A semi-closed air separation pre-cooling device

Abstract

The application discloses a semi-closed air separation pre-cooling device, which comprises a circulating water pipe network, a water cooling tower and an air cooling tower, wherein a normal-temperature water dry heat exchanger, a normal-temperature water sprayer, a first heat exchange filler and a cooling water heat exchange coil are arranged in the water cooling tower from top to bottom, a chilled water wet heat exchange system and a cooling water spraying system are arranged in the air cooling tower, the device further comprises pipelines which are connected with the circulating water pipe network, the normal-temperature water dry heat exchanger, the cooling water heat exchange coil and the chilled water wet heat exchange system, and a cooling water pump is arranged at the lower part of the water cooling tower and connected with the cooling water spraying system through the cooling water pump. The device can recycle the cold energy of the vented waste nitrogen through the heat exchanger arranged at the top of the water cooling tower, the chilled water adopts closed circulation to cancel the chilled water pump, the air cooling tower adopts the composite means of step-by-step heat exchange to improve the cooling efficiency, the end temperature of the compressed air is more efficiently reduced, the waste cold energy and waste pressure of each system are fully utilized, and the operation energy consumption of the pre-cooling system can be effectively saved.

Description

Technical Field

[0001] This invention relates to the field of air separation technology, and specifically to a semi-closed air separation precooling device. Background Technology

[0002] Industrial gases are figuratively called "industrial blood," and air separation units are the "heart" of gas production. The basic principle of air separation is to condense air into liquid using cryogenic distillation, and then separate the air according to the different evaporation temperatures of each component. The above-mentioned cryogenic distillation process requires a pre-cooling device to cool the compressed air before passing it through a molecular sieve to remove impurities. Therefore, a highly efficient and energy-saving pre-cooling device is crucial for the stability and economy of air separation unit operation.

[0003] The precooling system of a modern air separation unit typically consists of a water-cooled tower, an air-cooled tower, and related valves, pipes, and instruments used in wet heat exchange. Low-temperature, dry waste nitrogen from the distillation column cools the circulating water in the water-cooled tower to approximately 15°C. This cooling water is further cooled to approximately 8°C by the refrigeration unit, and then pressurized by cooling water pumps and chilled water pumps before being sprayed into the lower and upper sections of the air-cooled tower for heat exchange with high-temperature compressed air. Finally, the compressed air, initially at approximately 100°C, is cooled to approximately 10°C to meet the operating temperature requirements of the molecular sieve. However, the wet waste nitrogen vented from the top of the water-cooled tower in this precooling system is at a relatively low temperature, resulting in some wasted cooling capacity. Furthermore, the cooling water pumps and chilled water pumps need to overcome the high pressure inside the air-cooled tower, leading to high pump energy consumption. Summary of the Invention

[0004] 1. The technical problem that the invention aims to solve

[0005] The purpose of this invention is to solve the technical problems existing in the prior art and provide a semi-closed air separation precooling device. It can recover the cooling capacity of the released nitrogen by designing a heat exchanger at the top of the water-cooling tower; the chilled water adopts a closed circulation to eliminate the need for a chilled water pump; and the air-cooling tower improves cooling efficiency through staged heat exchange. This combination of methods can more efficiently reduce the terminal temperature of compressed air, make full use of the residual cooling and residual pressure of each stage of the system, and effectively save the operating energy consumption of the precooling system.

[0006] 2. Technical Solution

[0007] To solve the above problems, the technical solution provided by the present invention is as follows:

[0008] A semi-closed air separation precooling device includes a circulating water network, a water-cooled tower, and an air-cooled tower. The water-cooled tower contains, from top to bottom, a normal temperature water dry heat exchanger, a normal temperature water sprayer, a first heat exchange packing, and a cooling water heat exchange coil. The air-cooled tower contains a chilled water wet heat exchange system and a cooling water spray system. It also includes pipes that circulate and connect the circulating water network, the normal temperature water dry heat exchanger, the cooling water heat exchange coil, and the chilled water wet heat exchange system. The lower part of the water-cooled tower is equipped with a cooling water pump, which is connected to the cooling water spray system.

[0009] Optionally, a chiller is provided on the pipe connecting the cooling water heat exchange coil and the chilled water wet heat exchanger.

[0010] Optionally, the air-cooled tower is equipped with an air-ventilated water-collecting plate, with the area above the air-ventilated water-collecting plate being the primary cooling zone and the area below the air-ventilated water-collecting plate being the secondary cooling zone.

[0011] Optionally, a first chilled water sprayer is provided in the primary cooling area. The first chilled water sprayer is connected to the water collection area of ​​the ventilated water collection plate through a spray water pump. The chilled water wet heat exchange system includes a first wet cooling water heat exchanger located between the first chilled water sprayer and the ventilated water collection plate.

[0012] Optionally, a second heat exchange packing is provided in the secondary cooling area, the cooling water spray system includes the ventilated water collection plate and the second chilled water sprayer, and the chilled water wet heat exchange system further includes a second wet cooling water heat exchanger provided in the secondary cooling area, with the second chilled water sprayer, the second wet cooling water heat exchanger and the second heat exchange packing arranged from top to bottom.

[0013] Optionally, the circulating water network includes a circulating water supply pipe and a circulating water return pipe. The circulating water supply pipe is used to supply water to the water-cooled tower, and the water discharged from the air-cooled tower enters the circulating water return pipe.

[0014] Optionally, the system may also include a purification system connected to the air-cooled tower, wherein air discharged from the air-cooled tower enters the purification system.

[0015] 3. Beneficial effects

[0016] Compared with the prior art, the technical solution provided by this invention has the following advantages:

[0017] The water-cooled tower in this semi-closed air separation precooling unit recovers the cooling capacity of the released waste nitrogen by setting up a set of ambient temperature water dry heat exchangers, which further reduces the cooling water temperature, reduces the scale of the chiller unit for preparing chilled water from the cooling water, and fully improves the utilization of the waste nitrogen cooling capacity.

[0018] The chilled water in this semi-closed air separation precooling unit is in a closed-loop circulation. Conventional setups involve installing a chilled water pump before the chiller, pressurizing the water to overcome the internal pressure of the air-cooled tower, and spraying it to directly cool the compressed air, which is an open-loop circulation. This semi-closed air separation precooling unit utilizes the residual pressure of the circulating water system, eliminating the need for a chilled water pump and saving on operating energy consumption and construction investment.

[0019] In this semi-closed air separation precooling unit, the upper tower of the air-cooled tower is cooled by primary chilled water circulation, while the lower tower is cooled by secondary cooling water spray, making the heat exchange inside the air-cooled tower more uniform and thorough. Compared with the traditional air-cooled tower design, this semi-closed air separation precooling unit adds a precooling stage, improving the cooling effect on compressed air.

[0020] The split-type design of the air-cooling tower inside this semi-closed air separation precooling unit helps to improve the condensation problem caused by drastic temperature changes inside the air-cooling tower. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a semi-closed air separation precooling device according to an embodiment of the present invention;

[0022] a. Circulating water supply pipe; b. Circulating water return pipe; 1. Water-cooled tower; 1a. Sludge nitrogen inlet; 1b. Sludge nitrogen vent; 2. Air-cooled tower; 2a. Primary cooling zone; 2b. Secondary cooling zone; 2c. Compressed air inlet; 2d. Compressed air outlet; 3. Ambient temperature water dry heat exchanger; 4. Ambient temperature water sprayer; 5. First heat exchange packing; 6. Cooling water heat exchange coil; 7. Cooling water pump; 8. Chiller; 9. Ventilation and water collection plate; 10. Spray water pump; 11. First wet cooling water heat exchanger; 12. Second heat exchange packing; 13. Second chilled water sprayer; 14. Second wet cooling water heat exchanger; 15. First chilled water sprayer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of this invention.

[0024] It should be noted that when a component is referred to as "fixed to," "set on," "fixed to," or "mounted on" another component, it can be directly on the other component or there may be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component. Furthermore, when a component is considered to be "fixedly connected" to another component, the connection can be detachable or non-detachable, such as through socketing, snap-fitting, integral molding, welding, etc., which are achievable in the prior art and will not be elaborated upon here. When a component is perpendicular or approximately perpendicular to another component, it means that the ideal state is perpendicularity, but due to manufacturing and assembly effects, there may be a certain degree of perpendicularity error. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only and do not represent the only possible implementation.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] In this invention, the terms "first" and "second" do not represent a specific quantity or order, but are merely used to distinguish names.

[0027] Combined with appendix Figure 1 This embodiment of a semi-closed air separation precooling device includes a circulating water network, a water-cooled tower 1, and an air-cooled tower 2. The circulating water network includes a circulating water supply pipe a and a circulating water return pipe b. The circulating water supply pipe a supplies water to the water-cooled tower 1, and the water discharged from the air-cooled tower 2 enters the circulating water return pipe b. The water-cooled tower 1 has a nitrogen inlet 1a in the middle and a nitrogen vent 1b at the top. The air-cooled tower 2 has a compressed air inlet 2c at the bottom and a compressed air outlet 2d at the top. The water-cooled tower 1 contains a self-contained... The air-cooled tower 2 is equipped with a dry heat exchanger 3, a dry heat exchanger 4, a first heat exchange packing 5, and a cooling water heat exchange coil 6 from top to bottom. The air-cooled tower 2 is equipped with a chilled water wet heat exchange system and a cooling water spray system. It also includes pipes that circulate and connect the circulating water network, the dry heat exchanger 3, the cooling water heat exchange coil 6, and the chilled water wet heat exchange system. The circulating water network is also connected to the dry heat exchanger 4 through other pipes. The lower part of the air-cooled tower 1 is equipped with a cooling water pump 7 and is connected to the cooling water spray system through the cooling water pump 7.

[0028] In this semi-closed air separation precooling unit, the water-cooled tower recovers the cooling capacity of the released nitrogen by setting up a set of ambient temperature water dry heat exchangers 3, further reducing the cooling water temperature and the size of the chiller unit for preparing chilled water from the cooling water, thus fully improving the utilization of the nitrogen cooling capacity. Moreover, the chilled water is in a closed loop. Conventional setups involve setting up a chilled water pump before the chiller, pressurizing it to overcome the internal pressure of the air-cooled tower, and spraying it to directly cool the compressed air, which is an open loop. This semi-closed air separation precooling unit utilizes the residual pressure of the circulating water system, eliminating the need for a chilled water pump, thus saving operating energy consumption and construction investment.

[0029] As an optional embodiment of the present invention, a chiller 8 is provided on the pipe connecting the cooling water heat exchange coil 6 and the chilled water wet heat exchanger 7, and the chiller 8 is used to further reduce the temperature of the chilled water.

[0030] As an optional embodiment of the present invention, the air-cooled tower 2 is provided with a ventilated water collection plate 9. Above the ventilated water collection plate 9 is a primary cooling zone 2a, and below the ventilated water collection plate 9 is a secondary cooling zone 2b. The upper surface of the ventilated water collection plate 9 forms a water collection area under the action of spraying. A first chilled water sprayer 15 is provided in the primary cooling zone 2a. The first chilled water sprayer 15 is connected to the water collection area of ​​the ventilated water collection plate 9 via a spray water pump 10. The chilled water wet heat exchange system includes a first wet cooling water heat exchanger 11 disposed between the first chilled water sprayer 15 and the ventilated water collection plate 9. A second heat exchange packing 12 is provided in the secondary cooling zone 2b. The cooling water spraying system includes a ventilated water collection plate 10 and a second chilled water sprayer 13. The cooling water pump 7 is connected to the second chilled water sprayer 13. The chilled water wet heat exchange system also includes a second wet cooling water heat exchanger 14 located in the secondary cooling zone 2b. The second chilled water sprayer 13, the second wet cooling water heat exchanger 14, and the second heat exchange packing 12 are connected from top to bottom to the cooling water heat exchange coil 6. The pipes are first connected to the first wet cooling water heat exchanger 11, then to the second wet cooling water heat exchanger 14, and finally to the circulating water network. Compared with the traditional air-cooled tower design, this semi-closed air separation precooling device adopts an internal upper and lower separation design, which is beneficial to improving the scaling problem caused by drastic temperature changes in the air-cooled tower. It also adds a precooling stage, which improves the cooling effect on compressed air and makes the heat exchange inside the air-cooled tower more uniform and sufficient.

[0031] As an optional embodiment of the present invention, a purification system connected to the air-cooled tower 2 is also included, wherein air discharged from the air-cooled tower 2 enters the purification system, and the purification system is connected to the compressed air exhaust port 2d.

[0032] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A semi-closed air separation precooling device, characterized in that: The system includes a circulating water network, a water-cooled tower, and an air-cooled tower. The water-cooled tower contains, from top to bottom, a normal temperature water dry heat exchanger, a normal temperature water sprayer, a first heat exchange packing, and a cooling water heat exchange coil. The air-cooled tower contains a chilled water wet heat exchange system and a cooling water spray system. The system also includes pipes that circulate and connect the circulating water network, the normal temperature water dry heat exchanger, the cooling water heat exchange coil, and the chilled water wet heat exchange system. The lower part of the water-cooled tower is equipped with a cooling water pump, which is connected to the cooling water spray system. The air-cooled tower is equipped with a ventilation and water collection plate. The area above the ventilation and water collection plate is the primary cooling zone, and the area below the ventilation and water collection plate is the secondary cooling zone. The first chilled water sprayer is provided in the primary cooling area. The first chilled water sprayer is connected to the water collection area of ​​the ventilated water collection plate through a spray water pump. The chilled water wet heat exchange system includes a first wet cooling water heat exchanger located between the first chilled water sprayer and the ventilated water collection plate. The secondary cooling area is provided with a second heat exchange packing. The cooling water spray system includes a second chilled water sprayer located under the ventilated water collection plate. The chilled water wet heat exchange system also includes a second wet cooling water heat exchanger located in the secondary cooling area. The second chilled water sprayer, the second wet cooling water heat exchanger, and the second heat exchange packing are arranged from top to bottom. The pipes leading out from the cooling water heat exchange coil are first connected to the first wet cooling water heat exchanger, then to the second wet cooling water heat exchanger, and finally to the circulating water network. A chiller is installed on the pipeline connecting the cooling water heat exchange coil and the chilled water wet heat exchange system.

2. A semi-closed air separation precooling device according to any one of claims 1, characterized in that: The circulating water network includes a circulating water supply pipe and a circulating water return pipe. The circulating water supply pipe is used to supply water to the water-cooled tower, and the water discharged from the air-cooled tower enters the circulating water return pipe.

3. A semi-closed air separation precooling device according to any one of claims 1, characterized in that: It also includes a purification system connected to the air-cooled tower, into which air discharged from the air-cooled tower enters.

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