WO2024104237A1 - 一种用于流体的具有可变工况调节功能的冷却系统 - Google Patents
一种用于流体的具有可变工况调节功能的冷却系统 Download PDFInfo
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- WO2024104237A1 WO2024104237A1 PCT/CN2023/130571 CN2023130571W WO2024104237A1 WO 2024104237 A1 WO2024104237 A1 WO 2024104237A1 CN 2023130571 W CN2023130571 W CN 2023130571W WO 2024104237 A1 WO2024104237 A1 WO 2024104237A1
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- WIPO (PCT)
- Prior art keywords
- refrigerant
- expander
- cooling system
- sensor device
- motor
- Prior art date
Links
- 238000001816 cooling Methods 0.000 title claims abstract description 136
- 239000012530 fluid Substances 0.000 title claims abstract description 72
- 239000003507 refrigerant Substances 0.000 claims description 109
- 239000003949 liquefied natural gas Substances 0.000 claims description 24
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 12
- 230000001105 regulatory effect Effects 0.000 claims description 9
- 238000011084 recovery Methods 0.000 claims description 8
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 6
- 239000001569 carbon dioxide Substances 0.000 claims description 6
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 6
- 239000001307 helium Substances 0.000 claims description 6
- 229910052734 helium Inorganic materials 0.000 claims description 6
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 claims description 6
- 239000001257 hydrogen Substances 0.000 claims description 6
- 229910052739 hydrogen Inorganic materials 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 239000002826 coolant Substances 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 4
- 238000009413 insulation Methods 0.000 claims description 4
- 230000005540 biological transmission Effects 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 238000000034 method Methods 0.000 description 15
- 239000007789 gas Substances 0.000 description 13
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 13
- 230000000694 effects Effects 0.000 description 6
- 239000003345 natural gas Substances 0.000 description 6
- 101100012902 Saccharomyces cerevisiae (strain ATCC 204508 / S288c) FIG2 gene Proteins 0.000 description 5
- 238000012544 monitoring process Methods 0.000 description 5
- 230000001172 regenerating effect Effects 0.000 description 5
- 238000012546 transfer Methods 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000006835 compression Effects 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000004321 preservation Methods 0.000 description 2
- 238000005057 refrigeration Methods 0.000 description 2
- 239000000498 cooling water Substances 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63J—AUXILIARIES ON VESSELS
- B63J2/00—Arrangements of ventilation, heating, cooling, or air-conditioning
- B63J2/12—Heating; Cooling
- B63J2/14—Heating; Cooling of liquid-freight-carrying tanks
Definitions
- the present invention relates to the field of LNG storage and transportation, and in particular to a processing system for evaporated gas used in LNG ships, and more particularly to a cooling system for fluids with a variable operating condition adjustment function.
- any LNG ship may receive heat from the outside during transportation, thus generating boil-off gas, even if the cargo tank has good insulation performance.
- the generation of boil-off gas will increase the pressure in the cargo tank and damage the structure of the cargo tank. If the boil-off gas is discharged directly into the atmosphere, it will also cause direct economic losses and greenhouse hazards. Therefore, it is necessary to set up a cooling system for boil-off gas.
- the cooling system can re-condense and liquefy the boil-off gas in the cargo tank, reduce the possibility of evaporation of the boil-off gas in the cargo tank, reduce transportation costs and improve the safety of LNG transportation. It is an important high-value-added equipment on large LNG transport ships and bunkering ships. Such problems also exist in LNG storage facilities on land.
- the current LNG evaporated gas cooling system uses a mixed working fluid reliquefaction method, which will lead to a complicated process and difficult maintenance.
- working fluids such as propane are explosive gases, with a high risk of leakage and high danger.
- the nitrogen expansion reliquefaction method uses inert gas as a refrigerant, which is safer, but the system requires more auxiliary equipment such as evaporated gas compressors, nitrogen generators, evaporated gas heaters, etc., with a long installation and commissioning cycle and high maintenance costs.
- the present invention proposes a cooling system with variable working condition adjustment for a fluid, wherein the fluid may preferably be liquefied natural gas, and the cooling system comprises a cooling circuit, wherein the cooling circuit is used to cool the fluid, and the cooling circuit comprises:
- the compressor is used to compress the refrigerant in the cooling system, thereby increasing the pressure of the refrigerant;
- Cooler which cools the compressed refrigerant
- An expander is used to expand the cooled refrigerant
- An electric motor capable of driving a compressor to compress the refrigerant, wherein the speed of the electric motor is adjustable, in particular continuously variable;
- a heat exchanger is used to exchange heat between the cooled fluid and the expanded refrigerant
- the refrigerant operates in a closed cycle in the cooling circuit. After being compressed in the compressor, the refrigerant is cooled by the cooler and then expanded by the expander to reduce the pressure and temperature. After that, it absorbs heat from the cooled fluid in the heat exchanger to reduce the temperature of the cooled fluid. After absorbing the heat, the refrigerant enters the compressor and is compressed.
- the cooling system also includes a controller and a sensor device.
- the sensor device is configured to detect the temperature of the fluid and/or cooling medium.
- the sensor device and the motor are connected to the controller.
- the controller can receive data from the sensor device and control the speed of the motor based on the data from the sensor device.
- the sensing device can be arranged on at least one of the inlet pipe section of the expander, the pipe section between the outlet of the expander and the heat exchanger, the outlet pipe section of the cooled fluid of the heat exchanger, and the outlet pipe section of the refrigerant of the heat exchanger.
- a corresponding preset value is set in the controller.
- the controller adjusts the speed of the motor through PID control to adjust the circulation speed of the refrigerant in the cooling circuit and then adjust the cooling capacity provided by the cooling circuit until the actual value is the same as the preset value; in particular, when the actual value is greater than the preset value, the controller increases the speed of the motor, and when the actual value is less than the preset value, the controller reduces the speed of the motor.
- the temperature-related value can be the temperature value detected by a single sensor device, the rate of change of the temperature value detected by a single sensor device, the difference between the temperature values detected by multiple sensors, or the rate of change of the difference between the temperature values detected by multiple sensors.
- the flow direction of the fluid in at least part of the section of the heat exchanger is opposite to the flow direction of the expanded refrigerant; wherein the refrigerant is an inert gas, and the refrigerant is preferably He, N2, H2 or Ne, or a mixture of at least two of He, N2, H2, Ne; wherein the fluid is liquefied natural gas, carbon dioxide, hydrogen or helium, or a mixture of at least two of liquefied natural gas, carbon dioxide, hydrogen or helium.
- the cooling circuit also includes a heat recovery exchanger, in which the refrigerant flowing out of the heat exchanger exchanges heat with the refrigerant before entering the expansion machine; the heat exchanger and the heat recovery exchanger are installed in a thermal insulation device.
- the number of the compressors is at least two, and the at least two compressors are arranged in series and/or parallel in the cooling circuit, so that the refrigerant flows through the at least two compressors in series and/or parallel, wherein a cooler is arranged at the outlet of each compressor; the refrigerant expands in the expander so that the expander outputs energy, and at least one of the at least two compressors can receive the energy output by the expander; and at least one of the at least two compressors can be driven by an electric motor.
- At least one of the at least two compressors can be arranged in a coaxial transmission manner with the motor and the expander, so that the at least one compressor is driven jointly by the energy output by the motor and the expander.
- the number of the expansion machines is at least two, and the at least two expansion machines are arranged in series and/or parallel in the cooling circuit, so that the refrigerant flows through the at least two expansion machines in series and/or parallel.
- the compressor is an axial flow compressor or a centrifugal compressor
- the expander is an axial flow expander or a centrifugal expander
- the expander is provided with a bypass branch, one end of the bypass branch is connected to the inlet of the expander, and the other end of the bypass branch is connected to the outlet of the expander.
- a regulating valve is provided on the bypass branch to regulate the refrigerant flowing from the inlet of the expander to the outlet of the expander via the bypass branch; in particular, one end of the bypass branch is connected to a pipe section located upstream of the heat exchanger at the inlet of the expander, and the other end of the bypass branch is connected to a pipe section located downstream of the heat exchanger at the outlet of the expander.
- the cooling system includes a compressor driven by an electric motor, the speed of the electric motor is adjustable, and also includes a controller and a sensor device, the sensor device is configured to detect the temperature of the fluid and/or the cooling medium, the controller can receive data from the sensor device, and can control the speed of the electric motor based on the data of the sensor device, and then when the required cooling capacity of the cooled fluid and/or the cooling capacity provided by the refrigerant changes, by adjusting the speed of the electric motor, it can ensure that the temperature of the cooled fluid is maintained at a predetermined value; in particular, the control is carried out by PID adjustment, which has the advantages of simple control, safety and reliability, and rapid adjustment, and can enable the cooling system of the present invention to adjust the cooling capacity accordingly with the change of the operating condition, and realize variable operating condition adjustment with a cooling capacity range of 0-100%.
- PID adjustment which has the advantages of simple control, safety and reliability, and rapid adjustment, and can enable the cooling system of the present invention to adjust the cooling capacity accordingly with the change of the operating condition
- Figure 1 is the control flow chart of the present invention.
- Figure 2 is a system diagram of embodiment 1 of the present invention.
- Figure 3 is a system diagram of embodiment 2 of the present invention.
- Figure 4 is a system diagram of embodiment 3 of the present invention.
- Figure 5 is a system diagram of embodiment 4 of the present invention.
- FIG. 1 Compression-expansion machine; 2. Compression device; 3. Cooler; 4. Insulation device; 5. Heat recovery heat exchanger; 6. Heat exchanger; 7. First motor; 8. Second motor; 9. Controller; 10. Regulating valve of bypass branch; 11. Sensor device; C1. First-stage compressor; C2. Second-stage compressor; C3. Third-stage compressor; E1. Expander; L1. Fluid inlet pipe section; L2. Fluid outlet pipe section.
- the present invention proposes a cooling system with variable operating condition adjustment for a fluid, wherein the fluid may preferably be liquefied natural gas, carbon dioxide, hydrogen or helium, or a mixture of at least two of liquefied natural gas, carbon dioxide, hydrogen or helium.
- the cooling system includes a cooling circuit for cooling the fluid.
- a refrigerant is closed in the cooling circuit.
- the refrigerant is an inert gas.
- the refrigerant is preferably He, N2, H2 or Ne, or a mixture of at least two of He, N2, H2 and Ne.
- the cooling circuit of the cooling system includes:
- the compressor is used to compress the refrigerant of the cooling system; in the present embodiment, the compressor adopts a three-stage series compression method, that is, it includes a first-stage compressor C1, a second-stage compressor C2, and a third-stage compressor C3.
- the first-stage compressor C1, the second-stage compressor C2, and the third-stage compressor C3 are arranged in series, that is, the refrigerant passes through the first-stage compressor C1, the second-stage compressor C2, and the third-stage compressor C3 step by step in sequence, so that the refrigerant is pressurized step by step by each stage of the compressor, thereby gradually increasing the pressure of the refrigerant.
- the function of the cooler 3 is to cool the refrigerant after being compressed by the compressor.
- the interior of the cooler 3 includes three independent cooler modules, and each independent cooler module is respectively connected to the outlet of the first-stage compressor C1, the second-stage compressor C2, and the third-stage compressor C3, so as to cool down the refrigerant at the outlet of each stage of the compressor.
- the refrigerant it is compressed in the compressor, the volume is reduced, the pressure of the refrigerant will increase, and the temperature of the refrigerant will also increase; therefore, here, by arranging a cooler module at the outlet of each stage of the compressor, the temperature of the refrigerant can be reduced.
- the cold source in the cooler can be selected from cooling water or air at room temperature.
- the refrigerant at normal temperature and normal pressure (it does not refer to normal temperature and normal pressure relative to the ambient temperature, but refers to the relative state of the refrigerant circulating in the cooling circuit, and the same applies to the high temperature, low temperature, medium pressure, high pressure, and low pressure described below) is compressed by the first-stage compressor C1 to become a high-temperature and medium-pressure refrigerant, and then cooled by the cooler 3 to become a refrigerant at normal temperature and medium pressure, and then compressed by the second-stage compressor C2 to become a high-temperature and sub-high-pressure refrigerant, and then cooled by the cooler 3 to become a refrigerant at normal temperature and sub-high-pressure, and then compressed by the third-stage compressor C3 to become a high-temperature and high-pressure refrigerant, and then cooled by the cooler 3 to become a refrigerant at normal temperature and high pressure.
- the expander E1 is used to expand the cooled refrigerant.
- the inlet of the expander E1 is fluidically connected to the cooler 3, so as to expand the refrigerant at normal temperature and high pressure that has been compressed by the three-stage compressor and cooled by the cooler; in the expander E1, the volume of the refrigerant at normal temperature and high pressure increases, so that the pressure and temperature are reduced, and thus the refrigerant at normal temperature and high pressure is expanded by the expander E1 to become a refrigerant at low temperature and low pressure.
- the cooling circuit in order to cool the fluid, especially LNG, the cooling circuit includes a heat exchanger 6, wherein the fluid enters the heat exchanger 6 through the fluid inlet pipe section L1, and then the fluid flows out of the heat exchanger 6 through the fluid outlet pipe section L2.
- heat exchanger 6 heat is exchanged between the low-temperature and low-pressure refrigerant with deep cooling capacity and the cooled fluid.
- the cooled fluid transfers heat to the low-temperature and low-pressure refrigerant, thereby further reducing the temperature of the cooled fluid.
- the heat exchanger 6 can use a multi-stream heat exchanger; as shown in Figure 2, in at least part of the section of the heat exchanger 6, the flow direction of the fluid is opposite to the flow direction of the refrigerant, that is, the two transfer heat in the heat exchanger 6 in a relatively countercurrent flow manner, which can improve the efficiency of heat transfer and improve the cooling effect on the cooled fluid.
- a regenerative heat exchanger 5 is further provided here, and the refrigerant output by the heat exchanger 6 is used in the regenerative heat exchanger 5 to cool the normal-temperature and high-pressure refrigerant at the inlet of the expander E1, so as to further reduce the intake temperature of the expander E1 and achieve energy saving.
- the flow direction of the normal-temperature and high-pressure refrigerant at the inlet of the expander E1 is opposite to the flow direction of the refrigerant output by the heat exchanger 6, that is, the two transfer heat in the regenerative heat exchanger 5 in a relatively countercurrent flow manner, which can improve the efficiency of heat transfer and the cooling effect.
- a heat preservation device 4 is provided, and the regenerative heat exchanger 5 and the heat exchanger 6 are arranged in the heat preservation device 4, which effectively isolates the low-temperature cooled fluid and the heat exchange of the refrigerant with the external environment, thereby improving the effect of the entire cooling system.
- the refrigerant flows through the first-stage compressor C1, cooler 3, second-stage compressor C2, cooler 3, third-stage compressor C3, cooler 3, heat recovery heat exchanger 5, expander E1, heat exchanger 6, heat recovery heat exchanger 5 in sequence, and then returns to the inlet of the first-stage compressor C1, completing a cycle in the cooling circuit.
- Such a reciprocating cycle can provide continuous deep cooling capacity to the cooled fluid.
- the first-stage compressor C1, the second-stage compressor C2, and the third-stage compressor C3 can be axial flow compressors and/or centrifugal compressors, and the expander E1 can be an axial flow expander or a centrifugal expander.
- the cooling circuit also includes a first motor 7 and a second motor 8.
- the first motor 7 is used to drive the first-stage compressor C1
- the second motor 8 is used to drive the second-stage compressor C2 and the third-stage compressor C3.
- the second-stage compressor C2, the third-stage compressor C3 and the second motor 8 are connected via a common rotating shaft, so that only one second motor 8 is used to drive the second-stage compressor C2 and the third-stage compressor C3.
- the refrigerant expands in the expander E1, and then does work on the expander E1, so that the expander E1 rotates and can output mechanical energy.
- the expander E1 in order to improve the system operation effect by utilizing the energy output by the expander E1, as shown in FIG2 , the expander E1, the first motor 7 and the first-stage compressor C1 are installed on the same rotating shaft to form a compression-expansion integrated machine 1, so that the mechanical energy output by the first motor 7 and the mechanical energy output by the expander E1 can be transmitted to the first-stage compressor C1 through the common rotating shaft, thereby improving the energy utilization efficiency.
- the expander E1 can also be installed on a common rotating shaft with the second-stage compressor C2 and/or the third-stage compressor C3 to form a compression-expansion integrated machine, and the first-stage compressor C1 is driven by a motor alone; or two expanders arranged in series or in parallel are provided, and each expander can form a compression-expansion integrated machine coaxially with a compressor to drive the compressor.
- the compression-expansion integrated machine can include a compressor and an expander rotating coaxially, or a compressor, an expander and a motor rotating coaxially.
- a further alternative scheme in order to improve the refrigeration capacity of the cooling circuit, may include multiple compressors, multiple expanders, and three or more electric motors, with the number of compressors being more than 3 and the number of expanders being more than 2; wherein the multiple compressors are arranged in series, or in parallel, or in a combination of series and parallel.
- each compressor may be driven only by an electric motor, or coaxially driven by an electric motor and an expander, thereby forming a deep-cold evaporative gas cooling system with a more powerful refrigeration capacity.
- a bypass branch is also provided in the cooling circuit. Specifically, the upstream end of the bypass branch is connected to the pipe section between the cooler 3 and the heat exchanger 5, and the downstream end of the bypass branch is connected to the pipe section between the heat exchanger 5 and the inlet of the first-stage compressor C1, so that the high-pressure refrigerant after three-stage compression is partially delivered to the inlet of the first-stage compressor C1, which is used for anti-surge backflow and pressure and temperature regulation during the startup process in the system.
- a regulating valve 10 is provided on the bypass branch to regulate the refrigerant flowing from the inlet of the expander E1 to the outlet of the expander E1 via the bypass branch, or to regulate the refrigerant after three-stage compression flowing to the inlet of the first-stage compressor C1 via the bypass branch, especially to regulate the flow rate or pressure.
- the amount of refrigerant flowing to the expander E1 can be directly regulated and controlled, and the flow rate of the refrigerant in the three-stage compressor can be increased.
- the regulating valve 10 can be opened to adjust the working state of the compressor or expander, eliminate the surge phenomenon, and prevent the compressor or expander from being damaged or even destroyed due to surge. Specifically, when the cooling system is started, the regulating valve 10 is fully opened; when the cooling system is running stably, the regulating valve 10 is fully closed.
- the cooling system of the present invention also has the ability to adjust variable working conditions.
- the cooling system includes a sensor device 11, specifically a temperature sensor.
- the sensor device 11 is arranged at the outlet of the expander E1, specifically located on the pipe section between the outlet of the expander E1 and the heat exchanger 6, to detect the temperature of the low-temperature and low-pressure refrigerant at the outlet of the expander E1.
- the state of the cooled fluid in the heat exchanger 6 changes, such as the flow rate changes or the temperature changes, that is, the required cooling capacity changes; in this example, the required cooling capacity increases, then at this moment, the working condition of the refrigerant does not change temporarily, but when heat exchange occurs in the heat exchanger 6, due to the increase in the required cooling capacity of the fluid, and the cooling capacity of the refrigerant does not change temporarily, the direct consequence is that the temperature of the refrigerant flowing out of the heat exchanger 6 will rise, then when the refrigerant flow rate and flow rate in the cooling circuit do not change, it will cause the temperature of the refrigerant at the outlet of the expander E1 to rise, and the cooling capacity provided will be even more insufficient, thereby deteriorating the cycle.
- a decrease in cooling demand will cause the temperature of the refrigerant at the outlet of expander E1 to drop
- a decrease in cooling supply will cause the temperature of the refrigerant at the outlet of expander E1 to rise
- an increase in cooling supply will cause the temperature of the refrigerant at the outlet of expander E1 to drop.
- the cooling system also includes a controller 9, wherein the controller 9 is connected to the sensor device 11 and can receive data detected by the sensor device 11; the controller 9 can also be connected to the first motor 7 and the second motor 8.
- the controller 9 can control the rotation speed of the first motor 7 and the second motor 8 based on the data of the sensor device 11, thereby changing the flow rate of the refrigerant in the cooling circuit, that is, the circulation rate, thereby adjusting the amount of refrigerant flowing through the heat exchanger 6 per unit time, and then adjusting the amount of cold provided by the cooling circuit to the cooled fluid to ensure that the cooled fluid can be fully, reliably and stably cooled.
- the rotation speed of the first motor 7 and the second motor 8 can be controlled based on the temperature value detected by the single sensor device 11, or based on the change rate of the temperature value detected by the single sensor device 11 (the derivative of the temperature value), or based on both the temperature value detected by the single sensor device 11 and its change rate.
- a preset value SP is set in the controller 9.
- the controller 9 adjusts the rotation speed of the first motor 7 and the second motor 8 through PID control, adjusts the circulation speed of the refrigerant in the cooling circuit, and then adjusts the cooling capacity provided by the cooling circuit until the actual value PV is the same as the preset value SP.
- the preset value can also be adjusted manually or automatically, especially when the state of the fluid in storage changes or the refrigerant changes, such as temperature rise, etc., when it is clear that the cooling demand of the fluid or the cooling supply of the refrigerant has changed, the preset value can be adjusted manually or automatically to adapt to the change in cooling demand or cooling supply.
- the specific adjustment method is shown in Figure 1. After the cooling demand and/or cooling supply changes, the sensor device 11 obtains the actual value PV detected by the monitoring point. When the actual value PV is different from the preset value SP, it indicates that the cooling demand and the cooling supply are in a mismatched state, and the controller 9 adopts the PID adjustment method to adjust the speed of the first motor 7 and the second motor 8.
- the speed or rotation frequency of the first motor 7 and the second motor 8 is continuously variable; specifically, for example, when the actual value PV is greater than the preset value SP, the controller 9 increases the speed of the first motor 7 and the second motor 8, and when the actual value PV is less than the preset value SP, the controller 9 reduces the speed of the first motor 7 and the second motor 8 until the actual value PV is the same as the preset value SP, which indicates that the cooling demand and the cooling supply are in a matched state.
- the PID adjustment method has the advantages of simple control, safety and reliability, and rapid adjustment. It enables the cooling system to adjust the cooling capacity accordingly as the working conditions change, and achieve variable working condition adjustment of the cooling capacity range of 0-100%. This can match the power consumption of the cooling system with the cooling demand, thereby improving energy utilization efficiency.
- Example 2 The arrangement of Example 2 is shown in Figure 3, and the parts that are the same as Example 1 are not repeated here.
- the difference between Example 2 and Example 1 is that the sensor device 11 is arranged on the outlet pipeline of the refrigerant of the heat exchanger 6 to detect the temperature of the refrigerant after absorbing the heat of the cooled fluid in the heat exchanger 6. Then, at this monitoring point, it can also reflect whether the cooling demand and cooling supply match.
- Example 2 The control method of Example 2 is the same as that of Example 1, as shown in Figure 1, and will not be repeated here.
- Example 3 The arrangement of Example 3 is shown in Figure 4, and the parts that are the same as those in Example 1 are not repeated here.
- the difference between Example 3 and Example 1 is that the sensor device 11 is arranged on the inlet pipeline of the refrigerant of the expander E1 to detect the temperature of the refrigerant at the inlet of the expander E1. Then, at this monitoring point, it can also reflect whether the required cooling capacity and the supplied cooling capacity match.
- Example 3 The control method of Example 3 is the same as that of Example 1, as shown in Figure 1, and will not be repeated here.
- Example 4 The arrangement of Example 4 is shown in Figure 5, and the parts that are the same as those of Example 1 are not repeated here.
- the difference between Example 4 and Example 1 is that the sensor device 11 is directly arranged on the fluid outlet pipe section L2 of the cooled fluid of the heat exchanger 6 to detect the temperature of the refrigerant in the fluid outlet pipe section L2 of the cooled fluid of the heat exchanger 6. Then, at this monitoring point, it can also reflect whether the cooling demand and cooling supply match.
- Example 4 The control method of Example 4 is the same as that of Example 1, as shown in Figure 1, and will not be elaborated here.
- the sensor device 11 is arranged at only one monitoring point, alternatively, more than two sensor devices 11 may be arranged in the cooling system, and the sensor devices 11 are arranged at different positions respectively, so as to be able to more quickly monitor the change in the cooling capacity required by the fluid or the change in the cooling capacity supplied by the refrigerant.
- a sensor device may be arranged at the refrigerant inlet and outlet of the heat exchanger, thereby being able to monitor the temperature change of the refrigerant and the temperature difference of the refrigerant at the inlet and outlet of the heat exchanger in real time, and detecting the change in the working condition of the refrigerant more quickly and more rapidly; or a sensor device may be arranged at the fluid inlet and outlet of the heat exchanger, thereby being able to monitor the temperature change of the fluid and the temperature difference of the fluid at the inlet and outlet of the heat exchanger in real time, and detecting the change in the working condition of the fluid more quickly and more rapidly.
- the controller when it makes adjustments, it can use PID control to adjust the motor based on the data of a single sensor device (including temperature value, speed of change of temperature value, etc.), or based on the difference of multiple sensors, or based on the data of a single sensor device (including temperature value, speed of change of temperature value, etc.), the difference of multiple sensors, and/or the rate of change of the difference of multiple sensors (derivative of the difference of multiple sensors).
- the controller can only make adjustments based on the data of one sensor device when performing control and adjustment; or, in different situations, the data of corresponding different single sensors are used for adjustment, but only the data of one sensor device is used in one situation.
- the cooling system includes an expander, a compressor driven by an electric motor, the speed of the electric motor is adjustable, and also includes a controller and a sensor device, the sensor device is configured to detect the temperature of the fluid and/or the cooling medium, the controller can receive data from the sensor device, and can control the speed of the motor based on the data of the sensor device, and then when the required cooling capacity of the cooled fluid and/or the cooling capacity provided by the refrigerant changes, by adjusting the speed of the motor, it can ensure that the temperature of the cooled fluid is maintained at a predetermined value; in particular, the control is carried out by PID adjustment, which has the advantages of simple control, safety and reliability, and rapid adjustment, and can enable the cooling system of the present invention to adjust the cooling capacity accordingly with the change of the operating condition, and realize variable operating condition adjustment with a cooling capacity range of 0-100%.
- PID adjustment which has the advantages of simple control, safety and reliability, and rapid adjustment, and can enable the cooling system of the present invention to adjust the cooling capacity accordingly with the change of the
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Abstract
一种用于流体的具有可变工况调节功能的冷却系统，包括压缩机（C）、膨胀机（E）、冷却器（3）、热交换器（6）、电动机（7、8）、控制器（9）和传感装置（11），传感装置用于检测流体和/或冷却工质的温度，控制器能够接收传感装置的数据，并能够通过PID调节的方式控制电动机的转速，保证流体被冷却后的温度保持在预定值。本冷却系统控制简单、安全可靠、调节迅速。
Description
本发明涉及LNG存储及输送领域，尤其涉及应用于LNG船中蒸发气体的处理系统，特别是涉及一种用于流体的具有可变工况调节功能的冷却系统。
随着经济社会及现代工业的高速发展，能源利用和环境污染成为世界关注的焦点。面对日益严苛的环保要求，国际能源战略转型加速，清洁燃料的开发和应用成为能源战略的重要发展方向，其中天然气以其污染物排放量小、成本相对较低的特点，使得天然气在国际能源供应中的比例逐年上涨，预计全球天然气消费需求快速增长的态势将一直持续到2040年。相比于天然气采用管道运输，由于海上LNG（液化天然气，Liquified Natural GAS）运输不需要铺设很长的输送管道，并且能够灵活地将天然气输送到世界各地，因而具有灵活、产地及目的地多样化的优点。随着天然气贸易量的持续迅猛增长，全球LNG 海运行业也将随之迅速发展，预计2030年前全球将新增600艘大型LNG船订单。
鉴于LNG特殊的理化特性，任何LNG船在运输过程中，即使在液货舱绝热性能很好的情况下，LNG都有可能收到外部传导的热量，从而产生蒸发气。蒸发气的产生会使得液货舱压力升高，破坏液货舱的结构，若将蒸发气直接排入大气中，也会造成直接的经济损失和温室危害。因而，需要设置针对蒸发气的冷却系统，冷却系统能够将液货舱中蒸发气重新冷凝液化，降低液货舱中蒸发气的蒸发可能性，降低运输成本并且提高LNG运输的安全性，是目前大型LNG运输船、加注船上重要的高附加值设备。这样的问题也存在于陆上的LNG储存设施中。
但是，目前LNG蒸发气体冷却系统，从工艺技术来看，采用混合工质再液化方式会导致流程复杂、维护难度大，且丙烷等工质为易爆气体，泄漏风险大，危险性高；而采用氮膨胀再液化方式，其使用惰性气体作为制冷剂，安全性较高，但系统需要蒸发气压缩机、氮气发生器、蒸发气加热器等较多辅助设备，安装调试周期长，维护成本高。同时，由于LNG储存装置中的压力和温度受很多因素的影响，比如外部温度变化、进出LNG的量的变化以及相应温度的变化等，都造成LNG储存装置中的压力和温度处于不断地波动中。因而，急需开发一种具备安全性高、可靠性强、适应性强的控制方式的LNG冷却系统。
为解决上述技术问题，本发明提出一种用于流体的具有可变工况调节的冷却系统，该流体优选地可以是液化天然气，冷却系统包括冷却回路，冷却回路用于冷却该流体，冷却回路包括：
压缩机，用以对冷却系统的制冷工质进行压缩，由此提高制冷工质的压力；
冷却器，对压缩后的制冷工质进行冷却；
膨胀机，用以使冷却后的制冷工质膨胀；
电动机，能够驱动压缩机对制冷工质进行压缩，其中，电动机的转速是可调节的，尤其是连续可变的；
热交换器，用于在被冷却的流体与膨胀后的制冷工质之间产生热量交换；
制冷工质在冷却回路中以封闭循环的方式运行，制冷工质在压缩机中被压缩后，经过冷却器被冷却而降温，然后通过膨胀机膨胀而使得压力降低并且温度降低，之后在热交换器中从被冷却的流体吸收热量用以降低被冷却的流体的温度，吸收热量后的制冷工质然后进入压缩机被压缩；
冷却系统还包括控制器和传感装置，传感装置被配置用于检测流体和/或冷却工质的温度，传感装置和电动机与控制器连接，控制器能够接收传感装置的数据，并基于传感装置的数据来控制电动机的转速。
进一步，传感装置能够设置在膨胀机的进口管段、膨胀机出口与热交换器之间的管段、热交换器的被冷却的流体的出口管段、热交换器的制冷工质的出口管段中的至少一个上。
进一步，对于传感装置所安装位置处的制冷工质的或被冷却的流体的与温度相关的数值，控制器中设置有对应的预定值，当该传感装置所测得的实际值与预定值不同时，控制器通过PID的控制方式调节电动机的转速，用以调节冷却回路中的制冷工质的循环速度进而调整冷却回路所提供的制冷量，直到实际值与预定值相同；尤其，当实际值大于预定值时，控制器增加电动机的转速，而当实际值小于预定值时，控制器则降低电动机的转速。
进一步，与温度相关的数值能够是单个传感装置检测到的温度值、单个传感装置检测到的温度值的变化速度、多个传感装置检测到的温度值的差值或者多个传感装置检测到的温度值的差值的变化速度
进一步，在热交换器的至少部分区段中的流体的流向方向与膨胀后的制冷工质的流向方向相反；其中，制冷工质采用惰性气体，制冷工质优选地选用He、N2、H2或Ne，或者包括He、N2、H2、Ne中至少两种气体的混合气；其中，流体为液化天然气、二氧化碳、氢气或氦气，或者包括液化天然气、二氧化碳、氢气或氦气中至少两种的混合气。
进一步，冷却回路还包括回热换热器，流出热交换器的制冷工质与进入膨胀机之前的制冷工质在回热换热器中产生热量交换；热交换器与回热换热器被安装在保温装置中。
进一步，所述压缩机的数量为至少两台，至少两台压缩机在冷却回路中以串联和/或并联的方式设置，使得制冷工质以串联和/或并联的方式流经至少两台压缩机，其中，在每台压缩机的出口设置有冷却器；制冷工质在膨胀机中发生膨胀使得膨胀机输出能量，至少两台压缩机中的至少一台压缩机能够接收膨胀机所输出的能量；至少两台压缩机中的至少一台压缩机能够被电动机所驱动。
进一步，至少两台压缩机中的至少一台压缩机能够与电动机、膨胀机以共轴传动地方式设置，使得该至少一台压缩机被电动机和膨胀机输出的能量共同地驱动。
进一步，所述膨胀机的数量为至少两台，至少两台膨胀机在冷却回路中以串联和/或并联的方式设置，使得制冷工质以串联和/或并联的方式流经至少两台膨胀机。
进一步，所述压缩机为轴流式压缩机或离心式压缩机，所述膨胀机为轴流式膨胀机或离心式膨胀机。
进一步，所述膨胀机设置有旁路支路，旁路支路的一端连接膨胀机的进口，旁路支路的另一端连接膨胀机的出口，优选地在旁路支路上设置有调节阀，用以对从膨胀机进口经由旁路支路流向膨胀机出口的制冷工质进行调节；尤其，旁路支路的一端连接在膨胀机的进口的位于热交换器的上游的管段，旁路支路的另一端连接在膨胀机的出口的位于热交换器的下游的管段。
实施本发明，具有如下有益效果：通过本发明的用于流体的具有可变工况调节的冷却系统，冷却系统包括由电动机驱动的压缩机，电动机的转速是可调的，还包括控制器和传感装置，传感装置被配置用于检测流体和/或冷却工质的温度，控制器能够接收传感装置的数据，并能够基于传感装置的数据来控制电动机的转速，进而能够在被冷却流体的需求冷量和/或制冷工质所提供的冷量发生变化时，通过调节电动机的转速，进而能够保证流体被冷却后的温度保持在预定值；特别地是通过PID调节的方式来进行控制，具有控制简单、安全可靠、调节迅速的优点，能够使得本发明的冷却系统能够跟随工况的变化而对应地调整冷量，实现冷量范围为0—100%的变工况调节。
为了更清楚地说明本发明的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其它附图。
图1是本发明的控制流程图。
图2是本发明的实施例1的系统图。
图3是本发明的实施例2的系统图。
图4是本发明的实施例3的系统图。
图5是本发明的实施例4的系统图。
附图标记：1、压缩膨胀一体机；2、压缩装置； 3、冷却器；4、保温装置；5、回热换热器；6、热交换器；7、第一电动机；8、第二电动机；9、控制器；10、旁路支路的调节阀；11、传感装置；C1、一级压缩机；C2、二级压缩机；C3、三级压缩机；E1、膨胀机；L1、流体进口管段；L2、流体出口管段。
下面将结合本发明实施例中的附图，对发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明的实施例，本领域普通技术人员在没有做出创造性劳动的前提下所获得的所有其他实施例，都属于本发明保护的范围。
为解决上述技术问题，本发明提出一种用于流体的具有可变工况调节的冷却系统，该流体优选地可以是其中，流体为液化天然气、二氧化碳、氢气或氦气，或者包括液化天然气、二氧化碳、氢气或氦气中至少两种的混合气。
冷却系统包括冷却回路，冷却回路用于冷却该流体，在冷却回路中封闭地设置有制冷工质，制冷工质采用惰性气体，制冷工质优选地选用He、N2、H2或Ne，或者包括He、N2、H2、Ne中至少两种气体的混合气。
实施例1：
如图2所示，冷却系统的冷却回路包括：
压缩机，用以对冷却系统的制冷工质进行压缩；在本实施例中，压缩机采用了三级串联压缩的方式，也即包括一级压缩机C1、二级压缩机C2、三级压缩机C3，对于制冷工质来说，一级压缩机C1、二级压缩机C2、三级压缩机C3以串联的方式布置，也就是说制冷工质依次逐级地通过一级压缩机C1、二级压缩机C2、三级压缩机C3，由此制冷工质被每级压缩机逐级地加压，从而逐级地提高了制冷工质的压力。
冷却器3，其作用是对压缩机压缩之后的制冷工质进行冷却，在本实施例中，冷却器3的内部包括三个独立的冷却器模块，每个独立的冷却器模块分别连接至一级压缩机C1、二级压缩机C2、三级压缩机C3的出口，用以分别对每级压缩机出口的制冷工质进行冷却降温。对于制冷工质来说，其在压缩机中被压缩，体积减小，制冷工质的压力会增高的同时，制冷工质的温度也会升高；因而在此，通过在每级压缩机的出口处设置冷却器模块，进而能够使得制冷工质的温度降低。在此，冷却器中的冷源可以选用常温的冷却水或常温空气。由此，常温常压（并非指相对环境温度的常温常压，而是指在该冷却回路中循环的制冷工质的相对状态，下述的高温、低温、中压、高压、低压也是同理）的制冷工质经过一级压缩机C1的压缩变为高温中压的制冷工质，然后经过冷却器3的冷却变为常温中压的制冷工质，然后经过二级压缩机C2的压缩变为高温次高压的制冷工质，然后经过冷却器3的冷却变为常温次高压的制冷工质，然后经过三级压缩机C3的压缩变为高温高压的制冷工质，然后经过冷却器3的冷却变为常温高压的制冷工质。
膨胀机E1，用以使冷却后的制冷工质膨胀。膨胀机E1的进口流体地连接至冷却器3，用以对经过三级压缩机压缩和冷却器冷却的常温高压的制冷工质进行膨胀；在膨胀机E1中，常温高压的制冷工质体积变大，使得压力降低、温度降低，从而常温高压的制冷工质经过膨胀机E1的膨胀变为低温低压的制冷工质。
在此，为了能够对流体，特别是LNG进行冷却，冷却回路包括热交换器6，其中流体通过流体进口管段L1进入热交换器6，之后流体通过流体出口管段L2流出热交换器6。在热交换器6中，具备深冷能力的低温低压的制冷工质与被冷却的流体之间进行热量交换，具体地，被冷却的流体将热量转移至低温低压的制冷工质，从而使得被冷却的流体的温度进一步降低。热交换器6可以选用多股流换热器；其中如图2所示，在热交换器6的至少部分区段中，流体的流动方向与制冷工质的流动方向相反，也即两者是以相对逆流式的流动方式在热交换器6中进行热量的转移，能够提高热量转移的效率，提高对被冷却的流体的冷却效果。
同时，由于在热交换器6中，低温低压的制冷工质在吸收被冷却的流体热量后依然具备较低的温度，在此进一步地设置有回热换热器5，在回热换热器5中利用热交换器6输出的制冷工质对膨胀机E1进口的常温高压的制冷工质进行冷却，用以进一步降低膨胀机E1的进气温度，达到节能目的。同样地，如图2所示，在回热换热器5的至少部分区段中，膨胀机E1进口的常温高压的制冷工质的流动方向与热交换器6输出的制冷工质的流体流动方向相反，也即两者是以相对逆流式的流动方式在回热换热器5中进行热量的转移，能够提高热量转移的效率，提高冷却效果。在此，为了保证被冷却的流体以及制冷工质不向外界环境散发冷量，设置有保温装置4，回热换热器5与热交换器6设置在保温装置4中，有效地隔绝了低温的被冷却流体以及制冷工质与外界环境的热交换，提高了整个冷却系统的效果。
由此，制冷工质依次流经一级压缩机C1、冷却器3、二级压缩机C2、冷却器3、三级压缩机C3、冷却器3、回热换热器5、膨胀机E1、热交换器6、回热换热器5后，返回至一级压缩机C1的进口，在冷却回路中完成一个循环。如此往复循环，就能够向被冷却的流体提供持续性的深冷冷却能力。
所述一级压缩机C1、二级压缩机C2、三级压缩机C3可以轴流式压缩机和/或离心式压缩机，所述膨胀机E1可以选用轴流式膨胀机或离心式膨胀机。
由于压缩机是将外部能量转化为其所压缩的气体的内能，因而需要由外部的动力驱动才能够运转。在本实施例中，冷却回路还包括第一电动机7、第二电动机8，第一电动机7用于驱动一级压缩机C1，第二电动机8用于驱动二级压缩机C2、三级压缩机C3。特别地，如图2所示，二级压缩机C2、三级压缩机C3与第二电动机8通过共同的旋转轴连接，由此，只用一个第二电动机8来驱动二级压缩机C2和三级压缩机C3。
而制冷工质在膨胀机E1中膨胀，进而会对膨胀机E1做功，使得膨胀机E1旋转进而能够输出机械能。在此，为了能够利用膨胀机E1输出的能量来提高系统运转效果，如图2所示，将膨胀机E1、第一电动机7以及一级压缩机C1安装在同一根旋转轴上，形成压缩膨胀一体机1，由此使得第一电动机7输出的机械能以及膨胀机E1输出的机械能能够通过该共同的旋转轴共同地输送至一级压缩机C1，由此提高了能源利用效率。当然替代地，膨胀机E1也可以与二级压缩机C2和/或三级压缩机C3安装在共同的旋转轴上形成压缩膨胀一体机，而一级压缩机C1则单独地由电动机驱动；或者设置有两个串联或并联布置的膨胀机，每个膨胀机都能与一个压缩机共轴形成压缩膨胀一体机，来驱动压缩机。在此申明，压缩膨胀一体机既可以包括共轴旋转的压缩机和膨胀机，也可以包括共轴旋转的压缩机、膨胀机和电动机。
进一步替代的方案，为了提高冷却回路的制冷能力，可以包括多台压缩机、多台膨胀机、三台以上电动机，压缩机的数量为3台以上，膨胀机的数量为2台以上；其中，多台压缩机以串联的方式布置、或者以并联的方式布置、或者以串并联组合的方式布置，具体地，每台压缩机既可以只由电动机驱动，也可以由电动机和膨胀机共同地共轴驱动，由此组成制冷能力更加强大的深冷式蒸发气体冷却系统。
如图2所示，冷却回路中还设置有旁路支管，具体地，旁路支管的上游端连接至冷却器3与回热换热器5之间的管段，旁路支管的下游端则连接至位于回热换热器5与一级压缩机C1进口之间的管段，将经过三级压缩后的高压的制冷工质部分地输送至一级压缩机C1的进口中，用于系统内的防喘振回流和开机过程的压力温度调节。进一步地为了达到调节的效果，优选地在旁路支路上设置有调节阀10，用以对从膨胀机E1进口经由旁路支路流向膨胀机E1出口的制冷工质进行调节，或者说，用以对三级压缩后的制冷工质经由旁路支路流向一级压缩机C1进口的制冷工质进行调节，尤其是对流量或压力进行调节。这样，能够直接地调节和控制流向膨胀机E1的制冷工质的量，并且增大三级压缩机中制冷工质的流量。由此，在压缩机或膨胀机发生喘振时，能够打开调节阀10，来调整压缩机或膨胀机的工作状态，消除喘振现象，防止压缩机或膨胀机因喘振受损甚至毁坏。具体地，在冷却系统启动时，调节阀10完全打开；在冷却系统稳定运行时，调节阀10则完全关闭。
而由于被冷却流体的需冷量会在多种因素的影响下不断地发生变化，同时，冷却回路中的制冷工质提供的冷量也会在多种因素的影响下不断地发生变化，这就造成冷却回路的工况不断地发生变化。为了保证冷却回路能够对被冷却的流体在变化的情况下提供可靠、稳定的冷却效果，本发明的冷却系统还具备可变工况调节能力。
如图2所示，冷却系统包括传感装置11，具体地为温度传感器，传感装置11设置在膨胀机E1的出口，具体地位于膨胀机E1出口与热交换器6之间的管段上，用以检测膨胀机E1出口的低温低压的制冷工质的温度。对于本发明的冷却系统，当热交换器6中的被冷却流体的状态发生变化，例如流量发生变化或者温度发生变化，也即需冷量发生变化时；在此举例需冷量增大，那么此刻制冷工质的工况暂时未变，但是在热交换器6中产生热量交换时，由于流体的需冷量增大，而制冷工质的供冷量暂未变，直接地后果是造成流出热交换器6的制冷工质的温度会上涨，那么在冷却回路中制冷工质流速及流量未变时，会造成膨胀机E1出口的制冷工质的温度上升，提供的供冷量更加不足，由此循环恶化。同样的逻辑，需冷量减小会造成膨胀机E1出口的制冷工质的温度下降，供冷量减小会造成膨胀机E1出口的制冷工质的温度上升，供冷量增大会造成膨胀机E1出口的制冷工质的温度下降。
冷却系统还包括控制器9，其中，控制器9与传感装置11相连，能够接收传感装置11检测到的数据；控制器9还能够与第一电动机7、第二电动机8相连，控制器9能够基于传感装置11的数据来控制第一电动机7、第二电动机8的转速，进而改变冷却回路中制冷工质的流动速度，也即循环倍率，由此，就能够调节在单位时间内流经热交换器6的制冷工质的量，进而调节冷却回路向被冷却的流体所提供的冷量，来保证被冷却流体能够得到充分、可靠、稳定的冷却。在此，控制器9进行调节时，既可以基于该单个传感装置11所检测到的温度值，或者基于该单个传感装置11所检测到的温度值的变化速度（温度值的导数），或者同时基于该单个传感装置11所检测到的温度值以及其变化速度，来控制第一电动机7、第二电动机8的转速。
为了能够保证冷却回路提供恰当的供冷量来与被冷却流体的需冷量匹配，来提高冷却回路的效率，在控制器9中设置有预定值SP，当该传感装置11所测得的实际值PV与预定值SP不同时，控制器9通过PID的控制方式调节第一电动机7、第二电动机8的转速，调节冷却回路中的制冷工质的循环速度进而调整冷却回路所提供的制冷量，直到实际值PV与预定值SP相同。特别地，附加地，还能够人工或自动地调整预定值，尤其当流体在储存中的状态发生变化或制冷工质发生变化时，例如温度上升等，在明确了流体的需冷量或制冷工质的供冷量发生变化时，可以人工或自动地调整预定值，用以适配需冷量或供冷量的变化。
具体调节方法如图1所示，在需冷量和/或供冷量发生变化后，传感装置11获取监测点所检测到的实际值PV，当实际值PV与预定值SP不同时，表示需冷量与供冷量处于不匹配的状态，控制器9则采用PID的调节方式节第一电动机7、第二电动机8的转速，在此，第一电动机7、第二电动机8的转速或转动频率是连续可变的；具体地例如，当实际值PV大于预定值SP时，控制器9则增加第一电动机7、第二电动机8的转速，而当实际值PV小于预定值SP时，控制器9则降低第一电动机7、第二电动机8的转速，直至实际值PV与预定值SP相同，则表示需冷量与供冷量处于匹配的状态。
采用PID的调节方式，具有控制简单、安全可靠、调节迅速的优点，能够使得冷却系统能够跟随工况的变化而对应地调整供冷量，实现供冷量范围为0—100%的变工况调节，由此能够使得冷却系统的功耗与需冷量匹配，提高能源利用效率。
实施例2：
实施例2的布置方式如图3所示，在此，与实施例1相同的部分不做赘述。实施例2与实施例1不同的地方在于，将传感装置11布置在热交换器6的制冷工质的出口管路上，用以检测在热交换器6中吸收被冷却流体的热量后的制冷工质的温度。那么，在该监测点处，同样能够反应需冷量与供冷量之间是否匹配。
实施例2的控制方式同实施例1相同，如图1所示，在此不做赘述。
实施例3：
实施例3的布置方式如图4所示，在此，与实施例1相同的部分不做赘述。实施例3与实施例1不同的地方在于，将传感装置11布置在膨胀机E1的制冷工质的进口管路上，用以检测在膨胀机E1的进口的制冷工质的温度。那么，在该监测点处，同样能够反应需冷量与供冷量之间是否匹配。
实施例3的控制方式同实施例1相同，如图1所示，在此不做赘述。
实施例4：
实施例4的布置方式如图5所示，在此，与实施例1相同的部分不做赘述。实施例4与实施例1不同的地方在于，将传感装置11直接布置在热交换器6的被冷却流体的流体出口管段L2上，以检测热交换器6的被冷却流体的流体出口管段L2中的制冷工质的温度。那么，在该监测点处，同样能够反应需冷量与供冷量之间是否匹配。
实施例4的控制方式同实施例1相同，如图1所示，在此不做赘述。
尽管在上述实施例中，传感装置11只布置在一个监控点处，但是替代地，也可以在冷却系统中设置两个以上的传感装置11，传感装置11分别布置在不同的位置处，用以能够更快地监测流体需冷量的变化或者制冷工质的供冷量的变化。例如，可以在热交换器的制冷工质入口以及出口设置传感装置，由此能够实时地监控制冷工质的温度变化以及热交换器进出口的制冷工质的温差，更快、更迅速地检测到制冷工质的工况变化；或者在热交换器的流体入口和出口设置传感装置，由此能够实时地监控流体的温度变化以及热交换器进出口的流体的温差，来更快、更迅速地检测到流体的工况变化。进一步地，控制器进行调节时，既可以基于单个传感装置的数据（包括温度值、温度值的变化速度等），或者基于多个传感装置的差值，或者基于单个传感装置的数据（包括温度值、温度值的变化速度等）、多个传感装置的差值和/或多个传感装置的差值的变化率（多个传感装置的差值的导数）采用PID控制来对电动机进行调节。特别地，为了能够实现简单快速且安全的调节方式，尽管在冷却系统中设置有多个传感装置，控制器在执行控制和调节时，可以只基于一个传感装置的数据来进行调节；或者，在不同的状况下，采用对应的不同的单个传感装置的数据来进行调节，但是，一个状况下也仅采用一个传感装置的数据。
实施本发明，具有如下有益效果：通过本发明的用于流体的具有可变工况调节的冷却系统，冷却系统包括膨胀机，由电动机驱动的压缩机，电动机的转速是可调的，还包括控制器和传感装置，传感装置被配置用于检测流体和/或冷却工质的温度，控制器能够接收传感装置的数据，并能够基于传感装置的数据来控制电动机的转速，进而能够在被冷却流体的需求冷量和/或制冷工质所提供的冷量发生变化时，通过调节电动机的转速，进而能够保证流体被冷却后的温度保持在预定值；特别地是通过PID调节的方式来进行控制，具有控制简单、安全可靠、调节迅速的优点，能够使得本发明的冷却系统能够跟随工况的变化而对应地调整冷量，实现冷量范围为0—100%的变工况调节。
以上所揭露的仅为本发明的几个较佳实施例而已，当然不能以此来限定本发明之权利范围，因此依本发明权利要求所作的等同变化，仍属本发明所涵盖的范围。
Claims (14)
- 一种用于流体的具有可变工况调节功能的冷却系统，冷却系统包括冷却回路，冷却回路用于冷却该流体，冷却回路包括： 压缩机，用以对冷却系统的制冷工质进行压缩；冷却器，对压缩后的制冷工质进行冷却；膨胀机，用以使冷却后的制冷工质膨胀；电动机，能够驱动压缩机对制冷工质进行压缩，其中，电动机的转速是可调节的； 热交换器，用于在被冷却的流体与膨胀后的制冷工质之间产生热量交换；其中，冷却系统还包括控制器和传感装置，传感装置被配置用于检测流体和/或冷却工质的温度，传感装置和电动机与控制器连接，控制器用于接收传感装置的数据，并基于传感装置的数据来控制电动机的转速。
- 根据权利要求1所述的冷却系统，其特征在于，电动机的转速是连续可变的。
- 根据权利要求1所述的冷却系统，其特征在于，在膨胀机的进口管段、膨胀机出口与热交换器之间的管段、热交换器的被冷却的流体的出口管段、热交换器的制冷工质的出口管段中的至少一个上设置传感装置。
- 根据权利要求3所述的冷却系统，其特征在于，对于传感装置所安装位置处的制冷工质的与温度相关的数值或者被冷却的流体的与温度相关的数值，控制器中设置有对应的预定值；当该传感装置所测得的实际值与预定值不同时，控制器调节电动机的转速，直到实际值与预定值相同。
- 根据权利要求4所述的冷却系统，其特征在于，控制器采用PID的方式调节电动机的转速；所述预定值以可变的方式被设定；当该传感装置所测得的实际值大于预定值时，控制器增加电动机的转速，而当该传感装置所测得的实际值小于预定值时，控制器则降低电动机的转速。
- 根据权利要求4所述的冷却系统，其特征在于，与温度相关的数值是单个传感装置检测到的温度值、单个传感装置检测到的温度值的变化速度、多个传感装置检测到的温度值的差值和/或多个传感装置检测到的温度值的差值的变化速度。
- 根据权利要求1所述的冷却系统，其特征在于，在热交换器的至少部分区段中的流体的流向方向与膨胀后的制冷工质的流向方向相反；其中，制冷工质采用惰性气体；其中，流体为液化天然气、二氧化碳、氢气或氦气，或者包括液化天然气、二氧化碳、氢气或氦气中至少两种的混合气。
- 根据权利要求7所述的冷却系统，其特征在于，制冷工质选用He、N2、H2或Ne，或者包括He、N2、H2、Ne中至少两种气体的混合气。
- 根据权利要求1所述的冷却系统，其特征在于，冷却回路还包括回热换热器，流出热交换器的制冷工质与进入膨胀机之前的制冷工质在回热换热器中产生热量交换；热交换器与回热换热器被安装在保温装置中。
- 根据权利要求1至9中任一项所述的冷却系统，其特征在于，所述压缩机的数量为至少两台，至少两台压缩机在冷却回路中以串联和/或并联的方式设置，使得制冷工质以串联和/或并联的方式流经至少两台压缩机，其中，在每台压缩机的出口设置有冷却器；制冷工质在膨胀机中发生膨胀使得膨胀机输出能量，至少两台压缩机中的至少一台压缩机接收膨胀机所输出的能量；至少两台压缩机中的至少一台压缩机被电动机所驱动。
- 根据权利要求10所述的冷却系统，其特征在于，至少两台压缩机中的至少一台压缩机能够与电动机、膨胀机以共轴传动地方式设置，使得该至少一台压缩机被电动机和膨胀机输出的能量共同地驱动。
- 根据权利要求10所述的冷却系统，其特征在于，所述膨胀机的数量为至少两台，至少两台膨胀机在冷却回路中以串联和/或并联的方式设置，使得制冷工质以串联和/或并联的方式流经至少两台膨胀机。
- 根据权利要求1至12中任一项所述的冷却系统，其特征在于，所述膨胀机设置有旁路支路，旁路支路的一端连接膨胀机的进口，旁路支路的另一端连接膨胀机的出口，在旁路支路上设置有调节阀，用以对从膨胀机进口经由旁路支路流向膨胀机出口的制冷工质进行调节。
- 根据权利要求13所述的冷却系统，其特征在于，旁路支路的一端连接在膨胀机的进口的位于热交换器的上游的管段，旁路支路的另一端连接在膨胀机的出口的位于热交换器的下游的管段。
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| CN104520660A (zh) * | 2012-09-07 | 2015-04-15 | 吉宝岸外和海事技术中心私人有限公司 | 用于天然气液化的系统和方法 |
| CN110792922A (zh) * | 2018-08-01 | 2020-02-14 | 乔治洛德方法研究和开发液化空气有限公司 | 向容器加注加压气体的装置和方法 |
| CN113465210A (zh) * | 2021-06-17 | 2021-10-01 | 北京工业大学 | 一种全年冷却用空气制冷系统及其冷量调节方法 |
| KR102376279B1 (ko) * | 2020-10-30 | 2022-03-18 | 대우조선해양 주식회사 | 선박의 증발가스 재액화 시스템 및 그 운전방법 |
| CN217356480U (zh) * | 2022-05-19 | 2022-09-02 | 中海油能源发展股份有限公司采油服务分公司 | 一种bog再液化系统的变工况调节系统 |
| CN115556915A (zh) * | 2022-11-15 | 2023-01-03 | 中国船舶集团有限公司第七一一研究所 | 一种用于流体的具有可变工况调节功能的冷却系统 |
-
2022
- 2022-11-15 CN CN202211431999.6A patent/CN115556915A/zh active Pending
-
2023
- 2023-11-08 WO PCT/CN2023/130571 patent/WO2024104237A1/zh unknown
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20090127755A (ko) * | 2008-06-09 | 2009-12-14 | 삼성중공업 주식회사 | 유체 냉각 시스템 및 이를 이용한 유체 냉각 방법 |
| CN104334984A (zh) * | 2012-04-27 | 2015-02-04 | 开利公司 | 冷却系统 |
| CN104520660A (zh) * | 2012-09-07 | 2015-04-15 | 吉宝岸外和海事技术中心私人有限公司 | 用于天然气液化的系统和方法 |
| CN110792922A (zh) * | 2018-08-01 | 2020-02-14 | 乔治洛德方法研究和开发液化空气有限公司 | 向容器加注加压气体的装置和方法 |
| KR102376279B1 (ko) * | 2020-10-30 | 2022-03-18 | 대우조선해양 주식회사 | 선박의 증발가스 재액화 시스템 및 그 운전방법 |
| CN113465210A (zh) * | 2021-06-17 | 2021-10-01 | 北京工业大学 | 一种全年冷却用空气制冷系统及其冷量调节方法 |
| CN217356480U (zh) * | 2022-05-19 | 2022-09-02 | 中海油能源发展股份有限公司采油服务分公司 | 一种bog再液化系统的变工况调节系统 |
| CN115556915A (zh) * | 2022-11-15 | 2023-01-03 | 中国船舶集团有限公司第七一一研究所 | 一种用于流体的具有可变工况调节功能的冷却系统 |
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| CN115556915A (zh) | 2023-01-03 |
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