Hybrid cooling system and refrigerant circulation system
By adopting a hybrid cooling system in liquefied natural gas (LNG) plants, which combines air cooling followed by water cooling with an ambient temperature detection and control system, the problem of unstable refrigerant cooling effect has been solved, achieving refrigerant temperature stability and reducing energy consumption, thereby increasing LNG production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI CIMC TZ CLEAN ENERGY CO LTD
- Filing Date
- 2025-08-01
- Publication Date
- 2026-06-02
AI Technical Summary
In existing liquefied natural gas plants, the use of air-cooled or water-cooled refrigerant cooling methods has problems such as high environmental dependence, unstable cooling effect, high equipment cost and complex maintenance.
A hybrid cooling system is adopted, which first cools the refrigerant with air cooling and then cools it with water. The refrigerant temperature is regulated by an ambient temperature detection and control system.
This achieved stability in refrigerant temperature and reduced energy consumption, decreased equipment and maintenance costs, and increased liquefied natural gas production.
Smart Images
Figure CN224316533U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of refrigeration technology, and in particular to a mixed cooling system and a refrigerant circulation system applicable to refrigerants in liquefied natural gas plants. Background Technology
[0002] Currently, the liquefied natural gas (LNG) industry typically uses either air cooling or water cooling alone to cool the refrigerant. For example, in water-scarce areas of Northwest China, air cooling is often used to cool the compressed refrigerant, while in coastal areas with abundant water, water cooling is more common. However, air cooling alone is highly susceptible to environmental influences, increasing the heat exchange load on the cold box, especially during the daytime in summer when ambient temperatures are high and air cooling is ineffective. Furthermore, when the LNG plant is located in an area with large diurnal temperature variations, the control of the entire refrigeration system becomes more complex. Water cooling of the compressed refrigerant requires a high volume of circulating water, placing stringent demands on water source and quality, and incurring significant equipment and maintenance costs. Utility Model Content
[0003] The purpose of this invention is to provide a mixed cooling system and refrigerant circulation system applicable to refrigerants in liquefied natural gas plants. It employs a mixed cooling method of first air cooling and then water cooling, allowing the refrigerant to exchange heat with the coolant in the water cooling unit after air cooling. This effectively lowers the refrigerant temperature before it enters the cold box for throttling and cooling. This not only maintains a stable refrigerant temperature entering the cold box and reduces the required cooling capacity and energy consumption of the cold box, but also reduces the amount of coolant used in the water cooling unit, thereby reducing investment and maintenance costs and solving the aforementioned problems in the prior art.
[0004] To achieve the above objectives, this utility model provides the following solution:
[0005] This invention provides a hybrid cooling system, including an air-cooling device, a water-cooling device, and a control system. The air-cooling device is connected to a refrigeration source to perform primary cooling of the refrigerant discharged from the refrigeration source. The inlet of the water-cooling device is connected to the air-cooling device, and the outlet of the water-cooling device is connected to a cold box. The water-cooling device can perform secondary cooling of the refrigerant after primary cooling and discharge the secondary-cooled refrigerant into the cold box. The control system is communicatively connected to both the air-cooling device and the water-cooling device to adjust the temperature of the refrigerant formed after primary cooling and secondary cooling according to the ambient temperature.
[0006] In some embodiments, the air-cooling device includes an air-cooling frame, a first refrigerant pipeline, and a plurality of first fans. The first refrigerant pipeline is disposed inside the air-cooling frame, with its inlet connected to the cooling source and its outlet connected to the water-cooling device. The plurality of first fans are disposed on the air-cooling frame, and each first fan is used to output air-cooled airflow to the first refrigerant pipeline to perform the first-stage cooling of the refrigerant in the first refrigerant pipeline.
[0007] In some embodiments, the air-cooling device further includes a wind box, which is disposed on the air-cooling frame. The first refrigerant pipeline is disposed inside the wind box. The wind box has a first air outlet and a first air inlet. The outlet of each of the first fans is connected to the first air inlet to output the air-cooled airflow into the wind box.
[0008] In some embodiments, the water-cooling device includes a water-cooled heat exchanger and a coolant circulation device. The water-cooled heat exchanger includes a housing, a first coolant pipeline, and a second refrigerant pipeline. The first coolant pipeline is disposed within the housing. The second refrigerant pipeline is disposed within the housing and arranged adjacent to the first coolant pipeline. The inlet of the second refrigerant pipeline is connected to the outlet of the air-cooling device, and the outlet of the second refrigerant pipeline is used to connect to the cold box. The outlet and inlet of the coolant circulation device are respectively connected to the inlet and outlet of the first coolant pipeline. The coolant circulation device is used to cool the coolant and provide circulating coolant to the first coolant pipeline.
[0009] In some embodiments, the water-cooled heat exchanger is a shell-and-tube heat exchanger, the first coolant line is the shell side of the shell-and-tube heat exchanger, the second refrigerant line is the tube side of the shell-and-tube heat exchanger, the first coolant line is sleeved outside the second refrigerant line, and the inlet of the first coolant line and the outlet of the second refrigerant line are located at the same end, and the outlet of the first coolant line and the inlet of the second refrigerant line are located at the same end.
[0010] In some embodiments, the coolant circulation device includes a cooling tower and a circulation pump. The cooling tower is equipped with a cooling mechanism and a second coolant pipeline. The cooling mechanism can cool the coolant in the second coolant pipeline. The inlet of the second coolant pipeline is connected to the outlet of the first coolant pipeline, and the outlet of the second coolant pipeline is connected to the inlet of the first coolant pipeline to form a coolant circulation path. The circulation pump is disposed on the coolant circulation path to provide power for the circulation of the coolant.
[0011] In some embodiments, the cooling mechanism includes a water collection tank, a spray device, and a second fan. The water collection tank is located at the bottom of the cooling tower and below the second coolant pipeline. The spray device is connected to the water collection tank and can spray water from the water collection tank onto the outer wall of the second coolant pipeline. The second fan is located above the spray device. The top and bottom of the cooling tower are respectively provided with a second air outlet and a second air inlet. The second fan is close to the second air outlet and can draw air out of the cooling tower to form an airflow circulation within the cooling tower.
[0012] In some embodiments, a flow regulating valve is also provided on the first coolant pipeline, which can regulate the flow rate of coolant in the first coolant pipeline.
[0013] In some embodiments, the hybrid cooling system further includes an ambient temperature detection device and a refrigerant temperature detection device; the ambient temperature detection device is used to detect the ambient temperature; both the air-cooled device and the water-cooled device are equipped with the refrigerant temperature detection device, which is used to detect the temperature of the refrigerant in the air-cooled device and the water-cooled device; the control system is communicatively connected to both the ambient temperature detection device and the refrigerant temperature detection device to adjust the refrigerant temperature formed after the first-stage cooling and the second-stage cooling according to the ambient temperature.
[0014] This utility model also provides a refrigerant circulation system, including the above-mentioned mixed cooling system and a cold box, wherein the refrigerant inlet of the cold box is connected to the refrigerant outlet of the mixed cooling system.
[0015] The present invention achieves the following technical advantages over the prior art:
[0016] This invention provides a hybrid cooling system. First, an air-cooling device cools the refrigerant in one stage, followed by a water-cooling device for a second stage. Compared to water-cooling alone, this reduces the amount of circulating coolant, thus lowering equipment and maintenance costs. Compared to air-cooling alone, it further reduces the refrigerant temperature, decreasing the cooling load required before the refrigerant enters the cold box, resulting in lower energy consumption. Under the same energy consumption, liquefied natural gas (LNG) production can also be increased. A control system is also included to regulate the refrigerant temperature based on ambient temperature, ensuring a stable refrigerant temperature before entering the cold box. This reduces the impact of diurnal temperature variations on heat exchange within the cold box, facilitating temperature field control and preventing increased system energy consumption due to diurnal temperature fluctuations in the refrigerant entering the cold box.
[0017] The refrigerant circulation system provided by this utility model, by setting up the above-mentioned mixed cooling system, further reduces the temperature of the refrigerant before it enters the cold box, thereby reducing the amount of cooling required after the refrigerant enters the cold box, thus reducing the energy consumption of the refrigerant circulation system, and producing more liquefied natural gas under the same energy consumption. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 This is a schematic diagram of the overall structure of the hybrid cooling system in Embodiment 1 of this utility model;
[0020] Figure 2 This is a schematic diagram of the overall structure of the air-cooling device in Embodiment 1 of this utility model;
[0021] Figure 3 This is a schematic diagram of the overall structure of the water-cooled heat exchanger in Embodiment 1 of this utility model;
[0022] Figure 4 This is a schematic diagram of the overall structure of the coolant circulation device in Embodiment 1 of this utility model;
[0023] Figure 5 A schematic diagram of the refrigerant and circulating water circulation process in Embodiment 1 of this utility model.
[0024] In the diagram: 100-Hybrid cooling system; 1-Air-cooled device; 11-Air-cooled frame; 12-First refrigerant pipeline; 13-First fan; 14-Air box; 141-First air inlet; 142-First air outlet; 2-Water-cooled device; 21-Shell-tube heat exchanger; 211-Casing; 212-First coolant pipeline; 213-Second refrigerant pipeline; 22-Coolant circulation device; 221-Cooling tower; 222-Second coolant pipeline; 223-Water collection tank; 224-Spray device; 225-Second fan; 226-Second air inlet; 227-Second air outlet; 23-Flow regulating valve; 24-Refrigerant temperature detection device; 25-Circulating water temperature detection device. Detailed Implementation
[0025] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0026] The purpose of this invention is to provide a mixed cooling system and refrigerant circulation system applicable to refrigerants in liquefied natural gas plants. It adopts a mixed cooling method of first air cooling and then water cooling, so that the refrigerant can further exchange heat with the circulating water after air cooling, so that the temperature of the refrigerant can be effectively reduced before entering the cold box for throttling and cooling. This not only reduces the cooling capacity and energy consumption required by the cold box, but also reduces the circulating water volume of the system, thereby reducing investment and maintenance costs and solving the above-mentioned problems in the prior art.
[0027] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, the following description is provided in conjunction with the appendix. Figures 1-5 The present invention will be further described in detail below with reference to specific embodiments.
[0028] Example 1
[0029] This embodiment provides a hybrid cooling system 100, see reference. Figure 1 and Figure 5The system includes an air-cooled unit 1, a water-cooled unit 2, and a control system. The air-cooled unit 1 is connected to a refrigeration source to perform primary cooling of the refrigerant discharged from the refrigeration source. The inlet of the water-cooled unit 2 is connected to the air-cooled unit 1, and the outlet of the water-cooled unit 2 is connected to a cold box. The water-cooled unit 2 can perform secondary cooling of the refrigerant after primary cooling and discharge the secondary-cooled refrigerant into the cold box. The control system is communicatively connected to both the air-cooled unit 1 and the water-cooled unit 2 to adjust the temperature of the refrigerant after primary and secondary cooling according to the ambient temperature. The hybrid cooling system 100 provided in this embodiment first performs primary cooling of the refrigerant through the air-cooled unit 1, and then performs secondary cooling of the refrigerant through the water-cooled unit 2. Compared with the case of using only water cooling, it can reduce the amount of coolant used in the water-cooled unit while reducing equipment and maintenance costs. Compared with the case of using only air cooling, it can further reduce the refrigerant temperature, which can reduce the amount of cooling required after the refrigerant enters the cold box, thereby reducing energy consumption. Under the same energy consumption, the production of liquefied natural gas can also be increased. A control system is also installed to regulate the refrigerant temperature based on the ambient temperature, ensuring a stable refrigerant temperature before it enters the cold box. This reduces the impact of diurnal temperature variations on heat exchange within the cold box and prevents increased system energy consumption due to diurnal temperature changes in the refrigerant temperature entering the cold box. In this embodiment, the refrigeration source includes a refrigerant supply device (not shown in the figure) and a compressor, which compresses the refrigerant before discharging it.
[0030] In some implementations, reference Figure 2The air-cooling device 1 includes an air-cooling frame 11, a first refrigerant pipeline 12, and several first fans 13. The first refrigerant pipeline 12 is disposed inside the air-cooling frame 11. The inlet of the first refrigerant pipeline 12 is connected to a cooling source, and the outlet of the first refrigerant pipeline 12 is connected to a water-cooling device 2. Several first fans 13 are disposed on the air-cooling frame 11, and each first fan 13 is used to output air-cooled airflow to the first refrigerant pipeline 12 to perform primary cooling of the refrigerant in the first refrigerant pipeline 12. Through the first refrigerant pipeline 12 disposed inside the air-cooling frame 11, and through the several first fans 13, heat exchange is performed on the air-cooled airflow output from the first refrigerant pipeline 12. The structure is simple and easy to implement. In some other embodiments, a uniform air duct can be disposed near the outlet of the first fan 13, so that the first fans 13 are evenly arranged along the uniform air duct to achieve uniform cooling of the first refrigerant pipeline 12. In this embodiment, the first refrigerant pipeline 12 has multiple branches within the air-cooled frame 11 to expand the heat exchange area of the refrigerant, achieving uniform heat exchange and rapid cooling. In this example, several first fans 13 can be started and stopped individually. The control system can control the number of first fans 13 in operation based on the ambient temperature. During hot days, the number of first fans 13 in operation can be increased, and during cold nights, the number of first fans 13 in operation can be decreased to save system energy.
[0031] In some implementations, reference Figure 2 The air-cooling device 1 also includes a wind box 14, which is mounted on the air-cooling frame 11. A first refrigerant pipeline 12 is located inside the wind box 14. The wind box 14 has a first air outlet 142 and a first air inlet 141. The outlets of each first fan 13 are connected to the first air inlet 141 to output air-cooled airflow into the wind box 14. By setting up the wind box 14, which has a first air outlet 142 and a first air inlet 141, and the outlets of each first fan 13 are connected to the first air inlet 141, ambient air enters the wind box 14 from the first air inlet 141 driven by the first fan 13. After exchanging heat with the first refrigerant pipeline 12, it is discharged from the first air outlet 142, thus realizing heat exchange for the refrigerant. In this embodiment, the first air outlet 142 is also provided with louvers, which can reduce dust accumulation and avoid affecting the heat exchange effect, while also guiding the airflow direction, reducing the wind resistance of the air-cooled airflow, and improving the heat dissipation effect of the first fan 13.
[0032] In some implementations, reference Figures 1-4The water-cooling device 2 includes a water-cooled heat exchanger 21 and a coolant circulation device 22. The water-cooled heat exchanger includes a housing 211, a first coolant pipeline 212, and a second refrigerant pipeline 213. The first coolant pipeline 212 is disposed inside the housing 211. The second refrigerant pipeline 213 is disposed inside the housing 211 and is arranged adjacent to the first coolant pipeline 212. The inlet of the second refrigerant pipeline 213 is connected to the outlet of the air-cooling device 1, and the outlet of the second refrigerant pipeline 213 is used to connect to the cold box. The outlet and inlet of the coolant circulation device 22 are respectively connected to the inlet and outlet of the first coolant pipeline 212. The coolant circulation device 22 is used to cool the coolant and provide circulating coolant to the first coolant pipeline 212. By setting up a first coolant pipeline 212 and a second refrigerant pipeline 213, heat exchange occurs between them, and both the refrigerant and coolant flow within their respective pipelines, avoiding mutual contamination. In this embodiment, the coolant is circulating water. By setting up a coolant circulation device 22, the circulating water in the first coolant pipeline 212 can be cooled, achieving the recycling of the circulating water. After the air-cooling device 1 performs primary cooling of the refrigerant, the circulating water performs secondary cooling. Compared to cooling the refrigerant solely through water cooling, in this embodiment, the circulating water only needs to remove a portion of the refrigerant's heat, requiring less circulating water, thus reducing the amount of circulating water in the system. Compared to cooling the refrigerant solely through air cooling, this further reduces the refrigerant temperature before entering the cold box, reducing the cooling required after the refrigerant enters the cold box, achieving energy reduction. Under the same energy consumption, the production of liquefied natural gas can also be increased.
[0033] In some implementations, reference Figure 3The water-cooled heat exchanger is a shell-and-tube heat exchanger 21. The first coolant line 212 is the shell side of the shell-and-tube heat exchanger 21, and the second refrigerant line 213 is the tube side of the shell-and-tube heat exchanger 21. The first coolant line 212 is sleeved outside the second refrigerant line 213, and the inlet of the first coolant line 212 and the outlet of the second refrigerant line 213 are located at the same end. The outlet of the first coolant line 212 and the inlet of the second refrigerant line 213 are located at the same end. In this embodiment, the water-cooled heat exchanger is a shell-and-tube heat exchanger 21. Specifically, the shell-and-tube heat exchanger 21 used in this embodiment is the BEM1100 model shell-and-tube heat exchanger produced by Liaoning CIMC Harbin Cryogenic Gas Liquefaction Equipment Co., Ltd. The front tube box adopts a headed tube box, the casing 211 adopts a single-inlet single-outlet condenser shell, and the rear end adopts a fixed tube sheet structure similar to the front tube box, which can adapt to higher pressure and temperature, and has high heat exchange efficiency. The circulating water flows through the shell side, that is, the first coolant pipeline 212, with an operating pressure of 0.45MPa and an inlet / outlet design temperature of 32 / 40℃. The refrigerant flows through the tube side, that is, the second refrigerant pipeline 213, with an operating pressure of 3.8MPa and an inlet / outlet design temperature of 50 / 40℃. Furthermore, by setting the inlet of the first coolant line 212 and the outlet of the second refrigerant line 213 at the same end, and setting the outlet of the first coolant line 212 and the inlet of the second refrigerant line 213 at the same end, convection between the circulating water and the refrigerant can be achieved, so that the temperature of the refrigerant at the outlet of the second refrigerant line 213 is closer to the temperature of the circulating water, thereby further reducing the temperature of the refrigerant and reducing the amount of cooling required after the refrigerant enters the cold box.
[0034] In some implementations, reference Figure 4The coolant circulation device 22 includes a cooling tower 221 and a circulation pump. The cooling tower 221 contains a cooling mechanism and a second coolant pipeline 222. The cooling mechanism cools the coolant in the second coolant pipeline 222. The inlet of the second coolant pipeline 222 is connected to the outlet of the first coolant pipeline 212, and the outlet of the second coolant pipeline 222 is connected to the inlet of the first coolant pipeline 212, forming a coolant circulation path. The circulation pump is located on the coolant circulation path to provide power for the circulation of the coolant. By setting up the cooling tower 221 and the second coolant pipeline 222 within the cooling tower 221, and the cooling mechanism to cool the circulating water, and by setting up the circulation pump on the coolant circulation path to drive the flow of the circulating water, the circulation of the circulating water is achieved. In this embodiment, the circulation pump is a centrifugal pump located downstream of the cooling tower 221. In other embodiments, the circulation pump may also be located upstream of the cooling tower 221. Cooling tower 221 is a prior art technology. In this embodiment, a ZHBY-1607 crossflow closed-loop cooling tower manufactured by Xi'an Zhonghang Boyi Process Technology Co., Ltd. is used. The specific structure and working principle will not be described in detail here. In some other embodiments, the cooling tower can be replaced with other devices capable of cooling circulating water.
[0035] In some implementations, reference Figure 4The cooling mechanism includes a water collection tank 223, a spray device 224, and a second fan 225. The water collection tank 223 is located at the bottom of the cooling tower 221 and below the second coolant pipeline 222. The spray device 224 is connected to the water collection tank 223 and can spray the water in the water collection tank 223 onto the outer wall of the second coolant pipeline 222. The second fan 225 is located above the spray device 224. The top and bottom of the cooling tower 221 are respectively provided with a second air outlet 227 and a second air inlet 226. The second fan 225 is close to the second air outlet 227 and can draw out the air in the cooling tower 221 to form an airflow circulation in the cooling tower 221. By installing a spray device 224, water can be sprayed onto the outer wall of the second coolant pipe 222, forming a uniform water film on the outer wall. Through heat exchange and evaporation of this water film, the heat of the circulating water in the second coolant pipe 222 can be rapidly removed, lowering the temperature of the circulating water to a wet-bulb temperature 5-10°C below the ambient temperature. Furthermore, by installing a second fan 225 inside the cooling tower 221, the fan can draw air from the cooling tower 221 to remove heat, while simultaneously accelerating the evaporation of the water film on the outer wall of the second coolant pipe 222, thereby accelerating the reduction of the circulating water temperature. In this embodiment, the spraying device 224 includes a spraying pipeline, a water pump, and nozzles. The inlet of the spraying pipeline is connected to the water collection tank 223, and the outlet of the spraying pipeline is connected to the nozzles. The water pump is located in the middle section of the spraying pipeline, and the nozzles are evenly distributed above the second coolant pipeline 222 to spray water onto the second coolant pipeline 222 to form a water film.
[0036] In some implementations, reference Figure 1 A flow regulating valve 23 is also provided on the first coolant line 212, which can regulate the flow rate of coolant in the first coolant line 212. By providing a flow regulating valve 23 on the first coolant line 212, the flow rate entering the first coolant line 212 can be regulated, so as to control the circulating water flow rate of the first coolant line 212 according to the ambient temperature and reduce the total energy consumption of the system. In this embodiment, the flow regulating valve 23 and the circulating pump are separately arranged. In some other embodiments, the flow regulating valve 23 and the circulating pump are integrated, specifically, it can be set as a variable frequency centrifugal pump or other water pump capable of flow regulation.
[0037] In some implementations, reference Figure 1The hybrid cooling system 100 also includes an ambient temperature detection device and a refrigerant temperature detection device 24. The ambient temperature detection device is used to detect the ambient temperature. Both the air-cooled unit 1 and the water-cooled unit 2 are equipped with refrigerant temperature detection devices 24, which are used to detect the temperature of the refrigerant within the air-cooled unit 1 and the water-cooled unit 2. The control system is communicatively connected to both the ambient temperature detection device and the refrigerant temperature detection device 24 to adjust the refrigerant temperature formed after the first-stage cooling and the second-stage cooling according to the ambient temperature. By setting up a control system, the control system is communicatively connected to the ambient temperature detection device and the refrigerant temperature detection device 24 to adjust the refrigerant temperature after the first-stage cooling and the second-stage cooling. In this embodiment, the inlet of the first refrigerant pipeline 12, the outlet of the first refrigerant pipeline 12, and the outlet of the second refrigerant pipeline 213 are all equipped with refrigerant temperature detection devices 24. The inlet of the first coolant pipeline 212 and the inlet of the second coolant pipeline 222 are all equipped with circulating water temperature detection devices 25, which are also communicatively connected to the control system. Furthermore, the control system can automatically adjust the number of first fans 13 in the air-cooled unit 1 and their power, the flow rate of circulating water in the water-cooled unit 2, the power of the second fan 225, and the water spray volume of the spray system 224 according to the ambient temperature, thus achieving automatic system adjustment. For example, during the hot daytime, all first fans 13 are turned on, and the opening of the flow regulating valve 23 is increased. At the same time, the power of the second fan 225 and the water spray volume of the spray system are increased to ensure that the refrigerant temperature is close to the wet-bulb temperature after passing through the air-cooled unit 1 and the water-cooled unit 2. During the cold nighttime, some first fans 13 are turned off, and the opening of the flow regulating valve 23 is decreased to reduce the power of the second fan 225 and the water spray volume of the spray system 224, so that the refrigerant temperature can approach the wet-bulb temperature while reducing the system's energy consumption.
[0038] The compressor compresses the refrigerant and discharges it. The air-cooling unit performs a first-stage cooling of the refrigerant to obtain a refrigerant at a temperature of 35-45°C. The water-cooling unit performs a second-stage cooling of the refrigerant obtained after the first-stage cooling, further reducing the temperature by 5-10°C. At this point, the temperature is close to the wet-bulb temperature. Then, the refrigerant close to the wet-bulb temperature is introduced into the cold box.
[0039] Therefore, the hybrid cooling system 100 proposed in this invention can cool the refrigerant to 30-35°C before it enters the cold box. Compared to water cooling alone, this reduces the amount of circulating water used in the water cooling device, thus lowering equipment and maintenance costs. Compared to air cooling alone, the refrigerant temperature is 5-10°C lower, reducing the cooling load required after the refrigerant enters the cold box, resulting in lower energy consumption. Under the same energy consumption, liquefied natural gas production can also be increased. Simultaneously, a control system is installed to regulate the refrigerant temperature based on the ambient temperature, ensuring a stable refrigerant temperature before it enters the cold box. This reduces the impact of diurnal temperature variations on heat exchange in the cold box and avoids increased system energy consumption caused by diurnal temperature changes in the refrigerant temperature entering the cold box.
[0040] Example 2
[0041] This embodiment provides a refrigerant circulation system applicable to liquefied natural gas (LNG) plants, including the aforementioned mixed cooling system 100 and a cold box. The refrigerant inlet of the cold box is connected to the refrigerant outlet of the mixed cooling system 100. The refrigerant outlet of the mixed cooling system 100 can, for example, be the outlet of the second refrigerant pipeline in the above embodiment. The refrigerant circulation system provided in this embodiment, by incorporating the mixed cooling system 100, further reduces the refrigerant temperature, thereby reducing the cooling load required for the refrigerant to cool down after entering the cold box. This reduces the energy consumption of the refrigerant circulation system and allows for the production of more LNG with the same energy consumption.
[0042] The specific implementation results of this embodiment are as follows:
[0043] After the refrigerant is cooled by the mixing and cooling system, its temperature stabilizes at approximately 5°C higher than the local wet-bulb temperature. Calculations show that for every 5°C decrease in the refrigerant's inlet temperature, the energy consumed to produce one ton of LNG decreases by about 20.8 kWh. Based on a daily production of 330 tons of LNG, each 5°C decrease in refrigerant temperature saves 6864 kWh of energy per day, which translates to approximately 4118 yuan per day at a local electricity price of 0.6 yuan / kWh. With sufficient feedstock gas, this 6864 kWh of energy savings can increase LNG production by approximately 3%.
[0044] This utility model uses specific examples to illustrate its principles and implementation methods. The above description of the embodiments is only for the purpose of helping to understand the method and core idea of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the idea of this utility model. In summary, the content of this specification should not be construed as a limitation of this utility model.
Claims
1. A hybrid cooling system, characterized in that: include: An air-cooling device is used to connect to a refrigeration source to perform primary cooling of the refrigerant discharged by the refrigeration source. A water-cooling device, the inlet of which is connected to the air-cooling device, and the outlet of which is connected to a cold box, wherein the water-cooling device is capable of performing secondary cooling on the refrigerant after primary cooling and discharging the refrigerant after secondary cooling into the cold box. as well as The control system is communicatively connected to both the air-cooling device and the water-cooling device, enabling it to adjust the refrigerant temperature formed after the primary cooling and the secondary cooling according to the ambient temperature.
2. The hybrid cooling system according to claim 1, characterized in that: The air-cooling device includes: Air cooling frame; A first refrigerant pipeline is disposed inside the air-cooled frame. The inlet of the first refrigerant pipeline is connected to the cooling source, and the outlet of the first refrigerant pipeline is connected to the water-cooling device. A plurality of first fans are mounted on the air-cooled frame, and each first fan is used to output air-cooled airflow to the first refrigerant pipeline to perform the first-stage cooling of the refrigerant in the first refrigerant pipeline.
3. The hybrid cooling system according to claim 2, characterized in that: The air-cooling device also includes: The air box is mounted on the air-cooled frame, and the first refrigerant pipeline is located inside the air box. The air box has a first air outlet and a first air inlet, and the outlet of each of the first fans is connected to the first air inlet to output the air-cooled airflow into the air box.
4. The hybrid cooling system according to any one of claims 1 to 3, characterized in that: The water cooling device includes: A water-cooled heat exchanger includes a casing, a first coolant pipeline, and a second refrigerant pipeline. The first coolant pipeline is disposed within the casing. The second refrigerant pipeline is disposed within the casing and arranged adjacent to the first coolant pipeline. The inlet of the second refrigerant pipeline is connected to the outlet of the air-cooled device, and the outlet of the second refrigerant pipeline is used to connect to the cold box. The coolant circulation device has its outlet and inlet connected to the inlet and outlet of the first coolant pipeline, respectively. The coolant circulation device is used to cool the coolant and provide circulating coolant to the first coolant pipeline.
5. The hybrid cooling system according to claim 4, characterized in that: The water-cooled heat exchanger is a shell-and-tube heat exchanger. The first coolant pipeline is the shell side of the shell-and-tube heat exchanger, and the second refrigerant pipeline is the tube side of the shell-and-tube heat exchanger. The first coolant pipeline is sleeved outside the second refrigerant pipeline, and the inlet of the first coolant pipeline and the outlet of the second refrigerant pipeline are located at the same end. The outlet of the first coolant pipeline and the inlet of the second refrigerant pipeline are located at the same end.
6. The hybrid cooling system according to claim 4, characterized in that: The coolant circulation device includes: A cooling tower, wherein a cooling mechanism and a second coolant pipeline are provided inside the cooling tower; the cooling mechanism is capable of cooling the coolant in the second coolant pipeline; the inlet of the second coolant pipeline is connected to the outlet of the first coolant pipeline, and the outlet of the second coolant pipeline is connected to the inlet of the first coolant pipeline, thereby forming a coolant circulation path; and A circulation pump is installed in the coolant circulation path to provide power for the circulation of the coolant.
7. The hybrid cooling system according to claim 6, characterized in that: The cooling mechanism includes: A water collection tank is located at the bottom of the cooling tower and below the second coolant pipeline; A spraying device, connected to the water collection tank, is capable of spraying water from the water collection tank onto the outer wall of the second coolant pipeline; and The second fan is located above the spray device. The top and bottom of the cooling tower are respectively provided with a second air outlet and a second air inlet. The second fan is close to the second air outlet and can draw air out of the cooling tower to form an airflow circulation in the cooling tower.
8. The hybrid cooling system according to claim 4, characterized in that: The first coolant pipeline is also equipped with a flow regulating valve, which can regulate the flow rate of coolant passing through the first coolant pipeline.
9. The hybrid cooling system according to any one of claims 1 to 3, characterized in that: It also includes an ambient temperature detection device and a refrigerant temperature detection device; the ambient temperature detection device is used to detect the ambient temperature; both the air-cooling device and the water-cooling device are equipped with the refrigerant temperature detection device, which is used to detect the temperature of the refrigerant in the air-cooling device and the water-cooling device; The control system is communicatively connected to both the ambient temperature detection device and the refrigerant temperature detection device to adjust the refrigerant temperature formed after the first-stage cooling and the second-stage cooling according to the ambient temperature.
10. A refrigerant circulation system, characterized in that: include: The cold box and the hybrid cooling system according to any one of claims 1 to 9; The refrigerant inlet of the cold box is connected to the refrigerant outlet of the mixed cooling system.