CNG loading station energy-saving system and method based on deep coupling utilization of cold energy

Abstract

The present invention relates to the technical field of heat exchangers, and in particular to an energy-saving system and method for a CNG loading station based on deep coupling utilization of cold energy, comprising a heat exchange device, the heat exchange device comprising a shell side portion, and a front head and a rear head are respectively arranged at both ends of the shell side portion; the shell side portion comprises a shell, and tube sheets are arranged at both ends of the shell, and heat exchange tubes are arranged between the two tube sheets, and array-distributed baffle devices are arranged on the outside of the heat exchange tubes; the shell comprises a low-temperature zone and a high-temperature zone, and telescopic devices are respectively installed between the baffle devices located in the low-temperature zone and the baffle devices located in the high-temperature zone to adjust the plate spacing between adjacent baffle devices; a liquid inlet and a liquid outlet are arranged on the outside of the shell; the present invention judges the heat transfer efficiency between natural gas and high-temperature water in real time by monitoring the temperature difference at both ends of the heat exchange tube and the pressure drop value of the shell, and controls the telescopic device and the pusher to make corresponding structural changes according to the heat transfer efficiency to balance the temperature difference at both ends of the heat exchange tube and the pressure drop of the shell.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a CNG loading station energy-saving system and method based on deep coupling utilization of cold energy. Background Art

[0002] The CNG (compressed natural gas) decompression skid process is a process of converting high-pressure CNG into medium-pressure or low-pressure CNG to meet different application requirements. During the decompression process, high-pressure CNG flows out of the gas tank and enters the pressure reducer. The function of the pressure reducer is to reduce the pressure of CNG to medium-pressure or low-pressure levels, and the outlet pressure can be adjusted to send CNG to the next stage of the step-by-step decompression process. Step-by-step decompression gradually reduces the pressure of CNG through multi-stage pressure reducers to ensure a gradual transition from high pressure to medium pressure or low pressure, and prevent excessive pressure drop from causing damage to equipment and pipelines.

[0003] During the CNG decompression process, when high-pressure natural gas passes through the throttle port of the pressure reducing valve, the pressure drop is large and the speed is fast. The pressure, density and temperature of the natural gas parameters all change. The volume expansion loses energy when passing through the valve port, and the temperature change causes heat exchange between the natural gas and the surrounding wall. However, the heat exchange rate is much smaller than the change in the flow rate of the natural gas, and this process can be approximately regarded as an adiabatic process. Since adiabatic throttling is not a reversible adiabatic process, and the main component of natural gas is methane, and it also contains a small amount of ethane, propane, butane and inert gases, if the water content in the hydrocarbon exceeds a certain content, under certain temperature and pressure conditions, water can react with liquid and gaseous hydrocarbons to form crystalline hydrates, similar to ice or dense snow, causing the pipeline to freeze. Therefore, during the decompression of compressed natural gas, a dedicated heat exchanger should be set up to provide heat for the natural gas, but the existing heat exchanger has an unstable heating temperature and low working efficiency during the heating of compressed natural gas.

[0004] The Chinese patent application number CN201420598231.2 discloses a heat exchanger for a compressed natural gas pressure reducing device, including a heat exchanger housing, a primary heat exchange coil and a secondary heat exchange coil are installed in the heat exchanger housing, the natural gas to be reduced in pressure is first introduced into the primary heat exchange coil, the natural gas after primary heating is connected to the external primary pressure reducing device through the air guide pipe, the reduced pressure natural gas then enters the secondary heat exchange coil through the air guide pipe, and the natural gas after secondary heating is connected to the external secondary pressure reducing device through the air guide pipe for pressure reduction. The upper end of the heat exchanger housing is equipped with measuring instruments such as a thermometer, a temperature transmitter and a liquid level gauge to monitor the liquid level and temperature of the hot water in the heat exchanger housing. A support leg is installed at the lower end of the heat exchanger housing for easy installation and transportation. The hot water in the heat exchanger housing can be heated by an electric heater, or connected to an external boiler through a connecting pipe, and the external boiler provides circulating hot water.

[0005] Although the above-mentioned device can heat the compressed natural gas through the heat exchanger and effectively alleviate the icing problem that may be caused during the pressure reduction process, in the process of heating the natural gas by the heat exchanger, a significant temperature difference will be generated at both ends of the heat exchange tube. The temperature difference stress caused by this makes it easy for the connection between the heat exchange tube and the tube sheet to be pulled apart and broken, thereby increasing the risk of compressed natural gas leakage from the joint between the heat exchange tube and the tube sheet.

[0006] In addition, when a shell and tube heat exchanger is used to heat compressed natural gas, after the shell-side fluid flows through the circular area of ​​the arched baffle, a vortex area will be formed on the back of the baffle. In this area, the fluid flow is relatively stagnant, causing the shell-side fluid temperature to quickly reach equilibrium with the surface temperature of the outer wall of the heat exchange tube. Since the fluid in this area is almost stationary, heat accumulates here and is difficult to transfer to the downstream area in time, so the heat transfer effect in this area is extremely poor, which is called the "heat transfer dead zone". The existence of the heat transfer dead zone not only limits the effective utilization of the heat exchange area of ​​the shell and tube heat exchanger, but also significantly affects its heat transfer efficiency. At the same time, this area is prone to accumulation of dirt, which further aggravates the reduction of heat transfer efficiency.

[0007] In view of this, there is an urgent need for a CNG loading station energy-saving system and method based on deep coupling utilization of cold energy to solve the above-mentioned technical problems. Summary of the invention

[0008] The object of the present invention is to provide a CNG loading station energy-saving system and method based on deep coupling utilization of cold energy, so as to solve the technical problems raised in the above-mentioned background technology.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A CNG loading station energy-saving system based on deep coupling utilization of cold capacity, comprising a primary heat exchanger, a primary voltage regulator, a primary filter, a secondary heat exchanger, a secondary voltage regulator, and a secondary filter connected in sequence through a connecting pipeline;

[0011] The primary heat exchanger and the secondary heat exchanger include a shell-and-tube heat exchange device, the heat exchange device includes a shell-side portion for performing gas-liquid mass transfer operations, and the two ends of the shell-side portion are respectively provided with a front head and a rear head;

[0012] The shell side part includes a shell, both ends of the shell are provided with tube sheets, a heat exchange tube for CNG circulation is provided between the two tube sheets, an array of baffles are provided on the outer side of the heat exchange tube, the baffles include a circumferential plate, the circumferential plate is provided with a through hole for the heat exchange tube to pass through, the circumferential plate is provided with a notch for fluid to pass through, and the notch is provided with an adjusting member for sealing the notch;

[0013] The adjusting member comprises a limiting groove formed on the circumferential plate, a movable plate is arranged inside the limiting groove, and pushing members are arranged on both sides of the movable plate. The pushing members drive the movable plate to move up and down along the limiting groove and seal the notch.

[0014] Preferably, the heat exchange device is equipped with a water inlet and a water outlet, the water outlet of the primary heat exchanger is connected to the water inlet of the secondary heat exchanger, the water outlet of the secondary heat exchanger is connected to the water inlet of the low-temperature side of the cold storage tank, the water outlet of the low-temperature side of the cold storage tank is connected to the water inlet of the CNG compressor, the water outlet of the CNG compressor is connected to the water inlet of the high-temperature side of the cold storage tank, and the water outlet of the high-temperature side of the cold storage tank flows back to the water inlet of the primary heat exchanger to form a closed cycle.

[0015] Preferably, a primary filter is provided between the primary heat exchanger and the secondary heat exchanger, and the primary filter performs preliminary filtration on the compressed natural gas entering the secondary heat exchanger. A secondary filter is provided between the secondary heat exchanger and the urban pipeline network, and the secondary filter performs secondary filtration on the compressed natural gas entering the urban pipeline network.

[0016] Preferably, a primary purifier is provided between the water outlet of the primary heat exchanger and the water inlet of the secondary heat exchanger, and the primary purifier intercepts fluid impurities entering the secondary heat exchanger. A secondary purifier is provided between the water outlet of the secondary heat exchanger and the cold storage tank, and the secondary purifier intercepts impurities entering the cold storage tank.

[0017] Preferably, the baffle device blocks the fluid entering the housing so that the flow direction of the fluid is in a "W" shape;

[0018] The shell includes a low temperature zone and a high temperature zone, and telescopic devices are respectively installed between the baffles located in the low temperature zone and the baffles located in the high temperature zone to adjust the plate spacing between adjacent baffles;

[0019] The outer side of the shell is provided with a liquid inlet equivalent to the water inlet, and a liquid outlet equivalent to the water outlet.

[0020] Preferably, the front head portion includes a cover body, and a partition plate is provided inside the cover body, and the partition plate divides the cover body into two upper and lower areas;

[0021] An air inlet and an air outlet are arranged on the outer side of the cover body. The air inlet is connected to the upper half of the cover body, and the air outlet is connected to the lower half of the cover body.

[0022] Preferably, a swelling portion is provided on a side of the circumferential plate facing the occipital region, and when the area between two adjacent circumferential plates is in a sealed state, the plate spacing between the two circumferential plates is enlarged and the swelling portion is expanded.

[0023] Preferably, the expansion portion comprises a hollow groove opened on the circumferential plate, and an elastic membrane is arranged in the hollow groove.

[0024] Preferably, the end of the heat exchange tube is connected to the tube sheet through a compensation device, and the compensation device includes a fixed plate arranged on the tube sheet, a telescopic tube is provided on the fixed plate, a mounting plate is provided at the end of the telescopic tube, and a limiting movable part is provided between the mounting plate and the fixed plate.

[0025] The present invention also provides an energy-saving method for a CNG loading station energy-saving system based on deep coupling utilization of cold energy, the energy-saving method comprising the following steps:

[0026] S1, preliminary heating and filtering stage: First, the compressed natural gas is introduced into the primary heat exchanger for preliminary heating. After the heating is completed, it is depressurized by the primary pressure regulator and enters the primary filter for preliminary impurity removal;

[0027] S2, secondary heating and fine filtration stage: After the initial filtration, the compressed natural gas enters the secondary heat exchanger for secondary heating treatment, and then further reduces the pressure through the secondary pressure regulator, enters the secondary filter for secondary filtration, and finally transports the purified natural gas to the city pipeline network;

[0028] S3, cold energy recovery and reuse stage: Based on S1 and S2, the high-temperature water in the upper part of the cold storage tank is used to exchange heat with the low-temperature natural gas in the primary heat exchanger and the secondary heat exchanger. The high-temperature water after heat exchange flows to the lower part of the cold storage tank to reduce the water temperature in the lower part; at the same time, the low-temperature water in the lower part of the cold storage tank is used to cool the CNG compressor, and the generated high-temperature water flows back to the upper part of the cold storage tank for cold energy recovery and reuse cycle;

[0029] S4, heat exchange efficiency optimization stage: Based on S3, by monitoring the temperature difference and pressure drop changes inside the heat exchanger, using the dynamic adjustment of the control adjustment parts and telescopic devices, the heat exchange process between natural gas and high-temperature water is optimized according to the needs under different working conditions to ensure that the heat exchange is more sufficient and efficient.

[0030] Technical effects and advantages of the present invention:

[0031] 1. The present invention realizes the gradual heating of compressed natural gas through the series use of the primary heat exchanger and the secondary heat exchanger, and the circulating water system of the cold storage box and the heat exchanger, which significantly improves the heat exchange efficiency. At the same time, through the design of the circumferential plate and the notch, a "W"-shaped fluid flow path is formed in the shell, which increases the contact area and turbulence between the fluid and the heat exchange tube, thereby enhancing the heat exchange effect.

[0032] 2. The present invention can determine the heat transfer efficiency between natural gas and high-temperature water in real time by monitoring the temperature difference at both ends of the heat exchange tube and the pressure drop of the shell, and control the telescopic device and the pusher to make corresponding structural changes according to the heat transfer efficiency to balance the temperature difference at both ends of the heat exchange tube and the pressure drop of the shell; when the temperature difference exceeds the preset threshold, the plate spacing between the circumferential plates can be adjusted to effectively balance the temperature difference at both ends of the heat exchange tube and avoid connection damage caused by temperature difference stress; when the pressure drop exceeds the set state, the plate spacing between the circumferential plates is expanded by synchronously extending the telescopic devices located on the low-temperature side and the high-temperature side of the shell, thereby reducing the fluid resistance in the shell, thereby maintaining the stable flow of the fluid and reducing the pressure drop.

[0033] 3. The present invention uses a movable plate on the circumferential plate in conjunction with a pusher, and can automatically clean the scale on the heat exchange tube and the inner wall of the shell under the drive of the telescopic device, thereby avoiding the influence of scale on the heat transfer effect and fluid resistance; at the same time, through the combined design of the elastic membrane and the circumferential plate, the stress structure of the scale can be destroyed by the negative pressure and the expansion effect of the elastic membrane when cleaning the scale, so that the scale is easier to fall off and be washed away by the water flow.

[0034] 4. The present invention arranges compensation devices at both ends of the heat exchange tube. When the heat exchange tube generates stress stretching due to temperature difference, the telescopic tube can compensate and buffer the stress stretching of the heat exchange tube, thereby avoiding the pulling-off and rupture phenomenon at the connection between the heat exchange tube and the tube sheet, thereby ensuring the safe transmission of compressed natural gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the system distribution structure of the present invention;

[0036] Figure 2 It is a schematic structural diagram of the heat exchange device of the present invention;

[0037] Figure 3 It is a schematic diagram of the internal structure of the housing of the present invention;

[0038] Figure 4 It is a schematic diagram of the internal structure of the housing of the present invention from another perspective;

[0039] Figure 5 This is a schematic diagram of the working principle of the heat exchange device of the present invention;

[0040] Figure 6 It is a schematic diagram of the connection structure between the tube sheet and the heat exchange tube of the present invention;

[0041] Figure 7 It is a structural schematic diagram of the baffle device of the present invention;

[0042] Figure 8 It is a schematic diagram of the connection between the telescopic device and the baffle device of the present invention;

[0043] Fig. 9 For the present invention Figure 8 A schematic diagram of the enlarged structure at A in the middle;

[0044] Fig.10 It is a structural schematic diagram of the adjusting member of the present invention;

[0045] Fig.11 It is a schematic diagram of the structure of the compensation device of the present invention.

[0046] The accompanying drawings are marked as follows: 1. heat exchange device; 101. shell side; 1011. shell; 1012. tube sheet; 1013. heat exchange tube; 1014. liquid inlet; 1015. liquid outlet; 102. front head; 1021. cover; 1022. partition plate; 1023. air inlet; 1024. air outlet; 103. rear head; 2. baffle device; 201. circumferential plate; 202. perforation; 203. notch; 204. adjusting member; 2041. limit groove; 2042. movable plate; 2043. push member ; 205, expansion part; 2051, empty groove; 2052, elastic membrane; 3, telescopic device; 4, compensation device; 401, fixed plate; 402, telescopic tube; 403, mounting plate; 404, limiting movable part; 100, primary heat exchanger; 1001, primary filter; 1002, primary voltage regulator; 1003, primary purifier; 200, secondary heat exchanger; 2001, secondary filter; 2002, secondary voltage regulator; 2003, secondary purifier; 300, cold storage box; 400, CNG compressor. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] Embodiment 1

[0049] Reference Figure 1 As shown, a CNG loading station energy-saving system based on deep coupling utilization of cold energy includes a primary heat exchanger 100, a primary voltage regulator 1002, a primary filter 1001, a secondary heat exchanger 200, a secondary voltage regulator 2002, and a secondary filter 2001 which are sequentially connected through connecting pipes.

[0050] The 20MPa compressed natural gas is first heated by the primary heat exchanger 100, and then enters the secondary heat exchanger 200 for secondary heating after the initial pressure reduction by the primary pressure regulator 1002. After that, the pressure is reduced to 0.4MPa through the secondary pressure reduction by the secondary pressure regulator 2002, and can enter the urban pipeline network.

[0051] The primary heat exchanger 100 and the secondary heat exchanger 200 include a shell and tube heat exchange device 1, which is equipped with a water inlet and a water outlet. The water outlet of the primary heat exchanger 100 is connected to the water inlet of the secondary heat exchanger 200, and the water outlet of the secondary heat exchanger 200 is connected to the water inlet of the low-temperature side of the cold storage tank 300. The water outlet of the low-temperature side of the cold storage tank 300 is connected to the water inlet of the CNG compressor 400, and the water outlet of the CNG compressor 400 is connected to the water inlet of the high-temperature side of the cold storage tank 300. The water outlet of the high-temperature side of the cold storage tank 300 flows back to the water inlet of the primary heat exchanger 100 to form a closed cycle.

[0052] Reference Figure 1 As shown, a primary filter 1001 is provided between the primary heat exchanger 100 and the secondary heat exchanger 200, and the primary filter 1001 performs preliminary filtration on the compressed natural gas entering the secondary heat exchanger 200. A secondary filter 2001 is provided between the secondary heat exchanger 200 and the urban pipeline network, and the secondary filter 2001 performs secondary filtration on the compressed natural gas entering the urban pipeline network.

[0053] Reference Figure 1 As shown, a primary purifier 1003 is provided between the water outlet of the primary heat exchanger 100 and the water inlet of the secondary heat exchanger 200, and the primary purifier 1003 intercepts fluid impurities entering the secondary heat exchanger 200. A secondary purifier 2003 is provided between the water outlet of the secondary heat exchanger 200 and the cold storage tank 300, and the secondary purifier 2003 intercepts fluid impurities entering the cold storage tank 300.

[0054] It should be noted that the water level of the cold storage box 300 needs to make the water in the cold storage box 300 produce a cold and hot stratification effect. Preferably, the water level of the cold storage box 300 is not less than 2.5 m.

[0055] When in use, compressed natural gas (CNG) with a set pressure of 20 MPa is first introduced into the primary heat exchanger 100, and the primary heat exchanger 100 preliminarily heats the compressed natural gas. Subsequently, the preheated compressed natural gas flows through the primary pressure regulator 1002 to achieve the first pressure reduction. The compressed natural gas after the initial pressure reduction is transmitted to the primary filter 1001 through a connecting pipeline. The primary filter 1001 is intended to remove initial impurities in the compressed natural gas.

[0056] The compressed natural gas processed by the primary filter 1001 continues to flow to the secondary heat exchanger 200, which performs secondary heating on the compressed natural gas. After the secondary heating is completed, the compressed natural gas undergoes a second pressure reduction through the secondary pressure regulator 2002. Finally, the compressed natural gas flows into the secondary filter 2001 for more refined impurity removal.

[0057] During the heating process of compressed natural gas by the primary heat exchanger 100 and the secondary heat exchanger 200, the high-temperature water in the upper part of the cold storage tank 300 enters the primary heat exchanger 100 through the water inlet, and the high-temperature water exchanges heat with the low-temperature compressed natural gas. The water after heat exchange continues to flow to the secondary heat exchanger 200 after being purified by the primary purifier 1003, and the water entering the secondary heat exchanger 200 exchanges heat with the compressed natural gas for the second time. The water after the secondary heat exchange continues to flow to the lower part of the cold storage tank 300 after being purified by the secondary purifier 2003, thereby reducing the water temperature in the lower part of the cold storage tank 300. The low-temperature water in the lower part of the cold storage tank 300 is used to cool the CNG compressor 400, and the high-temperature water in the compressor cylinder returns to the upper part of the cold storage tank 300 through the water pump. Afterwards, this part of water is transported to the primary heat exchanger 100 again to achieve the heating of the compressed natural gas, forming a circulation system.

[0058] Embodiment 2

[0059] Although the above-mentioned embodiments can alleviate the freezing phenomenon of compressed natural gas during the decompression process to a certain extent, during the use of the system, when the heat exchange device 1 heats the compressed natural gas, a significant temperature difference will appear at both ends of the heat exchange tube 1013, causing the connection between the heat exchange tube 1013 and the tube sheet 1012 to be affected by the temperature difference stress, which is prone to pull-off and rupture, increasing the risk of natural gas leakage. In addition, after the fluid flows through the notch of the arched baffle, a heat transfer dead zone will be formed on the back side of the baffle. The existence of the heat transfer dead zone not only reduces the effective utilization of the heat exchange area, but also significantly affects the heat transfer efficiency. Dirt is easily accumulated in the heat transfer dead zone, further aggravating the decrease in heat transfer efficiency. In view of this, technical improvements are made on the basis of Example 1.

[0060] Reference Figures 1 to 11 As shown, the heat exchange device 1 includes a shell portion 101 for performing gas-liquid mass transfer operations, and a front head 102 and a rear head 103 are respectively provided at both ends of the shell portion 101.

[0061] The high temperature water flows in the shell part 101 in a "W" shape. The compressed natural gas flows in a "U" shape between the front head 102, the shell part 101 and the rear head 103. The high temperature water performs heat exchange on the compressed natural gas flowing through the heat exchange tubes 1013.

[0062] The shell part 101 includes a shell 1011, and tube sheets 1012 are provided at both ends of the shell 1011. Heat exchange tubes 1013 for CNG circulation are provided between the two tube sheets 1012. Array-distributed baffle devices 2 are provided on the outer side of the heat exchange tubes 1013. The baffle devices 2 block the fluid entering the shell 1011, so that the flow direction of the fluid is "W" shaped.

[0063] Sealing gaskets are provided at the connection between the tube sheet 1012 and the front head 102 and at the connection between the tube sheet 1012 and the rear head 103, and the gaps on the heat exchange device 1 are sealed by the sealing gaskets to prevent high-temperature water and compressed natural gas from leaking from the gaps.

[0064] The shell 1011 includes a low-temperature zone and a high-temperature zone. Telescopic devices 3 are respectively installed between the baffle devices 2 located in the low-temperature zone and the baffle devices 2 located in the high-temperature zone to adjust the plate spacing between adjacent baffle devices 2.

[0065] The telescopic device 3 includes an electromagnetic driving device or an electric push rod. The fixed end and the output end of the electromagnetic driving device are respectively fixedly connected to the corresponding deflection devices 2. Adjusting the plate spacing between the two deflection devices 2 by the electromagnetic driving device belongs to the existing technology and will not be elaborated here.

[0066] The outer side of the housing 1011 is provided with a liquid inlet 1014 equivalent to the water inlet, and a liquid outlet 1015 equivalent to the water outlet.

[0067] Reference Figures 2 to 5 As shown, the front head portion 102 includes a cover body 1021 , and a partition plate 1022 is provided inside the cover body 1021 . The partition plate 1022 divides the cover body 1021 into two upper and lower areas.

[0068] An air inlet 1023 and an air outlet 1024 are provided on the outer side of the cover body 1021 . The air inlet 1023 is connected to the upper half of the cover body 1021 , and the air outlet 1024 is connected to the lower half of the cover body 1021 .

[0069] Compressed natural gas enters the upper area of ​​the cover body 1021 through the air inlet 1023, and then enters the rear head 103 through the guidance of the heat exchange tube 1013. The compressed natural gas is turned in the rear head 103, and the turned compressed natural gas enters the lower area of ​​the cover body 1021 through the heat exchange tube 1013, and finally discharged from the heat exchange device 1 through the air outlet 1024 in the lower area of ​​the cover body 1021.

[0070] Reference Figures 3 to 9 As shown, the deflector 2 includes a circumferential plate 201 , which is provided with a through hole 202 for the heat exchange tube 1013 to pass through, and a notch 203 for the fluid to pass through. The notch 203 is provided with an adjusting member 204 for sealing the notch 203 .

[0071] The diameter of the circumferential plate 201 is matched with the inner diameter of the housing 1011. Further, the circumferential plate 201 near the liquid inlet 1014 is tightly combined with the housing 1011 by a fixed connection, and similarly, the circumferential plate 201 near the liquid outlet 1015 is also fixedly connected with the housing 1011. There is a specific area between the two circumferential plates 201 fixedly connected with the housing 1011, and the circumferential plates 201 in the area are designed to be movably connected with the housing 1011, so as to realize the tight assembly of the structure and the effective performance of the heat exchange function.

[0072] It should be noted that the notches 203 on the circumferential plates 201 distributed inside the shell 1011 are arranged in a staggered manner, which causes the high-temperature water flow to present a specific “W”-shaped flow path inside the shell 1011 .

[0073] An expansion portion 205 is provided on one side of the circumferential plate 201 facing the occipital region 103 . When the area between two adjacent circumferential plates 201 is in a sealed state, the plate spacing between the two circumferential plates 201 is enlarged and the expansion portion 205 expands.

[0074] Reference Figures 7 and 8 As shown, the adjusting member 204 includes a limiting groove 2041 opened on the circumferential plate 201, a movable plate 2042 is arranged inside the limiting groove 2041, and pushing members 2043 are arranged on both sides of the movable plate 2042. The pushing members 2043 drive the movable plate 2042 to move up and down along the limiting groove 2041 and seal the notch 203.

[0075] The pushing member 2043 is preferably an electric push rod, the fixed end of the pushing member 2043 is fixedly connected to the limiting groove 2041, and the output end of the pushing member 2043 is fixedly connected to the movable plate 2042. The extension amount of the movable plate 2042 from the limiting groove 2041 is adjusted by the extension amount of the pushing member 2043, thereby controlling the blocking amount of the movable plate 2042 on the notch 203.

[0076] Adjusting the extension amount of the movable plate 2042 by means of an electric push rod belongs to the prior art and will not be described in detail here.

[0077] Reference Figures 8 to 9 As shown, the expansion portion 205 includes a hollow groove 2051 opened on the circumferential plate 201 , and an elastic membrane 2052 is arranged in the hollow groove 2051 .

[0078] Temperature sensors are provided at both ends of the heat exchange tube 1013. The temperatures at both ends of the heat exchange tube 1013 are detected by the two temperature sensors, and the temperature difference between the two ends of the heat exchange tube 1013 is obtained by calculating the difference between the two.

[0079] The liquid inlet 1014 and the liquid outlet 1015 of the shell 1011 are both provided with pressure gauges. The pressures of the liquid inlet 1014 and the liquid outlet 1015 of the shell 1011 are detected by the two pressure gauges, and the pressure drop of the shell 1011 is obtained by calculating the difference between the two.

[0080] When in use, compressed natural gas is introduced into the upper area of ​​the cover body 1021 through the air inlet 1023. The compressed natural gas entering the cover body 1021 is guided by the heat exchange tube 1013 and gradually enters the back head 103. The compressed natural gas entering the back head 103 is turned inside the back head 103. The turned compressed natural gas enters the lower area of ​​the cover body 1021 through the heat exchange tube 1013, and is finally discharged from the heat exchange device 1 from the air outlet 1024 in the lower area of ​​the cover body 1021.

[0081] During the flow of compressed natural gas inside the heat exchange device 1, the high-temperature water flowing out of the cold storage tank 300 enters the interior of the shell 1011 through the liquid inlet 1014 on the shell 1011. The high-temperature water entering the shell 1011 flows in the shell 1011 in a "W" shape under the influence of the baffle (see Figure 5 As shown in the figure, when the high-temperature water flows in a "W" shape, turbulence will be formed between the two circumferential plates 201 when passing through the notch 203 of the circumferential plate 201, thereby improving the heat exchange effect between the high-temperature water and the heat exchange tube 1013.

[0082] During the flow of high-temperature water and compressed natural gas, the system determines the heat transfer efficiency between natural gas and high-temperature water by detecting the temperature difference at both ends of the heat exchange tube 1013 and the pressure drop value of the shell 1011, and controls the telescopic device 3 and the pushing member 2043 to make corresponding structural changes according to the heat transfer efficiency to ensure normal heat exchange between natural gas and high-temperature water.

[0083] During the system monitoring process, if it is found that the temperature difference between the two ends of the heat exchange tube 1013 exceeds the preset threshold, while at the same time, the pressure drop of the shell 1011 is maintained within the normal range, this phenomenon indicates that the high-temperature water contained in the shell 1011 does not provide sufficient heating efficiency for the compressed natural gas flowing through the heat exchange tube 1013. As a result, the temperature difference between the two ends of the heat exchange tube 1013 increases significantly.

[0084] by Figure 5For example, four circumferential plates 201 are provided inside the shell 1011. When the control system detects that the high-temperature water inside the shell 1011 cannot fully heat the compressed natural gas in the heat exchange tube 1013, the control system controls the telescopic device 3 located on the low-temperature side of the shell 1011 to contract, and controls the telescopic device 3 located on the high-temperature side of the shell 1011 to extend, thereby reducing the plate spacing between the two circumferential plates 201 located on the low-temperature side of the shell 1011 and expanding the plate spacing between the two circumferential plates 201 located on the high-temperature side of the shell 1011, thereby balancing the temperature difference at both ends of the heat exchange tube 1013 and avoiding damage to the connection between it and the tube sheet 1012 due to the influence of temperature difference stress.

[0085] It should be noted that in this embodiment, the low temperature side of the shell 1011 is the area of ​​the shell 1011 close to the front head 102 , and the high temperature side of the shell 1011 is the area of ​​the shell 1011 close to the back head 103 .

[0086] It should be noted that: when the spacing between the folded plates decreases, the flow path of the fluid in the heat exchanger will be shortened, and the frequency of the fluid changing its flow direction will increase accordingly, which helps to generate more turbulence; turbulence can enhance the heat exchange between the fluid and the heat exchange tube 1013, thereby improving the heat exchange efficiency.

[0087] When the distance between the folded plates increases, the fluid tends to accumulate in the heat transfer dead zone, forming a larger heat transfer dead zone. The fluid in the heat transfer dead zone flows slowly and the heat exchange effect is poor.

[0088] In the process of adjusting the distance between the circumferential plates 201, the pressure drop change of the shell 1011 is detected synchronously. When the pressure drop increases, the pushing member 2043 on the low-temperature side circumferential plate 201 is controlled to contract, and the pushing member 2043 drives the movable plate 2042 to move, so that the shielding range of the movable plate 2042 on the notch 203 becomes smaller, that is, the relative gap between the circumferential plate 201 and the shell 1011 becomes larger. When the relative gap height increases, the fluid flow rate decreases, the eddy current area expands, and it is easy to form a larger heat transfer dead zone inside the heat exchanger, thereby slowing down the heat exchange effect between the low-temperature sides and reducing the pressure drop.

[0089] It should be noted that: although the pressure drop can be reduced by controlling the movable plate 2042 to block the notch 203 in a smaller range, the plate spacing between the low-temperature side circular plates 201 has been shortened before, thereby reducing the pressure drop while ensuring that the heat transfer effect on the low-temperature side remains at a high level.

[0090] When the system detects that the temperature difference at both ends of the heat exchange tube 1013 is in a stable state, but the pressure drop of the shell 1011 exceeds the set state, the result indicates that the fluid inside the shell 1011 encounters too much resistance during the flow process. In order to maintain the flow of the fluid, it is necessary to provide a larger pressure difference at both ends of the shell 1011, which leads to an increase in the pressure drop of the heat exchanger.

[0091] by Figure 5 For example, four circumferential plates 201 are provided inside the shell 1011. When the control system detects that the resistance encountered by the fluid inside the shell 1011 during the flow is too large, the telescopic devices 3 located on the low-temperature side and the high-temperature side of the shell 1011 are controlled to extend synchronously, so that the plate spacing between the circumferential plates 201 located inside the shell 1011 is expanded, and the pressure drop between the liquid inlet 1014 and the liquid outlet 1015 of the shell 1011 is balanced, so as to avoid the shell 1011 running for a long time under the state of excessive pressure drop, which leads to a decrease in its structural strength and increases the risk of leakage and explosion.

[0092] It should be noted that: in the process of synchronous extension of the telescopic device 3 located on the low-temperature side of the shell 1011 and the telescopic device 3 located on the high-temperature side, the plate spacing between the two circumferential plates 201 opposite to the low-temperature side will gradually decrease. At this time, the pushing members 2043 located on the two circumferential plates 201 will shrink synchronously, so that the shielding range of the movable plates 2042 on the two circumferential plates 201 to the notch 203 is reduced, thereby reducing the pressure in the area corresponding to the two circumferential plates 201 to a certain extent, thereby reducing the pressure drop.

[0093] When the system detects that the temperature difference at both ends of the heat exchange tube 1013 and the pressure drop of the shell 1011 exceed the preset threshold, this phenomenon indicates that there is scaling on the surface of the heat exchange tube 1013 inside the shell 1011 and on the circumferential plate 201. Specifically, the accumulation of scaling on the surface of the heat exchange tube 1013 will significantly increase its surface roughness, thereby hindering the smoothness of the heat transfer path, resulting in a significant decrease in heat transfer efficiency. In addition, the formation of scaling also increases the fluid resistance in the shell 1011. This is because the presence of scaling changes the flow path and morphology of the fluid, forcing the fluid to overcome greater flow resistance when passing through, thereby causing an abnormal increase in pressure drop.

[0094] When the system detects scaling on the surface of the heat exchange tube 1013 and the circumferential plate 201, the control system controls the telescopic device 3 to drive the circumferential plate 201 to move back and forth on the heat exchange tube 1013, so that the perforations 202 on the circumferential plate 201 clear the structure on the heat exchange tube 1013, and the outer edge of the circumferential plate 201 clears the structure on the inner wall of the shell 1011, thereby preventing scaling from accumulating on the heat exchange tube 1013 and affecting the heat transfer effect of high-temperature water on the heat exchange tube 1013.

[0095] by Figure 5 As shown in the example, four circumferential plates 201 are arranged inside the shell 1011, two of which are located on the low temperature side of the shell 1011, and the other two are located on the high temperature side of the shell 1011. Of the two circumferential plates 201 corresponding to the low temperature side and the high temperature side, one is movably connected to the shell 1011 (referred to as A plate), and the other is fixedly connected to the shell 1011 (referred to as B plate).

[0096] It should be noted that: in the low temperature side area, the circumferential plate 201 close to the liquid inlet 1014 is fixedly connected to the shell 1011; in the high temperature side area, the circumferential plate 201 close to the liquid outlet 1015 is fixedly connected to the shell 1011.

[0097] When cleaning the scale accumulated on the low-temperature side circumferential plate 201, the telescopic device 3 drives the A plate to move toward the B plate. In this process, the pushers 2043 on the A plate and the B plate are both in a contracted state, so that the movable plate 2042 does not completely block the notch 203, thereby allowing water to flow freely through the notch 203.

[0098] When the telescopic device 3 drives the A plate to move away from the B plate, the pushers 2043 on the A plate and the B plate are both extended, and the movable plate 2042 immediately blocks the notch 203. Therefore, during the movement of the A plate, a negative pressure will be generated in the area between the A plate and the B plate, and under the influence of this pressure difference, the elastic membrane 2052 on the back of the B plate will expand. The expansion of the elastic membrane 2052 will damage the stress structure of the scale on the back of the B plate, thereby causing the scale on the back of the B plate to fall off. At the same time, during the movement of the A plate, the water flow will accumulate between the B plate and the tube sheet 1012. When the pushers 2043 on the A plate and the B plate are in a contracted state again, the water flow accumulated between the B plate and the tube sheet 1012 will flush the scale between the A plate and the B plate at a high speed. As the water flows, the flushed scale will be brought into the purifier for collection.

[0099] When cleaning the scale accumulated on the high-temperature side circumferential plate 201, the steps are the same as the above process.

[0100] It should be noted that when cleaning the scale accumulated at the junction of the low temperature side and the high temperature side, the movable circumferential plate 201 corresponding to the low temperature side should be kept stationary, and the junction should be cleaned using the movable circumferential plate 201 corresponding to the high temperature side. The specific operation steps can be carried out with reference to the above description.

[0101] In summary, the present invention uses a temperature sensor and a pressure gauge to monitor the temperature difference at both ends of the heat exchange tube 1013 and the pressure drop of the shell 1011 respectively, so as to evaluate the heat transfer efficiency between natural gas and high-temperature water. When the temperature difference or pressure drop exceeds the preset threshold, the control system changes the spacing of the circumferential plates 201 and the shielding range of the notch 203 by adjusting the telescopic device 3 and the pusher 2043 to balance the temperature difference and pressure drop. If the temperature difference is stable but the pressure drop is abnormal, it indicates that the fluid resistance is too large, and the telescopic device 3 needs to be extended synchronously to expand the spacing of the circumferential plates 201 to reduce the pressure drop. When both the temperature difference and the pressure drop exceed the threshold, it indicates that scaling exists. At this time, the control system drives the circumferential plate 201 to move back and forth. When the two circumferential plates 201 move away from each other, the movable plate 2042 immediately blocks the notch 203, and uses the negative pressure between the two circumferential plates 201 to drive the elastic membrane 2052 to expand. The water flow flushing and the expansion of the elastic membrane 2052 remove the scaling on the inner wall of the heat exchange tube 1013 and the shell 1011 to ensure the heat exchange efficiency. The entire system realizes precise control and optimization of the heat exchange process by dynamically adjusting the structural parameters.

[0102] Embodiment 3

[0103] Reference Fig.11 As shown, the end of the heat exchange tube 1013 is connected to the tube sheet 1012 through the compensation device 4, and the compensation device 4 includes a fixed plate 401 arranged on the tube sheet 1012, and a telescopic tube 402 is arranged on the fixed plate 401. The end of the telescopic tube 402 is provided with a mounting plate 403, and a limiting movable part 404 is provided between the mounting plate 403 and the fixed plate 401.

[0104] By arranging compensation devices 4 at both ends of the heat exchange tube 1013 to connect with the tube sheets 1012 at both ends of the shell 1011, when the temperature difference between the two ends of the heat exchange tube 1013 is large, if the heat exchange tube 1013 generates stress stretching, the telescopic tube 402 compensates and buffers the stress stretching of the heat exchange tube 1013 to avoid excessive stress stretching of the heat exchange tube 1013, resulting in the connection between the heat exchange tube 1013 and the tube sheet 1012 being pulled off and ruptured, causing the risk of compressed natural gas leaking from the joint between the heat exchange tube 1013 and the tube sheet 1012.

[0105] Embodiment 4

[0106] The present invention also provides an energy-saving method for a CNG loading station energy-saving system based on deep coupling utilization of cold energy, the energy-saving method comprising the following steps:

[0107] S1. Preliminary heating and filtering stage: First, the compressed natural gas is introduced into the primary heat exchanger 100 for preliminary heating. After the heating is completed, the compressed natural gas is depressurized by the primary pressure regulator 1002 and enters the primary filter 1001 for preliminary impurity removal;

[0108] S2. Secondary heating and fine filtration stage: The compressed natural gas after preliminary filtration enters the secondary heat exchanger 200 for secondary heating treatment, and then is further depressurized by the secondary pressure regulator 2002 and enters the secondary filter 2001 for secondary filtration, and finally the purified natural gas is transported to the city pipeline network;

[0109] S3. Cold recovery and reuse stage: Based on S1 and S2, the high-temperature water in the upper part of the cold storage tank 300 is used to perform heat exchange on the low-temperature natural gas in the primary heat exchanger 100 and the secondary heat exchanger 200. The high-temperature water after heat exchange flows to the lower part of the cold storage tank 300 to reduce the water temperature in the lower part; at the same time, the low-temperature water in the lower part of the cold storage tank 300 is used to cool the CNG compressor 400, and the generated high-temperature water flows back to the upper part of the cold storage tank 300 to perform a cold recovery and reuse cycle;

[0110] S4. Heat exchange efficiency optimization stage: Based on S3, by monitoring the temperature difference and pressure drop changes inside the heat exchanger, using the dynamic adjustment of the control adjustment member 204 and the telescopic device 3, the heat exchange process between natural gas and high-temperature water is optimized according to the needs under different working conditions to ensure that the heat exchange is more sufficient and efficient.

[0111] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A CNG loading station energy-saving system based on deep coupling utilization of cold energy, characterized in that: It comprises a primary heat exchanger (100), a primary pressure regulator (1002), a primary filter (1001), a secondary heat exchanger (200), a secondary pressure regulator (2002), and a secondary filter (2001) which are sequentially connected via connecting pipes; The primary heat exchanger (100) and the secondary heat exchanger (200) comprise a shell-and-tube heat exchange device (1), wherein the heat exchange device (1) comprises a shell-side portion (101) for performing gas-liquid mass transfer operations, and a front head portion (102) and a rear head portion (103) are respectively provided at two ends of the shell-side portion (101); The shell side portion (101) comprises a shell (1011), tube sheets (1012) are provided at both ends of the shell (1011), a heat exchange tube (1013) for CNG circulation is provided between the two tube sheets (1012), an array of baffle devices (2) are provided on the outside of the heat exchange tube (1013), the baffle device (2) comprises a circumferential plate (201), a through hole (202) for the heat exchange tube (1013) to pass through is opened on the circumferential plate (201), a notch portion (203) for fluid to pass through is provided on the circumferential plate (201), and an adjusting member (204) for sealing the notch portion (203) is provided in the notch portion (203); The adjusting member (204) comprises a limiting groove (2041) formed on the circumferential plate (201); a movable plate (2042) is provided inside the limiting groove (2041); pushing members (2043) are provided on both sides of the movable plate (2042); the pushing members (2043) drive the movable plate (2042) to move up and down along the limiting groove (2041) and perform a blocking operation on the notch (203); The circumferential plate (201) is provided with an expansion portion (205) on one side facing the occipital region (103); when the area between two adjacent circumferential plates (201) is in a sealed state, the plate spacing between the two circumferential plates (201) is enlarged, and the expansion portion (205) expands; The expansion portion (205) comprises a hollow groove (2051) formed on the circumferential plate (201), wherein an elastic membrane (2052) is provided in the hollow groove (2051).

2. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 1 is characterized in that: The heat exchange device (1) is equipped with a water inlet and a water outlet. The water outlet of the primary heat exchanger (100) is connected to the water inlet of the secondary heat exchanger (200). The water outlet of the secondary heat exchanger (200) is connected to the water inlet of the low-temperature side of the cold storage tank (300). The water outlet of the low-temperature side of the cold storage tank (300) is connected to the water inlet of the CNG compressor (400). The water outlet of the CNG compressor (400) is connected to the water inlet of the high-temperature side of the cold storage tank (300). The water outlet of the high-temperature side of the cold storage tank (300) flows back to the water inlet of the primary heat exchanger (100), forming a closed cycle.

3. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 2 is characterized in that: A primary filter (1001) is provided between the primary heat exchanger (100) and the secondary heat exchanger (200), and the primary filter (1001) performs preliminary filtering on the compressed natural gas entering the secondary heat exchanger (200). A secondary filter (2001) is provided between the secondary heat exchanger (200) and the urban pipeline network, and the secondary filter (2001) performs secondary filtering on the compressed natural gas entering the urban pipeline network.

4. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 3 is characterized in that: A primary purifier (1003) is provided between the water outlet of the primary heat exchanger (100) and the water inlet of the secondary heat exchanger (200), and the primary purifier (1003) intercepts fluid impurities entering the secondary heat exchanger (200). A secondary purifier (2003) is provided between the water outlet of the secondary heat exchanger (200) and the cold storage box (300), and the secondary purifier (2003) intercepts fluid impurities entering the cold storage box (300).

5. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 4 is characterized in that: The deflection device (2) blocks the fluid entering the housing (1011), so that the flow direction of the fluid is in a "W" shape; The shell (1011) comprises a low temperature zone and a high temperature zone, and telescopic devices (3) are respectively installed between the baffle devices (2) located in the low temperature zone and the baffle devices (2) located in the high temperature zone, so as to adjust the plate spacing between adjacent baffle devices (2); The outer side of the shell (1011) is provided with a liquid inlet (1014) equivalent to a water inlet, and a liquid outlet (1015) equivalent to a water outlet.

6. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 5 is characterized in that: The front head portion (102) comprises a cover body (1021), a partition plate (1022) is provided inside the cover body (1021), and the partition plate (1022) divides the cover body (1021) into two upper and lower areas; An air inlet (1023) and an air outlet (1024) are provided on the outer side of the cover body (1021); the air inlet (1023) is connected to the upper half of the cover body (1021), and the air outlet (1024) is connected to the lower half of the cover body (1021).

7. The CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 4 is characterized in that: The end of the heat exchange tube (1013) is connected to the tube sheet (1012) via a compensation device (4); the compensation device (4) comprises a fixed plate (401) arranged on the tube sheet (1012); a telescopic tube (402) is arranged on the fixed plate (401); a mounting plate (403) is arranged at the end of the telescopic tube (402); and a limiting movable part (404) is arranged between the mounting plate (403) and the fixed plate (401).

8. An energy-saving method for a CNG loading station energy-saving system based on deep coupling utilization of cold energy according to claim 6, characterized in that: The energy saving method comprises the following steps: S1. Preliminary heating and filtering stage: First, the compressed natural gas is introduced into the primary heat exchanger (100) for preliminary heating. After the heating is completed, the compressed natural gas is depressurized by the primary pressure regulator (1002) and enters the primary filter (1001) for preliminary impurity removal; S2. Secondary heating and fine filtration stage: The compressed natural gas after preliminary filtration enters the secondary heat exchanger (200) for secondary heating treatment, and then is further depressurized by the secondary pressure regulator (2002) and enters the secondary filter (2001) for secondary filtration, and finally the purified natural gas is transported to the city pipeline network; S3. Cold recovery and reuse stage: Based on S1 and S2, the high-temperature water in the upper part of the cold storage box (300) is used to perform heat exchange on the low-temperature natural gas in the primary heat exchanger (100) and the secondary heat exchanger (200). The high-temperature water after the heat exchange flows to the lower part of the cold storage box (300) to reduce the water temperature in the lower part. At the same time, the low-temperature water in the lower part of the cold storage box (300) is used to cool the CNG compressor (400), and the generated high-temperature water flows back to the upper part of the cold storage box (300) to perform a cold recovery and reuse cycle. S4. Heat exchange efficiency optimization stage: Based on S3, by monitoring the temperature difference and pressure drop changes inside the heat exchanger, the heat exchange process between natural gas and high-temperature water is optimized according to the needs under different working conditions by using the dynamic adjustment of the control regulating member (204) and the telescopic device (3).

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