Fused salt energy storage system and heat storage and heat release method for thermoelectric unit

Abstract

The invention relates to the technical field of fused salt energy storage, in particular to a fused salt energy storage system for a thermoelectric unit and a heat storage and release method. The system comprises a boiler, a heat storage system, a steam heating fused salt system, a fused salt steam generation system, a fused salt feed water heating system, a turboset and a water supply system. The boiler communicates with the turboset and the steam molten salt heating system, the water supply system communicates with the boiler and the steam molten salt heating system, and the heat storage system communicates with the steam molten salt heating system; the steam turbine unit is communicated with the steam heating molten salt system; the heat storage system is communicated with the fused salt steam generation system; the heat storage system is communicated with the fused salt feed water heating system, and the fused salt feed water heating system is communicated with the water supply system. By arranging the heat storage system and the steam heating system, the heat storage system and the steam heating system can be coupled with main steam exhausted by a boiler in the thermoelectric unit, reheated steam and exhaust of a steam turbine unit, and therefore the power generation output of the thermoelectric unit is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of molten salt energy storage, and in particular to a molten salt energy storage system for a thermal power unit and a heat storage and heat release method. Background Art

[0002] With the continuous advancement of the "dual carbon goals", the scale of renewable energy such as photovoltaic and wind power and their proportion in the power grid continue to increase, and the impact on the power system caused by their own fluctuations, homogeneity, and uncontrollable defects has gradually become prominent, and it is necessary to configure flexible power sources to smooth the output of photovoltaic and wind power and improve the power system's ability to absorb them. Among them, coal-fired power units that have undergone flexibility transformation are increasingly valued because they have advantages over flexible power sources such as gas power and hydropower in terms of fuel costs, geographical conditions and safety.

[0003] For the combined heat and power coal-fired power units, since they undertake the task of industrial heating and residential heating, they usually operate in the form of "heat to determine electricity", which makes it difficult to improve the regulation capacity of power generation output while ensuring heating. For this reason, some power plants have alleviated the thermal-electric coupling contradiction of the units to a certain extent through the zero-output transformation of the low-pressure cylinder, but this transformation can only work during the heating period or when the unit supplies low-pressure industrial steam, and it cannot improve the units that need to supply medium-pressure industrial steam at the same time, and it cannot take into account the realization of the maximum power generation output of the unit and the guarantee of heating during the peak period of the unit, so further transformation is needed to achieve a higher degree of thermal-electric decoupling.

[0004] The Chinese patent with publication number CN1104765485B discloses "an operating system and method for molten salt steam heat storage of a cylinder-cutting unit", which uses molten salt energy storage technology coupled with the exhaust gas of the intermediate pressure cylinder to improve the thermal and electric decoupling capacity of the unit. However, since it only uses the exhaust gas of the intermediate pressure cylinder as a heat source, the improvement in the regulation capacity of the thermal power unit is relatively small, and the effect is not significant during the non-heating period. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a molten salt energy storage system and a heat storage and release method for a thermal power unit, which solves the technical problems of only using the exhaust gas of the intermediate pressure cylinder as a heat source, which has a relatively small improvement on the regulating capacity of the unit and has no significant effect during the non-heating period.

[0007] (II) Technical solution

[0008] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0009] On the one hand, the present invention provides a molten salt energy storage system for a thermal power unit, comprising a boiler, a heat storage system, a steam-heated molten salt system, a molten salt steam generating system, a molten salt feedwater heating system, a steam turbine unit and a feedwater system; the boiler is connected to the steam turbine unit and the steam molten salt heating system, respectively, the feedwater system is connected to the boiler and the steam-heated molten salt system, respectively, the heat storage system is connected to the steam molten salt heating system; the steam turbine unit is connected to the steam-heated molten salt system; the heat storage system is connected to the molten salt steam generating system; the heat storage system is connected to the molten salt feedwater heating system, and the molten salt feedwater heating system is connected to the feedwater system.

[0010] Preferably, the heat storage system includes a high-temperature molten salt storage tank, a low-temperature molten salt storage tank and a thermocline water storage tank; the steam-heated molten salt system includes a first superheated molten salt heater, a second superheated molten salt heater, a phase-change molten salt heater, a first preheating molten salt heater and a second preheating molten salt heater; the inlet end of the high-temperature molten salt storage tank is respectively connected to the first outlet end of the first superheated molten salt heater and the first outlet end of the second superheated molten salt heater, the first inlet end of the first superheated molten salt heater and the first inlet end of the second superheated molten salt heater are both connected to the first outlet end of the phase-change molten salt heater, the second outlet end of the first superheated molten salt heater is connected to the first inlet end of the phase-change molten salt heater, and the second inlet end of the phase-change molten salt heater is respectively connected to the first inlet end of the first preheating molten salt heater. An outlet end is connected with the first outlet end of the second preheating molten salt heater, the second outlet end of the phase change molten salt heater is connected with the first inlet end of the second preheating molten salt heater, and the second inlet end of the second preheating molten salt heater and the second outlet end of the second preheating molten salt heater are respectively connected with the outlet end of the low-temperature molten salt storage tank and the first inlet end of the water supply system, the first inlet end of the first preheating molten salt heater is connected with the pipeline connecting the second superheated molten salt heater and the low-temperature molten salt storage tank through a first bypass; the second outlet end of the first preheating molten salt heater is connected with the first inlet end of the steam-water heat exchanger, the outlet end of the thermocline water storage tank is connected with the second inlet end of the steam-water heat exchanger, and the outlet end of the steam-water heat exchanger is connected with the second inlet end of the water supply system.

[0011] Preferably, the feed water system includes a shaft seal heater, a condenser and a water drying tower; the steam turbine unit includes an intermediate pressure cylinder; the inlet end of the intermediate pressure cylinder is connected to the first outlet end of the boiler, and the outlet end of the intermediate pressure cylinder is connected to the second inlet end of the first preheating molten salt heater; the second inlet end of the feed water system is connected to the first inlet end of the shaft seal heater, and the first outlet end of the shaft seal heater is connected to the inlet end of the condenser, the water drying tower can exchange heat with the nearly saturated steam condensed in the condenser to form saturated water, and connect the outlet end of the condenser with the second inlet end of the shaft seal heater through a condensate pump, the second outlet end of the shaft seal heater is connected to the third inlet end of the feed water system, and the outlet end of the feed water system is connected to the first inlet end of the boiler.

[0012] Preferably, the molten salt energy storage system also includes a pressure matcher; the steam turbine unit includes a high-pressure cylinder; the inlet end of the high-pressure cylinder and the outlet end of the high-pressure cylinder are respectively connected to the second outlet end of the boiler and the second inlet end of the boiler; a second bypass is provided on the pipeline connecting the first outlet end of the boiler and the inlet end of the medium-pressure cylinder, the second bypass is connected to the second inlet end of the second superheated molten salt heater, the second outlet end of the second superheated molten salt heater is connected to the first inlet end of the pressure matcher, and the outlet end of the pressure matcher is connected to the pipeline connecting the outlet end of the high-pressure cylinder and the second inlet end of the boiler; a third bypass is provided on the pipeline connecting the second outlet end of the boiler and the inlet end of the high-pressure cylinder, the third bypass is connected to the second inlet end of the first superheated molten salt heater, a fourth bypass is provided on the third bypass, and the outlet end of the fourth bypass is connected to the second inlet end of the pressure matcher.

[0013] Preferably, the water supply system includes a first high-pressure heater and a second high-pressure heater; the outlet end of the second preheating molten salt heater is connected to the inlet end of the second high-pressure heater, the outlet end of the second high-pressure heater is connected to the inlet end of the first high-pressure heater, and the outlet end of the first high-pressure heater is connected to the first inlet end of the boiler.

[0014] Preferably, the molten salt energy storage system also includes an external steam supply pipeline; the molten salt steam generation system includes a feedwater preheating heat exchanger, an evaporator and a superheated steam heat exchanger; the outlet end of the inclined temperature layer water storage tank is connected to the first inlet end of the feedwater preheating heat exchanger, the first outlet end of the feedwater preheating heat exchanger and the second inlet end of the feedwater preheating heat exchanger are respectively connected to the first inlet end of the evaporator and the first outlet end of the evaporator, the second outlet end of the evaporator and the second inlet end of the evaporator are respectively connected to the first inlet end of the superheated steam heat exchanger and the first outlet end of the superheated steam heat exchanger, the outlet end of the high-temperature molten salt storage tank is connected to the second inlet end of the superheated steam heat exchanger, and the second outlet end of the superheated steam heat exchanger is connected to the inlet end of the external steam supply pipeline.

[0015] Preferably, the molten salt feed water heating system includes a molten salt-water heat exchanger; the first outlet end and the first inlet end of the molten salt-water heat exchanger are respectively connected to the inlet end of the low-temperature molten salt storage tank and the second outlet end of the feed water preheating heat exchanger, and the second inlet end and the second outlet end of the molten salt-water heat exchanger are both connected to the water supply system.

[0016] Preferably, it also includes a molten salt electric heating system and a hydroelectric heating system; the molten salt electric heating system and the hydroelectric heating system are both connected to the heat storage system to store the heated molten salt and water in the heat storage system.

[0017] On the other hand, the present invention provides a heat storage method for a molten salt energy storage system of a thermal power unit, including the stage of reducing the power generation output of the thermal power unit:

[0018] S11: The boiler discharges main steam, a part of which enters the steam turbine unit to perform work, and another part of which enters the steam heating molten salt system and exchanges heat with the heat storage system step by step to form high-pressure supercooled water. The high-pressure supercooled water is transported to the water supply system for heating, and after heating is completed, it is transported back to the boiler for further heating;

[0019] S12: the boiler discharges the reheated steam heated in step S1, the reheated steam enters the steam heating molten salt system, and exchanges heat with the heat storage system to form low-pressure superheated steam, and a portion of the main steam in step S1 that enters the steam turbine unit to perform work is discharged by the steam turbine unit and then transported back to the boiler together with the low-pressure superheated steam for further heating;

[0020] S13: The steam exhausted by the steam turbine unit enters the steam heating molten salt system, exchanges heat with the heat storage system to form low-pressure supercooled water, and is heated in the water supply system and transported back to the boiler for further heating.

[0021] On the other hand, the present invention provides a heat release method for a molten salt energy storage system of a thermal power unit, including a stage of increasing the power generation output of the thermal power unit:

[0022] S21: the heat storage system discharges hot water, the hot water enters the molten salt steam generation system, exchanges heat with the heat storage system, and then is discharged;

[0023] S22: The heat storage system discharges part of the low-pressure feed water, which enters the molten salt feed water heating system, releases heat to form low-temperature molten salt, and is then transported back to the heat storage system for storage; another part of the low-pressure feed water exchanges heat with the molten salt feed water heat exchanger to form low-pressure medium-temperature feed water, which enters the feed water system, is heated in the feed water system, and is transported back to the boiler.

[0024] (III) Beneficial effects

[0025] The beneficial effects of the present invention are:

[0026] 1. A molten salt energy storage system and a heat storage and heat release method for a thermal power unit of the present invention can be coupled with the main steam, reheated steam and exhaust gas of the steam turbine unit discharged from the boiler of the thermal power unit by setting a heat storage system and a steam heating system, and the sensible heat or latent heat in the steam is used to heat molten salt or water, thereby reducing the power generation output of the thermal power unit. At the same time, the heat storage system slowly releases heat to supplement the heat supply of the thermal power unit reduced by steam extraction. In addition, it can release steam of different flavors, replace the original steam extraction of the thermal power unit for heating services, and heat the primary feed water, increase the peak output capacity of the thermal power unit, thereby further increasing the flexibility and adjustment capacity of the thermal power unit, and can play a significant role throughout the year. In addition, the present invention can store the sensible heat or latent heat in the multi-stage steam extraction of the thermal power unit in the heat storage stage, reduce the amount of steam per unit time and its thermal energy entering the thermal power unit to do work, thereby reducing the power generation output capacity of the thermal power unit during the deep peak regulation period, while ensuring that the thermal power unit completes the heating demand during this period.

[0027] 2. The molten salt energy storage system and heat storage and heat release method for a thermal power unit of the present invention can realize that when the main steam enters the first preheating molten salt heater, the phase change molten salt heater and the second superheated molten salt heater in sequence, the main steam can be coupled with the low-temperature molten salt in the low-temperature molten salt storage tank in a step-by-step heat exchange manner in the second preheating molten salt heater, the phase change molten salt heater and the second superheated molten salt heater, so that the main steam forms high-pressure supercooled water and the low-temperature molten salt forms high-temperature molten salt, thereby increasing the flexibility and adjustment capability of the thermal power unit.

[0028] 3. A molten salt energy storage system and a heat storage and heat release method for a thermal power unit of the present invention, through the exhaust steam of the medium-pressure cylinder, flows through the preheating molten salt heater, the steam-water heat exchanger, the shaft seal heater, and the condenser in sequence, exchanges heat with the water in the air-drying tower in the condenser, exchanges heat with the nearly saturated steam condensed in the condenser to form saturated water, and finally transports it back to the boiler, so as to realize a cycle of the exhaust steam of the medium-pressure cylinder. By setting a pressure matcher, when the reheated steam discharged from the boiler enters the superheated molten salt heat exchanger through the second bypass, the reheated steam exchanges heat with the molten salt to form low-pressure superheated steam, which is transported back to the boiler after the pressure is adjusted by the pressure matcher, and the high-pressure cylinder exhaust steam also enters the boiler with the superheated steam, so as to avoid the boiler from dry burning, which leads to danger. By setting a fourth bypass on the third bypass, when the reheated steam enters the pressure matcher, the pressure matcher can also extract part of the reheated steam that has not entered the superheated molten salt heater for heat exchange through the fourth bypass, so as to balance the pressure in the pressure matcher.

[0029] 4. The molten salt energy storage system and heat storage and heat release method for a thermal power unit of the present invention can, by setting a first high-pressure heater and a second high-pressure heater, enable the main steam to undergo step-by-step heat exchange with the heat storage system and the steam molten salt heating system respectively, and finally to undergo step-by-step heat exchange with the molten salt from the low-temperature molten salt storage tank to form high-pressure supercooled water, which is then transported to the first high-pressure heater and the second high-pressure heater to form high-pressure hot water, and then transported back to the boiler for further heating to form steam.

[0030] 5. The molten salt energy storage system and heat storage and release method for thermal power units of the present invention are provided with a feed water preheating heat exchanger, an evaporator and a superheated steam heat exchanger. The normal-pressure hot water in the upper layer of the inclined temperature layer water storage tank is pumped out by the feed water pump and enters the molten salt feed water preheater, the steam generator and the superheated steam heat exchanger in sequence, and exchanges heat with the high-temperature molten salt in the high-temperature molten salt storage tank step by step. Superheated steam of different pressures is formed according to the heating demand, which replaces the industrial steam extraction of the steam turbine unit or enters the external steam supply pipeline for industrial steam supply, so as to supply industrial users, residential users and heating water.

[0031] 6. The molten salt energy storage system and heat storage and heat release method for thermal power units of the present invention can realize that the low-temperature molten salt storage tank directly provides heat to the molten salt-water heat exchanger by setting a molten salt-water heat exchanger, and utilizes the heat in the low-temperature molten salt storage tank to replace the steam extraction of the steam turbine unit, thereby reducing or even eliminating the need for steam extraction of the steam turbine unit, thereby improving the power generation capacity.

[0032] 7. The molten salt energy storage system and heat storage and heat release method for thermal power units of the present invention, by setting up a molten salt electric heating system and a hydroelectric heating system, can convert the adjusted power output of the unit into molten salt and water sensible heat energy for storage in the heat storage system during deep peak regulation, further reducing the power output of the thermal power unit, and even achieving zero power output of the thermal power unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A schematic diagram of the heat storage process of a molten salt energy storage system and a heat storage and heat release method for a thermal power unit of the present invention;

[0034] Figure 2 The present invention is a schematic diagram of the heat release process of a molten salt energy storage system and a heat storage and heat release method for a thermal power unit.

[0035] [Description of Reference Numerals]

[0036] A: Thermal storage system;

[0037] B: Steam heating molten salt system;

[0038] C: Molten salt steam generation system;

[0039] D: Molten salt water heating system;

[0040] E: Steam turbine unit;

[0041] F: Water supply system;

[0042] 1: boiler; 2: high temperature molten salt storage tank; 3: low temperature molten salt storage tank; 4: thermocline water storage tank; 5: first superheated molten salt heater; 6: second superheated molten salt heater; 7: phase change molten salt heater; 8: first preheated molten salt heater; 9: second preheated molten salt heater; 10: inlet end of high temperature molten salt storage tank; 11: first outlet end of first superheated molten salt heater; 12: first outlet end of second superheated molten salt heater; 13: first inlet end of first superheated molten salt heater; 14: first inlet end of second molten salt heater; 15: first outlet end of phase change molten salt heater; 16: second outlet end of first superheated molten salt heater; 17: first inlet end of phase change molten salt heater; 18: second inlet end of phase change molten salt heater End; 19: first outlet end of the first preheating molten salt heater; 20: first outlet end of the second preheating molten salt heater; 21: second outlet end of the phase change molten salt heater; 22: first inlet end of the second preheating molten salt heater; 23: second inlet end of the second preheating molten salt heater; 24: second outlet end of the second preheating molten salt heater; 25: outlet end of the low-temperature molten salt storage tank; 26: first inlet end of the water supply system; 27: first inlet end of the first preheating molten salt heater; 28: first bypass; 29: second outlet end of the first preheating molten salt heater; 30: steam-water heat exchanger; 31: first inlet end of the steam-water heat exchanger; 32: outlet end of the inclined temperature layer water storage tank; 33: second inlet end of the steam-water heat exchanger; 34: steam-water heat exchanger outlet of the boiler; 35: the second inlet of the feed water system; 36: the shaft seal heater; 37: the condenser; 38: the air-drying tower; 39: the intermediate pressure cylinder; 40: the inlet of the intermediate pressure cylinder; 41: the first outlet of the boiler; 42: the outlet of the intermediate pressure cylinder; 43: the second inlet of the first preheating molten salt heater; 44: the first inlet of the shaft seal heater; 45: the first outlet of the shaft seal heater; 46: the inlet of the condenser; 47: the condensate pump; 48: the outlet of the condenser; 49: the second inlet of the shaft seal heater; 50: the second outlet of the shaft seal heater; 51: the third inlet of the feed water system; 52: the outlet of the feed water system; 53: the first inlet of the boiler; 54: the pressure matcher; 55: the high pressure cylinder; 56: the pressure matcher; 57: the pressure matcher; 58: the pressure matcher; 59: the pressure matcher; 60: the pressure matcher; 61: the pressure matcher; 62: the pressure matcher; 63: the pressure matcher; 64: the pressure matcher; 65: the pressure matcher; 66: the pressure matcher; 67: the pressure matcher; 68: the pressure matcher; 69: the pressure matcher; 69: the pressure matcher; 70: the pressure matcher; 71: the pressure matcher; 72: the pressure matcher; 73: the pressure matcher; 74: the pressure matcher; 75: the pressure matcher; 76: the pressure matcher; 77: the pressure matcher; 78: the pressure matcher; 79: the pressure matcher; 80: the pressure matcher; 81: the pressure matcher; 82: the pressure matcher; 6: inlet end of high-pressure cylinder; 57: outlet end of high-pressure cylinder; 58: second outlet end of boiler; 59: second inlet end of boiler; 60: second bypass; 61: second inlet end of second superheated molten salt heater; 62: second outlet end of second superheated molten salt heater; 63: first inlet end of pressure matcher; 64: outlet end of pressure matcher; 65: third bypass; 66: second inlet end of first superheated molten salt heater; 67: fourth bypass; 68: outlet end of fourth bypass; 69: second inlet end of pressure matcher; 70: first high-pressure heater; 71: second high-pressure heater; 72: inlet end of second high-pressure heater; 73: outlet end of second high-pressure heater; 74: inlet end of first high-pressure heater;75: outlet end of the first high-pressure heater; 76: feedwater preheating heat exchanger; 77: evaporator; 78: superheated steam heat exchanger; 79: first inlet end of the feedwater preheating heat exchanger; 80: first outlet end of the feedwater preheating heat exchanger; 81: second inlet end of the feedwater preheating heat exchanger; 82: first inlet end of the evaporator; 83: first outlet end of the evaporator; 84: second outlet end of the evaporator; 85: second inlet end of the evaporator; 86: first inlet end of the superheated steam heat exchanger; 87: first outlet end of the superheated steam heat exchanger; 88: Second outlet of superheated steam heat exchanger; 89: External steam supply pipeline; 90: Inlet of external steam supply pipeline; 91: Molten salt-water heat exchanger; 92: First outlet of molten salt-water heat exchanger; 93: First inlet of molten salt-water heat exchanger; 94: Second outlet of feed water preheating heat exchanger; 95: Second inlet of molten salt-water heat exchanger; 96: Second outlet of molten salt-water heat exchanger; 97: Second inlet of superheated steam heat exchanger; 98: Outlet of high-temperature molten salt storage tank; 99: Inlet of low-temperature molten salt storage tank. ; DETAILED DESCRIPTION

[0043] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a clearer and more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0044] Embodiment 1

[0045] like Figure 1-Figure 2 As shown, a molten salt energy storage system for a thermal power unit in this embodiment includes a boiler 1, a heat storage system A, a steam heating molten salt system B, a molten salt steam generating system C, a molten salt feed water heating system D, a steam turbine unit E and a feed water system F.

[0046] Specifically, the boiler 1 is connected to the steam turbine unit E and the steam molten salt heating system, respectively, the water supply system F is connected to the boiler and the steam heating molten salt system B, respectively, and the heat storage system A is connected to the steam molten salt heating system, so that part of the main steam discharged from the boiler 1 enters the steam turbine unit E to do work, and the other part of the main steam enters the steam heating molten salt system B to exchange heat with the heat storage system A step by step to form high-pressure supercooled water, which ranges from 8 to 10 MPa, and is transported back to the boiler 1 through the water supply system F for further heating. The steam turbine unit E is connected to the steam heating molten salt system B, so that the reheated steam discharged from the boiler 1 enters the steam heating molten salt system B to exchange heat with the heat storage system A to form low-pressure superheated steam, which ranges from about 2 MPa, and enters the boiler 1 together with the steam discharged when the steam turbine unit E does work. At the same time, the steam discharged from the steam turbine unit E enters the steam heating molten salt system B, exchanges heat with the heat storage system A to form low-pressure supercooled water, the pressure range of which is about 0.5MPa, and is heated in the water supply system F and transported back to the boiler 1. The heat storage system A is connected to the molten salt steam generation system C, so that the hot water discharged from the heat storage system A enters the molten salt steam generation system C, and the hot water is exchanged with the heat storage system A to form superheated steam for industrial exhaust steam or residential heating. The heat storage system A is connected to the molten salt feed water heating system D, and the molten salt feed water heating system D is connected to the feed water system F, so that part of the low-pressure feed water discharged from the heat storage system A enters the molten salt feed water heating system D to release heat and form low-temperature molten salt, and then is transported back to the heat storage system A, and the other part of the low-pressure feed water is exchanged with the molten salt feed water heating system D to form low-pressure medium-temperature feed water, which enters the feed water system F, and is further heated in the feed water system F and then transported back to the boiler 1. Among them, the pressure of low-pressure feed water is about 0.5MPa. By setting up a heat storage system A and a steam heating system, it can be coupled with the main steam, reheated steam discharged from the boiler 1 in the thermal power unit and the exhaust of the turbine unit E, and the sensible heat or latent heat in the steam is used to heat molten salt or water, thereby reducing the power generation output of the thermal power unit. At the same time, the heat storage system A slowly releases heat to supplement the heat supply of the thermal power unit reduced due to steam extraction. In addition, it can release steam of different tastes, that is, steam of different temperatures, pressures, etc., to replace the original thermal power unit steam extraction for heating services, and heat the primary feed water, increase the peak output capacity of the thermal power unit, thereby further increasing the flexibility and adjustment capacity of the thermal power unit, and can play a significant role throughout the year. In addition, in the heat storage stage, this embodiment can store the sensible heat or latent heat in the multi-stage steam extraction of the thermal power unit, reduce the amount of steam per unit time and its thermal energy entering the thermal power unit to do work, and then reduce the power generation output capacity of the thermal power unit during the deep peak regulation period, while ensuring that the thermal power unit completes the heating demand during this period.

[0047] Further, the heat storage system A includes a high-temperature molten salt storage tank 2, a low-temperature molten salt storage tank 3 and a thermocline water storage tank 4. It should be noted that the upper layer of the thermocline water storage tank 4 is hot water at normal pressure, and the lower layer is cold water at normal pressure. The steam-heated molten salt system B includes a first superheated molten salt heater 5, a second superheated molten salt heater 6, a phase change molten salt heater 7, a first preheating molten salt heater 8 and a second preheating molten salt heater 9. The inlet end 10 of the high-temperature molten salt storage tank is respectively connected to the first outlet end 11 of the first superheated molten salt heater and the first outlet end 12 of the second superheated molten salt heater, the first inlet end 13 of the first superheated molten salt heater and the first inlet end 14 of the second superheated molten salt heater are both connected to the first outlet end 15 of the phase change molten salt heater, the second outlet end 16 of the first superheated molten salt heater is connected to the first inlet end 17 of the phase change molten salt heater, the second inlet end 18 of the phase change molten salt heater is respectively connected to the first outlet end 19 of the first preheating molten salt heater and the first outlet end 20 of the second preheating molten salt heater, and the second outlet end 21 of the phase change molten salt heater is connected to the second preheating molten salt heater. The first inlet end 22 of the heater is connected, and the second inlet end 23 of the second preheating molten salt heater and the second outlet end 24 of the second preheating molten salt heater are respectively connected to the outlet end 25 of the low-temperature molten salt storage tank and the first inlet end 26 of the water supply system, and the first inlet end 27 of the first preheating molten salt heater is connected to the pipeline connected to the second superheated molten salt heater 6 and the low-temperature molten salt storage tank 3 through the first bypass 28, so that when the main steam enters the first superheated molten salt heater 5, the phase change molten salt heater 7 and the second preheating molten salt heater 9 in sequence, it is coupled with the low-temperature molten salt in the low-temperature molten salt storage tank 3 in a step-by-step heat exchange to form high-pressure supercooled water, and the low-temperature molten salt forms high-temperature molten salt. It should be explained here that when the main steam enters the second preheating molten salt heater 9, it changes from steam to water, and then forms high-temperature and high-pressure steam through the step-by-step heating of the water supply system F, and enters the boiler 1 for continued heating, thereby increasing the flexibility and adjustment capability of the thermal power unit. At the same time, the low-temperature molten salt in the low-temperature molten salt storage tank 3 is pumped out from the outlet end 25 of the low-temperature molten salt storage tank, and enters the second preheating molten salt heater 9 from the second inlet end 23 of the second preheating molten salt heater, and enters the first preheating molten salt heater 8 from the first inlet end 27 of the first preheating molten salt heater through the first bypass 28 to heat the low-temperature molten salt. The heated molten salt is output from the first outlet end 19 of the first preheating molten salt heater and the first outlet end 20 of the second preheating molten salt heater, respectively, and merges, and enters the phase change molten salt heater 7 from the second inlet end 18 of the phase change molten salt heater to exchange heat with the main steam, and continue to heat.The molten salt after heat exchange is output from the first outlet port 15 of the phase change molten salt heater, and is input into the first superheated molten salt heater 5 and the second superheated molten salt heater 6 from the first inlet port 13 of the first superheated molten salt heater and the first inlet port 14 of the second molten salt heater, respectively, to exchange heat with the main steam again and heat it. Finally, the molten salt after heat exchange is output from the first outlet port 11 of the first superheated molten salt heater and the first outlet port 12 of the second superheated molten salt heater, respectively, and enters the high-temperature molten salt storage tank 2 from the inlet port 10 of the high-temperature molten salt storage tank for storage, thereby realizing step-by-step heating for heat storage.

[0048] Further, the water supply system includes a shaft seal heater 36, a condenser 37 and a water drying tower 38. The steam turbine unit E includes an intermediate pressure cylinder 39. The second outlet end 29 of the first preheating molten salt heater is connected to the first inlet end 31 of the steam-water heat exchanger, the outlet end 32 of the thermocline water storage tank is connected to the second inlet end 33 of the steam-water heat exchanger, and the outlet end 34 of the steam-water heat exchanger is connected to the second inlet end 35 of the water supply system. The inlet end 40 of the intermediate pressure cylinder is connected to the first outlet end 41 of the boiler, and the outlet end 42 of the intermediate pressure cylinder is connected to the second inlet end 43 of the first preheating molten salt heater, so that the exhaust steam of the intermediate pressure cylinder 39 enters the first preheating molten salt heater 8 to exchange heat with the molten salt, and then enters the steam-water heat exchanger 30 to exchange heat with the normal pressure cold water in the thermocline water storage tank 4 to form low-pressure supercooled water. The second inlet end 35 of the water supply system is connected to the first inlet end 44 of the shaft seal heater, so that the low-pressure supercooled water enters the shaft seal heater 36 for cooling. The first outlet end 45 of the shaft seal heater is connected to the inlet end 46 of the condenser, so that the low-pressure supercooled water after cooling enters the condenser to form saturated water. The water drying tower 38 exchanges heat with the saturated water condensed in the condenser 37, and the outlet end 48 of the condenser is connected to the second inlet end 49 of the shaft seal heater through the condensate pump 47. The second outlet end 50 of the shaft seal heater is connected to the third inlet end 51 of the feed water system, so that the saturated water after heat exchange enters the feed water system F and is gradually heated in the feed water system F to form steam. The outlet end 52 of the feed water system is connected to the first inlet end 53 of the boiler, so that the heated steam enters the boiler 1 for heating again. The exhaust steam from the intermediate pressure cylinder 39 flows sequentially through the first preheating molten salt heater 8, the steam-water heat exchanger 30, the shaft seal heater 36, the condenser 37 and the water drying tower 38, and is finally transported back to the boiler 1 through the water supply system F, thereby realizing one cycle of the exhaust steam from the intermediate pressure cylinder 39. At the same time, by utilizing the latent heat in the exhaust steam from the intermediate pressure cylinder 39, the heat storage capacity of the inclined temperature layer water storage tank 4 is improved and the regulation ability is stronger.

[0049] Furthermore, the molten salt energy storage system also includes a pressure matcher 54. The steam turbine unit E includes a high-pressure cylinder 55. The inlet end 56 of the high-pressure cylinder and the outlet end 57 of the high-pressure cylinder are respectively connected to the second outlet end 58 of the boiler and the second inlet end 59 of the boiler. A second bypass 60 is provided on the pipeline connecting the first outlet end 41 of the boiler and the inlet end 40 of the medium-pressure cylinder. The second bypass 60 is connected to the second inlet end 61 of the second superheated molten salt heater, so that the reheated steam discharged from the boiler 1 enters the second superheated molten salt heater 6 and then exchanges heat with the molten salt in the second preheating molten salt heater 8 to form low-pressure superheated steam. The second outlet end 62 of the second superheated molten salt heater is connected to the first inlet end 63 of the pressure matcher, so that the low-pressure superheated steam is pressure-regulated in the pressure matcher 54, so that the pressure of the low-pressure superheated steam is reduced and is in a stable state. The outlet end 64 of the pressure matcher is connected to the pipeline connecting the outlet end 57 of the high-pressure cylinder and the second inlet end 59 of the boiler, so that the superheated steam after pressure adjustment and the steam discharged from the high-pressure cylinder 55 enter the boiler 1 together, avoiding dry burning of the boiler 1. By setting the pressure matcher 54, when the reheated steam discharged from the boiler 1 enters the second superheated molten salt heat exchanger 9 through the second bypass 60, the reheated steam exchanges heat with the molten salt to form low-pressure superheated steam, which is transported back to the boiler 1 after the pressure is adjusted by the pressure matcher 54, and the exhaust steam of the high-pressure cylinder 55 also enters the boiler 1 along with the superheated steam, avoiding the danger of dry burning of the boiler 1. A third bypass 65 is provided on the pipeline connecting the second outlet end 58 of the boiler and the inlet end 56 of the high-pressure cylinder. The third bypass 65 is connected to the second inlet end 66 of the first superheated molten salt heater. A fourth bypass 67 is provided on the third bypass 65. The outlet end 68 of the fourth bypass is connected to the second inlet end 69 of the pressure matcher. When the reheated steam discharged from the boiler 1 enters the pressure matcher 54, the pressure matcher 54 can also extract part of the reheated steam that has not entered the second superheated molten salt heater 6 for heat exchange through the fourth bypass 67, thereby balancing the pressure in the pressure matcher 54.

[0050] Further, the water supply system includes a first high-pressure heater 70 and a second high-pressure heater 71. The outlet end 24 of the second preheating molten salt heater is connected to the inlet end 72 of the second high-pressure heater, the outlet end 73 of the second high-pressure heater is connected to the inlet end 74 of the first high-pressure heater, and the outlet end 75 of the first high-pressure heater is connected to the first inlet end 53 of the boiler. So that the main steam, after step-by-step heat exchange with the heat storage system A and the steam heating molten salt system B respectively, finally exchanges heat with the molten salt from the low-temperature molten salt storage tank 3 step by step in the second preheating molten salt heater to form high-pressure supercooled water, and then is transported to the first high-pressure heater 70 and the second high-pressure heater 71 to form high-pressure hot water, and then transported back to the boiler 1 for further heating to form steam.

[0051] Furthermore, the molten salt energy storage system also includes an external steam supply pipeline 89. The molten salt steam generation system C includes a feedwater preheating heat exchanger 76, an evaporator 77 and a superheated steam heat exchanger 78. The outlet end 32 of the inclined temperature layer water storage tank is connected to the first inlet end 79 of the feedwater preheating heat exchanger, the first outlet end 80 of the feedwater preheating heat exchanger and the second inlet end 81 of the feedwater preheating heat exchanger are respectively connected to the first inlet end 82 of the evaporator and the first outlet end 83 of the evaporator, the second outlet end 84 of the evaporator and the second inlet end 85 of the evaporator are respectively connected to the first inlet end 86 of the superheated steam heat exchanger and the first outlet end 87 of the superheated steam heat exchanger, and the outlet end 98 of the high-temperature molten salt storage tank is connected to the second inlet end 97 of the superheated steam heat exchanger. , the second outlet end 88 of the superheated steam heat exchanger is connected to the inlet end 90 of the external steam supply pipeline, so that the normal-pressure hot water in the upper layer of the inclined temperature layer water storage tank 4 is pumped out by the feed water pump, and enters the feed water preheating heat exchanger 76, the evaporator 77 and the superheated steam heat exchanger 78 for heating in sequence, and then exchanges heat with the high-temperature molten salt in the high-temperature molten salt storage tank 2 step by step, and forms superheated steam of different pressures and temperatures according to the heating demand, replacing the industrial steam extraction of the steam turbine unit or entering the external steam supply pipeline 89 for industrial steam supply, so as to supply industrial users, residential users and heat the feed water. Among them, the normal-pressure hot water enters the feed water preheating heat exchanger 76 and is heated to about the saturation temperature, that is, 200℃-300℃, and then enters the evaporator 77 and the superheated steam heat exchanger 78 in sequence for heating, and is heated to the superheat temperature. According to the heating demand, superheated steam of different pressures is formed, which is supplied to industrial users, residential users and heat the feed water.

[0052] Further, the molten salt feedwater heating system D includes a molten salt-water heat exchanger 91. The first outlet end 92 and the first inlet end 93 of the molten salt-water heat exchanger are respectively connected to the inlet end 99 of the low-temperature molten salt storage tank and the second outlet end 94 of the feedwater preheating heat exchanger, and the second inlet end 95 and the second outlet end 96 of the molten salt-water heat exchanger are both connected to the feedwater system F. The high-temperature molten salt in the high-temperature molten salt storage tank 2 is pumped out from the outlet 98 of the high-temperature molten salt storage tank, and enters the superheated steam heat exchanger 78, the evaporator 77, and the feed water preheating heat exchanger 76 in sequence to release heat, and then outputs through the second outlet 94 of the feed water preheating heat exchanger, and enters the molten salt-water heat exchanger 91 from the first inlet 93 of the molten salt-water heat exchanger. At the same time, the water in the feed water system F enters the molten salt-water heat exchanger 91 from the second inlet 95 of the molten salt-water heat exchanger, and exchanges heat with the high-temperature molten salt after heat release. The heat-exchanged water is output from the second outlet 96 of the molten salt-water heat exchanger into the feed water system F, and is transported back to the boiler 1 after step-by-step heating of the feed water system F. The heat-exchanged molten salt is output from the first outlet 92 of the molten salt-water heat exchanger, and enters the low-temperature molten salt storage tank 3 from the inlet 99 of the low-temperature molten salt storage tank for storage. The difference is that the low-temperature molten salt storage tank 3 can also directly pump out the molten salt, allowing it to enter the molten salt-water heat exchanger 91 to release heat, and exchange heat with the water entering the molten salt-water heat exchanger 91 from the water supply system F. The heat of the molten salt in the low-temperature molten salt storage tank 3 is used to replace the steam extraction of the steam turbine unit, thereby reducing or even eliminating the need for steam extraction of the steam turbine unit E, thereby improving the power generation capacity.

[0053] Furthermore, the molten salt energy storage system also includes a molten salt electric heating system and a hydroelectric heating system. Both the molten salt electric heating system and the hydroelectric heating system are connected to the heat storage system A. The molten salt electric heating system and the hydroelectric heating system can directly heat the molten salt in the low-temperature molten salt storage tank 3 into high-temperature molten salt, and transport the heated high-temperature molten salt to the high-temperature molten salt storage tank 2 for storage, so as to store the heated molten salt and water in the high-temperature molten salt storage tank 2 and the thermocline water storage tank 4 respectively, that is, during the deep peak regulation period, the adjusted power generation output of the unit can be converted into molten salt and water sensible heat energy for storage in the heat storage system A, further reducing the power generation output of the thermal power unit, and even achieving zero power generation output of the thermal power unit.

[0054] Through the above structure, this embodiment can further reduce the amount of steam entering the unit to do work, and further improve the flexibility and adjustment ability of the unit. For a thermal power unit that has only completed the zero-output transformation of the low-pressure cylinder, it can only increase the adjustment ability during the heating period. After applying this embodiment, since the heat released by the heat storage system A can generate steam of different tastes and heat the primary feed water of the thermal power unit, the heating unit can use this system throughout the year.

[0055] Embodiment 2

[0056] like Figure 1 As shown, a heat storage method for a molten salt energy storage system of a thermal power unit in this embodiment includes a thermal power unit reducing power generation output stage,

[0057] S11: The boiler 1 discharges main steam, a part of which is output from the second outlet port 58 of the boiler, enters the high-pressure cylinder 55 from the inlet port 56 of the high-pressure cylinder to perform work, and is output from the outlet port 57 of the high-pressure cylinder, and enters the boiler 1 from the second inlet port 59 of the boiler; another part of the main steam is output from the second outlet port 58 of the boiler, enters the first superheated molten salt heater 5 from the second inlet port 66 of the first superheated molten salt heater via the third bypass 65, and is output from the second outlet port 16 of the first superheated molten salt heater, and enters the phase change molten salt heater 7 from the first inlet port 17 of the phase change molten salt heater for heat exchange. The heated main steam is output from the second outlet port 21 of the phase change molten salt heater, enters the second preheating molten salt heater 9 from the first inlet port 22 of the second preheating molten salt heater for heat exchange to form low-pressure supercooled water, the main steam after heat exchange is output from the second outlet port 24 of the second preheating molten salt heater, enters the water supply system F from the first inlet port 26 of the water supply system, and enters the second high-pressure heater 71 and the first high-pressure heater 70 from the inlet port 72 of the second high-pressure heater and the inlet port 74 of the first high-pressure heater in turn for heating, and finally is transported back to the boiler 1 from the outlet port 75 of the first high-pressure heater for further heating;

[0058] S12: The boiler discharges the reheated steam heated in step S1, and the reheated steam is output from the first outlet port 41 of the boiler. A part of the reheated steam enters the medium-pressure cylinder from the inlet port 40 of the medium-pressure cylinder to perform work; another part of the reheated steam enters the second superheated molten salt heater 6 from the second inlet port 61 of the second superheated molten salt heater through the second bypass 60, and the reheated steam is heated to form low-pressure superheated steam. The low-pressure superheated steam is discharged from the second outlet port 62 of the second superheated molten salt heater, and enters the pressure matcher 54 from the first inlet port 63 of the pressure matcher, and is adjusted in the pressure matcher 54. A part of the main steam that enters the high-pressure cylinder 55 to perform work in step S1 is discharged from the outlet port 57 of the high-pressure cylinder, and is transported back to the boiler 1 from the second inlet port 59 of the boiler together with the low-pressure superheated steam discharged from the outlet port 64 of the pressure matcher and adjusted by the pressure matcher 54 to continue heating, so as to prevent the boiler 1 from burning dry;

[0059] S13: Synchronously with step S12, when the main steam in step S11 is output from the second outlet port 58 of the boiler, a part of the main steam enters the third bypass 65, and is extracted through the pressure matcher 54, and the main steam enters the pressure matcher 54 through the fourth bypass 67, and is adjusted in the pressure matcher 54 together with the reheated steam to form low-pressure superheated steam, and is output from the outlet port 64 of the pressure matcher;

[0060] S14: The steam exhausted by the medium-pressure cylinder after work is discharged from the outlet end 42 of the medium-pressure cylinder, enters the first preheating molten salt heater 8 from the second inlet end 43 of the first preheating molten salt heater for heating, and is output from the second outlet end 29 of the first preheating molten salt heater, and enters the steam-water heat exchanger 30 from the first inlet end 31 of the steam-water heat exchanger. At the same time, the atmospheric pressure cold water in the inclined temperature layer water storage tank 4 is output from the second inlet end 33 of the steam-water heat exchanger to enter the steam-water heat exchanger 30. The exhaust steam of the medium-pressure cylinder 39 exchanges heat with the atmospheric pressure cold water in the steam-water heat exchanger 30 to form low-pressure supercooled water, which is output from the outlet end 34 of the steam-water heat exchanger, and enters the shaft seal heater from the second outlet end 50 of the shaft seal heater through the second inlet end 35 of the water supply system. The low-pressure supercooled water is cooled in the steam generator 36 and then output from the first outlet port 45 of the shaft seal heater and enter the condenser 37 from the inlet port 46 of the condenser. The water in the drying tower 38 exchanges heat with the low-pressure supercooled water in the condenser 37. The water after heat exchange is output from the outlet port 48 of the condenser and enters the shaft seal heater 36 from the second inlet port 49 of the shaft seal heater through the action of the condensate pump 47, and is output from the second outlet port 50 of the shaft seal heater, enters the feed water system F from the third inlet port 51 of the feed water system, flows through multiple low-temperature heaters, a deaerator, a second high-pressure heater 71 and a first high-pressure heater 70 in sequence, and finally enters the boiler 1 from the first inlet port 53 of the boiler for further heating.

[0061] S15: It is carried out simultaneously with steps S11, S12, S13, and S14. The low-temperature molten salt storage tank 3 pumps out the low-temperature molten salt from 25. The low-temperature molten salt enters the second preheating molten salt heater 9 from the second inlet end 23 of the second preheating molten salt heater to exchange heat with the main steam, enters the first preheating molten salt heater 8 from the first inlet end 27 of the first preheating molten salt heater through the first bypass 28 to exchange heat with the exhaust steam of the medium pressure cylinder 39, and heats the low-temperature molten salt at the same time. The heated molten salt is output from the first outlet end 19 of the first preheating molten salt heater and the first outlet end 20 of the second preheating molten salt heater and merges, enters the phase change molten salt heater 7 from the second inlet end 18 of the phase change molten salt heater to exchange heat with the exhaust steam of the medium pressure cylinder 39, and heats the low-temperature molten salt at the same time. The main steam in the molten salt heater 7 is heat exchanged and continued to be heated. The molten salt after heat exchange is output from the first outlet port 15 of the phase change molten salt heater, and is input into the first superheated molten salt heater 5 and the second superheated molten salt heater 6 from the first inlet port 13 of the first superheated molten salt heater and the first inlet port 14 of the second molten salt heater, respectively, so as to exchange heat with the main steam in the first superheated molten salt heater 5 and the reheated steam in the second superheated molten salt heater 6 and heat them. Finally, the high-temperature molten salt after heat exchange is output from the first outlet port 11 of the first superheated molten salt heater and the first outlet port 12 of the second superheated molten salt heater, respectively, and enter the high-temperature molten salt storage tank 2 from the inlet port 10 of the high-temperature molten salt storage tank for storage.

[0062] Embodiment 3

[0063] like Figure 2 As shown, a heat release method for a molten salt energy storage system of a thermal power unit in this embodiment includes a stage of increasing power generation output of the thermal power unit:

[0064] S21: The thermoclimatic layer water storage tank 4 discharges normal pressure hot water from the outlet end 32 of the thermoclimatic layer water storage tank, and the hot water enters the feed water preheating heat exchanger 76 from the first inlet end 79 of the feed water preheating heat exchanger. The preheated hot water is output from the first outlet end 80 of the feed water preheating heat exchanger, and enters the evaporator 77 from the first inlet end 82 of the evaporator to be heated and evaporated to form steam. The steam is output from the first outlet end 84 of the evaporator and enters the superheated steam heat exchanger from the first inlet end 86 of the superheated steam heat exchanger. 78 continues to be heated. At the same time, the high-temperature molten salt in the high-temperature molten salt storage tank 2 is output from the outlet end 98 of the high-temperature molten salt storage tank, and enters the superheated steam heat exchanger 78 from the third inlet end 97 of the superheated steam heat exchanger, so that the high-temperature molten salt releases heat and exchanges heat with the steam to form superheated steam of different pressures. The superheated steam is output from the first outlet end 88 of the superheated steam heat exchanger, and enters the external steam supply pipeline 89 from the inlet end 90 of the external steam supply pipeline to be used by industrial users, residential users, etc.

[0065] S22: After the high-temperature molten salt and steam in step S21 exchange heat in the superheated steam heat exchanger 78, the molten salt is output from the first outlet end 87 of the superheated steam heat exchanger, enters the evaporator 77 from the second inlet end 85 of the evaporator to release heat, and then is output from the first outlet end 83 of the evaporator, enters the feed water preheating heat exchanger 76 from the second inlet end 81 of the feed water preheating heat exchanger to continue to release heat, and then is output from the second outlet end 94 of the feed water preheating heat exchanger, and enters the molten salt-water heat exchanger 91 from the first inlet end 93 of the molten salt-water heat exchanger to release heat;

[0066] S23: Simultaneously with step S22, water in the water supply system enters the molten salt-water heat exchanger 91 from the second inlet port 95 of the molten salt-water heat exchanger, exchanges heat with the molten salt after heat release, so that the molten salt forms low-temperature molten salt, and the low-temperature molten salt is output from the first outlet port 92 of the molten salt-water heat exchanger, and enters the low-temperature molten salt storage tank 3 from the inlet port 99 of the low-temperature molten salt storage tank for storage. The hot water after heat exchange is output from the second outlet port 96 of the molten salt-water heat exchanger into the deaerator, is heated by the second high-temperature heater 71 and the first high-temperature heater 70, and is transported back to the boiler 1.

[0067] S24: The low-temperature molten salt in the low-temperature molten salt storage tank 3 enters the molten salt-water heat exchanger 91 through the outlet port 25 of the low-temperature molten salt storage tank and the first inlet port 92 of the molten salt-water heat exchanger to release heat, and the heat of the low-temperature molten salt is used to supply steam to the thermal power unit, thereby reducing the steam extraction of the original thermal power unit and improving the power generation capacity (not shown in the figure).

[0068] In the description of the present invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0069] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the present invention, unless otherwise clearly specified and limited, when a first feature is “on” or “below” a second feature, it may be that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, when a first feature is “above”, “above” or “above” a second feature, it may be that the first feature is directly above or obliquely above the second feature, or it may simply mean that the first feature is higher in level than the second feature. When a first feature is “below”, “below” or “below” a second feature, it may be that the first feature is directly below or obliquely below the second feature, or it may simply mean that the first feature is lower in level than the second feature.

[0071] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "embodiment", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0072] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may alter, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A molten salt energy storage system for a thermal power unit, comprising a boiler (1), It is characterized in that It also includes a heat storage system (A), a steam-heated molten salt system (B), a molten salt steam generation system (C), a molten salt feedwater heating system (D), a steam turbine unit (E) and a feedwater system (F); The boiler (1) is connected to the steam turbine unit (E) and the steam molten salt heating system (B), respectively; the water supply system (F) is connected to the boiler (1) and the steam heating molten salt system (B), respectively; and the heat storage system (A) is connected to the steam molten salt heating system (B); The steam turbine unit (E) is in communication with the steam-heated molten salt system (B); The heat storage system (A) is in communication with the molten salt steam generating system (C); The heat storage system (A) is connected to the molten salt water heating system (D), and the molten salt water heating system (D) is connected to the water supply system (F).

2. A molten salt energy storage system for a thermal power unit as claimed in claim 1, Features: The heat storage system (A) comprises a high-temperature molten salt storage tank (2), a low-temperature molten salt storage tank (3) and a thermocline water storage tank (4); The steam-heated molten salt system (B) comprises a first superheated molten salt heater (5), a second superheated molten salt heater (6), a phase-change molten salt heater (7), a first preheated molten salt heater (8) and a second preheated molten salt heater (9); The inlet end (10) of the high-temperature molten salt storage tank is respectively connected to the first outlet end (11) of the first superheated molten salt heater and the first outlet end (12) of the second superheated molten salt heater, the first inlet end (13) of the first superheated molten salt heater and the first inlet end (14) of the second superheated molten salt heater are both connected to the first outlet end (15) of the phase-change molten salt heater, the second outlet end (16) of the first superheated molten salt heater is connected to the first inlet end (17) of the phase-change molten salt heater, and the second inlet end (18) of the phase-change molten salt heater is respectively connected to the first outlet end (19) of the first preheating molten salt heater. ) is connected to the first outlet end (20) of the second preheating molten salt heater, the second outlet end (21) of the phase change molten salt heater is connected to the first inlet end (22) of the second preheating molten salt heater, and the second inlet end (23) of the second preheating molten salt heater and the second outlet end (24) of the second preheating molten salt heater are respectively connected to the outlet end (25) of the low-temperature molten salt storage tank and the first inlet end (26) of the water supply system, and the first inlet end (27) of the first preheating molten salt heater is connected to the pipeline connecting the second superheated molten salt heater (6) and the low-temperature molten salt storage tank (3) through a first bypass (28); The second outlet end (29) of the first preheating molten salt heater is connected to the first inlet end (31) of the steam-water heat exchanger, the outlet end (32) of the thermocline water storage tank is connected to the second inlet end (33) of the steam-water heat exchanger, and the outlet end (34) of the steam-water heat exchanger is connected to the second inlet end (35) of the water supply system.

3. A molten salt energy storage system for a thermal power unit as claimed in claim 2, Features: The water supply system includes a shaft seal heater (36), a condenser (37) and a water drying tower (38); The steam turbine unit (E) comprises a medium pressure cylinder (39); The inlet end (40) of the intermediate pressure cylinder is in communication with the first outlet end (41) of the boiler, and the outlet end (42) of the intermediate pressure cylinder is in communication with the second inlet end (43) of the first preheating molten salt heater; The second inlet end (35) of the water supply system is connected to the first inlet end (44) of the shaft seal heater, the first outlet end (45) of the shaft seal heater is connected to the inlet end (46) of the condenser, the water drying tower (38) is capable of exchanging heat with the nearly saturated steam condensed in the condenser (37) to form saturated water, and the outlet end (48) of the condenser is connected to the second inlet end of the shaft seal heater (36) through a condensate pump (47), the second outlet end of the shaft seal heater (36) is connected to the third inlet end (51) of the water supply system, and the outlet end (52) of the water supply system is connected to the first inlet end (53) of the boiler.

4. A molten salt energy storage system for a thermal power unit as claimed in claim 3, Features: The molten salt energy storage system also includes a pressure matcher (54); The steam turbine unit (E) comprises a high-pressure cylinder (55); The inlet end (56) of the high-pressure cylinder and the outlet end (57) of the high-pressure cylinder are respectively connected to the second outlet end (58) of the boiler and the second inlet end (59) of the boiler; A second bypass (60) is provided on a pipeline connecting the first outlet end (41) of the boiler and the inlet end (40) of the intermediate pressure cylinder, the second bypass (60) is connected to the second inlet end (61) of the second superheated molten salt heater, the second outlet end (62) of the second superheated molten salt heater is connected to the first inlet end (63) of the pressure matcher, and the outlet end (64) of the pressure matcher is connected to a pipeline connecting the outlet end (57) of the high pressure cylinder and the second inlet end (59) of the boiler; A third bypass (65) is provided on the pipeline connecting the second outlet end (58) of the boiler and the inlet end (56) of the high-pressure cylinder, and the third bypass (65) is connected to the second inlet end (66) of the first superheated molten salt heater. A fourth bypass (67) is provided on the third bypass (65), and the outlet end (68) of the fourth bypass is connected to the second inlet end (69) of the pressure matcher.

5. A molten salt energy storage system for a thermal power unit as claimed in claim 3, Features: The water supply system (F) comprises a first high-pressure heater (70) and a second high-pressure heater (71); The outlet end (24) of the second preheating molten salt heater is connected to the inlet end (72) of the second high-pressure heater, the outlet end (73) of the second high-pressure heater is connected to the inlet end (74) of the first high-pressure heater, and the outlet end (75) of the first high-pressure heater is connected to the first inlet end (53) of the boiler.

6. A molten salt energy storage system for a thermal power unit as claimed in claim 2, Features: The molten salt energy storage system also includes an external steam supply pipeline (89); The molten salt steam generating system (C) comprises a feed water preheating heat exchanger (76), an evaporator (77) and a superheated steam heat exchanger (78); The outlet end (32) of the inclined temperature layer water storage tank is connected to the first inlet end (79) of the feed water preheating heat exchanger, the first outlet end (80) of the feed water preheating heat exchanger and the second inlet end (81) of the feed water preheating heat exchanger are respectively connected to the first inlet end (82) of the evaporator and the first outlet end (83) of the evaporator, the second outlet end (84) of the evaporator and the second inlet end (85) of the evaporator are respectively connected to the first inlet end (86) of the superheated steam heat exchanger and the first outlet end (87) of the superheated steam heat exchanger, the outlet end (98) of the high-temperature molten salt storage tank is connected to the second inlet end (97) of the superheated steam heat exchanger, and the second outlet end (88) of the superheated steam heat exchanger is connected to the inlet end (90) of the external steam supply pipeline.

7. A molten salt energy storage system for a thermal power unit as claimed in claim 6, Features: The molten salt feedwater heating system (D) comprises a molten salt-water heat exchanger (91); The first outlet end (92) and the first inlet end (93) of the molten salt-water heat exchanger are respectively connected to the inlet end (99) of the low-temperature molten salt storage tank and the second outlet end (94) of the feed water preheating heat exchanger, and the second inlet end (95) and the second outlet end (96) of the molten salt-water heat exchanger are both connected to the water supply system (F).

8. A molten salt energy storage system for a thermal power unit as claimed in claim 1, Features: It also includes molten salt electric heating system and hydroelectric heating system; The molten salt electric heating system and the water electric heating system are both connected to the heat storage system (A) to store the heated molten salt and water in the heat storage system (A).

9. A heat storage method for a molten salt energy storage system for a thermal power unit according to any one of claims 1 to 8, Features: Including the stage of reducing the power generation output of the thermal power unit: S11: The boiler (1) discharges main steam, a portion of which enters the steam turbine unit (E) to perform work, and another portion of which enters the steam heating molten salt system (B) and exchanges heat with the heat storage system (A) step by step to form high-pressure supercooled water. The high-pressure supercooled water is transported to the water supply system (F) for heating, and after heating is completed, is transported back to the boiler (1) for further heating; S12: the boiler (1) discharges the reheated steam heated in step S1, the reheated steam enters the steam heating molten salt system (B), and exchanges heat with the heat storage system (A) to form low-pressure superheated steam, and a portion of the main steam in step S1 that enters the steam turbine unit (E) to perform work is discharged by the steam turbine unit (E) and then transported back to the boiler (1) together with the low-pressure superheated steam for further heating; S13: The steam exhausted by the steam turbine unit (E) enters the steam heating molten salt system (B), exchanges heat with the heat storage system (A) to form low-pressure supercooled water, and is heated in the water supply system (F) and transported back to the boiler (1) for further heating.

10. A heat release method for a molten salt energy storage system for a thermal power unit according to any one of claims 1 to 8, Features: Including the stage of increasing the power generation output of the thermal power unit: S21: the heat storage system (A) discharges hot water, the hot water enters the molten salt steam generation system (C), exchanges heat with the heat storage system (A), and is then discharged; S22: The heat storage system (A) discharges part of the low-pressure feed water, which enters the molten salt feed water heating system (D), releases heat to form low-temperature molten salt, and is then transported back to the heat storage system (A) for storage; another part of the low-pressure feed water exchanges heat with the molten salt feed water heat exchanger to form low-pressure medium-temperature feed water, which enters the feed water system (F), is heated in the feed water system (F), and is then transported back to the boiler (1).

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