A high-temperature CO2 heat pump steam generation system for use in the brewing industry and its working method

Abstract

The application belongs to the technical field of heat pump and industrial heating, and discloses a high-temperature CO2 heat pump steam generation system applied to the brewing industry and a working method thereof, so as to solve the technical defects of the existing cold-heat coupling waste heat utilization system, such as complex equipment and low energy efficiency. In the technical scheme of the application, a transcritical CO2 heat pump is taken as the core, and three subsystems of CO2 transcritical cycle, steam preparation at the heating end and cooling water circulation at the cooling end are integrated. The gas cooler is used to heat and pressurize water, and the throttling flash evaporation is used to prepare saturated steam to supply the wine retort. The evaporator is used to prepare low-temperature cooling water to meet the cooling demand, and a cold storage tank and a water mixing tank are matched to realize cold energy regulation and storage and accurate temperature regulation and control. In addition, a multi-parameter correlation model is constructed, and a multi-loop PID collaborative control is adopted to dynamically track the global optimal operating parameters. The application has the characteristics of high integration and excellent waste heat recovery efficiency, and can effectively improve the energy utilization efficiency and reduce the initial investment and operation and maintenance costs.

Description

Technical Field

[0001] This invention belongs to the field of heat pump and industrial heating technology, specifically relating to a high-temperature CO2 heat pump steam generation system and its working method applied in the brewing industry. Background Technology

[0002] In the production process of baijiu (Chinese liquor), the distillation process requires a large amount of low-pressure saturated steam to achieve the distillation of the liquor. The condensation process of the liquor steam generates cooling water carrying a large amount of medium and low temperature waste heat. In the traditional production mode, this waste heat resource is usually directly discharged, resulting in serious energy waste. At the same time, the baijiu brewing process also has a low-temperature cooling requirement for the liquor steam condensation stage, and there is a significant mismatch between the waste heat produced by each process stage and the energy demand for production. How to achieve efficient waste heat recovery and coordinated supply of cooling and heat has become a core issue that urgently needs to be addressed in the field of energy conservation and consumption reduction in the baijiu brewing industry.

[0003] Specifically, the existing conventional waste heat utilization system in the liquor industry mainly consists of a steam generating heat pump unit, a steam compressor unit, a hot water type lithium bromide refrigeration unit, and a cooling tower. Its working process is as follows: cold water enters the steam generating heat pump unit to absorb heat and generate steam, which is then compressed into saturated steam at 0.2-0.5 MPa by the steam compressor. The steam is then distilled in the still to produce liquor vapor, which is then condensed in an ice tank to become raw liquor. The high-temperature ice tank water generated after the liquor vapor is condensed in the ice tank drives the lithium bromide refrigeration cycle. The water is first cooled by the generator of the lithium bromide refrigeration unit and then used as a low-temperature heat source for the steam heat pump unit. The low-temperature ice tank water is then produced by the evaporator of the lithium bromide refrigeration unit and sent back to the ice tank. The cooling water circuit of the lithium bromide refrigeration unit discharges the waste heat of the refrigeration cycle into the environment through the intermediate plate heat exchanger and the cooling tower.

[0004] The aforementioned conventional cold and heat coupled waste heat comprehensive utilization system still has many technical defects in practical engineering applications, making it difficult to meet the industry's development needs for high efficiency and energy conservation. These defects include: the three sets of equipment are complex in composition, have low integration, are difficult to operate and maintain, and have high initial investment costs; there are many energy conversion stages, resulting in low system energy efficiency, as the system needs to go through multiple energy conversion processes such as heat exchange, compression, and phase change, and each stage of the conversion process involves irreversible energy loss, leading to low system operating efficiency; the waste heat grade matching is poor, resulting in insufficient resource utilization; the ability to coordinate and regulate cold and heat loads is weak, and the flexibility of adapting to operating conditions is insufficient. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature CO2 heat pump steam generation system and its operating method for the brewing industry, in order to solve the technical problems of existing conventional waste heat utilization systems in the liquor brewing industry, such as complex configuration, high initial investment cost, mismatched waste heat grades, and low energy utilization efficiency. This invention constructs a combined cooling and heating architecture with a transcritical CO2 heat pump as its core. Low-grade waste heat is directly recovered on the gas cooler side to heat pressurized water to the flash evaporation temperature range to produce saturated steam. Simultaneously, low-temperature cooling water is produced on the evaporator side to meet cooling needs. This reduces irreversible losses in multi-stage heat exchange and steam compression, thereby solving the technical problems of multiple energy conversion stages and low operating efficiency in existing systems, and achieving efficient cascaded utilization of energy.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, this invention provides a high-temperature CO2 heat pump steam generation system for use in the brewing industry, comprising: a CO2 transcritical cycle heat pump subsystem, a steam preparation subsystem at the heating end, and a cooling water circulation subsystem at the cooling end; wherein, The CO2 transcritical cycle heat pump subsystem includes: a compressor, a gas cooler, a CO2-side regenerator, a CO2-side throttling valve, an evaporator, a fourth three-way valve, a fifth three-way valve, and a regenerator bypass valve; wherein, the outlet of the compressor is connected to the inlet of the fourth three-way valve via the CO2-side channel of the gas cooler, the high-temperature CO2-side channel of the CO2-side regenerator, the CO2-side throttling valve, and the CO2-side channel of the evaporator; the first outlet of the fourth three-way valve is connected to the first inlet of the fifth three-way valve via the low-temperature CO2-side channel of the CO2-side regenerator; the second outlet of the fourth three-way valve is connected to the second inlet of the fifth three-way valve via the regenerator bypass valve; and the outlet of the fifth three-way valve is connected to the inlet of the compressor. The steam preparation subsystem at the heating end includes: a water supply pump, a water supply regulating valve, a first three-way valve, a pressurizing pump, the gas cooler, a water-side throttling valve, a flash evaporator, a still, and a cooler; wherein, the outlet of the water supply pump is connected to the first inlet of the first three-way valve via the water supply regulating valve, the saturated water outlet of the flash evaporator is connected to the second inlet of the first three-way valve, the outlet of the first three-way valve is connected to the inlet of the flash evaporator via the pressurizing pump, the water-side channel of the gas cooler, and the water-side throttling valve, and the saturated steam outlet of the flash evaporator is connected to the steam-side inlet of the cooler via the steam channel of the still; The cooling water circulation subsystem at the cooling end includes: the evaporator, the cooling water circulation pump, the third three-way valve, the cold storage tank, the low-temperature cooling water inlet regulating valve, the mixing tank, the cooler, the second three-way valve, and the high-temperature cooling water inlet regulating valve; wherein, the outlet of the mixing tank is connected to the inlet of the second three-way valve via the cooling water side channel of the cooler, the first outlet of the second three-way valve is connected to the high-temperature cooling water inlet of the mixing tank via the high-temperature cooling water inlet regulating valve, the second outlet of the second three-way valve is connected to the inlet of the third three-way valve via the cooling water side channel of the evaporator and the cooling water circulation pump, the first outlet of the third three-way valve is connected to the chilled water supply port, and the second outlet of the third three-way valve is connected to the low-temperature cooling water inlet of the mixing tank via the cold storage tank and the low-temperature cooling water inlet regulating valve, and the mixing tank is also provided with a chilled water return inlet.

[0007] A further improvement of the technical solution of the present invention is that it also includes: a compressor discharge pressure PID control module, used to control the compressor speed according to the optimal compressor discharge pressure correlation; The optimal compressor discharge pressure correlation is as follows: ; In the formula, The optimal compressor discharge pressure; This refers to the compressor suction temperature. This refers to the compressor discharge temperature. This refers to the compressor's suction pressure. This is the saturated steam output pressure; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0008] A further improvement of the technical solution of the present invention is that it also includes: a compressor exhaust temperature PID control module, used to control the opening degree of the regenerator bypass valve according to the optimal compressor exhaust temperature correlation. The optimal compressor discharge temperature correlation is as follows: ; In the formula, To achieve the optimal compressor discharge temperature; This refers to the outlet temperature of the water-side channel of the gas cooler. The temperature of the CO2 working fluid after reheating; The CO2 working fluid flow rate passing through the regenerator bypass valve; This refers to the CO2 side outlet temperature of the evaporator. This refers to the compressor's discharge pressure. This refers to the compressor's suction pressure. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0009] A further improvement of the technical solution of the present invention is that it also includes: a water replenishment flow PID control module, used to control the opening of the water replenishment regulating valve in accordance with the steam output flow rate; The correlation formula for the steam output flow rate is as follows: ; In the formula, The water supply flow rate for the water supply regulating valve; The saturated steam output flow rate for the steam outlet; The mixed water flow rate is the flow rate of the pipeline between the first three-way valve and the booster pump; This refers to the outlet temperature of the water-side channel of the gas cooler. The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0010] A further improvement of the technical solution of the present invention is that it also includes: a saturated steam output pressure PID control module, used to control the opening of the water-side throttle valve according to the steam output pressure correlation. The correlation for the steam production pressure is as follows: ; In the formula, The saturated steam output pressure for the steam outlet; The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; The water supply flow rate for the water supply regulating valve; The temperature of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0011] A further improvement of the technical solution of the present invention is that it also includes: a PID control module for the outlet water temperature of the mixing tank, used to control the opening degree of the high temperature cooling water inlet regulating valve and the low temperature cooling water inlet regulating valve according to the outlet water temperature of the mixing tank. The correlation formula for the outlet water temperature of the mixing tank is as follows: ; In the formula, The outlet water temperature of the mixing tank; This refers to the inlet flow rate of the high-temperature cooling water. This refers to the inlet temperature of the high-temperature cooling water. This refers to the chilled water return flow rate. This refers to the chilled water return temperature. This refers to the inlet flow rate of the low-temperature cooling water. This refers to the inlet temperature of the low-temperature cooling water. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0012] A further improvement to the technical solution of the present invention is that it further includes: The first flow meter is installed on the pipeline where the makeup water pump is located to detect the makeup water flow rate; The first pressure sensor and the first temperature sensor are installed on the pipeline between the pressurized water pump and the gas cooler, and are used to detect the pressure and temperature of the water after pressurization, respectively. The second temperature sensor is installed on the pipeline between the gas cooler and the water-side throttle valve to detect the outlet temperature of the water-side channel of the gas cooler. The second pressure sensor and the second flow meter are installed on the pipeline between the water-side throttling valve and the flash tank, and are used to detect the pressure and flow rate of the two-phase fluids after throttling, respectively. The third pressure sensor and the third flow meter are installed on the pipeline between the flash tank and the still, and are used to detect the saturated steam output pressure and flow rate, respectively. The fifth flow meter and the eighth temperature sensor are installed on the pipeline between the high-temperature cooling water inlet regulating valve and the mixing tank, and are used to detect the high-temperature cooling water inlet flow rate and temperature, respectively. The sixth flow meter and the ninth temperature sensor are installed on the pipeline between the low-temperature cooling water inlet regulating valve and the mixing tank, and are used to detect the low-temperature cooling water inlet flow rate and temperature, respectively. The seventh flow meter and the tenth temperature sensor are installed on the pipeline between the chilled water return shut-off valve and the mixing tank to detect the chilled water return flow rate and temperature, respectively. The third temperature sensor is installed on the pipeline between the low-temperature CO2 side channel of the CO2 side regenerator and the fifth three-way valve, and is used to detect the temperature of the CO2 working fluid after regeneration. The fifth temperature sensor and the fourth pressure sensor are installed on the pipeline between the fifth three-way valve and the compressor, and are used to detect the compressor suction temperature and suction pressure, respectively. The fourth temperature sensor is located at the outlet of the mixing tank and is used to detect the water temperature at the outlet of the mixing tank. The sixth temperature sensor and the fifth pressure sensor are installed on the pipeline between the compressor and the gas cooler to detect the compressor exhaust temperature and exhaust pressure, respectively. The fourth flow meter is installed on the pipeline between the fourth three-way valve and the regenerator bypass valve to detect the flow rate of CO2 working fluid flowing through the regenerator bypass valve. The seventh temperature sensor is installed on the pipeline between the evaporator and the fourth three-way valve to detect the CO2 outlet temperature of the evaporator.

[0013] A further improvement of the technical solution of the present invention is that the pressure of the saturated steam output by the flash tank is 0.2MPa to 0.5MPa; and the outlet water temperature of the mixing tank is controlled at 20℃ to 28℃.

[0014] A further improvement of the technical solution of the present invention is that a chilled water return valve is provided at the chilled water return inlet; and a chilled water supply valve is provided between the first outlet of the third three-way valve and the chilled water supply outlet.

[0015] A second aspect of the present invention provides a method for operating a high-temperature CO2 heat pump steam generation system applied in the brewing industry, as described in any one of the first aspects of the present invention, comprising: After being compressed into a high-temperature, high-pressure supercritical fluid by the compressor, the CO2 working fluid enters the CO2 side channel of the gas cooler. There, it undergoes countercurrent heat exchange with the pressurized water flowing through the water side channel of the gas cooler. After releasing heat and cooling down, the CO2 working fluid passes through the high-temperature CO2 side channel of the CO2 side regenerator and the CO2 side throttling valve to reduce its pressure before entering the CO2 side channel of the evaporator. There, it absorbs the waste heat of the cooling water flowing through the cooling water side channel of the evaporator and heats up. The heated CO2 working fluid is then split by the fourth three-way valve. One part of it exchanges heat and heats up through the low-temperature CO2 side channel of the CO2 side regenerator, while the other part bypasses through the regenerator bypass valve. The two paths merge and return to the compressor inlet, completing the CO2 transcritical cycle. The flow distribution ratio of the two CO2 working fluids is controlled by adjusting the opening of the regenerator bypass valve. External makeup water enters the first three-way valve via a makeup water pump and a makeup water regulating valve, where it mixes with saturated water from the flash tank's saturated water outlet to form mixed water. This mixed water is then pressurized by a pressurizing pump and sent to the water-side channel of the gas cooler, where it absorbs heat released by the CO2 working fluid and heats up to become high-temperature pressurized water. This high-temperature pressurized water is then throttled and depressurized by a water-side throttling valve before entering the flash tank to complete flash separation, producing saturated steam and saturated water. The saturated steam is sent through the steam channel of the still to the steam-side inlet of the cooler, where it condenses into raw liquor. The saturated water flows back to the first three-way valve to mix with the external makeup water, allowing for repeated recycling. Cooling water from the mixing tank enters the cooling water side channel of the cooler, where it absorbs heat released by the condensation of alcohol vapor and its temperature rises. The heated cooling water is then split through the second three-way valve. Part of it flows back to the high-temperature cooling water inlet of the mixing tank via the high-temperature cooling water inlet regulating valve, while the other part enters the cooling water side channel of the evaporator, where it releases heat and cools down to become low-temperature cooling water. The low-temperature cooling water is pumped to the third three-way valve by the cooling water circulation pump. Part of it is output through the chilled water supply port for air conditioning in the plant area, while the other part is stored in the cold storage tank and then flows back to the low-temperature cooling water inlet of the mixing tank via the low-temperature cooling water inlet regulating valve. The chilled water return flows back to the chilled water return inlet of the mixing tank via the chilled water return port. By adjusting the opening of the high-temperature cooling water inlet regulating valve and the low-temperature cooling water inlet regulating valve, the outlet water temperature of the mixing tank is controlled to be stable at the set value.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a high-temperature CO2 heat pump steam generation system for the brewing industry. It comprises a complete dual-system architecture consisting of a CO2 transcritical cycle heat pump subsystem, a steam preparation subsystem for the heating end, and a cooling water circulation subsystem for the cooling end. The series and parallel connections of the CO2-side circulation loop, the water-side circulation loop, and the cooling water circulation loop are clearly defined. Specifically, the compressor outlet forms a CO2 circulation loop via a gas cooler, a CO2-side regenerator, a throttle valve, and an evaporator. Simultaneously, a parallel bypass path is formed through the regenerator bypass valve and two three-way valves. In the water-side circulation, makeup water mixes with saturated water in the flash tank and is pumped into the gas cooler for heat absorption. It then enters the flash tank through the throttle valve to produce saturated steam, and the saturated water is recycled. In the cooling water circulation, water from the mixing tank flows sequentially through the cooler for heat absorption and the evaporator for heat release, before being diverted through the three-way valve to the chilled water supply and the cold storage tank, and finally returning to the mixing tank. Through the above technical solution, the present invention realizes the simultaneous production of saturated steam and cooling water circulation for the brewing industry with a single heat pump unit. It fundamentally replaces the traditional three-equipment combination system consisting of a steam generating heat pump, a steam compressor, a lithium bromide refrigerator, and a cooling tower. It solves the technical problems of complex equipment composition, low integration, and high initial investment cost of the existing system, and greatly reduces the system complexity and operation and maintenance difficulty.

[0017] This invention further incorporates a compressor discharge pressure PID control module and defines a mathematical model for the optimal compressor discharge pressure correlation. This correlation establishes a quantitative relationship between the optimal discharge pressure and the compressor suction temperature, compressor discharge temperature, compressor suction pressure, and saturated steam output pressure. This control module adjusts the compressor speed in real time. This invention achieves dynamic optimization of the system's global energy efficiency. In the transcritical carbon dioxide cycle, there exists an optimal compressor discharge pressure corresponding to the system's global optimal energy efficiency. This optimal discharge pressure is not a fixed value but changes dynamically with operating conditions. Traditional fixed discharge pressure control strategies cannot adapt to variable operating conditions. The correlation of this invention quantitatively characterizes the complex nonlinear relationship between the optimal discharge pressure and the compressor suction and discharge temperatures and pressures, as well as the steam output pressure. This allows the system to calculate the current optimal discharge pressure setpoint online based on real-time operating conditions and accurately track it by adjusting the compressor speed through PID control. This represents a technological advancement from constant pressure operation to dynamic energy efficiency optimization, ensuring that the system always operates at its highest global energy efficiency under different operating conditions.

[0018] This invention further incorporates a PID control module for compressor exhaust temperature and defines a mathematical model for the optimal compressor exhaust temperature correlation. This correlation establishes a quantitative relationship between the optimal exhaust temperature and the water-side outlet temperature of the gas cooler, the temperature of the regenerated carbon dioxide working fluid, the bypass flow rate, the carbon dioxide-side outlet temperature of the evaporator, the compressor exhaust pressure, and the compressor suction pressure. This control module adjusts the opening of the regenerator bypass valve in real time. This invention achieves dynamic and precise control of the compressor exhaust temperature. By controlling a portion of the carbon dioxide working fluid to bypass directly to the compressor suction port via a bypass pipeline, it mixes with the regenerated carbon dioxide working fluid. Without changing the compressor speed, the suction temperature and consequently the exhaust temperature are precisely controlled by adjusting the bypass ratio. The response is fast and the adjustment range is wide. The temperature correlation quantitatively reflects the combined influence of the carbon dioxide-side circulating thermodynamic state and the water-side heating capacity on the exhaust temperature, enabling the controller to calculate the optimal bypass valve opening in real time based on multi-dimensional inputs. This ensures that the compressor exhaust temperature operates stably at the optimal value under various disturbances, guaranteeing the system's heating capacity and operational safety.

[0019] This invention further incorporates a PID control module for the makeup water flow rate and defines a complete mathematical model for the correlation between the steam output flow rate and the makeup water flow rate. This correlation establishes a nonlinear quantitative relationship between the makeup water flow rate and multiple variables, including the saturated steam output flow rate, the mixed water flow rate, the water-side outlet temperature of the gas cooler, the pressure after the throttle valve, and the pressurized water pressure. This control module adjusts the opening of the makeup water regulating valve in real time. This invention achieves dynamic and precise tracking of the makeup water flow rate to the steam output flow rate, ensuring that the water-side circulation remains balanced under varying operating conditions. This effectively solves the engineering problems of flash tank water level fluctuations and unstable steam output. Simultaneously, this correlation enables the controller to pre-calculate the target makeup water volume based on multiple operating boundary conditions, achieving feedforward-feedback coordinated control. Compared to traditional single feedback control, this significantly improves the response speed and control accuracy under varying operating conditions, ensuring that the system maintains a stable dynamic balance in the water-side circulation under different operating conditions.

[0020] This invention further incorporates a PID control module for saturated steam output pressure and defines a mathematical model for the steam output pressure correlation. This correlation establishes a quantitative relationship between the pressure after the water-side throttling valve and the steam outlet pressure, and the pressurized water pressure, makeup water flow rate, and pressurized water temperature. This control module adjusts the opening of the water-side throttling valve in real time. This invention achieves stable and precise control of the steam outlet pressure, ensuring that the core process indicator of saturated steam pressure always meets the requirements of the brewing distillation process. The water-side throttling valve, as a key throttling element in the water-side circulation, directly determines the working pressure of the flash tank, thus affecting the output steam pressure. The pressure correlation quantitatively characterizes the nonlinear coupling relationship between the flash pressure and the upstream pressurized water pressure, makeup water flow rate, and makeup water temperature, providing a theoretical basis for the precise control of the throttling valve. This overcomes the blindness of traditional experience-based adjustments and ensures that the output steam pressure can quickly recover to the set value under various disturbances.

[0021] This invention further incorporates a PID control module for the mixing tank outlet temperature and defines a mathematical model for the correlation equation of the mixing tank outlet temperature. This correlation equation establishes a weighted quantitative relationship between the mixing tank outlet temperature and the inlet flow rate and temperature of high-temperature cooling water, the return flow rate and temperature of chilled water, and the inlet flow rate and temperature of low-temperature cooling water. This control module adjusts the opening degrees of the high-temperature and low-temperature cooling water inlet regulating valves in real time. This invention achieves precise control of the mixing tank outlet temperature within a preset range, meeting the differentiated requirements of different brewing processes for cooling water inlet temperature. The temperature correlation equation, based on the principle of energy conservation, quantitatively expresses the mathematical relationship between the temperature after mixing three different water sources and the flow rate and temperature of each branch. This allows the controller to calculate the optimal valve opening combination in real time based on multi-dimensional inputs, achieving high-precision closed-loop control of the mixing tank outlet temperature and ensuring that the temperature of the cooling water before entering the cooler remains stable at the user-set process value under various disturbances. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the process structure of a high-temperature CO2 heat pump steam generation system applied to the brewing industry in an embodiment of the present invention; Figure 2This is a schematic diagram of PID (Proportional-Integral-Derivative) control of a CO2 heat pump system in an embodiment of the present invention. Figure 3 This is a schematic diagram of the control logic of the CO2 heat pump system in an embodiment of the present invention; The explanations of the reference numerals in the figure are as follows: 1. Compressor; 2. Gas cooler; 3. CO2-side regenerator; 4. CO2-side throttling valve; 5. Evaporator; 6. Flash tank; 7. Makeup water pump; 8. Pressurized water pump; 9. Water-side throttling valve; 10. Distillation still; 11. Cooler; 12. Cooling water circulating pump; 13. Cold storage tank; 14. Mixing tank; 15. First three-way valve; 16. Second three-way valve; 17. Third three-way valve; 18. Fourth three-way valve; 19. Fifth three-way valve; 20. Regenerator bypass valve; 21. Makeup water regulating valve; 22. High-temperature cooling water inlet regulating valve; 23. Low-temperature cooling water inlet regulating valve; 24. Chilled water return shut-off valve; 25. Chilled water supply shut-off valve; 26. 27. First flow meter; 28. First pressure sensor; 29. ​​First temperature sensor; 30. Second temperature sensor; 31. Second pressure sensor; 32. Second flow meter; 33. Third temperature sensor; 34. Fourth temperature sensor; 35. Third flow meter; 36. Fifth temperature sensor; 37. Fourth pressure sensor; 38. Sixth temperature sensor; 39. Fifth pressure sensor; 40. Fourth flow meter; 41. Seventh temperature sensor; 42. Fifth flow meter; 43. Eighth temperature sensor; 44. Sixth flow meter; 45. Ninth temperature sensor; 46. Seventh flow meter; 47. Tenth temperature sensor. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of protection of the present invention, but rather to illustrate specific selected embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0025] The following detailed description, in conjunction with the accompanying drawings, outlines some embodiments of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other.

[0026] Please see Figure 1 This invention provides a high-temperature CO2 heat pump steam generation system for the brewing industry. Specifically, it is a CO2 heat pump system that can simultaneously generate steam and provide cooling for the brewing industry. It can efficiently and stably produce 0.2-0.5MPa saturated steam and provide the cooling capacity required for cooling water recycling and air conditioning in the brewery. Specifically, it includes: a compressor 1, a gas cooler 2, a CO2-side regenerator 3, a CO2-side throttling valve 4, an evaporator 5, a flash tank 6, a makeup water pump 7, a pressurized water pump 8, a water-side throttling valve 9, a still 10, a cooler 11, a cooling water circulation pump 12, a cold storage tank 13, a mixing tank 14, a first three-way valve 15, a second three-way valve 16, a third three-way valve 17, a fourth three-way valve 18, a fifth three-way valve 19, a regenerator bypass valve 20, and a makeup water pump 11. Water regulating valve 21, high-temperature cooling water inlet regulating valve 22, low-temperature cooling water inlet regulating valve 23, chilled water return shut-off valve 24, chilled water supply shut-off valve 25, first flow meter 26, first pressure sensor 27, first temperature sensor 28, second temperature sensor 29, second pressure sensor 30, second flow meter 31, third temperature sensor 32, fourth temperature sensor 33, third pressure sensor 34, third flow meter 35, fifth temperature sensor 36, fourth pressure sensor 37, sixth temperature sensor 38, fifth pressure sensor 39, fourth flow meter 40, seventh temperature sensor 41, fifth flow meter 42, eighth temperature sensor 43, sixth flow meter 44, ninth temperature sensor 45, seventh flow meter 46, and tenth temperature sensor 47.

[0027] The outlet of compressor 1 is connected to the CO2 side inlet of gas cooler 2. The CO2 side outlet of gas cooler 2 is connected to the high-temperature CO2 side inlet of regenerator 3. The high-temperature CO2 side outlet of regenerator 3 is connected to the inlet of CO2 side throttle valve 4. The outlet of CO2 side throttle valve 4 is connected to the CO2 side inlet of evaporator 5. The CO2 side outlet of evaporator 5 is connected to the inlet of fourth three-way valve 18. The first outlet of fourth three-way valve 18 is connected to the low-temperature CO2 side inlet of regenerator 3. The low-temperature CO2 side outlet of regenerator 3 is connected to the first inlet of fifth three-way valve 19. The second outlet of fourth three-way valve 18 is connected to the inlet of regenerator bypass valve 20. The outlet of regenerator bypass valve 20 is connected to the second inlet of fifth three-way valve 19. The outlet of fifth three-way valve 19 is connected to the inlet of compressor 1, thus forming a CO2 transcritical cycle heat pump subsystem.

[0028] The saturated water outlet of flash tank 6 is connected to the first inlet of the first three-way valve 15. The outlet of water supply pump 7 is connected to the inlet of water supply regulating valve 21. The outlet of water supply regulating valve 21 is connected to the second inlet of the first three-way valve 15. The outlet of the first three-way valve 15 is connected to the inlet of pressurized water pump 8. The outlet of pressurized water pump 8 is connected to the water-side inlet of gas cooler 2. The water-side outlet of gas cooler 2 is connected to the inlet of water-side throttle valve 9. The outlet of water-side throttle valve 9 is connected to the inlet of flash tank 6. The saturated steam outlet of flash tank 6 is connected to the steam channel inlet of still 10. The steam channel outlet of still 10 is connected to the steam-side inlet of cooler 11, thus forming a steam preparation subsystem for the heating side.

[0029] The outlet of the mixing tank 14 is connected to the cooling water inlet of the cooler 11. The cooling water outlet of the cooler 11 is connected to the inlet of the second three-way valve 16. The first outlet of the second three-way valve 16 is connected to the inlet of the high-temperature cooling water inlet regulating valve 22. The outlet of the high-temperature cooling water inlet regulating valve 22 is connected to the high-temperature cooling water inlet of the mixing tank 14. The second outlet of the second three-way valve 16 is connected to the cooling water inlet of the evaporator 5. The cooling water outlet of the evaporator 5 is connected to the inlet of the cooling water circulating pump 12. The outlet of the cooling water circulating pump 12 is connected to the inlet of the third three-way valve 17. The first outlet of valve 7 is connected to the inlet of chilled water supply shut-off valve 25, and the outlet of chilled water supply shut-off valve 25 is connected to the chilled water supply port. The second outlet of the third three-way valve 17 is connected to the inlet of cold storage tank 13. The outlet of cold storage tank 13 is connected to the inlet of low temperature cooling water inlet regulating valve 23. The outlet of low temperature cooling water inlet regulating valve 23 is connected to the low temperature cooling water inlet of mixing tank 14. The chilled water return port is connected to the inlet of chilled water return shut-off valve 24. The outlet of chilled water return shut-off valve 24 is connected to the medium temperature chilled water return inlet of mixing tank 14, thus forming a cooling water circulation subsystem.

[0030] This invention provides a CO2 heat pump system for the brewing industry that can simultaneously generate and cool steam, comprising: The CO2 transcritical cycle heat pump subsystem includes: a compressor, a gas cooler, a regenerator, a throttling valve, an evaporator, a three-way valve, and a bypass valve; the CO2 side channels of the compressor and gas cooler, the high-temperature CO2 side channel of the regenerator, the throttling valve, the CO2 side channel of the evaporator, and the low-temperature CO2 side channel of the CO2 side regenerator are sequentially connected to form a CO2 circulation loop, and the bypass valve is connected in parallel with the high-temperature CO2 side channel of the regenerator through two three-way valves; The steam preparation subsystem at the heating end includes a water supply pump, a water supply regulating valve, a three-way valve, a pressurized water pump, a gas cooler, a water-side throttling valve, a flash evaporator, a still, and a cooler. The water supply pump is connected to the water supply regulating valve, which is connected to the first inlet of the three-way valve. The saturated water outlet of the flash evaporator is connected to the second inlet of the three-way valve. The outlet of the three-way valve is connected to the inlet of the pressurized water pump. The outlet of the pressurized water pump is connected to the water-side channel inlet of the gas cooler. The water-side channel outlet of the gas cooler is connected to the inlet of the water-side throttling valve. The outlet of the water-side throttling valve is connected to the inlet of the flash evaporator. The saturated steam outlet of the flash evaporator is connected to the steam channel inlet of the still. The steam channel outlet of the still is connected to the steam channel inlet of the cooler, where the steam is condensed into raw liquor. The cooling water circulation subsystem for the cooling supply side includes an evaporator, a circulating water pump, a three-way valve, a cold storage tank, a regulating valve, a mixing tank, and a cooler. The cooling water side passage of the evaporator, the circulating water pump, the cold storage tank, the regulating valve, the mixing tank, and the cooling water side passage of the cooler are connected in sequence to form a cooling water circulation loop. Among them, the pipeline between the outlet of the cooling water side passage of the cooler and the inlet of the cooling water side passage of the evaporator is connected to the high-temperature water inlet of the mixing tank through a three-way valve and is equipped with a regulating valve. The air conditioning chilled water return is connected to the warm water inlet of the mixing tank and is equipped with a shut-off valve. The pipeline between the outlet of the circulating water pump and the inlet of the cold storage tank is connected to the air conditioning chilled water supply through a three-way valve and is equipped with a shut-off valve.

[0031] In this embodiment of the invention, a sixth temperature sensor 38 and a fifth pressure sensor 39 are installed on the connecting pipe between the compressor 1 and the CO2 side channel of the gas cooler 2, for detecting the temperature (T) of the CO2 working fluid at the compressor exhaust state point. 38 ) and pressure (P) 39 A seventh temperature sensor 41 is installed on the connecting pipe between the CO2 side channel of evaporator 5 and the fourth three-way valve 18 to detect the temperature (T) of the CO2 working fluid after heat absorption by the evaporator. 41 A fourth flow meter 40 is installed on the connecting pipeline between the fourth three-way valve 18 and the regenerator bypass valve 20 to detect the flow rate (m³) of the CO2 working fluid bypassing the regenerator. 40 A third temperature sensor 32 is installed on the connecting pipe between the low-temperature CO2 side channel of the regenerator 3 and the fifth three-way valve 19 to detect the temperature (T) of the CO2 working fluid after regeneration. 32 The fifth temperature sensor 36 and the fourth pressure sensor 37 are installed on the connecting pipe between the fifth three-way valve 19 and the compressor 1 to detect the temperature (T) of the CO2 working fluid at the compressor's suction point. 36 ) and pressure (P) 37 A first flow meter 26 is installed on the pipeline where the water supply pump 7 is located to detect the water supply flow rate (m³). 26A first pressure sensor 27 and a first temperature sensor 28 are installed on the connecting pipe between the pressurized water pump 8 and the water-side channel of the gas cooler 2 to detect the pressure (P) of the mixed water after pressurization. 27 ) and temperature (T) 28 A second temperature sensor 29 is installed on the connecting pipe between the water-side channel of the gas cooler 2 and the water-side throttle valve 9 to detect the temperature (T) of the pressurized water after it has been heated by the gas cooler. 29 A second pressure sensor 30 and a second flow meter 31 are installed on the connecting pipe between the water-side throttling valve 9 and the inlet of the flash tank 6 to detect the pressure (P) of the two-phase fluid after throttling. 30 ) and flow rate (m 31 A third pressure sensor 34 and a third flow meter 35 are installed on the connecting pipeline between the saturated steam outlet of flash evaporator 6 and still 10 to detect the pressure (P) of the produced saturated steam. 34 ) and flow rate (m 35 A fifth flow meter 42 and an eighth temperature sensor 43 are installed on the connecting pipe between the high-temperature cooling water inlet regulating valve 22 and the high-temperature cooling water inlet of the mixing tank 14 to detect the flow rate (m³) of the high-temperature cooling water inlet. 42 ) and temperature (T) 43 A sixth flow meter 44 and a ninth temperature sensor 45 are installed on the connecting pipe between the low-temperature cooling water inlet regulating valve 23 and the low-temperature cooling water inlet of the mixing tank 14 to detect the flow rate (m³) of the low-temperature cooling water inlet. 44 ) and temperature (T) 45 A seventh flow meter 46 and a tenth temperature sensor 47 are installed on the connecting pipe between the chilled water return shut-off valve 24 and the medium-temperature chilled water inlet of the mixing tank 14 to monitor the flow rate (m³) of the chilled water return. 46 ) and temperature (T) 47 ).

[0032] Please see Figure 2 and Figure 3 In this embodiment of the invention, the system control and optimization mainly revolve around five key parameters: water supply flow rate, saturated steam output pressure, mixing tank outlet water temperature, compressor exhaust temperature, and compressor exhaust pressure. By constructing an optimal setpoint feedforward model based on operating boundary conditions and combining it with multi-loop PID feedback control, the actuators at each level are adjusted in real time to ensure that the above parameters always track their dynamic optimal values, thereby ensuring that the system can stably operate at the highest global energy efficiency under different operating conditions.

[0033] This invention also provides a control strategy for a CO2 heat pump system capable of simultaneously generating and cooling steam, applied in the brewing industry. The strategy includes: a makeup water flow rate PID control module, a saturated steam output pressure PID control module, a mixing tank outlet water temperature PID control module, a compressor exhaust temperature PID control module, and a compressor exhaust pressure PID control module. When the CO2 heat pump system capable of simultaneously generating and cooling steam is running in the brewing industry, the makeup water flow rate PID controller adjusts the opening of the makeup water regulating valve to make the system's makeup water volume equal to the steam supply flow rate, achieving a balance in the steam generation cycle. The saturated steam output pressure PID controller adjusts the opening of the water-side throttling valve to make the saturated steam pressure reach a set value. The mixing tank outlet water temperature PID controller adjusts the opening of the high-temperature water inlet and low-temperature water inlet regulating valves to make the water temperature in the mixing tank reach a set value. The compressor exhaust temperature PID controller adjusts the opening of the bypass valve to make the compressor exhaust temperature reach an optimal value. The compressor exhaust pressure PID controller adjusts the compressor speed to make the compressor exhaust pressure reach an optimal value.

[0034] Specifically, the adaptive regulation of compressor discharge pressure includes: the compressor forming the core regulating actuator, which, during operation, controls the impeller's work capacity on the CO2 working fluid by adjusting the compressor's speed, thereby precisely regulating the discharge pressure. Specifically, the compressor discharge pressure (P...) 39 ) and compressor suction temperature (T) 36 ), compressor discharge temperature (T) 38 ), compressor suction pressure (P) 37 ), saturated steam output pressure (P) 34 To optimize the compressor discharge pressure and achieve the optimal system coefficient of performance (COP), a correlation model is constructed between the compressor discharge pressure and these variables. The correlation equation is as follows:

[0035] In the formula, The optimal compressor discharge pressure; This refers to the compressor suction temperature. This refers to the compressor discharge temperature. This refers to the compressor's suction pressure. The pressure at which saturated steam is produced; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0036] With compressor speed as the control variable, the controller's objective is to stabilize the compressor discharge pressure at the setpoint calculated by the optimization model. Based on the real-time feedback of the calculated system COP, the proportional control coefficient of the PID control module is optimized and adjusted. Integral adjustment coefficient and differential adjustment coefficient Each time the system completes a control cycle, it compares the deviation between the compressor discharge pressure setpoint and the actual measured value with a preset accuracy threshold. If the deviation exceeds the threshold, this deviation is used as the input to the controller. The PID controller calculates the corresponding control quantity based on this deviation, and by coordinating and adjusting the compressor speed, it precisely controls the compressor discharge pressure, ensuring that the system always operates within its optimal energy efficiency range.

[0037] The compressor discharge pressure is calculated using the differential method by the PID controller. The formula for calculating the dynamic adjustment speed n of compressor 1 is as follows:

[0038] in, The difference between the actual exhaust pressure and the real-time optimal exhaust pressure is represented by n, where n is the number of calculations. , and These are the proportional control coefficient, integral control coefficient, and derivative control coefficient, respectively. Based on the current operating conditions, the optimal compressor discharge pressure setpoint (P) under the current system operating conditions is calculated in real-time using the optimal correlation model of compressor discharge pressure. 39,opt To achieve rapid and accurate tracking of this setpoint, the proportional, integral, and derivative adjustment parameters are respectively set to [values ​​to be filled in]. , , The controller's output is directly used to adjust the compressor's speed.

[0039] Specifically, adaptive adjustment of compressor discharge temperature includes: Compressor discharge temperature is a key parameter affecting the system's heating capacity and safe operation. During operation, by adjusting the opening of the regenerator bypass valve, the flow distribution ratio of CO2 working fluid through regenerated and non-regenerated channels is controlled, thereby precisely regulating the temperature of the CO2 working fluid at the compressor's suction point. Specifically, the compressor discharge temperature (T...) 38 ) and the temperature after pressurized water heating (T) 29 ), Evaporator CO2 side outlet temperature (T) 41 ), CO2 reheat temperature (T) 32 CO2 bypass flow rate (m³) 40 ), compressor suction pressure (P) 37 ), compressor discharge pressure (P) 39 Related to these variables, a correlation model is constructed between the compressor discharge temperature and these variables, and the correlation formula is:

[0040] In the formula, To achieve the optimal compressor discharge temperature; This refers to the outlet temperature of the water-side channel of the gas cooler. The temperature of the CO2 working fluid after reheating; The CO2 working fluid flow rate passing through the regenerator bypass valve; This refers to the CO2 side outlet temperature of the evaporator. This refers to the compressor's discharge pressure. This refers to the compressor's suction pressure. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0041] Using the opening degree of the regenerator bypass valve as the control variable, the controller's control objective is to stabilize the compressor discharge temperature at the setpoint calculated by the optimization model. Based on the real-time feedback of the calculated system heating capacity, the proportional control coefficient of the PID control module is optimized and adjusted. Integral adjustment coefficient and differential adjustment coefficient Each time the system completes a control cycle, it compares the deviation between the compressor discharge temperature setpoint and the actual measured value with a preset accuracy threshold. If the deviation exceeds the threshold, this deviation is used as the input to the controller. The PID controller calculates the corresponding control quantity based on this deviation and precisely controls the compressor discharge temperature by coordinating and adjusting the opening of the regenerator bypass valve, ensuring that the system always operates within its optimal energy efficiency range.

[0042] The compressor discharge temperature PID controller uses the differential method for calculation. The formula for calculating the dynamic adjustment opening v of the regenerator bypass valve is:

[0043] in, The difference between the actual exhaust temperature and the set exhaust temperature, where n is the number of calculations. , and These are the proportional control coefficient, integral control coefficient, and derivative control coefficient, respectively. Based on the current operating conditions, the optimal compressor discharge temperature setpoint (T) under the current system operating conditions is calculated in real-time using the optimal correlation model for compressor discharge temperature. 39,opt To achieve rapid and accurate tracking of this setpoint, the proportional, integral, and derivative adjustment parameters are respectively set to [values ​​to be filled in]. , , The controller's output is directly used to adjust the opening of the regenerator bypass valve.

[0044] Specifically, the adaptive adjustment of the makeup water flow rate includes setting the makeup water flow rate to the steam flow rate that the steam preparation subsystem at the heating end can generate under specific operating conditions, so as to achieve dynamic balance in the water-side circulation. The steam flow rate (m³) 35 ) and mixed water flow rate (m31 ), pressurized water pressure (P) 27 ), water-side outlet temperature of gas cooler (T) 29 ), pressure after the throttle valve (P) 30 Based on factors such as steam flow rate and the aforementioned boundary conditions and operating parameters, a correlation model is established, which can be expressed as:

[0045] In the formula, The water supply flow rate for the water supply regulating valve; The saturated steam output flow rate for the steam outlet; The mixed water flow rate is the flow rate of the pipeline between the first three-way valve and the booster pump; This refers to the outlet temperature of the water-side channel of the gas cooler. The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0046] Using the opening degree of the water inlet regulating valve 26 as the control variable, the controller outputs the set value of the water inlet flow rate. Based on the dynamic characteristics of the system under coupled operating conditions, the proportional, integral, and derivative parameters of the PID control module are adjusted online. After the system completes one control cycle, if the absolute value of the deviation between the set value of the water inlet flow rate and the actual measured value of the steam flow rate is greater than the preset control accuracy threshold, this deviation is input as an error signal to the PID controller. The controller calculates the control quantity based on the error signal and adjusts the opening degree of the water inlet regulating valve to change the water inlet flow rate, thereby precisely adjusting the water inlet flow rate to be equal to the steam output flow rate. As the PID parameters are adaptively adjusted to approach the optimal value, the measured water inlet flow rate of the system will gradually approach and eventually stabilize near the target set value until the absolute value of the error is less than the control accuracy threshold. This control loop can adjust the control parameters and valve opening in real time according to different operating conditions, so that the water inlet flow rate is stabilized at the dynamic optimal value, thereby ensuring that the system performance is always in the best state.

[0047] The PID controller for the water supply flow rate uses the differential method for calculation. The formula for calculating the dynamic adjustment opening v of the water supply inlet regulating valve 26 is as follows:

[0048] in, The difference between the actual water supply flow rate and the set water supply flow rate, where n is the number of calculations. , and These are the proportional control coefficient, integral control coefficient, and derivative control coefficient, respectively. Based on the current operating conditions, the makeup water flow rate (m) under the current system operating conditions is calculated in real time according to the makeup water flow correlation model.27 To achieve rapid and accurate tracking of this setpoint, the proportional, integral, and derivative adjustment parameters are set to specific values. , , .

[0049] Specifically, the adaptive adjustment of saturated steam production pressure includes: saturated steam production pressure (P) 34 The setpoint (P) is the value given by the user according to process requirements. It is the output target that the system must guarantee. This setpoint is given by the user according to production needs, and the goal of system control is to drive the actual saturated steam output pressure to stabilize at this fixed setpoint. In the system, the saturated steam output pressure (P) is... 34 Mainly related to water replenishment flow (m³) 26 ), pressurized water pressure (P) 27 ), pressurized water temperature (T) 28 Closely related to these variables, a correlation model was established between the saturated steam production pressure and the aforementioned key variables. The correlation can be expressed as:

[0050] In the formula, The saturated steam output pressure for the steam outlet; The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; The water supply flow rate for the water supply regulating valve; The temperature of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0051] Using the opening degree of the water-side throttle valve as the control variable, the controller outputs the setpoint of the saturated steam production pressure, and adjusts the PID control module according to the system's dynamic characteristics. , and Three parameters are involved. After one cycle, if the absolute value of the deviation between the setpoint and the actual measured saturated steam output pressure exceeds the preset control accuracy threshold, this deviation is input as an error signal to the PID controller. The controller calculates the control input based on the error signal and adjusts the opening of the water-side throttle valve to change the saturated steam output pressure. As the PID parameters adaptively adjust towards the optimal value, the measured saturated steam output pressure gradually approaches and stabilizes near the target setpoint until the absolute value of the error is less than the control accuracy threshold. This control loop can adjust the opening of the water-side throttle valve in real time according to different operating conditions, stabilizing the saturated steam output pressure at the setpoint.

[0052] The saturated steam pressure PID controller uses the differential method for calculation. The formula for calculating the dynamic adjustment opening v of the water-side throttle valve is as follows:

[0053] in, The value of n represents the difference between the actual saturated steam output pressure and the set saturated steam output pressure, where n is the number of calculations. , and These are the proportional control coefficient, integral control coefficient, and derivative control coefficient, respectively. Based on the current operating conditions, the required saturated steam output pressure under these conditions is the system setpoint, and the setpoint values ​​for the proportional, integral, and derivative control parameters are respectively... , , 5.

[0054] Specifically, the adaptive adjustment of the mixing tank outlet water temperature includes: the mixing tank outlet water temperature (T 33 The setpoint, given by the user based on process requirements, is the output target that the system must guarantee. This setpoint is provided by the user according to production needs, and the system's control objective is to drive the actual mixing tank outlet water temperature to stabilize at this fixed setpoint. Because the mixing tank outlet water temperature is affected by multiple coupled factors, to meet stringent process parameters, a correlation model between the mixing tank outlet water temperature and key state parameters is established, and its expression is:

[0055] In the formula, The outlet water temperature of the mixing tank; This refers to the inlet flow rate of the high-temperature cooling water. This refers to the inlet temperature of the high-temperature cooling water. This refers to the chilled water return flow rate; This refers to the chilled water return temperature. This refers to the inlet flow rate of the low-temperature cooling water. This refers to the inlet temperature of the low-temperature cooling water. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

[0056] Using the opening degrees of the high-temperature cooling water inlet regulating valve and the low-temperature cooling water inlet regulating valve as control variables, the controller outputs the set value of the mixing tank outlet water temperature, and adjusts the PID control module according to the system's dynamic characteristics. , and Three parameters are used. After one cycle, if the absolute value of the deviation between the setpoint and the actual measured high-temperature steam output temperature exceeds the preset control accuracy threshold, this deviation is input as an error signal to the PID controller. The controller calculates the control quantity based on the error signal and adjusts the opening of the high-temperature cooling water inlet regulating valve and the low-temperature cooling water inlet regulating valve to change the flow ratio of the high and low-temperature cooling water, thereby controlling the outlet temperature of the mixing tank. As the PID parameters adaptively adjust towards the optimal value, the measured high-temperature steam output temperature will gradually approach and stabilize near the target setpoint until the absolute value of the error is less than the control accuracy threshold. This control loop can adjust the opening of the high-temperature cooling water inlet regulating valve and the low-temperature cooling water inlet regulating valve in real time according to different operating conditions, stabilizing the outlet temperature of the mixing tank at the setpoint.

[0057] The PID controller for the mixing tank outlet temperature uses the differential method for calculation. The calculation formulas for the opening degree v of the high-temperature cooling water inlet regulating valve and the low-temperature cooling water inlet regulating valve are as follows:

[0058]

[0059] in, The value of n represents the difference between the set value and the actual value of the mixing tank outlet water temperature. , and These are the proportional control coefficient, integral control coefficient, and derivative control coefficient, respectively. Based on the current operating conditions, the required high-temperature steam output temperature under these conditions is the system setpoint, and the setpoint values ​​for the proportional, integral, and derivative control parameters are respectively... , , .

[0060] To address the shortcomings of existing waste heat recovery systems in the liquor brewing industry, such as complex equipment composition, multiple energy conversion levels, low operating efficiency, and insufficient ability to coordinate and regulate heating and cooling loads, this invention uses a transcritical CO2 heat pump as its core architecture. It integrates a transcritical CO2 cycle heat pump subsystem, a steam preparation subsystem for heating, and a cooling water circulation subsystem for cooling. Pressurized water is heated by a gas cooler, and 0.2~0.5MPa saturated steam is produced through throttling flash evaporation to supply the distillation process. Low-temperature cooling water is produced by an evaporator, simultaneously meeting the cooling water circulation and air conditioning needs of the plant. A cold storage tank and a mixing tank are also included to achieve cold energy storage and precise control of the cooling water inlet temperature. This invention simultaneously constructs a multi-parameter correlation model for makeup water flow rate, saturated steam output pressure, mixing tank outlet water temperature, and compressor exhaust temperature and pressure. Employing a multi-loop PID collaborative control strategy, it can dynamically track the system's globally optimal operating parameters. By adjusting the compressor speed and valve openings, it ensures stable output of steam parameters and cooling water temperature while keeping the system operating within its optimal energy efficiency range. This invention features high integration and excellent waste heat recovery efficiency, and can simultaneously cover the heating and cooling needs of the brewing industry, effectively improving the overall energy utilization efficiency and reducing initial investment and operation and maintenance costs.

[0061] This invention discloses a system architecture and control logic. Its core technical approach is to abandon the traditional multi-device coupling and multi-stage energy conversion waste heat utilization mode, and instead use a single transcritical CO2 heat pump steam generator unit as the core hub of the entire system. On the one hand, it fully explores and utilizes the physical advantages of CO2 working fluid, which has a low critical temperature and significant temperature glide characteristics when releasing heat in the supercritical region, enabling it to achieve efficient countercurrent heat exchange with pressurized water on the gas cooler side. This directly converts low-grade waste heat into thermal energy in the 200°C temperature range, and produces 0.2~0.5MPa saturated steam in one step through throttling flash evaporation, thus physically avoiding the irreversible losses of multi-stage heat exchange and steam compression in conventional systems. On the other hand, through the expansion work of the transcritical cycle, low-temperature cooling water is simultaneously produced on the evaporator side, realizing the combined heating and cooling of high-pressure steam production and low-temperature chilled water supply. The embodiments of the present invention, through the above-mentioned highly integrated thermodynamic configuration and synergistic control strategy, completely replace the traditional three-equipment combination system consisting of a steam generating heat pump, a steam compressor, a lithium bromide refrigerator and a cooling tower with a single equipment group. While simplifying the system structure, it fundamentally improves the waste heat recovery efficiency and primary energy utilization rate.

[0062] In summary, this invention discloses a CO2 heat pump system and optimized control method capable of producing 0.2-0.5 MPa saturated steam required for brewing processes and simultaneously providing cooling. High-temperature brewing steam needs to exchange heat with cooling water in a cooler to condense into raw liquor. Part of the cooling capacity provided by the CO2 heat pump is used to offset the heat absorbed by the cooling water from the brewing steam, achieving the purpose of cooling water recycling; another part of the cooling capacity is used to handle the cooling load of the factory's air conditioning system. The cooling load is regulated by a cold storage tank due to fluctuations in ambient temperature and seasons. When the cooling load decreases, more of the low-temperature cooling water, cooled by the evaporator, enters the cold storage tank for storage. Depending on the process requirements of different liquors, the temperature of the cooling water before entering the cooler must be strictly controlled between 20℃ and 28℃. This requirement is achieved by controlling the opening of the regulating valves at the three inlets of the mixing tank to adjust the flow distribution between high-temperature cooling water, low-temperature cooling water, and medium-temperature chilled water return water. The specific cooling water inlet temperature is a user-set value. When the measured temperature is lower than the set value, the valve opening at the high-temperature cooling water inlet is increased, and the valve opening at the low-temperature cooling water inlet is decreased; when the measured temperature is higher than the set value, the valve opening at the low-temperature cooling water inlet is increased, and the valve opening at the high-temperature cooling water inlet is decreased. Furthermore, considering the strongly coupled and multivariable characteristics of the CO2 heat pump system, an intelligent control method based on dynamic optimal setpoint feedforward and multivariable collaborative control is proposed. By solving the globally optimal compressor discharge pressure and temperature under different operating conditions online, and combining this with a multi-loop PID algorithm to collaboratively control the compressor, regulating valve, throttle valve, bypass valve, and other actuators, the system always operates at its optimal energy efficiency point, while ensuring stable steam parameter output and precise control of the cooling water inlet temperature. The control algorithm of this invention possesses rapid response and precise adjustment capabilities. The system adopts a multi-loop PID controller architecture, which, through real-time monitoring of operating parameters and boundary conditions, including temperature and pressure, can quickly adjust when the external environment or user load changes, ensuring that the saturated steam output pressure and cooling water inlet temperature remain stable at the set values, while maintaining all key system parameters within the efficient and safe range. This invention can simultaneously meet the saturated steam supply requirements of the brewing industry, the cooling water recycling requirements, and the air conditioning cooling load of the plant area. It provides a promising technical solution for replacing the existing complex cold and heat coupling waste heat comprehensive utilization system, improving the comprehensive energy utilization efficiency, and realizing cost reduction and efficiency improvement in the brewing industry.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-temperature CO2 heat pump steam generation system for use in the brewing industry, characterized in that, include: The system comprises a CO2 transcritical cycle heat pump subsystem, a steam preparation subsystem for the heating end, and a cooling water circulation subsystem for the cooling end; among which... The CO2 transcritical cycle heat pump subsystem includes: a compressor (1), a gas cooler (2), a CO2-side regenerator (3), a CO2-side throttling valve (4), an evaporator (5), a fourth three-way valve (18), a fifth three-way valve (19), and a regenerator bypass valve (20); wherein, the outlet of the compressor (1) passes through the CO2-side channel of the gas cooler (2), the high-temperature CO2-side channel of the CO2-side regenerator (3), the CO2-side throttling valve (4), and the evaporator. (5) The CO2 side channel is connected to the inlet of the fourth three-way valve (18), the first outlet of the fourth three-way valve (18) is connected to the first inlet of the fifth three-way valve (19) through the low temperature CO2 side channel of the CO2 side regenerator (3), the second outlet of the fourth three-way valve (18) is connected to the second inlet of the fifth three-way valve (19) through the regenerator bypass valve (20), and the outlet of the fifth three-way valve (19) is connected to the inlet of the compressor (1); The heating end steam preparation subsystem includes: a water supply pump (7), a water supply regulating valve (21), a first three-way valve (15), a pressurizing water pump (8), the gas cooler (2), a water-side throttling valve (9), a flash tank (6), a still (10), and a cooler (11); wherein, the outlet of the water supply pump (7) is connected to the first inlet of the first three-way valve (15) via the water supply regulating valve (21), the saturated water outlet of the flash tank (6) is connected to the second inlet of the first three-way valve (15), the outlet of the first three-way valve (15) is connected to the inlet of the flash tank (6) via the pressurizing water pump (8), the water-side channel of the gas cooler (2), and the water-side throttling valve (9), and the saturated steam outlet of the flash tank (6) is connected to the steam-side inlet of the cooler (11) via the steam channel of the still (10); The cooling water circulation subsystem at the cooling end includes: the evaporator (5), the cooling water circulation pump (12), the third three-way valve (17), the cold storage tank (13), the low-temperature cooling water inlet regulating valve (23), the mixing tank (14), the cooler (11), the second three-way valve (16), and the high-temperature cooling water inlet regulating valve (22); wherein, the outlet of the mixing tank (14) is connected to the inlet of the second three-way valve (16) through the cooling water side channel of the cooler (11), and the first outlet of the second three-way valve (16) is connected to the high-temperature cooling water inlet regulating valve (22). 2) The high-temperature cooling water inlet of the mixing tank (14) is connected, the second outlet of the second three-way valve (16) is connected to the inlet of the third three-way valve (17) via the cooling water side channel of the evaporator (5) and the cooling water circulating pump (12), the first outlet of the third three-way valve (17) is connected to the chilled water supply port, the second outlet of the third three-way valve (17) is connected to the low-temperature cooling water inlet of the mixing tank (14) via the cold storage tank (13) and the low-temperature cooling water inlet regulating valve (23), and the mixing tank (14) is also provided with a chilled water return inlet.

2. The high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, Also includes: The compressor discharge pressure PID control module is used to control the speed of the compressor (1) according to the optimal compressor discharge pressure correlation. The optimal compressor discharge pressure correlation is as follows: ； In the formula, The optimal compressor discharge pressure; This refers to the compressor suction temperature. This refers to the compressor discharge temperature. This refers to the compressor's suction pressure. The pressure at which saturated steam is produced; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

3. The high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, Also includes: The compressor discharge temperature PID control module is used to control the opening degree of the regenerator bypass valve (20) according to the optimal compressor discharge temperature correlation. The optimal compressor discharge temperature correlation is as follows: ； In the formula, To achieve the optimal compressor discharge temperature; This refers to the outlet temperature of the water-side channel of the gas cooler. The temperature of the CO2 working fluid after reheating; The CO2 working fluid flow rate passing through the regenerator bypass valve; This refers to the CO2 side outlet temperature of the evaporator. This refers to the compressor's discharge pressure. This refers to the compressor's suction pressure. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

4. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, Also includes: The water supply flow PID control module is used to control the opening degree of the water supply regulating valve (21) in accordance with the steam output flow rate; The correlation formula for the steam output flow rate is as follows: ； In the formula, The water supply flow rate for the water supply regulating valve; The saturated steam output flow rate for the steam outlet; The mixed water flow rate is the flow rate of the pipeline between the first three-way valve and the booster pump; This refers to the outlet temperature of the water-side channel of the gas cooler. The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

5. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, It also includes: a saturated steam output pressure PID control module, used to control the opening of the water-side throttle valve (9) according to the steam output pressure correlation; The correlation for the steam production pressure is as follows: ； In the formula, The saturated steam output pressure for the steam outlet; The pressure of the two-phase fluid after the water-side throttling valve; The pressure of the water after being pressurized by a booster pump; The water supply flow rate for the water supply regulating valve; The temperature of the water after being pressurized by a booster pump; These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

6. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, Also includes: The mixing tank outlet water temperature PID control module is used to control the opening degree of the high temperature cooling water inlet regulating valve (22) and the low temperature cooling water inlet regulating valve (23) according to the mixing tank outlet water temperature correlation. The correlation formula for the outlet water temperature of the mixing tank is as follows: ; In the formula, The outlet water temperature of the mixing tank; This refers to the inlet flow rate of the high-temperature cooling water. This refers to the inlet temperature of the high-temperature cooling water. This refers to the chilled water return flow rate. This refers to the chilled water return temperature. This refers to the inlet flow rate of the low-temperature cooling water. This refers to the inlet temperature of the low-temperature cooling water. These are the empirical coefficients determined through system characteristic analysis and fitting of experimental data.

7. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, Also includes: The first flow meter (26) is installed on the pipeline where the water supply pump (7) is located, and is used to detect the water supply flow rate; The first pressure sensor (27) and the first temperature sensor (28) are installed on the pipeline between the pressurized water pump (8) and the gas cooler (2) to detect the pressure and temperature of the water after pressurization, respectively. The second temperature sensor (29) is installed on the pipeline between the gas cooler (2) and the water-side throttle valve (9) to detect the outlet temperature of the water-side channel of the gas cooler. The second pressure sensor (30) and the second flow meter (31) are installed on the pipeline between the water-side throttling valve (9) and the flash tank (6) to detect the pressure and flow rate of the two-phase fluid after throttling, respectively. The third pressure sensor (34) and the third flow meter (35) are installed on the pipeline between the flash tank and the still, and are used to detect the saturated steam output pressure and flow rate respectively. The fifth flow meter (42) and the eighth temperature sensor (43) are installed on the pipeline between the high-temperature cooling water inlet regulating valve (22) and the mixing tank (14) to detect the high-temperature cooling water inlet flow rate and temperature respectively. The sixth flow meter (44) and the ninth temperature sensor (45) are installed on the pipeline between the low-temperature cooling water inlet regulating valve (23) and the mixing tank (14) to detect the low-temperature cooling water inlet flow rate and temperature respectively. The seventh flow meter (46) and the tenth temperature sensor (47) are installed on the pipeline between the chilled water return shut-off valve (24) and the mixing tank (14) to detect the chilled water return flow rate and temperature respectively. The third temperature sensor (32) is installed on the pipeline between the low-temperature CO2 side channel of the CO2 side regenerator (3) and the fifth three-way valve (19) to detect the temperature of the CO2 working fluid after regeneration. The fourth temperature sensor (33) is located at the outlet of the mixing tank (14) and is used to detect the outlet temperature of the mixing tank. The fifth temperature sensor (36) and the fourth pressure sensor (37) are installed on the pipeline between the fifth three-way valve (19) and the compressor (1) to detect the compressor suction temperature and suction pressure respectively. The sixth temperature sensor (38) and the fifth pressure sensor (39) are installed on the pipeline between the compressor (1) and the gas cooler (2) to detect the compressor exhaust temperature and exhaust pressure respectively. The fourth flow meter (40) is installed on the pipeline between the fourth three-way valve (18) and the regenerator bypass valve (20) to detect the flow rate of CO2 working fluid flowing through the regenerator bypass valve; The seventh temperature sensor (41) is installed on the pipeline between the evaporator (5) and the fourth three-way valve (18) to detect the CO2 side outlet temperature of the evaporator.

8. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, The pressure of the saturated steam output by the flash tank (6) is 0.2MPa to 0.5MPa; the outlet water temperature of the mixing tank (14) is controlled at 20℃ to 28℃.

9. A high-temperature CO2 heat pump steam generation system for the brewing industry according to claim 1, characterized in that, A chilled water return valve (24) is provided at the chilled water return inlet; a chilled water supply valve (25) is provided between the first outlet of the third three-way valve (17) and the chilled water supply outlet.

10. A method of operating a high-temperature CO2 heat pump steam generation system for the brewing industry according to any one of claims 1 to 9, characterized in that, include: After being compressed into a high-temperature, high-pressure supercritical fluid by the compressor (1), the CO2 working fluid enters the CO2 side channel of the gas cooler (2) and undergoes countercurrent heat exchange with the pressurized water flowing through the water side channel of the gas cooler (2). After releasing heat and cooling down, the CO2 working fluid enters the CO2 side channel of the evaporator (5) after being throttled and depressurized by the high-temperature CO2 side channel of the CO2 side regenerator (3) and the CO2 side throttle valve (4). It absorbs the residual heat of the cooling water flowing through the cooling water side channel of the evaporator (5) and heats up. The heated CO2 working fluid is then split by the fourth three-way valve (18). One part is heated by heat exchange through the low-temperature CO2 side channel of the CO2 side regenerator (3), and the other part is bypassed by the regenerator bypass valve (20). The two paths merge and flow back to the inlet of the compressor (1), completing the CO2 transcritical cycle. The flow distribution ratio of the two CO2 working fluids is controlled by adjusting the opening of the regenerator bypass valve (20). External water is pumped by water pump (7) and water regulating valve (21) into the first three-way valve (15), where it mixes with saturated water from the saturated water outlet of flash tank (6) to form mixed water. The mixed water is pressurized by pressurizing water pump (8) and sent to the water side channel of gas cooler (2), where it absorbs the heat released by CO2 working medium and becomes high-temperature pressurized water. The high-temperature pressurized water is throttled and depressurized by water side throttle valve (9) and then enters flash tank (6) to complete flash separation, producing saturated steam and saturated water. The saturated steam is sent to the steam side inlet of cooler (11) through the steam channel of still (10) and condenses into raw wine in cooler (11). The saturated water flows back to the first three-way valve (15) to mix with external water and is recycled. Cooling water from the mixing tank (14) enters the cooling water side channel of the cooler (11). After absorbing the heat released by the condensation of alcohol vapor, the temperature rises. The heated cooling water is divided by the second three-way valve (16). Part of it flows back to the high-temperature cooling water inlet of the mixing tank (14) through the high-temperature cooling water inlet regulating valve (22), and the other part enters the cooling water side channel of the evaporator (5), where it releases heat and cools down to become low-temperature cooling water. The low-temperature cooling water is sent to the third three-way valve (16) by the cooling water circulation pump (12). 7) Part of the water is supplied through the chilled water outlet for air conditioning in the plant area, and the other part is stored in the cold storage tank (13) and then flows back to the low temperature cooling water inlet of the mixing tank (14) after passing through the low temperature cooling water inlet regulating valve (23); the chilled water return flows back to the chilled water return inlet of the mixing tank (14) through the chilled water return outlet; by adjusting the opening of the high temperature cooling water inlet regulating valve (22) and the low temperature cooling water inlet regulating valve (23), the outlet water temperature of the mixing tank (14) is controlled to be stable at the set value.

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