Medium-high temperature solar stepped heat supply system and application method thereof

Abstract

The invention relates to a medium-high temperature solar cascade type heat supply system which comprises a solar heat collector, a phase change heat storage tank, a steam generator, a standby boiler, a buried pipe group and a buffer water tank. An oil guide pipe network in which heat conduction oil flows is arranged outside the solar heat collector, one end of the oil guide pipe network is connected with the input end of a phase change heat storage tank, the output end of the phase change heat storage tank is connected with the input end of a steam generator, the steam generator is communicated with a steam turbine and a buffer water tank, and the steam turbine is communicated with the buffer water tank. The standby boiler is communicated with the steam generator and the steam turbine; the steam turbine is connected with a generator; the generator is connected to a resident through a wire. The buffer water tank and the buried pipe group are communicated with a first circulation loop, and a second circulation loop is communicated between the buffer water tank and the resident. The solar heat collector generates heat and transmits heat conduction oil, a phase change material exchanging heat with the heat conduction oil is arranged in the phase change heat storage tank, and the heat conduction oil exchanges heat with the phase change heat storage tank in the flowing process.

Description

Technical Field

[0001] The present disclosure relates to the field of solar energy and energy storage technology, and in particular to a medium- and high-temperature solar cascade heating system and an application method thereof. Background Art

[0002] As one of the main forms of renewable energy, solar energy resources have many advantages such as being extensive and inexhaustible. At the same time, they also have defects such as low heat flux density, intermittency and instability. Even in the same place, the amount of solar radiation available will change periodically or randomly with the change of seasons, day and night, and time.

[0003] After being concentrated, solar energy becomes a high-quality thermal energy that can meet the needs of various households and can also realize solar thermal power generation, solar refrigeration, and air conditioning. The medium- and high-temperature heat energy of 100-400℃ generated by the most typical trough-type concentrating solar collector has a wide range of application methods. Combining multiple heat storage methods is most conducive to the cascade utilization of heat energy.

[0004] Phase change heat storage is widely used due to its advantages of high heat storage density, high efficiency, easy process control, and stable temperature during heat storage / release process. It is suitable for short-term storage of high-grade thermal energy. Underground heat storage system has low cost and small footprint, and is suitable for large-scale long-term storage of solar energy, which can effectively solve the cross-seasonal mismatch of solar heating system. Combining the characteristics of the two heat storage systems, the cascade utilization of medium and high temperature solar energy is one of the most effective ways to rationally utilize solar energy. Summary of the invention

[0005] In view of the above technical problems in the related art, the present disclosure proposes a medium-high temperature solar cascade heating system, which can overcome the above deficiencies in the prior art.

[0006] To achieve the above technical objectives, the technical solution of the present disclosure is implemented as follows: The first object of the present disclosure is to provide a medium-high temperature solar cascade heating system, which includes a solar collector, a phase change heat storage tank, a steam generator, a backup boiler, an underground pipe group, and a buffer water tank; An oil pipe network with heat transfer oil flowing therein is arranged outside the solar collector, one end of the oil pipe network is connected to the input end of the phase change heat storage tank, the output end of the phase change heat storage tank is connected to the input end of the steam generator, the steam generator is connected to the steam turbine and the buffer water tank respectively, the steam turbine is connected to the buffer water tank, and the standby boiler is connected to the steam generator and the steam turbine; The steam turbine is also connected to a generator, thereby driving the generator to generate electricity; the generator is connected to the residents through a wire, thereby supplying electricity to the residents; the buffer water tank is connected to the buried pipe group through a circulation loop 1, and the buffer water tank is connected to the residents through a circulation loop 2; The above-mentioned connection mode is realized through pipelines. The solar collector absorbs sunlight to generate heat and transfers it to the heat transfer oil in the oil pipe network. The phase change heat storage tank is provided with a phase change material for heat exchange with the heat transfer oil. The heat transfer oil exchanges heat with the phase change heat storage tank during the flow process. A heat pump is provided on the circulation loop 2 between the buffer water tank and the residents, and the heat pump is also connected in parallel to the conductor between the generator and the residents, so that the heat pump obtains power supply from the generator. Preferably, the solar thermal collector is a trough solar thermal collector.

[0007] Preferably, the steam turbine is a small steam turbine.

[0008] Preferably, the generator is a small generator.

[0009] Preferably, a water pump or a valve is provided on the circulation loop between the buffer water tank and the buried pipe group.

[0010] Preferably, the buffer water tank is provided with waste heat output terminal 1 and waste heat output terminal 2, the waste heat output terminal 1 is connected to the input terminal of the standby boiler, and the waste heat output terminal 2 of the buffer water tank is connected to the input terminal of the oil tank; the output terminal of the oil tank is connected to the oil pipe network.

[0011] Preferably, a plurality of water pumps or valves are provided in the solar collector, the phase change heat storage tank, the steam generator, the standby boiler, the steam turbine, the oil tank, the underground pipe group, the buffer water tank, and the pipelines used by the residents.

[0012] The second object of the present disclosure is to provide an application method of the medium- and high-temperature solar cascade heating system, characterized in that: During the summer days when there is plenty of solar energy, medium and high temperature solar energy of 100-400℃ is collected by trough solar collectors, and the heat is transferred to the phase change heat storage tank through heat transfer oil, and heat is exchanged with the phase change material, thereby performing short-term heat storage; The remaining heat is used to generate high-temperature steam through a steam generator. The high-temperature steam enters a steam turbine to drive a generator to generate electricity, thereby providing electricity to residents during the day and powering devices such as heat pumps to achieve cooling. The unused waste heat in the steam generator enters the buffer water tank, which heats the water in the buffer water tank. On the one hand, the water in the buffer water tank heats the underground soil through the buried pipe group for long-term heat storage, and on the other hand, it provides 24-hour hot water supply for residents.

[0013] Preferably, during the summer nights when solar energy is insufficient, the valve can be adjusted so that the heat transfer oil does not pass through the solar collector, but directly enters the phase change heat storage tank, and the heat stored during the day is taken out through heat exchange, and the steam generator is used to generate high-temperature steam, which enters the steam turbine to drive the generator to generate electricity, provide electricity for residents at night, and power devices such as heat pumps, thereby achieving cooling.

[0014] Preferably, in winter when solar energy is insufficient, the heat energy provided by the trough solar collector is insufficient to produce sufficient high-temperature steam. At this time, some high-temperature steam is generated by the standby boiler to supplement the steam volume, thereby meeting the demand of the steam turbine, and then the steam turbine drives the generator to generate electricity to power residents and heat pumps.

[0015] Preferably, when solar energy is insufficient in winter, heat is continuously extracted from the underground soil through the buried pipe group to provide hot water for residents and heat for heat pumps, thereby providing heating for residents in winter.

[0016] Beneficial effects of the present disclosure: Compared with the prior art, the present disclosure has the following advantages: (A) The present disclosure provides a method for cascade utilization of medium and high temperature solar energy, which adds a short-term heat storage system using phase change materials and a seasonal heat storage system using buried pipe groups to traditional solar thermal power generation. This can provide residents with a stable power supply throughout the year, and provide cooling in summer and heating in winter.

[0017] (B) The present invention uses phase change heat storage materials for short-term heat storage, which effectively solves the problem of uneven supply of solar energy during a day. At the same time, the phase change heat storage tank is small in size and high in thermal density, saving the system's floor space.

[0018] (C) The present disclosure combines a seasonal underground heat storage system to store waste heat in the system in the soil in summer and extract it for use in winter, providing heating for residents through a heat pump system, effectively saving heat consumption and improving energy utilization.

[0019] (D) The method of cascade utilization of solar energy provided by the present disclosure achieves combined cooling, heating and power generation without substantially any pollutant emissions, which not only improves energy utilization efficiency but also effectively protects the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0021] Figure 1 It is a schematic structural diagram of the medium- and high-temperature solar cascade heating system described in the present invention.

[0022] Figure 2 This is a logical architecture diagram of the medium- and high-temperature solar cascade heating system described in the present disclosure.

[0023] In the figure: 1. Trough solar collector; 2. Phase change heat storage tank; 3. Steam generator; 4. Backup boiler; 5. Small steam turbine; 6. Small generator; 7. Oil tank; 8. Underground pipe group; 9. Buffer water tank; 10. Water pump; 11. Heat pump; 12. Valve; 13. Oil pipe network; 14. Residents. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure.

[0025] like Figure 1-2 As shown, in order to facilitate the understanding of the above technical solutions of the present disclosure, the above technical solutions of the present disclosure are described in detail below through specific usage methods.

[0026] The first object of the present disclosure is to provide a medium-high temperature solar cascade heating system, which includes a solar collector 1, a phase change heat storage tank 2, a steam generator 3, a backup boiler 4, an underground pipe group 8, and a buffer water tank 9; An oil pipe network 13 with heat transfer oil flowing therein is provided outside the solar thermal collector 1, one end of the oil pipe network 13 is connected to the input end of the phase change heat storage tank 2, the output end of the phase change heat storage tank 2 is connected to the input end of the steam generator 3, the steam generator 3 is connected to the steam turbine 5 and the buffer water tank 9 respectively, the steam turbine 5 is connected to the buffer water tank 9, and the standby boiler 4 is connected to the steam generator 3 and the steam turbine 5; The steam turbine 5 is further connected to a generator 6, thereby driving the generator 6 to generate electricity; the generator 6 is connected to the household 14 through a wire, thereby supplying electricity to the household 14; the buffer water tank 9 is connected to the buried pipe group 8 by a circulation loop 1, and the buffer water tank 9 is connected to the household 14 by a circulation loop 2; The above-mentioned connection mode is realized through pipelines. The solar collector 1 absorbs sunlight to generate heat and transfers it to the heat transfer oil in the oil pipe network 13. The phase change heat storage tank 2 is provided with a phase change material for heat exchange with the heat transfer oil. The heat transfer oil exchanges heat with the phase change heat storage tank 2 during the flow process. A heat pump 11 is provided on the circulation loop 2 between the buffer water tank 9 and the resident 14 . The heat pump 11 is also connected in parallel to the conductor between the generator 6 and the resident 14 . The heat pump 11 is thus powered by the generator 6 . In one embodiment, the solar thermal collector 1 is a trough solar thermal collector.

[0027] In one embodiment, the steam turbine 5 is a small steam turbine.

[0028] In one embodiment, the generator 6 is a small generator.

[0029] In one embodiment, a plurality of water pumps 10 or valves 12 are provided on the circulation loop between the buffer water tank 9 and the buried pipe group 8 .

[0030] In a certain embodiment, the buffer water tank 9 is provided with a waste heat output terminal 1 901 and a waste heat output terminal 2 902, the waste heat output terminal 1 901 is connected to the input end of the standby boiler 4, and the waste heat output terminal 2 902 of the buffer water tank 9 is connected to the input end of the oil tank 7; the output end of the oil tank 7 is connected to the oil pipe network 13.

[0031] In one embodiment, a water pump 10 or a valve 12 is provided in the pipelines used by the solar collector 1, the phase change heat storage tank 2, the steam generator 3, the standby boiler 4, the steam turbine 5, the oil tank 7, the buried pipe group 8, the buffer water tank 9, and the residents 14.

[0032] The second object of the present disclosure is to provide an application method of the medium- and high-temperature solar cascade heating system, characterized in that: During the summer days when there is sufficient solar energy, the trough solar collector 1 collects medium- and high-temperature solar energy of 100-400°C, and transmits the heat to the phase change heat storage tank 2 through the heat transfer oil, and exchanges heat with the phase change material, thereby performing short-term heat storage; The remaining heat is converted into high-temperature steam by the steam generator 3, and the high-temperature steam enters the steam turbine 5 to drive the generator 6 to generate electricity, thereby providing daytime electricity supply to the residents 14 and powering the heat pump 11 and other devices, thereby achieving cooling; The unused waste heat in the steam generator 3 enters the buffer water tank 9 to heat the water in the buffer water tank 9. On the one hand, the water in the buffer water tank 9 heats the underground soil through the buried pipe group 8 for long-term heat storage, and on the other hand, provides 24-hour hot water supply for the residents 14.

[0033] In one embodiment, during the summer night when solar energy is insufficient, the valve 12 is adjusted so that the heat transfer oil does not pass through the solar collector 1, but directly enters the phase change heat storage tank 2, and the heat stored during the day is taken out through heat exchange, and the steam generator 3 is used to generate high-temperature steam, which enters the steam turbine 5 to drive the generator 6 to generate electricity, provide electricity supply for the residents 14 at night, and power the heat pump 11 and other devices, thereby achieving cooling.

[0034] In one embodiment, in winter when solar energy is insufficient, the heat energy provided by the trough solar collector 1 is insufficient to generate sufficient high-temperature steam. At this time, part of the high-temperature steam is generated by the standby boiler 4 to supplement the steam volume, thereby meeting the demand of the steam turbine 5. The steam turbine 5 then drives the generator 6 to generate electricity to supply power to the residents 14 and the heat pump 11.

[0035] In one embodiment, when solar energy is insufficient in winter, heat is continuously extracted from the underground soil through the buried pipe group 8 to provide hot water for the residents 14 and heat for the heat pump 11, thereby providing heat for the residents 14 in winter.

[0036] Working principle: Figure 1-2 As shown, the application scenarios of the medium- and high-temperature solar cascade heating system can be roughly divided into: solar thermal collection system, short-term heat storage system, long-term heat storage system, thermal power generation system, and user system; among them, the short-term heat storage and long-term heat storage in the lower left corner together constitute the heat storage system. The above division is actually based on industry common sense. In order to better connect the divisions made in this disclosure, dotted line division is used, which is not a limitation or summary of the technical solution of this disclosure.

[0037] The solar heat collection system comprises a solar heat collector 1 and an oil pipe network 13. The solar heat collector receives solar energy, generates heat, and conducts the heat to a short-term heat storage system.

[0038] The short-term heat storage system includes a phase-change heat storage tank 2. The medium- and high-temperature solar energy collected by the solar thermal collection system will first enter the phase-change heat storage tank 2 for heat exchange to complete the short-term heat storage process. When the solar energy supply is insufficient at night, the short-term heat storage system provides medium- and high-temperature thermal energy for thermal power generation. The short-term heat storage system mainly realizes the stable supply of electrical energy and thermal energy throughout the day.

[0039] The long-term heat storage system includes a buried pipe group 8. In the summer when solar energy is abundant, the buried pipe group 8 collects waste heat from the thermal power generation system and stores low-grade heat in the underground soil. In the winter when solar energy is insufficient, low-grade heat is taken out from the underground soil for hot water supply and heat pump heating, effectively reducing the consumption of fossil fuels.

[0040] The thermal power generation system includes a steam generator 3, a standby boiler 4, a steam turbine 5, a generator 6, an oil tank 7, etc. In the summer when solar energy is sufficient, the medium and high temperature solar energy collected by the solar thermal collection system directly enters the steam generator 3, generates high temperature steam and enters the steam turbine 5, and the steam turbine 5 drives the generator 6 to generate electricity; at night, as described in step B, the short-term heat storage system provides medium and high temperature thermal energy for power generation; in the winter when solar energy is insufficient, as described in step C, the standby boiler supplements the shortage of medium and high temperature thermal energy supply. The generator 6 directly supplies electricity to the user. The unused heat energy in the steam generator 3 and the waste heat generated by the steam turbine 5 enter the buffer water tank.

[0041] The user system includes a buffer water tank 9, a heat pump 11, and residents 14. The electricity generated by the thermal power generation system is directly supplied to the residents 14, and also supplies power to the heat pump 11 and other equipment, so that the heat pump 11 and other equipment can provide cooling in summer and heating in winter. The unused low-grade heat energy in the thermal power generation system enters the buffer water tank 9. In summer, by adjusting the water volume and the opening of each auxiliary valve 12, hot water is supplied to the residents 14, and the unused low-grade heat energy is sent to the long-term heat storage system. When the heat supply is insufficient in winter, on the one hand, the waste heat of the thermal power generation system is used, and on the other hand, heat is taken out from the long-term heat storage system to ensure the supply of residents 14.

[0042] Specific usage: (i) During the summer days when there is sufficient solar energy, the trough type solar collector 1 collects medium and high temperature solar energy of 100-400°C, and transfers the heat to the phase change heat storage tank 2 through the heat transfer oil, and exchanges heat with the phase change material, thereby performing short-term heat storage.

[0043] The remaining heat is converted into high-temperature steam by the steam generator 3, and the high-temperature steam enters the steam turbine 5 to drive the generator 6 to generate electricity, thereby providing daytime electricity supply to the residents 14 and powering the heat pump 11 and other devices to achieve cooling.

[0044] The unused waste heat in the steam generator 3 enters the buffer water tank 9 to heat the water in the buffer water tank 9. On the one hand, the water in the buffer water tank 9 heats the underground soil through the buried pipe group 8 for long-term heat storage, and on the other hand, provides 24-hour hot water supply for the residents 14.

[0045] (ii) In the summer nights when solar energy is insufficient, the valve 12 is adjusted so that the heat transfer oil does not pass through the solar collector 1, but directly enters the phase change heat storage tank 2, and the heat stored during the day is taken out through heat exchange, and the steam generator 3 is used to generate high-temperature steam, which enters the steam turbine 5 to drive the generator 6 to generate electricity, providing nighttime electricity supply for the residents 14 and powering the heat pump 11 and other devices, thereby achieving cooling.

[0046] (III) In winter when solar energy is insufficient, the heat energy provided by the trough solar collector 1 is insufficient to generate sufficient high-temperature steam. At this time, the standby boiler 4 generates some high-temperature steam to supplement the steam volume, thereby meeting the demand of the steam turbine 5. The steam turbine 5 then drives the generator 6 to generate electricity to supply power to the residents 14 and the heat pump 11.

[0047] (iv) When solar energy is insufficient in winter, heat is continuously extracted from the underground soil through the buried pipe group 8 to provide hot water for the residents 14 and heat for the heat pump 11, thereby providing heat for the residents 14 in winter.

[0048] In summary, through the unique design of the present disclosure, compared with the prior art, the present disclosure has the following advantages: (A) The present disclosure provides a method for cascade utilization of medium and high temperature solar energy, which adds a short-term heat storage system for heat storage through phase change materials and a seasonal heat storage system for heat storage through buried pipe groups on the basis of traditional solar thermal power generation. Thus, it can provide residents with a stable power supply throughout the year, and provide cooling in summer and heating in winter; (B) The present disclosure uses phase change heat storage materials for short-term heat storage, which effectively solves the problem of uneven supply of solar energy in a day cycle. At the same time, the phase change heat storage tank has a small volume and high thermal density, which saves the system's floor space; (C) The present disclosure combines a seasonal underground heat storage system to store the waste heat in the system in the soil in summer, and extracts it for use in winter, and provides heating for residents through a heat pump system, effectively saving heat consumption and improving energy utilization; (D) The method for cascade utilization of solar energy provided by the present disclosure has basically no pollutant emissions on the basis of achieving combined cooling, heating and power, which not only improves energy utilization efficiency but also effectively protects the environment.

[0049] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A medium-high temperature solar cascade heating system, characterized in that: It comprises a solar thermal collector (1), a phase change heat storage tank (2), a steam generator (3), a standby boiler (4), an underground pipe group (8), and a buffer water tank (9); An oil pipe network (13) through which heat transfer oil flows is provided outside the solar thermal collector (1); one end of the oil pipe network (13) is connected to the input end of the phase change heat storage tank (2); the output end of the phase change heat storage tank (2) is connected to the input end of the steam generator (3); the steam generator (3) is connected to the steam turbine (5) and the buffer water tank (9) respectively; the steam turbine (5) is connected to the buffer water tank (9); and the standby boiler (4) is connected to the steam generator (3) and the steam turbine (5); The steam turbine (5) is further connected to a generator (6), thereby driving the generator (6) to generate electricity; the generator (6) is connected to a household (14) via a wire, thereby providing electricity to the household (14); The buffer water tank (9) is connected to the buried pipe group (8) via a circulation loop 1, and the buffer water tank (9) is connected to the household (14) via a circulation loop 2; The above-mentioned connection method is realized through pipelines, the solar collector (1) absorbs sunlight to generate heat and transfers it to the heat transfer oil in the oil pipe network (13), the phase change heat storage tank (2) is provided with a phase change material for heat exchange with the heat transfer oil, and the heat transfer oil exchanges heat with the phase change heat storage tank (2) during the flow process; A heat pump (11) is provided on the second circulation loop between the buffer water tank (9) and the household (14), and the heat pump (11) is also connected in parallel to the conductor between the generator (6) and the household (14), so that the heat pump (11) obtains power from the generator (6).

2. The heating system according to claim 1, characterized in that: The solar thermal collector (1) is a trough type solar thermal collector.

3. The heating system according to claim 1, characterized in that: The steam turbine (5) is a small steam turbine, and the generator (6) is a small generator.

4. The heating system according to claim 1, characterized in that: A water pump (10) or a valve (12) is provided on the circulation loop between the buffer water tank (9) and the buried pipe group (8).

5. The heating system according to claim 1, characterized in that: The buffer water tank (9) is provided with a waste heat output terminal 1 (901) and a waste heat output terminal 2 (902); the waste heat output terminal 1 (901) is connected to the input terminal of the standby boiler (4); the waste heat output terminal 2 (902) of the buffer water tank (9) is connected to the input terminal of the oil tank 7; and the output terminal of the oil tank 7 is connected to the oil pipe network (13).

6. The heating system according to claim 5, characterized in that: A plurality of water pumps (10) or valves (12) are provided in the pipelines used by the solar collector (1), the phase change heat storage tank (2), the steam generator (3), the standby boiler (4), the steam turbine (5), the oil tank 7, the underground pipe group (8), the buffer water tank (9), and the residents (14).

7. The application method of the medium-high temperature solar cascade heating system according to any one of claims 1 to 6, characterized in that: During the summer days when there is sufficient solar energy, medium- and high-temperature solar energy of 100-400° C. is collected by the trough-type solar collector (1), and the heat is transferred to the phase-change heat storage tank (2) through the heat transfer oil to exchange heat with the phase-change material, thereby performing short-term heat storage; The remaining heat is used to generate high-temperature steam through the steam generator (3), and the high-temperature steam enters the steam turbine (5) to drive the generator (6) to generate electricity, thereby providing daytime electricity supply to the residents (14) and powering the heat pump (11) and other devices, thereby achieving cooling; The unused waste heat in the steam generator (3) enters the buffer water tank (9), thereby heating the water in the buffer water tank (9). The water in the buffer water tank (9) heats the underground soil through the buried pipe group (8) for long-term heat storage, and provides 24-hour hot water supply to the residents (14) on the other hand.

8. The application method according to claim 6, characterized in that: During the summer night when solar energy is insufficient, the valve (12) is adjusted so that the heat transfer oil does not pass through the solar collector (1) but directly enters the phase change heat storage tank (2), and the heat stored during the day is taken out through heat exchange. The steam generator (3) generates high-temperature steam, which enters the steam turbine (5) to drive the generator (6) to generate electricity, thereby providing nighttime electricity supply to the residents (14) and powering the heat pump (11) and other devices, thereby achieving cooling.

9. The application method according to claim 6, characterized in that: In winter when solar energy is insufficient, the heat energy provided by the trough solar collector (1) is insufficient to generate sufficient high-temperature steam. At this time, the standby boiler (4) generates some high-temperature steam to supplement the steam volume, thereby meeting the demand of the steam turbine (5). The steam turbine (5) then drives the generator (6) to generate electricity to supply power to the resident (14) and the heat pump (11).

10. The application method according to claim 6, characterized in that: When solar energy is insufficient in winter, heat is continuously extracted from the underground soil through the buried pipe group (8) to provide hot water for the residents (14) and heat for the heat pump (11), thereby providing heat for the residents (14) in winter.

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