Liquid air energy storage project cold box inner plate fin heat exchanger pre-cooling device

Abstract

The present application relates to heat exchanger technical field, especially to a kind of liquid air energy storage project cold box inner plate fin heat exchanger precooling device.Its technical scheme includes gas-liquid separation tank, liquid nitrogen storage tank, plate-fin heat exchanger, positive flow gas outlet pipe, backflow gas pipeline, the bottom of the gas-liquid separation tank is provided with inlet pipe, top is provided with outlet pipe, side is provided with liquid nitrogen inlet, inside is provided with liquid nitrogen spraying device;The positive flow outlet pipe one end is fixedly connected with heat exchanger body.The present application uses liquid nitrogen cooling capacity to cool heat exchanger, detects the gas temperature difference at the positive flow gas outlet and backflow gas inlet position of heat exchanger when cooling, when temperature difference is large, by reducing the liquid nitrogen flow of first electric regulating valve and reducing the gas flow speed at second electric regulating valve, avoid temperature difference to further increase, prevent too low temperature gas even cryogenic liquid nitrogen into heat exchanger body to produce temperature impact to cause heat exchanger body damage.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and in particular to a pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project. Background Technology

[0002] Liquid air energy storage is a novel large-scale, long-term energy storage technology. It utilizes electricity generated during off-peak hours by compressing and liquefying air for storage. During peak demand periods, the liquid air is pressurized and reheated to release high-temperature, high-pressure air, which then drives an expander to generate electricity. By storing liquid air during periods of low electricity demand and releasing it during peak demand, it achieves peak shaving and valley filling. This technology solves the problems of low density in compressed air storage and the need for large storage containers. At atmospheric pressure, liquid air storage does not require underground salt caverns, artificial chambers, or large storage containers, is not limited by geographical conditions, and has a cost advantage.

[0003] Patent document CN119268415B proposes a plate heat exchanger that uses guide grooves to guide and limit the guide section, tilting the rotating seat, upper side plates, and lower side plates. This allows the heat exchange plates to be vertically inserted between the two upper and two lower side plates, avoiding the bending installation process and significantly reducing mechanical stress on the heat exchange plates. This reduces potential damage such as deformation, scratches, and creases during installation, improving the structural integrity and service life of the heat exchange plates. The rotating seat design not only facilitates installation but also simplifies the disassembly process. When maintenance is required, the heat exchange plates can be vertically removed by rotating the rotating seat back to the tilt angle, avoiding fatigue damage caused by repeated bending in traditional methods. This reduces maintenance difficulty and extends the service life of the heat exchange plates. However, this patent only addresses the plate stress problem during the manufacturing and installation stages of the heat exchanger.

[0004] During the operation of the heat exchanger, the cold medium is always a cryogenic liquid. If the cryogenic liquid directly enters the plate-fin heat exchanger during the initial start-up, the heat transfer is rapid, the temperature of the heat exchanger metal drops sharply, and the local constraint is extremely large, which will generate very large temperature difference stress and easily lead to damage to the plate-fin heat exchanger. Summary of the Invention

[0005] The purpose of this invention is to address the problem in the prior art where the rapid drop in the temperature of the heat exchanger metal leads to excessive thermal stress, and to propose a pre-cooling device for a plate-fin heat exchanger inside the cold box of a liquid air energy storage project.

[0006] The technical solution of this invention: A pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project, comprising a heat exchanger body, wherein a forward flow inlet pipe and a reverse flow outlet pipe are installed at the top of the heat exchanger body, and a forward flow outlet and a reverse flow inlet are installed at the bottom, and further comprising:

[0007] The precooling mechanism includes a gas-liquid separator. A positive outflow gas pipe is fixedly installed at the bottom of the gas-liquid separator. The end of the positive outflow gas pipe is fixedly connected to the heat exchanger body. A first temperature sensor is fixedly installed inside the positive inflow gas pipe. A fourth temperature sensor is fixedly installed inside the negative outflow gas pipe. An installation ring is fixedly installed inside the gas-liquid separator. A spray head is fixedly installed at the bottom of the installation ring. The spray head is connected to a liquid nitrogen storage tank through a pipe. A first electric regulating valve is fixedly installed on the pipe between the liquid nitrogen storage tank and the spray head.

[0008] The second and third temperature sensors are electrically connected to the first electric regulating valve.

[0009] The first temperature sensor and the fourth temperature sensor are electrically connected to the second electric regulating valve.

[0010] Optionally, multiple spray heads are provided and are distributed in a ring at equal angles at the bottom of the mounting ring.

[0011] Optionally, a first solid-liquid separation layer is fixedly installed inside the gas-liquid separator, and the height of the first solid-liquid separation layer is higher than the height of the mounting ring.

[0012] Optionally, the top of the gas-liquid separator is connected to a reflux inlet pipe, and a second electric regulating valve is fixedly installed between the end of the reflux inlet pipe and the heat exchanger body.

[0013] Optionally, a second temperature sensor is fixedly installed on the positive outflow pipe, and a third temperature sensor is fixedly installed on the reverse inflow pipe.

[0014] Optionally, a protection mechanism is provided on the side of the gas-liquid separator. The protection mechanism includes a pressure relief tank, and a branch pipe is fixedly installed at the bottom of the pressure relief tank. The end of the branch pipe is connected to the gas-liquid separator.

[0015] Optionally, a pressure relief valve is fixedly installed on the branch pipe, and the end of the branch pipe is fixedly installed between the spray head and the first solid-liquid separation layer.

[0016] Optionally, a loop pipe is fixedly installed on the side of the pressure relief tank. The loop pipe is fixedly installed on the side of the gas-liquid separator, and the end of the loop pipe is located above the first solid-liquid separation layer.

[0017] Optionally, a second solid-liquid separation layer is fixedly installed inside the pressure relief tank, and the volume of the pressure relief tank is half of the total pressure relief tank volume.

[0018] Optionally, the liquid nitrogen storage tank is externally fixedly equipped with a cold insulation layer or is a vacuum-insulated pressure vessel, and a flow valve is fixedly installed on the positive flow inlet pipe.

[0019] Compared with the prior art, the present invention has the following beneficial technical effects:

[0020] This invention detects the gas temperature difference between the inlet and outlet of the heat exchanger body. When the temperature difference is large, it reduces the liquid nitrogen flow rate at the first electric regulating valve and the gas flow rate at the second electric regulating valve to prevent the temperature difference from increasing further. This prevents excessively low-temperature gas or even low-temperature liquid nitrogen from entering the heat exchanger body and causing temperature shocks that could damage the heat exchanger body. As liquid nitrogen continuously replenishes the cooling capacity, the temperature of the return gas gradually decreases. Entering from the cold end of the heat exchanger body, the temperature gradually decreases from bottom to top, effectively establishing a temperature gradient for the heat exchanger body under design conditions, facilitating rapid start-up of the heat exchanger during normal operation.

[0021] This invention cools the dry, positive flow gas exiting the heat exchanger by adding liquid nitrogen into the gas-liquid separator. The vaporization of the liquid nitrogen causes an increase in the internal pressure of the gas-liquid separator. When the internal pressure of the gas-liquid separator reaches the maximum working pressure that the gas-liquid separator can withstand, the pressure relief valve opens, and the gas in the gas-liquid separator flows into the pressure relief tank through the branch pipe or is vented, thereby reducing the internal pressure of the gas-liquid separator and preventing excessive pressure from damaging the storage tank. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 This is a schematic diagram of gas flow according to the present invention;

[0024] Figure 3 This is a schematic diagram of the liquid nitrogen storage tank structure of the present invention;

[0025] Figure 4 This is a cross-sectional schematic diagram of the gas-liquid separator structure of the present invention;

[0026] Figure 5 This is a cross-sectional schematic diagram of the pressure relief tank structure of the present invention.

[0027] Reference numerals in the attached drawings: 1. Heat exchanger body; 2. Forward flow inlet pipe; 3. Flow valve; 4. Pre-cooling mechanism; 41. Gas-liquid separator; 42. Forward flow outlet pipe; 43. Liquid nitrogen storage tank; 44. Mounting ring; 45. Spray head; 46. First solid-liquid separation layer; 47. Backflow inlet pipe; 48. First temperature sensor; 49. Second temperature sensor; 410. Third temperature sensor; 411. Fourth temperature sensor; 412. First electric regulating valve; 413. Second electric regulating valve; 5. Backflow outlet pipe; 6. Protection mechanism; 61. Pressure relief tank; 62. Branch pipe; 63. Pressure relief valve; 64. Second solid-liquid separation layer; 65. Return pipe. Detailed Implementation

[0028] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0030] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0032] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0033] Example 1

[0034] This embodiment proposes a pre-cooling device for a plate-fin heat exchanger inside the cold box of a liquid air energy storage project, such as... Figure 1As shown, the device includes a heat exchanger body 1. A forward flow inlet pipe 2 and a reverse flow outlet pipe 5 are fixedly installed on the top of the heat exchanger body 1, while a forward flow outlet pipe 42 and a reverse flow inlet pipe 47 are connected to the bottom of the heat exchanger body 1. Dry compressed gas enters through the forward flow inlet pipe 2, passes through the heat exchanger body 1, the forward flow outlet pipe 42, the gas-liquid separator 41, and the reverse flow inlet pipe 47, returning to the reverse flow channel of the heat exchanger body 1, and finally exiting through the reverse flow outlet pipe 5. Multiple sets of vertically equidistant sensors are arranged on the side of the heat exchanger body 1. Each set of sensors is located at different flow channels on the same cross-section of the heat exchanger, used to detect the temperature at various vertical and horizontal positions of the heat exchanger body 1, thereby detecting the axial temperature gradient change of the heat exchanger body 1 and the temperature difference between different flow channels on the same cross-section of the heat exchanger body 1. A flow meter is installed on the forward flow inlet pipe 2 to observe the intake air volume, and a flow valve 3 is fixedly installed on the forward flow inlet pipe 2.

[0035] like Figures 1 to 4 As shown, the heat exchanger body 1 and the precooling mechanism 4 are connected through various pipelines. The precooling mechanism 4 includes a gas-liquid separator 41. A positive outflow gas pipe 42 is fixedly installed at the bottom of the gas-liquid separator 41. The end of the positive outflow gas pipe 42 is fixedly connected to the heat exchanger body 1. An installation ring 44 is fixedly installed inside the gas-liquid separator 41. A spray head 45 is fixedly installed at the bottom of the installation ring 44. The spray head 45 is connected to a liquid nitrogen storage tank 43 through a pipeline. A cold insulation layer or a vacuum-insulated pressure vessel is fixedly installed on the outside of the liquid nitrogen storage tank 43.

[0036] According to relevant standards and specifications, during cooling, the cooling rate of the heat exchanger body 1 should generally not exceed 1℃ / min, the cooling speed should not exceed 30℃ / h, and the temperature difference between different flow channels on the same cross-section of the heat exchanger body 1 should not exceed 30℃. Liquid nitrogen is injected into the liquid nitrogen storage tank 43 to assist in cooling the dry gas entering the gas-liquid separator 41, forming a cryogenic gas. The cryogenic gas returns to the heat exchanger body 1 in the cold box to exchange heat with the forward flow gas in the adjacent flow channel, simultaneously cooling the heat exchanger body 1, effectively controlling the cooling rate of the heat exchanger body 1. Using cryogenic gas cooling ensures controllable cryogenic gas temperature. Because the temperature of the cryogenic gas gradually decreases, and the temperature difference between the cryogenic gas entering the heat exchanger body 1 and the metal temperature of the heat exchanger body 1 is always controlled within 30℃, temperature shocks to the heat exchanger body 1 caused by the cryogenic gas are avoided, preventing damage to the heat exchanger. During the cooling process, the heat exchanger body 1 has a positive flow gas as a heat source, which can keep the temperature of the hot end of the heat exchanger stable. As the liquid nitrogen at the rear end continuously replenishes the cooling capacity, the low-temperature gas formed flows back from the cold end of the heat exchanger to the heat exchanger, gradually reducing the temperature of the cold end. During the heat exchange process between the positive flow gas and the backflow gas, the temperature gradient of the heat exchanger can be effectively established, which facilitates the rapid start-up of the heat exchanger.

[0037] Multiple spray heads 45 are provided and are distributed in a ring at equal angles at the bottom of the mounting ring 44 to ensure uniform spraying. A first solid-liquid separation layer 46 is fixedly installed inside the gas-liquid separator 41, and the height of the first solid-liquid separation layer 46 is higher than the height of the mounting ring 44. The first solid-liquid separation layer 46 intercepts unvaporized liquid nitrogen, preventing liquid nitrogen from directly entering the heat exchanger body 1.

[0038] like Figure 1 and Figure 2 As shown, a first temperature sensor 48 is fixedly installed inside the forward flow inlet pipe 2, and a fourth temperature sensor 411 is fixedly installed inside the return flow outlet pipe 5. A first electric regulating valve 412 is fixedly installed on the pipe between the liquid nitrogen storage tank 43 and the spray head 45. The temperature at the forward flow inlet pipe 2 is detected by the first temperature sensor 48, and the temperature at the return flow outlet pipe 5 is detected by the fourth temperature sensor 411. A return flow inlet pipe 47 is fixedly installed on the top of the gas-liquid separator 41. A second electric regulating valve 413 is fixedly installed between the end of the return flow inlet pipe 47 and the heat exchanger body 1. A second temperature sensor 49 is fixedly installed on the forward flow outlet pipe 42, and a third temperature sensor 410 is fixedly installed on the return flow inlet pipe 47. The second temperature sensor 49 and the third temperature sensor 410 are electrically connected to the first electric regulating valve 412; the first temperature sensor 48 and the fourth temperature sensor 411 are electrically connected to the second electric regulating valve 413.

[0039] The temperature of the gas at the forward inlet pipe 2 is detected by a first temperature sensor 48; the temperature of the gas at the forward outlet pipe 42 of the heat exchanger body 1 is detected by a second temperature sensor 49; the temperature of the gas at the return inlet pipe 47 is detected by a third temperature sensor 410; and the temperature of the gas at the return outlet pipe 5 is detected by a fourth temperature sensor 411. The second and third temperature sensors 49 and 410 transmit the temperature data to a computer, which calculates the temperature difference between the two (i.e., the cold end temperature difference of the heat exchanger body 1). When the temperature difference is too large, the computer uses a controller to reduce the flow rate of liquid nitrogen by the first electric regulating valve 412 to prevent the temperature of the low-temperature gas in the gas-liquid separator from becoming too low, thereby controlling the cold end temperature difference. The first and fourth temperature sensors 48 and 411 transmit the temperature data to a computer, which calculates the temperature difference between the two (i.e., the hot end temperature difference of the heat exchanger). When the temperature difference is too large, the computer uses a controller to reduce the flow rate of the low-temperature gas by the second electric regulating valve 413, thereby controlling the hot end temperature difference.

[0040] A stream of forward-flowing gas enters the forward-flowing gas channel from the hot end of heat exchanger body 1. Liquid nitrogen enters the gas-liquid separator and mixes with the forward-flowing gas exiting heat exchanger body 1. The vaporized liquid nitrogen, combined with the forward-flowing gas, forms a cryogenic gas that pre-cools heat exchanger body 1, effectively controlling the cooling rate of heat exchanger body 1. Using cryogenic gas for pre-cooling ensures controllable cryogenic gas temperature. Because the temperature of the cryogenic gas gradually decreases, and the temperature difference between the cryogenic gas entering heat exchanger body 1 and the metal temperature of heat exchanger body 1 is always controlled within 30℃, the direct entry of cryogenic liquid into the heat exchanger avoids temperature shock to the heat exchanger body, preventing damage to heat exchanger body 1. During pre-cooling, the forward-flowing gas inlet pipe 2 of heat exchanger body 1 serves as a heat source, maintaining a stable temperature of heat exchanger body 1. As liquid nitrogen continuously replenishes the cooling capacity, entering through the return-flowing gas inlet pipe 47 of heat exchanger body 1, the cold end temperature is gradually reduced, effectively establishing a temperature gradient in heat exchanger body 1, facilitating rapid start-up of heat exchanger body 1.

[0041] A manual or electric regulating valve is fixedly installed on the forward flow inlet pipe 2. By reducing the air intake of the regulating valve, the forward flow rate of the forward flow inlet pipe 2 is reduced. This reduces the liquid nitrogen intake at the first electric regulating valve 412, controlling the temperature difference between the return flow inlet pipe 47 and the forward flow outlet pipe 42. If the cooling rate is too fast in a short period of time, the first electric regulating valve 412 can be closed to prevent liquid nitrogen from entering, thus allowing for phased cooling of the heat exchanger body 1 and reducing the average cooling rate over a certain period. During the adjustment period, the temperature difference between the return flow inlet pipe 47 and the forward flow outlet pipe 42 can be controlled to never exceed 30℃.

[0042] This invention detects the gas temperature difference at the inlet and outlet of the heat exchanger body 1. When the temperature difference is large, it reduces the liquid nitrogen flow rate at the first electric regulating valve 412 and the gas flow rate at the second electric regulating valve 413 to prevent the temperature difference from increasing further, prevent low-temperature gas from entering the heat exchanger body 1 and causing temperature shock, and prevent damage to the heat exchanger body 1. As liquid nitrogen continuously replenishes the cooling capacity, it enters from the cold end of the heat exchanger body 1 and gradually reduces the cold end temperature, which can effectively establish a temperature gradient in the heat exchanger body 1 and facilitate rapid start-up of the heat exchanger.

[0043] like Figures 2 to 5 As shown, a protection mechanism 6 is provided on the side of the gas-liquid separator 41. The protection mechanism 6 includes a pressure relief tank 61. A branch pipe 62 is fixedly installed at the bottom of the pressure relief tank 61. The end of the branch pipe 62 is connected to the gas-liquid separator 41. A pressure relief valve 63 is fixedly installed on the branch pipe 62.

[0044] After liquid nitrogen is added to the gas-liquid separator 41, the vaporization of liquid nitrogen will cause the internal pressure of the gas-liquid separator 41 to increase. When the internal pressure of the gas-liquid separator 41 is greater than the maximum working pressure that the gas-liquid separator 41 can withstand, the pressure relief valve 63 opens, and the gas in the gas-liquid separator 41 flows into the pressure relief tank 61 from the branch pipe 62, reducing the internal pressure of the gas-liquid separator 41 and preventing damage to the gas-liquid separator 41.

[0045] The end of the branch pipe 62 is fixedly installed between the spray head 45 and the first solid-liquid separation layer 46. The unblocked droplets of liquid in the first solid-liquid separation layer 46 are introduced into the pressure relief tank 61 for diversion. A second solid-liquid separation layer 64 is fixedly installed inside the pressure relief tank 61. The volume of the pressure relief tank 61 is half of the total volume. The second solid-liquid separation layer 64 performs gas-liquid separation on the gas entering the pressure relief tank 61.

[0046] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A pre-cooling device for a plate-fin heat exchanger in a cold box of a liquid air energy storage project, comprising a heat exchanger body (1), wherein a forward flow inlet pipe (2) and a reverse flow outlet pipe (5) are installed on the top of the heat exchanger body (1), characterized in that, Also includes: The precooling mechanism (4) includes a gas-liquid separator (41), a positive outflow gas pipe (42) is fixedly installed at the bottom of the gas-liquid separator (41), the end of the positive outflow gas pipe (42) is fixedly connected to the heat exchanger body (1), a first temperature sensor (48) is fixedly installed inside the positive inflow gas pipe (2), a fourth temperature sensor (411) is fixedly installed inside the return outflow gas pipe (5), an installation ring (44) is fixedly installed inside the gas-liquid separator (41), a spray head (45) is fixedly installed at the bottom of the installation ring (44), the spray head (45) is connected to a liquid nitrogen storage tank (43) through a pipe, and a first electric regulating valve (412) is fixedly installed on the pipe between the liquid nitrogen storage tank (43) and the spray head (45). A reflux inlet pipe (47) is fixedly installed on the top of the gas-liquid separator (41). A second electric regulating valve (413) is fixedly installed between the end of the reflux inlet pipe (47) and the heat exchanger body (1). The first temperature sensor (48), the fourth temperature sensor (411) are electrically connected to the second electric regulating valve (413). A second temperature sensor (49) is fixedly installed on the positive outflow pipe (42), and a third temperature sensor (410) is fixedly installed on the reverse inflow pipe (47). The second temperature sensor (49) and the third temperature sensor (410) are electrically connected to the first electric regulating valve (412).

2. The pre-cooling device for a plate-fin heat exchanger in a cold box of a liquid air energy storage project according to claim 1, characterized in that: Multiple spray heads (45) are provided and are distributed in a ring at equal angles at the bottom of the mounting ring (44).

3. The pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project according to claim 2, characterized in that: The gas-liquid separator (41) has a first solid-liquid separation layer (46) fixedly installed inside, and the height of the first solid-liquid separation layer (46) is higher than the height of the mounting ring (44).

4. The pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project according to claim 3, characterized in that: The gas-liquid separator (41) is provided with a protection mechanism (6) on its side. The protection mechanism (6) includes a pressure relief tank (61). A branch pipe (62) is fixedly installed at the bottom of the pressure relief tank (61). The end of the branch pipe (62) is connected to the gas-liquid separator (41).

5. A pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project according to claim 4, characterized in that: A pressure relief valve (63) is fixedly installed on the branch pipe (62), and the end of the branch pipe (62) is fixedly installed between the spray head (45) and the first solid-liquid separation layer (46).

6. The pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project according to claim 5, characterized in that: A circuit pipe (65) is fixedly installed on the side of the pressure relief tank (61). The circuit pipe (65) is fixedly installed on the side of the gas-liquid separator (41), and the end of the circuit pipe (65) is located above the first solid-liquid separation layer (46).

7. A pre-cooling device for a plate-fin heat exchanger inside a cold box of a liquid air energy storage project according to claim 6, characterized in that: The pressure relief tank (61) has a second solid-liquid separation layer (64) fixedly installed inside, and the volume of the pressure relief tank (61) is half of the volume of the pressure relief tank (61).

8. The pre-cooling device for a plate-fin heat exchanger in a cold box of a liquid air energy storage project according to claim 7, characterized in that: The liquid nitrogen storage tank (43) is externally fixedly installed with a cold insulation layer or is a vacuum-insulated pressure vessel, and a flow valve (3) is fixedly installed on the positive flow inlet pipe (2).

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