A dyeing machine heat energy management system and method based on multi-stage heat exchange

Abstract

The present application relates to cloth dyeing machine technical field, especially in dyeing machine heat energy management system and method based on multistage heat exchange, including cloth dyeing machine main body, main heat exchange unit, multistage waste heat recovery unit, heat storage buffer unit and intelligent temperature control unit, cloth dyeing machine main body includes barrel, cloth guide pipe, dye liquor circulating pump and nozzle assembly, the inside of barrel forms cloth circulation channel, cloth guide pipe is connected to the both ends of barrel and forms dye liquor injection circuit with nozzle assembly;Main heat exchange unit includes steam inlet regulating valve, shell-and-tube heat exchanger and condensate recovery device, the shell side inlet of shell-and-tube heat exchanger is communicated with the bottom of barrel by dye liquor circulating pump, and the shell side outlet is communicated with nozzle assembly;The tube side inlet is connected with external steam source through steam inlet regulating valve, and the tube side outlet is connected with condensate recovery device.The present application realizes the step-by-step utilization and dynamic deployment of heat energy in the whole process of cloth dyeing by constructing the collaborative architecture of multistage heat exchange network and heat storage buffer unit.

Description

Technical Field

[0001] This invention relates to the field of dyeing machine technology, and in particular to a thermal energy management system and method for dyeing machines based on multi-stage heat exchange. Background Technology

[0002] As an industrial device that uses mechanical structures to achieve dyeing, the dyeing machine is mainly used in textile material processing and biomedical fields. In the textile industry, dyeing machines are usually made entirely of stainless steel and cover types such as rope dyeing and flat-width pad dyeing. Energy consumption is reduced through low liquor ratio design and intelligent control system.

[0003] Generally, a fabric dyeing machine mainly consists of a drum, a guide tube, a dye liquor supply device, and a heat exchanger. When fabric is being dyed in the machine, the dye liquor is first pumped to the heat exchanger tubes for indirect heat exchange with steam or room-temperature water. Then, the heated dye liquor is delivered to nozzles at the front of the drum, where a high-speed jet of water propels the fabric into the guide tube. The fabric and dye liquor absorb heat from the steam in the guide tube and enter the drum, moving from the tail to the head. There, it circulates under the influence of lifting wheels at the head and the pressure of the dye liquor from the nozzles. The entire dyeing process involves repeated heating, holding, and cooling cycles, requiring multiple cycles to complete the final dyeing process. However, existing dyeing equipment requires replacing the dye liquor after completing the same batch of dyeing operations, and typically discharges the preheated dye liquor directly, resulting in a significant waste of thermal energy. Statistics show that the thermal energy utilization rate of traditional dyeing equipment is usually only between 35% and 45%, with more than half of the thermal energy lost through waste liquor discharge. This not only increases energy costs for businesses but also causes significant thermal pollution to the environment.

[0004] Furthermore, existing dyeing equipment often employs a single-stage heat exchange system, which fails to fully utilize the temperature gradient between steam and dye liquor, thus limiting heat exchange efficiency. Although some dyeing machines have begun to experiment with waste heat recovery devices, these devices generally suffer from low recovery efficiency, significant degradation of recovered heat energy quality, and poor coupling with the main process system. Summary of the Invention

[0005] In order to address the technical deficiencies mentioned in the background art, the purpose of this invention is to provide a thermal energy management system and method for a dyeing machine based on multi-stage heat exchange, aiming to solve the technical problems of low thermal energy utilization rate, insufficient waste heat recovery efficiency, and poor coupling between the heat exchange system and the main process in existing dyeing equipment.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A thermal energy management system for a fabric dyeing machine based on multi-stage heat exchange includes a fabric dyeing machine body, a main heat exchange unit, a multi-stage waste heat recovery unit, and a heat storage buffer unit. The fabric dyeing machine body includes a cylinder, a guide pipe, a dye liquor circulation pump, and a nozzle assembly. A fabric circulation channel is formed inside the cylinder. The guide pipe is connected to both ends of the cylinder and forms a dye liquor spraying circuit with the nozzle assembly. The dye liquor circulation pump is located in the pipeline between the bottom outlet of the cylinder and the main heat exchange unit. The main heat exchange unit includes a steam inlet regulating valve, a shell-and-tube heat exchanger, and a condensate recovery device. The shell-side inlet of the shell-and-tube heat exchanger is connected to the bottom of the shell body through a dye liquor circulation pump, and the shell-side outlet is connected to a nozzle assembly. The tube-side inlet of the shell-and-tube heat exchanger is connected to an external steam source through a steam inlet regulating valve, and the tube-side outlet is connected to a condensate recovery device. The multi-stage waste heat recovery unit includes a primary plate heat exchanger, a secondary spiral wound tube heat exchanger, and a tertiary phase change heat storage heat exchanger. The high-temperature inlet of the primary plate heat exchanger is connected to the waste liquid discharge pipeline of the dyeing machine body, and the high-temperature outlet is connected to the high-temperature inlet of the secondary spiral wound tube heat exchanger. The low-temperature inlet of the primary plate heat exchanger is connected to an external water supply, and the low-temperature outlet is connected to the low-temperature inlet of the secondary spiral wound tube heat exchanger. The high-temperature outlet of the secondary spiral wound tube heat exchanger is connected to the high-temperature inlet of the tertiary phase change heat storage heat exchanger, and the low-temperature outlet is connected to the low-temperature inlet of the tertiary phase change heat storage heat exchanger. The high-temperature outlet of the tertiary phase change heat storage heat exchanger is connected to the wastewater treatment system, and the low-temperature outlet is connected to the inlet of the dye liquor circulation pump through a preheated dye liquor return pipe. The heat storage buffer unit includes a high-temperature heat storage tank, a medium-temperature heat storage tank, and a low-temperature heat storage tank. The inlet of the high-temperature heat storage tank is selectively connected to the high-temperature side outlet of the first-stage plate heat exchanger via a first electrically controlled three-way valve, and the outlet is selectively connected to the shell-side inlet of the main heat exchange unit via a second electrically controlled three-way valve. The inlet of the medium-temperature heat storage tank is selectively connected to the high-temperature side outlet of the second-stage spiral wound tube heat exchanger via a third electrically controlled three-way valve, and the outlet is selectively connected to the inlet of either the high-temperature heat storage tank or the low-temperature heat storage tank via a fourth electrically controlled three-way valve. The inlet of the low-temperature heat storage tank is selectively connected to the high-temperature side outlet of the third-stage phase change heat storage heat exchanger via a fifth electrically controlled three-way valve, and the outlet is selectively connected to the low-temperature side inlet of the second-stage spiral wound tube heat exchanger or an external water source preheating pipeline via a sixth electrically controlled three-way valve.

[0007] Preferably, multiple heat exchange tube bundles are embedded in the inner wall of the guide tube, and the multiple heat exchange tube bundles are circumferentially distributed in the cavity of the guide tube. One end of the heat exchange tube bundle is connected to the bottom outlet of the cylinder through a dye liquor circulation pump, and the other end is connected to the shell-side outlet of the main heat exchange unit through a one-way valve.

[0008] Preferably, the nozzle assembly includes a main nozzle, an auxiliary nozzle, and a nozzle switching valve group. The main nozzle is connected to the shell-side outlet of the main heat exchange unit, and the auxiliary nozzle is connected to the low-temperature side outlet of the three-stage phase change heat storage heat exchanger through a preheating dye liquor branch. The nozzle switching valve group controls the individual or combined activation of the main nozzle and the auxiliary nozzle according to the operating stage of the dyeing machine.

[0009] Preferably, a leak detection chamber is provided between the high-temperature side channel and the low-temperature side channel of the primary plate heat exchanger. The leak detection chamber is filled with a colorimetric indicator and connected to an optical leak alarm.

[0010] Preferably, the two-stage spiral wound tube heat exchanger includes an outer shell, a central cylinder, and a multi-layer spiral wound tube bundle. An annular counter-flow channel is formed between the outer shell and the central cylinder. The cross-sectional area of ​​the annular counter-flow channel gradually shrinks along the axial direction. The spiral wound tube bundle is concentrically wound in layers with the central cylinder as the axis, and the winding directions of adjacent layers of spiral wound tube bundles are opposite.

[0011] Preferably, the three-stage phase change heat exchanger includes a shell, a phase change heat storage core, and heat transfer finned tubes. The phase change heat storage core fills the interior of the shell and forms multiple parallel heat storage unit chambers. Each heat storage unit chamber is separated by a heat-conducting baffle. The heat transfer finned tubes penetrate each heat storage unit chamber, and the fins are perforated corrugated fins.

[0012] Preferably, the high-temperature heat storage tank, the medium-temperature heat storage tank, and the low-temperature heat storage tank are all equipped with temperature stratification partitions inside, and the temperature stratification partitions are horizontally arranged perforated inclined temperature stratification plates.

[0013] Preferably, the condensate recovery device includes a flash tank and a condensate pump. The inlet of the flash tank is connected to the tube-side outlet of the shell-and-tube heat exchanger, and the steam outlet of the flash tank is connected to the inlet side of the steam inlet regulating valve through a steam circulation pipeline. The inlet of the condensate pump is connected to the liquid water outlet of the flash tank, and the outlet is connected to the boiler feedwater system, the dye liquor preparation water system, and the external discharge pipeline through a water quality diversion valve group.

[0014] Preferably, it also includes an intelligent temperature control unit, the intelligent temperature control unit comprising: Temperature sensor used to monitor dye liquor temperature and recovered heat temperature in real time; A dye liquor flow monitoring module is installed at the junction of the outlet pipeline of the dye liquor circulation pump and the preheated dye liquor return pipeline. A steam pressure regulating module, which is electrically connected to a steam inlet regulating valve; The central control processor is connected to the temperature sensor, the dye liquor flow monitoring module, the steam pressure regulating module, the dye liquor circulation pump, and each electrically controlled three-way valve.

[0015] A method for a thermal energy management system for a dyeing machine based on multi-stage heat exchange includes the following steps: S1. Heat balance establishment: The central control processor receives parameters such as target dye liquor temperature, heating rate, holding time and cooling curve, and calculates the initial heat load distribution strategy based on the liquid level and temperature status of the heat storage tank. S2. Heat energy distribution during the heating stage: The dye liquor circulation pump operates at a set frequency, pumping the dye liquor from the bottom of the cylinder to the main heat exchange unit. After being heated by the shell-and-tube heat exchanger, it is injected into the guide pipe through the main nozzle. The temperature sensor monitors the temperature of the fabric and the dye liquor in real time. The central control processor adjusts the opening of the steam valve and the pump frequency according to the feedback deviation to ensure that the heating curve meets the set requirements. S3. Multi-stage waste heat recovery and heat storage: The first-stage plate heat exchanger uses high-temperature waste liquid to preheat and replenish the water source, and part of it is stored in the low-temperature heat storage tank; the medium-temperature waste liquid is heated to the water source again by the second-stage spiral wound tube heat exchanger, and the heated water source is led to the medium-temperature heat storage tank or continues to the third-stage heat exchange; the low-temperature waste liquid is heated by the third-stage phase change heat storage heat exchanger; when the medium-temperature heat storage tank is at full load, the heat energy is transferred to the high-temperature heat storage tank for storage through the fourth electrically controlled valve; S4. Low-energy operation during the heat preservation stage: After reaching the target temperature, reduce the frequency of the dye liquor circulation pump, close or slightly open the steam valve, and switch to the auxiliary nozzle mode; preheat the dye liquor and directly introduce it into the auxiliary nozzle to maintain circulation and temperature stability with low injection pressure. S5. Heat transfer and recovery during cooling stage: Start the combined nozzle mode, open the main / auxiliary nozzles in proportion, and inject heated dye liquor and low-temperature preheated dye liquor respectively, mix to form a gradient cooling; the dye liquor circulation pump runs at high frequency to transfer the heat of the cylinder to the waste heat recovery unit. S6. Shutdown maintenance and safety monitoring: After shutdown, execute the heat storage tank pressure holding procedure, close all electrically controlled three-way valves and maintain the heat insulation state to store heat energy for the next startup.

[0016] In summary, the beneficial effects of the present invention are as follows: This invention achieves tiered utilization and dynamic allocation of thermal energy throughout the dyeing process by constructing a collaborative architecture of a multi-stage heat exchange network and a heat storage buffer unit. The main heat exchange unit adopts a dual heating mode of shell-and-tube heat exchangers and heat exchange tube bundles inside the guide tubes, significantly shortening the heating time of the dye liquor and reducing the instantaneous steam consumption. The multi-stage waste heat recovery unit uses a series-parallel combination of three types of heat exchangers—plate, spiral wound tube, and phase change heat storage—to reduce the waste liquor discharge temperature from 85 to 95 degrees Celsius in traditional processes to 35 to 45 degrees Celsius, increasing the waste heat recovery rate to over 78%. The heat storage buffer unit is equipped with high, medium, and low temperature heat storage tanks, which, combined with the flexible switching of electrically controlled three-way valves, effectively solves the mismatch between waste heat recovery and the heat used in the main process in terms of time and grade, allowing the recovered heat energy to be directly reused in multiple stages such as dye liquor preheating, boiler feedwater, and dye liquor preparation. Attached Figure Description

[0017] Figure 1 This is a production layout diagram of the thermal energy management system for the dyeing machine of the present invention, wherein the solid line represents the waste liquid recovery path, the dashed line represents the waste heat recovery path, and the arrow indicates the flow direction. Figure 2 This is a flowchart of the multi-stage waste heat recovery unit in this invention, wherein the solid line represents the flow path of the waste liquid on the high-temperature side, the dashed line represents the flow path of the waste heat on the low-temperature side, and the arrow indicates the flow direction. Figure 3 This is a top view of the main body of the dyeing machine in this invention; Figure 4 This is a longitudinal sectional view of the guide tube in this invention; Figure 5 This is a schematic diagram of the condensate recovery device in this invention; Figure 6 This is a half-sectional view of the condensate recovery device in this invention; Figure 7 This is a schematic diagram of the structure of the primary plate heat exchanger in this invention; Figure 8 This is a half-sectional view of the primary plate heat exchanger in this invention; Figure 9 This is a schematic diagram of the structure of the two-stage spiral wound tube heat exchanger in this invention; Figure 10 This is a half-sectional view of the two-stage spiral wound tube heat exchanger in this invention; Figure 11 This is a schematic diagram of the three-stage phase change heat storage heat exchanger in this invention; Figure 12 This is a half-sectional view of the three-stage phase change heat storage heat exchanger in this invention; Figure 13 This is a half-sectional view of the heat storage buffer unit in this invention.

[0018] Explanation of the reference numerals in the figure: 1. Main body of the dyeing machine; 11. Cylinder; 12. Guide tube; 121. Heat exchange tube bundle; 13. Dye liquor circulation pump; 14. Nozzle assembly; 141. Main nozzle; 142. Auxiliary nozzle; 143. Nozzle switching valve group; 2. Main heat exchange unit; 21. Steam inlet regulating valve; 22. Shell and tube heat exchanger; 23. Condensate recovery device; 231. Flash tank; 232. Condensate pump; 3. Multi-stage waste heat recovery unit; 31. First-stage plate heat exchanger; 311. Leakage detection chamber; 32. Second-stage spiral wound tube heat exchanger; 32 1. Outer shell; 322. Central cylinder; 323. Spiral wound tube bundle; 33. Three-stage phase change heat exchanger; 331. Shell; 332. Phase change heat storage core; 333. Heat transfer finned tube; 334. Thermally conductive baffle; 4. Heat storage buffer unit; 41. High-temperature heat storage tank; 42. Medium-temperature heat storage tank; 43. Low-temperature heat storage tank; 44. Temperature stratification baffle; 5. First electrically controlled three-way valve; 6. Second electrically controlled three-way valve; 7. Third electrically controlled three-way valve; 8. Fourth electrically controlled three-way valve; 9. Fifth electrically controlled three-way valve; 10. Sixth electrically controlled three-way valve. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0020] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0021] In the description of this invention, the use of terms such as "a number" means one or more, with "more than" meaning two or more. Terms like "greater than," "less than," and "exceeding" are understood to exclude the stated number, while terms like "above," "below," and "within" are understood to include the stated number. The use of terms like "first," "second," and "third" is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, the number of indicated technical features, or the sequential relationship between indicated technical features.

[0022] The following is in conjunction with the appendix Figure 1-13The present invention will be further described in detail with respect to an embodiment of a thermal energy management system and method for a dyeing machine based on multi-stage heat exchange.

[0023] A thermal energy management system for a dyeing machine based on multi-stage heat exchange, such as Figure 1-3 As shown, it includes the main body of the dyeing machine 1, the main heat exchange unit 2, the multi-stage waste heat recovery unit 3, and the heat storage buffer unit 4.

[0024] In this embodiment, the main body 1 of the dyeing machine includes a cylinder 11, a guide pipe 12, a dye liquor circulation pump 13, and a nozzle assembly 14. A fabric circulation channel is formed inside the cylinder 11. The guide pipe 12 is connected to both ends of the cylinder 11 and forms a dye liquor spraying circuit with the nozzle assembly 14. The dye liquor circulation pump 13 is located in the pipeline between the bottom outlet of the cylinder 11 and the main heat exchange unit 2, and is used to drive the dye liquor to circulate in the system.

[0025] Furthermore, the cylinder body 11 adopts a double-layer stainless steel jacket structure, with the jacket filled with aerogel insulation material to effectively reduce heat loss from the surface of the cylinder body 11. The guide pipe 12 has an elliptical cross-section design, with its major axis aligned with the fabric running direction and the heat exchange tube bundle 121 mounting holes arranged along its minor axis. This design maximizes the heat exchange area while ensuring smooth fabric passage. The dye liquor circulation pump 13 is a variable frequency magnetic drive centrifugal pump. The pump body's flow-through components are made of 316L stainless steel, and the impeller adopts a backward-curved blade design to adapt to the varying circulation flow requirements of different dyeing processes.

[0026] To improve the utilization efficiency of residual heat from the dyeing liquor, in this embodiment, as follows: Figure 1 , 4 As shown, multiple heat exchange tube bundles 121 are embedded in the inner wall of the guide tube 12. These heat exchange tube bundles 121 are circumferentially distributed within the cavity of the guide tube 12. One end of each heat exchange tube bundle 121 is connected to the bottom outlet of the cylinder 11 via a dye liquor circulation pump 13, and the other end is connected to the shell-side outlet of the main heat exchange unit 2 via a one-way valve. This design fully utilizes the internal space of the guide tube 12 to preheat or precool the dye liquor during fabric transport, shortening the temperature adjustment response time of the main heat exchange unit 2. Simultaneously, it utilizes the residual heat of steam within the guide tube 12 to improve overall thermal efficiency.

[0027] In this embodiment, as Figure 1 , 3As shown, the nozzle assembly 14 includes a main nozzle 141, an auxiliary nozzle 142, and a nozzle switching valve group 143. The main nozzle 141 is connected to the shell-side outlet of the main heat exchange unit 2, and the auxiliary nozzle 142 is connected to the low-temperature side outlet of the three-stage phase change heat storage heat exchanger 33 through a preheating dye liquor branch. The nozzle switching valve group 143 controls the individual or combined activation of the main nozzle 141 and the auxiliary nozzle 142 according to the operation stage of the dyeing machine. During the heating stage, the main nozzle 141 is activated alone to ensure rapid heating. During the heat preservation stage, the auxiliary nozzle 142 is activated alone to maintain the temperature using low-grade heat energy. During the cooling stage, they are activated together to achieve gradient temperature control.

[0028] Furthermore, both the main nozzle 141 and the auxiliary nozzle 142 are equipped with swirling atomizers at their outlet ends. These atomizers employ a tangential liquid inlet structure, where the dye liquor is accelerated through the swirling chamber and then passes through a narrow-diameter nozzle to form a hollow conical atomized jet. This ensures uniform contact between the dye liquor and the fabric and reduces heat loss caused by dye liquor splashing. The nozzle switching valve assembly 143 includes a series-parallel combination of a two-position three-way solenoid valve and a proportional regulating valve. The central control processor controls the valve assembly opening based on the real-time temperature deviation signal, enabling stepless adjustment of the flow ratio between the main nozzle 141 and the auxiliary nozzle 142 between 0:100 and 100:0.

[0029] In this embodiment, as Figure 1 , 5 As shown in Figure 6, the main heat exchange unit 2 includes a steam inlet regulating valve 21, a shell-and-tube heat exchanger 22, and a condensate recovery device 23. The shell-side inlet of the shell-and-tube heat exchanger 22 is connected to the bottom of the cylinder 11 through the dye liquor circulation pump 13, and the shell-side outlet is connected to the nozzle assembly 14. The tube-side inlet is connected to an external steam source through the steam inlet regulating valve 21, and the tube-side outlet is connected to the condensate recovery device 23, thereby realizing efficient indirect heat exchange between steam and dye liquor.

[0030] Furthermore, the shell-and-tube heat exchanger 22 adopts a floating head structure, with the heat exchange area ratio of the tube side to the shell side optimized to 1.2:1 to match the heat capacity characteristics of steam condensation and dye liquor heating. The steam inlet regulating valve 21 is an electrically operated proportional regulating valve, which can achieve stepless adjustment of steam flow according to the instructions of the central control processor. The condensate recovery device 23 includes a flash tank 231 and a condensate pump 232. The flash tank 231 has a built-in automatic liquid level control system. When the liquid level reaches the set upper limit, the condensate pump 232 automatically starts; when the liquid level drops to the lower limit, the pump stops. The inlet of the flash tank 231 is connected to the tube-side outlet of the shell-and-tube heat exchanger 22. The steam outlet of the flash tank 231 is connected to the inlet side of the steam inlet regulating valve 21 through a steam circulation pipe, recovering the flash steam in the high-temperature condensate back to the steam system and reducing fresh steam consumption. The inlet of the condensate pump 232 is connected to the liquid water outlet of the flash tank 231. The outlet is connected to the boiler feedwater system, the dye liquor preparation water system and the external discharge pipeline through the water quality diversion valve group. The condensate water is used in a graded manner according to the water quality test results. When the water quality meets the standards, it is given priority for use in boiler feedwater or dye liquor preparation. When the water quality deteriorates, it is discharged into the wastewater treatment system.

[0031] In this embodiment, as Figure 1 , 2 As shown, the multi-stage waste heat recovery unit 3 includes a primary plate heat exchanger 31, a secondary spiral wound tube heat exchanger 32, and a tertiary phase change heat storage heat exchanger 33, which are arranged in series to form a tiered heat exchange network. The high-temperature inlet of the primary plate heat exchanger 31 is connected to the waste liquid discharge pipeline of the dyeing machine body 1, and its high-temperature outlet is connected to the high-temperature inlet of the secondary spiral wound tube heat exchanger 32. Its low-temperature inlet is connected to an external water supply, and its low-temperature outlet is connected to the low-temperature inlet of the secondary spiral wound tube heat exchanger 32. The high-temperature outlet of the secondary spiral wound tube heat exchanger 32 is connected to the high-temperature inlet of the tertiary phase change heat storage heat exchanger 33, and its low-temperature outlet is connected to the low-temperature inlet of the tertiary phase change heat storage heat exchanger 33. The high-temperature outlet of the tertiary phase change heat storage heat exchanger 33 is connected to the wastewater treatment system, and its low-temperature outlet is connected to the inlet of the dye liquor circulation pump 13 via a preheated dye liquor return pipe, realizing the recycling of the preheated dye liquor.

[0032] Furthermore, the waste heat recovery process of the multi-stage waste heat recovery unit 3 is as follows: After the dyeing machine 1 completes dyeing of the same batch of fabric, the high-temperature waste liquid generated is discharged from the waste liquid discharge pipe of the dyeing machine 1 into the primary plate heat exchanger 31, where it undergoes preliminary heat exchange with an external water source. The water source temperature is typically ambient temperature (20℃-25℃), which is raised to 45℃-50℃ after the primary heat exchange and stored in a low-temperature heat storage tank 43 or directly introduced into the secondary spiral wound tube heat exchanger 32 for further heating. The temperature of the waste liquid on the high-temperature side of the primary plate heat exchanger 31 drops from 85℃-90℃ to 55℃-60℃, achieving the first stage of waste heat recovery.

[0033] The cooled waste liquid enters the secondary spiral wound tube heat exchanger 32, where it undergoes deep heat exchange with the preheated water source from the primary heat exchanger. In the complex flow field formed by the spiral wound tube bundle 323, the waste liquid and water source are arranged in counter-current flow. The preheated water source is further heated to 70℃-75℃, meeting the storage temperature requirements of the medium-temperature heat storage tank 42. After the secondary heat exchange, the waste liquid temperature drops to 40℃-45℃ and enters the tertiary phase change heat storage heat exchanger 33 for final waste heat recovery.

[0034] In the three-stage heat exchanger, the low-temperature waste liquid exchanges heat with the phase change heat storage core 332, and stores the remaining heat in the paraffin-based composite phase change material. After absorbing the latent heat, the phase change material changes from solid to liquid, thus achieving high-density heat storage.

[0035] When the system requires preheating of the dye liquor, the ambient temperature replenishment water source or the returned dye liquor exchanges heat with the phase change material in reverse through the heat transfer finned tube 333. The phase change material releases latent heat and returns to a solid state, preheating the water source to 35℃-40℃, completing the closed-loop utilization of waste heat recovery. After the three-stage heat exchange, the temperature of the waste liquid drops to close to the ambient temperature by 25℃-30%, and it is discharged into the wastewater treatment system for further treatment.

[0036] In this embodiment, as Figure 7 , 8 As shown, a leak detection chamber 311 is provided between the high-temperature side flow channel and the low-temperature side flow channel of the primary plate heat exchanger 31. The leak detection chamber 311 is filled with a colorimetric indicator and connected to an optical leak alarm. When the sealing gasket of the plate heat exchanger fails, causing fluid leakage on both sides, the colorimetric indicator changes color, and the optical leak alarm monitors in real time and issues an alarm to prevent cross-contamination between the dye solution and the water source, ensuring dyeing quality and system safety.

[0037] Furthermore, the leak detection chamber 311 is located in the sealed area at the edge of the plate assembly. The color indicator is phenolphthalein ethanol solution, which is colorless under normal conditions. Once a micro-crack leak occurs in the plate, alkaline dye or water seeps into the chamber and triggers a color reaction. The optical leak alarm detects color changes through fiber optic sensing technology, with a response sensitivity of one part per million of concentration change. The alarm signal is transmitted to the central control processor in real time and triggers the shutdown protection program.

[0038] In this embodiment, as Figure 9 , 10 As shown, the two-stage spiral wound tube heat exchanger 32 includes an outer shell 321, a central cylinder 322, and a multi-layer spiral wound tube bundle 323. An annular counter-flow channel is formed between the outer shell 321 and the central cylinder 322. The cross-sectional area of ​​the annular counter-flow channel gradually contracts along the axial direction, causing the fluid velocity to gradually increase, thereby enhancing the turbulence and heat transfer effect. The spiral wound tube bundle 323 is concentrically wound in layers around the central cylinder 322, and the winding directions of adjacent layers of spiral wound tube bundle 323 are opposite, forming a complex secondary flow field, disrupting the thermal boundary layer, improving the heat transfer coefficient, and reducing the equipment volume.

[0039] Furthermore, the outer shell 321 of the two-stage spiral wound tube heat exchanger 32 is a rolled carbon steel cylinder, and the central cylinder 322 is a seamless stainless steel tube. The spiral wound tube bundle 323 consists of four layers, with the diameter increasing sequentially from the inside out. The spirals of adjacent layers form a cross-flow turbulence structure. The cross-sectional area of ​​the annular counter-flow channel gradually decreases from the high-temperature end to the low-temperature end at a ratio of 1.5:1, keeping the fluid velocity relatively stable along the flow path, thus enhancing the heat transfer coefficient while reducing flow resistance.

[0040] In this embodiment, as Figure 11 , 12 As shown, the three-stage phase change heat exchanger 33 includes a shell 331, a phase change heat storage core 332, and heat transfer finned tubes 333. The phase change heat storage core 332 fills the interior of the shell 331 and forms multiple parallel heat storage unit chambers. Each heat storage unit chamber is separated by a heat-conducting baffle 334 to prevent the flow and mixing of the phase change material after melting and to maintain the stability of the heat storage structure.

[0041] Furthermore, the phase change heat storage core 332 of the three-stage phase change heat exchanger 33 is made of paraffin-based composite phase change material, with a phase change temperature range of 58℃-62℃. The heat storage unit chamber has a rectangular cross-section, with 12 groups arranged at equal intervals along the length of the shell 331. The thermally conductive baffle 334 is made of aluminum plate, and its surface is anodized to enhance corrosion resistance. The heat transfer finned tubes 333 penetrate each heat storage unit chamber, and the fins of the heat transfer finned tubes 333 adopt a perforated corrugated structure. The perforated structure promotes lateral mixing of the fluid, and the corrugated structure increases the heat transfer area and induces periodic eddies, significantly improving the heat transfer rate of the phase change heat storage process.

[0042] In this embodiment, as Figure 1 , 13As shown, the heat storage buffer unit 4 includes a high-temperature heat storage tank 41, a medium-temperature heat storage tank 42, and a low-temperature heat storage tank 43, corresponding to the heat energy storage requirements at different temperature levels. The inlet of the high-temperature heat storage tank 41 is selectively connected to the high-temperature side outlet of the primary plate heat exchanger 31 via a first electrically controlled three-way valve 5, and its outlet is selectively connected to the shell-side inlet of the main heat exchange unit 2 via a second electrically controlled three-way valve 6. The inlet of the medium-temperature heat storage tank 42 is selectively connected to the high-temperature side outlet of the secondary spiral wound tube heat exchanger 32 via a third electrically controlled three-way valve 7, and its outlet is selectively connected to either the inlet of the high-temperature heat storage tank 41 or the inlet of the low-temperature heat storage tank 43 via a fourth electrically controlled three-way valve 8, realizing the transfer of heat energy across tanks and the improvement of its quality. The inlet of the low-temperature heat storage tank 43 is selectively connected to the high-temperature side outlet of the three-stage phase change heat storage heat exchanger 33 through the fifth electrically controlled three-way valve 9, and the outlet is selectively connected to the low-temperature side inlet of the two-stage spiral wound tube heat exchanger 32 or the external water source preheating pipeline through the sixth electrically controlled three-way valve 10, forming a flexible heat energy distribution path.

[0043] Furthermore, the low-temperature heat storage tank 43, the medium-temperature heat storage tank 42, and the high-temperature heat storage tank 41 all adopt a vertical cylindrical structure, and each is equipped with a temperature stratification baffle 44 inside. The temperature stratification baffle 44 is a horizontally arranged perforated inclined temperature layer. The inclined temperature layer utilizes the density difference to form a natural temperature stratification, with the high-temperature fluid in the upper layer and the low-temperature fluid in the lower layer. The perforated structure allows for limited vertical flow to balance pressure, while suppressing strong convective mixing, enabling a single tank to store fluids of various temperature grades, improving heat storage density and scheduling flexibility. Among them, the design heat storage temperature of the low-temperature heat storage tank 43 is 40℃-55℃, the medium-temperature heat storage tank 42 is 65℃-80℃, and the high-temperature heat storage tank 41 is 85℃-95℃. The effective volume ratio of the three is optimized to 3:2:1 to match the differentiated requirements of heat energy grade and quantity at different operating stages of the dyeing machine.

[0044] In this embodiment, the intelligent temperature control unit includes a temperature sensor, a dye liquor flow monitoring module, a steam pressure regulating module, and a central control processor. The temperature sensor is distributed in the cylinder 11, the guide pipe 12, the inlet and outlet of each heat exchanger, and inside the heat storage tank, for real-time monitoring of the temperature of the dye liquor and the recovered heat. The dye liquor flow monitoring module is located at the junction of the outlet pipe of the dye liquor circulation pump 13 and the preheated dye liquor return pipe, accurately measuring the total flow rate entering the main heat exchange unit 2 and the distribution ratio of each branch. The steam pressure regulating module is electrically connected to the steam inlet regulating valve 21, automatically adjusting the steam supply pressure and flow rate according to the heat load requirements. The central control processor is connected to the temperature sensor, the dye liquor flow monitoring module, the steam pressure regulating module, the dye liquor circulation pump 13, and each electrically controlled three-way valve, achieving coordinated and optimized operation of the entire system based on a preset control algorithm.

[0045] Furthermore, the temperature sensor employs a Pt100 platinum resistance element, with 12 measuring points arranged at key nodes in the dye liquor circulation pipeline, including the inlet and outlet of cylinder 11, the inlet and outlet of the main heat exchanger, the inlet and outlet of each stage of waste heat recovery unit, and the upper, middle, and lower layers of the heat storage tank. The dye liquor flow monitoring module uses a Coriolis mass flow meter to directly measure the mass flow rate and simultaneously acquire fluid density information, providing accurate data for heat load calculation. The central control processor is an industrial-grade PLC system, equipped with a 16-bit analog input module and a high-speed counting module, supporting PID self-tuning and fuzzy control algorithms, and can optimize control parameters based on historical operating data.

[0046] Based on the above system structure, the thermal energy management method for the dyeing machine in this embodiment includes the following detailed steps: S1. Heat Balance Establishment: The central control processor receives process parameters input by the operator, such as the target dye liquor temperature, heating rate, holding time, and cooling curve. Simultaneously, it collects signals from the level and temperature sensors of each heat storage tank, calculating the matching relationship between the currently available heat storage and the target heat load. Based on the heat balance equation Qtotal = Qheat storage + Qsteam, where Qheat storage is the heat that can be released from the heat storage tank, and Qsteam is the heat that needs to be supplemented with steam, the initial heat load allocation strategy is optimized to determine the initial opening of the steam inlet regulating valve 21, the initial frequency of the dye liquor circulation pump 13, and the initial state of each electrically controlled three-way valve. If the available heat in the heat storage tank is sufficient to cover more than 60% of the heat load during the heating phase, the heat storage preheating mode is prioritized to shorten the response delay of the steam system.

[0047] S2. Heating Stage Heat Energy Distribution: The dye liquor circulation pump 13 starts operating at a set frequency, pumping the dye liquor, which is at room temperature or residual temperature from the previous batch, from the bottom of the cylinder 11 to the main heat exchange unit 2. After being heated to near the target temperature by the shell-and-tube heat exchanger 22, it is injected into the guide pipe 12 at a higher injection pressure through the main nozzle 141. During this stage, the nozzle switching valve group 143 adjusts the opening of the main nozzle 141 to 100% and the auxiliary nozzle 142 is completely closed to ensure that the dye liquor has sufficient kinetic energy to penetrate the fabric layer and achieve uniform penetration. The temperature sensor monitors the fabric surface temperature and the main body temperature of the dye liquor at a sampling frequency of 10 times per second. The central control processor adopts a feedforward-feedback composite control algorithm. The feedforward link pre-adjusts the steam valve opening according to the set value of the heating rate, and the feedback link performs PID fine-tuning based on the deviation between the measured temperature and the set curve, dynamically adjusting the steam valve opening and pump frequency to ensure that the root mean square error between the actual heating curve and the set value does not exceed 2 degrees Celsius.

[0048] S3. Multi-stage Waste Heat Recovery and Storage: Waste liquid generated during the later stages of heating and heat preservation sequentially enters the multi-stage waste heat recovery unit 3. High-temperature waste liquid with a temperature above 85 degrees Celsius first enters the primary plate heat exchanger 31, where it undergoes counter-current heat exchange with an externally supplied ambient temperature water source, preheating the water source to 55-65 degrees Celsius. After heat exchange, the waste liquid temperature drops to approximately 70 degrees Celsius, and part of the preheated water source directly enters the low-temperature heat storage tank 43 for storage. Medium-temperature waste liquid with a temperature of approximately 70 degrees Celsius enters the secondary spiral wound tube heat exchanger 32, where it undergoes secondary heat exchange with fluid from the low-temperature heat storage tank 43 or an external water source, heating the fluid to 75-85 degrees Celsius. The heated fluid is then guided to the medium-temperature heat storage tank 42 for storage, or, depending on temperature matching requirements, continues to the tertiary heat exchanger. Low-temperature waste liquid at approximately 55 degrees Celsius enters the three-stage phase change heat exchanger 33, utilizing the latent heat characteristics of the phase change material to achieve high-density heat storage and stable output. The output fluid temperature is controlled between 45 and 50 degrees Celsius before being discharged into the wastewater treatment system. When the liquid level in the medium-temperature heat storage tank 42 reaches the upper limit or the temperature exceeds the set value, the central control processor controls the fourth electrically controlled three-way valve 8 to transfer excess heat energy to the high-temperature heat storage tank 41 for storage, realizing cross-tank distribution of heat storage.

[0049] S4. Low-energy operation during the heat preservation stage: After the dye liquor temperature reaches the target value and enters the heat preservation stage, the central control processor gradually reduces the frequency of the dye liquor circulation pump 13 to 30% to 50% of the normal operating frequency, closes or slightly opens the steam inlet regulating valve 21 to maintain heat loss compensation, and simultaneously switches to the auxiliary nozzle 142 mode. The preheated dye liquor is directly introduced into the auxiliary nozzle 142 from the low-temperature side outlet of the three-stage phase change heat exchanger 33 or the medium-temperature heat storage tank 42, maintaining dye liquor circulation and temperature stability with a lower injection pressure. This mode uses recovered low-grade heat energy to replace high-grade steam, and the measured steam consumption during the heat preservation stage can be reduced by more than 75%.

[0050] S5. Heat Transfer and Recovery During Cooling: During the cooling phase after the dyeing process, the combined nozzle mode is activated. The central control processor calculates the flow ratio of the main nozzle 141 and the auxiliary nozzle 142 according to the set cooling curve, and opens the main nozzle 141 and the auxiliary nozzle 142 proportionally. The main nozzle 141 injects dye liquor that has been moderately heated by the main heat exchange unit 2, and the auxiliary nozzle 142 injects low-temperature preheated dye liquor from the heat storage system. The two mix in the guide pipe 12 to form a dye liquor temperature that meets the requirements of gradient cooling. The dye liquor circulation pump 13 switches to high-frequency operation mode, quickly transferring the heat carried by the cylinder 11 and the fabric to the dye liquor, and introducing it into the multi-stage waste heat recovery unit 3 through the circulation loop to maximize the recovery of process waste heat to the heat storage system, storing thermal energy for the next batch of production.

[0051] S6. Shutdown Maintenance and Safety Monitoring: After the production batch ends and the system shuts down, the central control processor executes the pressure-holding procedure for the heat storage tank, closes all electrically controlled three-way valves, and activates the tank's insulation to maintain the temperature of the heat storage medium until the next startup. Simultaneously, the system enters leak monitoring mode, and the optical leak alarm continues to run. If a leak signal is detected in the primary plate heat exchanger 31, an emergency shutdown is immediately triggered, and the dye liquor isolation procedure is initiated. During regular maintenance, the system supports forced cooling and venting of the heat storage tank, as well as chemical cleaning procedures for each heat exchanger, ensuring long-term heat exchange efficiency.

[0052] In summary, this embodiment, through the synergistic effect of the above-mentioned system structure and method, achieves an increase in the thermal energy utilization rate of the dyeing machine from 35% to 45% of traditional equipment to 78% to 85%, a waste heat recovery efficiency of over 92%, and a reduction in steam consumption by 40% to 50%. At the same time, it significantly improves temperature control accuracy and process stability, demonstrating significant energy-saving and emission-reduction benefits and promotional application value.

[0053] The embodiments described in this specific implementation are preferred embodiments of this application and are not intended to limit the scope of protection of this application. Identical components are represented by the same reference numerals. Therefore, all equivalent changes made to the structure, shape, and principle of this application should be included within the scope of protection of this application.

Claims

1. A thermal energy management system for a dyeing machine based on multi-stage heat exchange, comprising a dyeing machine body, a main heat exchange unit, a multi-stage waste heat recovery unit, and a heat storage buffer unit, characterized in that, The main body of the dyeing machine includes a cylinder, a guide pipe, a dye liquor circulation pump, and a nozzle assembly. The inside of the cylinder forms a fabric circulation channel, and the guide pipe is connected to both ends of the cylinder and forms a dye liquor spraying circuit with the nozzle assembly. The dye liquor circulation pump is located in the pipeline between the bottom outlet of the cylinder and the main heat exchange unit. The main heat exchange unit includes a steam inlet regulating valve, a shell-and-tube heat exchanger, and a condensate recovery device. The shell-side inlet of the shell-and-tube heat exchanger is connected to the bottom of the shell body through a dye liquor circulation pump, and the shell-side outlet is connected to a nozzle assembly. The tube-side inlet of the shell-and-tube heat exchanger is connected to an external steam source through a steam inlet regulating valve, and the tube-side outlet is connected to a condensate recovery device. The multi-stage waste heat recovery unit includes a primary plate heat exchanger, a secondary spiral wound tube heat exchanger, and a tertiary phase change heat storage heat exchanger. The high-temperature inlet of the primary plate heat exchanger is connected to the waste liquid discharge pipeline of the dyeing machine body, and the high-temperature outlet is connected to the high-temperature inlet of the secondary spiral wound tube heat exchanger. The low-temperature inlet of the primary plate heat exchanger is connected to an external water supply, and the low-temperature outlet is connected to the low-temperature inlet of the secondary spiral wound tube heat exchanger. The high-temperature outlet of the secondary spiral wound tube heat exchanger is connected to the high-temperature inlet of the tertiary phase change heat storage heat exchanger, and the low-temperature outlet is connected to the low-temperature inlet of the tertiary phase change heat storage heat exchanger. The high-temperature outlet of the tertiary phase change heat storage heat exchanger is connected to the wastewater treatment system, and the low-temperature outlet is connected to the inlet of the dye liquor circulation pump through a preheated dye liquor return pipe. The heat storage buffer unit includes a high-temperature heat storage tank, a medium-temperature heat storage tank, and a low-temperature heat storage tank. The inlet of the high-temperature heat storage tank is selectively connected to the high-temperature side outlet of the first-stage plate heat exchanger via a first electrically controlled three-way valve, and the outlet is selectively connected to the shell-side inlet of the main heat exchange unit via a second electrically controlled three-way valve. The inlet of the medium-temperature heat storage tank is selectively connected to the high-temperature side outlet of the second-stage spiral wound tube heat exchanger via a third electrically controlled three-way valve, and the outlet is selectively connected to the inlet of either the high-temperature heat storage tank or the low-temperature heat storage tank via a fourth electrically controlled three-way valve. The inlet of the low-temperature heat storage tank is selectively connected to the high-temperature side outlet of the third-stage phase change heat storage heat exchanger via a fifth electrically controlled three-way valve, and the outlet is selectively connected to the low-temperature side inlet of the second-stage spiral wound tube heat exchanger or an external water source preheating pipeline via a sixth electrically controlled three-way valve.

2. The thermal energy management system for a dyeing machine based on multi-stage heat exchange as described in claim 1, characterized in that, Multiple heat exchange tube bundles are embedded in the inner wall of the guide tube. The multiple heat exchange tube bundles are circumferentially distributed in the cavity of the guide tube. One end of the heat exchange tube bundle is connected to the bottom outlet of the cylinder through the dye liquor circulation pump, and the other end is connected to the shell-side outlet of the main heat exchange unit through a one-way valve.

3. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, The nozzle assembly includes a main nozzle, an auxiliary nozzle, and a nozzle switching valve group. The main nozzle is connected to the shell-side outlet of the main heat exchange unit, and the auxiliary nozzle is connected to the low-temperature side outlet of the three-stage phase change heat storage heat exchanger through a preheating dye liquor branch. The nozzle switching valve group controls the individual or combined activation of the main nozzle and the auxiliary nozzle according to the operating stage of the dyeing machine.

4. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, A leak detection chamber is provided between the high-temperature side channel and the low-temperature side channel of the primary plate heat exchanger. The leak detection chamber is filled with a colorimetric indicator and connected to an optical leak alarm.

5. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, The two-stage spiral wound tube heat exchanger includes an outer shell, a central cylinder, and multiple layers of spiral wound tube bundles. An annular counterflow channel is formed between the outer shell and the central cylinder. The cross-sectional area of ​​the annular counterflow channel gradually shrinks along the axial direction. The spiral wound tube bundles are concentrically wound in layers with the central cylinder as the axis, and the winding directions of adjacent layers of spiral wound tube bundles are opposite.

6. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, The three-stage phase change heat exchanger includes a shell, a phase change heat storage core, and heat transfer finned tubes. The phase change heat storage core is filled inside the shell and forms multiple parallel heat storage unit chambers. Each heat storage unit chamber is separated by a heat-conducting baffle. The heat transfer finned tubes penetrate each heat storage unit chamber, and the fins are perforated corrugated fins.

7. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, The high-temperature heat storage tank, the medium-temperature heat storage tank, and the low-temperature heat storage tank are all equipped with temperature stratification partitions inside, and the temperature stratification partitions are horizontally arranged perforated inclined temperature stratification plates.

8. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, The condensate recovery device includes a flash tank and a condensate pump. The inlet of the flash tank is connected to the tube-side outlet of the shell-and-tube heat exchanger, and the steam outlet of the flash tank is connected to the inlet side of the steam inlet regulating valve through a steam circulation pipeline. The inlet of the condensate pump is connected to the liquid water outlet of the flash tank, and the outlet is connected to the boiler feedwater system, the dye liquor preparation water system, and the external discharge pipeline through a water quality diversion valve group.

9. The thermal energy management system for a dyeing machine based on multi-stage heat exchange according to claim 1, characterized in that, It also includes an intelligent temperature control unit, which comprises: Temperature sensor used to monitor dye liquor temperature and recovered heat temperature in real time; A dye liquor flow monitoring module is installed at the junction of the outlet pipeline of the dye liquor circulation pump and the preheated dye liquor return pipeline. A steam pressure regulating module, which is electrically connected to a steam inlet regulating valve; The central control processor is connected to the temperature sensor, the dye liquor flow monitoring module, the steam pressure regulating module, the dye liquor circulation pump, and each electrically controlled three-way valve.

10. A method for using a thermal energy management system for a dyeing machine based on multi-stage heat exchange as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Heat balance establishment: The central control processor receives parameters such as target dye liquor temperature, heating rate, holding time and cooling curve, and calculates the initial heat load distribution strategy based on the liquid level and temperature status of the heat storage tank. S2. Heat energy distribution during the heating stage: The dye liquor circulation pump operates at a set frequency, pumping the dye liquor from the bottom of the cylinder to the main heat exchange unit. After being heated by the shell-and-tube heat exchanger, it is injected into the guide pipe through the main nozzle. The temperature sensor monitors the temperature of the fabric and the dye liquor in real time. The central control processor adjusts the opening of the steam valve and the pump frequency according to the feedback deviation to ensure that the heating curve meets the set requirements. S3. Multi-stage waste heat recovery and heat storage: The first-stage plate heat exchanger uses high-temperature waste liquid to preheat and replenish the water source, and part of it is stored in the low-temperature heat storage tank; the medium-temperature waste liquid is heated to the water source again by the second-stage spiral wound tube heat exchanger, and the heated water source is led to the medium-temperature heat storage tank or continues to the third-stage heat exchange; the low-temperature waste liquid is heated by the third-stage phase change heat storage heat exchanger; when the medium-temperature heat storage tank is at full load, the heat energy is transferred to the high-temperature heat storage tank for storage through the fourth electrically controlled valve; S4. Low-energy operation during the heat preservation stage: After reaching the target temperature, reduce the frequency of the dye liquor circulation pump, close or slightly open the steam valve, and switch to the auxiliary nozzle mode; preheat the dye liquor and directly introduce it into the auxiliary nozzle to maintain circulation and temperature stability with low injection pressure. S5. Heat transfer and recovery during cooling stage: Start the combined nozzle mode, open the main / auxiliary nozzles in proportion, and inject heated dye liquor and low-temperature preheated dye liquor respectively, mix to form a gradient cooling; the dye liquor circulation pump runs at high frequency to transfer the heat of the cylinder to the waste heat recovery unit. S6. Shutdown maintenance and safety monitoring: After shutdown, execute the heat storage tank pressure holding procedure, close all electrically controlled three-way valves and maintain the heat insulation state to store heat energy for the next startup.

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