Large volume multi-stage air compression system and method for large ring die apparatus

Abstract

The application discloses a large-atmosphere multi-stage air supercharging system and method for a large ring mold device, and relates to the technical field of environmental testing. The supercharging system comprises a gas inlet device, a first condenser, a gas-water separator, a second condenser, a contact container, a liquid nitrogen separator, a pressure reducing valve, a supercharging valve and an environmental simulation vacuum container which are connected in sequence. Normal-temperature air is sequentially processed by the gas inlet device, the first condenser, the gas-water separator, the second condenser, the contact container, the liquid nitrogen separator and the pressure reducing valve, so that dry and clean air can be obtained, the dew point temperature is as low as the liquid nitrogen temperature range, and therefore, after the dry and clean air enters the inside of the environmental simulation vacuum container through the supercharging valve, no dew condensation phenomenon occurs, and asphyxiation is not caused, the use safety is ensured, the overall air volume is large, the supercharging is rapid, the liquid nitrogen consumption is small, and the power consumption is small.

Description

TECHNICAL FIELD

[0001] The present application generally relates to the field of environmental test technology, and in particular to an atmospheric multi-stage air repressing system and method for a large ring module device. BACKGROUND

[0002] With the continuous progress of space technology, the environmental simulation test equipment of spacecraft is developing towards large-scale and integration. The environmental simulation test equipment is mainly vacuum thermal test equipment, which uses a vacuum pump set to extract the vacuum container to the required vacuum degree, and then uses a heat sink to provide a cold black background. After the test is completed, the heat sink is warmed up, and the vacuum container is repressing operation. At this time, although there are means to warm up the heat sink, the effect of the heat sink warming up is not uniform, and the equipment such as fixtures and test pieces in the tank cannot be warmed up. When air enters, a large amount of liquid water will condense on the surface of these equipment, not only damaging the equipment in the tank, but also causing difficulty in vacuum pumping due to water molecules adsorbed on the surface of the materials in the tank.

[0003] Currently, the related technology adopts the mode of first passing a small amount of nitrogen, and then repressing with air after the temperature of each device returns to normal. Although this mode can solve the problems of condensation and gas adsorption, it greatly increases the repressing time and reduces the test efficiency, which has limitations. SUMMARY

[0004] In view of the above defects or shortcomings in the related art, it is desirable to provide an atmospheric multi-stage air repressing system and method for a large ring module device, which can efficiently repress and ensure safety in use without causing suffocation of personnel.

[0005] In a first aspect, the present application provides an atmospheric multi-stage air repressing system for a large ring module device, the repressing system comprising a gas inlet device, a first condenser, a gas-water separator, a second condenser, a contact container, a liquid nitrogen separator, a pressure reducing valve, a repressing valve and an environmental simulation vacuum container connected in sequence.

[0006] The gas inlet device is used to compress air to a first preset pressure value and a preset temperature state; the shell side of the first condenser is used to exchange heat with the compressed air at the first preset pressure value and the preset temperature state to obtain compressed air cooled to a first temperature; the gas-water separator is used to separate liquid water from the compressed air at the first temperature; the shell side of the second condenser is used to exchange heat with the compressed air passing through the gas-water separator to obtain compressed air cooled to a second temperature; the contact container is used to directly contact the liquid nitrogen stored therein with the compressed air at the second temperature to obtain compressed air cooled to a third temperature.

[0007] The liquid nitrogen separator is used for separating liquid nitrogen or condensed ice in the compressed air at the third temperature to obtain dry air; the tube passage of the secondary condenser is used for heating the dry air to a fourth temperature; the tube passage of the primary condenser is used for heating the dry air at the fourth temperature to a fifth temperature; the pressure reducing valve is used for reducing the dry air at the fifth temperature to normal pressure, and after isentropic expansion and temperature reduction, the dry air enters the environmental simulation vacuum container through the pressure increasing valve.

[0008] Optionally, in some embodiments of the present application, the air inlet device comprises a filter, an air compressor and a one-way valve connected in sequence, the filter is used for filtering solid particulate impurities in the air, and the air compressor is used for compressing air.

[0009] Optionally, in some embodiments of the present application, the air compressor is an oil-free type air compressor.

[0010] Optionally, in some embodiments of the present application, the displacement of the air compressor is calculated by the following formula:

[0011]

[0012] In formula (1), Q1 represents the displacement of the air compressor, p 0 represents the standard atmospheric pressure, V V represents the volume of the environmental simulation vacuum container, p 1 represents the working pressure of the air compressor, t T represents the pressure increasing time.

[0013] Optionally, in some embodiments of the present application, the working pressure of the air compressor ranges from 0.5 MPa to 1 MPa.

[0014] Optionally, in some embodiments of the present application, the air inlet flow of the filter is calculated by the following formula:

[0015]

[0016] In formula (2), Q2 represents the air inlet flow of the filter.

[0017] Optionally, in some embodiments of the present application, the pressure increasing system further comprises a pressure sensor, a nitrogen valve, a liquid supplement valve and a liquid nitrogen storage tank connected with the contact container, and the liquid nitrogen storage tank supplements liquid nitrogen to the contact container through the liquid supplement valve by self-pressurization.

[0018] Optionally, in some embodiments of the present application, the pressure increasing system further comprises a liquid level meter and a controller connected with the contact container, and the controller controls the liquid supplement valve to open according to the low liquid level signal sent by the liquid level meter, so that the liquid nitrogen storage tank can supplement liquid to the contact container.

[0019] Optionally, in some embodiments of the present application, the primary condenser and the gas-water separator are each provided with a drain valve.

[0020] In a second aspect, the present application provides a method for repressurizing, which is used in the repressurizing system of the first aspect, and the method comprises:

[0021] closing the pressure-reducing valve in the repressurizing system to prevent the high pressure from damaging the vacuum valve, opening the nitrogen valve in the repressurizing system, and passing the nitrogen in the liquid nitrogen storage tank in the repressurizing system into the repressurizing system to use the self-pressurization of the liquid nitrogen storage tank to increase the pressure indication value of the pressure sensor in the repressurizing system to the second preset pressure value;

[0022] opening the drain valve in the repressurizing system and discharging the residual air in the repressurizing system;

[0023] closing the drain valve to use the self-pressurization of the liquid nitrogen storage tank to increase the pressure indication value of the pressure sensor to the first preset pressure value;

[0024] opening the liquid supplement valve in the repressurizing system and supplementing the contact container in the repressurizing system with liquid nitrogen from the liquid nitrogen storage tank;

[0025] opening the repressurizing valve in the repressurizing system and starting the air inlet device of the repressurizing system, opening the pressure-reducing valve, and obtaining the repressurizing air at normal pressure to repressurize the environmental simulation vacuum container.

[0026] From the above technical solutions, it can be seen that the embodiments of the present application have the following advantages:

[0027] The embodiments of the present application provide an atmospheric large-volume multi-stage air repressurizing system and method for large-scale ring mold equipment. The repressurizing system processes the air at normal temperature through the air inlet device, the primary condenser, the gas-water separator, the secondary condenser, the contact container, the liquid nitrogen separator, and the pressure-reducing valve in sequence, can obtain dry and clean air, and the dew point temperature is as low as the liquid nitrogen temperature range. Therefore, after the dry and clean air enters the environmental simulation vacuum container through the repressurizing valve, no dew condensation phenomenon occurs, the liquid nitrogen vaporization amount is small in the process, the air amount in the repressurizing gas is ensured, suffocation is not easy to occur, use safety is ensured, the repressurizing air is air at normal temperature, container dew condensation can be avoided, the overall air volume is large, the repressurizing is rapid, the compression heat of the air compressor and the latent heat of vaporization of the liquid nitrogen are fully utilized, and the advantages of small liquid nitrogen consumption and small power consumption are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0028] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the following drawings:

[0029] Fig. 1A structural block diagram of a large-air-volume multi-stage air compression system for a large ring die device is provided in the embodiments of the present application.

[0030] Fig. 2 A specific example of a large-air-volume multi-stage air compression system for a large ring die device is provided in the embodiments of the present application.

[0031] Fig. 3 A compression process schematic diagram of a large-air-volume multi-stage air compression system for a large ring die device is provided in the embodiments of the present application.

[0032] Reference signs:

[0033] 100-compression system, 101-inlet device, 1011-filter, 1012-air compressor, 1013-check valve, 102-first-stage condenser, 103-gas-water separator, 104-second-stage condenser, 105-contact container, 1051-pressure sensor, 1052-gas nitrogen valve, 1053-liquid supplement valve, 1054-liquid nitrogen storage tank, 1055-liquid level meter, 1056-controller, 106-liquid nitrogen separator, 107-pressure reducing valve, 108-compression valve, 109-environmental simulation vacuum container, 110-drain valve. DETAILED DESCRIPTION

[0034] In order to make the personnel in the art better understand the scheme of the present application, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person of ordinary skill in the art without making creative efforts fall within the protection scope of the present application.

[0035] The terms “first”, “second”, “third”, “fourth” and the like (if any) in the specification and claims of the present application and the above drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described can be implemented in an order other than that illustrated or described herein.

[0036] In addition, the terms “include” and “have” and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or modules does not have to be limited to those steps or modules clearly listed, but can include other steps or modules that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the case of no conflict.

[0038] For the convenience of understanding and description, the following is through Figs. 1 to 3 The atmospheric large multi-stage air supercharging system and method for large ring die equipment provided by the embodiments of the present application are described in detail.

[0039] Please refer to Fig. 1 , which is a structural block diagram of an atmospheric large multi-stage air supercharging system for large ring die equipment provided by the embodiments of the present application. The supercharging system 100 includes a gas inlet device 101, a first condenser 102, a gas-water separator 103, a second condenser 104, a contact container 105, a liquid nitrogen separator 106, a pressure reducing valve 107, a supercharging valve 108 and an environmental simulation vacuum container 109 connected with each other. For example, the ring die equipment in the embodiments of the present application can be a vacuum thermal environmental simulation test equipment.

[0040] Among them, ① the gas inlet device 101 can compress air to a first preset pressure value and a preset temperature state, for example, the first preset pressure value is 1 MPa, and the preset temperature is 300℃. The advantage of such setting is that high-pressure gas is beneficial to increase the heat exchange efficiency of the subsequent condenser, and at the same time, the supercharging time is reduced. Further, the gas inlet device 101 can include a filter 1011, an air compressor 1012 and a one-way valve 1013 connected in sequence. The filter 1011 can filter out solid particulate impurities in the air, purify the supercharged air, and at the same time, avoid damaging the air compressor 1012 and other equipment. The air compressor 1012 can compress air, for example, the air compressor 1012 can be an oil-free type air compressor, which is selected according to the volume size and supercharging time of the environmental simulation vacuum container 109 to be supercharged, and the filter 1011 is determined according to the flow of the air compressor 1012, and the one-way valve 1013 can prevent high-pressure gas from flowing back during the supercharging process.

[0041] ② The shell side of the first condenser 102 can exchange heat with the compressed air at the first preset pressure value and the preset temperature state, so as to obtain compressed air cooled to a first temperature, for example, the first temperature is below 10℃. In this process, most of the water in the compressed air is condensed into liquid water. When the liquid water accumulates to a certain amount, it is discharged through the drain valve 110 at the bottom of the first condenser 102.

[0042] ③ The gas-water separator 103 can separate the liquid water in the compressed air at the first temperature, so as to avoid condensation in the second condenser 104. At the same time, the bottom of the gas-water separator 103 can also be provided with a drain valve 110 to discharge the liquid water through the drain valve 110 when the liquid water accumulates too much.

[0043] The shell side of the secondary condenser 104 can further cool and exchange heat with the compressed air passing through the gas-water separator 103, so as to obtain compressed air cooled to a second temperature, for example, the second temperature is about 120K, close to the liquid nitrogen temperature range. This process can further remove the moisture in the compressed air and reduce the temperature, thereby reducing the consumption of liquid nitrogen when the compressed air contacts the liquid nitrogen.

[0044] The contact container 105 can directly contact the liquid nitrogen stored therein with the compressed air at the second temperature, so as to obtain compressed air cooled to a third temperature. Since the condenser inevitably has uneven heat exchange due to the large amount of air used, in order to avoid the situation that impurities are left in the compressed air and to utilize the vaporized liquid nitrogen, the air and the liquid nitrogen are directly contacted in the contact container 105. The contact container 105 is a pressure container with good heat preservation performance, and the container contains liquid nitrogen. The compressed air flows into the contact container 105 from the bottom and fully contacts the liquid nitrogen. In this process, the compressed air is cooled to the liquid nitrogen temperature range. The boiling point of 1MPa liquid nitrogen is about 105K. At this temperature, the dew point temperature of the compressed air can be reduced to the liquid nitrogen temperature range, so that dewing does not occur even if the hot sink and the test piece are not warmed up. At the same time, the liquid nitrogen absorbs heat and vaporizes to produce nitrogen gas. The lower the temperature of the compressed air passing through the secondary condenser 104, the less the amount of liquid nitrogen vaporization, and the less the consumption of liquid nitrogen.

[0045] Further, the repressing system 100 in the embodiment of the present application can further include a pressure sensor 1051, a nitrogen valve 1052, a liquid supplement valve 1053 and a liquid nitrogen storage tank 1054 connected with the contact container 105. The liquid nitrogen storage tank 1054 can supplement the liquid nitrogen to the contact container 105 through the liquid supplement valve 1053 by self-pressurization. For example, the liquid nitrogen storage tank 1054 can increase its pressure to 1MPa, so as to ensure that the liquid nitrogen flows into the contact container 105 smoothly.

[0046] Further, the repressing system 100 in the embodiment of the present application can further include a liquid level meter 1055 and a controller 1056 connected with the contact container 105. The controller 1056 can control the liquid supplement valve 1053 to open according to the low liquid level signal sent by the liquid level meter 1055, so as to enable the liquid nitrogen storage tank 1054 to supplement the liquid to the contact container 105.

[0047] The liquid nitrogen separator 106 can separate the liquid nitrogen or condensed ice at the third temperature from the compressed air, that is, separate the liquid nitrogen or a small amount of ice condensed from water from the mixed gas stream of air and nitrogen, so as to obtain dry air. Since the liquid nitrogen separated here will evaporate slowly and the amount of ice will not be large, the liquid nitrogen separator 106 does not need to be provided with a structure for leading out the solid and liquid.

[0048] The tube passage of the secondary condenser 104 can increase the dry air to the fourth temperature. After passing through the liquid nitrogen separator 106, the compressed air is absolutely dry and clean high-pressure low-temperature air, and the nitrogen content is slightly increased. However, due to the cooling of the secondary condenser 104, the nitrogen gasification is not too much, and thus the nitrogen content is not too high, and the temperature is about 105K. The low-temperature gas entering the tube passage of the secondary condenser 104 provides cold energy for the compressed air, and at the same time, the low-temperature gas is moderately heated to prepare for the primary condensation. After passing through the secondary condenser 104, the dry air is increased to about 0℃, and due to the inevitable heat leakage in the process, the temperature of the dry air after passing through the secondary condenser 104 should be slightly lower than 0℃, so as to ensure that there is enough cold energy when entering the primary condenser 102.

[0049] The tube passage of the secondary condenser 104 can increase the dry air to the fourth temperature. After passing through the liquid nitrogen separator 106, the compressed air is absolutely dry and clean high-pressure low-temperature air, and the nitrogen content is slightly increased. However, due to the cooling of the secondary condenser 104, the nitrogen gasification is not too much, and thus the nitrogen content is not too high, and the temperature is about 105K. The low-temperature gas entering the tube passage of the secondary condenser 104 provides cold energy for the compressed air, and at the same time, the low-temperature gas is moderately heated to prepare for the primary condensation. After passing through the secondary condenser 104, the dry air is increased to about 0℃, and due to the inevitable heat leakage in the process, the temperature of the dry air after passing through the secondary condenser 104 should be slightly lower than 0℃, so as to ensure that there is enough cold energy when entering the primary condenser 102.

[0050] The pressure-reducing valve 107 can reduce the dry air at the fifth temperature to normal pressure, and after isentropic expansion and cooling, the dry air enters the environment simulation vacuum container 109 through the pressure-restoring valve 108. The air after passing through the pressure-reducing valve 107 is expanded and cooled, that is, after being reduced to normal pressure, the temperature is also restored to room temperature.

[0051] It should be noted that the air obtained after the above processing process is dry and clean, the humidity is extremely low, the dew point temperature is lower than 110K, the diameter of the impurities in the air is ≤3μm, and the proportion of nitrogen is not higher than 90%, and the pressure-restored gas is normal-temperature air, so that the internal condensation of the environment simulation vacuum container is not caused, and suffocation is not easily caused. In addition, by fully utilizing the latent heat of vaporization of liquid nitrogen, the liquid nitrogen consumption can be small, and the pressure-restored gas amount can be large.

[0052] The working principle of the pressure-restoring system 100 in the embodiment of the present application will be described in detail below in combination with FIG. 1. Fig. 2 Firstly, the pressure-restoring system 100 takes air from the atmosphere, and the air enters the air compressor 1012 after passing through the filter 1011, and is compressed to high temperature and high pressure in the air compressor 1012. The working pressure of the air compressor 1012 is in the range of 0.5MPa~1MPa, and is preferably 1MPa. p 1, and the displacement Q1 of the air compressor is calculated according to the following formula, that is:

[0053]

[0054] In formula (1), Q1 represents the displacement of the air compressor, and the unit is m3 / s. m 3 / min ;p 0 represents standard atmospheric pressure, i.e. 101325 Pa; V represents the volume of the environment simulation vacuum container, with the unit of m 3 ; p 1 represents the working pressure of the air compressor, with the unit of Pa; t represents the compression time, with the unit of min .

[0055] The air compressor 1012 is selected to be a clean and oil-free air compressor, so as to prevent oil stains from entering the compression system 100. The filter 1011 is selected according to the air inlet flow rate, and the air inlet flow rate Q2 is calculated according to the air compressor displacement Q1, i.e.

[0056]

[0057] In formula (2), Q2 represents the air inlet flow rate of the filter, with the unit of m 3 / min.

[0058] Further, the process of the air compressor 1012 compressing air is an isentropic process, and the temperature T1 of the compressed air is calculated according to the following formula, i.e.

[0059]

[0060] In formula (3), T1 represents the temperature of the compressed air, with the unit of K; T0 represents the temperature of the ambient air, which is approximately 300 K; gamma represents the specific heat ratio of the gas, which is dimensionless, and the specific heat ratio of air is 1.4.

[0061] When compressed to 1 MPa, the temperature T1 of the compressed air is about 580 K (≈300℃). Then, the high-temperature and high-pressure air flows into the shell side of the primary condenser 102 to be condensed and dehydrated. The mass m H2O of water in the saturated air is calculated according to the following formula, i.e.

[0062]

[0063] In formula (4), m H2O represents the mass of water, with the unit of kg; represents the saturated vapor pressure of water, with the unit of Pa; M H2O represents the molecular weight of water; p air represents the air pressure, with the unit of Pa; M air represents the molecular weight of air; m air represents the mass of air, with the unit of kg.

[0064] The saturated vapor pressure of water at 300K is 3361Pa, and according to formula (4), the water vapor in unit mass (1kg) of saturated air is about 20.6g, accounting for 2%. At 10℃, the saturated vapor pressure of water is about 1000Pa, and according to formula (4), the water vapor at this time is about 0.8g.

[0065] Further, the high-temperature compressed air in the primary condenser 102 and the 0℃-level compressed air flowing out of the secondary condenser 104 are subjected to heat exchange, and the heat exchange efficiency can be greatly improved by increasing the air pressure. In the cooling process, the heat Q3 released by the compressed air per unit time is calculated according to the following formula:

[0066]

[0067] In formula (5), Q3 represents the heat released by the compressed air, with the unit of kJ / min; C Cp represents the specific heat capacity, with the unit of J / (kg•℃); m represents the mass flow rate of the compressed air, with the unit of kg / min; and △T represents the temperature change value, with the unit of K.

[0068] The heat Q4 released by the water condensation is calculated according to the following formula:

[0069]

[0070] In formula (6), Q4 represents the heat released by the water condensation per unit time in the compressed air, with the unit of kJ / min; r L represents the latent heat of vaporization of water, with the unit of J / kg, and m represents the mass of the condensed water per unit time, with the unit of kg / min.

[0071] For unit mass of the compressed air, the heat released in the process of cooling from 580K to 10℃ is about 307kJ, and the phase change heat release is about 40kJ, totaling about 347kJ. Most of the water in the compressed air is condensed into liquid water, and when the liquid water accumulates to a certain amount, it is discharged through the drain valve 110 at the bottom of the primary condenser 102.

[0072] Exemplarily, the primary condenser 102 in the embodiment of the present application can be a tubular heat exchanger, which is designed in a counter-flow manner, with the compressed air in the shell side and the dry air passing through the contact container 105 and the secondary condenser 104 in the tube side. The compressed air is cooled and the water vapor is condensed in the shell side, and the dry air is heated in the tube side. The heat exchange capacity of the heat exchanger can be calculated according to the air flow rate obtained by formula (1) and the unit mass heat exchange amount obtained by formula (5), and the heat exchange area of the heat exchanger can be calculated according to the temperature difference between the two ends of the heat exchanger and the thermal resistance of the heat exchanger, and then the corresponding heat exchanger can be designed. Since the design of the heat exchanger is a mature technology, it will not be described here.

[0073] The compressed air passing through the primary condenser 102 flows into the gas-water separator 103 to separate the liquid water. The gas-water separator 103 is selected from a product with a drain valve 110, so that it can be discharged by reducing pressure when the liquid water accumulates too much.

[0074] The compressed air passing through the gas-water separator 103 flows into the shell side of the secondary condenser 104 to further cool and exchange heat, so that the temperature of the compressed air is reduced to about 120K, close to the liquid nitrogen temperature zone. According to formula (5) and formula (6), the heat release of 1 kg of compressed air in this process is about 173kJ.

[0075] The secondary condenser 104 can also be selected as a tube heat exchanger, which is designed in counter flow, the compressed air flows in the shell side, and the dry air passing through the contact container 105 flows in the tube side. The compressed air is cooled in the shell side, and the dry air is heated in the tube side. Similarly, as the primary condenser 102, the heat exchange capacity of the heat exchanger can be calculated according to the air flow obtained by formula (1) and the heat exchange capacity per unit mass obtained by formula (5), and the heat exchange area of the heat exchanger can be calculated according to the temperature difference between the two ends of the heat exchanger and the thermal resistance of the heat exchanger, and then the corresponding heat exchanger can be designed. Since most of the water is discharged in the primary condenser 102, the secondary condenser 104 does not need to be provided with a pressure reducing drain valve 110, that is, it can be cleaned regularly after the end of the compression process.

[0076] The water content in the compressed air passing through the secondary condenser 104 is very small and can be ignored, but due to the large amount of air used, in order to avoid the presence of uneven heat exchange in the condenser, causing residual impurities in the compressed air, and at the same time to utilize the vaporized liquid nitrogen, the air and liquid nitrogen are directly contacted in the contact container 105. In this process, the compressed air is cooled from 120K to 105K, and according to formula (5), the heat release of 1 kg of compressed air is about 18kJ. The liquid nitrogen absorbs heat and vaporizes into gaseous nitrogen, and according to formula (6), the gaseous nitrogen generated by absorbing heat is about 0.1kg. After mixing, the nitrogen content is about 88%. The lower the temperature of the compressed air passing through the secondary condenser 104, the less the liquid nitrogen vaporizes, the less the liquid nitrogen consumption, and the lower the nitrogen content in the mixed gas. In addition, the contact container 105 can be selected as a pressure container with a vacuum insulation layer to reduce the vaporization of liquid nitrogen due to heat leakage, and a container with a larger diameter should be selected to prevent liquid overflow.

[0077] After the air and nitrogen are mixed in the contact container 105, they flow into the liquid nitrogen separator 106, which can separate the liquid nitrogen or a small amount of water condensed into ice from the air and nitrogen mixture. The liquid nitrogen separator 106 can be selected as a cyclone separator, and its type is determined according to the flow and pressure drop.

[0078] After passing through the liquid nitrogen separator 106, the compressed air is absolutely dry and clean high-pressure low-temperature air, at this time the nitrogen content is slightly increased, but the cooling effect of the secondary condenser 104 is improved, and the liquid nitrogen vaporization will not be too much, and the temperature is about 105K. After the low-temperature gas enters the tube of the secondary condenser 104, it provides cold energy for the compressed air, and at the same time, it is moderately heated to prepare for the primary condensation. According to formula (5), it can be calculated that after the heat released by the absorption of the compressed air in the secondary condenser 104, the temperature of the mixed dry air can be increased to about -15°C, which can provide the condensation cold energy for the primary condenser 102.

[0079] Further, according to formula (5), it can be calculated that after the heat released by the absorption of the compressed air in the primary condenser 102, the temperature of the mixed dry air can be increased to about 290°C, close to 300°C.

[0080] Further, after the high-temperature dry air flows out of the primary condenser 102, it is depressurized to normal pressure through the pressure reducing valve 107, and this process can also be an approximate isentropic process. According to formula (3), the high-temperature high-pressure dry air at 290°C and 1MPa isentropically expanded to normal pressure, and the temperature is about 18°C, close to room temperature, at this time it will not be damaged due to too low temperature. Finally, the dry air enters the environmental simulation vacuum container 109 through the pressure increasing valve 108.

[0081] As another aspect, the embodiment of the present application provides a pressure increasing method, which can be used for the pressure increasing system 100 of the corresponding embodiment. Figs. 1~2 As shown in the pressure increasing system 100 of the corresponding embodiment, the pressure increasing method specifically comprises the following steps: Fig. 3

[0082] S101, close the pressure reducing valve in the pressure increasing system to prevent high pressure from damaging the vacuum valve, open the nitrogen valve in the pressure increasing system, and pass the nitrogen in the liquid nitrogen storage tank in the pressure increasing system into the pressure increasing system to use the self-pressurization of the liquid nitrogen storage tank to increase the pressure indication value of the pressure sensor in the pressure increasing system to a second preset pressure value.

[0083] For example, the second preset pressure value in the embodiment of the present application can be 1.2atm.

[0084] S102, open the drain valve in the pressure increasing system, and drain the residual air in the pressure increasing system.

[0085] S103, close the drain valve to use the self-pressurization of the liquid nitrogen storage tank to increase the pressure indication value of the pressure sensor to a first preset pressure value.

[0086] For example, the first preset pressure value in the embodiment of the present application can be 1MPa.

[0087] ​S104, open the liquid supplement valve in the repressing system, and supplement the contact container in the repressing system through the liquid nitrogen storage tank.

[0088] S105, open the repressing valve in the repressing system, start the air inlet device of the repressing system, open the decompression valve, and obtain the repressing air at normal pressure to repress the environmental simulation vacuum container.

[0089] It should be noted that the description of the same steps or the same content in the embodiments of the present application and other embodiments can refer to the description in other embodiments, and will not be repeated here.

[0090] The atmospheric multi-stage air repressing system and method for large ring mold equipment provided by the embodiments of the present application can obtain dry and clean air by sequentially processing the air at normal temperature through the air inlet device, the first condenser, the gas-water separator, the second condenser, the contact container, the liquid nitrogen separator, and the decompression valve, and the dew point temperature is as low as the liquid nitrogen temperature range. Therefore, after the dry and clean air enters the environmental simulation vacuum container through the repressing valve, no dewing phenomenon occurs, the liquid nitrogen vaporization amount is small in the process, the air amount in the repressing gas is ensured, and suffocation is not easy to occur, use safety is ensured, the repressing air is air at normal temperature, which can avoid container dewing, the overall air amount is large, the repressing is rapid, the compression heat of the air compressor and the latent heat of vaporization of the liquid nitrogen are fully utilized, and the advantages of small liquid nitrogen consumption and small power consumption are achieved.

[0091] The above description is only the preferred embodiments of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the scope of the application involved in the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or equivalent features without departing from the inventive concept. For example, the technical solutions formed by the mutual replacement of the above features and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A large-volume multi-stage air repressurization system for large-scale ring mold equipment, characterized in that, The repressurization system includes an air intake device, a primary condenser, a gas-liquid separator, a secondary condenser, a contact container, a liquid nitrogen separator, a pressure reducing valve, a repressurization valve, and an environmental simulation vacuum container connected to each other. The air intake device is used to compress air to a first preset pressure value and a preset temperature state; the shell side of the first-stage condenser is used to exchange heat with the compressed air at the first preset pressure value and preset temperature state to obtain compressed air cooled to the first temperature. The gas-water separator is used to separate liquid water from the compressed air at the first temperature; the shell side of the secondary condenser is used to exchange heat with the compressed air that has passed through the gas-water separator to obtain compressed air cooled to the second temperature. The contact container is used to directly contact the liquid nitrogen stored inside with the compressed air at the second temperature to obtain compressed air cooled to the third temperature. The liquid nitrogen separator is used to separate liquid nitrogen or condensed ice from the compressed air at the third temperature to obtain dry air; The tube side of the secondary condenser is used to heat the dry air to a fourth temperature; the tube side of the primary condenser is used to heat the dry air at the fourth temperature to a fifth temperature; the pressure reducing valve is used to reduce the pressure of the dry air at the fifth temperature to atmospheric pressure, and after isentropic expansion and cooling, it enters the environmental simulation vacuum container through the pressure reducing valve.

2. The pressure-reinforcing system according to claim 1, characterized in that, The air intake device includes a filter, an air compressor, and a one-way valve connected in sequence. The filter is used to remove solid particulate impurities from the air, and the air compressor is used to compress the air.

3. The pressure-reinforcing system according to claim 2, characterized in that, The air compressor is an oil-free air compressor.

4. The pressure-reinforcing system according to claim 2, characterized in that, The displacement of the air compressor is calculated using the following formula: In equation (1), Q1 represents the air compressor displacement, p0 represents the standard atmospheric pressure, V represents the volume of the environmental simulation vacuum container, p1 represents the working pressure of the air compressor, and t represents the repressurization time.

5. The pressure-reinforcing system according to claim 4, characterized in that, The working pressure range of the air compressor is 0.5MPa to 1MPa.

6. The pressure-reinforcing system according to claim 4, characterized in that, The air intake flow rate of the filter is calculated using the following formula: In equation (2), Q2 represents the filter inlet flow rate.

7. The pressure-reinforcing system according to any one of claims 1 to 6, characterized in that, The pressure recovery system also includes a pressure sensor, a gas nitrogen valve, a replenishment valve, and a liquid nitrogen storage tank connected to the contact container. The liquid nitrogen storage tank uses self-pressurization to replenish liquid nitrogen to the contact container through the replenishment valve.

8. The pressure-reinforcing system according to claim 7, characterized in that, The pressure recovery system also includes a level gauge and a controller connected to the contact container. The controller is used to control the liquid replenishment valve to open according to the low liquid level signal sent by the level gauge, so that the liquid nitrogen storage tank can replenish the contact container.

9. The pressure-reinforcing system according to claim 8, characterized in that, Both the primary condenser and the gas-liquid separator are equipped with drain valves.

10. A method for applying pressure, characterized in that, The method is used in the pressure-reinforcing system of claim 9, and the method includes: Close the pressure reducing valve in the repressurization system to prevent high pressure from damaging the vacuum valve, open the gas nitrogen valve in the repressurization system, and introduce nitrogen from the liquid nitrogen storage tank in the repressurization system into the repressurization system so as to use the self-pressurization of the liquid nitrogen storage tank to raise the pressure indication value of the pressure sensor in the repressurization system to the second preset pressure value. Open the drain valve in the pressurization system and release the residual air in the pressurization system; Close the drain valve to use the self-pressurization of the liquid nitrogen storage tank to raise the pressure indication value of the pressure sensor to the first preset pressure value; Open the replenishment valve in the repressurization system and replenish the contact container in the repressurization system through the liquid nitrogen storage tank; Open the repressurization valve in the repressurization system, start the air intake device of the repressurization system, and open the pressure reducing valve to obtain atmospheric pressure repressurized air to repressurize the environmental simulation vacuum container.

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