Internal combustion engine coupling molten salt heat storage system and power generation system

Abstract

The utility model relates to the technical field of molten salt heat storage technologies, in particular to an internal combustion engine coupling molten salt heat storage system and a power generation system. Comprising a heat supply part used for providing a heat source, a heat absorption part which is connected with the heat supply part and exchanges the heat source of the heat supply part, and a heat storage part which is connected with the heat absorption part and conveys heat-exchanged molten salt to the heat absorption part. The system has the beneficial effects that the flue gas waste heat of the internal combustion engine is recovered and is supplied to the thermal load after passing through the molten salt heat storage system, so that the overall operation efficiency of the system can be effectively improved; besides, the molten salt heat storage system has good heat storage capacity, so that the system can store excess heat energy in the energy demand valley period and release heat energy in the demand peak period, and therefore the stability of energy supply is achieved; and moreover, the high-efficiency conversion of the molten salt heat storage system is also beneficial to reducing the dependence on high-carbon energy sources such as traditional fire coal and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of molten salt heat storage, in particular to an internal combustion engine coupled molten salt heat storage system and a power generation system. Background Art

[0002] In recent years, my country has issued requirements for accelerating the improvement of power supply regulation capabilities, including implementing thermal power flexibility enhancement projects and promoting the development and application of new energy storage technologies. However, existing thermal power unit flexibility improvements are primarily limited by the limited depth of boiler peak regulation and insufficient unit economics and safety. Frequent and drastic adjustments shorten the lifespan of thermal power units and result in lower returns.

[0003] Internal combustion engines are a relatively mature power generation technology, characterized by fast regulation and high precision. They can start and stop in less than a minute, and can achieve a frequency modulation rate of 60%-100% of rated output per minute, significantly faster than coal-fired power plants, gas turbines, and other generator sets. Coupling internal combustion engines with coal-fired power is an effective way to increase power generation flexibility. However, a significant challenge of coupling coal-fired power with internal combustion engines is the low efficiency of only 45% in a single cycle. Combined cycle efficiency improves slightly, but not significantly, to only 50%.

[0004] Thermal storage technology can achieve efficient integration of energy resources and improve the peak-shaving capacity of energy systems. However, current thermal storage technologies for thermal power units are primarily used for civilian heating on the turbine side, with limited capacity and inability to provide peak-shaving services during non-heating periods. Molten salt thermal storage is currently primarily used in conjunction with solar thermal power generation, offering good economic benefits. There is also research on using molten salt energy storage for peak load shifting on the grid or load side, achieving flexible regulation. Compared to electrochemical energy storage, its investment cost is lower, with a unit cost of only half that of electrochemical energy storage. However, its operating efficiency is lower, with a charge-discharge conversion efficiency of approximately 92% to 95% for electrochemical energy storage, compared to approximately 37% to 40% for electrochemical energy storage.

[0005] In summary, we propose an internal combustion engine coupled molten salt heat storage system and power generation system, which not only achieves high regulation performance of the power supply but also further improves the operating efficiency of the system itself. Utility Model Content

[0006] In view of the problem that the heat storage technology of the above-mentioned existing thermal power units has limited capacity and cannot play a peak-shaving role during the non-heating period, the present utility model is proposed.

[0007] The utility model aims to provide an internal combustion engine coupled molten salt heat storage system, which aims to solve the problem that the existing thermal power unit heat storage technology has limited capacity and cannot play a peak regulation role during the non-heating period.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: an internal combustion engine coupled molten salt heat storage system, which includes a heating element for providing a heat source, a heat absorbing element connected to the heating element and exchanging the heat source of the heating element, and a heat storage element connected to the heat absorbing element and transporting the molten salt after heat exchange to the heat absorbing element; wherein, the molten salt in the heat absorbing element circulates in the heat storage element and the heat absorbing element.

[0009] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, the heating component includes a generator, an internal combustion engine and a chimney.

[0010] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, the generator is connected to the internal combustion engine, and the exhaust pipe of the internal combustion engine is connected to the chimney.

[0011] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, the heat storage component includes a first heat exchange component and a hot salt tank connected to the first heat exchange component.

[0012] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, the first heat exchange element is connected between the chimney and the internal combustion engine.

[0013] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, the heat absorption element includes a second heat exchange element and a cold salt tank connected to the second heat exchange element.

[0014] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the utility model, the cold salt tank outlet and the hot salt tank inlet are connected through the first heat exchanger, and the high-temperature flue gas discharged by the internal combustion engine is used to heat the low-temperature molten salt in the cold salt tank through the first heat exchanger.

[0015] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the present invention, a heat load is provided outside the second heat exchange element, and the heat load outlet pipe is connected to the inside of the second heat exchange element.

[0016] As a preferred solution of the internal combustion engine coupled molten salt heat storage system of the utility model, wherein: the hot salt tank outlet is connected to the cold salt tank feed port through the second heat exchanger, and the heat of the high-temperature molten salt inside the hot salt tank is exchanged to the heat load through the second heat exchanger.

[0017] The utility model also provides the following technical solution: a power generation system including an internal combustion engine coupled with a molten salt heat storage system.

[0018] The beneficial effects of the internal combustion engine-coupled molten salt heat storage system of this utility model are as follows: in terms of high-efficiency energy conversion, the exhaust heat of the internal combustion engine's flue gas is recovered and supplied to the heat load through the molten salt heat storage system, effectively improving the overall operating efficiency of the system; in terms of stable energy supply, the molten salt heat storage system has excellent heat storage capacity, enabling the system to store excess heat energy during low energy demand and release heat energy during peak demand, thereby achieving a stable energy supply; in terms of reducing greenhouse gas emissions, the internal combustion engine can adopt advanced emission control technologies during the combustion process, thereby reducing greenhouse gas emissions. The high-efficiency energy conversion of the molten salt heat storage system also helps to reduce dependence on high-carbon energy sources such as traditional coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0020] Figure 1 This is a schematic diagram of the overall system of the internal combustion engine coupled molten salt heat storage system in the present invention. DETAILED DESCRIPTION

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below with reference to the accompanying drawings.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0024] Example 1, reference Figure 1, which is the first embodiment of the present utility model, provides an internal combustion engine coupled molten salt heat storage system, including a heating element 100 for providing a heat source, a heat absorbing element 300 connected to the heating element 100 and exchanging the heat source of the heating element 100, and a heat storage element 200 connected to the heat absorbing element 300 and transferring the molten salt after heat exchange to the heat absorbing element 300; wherein, the molten salt in the heat absorbing element 300 circulates in the heat storage element 200 and the heat absorbing element 300.

[0025] Preferably, low-temperature coupled molten salt is stored in the heat absorption element 300, and high-temperature coupled molten salt is stored in the heat storage element 200.

[0026] Preferably, the high-temperature flue gas generated after the heating element 100 burns the fuel is passed through the high-temperature exhaust pipe of the heating element 100, and the heat carried in the high-temperature flue gas is exchanged with the low-temperature coupled molten salt in the heat absorption element 300. The low-temperature coupled molten salt is heated and then transported to the heat storage element 200 for storage. At this time, the high-temperature coupled molten salt is stored in the heat storage element 200.

[0027] Furthermore, the high-temperature coupled molten salt in the heat storage component 200 exchanges heat with the external heat load, exchanges heat with the water in the low-temperature water supply pipeline in the heat load, and then the high-temperature coupled molten salt in the heat storage component 200 is cooled down and converted into low-temperature coupled molten salt and sent back to the heat absorption component 300, thus completing the cycle.

[0028] In summary, by coupling the molten salt with the heat exchange between the heating element 100 and the heat load, energy storage is achieved by coupling the molten salt, reducing coal consumption. In terms of high-efficiency energy conversion, the exhaust heat from the internal combustion engine's flue gas is recovered and supplied to the heat load through the molten salt heat storage system, effectively improving the overall operating efficiency of the system. In terms of stable energy supply, the molten salt heat storage system has excellent heat storage capacity, enabling the system to store excess heat energy during low energy demand and release heat energy during peak demand, thereby achieving a stable energy supply. In terms of reducing greenhouse gas emissions, the internal combustion engine can adopt advanced emission control technologies during the combustion process, thereby reducing greenhouse gas emissions. The high-efficiency energy conversion of the molten salt heat storage system also helps reduce dependence on high-carbon energy sources such as traditional coal.

[0029] Example 2, reference Figure 1 , which is the second embodiment of the present utility model, provides an internal combustion engine coupled molten salt heat storage system, including a heating component 100 including a generator 101, an internal combustion engine 102 and a chimney 103.

[0030] The generator 101 is connected to the internal combustion engine 102 , and the exhaust pipe of the internal combustion engine 102 is connected to the chimney 103 .

[0031] Preferably, the internal combustion engine 102 is directly connected to the generator 101 through a coupling. The rotation of the internal combustion engine 102 drives the rotor of the generator to rotate, converting mechanical energy into electrical energy output. The high-temperature flue gas generated by the combustion of fuel in the internal combustion engine 102 is connected to the chimney 103 through a high-temperature exhaust pipe.

[0032] The heat storage element 200 includes a first heat exchange element 201 and a hot salt tank 202 connected to the first heat exchange element 201 .

[0033] The first heat exchange element 201 is connected between the chimney 103 and the internal combustion engine 102 .

[0034] Preferably, the first heat exchange element 201 is a flue gas heat exchanger, and the high-temperature exhaust pipe of the internal combustion engine 102 is connected to the inside of the first heat exchange element 201 .

[0035] The heat absorbing element 300 includes a second heat exchange element 301 and a cold salt tank 302 connected to the second heat exchange element 301 .

[0036] Preferably, the second heat exchanger 301 is a heat exchanger, which is used to heat the high-temperature coupled molten salt inside the hot salt tank 202 into low-temperature coupled molten salt after exchanging heat with cold water discharged from the water supply pipe within the heat load in the second heat exchanger 301.

[0037] In summary, the high-temperature coupled molten salt is reheated into the low-temperature coupled molten salt through the above-mentioned heat exchange. When the high-temperature coupled molten salt increases, the low-temperature coupled molten salt decreases. Conversely, when the high-temperature coupled molten salt decreases, the low-temperature coupled molten salt increases.

[0038] Example 3, reference Figure 1 This is the third embodiment of the present invention, which provides an internal combustion engine-coupled molten salt heat storage system. This embodiment primarily describes the molten salt heat storage process. The outlet of the cold salt tank 302 is connected to the inlet of the hot salt tank 202 via a first heat exchanger 201. High-temperature flue gas from the internal combustion engine 102 is used to heat the low-temperature molten salt in the cold salt tank 302 via the first heat exchanger 201.

[0039] Preferably, a low-temperature molten salt pump 302a is provided between the discharge port of the cold salt tank 302 and the first heat exchange element 201, and the low-temperature coupled molten salt inside the cold salt tank 302 is transported to the first heat exchange element 201 through the low-temperature molten salt pump 302a, and heat-exchanged with the high-temperature flue gas discharged by the internal combustion engine 102, so as to convert the low-temperature coupled molten salt inside the cold salt tank 302 into high-temperature coupled molten salt, which is transported to the hot salt tank 202 through the discharge port of the cold salt tank 302.

[0040] Furthermore, a preheating heater is provided between the discharge port of the cold salt tank 302 and the first heat exchange element 201, and an overheating heater is provided between the first heat exchange element 201 and the bracket of the hot salt tank 202.

[0041] In summary, the low-temperature molten salt in the cold salt tank 302 of the thermal energy storage module is pressurized by the low-temperature molten salt pump 302a and first fed into the preheating heater in the thermal charging power module. After being heated, it enters the flue gas heat exchanger for heating, then enters the superheating heater for heating, and then enters the hot salt tank 202 for storage, completing the flow and heat storage of the molten salt circuit. During the heat storage phase, the molten salt in the cold salt tank 302 gradually decreases, while the molten salt in the hot salt tank 202 gradually increases.

[0042] Example 4, with reference to Figure 1 This is the fourth embodiment of the present invention, providing an internal combustion engine coupled to a molten salt heat storage system. This embodiment primarily describes the heat release process of the molten salt. The system includes a heat load 303 disposed externally of a second heat exchanger 301, with a water outlet pipe of the heat load 303 connected to the interior of the second heat exchanger 301.

[0043] The discharge port of the hot salt tank 202 is connected to the feed port of the cold salt tank 302 through the second heat exchanger 301 , and the heat of the high-temperature coupled molten salt inside the hot salt tank 202 is exchanged to the heat load 303 through the second heat exchanger 301 .

[0044] Preferably, a high-temperature molten salt pump 202a is provided between the discharge port of the hot salt tank 202 and the second heat exchange element 301, and the high-temperature coupled molten salt inside the hot salt tank 202 is transported to the second heat exchange element 301 through the high-temperature molten salt pump 202a, and heat is exchanged with the feed water in the heat load 303, and the high-temperature coupled molten salt inside the hot salt tank 202 is converted into low-temperature coupled molten salt and transported to the cold salt tank 302 through the feed port of the cold salt tank 302.

[0045] Furthermore, a preheater and an evaporator are provided between the discharge port of the hot salt tank 202 and the feed port of the cold salt tank 302 .

[0046] In summary, molten salt heat storage is high-temperature heat storage, and the heat release process can produce steam with higher parameters. Within the molten salt steam generation system, this heat is exchanged with the high-temperature molten salt from the hot salt tank 202 of the thermal energy storage module. After passing through the preheater and evaporator, steam with the set parameters is generated, which supplies energy to the heat load 303. After heat release, the cold salt flows back to the cold salt tank 302. During the heat release process, the molten salt in the cold salt tank 302 gradually increases, while the molten salt in the hot salt tank 202 gradually decreases.

[0047] Example 5, reference Figure 1This is the fifth embodiment of the present utility model. This embodiment provides an internal combustion engine-coupled molten salt heat storage system, which couples the flue gas waste heat of 14 18MW internal combustion engines with molten salt energy storage. The heat storage power module involves the heat loss rate η1 of pipelines and equipment. According to the design specifications, the pipeline efficiency should be 99%. That is, through reasonable insulation design, the heat storage efficiency of the energy storage system can be guaranteed to be 99%. Therefore, the heat loss rate η1 can be set to 1%. The heat storage and release processes involve the molten salt pump's operating power consumption, η2. Based on a molten salt heat storage density of 300 kJ / kg, a resistance of 1 MPa, and a thermoelectric efficiency of 40%, the estimated pump power consumption is 0.83%. Maintaining the main engine system's safety involves the reheat steam booster pump's operating power consumption. Based on reheat steam compression work of 130 kJ / kg, a reheat steam heat density of 470 kJ / kg, a reheat steam heat ratio of 20% of the total heat, and a thermoelectric efficiency of 40%, the estimated reheat steam booster pump power consumption is 13.83%. Therefore, the operating power consumption, η2, equals 14.66%. The heat storage capacity module involves the heat loss rate, η3, of piping and equipment, while the heat release power module involves the heat loss rate, η4, of piping and equipment. Following the principle of selecting η1 above, the heat loss rate, η3 = η4 = 2%. The overall efficiency, η, of the energy storage system can be calculated as follows:

[0048] η=(1-η1)×(1-η2)×(1-η3)×(1-η4)

[0049] Therefore, the estimated theoretical comprehensive thermal efficiency of the internal combustion engine coupled with the molten salt heat storage system is 82.8%. According to the thermal efficiency of the molten salt system, the flue gas recovery rate is 60%. Under rated power operation, compared with the cogeneration heating of coal-fired power units, it can save 49.68 tons of coal consumption per hour and reduce 140.76 tons of carbon dioxide emissions per hour.

[0050] Example 6 is the sixth example of the present utility model. This example provides a power generation system, including an internal combustion engine coupled with a molten salt heat storage system. By adopting an internal combustion engine coupled with a molten salt heat storage system in the power generation system, the energy utilization efficiency can be significantly improved. By recovering the waste heat of the high-temperature flue gas emitted by the internal combustion engine and converting it into steam, it is mixed with the steam extracted from the medium-pressure cylinder of the coal-fired unit and supplied to users, thereby reducing the inefficient use of high-quality steam, saving coal consumption, and reducing carbon dioxide emissions. This not only improves the heating energy efficiency of the system, but also brings significant economic and environmental benefits.

[0051] It is important to note that the construction and arrangement of the present application shown in a number of different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, colors, directional changes, etc.) without departing substantially from the novel teachings and advantages of the subject matter described in this application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete elements may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also an equivalent structure. Without departing from the scope of the present invention, other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the present invention is not limited to the specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0052] Additionally, in order to provide a concise description of example embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0053] It will be appreciated that in the development of any actual embodiment, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will, for those of ordinary skill having the benefit of this disclosure, be a routine undertaking of design, fabrication, and production without undue experimentation.

[0054] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the claims of the present invention.

Claims

1. An internal combustion engine coupled molten salt heat storage system, characterized by: include, A heating element (100) for providing a heat source, a heat absorbing element (300) connected to the heating element (100) and exchanging the heat source of the heating element (100), and a heat storage element (200) connected to the heat absorbing element (300) and transporting the molten salt after heat exchange to the heat absorbing element (300); The molten salt in the heat absorbing element (300) circulates in the heat storage element (200) and the heat absorbing element (300).

2. The internal combustion engine coupled molten salt heat storage system according to claim 1, characterized in that: The heating element (100) includes a generator (101), an internal combustion engine (102), and a chimney (103).

3. The internal combustion engine coupled molten salt thermal storage system according to claim 2, characterized in that: The generator (101) is connected to the internal combustion engine (102), and the exhaust pipe of the internal combustion engine (102) is connected to the chimney (103).

4. The internal combustion engine coupled molten salt heat storage system according to claim 3, characterized in that: The heat storage element (200) comprises a first heat exchange element (201) and a hot salt tank (202) connected to the first heat exchange element (201).

5. The internal combustion engine coupled molten salt heat storage system according to claim 4, characterized in that: The first heat exchange element (201) is connected between the chimney (103) and the internal combustion engine (102).

6. The internal combustion engine coupled molten salt heat storage system according to claim 5, characterized in that: The heat absorbing element (300) comprises a second heat exchange element (301) and a cold salt tank (302) connected to the second heat exchange element (301).

7. The internal combustion engine coupled molten salt heat storage system according to claim 6, characterized in that: The discharge port of the cold salt tank (302) and the feed port of the hot salt tank (202) are connected via the first heat exchanger (201), and the high-temperature flue gas discharged from the internal combustion engine (102) is used to heat the low-temperature molten salt in the cold salt tank (302) via the first heat exchanger (201).

8. The internal combustion engine coupled molten salt heat storage system according to claim 7, characterized in that: A heat load (303) is provided outside the second heat exchange component (301), and a water outlet pipe of the heat load (303) is connected to the inside of the second heat exchange component (301).

9. The internal combustion engine coupled molten salt heat storage system according to claim 8, characterized in that: The hot salt tank (202) outlet is connected to the cold salt tank (302) feed port via the second heat exchanger (301), and the heat of the high-temperature molten salt inside the hot salt tank (202) is exchanged to the heat load (303) via the second heat exchanger (301).

10. A power generation system, characterized in that: It comprises the internal combustion engine coupled molten salt heat storage system according to any one of claims 1 to 9.

Images