JP4980284B2 - Liquid cooling device - Google Patents

Description

  The present invention relates to a liquid cooling device that cools a liquid phase in a reaction generation unit that generates a gas hydrate by reacting a raw material gas and water under low temperature and high pressure.

  In gas hydrate, gas molecules such as hydrocarbons such as methane, ethane, propane, and butane, which are natural gas components, and carbon dioxide are taken into the interior of the three-dimensional structure formed by combining water molecules. It is a general term for clathrate hydrates (hydrates) formed in this way. That is, the gas hydrate is an ice-like solid substance composed of source gas molecules and water molecules, and is a stable clathrate compound in which source gas molecules are included inside a three-dimensional cage structure formed by water molecules. It is a kind. This gas hydrate has a relatively large gas storage capacity, and has characteristic properties such as large generation / decomposition energy and selectivity of hydrated gas. For example, transportation and storage of natural gas, etc. Various applications such as means, heat storage systems, actuators, and separation and recovery of specific component gases are possible, and research is actively conducted.

  Gas hydrate is usually generated under high pressure and low temperature conditions. The following methods are well known as generation methods. By spraying cooled water from the top of the reaction vessel filled with raw material gas at high pressure, so-called "water spray method", in which gas hydrate is generated on the surface of the water droplet when the water droplet falls in the raw material gas, reaction A so-called “bubbling method” or the like is performed such that gas hydrate is generated on the surface of the bubbles when the bubbles of the source gas rise in the water by introducing the source gas into the water in the container as bubbles.

  In the bubbling method, the gas hydrate generated in the water in the reaction vessel floats in the water because the specific gravity is smaller than that of water. Then, the amount of gas hydrate increases with the progress of the production reaction and is slurried by stirring. Usually, when the content of gas hydrate in the slurry becomes about 10 wt% to 20 wt%, the generated gas hydrate is extracted out of the reaction vessel in a slurry state.

  The extracted gas hydrate in the slurry state is passed through a dehydrator to be dehydrated and the gas hydrate content is increased to about 40 wt% to 50 wt%. In this state, it is sent to the next generation step for further increasing the gas hydrate content to about 90 wt%.

  FIG. 8 shows a schematic configuration diagram of a conventional gas hydrate manufacturing apparatus (for example, Patent Document 1). A reaction generator 1 that generates a primary gas hydrate 6 by reacting a raw material gas and water under low temperature and high pressure, a liquid cooling device 2 that cools a liquid in the reaction generator 1, and the reaction generator The slurry of the primary gas hydrate 6 generated in 1 is sent through the slurry pump 10, and the dehydrating device 3 for concentrating the slurry, the concentrated slurry dehydrated by the dehydrating device 3 and the raw material gas are reacted again. And a second reaction generation unit 5 that generates a high concentration secondary gas hydrate 4.

The liquid cooling device 2 is provided to suppress an increase in the liquid temperature in the reaction generation unit 1 because the gas hydrate generation reaction is an exothermic reaction. As shown in FIG. 8, the liquid cooling device 2 includes a circulation line 7 that draws liquid from the first reaction generation unit 1 and returns the liquid, a circulation pump 8 provided in the circulation line 7, The heat exchanger 9 is provided downstream from the circulation pump 8 in the circulation direction.
JP 2006-111746 A

  However, when the slurry of the primary gas hydrate 6 generated in the reaction generation unit 1 is extracted and cooled in the heat exchanger 9, the liquid temperature of the slurry can be lowered, but the liquid temperature decrease is caused by the gas hydrate generation reaction. Acts in the forward direction. As a result, there is a problem that gas hydrate is generated and adhered in the heat exchanger 9 and the flow path is blocked.

  The conventional heat exchanger 9 has a heat transfer tube 11 having the same diameter structure with a uniform inner diameter over the entire length. The inner diameter is usually about 19 mm. Moreover, the shape includes a straight line, a U-shaped reversal shape, etc., and the total length is usually about 4 to 6 m. In such a long, same-diameter structure, the liquid flowing inside flows at a uniform speed, so that it is an environment in which gas hydrate is easily generated and adheres to the inner wall, and once in the heat transfer tube 11, the gas hydrate is temporarily formed. When clogging occurs due to the generation and adhesion of gas, the generation and adhesion of gas hydrate increases from that point, and it is difficult to remove the adhering gas hydrate.

  An object of the present invention is to provide a liquid cooling device in which gas hydrate is unlikely to adhere to the inner wall of a heat transfer tube of a heat exchanger. It is another object of the present invention to provide a liquid cooling device that can be easily removed even if it adheres.

  In order to achieve the above object, the liquid cooling apparatus according to the first aspect of the present invention includes a liquid phase in a reaction generation unit that generates a gas hydrate by reacting a raw material gas and water under low temperature and high pressure. A liquid cooling device for cooling, comprising a circulation line for extracting liquid from the reaction generation unit and returning it again, a circulation pump provided in the circulation line, and a heat exchanger provided in the circulation line, The heat exchanger is characterized in that the heat transfer tube through which the liquid flows has a different diameter structure in which the inlet side in the liquid circulation direction has a large diameter and the outlet side has a small diameter.

  According to this aspect, since the inner diameter of the heat transfer tube through which the liquid flows is configured to have a different diameter structure in which the inlet side in the liquid circulation direction has a large diameter and the outlet side has a small diameter, the liquid flow rate is from the inlet toward the outlet. It gets faster and faster as you go. Due to the gradually changing flow velocity, the gas hydrate flowing in the heat transfer tube can be made difficult to adhere to the inner wall of the heat transfer tube.

According to a second aspect of the present invention, in the liquid cooling apparatus according to the first aspect, the different diameter structure of the heat transfer tube has a tapered shape in which an inner diameter gradually decreases in a liquid circulation direction. is there.
According to this aspect, since the taper shape is used, uniform speeding-up can be realized over the entire length of the heat transfer tube, so that blockage can hardly occur at any location.

  According to a third aspect of the present invention, in the liquid cooling apparatus according to the first aspect, the different-diameter structure of the heat transfer tube has a multistage shape in which the inner diameter decreases stepwise in the liquid circulation direction. Is.

  According to this aspect, since the inner diameter of the heat transfer tube is a multi-stage shape that gradually decreases, the liquid (fluid) flowing in the tube is gradually increased in speed, and the flow is changed, and the gas hydrate is further transferred to the heat transfer tube. It becomes difficult to adhere to the inner wall of the.

  According to a fourth aspect of the present invention, in the liquid cooling apparatus according to the third aspect, a heat insulating member is provided on an outer surface portion of the heat transfer tube corresponding to a region where the inner diameter of the heat transfer tube changes from large to small. It is characterized by being.

  In a multi-stage shape in which the inner diameter of the heat transfer tube is reduced stepwise, gas hydrate is likely to adhere to the portion where the inner diameter of the heat transfer tube gradually decreases due to cooling of the refrigerant flowing therearound. However, in the present invention, since the heat insulating member is provided on the outer surface portion of the corresponding heat transfer tube, the cooling action by the refrigerant is alleviated and the gas hydrate is difficult to adhere.

  According to a fifth aspect of the present invention, in the liquid cooling apparatus according to any one of the first to fourth aspects, a pressure sensor that detects a differential pressure upstream and downstream of the heat exchanger, and the pressure sensor And a control unit that switches the direction of the circulation flow by the circulation pump in the reverse direction when the differential pressure exceeds the first set value P1.

  According to this aspect, the gas hydrate is less likely to adhere to the inner wall of the heat transfer tube due to the increase in speed. However, when the gas hydrate still adheres and becomes clogged, the occurrence of the clogging is determined by the pressure sensor and controlled. The unit switches the direction of the circulation flow of the liquid by the circulation pump in the reverse direction. The gas hydrate adhering to the impact due to the reversal change in the flow direction can be removed to eliminate the blockage.

  According to a sixth aspect of the present invention, in the liquid cooling apparatus according to the fifth aspect, the control unit receives a detection signal from the pressure sensor, and the differential pressure becomes equal to or less than a second set value P2. Is configured to return the direction of the circulation flow by the circulation pump to the initial direction.

  According to this aspect, after the reversal change of the flow direction, when the clogging of the gas hydrate is resolved, the direction of the liquid circulation flow can be automatically returned to the initial state to return to the normal operation.

  According to a seventh aspect of the present invention, in the liquid cooling apparatus according to any one of the first to fourth aspects, a pressure sensor that detects a differential pressure upstream and downstream of the heat exchanger, and the pressure sensor And a control unit that outputs a control signal in response to the detection signal, and when the differential pressure exceeds a first set value P1, the control unit changes the direction of the circulation flow by the circulation pump in the reverse direction. Thereafter, when the first set time T1 has elapsed, it is determined whether or not the differential pressure has become equal to or less than the second set value P2, and when the differential pressure has not become equal to or less than the second set value P2, circulation by the circulation pump is performed. The flow direction is changed to the initial direction, and when the second set time T2 elapses thereafter, it is again determined whether the differential pressure has become the second set value P2 or less, and the differential pressure has been set to the second set value P2 or less. If not, the circulation flow by the circulation pump A control unit that returns to the step of changing the direction to the opposite direction, and on the other hand returns the direction of the circulation flow by the circulation pump to the initial direction when the differential pressure becomes equal to or less than the second set value P2, and ends. It is characterized by.

  According to this aspect, even in the case of a high load where the blockage of the gas hydrate cannot be easily resolved, the change in the direction of the circulation flow of the liquid can be repeated forward and backward, so the blockage is eliminated by the impact of the repeated change. can do.

  According to an eighth aspect of the present invention, in the liquid cooling device according to any one of the first to seventh aspects, the heat exchanger is located upstream in the circulation direction from the circulation pump. It is what.

  According to this aspect, in the circulation line, the heat exchanger is provided upstream of the circulation pump in the circulation direction. Therefore, when a blockage based on gas hydrate occurs in the heat transfer tube, the pump pressure of the circulation pump becomes a suction force and acts on the blockage portion, and the pressure of the blockage portion is changed to the pump pressure (suction force). Acts to automatically lower. When the pressure drops below the equilibrium pressure for gas hydrate decomposition, the gas hydrate decomposition reaction that caused the blockage begins and proceeds. Therefore, in combination with the different-diameter structure, it is possible to further prevent clogging.

  According to the present invention, the inner diameter of the heat transfer tube through which the liquid flows in the heat exchanger is configured to have a different diameter structure in which the inlet side in the circulation direction of the liquid has a large diameter and the outlet side has a small diameter. It gets faster and faster as you move toward. Due to the gradually changing flow velocity, the gas hydrate flowing in the heat transfer tube can be made difficult to adhere to the inner wall of the heat transfer tube.

[Embodiment 1]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 (A) is a schematic configuration diagram showing a gas hydrate manufacturing apparatus including a liquid cooling device according to Embodiment 1 of the present invention, and FIG. 1 (B) shows a gas hydrate attached to a heat transfer tube. It is a principal part expanded sectional view in a state. FIG. 2 is a cross-sectional view showing a schematic configuration of the heat exchanger, and FIG. 3 is a cross-sectional view showing a schematic configuration of the heat exchanger in a state where gas hydrate is attached to the inner wall of the heat transfer tube. FIG. 4 is a flowchart for explaining the control contents of the controller of the liquid cooling device.

  The apparatus for producing a gas hydrate according to the present embodiment generates a primary gas hydrate 6 by reacting a raw material gas and water under a low temperature (about 3 ° C.) and a high pressure (about 5.5 MPa). Unit 1, a liquid cooling device 2 that cools the liquid in the reaction generation unit 1, and a slurry of the primary gas hydrate 6 generated in the reaction generation unit 1 is sent through a slurry pump 10, and the slurry is concentrated And a second reaction generation unit 5 that generates a high-concentration secondary gas hydrate 4 by reacting the concentrated slurry dehydrated by the dehydration device 3 with the raw material gas again. Yes.

  Although the liquid cooling device 2 will be described repeatedly, since the gas hydrate production reaction is an exothermic reaction, the liquid cooling device 2 is provided to suppress an increase in the liquid temperature in the reaction production unit 1. As shown in FIG. 1A, the liquid cooling device 2 includes a circulation line 7 that draws liquid from the first reaction generation unit 1 and returns it to the outside, and a circulation pump 8 provided in the circulation line 7. And the heat exchanger 9 provided on the downstream side in the circulation direction F from the circulation pump 8.

  The heat exchanger 9 has a different diameter structure in which the inner diameter of the heat transfer tube 11 through which the liquid flows has a large diameter on the inlet side and a small diameter on the outlet side in the liquid circulation direction F. In the present embodiment, as shown in FIG. 1B, FIG. 2, or FIG. 3, the different diameter structure of the heat transfer tube 11 has a tapered shape in which the inner diameter gradually decreases in the liquid circulation direction F. .

  Further, the pressure sensors 12 and 13 for detecting the differential pressure upstream and downstream of the heat exchanger 9 and the detection signals of the pressure sensors 12 and 13 receive the differential pressure exceeding the first set value P1. In some cases, a control unit 14 that switches the direction of the circulation flow by the circulation pump 8 to the reverse direction U is provided. Here, the first set value P1 is a pressure difference, that is, a pressure difference between the upstream and downstream sides of the heat transfer tube 11 when clogging occurs and it becomes difficult to eliminate if left blocked, and is determined in advance by actual measurement. Is.

  In the present embodiment, the control unit 14 further receives the detection signals of the pressure sensors 12 and 13, and when the differential pressure becomes equal to or lower than the second set value P2, the control unit 14 determines the circulation flow by the circulation pump 8. The direction is configured to return to the initial direction F. Here, the second set value P2 indicates that the gas hydrate attached to the inner wall of the heat transfer tube 11 in a state where the circulation flow is switched in the reverse direction U after the heat transfer tube 11 is blocked. When the clogging is gradually removed and the blockage is eliminated, the differential pressure gradually decreases, but the differential pressure in a state in which the clogging is almost completely eliminated by the reduced differential pressure is also determined in advance by actual measurement. It is.

  In FIG. 1B and FIG. 3, reference numeral 15 indicates gas hydrate attached to the inner wall 16 of the heat transfer tube 11. 2 and 3, reference numeral 17 denotes an inlet of the refrigerant 19 provided in the main body 20 of the heat exchanger 9, and reference numeral 18 denotes the outlet.

  The operational effects of the first embodiment will be described. Since the inner diameter of the heat transfer tube 11 through which the liquid flows has a different diameter structure in which the inlet side in the liquid circulation direction has a large diameter and the outlet side has a small diameter, the flow rate of the liquid gradually increases as it proceeds from the inlet toward the outlet. . Due to this gradually changing flow velocity, the risk of gas hydrate flowing in the heat transfer tube 11 from adhering to the inner wall 16 of the heat transfer tube 11 can be reduced. Furthermore, by making the said different diameter structure into a taper shape, uniform speed-up can be implement | achieved over the full length of the heat exchanger tube 11, and obstruction | occlusion can be made hard to occur in any location.

  Moreover, although the gas hydrate is less likely to adhere to the inner wall 16 of the heat transfer tube 11 due to the increase in speed, when the gas hydrate still adheres and becomes blocked, the control unit 14 performs the following control flow in the control flow shown in FIG. To be controlled.

  The occurrence of the blockage is determined by the pressure sensors 12 and 13 (whether the first set value P1 has been exceeded? Step S1), and the control unit 14 switches the direction of the circulating liquid flow by the circulation pump 8 to the reverse direction U. Is output (step S2). The gas hydrate adhering to the inner wall 16 of the heat transfer tube 11 is dropped by the impact due to the reverse change of the flow direction, and the blockage can be eliminated.

  Further, after the reversal change of the circulating flow (U direction), when the gas hydrate blockage is resolved, the differential pressure decreases, but this is detected by the pressure sensors 12 and 13 (second set value). Step S3), the direction of the liquid circulation flow can be automatically returned to the initial state (direction F) to return to normal operation (step S4).

[Embodiment 2]
FIG. 5 is a flowchart for explaining the control contents of the controller of the liquid cooling apparatus according to Embodiment 2 of the present invention. In the present embodiment, when the differential pressure exceeds the first set value P1 (step S11), the control unit 14 changes the direction of the circulation flow by the circulation pump 8 in the reverse direction (step S12). Thereafter, when the first set time T1 has elapsed (step S13), it is determined whether the differential pressure has become equal to or less than the second set value P2 (step S14), and the differential pressure becomes equal to or less than the second set value P2. If not, the direction of the circulation flow by the circulation pump 8 is changed to the initial direction F (step S15), and after the second set time T2 has elapsed (step S16), the differential pressure is again set to the second set value. It is determined whether or not the pressure is equal to or lower than P2 (step S17). If the differential pressure is not lower than or equal to the second set value P2, the process returns to the step of changing the direction of the circulating flow by the circulating pump 8 to the reverse direction U (step S). 2). Then, the direction of the circulation flow by the circulation pump 8 is switched between forward and reverse, and this is repeated.

  On the other hand, when the differential pressure becomes equal to or less than the second set value P2 (steps 14 and 17), the direction of the circulation flow by the circulation pump 8 is returned to the initial direction F (step 18) and the process is ended. The control unit 14 is configured.

  According to the present embodiment, even in the case of a high load where the blockage of the gas hydrate cannot be easily resolved, the change in the direction of the circulation flow of the liquid can be repeated forward and reverse, so that the blockage is caused by the impact of the repeated change. Can be eliminated.

[Embodiment 3]
FIG. 6 is a schematic cross-sectional view of a liquid cooling apparatus according to Embodiment 3 of the present invention. The liquid cooling device according to the present embodiment is characterized in that the different diameter structure of the heat transfer tube 11 is a multi-stage shape in which the inner diameter decreases stepwise in the liquid circulation direction. That is, the heat transfer tube 11 has the largest inner diameter portion 21, the second inner diameter portion 22, the third inner diameter portion 23, and the smallest inner diameter portion 24 positioned in this order along the direction F. is doing. And the taper part 25,26,27 is located in the order along the direction F in the boundary part of each same diameter part. Furthermore, a heat insulating member 28 is provided on the outer surface portion of the heat transfer tube 11 corresponding to the tapered portions 25, 26, and 27, which are regions where the inner diameter of the heat transfer tube 11 changes from large to small. The kind of heat insulating material 28 can use what is used widely, and is not limited to a specific kind.

  According to the present embodiment, since the inner diameter of the heat transfer tube 11 is a multistage shape that gradually decreases, the liquid (fluid) flowing in the tube gradually increases in speed and changes in the flow to further increase the gas hydrate. Is difficult to adhere to the inner wall 16 of the heat transfer tube 11.

  Further, in the multistage shape in which the inner diameter of the heat transfer tube 11 is reduced stepwise, the tapered portions 25, 26, and 27, which are portions where the inner diameter of the heat transfer tube 11 gradually decreases, are cooled by the cooling of the refrigerant 19 flowing around the gas. Hydrate tends to adhere. However, in the present embodiment, since the heat insulating member 28 is provided on the corresponding outer surface portion of the heat transfer tube 11, the cooling action by the refrigerant 19 is alleviated and the gas hydrate is difficult to adhere.

[Embodiment 4]
FIG. 7 is a schematic configuration diagram showing a gas hydrate manufacturing apparatus provided with a liquid cooling apparatus according to Embodiment 4 of the present invention. The liquid cooling apparatus 2 according to the present embodiment is characterized in that the heat exchanger 9 is located upstream of the circulation pump 8 in the circulation direction. Since the other configuration is the same as that of the first embodiment shown in FIG. 1, the same parts are denoted by the same reference numerals and the description thereof is omitted.

  According to the present embodiment, in the circulation line 7, the heat exchanger 9 is provided upstream of the circulation pump 8 in the circulation direction. Therefore, when the heat transfer tube 11 is blocked due to gas hydrate, the pump pressure of the circulation pump 8 acts as a suction force on the closed portion, and the pressure in the closed portion is reduced to the pump pressure (suction). Force) to automatically lower. When the pressure drops below the equilibrium pressure for gas hydrate decomposition, the gas hydrate decomposition reaction that caused the blockage begins and the decomposition proceeds. Therefore, in combination with the different-diameter structure, it is possible to further prevent clogging.

(A) is a schematic block diagram which shows the manufacturing apparatus of the gas hydrate provided with the liquid cooling device which concerns on Embodiment 1 of this invention, (B) is the principal part in the state in which the gas hydrate of the heat exchanger tube adhered. It is an expanded sectional view. 1 is a cross-sectional view illustrating a schematic configuration of a heat exchanger according to Embodiment 1. FIG. It is a schematic block diagram which shows the manufacturing apparatus of the gas hydrate which concerns on Embodiment 1 of this invention. It is a schematic block diagram which shows the manufacturing apparatus of the gas hydrate which concerns on Embodiment 2 of this invention. 2 is a cross-sectional view showing a schematic configuration of a heat exchanger in a state where gas hydrate is attached to an inner wall of a heat transfer tube according to Embodiment 1. FIG. 4 is a flowchart for explaining the control contents of a control unit of the liquid cooling apparatus according to the first embodiment. 10 is a flowchart for explaining control contents of a control unit of the liquid cooling apparatus according to the second embodiment. 6 is a schematic cross-sectional view of a liquid cooling apparatus according to Embodiment 3. FIG. FIG. 6 is a schematic configuration diagram showing a gas hydrate manufacturing apparatus including a liquid cooling device according to a fourth embodiment. It is a schematic block diagram which shows the manufacturing apparatus of the gas hydrate provided with the conventional liquid cooling device.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Reaction production | generation part, 2 Liquid cooling device, 3 Dehydration apparatus, 4 High concentration secondary gas hydrate, 5 Second reaction production | generation part, 6 Primary gas hydrate, 7 Circulation line, 8 Circulation pump, 9 Heat exchanger , 10 Slurry pump, 11 Heat transfer tube, 12 Pressure sensor, 13 Pressure sensor, 14 Control unit, 15 Adhered gas hydrate, 16 Inner wall, 17 Refrigerant inlet, 18 Refrigerant outlet, 19 Refrigerant, 20 Heat exchanger main body 21 Same diameter part with maximum inner diameter, 22 Same diameter part with second inner diameter, 23 Third same diameter part, 24 Minimum same diameter part, 25, 26, 27 Tapered part, 28 Heat insulation member

Claims (7)

A liquid cooling device that cools a liquid phase in a reaction generation unit that reacts a raw material gas and water under low temperature and high pressure to generate gas hydrate,
A circulation line for extracting liquid from the reaction generation unit and returning it again;
A circulation pump provided in the circulation line;
A heat exchanger provided in the circulation line,
The heat exchanger, the inlet side of the circulation direction inside diameter of the liquid of the heat transfer tube that has a part of the circulation line, wherein the liquid flow diameter, configured in different diameters structure outlet side becomes small,
The heat exchanger is located upstream of the circulation pump in the circulation line in the circulation line, and the pump pressure of the circulation pump acts as a suction force on the small diameter outlet portion of the heat transfer tube. A liquid cooling device. The liquid cooling device according to claim 1,
The liquid cooling apparatus according to claim 1, wherein the heat transfer tube has a different diameter structure having a tapered shape in which an inner diameter gradually decreases in a liquid circulation direction. The liquid cooling device according to claim 1,
2. The liquid cooling apparatus according to claim 1, wherein the heat transfer tube has a different-diameter structure having a multistage shape in which an inner diameter is gradually reduced in a liquid circulation direction. The liquid cooling device according to claim 3.
A liquid cooling device, wherein a heat insulating member is provided on an outer surface portion of the heat transfer tube corresponding to a region where the inner diameter of the heat transfer tube changes from large to small. In the liquid cooling device according to any one of claims 1 to 4,
A pressure sensor for detecting a differential pressure upstream and downstream of the heat exchanger;
And a control unit that receives a detection signal of the pressure sensor and switches the direction of the circulation flow by the circulation pump in a reverse direction when the differential pressure exceeds a first set value P1. Cooling system. The liquid cooling device according to claim 5, wherein
The control unit is configured to receive a detection signal of the pressure sensor and to return the direction of the circulation flow by the circulation pump to the initial direction when the differential pressure becomes equal to or less than a second set value P2. A liquid cooling device. In the liquid cooling device according to any one of claims 1 to 4,
A pressure sensor for detecting a differential pressure upstream and downstream of the heat exchanger;
A control unit that receives a detection signal of the pressure sensor and outputs a control signal; and
The controller is
When the differential pressure exceeds the first set value P1, the direction of the circulation flow by the circulation pump is changed to the reverse direction, and after the first set time T1, the differential pressure is equal to or less than the second set value P2. When the differential pressure is not less than or equal to the second set value P2, the direction of the circulation flow by the circulation pump is changed to the initial direction, and after the second set time T2 has passed, It is determined whether or not the differential pressure is equal to or lower than the second set value P2, and when the differential pressure is not equal to or lower than the second set value P2, the process returns to the step of changing the direction of the circulation flow by the circulation pump to the opposite direction. On the other hand, a liquid cooling apparatus comprising: a control unit that returns the direction of the circulation flow by the circulation pump to an initial direction when the differential pressure becomes equal to or less than a second set value P2, and ends.

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