Energy storage type high-temperature heat pump steam generation system and control method thereof

Abstract

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, and the cascade high-temperature heat pump module comprises a first closed circulation loop 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 interstage heat exchanger in series; the high-temperature compressor, the condenser, the high-temperature electronic expansion valve and the high-temperature side of the interstage heat exchanger are connected in series to form a second closed circulation loop; the phase change heat storage module comprises a heat storage device, a heat storage working medium, a heat exchange pipe, a first three-way valve, a second three-way valve and a high-temperature circulating pump; the steam generation module comprises a flash tank and a water vapor compressor. By the adoption of the technical scheme, in the valley electricity period, low-price electric energy and environment heat energy are fully utilized for heat charging and energy storage; and in the peak electricity period, the stored heat energy is released for steam production, and maximization of economic benefits is achieved. The invention further provides a control method of the energy storage type high-temperature heat pump steam generation system.

Description

Technical Field

[0001] The present invention relates to the field of petrochemical industry and energy utilization, and in particular to a storage-type high-temperature heat pump steam generation system and a control method thereof. The system integrates advanced cascade high-temperature heat pump technology and phase change heat storage technology to achieve efficient, stable and economical steam supply to meet the continuous demand for steam in the petrochemical production process. Background Art

[0002] In the petrochemical industry, the stable supply and efficient use of steam are the core links in the production process. However, although traditional steam generation methods such as coal-fired boilers and gas-fired boilers can meet basic production needs, 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, the existing steam storage technology also has defects such as difficulty in construction, 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 a control method thereof, which realizes efficient production and stable supply of steam by integrating advanced cascade high temperature heat pump technology and phase change heat storage technology. The system can flexibly adjust the operation mode according to the change of electricity price, realize efficient utilization of energy and reduce costs, thereby significantly improving the energy utilization efficiency and economic benefits of 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, comprising: 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 comprising: a low temperature stage circulation unit, the low temperature stage circulation unit is composed of an air source evaporator, a low temperature stage compressor, a low temperature stage electronic expansion valve and the low temperature side of an interstage heat exchanger connected in series to form a first closed circulation loop, which is used to absorb low-grade heat energy from the environment, and the low temperature stage circulation unit is filled with a low temperature working fluid; a high temperature stage circulation unit, the high temperature stage circulation unit is composed of a high temperature stage compressor, a condenser, a high temperature stage electronic expansion valve and the high temperature side of an interstage 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 stage circulation unit, and the high temperature stage circulation unit is filled with a high temperature working fluid; the phase change heat storage module comprises a heat storage device, a heat storage working fluid, a heat exchange pipe, 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 stage circulation unit; the steam generation module comprises a flash tank and a water vapor compressor, which is used to convert the heat energy released by the phase change heat storage module into high pressure steam.

[0005] The adoption of the above technical scheme can significantly improve energy utilization efficiency. The cascade high-temperature heat pump module can efficiently absorb low-grade thermal energy from the environment, and further improve the efficiency through the high-temperature circulation unit. Combined with the energy storage and release functions of the phase change heat storage module, the cascade utilization of thermal energy is realized, energy waste is reduced, and operating costs are reduced. During off-peak electricity periods, low-priced electricity and environmental thermal energy are fully utilized for heat charging and energy storage. During peak electricity periods, the stored thermal energy is released for steam production, effectively avoiding high electricity price periods and maximizing economic benefits. It can reduce dependence on traditional energy. As a clean energy utilization system, the invention makes full use of low-grade thermal 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 embodiment of the present invention discloses an energy storage type high-temperature heat pump steam generation system, during the valley power 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 thermal energy into the heat storage device; 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 device to generate steam through the flash tank, and the water vapor compressor outputs high-pressure steam.

[0007] By adopting the above technical solution, we can make full use of the difference in electricity prices in different time periods, store thermal energy at a lower cost during off-peak hours, and release the stored thermal energy for steam production during peak hours, thereby effectively reducing the overall cost of steam production and improving the economy and energy 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 in the embodiment of the present invention, 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, the embodiment of the present invention discloses an energy storage type high temperature heat pump steam generation system, the heat exchange tube is a serpentine copper tube, and the heat exchange tube is covered with aluminum fins.

[0010] By adopting the above technical solution, the serpentine copper tube has good thermal conductivity and can quickly transfer heat to the heat storage medium, while the outer aluminum fins can increase the heat exchange area and further improve the heat exchange efficiency, so that heat energy can be more efficiently transferred 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 embodiment of the present invention discloses an energy storage type high temperature heat pump steam generation system, and the phase change material includes hexahydrate nitrate, dimethyl fumarate, ribitol, xylitol, arabitol, erythritol, and RT100.

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

[0013] By adopting the above technical solution, the twin-screw compressor has the advantages of compact structure, stable operation, high efficiency and low noise. 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 reduce the maintenance cost and operating energy consumption of the equipment.

[0014] According to another specific embodiment of the present invention, an embodiment of the present invention discloses an energy storage type high-temperature heat pump steam generation system, and the steam generation module also 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 connected to 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 further discloses a control method for an energy storage type high temperature heat pump steam generating system. The control method is used to control any of the above energy storage type high temperature heat pump steam generating systems. 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 , time-of-use electricity price c and 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.

[0016] By adopting the above technical scheme, it is possible to achieve refined control of the energy storage type high temperature heat pump steam generation system, flexibly adjust the system operation mode according to the various parameters detected in real time, ensure that it can operate in the best way under different working conditions, thereby improving the energy utilization efficiency of the system and reducing the operation cost; it can effectively respond to changes in electricity prices and fluctuations in environmental conditions in different periods of time, and by reasonably triggering different steam supply modes and heating modes, while meeting the user's steam demand, maximize the use of low-priced electricity and environmental thermal energy, reduce dependence on high-priced electricity, and improve the economy and sustainability of the system; it can enhance the stability and reliability of the system, and in a complex and changeable operating environment, timely adjust the system's operating status through real-time monitoring and intelligent control 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.

[0017] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a control method for an energy storage type high temperature heat pump steam generation system, wherein the multi-module coordinated control step further comprises: when Q steam >0, and c=c v When Q steam >0, and c=c p When 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; where F v (T v ,c v ,t v ) is the steam production cost threshold during off-peak hours.

[0018] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a control method for an energy storage type high temperature heat pump steam generation system, wherein 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 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 hours.

[0019] According to another specific embodiment of the present invention, an embodiment of the present invention discloses a control method for an energy storage type high temperature heat pump steam generation system, wherein the triggering condition for triggering the shutdown mode is: when Q steam =0, and any of the following conditions are met: During peak power period (c=c p ); The heat storage capacity is full (C v ≥90%);c=c v , C v <90%, T amb ≤5℃ and steam production cost F(T amb ,c,t)≥F p (T p ,c p ,t p ), where F p It is the steam generation threshold during peak power hours.

[0020] 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, and the steam production cost is: ; Among them, η(T amb ) is the energy efficiency of the cascade high-temperature heat pump module, which is determined by the ambient temperature, interstage heat exchanger, low-temperature compressor and high-temperature compressor performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A circuit diagram showing the energy storage type high temperature heat pump steam generation system of the present invention; Figure 2 An example of specific operating parameters of the energy storage type high temperature heat pump steam generation system of the present invention is shown; Figure 3A logic diagram showing a control method of an energy storage type high temperature heat pump steam generation system in the present invention.

[0022] Description of Figure Numbers: Energy storage type high temperature heat pump steam generation system 0; Cascade high-temperature heat pump module 100, low-temperature circulation unit 101, high-temperature circulation unit 102, phase change heat storage module 200, steam generation module 300; Air source evaporator 1, low temperature compressor 2, high temperature compressor 3, high temperature electronic expansion valve 10, low temperature electronic expansion valve 12, condenser 11, interstage heat exchanger 13; Heat storage device 7, first three-way valve 4, high temperature circulation pump 8, second three-way valve 9; Water vapor compressor 5, flash tank 6. DETAILED DESCRIPTION

[0023] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may extend based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0024] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0025] In the description of this embodiment, it should be noted that the terms "upper", "lower", "inner", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the inventive product is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply 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 on the present invention.

[0026] The terms “first”, “second”, etc. are only used for distinguishing descriptions and should not be understood as indicating or implying relative importance.

[0027] In the description of this embodiment, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "connected", and "connected" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0029] Combination Figure 1 The present invention proposes an energy storage type high temperature heat pump steam generation system 0, comprising: a cascade high temperature heat pump module 100, a phase change heat storage module 200, and a steam generation module 300.

[0030] The cascade high-temperature heat pump module 100 includes a low-temperature stage circulation unit 101 and a high-temperature stage circulation unit 102 .

[0031] The low-temperature circulation unit 101 is connected in series by the air source evaporator 1, the low-temperature compressor 2, the low-temperature electronic expansion valve 12 and the low-temperature side of the interstage heat exchanger 13 to form a first closed circulation loop, wherein the low-temperature working fluid (not shown in the figure) flows in the first closed circulation loop, and the specific flow path of the low-temperature working fluid is as follows: the low-temperature working fluid absorbs heat energy from the external environment in the air source evaporator 1, and changes into a low-temperature and low-pressure gas state after heat exchange with the external environment. The air source evaporator 1 is connected to the inlet of the low-temperature compressor 2, and the low-temperature working fluid in the low-temperature and low-pressure gas state enters the low-temperature compressor 2 and is compressed into high-temperature and high-pressure steam. The low-temperature compressor 2 transports the high-temperature and high-pressure steam to the low-temperature side of the interstage heat exchanger 13, and the high-temperature and high-pressure steam releases heat to the high-temperature working fluid in the interstage heat exchanger 13, and the low-temperature working fluid condenses into a high-pressure liquid. The low-temperature side outlet of the inter-stage heat exchanger 13 is connected to the low-temperature 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 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 cycle.

[0032] The low-temperature circulation unit 101 is used to absorb low-grade thermal energy from the external environment, improve the energy grade of the low-temperature working fluid through compression, and release the energy to the high-temperature circulation on the low-temperature side of the inter-stage heat exchanger 13, thereby achieving initial efficiency improvement and cycle closure of thermal energy.

[0033] In some embodiments, the low temperature grade working fluid is R134a, R290, R32 or R410A.

[0034] The high-temperature circulation unit 102 is composed of a high-temperature compressor 3, a condenser 11, a high-temperature electronic expansion valve 10 and a high-temperature side of an inter-stage heat exchanger 13 connected in series to form a second closed circulation loop for improving the efficiency of the heat energy provided by the low-temperature circulation unit 101.

[0035] Among them, the high-temperature working fluid (not shown in the figure) flows in the second closed circulation loop, and the flow path of the high-temperature working fluid is specifically as follows: the high-temperature working fluid absorbs the heat provided by the low-temperature circulation unit 101 in the inter-stage heat exchanger 13, and evaporates into a low-temperature gas. The high-temperature side outlet of the inter-stage heat exchanger 13 is connected to the inlet of the high-temperature compressor 3. The low-temperature gas is compressed into ultra-high temperature and high-pressure steam by the high-temperature compressor 3. The high-temperature 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 is condensed into a high-pressure liquid. The outlet of the condenser 11 is connected to the high-temperature electronic expansion valve 10. The high-pressure liquid forms a low-temperature and low-pressure gas-liquid mixture after throttling and reducing the pressure. The high-temperature electronic expansion valve 10 transports the low-temperature and low-pressure gas-liquid mixture back to the high-temperature side inlet of the inter-stage heat exchanger 13, completing the high-temperature cycle and improving the efficiency of the heat energy transferred by the low-temperature circulation unit 101 for a second time.

[0036] In some embodiments, the high temperature grade working fluid is R245fa, R1234ze, R1336mzz-Z or R718.

[0037] The phase change heat storage module 200 includes a heat storage device 7, a heat storage medium (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 are used to store or release the heat energy transferred by the high-temperature stage circulation unit 102.

[0038] The steam generation module 300 includes a flash tank 6 and a water vapor compressor 5, and is used to convert the thermal energy released by the phase change thermal storage module 200 into high-pressure steam.

[0039] Specifically, during the valley power period, the cascade high-temperature heat pump module 100 is operated to drive the phase change heat storage module 200 to charge heat and complete the thermal energy storage. The high-temperature working fluid releases heat in the condenser 11 and heats 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 the circulating water is used as a 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 being lost 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, the heat is transferred to the heat storage working fluid through the metal tube wall of the heat exchange tube. The heat storage working fluid absorbs heat from the initial solid state and melts into a liquid state, storing energy in the form of latent heat.

[0040] The cooled circulating water flows out from the outlet of the heat exchange tube and enters the high-temperature circulating pump 8 through 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. The various components work together to form a heat 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 then re-injected into the condenser 11 to absorb the heat released by the high-temperature working fluid again.

[0041] The above technical solution can significantly improve energy utilization efficiency. The cascade high-temperature heat pump module 100 can efficiently absorb low-grade thermal energy from the external environment, and further improve the efficiency through the high-temperature circulation unit 102. Combined with the energy storage and release functions of the phase change heat storage module 200, the cascade utilization of thermal energy is realized, energy waste is reduced, and operating costs are reduced. During off-peak power periods, low-priced electricity and environmental thermal energy are fully utilized for heat charging and energy storage. During peak power periods, the stored thermal energy is released for steam production, effectively avoiding high electricity price periods and maximizing economic benefits. It can reduce dependence on traditional energy. As a clean energy utilization system, the invention fully utilizes low-grade thermal energy in the external environment, reduces carbon emissions, meets the requirements of sustainable development, and has positive significance for environmental protection.

[0042] In some embodiments, the heat exchange tube is a spiral fin heat exchange tube, and the spiral fin heat exchange tube is immersed in the heat storage medium.

[0043] In some embodiments, the heat exchange tube is a serpentine copper tube, and the heat exchange tube is covered with aluminum fins.

[0044] The design of spiral fins or aluminum fins increases the surface area of ​​the heat exchange tube, thereby increasing the contact area between the heat storage medium and the heat exchange tube, thereby improving the heat exchange efficiency. This allows heat energy to be more efficiently transferred between the phase change heat storage module 200 and the steam generation module 300, which helps to improve the performance and efficiency of the entire system.

[0045] Specifically, during the peak electricity period, the system switches to the heat release mode, the cascade high-temperature heat pump module 100 stops running, and the heat storage module releases the stored latent heat to drive steam generation.

[0046] 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 a closed state, the second outlet of the first three-way valve 4 is opened, and the second outlet is connected to the inlet of the high-temperature electronic expansion valve 10. The high-temperature working fluid naturally dissipates heat through the pressure relief channel formed by the second outlet of the first three-way valve 4 and the high-temperature electronic expansion valve 10, avoiding abnormal pressure increase in the condenser 11, and is used to release the pressure of the residual high-temperature 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 pipe, 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 a closed state, forming a heat release closed loop, the heat storage working fluid solidifies from liquid to solid, releases latent heat and is transferred to the circulating water through the heat exchange pipe, and the heated circulating water enters the flash tank 6 after being pressurized by the high-temperature circulation pump 8, and quickly flashes into low-pressure steam and a small amount of unvaporized liquid water.

[0047] The low-pressure steam flows out from the outlet of the flash tank 6 and enters the water vapor compressor 5. The water vapor compressor 5 compresses the steam and finally outputs high-pressure dry saturated steam that meets industrial needs.

[0048] In some embodiments, the water vapor compressor 5 is a twin-screw compressor, which pressurizes the low-pressure steam to 1.0-4.0 MPa through the isentropic compression effect of the twin-screw rotors.

[0049] The liquefied water that has not yet reached the gas state 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 to the heat exchange pipe through the second outlet of the second three-way valve 9 to absorb heat again. The liquid water absorbs the latent heat released by the phase change material in the heat storage 7, and then enters the flash tank 6 again for recycling, forming a closed-loop flow. The circulating water circulates in a closed loop from the heat storage 7 to the flash tank 6 to the high-temperature circulation pump 8 to the heat storage 7 and then back to the flash tank 6, realizing the reuse of water resources and thermal energy.

[0050] 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 water vapor compressor 5; and a water return 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 water vapor compressor 5 to avoid heat loss during steam transportation and ensure that the output steam dryness is ≥ 99%.

[0051] 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 connected to the outlet of the high-temperature circulation pump 8 through the second outlet of the second three-way valve 9, thereby realizing the closed-loop circulation of liquid water in the exothermic mode, reducing water loss to less than 5%, and significantly reducing the amount of water replenishment in the system.

[0052] In some embodiments, the heat storage medium is a phase change material with a phase change temperature of 80°C-120°C. The phase change material in this phase change temperature range can realize efficient phase change energy storage and energy release process within a suitable temperature range, can effectively absorb and store a large amount of heat energy during the heat storage process, and can stably release the stored heat energy during the heat release process, thus meeting the needs of the steam generation module 300.

[0053] In some embodiments, the phase change material includes hexahydrate nitrate Mg(NO3)2·6H2O, dimethyl fumarate (CNCO2NH3)2, ribitol (C5H 12 O5), xylitol (C5H 12 O5), arabinitol (C5H 12 O5), erythritol, RT100. These specific phase change materials have their own unique physical and chemical properties, such as suitable phase change temperature, high phase change latent heat, etc. They can be selected and combined according to actual application scenarios and needs to achieve the best heat storage effect and improve the system's energy storage capacity and energy utilization efficiency.

[0054] During the off-peak period of electricity consumption, the cascade high-temperature heat pump module 100 is used to absorb low-grade thermal energy from the external environment and store it in the phase change heat storage module 200. During peak electricity consumption or when the demand for steam is large, the stored thermal energy is used to drive the water vapor compression cycle to produce steam of 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%, the heating 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 reach more than 63%.

[0055] Taking a set of 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 / ton of crude oil. The system has an operating cycle of 24 hours. Figure 2 is a specific example of operating parameters.

[0056] During the specific operation, during the off-peak period (1:00-7:00), the cascade high-temperature heat pump module 100 is driven with a power of 80 MW, 60 MW of thermal energy is stored in the phase change heat storage module 200, and most of the 30 tons / hour steam demand is directly supplied by the cascade high-temperature heat pump module 100; during the electricity price transition period (7:00-12:00), the cascade high-temperature heat pump module 100 is driven with a power of 70 MW, 50 MW of thermal energy is stored in the phase change heat storage module 200, and the 40 tons / hour steam demand is supplied by the cascade high-temperature heat pump module 100 and the phase change heat storage module 200 in coordination; during the peak period (12:00-18:00), the power of the cascade high-temperature heat pump module 100 is reduced to 20 MW, and the phase change heat storage module 200 releases latent heat with a power of 100 MW to meet the 60 tons / hour steam demand. During the peak period (18:00-24:00), the power of the cascade high-temperature heat pump module 100 is reduced to 40 MW, the phase change heat storage module 200 releases latent heat with 80MW power to meet the steam demand of 50 tons / hour, avoiding high electricity price energy consumption. Through the dynamic adjustment of "valley electricity heat storage and peak electricity energy release". Assuming that the steam is saturated steam, the pressure is 10 bar, and its enthalpy value is 2776 kJ / kg, after adopting the energy storage type high temperature heat pump steam generation system 0, it is estimated that about 27,000 tons of standard coal can be saved each year, and about 68,000 tons of carbon dioxide emissions can be reduced, with significant economic and environmental benefits.

[0057] 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 of the above energy storage type high temperature heat pump steam generation systems, combined with Figure 3 , 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 100, the phase change heat storage module 200 and the steam generation module 300 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 100 and the steam generation module 300 to cooperate in the steam supply mode, or triggering the phase change heat storage module 200 and the steam generation module 300 to cooperate in the steam supply mode, where t is the operation time of the cascade high-temperature heat pump module 100; 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 , triggering the cascade high temperature heat pump module 100 to charge the phase change heat storage module 200, or triggering the shutdown mode.

[0058] When the cascade high-temperature heat pump module 100 and the steam generation module 300 work together to provide steam, the low-temperature working fluid is driven by the low-temperature compressor 2 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 interstage 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 by the low-temperature stage on the high-temperature side of the interstage heat exchanger 13, and further increases the heat energy temperature to 120℃~150℃ through step-by-step efficiency improvement; the high-temperature working fluid then enters the condenser 11, transfers heat to the circulating water to raise its temperature to 120℃~130℃, and the heated circulating water converts part of the liquid water into low-pressure saturated steam with a dryness of ≥95% in the flash tank 6 through the principle of pressure reduction flash evaporation, 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 1.0~4.0 MPa high-pressure dry steam output through the water vapor compressor 5.

[0059] 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 electronic expansion valve 10; the inlet of the second three-way valve 9 is connected to the outlet of the heat exchange pipe of the heat storage 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 7→high-temperature circulation pump 8→flash tank 6"; the heat storage medium with a phase change temperature of 80℃~120℃ in the heat storage 7 releases latent heat during the solidification process, and transfers heat energy to the circulating water through the heat exchange pipe, so that it is heated to 120℃~130℃; the high-temperature circulation pump 8 drives the circulating water into the flash tank 6, and flashes at a pressure of 0.3~0.5 MPa to become low-pressure saturated steam with a dryness of ≥95%, and the unvaporized high-temperature circulating water returns to the heat storage 7 through the return water channel to reabsorb heat energy; the low-pressure steam is compressed to 1.0~4.0 by the water vapor compressor 5 MPa high-pressure dry steam output, the inter-stage heat exchanger 13, the high-temperature stage compressor 3 and the low-temperature stage compressor 2 remain in a shutdown state, ensuring that the heat energy is completely supplied independently by the phase change heat storage module 200.

[0060] When the cascade high-temperature heat pump module 100 charges heat to 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 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 heat charging loop of "condenser 11→heat storage 7→high-temperature circulation pump 8"; the low-temperature compressor 2 drives the low-temperature working medium to absorb the external environmental heat energy in the air source evaporator 1, and then transfers the heat energy to the high-temperature working medium through the inter-stage heat exchanger 13 in a step-by-step manner, and the high-temperature working medium heats the circulating water to 120°C~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 7, and the heat storage working medium gradually melts from solid to liquid after absorbing heat, and the heat charging efficiency reaches more than 90%.

[0061] When the energy storage type high temperature heat pump steam generating 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 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 pipe 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 compressor 2 and the high temperature compressor 3 completely stop running.

[0062] The multi-module collaborative control step further includes: When Q steam >0, and c=c v When the cascade high-temperature heat pump module 100 and the steam generation module 300 are in a coordinated steam supply mode, When Q steam >0, and c=c p , follow the following rules: Steam production cost F(T amb ,c,t) <F v (T v ,c v ,t v ), triggering the cascade high-temperature heat pump module 100 and the steam generation module 300 to work in a coordinated steam supply mode; Steam production cost F(T amb ,c,t)≥F v (T v ,c v ,t v ), triggering the phase change heat storage module 200 and the steam generation module 300 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.

[0063] When the energy storage type high temperature heat pump steam generation system 0 detects the steam demand Q steam >0 and in the valley period (c=c v ), the cascade high-temperature heat pump module 100 and the steam generation module 300 are directly triggered to work in a collaborative steam supply mode. At this time, the low-temperature compressor 2 and the high-temperature compressor 3 are started, and the air source evaporator 1 absorbs heat energy from the external environment. After the inter-stage heat exchanger 13 increases the efficiency, the condenser 11 heats the circulating water to 120°C~130°C. The heated circulating water is depressurized and flash-evaporated into steam through the flash tank 6 and is compressed and pressurized for output by the water vapor.

[0064] When Q steam >0, the energy storage type high temperature heat pump steam generation system 0 from the peak and valley period (c=c v ) to the peak 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 ) Dynamically adjust according to the ambient temperature. If the calculated result is lower than the steam production cost threshold F during the off-peak period, v (T v ,c v ,t v ), the cascade high temperature heat pump module 100 and the steam generation module 300 are maintained in a coordinated steam supply mode. If the calculated result is not lower than the steam production cost threshold F during the off-peak period v (T v ,c v ,t v ), switching to the phase change heat storage module 200 and the steam generation module 300 collaborative steam supply mode.

[0065] The conditions for triggering the cascade high temperature heat pump module 100 to charge the phase change heat storage module 200 are: 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 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 hours.

[0066] When the system detects a valley power period (c=c v ) and the heat storage capacity is not full (C v <90%), the conditions for triggering the cascade high temperature heat pump module 100 to charge the phase change heat storage module 200 further include: if the ambient temperature T amb >5℃, the cascade high-temperature heat pump module 100 transfers the ambient heat energy to the heat storage medium of the heat storage device 7 after the inter-stage heat exchanger 13 performs step-by-step efficiency enhancement, so that the heat is absorbed and melted into liquid; if the ambient temperature T amb ≤5℃, the current steam production cost F(T amb ,c,t) and the preset peak power period steam production cost threshold F p (T p ,c p ,t p ) for comparison, only when F(T amb ,c,t) <F p The heat charging is allowed at this time to ensure that the phase change heat storage module 200 preferentially absorbs the heat energy during the low-price valley electricity period, providing economic guarantee for the steam supply during the peak electricity period.

[0067] The trigger conditions for triggering shutdown mode are: 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 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.

[0068] When the energy storage type high temperature heat pump steam generation system 0 detects that there is no steam demand Q steam =0 and any of the following conditions are met, the shutdown mode is triggered: If it is during the peak power period (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 compressor 2 and the high-temperature compressor 3 are completely shut down to avoid high electricity price energy consumption.

[0069] If the heat storage capacity is full (C v≥90%), the heat storage medium is completely melted into liquid and the heat capacity is saturated, the system cuts off the power supply of the interstage 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 7 to ensure that there is no risk of overcharging.

[0070] If it is in the valley period (c=c v ) But the ambient temperature T amb ≤5℃ and the current steam production cost F(T amb ,c,t)≥F p , where F p The steam production cost threshold during the peak power period is reached, and the heat storage medium circulation between the inter-stage heat exchanger 13 and the condenser 11 is immediately closed, and the low-temperature stage compressor 2 and the high-temperature stage compressor 3 are completely stopped.

[0071] The cost of steam production is: ; Among them, η(T amb ) is the energy efficiency of the cascade high temperature heat pump module 100, which is determined by the ambient temperature, the inter-stage heat exchanger 13, the low temperature stage compressor 2 and the high temperature stage compressor 3 performance.

[0072] By adopting the above technical scheme, it is possible to achieve refined control of the energy storage type high temperature heat pump steam generation system, flexibly adjust the system operation mode according to the various parameters detected in real time, ensure that it can operate in the best way under different working conditions, thereby improving the energy utilization efficiency of the system and reducing the operation cost; it can effectively respond to changes in electricity prices and fluctuations in environmental conditions in different periods of time, and by reasonably triggering different steam supply modes and heating modes, while meeting the user's steam demand, maximize the use of low-priced electricity and environmental thermal energy, reduce dependence on high-priced electricity, and improve the economy and sustainability of the system; it can enhance the stability and reliability of the system, and in a complex and changeable operating environment, timely adjust the system's operating status through real-time monitoring and intelligent control 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.

[0073] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may 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. An energy storage type high temperature heat pump steam generation system, characterized in that: include: Cascade high temperature heat pump module, phase change heat storage module and 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 thermal energy released by the phase change heat storage module into high-pressure steam.

2. 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 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 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 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. A control method for an energy storage type high temperature heat pump steam generation system, characterized in that: The control method is used to control the energy storage type high temperature heat pump steam generation system according to any one of claims 1 to 5, and 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.

7. The control method of the energy storage type high temperature heat pump steam generation system according to claim 6, characterized in that: 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.

8. The control method of the energy storage type high temperature heat pump steam generation system according to claim 7, 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.

9. The control method of the energy storage type high temperature heat pump steam generation system according to claim 6, 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.

10. The control method of the energy storage type high temperature heat pump steam generation system according to any one of claims 6 to 9, characterized in that: The steam production cost is: ; 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 interstage heat exchanger, the low-temperature compressor and the high-temperature compressor performance.

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