Steam cogeneration system and operating method thereof

Abstract

This application relates to a steam cogeneration system, which may include a heat pump and valley power heat storage system, a primary flash steam supply system, a secondary flash steam supply system, and optionally a heat pump recovery system and a tertiary flash steam supply system. This application also relates to an operating method for the steam cogeneration system described above. The steam cogeneration system described herein utilizes a heat pump and valley power heat storage system to achieve economical and reliable heat storage. Furthermore, by controlling the operating states of the primary flash steam supply system, the secondary flash steam supply system, the heat pump recovery system, and the tertiary flash steam supply system, it is possible to supply high-pressure, medium-pressure, and low-pressure steam, as well as high-temperature hot water.

Description

Technical Field

[0001] The present application relates to the field of heat pump energy saving and heat storage technology, and in particular to a steam cogeneration system and a working method thereof. Background Art

[0002] Steam boilers provide high-temperature, high-pressure steam and are widely used in various industrial and daily processes. Existing boilers primarily consist of fuel-fired boilers, such as coal-fired and gas-fired boilers, or electric boilers. However, fuel-fired boilers pose a significant environmental risk. With increasingly stringent national energy conservation and environmental protection requirements, the trend is towards high-efficiency, energy-saving, and low-pollution industrial boilers that utilize clean fuels and corresponding new technologies. Therefore, the future development of the industrial boiler market will be influenced not only by factors such as the speed of national economic growth and investment scale, but also by increasing constraints imposed by energy policies and energy conservation and environmental protection requirements. Consequently, boilers utilizing innovative energy-saving technologies, such as heat pump steam systems, are expected to experience rapid growth.

[0003] Currently, there are many heat pump steam technologies, such as the Chinese invention patent application number CN201710630592.9, titled "A Dual-Heat Source Two-Stage Flash Evaporation Two-Stage Compression Heat Pump Device and Operating Method." While this technology proposes a steam supply technology based on heat pump waste heat recovery, steam generation still relies on an additional heat source, inevitably requiring a reliance on that source. This often prevents direct use in many applications without a heat source. Furthermore, to avoid the significant power consumption of electric boilers, as well as the high electricity prices and operating costs associated with peak and off-peak electricity, a steam supply technology combining heat pump technology with off-peak electricity storage is needed. This would ensure safe and stable operation in all application scenarios, reduce operating costs, and improve the economic efficiency of steam generation. The Chinese invention patent application number CN201410462127.5, titled "A Clean Energy Steam Boiler Using Molten Salt for Heat Transfer and Storage and a Method for Producing Steam Thereof," discloses a steam supply system using molten salt for heat storage. However, molten salt heat storage is a phase change heat storage, which has the following shortcomings: 1. The phase change heat is relatively small, the melting point is relatively low, and the heat storage density is relatively small; 2. The heat storage medium is crystalline salt, and the phase is converted between solid and liquid during use. The unfavorable factors of phase separation in the current use process have not been overcome. The phase change heat of molten salt will gradually decay, and the medium must be replaced regularly, and the operating cost is high; 3. Molten salt is easy to agglomerate during the heat release process, and large gaps will appear in the solid molten salt, and the heat storage density and thermal conductivity coefficient will be reduced; 4. Liquid molten salt is corrosive to the copper and steel pipes of the heat exchanger. The heat exchanger must use corrosion-resistant materials, so the heat exchanger efficiency is low.

[0004] In summary, existing heat pump steam supply systems have the following shortcomings: strong dependence on heat source conditions and the environment; unstable operation and poor performance; limited system usage; high power consumption and high operating costs during peak hours; and expensive energy storage materials and high replacement costs. Therefore, the field needs to develop a steam supply system based on a more economical and reliable heat storage method. Summary of the Invention

[0005] The purpose of this application is to provide a steam co-generation system based on heat pump and valley electricity heat storage and deep heat utilization three-stage flash evaporation. The steam co-generation system described herein mainly includes a heat pump and valley electricity heat storage system, a primary flash evaporation steam supply system, a secondary flash evaporation steam supply system, a heat pump recovery system and a tertiary flash evaporation steam supply system. With the help of the heat pump and valley electricity heat storage system, economical and reliable heat storage can be achieved. In addition, by controlling the working states of the primary flash evaporation steam supply system, the secondary flash evaporation steam supply system, the heat pump recovery system and the tertiary flash evaporation steam supply system, it is possible to supply high-pressure, medium-pressure, low-pressure steam and high-temperature hot water, etc. It should be noted that, in one embodiment, the steam co-generation system described herein may not include a heat pump recovery system and a tertiary flash evaporation steam supply system.

[0006] The purpose of this application is also to provide a working method of the steam cogeneration system as described above.

[0007] In order to solve the above technical problems, this application provides the following technical solutions.

[0008] In a first aspect, the present application provides a steam cogeneration system, characterized in that the steam cogeneration system comprises:

[0009] A heat pump and valley electricity heat storage system is used to heat a low-temperature water working medium into a high-temperature water working medium using an air source and valley electricity. The heat pump and valley electricity heat storage system includes a circulating water tank, a heat storage water supply pump, a hot water storage tank, a heat storage heat pump expansion valve, a heat storage heat pump evaporator, and a heat storage heat pump compressor. A heat storage heat pump condenser and an electric heater are provided in the hot water storage tank. The circulating water tank, the heat storage water supply pump, and the hot water storage tank are fluidically connected in sequence. The heat storage heat pump condenser, the heat storage heat pump expansion valve, the heat storage heat pump evaporator, and the heat storage heat pump compressor form a fluid flow loop.

[0010] A first-stage flash steam supply system, comprising a heat storage tank, a first-stage flash circulation pump, a first-stage flash pressure reducing valve, a first-stage flash tank, a first-stage flash water vapor compressor, a first-stage flash exhaust pipe, a first-stage flash water supply pump, and a first-stage flash water supply pipe, wherein a first-stage flash tank is provided with a first-stage flash atomizing nozzle, wherein the heat storage tank, the first-stage flash circulation pump, the first-stage flash pressure reducing valve, and the first-stage flash tank are fluidly connected in sequence, wherein the first-stage flash tank and the first-stage flash water vapor compressor are fluidly connected for conveying water vapor to be compressed to the first-stage flash water vapor compressor, wherein the first-stage flash water supply pipe, the first-stage flash water supply pump, and the first-stage flash water vapor compressor are fluidly connected in sequence for conveying external make-up water to the first-stage flash water vapor compressor, wherein the first-stage flash exhaust pipe is fluidly connected to the first-stage flash water vapor compressor for conveying compressed water vapor;

[0011] A two-stage flash steam supply system, comprising a first-stage flash tank, a second-stage flash circulation pump, a second-stage flash pressure reducing valve, a second-stage flash tank, a second-stage flash water vapor compressor, a second-stage flash exhaust pipe, a second-stage flash water supply pump, and a second-stage flash water supply pipe, wherein the first-stage flash tank, the second-stage flash circulation pump, the second-stage flash pressure reducing valve, and the second-stage flash tank are fluidically connected in sequence, wherein the second-stage flash tank and the second-stage flash water vapor compressor are fluidically connected for conveying water vapor to be compressed to the second-stage flash water vapor compressor, wherein the second-stage flash water supply pipe, the second-stage flash water supply pump, and the second-stage flash water vapor compressor are fluidically connected in sequence for conveying external make-up water to the second-stage flash water vapor compressor, wherein the second-stage flash exhaust pipe is fluidly connected to the second-stage flash water vapor compressor for conveying compressed water vapor;

[0012] Wherein, the secondary flash tank, the return water circulation pump and the circulating water tank are fluidically connected in sequence.

[0013] In one embodiment of the first aspect, the steam cogeneration system further comprises:

[0014] A heat pump recovery system, comprising a secondary flash tank, a return water circulation pump, a circulating water tank, a heat pump evaporator, a heat pump expansion valve, a heat pump condenser, a heat pump compressor, and a first return water bypass pipe, wherein the secondary flash tank, the return water circulation pump, the heat pump evaporator, and the circulating water tank are fluidically connected in sequence, wherein the heat pump evaporator, the heat pump expansion valve, the heat pump condenser, and the heat pump compressor form a fluid loop, wherein the return water circulation pump is fluidically connected to the heat pump condenser via the first return water bypass pipe;

[0015] A three-stage flash steam supply system comprises a secondary flash tank, a return water circulation pump, a third-stage flash pressure reducing valve, a third-stage flash tank, a third-stage flash water vapor compressor, a third-stage flash exhaust pipe, a third-stage flash water supply pump and a third-stage flash water supply pipe, wherein the secondary flash tank, the return water circulation pump, the third-stage flash pressure reducing valve and the third-stage flash tank are fluidically connected in sequence, wherein the third-stage flash tank and the third-stage flash water vapor compressor are fluidically connected for conveying water vapor to be compressed to the third-stage flash water vapor compressor, wherein the third-stage flash water supply pipe, the third-stage flash water supply pump and the third-stage flash water vapor compressor are fluidically connected in sequence for conveying external supplementary water to the third-stage flash water vapor compressor, wherein the third-stage flash exhaust pipe is fluidly connected to the third-stage flash water vapor compressor for conveying compressed water vapor.

[0016] In one embodiment of the first aspect, the first-stage flash steam supply system includes a first-stage flash exhaust bypass pipe, one end of the first-stage flash exhaust bypass pipe is in fluid communication with the first-stage flash tank, and the other end of the first-stage flash exhaust pipe is in fluid communication with the first-stage flash tank;

[0017] The secondary flash steam supply system includes a secondary flash exhaust bypass pipe, one end of which is in fluid communication with the secondary flash tank, and the other end of which is in fluid communication with the secondary flash exhaust pipe.

[0018] In one embodiment of the first aspect, the primary flash steam supply system includes a primary flash drain pipe for draining water from the primary flash tank. The secondary flash steam supply system includes a secondary flash drain pipe for draining water from the secondary flash tank.

[0019] In one embodiment of the first aspect, the three-stage flash steam supply system includes a three-stage flash exhaust bypass pipe, one end of which is in fluid communication with the three-stage flash tank and the other end of which is in fluid communication with the three-stage flash exhaust pipe. The three-stage flash steam supply system includes a three-stage flash drain pipe for draining water from the three-stage flash tank.

[0020] In one embodiment of the first aspect, the three-stage flash steam supply system further includes a three-stage flash circulation pump, and the three-stage flash tank, the three-stage flash circulation pump and the heat pump evaporator are fluidically connected in sequence.

[0021] In one embodiment of the first aspect, the heat pump and valley power thermal storage system includes a thermal storage water supply pump outlet pipe for delivering external replenishment water to the hot water storage tank. The circulating water tank includes a circulating water tank drain pipe for draining water from the circulating water tank. The hot water storage tank includes a hot water tank drain pipe for draining water from the hot water storage tank.

[0022] In a second aspect, the present application provides a method for operating the steam cogeneration system according to the first aspect, characterized in that the method comprises the following steps:

[0023] S1: At night, the water working medium in the heat storage tank of the heat pump and valley electricity heat storage system is heated by an air source and valley electricity to obtain a first high-temperature water working medium;

[0024] S2: When steam supply is required, the first high-temperature water working medium is flash evaporated by the first flash steam supply system and the second flash steam supply system to obtain high-temperature and high-pressure or medium-temperature and medium-pressure steam;

[0025] Wherein, in step S1, the low-temperature water working medium from the circulating water tank is not mixed with the high-temperature water working medium in the hot water storage tank.

[0026] In one embodiment of the second aspect, the method comprises the following steps:

[0027] S1: At night, the water working medium in the heat storage tank of the heat pump and valley electricity heat storage system is heated by an air source and valley electricity to obtain a first high-temperature water working medium;

[0028] S2: When steam supply is required, the first high-temperature water working medium is flash evaporated by the first flash steam supply system and the second flash steam supply system to obtain high-temperature and high-pressure or medium-temperature and medium-pressure steam;

[0029] S3: flash evaporating the second high-temperature water working medium from the heat pump condenser using a three-stage flash steam supply system to obtain low-temperature and low-pressure water vapor;

[0030] Wherein, in step S1, the low-temperature water working medium from the circulating water tank is not mixed with the high-temperature water working medium in the hot water storage tank.

[0031] Compared with the prior art, the positive effects of the present invention are as follows.

[0032] 1. By using air source heat pumps for heat storage, the hot water in the heat storage tank is first heated to 120°C to achieve the first-level medium-temperature heat storage. This can effectively utilize the performance advantages of air source heat pumps, reduce electricity consumption, and reduce operating costs and expenses. Air source is a ubiquitous heat source, which effectively solves the dependence of application production sites on heat sources.

[0033] 2. By using valley electricity heat storage, thermal energy is stored through electric heating during the low electricity consumption period in the city at night, and the hot water in the water storage tank heated to 120°C by the air source heat pump is further heated to above 200°C, realizing the second-level high-temperature heat storage, improving the temperature quality of the stored heat, and effectively solving the dependence of the application production site on the heat source. It can also be directly used in many application scenarios without heat sources.

[0034] 3. The combination of air source heat pump heat storage and electric heating heat storage effectively realizes the heat storage capacity of hot water in different temperature ranges from low temperature to high temperature, reducing the heat storage energy consumption.

[0035] 4. By using high-temperature and high-pressure hot water above 200°C for heat storage, the water working fluid is cheap, the cost of use is low, and it does not corrode the water tank, effectively avoiding the high cost of molten salt heat storage.

[0036] 5. By directly flashing high-temperature and high-pressure hot water above 200°C to generate high-temperature and high-pressure steam, the heat exchange temperature difference and heat exchange system required for molten salt heat storage are effectively avoided, thereby improving steam production efficiency and reducing equipment costs.

[0037] 6. Through multi-stage flash evaporation and coupling with a water vapor compressor, it can not only meet the demand for high-temperature and high-pressure steam above 180°C, but also meet the demand for medium-temperature and medium-pressure steam at 120-180°C, and also meet the demand for low-temperature and low-pressure steam around 80-120°C. It meets the steam demand in almost all ranges of industrial heating, greatly expanding the steam supply range and applicable application scenarios.

[0038] 7. The multi-stage flash evaporation method can reduce the temperature of high-temperature hot water above 200°C to below 80°C, achieving a temperature difference of more than 120°C, fully and deeply utilizing the heat stored in valley electricity, and greatly improving the heat storage utilization rate.

[0039] 8. It is also equipped with a heat pump recovery system to further recycle the hot water after the second stage flash evaporation through the heat pump, thereby improving the utilization rate of heat storage and realizing the deep utilization of heat storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A steam cogeneration system according to one embodiment of the present application is shown.

[0041] The reference numerals in the accompanying drawings are as follows:

[0042] 10 circulating water tank, 11 first stop valve, 12 circulating water tank drain pipe, 13 second stop valve, 14 circulating water tank outlet pipe;

[0043] 31 thermal storage heat pump evaporator pipe, 32 thermal storage heat pump compressor, 33 thermal storage heat pump exhaust pipe, 34 thermal storage heat pump condenser pipe, 35 thermal storage heat pump liquid return pipe, 36 thermal storage heat pump expansion valve, 37 thermal storage heat pump liquid inlet pipe, 38 thermal storage heat pump evaporator, 39 third stop valve, 40 thermal storage water supply pump, 41 thermal storage water supply pump outlet pipe, 42 fourth stop valve, 43 hot water storage tank, 44 electric heater, 45 hot water storage tank drain pipe, 46 fifth stop valve, 47 thermal storage water supply pipe;

[0044] 50 First-stage flash evaporation first stop valve, 51 First-stage flash evaporation circulation pump, 52 First-stage flash evaporation circulation pipe, 53 First-stage flash evaporation pressure reducing valve, 54 First-stage flash evaporation second stop valve, 55 First-stage flash evaporation tank, 56 First-stage flash evaporation atomizing nozzle, 57 First-stage flash evaporation air inlet pipe, 58 First-stage flash evaporation third stop valve, 59 First-stage flash evaporation water compressor, 60 First-stage flash evaporation exhaust pipe, 61 First-stage flash evaporation fourth stop valve, 62 First-stage flash evaporation exhaust bypass pipe, 63 First-stage flash evaporation fifth stop valve, 64 First-stage flash evaporation water supply pump, 65 First-stage flash evaporation water supply pipe, 66 First-stage flash evaporation sixth stop valve, 67 First-stage flash evaporation drain pipe,

[0045] 70 Secondary flash evaporation first stop valve, 71 Secondary flash evaporation circulation pump, 72 Secondary flash evaporation circulation pipe, 73 Secondary flash evaporation pressure reducing valve, 74 Secondary flash evaporation second stop valve, 75 Secondary flash evaporation tank, 76 Secondary flash evaporation atomizing nozzle, 77 Secondary flash evaporation air inlet pipe, 78 Secondary flash evaporation third stop valve, 79 Secondary flash evaporation water compressor, 80 Secondary flash evaporation exhaust pipe, 81 Secondary flash evaporation fourth stop valve, 82 Secondary flash evaporation exhaust bypass pipe, 83 Secondary flash evaporation fifth stop valve, 84 Secondary flash evaporation water supply pump, 85 Secondary flash evaporation water supply pipe, 86 Secondary flash evaporation sixth stop valve, 87 Secondary flash evaporation drain pipe,

[0046] 90 Sixth stop valve, 91 Return water circulation pump, 92 First return water pipe, 93 Seventh stop valve, 94 Second return water pipe, 95 Eighth stop valve, 96 Ninth stop valve, 97 First return water bypass pipe, 98 Heat pump evaporation pipe, 99 Heat pump compressor, 100 Heat pump exhaust pipe, 101 Heat pump condenser, 102 High-temperature water outlet pipe, 103 Heat pump return liquid pipe, 104 Heat pump expansion valve, 105 Heat pump liquid inlet pipe, 106 Heat pump evaporator,

[0047] 113 three-stage flash distillation pressure reducing valve, 114 three-stage flash distillation first stop valve, 115 three-stage flash distillation tank,

[0048] 116 three-stage flash evaporation atomizing nozzle, 117 three-stage flash evaporation air inlet pipe, 118 three-stage flash evaporation second stop valve, 119 three-stage flash evaporation water vapor compressor, 120 three-stage flash evaporation exhaust pipe, 121 three-stage flash evaporation third stop valve, 122 three-stage flash evaporation exhaust bypass pipe, 123 three-stage flash evaporation fourth stop valve, 124 three-stage flash evaporation water supply pump, 125 three-stage flash evaporation water supply pipe, 126 three-stage flash evaporation fifth stop valve, 127 three-stage flash evaporation drain pipe, 128 three-stage flash evaporation sixth stop valve, 129 three-stage flash evaporation return pipe, 130 three-stage flash evaporation circulation pump, 131 three-stage flash evaporation seventh stop valve, 132 three-stage flash evaporation circulation pump outlet pipe. DETAILED DESCRIPTION

[0049] Unless otherwise defined, technical or scientific terms used in this specification and claims shall have the same general meaning as understood by persons having ordinary skills in the technical field to which the present invention belongs.

[0050] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying 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 operate in a specific orientation, and therefore should not be understood as limiting the present invention.

[0051] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the technical features being referred to. Thus, a feature identified with "first," "second," etc., may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0052] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to connection, detachable connection, or integral connection; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; or internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0053] The technical solution of the present application will be clearly and completely described below in conjunction with the accompanying drawings and embodiments of the present application.

[0054] refer to Figure 1 The present application first provides a steam cogeneration system based on an economical and reliable heat pump and valley power heat storage, which mainly includes a heat pump and valley power heat storage system, a first-stage flash steam supply system, a second-stage flash steam supply system, a heat pump recovery system, and a third-stage flash steam supply system. The heat pump is connected to the valley power heat storage system and the first-stage flash steam supply system through a hot water storage tank 43, in which there is a heat storage heat pump condenser 34 and an electric heater 44. The heat pump is connected to the valley power heat storage system and the heat pump recovery system through a circulating water tank 10. The first-stage flash steam supply system and the second-stage flash steam supply system are connected through a first flash tank 55. The second-stage flash steam supply system and the heat pump recovery system are connected through a second flash tank 75. The third-stage flash steam supply system and the heat pump recovery system are connected through a first return water pipe 92 and a high-temperature water outlet pipe 102.

[0055] In a specific embodiment, the heat pump and valley power heat storage system includes a circulating water tank 10, a first stop valve 11, a circulating water tank drain pipe 12, a second stop valve 13, a circulating water tank outlet pipe 14, a thermal storage heat pump evaporator pipe 31, a thermal storage heat pump compressor 32, a thermal storage heat pump exhaust pipe 33, a thermal storage heat pump condenser pipe 34, a thermal storage heat pump return pipe 35, a thermal storage heat pump expansion valve 36, a thermal storage heat pump inlet pipe 37, a thermal storage heat pump evaporator 38, a third stop valve 39, a thermal storage water supply pump 40, a thermal storage water supply pump outlet pipe 41, a fourth stop valve 42, a hot water storage tank 43, an electric heater 44, a hot water storage tank drain pipe 45, a fifth stop valve 46 and a thermal storage water supply pipe 47.

[0056] In this embodiment, the circulating water tank 10 is connected to a thermal storage water supply pump 40 via a circulating water tank outlet pipe 14, and the thermal storage water supply pump 40 is connected to a hot water storage tank 43 via a thermal storage water supply pump outlet pipe 41. A second shut-off valve 13 is provided on the circulating water tank outlet pipe 14, and a fourth shut-off valve 42 is provided on the thermal storage water supply pump outlet pipe 41. This allows the water working medium in the circulating water tank 10 to be transported to the hot water storage tank 43. The circulating water tank 10 is also fluidically connected to a circulating water tank drain pipe 12 for draining water from the circulating water tank 10. The circulating water tank drain pipe 12 may be provided with a first shut-off valve 11. When the circulating water tank 10 is running low on water, external water can be supplied to the hot water storage tank 43 via a thermal storage water supply pipe 47 and the thermal storage water supply pump 40. A third shut-off valve 39 may be provided on the thermal storage water supply pipe 47.

[0057] In this embodiment, the hot water storage tank 43 may be equipped with a heat pump condenser 34 and an electric heater 44, which are used to heat the water working medium in the hot water storage tank 43 through condensation of the heat pump working medium or electrical heating. The heat pump condenser 34 is connected to the heat pump expansion valve 36 via a heat pump return pipe 35. The heat pump expansion valve 36 is connected to the heat pump evaporator 38 via a heat pump inlet pipe 37. The heat pump evaporator 38 is connected to the heat pump compressor 32 via a heat pump evaporation pipe 31. The heat pump compressor 32 is connected to the heat pump condenser 34 via a heat pump exhaust pipe 33, forming a fluid flow loop. The hot water storage tank 43 may be connected to a heat pump drain pipe 45 for draining the high-temperature hot water from the hot water storage tank 43. The heat pump drain pipe 45 is typically located at the bottom of the hot water storage tank 43 and may be equipped with a fifth shut-off valve 46.

[0058] In a specific embodiment, the first-stage flash steam supply system includes a heat storage tank 43, a first-stage flash first stop valve 50, a first-stage flash circulation pump 51, a first-stage flash circulation pipe 52, a first-stage flash pressure reducing valve 53, a first-stage flash second stop valve 54, a first-stage flash tank 55, a first-stage flash atomizing nozzle 56, a first-stage flash air inlet pipe 57, a first-stage flash third stop valve 58, a first-stage flash water vapor compressor 59, a first-stage flash exhaust pipe 60, a first-stage flash fourth stop valve 61, a first-stage flash exhaust bypass pipe 62, a first-stage flash fifth stop valve 63, a first-stage flash water supply pump 64, a first-stage flash water supply pipe 65, a first-stage flash sixth stop valve 66 and a first-stage flash drain pipe 67.

[0059] In this embodiment, the hot water storage tank 43 is connected to a primary flash evaporation circulation pump 51, and a primary flash evaporation first shut-off valve 50 is provided on the connecting pipeline. The primary flash evaporation circulation pump 51 is connected to a primary flash evaporation pressure reducing valve 53 via a primary flash evaporation circulation pipe 52. The primary flash evaporation pressure reducing valve 53 is connected to a primary flash evaporation tank 55, and a primary flash evaporation second shut-off valve 54 is provided on the connecting pipeline for delivering water to be flashed to the primary flash evaporation tank 55. The primary flash evaporation tank 55 is equipped with a primary flash evaporation atomizing nozzle 56 for flash evaporating the water.

[0060] In this embodiment, the primary flash tank 55 is connected to a primary flash water vapor compressor 59 via a primary flash air inlet pipe 57, supplying water vapor to be compressed to the primary flash water vapor compressor 59. A primary flash air inlet pipe 57 is provided with a primary flash third shut-off valve 58. A primary flash water supply pump 64 can have its water inlet connected to the primary flash water supply pipe 65 and its water outlet connected to the primary flash water vapor compressor 59, replenishing water to the primary flash water vapor compressor 59. A primary flash fifth shut-off valve 63 can be provided on the pipeline connecting the primary flash water supply pump 64 to the primary flash water vapor compressor 59.

[0061] In this embodiment, the primary flash tank 55 is further connected to a primary flash exhaust pipe 60 via a primary flash exhaust bypass pipe 62. A primary flash fourth shut-off valve 61 may be provided on the primary flash exhaust bypass pipe 62. In this embodiment, the primary flash tank 55 is further connected to a primary flash drain pipe 67 for draining water from the primary flash tank 55. A primary flash sixth shut-off valve 66 may be provided on the primary flash drain pipe 67.

[0062] In a specific embodiment, the secondary flash steam supply system includes a primary flash tank 55, a secondary flash first stop valve 70, a secondary flash circulation pump 71, a secondary flash circulation pipe 72, a secondary flash pressure reducing valve 73, a secondary flash second stop valve 74, a secondary flash tank 75, a secondary flash atomizing nozzle 76, a secondary flash air inlet pipe 77, a secondary flash third stop valve 78, a secondary flash water vapor compressor 79, a secondary flash exhaust pipe 80, a secondary flash fourth stop valve 81, a secondary flash exhaust bypass pipe 82, a secondary flash fifth stop valve 83, a secondary flash water supply pump 84, a secondary flash water supply pipe 85, a secondary flash sixth stop valve 86 and a secondary flash drain pipe 87.

[0063] In this embodiment, the primary flash tank 55 is connected to a secondary flash circulation pump 71, and a secondary flash first shut-off valve 70 is provided on the connecting pipeline. The secondary flash circulation pump 71 is connected to a secondary flash pressure reducing valve 73 via a secondary flash circulation pipe 72. The secondary flash pressure reducing valve 73 is connected to the secondary flash tank 75, for delivering water to be flashed to the secondary flash tank 75. A secondary flash second shut-off valve 74 is provided on the connecting pipeline between the secondary flash pressure reducing valve 73 and the secondary flash tank 75. A secondary flash atomizing nozzle 76 is provided within the secondary flash tank 75 for flashing the water.

[0064] In this embodiment, the secondary flash tank 75 is connected to the secondary flash water vapor compressor 79 via a secondary flash air inlet pipe 77, supplying water vapor to be compressed to the secondary flash water vapor compressor 79. A secondary flash air inlet pipe 77 is provided with a secondary flash third shut-off valve 78. A secondary flash water supply pump 84 can have its water inlet connected to the secondary flash water supply pipe 85 and its water outlet connected to the secondary flash water vapor compressor 79, replenishing water to the secondary flash water vapor compressor 79. A secondary flash fifth shut-off valve 83 can be provided on the pipeline connecting the secondary flash water supply pump 84 to the secondary flash water vapor compressor 79.

[0065] In this embodiment, the secondary flash tank 75 is further in fluid communication with a secondary flash exhaust pipe 80 via a secondary flash exhaust bypass pipe 82. A secondary flash fourth shut-off valve 81 may be provided on the secondary flash exhaust bypass pipe 82. In this embodiment, the secondary flash tank 75 is further connected to a secondary flash drain pipe 87 for draining water from the secondary flash tank 75. A secondary flash sixth shut-off valve 86 may be provided on the secondary flash drain pipe 87.

[0066] In a specific embodiment, the heat pump recovery system includes a circulating water tank 10, a secondary flash tank 75, a sixth stop valve 90, a return water circulation pump 91, a first return water pipe 92, a seventh stop valve 93, a second return water pipe 94, an eighth stop valve 95, a ninth stop valve 96, a first return water bypass pipe 97, a heat pump evaporation pipe 98, a heat pump compressor 99, a heat pump exhaust pipe 100, a heat pump condenser 101, a high-temperature water outlet pipe 102, a heat pump return liquid pipe 103, a heat pump expansion valve 104, a heat pump liquid inlet pipe 105 and a heat pump evaporator 106.

[0067] In this embodiment, the secondary flash tank 75 is connected to a return water circulation pump 91, which is connected to a heat pump evaporator 106 via a first return water pipe 92. The heat pump evaporator 106 is connected to the circulating water tank 10 via a second return water pipe 94. A sixth shut-off valve 90 is provided on the connecting pipe between the secondary flash tank 75 and the return water circulation pump 91, a seventh shut-off valve 93 is provided on the first return water pipe 92, and an eighth shut-off valve 95 is provided on the second return water pipe 94.

[0068] In this embodiment, the return water circulation pump 91 can also be connected to the heat pump condenser 101 via the first return water pipe 92 and the first return water bypass pipe 97, and the first return water bypass pipe 97 can be provided with a ninth shut-off valve 96. The heat pump condenser 101 can be connected to the three-stage flash pressure reducing valve 73 described below via the high-temperature water outlet pipe 102. In this embodiment, the heat pump evaporator 106 can also be connected to the heat pump compressor 99 via the heat pump evaporation pipe 98. The heat pump compressor 99 is connected to the heat pump condenser 101 via the heat pump exhaust pipe 100. The heat pump condenser 101 is connected to the heat pump expansion valve 104 via the heat pump return liquid pipe 103. The heat pump expansion valve 104 is connected to the heat pump evaporator 106 via the heat pump liquid inlet pipe 105, forming a fluid flow loop.

[0069] In a specific embodiment, the three-stage flash steam supply system includes a first return pipe 92, a high-temperature water outlet pipe 102, a three-stage flash pressure reducing valve 113, a three-stage flash first stop valve 114, a three-stage flash tank 115, a three-stage flash atomizing nozzle 116, a three-stage flash air inlet pipe 117, a three-stage flash second stop valve 118, a three-stage flash water vapor compressor 119, a three-stage flash exhaust pipe 120, a three-stage flash third stop valve 121, a three-stage flash exhaust bypass pipe 122, a three-stage flash fourth stop valve 123, a three-stage flash water supply pump 124, a three-stage flash water supply pipe 125, a three-stage flash fifth stop valve 126, a three-stage flash drain pipe 127, a three-stage flash sixth stop valve 128, a three-stage flash water return pipe 129, a three-stage flash circulation pump 130 and a three-stage flash seventh stop valve 131.

[0070] In this embodiment, the water inlet of the three-stage flash pressure reducing valve 113 is connected to the return water circulation pump 91 via the first return water pipe 92, and the water outlet is connected to the three-stage flash tank 115, for delivering water to be flashed to the three-stage flash tank 115. A three-stage flash first stop valve 114 is installed in the pipeline connecting the three-stage flash pressure reducing valve 113 and the three-stage flash tank 115. A three-stage flash atomizing nozzle 116 is installed in the three-stage flash tank 115 for flashing the water.

[0071] In this embodiment, the third-stage flash tank 115 is connected to a third-stage flash water vapor compressor 119 via a third-stage flash air inlet pipe 117, supplying water vapor to be compressed to the third-stage flash water vapor compressor 119. A third-stage flash second shut-off valve 118 is provided on the third-stage flash air inlet pipe 117. A third-stage flash water supply pump 124 can have its water inlet connected to the third-stage flash water supply pipe 125 and its water outlet connected to the third-stage flash water vapor compressor 119, replenishing water to the third-stage flash water vapor compressor 119. A third-stage flash fourth shut-off valve 123 can be provided on the pipeline connecting the third-stage flash water supply pump 124 to the third-stage flash water vapor compressor 119.

[0072] In this embodiment, the third-stage flash tank 115 is further connected to the third-stage flash exhaust pipe 120 via a third-stage flash exhaust bypass pipe 122. A third-stage flash third shut-off valve 121 may be provided on the third-stage flash exhaust bypass pipe 122. In this embodiment, the third-stage flash tank 115 is further connected to a third-stage flash drain pipe 127 for draining water from the third-stage flash tank 115. A fifth third-stage flash shut-off valve 126 may be provided on the third-stage flash drain pipe 127.

[0073] In a preferred embodiment, the tertiary flash tank 115 is further connected to a tertiary flash circulation pump 130 via a tertiary flash return pipe 129, and a tertiary flash sixth shut-off valve 128 may be provided on the tertiary flash return pipe 129. The outlet of the tertiary flash circulation pump 130 may be in fluid communication with the first return pipe 92 via a tertiary flash circulation pump outlet pipe 132, and further connected to the heat pump evaporator 106. A tertiary flash seventh shut-off valve 131 may be provided on the tertiary flash circulation pump outlet pipe 132.

[0074] Next, the working method of the steam cogeneration system described in this article will be described in detail.

[0075] In one embodiment, the water working medium in the hot water storage tank 43 can be heated to 120°C at night by means of an air source heat pump to achieve the first stage of heat storage. Then, the hot water temperature is heated to above 200°C by valley electricity heating to store high-temperature and high-pressure hot water to achieve the second stage of heat storage. When used during the day, two-stage flash evaporation is first performed and coupled with corresponding water vapor compressors to supply water vapor of different pressure and temperature levels such as high-temperature and high-pressure steam, medium-temperature and medium-pressure steam, and low-temperature and low-pressure steam to meet different working conditions. At the same time, the water working medium after the two-stage flash evaporation can also further recover heat in depth through the heat pump recovery system to supply high-temperature and high-pressure hot water, and combine the flash evaporation of the three-stage flash evaporation steam supply system and couple the corresponding water vapor compressor to once again achieve the supply of high-temperature and high-pressure steam. In this embodiment, the two-stage flash evaporation refers to the flash evaporation in the first-stage flash evaporation steam supply system and the second-stage flash evaporation steam supply system.

[0076] In another embodiment, at night, when electricity prices are low and the electricity load is sufficient, the heat pump and valley power heat storage system first operate. The second shut-off valve 13 and the fourth shut-off valve 42 are opened, and the low-temperature water working medium stored in the circulating water tank 10 during the day is transported to the hot water storage tank 43 through the circulating water tank outlet pipe 14, the thermal storage water supply pump 40, and the thermal storage water supply pump outlet pipe 41. The second shut-off valve 13 is then closed, the third shut-off valve 39 is opened, and some water working medium is added to the hot water storage tank 43 to ensure that the hot water storage tank 43 stores sufficient water working medium. The water working medium stored in the hot water storage tank 43 is then heated. First, the air source heat pump operates, and the working medium flows through the thermal storage heat pump expansion valve 36, the thermal storage heat pump evaporator 38, the thermal storage heat pump compressor 32, and the thermal storage heat pump condenser 34, forming a complete cycle. Heat is extracted from the air in the heat storage heat pump evaporator 38, condensed and released in the heat storage heat pump condenser 34, heating the water working medium in the hot water storage tank 43 to approximately 120°C, completing the first stage of heating. The valley heating system then operates, heating the water working medium in the hot water storage tank 43 via the electric heater 44 to a temperature above 200°C and a corresponding pressure above 1.555 MPa. The water working medium in the hot water storage tank 43 is kept mostly in liquid form, with only a small amount remaining in vapor form, achieving valley heating using the high-temperature, high-pressure water working medium.

[0077] During peak hours during the day, when steam is needed, the first-stage flash steam supply system is activated. The first-stage flash stop valve 50 and the second-stage flash stop valve 54 are opened, and the opening of the first-stage flash pressure reducing valve 53 is adjusted. The high-temperature and high-pressure water medium above 200°C stored in the heat storage tank 43 is fed through the first-stage flash atomizing nozzle 56 via the first-stage flash circulation pump 51 and the first-stage flash circulation pipe 52 and sent into the first-stage flash tank 55. The pressure is reduced and flash evaporated in the first-stage flash tank 55, generating high-temperature and high-pressure steam at a temperature of approximately 180°C and a pressure of 1.003 MPa, and high-temperature and high-pressure saturated water at a temperature of 180°C and a pressure of 1.003 MPa. Depending on user needs, the generated high-temperature, high-pressure steam with a temperature of approximately 180°C and a pressure of approximately 1.003 MPa can be supplied in two ways: the first is to close the third stop valve 58 of the first-stage flash evaporation and open the fourth stop valve 61 of the first-stage flash evaporation. The generated high-temperature, high-pressure steam with a temperature of approximately 180°C and a pressure of approximately 1.003 MPa can be directly supplied to the user through the first-stage flash evaporation inlet pipe 57, the first-stage flash evaporation exhaust bypass pipe 62, and the first-stage flash evaporation exhaust pipe 60. The second is to open the third stop valve 58 of the first-stage flash evaporation and close the fourth stop valve 61 of the first-stage flash evaporation. The generated high-temperature, high-pressure steam with a temperature of approximately 180°C and a pressure of approximately 1.003 MPa can be supplied to the user through the first-stage flash evaporation inlet pipe 57, compressed by the first-stage flash evaporation water vapor compressor 59, and then supplied to the user through the first-stage flash evaporation exhaust pipe 60, thereby meeting the steam heating demand above 200°C. During the compression process of the first-stage flash vapor compressor 59, it is also necessary to open the first-stage flash fifth stop valve 63, and external make-up water flows into the compression chamber of the first-stage flash vapor compressor 59 through the first-stage flash vapor make-up water pipe 65 and the first-stage flash vapor make-up water pump 64 to reduce the superheat of the compression process and ensure the safety and efficiency of the compression process.

[0078] After the primary flash steam supply system is operational, the secondary flash steam supply system begins operation. The secondary flash first shutoff valve 70 and the secondary flash second shutoff valve 74 are opened, and the opening of the secondary flash pressure reducing valve 73 is adjusted. The high-temperature, high-pressure water (180°C) stored in the primary flash tank 55 is pumped through the secondary flash atomizing nozzle 76 via the secondary flash circulation pump 71 and secondary flash circulation pipe 72 into the secondary flash tank 75. Within the secondary flash tank 75, the water undergoes pressure reduction and flash evaporation, producing steam at a temperature of approximately 120-160°C and a pressure of approximately 0.199-0.618 MPa, and saturated water at a temperature of approximately 120-160°C and a pressure of approximately 0.199-0.618 MPa. Depending on user needs, the steam at a temperature of approximately 120-160°C and a pressure of approximately 0.199-0.618 MPa can be supplied in two ways. The first method is to close the secondary flash evaporation third stop valve 78 and open the secondary flash evaporation fourth stop valve 81. The steam generated with a temperature of 120-160°C and a pressure of approximately 0.199-0.618 MPa can be directly supplied to users through the secondary flash evaporation inlet pipe 77, the secondary flash evaporation exhaust bypass pipe 82 and the secondary flash evaporation exhaust pipe 80. The second method is to open the secondary flash evaporation third stop valve 78 and close the secondary flash evaporation fourth stop valve 81. The steam generated with a temperature of 120-160°C and a pressure of about 0.199-0.618MPa passes through the secondary flash evaporation inlet pipe 77 and is compressed by the secondary flash evaporation water vapor compressor 79. The temperature and pressure are further increased to 180°C and above 1.003Mpa through the secondary flash evaporation exhaust pipe 80 to be supplied to users for use, meeting the steam heat demand above 180°C. During the compression process of the secondary flash evaporation water vapor compressor 79, it is also necessary to open the secondary flash evaporation fifth stop valve 83, and the external make-up water flows into the compression chamber of the secondary flash evaporation water vapor compressor 79 through the secondary flash evaporation water supply pump 84 and the secondary flash evaporation water supply pipe 85 to reduce the superheat of the compression process and ensure the safety and efficiency of the compression process.

[0079] After the secondary flash steam supply system is operational, the heat pump recovery system can select two modes, depending on the steam volume demanded by the user: heat pump recovery system inoperative mode or heat pump heating followed by high-temperature hot water supply. In the first mode, the heat pump recovery system inoperative mode opens the sixth, seventh, and eighth stop valves 90, 93, and 95, and closes the ninth stop valve 96. Saturated water near 120°C in the secondary flash tank 75 flows through the return water circulation pump 91, the first and second return water pipes 92, 94, and the heat pump evaporator 106, directly into the circulating water tank 10 for storage. In the second mode, heat pump heating followed by high-temperature hot water supply mode, the sixth, seventh, eighth, and ninth stop valves 90, 93, 95, and 96 are opened, and the openings of the seventh and ninth stop valves 93, 96 are adjusted to appropriately match the flow rate of water near 120°C flowing through the heat pump evaporator 106 and the heat pump condenser 101. The heat pump recovery system then operates. The heat pump working fluid absorbs the heat of saturated water at approximately 120°C in the heat pump evaporator 106, evaporates, flows through the heat pump evaporator pipe 98, and, after being compressed and heated and pressurized, flows through the heat pump exhaust pipe 100 into the heat pump condenser 101. Inside the heat pump condenser 101, it condenses and heats the saturated water at approximately 120°C flowing through the heat pump condenser 101, raising its temperature to above 120°C before being supplied to the three-stage flash steam supply system through the high-temperature water outlet pipe 102. The condensed heat pump working fluid flows through the heat pump return pipe 103, passes through the heat pump expansion valve 104, and, after cooling and reducing its pressure, flows through the heat pump inlet pipe 105 into the heat pump evaporator 106, completing a complete cycle. After the saturated water at approximately 120°C flowing through the heat pump condenser 101 releases heat in the heat pump condenser 101, the heat is further recovered and the temperature is further reduced to approximately 80°C. It flows into the circulating water tank 10 through the second return pipe 94 and is stored.

[0080] In the heat pump heating and high-temperature hot water supply mode, the heat pump recovery system begins operation. The three-stage flash steam supply system begins operation, opening the three-stage flash first stop valve 114 and adjusting the opening of the three-stage flash pressure reducing valve 113. The high-temperature water working medium with a temperature above 120°C from the heat pump condenser 101 flows through the high-temperature water outlet pipe 102 and passes through the three-stage flash atomizing nozzle 116 into the three-stage flash tank 115. The pressure is reduced and flash evaporated in the three-stage flash tank 115, producing low-temperature, low-pressure steam with a temperature of approximately 120°C and a pressure of approximately 0.101 MPa, and low-temperature saturated water with a temperature of approximately 120°C and a pressure of approximately 0.101 MPa. Depending on user needs, the generated low-temperature, low-pressure steam with a temperature of approximately 120°C and a pressure of approximately 0.101 MPa can be supplied in two ways: the first is to close the third-stage flash second stop valve 118 and open the third-stage flash third stop valve 121. The generated low-temperature, low-pressure steam with a temperature of approximately 120°C and a pressure of approximately 0.101 MPa can be directly supplied to the user through the third-stage flash inlet pipe 117, the third-stage flash exhaust bypass pipe 122, and the third-stage flash exhaust pipe 120. The second is to open the third-stage flash second stop valve 118 and close the third-stage flash third stop valve 121. The generated low-temperature, low-pressure steam with a temperature of approximately 120°C and a pressure of approximately 0.101 MPa can be supplied to the user through the third-stage flash inlet pipe 117, compressed by the third-stage flash water vapor compressor 119, and then supplied to the user through the third-stage flash exhaust pipe 120, thereby meeting the steam heating demand above 120°C. During the compression process of the three-stage flash vapor compressor 119, the third-stage flash fourth shut-off valve 123 needs to be opened, and external make-up water flows into the compression chamber of the three-stage flash vapor compressor 119 through the third-stage flash make-up water pump 124 and the third-stage flash make-up water pipe 125 to reduce the superheat during the compression process and ensure the safety and efficiency of the compression process. After the three-stage flash steam supply system is in operation, the third-stage flash sixth shut-off valve 128 and the third-stage flash seventh shut-off valve 131 are opened, and the low-temperature saturated water at a temperature of 120°C and a pressure of 0.101 MPa in the third-stage flash tank 115 flows through the third-stage flash return pipe 129 and the third-stage flash circulation pump 130 into the first return pipe 92, where it mixes with the water working medium from the second-stage flash tank 75.

[0081] During the day, the entire steam cogeneration system operates continuously to ensure the supply of steam during the day. The high-temperature and high-pressure water medium above 200°C stored in the heat storage tank 43 is continuously consumed to produce steam of different temperatures and pressures to meet the needs of different users. The low-temperature water medium stored in the circulating water tank 10 is also continuously increased. After the daytime heating is completed, the high-temperature and high-pressure water medium above 200°C stored in the heat storage tank 43 is consumed, and a large amount of reflux low-temperature water medium is also stored in the circulating water tank 10. At night, the second stop valve 13 and the fourth stop valve 42 are opened, and the circulating water tank outlet pipe 14 and the heat storage water pump 40 are used to return the steam. The low-temperature water working medium in the circulating water tank 10 is returned to the hot water storage tank 43 through the heat storage water supply pipe 41, and then the third stop valve 39 is opened to replenish the consumed water working medium through the heat storage water supply pump 40 and the heat storage water supply pipe 47, and is heated during the off-peak hours at night through the heat pump heat storage system and the off-peak heat storage system. In this way, when the system is running during the day, the returned low-temperature water working medium is stored in the circulating water tank 10 and will not mix with the high-temperature water working medium in the hot water storage tank 43, thereby not lowering the temperature of the water working medium in the hot water storage tank 43, thereby ensuring the high temperature of the water working medium in the hot water storage tank 43 and sufficient gas production, making the entire system more efficient.

[0082] The above description of the embodiments is intended to facilitate understanding and application of the present application by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without expending any creative effort. Therefore, the present application is not limited to the embodiments described herein, and improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A steam cogeneration system, characterized in that: The steam cogeneration system comprises: A heat pump and valley electricity heat storage system is used to heat a low-temperature water working medium into a high-temperature water working medium using an air source and valley electricity. The heat pump and valley electricity heat storage system includes a circulating water tank, a heat storage water supply pump, a hot water storage tank, a heat storage heat pump expansion valve, a heat storage heat pump evaporator, and a heat storage heat pump compressor. A heat storage heat pump condenser and an electric heater are provided in the hot water storage tank. The circulating water tank, the heat storage water supply pump, and the hot water storage tank are fluidically connected in sequence. The heat storage heat pump condenser, the heat storage heat pump expansion valve, the heat storage heat pump evaporator, and the heat storage heat pump compressor form a fluid flow loop. A first-stage flash steam supply system, comprising a heat storage tank, a first-stage flash circulation pump, a first-stage flash pressure reducing valve, a first-stage flash tank, a first-stage flash water vapor compressor, a first-stage flash exhaust pipe, a first-stage flash water supply pump, and a first-stage flash water supply pipe, wherein a first-stage flash tank is provided with a first-stage flash atomizing nozzle, wherein the heat storage tank, the first-stage flash circulation pump, the first-stage flash pressure reducing valve, and the first-stage flash tank are fluidly connected in sequence, wherein the first-stage flash tank and the first-stage flash water vapor compressor are fluidly connected for conveying water vapor to be compressed to the first-stage flash water vapor compressor, wherein the first-stage flash water supply pipe, the first-stage flash water supply pump, and the first-stage flash water vapor compressor are fluidly connected in sequence for conveying external make-up water to the first-stage flash water vapor compressor, wherein the first-stage flash exhaust pipe is fluidly connected to the first-stage flash water vapor compressor for conveying compressed water vapor; A two-stage flash steam supply system, comprising a first-stage flash tank, a second-stage flash circulation pump, a second-stage flash pressure reducing valve, a second-stage flash tank, a second-stage flash water vapor compressor, a second-stage flash exhaust pipe, a second-stage flash water supply pump, and a second-stage flash water supply pipe, wherein the first-stage flash tank, the second-stage flash circulation pump, the second-stage flash pressure reducing valve, and the second-stage flash tank are fluidically connected in sequence, wherein the second-stage flash tank and the second-stage flash water vapor compressor are fluidically connected for conveying water vapor to be compressed to the second-stage flash water vapor compressor, wherein the second-stage flash water supply pipe, the second-stage flash water supply pump, and the second-stage flash water vapor compressor are fluidically connected in sequence for conveying external make-up water to the second-stage flash water vapor compressor, wherein the second-stage flash exhaust pipe is fluidly connected to the second-stage flash water vapor compressor for conveying compressed water vapor; Wherein, the secondary flash tank, the return water circulation pump and the circulating water tank are fluidically connected in sequence.

2. The steam cogeneration system according to claim 1, wherein: The steam cogeneration system further comprises: A heat pump recovery system, comprising a secondary flash tank, a return water circulation pump, a circulating water tank, a heat pump evaporator, a heat pump expansion valve, a heat pump condenser, a heat pump compressor, and a first return water bypass pipe, wherein the secondary flash tank, the return water circulation pump, the heat pump evaporator, and the circulating water tank are fluidically connected in sequence, wherein the heat pump evaporator, the heat pump expansion valve, the heat pump condenser, and the heat pump compressor form a fluid loop, wherein the return water circulation pump is fluidically connected to the heat pump condenser via the first return water bypass pipe; A three-stage flash steam supply system comprises a secondary flash tank, a return water circulation pump, a first return water pipe, a third-stage flash pressure reducing valve, a third-stage flash tank, a third-stage flash water vapor compressor, a third-stage flash exhaust pipe, a third-stage flash water supply pump and a third-stage flash water supply pipe, wherein the secondary flash tank, the return water circulation pump, the first return water pipe, the third-stage flash pressure reducing valve and the third-stage flash tank are fluidically connected in sequence, wherein the third-stage flash tank and the third-stage flash water vapor compressor are fluidically connected for conveying water vapor to be compressed to the third-stage flash water vapor compressor, wherein the third-stage flash water supply pipe, the third-stage flash water supply pump and the third-stage flash water vapor compressor are fluidically connected in sequence for conveying external make-up water to the third-stage flash water vapor compressor, wherein the third-stage flash exhaust pipe is fluidly connected to the third-stage flash water vapor compressor for conveying compressed water vapor.

3. The steam cogeneration system according to claim 1 or 2, characterized in that: The first-stage flash steam supply system includes a first-stage flash exhaust bypass pipe, one end of which is in fluid communication with the first-stage flash tank and the other end of which is in fluid communication with the first-stage flash exhaust pipe; The secondary flash steam supply system includes a secondary flash exhaust bypass pipe, one end of which is in fluid communication with the secondary flash tank, and the other end of which is in fluid communication with the secondary flash exhaust pipe.

4. The steam cogeneration system according to claim 1 or 2, characterized in that: The primary flash steam supply system includes a primary flash drain pipe for draining water from the primary flash tank; The secondary flash steam supply system includes a secondary flash drain pipe for draining water from the secondary flash tank.

5. The steam cogeneration system according to claim 2, wherein: The three-stage flash steam supply system includes a three-stage flash exhaust bypass pipe, one end of which is in fluid communication with the three-stage flash tank and the other end of which is in fluid communication with the three-stage flash exhaust pipe; The three-stage flash steam supply system includes a three-stage flash drain pipe for draining water from the three-stage flash tank.

6. The steam cogeneration system according to claim 2, wherein: The three-stage flash steam supply system further includes a three-stage flash circulation pump, and the three-stage flash tank, the three-stage flash circulation pump and the heat pump evaporator are fluidically connected in sequence.

7. The steam cogeneration system according to claim 1 or 2, characterized in that: The heat pump and valley power heat storage system includes a heat storage water supply pump outlet pipe for delivering external supplementary water to the heat storage tank; The circulating water tank includes a circulating water tank drain pipe for draining water from the circulating water tank; The hot water storage tank comprises a hot water storage tank drain pipe for draining water from the hot water storage tank.

8. The method for operating the steam cogeneration system according to claim 1, wherein: The method comprises the following steps: S1: At night, the water working medium in the heat storage tank of the heat pump and valley electricity heat storage system is heated by an air source and valley electricity to obtain a first high-temperature water working medium; S2: When steam supply is required, the first high-temperature water working medium is flash evaporated by the first flash steam supply system and the second flash steam supply system to obtain high-temperature and high-pressure or medium-temperature and medium-pressure steam; Wherein, in step S1, the low-temperature water working medium from the circulating water tank is not mixed with the high-temperature water working medium in the hot water storage tank.

9. The method for operating the steam cogeneration system according to claim 2, wherein: The method comprises the following steps: S1: At night, the water working medium in the heat storage tank of the heat pump and valley electricity heat storage system is heated by an air source and valley electricity to obtain a first high-temperature water working medium; S2: When steam supply is required, the first high-temperature water working medium is flash evaporated by the first flash steam supply system and the second flash steam supply system to obtain high-temperature and high-pressure or medium-temperature and medium-pressure steam; S3: flash evaporating the second high-temperature water working medium from the heat pump condenser using a three-stage flash steam supply system to obtain low-temperature and low-pressure water vapor; Wherein, in step S1, the low-temperature water working medium from the circulating water tank is not mixed with the high-temperature water working medium in the hot water storage tank.

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