An energy storage type high-temperature heat pump steam generation system and its control method

Abstract

The present invention discloses an energy storage type high-temperature heat pump steam generation system, which includes a cascade high-temperature heat pump module, a phase change heat storage module and a steam generation module. The cascade high-temperature heat pump module includes a first closed circulation loop formed by connecting in series an air source evaporator, a low-stage compressor, a low-stage electronic expansion valve and the low-temperature side of an inter-stage heat exchanger, and a second closed circulation loop formed by connecting in series a high-stage compressor, a condenser, a high-stage electronic expansion valve and the high-temperature side of the inter-stage heat exchanger; the phase change heat storage module includes a heat storage tank, a heat storage working medium, a heat exchange tube, a first three-way valve, a second three-way valve and a high-temperature circulation pump; the steam generation module includes a flash tank and a steam compressor. By adopting the above technical solution, during the valley electricity period, low-cost electric energy and environmental heat energy are fully utilized for heat charging and energy storage; during the peak electricity period, the stored heat energy is released for steam production, achieving the maximization of economic benefits. The present invention also provides a control method for the energy storage type high-temperature heat pump steam generation system.

Description

Technical Field

[0001] The present invention relates to the fields of petrochemical industry and energy utilization, and particularly to an energy storage type high-temperature heat pump steam generation system and its control method. The system aims to achieve efficient, stable and economical steam supply by integrating advanced cascaded high-temperature heat pump technology and phase change heat storage technology to meet the continuous demand for steam in the petrochemical production process. Background Art

[0002] In the petrochemical industry, the stable supply and efficient utilization of steam are the core links in the production process. However, traditional steam generation methods such as coal-fired boilers and gas-fired boilers can meet the basic production needs, but they face problems such as high energy consumption, serious environmental pollution and high operating costs. With the development of heat pump technology, air-source high-temperature heat pumps have been applied to steam production to a certain extent, but there are still problems such as sensitivity to ambient temperature and attenuation of heating performance. In addition, existing steam storage technologies also have defects such as large construction difficulty, high maintenance cost and significant heat energy loss. Therefore, there is an urgent need for a new type of steam generation system and its control method to solve the above technical problems. Summary of the Invention

[0003] The purpose of the present invention is to provide an energy storage type high-temperature heat pump steam generation system and its control method, which can achieve efficient production and stable supply of steam by integrating advanced cascaded high-temperature heat pump technology and phase change heat storage technology. The system can flexibly adjust the operation mode according to the electricity price change, realize efficient utilization of energy and reduction of cost, thus significantly improving the energy utilization efficiency and economic benefits in the petrochemical production process.

[0004] To solve the above technical problems, an embodiment of the present invention discloses an energy storage type high-temperature heat pump steam generation system, including: a cascaded high-temperature heat pump module, a phase change heat storage module and a steam generation module. The cascaded high-temperature heat pump module includes: a low-temperature stage circulation unit, which is formed by connecting an air-source evaporator, a low-temperature stage compressor, a low-temperature stage electronic expansion valve and the low-temperature side of an inter-stage heat exchanger in series to form a first closed circulation loop for absorbing low-grade heat energy from the environment. The low-temperature stage circulation unit is filled with a low-temperature stage working medium; a high-temperature stage circulation unit, which is formed by connecting a high-temperature stage compressor, a condenser, a high-temperature stage electronic expansion valve and the high-temperature side of the inter-stage heat exchanger in series to form a second closed circulation loop for boosting the heat energy transferred by the low-temperature stage circulation unit. The high-temperature stage circulation unit is filled with a high-temperature stage working medium; the phase change heat storage module includes a heat storage tank, a heat storage working medium, heat exchange tubes, a first three-way valve, a second three-way valve and a high-temperature circulation pump for storing or releasing the heat energy transferred by the high-temperature stage circulation unit; the steam generation module includes a flash tank and a steam compressor for converting the heat energy released by the phase change heat storage module into high-pressure steam.

[0005] Adopting the above technical solution can significantly improve the energy utilization efficiency. The cascaded high-temperature heat pump module efficiently absorbs low-grade heat energy from the environment, and further improves the efficiency through the high-temperature stage circulation unit. Combining with the energy storage and energy release functions of the phase change heat storage module, the cascade utilization of heat energy is realized, reducing energy waste and operating costs. During the valley electricity period, low-cost electric energy and environmental heat energy are fully utilized for heat charging and energy storage. During the peak electricity period, the stored heat energy is released for steam production, effectively avoiding the high electricity price period and maximizing the economic benefits. It can reduce the dependence on traditional energy. As a clean energy utilization system, the invention makes full use of the low-grade heat energy in the environment, reduces carbon emissions, meets the requirements of sustainable development, and has positive significance for environmental protection.

[0006] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed. During the valley electricity period, the inlet of the first three-way valve is connected to the outlet of the condenser, and the first outlet of the first three-way valve is connected to the inlet of the heat exchange tube. The inlet of the second three-way valve is connected to the outlet of the heat exchange tube, and the first outlet of the second three-way valve is connected to the inlet of the high-temperature circulation pump, forming a heat charging closed loop, and the cascaded high-temperature heat pump module charges heat energy into the heat storage device. During the peak electricity period, the inlet of the first three-way valve is connected to the outlet of the condenser, the second outlet of the first three-way valve is connected to the inlet of the high-temperature stage electronic expansion valve. The inlet of the second three-way valve is connected to the outlet of the heat exchange tube, and the second outlet of the second three-way valve is connected to the inlet of the high-temperature circulation pump, forming a heat release closed loop. The high-temperature circulation pump drives the heat energy released by the heat storage device to generate steam through the flash tank, and the high-pressure steam is output by the steam compressor.

[0007] Adopting the above technical solution can make full use of the electricity price difference at different times. During the valley electricity period, heat energy is stored at a lower cost, and during the peak electricity period, the stored heat energy is released for steam production, thereby effectively reducing the overall cost of steam production and improving the economy and energy utilization efficiency of the system.

[0008] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed, and the heat storage working medium is a phase change material with a phase change temperature of 80°C - 120°C.

[0009] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed, and the heat exchange tube is a serpentine copper tube covered with aluminum fins on the outside.

[0010] Adopting the above technical solution, the serpentine copper tube has good thermal conductivity and can quickly transfer heat to the heat storage working medium, while the outer aluminum fins can increase the heat exchange area and further improve the heat exchange efficiency, enabling heat energy to be transferred more efficiently between the phase change heat storage module and the steam generation module, which helps to improve the performance and efficiency of the entire system.

[0011] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed in the embodiment of the present invention. The phase change material includes hexahydrate nitrate, dimethyl fumarate, ribitol, xylitol, arabitol, erythritol, RT100.

[0012] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed in the embodiment of the present invention. The water vapor compressor is a twin-screw compressor.

[0013] Adopting the above technical solution, the twin-screw compressor has the advantages of compact structure, stable operation, high efficiency, low noise, etc. It can effectively compress the low-pressure steam generated by the flash tank into high-pressure steam, meet the demand for high-pressure steam in industrial production or other application scenarios, and at the same time reduce the maintenance cost and operation energy consumption of the equipment.

[0014] According to another specific embodiment of the present invention, an energy storage type high-temperature heat pump steam generation system is disclosed in the embodiment of the present invention. The steam generation module further includes: a steam pipeline, which is respectively connected to the top outlet of the flash tank and the inlet of the water vapor compressor; a return water channel, which extends from the bottom outlet of the flash tank to the inlet of the high-temperature circulation pump and is communicated with the outlet of the high-temperature circulation pump through the second outlet of the second three-way valve.

[0015] The embodiment of the present invention also discloses a control method for an energy storage type high-temperature heat pump steam generation system. The control method is used to control any one of the above energy storage type high-temperature heat pump steam generation systems. The control method includes the following steps:

[0016] S1. Parameter detection step

[0017] Real-time detection of the user's steam demand power Q steam , time-of-use electricity price c, ambient temperature T amb , remaining capacity C of the phase change heat storage module v , where c ∈ {c v , c p}, c v is the electricity price during the valley electricity period, c p is the electricity price during the peak electricity period and c p > c v ;

[0018] S2. Multi-module collaborative control step

[0019] Based on the detected parameters, control the collaborative operation of the cascade high-temperature heat pump module, the phase change heat storage module and the steam generation module; when Q steam > 0, according to the time-of-use electricity price c and the steam production cost F(T amb, c, t), trigger the collaborative steam supply mode of the cascaded high-temperature heat pump module and the steam generation module, or trigger the collaborative steam supply mode of the phase change heat storage module and the steam generation module, where t is the operating time of the cascaded high-temperature heat pump module; when Q steam = 0, according to the remaining capacity C of the phase change heat storage module v , time-of-use electricity price c and ambient temperature T amb , trigger the heat charging mode of the cascaded high-temperature heat pump module to the phase change heat storage module, or trigger the shutdown mode.

[0020] By adopting the above technical solution, the refined control of the energy storage type high-temperature heat pump steam generation system can be realized. According to the parameters detected in real time, the operation mode of the system can be flexibly adjusted to ensure that it can operate in the optimal way under different working conditions, thereby improving the energy utilization efficiency of the system and reducing the operation cost; it can effectively cope with the changes in electricity prices at different times and the fluctuations of environmental conditions. By reasonably triggering different steam supply modes and heat charging modes, while meeting the steam demand of users, the low-price electric energy and environmental heat energy can be utilized to the greatest extent, reducing the dependence on high-price electric energy, and improving the economy and sustainability of the system; it can enhance the stability and reliability of the system. In a complex and changeable operating environment, through real-time monitoring and intelligent control, the operating state of the system can be adjusted in time to avoid problems such as energy waste or equipment overload that may be caused by single-mode operation, and ensure the long-term stable operation of the system.

[0021] According to another specific embodiment of the present invention, the embodiment of the present invention discloses a control method for an energy storage type high-temperature heat pump steam generation system. The multi-module collaborative control step further includes: when Q steam > 0, and c = c v , trigger the collaborative steam supply mode of the cascaded high-temperature heat pump module and the steam generation module; when Q steam > 0, and c = c p , execute according to the following rules: the steam production cost F(T amb , c, t) < F v (T v , c v , t v ), trigger the collaborative steam supply mode of the cascaded high-temperature heat pump module and the steam generation module; the steam production cost F(T amb , c, t) ≥ F v (T v , c v , t v ), trigger the collaborative steam supply mode of the phase change heat storage module and the steam generation module; where F v (T v , c v , t v ) is the steam production cost threshold during the valley electricity period.

[0022] According to another specific embodiment of the present invention, the embodiment of the present invention discloses a control method for an energy storage type high-temperature heat pump steam generation system. The conditions for triggering the heat charging mode of the cascade high-temperature heat pump module to the phase change heat storage module further include: when Q steam =0, c = c v , C v <90%, and when any of the following conditions is satisfied: T amb >5°C; T amb ≤5°C and the steam production cost F(T amb , c, t) < F p (T p , c p , t p ), where F p is the steam production cost threshold during peak power periods.

[0023] According to another specific embodiment of the present invention, the embodiment of the present invention discloses a control method for an energy storage type high-temperature heat pump steam generation system. The triggering conditions for triggering the shutdown mode are: when Q steam =0, and when any of the following conditions is satisfied: being in the peak power period (c = c p ); the heat storage capacity is full (C v ≥90%); c = c v , C v <90%, T amb ≤5°C and the steam production cost F(T amb , c, t) ≥ F p (T p , c p , t p ), where F p is the steam generation threshold during peak power periods.

[0024] According to another specific embodiment of the present invention, the embodiment of the present invention discloses a control method for an energy storage type high-temperature heat pump steam generation system. The steam production cost is: ; where η(T amb ) is the energy efficiency of the cascade high-temperature heat pump module, which is jointly determined by the ambient temperature, the performance of the inter-stage heat exchanger, the low-temperature stage compressor, and the high-temperature stage compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Shows the circuit diagram of the energy storage type high-temperature heat pump steam generation system in the present invention;

[0026] Figure 2 Shows specific operating parameter examples of the energy storage type high-temperature heat pump steam generation system in the present invention;

[0027] Figure 3 Logic diagram showing the control method of the energy storage type high-temperature heat pump steam generation system in the present invention.

[0028] Explanation of the reference numerals in the drawings:

[0029] Energy storage type high-temperature heat pump steam generation system 0;

[0030] Cascade high-temperature heat pump module 100, low-temperature stage circulation unit 101, high-temperature stage circulation unit 102, phase change heat storage module 200, steam generation module 300;

[0031] Air source evaporator 1, low-temperature stage compressor 2, high-temperature stage compressor 3, high-temperature stage electronic expansion valve 10, low-temperature stage electronic expansion valve 12, condenser 11, inter-stage heat exchanger 13;

[0032] Heat storage tank 7, first three-way valve 4, high-temperature circulation pump 8, second three-way valve 9;

[0033] Water vapor compressor 5, flash tank 6. Specific implementation mode

[0034] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without using these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0035] It should be noted that in this specification, similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0036] In the description of this embodiment, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0037] The terms "first", "second", etc. are only used for distinguishing descriptions and shall not be construed as indicating or implying relative importance.

[0038] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "connected", and "connected to" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific situations.

[0039] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0040] Combined with Figure 1 , the present invention provides an energy storage type high-temperature heat pump steam generation system 0, including: a cascade high-temperature heat pump module 100, a phase change heat storage module 200, and a steam generation module 300.

[0041] The cascade high-temperature heat pump module 100 includes a low-temperature stage circulation unit 101 and a high-temperature stage circulation unit 102.

[0042] The low-temperature stage circulation unit 101 is formed by connecting an air source evaporator 1, a low-temperature stage compressor 2, a low-temperature stage electronic expansion valve 12, and the low-temperature side of an inter-stage heat exchanger 13 in series to form a first closed circulation loop. A low-temperature stage working medium (not shown in the figure) flows in this first closed circulation loop. The specific path of the low-temperature stage working medium flow is as follows: The low-temperature stage working medium absorbs heat energy from the external environment in the air source evaporator 1 and exchanges heat with the external environment to change into a low-temperature and low-pressure gas state. The air source evaporator 1 is connected to the inlet of the low-temperature stage compressor 2, and the low-temperature stage working medium in the low-temperature and low-pressure gas state enters the low-temperature stage compressor 2 and is compressed into high-temperature and high-pressure steam. The low-temperature stage compressor 2 transports the high-temperature and high-pressure steam to the low-temperature side of the inter-stage heat exchanger 13, and the high-temperature and high-pressure steam releases heat to the high-temperature stage working medium in the inter-stage heat exchanger 13, and the low-temperature stage working medium condenses into a high-pressure liquid. The outlet of the low-temperature side of the inter-stage heat exchanger 13 is connected to the low-temperature stage electronic expansion valve 12. The high-pressure liquid forms a low-temperature and low-pressure gas-liquid mixture after throttling and pressure reduction. The low-temperature stage electronic expansion valve 12 transports the low-temperature and low-pressure gas-liquid mixture back to the inlet of the air source evaporator 1 to complete the low-temperature stage circulation.

[0043] The low-temperature stage circulation unit 101 is used to absorb low-grade heat energy from the external environment, improve the energy grade of the low-temperature stage working medium through compression, and release energy to the high-temperature stage circulation on the low-temperature side of the inter-stage heat exchanger 13 to achieve the preliminary efficiency improvement and cycle closure of the heat energy.

[0044] In some embodiments, the low-temperature stage working fluid is R134a, R290, R32 or R410A.

[0045] The high-temperature stage circulation unit 102 is formed by connecting in series the high-temperature stage compressor 3, the condenser 11, the high-temperature stage electronic expansion valve 10 and the high-temperature side of the inter-stage heat exchanger 13 to form a second closed circulation loop, which is used to improve the efficiency of the thermal energy provided by the low-temperature stage circulation unit 101.

[0046] Among them, the high-temperature stage working fluid (not shown in the figure) flows in this second closed circulation loop. The specific path of the high-temperature stage working fluid flow is as follows: The high-temperature stage working fluid absorbs the heat provided by the low-temperature stage circulation unit 101 in the inter-stage heat exchanger 13 and evaporates into low-temperature gas. The outlet of the high-temperature side of the inter-stage heat exchanger 13 is connected to the inlet of the high-temperature stage compressor 3. The low-temperature gas is compressed into ultra-high temperature and high-pressure steam by the high-temperature stage compressor 3. The high-temperature stage compressor 3 transports the ultra-high temperature and high-pressure steam to the condenser 11 and releases heat to the phase change heat storage module 200. The high-temperature and high-pressure steam condenses into high-pressure liquid. The outlet of the condenser 11 is connected to the high-temperature stage electronic expansion valve 10. The high-pressure liquid forms a low-temperature and low-pressure gas-liquid mixture after throttling and pressure reduction. The high-temperature stage electronic expansion valve 10 transports the low-temperature and low-pressure gas-liquid mixture back to the inlet of the high-temperature side of the inter-stage heat exchanger 13 to complete the high-temperature stage cycle and improve the efficiency of the thermal energy transferred by the low-temperature stage circulation unit 101 for the second time.

[0047] In some embodiments, the high-temperature stage working fluid is R245fa, R1234ze, R1336mzz-Z or R718.

[0048] The phase change heat storage module 200 includes a heat storage tank 7, a heat storage working fluid (not shown in the figure), a heat exchange tube (not shown in the figure), a first three-way valve 4, a second three-way valve 9 and a high-temperature circulation pump 8, which is used to store or release the thermal energy transferred by the high-temperature stage circulation unit 102.

[0049] The steam generation module 300 includes a flash tank 6 and a steam compressor 5, which is used to convert the thermal energy released by the phase change heat storage module 200 into high-pressure steam.

[0050] Specifically, during the valley electricity period, the cascade high-temperature heat pump module 100 operates to drive the phase change heat storage module 200 to charge heat and complete the heat energy storage. The high-temperature stage working medium releases heat in the condenser 11 to heat the circulating water flowing through the condenser 11. In some embodiments, the circulating water is heated from 90°C to 110°C - 120°C, and this circulating water serves as the heat transfer fluid. Among them, the inlet of the first three-way valve 4 is connected to the outlet of the condenser 11, and the first outlet of the first three-way valve 4 is connected to the inlet of the heat exchange tube. The second outlet of the first three-way valve 4 remains closed to prevent heat from leaking to other paths and ensure that all the heated circulating water flows to the heat exchange tube. When the heated circulating water flows through the heat exchange tube, heat is transferred to the heat storage working medium through the metal tube wall of the heat exchange tube. The heat storage working medium absorbs heat from its initial solid state and melts into a liquid state, storing energy in the form of latent heat.

[0051] The cooled circulating water flows out from the outlet of the heat exchange tube and enters the high-temperature circulating pump 8 under the control of the second three-way valve 9. Specifically, the inlet of the second three-way valve 9 is connected to the outlet of the heat exchange tube, the first outlet of the second three-way valve 9 is connected to the inlet of the high-temperature circulating pump 8, and the second outlet of the second three-way valve 9 remains closed. Each component works together to form a charging closed loop, forcing the cooled circulating water to return to the high-temperature circulating pump 8. The circulating water is pressurized by the high-temperature circulating pump 8 and re-injected into the condenser 11 to absorb the heat released by the high-temperature stage working medium again.

[0052] By adopting the above technical solutions, the energy utilization efficiency can be significantly improved. The cascade high-temperature heat pump module 100 efficiently absorbs low-grade heat energy from the external environment, and is further enhanced by the high-temperature stage circulation unit 102. Combining with the energy storage and energy release functions of the phase change heat storage module 200, the cascade utilization of heat energy is realized, reducing energy waste and operating costs; during the valley electricity period, low-cost electric energy and environmental heat energy are fully utilized for charging and energy storage; during the peak electricity period, the stored heat energy is released for steam production, effectively avoiding high electricity price periods and maximizing economic benefits; it can reduce the dependence on traditional energy. As a clean energy utilization system, the invention makes full use of the low-grade heat energy in the external environment, reduces carbon emissions, meets the requirements of sustainable development, and has a positive significance for environmental protection.

[0053] In some embodiments, the heat exchange tube is a spiral finned heat exchange tube, and the spiral finned heat exchange tube is immersed in the heat storage working medium.

[0054] In some embodiments, the heat exchange tube is a serpentine copper tube, and the outside of the heat exchange tube is covered with aluminum fins.

[0055] The design of spiral fins or aluminum fins increases the surface area of the heat exchange tubes, enlarging the contact area between the heat storage working fluid and the heat exchange tubes, thereby improving the heat exchange efficiency. This enables heat energy to be transferred more efficiently between the phase change heat storage module 200 and the steam generation module 300, contributing to enhancing the performance and efficiency of the entire system.

[0056] Specifically, during peak electricity periods, the system switches to the exothermic mode. The cascaded high-temperature heat pump module 100 stops operating, and the heat storage module releases the stored latent heat to drive steam generation.

[0057] Specifically, at this time, the inlet of the first three-way valve 4 is still connected to the outlet of the condenser 11, but the first outlet of the first three-way valve 4 is switched to the closed state, and the second outlet of the first three-way valve 4 is opened. The second outlet is connected to the inlet of the high-temperature stage electronic expansion valve 10. The high-temperature stage working fluid dissipates heat naturally through the pressure relief channel formed by the second outlet of the first three-way valve 4 and the high-temperature stage electronic expansion valve 10, preventing the pressure in the condenser 11 from rising abnormally and releasing the pressure of the residual high-temperature stage working fluid in the condenser 11. At the same time, the inlet of the second three-way valve 9 is connected to the outlet of the heat exchange tube, the second outlet of the second three-way valve 9 is connected to the inlet of the high-temperature circulation pump 8, and the first outlet of the second three-way valve 9 is switched to the closed state, forming an exothermic closed loop. The heat storage working fluid solidifies from the liquid state to the solid state, releasing latent heat that is transferred to the circulating water through the heat exchange tube. The heated circulating water is pressurized by the high-temperature circulation pump 8 and then enters the flash tank 6, where it quickly flashes into low-pressure steam and a small amount of unvaporized liquid water.

[0058] The low-pressure steam flows out from the outlet of the flash tank 6 and enters the steam compressor 5. The steam compressor 5 compresses the steam and finally outputs high-pressure dry saturated steam that meets industrial requirements.

[0059] In some embodiments, the steam compressor 5 is a twin-screw compressor, which pressurizes the low-pressure steam to 1.0 - 4.0 MPa through the isentropic compression of the twin-screw rotors.

[0060] The unvaporized liquefied water flows into the high-temperature circulation pump 8 from the bottom of the flash tank 6. The high-temperature circulation pump 8 pressurizes the liquid water and returns it through the second outlet of the second three-way valve 9 to the heat exchange tube to re-absorb heat. The liquid water absorbs the latent heat released by the phase change material in the heat storage device 7 and then enters the flash tank 6 again for recycling, forming a closed-loop flow. The circulating water circulates in the closed loop from the heat storage device 7 to the flash tank 6 to the high-temperature circulation pump 8 to the heat storage device 7 and back to the flash tank 6, realizing the repeated utilization of water resources and heat energy.

[0061] The steam generation module 300 further includes: a steam pipeline (not shown in the figure), which is respectively connected to the top outlet of the flash tank 6 and the inlet of the steam compressor 5; a return water channel (not shown in the figure), which extends from the bottom outlet of the flash tank 6 to the inlet of the high-temperature circulation pump 8. The steam pipeline directly connects the top outlet of the flash tank 6 and the steam compressor 5, avoiding heat loss during steam transportation and ensuring that the dryness of the output steam is ≥99%.

[0062] The return water channel connects the bottom outlet of the flash tank 6 and the inlet of the high-temperature circulation pump 8, and is communicated with the outlet of the high-temperature circulation pump 8 through the second outlet of the second three-way valve 9, realizing the closed-loop circulation of liquid water in the heat release mode, reducing the water consumption loss to less than 5%, and significantly reducing the make-up water volume of the system.

[0063] In some embodiments, the heat storage working medium is a phase change material with a phase change temperature of 80°C - 120°C. The phase change material within this phase change temperature range can achieve efficient phase change energy storage and release processes within a suitable temperature range, being able to effectively absorb and store a large amount of thermal energy during the heat storage process and stably release the stored thermal energy during the heat release process, meeting the requirements of the steam generation module 300.

[0064] In some embodiments, the phase change material includes magnesium nitrate hexahydrate Mg(NO 3 ) 2 ·6H 2 O, dimethyl fumarate (CNCO 2 NH 3 ) 2 , ribitol (C 5 H 12 O 5 ), xylitol (C 5 H 12 O 5 ), arabitol (C 5 H 12 O 5 ), erythritol, RT100. These specific phase change materials have their own unique physical and chemical properties, such as suitable phase change temperatures, relatively high phase change latent heats, etc., and can be selected and combined according to the actual application scenarios and requirements to achieve the best heat storage effect, improve the energy storage capacity of the system and the energy utilization efficiency.

[0065] During the low electricity consumption period, the cascaded high-temperature heat pump module 100 absorbs low-grade heat energy from the external environment and stores it in the phase change heat storage module 200. During the high electricity consumption period or when the steam demand is high, the stored heat energy is used to drive the water vapor compression cycle to produce steam with the required pressure and temperature. Compared with traditional boilers, the energy storage type high-temperature heat pump steam generation system 0 can significantly reduce energy consumption. Assuming that the thermal efficiency of a traditional boiler is 80%, while the heating energy efficiency (COP) of the energy storage type high-temperature heat pump steam generation system 0 of the present invention can reach 2.2, and the energy saving rate can be over 63%.

[0066] Taking a atmospheric and vacuum distillation unit with a processing capacity of 10 million tons / year as an example, the steam consumption rate of the atmospheric and vacuum distillation unit is 0.04 tons of steam per ton of crude oil. The system has a 24-hour operation cycle, Figure 2 which is an example of specific operation parameters.

[0067] In specific operation, during the low valley period (1:00 - 7:00), the cascaded high-temperature heat pump module 100 is driven at a power of 80 MW, 60 MW of heat energy is stored in the phase change heat storage module 200, and most of the steam demand of 30 tons / hour is directly supplied by the cascaded high-temperature heat pump module 100; during the electricity price transition period (7:00 - 12:00), the cascaded high-temperature heat pump module 100 is driven at a power of 70 MW, 50 MW of heat energy is stored in the phase change heat storage module 200, and the steam demand of 40 tons / hour is supplied by the cooperation of the cascaded high-temperature heat pump module 100 and the phase change heat storage module 200; during the peak period (12:00 - 18:00), the power of the cascaded high-temperature heat pump module 100 drops to 20 MW, and the phase change heat storage module 200 releases latent heat at a power of 100 MW to meet the steam demand of 60 tons / hour. During the peak period (18:00 - 24:00), the power of the cascaded high-temperature heat pump module 100 drops to 40 MW, and the phase change heat storage module 200 releases latent heat at a power of 80 MW to meet the steam demand of 50 tons / hour, avoiding high electricity price energy consumption. Through the dynamic regulation of "storing heat during valley electricity and releasing energy during peak electricity". Assuming that the steam is saturated steam with a pressure of 10 bar and an enthalpy value of 2776 kJ / kg, after adopting the energy storage type high-temperature heat pump steam generation system 0, it is expected to save about 27,000 tons of standard coal per year and reduce carbon dioxide emissions by about 68,000 tons, with significant economic and environmental benefits.

[0068] The present invention also discloses a control method for an energy storage type high-temperature heat pump steam generation system. The control method is used to control any one of the above energy storage type high-temperature heat pump steam generation systems, combined with Figure 3 the following, the control method includes the following steps:

[0069] S1. Parameter detection step

[0070] Real-time detect the user's steam demand power Q steam 、time-of-use electricity price c, and environmental temperature Tamb , the remaining capacity C of the phase change heat storage module v , where c ∈ {c v , c p}}, c v is the electricity price during off-peak hours, c p is the electricity price during peak hours and c p > c v ;

[0071] S2. Multi-module collaborative control steps

[0072] Based on the detection parameters, control the collaborative operation of the cascade high-temperature heat pump module 100, the phase change heat storage module 200 and the steam generation module 300;

[0073] When Q steam > 0, according to the time-of-use electricity price c and the steam production cost F(T amb , c, t), trigger the collaborative steam supply mode of the cascade high-temperature heat pump module 100 and the steam generation module 300, or trigger the collaborative steam supply mode of the phase change heat storage module 200 and the steam generation module 300, where t is the operating time of the cascade high-temperature heat pump module 100;

[0074] When Q steam = 0, according to the remaining capacity C of the phase change heat storage module v , the time-of-use electricity price c and the ambient temperature T amb , trigger the heat charging mode of the cascade high-temperature heat pump module 100 to the phase change heat storage module 200, or trigger the shutdown mode.

[0075] When the cascade high-temperature heat pump module 100 and the steam generation module 300 work together to provide steam, the low-temperature compressor 2 drives the low-temperature working fluid to absorb low-grade heat energy from the external environment in the air source evaporator 1, and then the low-temperature working fluid enters the low-temperature side of the inter-stage heat exchanger 13 to release heat; at the same time, the high-temperature compressor 3 drives the high-temperature working fluid to absorb the heat energy transferred from the low-temperature stage on the high-temperature side of the inter-stage heat exchanger 13, and further raises the temperature of the heat energy to 120°C - 150°C through cascade efficiency improvement; the high-temperature working fluid then enters the condenser 11, transfers the heat to the circulating water to raise its temperature to 120°C - 130°C, and the heated circulating water converts part of the liquid water into low-pressure saturated steam with a dryness ≥ 95% through the pressure-reducing flashing principle in the flash tank 6, and the unvaporized high-temperature water returns to the system through the high-temperature circulating pump 8 for reheating; the low-pressure steam is finally compressed to high-pressure dry steam of 1.0 - 4.0 MPa by the steam compressor 5 for output.

[0076] When the phase change heat storage module 200 and the steam generation module 300 work together to provide steam, the inlet of the first three-way valve 4 is connected to the outlet of the condenser 11, and the second outlet of the first three-way valve 4 is connected to the inlet of the high-temperature stage electronic expansion valve 10; the inlet of the second three-way valve 9 is connected to the outlet of the heat exchange tube of the heat storage device 7, and the second outlet of the second three-way valve 9 is connected to the inlet of the high-temperature circulation pump 8, forming a heat release loop of "heat storage device 7 → high-temperature circulation pump 8 → flash tank 6"; the heat storage working medium with a phase change temperature of 80°C to 120°C in the heat storage device 7 releases latent heat during the solidification process, transfers heat energy to the circulating water through the heat exchange tube, and raises its temperature to 120°C to 130°C; the high-temperature circulation pump 8 drives the circulating water into the flash tank 6, where it flashes into low-pressure saturated steam with a dryness of ≥95% under a pressure of 0.3 to 0.5 MPa, and the unvaporized high-temperature circulating water returns to the heat storage device 7 through the return water channel to absorb heat energy again; the low-pressure steam is compressed by the steam compressor 5 to high-pressure dry steam with a pressure of 1.0 to 4.0 MPa and output, and the inter-stage heat exchanger 13, the high-temperature stage compressor 3, and the low-temperature stage compressor 2 remain in the shutdown state to ensure that the heat energy is completely supplied independently by the phase change heat storage module 200.

[0077] When the cascade high-temperature heat pump module 100 charges the phase change heat storage module 200, the inlet of the first three-way valve 4 is connected to the outlet of the condenser 11, the first outlet of the first three-way valve 4 is connected to the inlet of the heat exchange tube of the heat storage device 7, and the second outlet remains closed; the inlet of the second three-way valve 9 is connected to the outlet of the heat exchange tube, and the first outlet of the second three-way valve 9 is connected to the inlet of the high-temperature circulation pump 8, forming a charging loop of "condenser 11 → heat storage device 7 → high-temperature circulation pump 8"; the low-temperature stage compressor 2 drives the low-temperature stage working medium to absorb heat energy from the external environment in the air source evaporator 1, and then transfers the heat energy to the high-temperature stage working medium in a stepped manner through the inter-stage heat exchanger 13. The high-temperature stage working medium heats the circulating water to 120°C to 130°C in the condenser 11; the heated circulating water continuously transfers heat to the heat storage working medium through the heat exchange tube of the heat storage device 7, and the heat storage working medium gradually melts from a solid state to a liquid state after absorbing heat, and the charging efficiency reaches more than 90%.

[0078] When the energy storage type high-temperature heat pump steam generation system 0 enters the shutdown mode, the inlet of the first three-way valve 4 is disconnected from the outlet of the condenser 11, and the second outlet of the first three-way valve 4 is connected to the inlet of the high-temperature stage electronic expansion valve 10 to release the system pressure; the second three-way valve 9 is synchronously switched to the closed state, the inlet of the second three-way valve 9 is disconnected from the outlet of the heat exchange tube of the heat storage device 7, and the second outlet of the second three-way valve 9 blocks the inlet path of the flash tank 6, completely isolating the heat energy transfer between the phase change heat storage module 200 and the steam generation module 300; the low-temperature stage compressor 2 and the high-temperature stage compressor 3 completely stop running.

[0079] The multi-module collaborative control step further includes:

[0080] When Q steam> 0 and c = c v When triggered, the cascade high-temperature heat pump module 100 and the steam generation module 300 cooperate in the steam supply mode;

[0081] When Q steam > 0 and c = c p When, execute according to the following rules:

[0082] The steam production cost F(T amb , c, t) < F v (T v , c v , t v ), trigger the cascade high-temperature heat pump module 100 and the steam generation module 300 to cooperate in the steam supply mode;

[0083] The steam production cost F(T amb , c, t) ≥ F v (T v , c v , t v ), trigger the phase change heat storage module 200 and the steam generation module 300 to cooperate in the steam supply mode;

[0084] Where F v (T v , c v , t v ) is the steam production cost threshold during off-peak electricity hours.

[0085] When the energy storage high-temperature heat pump steam generation system 0 detects that the steam demand Q steam > 0 and is in the off-peak electricity period (c = c v ), directly trigger the cascade high-temperature heat pump module 100 and the steam generation module 300 to cooperate in the steam supply mode. At this time, the low-stage compressor 2 and the high-stage compressor 3 are started, and the external environmental heat energy is absorbed through the air source evaporator 1. After the cascade heat exchanger 13 improves the efficiency step by step, the condenser 11 heats the circulating water to 120°C to 130°C, and the heated circulating water is depressurized and flashed into steam by the flash tank 6 and output by steam compression pressurization.

[0086] When Q steam > 0, when the energy storage high-temperature heat pump steam generation system 0 comes from the peak-valley period (c = c v ) to the peak electricity period (c = c p ), the energy storage high-temperature heat pump steam generation system 0 calculates the current steam production cost in real time , where η(T amb ) is dynamically adjusted according to the ambient temperature. If the calculation result is lower than the steam production cost threshold F during off-peak electricity hours v (T v , c v , tv ), the collaborative steam supply mode of the cascade high-temperature heat pump module 100 and the steam generation module 300 is maintained. If the calculation result is not lower than the steam production cost threshold F during the valley electricity period v (T v , c v , t v ), switch to the collaborative steam supply mode of the phase change heat storage module 200 and the steam generation module 300.

[0087] The conditions for triggering the heat charging mode of the cascade high-temperature heat pump module 100 to the phase change heat storage module 200 are:

[0088] When Q steam = 0, c = c v , C v < 90%, and when any of the following conditions is met:

[0089] T amb > 5°C;

[0090] T amb ≤ 5°C and the steam production cost F(T amb , c, t) < F p (T p , c p , t p ), where F p is the steam production cost threshold during the peak electricity period.

[0091] When the system detects the valley electricity period (c = c v ) and the heat storage capacity is not full (C v < 90%), the conditions for triggering the heat charging mode of the cascade high-temperature heat pump module 100 to the phase change heat storage module 200 further include: If the ambient temperature T amb > 5°C, the cascade high-temperature heat pump module 100 transfers the ambient heat energy to the heat storage working fluid of the heat storage tank 7 after stepwise efficiency improvement through the inter-stage heat exchanger 13, causing it to absorb heat and melt into a liquid state; if the ambient temperature T amb ≤ 5°C, then it is necessary to calculate the current steam production cost F(T amb , c, t) in real time and compare it with the preset steam production cost threshold F p (T p , c p , t p ). Only when F(T amb , c, t) < F p is heat charging allowed, ensuring that the phase change heat storage module 200 preferentially absorbs the heat energy during the low-cost valley electricity period to provide economic guarantee for steam supply during the peak electricity period.

[0092] The trigger conditions for triggering the shutdown mode are:

[0093] When Q steam = 0 and any of the following conditions is met:

[0094] During peak power hours (c = c p );

[0095] The heat storage capacity is full (C v ≥ 90%);

[0096] c = c v 、C v < 90%, T amb ≤ 5°C and F(T amb , c, t) ≥ F p (T p , c p , t p ), where F p is the steam production cost threshold during peak power hours.

[0097] When the energy storage type high-temperature heat pump steam generation system 0 detects no steam demand Q steam = 0 and any of the following conditions is met, the shutdown mode is triggered: If during peak power hours (c = c p ), the first three-way valve 4 blocks the heat energy transfer between the condenser 11 and the phase change heat storage module 200, the second three-way valve 9 closes the inlet path of the flash tank 6, and the low-temperature stage compressor 2 and the high-temperature stage compressor 3 are completely shut down to avoid high electricity price energy consumption.

[0098] If the heat storage capacity is full (C v ≥ 90%), the heat storage working medium is completely melted into a liquid state and the heat capacity is saturated. The system cuts off the power supply to the inter-stage heat exchanger 13 of the cascade high-temperature heat pump module 100, and monitors the state of the phase change material in real time through the temperature sensor (not shown in the figure) in the heat storage tank 7 to ensure no overcharge risk.

[0099] If during off-peak power hours (c = c v ) but the ambient temperature T amb ≤ 5°C and the current steam production cost F(T amb , c, t) ≥ F p , where F p is the steam production cost threshold during peak power hours, immediately close the heat storage working medium circulation between the inter-stage heat exchanger 13 and the condenser 11, and the low-temperature stage compressor 2 and the high-temperature stage compressor 3 completely stop running.

[0100] The steam production cost is: ;

[0101] Among them, η(T amb) The energy efficiency of the cascaded high-temperature heat pump module 100 is determined by the ambient temperature, the performance of the intermediate heat exchanger 13, the low-stage compressor 2, and the high-stage compressor 3.

[0102] By adopting the above technical solutions, it is possible to achieve refined control of the energy storage type high-temperature heat pump steam generation system. According to the various parameters detected in real time, the operation mode of the system can be flexibly adjusted to ensure that it operates in the optimal manner under different working conditions, thereby improving the energy utilization efficiency of the system and reducing the operation cost. It can effectively respond to the changes in electricity prices at different times and the fluctuations in environmental conditions. By reasonably triggering different steam supply modes and heat charging modes, while meeting the steam demand of users, it can make the most of low-cost electric energy and environmental heat energy, reduce the dependence on high-cost electric energy, and improve the economy and sustainability of the system. It can enhance the stability and reliability of the system. In a complex and changeable operating environment, through real-time monitoring and intelligent control, the operating state of the system can be adjusted in a timely manner to avoid problems such as energy waste or equipment overload that may be caused by single-mode operation, and ensure the long-term stable operation of the system.

[0103] Although the present invention has been illustrated and described by referring to some preferred embodiments of the present invention, those of ordinary skill in the art should understand that the above content is a further detailed description of the present invention in combination with specific embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. Those skilled in the art can make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A control method for an energy storage type high temperature heat pump steam generation system, characterized in that: The energy storage type high temperature heat pump steam generation system comprises: a cascade high temperature heat pump module, a phase change heat storage module and a steam generation module. The cascade high temperature heat pump module comprises: A low-temperature circulation unit, wherein the low-temperature circulation unit is composed of an air source evaporator, a low-temperature compressor, a low-temperature electronic expansion valve and a low-temperature side of an inter-stage heat exchanger connected in series to form a first closed circulation loop, and is used to absorb low-grade heat energy from the environment, and the low-temperature circulation unit is filled with a low-temperature working fluid; A high-temperature circulation unit, wherein the high-temperature circulation unit is composed of a high-temperature compressor, a condenser, a high-temperature electronic expansion valve and a high-temperature side of an inter-stage heat exchanger connected in series to form a second closed circulation loop, which is used to improve the efficiency of the heat energy transferred by the low-temperature circulation unit, and the high-temperature circulation unit is filled with a high-temperature working fluid; The phase change heat storage module includes a heat storage device, a heat storage medium, a heat exchange tube, a first three-way valve, a second three-way valve and a high-temperature circulation pump, which is used to store or release the heat energy transferred by the high-temperature circulation unit; The steam generation module includes a flash tank and a water vapor compressor, which are used to convert the heat energy released by the phase change heat storage module into high-pressure steam; The control method comprises the following steps: S1. Parameter detection steps Real-time detection of user steam demand power Q steam , time-of-use electricity price c, ambient temperature T amb , the remaining capacity of the phase change heat storage module C v , where c∈{c v ,c p }, c v is the off-peak electricity price, c p is the peak electricity price and c p >c v ; S2. Multi-module collaborative control steps Based on the detection parameters, the coordinated operation of the cascade high-temperature heat pump module, the phase change heat storage module and the steam generation module is controlled; When Q steam >0, according to the time-of-use electricity price c and steam production cost F(T amb ,c,t), triggering the cascade high-temperature heat pump module and the steam generation module to cooperate in the steam supply mode, or triggering the phase change heat storage module and the steam generation module to cooperate in the steam supply mode, where t is the operation time of the cascade high-temperature heat pump module; When Q steam =0, according to the remaining capacity C of the phase change heat storage module v、 The time-of-use electricity price c and the ambient temperature T amb , triggering the cascade high temperature heat pump module to charge the phase change heat storage module, or triggering the shutdown mode; The multi-module collaborative control step further includes: When Q steam >0, and c=c v When the cascade high-temperature heat pump module and the steam generation module cooperate to supply steam, the cascade high-temperature heat pump module and the steam generation module cooperate to supply steam; When Q steam >0, and c=c p , follow the following rules: The steam production cost F(T amb ,c,t) <F v (T v ,c v ,t v ), triggering the cascade high-temperature heat pump module and the steam generation module to cooperate in the steam supply mode; The steam production cost F(T amb ,c,t)≥F v (T v ,c v ,t v ), triggering the phase change heat storage module and the steam generation module to cooperate in the steam supply mode; Among them, F v (T v ,c v ,t v ) is the steam production cost threshold during off-peak hours.

2. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: During the off-peak period, the inlet of the first three-way valve is connected to the outlet of the condenser, and the first outlet of the first three-way valve is connected to the inlet of the heat exchange tube; the inlet of the second three-way valve is connected to the outlet of the heat exchange tube, and the first outlet of the second three-way valve is connected to the inlet of the high-temperature circulation pump, forming a heat charging closed loop, and the cascade high-temperature heat pump module charges heat energy into the heat storage; During the peak power period, the inlet of the first three-way valve is connected to the outlet of the condenser, and the second outlet of the first three-way valve is connected to the inlet of the high-temperature electronic expansion valve; the inlet of the second three-way valve is connected to the outlet of the heat exchange tube, and the second outlet of the second three-way valve is connected to the inlet of the high-temperature circulation pump, forming a heat release closed loop, and the high-temperature circulation pump drives the heat energy released by the heat storage to generate steam through the flash tank, and the water vapor compressor outputs high-pressure steam.

3. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: The heat storage medium is a phase change material with a phase change temperature of 80°C-120°C.

4. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: The heat exchange tube is a serpentine copper tube, and the heat exchange tube is covered with aluminum fins.

5. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: The steam generation module further comprises: A steam pipeline, the steam pipeline is respectively connected to the top outlet of the flash tank and the inlet of the water vapor compressor; The return water channel extends from the bottom outlet of the flash tank to the inlet of the high-temperature circulation pump, and is connected to the outlet of the high-temperature circulation pump through the second outlet of the second three-way valve.

6. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: The conditions for triggering the cascade high temperature heat pump module to charge the phase change heat storage module further include: When Q steam =0、c=c v , C v <90% and any of the following conditions are met: T amb >5℃； T amb ≤5℃ and the steam production cost F(T amb ,c,t) <F p (T p ,c p ,t p ), where F p The threshold value for steam production cost during peak power hours.

7. The control method of the energy storage type high temperature heat pump steam generation system according to claim 1, characterized in that: The triggering condition for triggering the shutdown mode is: When Q steam =0, and any of the following conditions is met: During peak power period (c=c p ); Heat storage capacity is full (C v ≥90%)); c=c v , C v <90%, T amb ≤5℃ and the steam production cost F(T amb ,c,t)≥F p (T p ,c p ,t p ), where F p The threshold value for steam production cost during peak power hours.

8. The control method of the energy storage type high temperature heat pump steam generation system according to any one of claims 1 to 7, characterized in that: The steam production cost is: F(T amb ,c,t)= t; Among them, η(T amb ) is the energy efficiency of the cascade high-temperature heat pump module, which is determined by the ambient temperature, the inter-stage heat exchanger, the low-temperature compressor and the high-temperature compressor performance.

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