Cryogenic air separation circulating water energy-saving system

Abstract

The utility model discloses a deep cooling air separation circulating water energy-saving system which comprises a circulating water return pipeline, a waste nitrogen supply pipeline, a waste nitrogen recovery pipeline, a precooler and double-section cooling devices arranged on all sections of air compressor output pipelines, and each double-section cooling device comprises a heat exchanger and a water cooler. A refrigerant inlet of the heat exchanger is connected with a waste nitrogen supply pipeline; the water outlet side of the circulating water return pipeline is connected with a heating medium inlet of the precooler, and a refrigerant inlet of the precooler is connected with the gas outlet side of the waste nitrogen recycling pipeline. A double-section cooling device is adopted, before circulating water cools compressed air of all sections, a heat exchanger is used for primary cooling, a cooling medium of the heat exchanger is waste nitrogen from a fractionating tower, meanwhile, residual cooling capacity obtained after heat exchange of the waste nitrogen is used for pre-cooling backflow circulating water, the waste nitrogen is fully used for heat exchange cooling, and the cooling efficiency is improved. Therefore, the energy consumption of the circulating water cooling system is reduced, and the waste nitrogen can be directly discharged after heat exchange.

Description

Technical Field

[0001] The utility model relates to the technical field of air separation systems, in particular to a deep-cold air separation circulating water energy-saving system. Background Art

[0002] At present, the air compressor of the deep cold air separation system generally adopts four-stage pressurization. After each stage of air is compressed, a certain amount of heat will be generated, which will increase the air temperature. In order to reduce the temperature of the compressed air, technical personnel in this field use circulating water cooling to reduce the air temperature and meet the intake temperature requirements, such as the intake temperature of the distillation system for distillation. Since the temperature of the circulating water will increase after heat exchange, it needs to be cooled before it can be recycled again. The circulating water cooling currently adopts a cooling unit, which is composed of a water pump, a water chiller, a cooling tower and other equipment. In order to reduce the temperature of the circulating water, there is a technical problem of large energy consumption. Summary of the invention

[0003] In order to solve the above technical problems, the utility model provides a deep cold air separation circulating water energy saving system. In order to have a basic understanding of some aspects of the disclosed embodiments, a simple summary is given below. This summary is not a general review, nor is it intended to identify key / important components or describe the scope of protection of these embodiments. Its only purpose is to present some concepts in a simple form as a preface to the detailed description that follows.

[0004] The utility model adopts the following technical solutions:

[0005] Provided is a deep-cold air separation circulating water energy-saving system, comprising: a circulating water return pipeline; further comprising: a dirty nitrogen supply pipeline, a dirty nitrogen recovery pipeline, a precooler, and a two-stage cooling device arranged on the output pipeline of each section of the air compressor, and the two-stage cooling device comprises: a heat exchanger and a water cooler;

[0006] The heat medium outlet of the heat exchanger is connected to the heat medium inlet of the water cooler, the cold medium inlet of the heat exchanger is connected to the dirty nitrogen supply pipeline, and the air inlet side of the dirty nitrogen supply pipeline is connected to the fractionation tower in the air separation system;

[0007] The refrigerant outlet of the water cooler is connected to the circulating water return pipeline, the water outlet side of the circulating water return pipeline is connected to the heat medium inlet of the precooler, and the refrigerant inlet of the precooler is connected to the gas outlet side of the contaminated nitrogen recovery pipeline.

[0008] Furthermore, the heat medium inlet of the heat exchanger is connected to the output port of the air compressor, and the refrigerant outlet of the heat exchanger is connected to the air inlet side of the contaminated nitrogen recovery pipeline.

[0009] Furthermore, the air inlet side of the contaminated nitrogen gas recovery pipeline is provided with a first recovery air port, a second recovery air port, a third recovery air port and a fourth recovery air port in sequence according to the contaminated nitrogen gas conveying direction; the refrigerant outlet of the heat exchanger located between the first stage air compressor and the second stage air compressor is connected to the first recovery air port; the refrigerant outlet of the heat exchanger located between the second stage air compressor and the third stage air compressor is connected to the second recovery air port; the refrigerant outlet of the heat exchanger located between the third stage air compressor and the fourth stage air compressor is connected to the third recovery air port; the refrigerant outlet of the heat exchanger located on the output pipeline of the fourth stage air compressor is connected to the fourth recovery air port.

[0010] Furthermore, a flow divider is arranged on the contaminated nitrogen gas supply pipeline, and the flow divider is provided with a first air supply port, a second air supply port, a third air supply port and a fourth air supply port with gradually decreasing air supply diameters; the refrigerant inlet of the heat exchanger located between the first stage air compressor and the second stage air compressor is connected to the first air supply port; the refrigerant inlet of the heat exchanger located between the second stage air compressor and the third stage air compressor is connected to the second air supply port; the refrigerant inlet of the heat exchanger located between the third stage air compressor and the fourth stage air compressor is connected to the third air supply port; the refrigerant inlet of the heat exchanger located on the output pipeline of the fourth stage air compressor is connected to the fourth air supply port.

[0011] Furthermore, the refrigerant outlet of the precooler is connected to the venting pipeline at the top of the water cooling tower, and the heat medium outlet of the precooler is connected to the circulating water cooling unit.

[0012] Furthermore, the deep-cold air separation circulating water energy-saving system also includes: a circulating water cooling water pipeline, and the circulating water cooling water pipeline is connected to the circulating water cooling unit; the heat medium outlet of the water cooler is connected to the input port of the air compressor, and the refrigerant inlet of the water cooler is connected to the circulating water cooling water pipeline.

[0013] Furthermore, the deep-cold air separation circulating water energy-saving system also includes: a residual liquid storage tank and a heat exchanger; the heat medium inlet of the heat exchanger is connected to the heat medium outlet of the water cooler located on the four-stage air compressor output pipeline, and the heat medium outlet of the heat exchanger is connected to the air cooling tower; the residual liquid storage tank is connected to the refrigerant inlet of the heat exchanger.

[0014] The beneficial effects brought by the utility model are as follows: the application adopts a two-stage cooling device, and before the circulating water cools down the compressed air of each section, a heat exchanger is used for preliminary cooling, and the cooling medium of the heat exchanger is the dirty nitrogen from the distillation tower, and the residual cooling capacity after the heat exchange of the dirty nitrogen is used to pre-cool the reflux circulating water. The application makes full use of the dirty nitrogen for heat exchange and cooling, thereby reducing the return water temperature of the circulating water, thereby reducing the energy consumption of the circulating water cooling system, and the dirty nitrogen can be directly discharged after heat exchange without pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 It is a schematic diagram of a deep-cold air separation circulating water energy-saving system of the utility model. DETAILED DESCRIPTION

[0017] The following is a detailed description of the embodiments of the utility model in conjunction with the accompanying drawings. It should be clear that the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] At present, the air compressors of the cryogenic air separation system generally adopt four-stage pressurization. In this embodiment, each stage of the air compressor is marked as a first-stage air compressor 101, a second-stage air compressor 102, a third-stage air compressor 103, and a fourth-stage air compressor 104.

[0019] like Figure 1 As shown, in some illustrative embodiments, a deep-cold air separation circulating water energy-saving system is provided, including: a circulating water cooling water pipeline 1, a circulating water return pipeline 2, a dirty nitrogen supply pipeline 3, a dirty nitrogen recovery pipeline 4, a precooler 5, a residual liquid storage tank 6, a heat exchanger 7 and a two-stage cooling device.

[0020] A two-stage cooling device is provided on the output pipeline of each section of the air compressor, wherein the output pipeline of the air compressor refers to the pipeline used to transport compressed air. The two-stage cooling device includes: a heat exchanger 8 and a water cooler 9, and the heat exchanger 8 is located on the input side of the water cooler 9, that is, the compressed air output by the air compressor first enters the heat exchanger 8 for the first heat exchange and cooling, and then enters the water cooler 9 for the second heat exchange and cooling, thereby reducing the requirement for the temperature of the cooling medium used by the water cooler 9.

[0021] The heat medium inlet of the heat exchanger 8 is connected to the output port of the air compressor, and the heat medium outlet of the heat exchanger 8 is connected to the heat medium inlet of the water cooler 9, so that the compressed air output by the air compressor is cooled twice through the heat exchanger 8 and the water cooler 9 in sequence.

[0022] The cooling medium used by the heat exchanger 8 is the dirty nitrogen gas from the fractionation tower. The refrigerant inlet of the heat exchanger 8 is connected to the dirty nitrogen gas supply pipeline 3, and the air inlet side of the dirty nitrogen gas supply pipeline 3 is connected to the fractionation tower 10 in the air separation system. The refrigerant outlet of the heat exchanger 8 is connected to the air inlet side of the dirty nitrogen gas recovery pipeline 4, and the dirty nitrogen gas after heat exchange is transported to the next heat exchange equipment by the dirty nitrogen gas recovery pipeline 4.

[0023] The air inlet side of the contaminated nitrogen recovery pipeline 4 is provided with a first recovery air port 401, a second recovery air port 402, a third recovery air port 403 and a fourth recovery air port 404 in sequence according to the contaminated nitrogen delivery direction. The refrigerant outlet of the heat exchanger 8 located between the first stage air compressor 101 and the second stage air compressor 102 is connected to the first recovery air port 401; the refrigerant outlet of the heat exchanger 8 located between the second stage air compressor 102 and the third stage air compressor 103 is connected to the second recovery air port 402. The refrigerant outlet of the heat exchanger 8 located between the third stage air compressor 103 and the fourth stage air compressor 104 is connected to the third recovery air port 403. The refrigerant outlet of the heat exchanger 8 located on the output pipeline of the fourth stage air compressor 104 is connected to the fourth recovery air port 404. The above structural design enables the contaminated nitrogen gas after heat exchange in each stage to be discharged into the contaminated nitrogen gas recovery pipeline 4 in the order of cooling of the compressed air. This can ensure the stability of gas transportation and better match the energy consumption during gas transportation, further improving the utilization rate of the contaminated nitrogen gas cooling capacity.

[0024] A flow divider is provided on the dirty nitrogen supply pipeline 3, and the flow divider is provided with a first air supply port 301, a second air supply port 302, a third air supply port 303 and a fourth air supply port 304 with gradually decreasing air supply diameters. The refrigerant inlet of the heat exchanger 8 located between the first stage air compressor 101 and the second stage air compressor 102 is connected to the first air supply port 301. The refrigerant inlet of the heat exchanger 8 located between the second stage air compressor 102 and the third stage air compressor 103 is connected to the second air supply port 302. The refrigerant inlet of the heat exchanger 8 located between the third stage air compressor 103 and the fourth stage air compressor 104 is connected to the third air supply port 303. The refrigerant inlet of the heat exchanger 8 located on the output pipeline of the fourth stage air compressor 104 is connected to the fourth air supply port 304. The above structural design ensures that the dirty nitrogen gas used for heat exchange in each stage is sent into the air compressor output pipeline according to the dirty nitrogen gas transportation direction and corresponds to the cooling order of the compressed air, and the dirty nitrogen gas supply volume is gradually reduced. Firstly, it can ensure the stability of gas transportation, and secondly, it can better match the changing trend of compressed air compression and cooling gas volume and the energy consumption during gas transportation, further improving the utilization rate of dirty nitrogen gas cooling capacity.

[0025] The heat medium inlet of the water cooler 9 is connected to the heat medium outlet of the heat exchanger 8. The heat medium outlet of the water cooler 9 is connected to the input port of the air compressor. In the first three stages, the compressed air cooled by the water cooler 9 enters the air compressor of the next stage, but the heat medium outlet of the water cooler 9 located on the output pipeline of the four-stage air compressor 104 is connected to the heat exchange system of the next process, such as the air cooling tower 11, and then enters the air cooling tower 11 after pre-cooling through the heat exchanger 7 of this embodiment.

[0026] The heat medium inlet of the heat exchanger 7 is connected to the heat medium outlet of the water cooler 9 located on the output pipeline of the four-stage air compressor 104, and the heat medium outlet of the heat exchanger 7 is connected to the air cooling tower 11; the residual liquid storage tank 6 is connected to the refrigerant inlet of the heat exchanger 7. The residual liquid storage tank 6 contains some residual liquid generated by the air separation process, which absorbs heat when it is gasified. Therefore, the residual liquid in the residual liquid storage tank 6 can be used as the compressed air of the compression stage for further cooling to reduce the energy consumption of the air cooling tower 11.

[0027] The refrigerant outlet of the water cooler 9 is connected to the circulating water return pipeline 2, and the water outlet side of the circulating water return pipeline 2 is connected to the heat medium inlet of the precooler 5. The circulating water with increased temperature output by the water cooler 9 is sent to the precooler 5 by the circulating water return pipeline 2 for pre-cooling, so as to further reduce the energy consumption required for circulating water cooling. The refrigerant inlet of the precooler 5 is connected to the outlet side of the dirty nitrogen recovery pipeline 4, that is, the cooling medium used by the precooler 5 is the residual cooling capacity of the dirty nitrogen, that is, the residual cooling capacity after cooling the compressed air. The refrigerant outlet of the precooler 5 is connected to the venting pipeline at the top of the water cooling tower 12, and the dirty nitrogen can be directly discharged into the atmosphere after completing the heat exchange, which is pollution-free, safe and environmentally friendly. The heat medium outlet of the precooler 5 is connected to the circulating water cooling unit 13, that is, the circulating water after preliminary cooling by the precooler 5 enters the circulating water cooling unit 13 for final cooling, further reducing the energy consumption of the circulating water cooling unit 13. The circulating water cooling water pipeline 1 is connected to the circulating water cooling unit 13. The circulating water cooled by the circulating water cooling unit 13 enters the compression stage again to cool the compressed air circulation. The refrigerant inlet of the water cooler 9 is connected to the circulating water cooling water pipeline 1.

[0028] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A deep-cold air separation circulating water energy-saving system, comprising: Circulating water return pipeline; characterized in that it also includes: a dirty nitrogen supply pipeline, a dirty nitrogen recovery pipeline, a precooler and a two-stage cooling device arranged on the output pipeline of each section of the air compressor, and the two-stage cooling device includes: a heat exchanger and a water cooler; The heat medium outlet of the heat exchanger is connected to the heat medium inlet of the water cooler, the cold medium inlet of the heat exchanger is connected to the dirty nitrogen supply pipeline, and the air inlet side of the dirty nitrogen supply pipeline is connected to the fractionation tower in the air separation system; The refrigerant outlet of the water cooler is connected to the circulating water return pipeline, the water outlet side of the circulating water return pipeline is connected to the heat medium inlet of the precooler, and the refrigerant inlet of the precooler is connected to the gas outlet side of the contaminated nitrogen recovery pipeline.

2. A deep-cold air separation circulating water energy-saving system according to claim 1, characterized in that: The heat medium inlet of the heat exchanger is connected to the output port of the air compressor, and the refrigerant outlet of the heat exchanger is connected to the air inlet side of the contaminated nitrogen recovery pipeline.

3. A deep-cold air separation circulating water energy-saving system according to claim 2, characterized in that: The air inlet side of the contaminated nitrogen gas recovery pipeline is provided with a first recovery air port, a second recovery air port, a third recovery air port and a fourth recovery air port in sequence according to the contaminated nitrogen gas conveying direction; the refrigerant outlet of the heat exchanger located between the first stage air compressor and the second stage air compressor is connected to the first recovery air port; the refrigerant outlet of the heat exchanger located between the second stage air compressor and the third stage air compressor is connected to the second recovery air port; the refrigerant outlet of the heat exchanger located between the third stage air compressor and the fourth stage air compressor is connected to the third recovery air port; the refrigerant outlet of the heat exchanger located on the output pipeline of the fourth stage air compressor is connected to the fourth recovery air port.

4. A deep-cold air separation circulating water energy-saving system according to claim 3, characterized in that: A flow divider is arranged on the dirty nitrogen gas supply pipeline, and the flow divider is provided with a first air supply port, a second air supply port, a third air supply port and a fourth air supply port with gradually decreasing air supply diameters; the refrigerant inlet of the heat exchanger located between the first-stage air compressor and the second-stage air compressor is connected to the first air supply port; the refrigerant inlet of the heat exchanger located between the second-stage air compressor and the third-stage air compressor is connected to the second air supply port; the refrigerant inlet of the heat exchanger located between the third-stage air compressor and the fourth-stage air compressor is connected to the third air supply port; the refrigerant inlet of the heat exchanger located on the output pipeline of the fourth-stage air compressor is connected to the fourth air supply port.

5. A deep-cold air separation circulating water energy-saving system according to claim 4, characterized in that: The refrigerant outlet of the precooler is connected to the venting pipeline at the top of the water cooling tower, and the heat medium outlet of the precooler is connected to the circulating water cooling unit.

6. A deep-cold air separation circulating water energy-saving system according to claim 5, characterized in that: Also includes: A circulating water cooling water pipeline is connected to a circulating water cooling unit; the heat medium outlet of the water cooler is connected to the input port of the air compressor, and the refrigerant inlet of the water cooler is connected to the circulating water cooling water pipeline.

7. A deep-cold air separation circulating water energy-saving system according to claim 6, characterized in that: Also includes: A residual liquid storage tank and a heat exchanger; the heat medium inlet of the heat exchanger is connected to the heat medium outlet of the water cooler located on the output pipeline of the four-stage air compressor, and the heat medium outlet of the heat exchanger is connected to the air cooling tower; the residual liquid storage tank is connected to the refrigerant inlet of the heat exchanger.

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