.1 driven by the heat exchange medium steam.

[0119] As a method to obtain the second-stage reference pumping rate S 2std In this way, the condenser 3.6 can be observed during the evacuation process. If no steam is generated in the condenser 3.6 at this time, it is determined that the evacuation rate of the vacuum pump 3.2 is insufficient. The evacuation rate of the vacuum pump 3.2 can be gradually increased until the liquid heat exchange medium is continuously generated in the condenser 3.6. The evacuation rate of the vacuum pump 3.2 at this time is recorded as S 2std .

[0120] Then, set the vacuum pump 3.2 to a pumping speed of S 2std , the liquid heat exchange medium in the heat pipe 1.1 continues to boil, and when the mixed gas of air and heat exchange medium steam discharged from the pipe passes through the condenser 3.6, the heat exchange medium steam in the discharged gas is condensed into liquid, and the air is pumped into the vacuum pump 3.2. As the exhaust time increases, the proportion of heat exchange medium steam in the discharged gas gradually increases, while the proportion of air gradually decreases, the mass of liquid heat exchange medium generated by heat exchange medium steam gradually increases, and the flow measured by the flow meter 3.7 also gradually increases.

[0121] When the flow rate measured by the flow meter 3.7 stops increasing, it is determined that the non-condensable gas in the test tube 1.1 is pushed out, and the pumping rate S of the vacuum pump 3.2 at this time is recorded. 2std The corresponding vacuum time t 2std , and the mass m of the liquid heat exchange medium collected by the liquid collecting device 3.4 during this process 1 .

[0122] In this way, the two-stage reference pumping rate S of the experimental tube 1.1 under the condition of continuous boiling is obtained. 2std , the corresponding second stage reference pumping time t 2std And the heat exchange medium m discharged from the experimental tube 1.1 2In this step, the heat exchange medium continues to boil and vaporize, thereby bringing out the non-condensable gas in the heat pipe 1.1, thereby realizing the vacuum operation of the experimental tube 1.1.

[0123] In the aforementioned technical solution, step SE2 also includes step SE22, performing a heat pipe 1.1 inspection experiment on the heat pipe 1.1 that has completed the two-stage exhaust experiment to determine whether the vacuum degree of the experimental tube 1.1 meets the standard. If so, retain the two-stage exhaust operation parameters obtained previously. If not, repeat steps SE1 and SE21 until the vacuum degree of the experimental tube 1.1 meets the standard.

[0124] Specifically, after the second stage of the exhaust experiment is completed, the temperature collection unit 1.5 starts to record the temperature of the first end of the tube body of the test tube 1.1. When the temperature of the first end of the tube body of the test tube 1.1 stops decreasing, the top surface temperature T of the test tube 1.1 is recorded. 0 . In the implementation of the present application, the temperature acquisition component can be a thermal imaging camera or other device capable of collecting temperature. The vacuuming process of the heat pipe 1.1 is divided into two stages. In the first stage of the vacuuming process, the vacuum pump 3.2 uses a large output to vacuum until the working medium and heat exchange working medium in the tube boil, and the vacuum pump 3.2 is used to directly pump most of the air in the tube out of the heat pipe 1.1. In the second stage of the vacuuming process, the vacuum pump 3.2 uses a smaller output to keep the working medium and heat exchange working medium in the tube at a smaller degree of boiling, and uses the working medium and heat exchange working medium steam it generates to carry the remaining small part of the air out of the heat pipe 1.1.

[0125] Open the heat exchange medium collection valve 3.5, and then the vacuum control console 3.1 issues a command to set the pumping rate to S 2 , start the vacuum pump 3.2, open the vacuum valve 3.3 corresponding to the experimental tube 1.1, at this time, the vacuum degree in the experimental tube 1.1 further decreases, the boiling degree of the liquid heat exchange medium increases, the heat exchange medium steam generated by boiling cannot be completely condensed in the condensation section, enters the exposed section of the experimental tube 1.1, heats the top of the experimental tube 1.1, and the temperature of the top of the experimental tube 1.1 gradually increases. When the surface temperature of the heat pipe 1.1 stops rising, record and then the temperature T at the head end of the heat pipe 1.1 t , and the time Δt of temperature change, according to T 0 , T t And Δt is obtained

[0126] Heating rate T' of the experimental tube 1.1 std If the heating rate T′ of the experimental tube 1.1 is std If the vacuum degree test condition is met, the experimental tube 1.1 is determined to be a qualified heat pipe 1.1; if not, the vacuum degree of the experimental tube 1.1 is determined to be unqualified.

[0127] The heating rate T' of the experimental tube 1.1 is calculated according to the following formula: std:

[0128]

[0129] The vacuum test condition is T' std -T′ 0 ≥0, if this condition is met, it is determined that the vacuum pumping of the experimental tube 1.1 meets the requirements. 0 It is the heat pipe 1.1 heating rate standard obtained based on engineering experience.

[0130] According to the above experimental operation, after obtaining the first-stage operation parameters and the second-stage parameters, the mass of the heat exchange medium after all the non-condensable gases are discharged during the experiment is obtained to provide parameter support for the formal online vacuum operation. That is, before the formal online vacuum operation, the heat exchange medium of this mass can be poured into the vacuum tube to be evacuated, so as to keep the mass of the heat exchange medium in the vacuum tube before and after the vacuum is not affected.

[0131] Specifically, before step SA1, step SA1 s is also included;

[0132] Step SA1 s. Pour a mass of m into the vacuum tube to be evacuated. 0 The heat transfer medium, where m 0 =m 1 +m 2 . m 1 is the reference pumping rate s of the experimental tube in one stage 1std The next stage is referred to as the pumping time t 1std The mass of the heat exchange medium extracted after the vacuum operation, m2 is the reference vacuum rate s of the experimental tube in the second stage 2std The second stage is carried out with reference to the pumping time t 2std The mass of the heat exchange medium extracted after the pumping operation.

[0133] After the heat pipe 1.1 test experiment is completed, the vacuum valve 3.3 is closed, the working medium heat exchange working medium collection valve 3.5 is closed, and the working medium heat exchange working medium injection console 2.1 issues a command to open the working medium heat exchange working medium injection valve 2.3. Under the action of negative pressure, the liquid working medium heat exchange working medium enters the experimental tube 1.1 from the working medium heat exchange working medium storage tank 2.2. When the added liquid working medium heat exchange working medium mass reaches m 0 When the working medium heat exchange working medium filling control console 2.1 issues a command to close the working medium heat exchange working medium filling valve 2.3, and the vacuum control console 3.1 issues a command to open the vacuum valve 3.3, and the air re-enters the heat pipe 1.1, and the experimental tube 1.1 returns to the state before the first stage of the heat pipe 1.1 exhaust experiment. During the second stage of exhaust and the inspection of the heat pipe 1.1, part of the working medium heat exchange working medium steam will be discharged from the heat pipe 1.1 along with the air. Therefore, before the exhaust operation, the working medium heat exchange working medium in the heat pipe 1.1 needs to be supplemented and filled in advance.

[0134] In a specific example, when the heat pipe 1.1 is being filled with heat exchange medium, the vacuum control console 3.1 issues a command to open the vacuum valve 3.3 at the minimum gear position S 0 Start the vacuum pump 3.2 for a starting time of t 0 , t 0 After 10 seconds, the vacuum control console 3.1 issues a command to close the vacuum valve 3.3 and the vacuum pump 3.2. At this time, the heat pipe 1.1 is turned into negative pressure, but the vacuum is not enough to make the heat exchange medium in the pipe boil. The heat exchange medium injection control console 2.1 issues a command to open the heat exchange medium injection valve 2.3. Under the action of negative pressure, the liquid heat exchange medium enters the heat pipe 1.1 from the heat exchange medium storage tank 2.2. When the mass of the heat exchange medium entering the single heat pipe 1.1 reaches m 0 When the heat exchange medium filling valve 2.3 corresponding to the heat pipe 1.1 is closed, the heat exchange medium filling stage of the heat pipe 1.1 is completed after the heat exchange medium filling of all the heat pipes 1.1 is completed.

[0135] In this way, the discharge amount of the heat exchange medium when the final experimental tube 1.1 becomes an effective heat pipe 1.1 after vacuuming can be obtained. In this way, the corresponding heat exchange medium is poured into the vacuum tube before the vacuuming operation is performed, so that the mass m 0 After the heat exchange medium is vaporized, the non-condensable gas in the vacuum tube can be taken out.

[0136] In the formal online air extraction operation, step SA1 e is further included before step SA1;

[0137] Step SA1 e: The number of vacuum tubes to be evacuated is K. The ambient flue gas temperature corresponding to each of the K vacuum tubes to be evacuated is obtained as the actual ambient temperature T k , {T k}={T 1 , T 2 ……T k}, according to the actual ambient temperature T k Calculate the first-stage pumping rate S 1 and the second stage pumping rate S 2 ;in,

[0138]

[0139] Among them, T in is the flue gas inlet temperature of the heat pipe air preheater, T out is the flue gas outlet temperature of the heat pipe air preheater, i 1 is the number of rows of a single vacuum tube in the direction of flue gas flow, and n is the number of effective heat pipes.

[0140] Connect k heat pipes 1.1 to the online vacuum pumping device to vacuum the heat pipe air preheater. Number the k heat pipes 1.1 as 1, 2, ... k, and calculate the flue gas temperature T of all the heat pipes 1.1 to be vacuumed. k , {T k}={T 1 , T 2 ……T k}.

[0141] Before the vacuum operation, obtain the corresponding vacuum environment temperature T of K vacuum tubes to be vacuumed. k In this way, the technical solution of the present application can select any number of vacuum tubes to be evacuated at any position for vacuuming operation.

[0142] After the heat exchange medium is filled, the corresponding exhaust environment temperature T of each of the K vacuum tubes to be evacuated is obtained. k After that, the first-stage vacuuming operation is started for any number and position of vacuum tubes to be evacuated.

[0143] According to the actual ambient temperature T k and reference ambient temperature T std Calculate the one-stage evacuation time t of each of the K vacuum tubes to be evacuated 1k , {t 1k}={t 11 , t 12 ……t 1k};in,

[0144]

[0145] Among them, B 1 The pumping time of one stage is t 1k Flue gas temperature correction factor, t 1std It is the reference pumping time for one stage.

[0146] During the specific operation, the first-stage exhaust time t of each vacuum tube to be evacuated is collected. 1k , the vacuum time t of each vacuum tube to be evacuated corresponds to 1k After completion, it is determined that the vacuum tube to be evacuated has completed one stage of evacuation operation.

[0147] Therefore, it is possible to determine whether the one-stage exhaust operation of the heat pipe 1.1 has been completed by obtaining whether the time of the one-stage exhaust operation corresponding to each to-be-evacuated tube has been met.

[0148] According to the reference ambient temperature T std and the actual ambient temperature T k Calculate the first-stage pumping rate S 1 :

[0149]

[0150] Among them, T max For {T k}, A 1 S is the pumping rate of one stage 1 Flue gas temperature correction factor, T std is the reference ambient temperature, S 1std It is a reference pumping rate obtained before the online pumping operation.

[0151] Optionally, the first judgment condition includes whether the time for the vacuum tube to be evacuated to perform a stage of evacuation operation is completed for a stage of evacuation time t 1k If the result is yes, it is determined that the vacuum tube to be evacuated has completed one stage of evacuation operation.

[0152] In some other embodiments, step SA1 includes:

[0153] Step SA11: According to the first stage of the pumping rate S 1 Perform one-stage vacuuming operation on K vacuum tubes at the same time;

[0154] Step SA12, determining whether the vacuum tube to be evacuated has completed a stage of evacuation operation;

[0155] Step SA13: If the result is yes, calculate the new air extraction rate S' for the first stage 1 , calculate the new pumping rate S' in the first stage according to the following formula 1 :

[0156]

[0157] Wherein, x1 is the number of heat pipes 1.1 that have completed one stage of exhaust operation.

[0158] Step SA14: adopting a new first-stage pumping rate S' 1 The remaining vacuum tubes to be evacuated are evacuated, and step SA13 is repeated until the K vacuum tubes to be evacuated have completed the first stage of evacuation operation.

[0159] In this way, when performing the evacuation operation on K vacuum tubes, after each vacuum tube completes one stage of evacuation operation, the evacuation rate of the one stage of evacuation operation is adjusted, so that the new evacuation rate can meet the demand of the remaining vacuum tubes.

[0160] In a specific example, during the first stage of vacuuming, the vacuum control console 3.1 issues a command to open the vacuum valve 3.3, start the vacuum pump 3.2, and set the vacuuming rate to S 1, start to evacuate the heat pipe 1.1. For the heat pipe 1.1 of No. k, when the first stage of evacuation time t is reached, 1k When the vacuum valve 3.3 corresponding to the heat pipe 1.1 is closed, and whenever a heat pipe 1.1 completes one stage of vacuuming, the vacuum pump 3.2 is adjusted to pump air at a rate until all the test heat pipes 1.1 to be vacuumed complete one stage of vacuuming.

[0161] In addition, after the first stage of the vacuuming operation is completed, the K vacuum tubes to be vacuumed are subjected to the second stage of the vacuuming operation. In this embodiment, according to the actual ambient temperature T k and reference ambient temperature T std Calculate the two-stage vacuuming time t of each of the K vacuum tubes to be evacuated 2k , {t 2k}={t 21 , t 22 ……t 2k};in,

[0162]

[0163] Among them, B 2 is the second stage pumping time t 2k Flue gas temperature correction factor, t 2std It is the second-stage reference pumping time obtained prior to the online pumping operation.

[0164] In the above-mentioned embodiment, according to a stage reference exhaust time t 1std Get the corresponding reference pumping rate S for one stage 1std According to the second stage reference pumping time t 2std Get the corresponding second-stage reference pumping rate S 2std .

[0165] Specifically, the second-stage pumping rate S is calculated according to the following formula: 2 :

[0166]

[0167] Among them, A 2 is the flue gas temperature correction coefficient of the second stage extraction rate, T min For {T k Thus, the pumping rate when two-stage pumping operation is performed on K vacuum tubes to be pumped simultaneously can be obtained.

[0168] Optionally, according to the vacuum environment temperature T corresponding to each of the K vacuum tubes to be evacuated k Get the second-stage vacuuming time t corresponding to each vacuum tube to be evacuated 2k , {t 2k}={t 21 , t22 ……t 2k};

[0169] Step SA12 also includes collecting the second-stage exhaust time t of each vacuum tube to be evacuated for the second-stage exhaust operation. 2k , the second stage vacuuming time t corresponding to each vacuum tube to be evacuated 2k After completion, it is determined that the vacuum tube to be evacuated has completed the second-stage evacuation operation.

[0170] Therefore, it is possible to determine whether the vacuum tube to be evacuated has completed the two-stage evacuation operation according to the corresponding time.

[0171] Optionally, the second-stage vacuuming time t corresponding to each vacuum tube to be evacuated is 2k The calculation is performed as follows:

[0172]

[0173] Among them, B 2 is the second stage pumping time t 2k Flue gas temperature correction coefficient. Thus, the second-stage exhaust time of each vacuum tube to be evacuated can be obtained.

[0174] During the second stage of vacuuming, the vacuum console 3.1 issues a command to set the vacuuming rate to S 2 , start the vacuum pump 3.2, open the heat exchange medium collecting valve 3.5, open all vacuum valves 3.3, and start evacuating the heat pipe 1.1. For k heat pipes 1.1, when the second stage evacuation time t is reached, 2k At the same time, when a heat pipe 1.1 completes the second stage of vacuuming, the vacuum pump 3.2 is adjusted to pump air at a rate that is proportional to the heat pipe 1.1. When all heat pipes 1.1 reach the vacuuming time, the heat exchange medium collecting valve 3.5 is closed, and the second stage of vacuuming of the heat pipe 1.1 is completed.

[0175] In some optional embodiments, step SA2 further includes:

[0176] Step SA21: According to the second stage exhaust rate S 2 Perform two-stage vacuuming operation on K vacuum tubes at the same time;

[0177] Step SA22, determining whether the vacuum tube to be evacuated has completed the second stage of evacuation operation;

[0178] Step SA23: If the result is yes, calculate the second-stage new pumping rate S' 2 , calculate the second-stage new pumping rate S' according to the following formula 2 :

[0179]

[0180] Here, x2 is the number of heat pipes 1.1 that have completed the second-stage exhaust operation.

[0181] Step SA24: adopting the two-stage new pumping rate S' 2 The remaining vacuum tubes to be evacuated are evacuated, and step SA23 is repeated until the K vacuum tubes to be evacuated have completed the second-stage evacuation operation.

[0182] Thus, the two-stage pumping operation can be performed on K vacuum tubes at the same time, and whenever one vacuum tube completes the two-stage pumping operation, the two-stage pumping rate is recalculated to meet the requirements of the two-stage pumping operation on the remaining vacuum tubes.

[0183] In the aforementioned embodiment, the online vacuuming method further comprises:

[0184] Step SC1: Obtain the actual heating rate T' and the standard heating rate T' of the set position of the vacuum tube to be evacuated 0 , judge the actual heating rate T' and the standard heating rate T' 0 Whether the difference of meets the first condition, if the result is yes, the vacuum degree of the vacuum tube to be evacuated meets the requirement. In this way, it is judged whether the vacuum degree of the vacuum tube to be evacuated meets the requirement.

[0185] Optionally, in step SC1, it further includes:

[0186] Step SC11, collect the real-time temperature of the set area of ​​the vacuum tube to be evacuated, that is, the temperature of the head end of the heat pipe 1.1. When the real-time temperature meets the second condition, obtain the current temperature as the first temperature T 0 ;

[0187] Step SC12: perform a vacuum operation on the vacuum tube to be evacuated during the inspection phase, and collect the real-time temperature of the set area. When the real-time temperature meets the third condition, the temperature at the current moment is obtained as the second temperature T t , and obtain the first temperature T 0 To the second temperature T t time Δt;

[0188] Step SC13: Calculate the actual heating rate T′ according to the following formula:

[0189] In this way, the actual heating rate can be obtained and used as a parameter condition to determine whether the heat pipe 1.1 meets the vacuum requirement. If not, it means that there is still a certain amount of air in the heat pipe 1.1, and the heat pipe 1.1 will be evacuated again. After the qualified heat pipe 1.1 head is sealed, all vacuum valves 3.3 are opened, and the working medium heat exchange working medium injection system 2 and the vacuum generation system 3 are disconnected from the heat pipe air preheater 1. At this point, the evacuation of the heat pipe 1.1 is completed.

[0190] By adopting the above solution, the present application has the following advantages:

[0191] First, the technical solution of the present application can realize the vacuuming of the heat pipe air preheater 1 at the installation location of the heat pipe air preheater 1 without cutting off the cold source of the heat pipe air preheater 1 and without affecting the normal operation of other equipment. In addition, it is possible to vacuumize any number of heat pipes 1.1 and heat pipes 1.1 at any position at the same time, which improves the efficiency of the vacuuming work and also meets the requirement that only some of the heat pipes 1.1 in the heat pipe air preheater need to be vacuumed. At the same time, the entire vacuuming process is automated, without the need for operator intervention, which improves the work efficiency of the vacuuming operation of the heat pipe 1.1.

[0192] Second, before the heat pipe 1.1 is formally evacuated to form a vacuum, a vacuum test is performed on the heat pipe 1.1 to obtain the operating parameters required for the formal vacuuming and the mass of the heat exchange medium consumed during the vacuuming process, which provides reference data for the formal vacuuming operation and helps to ensure the quality of the heat exchange work during the vacuuming process of the heat pipe 1.1.

[0193] Third, before the heat pipe 1.1 is evacuated, a slight negative pressure environment is created in the heat pipe 1.1 by using the vacuum generating system 3, and then the heat exchange medium injection system 2 uses this negative pressure environment to inject a certain mass of heat exchange medium into the heat pipe 1.1, thereby compensating for the heat exchange medium lost during the evacuation of the heat pipe 1.1 and the inspection of the heat pipe 1.1, ensuring the consistency of the heat exchange medium quality in the heat pipe 1.1 before and after evacuation, and avoiding the loss of heat exchange medium in the pipe due to evacuation, which leads to a decrease in the heat exchange efficiency of the heat pipe 1.1.

[0194] Fourth, when the heat pipe 1.1 is formally evacuated, the evacuation rate of the vacuum pump 3.2 is dynamically and real-time adjusted according to the operating parameters obtained from the evacuation experiment of the heat pipe 1.1, combined with the flue gas temperature during the formal evacuation, the number of heat pipes 1.1 and other conditions, to ensure that the boiling rate of the heat exchange medium in the heat pipe 1.1 is within a normal range. At the same time, combined with the position of each heat pipe 1.1 in the heat pipe air preheater, a reasonable evacuation time is set for each heat pipe 1.1 to avoid a decrease in the heat transfer efficiency of the heat pipe 1.1 caused by insufficient or excessive exhaust.

[0195] After the heat pipe 1.1 is evacuated, the heat pipe 1.1 is evacuated again, and whether the heat pipe 1.1 is evacuated properly is determined based on the heating rate of the heat pipe 1.1, thereby ensuring that the vacuum degree of the heat pipe 1.1 meets the requirements.

[0196] During the inspection of the heat pipe 1.1, the heat pipe 1.1 is evacuated using a two-stage exhaust rate, the temperature acquisition component 1.5 is used to record the temperature change on the surface of the heat pipe 1.1, and the heating rate of the heat pipe 1.1 is calculated. Whether the vacuuming of the heat pipe 1.1 is qualified is determined based on the heating rate of the heat pipe 1.1.

[0197] Fifth, during the first stage of exhaustion, the exhaust rate is adjusted according to the highest flue gas temperature among all the heat extraction tubes 1.1 and the number of heat extraction tubes 1.1, and the exhaust time is adjusted according to the flue gas temperature of each heat pipe 1.1. At the same time, whenever a heat pipe 1.1 reaches the exhaust time and completes the first stage of exhaustion, the vacuuming rate of the heat pipe 1.1 is reduced synchronously. During the second stage of exhaustion of the heat pipe 1.1, the exhaust rate is adjusted according to the lowest flue gas temperature among all the heat extraction tubes 1.1 and the number of heat extraction tubes 1.1, and the exhaust time is adjusted according to the flue gas temperature of each heat pipe 1.1. At the same time, whenever a heat pipe 1.1 reaches the exhaust time and completes the second stage of exhaustion, the vacuuming rate of the heat pipe 1.1 is reduced synchronously.

[0198] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the core idea of ​​the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for online vacuuming of a heat pipe air preheater, characterized in that: The heat pipe air preheater is applied to a boiler system, and the method for online vacuuming of the heat pipe air preheater comprises: Step SA, while maintaining the normal operating condition of the boiler system, performing an online vacuum operation on the vacuum tube to be evacuated; Step SC, checking whether the vacuum degree of the vacuum tube to be evacuated is qualified, and if the result is yes, performing a packaging operation on the vacuum tube to be evacuated.

2. The method for online vacuuming of a heat pipe air preheater according to claim 1, characterized in that: In the step SA, the online air extraction operation further includes: Step SA1, performing a first-stage exhaust operation on the vacuum tube to be exhausted according to a first-stage operating parameter, wherein the first-stage operating parameter includes a first-stage exhaust rate S1; Step SA2, judging whether the vacuum tube to be evacuated has completed the first-stage exhaust operation according to the first judgment condition, and after the vacuum tube to be evacuated satisfies the first judgment condition, performing the second-stage exhaust operation on the vacuum tube to be evacuated according to the second-stage operation parameters, wherein the second-stage operation parameters include the second-stage exhaust rate S2; wherein the first-stage exhaust rate S1 is greater than the second-stage exhaust rate S2; Step SA3: judging whether the vacuum tube to be evacuated has completed the two-stage exhaust operation according to the second judgment condition; after the vacuum tube to be evacuated satisfies the second judgment condition, performing step SC.

3. The method for online vacuuming of a heat pipe air preheater according to claim 2, characterized in that: Before the step SA, the method further includes: Step SE1a: Select a vacuum tube at any position as a test tube, and obtain the flue gas environment temperature corresponding to the test tube as the reference environment temperature T std , the first-stage pumping rate S1 and the second-stage pumping rate S2 are calculated according to the reference ambient temperature; wherein, T instd is the flue gas inlet temperature of the heat pipe air preheater, T outstd is the flue gas outlet temperature of the heat pipe air preheater, i std is the number of rows of the experimental tubes in the direction of smoke flow, and n is the number of effective heat pipes.

4. The method for online vacuuming of a heat pipe air preheater according to claim 3, characterized in that: Before step SA1, step SA1e is also included; Step SA1e: The number of the vacuum tubes to be evacuated is K, and the ambient flue gas temperature corresponding to each of the K vacuum tubes to be evacuated is obtained as the actual ambient temperature T k , {T k }={T1,T2……T k }, according to the actual ambient temperature T k Calculating the first-stage pumping rate S1 and the second-stage pumping rate S2; in, Among them, T in is the flue gas inlet temperature of the heat pipe air preheater, T out is the flue gas outlet temperature of the heat pipe air preheater, i1 is the number of rows of the single vacuum tube to be evacuated in the flue gas flow direction, and n is the number of effective heat pipes.

5. The method for online vacuuming of a heat pipe air preheater according to claim 4, characterized in that: According to the reference ambient temperature T std and the actual ambient temperature T k Calculate the pumping rate S1 of the first stage: Among them, T max For {T k }, A1 is the flue gas temperature correction coefficient of the first stage exhaust rate S1, T std is the reference ambient temperature, S 1std It is the reference pumping rate of the stage obtained before the online pumping operation.

6. The method for online vacuuming of a heat pipe air preheater according to claim 5, characterized in that: According to the actual ambient temperature T k and the reference ambient temperature T std Calculate the vacuum time t of each of the K vacuum tubes to be evacuated in one stage 1k , {t 1k }={t 11 , t 12 ……t 1k };in, Wherein, B1 is the pumping time t of the first stage 1k Flue gas temperature correction factor, t 1std The reference pumping time for the said stage.

7. The method for online vacuuming of a heat pipe air preheater according to claim 6, characterized in that: According to the first stage reference pumping time t 1std Get the corresponding reference pumping rate S of the stage 1std ; The step SA1 comprises: Step SA11, performing the one-stage pumping operation on the K vacuum tubes to be pumped at the same time according to the one-stage pumping rate S1; Step SA13, when each of the K vacuum tubes to be evacuated completes the one-stage evacuation operation, calculating the one-stage new evacuation rate S′1; Step SA14, using the new one-stage pumping rate S′1 to pump the remaining vacuum tubes, and repeating step SA13 until the K vacuum tubes have completed the one-stage pumping operation; wherein, The new pumping rate S′1 of the first stage is calculated according to the following formula: x1 is the number of heat pipes that have completed one stage of exhaust operation.

8. The method for online vacuuming of a heat pipe air preheater according to any one of claims 4 to 7, characterized in that: According to the reference ambient temperature T std and the actual ambient temperature T k Calculate the second stage pumping rate S2: Where A2 is the flue gas temperature correction coefficient of the second stage extraction rate, T min For {T k }, T std is the reference ambient temperature, S 2std It is the second-stage reference pumping rate obtained before the online pumping operation.

9. The method for online vacuuming of a heat pipe air preheater according to claim 8, characterized in that: The actual ambient temperature T k and the reference ambient temperature T std Calculate the second-stage vacuuming time t of each of the K vacuum tubes to be evacuated 2k , {t 2k }={t 21 , t 22 ……t 2k };in, Wherein, B2 is the second stage exhaust time t 2k Flue gas temperature correction factor, t 2std It is the second-stage reference pumping time obtained prior to the online pumping operation.

10. The method for online vacuuming of a heat pipe air preheater according to claim 9, characterized in that: According to the two-stage reference pumping time t 2std Get the corresponding second-stage reference pumping rate S 2std ; The step SA2 further comprises: Step SA21, performing the two-stage pumping operation on K vacuum tubes to be pumped at the same time according to the two-stage pumping rate S2; Step SA23: among the K vacuum tubes to be evacuated, whenever one of the vacuum tubes to be evacuated completes the second-stage evacuation operation, calculate the second-stage new evacuation rate S′2, and calculate the second-stage new evacuation rate S′2 according to the following formula: x2 is the number of vacuum tubes to be evacuated that have completed the two-stage evacuation operation Step SA24, using the second-stage new pumping rate S′2 to pump air on the remaining vacuum tubes to be pumped, and repeating step SA23 until the K vacuum tubes to be pumped have completed the second-stage pumping operation.

11. An online vacuum pumping device for a heat pipe air preheater, characterized in that: A method for online vacuuming of a heat pipe air preheater adapted to any one of claims 1 to 10, wherein the heat pipe air preheater comprises a plurality of pipe rows distributed along a first direction, each of the heat pipe rows is provided with a plurality of heat pipes, and a heat exchange medium is contained in the heat pipes; It comprises a smoke channel and an air channel, one side of each heat pipe is located in the smoke channel, and the other side is located in the air channel; The first end of the heat pipe extends from a side of the air passage away from the smoke passage; It also comprises a vacuum pump (3.2), a condenser (3.6) and a liquid collecting device (3.4); the inlet of the condenser (3.6) is connected to the head end of the tube body, the gas outlet of the condenser (3.6) is connected to the vacuum pump (3.2), and the liquid outlet of the condenser (3.6) is connected to the liquid collecting device (3.4).

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