Air separation unit pre-cooling system suitable for cold region

Abstract

The utility model relates to an air separation unit precooling system suitable for a cold region. The air separation unit precooling system comprises an air compressor, a hot water heat exchanger, an air cooling tower and a water cooling tower, an air outlet of the air compressor is communicated with an air inlet of the hot water heat exchanger; an air outlet of the hot water heat exchanger is communicated with an air inlet of the air cooling tower; the hot water heat exchanger is provided with a circulating hot water inlet and outlet communicated with a hot water station; the air cooling tower comprises a cooling water section and a chilled water section, the chilled water section is provided with a chilled water inlet and is communicated with the chilled water outlet of the water cooling tower, the cooling water section is provided with a circulating cooling water inlet, an air inlet of the air cooling tower is arranged below the cooling water section, and an exhaust pipe is arranged at the top end of the air cooling tower; and the chilled water outlet of the water cooling tower is upwards provided with a waste nitrogen inlet and a circulating water supply inlet in sequence. According to the utility model, the power consumption for conveying cooling water of the air cooling tower is reduced, the consumption for heating hot water by using steam in a traditional hot water station is reduced, the heat utilization rate of the whole device is improved, and the operation cost of a factory is effectively reduced.

Description

Technical Field

[0001] This utility model relates to the technical field of air separation gas production devices, specifically to a precooling system for air separation devices suitable for cold regions. Background Technology

[0002] Air separation units are process devices that separate and purify gases such as oxygen, nitrogen, and argon from the air. They are widely used in modern industry, especially in the steel, petrochemical, and coal chemical industries. However, with the continuous growth of energy demand and the increasing demands for environmental protection, energy conservation and consumption reduction in traditional air separation units have become an important research topic.

[0003] The precooling system of an air separation unit plays a crucial role in the entire cryogenic distillation process. Currently, the precooling system in air separation units involves directly feeding the compressed air, which has reached a certain temperature after the final stage of compression in the air compressor, into an air-cooling tower. The compressed air is then cleaned and cooled using ambient temperature cooling water and chilled water. However, this method of directly using cooling water and chilled water from the air-cooling tower to cool the compressed air after the air compressor neither effectively utilizes the waste heat of the compressed air after the air compressor nor reduces the consumption of cooling water. Therefore, there are areas for improvement in terms of energy utilization and energy conservation.

[0004] Meanwhile, in cold regions, extremely low winter temperatures pose severe challenges to normal factory production and the working environment of employees. To address this issue, traditional factories install hot water stations to centrally supply hot water and ensure heating for the entire plant. Traditional hot water stations typically use steam heaters to heat the water, but this method consumes steam, increasing the factory's heating costs. Utility Model Content

[0005] This invention provides a pre-cooling system for air separation units in cold regions. The process adds a hot water heat exchanger between the air compressor and the air-cooling tower in a traditional air separation unit. Before entering the air-cooling tower, the compressed air first enters the hot water heat exchanger to exchange heat with hot water from a hot water station, utilizing the heat of the compressed air. After heating the hot water, the compressed air is cooled before entering the air-cooling tower. The heated hot water returns to the hot water station to supply heating for the entire plant. This invention improves the heat utilization rate of the entire unit, reduces the consumption of cooling water in the air-cooling tower and the electricity consumption of the cooling water pump, and reduces the steam consumption of the traditional hot water station for heating hot water, effectively reducing the plant's operating costs. It also allows for a smaller air-cooling tower, reducing equipment investment.

[0006] The solution of this utility model to solve the above-mentioned technical problems is as follows: a precooling system for air separation units suitable for cold regions, comprising: an air compressor, a hot water heat exchanger, an air-cooled tower, and a water-cooled tower;

[0007] The compressed air outlet of the air compressor is connected to the compressed air inlet of the hot water heat exchanger, and the compressed air outlet of the hot water heat exchanger is connected to the compressed air inlet of the air-cooled tower; the hot water heat exchanger is equipped with a circulating hot water inlet and a circulating hot water outlet connected to the plant's hot water station.

[0008] The air-cooled tower includes a cooling water section and a chilled water section. The chilled water section is located at the upper part of the tower body, and the cooling water section is located at the lower part of the tower body. The chilled water section is provided with a chilled water inlet, and the cooling water section is provided with a circulating cooling water inlet. The compressed air inlet of the air-cooled tower is located below the circulating cooling water inlet, and an exhaust pipe is provided at the top of the air-cooled tower.

[0009] The chilled water inlet of the air-cooled tower is connected to the chilled water outlet of the water-cooled tower, and the chilled water outlet of the water-cooled tower is provided with a waste nitrogen gas inlet and a circulating water inlet in sequence upwards.

[0010] Preferably, the device further includes an air filter, the air outlet of which is connected to the air inlet of the air compressor.

[0011] Preferably, the height of the chilled water section is 30-40% of the height of the air-cooled tower, and the height of the cooling water section is 15-20% of the height of the air-cooled tower.

[0012] Preferably, a top air outlet section is formed between the top of the chilled water section and the top of the air-cooled tower, and the exhaust pipe of the air-cooled tower is located in the top air outlet section; a liquid collection section is formed between the bottom of the cooling water section and the bottom of the air-cooled tower; and the liquid collection section is provided with a water outlet pipe.

[0013] Preferably, the cooling water section is filled with reinforced polypropylene rings (Dg76) and stainless steel rings (Dg76), while the chilled water section is filled with reinforced polypropylene rings (Dg50). Since air-cooled towers are medium-to-high temperature towers, reinforced polypropylene rings are suitable for operation under low-pressure conditions; therefore, reinforced polypropylene rings are used as packing material in air-cooled towers.

[0014] Air-cooled towers are high-efficiency heat and mass transfer towers with countercurrent gas-liquid contact. They are vertical cylindrical pressure vessels, usually made of carbon steel (with an anti-corrosion coating) or stainless steel, and internally separated by horizontal baffles or packing support structures.

[0015] Preferably, the circulating cooling water inlet of the air-cooled tower is connected to a cooling water pump. Preferably, the inlet temperature of the circulating cooling water of the air-cooled tower is 30-34°C, the inlet temperature of the chilled water of the air-cooled tower is 7-10°C, and the outlet temperature of the compressed air of the air-cooled tower is 10-15°C.

[0016] Preferably, the air-cooled tower is equipped with a first liquid level control valve at the bottom.

[0017] Preferably, a packing zone is provided between the waste nitrogen inlet and the chilled water inlet of the water-cooled tower, and the packing zone is filled with polypropylene rings Dg50. Since the water-cooled tower is an ambient temperature tower, ordinary polypropylene rings are suitable for operation under normal pressure conditions; therefore, polypropylene rings are used as packing material in the water-cooled tower.

[0018] Preferably, a chilled water pump is provided between the chilled water outlet of the water-cooled tower and the chilled water inlet of the air-cooled tower.

[0019] Preferably, a second liquid level control valve is provided at the bottom of the water-cooled tower.

[0020] The beneficial effects of this invention are as follows: This invention utilizes a hot water heat exchanger to reduce the temperature of the compressed air entering the air-cooled tower. On the one hand, it combines the waste heat of the compressed air from the air separation unit with the heat demand of the hot water station, improving heat utilization efficiency and saving steam consumption for hot water heating in cold regions during winter, thus reducing energy consumption and heating costs. On the other hand, because the hot water heat exchanger displaces a portion of the heat, the water consumption for initial cooling in the air-cooled tower and the electricity consumption of the cooling water pump are reduced by nearly half. This effectively reduces the plant's water and electricity consumption and operating costs, and also allows for a smaller air-cooled tower equipment size, reducing equipment investment. By arranging level control valves at the bottom of the air-cooled tower and water-cooled tower, and controlling the relatively independent drainage volume rather than the input and output of other materials, a dynamic balance in the compressed air heat exchange process is maintained, ensuring a stable and continuous production state for the continuous process.

[0021] The above description is merely an overview of the technical solution of this utility model. In order to better understand the technical means of this utility model and to implement it according to the contents of the specification, the preferred embodiments of this utility model are described in detail below with reference to the accompanying drawings. The specific implementation methods of this utility model are given in detail in the following embodiments and their accompanying drawings. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the present invention and form part of this application, illustrate exemplary embodiments of the present invention and, together with the description thereof, serve to explain the present invention and do not constitute an undue limitation thereof. In the drawings:

[0023] Figure 1 A schematic diagram of a precooling system framework for an air separation unit suitable for cold regions, provided in Embodiment 1 of this utility model;

[0024] The attached diagram lists the components represented by each number as follows:

[0025] 1. Air compressor; 1.1 Air inlet of air compressor; 1.2 Compressed air outlet of air compressor; 2. Hot water heat exchanger; 2.1 Compressed air inlet of hot water heat exchanger; 2.2 Compressed air outlet of hot water heat exchanger; 2.3 Circulating hot water inlet; 2.4 Circulating hot water outlet; 3. Air-cooled tower; 3.1 Cooling water section; 3.2 Chilled water section; 3.3 Chilled water inlet; 3.4 Circulating cooling water inlet; 3.5 Compressed air inlet of air-cooled tower; 3.6 Exhaust pipe; 3.7 First liquid level control valve; 3.8 Top air outlet section; 3.9 Liquid collection section; 4. Water-cooled tower; 4.1 Chilled water outlet; 4.2 Sludge nitrogen inlet; 4.3 Circulating feed water inlet; 4.4 Second liquid level control valve; 5. Air filter; 5.1 Air outlet of air filter; 6. Cooling water pump; 7. Chilled water pump. Detailed Implementation

[0026] The following is in conjunction with the appendix Figure 1 The principles and features of this utility model are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of this utility model. The utility model is described more specifically in the following paragraphs by way of example with reference to the accompanying drawings. The advantages and features of this utility model will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this utility model.

[0027] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0028] 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 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.

[0029] The working principle of this invention is as follows: Atmospheric air, after being filtered by a self-cleaning air filter 5 to remove dust and other mechanical impurities, enters the air compressor 1. The compressed air, after being compressed by the air compressor 1, reaches approximately 105°C. It first enters the hot water heat exchanger 2 to exchange heat with circulating hot water from the hot water station. The heated circulating hot water is then used for heating throughout the plant. The compressed air, after being cooled by the hot water heat exchanger 2, then enters the air-cooled tower 3. The cooling water entering the air-cooled tower 3 is divided into two parts: circulating cooling water from the pipeline network is pressurized by the cooling water pump 6 and sprayed from the middle of the air-cooled tower 3 to initially cool and clean the compressed air entering the air-cooled tower 3; chilled water from the water-cooled tower 4, cooled by sludge nitrogen, is pressurized by the chilled water pump 7 and sprayed from the top of the air-cooled tower 3 to further cool the compressed air. The compressed air, after undergoing secondary cooling, is discharged from the top of the air-cooled tower 3 and then enters the subsequent molecular sieve purification system.

[0030] Example 1

[0031] like Figure 1 As shown, this embodiment provides a precooling system for an air separation unit suitable for cold regions, including: an air filter 5, an air compressor 1, a hot water heat exchanger 2, an air-cooled tower 3, and a water-cooled tower 4.

[0032] The air outlet 5.1 of the air filter is connected to the air inlet 1.1 of the air compressor. The compressed air outlet 1.2 of the air compressor is connected to the compressed air inlet 2.1 of the hot water heat exchanger. The compressed air outlet 2.2 of the hot water heat exchanger is connected to the compressed air inlet 3.5 of the air-cooled tower. The hot water heat exchanger 2 is equipped with a circulating hot water inlet 2.3 connected to the hot water station in the plant area and a circulating hot water outlet 2.4 for hot water users throughout the plant.

[0033] The air-cooled tower 3 includes a cooling water section 3.1 and a chilled water section 3.2. The chilled water section 3.2 is filled with reinforced polypropylene ring Dg50 packing and is located in the upper part of the air-cooled tower 3. The cooling water section 3.1 is filled with reinforced polypropylene ring Dg76 and stainless steel ring Dg76 packing and is located in the lower part of the air-cooled tower 3. The top of the chilled water section 3.2 and the top of the air-cooled tower 3 form a top air outlet section 3.8, and the bottom of the cooling water section 3.1 and the bottom of the air-cooled tower 3 form a liquid collection section 3.9. The height of the chilled water section 3.2 is 30-40% of the height of the air-cooled tower, and the height of the cooling water section 3.1 is 15-20% of the height of the air-cooled tower.

[0034] The chilled water section 3.2 is equipped with a chilled water inlet 3.3, which is connected to the chilled water outlet 4.1 of the water-cooled tower 4. The cooling water section 3.1 is equipped with a circulating cooling water inlet 3.4, and the circulating cooling water inlet 3.4 of the air-cooled tower 3 is connected to a cooling water pump 6. The circulating cooling water is pressurized by the pump and sprayed down from the cooling water section 3.2. The compressed air inlet 3.5 of the air-cooled tower is located below the circulating cooling water inlet 3.4. The exhaust pipe 3.6 of the air-cooled tower 3 is located at the top air outlet section 3.8, and the liquid collection section 3.9 is equipped with a water outlet pipe.

[0035] The liquid collection section 3.9 of the air-cooled tower 3 is equipped with a first liquid level control valve 3.7. The liquid level threshold of the first liquid level control valve is set to 1 / 16 to 1 / 12 of the height of the air-cooled tower 3. When the liquid level of the air-cooled tower 3 exceeds the set threshold, the first liquid level control valve 3.7 controls the opening of the water outlet pipe at the bottom of the air-cooled tower 3.

[0036] The chilled water outlet 4.1 of the water-cooled tower 4 is sequentially connected to a nitrogen inlet 4.2 and a circulating water inlet 4.3. A packing zone 4.5 is located between the nitrogen inlet 4.2 and the circulating water inlet of the water-cooled tower 4, and the packing zone 4.5 is filled with polypropylene rings Dg50. A chilled water pump 7 is installed between the chilled water outlet 4.1 of the water-cooled tower 4 and the chilled water inlet 3.3 of the air-cooled tower 3.

[0037] The bottom of the water-cooled tower 4 is equipped with a second liquid level control valve 4.4. The liquid level threshold of the second liquid level control valve 4.4 is set to 1 / 16 to 1 / 12 of the height of the water-cooled tower 4. When the liquid level of the water-cooled tower 4 exceeds the set threshold, the second liquid level control valve 4.4 controls the opening of the circulating water inlet pipe at the bottom of the water-cooled tower 4.

[0038] In this embodiment, 44,000 Nm 3 Taking an oxygen production air separation unit with a capacity of [number] h as an example, atmospheric air enters the air compressor 1 after dust and other mechanical impurities are removed by the air filter 5. The air compressor 1 discharges compressed air (outlet temperature: 105℃, outlet pressure: 0.49MPag, outlet flow rate: 243000Nm). 3 The compressed air (t / h) enters the hot water heat exchanger 2, where it exchanges heat with the circulating hot water (temperature: 60℃, pressure: 0.8MPag, flow rate: 134t / h) from the plant's hot water station. The circulating hot water is heated to 80℃ and then supplied for heating throughout the plant. The compressed air is cooled to 70℃ and enters the air-cooled tower 3. The circulating cooling water is pressurized by the cooling water pump 6 (temperature: 32℃, pressure: 0.9MPag, flow rate: 270t / h) and sprayed from the cooling water section 3.1 of the air-cooled tower 3, providing initial cooling and cleaning to the compressed air entering the tower. Chilled water from the water-cooled tower 4, cooled by sludge nitrogen, is sprayed from the chilled water section 3.2 of the air-cooled tower 3 to further cool the compressed air. The compressed air exiting the air-cooled tower 3 is approximately 13℃ and then enters the subsequent molecular sieve purification system.

[0039] Table 1 shows a comparison of material consumption between conventional air separation units and the air separation unit of this embodiment during winter in cold regions:

[0040] Table 1 Material Consumption of Traditional Air Separation Unit and Air Separation Unit in This Embodiment

[0041]

[0042]

[0043] (Note: Low-pressure steam specifications: Temperature: 158℃, Pressure: 0.5MPag)

[0044] As shown in the table, the traditional air separation process consumes 540 t / h of cooling water and 82 kW of electricity for the initial precooling of the air-cooled tower. In contrast, the air separation process of this invention consumes only 270 t / h of cooling water and only 43 kW of electricity for the initial precooling of the air-cooled tower. This represents a 50% reduction in both water and electricity consumption. Furthermore, by utilizing the heat from the compressed air after air compressor operation, it saves 6 t / h of low-pressure steam consumption from the thermal power plant. Based on a factory in a cold region requiring heating for five months of the year, the total operating cost savings of this invention compared to the traditional air separation process is 1.5353 million yuan per year. Simultaneously, due to the reduced temperature and volume of the compressed air entering the air-cooled tower 3, the cooling water consumption is reduced, allowing for a corresponding reduction in the size of the air-cooled tower 3 equipment, thus lowering equipment investment to some extent.

[0045] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model in any way. Those skilled in the art can readily implement this utility model based on the accompanying drawings and the above description. However, any modifications, alterations, or equivalent variations made by those skilled in the art without departing from the scope of the utility model's technical solution, utilizing the disclosed technical content, are considered equivalent embodiments of this utility model. Furthermore, any equivalent changes, alterations, or variations made to the above embodiments based on the essential technology of this utility model are still within the protection scope of this utility model's technical solution.

Claims

1. A precooling system for air separation units suitable for cold regions, characterized in that, include: Air compressor (1), hot water heat exchanger (2), air-cooled tower (3) and water-cooled tower (4); The compressed air outlet (1.2) of the air compressor is connected to the compressed air inlet (2.1) of the hot water heat exchanger, and the compressed air outlet (2.2) of the hot water heat exchanger is connected to the compressed air inlet (3.5) of the air-cooled tower; the hot water heat exchanger (2) is equipped with a circulating hot water inlet (2.3) and a circulating hot water outlet (2.4) connected to the hot water station in the plant area; The air-cooled tower (3) includes a cooling water section (3.1) and a chilled water section (3.2). The chilled water section (3.2) is located on the upper part of the tower body of the air-cooled tower (3), and the cooling water section (3.1) is located on the lower part of the tower body of the air-cooled tower (3). The chilled water section (3.2) is provided with a chilled water inlet (3.3), and the cooling water section (3.1) is provided with a circulating cooling water inlet (3.4). The compressed air inlet (3.5) of the air-cooled tower is located below the circulating cooling water inlet (3.4). The top of the air-cooled tower (3) is provided with an exhaust pipe (3.6). The chilled water inlet (3.3) of the air-cooled tower (3) is connected to the chilled water outlet (4.1) of the water-cooled tower (4). The chilled water outlet (4.1) of the water-cooled tower (4) is provided with a nitrogen inlet (4.2) and a circulating water inlet (4.3) in sequence.

2. The pre-cooling system for air separation unit in cold region as claimed in claim 1, wherein It also includes an air filter (5), the air outlet (5.1) of which is connected to the air inlet (1.1) of the air compressor.

3. The pre-cooling system for air separation unit in cold region as claimed in claim 1 wherein, The height of the chilled water section (3.2) is 30-40% of the height of the air-cooled tower (3), and the height of the cooling water section (3.1) is 15-20% of the height of the air-cooled tower (3).

4. The pre-cooling system for air separation unit in cold region as claimed in claim 3, wherein A top air outlet section (3.8) is formed between the top of the chilled water section (3.2) and the top of the air-cooled tower (3), and the exhaust pipe (3.6) of the air-cooled tower (3) is located in the top air outlet section (3.8); a liquid collection section (3.9) is formed between the bottom of the cooling water section (3.1) and the bottom of the air-cooled tower (3); and the liquid collection section (3.9) is provided with a water outlet pipe.

5. The pre-cooling system for air separation unit in cold region as claimed in claim 1 wherein, The cooling water section (3.1) is provided with reinforced polypropylene ring Dg76 and stainless steel ring Dg76, and the chilled water section (3.2) is provided with reinforced polypropylene ring Dg50.

6. The pre-cooling system for air separation unit in cold region as claimed in claim 1 wherein, The air-cooled tower (3) has a circulating cooling water inlet (3.4) connected to a cooling water pump (6).

7. The pre-cooling system for air separation unit applicable in cold region according to claim 1, characterized in that, The liquid collection section of the air-cooled tower (3) is equipped with a first liquid level control valve (3.7).

8. The pre-cooling system for air separation unit applicable in cold region according to claim 1, characterized in that, A packing zone (4.5) is provided between the waste nitrogen inlet (4.2) of the water cooling tower (4) and the circulating water inlet (4.3) of the water cooling tower (4), and the packing zone (4.5) is filled with polypropylene rings Dg50.

9. A precooling system for air separation units suitable for cold regions according to claim 7, characterized in that, A chilled water pump (7) is provided between the chilled water outlet (4.1) of the water-cooled tower (4) and the chilled water inlet (3.3) of the air-cooled tower (3).

10. The pre-cooling system for air separation unit applicable in cold region according to claim 7, characterized in that, The bottom of the water-cooled tower (4) is equipped with a second liquid level control valve (4.4).

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