Semi-closed air separation precooling device

Abstract

The utility model discloses a semi-closed type air separation precooling device which comprises a circulating water pipe network, a water cooling tower and an air cooling tower, a normal temperature water dry type heat exchanger, a normal temperature water sprayer, a first heat exchange filler and a cooling water heat exchange coil pipe are arranged in the water cooling tower from top to bottom, and a chilled water wet type heat exchange system and a cooling water spraying system are arranged in the air cooling tower. The system further comprises a pipeline which is circularly connected with the circulating water pipe network, the normal-temperature water dry-type heat exchanger, the cooling water heat exchange coil and the chilled water wet-type heat exchange system, and the lower portion of the water cooling tower is provided with a cooling water pump and is connected with the cooling water spraying system through the cooling water pump. The heat exchanger is designed at the top of the water cooling tower to recover the cooling capacity of discharged waste nitrogen; chilled water adopts closed circulation so as to eliminate a chilled water pump; the composite means of step-by-step heat exchange of the air cooling tower to improve the cooling efficiency is adopted, the tail end temperature of compressed air is reduced more efficiently, residual cold and residual pressure of all stages of systems are fully utilized, and the operation energy consumption of the pre-cooling system can be effectively saved.

Description

Technical Field

[0001] The utility model relates to the technical field of air separation, in particular to a semi-closed air separation precooling device. Background Art

[0002] Industrial gas is figuratively called the "industrial blood", and the air separation unit is the "heart" of gas production. The basic principle of air separation is to condense air into liquid by cryogenic distillation, and then separate the air according to the different evaporation temperatures of each component. The above cryogenic distillation process requires a precooling device to cool the compressed air and then remove impurities through a molecular sieve. Therefore, an efficient and energy-saving precooling device is crucial to the stability and economy of the operation of the air separation unit.

[0003] The precooling system of a modern air separation unit usually consists of a water-cooling tower, an air-cooling tower, and related valves, pipes, and instruments for wet heat exchange. The low-temperature, dry dirty nitrogen from the distillation tower cools the circulating water to about 15°C in the water-cooling tower. The cooling water is further cooled to about 8°C chilled water after the refrigeration unit works, and then pressurized by the cooling water pump and the chilled water pump into the lower and upper towers of the air-cooling tower for spraying and heat exchange with the high-temperature compressed air. Finally, the compressed air at about 100°C is cooled to about 10°C to meet the working temperature requirements of the molecular sieve. The temperature of the wet dirty nitrogen discharged from the top of the water-cooling tower in the above-mentioned precooling system is relatively low, and there is a certain waste of cooling capacity. In addition, the cooling water pump and the chilled water pump need to overcome the high pressure inside the air-cooling tower, and the water pump energy consumption is relatively high. Utility Model Content

[0004] 1. Technical problems to be solved by the utility model

[0005] The utility model aims to solve the technical problems existing in the prior art and provides a semi-closed air separation precooling device, which can recover the cold of the discharged polluted nitrogen by designing a heat exchanger at the top of the water cooling tower; the chilled water adopts a closed circulation to eliminate the chilled water pump; the air cooling tower uses a composite means of step-by-step heat exchange to improve the cooling efficiency, more efficiently reduce the terminal temperature of the compressed air, make full use of the excess cooling and excess pressure of the systems at all levels, and can effectively save the operating energy consumption of the precooling system.

[0006] 2. Technical solution

[0007] In order to solve the above problems, the technical solution provided by the utility model is:

[0008] A semi-closed air separation precooling device comprises a circulating water network, a water cooling tower and an air cooling tower, wherein the water cooling tower is provided with a normal temperature water dry heat exchanger, a normal temperature water sprayer, a first heat exchange filler and a cooling water heat exchange coil from top to bottom, wherein the air cooling tower is provided with a chilled water wet heat exchange system and a cooling water spray system, and further comprises a pipeline cyclically connecting 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, wherein a cooling water pump is provided at the lower part of the water cooling tower and is connected to the cooling water spray system through the cooling water pump.

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

[0010] Optionally, a ventilation and water collecting plate is provided in the air cooling tower, the upper part of the ventilation and water collecting plate is a primary cooling area, and the lower part of the ventilation and water collecting plate is a secondary cooling area.

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

[0012] Optionally, a second heat exchange filler is provided in the secondary cooling area, the cooling water spray system includes a second chilled water sprayer arranged under the ventilation and water collecting plate, and the chilled water wet heat exchange system also includes a second wet cooling water heat exchanger arranged in the secondary cooling area, and the second chilled water sprayer, the second wet cooling water heat exchanger and the second heat exchange filler are 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 cooling tower, and the water discharged from the air cooling tower enters the circulating water return pipe.

[0014] Optionally, a purification system connected to the air cooling tower is further included, and the air exhausted from the air cooling tower enters the purification system.

[0015] 3. Beneficial effects

[0016] Compared with the prior art, the technical solution provided by the utility model has the following beneficial effects:

[0017] The water cooling tower in the semi-closed air separation precooling device recovers the cold of the discharged polluted nitrogen by setting a group of normal temperature water dry heat exchangers, further reducing the cooling water temperature, reducing the scale of the refrigeration unit for preparing chilled water with cooling water, and fully improving the utilization of the polluted nitrogen cold capacity;

[0018] The chilled water of this semi-closed air separation precooling device is a closed cycle. The conventional setting is to install a chilled water pump in front of the freezer. After pressurization, it overcomes the internal pressure of the air cooling tower and sprays to directly cool the compressed air. It is an open cycle. This semi-closed air separation precooling device utilizes the residual pressure of the circulating water system and does not need to install a chilled water pump, saving operating energy consumption and construction investment.

[0019] The upper tower of the air-cooling tower in the semi-closed air separation precooling device is a first-stage chilled water circulation cooling, and the lower tower of the air-cooling tower is a second-stage cooling water spray cooling, so that the heat exchange inside the air-cooling tower is more uniform and sufficient; compared with the traditional air-cooling tower design, the semi-closed air separation precooling device adds a first-stage precooling, which improves the cooling effect of compressed air.

[0020] The upper and lower separation design inside the air cooling tower in the semi-closed air separation precooling device is conducive to improving the temperature problems caused by the drastic temperature changes in the air cooling tower. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of the structure of a semi-closed air separation precooling device proposed in an embodiment of the utility model;

[0022] a. Circulating water supply pipe; b. Circulating return water pipe; 1. Water cooling tower; 1a. Dirty nitrogen inlet; 1b. Dirty nitrogen vent; 2. Air cooling tower; 2a. Primary cooling area; 2b. Secondary cooling area; 2c. Compressed air inlet; 2d. Compressed air exhaust; 3. Normal temperature water dry heat exchanger; 4. Normal temperature water sprayer; 5. First heat exchange filler; 6. Cooling water heat exchange coil; 7. Cooling water pump; 8. Refrigerator; 9. Ventilation and water collecting plate; 10. Spray water pump; 11. First wet cooling water heat exchanger; 12. Second heat exchange filler; 13. Second chilled water sprayer; 14. Second wet cooling water heat exchanger; 15. First chilled water sprayer. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be understood that the specific implementation methods described here are only used to explain the utility model and do not limit the protection scope of the utility model.

[0024] It should be noted that when an element is referred to as being "fixed to", "disposed on", "fixed on" or "installed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. Further, when an element is considered to be "fixedly connected to" another element, the two may be fixed in a detachable connection manner or in a non-detachable connection manner, such as socketing, snap-on, one-piece fixation, welding, etc., which can be achieved in the prior art and will not be repeated here. When an element is perpendicular or approximately perpendicular to another element, it means that the ideal state of the two is vertical, but due to the influence of manufacturing and assembly, there may be a certain vertical error. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the technical field of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0026] The “first” and “second” involved in the present utility model do not represent specific quantities and orders, but are merely used to distinguish names.

[0027] Combined with Figure 1 A semi-closed air separation precooling device of this embodiment includes a circulating water network, a water cooling tower 1 and an air cooling tower 2, wherein the circulating water network includes a circulating water supply pipe a and a circulating water return pipe b, wherein the circulating water supply pipe a is used to supply water to the water cooling tower 1, and the water discharged from the air cooling tower 2 enters the circulating water return pipe b, wherein a waste nitrogen inlet 1a is provided in the middle of the water cooling tower 1, a waste nitrogen vent 1b is provided at the top of the water cooling tower 1, a compressed air inlet 2c is provided at the bottom of the air cooling tower 2, a compressed air exhaust port 2d is provided at the top of the air cooling tower 2, and a compressed air outlet 2d is provided in the water cooling tower 1. From top to bottom, a normal temperature water dry heat exchanger 3, a normal temperature water sprayer 4, a first heat exchange filler 5 and a cooling water heat exchange coil 6 are arranged. A chilled water wet heat exchange system and a cooling water spray system are arranged in the air cooling tower 2. It also includes a pipeline cyclically connecting the circulating water network, the normal temperature water 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 normal temperature water sprayer 4 through other pipelines. A cooling water pump 7 is arranged at the lower part of the water cooling tower 1 and is connected to the cooling water spray system through the cooling water pump 7.

[0028] The water cooling tower in the semi-closed air separation precooling device recovers the cold of the discharged contaminated nitrogen by setting a group of normal temperature water dry heat exchangers 3, further reducing the cooling water temperature, reducing the scale of the refrigeration unit for preparing chilled water with cooling water, and fully improving the utilization of the contaminated nitrogen cold capacity; and the chilled water is a closed cycle. The conventional setting is to set a chilled water pump in front of the freezer. After pressurization, it overcomes the internal pressure of the air cooling tower and sprays to directly cool the compressed air. It is an open cycle. The semi-closed air separation precooling device utilizes the residual pressure of the circulating water system, does not need to set a chilled water pump, and saves operating energy consumption and construction investment.

[0029] As an optional solution of the present utility model, a refrigerator 8 is provided on the pipeline connecting the cooling water heat exchange coil 6 and the chilled water wet heat exchanger 7, and the refrigerator 8 is used to further reduce the temperature of the chilled water.

[0030] As an optional solution of the utility model, a ventilation water collecting plate 9 is provided in the air cooling tower 2, the upper part of the ventilation water collecting plate 9 is a primary cooling area 2a, the lower part of the ventilation water collecting plate 9 is a secondary cooling area 2b, the upper end surface of the ventilation water collecting plate 9 forms a water collecting area under the action of spraying, a first chilled water sprayer 15 is provided in the primary cooling area 2a, the first chilled water sprayer 15 is connected to the water collecting area of ​​the ventilation water collecting plate 9 through a spray water pump 10, the chilled water wet heat exchange system includes a first wet cooling water heat exchanger 11 arranged between the first chilled water sprayer 15 and the ventilation water collecting plate 9, a second heat exchange filler 12 is provided in the secondary cooling area 2b, the cooling water spray system includes a second chilled water sprayer 13 arranged under the ventilation water collecting plate 9, the The cooling water pump 7 is connected to the second chilled water sprinkler 13, and the chilled water wet heat exchange system also includes a second wet cooling water heat exchanger 14 arranged in the secondary cooling area 2b. The second chilled water sprinkler 13, the second wet cooling water heat exchanger 14 and the second heat exchange filler 12 are connected from top to bottom. The pipeline led out from the cooling water heat exchange coil 6 is first connected to the first wet cooling water heat exchanger 11, then connected to the second wet cooling water heat exchanger 14, and finally connected to the circulating water network; compared with the traditional air-cooling tower design, the semi-closed air separation precooling device adopts an upper and lower separation design in the tower, which is conducive to improving the scaling problem caused by the drastic temperature change in the air-cooling tower, and adds a first-level precooling, which improves the cooling effect of the compressed air, making the heat exchange inside the air-cooling tower more uniform and sufficient.

[0031] As an optional solution of the present invention, it also includes a purification system connected to the air cooling tower 2, the air exhausted from the air cooling tower 2 enters the purification system, and the purification system is connected to the compressed air exhaust port 2d.

[0032] The above schematically describes the present invention and its implementation methods, which are not restrictive. The drawings show only one implementation method of the present invention, and the actual structure is not limited thereto. Therefore, if ordinary technicians in this field are inspired by it and design structural methods and embodiments similar to the technical solution without creativity without departing from the purpose of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A semi-closed air separation precooling device, characterized in that: It includes a circulating water network, a water cooling tower and an air cooling tower. The water cooling tower is provided with a normal temperature water dry heat exchanger, a normal temperature water sprayer, a first heat exchange filler and a cooling water heat exchange coil from top to bottom. The air cooling tower is provided with a chilled water wet heat exchange system and a cooling water spray system, and also includes pipelines 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. A cooling water pump is provided at the bottom of the water cooling tower and is connected to the cooling water spray system through the cooling water pump.

2. A semi-closed air separation precooling device according to claim 1, characterized in that: A refrigerator is arranged on the pipeline connecting the cooling water heat exchange coil and the chilled water wet heat exchanger.

3. A semi-closed air separation precooling device according to claim 1, characterized in that: A ventilation and water collecting plate is arranged in the air cooling tower, the upper part of the ventilation and water collecting plate is a primary cooling area, and the lower part of the ventilation and water collecting plate is a secondary cooling area.

4. A semi-closed air separation precooling device according to claim 3, characterized in that: A first chilled water sprayer is provided in the primary cooling area, and the first chilled water sprayer is connected to the water collecting area of ​​the ventilation water collecting plate through a spray water pump. The chilled water wet heat exchange system includes a first wet cooling water heat exchanger provided between the first chilled water sprayer and the ventilation water collecting plate.

5. A semi-closed air separation precooling device according to claim 4, characterized in that: A second heat exchange filler is provided in the secondary cooling area, the cooling water spray system includes a second chilled water sprayer arranged under the ventilation and water collecting plate, and the chilled water wet heat exchange system also includes a second wet cooling water heat exchanger arranged in the secondary cooling area, the second chilled water sprayer, the second wet cooling water heat exchanger and the second heat exchange filler are arranged from top to bottom.

6. A semi-closed air separation precooling device according to any one of claims 1 to 5, characterized in that: The circulating water pipe 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 cooling tower, and the water discharged from the air cooling tower enters the circulating water return pipe.

7. A semi-closed air separation precooling device according to any one of claims 1 to 5, characterized in that: It also includes a purification system connected to the air cooling tower, and the air exhausted from the air cooling tower enters the purification system.

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