Pre-cooling system and air separation equipment

Abstract

The utility model provides a pre-cooling system and air separation equipment. The pre-cooling system comprises an air cooling tower and a pipeline system. The pipeline system comprises a water inlet pipe used for introducing cooling water from the outside. The pre-cooling system further comprises a first heat exchanger. The pipeline system further comprises a cooling liquid pipeline. And the cooling liquid pipeline is used for conveying discharge liquid discharged from the bottom of the air cooling tower to a cooling liquid inlet of the air cooling tower. The cooling liquid pipeline and the water inlet pipe are arranged to exchange heat with each other in the first heat exchanger, so that the discharge liquid in the cooling liquid pipeline is cooled. The pre-cooling system can reduce energy consumption.

Description

Technical Field

[0001] The utility model belongs to the field of air separation and relates to an air separation device, more specifically, to a precooling system. Background Art

[0002] Air separation plants often require a pre-cooling system to pre-cool the feed air. The pre-cooled feed air then enters a purification system such as an adsorber to remove impurities.

[0003] Chinese utility model patent CN214199400U discloses a pre-cooling system. A portion of the cooling water from the cooling water system is pumped by a cooling water pump through the cooling water inlet into an air-cooling tower. Another portion of the cooling water enters the water-cooling tower, where it exchanges heat with low-temperature contaminated nitrogen, reducing its temperature and becoming chilled water. The chilled water, pumped by the chilled water pump, enters the air-cooling tower through the chilled water inlet. After entering the air-cooling tower, the feed air exchanges heat with the cooling water entering through the cooling water inlet and the chilled water entering through the chilled water inlet, thereby being cooled.

[0004] The inventors analyzed that the cooling water pumps and chilled water pumps in the aforementioned pre-cooling system not only need to overcome head loss in the piping system but also need to pressurize the water in the pipes to the required pressure within the air-cooling tower, resulting in high energy consumption. Especially for situations where the required pressure within the air-cooling tower is high, a pre-cooling system that can reduce energy consumption is needed.

[0005] Therefore, how to optimize the pre-cooling system to reduce its energy consumption is a problem that needs to be solved. Utility Model Content

[0006] The purpose of the utility model is to provide a pre-cooling system which can reduce energy consumption.

[0007] The utility model provides a precooling system comprising an air-cooling tower and a piping system. The piping system includes a water inlet pipe for introducing cooling water from an external source. The precooling system also includes a first heat exchanger. The piping system also includes a coolant pipeline. The coolant pipeline transports effluent discharged from the bottom of the air-cooling tower to a coolant inlet of the air-cooling tower. The coolant pipeline and the water inlet pipe are configured to exchange heat with each other in the first heat exchanger, thereby reducing the temperature of the effluent in the coolant pipeline.

[0008] In one embodiment, the air-cooling tower further comprises a refrigerant inlet, which receives a lower temperature liquid than the cooling liquid inlet. The pre-cooling system further comprises a nitrogen water tower, wherein the refrigerant stream chilled by the nitrogen water tower is fed into the refrigerant inlet of the air-cooling tower. The piping system further comprises a first liquid infusion pipe extending from a branch point of the cooling liquid pipeline, the first liquid infusion pipe feeding a portion of the discharge liquid from the cooling liquid pipeline, which has been cooled by the first heat exchanger, into the nitrogen water tower.

[0009] In one embodiment, the pre-cooling system further comprises a first pump, which is disposed in the coolant pipeline at a position downstream of the first heat exchanger.

[0010] In one embodiment, the branching location is located between the first pump and the first heat exchanger.

[0011] In one embodiment, the precooling system further comprises a second pump, which is provided on an output pipeline connected between the nitrogen water tower and the refrigerant inlet of the air cooling tower, so as to deliver the refrigerant flow chilled by the nitrogen water tower to the refrigerant inlet.

[0012] In one embodiment, the pre-cooling system further includes a nitrogen water tower and a second heat exchanger. The air cooling tower also has a refrigerant inlet, and the temperature of the liquid received by the refrigerant inlet is lower than that of the cooling liquid inlet. The piping system also includes an output pipeline, and the piping system also includes a second liquid infusion pipe drawn from a branch position of the cooling liquid pipeline. The output pipeline is used to send the frozen flow frozen by the nitrogen water tower into the second heat exchanger, and the second liquid infusion pipe is used to send a part of the discharge liquid cooled by the first heat exchanger in the cooling liquid pipeline into the refrigerant inlet through the second heat exchanger. The output pipeline and the second liquid infusion pipe are arranged to exchange heat with each other in the second heat exchanger, so that a part of the discharge liquid cooled by the first heat exchanger is further cooled.

[0013] In one embodiment, the output pipeline passes through the second heat exchanger and then leads to the water inlet of the nitrogen-water tower.

[0014] In one embodiment, the pre-cooling system further comprises a first pump, which is disposed in the coolant pipeline at a position upstream of the first heat exchanger.

[0015] In one embodiment, the pre-cooling system further comprises a second pump, which is disposed in the output pipeline at a position upstream of the second heat exchanger.

[0016] The utility model also provides an air separation plant comprising the aforementioned precooling system, a cooling water tower, and a feed pipeline for supplying air. The precooling system's water inlet pipe introduces cooling water from the cooling water tower. Air in the feed pipeline, in the precooling system's air cooling tower, sequentially contacts the coolant and refrigerant in the precooling system for heat exchange and is subsequently cooled.

[0017] In the aforementioned precooling system and air separation plant, the effluent from the air-cooling tower is cooled by exchanging heat with cooling water in the first heat exchanger, and then used as the coolant input to the air-cooling tower. Compared to directly inputting cooling water into the air-cooling tower, this reduces the pressurization requirements for the stream, thereby reducing energy consumption, especially the energy consumption of the pumping equipment in the pipeline, and thus saving operating costs.

[0018] Furthermore, a portion of the discharge liquid from the air-cooling tower is cooled by heat exchange with cooling water in the first heat exchanger, thus serving as the coolant input to the air-cooling tower. Simultaneously, another portion of the discharge liquid is cooled by heat exchange with the refrigerated stream in the second heat exchanger, thus serving as the refrigerant input to the air-cooling tower. This reduces energy consumption of the pumping equipment in the refrigerant delivery pipeline, further saving operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The advantages and spirit of the present invention can be further understood through the following detailed description of the present invention and the accompanying drawings.

[0020] Figure 1 is a schematic diagram of an exemplary pre-cooling system according to a first embodiment.

[0021] Figure 2 is a schematic diagram of an exemplary pre-cooling system according to a second embodiment. DETAILED DESCRIPTION

[0022] The following describes in detail the specific embodiments of the present invention in conjunction with the accompanying drawings. However, it should be understood that the present invention is not limited to the embodiments described below, and the technical concept of the present invention can be implemented in combination with other known technologies or functions, or other technologies that are the same as those known technologies.

[0023] For example, a description later in the specification of a first feature being formed above or on a second feature may include an embodiment in which the first and second features are directly connected, or an embodiment in which an additional feature is formed between the first and second features, thereby eliminating the need for a direct connection between the first and second features. Furthermore, when a first element is described as being connected to or coupled to a second element, the description includes embodiments in which the first and second elements are directly connected or coupled to each other, as well as embodiments in which the first and second elements are indirectly connected or coupled to each other using one or more other intervening elements.

[0024] The term "and / or" used in this document includes any and all combinations of one or more related listed items. Unless otherwise indicated, the meaning of all terms (including technical and scientific terms) used in this document is the same as that commonly understood by the common technology in the field to which this utility model belongs. It should also be understood that terms, such as those defined in commonly used dictionaries, should be understood to have a meaning consistent with their meaning in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense unless expressly provided in the text. For the sake of brevity and / or clarity, well-known functions or configurations may not be described in detail.

[0025] Figure 1 and Figure 2The pre-cooling systems 10 and 10a according to two different embodiments are shown in FIG. The same or similar reference numerals are used to represent the same or similar elements in the first embodiment and the second embodiment to omit repeated descriptions and make the overall description more concise.

[0026] Figure 1 In the first embodiment shown, the precooling system 10 includes an air-cooling tower 1 and a piping system 6. The piping system 6 includes an inlet pipe 60 for introducing cooling water L0 from an external source. Examples of the external source include the cooling water system mentioned in the previous background and the cooling water tower 30 described later. The air-cooling tower 1, also commonly referred to in the industry as an air-water tower, is a direct-contact tower structure.

[0027] The precooling system 10 further includes a first heat exchanger 51. The piping system 6 further includes a coolant line 61, which delivers the exhaust liquid L1 discharged from the bottom of the air-cooling tower 1 to the coolant inlet 11 of the air-cooling tower 1. The coolant inlet 11 and the chilled liquid inlet 12 described later are similar to the cooling water inlet and chilled water inlet mentioned above.

[0028] The cooling liquid line 61 and the water inlet pipe 60 are configured to exchange heat with each other in the first heat exchanger 51, thereby reducing the temperature of the exhaust liquid L1 in the cooling liquid line 61. That is, the exhaust liquid L1 cooled by the first heat exchanger 51 enters the air-cooling tower 1 as coolant. In short, the exhaust liquid L1 discharged from the bottom of the air-cooling tower 1 ultimately returns to the air-cooling tower 1 as coolant.

[0029] It can be understood that the terms "pipeline", "pipeline", "pipe section", etc. used herein all refer to the lines for the flow stream to circulate, and do not limit the physical form of the corresponding components. Taking "pipeline" as an example, a pipeline can refer to a segment in a complete pipeline. A pipeline can also be a combination of multiple pipelines connected in sequence. The multiple pipelines can be connected through pipe joints or other pipeline components such as valves. Among them, the space in the pipe joints or other pipeline components for the flow stream to pass through can also be considered as part of the pipeline. For example, Figure 1 In the embodiment, taking the coolant pipe 61 as an example, the passage or space in the first heat exchanger 51 through which the exhaust liquid L1 passes can also be considered as a part of the coolant pipe 61. The heat exchanger herein is, for example, a plate-fin heat exchanger.

[0030] In the pre-cooling system 10, the first heat exchanger 51 is installed to exchange heat between the cooling water L0 and the effluent L1 from the air-cooling tower 1, bringing the effluent L1 to a temperature comparable to that of the cooling water L0. Since the low-temperature effluent L1 originates from the air-cooling tower 1, no further pressurization is required. Therefore, for example, the first pump 31, described later, only needs to compensate for head loss or pressure loss, significantly reducing energy consumption and operating expenses (OPEX).

[0031] Continue to see Figure 1 The air cooling tower 1 also has a refrigerant inlet 12. Compared with the cooling liquid inlet 11, the liquid temperature received by the refrigerant inlet 12 is lower. That is, the air cooling tower 1 is a two-stage or even more-stage air cooling tower. Commonly, the air cooling tower 1 can be as follows Figure 1 The two-stage direct-contact air cooling tower shown includes an upper stage and a lower stage. Generally, similar to the background description above, the coolant inlet 11 of the air cooling tower 1 receives cooling water, while the chilled liquid inlet 12 receives cooler chilled water. The chilled liquid inlet 12 and the coolant inlet 11 can be located in the upper stage and the lower stage, respectively.

[0032] The pre-cooling system 10 further includes a nitrogen-water tower 2. The refrigerated flow L2 refrigerated by the nitrogen-water tower 2 is fed into the refrigerated liquid inlet 12 of the air-cooling tower 1.

[0033] The piping system 6 also includes a first liquid delivery pipe 66 extending from a branch point P1 of the coolant pipeline 61. The first liquid delivery pipe 66 delivers a portion L12 of the effluent L1 in the coolant pipeline 61, which has been cooled by the first heat exchanger 51, to the nitrogen water tower 2. In other words, the branch point P1 is located downstream of the first heat exchanger 51. The first portion L11 of the effluent L1, cooled by the first heat exchanger 51, flows as coolant through the coolant pipeline 61 to the coolant inlet 11 of the air-cooling tower 1. The second portion L12 of the effluent L1 flows through the first liquid delivery pipe 66 to the refrigerant inlet 12 of the air-cooling tower 1 as refrigerant.

[0034] With the above arrangement, the refrigerant also forms part of the exhaust liquid L1 discharged from the air-cooling tower 1. That is, both the refrigerant and the cooling liquid are circulated internally, resulting in a pure composition that is less likely to contaminate the feed air GA that it directly contacts and cools. In particular, in the case where the refrigerant, as mentioned in the background section, originates from a cooling water system, typically a cooling water tower 30. The cooling water provided by the cooling water tower 30 is often contaminated with impurities such as oil.

[0035] Figure 1 In the embodiment, the precooling system 10 further includes a first pump 31. The first pump 31 is disposed in the coolant line 61 downstream of the first heat exchanger 51. Furthermore, a branch point P1 is located between the first pump 31 and the first heat exchanger 51. This reduces the head pressure, thereby saving energy and costs.

[0036] Continue to see Figure 1The pre-cooling system 10 also includes a second pump 32. The second pump 32 is disposed on an output pipeline 67 connected between the nitrogen water tower 2 and the refrigerant inlet 12 of the air-cooling tower 1, thereby delivering the chilled liquid L2 chilled by the nitrogen water tower 2 to the refrigerant inlet 12. The first pump 31 and the second pump 32 are similar to the cooling water pump and chilled water pump mentioned above, respectively pumping coolant and refrigerant. These first pumps 31 and 32 pump the effluent L1 discharged from the bottom of the air-cooling tower 1 back to a higher position in the air-cooling tower 1, and therefore can also be referred to as circulating pumps.

[0037] Figure 2 In the precooling system 10a of the second embodiment shown, Figure 1 Similarly, pre-cooling system 10a also includes a nitrogen water tower 2. Air-cooling tower 1 also has a refrigerant inlet 12. Refrigerant inlet 12 receives a lower temperature liquid than coolant inlet 11. It should be understood that the drawings herein are for illustrative purposes only and are not necessarily drawn to scale. These drawings should not be construed as limiting the scope of protection claimed by the present invention.

[0038] Figure 2 In the embodiment, the pipeline system 6a further includes an output pipeline 62. The pipeline system 6a further includes a second liquid delivery pipe 68 extending from a branch position P2 of the coolant pipeline 61.

[0039] The pre-cooling system 10a also includes a second heat exchanger 52. An output pipeline 62 is used to deliver the chilled stream L2, chilled by the nitrogen-water tower 2, to the second heat exchanger 52. A second liquid delivery pipe 68 is used to deliver a portion L12 of the discharge liquid L1 in the cooling liquid pipeline 61, which has been cooled by the first heat exchanger 51, to the chilled liquid inlet 12 via the second heat exchanger 52. The output pipeline 62 and the second liquid delivery pipe 68 are configured to exchange heat with each other in the second heat exchanger 52, thereby further cooling the portion L12 of the discharge liquid L1 cooled by the first heat exchanger 51. In other words, the portion L12 of the discharge liquid L1 cooled by the second heat exchanger 52 enters the air-cooling tower 1 as chilled liquid.

[0040] The terms "first" and "second" in the text are used for descriptive purposes only and do not refer to the limitation of time sequence, quantity, or importance. They cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features, but are only for distinguishing one technical feature from another technical feature in the present technical solution. Therefore, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present utility model, the meaning of "multiple" is two or more than two (that is, more than two), unless otherwise clearly specified. Similarly, the qualifiers similar to "one" appearing in the text do not refer to the limitation of quantity, but describe technical features that have not appeared in the previous text. Similarly, unless it is a noun modified by a specific quantitative quantifier, the text should be regarded as including both singular and plural forms, and the technical solution can include both singular and plural technical features. Similarly, modifiers similar to "about" and "approximately" that appear before the numerals in the text usually include the number itself, and their specific meaning should be understood in conjunction with the context.

[0041] The precooling system 10a is equipped with a second heat exchanger 52. The first heat exchanger 51 is used for heat exchange between the cooling water L0 and the effluent L1, while the second heat exchanger 52 is used for heat exchange between the chilled flow L2 and the second portion L12 of the effluent L1. The first pump 31a, described later, is primarily required only to overcome pressure losses in the circuit and the head pressure of the air-cooling tower 1, while the second pump 32a is primarily required only to overcome the head pressure of the nitrogen-water tower 2 and the pressure losses in the circuit, specifically compensating for the pressure loss of the second heat exchanger 52. This results in lower operating costs for both pumps.

[0042] Figure 2 In the example, output pipeline 62 passes through the second heat exchanger 52 and then flows to the water inlet 21 of nitrogen water tower 2. That is, the chilled stream L2 output from nitrogen water tower 2 flows back into nitrogen water tower 2, forming a closed loop. If output pipeline 62 were to flow through the second heat exchanger 52 and then flow to another location, such as cooling water tower 30, and the inlet stream to nitrogen water tower 2 were provided by a cooling water system, such as cooling water tower 30, a pipeline would be required to deliver the heat-exchanged chilled stream L2 from the second heat exchanger 52 to the cooling water tower 30. Furthermore, a pipeline would be required to deliver cooling water from the cooling water tower 30 to the nitrogen water tower 2. This would increase pressure loss and head loss, and increase the energy consumption of the pumping system.

[0043] Figure 2 In the embodiment, precooling system 10a further includes a first pump 31a. First pump 31a is positioned upstream of first heat exchanger 51 in coolant line 61. Specifically, first pump 31a pumps discharge liquid L1 from the bottom of air-cooling tower 1 to first heat exchanger 51. This arrangement optimizes pipeline layout and further reduces energy consumption.

[0044] Figure 2 In the embodiment, pre-cooling system 10a further includes a second pump 32a. Second pump 32a is positioned upstream of second heat exchanger 52 in output pipeline 62. Specifically, second pump 32a pumps refrigerated flow L2 output from the bottom of nitrogen-water tower 2 to second heat exchanger 52. This arrangement optimizes pipeline layout and further reduces energy consumption.

[0045] Overall, the precooling systems 10 and 10a can reduce the requirements for the pumps installed in the pipeline, especially the requirements for their boosting capacity, and are particularly suitable for high-pressure precooling systems. For example, the pressure of the feed air GA required to be processed by the precooling system is above 5 bara or 6 bara.

[0046] It is worth mentioning that compared with the pre-cooling system 10a, Figure 1 The pre-cooling system 10 has a simpler structure and lower investment cost (CAPEX).

[0047] by Figure 1 For example, Figure 1 A portion of an air separation plant 100 is also shown. Air separation plant 100 includes a precooling system 10, a cooling tower 30, and a feed line 20 for supplying air GA. A water inlet pipe 60 of precooling system 10 introduces cooling water L0 from cooling tower 30. Air GA from feed line 20 is cooled in air cooling tower 1 of precooling system 10 by sequentially exchanging heat with the coolant and refrigerant in precooling system 10. Figure 1 In this example, the cooling liquid is the first portion L11 of the effluent L1 discharged from the bottom of air-cooling tower 1, and the refrigerated liquid is the refrigerated flow L2 output from the bottom of nitrogen-water tower 2. Furthermore, the refrigerated flow of nitrogen-water tower 2 is essentially the second portion L12 of the effluent L1, which is further cooled by heat exchange with waste nitrogen in nitrogen-water tower 2. Figure 2 In the embodiment, the cooling liquid is the first part L11 of the discharge liquid L1 discharged from the bottom of the air cooling tower 1 , and the refrigerated liquid is the second part L12 of the discharge liquid L1 further cooled in the second heat exchanger 52 .

[0048] The above-mentioned air separation equipment 100 can reduce energy consumption and cost, and is particularly suitable for the case where the feed air to be processed by the pre-cooling system is high pressure.

[0049] Unless clearly indicated to the contrary, each aspect or embodiment defined herein may be combined with any other aspect or embodiments. In particular, any feature indicated as preferred or advantageous may be combined with any other feature indicated as preferred or advantageous.

[0050] The present invention is described in this specification as a preferred embodiment of the present invention. The above embodiments are intended only to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning, or limited experimentation based on the concept of the present invention should be within the scope of the present invention.

Claims

1. A precooling system, comprising an air cooling tower and a piping system, wherein the piping system comprises a water inlet pipe for introducing cooling water from the outside, characterized in that: The precooling system further includes a first heat exchanger, and the pipeline system further includes a coolant pipeline, which delivers the discharge liquid discharged from the bottom of the air cooling tower to the coolant inlet of the air cooling tower. The coolant pipeline and the water inlet pipe are configured to exchange heat with each other in the first heat exchanger, so that the discharge liquid in the coolant pipeline is cooled.

2. The precooling system according to claim 1, characterized in that: The air cooling tower also has a refrigerant inlet, and the temperature of the liquid received by the refrigerant inlet is lower than that of the cooling liquid inlet; The precooling system further comprises a nitrogen water tower, and the refrigerated fluid refrigerated by the nitrogen water tower is fed into the refrigerated liquid inlet of the air cooling tower; The pipeline system also includes a first liquid infusion pipe extending from a branch position of the coolant pipeline, and the first liquid infusion pipe delivers a portion of the discharge liquid in the coolant pipeline that has been cooled by the first heat exchanger into the nitrogen water tower.

3. The precooling system according to claim 2, characterized in that: The precooling system further includes a first pump, which is disposed in the coolant pipeline at a position downstream of the first heat exchanger.

4. The precooling system according to claim 3, characterized in that: The branch position is located between the first pump and the first heat exchanger.

5. The precooling system according to claim 2, characterized in that: The precooling system further includes a second pump, which is disposed on an output pipeline connected between the nitrogen water tower and the refrigerant liquid inlet of the air cooling tower, so as to deliver the refrigerant fluid frozen by the nitrogen water tower to the refrigerant liquid inlet.

6. The precooling system according to claim 1, characterized in that: The precooling system also includes a nitrogen water tower and a second heat exchanger. The air cooling tower also has a refrigerant inlet, and the temperature of the liquid received by the refrigerant inlet is lower than that of the cooling liquid inlet; The pipeline system further includes an output pipeline, and the pipeline system further includes a second liquid infusion pipe extending from a branch position of the coolant pipeline; The output pipeline is used to deliver the refrigerated flow frozen by the nitrogen water tower into the second heat exchanger, and the second liquid infusion pipe is used to deliver a portion of the discharge liquid cooled by the first heat exchanger in the cooling liquid pipeline into the refrigerated liquid inlet through the second heat exchanger. The output pipeline and the second liquid infusion pipe are configured to exchange heat with each other in the second heat exchanger, so that the portion of the discharge liquid cooled by the first heat exchanger is further cooled.

7. The precooling system according to claim 6, characterized in that: The output pipeline passes through the second heat exchanger and leads to the water inlet of the nitrogen water tower.

8. The precooling system according to claim 6, characterized in that: The precooling system further includes a first pump, which is disposed in the coolant pipeline at a position upstream of the first heat exchanger.

9. The precooling system according to claim 8, characterized in that: The precooling system further includes a second pump disposed in the output pipeline at a position upstream of the second heat exchanger.

10. An air separation plant, characterized in that: The precooling system comprises the precooling system as claimed in any one of claims 1 to 9, further comprising a cooling water tower and a feed pipeline for supplying air, wherein the water inlet pipe of the precooling system introduces cooling water from the cooling water tower, and the air in the feed pipeline is cooled in the air cooling tower of the precooling system after contacting with the coolant and the refrigerant in the precooling system in turn for heat exchange.

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