A pressure isolating device for preventing steam penetration

Abstract

The present invention discloses a pressure isolation device for preventing steam penetration, which belongs to the field of refrigerators or heat pump systems; wherein a U-tube inlet section, a U-tube cooling section and a U-tube outlet section are sequentially connected, the U-tube inlet section is connected to the high-pressure cavity liquid refrigerant water outlet, and the U-tube outlet section is connected to the low-pressure cavity liquid refrigerant water inlet, and the fluid in the U-tube cooling section is cooled and heat-exchanged, thereby preventing steam penetration from occurring in the pressure isolation device. In the present invention, the working medium temperature in the U-tube is reduced to below the flash evaporation temperature, that is, it is ensured that steam penetration does not occur in the tube, thereby greatly improving the refrigeration COP of various existing absorption machines.

Description

Technical Field

[0001] The invention belongs to the technical field of refrigerators or heat pump systems, and in particular relates to a pressure isolating device for preventing steam from penetrating. Background Art

[0002] Lithium bromide absorption heat pumps or absorption refrigerators are widely used in heating systems and various industrial processes. The stability and good performance of the unit operation are the key to the design and development of the unit. The unit operates in a vacuum environment. There are multiple cavities inside the unit. The working fluid (such as lithium bromide solution, refrigerant water) will flow between multiple cavities. The cavities are generally connected by U-shaped tubes as flow isolation devices. The U-shaped tube can not only provide a working fluid flow channel, but also play a role in stabilizing the pressure isolation of the two cavities. When the working fluid in the high-pressure cavity flows to the low-pressure cavity, violent flash evaporation will occur in the flow isolation device, forming a fierce gas-liquid two-phase flow, causing the average density of the fluid in the tube to be greatly reduced, which makes the actual pressure isolation capacity of the pressure isolation device (U-shaped tube) more than 60% lower than the design value. When the pressure difference between the cavities at both ends of the U-shaped tube is high, the liquid level of the U-shaped tube disappears, and the pressure effect of isolating the two cavities by the liquid seal disappears, and the steam in the two cavities penetrates. Especially when steam penetrates the condensing U-tube from the condenser to the evaporator, the cooling capacity of the unit will be reduced and the COP will be greatly reduced; therefore, process structure optimization should be adopted to avoid this problem.

[0003] The applicant discovered that the reason for the steam penetration of the U-tube used for pressure isolation is the process of two-phase flow (phase change) in the flow of the internal working fluid. This spontaneous flash phase change under vacuum to produce a gas-liquid two-phase flow process was discovered for the first time in the field of absorption heat pumps or absorption refrigerators, and is also rare in the field of traditional two-phase flow research. Therefore, there is no method or device in the existing research and invention to prevent the steam penetration of the U-tube pressure isolation device; when two-phase flow occurs in the tube, all existing units simply do not have the height conditions to design a U-tube that high to maintain the required pressure difference; specifically, a U-tube of about 6 to 8 meters in height is required to maintain the pressure difference; but this exceeds the height of all lithium bromide absorption heat pumps or absorption refrigerators.

[0004] To address this problem, we propose a new pressure isolation device for preventing steam penetration; we look for a suitable cold source in the process of lithium bromide absorption heat pump or absorption refrigeration unit, and cool the fluid passing through the pressure isolation device (U-tube) in various heat exchange modes without affecting the performance of the unit, thereby avoiding two-phase flow and steam penetration problems; while maintaining the pressure isolation mode of the pressure isolation device (U-tube), only a slight change can solve the common steam penetration problem of absorption machines, thereby greatly improving the refrigeration COP of various existing absorption machines. Summary of the invention

[0005] In response to the problems existing in the background technology, the present invention provides a pressure isolating device for preventing steam penetration, characterized in that it comprises: a U-shaped tube inlet section, a U-shaped tube outlet section and a U-shaped tube cooling section, wherein the U-shaped tube inlet section, the U-shaped tube cooling section and the U-shaped tube outlet section are connected in sequence, the U-shaped tube inlet section is connected to the liquid refrigerant water outlet of the high-pressure cavity, and the U-shaped tube outlet section is connected to the liquid refrigerant water inlet of the low-pressure cavity, and the fluid in the U-shaped tube cooling section is cooled and heat-exchanged, thereby preventing steam penetration from occurring in the pressure isolating device.

[0006] The cooling and heat exchange of the fluid in the U-tube cooling section is to reduce the temperature of the fluid in the pressure-isolating U-tube cooling section to below the saturation temperature corresponding to the outlet pressure of the U-tube outlet section, ensuring that the fluid in the U-tube cooling section and the outlet section flows in a pure liquid state.

[0007] The cooling and heat exchange of the fluid in the U-tube cooling section is achieved by: cooling and heat exchange by a low-temperature fluid or direct heat exchange inside the unit.

[0008] The cooling and heat exchange by a low-temperature fluid is as follows: a heat exchanger is installed outside the U-tube cooling section to exchange heat with the low-temperature fluid, wherein the hot side of the heat exchanger is the U-tube cooling section, and the low-temperature fluid in the cold side pipe of the heat exchanger connected to the cold side of the heat exchanger is the low-temperature refrigerant water in the cold water tank in the unit, the cooling water of the unit or other available cold sources.

[0009] The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and U-tube outlet section of each stage are respectively connected to the condenser and evaporator of this stage; at the same time, the refrigerant water of the lower refrigerant water tank is used as the cold side fluid of the heat exchanger of this stage, and the refrigerant water of the lowest refrigerant water tank is also used as the cold side fluid of the heat exchanger of this stage.

[0010] The direct heat exchange from inside the unit is as follows: a transverse tube is respectively installed at the position where the U-tube cooling section is connected to the U-tube inlet section and at the position where the U-tube cooling section is connected to the U-tube outlet section, and the U-tube cooling section with the transverse tube installed is immersed in the refrigerant water of the low-temperature refrigerant water tank in the unit; thereby reducing the flow resistance of the U-tube cooling section.

[0011] The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and U-tube outlet section of each stage are respectively connected to the condenser and evaporator of the same stage; at the same time, the U-tube cooling section of each stage is connected to the refrigerant water tank of the lower stage through a cross pipe, and the refrigerant water in the refrigerant water tank of the lower stage is used to exchange heat with the fluid in the U-tube cooling section of the current stage, and the refrigerant water in the refrigerant water tank of the lowest stage is also used as the cold side fluid of the U-tube cooling section of the current stage.

[0012] The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and the U-tube outlet section are respectively connected to the liquid refrigerant water outlet of the last stage condenser and the liquid refrigerant water inlet of the first stage evaporator.

[0013] The unit is a second-type absorption heat pump, the U-tube inlet section is connected to the evaporator liquid refrigerant water outlet, and the U-tube outlet section is connected to the condenser liquid refrigerant water inlet.

[0014] The beneficial effects of the present invention are:

[0015] 1. As long as the working medium temperature in the U-tube is reduced to below the flash temperature, it can be ensured that there will be no steam penetration in the tube.

[0016] 2. The common vapor penetration problem of absorption machines can be solved by a small change, thereby greatly improving the refrigeration COP of various existing absorption machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of Embodiment 1 of a pressure isolating device for preventing steam penetration according to the present invention;

[0018] Figure 2 This is a vertical view of Example 1 of the present invention when the heat exchanger is not turned on and a gas-liquid two-phase flow is generated to cause steam penetration;

[0019] Figure 3 This is a vertical view of the fluid cooling to form a pure liquid flow after the heat exchanger is turned on in Example 1 of the present invention;

[0020] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0021] Figure 5 This is a schematic diagram of the structure of Embodiment 3 of the present invention;

[0022] Figure 6 This is a schematic diagram of the structure of Embodiment 4 of the present invention;

[0023] Figure 7 This is a schematic diagram of the structure of Embodiment 5 of the present invention;

[0024] Figure 8 This is a schematic diagram of the structure of Embodiment 6 of the present invention;

[0025] Fig. 9 This is a schematic diagram of the structure of Embodiment 7 of the present invention;

[0026] Fig.10 This is a schematic diagram of the structure of Example 8 of the present invention.

[0027] Among them: 1-U-tube inlet section, 2-U-tube outlet section, 3-heat exchanger, 4-condenser; 5-evaporator, 6-heat exchanger cold side pipe, 7-cold water tank, 8-cross tube, 9-U-tube cooling section, 10-generator, 11-absorber, 12-solution tank; 4001-first section condenser, 4002-second section condenser, 4020-twentieth section condenser, 4101-first stage condenser, 4102-second stage condenser, 4119-nineteenth stage condenser, 4120-twentieth stage condenser; 5001-first section evaporator, 5002-second section evaporator, 5020-twentieth section evaporator, 5101-first stage evaporator, 5102-second stage evaporator, 5119-nineteenth stage evaporator, 5120-twentieth stage evaporator; 7101-first stage evaporator, 7102-second stage evaporator, 7119-nineteenth stage evaporator, 7120-twentieth stage evaporator; 10001-first stage generator, 10002-second stage generator, 10020-twentieth stage generator, 10101-first stage generator, 10102-second stage generator, 10119-nineteenth stage generator, 10120-twentieth stage generator; 11001-first stage absorber, 11002-second stage absorber, 11020-twentieth stage absorber, 11101-first stage absorber, 11102-second stage absorber, 11119-nineteenth stage, 11120-twentieth stage absorber; 12101-first stage solution tank, 12102-second stage solution tank, 12119-nineteenth stage solution tank, 12120-twentieth stage solution tank. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0029] The present invention proposes a pressure isolation device for preventing steam penetration, which can be used as a pressure isolation device between any two cavities in a lithium bromide absorption heat pump or a refrigeration unit where liquid flows from a high-pressure cavity to a low-pressure cavity. Such as a pressure isolation device between a condenser and an evaporator, a pressure isolation device between a generator and an absorber, etc. The following takes the pressure isolation device between a condenser and an evaporator in a lithium bromide absorption heat pump or a refrigeration unit as an example to illustrate the device principle and effect of the present invention.

[0030] like Figure 1 to Figure 3The embodiment 1 of the present invention shown comprises: a U-tube inlet section 1, a U-tube outlet section 2 and a U-tube cooling section 9, wherein the U-tube inlet section 1, the U-tube cooling section 9 and the U-tube outlet section 2 are connected in sequence, the U-tube inlet section 1 is connected to the liquid refrigerant water outlet of the condenser 4 of the high-pressure cavity, and the U-tube outlet section 2 is connected to the liquid refrigerant water inlet of the evaporator 5 of the low-pressure cavity; the generator 10 is connected to the absorber 11 through a solution pipeline, the condenser 4 is connected to the evaporator through a refrigerant water pipeline, the generator 10 is separated and connected to the condenser 4 through a liquid baffle plate, and the absorber 11 is separated and connected to the evaporator 5 through a liquid baffle plate; the solution tank 12 and the refrigerant water tank 7 are placed at the bottom of the unit.

[0031] like Figure 3 As shown, during operation, the fluid in the cooling section 9 of the U-tube isolating device is cooled by heat exchange with the fluid in the cooling section 9 of the U-tube. The outlet pressure of the outlet section 2 of the U-tube corresponds to the saturation temperature of a steam. It is only necessary to reduce the temperature of the fluid in the cooling section 9 of the U-tube to the saturation temperature or lower, so that the fluid in the cooling section 9 and the outlet section 2 of the U-tube can flow in a pure liquid state. The fluid density is 3 to 4 times the fluid density after the existing pressure isolating device forms a two-phase flow, so that the pressure isolation capacity of the entire pressure isolating device (U-tube) is increased by 3 to 4 times, thereby avoiding steam penetration of the pressure isolating device (U-tube). For example, when the outlet pressure of the outlet section 2 of the U-tube corresponds to the saturation temperature of steam of 30°C, it is only necessary to reduce the temperature of the fluid in the U-tube to 30°C or lower, so that the tube can be guaranteed to flow in a pure liquid state.

[0032] There are two ways to implement cooling and heat exchange of the fluid in the U-tube cooling section 9, namely, cooling and heat exchange by a stream of low-temperature fluid through an external heat exchanger or direct immersion cooling and heat exchange inside the unit;

[0033] In Example 1, heat exchange of the fluid in the U-tube cooling section 9 is achieved by cooling and exchanging heat with a low-temperature fluid through an external heat exchanger. Specifically, a heat exchanger 3 is installed outside the U-tube cooling section 9 to exchange heat with the low-temperature fluid, wherein the hot side of the heat exchanger 3 is the U-tube cooling section 9, and the low-temperature fluid in the cold side pipe 6 of the heat exchanger connected to the cold side of the heat exchanger 3 is the low-temperature refrigerant water in the cold water tank 7 in the unit, the cooling water of the unit, or other available cold sources;

[0034] In Example 1, the condenser 4 and evaporator 5 connected to the pressure isolation device are the condenser and evaporator in a single-stage, single-stage lithium bromide absorption heat pump or refrigeration unit. The fluid is cooled and cooled in the U-shaped tube cooling section 9 of the pressure isolation device to achieve fluid supercooling, eliminate the two-phase flow in the tube, improve the pressure isolation capacity of the pressure isolation device (U-shaped tube), and thus prevent steam penetration; in the effect test, the steam penetration problem is effectively avoided.

[0035] like Figure 4The illustrated embodiment 2, the undescribed parts are the same as the embodiment 1;

[0036] In Example 2, the condenser 4 and the evaporator 5 connected to the pressure isolation device are the condenser and the evaporator in a multi-stage lithium bromide absorption heat pump or refrigeration unit (such as the unit disclosed in Chinese Patent No. ZL201410432395.2), that is, the generator 10 and the condenser 4 in the unit are divided into m sections (2≤m≤20), namely, the first section generator 10001, the second section generator 10002...the twentieth section generator 10020, and the first section condenser 4001, the second section condenser 4002... The twentieth-stage condenser 4020; the absorber 11 and the evaporator 5 in the unit are divided into n sections (2≤n≤20), namely the first-stage absorber 11001, the second-stage absorber 11002...the twentieth-stage absorber 11020, and the first-stage evaporator 5001, the second-stage evaporator 5002...the twentieth-stage evaporator 5020; and a pressure isolation device (U-shaped tube) is used between the last-stage condenser (the twentieth-stage condenser 4020) and the first-stage evaporator (the first-stage evaporator 5001) for pressure isolation;

[0037] The U-shaped tube inlet section 1 and the U-shaped tube outlet section 2 are connected to the liquid refrigerant water outlet of the last section condenser and the liquid refrigerant water inlet of the first section evaporator respectively;

[0038] Specifically, when m and n are equal to 20, the U-tube inlet section 1 is connected to the liquid refrigerant water outlet of the twentieth-stage condenser 4020 , and the U-tube outlet section 2 is connected to the liquid refrigerant water inlet of the first-stage evaporator 5001 .

[0039] like Figure 5 The illustrated embodiment 3, the undescribed parts are the same as the embodiment 1;

[0040] In Example 3, the condenser 4 and evaporator 5 connected to the pressure isolation device are the condenser and evaporator of each absorption cycle in a multi-stage lithium bromide absorption heat pump or refrigeration unit. The unit is formed by p-stage (2≤p≤20) lithium bromide absorption machines connected in series, each stage includes an independent generator 10, absorber 11, solution tank 12, condenser 4, evaporator 5, and refrigerant water tank 7; and the condenser and evaporator in each stage are pressure-isolated by a pressure isolation device (U-shaped tube); according to the pressure of the evaporator 5, it is divided into the first stage, the second stage...the pth stage from high to low;

[0041] The U-tube inlet section 1 and the U-tube outlet section 2 of each stage are respectively connected to the condenser and the evaporator of this stage; at the same time, the refrigerant water of the lower refrigerant water tank is used as the cold side fluid of the heat exchanger 3 of this stage, and the refrigerant water of the lowest refrigerant water tank is also used as the cold side fluid of the heat exchanger 3 of this stage.

[0042] Specifically, when p is equal to 20, it includes 20-stage heat exchangers 3, 20-stage condensers 4, 20-stage evaporators 5, 20-stage refrigerant water tanks 7, 20-stage generators 10 (respectively first-stage generator 10101, second-stage generator 10102 ... twentieth-stage generator 10120), 20-stage absorbers 11 (respectively first-stage absorbers 11101, second-stage absorbers 11102 ... twentieth-stage absorbers 11120) and 20-stage solution tanks 12 (respectively first-stage solution tank 12101, second-stage solution tank 12102 ... twentieth-stage solution tank 12120); 20 U-tube inlet sections 1 are respectively connected to the first-stage condenser 4101 of the first stage, the second-stage condenser 4102 of the second stage ... the nineteenth-stage condenser of the 19th (p-1) stage and the twentieth-stage condenser of the 20th (p) stage. The liquid refrigerant water outlet of the condenser 4120, the 20 U-tube outlet sections 2 are respectively connected to the liquid refrigerant water inlets of the first-stage evaporator 5101 of the first stage, the second-stage evaporator 5102 of the second stage...the nineteenth-stage evaporator of the 19th stage and the twentieth-stage evaporator 5120 of the 20th stage; at the same time, the refrigerant water of the second-stage refrigerant water tank 7002 of the second stage is passed into the U-tube pipeline heat exchanger 3 of the first stage, and the third stage is adopted. The refrigerant water of the third-stage refrigerant water tank of the stage is passed into the U-tube pipeline heat exchanger 3 of the second stage...the refrigerant water of the nineteenth-stage refrigerant water tank of the nineteenth stage is passed into the U-tube pipeline heat exchanger 3 of the eighteenth stage, the refrigerant water of the twentieth-stage refrigerant water tank 7020 of the 20th stage is passed into the U-tube pipeline heat exchanger 3 of the 19th stage, and the refrigerant water of the twentieth-stage refrigerant water tank 7020 is also passed into the U-tube pipeline heat exchanger 3 of the 20th stage.

[0043] like Figure 6 The illustrated embodiment 4, the undescribed parts are the same as the embodiment 1;

[0044] In Example 4, the condenser 4 and evaporator 5 connected to the pressure isolation device are the condenser and evaporator of a second-type absorption heat pump unit, wherein the U-tube inlet section 1 is connected to the liquid refrigerant water outlet of the evaporator 5, and the U-tube outlet section 2 is connected to the liquid refrigerant water inlet of the condenser 4.

[0045] like Figure 7 The illustrated embodiment 5, the undescribed parts are the same as the embodiment 1;

[0046] In Example 5, heat exchange of the fluid in the U-tube cooling section 9 is achieved by direct immersion cooling heat exchange inside the unit. Specifically, a cross tube 8 is installed at the position where the U-tube cooling section 9 is connected to the U-tube inlet section 1 and at the position where the U-tube cooling section 9 is connected to the U-tube outlet section 2, respectively. The U-tube cooling section 9 with the cross tube 8 installed is immersed in the refrigerant water of the low-temperature refrigerant water tank 7 in the unit. This embodiment eliminates the heat exchanger 3 by modifying the pressure isolation device (U-tube) pipeline itself, thereby reducing the flow resistance of the U-tube cooling section 9.

[0047] In Example 5, the condenser 4 and the evaporator 5 connected to the pressure isolation device are the condenser and the evaporator in the same single-stage single-stage lithium bromide absorption heat pump or absorption refrigerator.

[0048] like Figure 8 The illustrated embodiment 6, the undescribed parts are the same as the embodiment 5;

[0049] In Example 6, the condenser 4 and the evaporator 5 connected to the pressure isolation device are the condenser and the evaporator in a multi-stage lithium bromide absorption heat pump or a refrigeration unit, that is, the generator 10 and the condenser 4 in the unit are divided into m sections (2≤m≤20), namely the first section generator 10001, the second section generator 10002...the twentieth section generator 10020, and the first section condenser 4001, the second section condenser 4002...the twentieth section condenser 4020; The absorber 11 and the evaporator 5 are divided into n sections (2≤n≤20), namely the first section absorber 11001, the second section absorber 11002...the twentieth section absorber 11020, and the first section evaporator 5001, the second section evaporator 5002...the twentieth section evaporator 5020; and a pressure isolation device (U-shaped tube) is used between the last section condenser (the twentieth section condenser 4020) and the first section evaporator (the first section evaporator 5001) for pressure isolation.

[0050] The U-shaped tube inlet section 1 and the U-shaped tube outlet section 2 are connected to the liquid refrigerant water outlet of the last section condenser and the liquid refrigerant water inlet of the first section evaporator respectively;

[0051] Specifically, when m and n are equal to 20, the U-tube inlet section 1 is connected to the liquid refrigerant water outlet of the twentieth-stage condenser 4020 , and the U-tube outlet section 2 is connected to the liquid refrigerant water inlet of the first-stage evaporator 5001 .

[0052] like Fig. 9 The illustrated embodiment 7, the undescribed parts are the same as the embodiment 5;

[0053] In Example 7, the condenser 4 and evaporator 5 connected to the pressure isolation device are the condenser and evaporator of each absorption cycle in a multi-stage lithium bromide absorption heat pump or refrigeration unit; the unit is formed by p stages (2≤p≤20) of lithium bromide absorption machines connected in series, and each stage includes an independent generator 10, absorber 11, solution tank 12, condenser 4, evaporator 5, and refrigerant water tank 7; and the condenser and evaporator in each stage are pressure-isolated by a pressure isolation device (U-shaped tube); according to the pressure of the evaporator 5, they are divided into the first stage, the second stage...the pth stage from high to low.

[0054] The U-tube inlet section 1 and the U-tube outlet section 2 of each stage are respectively connected to the condenser and the evaporator of this stage; at the same time, the U-tube cooling section 9 of each stage is connected to the refrigerant water tank of the lower stage through a cross pipe, and the refrigerant water in the refrigerant water tank of the lower stage is used to exchange heat with the fluid in the U-tube cooling section 9 of this stage, and the refrigerant water in the refrigerant water tank of the lowest stage is also used as the cold side fluid of the U-tube cooling section 9 of this stage.

[0055] Specifically, when p is equal to 20, it includes 20-stage heat exchangers 3, 20-stage condensers 4, 20-stage evaporators 5, 20-stage refrigerant water tanks 7, 20-stage generators 10 (respectively, the first-stage generator 10101, the second-stage generator 10102 ... the nineteenth-stage generator 10119 and the twentieth-stage generator 10120), 20-stage absorbers 11 (respectively, the first-stage absorber 11101, the second-stage absorber 11102 ... the nineteenth-stage generator 11119 and the twentieth-stage absorber 11120) and 20-stage solution tanks 12 (respectively, The first-stage solution tank 12101, the second-stage solution tank 12102 ... the nineteenth-stage solution tank 12119 and the twentieth-stage solution tank 12120); 20 U-shaped tube inlet sections 1 are respectively connected to the liquid refrigerant water outlets of the first-stage first condenser 4101, the second-stage second condenser 4102 ... the twentieth-stage condenser 4120 of the 20(p) stage, and the 20 U-shaped tube outlet sections 2 are respectively connected to the liquid refrigerant water inlets of the first-stage first evaporator 5101, the second-stage second evaporator 5102 ... the twentieth-stage evaporator 5120 of the 20th stage;

[0056] A transverse tube 8 is installed at the position where each stage of the U-tube cooling section 9 is connected to the U-tube inlet section 1 and the position where it is connected to the U-tube outlet section 2. The two transverse tubes 8 of the first stage are immersed in the second-stage refrigerant water tank 7102 of the second stage, the two transverse tubes 8 of the second stage are immersed in the third-stage refrigerant water tank 7103 of the third stage...the two transverse tubes 8 of the 19th stage are immersed in the 20th stage refrigerant water tank 7120, and the two transverse tubes 8 of the 20th stage are also immersed in the refrigerant water tank 7120 of the 20th stage.

[0057] like Fig.10The illustrated embodiment 8, the undescribed parts are the same as the embodiment 5;

[0058] In Example 8, the condenser 4 and evaporator 5 connected to the pressure isolation device are the condenser and evaporator of a second-type absorption heat pump unit, wherein the U-tube inlet section 1 is connected to the liquid refrigerant water outlet of the evaporator 5, and the U-tube outlet section 2 is connected to the liquid refrigerant water inlet of the condenser 4.

Claims

1. A pressure isolating device for preventing steam penetration, characterized in that: include: A U-tube inlet section, a U-tube outlet section and a U-tube cooling section, wherein the U-tube inlet section, the U-tube cooling section and the U-tube outlet section are connected in sequence, the U-tube inlet section is connected to the high-pressure cavity liquid refrigerant water outlet, and the U-tube outlet section is connected to the low-pressure cavity liquid refrigerant water inlet, and the fluid in the U-tube cooling section is cooled and heat-exchanged, thereby preventing steam penetration from occurring in the pressure isolation device; The cooling and heat exchange of the fluid in the U-tube cooling section is to reduce the temperature of the fluid in the pressure-isolating U-tube cooling section to below the saturation temperature corresponding to the outlet pressure of the U-tube outlet section, ensuring that the fluid in the U-tube cooling section and the outlet section flows in a pure liquid state.

2. A pressure isolating device for preventing steam penetration according to claim 1, characterized in that: The cooling and heat exchange of the fluid in the U-tube cooling section is achieved by: cooling and heat exchange by a low-temperature fluid or direct heat exchange inside the unit.

3. A pressure isolating device for preventing steam penetration according to claim 2, characterized in that: The cooling and heat exchange by a low-temperature fluid is as follows: a heat exchanger is installed outside the U-tube cooling section to exchange heat with the low-temperature fluid, wherein the hot side of the heat exchanger is the U-tube cooling section, and the low-temperature fluid in the cold side pipe of the heat exchanger connected to the cold side of the heat exchanger is the low-temperature refrigerant water in the cold water tank in the unit or the cooling water of the unit.

4. A pressure isolating device for preventing steam penetration according to claim 3, characterized in that: The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and U-tube outlet section of each stage are respectively connected to the condenser and evaporator of this stage; at the same time, the refrigerant water of the lower refrigerant water tank is used as the cold side fluid of the heat exchanger of this stage, and the refrigerant water of the lowest refrigerant water tank is also used as the cold side fluid of the heat exchanger of this stage.

5. A pressure isolating device for preventing steam penetration according to claim 2, characterized in that: The direct heat exchange from inside the unit is as follows: a transverse tube is respectively installed at the position where the U-tube cooling section is connected to the U-tube inlet section and at the position where the U-tube cooling section is connected to the U-tube outlet section, and the U-tube cooling section with the transverse tube installed is immersed in the refrigerant water of the low-temperature refrigerant water tank in the unit; thereby reducing the flow resistance of the U-tube cooling section.

6. A pressure isolating device for preventing steam penetration according to claim 5, characterized in that: The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and U-tube outlet section of each stage are respectively connected to the condenser and evaporator of the same stage; at the same time, the U-tube cooling section of each stage is connected to the refrigerant water tank of the lower stage through a cross pipe, and the refrigerant water in the refrigerant water tank of the lower stage is used to exchange heat with the fluid in the U-tube cooling section of the current stage, and the refrigerant water in the refrigerant water tank of the lowest stage is also used as the cold side fluid of the U-tube cooling section of the current stage.

7. A pressure isolating device for preventing steam penetration according to claim 3 or 5, characterized in that: The unit is a multi-stage lithium bromide absorption heat pump or refrigerator, and the U-tube inlet section and the U-tube outlet section are respectively connected to the liquid refrigerant water outlet of the last stage condenser and the liquid refrigerant water inlet of the first stage evaporator.

8. A pressure isolating device for preventing steam penetration according to claim 3 or 5, characterized in that: The unit is a second-type absorption heat pump, the U-tube inlet section is connected to the evaporator liquid refrigerant water outlet, and the U-tube outlet section is connected to the condenser liquid refrigerant water inlet.

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