Ice-freezing water-proof pressure-maintenance water-stopping device

Abstract

The present invention discloses a frozen water-proof type pressure maintenance water-stop device, which is used to form a water-proof belt in a frozen manner when replacing the soft packing water-stop in the packing box; it includes a freezing heat exchanger, a refrigerator and a temperature measuring device; the refrigerator supplies freezing liquid to the freezing heat exchanger; the freezing heat exchanger is connected to the packing box, and the connection position is provided with a temperature collection hole groove and a working hole groove; the freezing heat exchanger is an annular sleeve with a hollow interior on the shaft of the soft packing water-stop to be replaced, and includes an outer shell, a heat insulation layer, an inner cavity and a sealing plate from the outside to the inside; the inner cavity and the sealing plate surround a heat exchange area for accommodating the freezing liquid, and the sealing plate is made of metal material and is recessed into the inner ring surface of the freezing heat exchanger to form an annular freezing groove. The present invention can create a water-free and safe working environment for replacing damaged soft packing water-stops, and the invented device can also be applied to similar sealing structures, with low cost, short operation time, safety and reliability, and easy operation.

Description

Technical Field

[0001] The invention relates to the technical field of replacement and maintenance of water conservancy projects, and in particular to an ice-freezing water-isolating type pressure-maintenance water-stopping device. Background Art

[0002] In the prior art, if it is necessary to replace and repair the soft filler waterstop in a water conservancy project, the original waterstop (such as packing filler) is usually removed first, and then a new waterstop material is installed. During the process of removing the original waterstop and before installing the new waterstop material, a large amount of water leakage or even water spraying will occur. On the one hand, it is inconvenient for disassembly and assembly work, affecting the installation quality, and in serious cases may endanger the personal safety of the operators. On the other hand, a large amount of water leakage may cause the risk of flooding the machine room.

[0003] In order to avoid the impact of the above-mentioned events, the damaged and replaced soft fillers (such as packing) in water conservancy projects are usually replaced by the existing technology of building cofferdams in the river channel or using maintenance gates to cut off the flow, and then draining the water in the working space to create a waterless working environment. During the construction work, some safety measures must be taken to maintain the waterless environment (such as cutting off the flow to prevent seepage, continuous drainage, etc.). However, the cutting off operation takes a long time, is relatively difficult and risky, has a great impact, and is expensive (the cost of the measures is much greater than the cost of replacing the fillers), especially under certain working conditions where the conditions for cutting off the flow are not yet met.

[0004] Therefore, how to create a water-free and safe working environment for replacing damaged soft filler water-stopping has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0005] In view of the above-mentioned defects of the prior art, the present invention provides an ice-frozen water-proof type pressure-maintenance water-stopping device, the purpose of which is to create a water-free and safe working environment for replacing damaged soft-filling water-stopping; before replacing the soft-filling water-stopping, the device of the present invention is adopted, and the local water body at the front end (river water side) of the soft-filling water-stopping is frozen by utilizing the refrigerator for refrigeration to form an ice-frozen zone water-proofing; after the replacement of the soft-filling water-stopping is completed, the refrigerator is stopped for refrigeration, and the frozen zone at the front end (river water side) of the soft-filling water-stopping will slowly heat up and melt into water, restoring to the intact state before the maintenance, and the device of the invention can also be applied to similar sealing structures (not limited to soft-filling water-stopping), and it has low cost, short operation time, safety and reliability, and easy operation.

[0006] To achieve the above-mentioned purpose, the present invention discloses a frozen water-proof pressure maintenance water-stopping device, which is used to form a water-proof belt in a freezing manner when replacing the soft filler water-stopping in the filler box; it includes a refrigerated heat exchanger, a freezer and a temperature measuring device; the freezer supplies refrigerant to the refrigerated heat exchanger.

[0007] Wherein, the refrigeration heat exchanger is connected to the stuffing box; the position where the stuffing box is connected to the refrigeration heat exchanger is provided with a temperature collection hole slot and a working hole slot;

[0008] The temperature sensor of the temperature measuring device is arranged in the temperature collection hole groove, and is used to collect and observe the temperature of the water body near the refrigeration heat exchanger;

[0009] The working hole is connected to the water body near the refrigeration heat exchanger, and is used to observe whether the water body near the refrigeration heat exchanger is successfully sealed and blocked, or is used for injection and filling of mud fillers and other similar materials;

[0010] The refrigeration heat exchanger is in the form of an annular hollow sleeve on the shaft of the soft filler water stop to be replaced, and comprises an outer shell, a heat insulation layer, an inner cavity and a sealing plate from the outside to the inside;

[0011] The inner cavity and the sealing plate form a heat exchange area for accommodating the refrigerant. The sealing plate is made of metal material and is recessed into the inner annular surface of the refrigeration heat exchanger to form an annular freezing groove.

[0012] Preferably, the soft filler water stop is fixed in the filler box through a pressure cover, and a small groove is provided at the lower part of the outer side of the pressure cover.

[0013] Preferably, the refrigeration heat exchanger is connected to the stuffing box by welding.

[0014] Preferably, the refrigerator and the refrigeration heat exchanger are connected via a refrigerant liquid delivery pipe.

[0015] More preferably, a small partition is provided in the heat exchange area surrounded by the inner cavity and the sealing plate to separate the input port and the output port of the refrigerant delivery pipe.

[0016] Beneficial effects of the present invention:

[0017] (1) The present invention adopts a brand-new freezing technology to seal and stop leakage, which is a conceptual innovation;

[0018] (2) The present invention directly cools the leakproof medium (water, the same below) and uses the characteristics of the medium material to achieve the effects of self-sealing and self-ablation. When the temperature is lowered, ice is frozen to seal and plug leaks. When the temperature is raised and thawed, water is formed for lubrication, which does not affect the operation of the shaft.

[0019] (3) The freezing sealing plugging material of the present invention is water, which is obtained locally and does not need to be replaced, which is environmentally friendly;

[0020] (4) The external structure of the main body of the refrigeration heat exchanger of the present invention is made of stainless steel with low thermal conductivity, and polyurethane foaming agent is used for insulation between the inner and outer rings to reduce energy loss;

[0021] (5) The surface of the rotating shaft of the present invention is wrapped with a material with a low thermal conductivity as a heat insulation layer (such as polyurethane elastomer, stainless steel sleeve (the sleeve and the shaft are bonded with epoxy resin), fiberglass or carbon fiber winding, spray insulation ceramics, etc.), which reduces energy consumption and protects the shaft structure from low temperature brittleness;

[0022] (6) The present invention utilizes conventional methods to temporarily plug water on the downstream side (backwater side), such as temporarily plugging leaks on the outside and rear side of the packing gland, and can also utilize the working hole groove to inject mud-like filler-like soft materials to reduce the amount of water leakage and flow rate during freezing. The actual amount of water leakage can be achieved to 0, effectively avoiding the problem of "flowing water is difficult to freeze", improving freezing efficiency, and reducing energy loss.

[0023] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of an embodiment of the present invention is shown.

[0025] Figure 2 A schematic diagram of the structure of a refrigeration heat exchanger sleeved on a shaft in one embodiment of the present invention is shown.

[0026] Figure 3 Showing the present invention Figure 2 Schematic diagram of the AA section structure.

[0027] Figure 4 Showing the present invention Figure 2 Schematic diagram of the local enlarged structure at point I in the middle.

[0028] Figure 5 A diagram showing an assembly of a model device according to an embodiment of the present invention.

[0029] Figure 6 A schematic diagram showing the on-site installation of a model device according to an embodiment of the present invention is shown.

[0030] Figure 7 A schematic diagram showing the operating status of operating condition 1 of an embodiment of the present invention is shown.

[0031] Figure 8 A schematic diagram showing the operating status of operating condition 2 of an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0032] Example 1

[0033] like Figures 1 to 4As shown, the frozen water-proof type pressure maintenance water-stopping device is used to form a water-proof belt by freezing when replacing the soft packing water-stopping 11 in the packing box 1; it includes a refrigerated heat exchanger 3, a freezer 4 and a temperature measuring device 5; the freezer 4 supplies refrigerant to the refrigerated heat exchanger 3.

[0034] The refrigeration heat exchanger 3 is connected to the stuffing box 1; the position where the stuffing box 1 is connected to the refrigeration heat exchanger 3 is provided with a temperature collection hole slot and a working hole slot 12;

[0035] A temperature sensor 51 of the temperature measuring device 5 is provided in the temperature collection hole groove, which is used to collect and observe the temperature of the water body near the refrigeration heat exchanger 3;

[0036] The working hole 12 is connected to the water body near the refrigeration heat exchanger 3, and is used to observe whether the water body near the refrigeration heat exchanger 3 is successfully sealed and blocked, or is used for injection and filling of mud fillers and other similar materials;

[0037] The refrigeration heat exchanger 3 is an annular hollow sleeve on the shaft 6 of the soft filler water stop 11 to be replaced, and includes a shell 31, a heat insulation layer 32, an inner cavity 33 and a sealing plate 34 from the outside to the inside;

[0038] The inner cavity 33 and the sealing plate 34 form a heat exchange area for accommodating the refrigerant. The sealing plate 34 is made of metal material and is recessed into the inner annular surface of the refrigeration heat exchanger 3 to form an annular freezing groove 35.

[0039] The soft packing waterproof 11 is fixed in the packing box 1 through the pressure cover 2, and a small groove 21 is provided at the lower part of the outer side of the pressure cover 2.

[0040] The refrigeration heat exchanger 3 is connected to the stuffing box 1 by welding.

[0041] The refrigerator 4 and the refrigeration heat exchanger 3 are connected via a refrigerant liquid delivery pipe 41 .

[0042] A small partition 36 is provided in the heat exchange area surrounded by the inner cavity 33 and the sealing plate 34 to separate the input port and the output port of the refrigerant delivery pipe 41 .

[0043] The working principle of the present invention is as follows: the present invention manufactures a set of refrigeration heat exchanger device at the front end (river water side) of the soft packing water stop 11; before replacing and repairing the soft packing water stop 11, conventional measures are taken on the outer side and rear side of the pressure cover 2 to temporarily stop the leakage (reduce the flow rate of the leaking water to create conditions for freezing), and then a refrigerator is used to input -15℃ to -10℃ refrigerant into the refrigeration heat exchanger 3, and circulate it continuously to cool the local water body between the refrigeration heat exchanger 3 and the shaft 6, so that it freezes and forms a frozen zone water isolation, thereby achieving the effect of temporary sealing and water blocking at the front end (river water side) of the soft packing water stop 11.

[0044] Among them, the freezer 4 is a conventional ordinary model, composed of a compressor, a water pump, a thermostat, etc. The refrigerant is ethylene glycol antifreeze, the freezing point temperature is -15°C (can be lower), and the freezing temperature can be set by the thermostat.

[0045] The temperature measuring device 5 is mainly composed of a temperature sensor 51 and a temperature inspection instrument. The temperature sensor 51 collects the temperature of the water near the refrigeration heat exchanger 3 in real time and outputs the signal to the temperature inspection instrument (real-time display). The temperature inspection instrument can also be connected to an external computer to automatically record and save the temperature data;

[0046] Other auxiliary parts include the pipeline between the refrigeration heat exchanger 3 and the refrigerator 4 and its insulation materials, valves, closing bolts of the working holes, etc., which are all conventional parts.

[0047] By adopting this device, a small amount of water between the refrigerated heat exchanger and the shaft can be quickly frozen and sealed within 1.5 to 3 hours after temporary plugging of the leak on the downstream side (backwater side) in advance (the water leakage can be achieved to 0). The freezing and water-proofing time depends on the depth of the freezing tank, the leakage, the insulation measures of the shaft, the ambient temperature, etc.), thus creating a waterless working environment for replacing the water stop, saving time and effort, low cost, easy operation, safety and reliability.

[0048] The principle of freezing water insulation is as follows:

[0049] Principle 1. Three-phase properties of water: Under standard atmospheric pressure, the freezing point of water is 0°C and the boiling point is 100°C;

[0050] Principle 2. Mechanical properties of ice: The compressive strength of ice is 0.3 to 5.5 MPa (within a certain temperature range, the lower the temperature, the higher the strength), the shear strength is about 1 / 2 of the compressive strength, and the bonding strength between ice and steel is about 0.7 to 0.8 MPa;

[0051] Principle 3, ice sealing principle: According to the mechanical properties of ice in Principle 2, the shear strength is the lowest, about 1 / 2 of the compressive strength. In order to improve the pressure-bearing capacity, the shear surface area can be increased, that is, the width of the ice circle can be increased so that the ratio of the ice circle width to the pressure-bearing surface (contact surface) thickness is not less than 2.

[0052] In the present invention, the ice ring formed between the refrigeration heat exchanger and the shaft has a width of 40 mm, and the maximum distance between the sealing plate of the inner cavity of the refrigeration heat exchanger and the shaft is 4 to 5 mm, that is, the maximum pressure-bearing surface (contact surface) thickness of the ice ring is 4 to 5 mm, and the ratio of the shearing area of ​​the ice ring to the pressure contact area is about 8 to 10. Therefore, theoretically, the ice ring can withstand a pressure of at least 0.3 MPa, that is, a head difference of 30 m;

[0053] Principle 4, Freezing process: The freezer continuously inputs -15℃ to -10℃ refrigerant into the refrigeration heat exchanger, and takes away the heat of the water between the shaft and the refrigeration heat exchanger (i.e. in the freezing tank) through the sealing plate of the inner cavity of the refrigeration heat exchanger. The water body continues to cool down. When the water temperature drops below 0℃, the water begins to turn into solid ice, forming an ice ring in the freezing tank to seal and block water, and cut off the water at the front end of the soft filler water stop (river side). After the ice ring is formed, the freezer continues to work until the maintenance is completed, and -15℃ to -10℃ refrigerant is continuously input into the refrigeration heat exchanger. The heat input from the environment around the ice ring and the cooling capacity input by the freezer will reach a balance, maintaining the ice ring in a frozen state at all times to achieve the effect of continuous water blocking and ensure waterless safe working conditions;

[0054] Principle 5, Insulation and efficiency improvement: The outer shell and inner cavity of the refrigeration heat exchanger are filled with polyurethane foam for insulation (thermal conductivity is about 0.023w / mk), and the surface of the shaft is treated with heat insulation, such as polyurethane elastomer (polytetrahydrofuran) coating (thermal conductivity is about 0.06w / mk). The cross-sectional thickness of the inner cavity sealing plate of the refrigeration heat exchanger is small (the heat conduction area on both sides is small), which can effectively insulate and improve freezing efficiency;

[0055] Principle 6, Refrigeration power: Through the insulation measures of Principle 5 above, the main heat transfer methods during the freezing process are: heat conduction and convection heat transfer.

[0056] Heat conduction: The water in the freezing tank conducts heat through the sealing plate and the -15℃ to -10℃ refrigerant in the inner cavity of the freezing heat exchanger. The gap between the inner ring of the front end of the freezing heat exchanger and the shaft is 1 to 2mm (or less). The freezing tank is 1 to 3mm deep and 40mm wide. The volume of water that needs to be cooled and frozen is very small (for example: the thickness of the water ring is h = 2 to 5mm, the width is b = 40mm, the shaft radius is r = 265mm, and the volume of the water ring is V = π ((r + h) 2 -r 2 )b, water circle volume V≈133 to 336 ml).

[0057] Convective heat transfer: After the water in the freezing tank on the inner side of the inner cavity is cooled, there is a temperature difference with the water on both sides. The water will form convection heat transfer through the gap of only 1 to 2mm (or smaller) on both sides of the freezing tank. After the water near the freezing tank seal plate freezes, the ice will cover the surface of the freezing tank seal plate. The unfrozen water on the inside needs to pass through this ice layer for cooling. The thermal conductivity of ice is about 2.23w / mk, so the cooling and freezing process is relatively slow, and the gap of the water convection channel is very small, so the convection heat transfer is relatively small.

[0058] The above two heat transfer methods require a small amount of refrigeration, and the corresponding ordinary refrigerator can meet the requirements, and the refrigeration and freezing time is relatively short;

[0059] Principle 7, frost heave problem: Since the frozen area is local, the freezing process is that the freezing tank slowly freezes toward the axis. The water bodies on both sides of the freezing range are in a state of free expansion rather than a closed environment, so frost heave problem will not occur.

[0060] Example 2

[0061] The present invention has not yet been applied in actual engineering, but in order to verify the feasibility of freezing plugging and obtain more effective data, a series of model tests were carried out with reference to the through-wall water-stopping structure of the bottom shaft-driven flap door (commonly known as steel dam) in water conservancy projects.

[0062] Since there are a lot of test data, this article will not go into details, and only extract the content and data of two tests for illustration. The two tests are as follows: Working condition 1: temporary plugging of the leak, making the leak amount zero and then freezing; Working condition 2: freezing in a simulated state of a small amount of leak, that is, freezing while a small amount of leak occurs.

[0063] 1. Model structure (such as Figure 5 )

[0064] (1) Refrigeration heat exchanger: The freezing tank depth is 3mm and the inner width is 40mm.

[0065] (2) Bottom shaft: The bottom shaft steel tube has a wall thickness of 10 mm and an outer diameter of 510 mm. The outside is wrapped with a 10 mm thick polyurethane elastomer (polytetramethylene furan) jacket for insulation. The total outer diameter of the bottom shaft is 530 mm.

[0066] (3) Freezer: Model: ICA-3L, refrigeration capacity: 3.1KW, minimum freezing temperature: -15°C, refrigerant flow rate: 8.8L / min;

[0067] (4) Temperature measuring device: 4 temperature sensors (Pt100) evenly distributed around the circle, with a measuring range of -15°C to +100°C, 4 to 20 mA signal output, 1 temperature inspection instrument (not shown), and an external computer (not shown) to store temperature data;

[0068] (5) Install 8 M8 screws on the inner side of the bottom shaft to adjust the gap between the bottom shaft and the stuffing box.

[0069] 2. Model on-site installation

[0070] (1) Head difference simulation: front end of the device ( Figure 5 A cylindrical water tank is made (left side in the middle), and tap water is connected to the outside (the tap is at an elevation of about 2.00m). The whole device is placed on the pump level of a pump gate (elevation -3.40m), and the height difference of the position and the pressure of the tap water are used to simulate the head difference. For details, see Figure 6 ;

[0071] (2) The lower part of the model device is supported and fixed by a bracket (not shown in the figure). The structure of the model device itself is the same as before and will not be described again.

[0072] 3. The specific operation steps for working condition 1 are as follows:

[0073] (1) Use "rubber + clamp" on the outside of the gland and stuffing box①, the rear side of the gland ( Figure 7 (right side in the middle) Use retaining ring ② and "rubber + clamp" ③ to temporarily block the downstream side (backwater side) by conventional methods of "holding and squeezing" to make the leakage amount zero, see Figure 7 ;

[0074] (2) Connect the pipeline between the refrigerator and the refrigeration heat exchanger, connect the line between the temperature sensor and the temperature inspection instrument, set the refrigerator temperature to -15°C, start the refrigerator and input refrigerant into the refrigeration heat exchanger, and circulate it continuously;

[0075] (3) During the freezing process, the measured water pressure in the water tank was 0.22 MPa, the ambient temperature was 13.4°C to 13.8°C, the tap water temperature was 16.2°C, and the temperature of the four temperature measuring points around the refrigeration heat exchanger dropped rapidly at the beginning, and then dropped slowly in the later stage. When the temperature of the four points was between -0.9°C and +2.4°C (the temperature measuring points were a certain distance away from the cryosphere), the observation hole screws on the working hole slot were opened, and there was no water leakage. The freezing seal was successfully sealed and water-blocked.

[0076] (4) Remove the conventional temporary water-blocking parts such as "rubber + clamp" ①, retaining ring ② and "rubber + clamp" ③, remove the gland, remove the packing, install the new packing, and install the gland (not completely tightened); during the process of removing and replacing the packing water-blocking, the temperature of the four temperature measuring points is still slowly decreasing;

[0077] (5) After the packing is replaced, turn off the refrigerator and tighten the screws of the observation hole on the working hole slot. The temperature of the four temperature measuring points will rise slowly. Water will leak out of the packing gland. Tighten the gland after it returns to the state before the overhaul.

[0078] (6) During the whole process, the lowest temperature of the inner surface of the bottom shaft was +5.8°C, and the freezing seal and water-blocking took 2.5 hours. After the freezing seal and water-blocking, there was no water leakage during the process of removing and replacing the packing water-stopping.

[0079] 4. The specific operation steps for working condition 2 are as follows:

[0080] (1) On the prototype of working condition 1, loosen the "rubber + clamp" ①, the downstream retaining ring ② and the "rubber + clamp" ③, and adjust the tightness of the packing gland, see Figure 8 , adjust the water tap opening, control the water tank water pressure to 0.12MPa, and measure the water leakage to be 5.2mL / s, which is in the form of flowing water (far exceeding the requirement of dripping without forming a line allowed by the specification);

[0081] (2) Start the refrigerator to supply cold air to the refrigeration heat exchanger, same as working condition 1 (2);

[0082] (3) During the freezing process, the ambient temperature was 12.4°C to 13.2°C, the tap water temperature was 15.9°C, and the temperatures of the four temperature measuring points around the refrigeration heat exchanger dropped rapidly at the beginning and then slowly in the later stage. When the temperatures of the four points were between -2.8°C and +0.8°C (the temperature measuring points were at a certain distance from the cryosphere), the water leakage stopped. The observation hole screws on the working hole slot were opened, and there was no water leakage. The freezing seal was successfully sealed against water.

[0083] (4) The process of removing and replacing the water stop is the same as (4) and (5) of working condition 1;

[0084] (5) During the whole process, the lowest temperature of the inner surface of the bottom shaft was +4.0°C, and the freezing seal and water-blocking took 4.3 hours. After the freezing seal and water-blocking, there was no water leakage during the process of removing and replacing the packing water-stopping.

[0085] Note: Working condition 2 can also be achieved by injecting appropriate soft filler into the observation hole of the working hole slot to reduce the amount of water leakage or completely eliminate water leakage, which can further shorten the freezing time.

[0086] The specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A frozen water-blocking type pressure maintenance water-stopping device, used to form a water-blocking belt by freezing when replacing a soft packing water-stopping (11) in a packing box (1); characterized in that: It comprises a refrigeration heat exchanger (3), a refrigerator (4) and a temperature measuring device (5); the refrigerator (4) supplies refrigeration liquid to the refrigeration heat exchanger (3); The refrigeration heat exchanger (3) is connected to the stuffing box (1); a temperature collection hole slot and a working hole slot (12) are provided at the position where the stuffing box (1) and the refrigeration heat exchanger (3) are connected; The temperature collection hole groove is provided with a temperature sensor (51) of the temperature measuring device (5) for collecting and observing the temperature of the water body near the refrigeration heat exchanger (3); The working hole groove (12) is in communication with the water body near the refrigeration heat exchanger (3) and is used to observe whether the water body near the refrigeration heat exchanger (3) is successfully sealed and blocked, or is used for injection and filling of mud filler; The refrigeration heat exchanger (3) is in the form of an annular sleeve with a hollow interior and is mounted on the shaft (6) of the soft filler water stop (11) to be replaced, and comprises, from the outside to the inside, an outer shell (31), a heat insulation layer (32), an inner cavity (33) and a sealing plate (34); The inner cavity (33) and the sealing plate (34) form a heat exchange area for accommodating the refrigerant. The sealing plate (34) is made of metal material and is recessed into the inner annular surface of the refrigeration heat exchanger (3) to form an annular freezing groove (35).

2. The ice-proof water-stopping device for pressure maintenance according to claim 1 is characterized in that: The soft filler waterproofing (11) is fixed in the filler box (1) via a gland (2), and a small groove (21) is provided at the lower part of the outer side of the gland (2).

3. The ice-isolating pressure maintenance water-stopping device according to claim 1 is characterized in that: The refrigeration heat exchanger (3) is connected to the stuffing box (1) by welding.

4. The ice-proof water-stopping device for pressure maintenance according to claim 1 is characterized in that: The refrigerator (4) and the refrigeration heat exchanger (3) are connected via a refrigeration liquid delivery pipe (41).

5. The ice-isolating pressure maintenance water-stopping device according to claim 4 is characterized in that: A small partition (36) is provided in the heat exchange area surrounded by the inner cavity (33) and the sealing plate (34) to separate the input port and the output port of the refrigerant delivery pipe (41).

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