Distributed liquid nitrogen cold energy recovery device

Abstract

The utility model relates to a distributed liquid nitrogen cold energy recovery device which mainly comprises an air compression purification system, a heat exchange cold box, a liquid air storage tank, a liquid nitrogen pump and a liquid nitrogen storage tank. The air compression and purification system comprises an air compressor, a freezing dryer and an adsorption dryer; the heat exchange cold box is composed of a main heat exchanger, a flash evaporator and a subcooler, and recovery and utilization of liquid nitrogen cooling capacity are achieved through the components. According to the utility model, the PLC system is used for automatically controlling operation parameters, and the cooling capacity during liquid nitrogen vaporization is used for liquid air production, so that steam required by liquid nitrogen vaporization is saved, and the liquid air production cost is reduced. The device adopts a skid-mounted design, and is small in size, convenient to install and suitable for cold energy recovery of liquid nitrogen dispersion small users.

Description

Technical Field

[0001] The utility model belongs to the technical field of liquid nitrogen cold energy recovery and relates to a distributed liquid nitrogen cold energy recovery device. Background Art

[0002] Liquid nitrogen is the form of nitrogen in a liquefied state, which is a white liquid. It is widely used in metallurgy, chemical industry, glass manufacturing, electronic manufacturing, food preservation, and other fields. With the rapid development of my country's modernization, the application of nitrogen is becoming more and more extensive. In addition to metallurgy and chemical industry, liquid nitrogen users are showing a trend of small quantity and dispersion. The total expansion ratio of liquid nitrogen is as high as 650:1. Liquid is more economical than gas transportation. Because of this advantage, it is widely used in industrial production and food preservation in modern times. In the industrial production process, nitrogen is mainly used because of its inactive chemical properties. It is usually used as a protective gas, sealing gas, power gas source, etc. Liquid nitrogen usually uses an air-temperature vaporizer to vaporize the liquid. In the process of liquid nitrogen vaporization, a large amount of cold is directly discharged into the air and is not recycled. Cold recovery is to recover the cold generated by the vaporization of liquid nitrogen and produce liquid air to save some electricity.

[0003] The existing cold recovery technology is mainly aimed at large-scale cold recovery, and the technology is relatively mature. However, it is more difficult to achieve decentralized, small-volume cold recovery, and there is currently no mature device. Utility Model Content

[0004] In view of this, the purpose of the utility model is to solve the problem of cold recovery and utilization of liquid nitrogen vaporization of dispersed users, and provide a distributed liquid nitrogen cold recovery device.

[0005] In order to achieve the above object, the utility model provides the following technical solutions:

[0006] A distributed liquid nitrogen cooling capacity recovery device, comprising an air compression purification system, a heat exchange cold box, a liquid air storage tank, a liquid nitrogen pump, and a liquid nitrogen storage tank;

[0007] The air compression purification system comprises an air compressor, a cold dryer, and an adsorption dryer; the adsorption dryer is provided with two groups of inlets and outlets, namely, an air inlet and an air outlet, and a desorption gas inlet and a desorption gas outlet;

[0008] The heat exchange cold box includes a main heat exchanger, a flash evaporator, and a subcooler; the main heat exchanger is provided with three groups of inlets and outlets, namely, a first inlet and a first outlet of the main heat exchange, a second inlet and a second outlet of the main heat exchange, and a third inlet and a third outlet of the main heat exchange; the flash evaporator is provided with a flash feed inlet, a flash liquid outlet, and a flash exhaust outlet; the subcooler is provided with two groups of inlets and outlets, namely, a first subcooling inlet and a first subcooling outlet, and a second subcooling inlet and a second subcooling outlet;

[0009] The air compressor, the cold dryer, and the adsorption dryer are connected in series in sequence, the cold dryer is connected to the air inlet of the adsorption dryer, the air outlet of the adsorption dryer is connected to the first inlet of the main heat exchange, the first outlet of the main heat exchange is connected to the flash feed inlet, the flash liquid outlet is connected to the first subcooling inlet, and the flash exhaust port is connected to the second inlet of the main heat exchange; the first subcooling outlet leads to two paths, one path is connected to the liquid-air storage tank, and the other path is connected to the second subcooling inlet, the second subcooling outlet is connected to the second inlet of the main heat exchange, and the second outlet of the main heat exchange is connected to the analytical gas inlet;

[0010] The liquid nitrogen storage tank is connected to the third inlet of the main heat exchange through a liquid nitrogen pump, and the third outlet of the main heat exchange is connected to the user nitrogen pipeline network. The cold capacity of the liquid nitrogen is used for the preparation of liquid air through the main heat exchanger.

[0011] Furthermore, throttle valves are provided between the first outlet of the main heat exchange and the flash feed inlet, between the first subcooling outlet and the second subcooling inlet, between the first subcooling outlet and the liquid-air storage tank, and between the flash exhaust port and the second inlet of the main heat exchange.

[0012] Furthermore, the liquid air storage tank is also provided with a steam outlet, which is connected to the second inlet of the main heat exchange.

[0013] Furthermore, the air compressor is a screw compressor, adopts single-stage compression, oil-free water lubrication, has its own air cooler, and is equipped with a permanent magnet motor, a vector inverter, and a water purification system.

[0014] Furthermore, the distributed liquid nitrogen cooling capacity recovery device is integrated as a whole on the skid-mounted frame.

[0015] Furthermore, the cold dryer realizes refrigeration and dehumidification through a refrigeration cycle, and the refrigerant is R134, R407, R717 or R22.

[0016] Furthermore, the adsorption dryer is a double-layer bed structure, and the adsorbent is activated alumina and 13X molecular sieve. The adsorption dryer adopts a long-cycle regeneration cycle, a switching cycle of 12 hours, and a low-heat regeneration method.

[0017] Furthermore, the air compressor, cold dryer and adsorption dryer are separately integrated and assembled into one body.

[0018] The beneficial effects of the utility model are:

[0019] 1. The utility model transfers the cold released by the vaporization of liquid nitrogen from dispersed users to the air, liquefies it into liquid air, and makes full use of the cold energy of liquid nitrogen. On the one hand, it can save a large amount of steam required for the vaporization of liquid nitrogen, and on the other hand, it can produce liquid air products at a low cost; there is no emission of waste gas, sewage and dust during the production process, which reduces energy consumption, improves economic benefits, and avoids the waste of cold during vaporization.

[0020] 2. The utility model utilizes the cold energy provided by the vaporization of liquid nitrogen to liquefy air into liquid air, and introduces a flash evaporator in the middle to recycle the flash vapor, thereby reducing the product throttling vaporization rate and increasing the liquid output.

[0021] 3. The utility model adopts skid-mounted installation, which is small in size and easy to install, and is conducive to the recovery of cold energy of small users with dispersed liquid nitrogen; the dispersed cold energy can be fed back to the air separation production link through the intermediate product of liquid air, so as to promote energy saving and consumption reduction of large-scale air separation.

[0022] 4. The utility model air compressor uses an oil-free water-lubricated screw machine with high isothermal compression efficiency. In addition, it is coupled with the heat of the adsorption dryer, has a long-cycle regeneration, and uses a permanent magnet motor, which greatly reduces the compression energy consumption.

[0023] 5. The utility model uses the flash steam, supercooled air and evaporated gas from the liquid air storage tank for analytical gas in the adsorption dryer after fully reheating, thereby utilizing the dryness thereof, enhancing the integrated utilization efficiency, saving the amount of raw material compressed air, saving the compression cost and reducing the unit consumption of the product.

[0024] 6. The utility model air compressor adopts screw machine, permanent magnet motor and vector frequency conversion, which realizes automatic load change from 0 to 100% according to the change of nitrogen usage by users, reduces energy waste and reduces unit product energy consumption.

[0025] 7. The utility model can adopt PLC automatic control and remote control, which reduces labor costs.

[0026] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and will be apparent to those skilled in the art based on the following examination and research, or can be taught from the practice of the present invention to some extent. The objectives and other advantages of the present invention can be achieved and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be described in detail below in conjunction with the accompanying drawings, in which:

[0028] Figure 1 This is a schematic diagram of the distributed liquid nitrogen cooling capacity recovery device in the utility model.

[0029] Figure markings: 1-air compressor; 2-cold dryer; 3-adsorption dryer; 4-main heat exchanger; 5-flash evaporator; 6-subcooler; 7-liquid air storage tank; 8-liquid nitrogen pump; 9-liquid nitrogen storage tank; 31-air inlet; 32-air outlet; 33-analysis gas inlet; 34-analysis gas outlet; 41-main heat exchange first inlet; 42-main heat exchange first outlet; 43-main heat exchange second inlet; 44-main heat exchange second outlet; 45-main heat exchange third inlet; 46-main heat exchange third outlet; 51-flash evaporation feed inlet; 52-flash evaporation liquid outlet; 53-flash evaporation exhaust outlet; 61-subcooling first inlet; 62-subcooling first outlet; 63-subcooling second inlet; 64-subcooling second outlet. DETAILED DESCRIPTION

[0030] The following describes the implementation of the present invention through specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific implementations, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner. The following embodiments and the features in the embodiments can be combined with each other without conflict.

[0031] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present utility model. In order to better illustrate the embodiments of the present utility model, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0032] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "back" and the like indicate directions or positional relationships, they are based on the directions or positional relationships shown in the drawings, which are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, the terms describing the positional relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0033] See also Figure 1 , which is a distributed liquid nitrogen cooling recovery device, including an air compression purification system, a heat exchange cold box, a liquid air storage tank 7, a liquid nitrogen pump 8, and a liquid nitrogen storage tank 9;

[0034] The air compression purification system includes an air compressor 1, a cold dryer 2, and an adsorption dryer 3; the adsorption dryer 3 is provided with two groups of inlets and outlets, namely an air inlet 31 and an air outlet 32, and a desorption gas inlet 33 and a desorption gas outlet 34;

[0035] The heat exchange cold box includes a main heat exchanger 4, a flash evaporator 5, and a subcooler 6; the main heat exchanger 4 is provided with three groups of inlets and outlets, namely, a main heat exchange first inlet 41 and a main heat exchange first outlet 42, a main heat exchange second inlet 43 and a main heat exchange second outlet 44, a main heat exchange third inlet 45 and a main heat exchange third outlet 46; the flash evaporator 5 is provided with a flash feed inlet 51, a flash liquid outlet 52, and a flash exhaust outlet 53; the subcooler 6 is provided with two groups of inlets and outlets, namely, a subcooling first inlet 61 and a subcooling first outlet 62, a subcooling second inlet 63 and a subcooling second outlet 64;

[0036] The air compressor 1, the cold dryer 2, and the adsorption dryer 3 are connected in series in sequence. The cold dryer 2 is connected to the air inlet 31 of the adsorption dryer 3. The air outlet 32 ​​of the adsorption dryer 3 is connected to the first main heat exchange inlet 41. The first main heat exchange outlet 42 is connected to the flash feed inlet 51. The flash liquid outlet 52 is connected to the first subcooling inlet 61. The flash exhaust port 53 is connected to the second main heat exchange inlet 43. The first subcooling outlet 62 leads to two paths, one of which is connected to the liquid-air storage tank 7, and the other is connected to the second subcooling inlet 63. The second subcooling outlet 64 is connected to the second main heat exchange inlet 43. The second main heat exchange outlet 44 is connected to the analytical gas inlet 33.

[0037] The liquid nitrogen storage tank 9 is connected to the third main heat exchange inlet 45 through the liquid nitrogen pump 8, and the third main heat exchange outlet 46 is connected to the user nitrogen pipeline network. The coldness of the liquid nitrogen is used for the preparation of liquid air through the main heat exchanger 4.

[0038] Throttle valves are provided between the first main heat exchange outlet 42 and the flash feed inlet 51, between the first subcooling outlet 62 and the second subcooling inlet 63, between the first subcooling outlet 62 and the liquid air storage tank 7, and between the flash exhaust port 53 and the second main heat exchange inlet 43. The liquid air storage tank 7 is also provided with a steam outlet, which is connected to the second main heat exchange inlet 43.

[0039] The air compressor is a screw compressor with single-stage compression, oil-free water lubrication, built-in air cooler, and equipped with a permanent magnet motor, vector inverter, and water purification system.

[0040] The air compressor 1, the cold dryer 2, and the adsorption dryer 3 in this embodiment are separately integrated and assembled into one body, and the distributed liquid nitrogen cold recovery device is integrated as a whole on the skid-mounted frame.

[0041] The cold dryer 2 realizes refrigeration and dehumidification through a refrigeration cycle, and the refrigerant is R134, R407, R717 or R22.

[0042] Adsorption dryer 3 is a double-layer bed structure, and the adsorbent is activated alumina and 13X molecular sieve. Adsorption dryer 3 adopts a long-cycle regeneration cycle, a switching cycle of 12 hours, and a low-heat regeneration method.

[0043] The distributed liquid nitrogen cooling capacity recovery device in this embodiment is used for liquid nitrogen cooling capacity recovery. The distributed liquid nitrogen cooling capacity recovery device adopts a PLC system to automatically control the operating parameters, and the cooling capacity when the liquid nitrogen is vaporized is used for liquid air production; the air is pressurized by the air compressor 1, enters the cold dryer 2 for cooling, and then enters the adsorption dryer 3 to obtain dry and clean compressed air; the clean and dry compressed air enters the main heat exchanger 4, is cooled and liquefied, and then enters the flash evaporator 5 for gas-liquid separation, and then is supercooled by the cooler 6; from the liquid nitrogen storage tank 9 The liquid nitrogen pressurized by the liquid nitrogen pump 8 enters the main heat exchanger 4 for heat exchange, and the liquid nitrogen is vaporized and reheated before entering the user's nitrogen pipeline network; the liquid air supercooled by the subcooler 6 is divided into two destinations, one part is throttled to normal pressure and then returns to the subcooler 6, and after being vaporized, it merges with the naturally evaporated low-temperature air in the liquid air storage tank 7 and the air coming out of the flash exhaust port 53 of the flash evaporator 5, and then enters the main heat exchanger 4 for further reheating, and then enters the adsorption dryer 3 as the analytical gas, and the other part is sent to the liquid air storage tank as the liquid air product.

[0044] Among them, the air is pressurized to 1.2MPa by the air compressor 1, and the interface diameter is DN50. Liquid nitrogen is taken out from the user's liquid nitrogen pump 8 and sent to the main heat exchanger 4, with a junction pressure of about 1.0MPa and an interface diameter of DN25. Normal pressure air is taken out from the heat exchange cold box and sent to the air dryer purifier with a junction pressure of about 15kPa and an interface diameter of DN50. Liquid air is taken out from the heat exchange cold box and sent to the liquid air storage tank, with a junction pressure of about 0.2MPa and an interface diameter of DN25. Nitrogen is taken out from the heat exchange cold box and sent to the user's nitrogen main network, with a junction pressure of about 1.0MPa and an interface diameter of DN100.

[0045] The raw materials used in this example are: liquid nitrogen: 1000Nm 3 / h (converted to gas), 1.0MPa; air: 1180Nm 3 / h, 1.2MPa. Product obtained: Liquid air: 1000Nm 3 / h (converted to gas); normal pressure air: 150m 3 / h, 15kPa; Nitrogen: 1000Nm 3 / h / h, 1.0MPa.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the utility model.

Claims

1. A distributed liquid nitrogen cooling capacity recovery device, characterized in that: Including air compression purification system, heat exchange cold box, liquid air storage tank, liquid nitrogen pump, liquid nitrogen storage tank; The air compression purification system comprises an air compressor, a cold dryer, and an adsorption dryer; the adsorption dryer is provided with two groups of inlets and outlets, namely, an air inlet and an air outlet, and a desorption gas inlet and a desorption gas outlet; The heat exchange cold box includes a main heat exchanger, a flash evaporator, and a subcooler; the main heat exchanger is provided with three groups of inlets and outlets, namely, a first inlet and a first outlet of the main heat exchange, a second inlet and a second outlet of the main heat exchange, and a third inlet and a third outlet of the main heat exchange; the flash evaporator is provided with a flash feed inlet, a flash liquid outlet, and a flash exhaust outlet; the subcooler is provided with two groups of inlets and outlets, namely, a first subcooling inlet and a first subcooling outlet, and a second subcooling inlet and a second subcooling outlet; The air compressor, the cold dryer, and the adsorption dryer are connected in series in sequence, the cold dryer is connected to the air inlet of the adsorption dryer, the air outlet of the adsorption dryer is connected to the first inlet of the main heat exchange, the first outlet of the main heat exchange is connected to the flash feed inlet, the flash liquid outlet is connected to the first subcooling inlet, and the flash exhaust port is connected to the second inlet of the main heat exchange; the first subcooling outlet leads to two paths, one path is connected to the liquid-air storage tank, and the other path is connected to the second subcooling inlet, the second subcooling outlet is connected to the second inlet of the main heat exchange, and the second outlet of the main heat exchange is connected to the analytical gas inlet; The liquid nitrogen storage tank is connected to the third inlet of the main heat exchange through a liquid nitrogen pump, and the third outlet of the main heat exchange is connected to the user nitrogen pipeline network. The coldness of the liquid nitrogen is used for the preparation of liquid air through the main heat exchanger.

2. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: Throttle valves are arranged between the first outlet of the main heat exchange and the flash feed inlet, between the first subcooling outlet and the second subcooling inlet, between the first subcooling outlet and the liquid-air storage tank, and between the flash exhaust port and the second inlet of the main heat exchange.

3. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The liquid air storage tank is also provided with a steam outlet, which is communicated with the second inlet of the main heat exchange.

4. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The air compressor is a screw compressor with single-stage compression, oil-free water lubrication, built-in air cooler, and equipped with a permanent magnet motor, a vector inverter, and a water purification system.

5. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The distributed liquid nitrogen cooling capacity recovery device is integrated as a whole on the skid-mounted frame.

6. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The cold dryer realizes refrigeration and dehumidification through a refrigeration cycle, and the refrigerant is R134, R407, R717 or R22.

7. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The adsorption dryer is a double-layer bed structure.

8. The distributed liquid nitrogen cooling capacity recovery device according to claim 1, characterized in that: The air compressor, cold dryer and adsorption dryer are individually integrated and assembled into one body.

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