Heat and power cogeneration system utilizing multi-medium heat energy storage and control method of heat and power cogeneration system

Abstract

The invention discloses a combined heat and power system utilizing multi-medium heat energy storage and a control method of the combined heat and power system, gradient utilization of heat energy is achieved through coupling of a fused salt heat storage power generation system and a heat conduction oil heat storage and supply system, and in order to ensure stable and efficient operation of all parts of the system, the heat energy is stored in the heat conduction oil heat storage and supply system. Inlet and outlet temperature control logic for core assemblies such as a steam generator, a fused salt-heat conduction oil heat exchanger and a heat conduction oil-water heat exchanger is designed, it is guaranteed that the heat energy storage temperature of all media is within a safe and stable working range, and therefore the safety and reliability of the system under different working conditions are guaranteed. Through an accurate temperature control scheme, the system can cope with different loads and external environment changes, and efficient conversion and utilization of heat energy are achieved. The combined heat and power supply system can meet the dual requirements of power generation and heat supply at the same time, the advantage of multi-medium heat energy storage is fully played, and the utilization efficiency of energy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of combined heat and power supply, and particularly relates to a combined heat and power supply system using multi-media thermal energy storage and its control method. Background Art

[0002] Under the background of the "dual carbon" goal, with the continuous growth of energy demand and the increasing awareness of environmental protection, efficient and clean energy utilization methods have become a hot topic in current research. As a comprehensive energy system that can provide both electric energy and heat energy simultaneously, the combined heat and power supply system has attracted much attention due to its characteristics of efficient energy utilization and environmental friendliness. Traditional combined heat and power supply systems often rely on a single energy storage medium, such as hot water or steam, and these systems have certain limitations in terms of energy conversion efficiency and thermal energy storage. To overcome the deficiencies of traditional combined heat and power supply systems, researchers have begun to explore combined heat and power supply systems that use multiple media for thermal energy storage. The multi-media thermal energy storage system can store and release thermal energy in different temperature ranges by using different energy storage media, thereby improving the energy utilization efficiency. Among them, molten salt and heat transfer oil have become preferred media in the multi-media thermal energy storage system due to their good thermal stability and thermal conductivity. Molten salt has a relatively high melting point and heat capacity, and can stably store a large amount of thermal energy at high temperatures. In the field of solar thermal power generation, molten salt is often used as an energy storage medium, which absorbs the heat in the solar collector and stores it, and then releases the thermal energy to generate steam to drive the steam turbine to generate electricity when needed. Heat transfer oil, on the other hand, has a relatively low melting point and good fluidity, and is suitable for medium and low temperature thermal energy storage and transmission. In the heating system, heat transfer oil can absorb the heat in the heat source and transfer the thermal energy to water or other working media through a heat exchanger, thereby realizing the efficient utilization of thermal energy. Combining the advantages of molten salt and heat transfer oil, a combined heat and power supply system using multi-media thermal energy storage has emerged. This system realizes the combined supply of electric energy and heat energy by integrating a molten salt thermal energy storage power generation system and a heat transfer oil thermal energy storage heating system. However, to achieve the efficient and stable operation of this system, multiple technical problems need to be solved, such as the thermal energy transfer efficiency between different media, the control strategy of the system, and the selection and optimization of equipment. Summary of the Invention

[0003] To solve the problems existing in the above-mentioned prior art, the object of the present invention is to propose a combined heat and power supply system using multi-medium thermal energy storage and its control method. The system consists of two major parts: a molten salt thermal energy storage power generation system and a heat transfer oil thermal energy storage heating system. The molten salt thermal energy storage power generation system heats the molten salt through a solar collector, and uses the hot salt to generate steam to drive a steam turbine to generate electricity while providing thermal energy. The heat transfer oil system transfers heat to the heat transfer oil by exchanging heat between the molten salt and the heat transfer oil, and then supplies heat to the heat exchanger of the heating network through a heat transfer oil-water heat exchanger. The control method adjusts the temperature and the operation of the pump by using the PID control logic through real-time monitoring of various temperature and flow parameters, ensuring the efficient and stable operation of the system, being able to provide both electricity and thermal energy, and optimizing the energy utilization efficiency.

[0004] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0005] A combined heat and power supply system using multi-medium thermal energy storage, comprising a molten salt thermal energy storage power generation system and a heat transfer oil thermal energy storage heating system;

[0006] The molten salt thermal energy storage power generation system includes a solar collector 1-1, a high-temperature molten salt storage tank 1-2, a first molten salt pump 1-9, a first molten salt valve 1-10, a steam generator 1-3, a medium-temperature molten salt storage tank 1-4, a second molten salt pump 1-14, a second molten salt valve 1-15, a molten salt - heat transfer oil heat exchanger 1-5, a low-temperature molten salt storage tank 1-6, a third molten salt pump 1-16, a third molten salt valve 1-17, a feed water pump 1-12, a steam valve 1-11, a steam turbine 1-8, a generator 1-13 and a condenser 1-7; wherein the molten salt from the low-temperature molten salt storage tank 1-6 is successively sent into the solar collector 1-1 through the third molten salt pump 1-16 and the third molten salt valve 1-17, and the generated high-temperature molten salt enters the high-temperature molten salt storage tank 1-2. Then the high-temperature molten salt successively passes through the first molten salt pump 1-9 and the first molten salt valve 1-10 and is sent into the steam generator 1-3. In the steam generator 1-3, the molten salt releases heat to heat water to generate steam. Then the medium-temperature molten salt enters the medium-temperature molten salt storage tank 1-4. The medium-temperature molten salt then successively passes through the second molten salt pump 1-14 and the second molten salt valve 1-15 and enters the molten salt - heat transfer oil heat exchanger 1-5. The molten salt in the molten salt - heat transfer oil heat exchanger 1-5 exchanges heat with the heat transfer oil, and the outlet low-temperature molten salt returns to the low-temperature molten salt storage tank 1-6 to complete the cycle; the water from the condenser 1-7 is sent into the steam generator 1-3 through the feed water pump 1-12, and the generated steam enters the steam turbine 1-8 to do work through the steam valve 1-11. The generated mechanical energy is output as electric energy outward through the generator 1-13, and the steam after doing work in the steam turbine 1-8 enters the condenser 1-7 to be cooled into water to complete the cycle;

[0007] The heat-conducting oil heat storage and heat supply system includes a low-temperature heat-conducting oil storage tank 2-1, a first heat-conducting oil pump 2-3, a first heat-conducting oil valve 2-6, a molten salt-heat-conducting oil heat exchanger 1-5, a high-temperature heat-conducting oil storage tank 2-7, a second heat-conducting oil pump 2-8, a second heat-conducting oil valve 2-9, a heat-conducting oil-water heat exchanger 2-2, a circulating water pump 2-4, a water valve 2-5, and a heat supply network heat exchanger 2-10. The heat-conducting oil in the low-temperature heat-conducting oil storage tank 2-1 sequentially enters the molten salt-heat-conducting oil heat exchanger 1-5 through the first heat-conducting oil pump 2-3 and the first heat-conducting oil valve 2-6. The heat-conducting oil is heated by the medium-temperature molten salt, and the generated high-temperature heat-conducting oil enters the high-temperature heat-conducting oil storage tank 2-7. The heat-conducting oil at the outlet of the high-temperature heat-conducting oil storage tank 2-7 sequentially passes through the second heat-conducting oil pump 2-8 and the second heat-conducting oil valve 2-9 and enters the heat-conducting oil-water heat exchanger 2-2 to heat the water. The low-temperature heat-conducting oil at the outlet enters the low-temperature heat-conducting oil storage tank 2-1 to complete the cycle. The cold water at the outlet of the heat supply network heat exchanger 2-10 sequentially passes through the circulating water pump 2-4 and the water valve 2-5 and enters the heat-conducting oil-water heat exchanger 2-2 to generate high-temperature water and supply it to the heat supply network heat exchanger 2-10 to complete the cycle.

[0008] In the molten salt heat storage power generation system, the main circulating working medium is molten salt. The operating temperature of the molten salt in the high-temperature molten salt storage tank 1-2 is 450°C to 550°C, and the operating temperature of the molten salt in the medium-temperature molten salt storage tank 1-4 is 275°C to 325°C. The operating temperature of the molten salt in the low-temperature molten salt storage tank 1-6 is 190°C to 220°C.

[0009] In the heat-conducting oil heat storage and heat supply system, the main circulating working medium is heat-conducting oil. The operating temperature of the heat-conducting oil in the low-temperature heat-conducting oil storage tank 2-1 is 130°C to 150°C, and the operating temperature of the heat-conducting oil in the high-temperature heat-conducting oil storage tank 2-7 is 160°C to 180°C.

[0010] The solar collector 1-1 is a tower-type solar collector. The steam generator 1-3 is composed of three shell-and-tube heat exchangers in parallel. In each shell-and-tube heat exchanger, the molten salt flows on the shell side and the water flows on the tube side. The molten salt-heat-conducting oil heat exchanger 1-5 is a shell-and-tube heat exchanger, where the molten salt flows on the tube side and the heat-conducting oil flows on the shell side. The heat-conducting oil-water heat exchanger 2-2 is a shell-and-tube heat exchanger, where the heat-conducting oil flows on the shell side and the water flows on the tube side.

[0011] The control method of a combined heat and power supply system using multi-medium thermal energy storage is controlled by a measurement and control unit.

[0012] The measurement and control unit includes a first thermocouple 3-1 for monitoring the temperature of molten salt in the high-temperature molten salt storage tank 1-2, a second thermocouple 3-2 for monitoring the temperature of molten salt in the medium-temperature molten salt storage tank 1-4, a third thermocouple 3-3 for monitoring the temperature of molten salt in the low-temperature molten salt storage tank 1-6, a fourth thermocouple 3-4 for monitoring the temperature of heat-conducting oil in the low-temperature heat-conducting oil tank 2-1, a fifth thermocouple 3-5 for monitoring the temperature of the water at the outlet of the water pipeline of the heat-conducting oil-water heat exchanger 2-2, a sixth thermocouple 3-6 for monitoring the temperature of water in the heat supply network heat exchanger 2-10, a seventh thermocouple 3-7 for monitoring the temperature of heat-conducting oil in the high-temperature heat-conducting oil tank 2-7, an eighth thermocouple 3-8 for monitoring the temperature of the steam at the outlet of the steam generator 1-3, a first flowmeter 3-9 for monitoring the flow rate of molten salt in the pipeline between the high-temperature molten salt storage tank 1-2 and the steam generator 1-3, a third flowmeter 3-11 for monitoring the flow rate of heat-conducting oil in the pipeline between the low-temperature heat-conducting oil tank 2-1 and the molten salt-heat-conducting oil heat exchanger 1-5, a second flowmeter 3-10 for monitoring the flow rate of heat-conducting oil in the pipeline between the high-temperature heat-conducting oil tank 2-7 and the heat-conducting oil-water heat exchanger 2-2, a fourth flowmeter 3-12 for monitoring the flow rate of molten salt in the pipeline between the medium-temperature molten salt storage tank 1-4 and the molten salt-heat-conducting oil heat exchanger 1-5; a fifth flowmeter 3-13 for monitoring the steam flow rate in the steam generator 1-3;

[0013] The control method includes a temperature control logic for the molten salt-heat-conducting oil heat exchanger 1-5, a temperature control logic for the heat-conducting oil-water heat exchanger 2-2, and a temperature control logic for the steam generator 1-3:

[0014] 1) Temperature control logic for the molten salt-heat-conducting oil heat exchanger 1-5

[0015] When the system is running, obtain the real-time value T of the temperature of the low-temperature molten salt storage tank 1-6 ls,rt and the set value T of the temperature of the low-temperature molten salt storage tank 1-6 ls,st Compare them in the comparator Δ 1 to obtain the molten salt temperature adjustment amount ΔT l ;

[0016] Input the molten salt temperature adjustment amount ΔT 1 in the PID 1 control to obtain the second molten salt pump power adjustment amount ΔP 1 :

[0017]

[0018] In the formula: K p1 is the proportional gain, K i1 is the integral gain, K d1 is the derivative gain;

[0019] Apply the obtained second molten salt pump power adjustment amount ΔP 1 to the second molten salt pump 1-14 to generate a control signal for the second molten salt pump 1-14;

[0020] Obtain the real-time value T of the temperature of the high-temperature heat-conducting oil tank 2-7 ho,rt , and the set value T of the temperature of the high-temperature heat-conducting oil tank 2-7 ho,st Compare them in the comparator Δ 2 to obtain the adjustment amount ΔT of the heat-conducting oil temperature 2 ;

[0021] Input the power adjustment amount ΔP obtained by the PID 1 controller and the adjustment amount ΔT of the heat-conducting oil temperature 1 into the processing unit F 2 (x) to obtain a new adjustment amount ΔT of the heat-conducting oil temperature 1 ; 3 ;

[0022] ΔT 3 = k 1 ΔT 2 ;

[0023]

[0024] In the formula: k 1 is the proportionality coefficient, q s1 is the adjusted molten salt flow rate, Cp s1 is the specific heat capacity of the molten salt, q o1 is the heat-conducting oil flow rate, Cp o1 is the specific heat capacity of the heat-conducting oil;

[0025] Input the new adjustment amount ΔT of the heat-conducting oil temperature 3 in the PID 2 control to obtain the first power adjustment amount ΔP of the heat-conducting oil pump 2 :

[0026]

[0027] In the formula: K p2 is the proportional gain, K i2 is the integral gain, K d2 is the derivative gain;

[0028] Apply the obtained first power adjustment amount ΔP of the heat-conducting oil pump 2 to the first heat-conducting oil pump 2-3 to generate a control signal for the first heat-conducting oil pump 2-3;

[0029] Finally, form the temperature adjustment control logic of the molten salt-heat-conducting oil heat exchanger 1-5;

[0030] 2) Temperature control logic of the heat-conducting oil-water heat exchanger 2-2

[0031] By taking the real-time value T of the temperature at the water outlet of the water path of the heat-conducting oil-water heat exchanger hw,rtWith the set value T of the water outlet temperature of the heat transfer oil - water heat exchanger water circuit hw,st In the comparator Δ 3 Compare to obtain the adjustment amount ΔT of the water outlet temperature of the heat transfer oil - water heat exchanger water circuit 4 ;

[0032] Input the adjustment amount ΔT of the water outlet temperature of the heat transfer oil - water heat exchanger water circuit 4 In the PID 3 Control to obtain the third power adjustment amount ΔP 3 :

[0033]

[0034] Where: K p3 Is the proportional gain, K i3 Is the integral gain, K d3 Is the derivative gain;

[0035] Apply the obtained third power adjustment amount ΔP 3 To the circulating water pump 2 - 4 to generate a control signal for the circulating water pump 2 - 4;

[0036] Obtain the real - time value T of the temperature of the low - temperature heat transfer oil tank 2 - 1 according to the operation of the system lo,rt , and the set value T of the temperature of the low - temperature heat transfer oil tank 2 - 1 lo,st In the comparator Δ 4 Compare to obtain the adjustment amount ΔT of the low - temperature heat transfer oil temperature 5 ;

[0037] Input the third power adjustment amount ΔP obtained by the PID 3 Controller and the adjustment amount ΔT of the low - temperature heat transfer oil temperature 3 Into the processing unit F 5 (x) to obtain a new adjustment amount ΔT of the low - temperature heat transfer oil temperature 2 ; 6 ;

[0038] ΔT 6 = k 2 ΔT 5 ;

[0039]

[0040] Where: k 2 Is the proportional coefficient, q w1 Is the adjusted circulating water flow rate, Cp w1 Is the specific heat capacity of water, q o2 Is the heat transfer oil flow rate, Cp o2 Is the specific heat capacity of the heat transfer oil;

[0041] Input the new adjustment amount ΔT of the low - temperature heat transfer oil temperature6 Obtain the second heat transfer oil pump power adjustment amount ΔP 4 in the PID control: 4 :

[0042]

[0043] Where: K p4 is the proportional gain, K i4 is the integral gain, K d4 is the derivative gain;

[0044] The obtained second heat transfer oil pump power adjustment amount ΔP 4 is superimposed on the second heat transfer oil pump 2-8 corresponding to the low-temperature heat transfer oil temperature adjustment scheme to generate a control signal for the second heat transfer oil pump 2-8;

[0045] Finally, form the temperature adjustment control logic of the heat transfer oil - water heat exchanger;

[0046] 3) Steam generator temperature control logic

[0047] Obtain the real-time value T of the steam outlet temperature of the steam generator according to the operation of the system st,rt , and compare it with the steam outlet temperature set value T st,st in the comparator Δ 5 to obtain the steam outlet temperature adjustment amount ΔT 7 ;

[0048] Input the steam outlet temperature adjustment value ΔT 7 in the PID control 5 to obtain the feed water pump power adjustment amount ΔP 5 :

[0049]

[0050] Where: K p5 is the proportional gain, K i5 is the integral gain, K d5 is the derivative gain;

[0051] The obtained feed water pump power adjustment amount ΔP 5 acts on the feed water pump 1-12 to generate a control signal for the feed water pump 1-12;

[0052] Obtain the real-time value T of the temperature of the medium-temperature molten salt storage tank 1-4 according to the operation of the system ms,rt and compare it with the temperature set value T of the medium-temperature molten salt storage tank 1-4 ms,st in the comparator Δ 6 to obtain the temperature adjustment amount ΔT of the medium-temperature molten salt storage tank 8 ;

[0053] Input the PID5 The feed pump power regulation amount ΔP obtained by the controller 5 and the intermediate temperature molten salt temperature regulation amount ΔT 8 are input into the processing unit F 3 to obtain a new intermediate temperature molten salt tank temperature regulation amount ΔT from (x) 9 ;

[0054] ΔT 9 = k 3 ΔT 8 ;

[0055]

[0056] where: k 3 is the proportionality coefficient, q st is the steam flow rate after regulation, Cp st is the specific heat capacity of steam, q s2 is the molten salt flow rate, Cp o2 is the specific heat capacity of molten salt;

[0057] The new intermediate temperature molten salt tank temperature regulation amount ΔT is input 9 in the PID 6 control to obtain the first molten salt pump power regulation amount ΔP 6 :

[0058]

[0059] where: K p6 is the proportional gain, K i6 is the integral gain, K d6 is the derivative gain;

[0060] The obtained first molten salt pump power regulation amount ΔP 6 acts on the first molten salt pump 1-9 to generate the latest power P of the first molten salt pump 1-9 new6 ;

[0061] Finally, a steam generator temperature regulation control logic is formed.

[0062] The present invention aims to improve energy utilization efficiency and reduce operating costs by optimizing the system structure and control strategy, and provides an efficient and clean energy utilization solution for the energy field. Compared with the prior art, the present invention has the following advantages:

[0063] 1. By combining the molten salt thermal energy storage power generation system with the heat transfer oil thermal energy storage heating system, the present invention realizes power generation and heating simultaneously. This dual-function design improves energy utilization efficiency and can maximize the utilization of thermal energy, not only meeting the power demand but also providing a stable thermal energy supply for the heat exchanger of the heating pipe network.

[0064] 2. The system of the present invention utilizes PID control logic to precisely adjust the system based on real-time temperature and flow data, ensuring stable operation of the system under different loads and operating conditions, avoiding overheating or insufficient heating, and introducing heat transfer oil as an intermediate heat exchange medium between molten salt and hot water supply, thus avoiding the problem of easy condensation of molten salt when encountering low-temperature water, and improving the operating efficiency and reliability. By precisely adjusting the temperature regulation and flow control under different operating conditions, the system can dynamically adjust its operating state according to actual needs, improving flexibility and adaptability. Especially when the power generation and heating demands are unstable, the system can efficiently adjust the resource allocation to ensure the optimal configuration of energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 It is a configuration of a combined heat and power generation system using multi-media thermal energy storage.

[0066] Figure 2 It is the temperature control logic of the molten salt - heat transfer oil heat exchanger.

[0067] Figure 3 It is the temperature control logic of the heat transfer oil - water heat exchanger.

[0068] Figure 4 It is the temperature control logic of the steam generator. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0069] The present invention will be further described below with reference to the accompanying drawings.

[0070] As Figure 1Shown is a combined heat and power system using multi-media thermal energy storage, including a molten salt thermal energy storage power generation system and a heat transfer oil thermal energy storage heating system; the molten salt thermal energy storage power generation system includes a solar collector 1-1, a high-temperature molten salt storage tank 1-2, a first molten salt pump 1-10, a first molten salt valve 1-10, a steam generator 1-3, a medium-temperature molten salt storage tank 1-4, a second molten salt pump 1-14, a second molten salt valve 1-15, a molten salt - heat transfer oil heat exchanger 1-5, a low-temperature molten salt storage tank 1-6, a third molten salt pump 1-16, a third molten salt valve 1-17, a feed water pump 1-12, a steam valve 1-11, a steam turbine 1-8, a generator 1-13, and a condenser 1-7; among them, the molten salt from the low-temperature molten salt storage tank 1-6 is successively sent into the solar collector 1-1 through the third molten salt pump 1-16 and the third molten salt valve 1-17, and the generated high-temperature molten salt enters the high-temperature molten salt storage tank 1-2. Then, the high-temperature molten salt successively passes through the first molten salt pump 1-9 and the first molten salt valve 1-10 and is sent into the steam generator 1-3. In the steam generator 1-3, the molten salt releases heat to heat water to generate steam. Then, the medium-temperature molten salt enters the medium-temperature molten salt storage tank 1-4. The medium-temperature molten salt then successively passes through the second molten salt pump 1-14 and the second molten salt valve 1-15 and enters the molten salt - heat transfer oil heat exchanger 1-5. The molten salt in the molten salt - heat transfer oil heat exchanger 1-5 exchanges heat with the heat transfer oil, and the outlet low-temperature molten salt returns to the low-temperature molten salt storage tank 1-6 to complete the cycle; the water from the condenser 1-7 is sent into the steam generator 1-3 through the feed water pump 1-12, and the generated steam enters the steam turbine 1-8 to do work after passing through the steam valve 1-11. The generated mechanical energy is output as electrical energy outward through the generator 1-13. The steam after doing work in the steam turbine 1-8 enters the condenser 1-7 to be cooled into water to complete the cycle;

[0071] The heat transfer oil thermal energy storage heating system includes a low-temperature heat transfer oil storage tank 2-1, a first heat transfer oil pump 2-3, a first heat transfer oil valve 2-6, a molten salt - heat transfer oil heat exchanger 1-5, a high-temperature heat transfer oil storage tank 2-7, a second heat transfer oil pump 2-8, a second heat transfer oil valve 2-9, a heat transfer oil - water heat exchanger 2-2, a circulating water pump 2-4, a water valve 2-5, and a heat supply network heat exchanger 2-10; among them, the heat transfer oil in the low-temperature heat transfer oil storage tank 2-1 successively enters the molten salt - heat transfer oil heat exchanger 1-5 through the first heat transfer oil pump 2-3 and the first heat transfer oil valve 2-6, uses the medium-temperature molten salt to heat the heat transfer oil, and the generated high-temperature heat transfer oil enters the high-temperature heat transfer oil storage tank 2-7. The heat transfer oil at the outlet of the high-temperature heat transfer oil storage tank 2-7 successively passes through the second heat transfer oil pump 2-8 and the second heat transfer oil valve 2-9 and enters the heat transfer oil - water heat exchanger 2-2 to heat the water. The outlet low-temperature heat transfer oil enters the low-temperature heat transfer oil storage tank 2-1 to complete the cycle; the cold water at the outlet of the heat supply network heat exchanger 2-10 successively passes through the circulating water pump 2-4 and the water valve 2-5 and enters the heat transfer oil - water heat exchanger 2-2 to generate high-temperature water for the heat supply network heat exchanger 2-10 to complete the cycle.

[0072] Preferably, the main circulating working fluid in the molten salt thermal energy storage power generation system is molten salt; the operating temperature of the molten salt in the high-temperature molten salt storage tank 1-2 is 450°C to 550°C, and the operating temperature of the molten salt in the medium-temperature molten salt storage tank 1-4 is 275°C to 325°C; the operating temperature of the molten salt in the low-temperature molten salt storage tank 1-6 is 190°C to 220°C. By setting molten salt storage tanks (high-temperature, medium-temperature, low-temperature) in multiple temperature ranges, heat energy can be stored and transferred at different temperature segments. The high-temperature storage tank can provide sufficient heat to support power generation, while the medium-temperature and low-temperature storage tanks can provide heat energy for heating.

[0073] Preferably, the main circulating working fluid in the heat transfer oil thermal energy storage and heating system is heat transfer oil. The operating temperature of the heat transfer oil in the low-temperature heat transfer oil storage tank 2-1 is 130°C to 150°C, and the operating temperature of the heat transfer oil in the high-temperature heat transfer oil storage tank 2-7 is 160°C to 180°C. The heat transfer oil system provides heat transfer within different temperature ranges. The low-temperature heat transfer oil is suitable for heating with low-temperature requirements, while the high-temperature heat transfer oil is suitable for heat exchange with molten salt to prevent the molten salt from directly exchanging heat with low-temperature media and causing condensation problems.

[0074] Preferably, the solar collector 1-1 is a tower-type solar collector, and the steam generator 1-3 is composed of three shell-and-tube heat exchangers in parallel. In each shell-and-tube heat exchanger, the molten salt flows on the shell side and water flows on the tube side; the molten salt - heat transfer oil heat exchanger 1-5 is a shell-and-tube heat exchanger, where the molten salt flows on the tube side and the heat transfer oil flows on the shell side; the heat transfer oil - water heat exchanger 2-2 is a shell-and-tube heat exchanger, with the heat transfer oil flowing on the shell side and water flowing on the tube side. The tower-type solar collector can concentrate and effectively collect solar energy, store the heat energy through molten salt and transfer it to subsequent systems. Compared with flat-plate collectors, the tower-type collector can achieve higher heat energy collection efficiency in a smaller space and can heat the molten salt to the above temperatures. The design of the steam generator, molten salt - heat transfer oil heat exchanger, and heat transfer oil - water heat exchanger constructs an efficient heat exchange process. The heat energy transfer between different media ensures the efficient operation of the system at multiple temperature segments. Each stage of the heat exchanger can adjust the temperature and transfer heat as needed, avoiding energy waste. The design of using shell-and-tube heat exchangers helps to improve the heat exchange efficiency, and through different flow modes of fluids, the temperature and heat energy flow direction can be flexibly adjusted under different working conditions to optimize the heat energy transfer process.

[0075] The control method of a combined heat and power supply system using multi-media thermal energy storage is controlled by a measurement and control unit;

[0076] The measurement and control unit includes a first thermocouple 3-1 for monitoring the temperature of the molten salt in the high-temperature molten salt storage tank 1-2, a second thermocouple 3-2 for monitoring the temperature of the molten salt in the medium-temperature molten salt storage tank 1-4, a third thermocouple 3-3 for monitoring the temperature of the molten salt in the low-temperature molten salt storage tank 1-6, a fourth thermocouple 3-4 for monitoring the temperature of the heat transfer oil in the low-temperature heat transfer oil tank 2-1, a fifth thermocouple 3-5 for monitoring the water temperature at the outlet of the water pipeline of the heat transfer oil-water heat exchanger 2-2, a sixth thermocouple 3-6 for monitoring the water temperature in the heat supply network heat exchanger 2-10, a seventh thermocouple 3-7 for monitoring the temperature of the heat transfer oil in the high-temperature heat transfer oil tank 2-7, an eighth thermocouple 3-8 for monitoring the steam temperature at the outlet of the steam generator 1-3, a first flowmeter 3-9 for monitoring the molten salt flow rate in the pipeline between the high-temperature molten salt storage tank 1-2 and the steam generator 1-3, a third flowmeter 3-11 for monitoring the heat transfer oil flow rate in the pipeline between the low-temperature heat transfer oil tank 2-1 and the molten salt-heat transfer oil heat exchanger 1-5, a second flowmeter 3-10 for monitoring the heat transfer oil flow rate in the pipeline between the high-temperature heat transfer oil tank 2-7 and the heat transfer oil-water heat exchanger 2-2, a fourth flowmeter 3-12 for monitoring the molten salt flow rate in the pipeline between the medium-temperature molten salt storage tank 1-4 and the molten salt-heat transfer oil heat exchanger 1-5; a fifth flowmeter 3-13 for monitoring the steam flow rate in the steam generator 1-3;

[0077] The control method includes the temperature control logic of the molten salt-heat transfer oil heat exchanger 1-5, the temperature control logic of the heat transfer oil-water heat exchanger 2-2, and the temperature control logic of the steam generator 1-3.

[0078] As Figure 2 shown is the temperature control logic of the molten salt-heat transfer oil heat exchanger 1-5. Among them, Process 1: Input the set value of the temperature of the low-temperature molten salt storage tank 1-6 into the comparator Δ1; Process 2: Send the measured temperature of the low-temperature molten salt storage tank 1-6 to the comparator Δ1; Process 3: Generate a temperature deviation signal and send it into the PID 1 controller; Process 4: The PID 1 controller converts the input temperature deviation signal into a power adjustment signal for the second molten salt pump 1-14 and sends it to the power execution unit of the second molten salt pump 1-14; Process 5: Send the power control signal of the second molten salt pump 1-14 generated by the PID 1 controller to the processing unit F 1 (x); Process 6: Input the set value of the temperature of the high-temperature heat transfer oil tank 2-7 into the comparator Δ2; Process 7: Send the measured temperature of the high-temperature heat transfer oil tank 2-7 to the comparator Δ2; Process 8: Generate a temperature deviation signal for the high-temperature heat transfer oil tank 2-7 and send it to the processing unit F 1 (x); Process 9: Generate a new temperature deviation signal for the high-temperature heat transfer oil in the processing unit F 1 (x) and send it into the PID 2In the controller; Process 10: In the PID controller, the input temperature deviation signal is converted into a regulating signal for the first heat transfer oil pump 2-3 and sent to the execution unit of the first heat transfer oil pump 2-3.

[0079] As Figure 3 shown in the temperature control logic of the heat transfer oil - water heat exchanger. Among them, Process 1: The set value of the water outlet temperature of the water circuit of the heat transfer oil - water heat exchanger is input into the comparator Δ3; Process 2: The measured water outlet temperature of the water circuit of the heat transfer oil - water heat exchanger is sent to the comparator Δ3; Process 3: A temperature deviation signal is generated and sent into the PID 3 controller; Process 4: The PID 3 controller converts the input temperature deviation signal into a power regulating signal for the circulating water pump 2-4 and sends it to the power execution unit of the circulating water pump 2-4; Process 5: The power control signal of the circulating water pump 2-4 generated by the PID 3 controller is sent to the processing unit F 2 (x); Process 6: The set value of the temperature of the low-temperature heat transfer oil tank 2-1 is input into the comparator Δ4; Process 7: The measured temperature of the low-temperature heat transfer oil tank 2-1 is sent to the comparator Δ4; Process 8: A temperature deviation signal of the low-temperature heat transfer oil tank 2-1 is generated and sent to the processing unit F 2 (x); Process 9: In the processing unit F 2 (x), a new temperature deviation signal of the low-temperature heat transfer oil is generated and sent into the PID 4 controller; Process 10: The PID 4 controller converts the input temperature deviation signal into a regulating signal for the second heat transfer oil pump 2-8 and sends it to the execution unit of the second heat transfer oil pump 2-8.

[0080] As Figure 4 shown in the temperature control logic of the steam generator. Among them, Process 1: The set value of the steam outlet temperature of the steam generator is input into the comparator Δ5; Process 2: The measured steam outlet temperature of the steam generator is sent to the comparator Δ5; Process 3: A temperature deviation signal is generated and sent into the PID 5 controller; Process 4: The PID 5 controller converts the input temperature deviation signal into a power regulating signal for the feed water pump 1-12 and sends it to the power execution unit of the feed water pump 1-12; Process 5: The power control signal of the feed water pump 1-12 generated by the PID 5 is sent to the processing unit F 3 (x); Process 6: The set value of the temperature of the medium-temperature molten salt storage tank 1-4 is input into the comparator Δ6; Process 7: The measured temperature of the medium-temperature molten salt storage tank 1-4 is sent to the comparator Δ6; Process 8: A temperature deviation signal of the medium-temperature molten salt storage tank 1-4 is generated and sent to the processing unit F 3 (x); Process 9: In the processing unit F3 A new medium-temperature molten salt temperature deviation signal is generated in (x) and sent to the PID 6 controller; Process 10: PID 6 In the controller, the input temperature deviation signal is converted into a first molten salt pump 1-10 adjustment signal and sent to the first molten salt pump 1-10 execution unit.

Claims

1. A combined heat and power system using multi-medium thermal energy storage, characterized in that: The cogeneration system comprises a molten salt heat storage power generation system and a thermal oil heat storage heating system; The molten salt heat storage power generation system comprises a solar collector (1-1), a high-temperature molten salt storage tank (1-2), a first molten salt pump (1-9), a first molten salt valve (1-10), a steam generator (1-3), a medium-temperature molten salt storage tank (1-4), a second molten salt pump (1-14), a second molten salt valve (1-15), a molten salt-heat transfer oil heat exchanger (1-5), a low-temperature molten salt storage tank (1-6), a third molten salt pump (1-16), a third molten salt valve (1-17 ... -17), a feed water pump (1-12), a steam valve (1-11), a steam turbine (1-8), a generator (1-13) and a condenser (1-7); wherein the molten salt from the low-temperature molten salt storage tank (1-6) is sequentially fed into the solar collector (1-1) through the third molten salt pump (1-16) and the third molten salt valve (1-17), and the generated high-temperature molten salt enters the high-temperature molten salt storage tank (1-2), and then the high-temperature molten salt is sequentially fed into the first molten salt pump (1-16) and the third molten salt valve (1-17). 9) and the first molten salt valve (1-10), and is sent to the steam generator (1-3). In the steam generator (1-3), the molten salt releases heat to heat the water to generate steam. Then the medium-temperature molten salt enters the medium-temperature molten salt storage tank (1-4). The medium-temperature molten salt then passes through the second molten salt pump (1-14) and the second molten salt valve (1-15) in sequence and enters the molten salt-heat transfer oil heat exchanger (1-5). The molten salt in the molten salt-heat transfer oil heat exchanger (1-5) exchanges heat with the heat transfer oil. The low-temperature molten salt at the outlet returns to the low-temperature molten salt storage tank (1-6), completing the cycle; the water from the condenser (1-7) is sent to the steam generator (1-3) through the water supply pump (1-12), and the generated steam passes through the steam valve (1-11) and enters the steam turbine (1-8) to perform work. The generated mechanical energy is output to the outside through the generator (1-13). The steam from the steam turbine (1-8) after performing work enters the condenser (1-7) to be cooled and turned into water, completing the cycle; The thermal oil heat storage and heating system comprises a low-temperature thermal oil tank (2-1), a first thermal oil pump (2-3), a first thermal oil valve (2-6), a molten salt-thermal oil heat exchanger (1-5), a high-temperature thermal oil tank (2-7), a second thermal oil pump (2-8), a second thermal oil valve (2-9), a thermal oil-water heat exchanger (2-2), a circulating water pump (2-4), a water valve (2-5) and a heating pipe network heat exchanger (2-10); The heat transfer oil in the low-temperature heat transfer oil tank (2-1) passes through the first heat transfer oil pump (2-3) and the first heat transfer oil valve (2-6) in sequence and enters the molten salt-heat transfer oil heat exchanger (1-5). The heat transfer oil is heated by the medium-temperature molten salt, and the generated high-temperature heat transfer oil enters the high-temperature heat transfer oil tank (2-7). The heat transfer oil at the outlet of the high-temperature heat transfer oil tank (2-7) passes through the second heat transfer oil pump (2-8) and the second heat transfer oil valve (2-9) in sequence and enters the heat transfer oil-water heat exchanger (2-2) to heat the water. The low-temperature heat transfer oil at the outlet enters the low-temperature heat transfer oil tank (2-1), completing the cycle. The cold water at the outlet of the heat supply pipe network heat exchanger (2-10) passes through the circulating water pump (2-4) and the water valve (2-5) in sequence and enters the heat transfer oil-water heat exchanger (2-2), generating high-temperature water that is provided to the heat supply pipe network heat exchanger (2-10), completing the cycle.

2. A combined heat and power system using multi-medium thermal energy storage according to claim 1, characterized in that: The main circulating working fluid in the molten salt heat storage power generation system is molten salt; the operating temperature of the molten salt in the high-temperature molten salt storage tank (1-2) is 450°C to 550°C, the operating temperature of the molten salt in the medium-temperature molten salt storage tank (1-4) is 275°C to 325°C; and the operating temperature of the molten salt in the low-temperature molten salt storage tank (1-6) is 190°C to 220°C.

3. A combined heat and power system using multi-medium thermal energy storage according to claim 1, characterized in that: The main circulating working fluid of the thermal oil heat storage and heating system is thermal oil, wherein the operating temperature of the thermal oil in the low-temperature thermal oil tank (2-1) is 130°C to 150°C, and the operating temperature of the thermal oil in the high-temperature thermal oil tank (2-7) is 160°C to 180°C.

4. A combined heat and power system using multi-medium thermal energy storage according to claim 1, characterized in that: The solar collector (1-1) is a tower solar collector. The steam generator (1-3) is composed of three shell and tube heat exchangers connected in parallel. In each shell and tube heat exchanger, molten salt flows on the shell side and water flows on the tube side. The molten salt-heat transfer oil heat exchanger (1-5) is a shell and tube heat exchanger. The molten salt flows on the tube side and the heat transfer oil flows on the shell side. The heat transfer oil-water heat exchanger (2-2) is a shell and tube heat exchanger. The heat transfer oil flows on the shell side and water flows on the tube side.

5. A control method for a combined heat and power system using multi-medium thermal energy storage according to any one of claims 1 to 4, characterized in that: Control via measurement control unit; The measurement control unit comprises a first thermocouple (3-1) for monitoring the temperature of molten salt in a high-temperature molten salt storage tank (1-2), a second thermocouple (3-2) for monitoring the temperature of molten salt in a medium-temperature molten salt storage tank (1-4), a third thermocouple (3-3) for monitoring the temperature of molten salt in a low-temperature molten salt storage tank (1-6), a fourth thermocouple (3-4) for monitoring the temperature of heat transfer oil in a low-temperature heat transfer oil tank (2-1), a fifth thermocouple (3-5) for monitoring the temperature of water at the outlet of a water pipeline of a heat transfer oil-water heat exchanger (2-2), a sixth thermocouple (3-6) for monitoring the temperature of water in a heat supply network heat exchanger (2-10), a seventh thermocouple (3-7) for monitoring the temperature of heat transfer oil in a high-temperature heat transfer oil tank (2-7), and a fourth thermocouple (3-4) for monitoring the temperature of heat transfer oil in a low-temperature heat transfer oil tank (2-1). -3) an eighth thermocouple (3-8) for monitoring the outlet steam temperature, a first flowmeter (3-9) for monitoring the molten salt flow rate in the high-temperature molten salt storage tank (1-2) and the steam generator (1-3) pipeline, a third flowmeter (3-11) for monitoring the heat transfer oil flow rate in the low-temperature heat transfer oil tank (2-1) and the molten salt-heat transfer oil heat exchanger (1-5) pipeline, a second flowmeter (3-10) for monitoring the heat transfer oil flow rate in the high-temperature heat transfer oil tank (2-7) and the heat transfer oil-water heat exchanger (2-2) pipeline, a fourth flowmeter (3-12) for monitoring the molten salt flow rate in the medium-temperature molten salt storage tank (1-4) and the molten salt-heat transfer oil heat exchanger (1-5) pipeline; a fifth flowmeter (3-13) for monitoring the steam flow rate in the steam generator (1-3); The control method includes a temperature control logic of a molten salt-heat transfer oil heat exchanger (1-5), a temperature control logic of a heat transfer oil-water heat exchanger (2-2) and a temperature control logic of a steam generator (1-3): 1) Molten salt-thermal oil heat exchanger (1-5) temperature control logic When the system is running, obtain the real-time temperature value T of the low-temperature molten salt storage tank (1-6) ls,rt The temperature setting value T of the low temperature molten salt storage tank (1-6) ls,st Comparison is performed at comparator Δ1 to obtain the molten salt temperature adjustment value ΔT l ; Input the molten salt temperature adjustment value ΔT1 to obtain the second molten salt pump power adjustment value ΔP1 in PID1 control: Where: K p1 is the proportional gain, K i1 is the integral gain, K d1 is the differential gain; Applying the obtained second molten salt pump power adjustment amount ΔP1 to the second molten salt pump (1-14) to generate a control signal for the second molten salt pump (1-14); Get the real-time temperature value T of the high-temperature thermal oil tank (2-7) ho,rt , and the temperature setting value T of the high temperature thermal oil tank (2-7) ho,st Comparison is performed at comparator Δ2 to obtain the thermal oil temperature adjustment value ΔT2; The power adjustment value ΔP1 and the heat transfer oil temperature adjustment value ΔT2 obtained by the PID1 controller are input into the processing unit F1(x) to obtain a new heat transfer oil temperature adjustment value ΔT3; ΔT3=k1ΔT2; Where: k1 is the proportionality coefficient, q s1 To adjust the molten salt flow, Cp s1 is the specific heat capacity of the molten salt, q o1 is the heat transfer oil flow rate, Cp o1 is the specific heat capacity of the heat transfer oil; Input the new thermal oil temperature adjustment value ΔT3 to obtain the first thermal oil pump power adjustment value ΔP2 in PID2 control: Where: K p2 is the proportional gain, K i2 is the integral gain, K d2 is the differential gain; Applying the obtained first heat transfer oil pump power adjustment amount ΔP2 to the first heat transfer oil pump (2-3) to generate a control signal for the first heat transfer oil pump (2-3); Finally, the temperature regulation control logic of the molten salt-thermal oil heat exchanger (1-5) is formed; 2) Thermal oil-water heat exchanger (2-2) temperature control logic By using the real-time value of the outlet temperature of the thermal oil-water heat exchanger water path T hw,rt The temperature setting value T of the water outlet of the thermal oil-water heat exchanger hw,st Comparison is performed at the comparator Δ3 to obtain the temperature adjustment value ΔT4 of the water outlet of the thermal oil-water heat exchanger; The input thermal oil-water heat exchanger water outlet temperature adjustment amount is ΔT4 and the third power adjustment amount ΔP3 is obtained in PID3 control: Where: K p3 is the proportional gain, K i3 is the integral gain, K d3 is the differential gain; Applying the obtained third power adjustment amount ΔP3 to the circulating water pump (2-4) to generate a control signal for the circulating water pump (2-4); According to the operation status of the system, the real-time temperature value T of the low-temperature thermal oil tank (2-1) is obtained lo,rt , and the temperature setting value T of the low temperature thermal oil tank (2-1) lo,st Comparison is performed at comparator Δ4 to obtain the low-temperature heat transfer oil temperature adjustment value ΔT5; The third power adjustment value ΔP3 and the low-temperature heat transfer oil temperature adjustment value ΔT5 obtained by the PID3 controller are input into the processing unit F2 (x) to obtain a new low-temperature heat transfer oil temperature adjustment value ΔT6; ΔT6=k2ΔT5; Where: k2 is the proportionality coefficient, q w1 To adjust the circulating water flow, Cp w1 is the specific heat of water, q o2 is the heat transfer oil flow rate, Cp o2 is the specific heat capacity of the heat transfer oil; Input the new low-temperature thermal oil temperature adjustment value at ΔT6 and obtain the second thermal oil pump power adjustment value ΔP4 in PID4 control: Where: K p4 is the proportional gain, K i4 is the integral gain, K d4 is the differential gain; The obtained second heat transfer oil pump power adjustment amount ΔP4 is superimposed on the second heat transfer oil pump (2-8) corresponding to the low-temperature heat transfer oil temperature adjustment scheme to generate a control signal for the second heat transfer oil pump (2-8); Finally, the temperature regulation control logic of the thermal oil-water heat exchanger is formed; 3) Steam generator temperature control logic According to the operation status of the system, the real-time value T of the steam generator steam outlet temperature is obtained st,rt , and the steam outlet temperature setting value T st,st Comparison is performed at comparator Δ5 to obtain the steam outlet temperature adjustment value ΔT7; Input the steam outlet temperature adjustment value at ΔT7 and obtain the feedwater pump power adjustment value ΔP5 in PID5 control: Where: K p5 is the proportional gain, K i5 is the integral gain, K d5 is the differential gain; Applying the obtained feedwater pump power adjustment amount ΔP5 to the feedwater pump (1-12) to generate a control signal for the feedwater pump (1-12); According to the operation status of the system, the real-time temperature value T of the medium-temperature molten salt storage tank (1-4) is obtained ms,rt The temperature setting value T of the medium temperature molten salt storage tank (1-4) ms,st Comparison is performed at comparator Δ6 to obtain the temperature adjustment value ΔT8 of the medium-temperature molten salt storage tank; The feedwater pump power adjustment value ΔP5 and the medium-temperature molten salt temperature adjustment value ΔT8 obtained by the PID5 controller are input into the processing unit F3 (x) to obtain a new medium-temperature molten salt tank temperature adjustment value ΔT9; ΔT9 = k3ΔT8; Where: k3 is the proportional coefficient, q st For the regulated steam flow, Cp st is the specific heat capacity of steam, q s2 is the molten salt flow rate, Cp o2 is the specific heat capacity of molten salt; Input the new medium-temperature molten salt tank temperature adjustment value at ΔT9 and obtain the first molten salt pump power adjustment value ΔP6 in PID6 control: Where: K p6 is the proportional gain, K i6 is the integral gain, K d6 is the differential gain; The obtained power adjustment amount ΔP6 of the first molten salt pump is applied to the first molten salt pump (1-9) to generate the latest power P of the first molten salt pump (1-9). new6 ; Finally, the steam generator temperature regulation control logic is formed.

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