A dual-gas-source-based refrigeration and heating combined system and a control method thereof

Abstract

The application relates to a refrigeration and heating combined system based on a double air source and a control method thereof, which comprises a compressed air subsystem, a steam subsystem and a heat pump subsystem; the compressed air subsystem comprises an air compressor and a first gas-liquid separator, the air compressor is connected with the first gas-liquid separator; the steam subsystem comprises a water pump and a second gas-liquid separator, the water pump is connected with the second gas-liquid separator; the heat pump subsystem comprises a first cooler, a second cooler, a heat pump compressor and a condenser, the first gas-liquid separator is connected with the air compressor through the second cooler, the first gas-liquid separator discharges air through the first cooler, and the water pump is connected with the second gas-liquid separator through the condenser. The refrigeration and heating combined system based on the double air source and the control method thereof have the following advantages: an integrated compressed air and steam supply system is constructed, the heat pump subsystem absorbs the heat dissipation in the compressed air subsystem as the heat source of the steam subsystem, and system energy consumption can be maximally converted into effective energy.

Description

Technical Field

[0001] This invention relates to the field of energy technology, and in particular to a combined refrigeration and heating system based on dual gas sources and its control method. Background Technology

[0002] Compressed air is an important industrial gas source, widely used in industrial production fields such as chemical, textile, and shipbuilding. In industrial production, the energy consumption of compressed air systems accounts for 15% to 40% of the total energy consumption of a factory, and even higher in some heavy industries.

[0003] Steam is a crucial industrial heat source, widely used in chemical, food processing, textile, and pharmaceutical production sectors, and its applications largely overlap with compressed air systems. In most industrial facilities, both steam and compressed air systems are major energy-consuming units, with steam systems accounting for approximately 25% of total industrial energy consumption. Therefore, upgrading the technology of compressed air and steam supply devices is a key aspect of industrial energy conservation and emission reduction. Currently, with rising energy costs and stricter environmental requirements, improving the energy efficiency of steam and compressed air systems has clear practical significance for reducing enterprise operating costs and carbon emissions.

[0004] Currently, air compressor units on the market typically include an intake filter, an air compressor, a gas-liquid separator, and an aftercooler. The aftercooler cools the separated air and liquid respectively. Aftercoolers generally use air cooling to dissipate heat to the atmosphere. However, 50% to 60% of the energy consumption of an air compressor is converted into the heat energy of the liquid injected into the compressed air. The dissipation of this heat results in low energy efficiency of the compressed air supply system. Summary of the Invention

[0005] One objective of this application is to provide a combined refrigeration and heating system based on dual gas sources and its control method, which can improve energy utilization efficiency.

[0006] The technical solution adopted in this application is: a combined refrigeration and heating system based on dual gas sources, comprising:

[0007] The compressed air subsystem, used to provide compressed air, includes an air compressor and a first gas-liquid separator. The outlet of the air compressor is connected to the inlet of the first gas-liquid separator. The inlet of the air compressor is connected to the outside. The air compressor is cooled by liquid injection.

[0008] The steam subsystem, used to provide steam, includes a water pump and a second gas-liquid separator. The inlet of the water pump is connected to the outlet of the second gas-liquid separator, and the inlet of the water pump is used to supply water.

[0009] The heat pump subsystem, used to connect the compressed air subsystem and the steam subsystem, includes a first cooler, a second cooler, a heat pump compressor, and a condenser. The refrigerant outlet of the first cooler is connected to the inlet of the heat pump compressor, the refrigerant outlet of the second cooler is connected to the inlet of the heat pump compressor, the outlet of the heat pump compressor is connected to the refrigerant inlet of the condenser, and the refrigerant outlet of the condenser is connected to the refrigerant inlets of the first cooler and the second cooler, respectively.

[0010] The outlet of the first gas-liquid separator is connected to the air compressor through the second cooler. The outlet of the first gas-liquid separator discharges compressed air through the first cooler. The outlet of the water pump is connected to the inlet of the second gas-liquid separator through the condenser. The outlet of the second gas-liquid separator is used to discharge water vapor. A subcooler is provided on the connection channel between the condenser and the first cooler.

[0011] Compared with the prior art, the advantage of this application is that it constructs an integrated compressed air and steam supply system, in which the heat pump subsystem absorbs the heat dissipation of the compressed air subsystem as the heat source of the steam subsystem, which can maximize the conversion of system energy consumption into effective energy and improve energy utilization efficiency.

[0012] In some embodiments of this application, the inlet of the air compressor is connected to the outside through an air intake filter; the refrigerant inlet of the subcooler is connected to the refrigerant outlet of the condenser, the refrigerant outlet of the subcooler is connected to the refrigerant inlet of the first cooler and the refrigerant inlet of the second cooler respectively, the water outlet of the subcooler is connected to the inlet of the water pump, and the water inlet of the subcooler is used to introduce makeup water.

[0013] In some embodiments of this application, the second cooler is connected to the air compressor via a first regulating valve; the outlet of the first gas-liquid separator is connected to the first cooler via a first pressure regulating valve.

[0014] Furthermore, the subcooler is connected to the first cooler via a first expansion valve; the subcooler is connected to the second cooler via a second expansion valve; the first cooler is connected to the heat pump compressor via a first constant pressure valve; the second cooler is connected to the heat pump compressor via a second constant pressure valve; the first constant pressure valve is connected to the heat pump compressor via a first check valve; and the second constant pressure valve is connected to the heat pump compressor via a second check valve.

[0015] Furthermore, the subcooler is connected to the inlet of the water pump via a second regulating valve; the outlet of the second gas-liquid separator is equipped with a second pressure regulating valve, which is used to ensure the water vapor supply pressure; the second gas-liquid separator is equipped with a third regulating valve, which is used for liquid level control of the second gas-liquid separator.

[0016] A control method for a dual-gas-source combined refrigeration and heating system, applied to the aforementioned dual-gas-source combined refrigeration and heating system, includes: collecting the water vapor content A, and adjusting the operating frequency of the water pump according to the water vapor content A to maintain the water vapor content at 10%;

[0017] When A≥20%, the frequency of the water pump is adjusted in increments of 10Hz.

[0018] When 15% < A < 20%, the frequency of the water pump is adjusted by increasing or decreasing the frequency in increments of 5 Hz.

[0019] When 5%≤A≤15%, the frequency of the water pump is adjusted by increasing or decreasing the frequency in increments of 1Hz.

[0020] When 0 < A < 5%, the frequency of the water pump is adjusted by downgrading in increments of 5 Hz.

[0021] When A=0, the water pump operates at the lowest frequency.

[0022] In some embodiments of this application, the method includes: collecting the temperature of compressed air at the air outlet and adjusting the volumetric flow rate of the heat pump compressor based on the temperature of the compressed air.

[0023] In some embodiments of this application, the method includes: collecting the subcooling degree of the refrigerant after passing through the subcooler and the temperature of the makeup water after passing through the condenser; when the subcooling degree of the refrigerant is greater than a preset target, increasing the operating frequency of the water pump when the temperature of the makeup water is higher than a preset temperature, and decreasing the operating frequency of the water pump when the temperature of the makeup water is lower than a preset temperature; and when the subcooling degree of the refrigerant is less than a preset target, increasing the operating frequency of the water pump when the subcooling degree of the refrigerant decreases.

[0024] In some embodiments of this application, the method includes: collecting the liquid level in the second gas-liquid separator and adjusting the second and third regulating valves according to the liquid level of the second gas-liquid separator; when the liquid level of the second gas-liquid separator is higher than a preset upper limit liquid level, opening the third regulating valve to release water until the liquid level of the second gas-liquid separator returns to the target liquid level; if the liquid level cannot be restored to the target liquid level within a first set time, the machine is forcibly shut down; if the water release is too large and causes the liquid level of the second gas-liquid separator to be lower than the preset target liquid level, increasing the opening of the second regulating valve to increase the water supply flow; when the liquid level of the second gas-liquid separator is lower than a preset lower limit liquid level, increasing the opening of the second regulating valve to the maximum and triggering a low liquid level alarm; if the liquid level remains lower than the set lower limit liquid level for a second set time, the machine is forcibly shut down.

[0025] In some embodiments of this application, the method includes: collecting the exhaust temperature of the air compressor and controlling the flow rate of coolant injected into the air compressor based on the exhaust temperature of the air compressor; increasing the opening of the first regulating valve when the exhaust temperature of the air compressor is higher than the preset temperature; and decreasing the opening of the first regulating valve when the exhaust temperature of the air compressor is lower than the preset temperature. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present invention.

[0027] In the diagram: 1. Intake filter; 2. Air compressor; 3. First gas-liquid separator; 4. First cooler; 5. Second cooler; 6. Heat pump compressor; 7. Condenser; 8. Subcooler; 9. First expansion valve; 10. First constant pressure valve; 11. Second expansion valve; 12. Second constant pressure valve; 13. Water pump; 14. Second gas-liquid separator; 15. First pressure regulating valve; 16. Second pressure regulating valve; 17. First regulating valve; 18. First check valve; 19. Second check valve; 20. Second regulating valve; 21. Third regulating valve; 22. First temperature sensor; 23. Second temperature sensor; 24. Third temperature sensor; 25. Fourth temperature sensor; 26. Second liquid level sensor; 27. First liquid level sensor. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of this disclosure, the following detailed, clear, and complete description of this disclosure is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of this disclosure and are not intended to limit it.

[0029] In the description of this application, the use of "first" and "second" is for the purpose of distinguishing technical features only, and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or the order of the technical features indicated.

[0030] Those skilled in the art should understand that in the disclosure of this application, the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limitations on this application.

[0031] Example 1:

[0032] This embodiment provides a combined cooling and heating system based on dual gas sources, such as... Figure 1 As shown, it includes:

[0033] The compressed air subsystem, used to provide compressed air, includes an air compressor 2 and a first gas-liquid separator 3. The outlet of the air compressor 2 is connected to the inlet of the first gas-liquid separator 3, and the inlet of the air compressor 2 is connected to the outside. The air compressor 2 is cooled by liquid injection.

[0034] The steam subsystem, used to provide steam, includes a water pump 13 and a second gas-liquid separator 14. The inlet of the water pump 13 is connected to the outlet of the second gas-liquid separator 14. The inlet of the water pump 13 is used for makeup water. The water pump 13 is a variable frequency water pump.

[0035] The heat pump subsystem, used to connect the compressed air subsystem and the steam subsystem, includes a first cooler 4, a second cooler 5, a heat pump compressor 6, and a condenser 7. The refrigerant outlet of the first cooler 4 is connected to the inlet of the heat pump compressor 6, the refrigerant outlet of the second cooler 5 is connected to the inlet of the heat pump compressor 6, the outlet of the heat pump compressor 6 is connected to the refrigerant inlet of the condenser 7, and the refrigerant outlet of the condenser 7 is connected to the refrigerant inlets of the first cooler 4 and the second cooler 5, respectively.

[0036] The liquid outlet of the first gas-liquid separator 3 is connected to the air compressor 2 through the second cooler 5, and the air outlet of the first gas-liquid separator 3 discharges compressed air through the first cooler 4. The outlet of the water pump 13 is connected to the inlet of the second gas-liquid separator 14 through the condenser 7, and the air outlet of the second gas-liquid separator 14 is used to discharge water vapor.

[0037] The heat pump subsystem also includes a subcooler 8, the refrigerant inlet of the subcooler 8 is connected to the refrigerant outlet of the condenser 7, the refrigerant outlet of the subcooler 8 is connected to the refrigerant inlet of the first cooler 4 and the refrigerant inlet of the second cooler 5 respectively, the water outlet of the subcooler 8 is connected to the inlet of the water pump 13, and the water inlet of the subcooler 8 is used to introduce makeup water. Figure 1 In the diagram, A represents compressed air, B represents makeup water, and C represents water vapor.

[0038] Air compressor 2 draws in ambient air, which is then compressed, heated, and pressurized. During the compression process, air compressor 2 requires liquid cooling. For conventional air compressor 2, oil cooling can be used, while for oil-free air compressors, water cooling can be used. The gas-liquid mixture discharged from air compressor 2 enters the first gas-liquid separator 3 for gas-liquid separation. The separated air is cooled by the first cooler 4 before being supplied to the outside, and the separated liquid is cooled by the second cooler 5 before being injected into air compressor 2 for cooling.

[0039] The heat pump compressor 6 is used to provide the driving force for the refrigerant in the pipeline. The high-temperature refrigerant gas discharged from the heat pump compressor 6 will first pass through the condenser 7 to release heat and condense. Then it will be divided into two paths. One path goes to the first cooler 4 to evaporate and absorb the heat of the compressed air, and the other path goes to the second cooler 5 to evaporate and absorb the heat of the liquid separated by the first gas-liquid separator 3. Then they will both flow into the suction port of the heat pump compressor 6, be compressed and heated to start the next thermodynamic cycle.

[0040] The inlet of water pump 13 is connected to the external makeup water. After water pump 13 draws makeup water, it is pumped into condenser 7, so that the makeup water absorbs the heat of the refrigerant and evaporates into water vapor. Then it enters the second gas-liquid separator 14 for gas-liquid separation. The unevaporated hot water separated from the water pump is combined with the initial makeup water and enters water pump 13. It is then pumped into condenser 7 to continue to be heated and evaporated. The separated water vapor is supplied to the outside.

[0041] The subcooler 8 is designed to allow the low-temperature makeup water to absorb heat from the refrigerant and increase its temperature, thereby raising the temperature of the makeup water and lowering the temperature of the refrigerant. The makeup water that has passed through the subcooler 8 is then combined with the unevaporated hot water separated by the second gas-liquid separator 14. After mixing, they are pumped into the condenser 7 to continue to be heated and evaporated.

[0042] This application constructs an integrated compressed air and steam supply system, in which the heat pump subsystem absorbs the heat dissipation of the compressed air subsystem as the heat source of the steam subsystem, which can maximize the conversion of system energy consumption into effective energy and improve energy utilization efficiency.

[0043] To improve the quality of compressed air, the inlet of the air compressor 2 is connected to the outside environment through an intake filter 1. The intake filter 1 filters impurities from the ambient air entering the air compressor 2, improving the quality of the incoming air and thus the quality of the subsequently discharged compressed air. It also reduces the impact of impurities and improves operational stability.

[0044] To ensure stable liquid cooling of the air compressor 2, the second cooler 5 is connected to the air compressor 2 via the first regulating valve 17; the outlet of the first gas-liquid separator 3 is connected to the first cooler 4 via the first pressure regulating valve 15. The design of the first regulating valve 17 can adjust the flow rate of coolant into the air compressor 2, facilitating control of the cooling effect on the air compressor 2; the design of the first pressure regulating valve 15 can ensure a stable air supply pressure.

[0045] To ensure stable refrigerant flow, the subcooler 8 is connected to the first cooler 4 via a first expansion valve 9; the subcooler 8 is connected to the second cooler 5 via a second expansion valve 11; the first cooler 4 is connected to the heat pump compressor 6 via a first constant pressure valve 10; the second cooler 5 is connected to the heat pump compressor 6 via a second constant pressure valve 12; the first constant pressure valve 10 is connected to the heat pump compressor 6 via a first one-way valve 18; and the second constant pressure valve 12 is connected to the heat pump compressor 6 via a second one-way valve 19. The first expansion valve 9 is used to throttle and reduce the pressure of the refrigerant entering the first cooler 4, and the second expansion valve 11 is used to throttle and reduce the pressure of the refrigerant entering the second cooler 5, ensuring the heat absorption and cooling effect of the refrigerant in the pipeline; the first constant pressure valve 10 and the second constant pressure valve 12 are used to stabilize the evaporation pressure and temperature to ensure that the cooled air and liquid reach the target temperature; the first one-way valve 18 and the second one-way valve 19 are used to ensure that the refrigerant can complete the circulation.

[0046] To ensure a stable supply of makeup water, the subcooler 8 is connected to the inlet of the water pump 13 via a second regulating valve 20, which adjusts the flow rate of makeup water into the pump 13. A second pressure regulating valve 16 is installed at the outlet of the second gas-liquid separator 14 to ensure the steam supply pressure. A third regulating valve 21 is located at the bottom of the second gas-liquid separator 14 for level control. When the system starts, the second regulating valve 20 can be closed, allowing the water in the second gas-liquid separator 14 to circulate and heat in the condenser 7 until steam is generated. Then, the second regulating valve 20 can be opened to control the makeup water supply.

[0047] To ensure stable system operation, the air compressor 2 is equipped with a first temperature sensor 22 at its outlet, which is electrically connected to a first regulating valve 17. The first temperature sensor 22 can collect the exhaust temperature, transmit the signal to the main controller for processing, and control the flow rate of coolant injected into the air compressor 2 based on the exhaust temperature, that is, adjust the opening of the first regulating valve 17. When the temperature rises, the opening of the first regulating valve 17 is increased, thus increasing the coolant flow rate; when the temperature falls, the opening of the first regulating valve 17 is decreased, thus decreasing the coolant flow rate.

[0048] To ensure stable system operation, a second temperature sensor 23 is installed at the air outlet of the first cooler 4, and the second temperature sensor 23 is electrically connected to the heat pump compressor 6. The second temperature sensor 23 can collect the temperature of the compressed air at the air outlet, transmit the signal to the main controller for processing, and adjust the volumetric flow rate of the heat pump compressor 6 according to the temperature of the compressed air, so that the cooling capacity provided by the heat pump compressor 6 matches the air cooling load demand. The volumetric flow rate adjustment method of the heat pump compressor 6 can be frequency conversion, or other available methods can be adopted according to the characteristics of the compressor model.

[0049] To ensure stable system operation, a third temperature sensor 24 is installed at the refrigerant outlet of the subcooler 8, and a fourth temperature sensor 25 is installed at the water outlet of the condenser 7. Both the third and fourth temperature sensors 24 and 25 are electrically connected to the water pump 13. The third temperature sensor 24 can collect the temperature of the refrigerant after passing through the subcooler 8, and the fourth temperature sensor 25 can collect the temperature of the makeup water after passing through the condenser 7. The signals from both sensors are transmitted to the main controller for processing, which together controls the operating frequency of the water pump 13, i.e., controls the makeup water flow rate. The temperature collected by the third temperature sensor 24 can be used to calculate the degree of refrigerant subcooling.

[0050] When the refrigerant subcooling of the subcooler 8 is greater than the preset target, the operating frequency of the water pump 13 is controlled by the temperature collected by the fourth temperature sensor 25, as follows: when the outlet temperature of the condenser 7 is higher than the preset temperature, the operating frequency of the water pump 13 is increased and the water flow rate is increased; otherwise, the water flow rate is reduced, so as to ensure that the heated makeup water in the condenser 7 can partially evaporate to generate water vapor.

[0051] When the refrigerant subcooling of the subcooler 8 is less than the preset target, the operating frequency of the water pump 13 is controlled by the temperature collected by the third temperature sensor 24, as follows: when the refrigerant subcooling of the subcooler 8 decreases, the operating frequency of the water pump 13 is increased, and the water flow into the condenser 7 is increased to ensure that the compressed refrigerant gas can be completely liquefied and has the subcooling required to meet the design requirements. That is, the supply of compressed air that meets the requirements takes priority over the supply of water vapor.

[0052] The change in the operating frequency of water pump 13 mainly affects the flow rate of the hot water that continues to be heated out of the second gas-liquid separator 14. The third temperature sensor 24 is used to determine whether the refrigerant liquid has subcooling. Only when the subcooling meets the requirements can the cooling of the compressed air subsystem be ensured. The temperature data of the third temperature sensor 24 controls the frequency conversion of water pump 13. As the frequency of water pump 13 increases, the liquid level in the second gas-liquid separator 14 will decrease. Then, the liquid level data of the second liquid level sensor 26 controls the opening of the second regulating valve 20, indirectly increasing the makeup water flow rate. After the low-temperature makeup water flow rate increases, the amount of water heated and evaporated in the condenser 7 will decrease, and the liquid level in the second gas-liquid separator 14 will increase, thus affecting the control of the makeup water.

[0053] Therefore, in order to ensure the stable operation of the system, the second gas-liquid separator 14 is equipped with a second liquid level sensor 26 and a third regulating valve 21. The second liquid level sensor 26 is electrically connected to the second regulating valve 20 and the third regulating valve 21 respectively. The second liquid level sensor 26 can collect the liquid level height in the second gas-liquid separator 14, transmit the signal to the main controller for processing, and adjust the second regulating valve 20 and the third regulating valve 21 according to the liquid level of the second gas-liquid separator 14. When the liquid level of the second gas-liquid separator 14 is higher than the preset upper limit liquid level, the third regulating valve 21 is opened to release water until the liquid level of the second gas-liquid separator 14 returns to the target liquid level. If it cannot return to the target liquid level within the first set time, the machine is forcibly shut down. If the water discharge is too large and causes the liquid level of the second gas-liquid separator 14 to be lower than the preset target liquid level, the opening of the second regulating valve 20 is increased to increase the water supply flow. When the liquid level of the second gas-liquid separator 14 is lower than the preset lower limit liquid level, the opening of the second regulating valve 20 is increased to the maximum and a low liquid level alarm is triggered. If the liquid level continues to be lower than the set lower limit liquid level for a second set time, the machine is forcibly shut down.

[0054] Liquid level control is necessary to coordinate the operation of the heat pump subsystem and the steam subsystem. When the third temperature sensor 24 controls the frequency of the water pump 13, a low liquid level may occur in the second gas-liquid separator 14. In this case, the water supply must be increased to ensure refrigerant gas condensation. Because the supply water temperature is low, the inlet water temperature of the condenser 7 is also low, causing the heated water to not evaporate and thus preventing steam supply. The liquid level in the second gas-liquid separator 14 will rise rapidly. Therefore, drainage control must be implemented to stabilize system operation and continuously output compressed air to meet requirements. Steam is a product of the heat pump subsystem recovering heat from the air subsystem; therefore, compressed air supply takes precedence over steam supply.

[0055] To ensure the stable operation of the system, the first gas-liquid separator 3 is equipped with a first liquid level sensor 27. The first liquid level sensor 27 can collect the liquid level height in the first gas-liquid separator 3. When the liquid level is too low, it can be fed back to the main controller to perform a liquid level alarm and emergency shutdown.

[0056] It also includes a main controller. The signals collected by the first temperature sensor 22, the second temperature sensor 23, the third temperature sensor 24, the second liquid level sensor 26, and the first liquid level sensor 27 are all transmitted to the main controller for processing, and then the main controller sends signals to each valve, compressor, and water pump 13.

[0057] Example 2:

[0058] This embodiment provides a control method for a dual-gas-source combined refrigeration and heating system, applied to a dual-gas-source combined refrigeration and heating system as described in Embodiment 1. The method includes: collecting the water vapor content A (the water vapor content A is the mass ratio of gas in the gas discharged from the outlet of the second gas-liquid separator 14), and adjusting the operating frequency of the water pump 13 according to the water vapor content A to maintain the water vapor content A at 10%.

[0059] When A≥20%, the frequency of water pump 13 is adjusted in increments of 10Hz to increase the amount of low-temperature makeup water entering the condenser 7, thereby reducing the temperature of the water flow and the amount of steam generated. Without reducing the gas content, the operating frequency of water pump 13 can be continuously increased until it reaches the highest frequency.

[0060] When 15% < A < 20%, the frequency of water pump 13 is adjusted by increasing or decreasing the frequency in increments of 5 Hz. When the gas content A increases, the frequency of water pump 13 is increased by increments of 5 Hz to reduce the temperature of the water entering condenser 7, thereby reducing the amount of steam generated. When the gas content A decreases, the frequency of water pump 13 is decreased by increments of 5 Hz to facilitate control when the gas content A decreases to the next range.

[0061] When 5% ≤ A ≤ 15%, the frequency of water pump 13 is adjusted by increasing or decreasing in 1Hz increments. When 5% ≤ A < 10% and the gas content A decreases, the frequency of water pump 13 is decreased in 1Hz increments to reduce the amount of low-temperature makeup water entering, thereby increasing the temperature of the water flowing into condenser 7 and thus increasing the steam production. When 5% ≤ A < 10% and the gas content A increases, the frequency of water pump 13 is increased in 1Hz increments, so that as it approaches 10%, the increase in water content in the steam gradually decreases, and the gas content A can more stably reach 10%. When 10% < A ≤ 15% and the gas content A decreases... In the normal state, the frequency of water pump 13 is reduced in 1Hz increments, so that when it approaches 10%, the reduction of water in the steam will gradually decrease, and the gas content A can more stably reach 10%. When 10% < A ≤ 15% and the gas content A is increasing, the frequency of water pump 13 is increased in 1Hz increments, increasing the amount of low-temperature makeup water entering, reducing the temperature of the water entering condenser 7, and thus reducing the amount of steam generated. Fine-tuning in 1Hz increments provides high precision control over the gas content and prevents fluctuations in the gas content. The frequency adjustment also makes the rate of change of the gas content A slower and more stable as it approaches 10%.

[0062] When 0 < A < 5%, the frequency of water pump 13 is adjusted in 5Hz increments to reduce the amount of low-temperature makeup water entering, thereby increasing the temperature of the water entering condenser 7 and thus increasing the amount of steam generated.

[0063] When A=0, water pump 13 operates at the lowest frequency, minimizing the inflow of low-temperature makeup water, allowing the water flow in the pipeline to quickly generate steam within the condenser 7. The lowest frequency of water pump 13 meets the heat exchange requirements of the condenser 7.

[0064] The adjustment interval between each gear increase or decrease in the operating frequency of the above-mentioned water pump 13 is 10ms.

[0065] In this embodiment, a first mass flow meter is installed at the outlet of the second gas-liquid separator 14. The first mass flow meter is used to collect the steam mass flow rate B. A second mass flow meter is installed on the channel between the subcooler 8 and the external makeup water. The second mass flow meter is used to collect the inlet mass flow rate C. The gas content A = steam mass flow rate B / inlet mass flow rate C * 100%, thereby obtaining the water vapor content A. The first and second mass flow meters are E+H mass flow meters, model 8F3B80.

[0066] In order to control the exhaust temperature, the system collects the exhaust temperature of the air compressor 2 and controls the flow rate of the coolant injected into the air compressor 2 based on the exhaust temperature of the air compressor 2. When the exhaust temperature of the air compressor 2 increases relative to the preset temperature, the opening of the first regulating valve 17 is increased. When the exhaust temperature of the air compressor 2 decreases relative to the preset temperature, the opening of the first regulating valve 17 is decreased.

[0067] When the exhaust temperature minus the preset temperature is greater than 10°C, the first regulating valve 17 remains at its maximum opening. If the exhaust temperature continues to rise, a high temperature alarm will be issued and the shutdown will be delayed.

[0068] When -10℃ ≤ exhaust temperature - preset temperature ≤ 10℃, the opening of the first regulating valve 17 increases or decreases by one level each time; that is, when the temperature difference between the exhaust temperature and the preset temperature is within 10℃, it increases or decreases once per minute. When -10℃ ≤ exhaust temperature - preset temperature < 0℃ and the temperature difference increases, the first regulating valve 17 decreases by one level per minute until the first regulating valve 17 maintains the lowest opening. When 0℃ < exhaust temperature - preset temperature ≤ 10℃ and the temperature difference increases, the first regulating valve 17 increases by one level per minute until the first regulating valve 17 maintains the maximum opening.

[0069] When the exhaust temperature minus the preset temperature is less than -10℃, the first regulating valve 17 maintains the lowest opening and injects the lowest flow rate into the compressor without adjusting the flow rate.

[0070] In this embodiment, the outlet of the air compressor 2 is provided with a first temperature sensor 22, which is used to collect the exhaust temperature of the air compressor 2. The second cooler 5 is connected to the air compressor 2 through the first regulating valve 17, and the first temperature sensor 22 is electrically connected to the first regulating valve 17. The preset exhaust temperature of the air compressor 2 is 70°C, and the opening degree of the first regulating valve 17 is divided into ten levels from closed to maximum opening.

[0071] To control the heat exchange effect, the compressed air temperature at the air outlet is collected, and the volumetric flow rate of the heat pump compressor 6 is adjusted according to the compressed air temperature, so that the cooling capacity provided by the heat pump compressor 6 matches the air cooling load demand. The volumetric flow rate adjustment method of the heat pump compressor 6 can be frequency conversion, or other available methods can be adopted according to the characteristics of the compressor model.

[0072] In other words, when the temperature of the compressed air at the air outlet increases relative to the preset temperature, the operating frequency of the heat pump compressor 6 is increased, which increases the cooling capacity. When the temperature of the compressed air at the air outlet decreases relative to the preset temperature, the operating frequency of the heat pump compressor 6 is decreased, which decreases the cooling capacity.

[0073] In this embodiment, the preset temperature of compressed air is 70°C, and the operating frequency of the heat pump compressor 6 is divided into six levels from zero to the maximum frequency.

[0074] When the compressed air temperature is >70℃, the operating frequency of the heat pump compressor 6 increases by one level per minute until the heat pump compressor 6 operates at the maximum frequency or the compressed air temperature returns to 70℃.

[0075] When the compressed air temperature is less than 70°C, the operating frequency of the heat pump compressor 6 decreases by one level per minute until the heat pump compressor 6 stops operating.

[0076] In this embodiment, the air outlet of the first cooler 4 is provided with a second temperature sensor 23, which can collect the temperature of the compressed air at the air outlet. The second temperature sensor 23 is electrically connected to the heat pump compressor 6.

[0077] To control the evaporation effect, the subcooling degree of the refrigerant after passing through the subcooler 8 and the temperature of the makeup water after passing through the condenser 7 are collected. When the subcooling degree of the refrigerant is greater than the preset target, the operating frequency of the water pump 13 is controlled by the temperature collected by the fourth temperature sensor 25. When the temperature of the makeup water is higher than the preset temperature, the operating frequency of the water pump 13 is increased, and when the temperature of the makeup water is lower than the preset temperature, the operating frequency of the water pump 13 is decreased. When the subcooling degree of the refrigerant is less than the preset target, the operating frequency of the water pump 13 is increased when the subcooling degree of the refrigerant decreases.

[0078] In this embodiment, the subcooling of the refrigerant is preset to 10°C, the preset temperature of the makeup water is 105°C, and the operating frequency of the water pump 13 is divided into six levels from zero to the maximum frequency.

[0079] When the refrigerant subcooling is greater than 10°C,

[0080] When the temperature of the makeup water is >105℃, the operating frequency of water pump 13 will be increased in increments of 5Hz per second.

[0081] When the temperature of the makeup water is <105℃, the operating frequency of water pump 13 will be reduced in increments of 5Hz per second.

[0082] When the refrigerant subcooling is <10℃,

[0083] When the refrigerant subcooling is less than 10°C, the operating frequency of water pump 13 increases by 5 Hz per second.

[0084] In this embodiment, the refrigerant outlet of the subcooler 8 is equipped with a third temperature sensor 24, and the water outlet of the condenser 7 is equipped with a fourth temperature sensor 25. Both the third temperature sensor 24 and the fourth temperature sensor 25 are electrically connected to the water pump 13. The third temperature sensor 24 is used to collect the temperature of the refrigerant after passing through the subcooler 8, and the fourth temperature sensor 25 is used to collect the temperature of the makeup water after passing through the condenser 7. The subcooling degree of the refrigerant can be calculated from the temperature collected by the third temperature sensor 24. The formula is: subcooling degree of refrigerant = freezing point temperature of refrigerant - actual temperature of refrigerant. This calculation can be completed by the main controller.

[0085] To ensure stable operation of the second gas-liquid separator 14, the system collects the liquid level within the separator and adjusts the second regulating valve 20 and the third regulating valve 21 based on this level. When the liquid level in the second gas-liquid separator 14 exceeds a preset upper limit, the third regulating valve 21 is opened to release water until the liquid level returns to the target level. If the liquid level cannot be restored to the target level within a first set time, the system is forcibly shut down. If excessive water release causes the liquid level in the second gas-liquid separator 14 to fall below the preset target level, the opening of the second regulating valve 20 is increased to increase the water supply flow. When the liquid level in the second gas-liquid separator 14 falls below a preset lower limit, the opening of the second regulating valve 20 is increased to its maximum, and a low liquid level alarm is triggered. If the liquid level remains below the set lower limit for a second set time, the system is forcibly shut down.

[0086] In this embodiment, the preset upper limit liquid level of the second gas-liquid separator 14 is 2 / 3 of the total height of the container, the preset target liquid level of the second gas-liquid separator 14 is 1 / 2 of the total height of the container, the first setting time is 60s, the preset lower limit liquid level of the second gas-liquid separator 14 is 1 / 3 of the total height of the container, the second setting time is 60s, and the opening degree of the second regulating valve 20 is divided into ten levels from closed to maximum opening.

[0087] When the liquid level of the second gas-liquid separator 14 is higher than 2 / 3 of the total height of the container, the third regulating valve 21 keeps the maximum opening to discharge water until the liquid level of the second gas-liquid separator 14 returns to the target liquid level. If it cannot return to the target liquid level within 60 seconds, it will be forcibly shut down.

[0088] If the liquid level of the second gas-liquid separator 14 is lower than 1 / 2 of the total height of the container, the opening of the second regulating valve 20 increases by one level every 10 seconds until the liquid level of the second gas-liquid separator 14 returns to the target liquid level.

[0089] When the liquid level in the second gas-liquid separator 14 is lower than 1 / 3 of the total height of the container, the second regulating valve 20 keeps the water inlet at its maximum opening and issues a low liquid level alarm. If the liquid level remains lower than 1 / 3 of the total height of the container for 60 seconds, the machine is forcibly shut down.

[0090] In this embodiment, the second gas-liquid separator 14 is provided with a second liquid level sensor 26, the subcooler 8 is connected to the inlet of the water pump 13 through the second regulating valve 20, the second gas-liquid separator 14 is provided with a third regulating valve 21, and the second liquid level sensor 26 is electrically connected to the second regulating valve 20 and the third regulating valve 21 respectively.

[0091] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A combined refrigeration and heating system based on dual gas sources, characterized in that, include: The compressed air subsystem, used to provide compressed air, includes an air compressor (2) and a first gas-liquid separator (3), the outlet of the air compressor (2) is connected to the inlet of the first gas-liquid separator (3), and the air compressor (2) is cooled by liquid injection. A steam subsystem for providing steam includes a water pump (13) and a second gas-liquid separator (14), the inlet of which is connected to the outlet of the second gas-liquid separator (14); The heat pump subsystem, used to connect the compressed air subsystem and the steam subsystem, includes a first cooler (4), a second cooler (5), a heat pump compressor (6), and a condenser (7). The refrigerant outlet of the first cooler (4) is connected to the inlet of the heat pump compressor (6), the refrigerant outlet of the second cooler (5) is connected to the inlet of the heat pump compressor (6), the outlet of the heat pump compressor (6) is connected to the refrigerant inlet of the condenser (7), and the refrigerant outlet of the condenser (7) is connected to the refrigerant inlet of the first cooler (4) and the refrigerant inlet of the second cooler (5), respectively. The outlet of the first gas-liquid separator (3) is connected to the air compressor (2) through the second cooler (5), and the outlet of the first gas-liquid separator (3) discharges compressed air through the first cooler (4). The outlet of the water pump (13) is connected to the inlet of the second gas-liquid separator (14) through the condenser (7). A subcooler (8) is provided on the connection channel between the condenser (7) and the first cooler (4).

2. The combined refrigeration and heating system based on dual gas sources according to claim 1, characterized in that, The air compressor (2) is connected to the outside through the intake filter (1); the refrigerant inlet of the subcooler (8) is connected to the refrigerant outlet of the condenser (7); the refrigerant outlet of the subcooler (8) is connected to the refrigerant inlet of the first cooler (4) and the refrigerant inlet of the second cooler (5); the outlet of the subcooler (8) is connected to the inlet of the water pump (13); and the inlet of the subcooler (8) is used to introduce makeup water.

3. The combined refrigeration and heating system based on dual gas sources according to claim 1, characterized in that, The second cooler (5) is connected to the air compressor (2) through the first regulating valve (17); the outlet of the first gas-liquid separator (3) is connected to the first cooler (4) through the first pressure regulating valve (15).

4. A combined refrigeration and heating system based on dual gas sources according to claim 2, characterized in that, The subcooler (8) is connected to the first cooler (4) via the first expansion valve (9); the subcooler (8) is connected to the second cooler (5) via the second expansion valve (11); the first cooler (4) is connected to the heat pump compressor (6) via the first constant pressure valve (10); the second cooler (5) is connected to the heat pump compressor (6) via the second constant pressure valve (12); the first constant pressure valve (10) is connected to the heat pump compressor (6) via the first check valve (18); and the second constant pressure valve (12) is connected to the heat pump compressor (6) via the second check valve (19).

5. A combined refrigeration and heating system based on dual gas sources according to claim 2, characterized in that, The subcooler (8) is connected to the inlet of the water pump (13) through the second regulating valve (20); the outlet of the second gas-liquid separator (14) is provided with a second pressure regulating valve (16), which is used to ensure the supply pressure of water vapor; the second gas-liquid separator (14) is provided with a third regulating valve (21), which is used for the liquid level control of the second gas-liquid separator (14).

6. A control method for a combined refrigeration and heating system based on dual gas sources, characterized in that, The system is applied to a dual-gas-source combined cooling and heating system as described in any one of claims 1-5, comprising: collecting the vapor content A of water vapor, and adjusting the operating frequency of the water pump (13) according to the vapor content A to maintain the vapor content at 10%; When A≥20%, the frequency of the water pump (13) is adjusted in increments of 10Hz. When 15% < A < 20%, the frequency of the water pump (13) is adjusted by increasing or decreasing the frequency in increments of 5Hz. When 5%≤A≤15%, the frequency of the water pump (13) is adjusted by increasing or decreasing the frequency in increments of 1Hz. When 0 < A < 5%, the frequency of the water pump (13) is adjusted by downgrading in increments of 5 Hz. When A=0, the water pump (13) operates at the lowest frequency.

7. The control method for a combined refrigeration and heating system based on dual gas sources according to claim 6, characterized in that, include: The compressed air temperature at the air outlet is collected, and the volumetric flow rate of the heat pump compressor (6) is adjusted according to the compressed air temperature.

8. The control method for a combined refrigeration and heating system based on dual gas sources according to claim 6, characterized in that, include: The subcooling degree of the refrigerant after passing through the subcooler (8) and the temperature of the makeup water after passing through the condenser (7) are collected. When the subcooling degree of the refrigerant is greater than the preset target, the operating frequency of the water pump (13) is increased when the temperature of the makeup water is higher than the preset temperature. When the temperature of the makeup water is lower than the preset temperature, the operating frequency of the water pump (13) is decreased. When the subcooling degree of the refrigerant is less than the preset target, the operating frequency of the water pump (13) is increased when the subcooling degree of the refrigerant decreases.

9. The control method for a combined refrigeration and heating system based on dual gas sources according to claim 6, characterized in that, include: The liquid level in the second gas-liquid separator (14) is collected, and the second regulating valve (20) and the third regulating valve (21) are adjusted according to the liquid level of the second gas-liquid separator (14). When the liquid level of the second gas-liquid separator (14) is higher than the preset upper limit liquid level, the third regulating valve (21) is opened to release water until the liquid level of the second gas-liquid separator (14) returns to the target liquid level. If the liquid level cannot be restored to the target liquid level within the first set time, the machine is forcibly shut down. If the water discharge is too large and the liquid level of the second gas-liquid separator (14) is lower than the preset target liquid level, the opening of the second regulating valve (20) is increased to increase the water supply flow. When the liquid level of the second gas-liquid separator (14) is lower than the preset lower limit liquid level, the opening of the second regulating valve (20) is increased to the maximum and a low liquid level alarm is triggered. If the liquid level continues to be lower than the set lower limit liquid level for the second set time, the machine is forcibly shut down.

10. The control method for a combined refrigeration and heating system based on dual gas sources according to claim 6, characterized in that, include: The exhaust temperature of the air compressor (2) is collected, and the flow rate of the coolant injected into the air compressor (2) is controlled according to the exhaust temperature of the air compressor (2). When the exhaust temperature of the air compressor (2) increases relative to the preset temperature, the opening of the first regulating valve (17) is increased. When the exhaust temperature of the air compressor (2) decreases relative to the preset temperature, the opening of the first regulating valve (17) is decreased.

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