Waste heat recovery cold and heat combined supply system based on organic Rankine cycle

Abstract

The invention provides a waste heat recovery cold and heat combined supply system based on an organic Rankine cycle, and relates to the technical field of waste heat recovery and cold and heat combined supply. The organic Rankine cycle module comprises a first evaporator, an expansion machine, a first condenser and a first working medium pump; wherein the first evaporator is connected with the boiler waste heat recovery module, the expansion machine is connected with the first evaporator, the first condenser is connected with the expansion machine, and the first working medium pump is connected with the first condenser and the first evaporator; the combined cooling and heating module comprises a second evaporator, a second working medium pump, a second condenser, a compressor and a motor; the cold and heat switching module comprises a heat supply switching valve group and a cold supply switching valve group; the heat supply switching valve set is used for controlling the combined cold and heat supply module to supply heat, the cold supply switching valve set is used for controlling the combined cold and heat supply module to supply cold, waste heat discharged by the boiler can be fully utilized, switching of heat supply and cold supply is achieved through the combined cold and heat supply module, and the energy utilization rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of waste heat recovery and combined cooling and heating, and in particular to a waste heat recovery combined cooling and heating system based on an organic Rankine cycle. Background Art

[0002] In the industrial production process, boilers and other equipment will generate a large amount of waste heat, which is usually discharged in the form of waste heat, which not only causes energy waste, but also causes certain thermal pollution to the environment. Although traditional waste heat recovery technology can recover part of the heat, it often has problems such as low recovery efficiency, complex system, and high cost. In addition, most of the existing waste heat recovery systems can only provide heat energy or cold energy alone, and cannot meet the needs of combined heat and cold supply at the same time. Therefore, it is of great practical significance to develop a waste heat recovery system that is efficient, energy-saving, and can achieve combined heat and cold supply. Summary of the invention

[0003] The present invention provides a waste heat recovery combined cooling and heating system based on an organic Rankine cycle, which is used to solve the technical problem that combined cooling and heating cannot be achieved in the prior art.

[0004] In one aspect, the present invention provides a waste heat recovery and combined cooling and heating system based on an organic Rankine cycle, comprising: Boiler waste heat recovery module, used to provide driving heat source; An organic Rankine cycle module, comprising a first evaporator, an expander, a first condenser and a first working fluid pump; wherein the first evaporator is connected to the boiler waste heat recovery module, the expander is connected to the first evaporator, the first condenser is connected to the expander, and the first working fluid pump is connected to the first condenser and the first evaporator respectively; A combined cooling and heating module, comprising a second evaporator, a second working fluid pump, a second condenser, a compressor and a motor; wherein the motor is connected to the expander and the compressor respectively, the second condenser is connected to the compressor and the second evaporator respectively, and the second working fluid pump is connected to the second evaporator and the compressor respectively; The hot and cold switching module comprises a heating switching valve group and a cooling switching valve group; wherein the heating switching valve group is used to control the heating of the combined cooling and heating module, and the cooling switching valve group is used to control the cooling of the combined cooling and heating module.

[0005] According to a waste heat recovery cooling and heating system based on an organic Rankine cycle provided by the present invention, the heating switching valve group includes a first valve, a third valve, a condenser and a steam-water heat exchanger, and the cooling switching valve group includes a second valve and a fourth valve; The steam-water heat exchanger is connected to the water supply pipeline of the combined cooling and heating network and the third valve respectively, the third valve is connected to the second condenser, one end of the fourth valve is connected to the water supply pipeline of the combined cooling and heating network, and the other end is connected between the second condenser and the third valve; The first valve is connected to the return water pipeline of the combined cooling and heating network and the condenser respectively, the condenser is connected to the second condenser, one end of the second valve is connected to the return water pipeline of the combined cooling and heating network, and the other end is connected to the second evaporator; At the preset heating time, the first valve and the third valve are opened, and the second valve and the fourth valve are closed, so that the return water from the combined cooling and heating network passes through the condenser, the second condenser and the steam-water heat exchanger to supply heat to the outside; During the preset cooling time, the second valve and the fourth valve are opened, and the first valve and the third valve are closed, so that the return water from the combined cooling and heating network enters the second evaporator and supplies cooling to the outside after the temperature is lowered.

[0006] According to a waste heat recovery cooling and heating system based on an organic Rankine cycle provided by the present invention, the heating switching valve group further includes a low-pressure cylinder, and the low-pressure cylinder is connected to the condenser.

[0007] According to a waste heat recovery cooling and heating system based on an organic Rankine cycle provided by the present invention, the boiler waste heat recovery module includes a boiler exhaust pipe and an expansion tank; Wherein, the flash steam of the expansion vessel is produced by flash evaporation of boiler wastewater; The second evaporator is connected to the expansion tank, and the second evaporator uses the expansion water of the expansion tank as a low-level heat source to recover the waste heat of the expansion water; The second condenser is connected to a cooling tower, uses circulating water from the cooling tower as a high-level heat source, and releases heat through the cooling tower.

[0008] According to a waste heat recovery combined heat and cooling system based on an organic Rankine cycle provided by the present invention, the compressor of the combined heat and cooling module is driven by the expander, and when the output power of the expander does not meet the power consumption of the compressor, the motor and the expander are controlled to jointly drive the compressor.

[0009] According to a waste heat recovery and combined heat and cold supply system based on an organic Rankine cycle provided by the present invention, the expander is connected to a power-consuming component driven by a small steam turbine of a power plant. During a preset non-heating or cooling time, the expander and the small steam turbine of the power plant jointly drive the power-consuming component to reduce the load of the small steam turbine of the power plant.

[0010] According to a waste heat recovery and cooling and heating system based on an organic Rankine cycle provided by the present invention, the organic Rankine cycle module further includes: The working medium flow regulating unit dynamically regulates the flow of the working medium in the first evaporator according to the heat source temperature and pressure provided by the boiler waste heat recovery module and the operation requirements of the combined cooling and heating module.

[0011] According to a waste heat recovery and combined heat and cold supply system based on an organic Rankine cycle provided by the present invention, the flow rate of the working medium in the first evaporator is dynamically adjusted according to the heat source temperature and pressure provided by the boiler waste heat recovery module and the operation requirements of the combined heat and cold supply module, including: The working fluid flow regulating unit includes a flow sensor, a temperature sensor, a pressure sensor, and a regulating valve; The flow sensor, the temperature sensor and the pressure sensor are respectively installed at the inlet and outlet of the first evaporator, and are used to monitor the flow rate, temperature and pressure of the working medium entering and leaving the first evaporator in real time; Calculate the current heat load of the first evaporator according to the real-time data collected by the flow sensor, the temperature sensor, and the pressure sensor, and compare it with a preset heat load target value; When the current heat load is lower than the preset heat load target value, increasing the flow rate of the working medium in the first evaporator through the regulating valve; When the current heat load is higher than the preset heat load target value, the flow rate of the working medium in the first evaporator is reduced by adjusting the valve.

[0012] According to the present invention, a waste heat recovery cooling and heating system based on an organic Rankine cycle further includes: Dynamically adjusting the preset heat load target value according to the operation demand of the combined cooling and heating module includes: When the mechanical energy required by the combined cooling and heating module increases, increasing the preset heat load target value; When the mechanical energy required by the combined cooling and heating module decreases, the preset heat load target value is reduced.

[0013] According to a waste heat recovery cooling and heating system based on an organic Rankine cycle provided by the present invention, the working fluid flow regulating unit further includes: a fault diagnosis subunit, configured to monitor the operating state of the organic Rankine cycle module in real time, and diagnose whether the organic Rankine cycle module has a fault or an abnormal operating state based on the real-time data collected by the flow sensor, the temperature sensor, and the pressure sensor; The fault-tolerant control subunit automatically switches to a fault-tolerant operation mode when the fault diagnosis subunit detects a fault or an abnormal operation state. The adjustment logic of the fault-tolerant operation mode includes: When the heat exchange efficiency of the first evaporator decreases, increasing the flow rate of the working medium in the first evaporator through the regulating valve to maintain the output power of the organic Rankine cycle module; When the output power of the expander decreases, the flow rate of the working medium in the first evaporator is reduced by the regulating valve to reduce the load of the expander, and the auxiliary power of the motor is increased to ensure the normal operation of the combined cooling and heating module; When the cooling effect of the first condenser decreases, the flow rate of the working medium in the first evaporator is reduced by the regulating valve to reduce the heat load of the first condenser, and the backup cooling system is started at the same time to ensure the stable operation of the organic Rankine cycle module.

[0014] The waste heat recovery and combined heat and cold supply system based on the organic Rankine cycle provided by the present invention realizes the functions of efficient waste heat recovery and combined heat and cold supply through the organic combination of the boiler waste heat recovery module, the organic Rankine cycle module, the combined heat and cold supply module and the combined heat and cold switch module. The system can make full use of the waste heat discharged by the boiler, drive the organic Rankine cycle to generate mechanical energy, and realize the switching of heating and cooling through the combined heat and cold supply module, thereby improving the energy utilization efficiency, reducing energy consumption, and meeting the heating and cooling needs in different scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 is a structural schematic diagram of a waste heat recovery cooling and heating system based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 2 is a structural schematic diagram of a heating operation based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 3 is a structural schematic diagram of a cooling operation based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 4 It is a structural schematic diagram of non-heating and cooling operation based on the organic Rankine cycle provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Figure 1 is a structural schematic diagram of a waste heat recovery cooling and heating system based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 2 is a structural schematic diagram of a heating operation based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 3 is a structural schematic diagram of a cooling operation based on an organic Rankine cycle provided in an embodiment of the present invention; Figure 4 It is a structural schematic diagram of non-heating and cooling operation based on the organic Rankine cycle provided in an embodiment of the present invention.

[0019] Figure 1 In the figure, different types of connecting lines can represent different types of operating functions. For example, a solid line represents return water or water supply of a combined cooling and heating network. Those skilled in the art can understand various types of connecting lines, which will not be introduced one by one here.

[0020] See also Figure 1 The waste heat recovery and combined heat and cold supply system 100 based on an organic Rankine cycle (ORC) may include a boiler waste heat recovery module 20 , an organic Rankine cycle module 30 , a combined heat and cold supply module 40 and a heat and cold switching module 50 .

[0021] The boiler waste heat recovery module 20 is used to provide a driving heat source.

[0022] The organic Rankine cycle module 30 includes a first evaporator 301, an expander 302, a first condenser 303 and a first working fluid pump 304; wherein the first evaporator 301 is connected to the boiler waste heat recovery module 20, the expander 302 is connected to the first evaporator 301, the first condenser 303 is connected to the expander 302, and the first working fluid pump 304 is respectively connected to the first condenser 303 and the first evaporator 301.

[0023] The combined cooling and heating module 40 includes a second evaporator 401, a second working fluid pump 402, a second condenser 403, a compressor 404 and a motor 405; wherein the motor 405 is connected to the expander 302 and the compressor 404 respectively, the second condenser 403 is connected to the compressor 404 and the second evaporator 401 respectively, and the second working fluid pump 402 is connected to the second evaporator 401 and the compressor 404 respectively.

[0024] The heat-cold switching module 50 includes a heat supply switching valve group and a cool supply switching valve group; wherein the heat supply switching valve group is used to control the heat supply of the combined heat and cold supply module 40, and the cool supply switching valve group is used to control the cool supply of the combined heat and cold supply module 40.

[0025] In this embodiment, the functions of efficient waste heat recovery and combined cooling and heating are realized through the organic combination of the boiler waste heat recovery module 20, the organic Rankine cycle module 30, the combined cooling and heating module 40 and the combined cooling and heating switching module 50. The waste heat recovery combined cooling and heating system 100 can make full use of the waste heat discharged by the boiler 702, drive the organic Rankine cycle to generate mechanical energy, and realize the switching between heating and cooling through the combined cooling and heating module 40, thereby improving energy utilization efficiency, reducing energy consumption, and meeting the cooling and heating needs in different scenarios.

[0026] In one embodiment of the present specification, the heating switching valve group includes a first valve 501, a third valve 502, a condenser 503 and a steam-water heat exchanger 504, and the cooling switching valve group includes a second valve 505 and a fourth valve 506; The steam-water heat exchanger 504 is connected to the combined cooling and heating network water supply pipeline 601 and the third valve 502 respectively, the third valve 502 is connected to the second condenser 403, one end of the fourth valve 506 is connected to the combined cooling and heating network water supply pipeline 601, and the other end is connected between the second condenser 403 and the third valve 502; The first valve 501 is connected to the combined cooling and heating network return water pipe 602 and the condenser 503 respectively, the condenser 503 is connected to the second condenser 403, one end of the second valve 505 is connected to the combined cooling and heating network return water pipe 602, and the other end is connected to the second evaporator 401; At the preset heating time, the first valve 501 and the third valve 502 are opened, and the second valve 505 and the fourth valve 506 are closed, so that the return water of the combined heating and cooling network passes through the condenser 503, the second condenser 403 and the steam-water heat exchanger 504 to supply heat to the outside; During the preset cooling time, the second valve 505 and the fourth valve 506 are opened, and the first valve 501 and the third valve 502 are closed, so that the return water from the combined cooling and heating network enters the second evaporator 401 and provides cooling to the outside after the temperature is reduced.

[0027] In this embodiment, by setting the heating switching valve group and the cooling switching valve group, the combined heating and cooling module 40 is flexibly switched between the heating and cooling modes. This design enables the system to accurately control the cooling and heating supply according to actual needs, improves the operating efficiency and reliability of the system, and reduces energy waste. The preset heating time generally refers to winter, and the preset cooling time generally refers to summer. The specific time range can be set according to the actual local climate, and no specific limitation is made here.

[0028] An example of a heating case is shown below: Open the first valve 501 and the third valve 502, and close the second valve 505 and the fourth valve 506. The 50°C heat network return water first enters the condenser 503 of the high back pressure turbine for heating (turbine back pressure 35kpa), and is heated to 60°C; then enters the second condenser 403, is heated to 70°C, and finally enters the steam-water heat exchanger 504, is heated to 100°C by the turbine exhaust, and supplies heat to the outside. Under the heating condition, the second evaporator 401 uses the expansion water (50°C) of the expansion tank 202 as the low-level heat source to recover the waste heat of the expansion water. The expansion water comes from the wastewater of the boiler 702. After the wastewater of the boiler 702 is flashed in the expansion tank 202, 140°C flash steam and 50°C expansion water are output to the outside. Flash steam and exhaust gas from boiler 702 serve together as the driving heat source for ORC, and expansion water serves as the low-level heat source for the heat pump cycle, providing heat after the energy quality is increased by the heat pump.

[0029] An example of a cooling condition is shown below: Open the second valve 505 and the fourth valve 506, and close the first valve 501 and the third valve 502. The return water from the cold network enters the second evaporator 401, and after the temperature drops to 5°C, it is output to the outside for cold water supply. Under the cooling condition, the second condenser 403 uses the circulating water of the cooling tower 701 as the high-level heat source, and relies on the cooling tower 701 to take away the heat of the return water from the cold network.

[0030] In one embodiment of the present specification, the heating switching valve group further includes a low-pressure cylinder 507 , and the low-pressure cylinder 507 is connected to the condenser 503 .

[0031] In this embodiment, a low-pressure cylinder 507 is added to the heating switching valve group and connected to the condenser 503, which further optimizes the heating process. By utilizing the characteristics of the low-pressure cylinder 507, the heating capacity and thermal energy utilization efficiency of the system are improved, thereby enhancing the overall performance of the system.

[0032] In one embodiment of the present specification, the boiler waste heat recovery module 20 includes a boiler exhaust pipe (not shown) and an expansion tank 202; The flash steam of the expansion tank 202 is generated by flash evaporation of the blowdown water of the boiler 702; The second evaporator 401 is connected to the expansion tank 202. The second evaporator 401 uses the expansion water in the expansion tank 202 as a low-level heat source to recover the waste heat of the expansion water. The second condenser 403 is connected to the cooling tower 701 , and uses the circulating water of the cooling tower 701 as a high-level heat source to release heat through the cooling tower 701 .

[0033] In this embodiment, a boiler smoke exhaust pipe and an expansion tank 202 are introduced, and the flash steam of the expansion tank 202 is used to generate expansion water as a low-level heat source. This design not only improves the efficiency of waste heat recovery, but also further reduces the energy consumption of the system by rationally utilizing the waste heat of the expansion water, while realizing deep recovery of the waste heat of the boiler 702.

[0034] A low-level heat source refers to a heat energy source with a lower temperature, and its temperature is usually lower than that of other heat sources in the system. The heat of a low-level heat source is usually not enough to directly drive certain thermal equipment, but it can be effectively utilized through a suitable thermodynamic cycle (such as an organic Rankine cycle). The low-level heat source comes from the expansion water of the expansion tank 202. The expansion water is produced by flash evaporation of the wastewater from the boiler 702, and its temperature is relatively low, but it still has a certain amount of thermal energy. The low-level heat source (expansion water) is used in the second evaporator 401 as one of the heat sources in the organic Rankine cycle. Through heat exchange with the working fluid, the heat of the low-level heat source is absorbed, causing the working fluid to evaporate and drive the expander 302 to do work, thereby realizing the effective utilization of waste heat.

[0035] A high-level heat source refers to a heat energy source with a higher temperature, which usually has sufficient temperature and heat energy to directly drive thermal equipment or perform heat exchange. The temperature and heat energy level of a high-level heat source are usually higher than those of a low-level heat source, so it has a higher utilization value in a thermal system. The high-level heat source comes from the circulating water of the cooling tower 701. The circulating water of the cooling tower 701 absorbs a large amount of heat during the cooling process, and its temperature is relatively high. The high-level heat source (circulating water of the cooling tower 701) is used in the second condenser 403 as a heat source for the combined heat and cold supply module 40. Through heat exchange with the working fluid, the heat of the high-level heat source is released to the condenser for heating or cooling. At the same time, the circulating water of the cooling tower 701 lowers its own temperature by releasing heat, completing the cooling cycle.

[0036] In one embodiment of the present specification, the compressor 404 of the combined cooling and heating module 40 is driven by the expander 302 . When the output power of the expander 302 does not meet the power consumption of the compressor 404 , the motor 405 is controlled to drive the compressor 404 together with the expander 302 .

[0037] In this embodiment, the compressor 404 of the combined cooling and heating module 40 is driven by the expander 302. When the output power of the expander 302 is insufficient, the motor 405 and the expander 302 jointly drive the compressor 404. This design makes full use of the mechanical energy generated by the organic Rankine cycle, reduces dependence on external electric energy, reduces the operating cost of the system, and improves the energy self-sufficiency rate of the system.

[0038] In one embodiment of the present specification, the expander 302 is connected to a power-consuming component 406 driven by a small steam turbine of a power plant. During a preset non-heating or non-cooling time, the expander 302 and the small steam turbine of the power plant jointly drive the power-consuming component 406 to reduce the load of the small steam turbine of the power plant.

[0039] In this embodiment, the application scenario of the expander 302 is further expanded, so that it can drive the power-consuming component 406 together with the small steam turbine of the power plant during non-heating and cooling time to reduce the load of the small steam turbine. This improvement not only improves the flexibility and adaptability of the system, but also further optimizes the energy utilization efficiency of the power plant and reduces energy waste. The preset non-heating and cooling time can refer to spring and autumn. The specific time range can be set according to the actual local climate and is not specifically limited here. The power-consuming component 406 can generally include a feed water pump and an induced draft fan.

[0040] In one embodiment of the present specification, the organic Rankine cycle module 30 further includes: The working medium flow regulating unit (not shown in the figure) dynamically regulates the flow of the working medium in the first evaporator 301 according to the heat source temperature and pressure provided by the boiler waste heat recovery module 20 and the operation requirements of the combined heat and cold supply module 40 .

[0041] In this embodiment, a working fluid flow regulating unit is introduced, which can dynamically adjust the flow of the working fluid in the first evaporator 301 according to the temperature and pressure of the heat source provided by the boiler waste heat recovery module 20 and the operating requirements of the combined heat and cold supply module 40. This design enables the system to adapt to different working conditions in real time, optimize the operating efficiency of the organic Rankine cycle, and improve the stability and reliability of the system. The operating requirements generally include dynamically adjusting the operating capacity of the heat pump or refrigeration cycle according to changes in heating or cooling demand, dynamically adjusting the mechanical energy supply according to the output power of the ORC expander and the power consumption requirements of the compressor, adapting to changes in the heat source conditions provided by the boiler waste heat recovery module, and maintaining the stable operation of the system.

[0042] In one embodiment of the present specification, dynamically adjusting the flow rate of the working medium in the first evaporator according to the heat source temperature and pressure provided by the boiler waste heat recovery module and the operation requirements of the combined cooling and heating module includes: The working fluid flow regulating unit includes a flow sensor, a temperature sensor, a pressure sensor, and a regulating valve; The flow sensor, temperature sensor and pressure sensor are respectively installed at the inlet and outlet of the first evaporator 301 to monitor the flow rate, temperature and pressure of the working fluid entering and leaving the first evaporator 301 in real time; Calculate the current heat load of the first evaporator 301 according to the real-time data collected by the flow sensor, the temperature sensor, and the pressure sensor, and compare it with the preset heat load target value; When the current heat load is lower than the preset heat load target value, it is determined that the temperature or pressure of the heat source provided by the boiler waste heat recovery module 20 is lower than the preset threshold value, and the flow rate of the working medium in the first evaporator 301 is increased through the regulating valve; When the current heat load is higher than the preset heat load target value, it is determined that the heat source temperature or pressure provided by the boiler waste heat recovery module 20 is higher than the preset threshold value, and the flow rate of the working medium in the first evaporator 301 is reduced by adjusting the valve.

[0043] In this embodiment, the composition and working principle of the working medium flow regulating unit are further refined, and the precise control of the organic Rankine cycle module 30 is achieved through the synergistic effect of the flow sensor, temperature sensor, pressure sensor and regulating valve. This design not only improves the automation of the system, but also can dynamically adjust the working medium flow according to real-time data, further optimizing the operating efficiency of the system. The regulating valve can be installed at the inlet of the first evaporator 301 to control the working medium flow entering the evaporator.

[0044] In one embodiment of this specification, it also includes: Dynamically adjusting the preset heat load target value according to the operation demand of the combined cooling and heating module 40 includes: When the mechanical energy required by the combined cooling and heating module 40 increases, the preset heat load target value is increased; When the mechanical energy required by the combined cooling and heating module 40 decreases, the preset heat load target value is lowered.

[0045] In this embodiment, the heat load target value is adjusted in real time according to the operating requirements of the combined cooling and heating module 40. This design enables the system to better adapt to different cooling and heating requirements, further improves the flexibility and adaptability of the system, and optimizes energy utilization efficiency.

[0046] In one embodiment of the present specification, the working fluid flow regulating unit further includes a fault diagnosis subunit and a fault-tolerant control subunit.

[0047] The fault diagnosis subunit is used to monitor the operating state of the organic Rankine cycle module 30 (including the first evaporator 301, the expander 302, the first condenser 303 and the first working fluid pump 304) in real time, and diagnose whether the organic Rankine cycle module 30 has a fault or an abnormal operating state based on the real-time data collected by the flow sensor, the temperature sensor and the pressure sensor; The fault-tolerant control subunit is used to automatically switch to the fault-tolerant operation mode when the fault diagnosis subunit detects a fault or abnormal operation state. The adjustment logic of the fault-tolerant operation mode includes: When the heat exchange efficiency of the first evaporator 301 decreases, the flow rate of the working medium in the first evaporator 301 is increased by the regulating valve to maintain the output power of the organic Rankine cycle module 30; When the output power of the expander 302 decreases, the flow rate of the working medium in the first evaporator 301 is reduced through the regulating valve to reduce the load of the expander 302, and at the same time, the auxiliary power of the motor 405 is increased to ensure the normal operation of the combined cooling and heating module 40; When the cooling effect of the first condenser 303 decreases, the flow rate of the working medium in the first evaporator 301 is reduced by adjusting the valve to reduce the heat load of the first condenser 303 , and the backup cooling system is started at the same time to ensure the stable operation of the organic Rankine cycle module 30 .

[0048] In this embodiment, a fault diagnosis subunit and a fault-tolerant control subunit are introduced. When the system fails or operates abnormally, it can automatically switch to the fault-tolerant operation mode, and ensure the stable operation of the system by adjusting the working fluid flow, increasing auxiliary power, or starting the backup cooling system. This design greatly improves the reliability and safety of the system and reduces the downtime and maintenance costs caused by failures.

[0049] Example 1: Evaporator fouling leads to decreased heat exchange efficiency: Fault diagnosis: The flow sensor and the temperature sensor detect that the outlet temperature of the first evaporator 301 is higher than the normal value, indicating that the heat exchange efficiency is reduced.

[0050] Fault-tolerant control: The regulating valve automatically increases the working fluid flow rate to increase the heat absorption of the evaporator.

[0051] The system records the fault information and prompts the maintenance personnel to check the evaporator.

[0052] Example 2: The output power of expander 302 is insufficient: Fault diagnosis: The power sensor detects that the output power of the expander 302 is lower than a preset threshold.

[0053] Fault-tolerant control: The regulating valve reduces the flow of the working fluid and reduces the load of the expander 302.

[0054] The motor 405 increases auxiliary power to ensure the normal operation of the compressor 404 .

[0055] The system records the fault information and prompts the maintenance personnel to check the expander 302.

[0056] Example 3: Condenser cooling effect decreased: Fault diagnosis: The temperature sensor detects that the outlet temperature of the first condenser 303 is higher than the normal value, indicating that the cooling effect is reduced.

[0057] Fault-tolerant control: The regulating valve reduces the working fluid flow rate and reduces the heat load of the condenser.

[0058] Start the backup cooling fan to enhance the cooling effect.

[0059] The system records the fault information and prompts the maintenance personnel to check the condenser.

[0060] Specific working process of ORC cycle: ORC cycle working fluid is R245fa (C3H3F5), and its driving heat source is the exhaust gas of boiler 702 at about 140°C and the flash gas of expansion tank 202, both of which are waste heat of boiler 702. After the temperature and pressure of R245fa are increased in the first evaporator 301, it enters the expander 302 to expand and do work. After doing work, R245fa evaporates into exhaust steam, which enters the first condenser 303 to condense into liquid phase, and then enters the first working fluid pump 304 to increase pressure. The pressurized liquid phase R245fa enters the first evaporator 301 again to complete the entire power cycle.

[0061] The expander 302 of the ORC cycle performs work externally throughout the year. In the heating season, the expander 302 assists the motor 405 to drive the compressor 404; in the cooling season, the expander 302 assists the motor 405 to drive the compressor 404 of the refrigeration cycle; in the non-heating and cooling season, the expander 302 assists the small steam turbine of the power plant to drive the feed water pump, induced draft fan and other power-consuming components 406. Small steam turbines are usually driven by reheated steam or main steam turbine exhaust. Reducing the load of the small steam turbine can increase the power of the main steam turbine, and can achieve energy cascade utilization and year-round waste heat recovery of the boiler 702.

[0062] Specific working process of heat pump / refrigeration cycle: The working fluid of heat pump / refrigeration cycle is R410A (R32 (CH2F2) and R125 (C2HF5) are mixed at a mass fraction of 50:50). Compressor 404 is driven by expander 302 of ORC cycle. When the output power of expander 302 does not meet the power consumption of compressor 404, motor 405 intervenes and drives compressor 404 together with expander 302. In the heating season, the heat pump recovers the waste heat of expansion water from the expansion tank 202 of the power plant, improves the energy quality, and assists in heating the return water; in the cooling season, the refrigeration cycle uses the circulating cooling water of the power plant as the high-level heat source, releases the return water heat of the cold network through the cooling tower 701, and outputs cold to the outside. An expansion valve 407 is connected between the second evaporator 401 and the second condenser 403 to adjust the flow.

[0063] The device embodiments described above are merely illustrative, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative labor.

[0064] Through the description of the above implementation methods, those skilled in the art can clearly understand that each implementation method can be implemented by means of software plus a necessary general hardware platform, and of course, can also be implemented by hardware. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, a disk, an optical disk, etc., including a number of instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0065] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A waste heat recovery and combined cooling and heating system based on an organic Rankine cycle, characterized in that: include: Boiler waste heat recovery module, used to provide driving heat source; An organic Rankine cycle module, comprising a first evaporator, an expander, a first condenser and a first working fluid pump; wherein the first evaporator is connected to the boiler waste heat recovery module, the expander is connected to the first evaporator, the first condenser is connected to the expander, and the first working fluid pump is connected to the first condenser and the first evaporator respectively; A combined cooling and heating module, comprising a second evaporator, a second working fluid pump, a second condenser, a compressor and a motor; wherein the motor is connected to the expander and the compressor respectively, the second condenser is connected to the compressor and the second evaporator respectively, and the second working fluid pump is connected to the second evaporator and the compressor respectively; The hot and cold switching module comprises a heating switching valve group and a cooling switching valve group; wherein the heating switching valve group is used to control the heating of the combined cooling and heating module, and the cooling switching valve group is used to control the cooling of the combined cooling and heating module.

2. The waste heat recovery and cooling and heating system based on the organic Rankine cycle according to claim 1 is characterized in that: The heating switching valve group includes a first valve, a third valve, a condenser and a steam-water heat exchanger, and the cooling switching valve group includes a second valve and a fourth valve; The steam-water heat exchanger is connected to the water supply pipeline of the combined cooling and heating network and the third valve respectively, the third valve is connected to the second condenser, one end of the fourth valve is connected to the water supply pipeline of the combined cooling and heating network, and the other end is connected between the second condenser and the third valve; The first valve is connected to the return water pipeline of the combined cooling and heating network and the condenser respectively, the condenser is connected to the second condenser, one end of the second valve is connected to the return water pipeline of the combined cooling and heating network, and the other end is connected to the second evaporator; At the preset heating time, the first valve and the third valve are opened, and the second valve and the fourth valve are closed, so that the return water from the combined cooling and heating network passes through the condenser, the second condenser and the steam-water heat exchanger to supply heat to the outside; During the preset cooling time, the second valve and the fourth valve are opened, and the first valve and the third valve are closed, so that the return water from the combined cooling and heating network enters the second evaporator and supplies cooling to the outside after the temperature is lowered.

3. The waste heat recovery and cooling and heating system based on organic Rankine cycle according to claim 2 is characterized in that: The heating switching valve group also includes a low-pressure cylinder, and the low-pressure cylinder is connected to the condenser.

4. The waste heat recovery and cooling and heating system based on the organic Rankine cycle according to claim 1 is characterized in that: The boiler waste heat recovery module includes a boiler exhaust pipe and an expansion tank; Wherein, the flash steam of the expansion vessel is produced by flash evaporation of boiler wastewater; The second evaporator is connected to the expansion tank, and the second evaporator uses the expansion water of the expansion tank as a low-level heat source to recover the waste heat of the expansion water; The second condenser is connected to a cooling tower, uses circulating water from the cooling tower as a high-level heat source, and releases heat through the cooling tower.

5. The waste heat recovery and cooling and heating system based on organic Rankine cycle according to claim 1 is characterized in that: The compressor of the combined cooling and heating module is driven by the expander. When the output power of the expander does not meet the power consumption of the compressor, the motor is controlled to jointly drive the compressor with the expander.

6. The waste heat recovery and cooling and heating system based on organic Rankine cycle according to claim 1 is characterized in that: The expander is connected to a power-consuming component driven by a small steam turbine of a power plant. During a preset non-heating or non-cooling time, the expander and the small steam turbine of the power plant jointly drive the power-consuming component to reduce the load of the small steam turbine of the power plant.

7. The waste heat recovery and combined cooling and heating system based on organic Rankine cycle according to claim 1 is characterized in that: The organic Rankine cycle module further comprises: The working medium flow regulating unit dynamically regulates the flow of the working medium in the first evaporator according to the heat source temperature and pressure provided by the boiler waste heat recovery module and the operation requirements of the combined cooling and heating module.

8. The waste heat recovery and cooling and heating system based on organic Rankine cycle according to claim 7 is characterized in that: According to the heat source temperature and pressure provided by the boiler waste heat recovery module and the operation requirements of the combined cooling and heating module, the flow rate of the working medium in the first evaporator is dynamically adjusted, including: The working fluid flow regulating unit includes a flow sensor, a temperature sensor, a pressure sensor, and a regulating valve; The flow sensor, the temperature sensor and the pressure sensor are respectively installed at the inlet and outlet of the first evaporator, and are used to monitor the flow rate, temperature and pressure of the working medium entering and leaving the first evaporator in real time; Calculate the current heat load of the first evaporator according to the real-time data collected by the flow sensor, the temperature sensor, and the pressure sensor, and compare it with a preset heat load target value; When the current heat load is lower than the preset heat load target value, increasing the flow rate of the working medium in the first evaporator through the regulating valve; When the current heat load is higher than the preset heat load target value, the flow rate of the working medium in the first evaporator is reduced by adjusting the valve.

9. The waste heat recovery and cooling and heating system based on the organic Rankine cycle according to claim 8 is characterized in that: Also includes: Dynamically adjusting the preset heat load target value according to the operation demand of the combined cooling and heating module includes: When the mechanical energy required by the combined cooling and heating module increases, increasing the preset heat load target value; When the mechanical energy required by the combined cooling and heating module decreases, the preset heat load target value is reduced.

10. The waste heat recovery and cooling and heating system based on the organic Rankine cycle according to claim 9 is characterized in that: The working fluid flow regulating unit also includes: a fault diagnosis subunit, configured to monitor the operating state of the organic Rankine cycle module in real time, and diagnose whether the organic Rankine cycle module has a fault or an abnormal operating state based on the real-time data collected by the flow sensor, the temperature sensor, and the pressure sensor; The fault-tolerant control subunit automatically switches to a fault-tolerant operation mode when the fault diagnosis subunit detects a fault or an abnormal operation state. The adjustment logic of the fault-tolerant operation mode includes: When the heat exchange efficiency of the first evaporator decreases, increasing the flow rate of the working medium in the first evaporator through the regulating valve to maintain the output power of the organic Rankine cycle module; When the output power of the expander decreases, the flow rate of the working medium in the first evaporator is reduced by the regulating valve to reduce the load of the expander, and the auxiliary power of the motor is increased to ensure the normal operation of the combined cooling and heating module; When the cooling effect of the first condenser decreases, the flow rate of the working medium in the first evaporator is reduced by the regulating valve to reduce the heat load of the first condenser, and the backup cooling system is started at the same time to ensure the stable operation of the organic Rankine cycle module.

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