Cross-seasonal heat storage and supply peak regulation system and method coupled with waste heat recovery of thermoelectric unit

Abstract

The invention relates to a cross-seasonal heat storage and supply peak shaving system and method coupled with thermoelectric unit waste heat recovery, a cross-seasonal heat storage mechanism is arranged, an underground heat storage device and a first heat exchange device are utilized, an absorption heat pump can be started in a non-heating season, waste heat is stored in the underground heat storage device, the situation that the idle capacity of the absorption heat pump is too high, and the heat exchange efficiency is high is avoided. Meanwhile, the problem that the peak regulation capacity of the cogeneration unit in the non-heating season is insufficient, especially the load reduction and peak regulation capacity of the unit is insufficient is solved; in the heating season and when the combined heat and power generation unit operates in a peak regulation mode, the heat supply system can serve as a supplementary heat source to conduct secondary heating on heat supply network water or serve as low-temperature water supplement of the absorption heat pump so as to make up the external heat supply gap generated by the combined heat and power generation unit in the peak regulation mode in order to meet the requirement for flexible adjustment of the electrical load.

Description

Technical Field

[0001] The present invention relates to the field of heating technology, and in particular to an inter-seasonal heat storage heating peak-shaving system and method coupled with waste heat recovery of thermal power units. Background Art

[0002] At present, the heat source for centralized heating in northern cities is still mainly cogeneration, accounting for 49%. Through a series of technical transformations, some thermal power plants have effectively recovered the low-temperature waste heat that was originally wasted by cogeneration units and used it to meet the heat source required for heating in external cities, which has not only reduced the coal consumption of thermal power plants for power generation, but also achieved low-carbon heating.

[0003] However, with the development of clean energy, the positioning of thermal power generation in my country has undergone a fundamental change, from the original main power supply for power supply guarantee to a flexible and adjustable power supply. This leads to the following problems: In the heating season, in order to increase the power grid's ability to absorb new energy electricity, the cogeneration unit can only operate at low load peak load. At this time, the cogeneration unit has insufficient external heating capacity, especially for thermal power plants that have undergone absorption heat pump waste heat recovery and heating transformation. When the cogeneration unit is operated at low load, the waste heat that can be used to recover heating is far less than the waste heat required by the absorption heat pump design condition, resulting in excessive idle capacity of the absorption heat pump, which to a certain extent also causes a waste of equipment investment costs; in the non-heating season, the cogeneration unit of the power plant has insufficient peak load regulation capacity, especially the unit's insufficient load reduction and peak regulation capacity, and the unit's waste heat cannot be effectively utilized, resulting in energy waste.

[0004] Based on this, it is necessary to transform the waste heat recovery system of the thermal power unit to improve the unit's load reduction and peak regulation capabilities and energy utilization rate. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects in the prior art, thereby providing a cross-seasonal heat storage heating peak-shaving system and method coupled with waste heat recovery of thermal power units.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A cross-seasonal heat storage and heating peak-shaving system coupled with waste heat recovery of thermal power units, comprising:

[0008] Combined heat and power unit, including steam turbine, condenser, heater and deaerator;

[0009] A heating mechanism comprises an absorption heat pump and a heat network heater, wherein the absorption heat pump and the condenser form a first heat exchange loop, and the absorption heat pump and the heat network heater form a second heat exchange loop;

[0010] The inter-seasonal heat storage mechanism comprises an underground heat storage device, a first heat exchange device and a second heat exchange device, wherein the first heat exchange device is connected to the heater and / or the deaerator through a third heat exchange loop; the first heat exchange device is connected to the second heat exchange device through a fourth heat exchange loop, the second heat exchange device is connected to the underground heat storage device through a fifth heat exchange loop, the second heat exchange device is connected to the absorption heat pump through a sixth heat exchange loop; the second heat exchange device is connected to the heat network heater through a seventh heat exchange loop;

[0011] The underground heat storage device is connected to the low-temperature water inlet and the low-temperature water outlet of the absorption heat pump respectively to form a low-temperature water circuit, or the underground heat storage device and the second heat exchange device are connected to the low-temperature water inlet and the low-temperature water outlet of the absorption heat pump respectively to form a low-temperature water circuit.

[0012] Preferably, the steam turbine includes a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected in sequence, and the heater includes a high-pressure heater corresponding to the exhaust port of the high-pressure cylinder, a medium-pressure heater corresponding to the heat recovery extraction port of the medium-pressure cylinder, and a low-pressure heater connected to the heat recovery extraction port of the low-pressure cylinder; the low-pressure heater, the deaerator, the medium-pressure heater and the high-pressure heater are connected in sequence along the flow direction of boiler feed water.

[0013] Preferably, the first heat exchange device, the deaerator and the medium-pressure heater form the third heat exchange circuit; or,

[0014] The first heat exchange device and the deaerator constitute the third heat exchange circuit; or,

[0015] The first heat exchange device and the medium-pressure heater form the third heat exchange circuit.

[0016] Preferably, the third heat exchange circuit comprises a first valve provided at the high temperature water inlet of the first heat exchange device and a second valve provided at the high temperature water outlet.

[0017] A feed water circulation pump is provided between the deaerator and the medium-pressure heater, and a first flow valve is provided between the medium-pressure heater and the high-pressure heater.

[0018] Preferably, the heating network heater is connected to the medium-pressure connecting pipe between the medium-pressure cylinder and the low-pressure cylinder through a heating steam extraction pipe, and is turned on in the heating season.

[0019] Preferably, the fifth heat exchange circuit includes a first heat storage branch pipe and a second heat storage branch pipe, the first heat storage branch pipe is connected to an inlet and outlet of the low temperature side of the second heat exchange device and an inlet and outlet of the underground heat storage device, the second heat storage branch pipe is connected to another inlet and outlet of the low temperature side of the second heat exchange device and another inlet and outlet of the underground heat storage device, the underground heat storage device is also connected to the low temperature water outlet of the absorption heat pump, and the first heat storage branch pipe is also connected to the low temperature water inlet of the absorption heat pump;

[0020] The first heat storage branch pipe is provided with a third valve, a fourth valve and a second circulation pump, and the second heat storage branch pipe is provided with a fifth valve and a sixth valve.

[0021] It also includes a bypass pipeline connected between the first heat storage branch pipe and the second heat storage branch pipe, the bypass pipeline is provided with a seventh valve, one end of the bypass pipeline is connected between the third valve and the fourth valve, and the other end is connected between the fifth valve and the sixth valve.

[0022] To achieve the above purpose, the present invention also adopts the following technical solutions:

[0023] A cross-seasonal heat storage heating peak-shaving method coupled with waste heat recovery of thermal power units adopts the above system and includes the following steps:

[0024] In the non-heating season, the second heat exchange circuit, the seventh heat exchange circuit and the low-temperature water circuit are closed, the first heat exchange circuit, the fifth heat exchange circuit and the sixth heat exchange circuit are turned on, and the low-temperature waste heat is stored in the underground heat storage device through the absorption heat pump and the second heat exchange device;

[0025] In the heating season, the third heat exchange loop and the fourth heat exchange loop are closed, and the first heat exchange loop and the second heat exchange loop are connected. The temperature of the first heat exchange loop is increased by the absorption heat pump to heat the heating network water and realize external heat supply. When the cogeneration unit needs to peak, the underground heat storage device and the absorption heat pump are connected to supplement the heating network water, and the absorption heat pump is supplemented with low-temperature water through the low-temperature water loop.

[0026] Preferably, based on the peak load regulation requirements of the cogeneration unit, the following steps are also included:

[0027] In the non-heating season, when the cogeneration unit needs to reduce load and peak load, the third heat exchange loop and the fourth heat exchange loop are also turned on to increase the heat recovery steam extraction of the unit, and store it in the underground heat storage device through the deaerator, the heater, the first heat exchange device and the second heat exchange device; and / or

[0028] In the heating season, when the cogeneration unit needs to peak-shaving, the underground heat storage device and the absorption heat pump are connected, including: when the cogeneration unit needs to reduce the load for peak-shaving, the second heat storage branch pipe and the low-temperature water circuit are also connected, and the heat stored in the underground heat storage device is used to supplement the heating network water, and it also serves as supplementary low-temperature water for the absorption heat pump; when the cogeneration unit needs to increase the load for peak-shaving, the heating steam extraction amount of the unit is reduced to increase the amount of steam used by the unit for power generation. At the same time, the second heat storage branch pipe and the low-temperature water circuit are also connected, and the heat stored in the underground heat storage device is used to supplement the heating network water, and it also serves as supplementary low-temperature water for the absorption heat pump.

[0029] Preferably, the method further comprises the following steps in the non-heating season:

[0030] Based on the peak-shaving efficiency, the third heat exchange circuit in which the first heat exchange device is connected to the deaerator and the medium-pressure heater is selected to perform load-reducing peak-shaving operation of the cogeneration unit in the non-heating season;

[0031] Based on energy-saving requirements, the third heat exchange circuit in which the first heat exchange device is connected to the deaerator is selected to perform load reduction and peak regulation operation of the cogeneration unit in the non-heating season.

[0032] Preferably, the method further comprises the steps of:

[0033] In the heating season, if the difference between the temperature of the stored water of the underground heat storage device and the temperature of the water in the heating network is greater than the set value, the seventh heat exchange circuit is turned on, the second heat storage branch pipe of the fifth heat exchange circuit is turned on, the third valve on the first heat storage branch pipe of the fifth heat exchange circuit is opened, and the fourth valve and the second circulation pump on the first heat storage branch pipe are closed, so that the water inlet of the underground heat storage device and the low-temperature side water outlet of the second heat exchange device are connected to the low-temperature water circuit;

[0034] If the difference between the temperature of the stored water in the underground heat storage device and the temperature of the water in the heating network is less than a set value, or the temperature of the stored water in the underground heat storage device is lower than the temperature of the water in the heating network, the seventh heat exchange circuit is closed, the fifth valve on the second heat storage branch pipe of the fifth heat exchange circuit is opened, the sixth valve is closed, the third valve, the fourth valve and the second circulation pump on the first heat storage branch pipe are closed, and the bypass pipeline is opened so that the water inlet and the water outlet of the underground heat storage device are connected to the low-temperature water circuit, and the stored water in the underground heat storage device flows directly to the low-temperature water inlet of the absorption heat pump.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The cross-seasonal heat storage and heating peak-shaving system and method for coupled cogeneration unit waste heat recovery provided in the above-mentioned technical scheme is provided with a cross-seasonal heat storage mechanism, in which the underground heat storage device and the second heat exchange device are linked with the heating and heating mechanism, and the absorption heat pump can be activated in the non-heating season to store the waste heat in the underground heat storage device, so as to avoid excessive idle capacity of the absorption heat pump, increase the utilization time of the original absorption heat pump and other major equipment of the power plant, and improve the economy of the absorption heat pump renovation project to a certain extent; it can also be used as a supplementary heat source to reheat the heat network water or as a low-temperature water supplement for the absorption heat pump when the cogeneration unit is in peak-shaving operation in the heating season, so as to make up for the external heat supply gap caused by the flexible adjustment of the electric load when the cogeneration unit is in peak-shaving operation; the efficient utilization of the unit's waste heat throughout the year and the peak-shaving operation during the heating season are realized. At the same time, in the above technical scheme, the cross-seasonal heat storage mechanism also includes a first heat exchange device, which forms a third heat exchange circuit with the heater and / or the deaerator, which can solve the problem of insufficient peak-shaving capacity of the cogeneration unit in the non-heating season, especially the insufficient capacity of the unit to reduce load and peak-shaving. The excess water supply for load reduction and peak-shaving of the unit is transported to the first heat exchange device, and is stored through the second heat exchange device using the underground heat storage device, so that the cogeneration unit can easily achieve load reduction and peak-shaving in the non-heating season and avoid waste of waste heat.

[0037] In general, based on the systems and methods of the above-mentioned technical solutions, the cogeneration unit can achieve efficient waste heat utilization and load reduction and peak regulation throughout the year, ensure heating for people's livelihood, and realize the cross-seasonal utilization of low-temperature waste heat from power plants in the non-heating season. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 Schematic diagram of the system framework of the first embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the conducting pipelines of the system of Embodiment 1 of the present invention in the non-heating season.

[0041] Figure 3 This is a schematic diagram of the conduction pipelines of the system in the heating season according to the first embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram of the system framework of the second embodiment of the present invention.

[0043] Figure 5This is a schematic diagram of one type of conducting pipeline of the system of Embodiment 2 of the present invention during the heating season.

[0044] Figure 6 This is a schematic diagram of the piping of the system of Embodiment 3 of the present invention in the non-heating season.

[0045] Figure 7 This is a schematic diagram of the piping of the system of Embodiment 4 of the present invention in the non-heating season.

[0046] Description of reference numerals:

[0047] 100, cogeneration unit; 101, boiler; 102, high-pressure cylinder; 103, medium-pressure cylinder; 104, low-pressure cylinder; 105, condenser; 1051, cooling water circulation pump; 106, cooling tower; 107, low-pressure heater; 108, deaerator; 109, medium-pressure heater; 110, high-pressure heater; 111, medium-pressure connecting pipe; 112, condensate pump; 113, feed water circulation pump; 114, first flow valve; 115, second flow valve;

[0048] 200, heating and heat supply mechanism; 201, absorption heat pump; 202, heating network heater; 203, first heat exchange loop; 2031, first cooling water branch pipe; 2032, second cooling water branch pipe; 204, second heat exchange loop; 2041, first heating network water branch pipe; 2042, second heating network water branch pipe; 205, heating network water main pipe; 2051, heating network circulating water pump; 206, heating network water supply main pipe; 207, heating steam extraction pipe;

[0049] 300, inter-seasonal heat storage mechanism; 301, underground heat storage device; 302, first heat exchange device; 303, second heat exchange device; 304, third heat exchange circuit; 3041, water supply branch pipe; 3042, return branch pipe; 3043, first valve; 3044, second valve; 3045, branch road; 3046, branch road valve; 3047, fourth circulation pump; 305, fourth heat exchange circuit; 3051, water inlet branch; 3052, water outlet branch; 3053, third circulation pump; 306, fifth heat exchange circuit; 3061, first heat storage branch pipe; 3062 , the second heat storage branch pipe; 3063, the third valve; 3064, the second circulation pump; 3065, the fourth valve; 3066, the fifth valve; 3067, the sixth valve; 307, the sixth heat exchange circuit; 3071, the first hot water branch pipe; 3072, the second hot water branch pipe; 308, the seventh heat exchange circuit; 3081, the supplementary heating inlet pipe; 3082, the supplementary heating outlet pipe; 309, the low-temperature water circuit; 3091, the low-temperature water supplementary outlet pipe; 3092, the low-temperature water supplementary inlet pipe; 3093, the low-temperature water circulation pump; 3010, the bypass pipeline; 3011, the seventh valve. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0052] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0053] The embodiment of the present invention discloses a cross-seasonal heat storage and heating peak-shaving system coupled with waste heat recovery of thermal power units, comprising a cogeneration unit 100, a heating and heating mechanism 200 and a cross-seasonal heat storage mechanism 300, wherein the cogeneration unit 100 is the original equipment of the power plant, comprising a boiler 101, a steam turbine, a condenser 105, a heater and a deaerator 108, the steam from the boiler 101 enters the steam turbine to perform work, the steam exhausted by the steam turbine flows into the condenser 105, the condensate flows back to the deaerator 108 and the heater, and after deoxidation and reflux heating, flows back to the boiler 101; the heating and heating mechanism 200 can be the original equipment of the power plant The original equipment may also be the equipment added after upgrading and transformation, including absorption heat pump 201 and heating network heater 202. The absorption heat pump 201 and condenser 105 constitute the first heat exchange loop 203. The absorption heat pump 201 and heating network heater 202 constitute the second heat exchange loop 204. The condensate of the condenser 105 flows into the absorption heat pump 201. The low-temperature condensate is used to produce heat with less heat than that of the medium-temperature heat source but higher than that of the medium-temperature heat source by using the thermal potential difference between a large amount of medium-temperature heat source and a low-temperature heat source. Part of the medium-low heat energy is transferred to a higher temperature to heat the heating network water in the second heat exchange loop 204, thereby realizing waste heat utilization.

[0054] In the heating season, the cogeneration unit 100, which is a flexible adjustable power source, can only operate at low load and peak load, which leads to insufficient external heating capacity of the cogeneration unit 100, especially for thermal power plants that have undergone absorption heat pump 201 waste heat recovery and heating transformation. The waste heat that can be used for heating is far less than the waste heat required by the absorption heat pump 201 under the design condition, resulting in too high idle capacity of the absorption heat pump 201. In the non-heating season, the low-temperature waste heat of the cogeneration unit 100 has no other use and can only be discharged and wasted. At the same time, the load reduction and peak load regulation capacity of the cogeneration unit 100 is insufficient, and the energy utilization rate is not high, resulting in low economic benefits of the system.

[0055] Based on this, the system of the embodiment of the present invention adds a cross-seasonal heat storage mechanism 300, including an underground heat storage device 301, a first heat exchange device 302 and a second heat exchange device 303.

[0056] The first heat exchange device 302 is connected to the heater and / or the deaerator 108 via a third heat exchange loop 304, and when the cogeneration unit 100 needs to reduce load and peak load in the non-heating season, the excess feed water output after being heated by the deaerator 108 and the heater is input to the first heat exchange device 302 via the third heat exchange loop 304; the first heat exchange device 302 is connected to the second heat exchange device 303 via a fourth heat exchange loop 305, and the heat of the excess feed water input to the first heat exchange device 302 can be transferred to the second heat exchange device 303, and the second heat exchange device 303 can be connected to the first heat exchange device 302 via a fourth heat exchange loop 305. 03 is connected to the underground heat storage device 301 through the fifth heat exchange loop 306, and can transfer the above-mentioned heat to the underground heat storage device 301 for storage; at the same time, the second heat exchange device 303 is connected to the absorption heat pump 201 through the sixth heat exchange loop 307, and can transfer the heat generated by the absorption heat pump 201 through the low-temperature condensate water in the non-heating season to the second heat exchange device 303, and then transfer it to the underground heat storage device 301 for storage; thus, the underground heat storage device 301 can store excess heat during the normal operation and load reduction and peak regulation operation of the cogeneration unit 100.

[0057] At the same time, the second heat exchange device 303 and the underground heat storage device 301 can also be used to directly heat the hot water network in the heating season. As a supplement to the heat source, the second heat exchange device 303 and / or the underground heat storage device 301 are also connected to the low-temperature water inlet and low-temperature water outlet of the absorption heat pump 201, respectively, to form a low-temperature water loop 309. In the heating season, the cogeneration unit 100 reduces the load and peaks. When the steam and condensed water of the cogeneration unit 100 are insufficient, the low-temperature water of the second heat exchange device 303 and the underground heat storage device 301 can also supplement the low-temperature water of the absorption heat pump 201, thereby ensuring that the absorption heat pump 201 fully heats the hot water network in the second heat exchange loop 204, which not only realizes the load reduction and peak regulation of the cogeneration unit 100, but also ensures the heating of the people's livelihood. As a preferred embodiment, the sixth heat exchange loop 307 is connected to the fourth heat exchange loop 305, sharing part of the pipeline, simplifying the pipeline, and reducing costs. Preferably, the second heat exchange device 303 is connected to the heating network heater 202 via a seventh heat exchange loop 308 .

[0058] Based on the above system, an embodiment of the present invention further discloses a cross-seasonal heat storage heating peak-shaving method coupled with waste heat recovery of a thermal power unit, comprising the following steps:

[0059] In the non-heating season, the second heat exchange loop 204, the seventh heat exchange loop 308 and the low-temperature water loop 309 are closed, and the first heat exchange loop 203, the fifth heat exchange loop 306 and the sixth heat exchange loop 307 are turned on. Then, the condensate of the cogeneration unit 100 can be input into the absorption heat pump 201 through the first heat exchange loop 203, and the absorption heat pump 201 uses the waste heat to release heat. At the same time, the sixth heat exchange loop 307 connects the second heat exchange device 303 and the absorption heat pump 201, so as to transfer the heat of the absorption heat pump 201 to the second heat exchange device 303, and then the second heat exchange device 303 transfers the heat to the underground heat storage device 301 through the fifth heat exchange loop 306 for storage.

[0060] Based on the peak-shaving requirement, the flow in the third heat exchange loop 304 is turned on and controlled, that is, when the cogeneration unit 100 performs load reduction peak-shaving, the feed water heat exchange amount of the deaerator 108 and / or the heater is increased, thereby increasing the amount of steam consumed by the deaerator 108 and / or the heater, thereby reducing the amount of steam used by the cogeneration unit 100 for power generation, so that the cogeneration unit 100 achieves load reduction peak-shaving, and at the same time, the excess feed water output after being heated by the deaerator 108 and / or the heater is input into the first heat exchange device 302 through the third heat exchange loop 304, and the heat is transferred and stored in the underground heat storage device 301 through the fourth heat exchange loop 305 and the second heat exchange device 303; thus, in the non-heating season, the waste heat is stored in the underground heat storage device 301 through the absorption heat pump 201, the first heat exchange device 302 and the second heat exchange device 303;

[0061] In the heating season, the third heat exchange loop 304, the fourth heat exchange loop 305 and the sixth heat exchange loop 307 are closed, and the first heat exchange loop 203 and the second heat exchange loop 204 are turned on. Then, the condensate of the cogeneration unit 100 can be input into the absorption heat pump 201 through the first heat exchange loop 203. The absorption heat pump 201 utilizes the waste heat to release heat, and the temperature of the first heat exchange loop 203 is increased through the absorption heat pump 201 to heat the hot network water.

[0062] When the cogeneration unit needs to be peak-loaded, the underground heat storage device 301 is connected to the absorption heat pump 201 to supplement the heating network water, and the absorption heat pump 201 is supplemented with low-temperature water through the low-temperature water circuit 309. Specifically, when the cogeneration unit needs to reduce the load to be peak-loaded, if the steam and condensate of the cogeneration unit 100 are insufficient, the low-temperature water of the second heat exchange device 303 and / or the underground heat storage device 301 can also supplement the low-temperature water entering the absorption heat pump 201, thereby ensuring that the low-temperature water input to the absorption heat pump 201 is full. The absorption heat pump 201 works normally to heat the water in the heat network without increasing the load of the cogeneration unit 100; when the cogeneration unit needs to increase the load for peak regulation, the heating steam extraction amount of the unit is reduced to increase the amount of steam used for power generation by the unit. At the same time, the second heat storage branch pipe 3062 and the low-temperature water circuit 309 are connected, and the heat stored in the buried heat storage device 301 is used to supplement the heating network water, and it also serves as supplementary low-temperature water for the absorption heat pump 201.

[0063] In general, based on the system and method of the above technical solution, the cogeneration unit 100 can achieve efficient waste heat utilization and flexible peak load regulation throughout the year, ensure heating for people's livelihood, and realize cross-seasonal utilization of low-temperature waste heat from power plants in the non-heating season.

[0064] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in several embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0065] As attached Figure 1In the illustrated embodiment 1, the steam turbine includes a high-pressure cylinder 102, an intermediate-pressure cylinder 103 and a low-pressure cylinder 104 connected in sequence, the heater includes a high-pressure heater 110 corresponding to the exhaust port connected to the high-pressure cylinder 102, an intermediate-pressure heater 109 corresponding to the extraction port connected to the intermediate-pressure cylinder 103, and a low-pressure heater 107 connected to the heat recovery extraction port of the low-pressure cylinder 104; the cogeneration unit 100 also includes a boiler 101 and a cooling tower 106. Specifically, the main steam outlet of the boiler 101 is connected to the steam inlet of the high-pressure cylinder 102, the exhaust port of the high-pressure cylinder 102 is connected to the cold re-inlet of the boiler 101 and the steam inlet of the high-pressure heater 110, the hot re-outlet of the boiler 101 is connected to the steam inlet of the medium-pressure cylinder 103, the heat recovery steam extraction port of the medium-pressure cylinder 103 is connected to the steam inlet of the medium-pressure heater 109, the exhaust port of the medium-pressure cylinder 103 is connected to the steam inlet of the deaerator 108, the exhaust port of the medium-pressure cylinder 103 is also connected to the steam inlet of the low-pressure cylinder 104 through the medium-pressure connecting pipe 111, and the heat recovery steam extraction port of the low-pressure cylinder 104 is connected to the steam inlet of the low-pressure heater 107 The exhaust port of the low-pressure cylinder 104 is connected to the exhaust steam inlet of the condenser 105, the low-temperature cooling water side of the condenser 105 is connected to the cooling tower 106, a corresponding control valve is provided on the connecting pipeline, and a cooling circulating water pump is installed at the cooling water inlet of the condenser 105, the condensate outlet of the condenser 105 is connected to the water inlet of the condensate pump 112, the condensate pump 112 is connected to the low-pressure heater 107, the low-pressure heater 107, the deaerator 108, the medium-pressure heater 109 and the high-pressure heater 110 are connected in sequence along the flow direction of the boiler 101 feed water, and the feed water outlet of the high-pressure heater 110 is connected to the feed water inlet of the boiler 101. The above is one of the conventional connection methods of the cogeneration unit 100.

[0066] In this embodiment, the absorption heat pump 201 in the heating and heat supply mechanism 200 is a second-class absorption heat pump 201, the heat network heater 202 is a heat exchanger, and the first heat exchange loop 203 includes a first cooling water branch pipe 2031, a second cooling water branch pipe 2032 and a corresponding control valve. Specifically, the low-temperature water outlet of the absorption heat pump 201 is connected to the cooling water inlet of the condenser 105 through the first cooling water branch pipe 2031, and a cooling water circulation pump 1051 is provided at the cooling water inlet of the condenser 105. The low-temperature water inlet of the absorption heat pump 201 is connected to the cooling water inlet of the condenser 105 through the second cooling water branch pipe 2032. Water outlet connection; the second heat exchange loop 204 is connected to the heat network water main pipe 205 and the heat network water supply main pipe 206. Specifically, the second heat exchange loop 204 includes a first heat network water branch pipe 2041, a second heat network water branch pipe 2042 and a corresponding control valve. A heat network circulating water pump 2051 is provided on the heat network water main pipe 205, and its water outlet end is connected to the high-temperature water inlet of the absorption heat pump 201 through the second heat network water branch pipe 2042. The high-temperature water outlet of the absorption heat pump 201 is connected to the water inlet of the heat network heater 202 through the first heat network branch pipe, and the water outlet of the heat network heater 202 is connected to the heat network water supply main pipe 206.

[0067] More preferably, the heat network heater 202 is connected to the exhaust pipe of the medium pressure cylinder 103 through the heating steam extraction pipe 207, and the steam inlet of the heat network heater 202 is connected through the exhaust pipe of the heating steam extraction pipe 207 (i.e., the medium pressure connecting pipe 111), and the heating steam extraction pipe 207 and the medium pressure connecting pipe 111 are also respectively provided with corresponding control valves.

[0068] The inter-seasonal heat storage mechanism 300 includes an underground heat storage device 301, a first heat exchange device 302, and a second heat exchange device 303. The first heat exchange device 302 is connected to the heater and the deaerator 108 through a third heat exchange loop 304. Specifically, the third heat exchange loop 304 includes a water supply branch pipe 3041 and a return water branch pipe 3042. The water supply branch pipe 3041 connects the high-temperature water inlet of the first heat exchange device 302 and the water supply outlet of the medium-pressure heater 109, and a first valve 3043 is provided on it. The return water branch pipe 3042 connects the high-temperature water inlet of the first heat exchange device 302 and the return water outlet of the medium-pressure heater 109. The high-temperature water outlet of the first heat exchange device 302 is connected to the feed water outlet of the deaerator 108 and the feed water inlet of the medium-pressure heater 109. The condensate pump 112 is arranged between the condensate outlet of the condenser 105 and the feed water inlet of the low-pressure heater 107. The flow valve includes a first flow valve 114 arranged between the medium-pressure heater 109 and the high-pressure heater 110.

[0069] The first heat exchange device 302 and the second heat exchange device 303 are connected through the fourth heat exchange loop 305. Specifically, the fourth heat exchange loop 305 includes an inlet branch 3051, an outlet branch 3052, and corresponding control valves and a third circulation pump 3053. The inlet branch 3051 connects the low-temperature water outlet of the first heat exchange device 302 and the high-temperature water inlet of the second heat exchange device 303, and is provided with at least one control valve and a third circulation pump 3053. The outlet branch 3052 connects the low-temperature water inlet of the first heat exchange device 302 and the high-temperature water outlet of the second heat exchange device 303, and is provided with a control valve.

[0070] The second heat exchange device 303 is connected to the underground heat storage device 301 through the fifth heat exchange loop 306, and the second heat exchange device 303 is connected to the absorption heat pump 201 through the sixth heat exchange loop 307; specifically, the fifth heat exchange loop 306 includes a first heat storage branch pipe 3061 and a second heat storage branch pipe 3062, the first heat storage branch pipe 3061 connects an inlet and outlet on the low temperature side of the second heat exchange device 303 and an inlet and outlet of the underground heat storage device 301, the second heat storage branch pipe 3062 connects another inlet and outlet on the low temperature side of the second heat exchange device 303 and another inlet and outlet of the underground heat storage device 301, the first heat storage branch pipe 3061 is provided with a third valve 3063 and a second circulation pump 3064, and the second heat storage branch pipe 3062 is provided with a fifth valve 3066.

[0071] The second heat exchange device 303 is connected to the absorption heat pump 201 through the sixth heat exchange loop 307. Specifically, the sixth heat exchange loop 307 includes a first hot water branch pipe 3071 and a second hot water branch pipe 3072. The first hot water branch pipe 3071 connects the high-temperature water outlet of the absorption heat pump 201 and the water inlet branch pipe of the fourth heat exchange loop 305. Two control valves are provided on the water inlet branch pipe of the fourth heat exchange loop 305, which are respectively located upstream and downstream of the connection between the first hot water branch pipe 3071 and the water inlet branch pipe. The third circulation pump 3053 is located downstream of the connection between the first hot water branch pipe 3071 and the water inlet branch pipe, close to the high-temperature water inlet of the second heat exchange device 303. The second hot water branch pipe 3072 connects the high-temperature water inlet of the absorption heat pump 201 and the high-temperature water outlet of the second heat exchange device 303, and a control valve is provided on it.

[0072] Preferably, a seventh heat exchange loop 308 is formed between the second heat exchange device 303 and the heat network heater 202. Specifically, the seventh heat exchange loop 308 includes a supplementary heating inlet pipe 3081, a supplementary heating outlet pipe 3082 and a corresponding control valve. The supplementary heating inlet pipe 3081 is connected to the second heat network water branch pipe 2042 and the high-temperature water inlet of the second heat exchange device 303, and the supplementary heating outlet pipe 3082 is connected to the first heat network water branch pipe 2041 and the high-temperature water outlet of the second heat exchange device 303.

[0073] The second heat exchange device 303 and / or the underground heat storage device 301 are also connected to the low-temperature water inlet and the low-temperature water outlet of the absorption heat pump 201, respectively, to form a low-temperature water loop 309; Figure 3 As shown, the water inlet of the underground heat storage device 301 is also connected to the low-temperature water outlet of the absorption heat pump 201, that is, the low-temperature water replenishment outlet pipe 3091 of the low-temperature water loop 309, and the first heat storage branch pipe 3061 connected to the low-temperature side water outlet of the second heat exchange device 303 is also connected to the low-temperature water inlet of the absorption heat pump 201, that is, through the low-temperature water replenishment inlet pipe 3092 of the low-temperature water loop 309 and the low-temperature water inlet of the absorption heat pump 201, and the low-temperature water replenishment inlet pipe 3092 is also provided with a low-temperature water circulation pump 3093 and a corresponding control valve, and the low-temperature water replenishment outlet pipe 3091 is also provided with a corresponding control valve.

[0074] Based on the above structure, the corresponding circuit is opened or closed by controlling the corresponding valve on each circuit.

[0075] Specifically, as attached Figure 2 As shown, in the non-heating season, the cogeneration unit 100 operates normally, the control valves on the first heat exchange loop 203 are all turned on, the first heat exchange loop 203 is turned on, the cooling water of the condenser 105 is input into the absorption heat pump 201, the control valves on the second heat exchange loop 204 are all closed, the second heat exchange loop 204 is closed, and at the same time, the fourth heat exchange loop 305 and the sixth heat exchange loop 307 are turned on, and the high temperature water of the absorption heat pump 201 enters the second heat exchange device 30 3, the fifth heat exchange loop 306 is turned on, the first heat storage branch pipe 3061 of the fifth heat exchange loop 306 is the outlet pipe of the underground heat storage device, the second heat storage branch pipe 3062 is the inlet pipe of the underground heat storage device, the third valve 3063, the fifth valve 3066 and the second circulation pump 3064 work normally, and the low-temperature water loop 309 is closed, thereby, the heat of the absorption heat pump 201 is transferred and stored in the underground heat storage device 301; the cogeneration unit 100 needs to reduce the load When the load is at a peak, the first valve 3043 and the second valve 3044 can be opened to increase the flow of the feed water circulation pump 113 and the condensate pump 112, increase the feed water heat exchange of the deaerator 108 and the medium-pressure heater 109, and then increase the amount of steam consumed by the deaerator 108 and the medium-pressure heater 109, thereby reducing the amount of steam used by the cogeneration unit 100 for power generation, so that the cogeneration unit 100 can achieve load reduction and peak regulation, and the steam consumed by the deaerator 108 and the medium-pressure heater 109 can be reduced. The excess water output after heating enters the first heat exchange device 302 through the water supply branch pipe 3041, and exchanges heat with the second heat exchange device 303 through the fourth heat exchange loop 305. The two streams of high-temperature water are mixed and enter the second heat exchange device 303 to exchange heat and store with the underground heat storage device 301. At this time, the high-temperature water volume is large, the water temperature is high, and the heat exchange efficiency is high, so that all the excess heat of the cogeneration unit 100 can be stored in the underground heat storage device 301 to achieve long-term storage.

[0076] As attached Figure 3 As shown, in the heating season, the cogeneration unit 100 operates normally, the control valves on the first heat exchange loop 203 are all turned on, the first heat exchange loop 203 is turned on, the cooling water of the condenser 105 is input into the absorption heat pump 201, the control valves on the second heat exchange loop 204 are all turned on, the second heat exchange loop 204 is turned on, the third valve 3063 and the second circulation pump 3064 on the first heat storage branch 3061 of the fifth heat exchange loop 306 are closed, the second heat storage branch 3062 serves as the water inlet pipe of the buried heat storage device, and the fifth valve 3066 thereon operates normally, the low-temperature water loop 309 is turned on, and the third heat exchange loop 304, the fourth heat exchange loop 305 and the sixth heat exchange loop 307 are closed at the same time. When the user's required heat is relatively low, the seventh heat exchange circuit 308 is turned on, and the heat stored in the underground heat storage device 301 is used to supplement the heating of the hot network water. The control valve on the heating steam extraction pipe 207 is not opened, and the absorption heat pump 201 works normally. When the user's required heat increases, the hot network water is heated again by the absorption heat pump 201. At the same time, the control valve on the heating steam extraction pipe 207 is opened, and the hot network heater 202 heats the hot network water again through the heating steam extraction pipe 207, so that the temperature of the hot network water is further increased to meet the heating requirements. When the cogeneration unit 100 needs to reduce the load for peak regulation, the steam volume and the cooling water volume of the condenser 105 are insufficient, the heat supply of the absorption heat pump 201 is insufficient, and the extraction volume of the heating steam extraction pipe 207 is also insufficient. At this time, the low-temperature water of the second heat exchange device 303 is input to the low-temperature water side of the absorption heat pump 201 through the low-temperature water circuit 309, as a supplementary low-temperature heat source for the absorption heat pump 201, so that the absorption heat pump 201 can generate enough heat to compensate for the insufficient heating steam extraction volume and the waste heat of the circulating water when the cogeneration unit 100 reduces the load for peak regulation. The gap in external heat supply caused by insufficient heat; when the cogeneration unit needs to increase the load for peak regulation, the heating steam extraction of the unit is reduced to increase the amount of steam used by the unit for power generation. At the same time, the second heat storage branch pipe 3062 and the low-temperature water circuit 309 are connected, and the heat stored in the underground heat storage device 301 is used to supplement the heating network water. At the same time, it is also used as supplementary low-temperature water for the absorption heat pump 201 to make up for the heating gap caused by the unit reducing the heating steam extraction to increase the load of the unit, thereby realizing the load reduction and peak regulation of the unit and ensuring the heating supply for people's livelihood.

[0077] It should be noted that the water inlet and outlet of the underground heat storage device 301 are interchangeable in the heating season and the non-heating season. Figure 2 and attached Figure 3 as shown in .

[0078] As attached Figure 4The second embodiment shown is different from the first embodiment in that the fifth heat exchange circuit 306 also includes a bypass pipeline 3010 connected between the first heat storage branch pipe 3061 and the second heat storage branch pipe 3062, the first heat storage branch pipe 3061 is provided with a third valve 3063, a fourth valve 3065 and a second circulation pump 3064, the second heat storage branch pipe 3062 is provided with a fifth valve 3066 and a sixth valve 3067, the bypass pipeline 3010 is provided with a seventh valve 3011, one end of the bypass pipeline 3010 is connected between the third valve 3063 and the fourth valve 3065, and the other end is connected between the fifth valve 3066 and the sixth valve 3067.

[0079] Based on this, the underground heat storage device 301 can be controlled more flexibly. Specifically, in the heating season, if the difference between the temperature of the stored water of the underground heat storage device 301 and the temperature of the water in the heating network is greater than the set value, the seventh heat exchange loop 308 is turned on, the second heat storage branch pipe 3062 of the fifth heat exchange loop 306 is turned on, the third valve 3063 on the first heat storage branch pipe 3061 of the fifth heat exchange loop 306 is opened, and the fourth valve 3065 and the second circulation pump 3064 on the first heat storage branch pipe 3061 are closed, so that the water inlet of the underground heat storage device 301 and the low-temperature side water outlet of the second heat exchange device 303 are connected to the low-temperature water loop 309, and the low-temperature water circulation pump 3093 and the corresponding control valve in the low-temperature water loop 309 are turned on;

[0080] If the difference between the temperature of the stored water in the underground heat storage device 301 and the temperature of the water in the heating network is less than the set value, or the temperature of the stored water in the underground heat storage device 301 is lower than the temperature of the water in the heating network, the seventh heat exchange loop 308 is closed, the fifth valve 3066 on the second heat storage branch pipe 3062 of the fifth heat exchange loop 306 is opened, the sixth valve 3067 is closed, the third valve 3063, the fourth valve 3065 and the second circulation pump 3064 on the first heat storage branch pipe 3061 are closed, and the bypass line 3010 is opened, so that the water inlet and outlet of the underground heat storage device 301 are connected to the low-temperature water loop 309, and the stored water in the underground heat storage device 301 flows directly to the low-temperature water inlet of the absorption heat pump 201, as shown in the attached Figure 5 shown.

[0081] As attached Figure 6The third embodiment shown is different from the first embodiment in that the third heat exchange circuit 304 in which the first heat exchange device 302 is connected to the deaerator 108, that is, the third heat exchange circuit 304 includes a feed water branch 3041 and a return water branch 3042, the feed water branch 3041 connects the high-temperature water inlet of the first heat exchange device 302 and the feed water outlet of the deaerator 108, and is provided with a first valve 3043 and a fourth circulation pump 3047, the return water branch 3042 connects the high-temperature water outlet of the first heat exchange device 302 and the feed water outlet of the low-pressure heater 107, the feed water outlet of the low-pressure heater 107 is connected to the feed water inlet of the deaerator 108, the high-temperature water outlet of the first heat exchange device 302 is provided with a second valve 3044, the feed water circulation pump 113 is connected between the feed water outlet of the deaerator 108 and the feed water inlet of the medium-pressure heater 109, and the flow valve includes a second flow valve 115 arranged between the medium-pressure heater 109 and the deaerator 108.

[0082] In the non-heating season, when the cogeneration unit 100 needs to reduce the load for peak regulation, the first valve 3043 and the second valve 3044 are opened to increase the flow of the condensate pump 112, increase the heat exchange of the feed water of the deaerator 108, and the excess feed water output after heating by the deaerator 108 enters the first heat exchange device 302 through the feed water branch pipe 3041. Since the heating power consumption of the deaerator 108 is low, it is suitable for long-term load reduction and peak regulation of the cogeneration unit 100, and is more economical.

[0083] Of course, in other embodiments, the third heat exchange loop 304 in which the first heat exchange device 302 is connected to the medium-pressure heater 109, that is, the water supply branch pipe 3041 and the return water branch pipe 3042 are respectively connected to the upstream and downstream of the medium-pressure heater 109, and the water supply circulation pump 113 is arranged at the water supply inlet of the medium-pressure heater 109. In the non-heating season, when the cogeneration unit 100 needs to reduce the load for peak regulation, the first valve 3043 and the second valve 3044 are opened to increase the flow of the condensate pump 112 and the water supply circulation pump 113, and increase the water supply heat exchange capacity of the medium-pressure heater 109, and the excess water supply output after heating by the medium-pressure heater 109 enters the first heat exchange device 302 through the water supply branch pipe 3041. Since the heating efficiency of the medium-pressure heater 109 is relatively high, rapid peak regulation can be achieved, and the peak regulation efficiency is higher.

[0084] Furthermore, as attached Figure 7The fourth embodiment shown in the figure can be combined with the first embodiment and the third embodiment. The third heat exchange circuit 304 includes a feed water branch pipe 3041, a return water branch pipe 3042 and a branch pipe. The feed water branch pipe 3041 connects the high-temperature water inlet of the first heat exchange device 302 and the feed water outlet of the medium-pressure heater 109, and is provided with a first valve 3043. The return water branch pipe 3042 connects the high-temperature water outlet of the first heat exchange device 302 and the feed water outlet of the low-pressure heater 107. The feed water outlet of the low-pressure heater 107 is connected to the outlet of the heat exchange device 302. The water supply inlet of the deaerator 108 is connected, the high-temperature water outlet of the first heat exchange device 302 is provided with a second valve 3044, the water supply circulation pump 113 is connected between the water supply outlet of the deaerator 108 and the water supply inlet of the medium-pressure heater 109, the branch road 3045 connects the water supply branch pipe 3041 and the water outlet of the water supply circulation pump 113, and a branch valve 3046 is provided on it. At the same time, the second flow valve 115 is set between the water outlet of the water supply circulation pump 113 and the water supply inlet of the medium-pressure heater 109. If the first valve 3043 and the second valve 3044 are turned on and the branch valve 3046 is closed, the third heat exchange circuit 304 connects the first heat exchange device 302 with the deaerator 108 and the medium-pressure heater 109. When in use, the flow of the second flow valve 115 and the water supply circulation pump 113 needs to be increased, and the flow of the first flow valve 114 needs to be decreased; if the branch valve 3046 and the second valve 3044 are turned on and the first valve 3043 is closed, the third heat exchange circuit 304 connects the first heat exchange device 302 with the deaerator 108. When in use, the flow of the water supply circulation pump 113 needs to be increased, and the flow of the first flow valve 114 and the second flow valve 115 needs to be decreased.

[0085] Based on the above structure, in the non-heating season, the system can select a suitable third heat exchange loop 304 to be connected according to the peak-shaving requirements. Specifically, based on the peak-shaving efficiency, the third heat exchange loop 304 connecting the first heat exchange device 302 with the deaerator 108 and the medium-pressure heater 109 is selected; based on the energy-saving requirements, the third heat exchange loop 304 connecting the first heat exchange device 302 with the deaerator 108 is selected, so that the choices are more diverse and the adjustments are more flexible.

[0086] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A cross-seasonal heat storage and heating peak-shaving system coupled with waste heat recovery of thermal power units, characterized in that: include: Combined heat and power unit, including steam turbine, condenser, heater and deaerator; A heating mechanism comprises an absorption heat pump and a heat network heater, wherein the absorption heat pump and the condenser form a first heat exchange loop, and the absorption heat pump and the heat network heater form a second heat exchange loop; The inter-seasonal heat storage mechanism comprises an underground heat storage device, a first heat exchange device and a second heat exchange device, wherein the first heat exchange device is connected to the heater and / or the deaerator through a third heat exchange loop; the first heat exchange device is connected to the second heat exchange device through a fourth heat exchange loop, the second heat exchange device is connected to the underground heat storage device through a fifth heat exchange loop, the second heat exchange device is connected to the absorption heat pump through a sixth heat exchange loop; the second heat exchange device is connected to the heat network heater through a seventh heat exchange loop; The underground heat storage device is connected to the low-temperature water inlet and the low-temperature water outlet of the absorption heat pump respectively to form a low-temperature water circuit, or the underground heat storage device and the second heat exchange device are connected to the low-temperature water inlet and the low-temperature water outlet of the absorption heat pump respectively to form a low-temperature water circuit.

2. The system according to claim 1, characterized in that The steam turbine includes a high-pressure cylinder, a medium-pressure cylinder and a low-pressure cylinder connected in sequence, and the heater includes a high-pressure heater corresponding to the exhaust port of the high-pressure cylinder, a medium-pressure heater corresponding to the heat recovery extraction port of the medium-pressure cylinder, and a low-pressure heater connected to the heat recovery extraction port of the low-pressure cylinder; the low-pressure heater, the deaerator, the medium-pressure heater and the high-pressure heater are connected in sequence along the flow direction of boiler feed water.

3. The system according to claim 2, characterized in that The first heat exchange device, the deaerator and the medium-pressure heater form the third heat exchange circuit; or, The first heat exchange device and the deaerator constitute the third heat exchange circuit; or, The first heat exchange device and the medium-pressure heater form the third heat exchange circuit.

4. The system according to claim 3, characterized in that The third heat exchange circuit includes a first valve disposed at a high-temperature water inlet of the first heat exchange device and a second valve disposed at a high-temperature water outlet. A feed water circulation pump is provided between the deaerator and the medium-pressure heater, and a first flow valve is provided between the medium-pressure heater and the high-pressure heater.

5. The system according to claim 2, characterized in that The heating network heater is connected to the medium-pressure connecting pipe between the medium-pressure cylinder and the low-pressure cylinder through a heating steam extraction pipe, and is turned on in the heating season.

6. The system according to claim 1 or 5, characterized in that: The fifth heat exchange circuit includes a first heat storage branch pipe and a second heat storage branch pipe, the first heat storage branch pipe is connected to an inlet and outlet of the low temperature side of the second heat exchange device and an inlet and outlet of the underground heat storage device, the second heat storage branch pipe is connected to another inlet and outlet of the low temperature side of the second heat exchange device and another inlet and outlet of the underground heat storage device, the underground heat storage device is also connected to the low temperature water outlet of the absorption heat pump, and the first heat storage branch pipe is also connected to the low temperature water inlet of the absorption heat pump; The first heat storage branch pipe is provided with a third valve, a fourth valve and a second circulation pump, and the second heat storage branch pipe is provided with a fifth valve and a sixth valve. It also includes a bypass pipeline connected between the first heat storage branch pipe and the second heat storage branch pipe, the bypass pipeline is provided with a seventh valve, one end of the bypass pipeline is connected between the third valve and the fourth valve, and the other end is connected between the fifth valve and the sixth valve.

7. A cross-seasonal heat storage and heating peak-shaving method coupled with waste heat recovery of thermal power units, characterized in that: The system according to any one of claims 1 to 6 comprises the following steps: In the non-heating season, the second heat exchange circuit, the seventh heat exchange circuit and the low-temperature water circuit are closed, the first heat exchange circuit, the fifth heat exchange circuit and the sixth heat exchange circuit are turned on, and the low-temperature waste heat is stored in the underground heat storage device through the absorption heat pump and the second heat exchange device; In the heating season, the third heat exchange loop and the fourth heat exchange loop are closed, and the first heat exchange loop and the second heat exchange loop are connected. The temperature of the first heat exchange loop is increased by the absorption heat pump to heat the heating network water and realize external heat supply. When the cogeneration unit needs to peak, the underground heat storage device and the absorption heat pump are connected to supplement the heating network water, and the absorption heat pump is supplemented with low-temperature water through the low-temperature water loop.

8. The method according to claim 7, characterized in that Based on the peak load requirements of the cogeneration unit, the following steps are also included: In the non-heating season, when the cogeneration unit needs to reduce load and adjust peak load, the third heat exchange loop and the fourth heat exchange loop are also turned on to increase the heat recovery steam extraction of the unit, and store it in the underground heat storage device through the deaerator, the heater, the first heat exchange device and the second heat exchange device; and / or In the heating season, when the cogeneration unit needs to peak-shaving, the underground heat storage device and the absorption heat pump are connected, including: when the cogeneration unit needs to reduce the load for peak-shaving, the second heat storage branch pipe and the low-temperature water circuit are also connected, and the heat stored in the underground heat storage device is used to supplement the heating network water, and it also serves as supplementary low-temperature water for the absorption heat pump; when the cogeneration unit needs to increase the load for peak-shaving, the heating steam extraction amount of the unit is reduced to increase the amount of steam used by the unit for power generation. At the same time, the second heat storage branch pipe and the low-temperature water circuit are also connected, and the heat stored in the underground heat storage device is used to supplement the heating network water, and it also serves as supplementary low-temperature water for the absorption heat pump.

9. The method according to claim 8, characterized in that In the non-heating season, the following steps are also included: Based on the peak-shaving efficiency, the third heat exchange circuit in which the first heat exchange device is connected to the deaerator and the medium-pressure heater is selected to perform load-reducing peak-shaving operation of the cogeneration unit in the non-heating season; Based on energy-saving requirements, the third heat exchange circuit in which the first heat exchange device is connected to the deaerator is selected to perform load reduction and peak regulation operation of the cogeneration unit in the non-heating season.

10. The method according to claim 8, characterized in that The following steps are also included: In the heating season, if the difference between the temperature of the stored water of the underground heat storage device and the temperature of the water in the heating network is greater than the set value, the seventh heat exchange circuit is turned on, the second heat storage branch pipe of the fifth heat exchange circuit is turned on, the third valve on the first heat storage branch pipe of the fifth heat exchange circuit is opened, and the fourth valve and the second circulation pump on the first heat storage branch pipe are closed, so that the water inlet of the underground heat storage device and the low-temperature side water outlet of the second heat exchange device are connected to the low-temperature water circuit; If the difference between the temperature of the stored water in the underground heat storage device and the temperature of the water in the heating network is less than a set value, or the temperature of the stored water in the underground heat storage device is lower than the temperature of the water in the heating network, the seventh heat exchange circuit is closed, the fifth valve on the second heat storage branch pipe of the fifth heat exchange circuit is opened, the sixth valve is closed, the third valve, the fourth valve and the second circulation pump on the first heat storage branch pipe are closed, and the bypass pipeline is opened so that the water inlet and the water outlet of the underground heat storage device are connected to the low-temperature water circuit, and the stored water in the underground heat storage device flows directly to the low-temperature water inlet of the absorption heat pump.

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