A steam generation system coupling pressurized water heat storage and phase change heat storage

Abstract

The present invention provides a steam generation system that couples pressurized water heat storage and phase change heat storage, which can not only improve the heat supply capacity of pressurized water heat storage, but also make full use of the advantages of high heat storage density of phase change heat storage, simplify the system configuration, reduce costs, and extend the service life of materials. Pipeline 1 is connected to the pressurized water heat storage tank, and a shut-off valve is installed on Pipeline 1; Pipeline 2 is connected to the pressurized water heat storage tank, and a shut-off valve and a pressure regulating valve are installed on Pipeline 2; the pressurized water heat storage tank is connected to a circulation water pump, and the circulation water pump is connected to a water jet steam ejector through Pipeline 9, and a shut-off valve is installed on Pipeline 9; the pressurized water heat storage tank is connected to the phase change heat storage device through Pipeline 4, and a shut-off valve is installed on Pipeline 4; the temperature mixing device is connected to Pipeline 4 through Pipeline 5, and a regulating valve is installed on Pipeline 5; the temperature mixing device is connected to the water jet steam ejector through Pipeline 7, and a shut-off valve is provided on Pipeline 7; Pipeline 3 is connected to Pipeline 7, and a shut-off valve and a pressure regulating valve are installed on Pipeline 3.

Description

Technical Field

[0001] The present invention relates to a steam generation system that couples pressurized water heat storage and phase change heat storage. Background Art

[0002] China vigorously develops new energy technologies such as photovoltaic and wind power. At the same time, energy storage, as the "buffer pool" for new energy utilization, is crucial for improving the utilization rate of new energy. As an important technical means, the heat storage and steam supply technology can connect green electricity or valley electricity on one hand and industrial steam users on the other hand, which is of great significance for green electricity consumption and peak shaving and valley filling of the power system.

[0003] As an important raw material for industrial production, industrial steam has a large market demand. However, due to the diversity of user needs and the uncertainty of application regions, the existing fixed pipe network heating method can no longer meet the needs of some users, and seriously restricts the development of social economy. The application of mobile heat storage and steam supply technology can not only meet the needs of enterprises, but also play a flexible role in energy storage peak shaving of the power grid or power plant, which is of great significance for the promotion of energy storage technology on the user side.

[0004] The most crucial requirement for mobile heating technology is that the system is simple, the energy storage density is high, and the equipment volume is small and convenient for transportation. Currently, the mainstream application technologies are pressurized water heat storage and phase change heat storage. The two technologies are as follows:

[0005] The pressurized water heat storage technology uses water as the heat storage medium. For external heat supply, only pressure reduction and flashing are required to complete external steam supply, and the system is simple. The main application scenario is that during the low heat load period, the extracted steam of the steam turbine is used to heat water and store it in a pressurized and pressure-bearing hot water storage tank. Then, when heat is needed, the storage tank is transported to the user side by vehicle and the heat is released in the form of steam for users to use. The main problems of this technology are: (1) When releasing heat, only the steam generated by the flashing of the pressure-bearing hot water storage tank itself is used, and the amount of steam is small, usually only about 10-20% of the total water storage capacity of the pressure-bearing hot water storage tank, and the external heat supply capacity is limited. (2) In order to increase the steam generation amount, it is necessary to increase the pressure of the pressure-bearing hot water storage tank, enlarge the water storage volume, or use electric heating assistance. This not only increases the system cost, but also puts forward higher requirements for the safety and reliability of mobile transportation.

[0006] As a conventional technical means, the phase change heat storage technology has the characteristics of high energy storage density, high thermal conductivity, and stable heat output. The main energy storage materials include inorganic salt phase change materials (fluorides, chlorides, nitrates, sulfates, etc.), metal phase change materials (aluminum, aluminum-based alloys, zinc-based alloys, magnesium-based alloys, germanium-based alloys, nickel-based alloys, etc.), silicon, etc. However, at present, there are few applications that directly generate steam using phase change heat storage. The main problems of this technology are: (1) Directly using water to exchange heat with the phase change energy storage material causes a large thermal shock to the heat storage container and shortens the service life of the material. (2) Adopting an indirect heat exchange method, using an intermediate heat exchange medium to exchange heat with the phase change material, and then the intermediate heat exchange medium exchanges heat with water to generate steam. The system is complex and costly, and the heat storage efficiency is low, which is not conducive to energy conservation and emission reduction.

[0007] Generally speaking, in the field of mobile heating, the technical deficiencies of single pressurized water heat storage or phase change heat storage are difficult to meet the market demand for industrial steam. Summary of the Invention

[0008] The purpose of the present invention is to overcome the above deficiencies existing in the prior art, and provide a steam generation system that couples pressurized water heat storage and phase change heat storage with a reasonable structural design. It can not only improve the heating capacity of pressurized water heat storage, but also make full use of the advantage of high heat storage density of phase change heat storage to realize steam generation by one-time heat exchange, simplify the system configuration, reduce the cost, and extend the service life of the material.

[0009] The technical solution adopted by the present invention to solve the above problems is: A steam generation system that couples pressurized water heat storage and phase change heat storage, including a pressurized heat storage water tank and a phase change heat storage device, characterized in that: it further includes a circulating water pump, a water jet steam ejector, a mixing heater, a temperature mixing device, pipeline one, pipeline two, pipeline three, pipeline four, pipeline five, pipeline six, pipeline seven, pipeline eight and pipeline nine; a shut-off valve two is installed on the steam inlet of the phase change heat storage device, and a shut-off valve three is installed on the steam outlet; pipeline one is connected to the water inlet of the pressurized heat storage water tank, and a shut-off valve five is installed on pipeline one; pipeline two is connected to the steam outlet of the pressurized heat storage water tank, and a shut-off valve seven and a pressure regulating valve one are installed on pipeline two; the water outlet of the pressurized heat storage water tank is connected to the water inlet of the circulating water pump through pipeline eight, and the water outlet of the circulating water pump is connected to the water inlet of the water jet steam ejector through pipeline nine, and a shut-off valve six is installed on pipeline nine; the mixing heater is arranged in the water side space of the pressurized heat storage water tank, and its inlet is connected to the outlet of the water jet steam ejector; the steam outlet of the pressurized heat storage water tank is connected to the steam inlet of the phase change heat storage device through pipeline four, and a shut-off valve one is installed on pipeline four; one inlet of the temperature mixing device is connected to the steam outlet of the phase change heat storage device through pipeline six, and the other inlet is connected to pipeline four through pipeline five, and a regulating valve is installed on pipeline five; the outlet of the temperature mixing device is connected to the steam inlet of the water jet steam ejector through pipeline seven, and a shut-off valve four is arranged on pipeline seven; pipeline three is connected to pipeline seven, and a shut-off valve eight and a pressure regulating valve two are installed on pipeline three.

[0010] In the steam side space of the pressure-bearing hot water storage tank of the present invention, a first thermometer, a first pressure gauge and a safety valve are provided.

[0011] In the water side space of the pressure-bearing hot water storage tank of the present invention, a liquid level gauge is provided.

[0012] In the phase change heat storage device of the present invention, a phase change energy storage material is provided.

[0013] A first flow meter is installed on pipeline two of the present invention.

[0014] A second flow meter is installed on pipeline three of the present invention.

[0015] The phase change heat storage device of the present invention is provided with an auxiliary electric heater.

[0016] On pipeline seven of the present invention, a third flow meter, a second thermometer, a second pressure gauge and a check valve are provided.

[0017] A fourth flow meter is installed on pipeline nine of the present invention.

[0018] Connecting flanges are provided on pipeline four and pipeline six of the present invention.

[0019] The circulating water pump of the present invention is arranged below the pressure-bearing hot water storage tank.

[0020] Compared with the prior art, the present invention has the following advantages and effects:

[0021] (1) By using phase change heat storage to circularly heat the saturated steam of the pressurized water heat storage, continuous and stable steam supply to the outside by the pressure-bearing hot water storage tank can be realized, and the steam evaporation ratio can reach more than 80%.

[0022] (2) Industrial steam can be generated externally by using phase change energy storage for one-time heat exchange. Moreover, by using water steam as the heat exchange medium, the thermal shock to the container of the phase change material, especially the high-temperature phase change material, is relatively small, and the service life of the material is prolonged.

[0023] (3) By using the hot water in the pressure-bearing hot water storage tank as the driving medium, there is no need to introduce an external driving medium, the power of the circulating pump is relatively low, and the system efficiency is high.

[0024] (4) The combined supply of saturated and superheated steam can be realized, and various steam parameter requirements can be met.

[0025] (5) The system is simple and reliable, modular assembly can be realized, and there are various commercial application modes. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of an embodiment of the present invention. Detailed Embodiments

[0027] The present invention will be further described in detail below with reference to the accompanying drawings and through embodiments. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0028] The embodiments of the present invention include a pressure-bearing hot water storage tank 1, a phase change heat storage device 3, a circulation water pump 2, a water jet steam ejector 4, a mixing heater 5, a temperature mixing device 27, pipeline one L1, pipeline two L2, pipeline three L3, pipeline four L4, pipeline five L5, pipeline six L6, pipeline seven L7, pipeline eight L8, and pipeline nine L9.

[0029] The pressure-bearing hot water storage tank 1 is used to store pressurized saturated water, has the function of pressure water heat storage, and at the same time has the function of a steam generator, and supplies saturated or slightly superheated steam externally, and the steam pressure range is 0.2 - 10 MPa. The hot water source of the pressure-bearing hot water storage tank 1 comes from external customer heat storage hot water, pressurized condensate recovery hot water, or an electric boiler + pressure water heat storage for power plant peak-valley electricity consumption.

[0030] A thermometer T1, a pressure gauge P1, and a safety valve 11 are provided in the steam side space of the pressure-bearing hot water storage tank 1, and a liquid level gauge 8 is provided in the water side space of the pressure-bearing hot water storage tank 1.

[0031] The phase change heat storage device 3 is provided with a phase change energy storage material 6, has the function of phase change heat storage, and at the same time has the function of a steam superheater, and can directly provide superheated steam externally according to requirements or continuously generate saturated steam through internal circulation. Its heat source comes from valley electricity, green electricity heating, or high-temperature waste heat recovery. The phase change energy storage material 6 should be selected as a suitable phase change material according to the steam parameter requirements. The phase change heat storage device 3 is provided with an auxiliary electric heater 31. A shut-off valve two SV2 is installed at the steam inlet of the phase change heat storage device 3, and a shut-off valve three SV3 is installed at the steam outlet of the phase change heat storage device 3.

[0032] Pipeline one L1 is connected to the water inlet of the pressure-bearing hot water storage tank 1. A shut-off valve five SV5 is installed on pipeline one L1.

[0033] Pipeline two L2 is connected to the steam outlet of the pressure-bearing hot water storage tank 1. A shut-off valve seven SV7, a pressure regulating valve one RV1, and a flow meter one F1 are installed on pipeline two L2. Pipeline two L2 is used to supply industrial saturated steam externally.

[0034] The water outlet of the pressure-bearing hot water storage tank 1 is connected to the water inlet of the circulation water pump 2 through pipeline eight L8, and the water outlet of the circulation water pump 2 is connected to the water inlet of the water jet steam ejector 4 through pipeline nine L9. A shut-off valve six SV6 and a flow meter four F4 are installed on pipeline nine L9. The circulation water pump 2 is used to provide a certain pressure to circulate the saturated water. Through the water jet steam ejector 4, according to Bernoulli's equation: z + p / γ + υ 2 / 2g = C, that is, increasing the water flow velocity can reduce the pressure inside the water pipe, thereby achieving the suction of the superheated steam from the phase change heat storage device 3. The circulating water pump 2 needs to be arranged below the pressure-bearing hot water storage tank 1, and the bottom of the pressure-bearing hot water storage tank 1 should be at least 0.5 m higher than the water inlet of the pump. The circulating water pump 2 is driven by a variable-frequency motor or a speed-regulating steam-driven pump, and the pump head can be adjusted according to requirements.

[0035] The mixing heater 5 is arranged in the water side space of the pressure-bearing hot water storage tank 1, and its inlet is connected to the outlet of the water jet steam ejector 4, bringing the mixed water vapor into the pressure-bearing hot water storage tank 1 and realizing the function of uniform heating.

[0036] The steam outlet of the pressure-bearing hot water storage tank 1 is connected to the steam inlet of the phase change heat storage device 3 through the pipeline four L4. A shut-off valve one SV1 is installed on the pipeline four L4.

[0037] One inlet of the temperature mixing device 27 is connected to the steam outlet of the phase change heat storage device 3 through the pipeline six L6, and the other inlet is connected to the pipeline four L4 through the pipeline five L5. A regulating valve RV3 is installed on the pipeline five L5; the outlet of the temperature mixing device 27 is connected to the steam inlet of the water jet steam ejector 4 through the pipeline seven L7. A flow meter three F3, a thermometer two T2, a pressure gauge two P2, a check valve 26 and a shut-off valve four SV4 are arranged on the pipeline seven L7.

[0038] The pipeline three L3 is connected to the pipeline seven L7; a shut-off valve eight SV8, a pressure regulating valve two RV2 and a flow meter two F2 are installed on the pipeline three L3. The pipeline three L3 supplies industrial superheated steam.

[0039] Connecting flanges 30 are arranged on the pipeline four L4 and the pipeline six L6. The combined splitting and expansion can be achieved through the connecting flanges 30, which also means that the two heat storage units can store heat independently from different scenarios according to requirements, with a flexible and variable heat storage application mode.

[0040] The present invention has the following working modes:

[0041] 1. Heat storage mode.

[0042] When the pressure-bearing hot water storage tank 1 stores heat, the shut-off valve five SV5 is opened, and the shut-off valve one SV1, the shut-off valve six SV6, the shut-off valve seven SV7, and the shut-off valve four SV4 are closed. The hot water is input into the closed and empty pressure-bearing hot water storage tank 1 through the pipeline one L1.

[0043] When the phase change heat storage device 3 stores heat, the phase change energy storage material 6 is melted by industrial waste heat or electricity, so that the heat energy or electrical energy is stored as the sensible heat of temperature rise and the latent heat of phase change of the phase change energy storage material 6, thereby achieving the heat storage effect.

[0044] 2. Heat release mode.

[0045] During the exothermic stage, the system can supply steam with various parameters such as saturated, slightly superheated, and highly superheated steam to the outside. When saturated steam needs to be supplied to the outside, in the initial stage, shut-off valve 1 (SV1), shut-off valve 5 (SV5), shut-off valve 6 (SV6), and shut-off valve 4 (SV4) are closed, and shut-off valve 7 (SV7) is opened to supply saturated steam or slightly superheated steam to the outside. The steam pressure and flow rate are automatically or manually controlled by pressure regulating valve 1 (RV1) according to the signal parameters feedback of flowmeter 1 (F1) behind the valve. After the flashing stage ends, when the pressure of the pressurized hot water storage tank 1 drops to the set value, according to the signal feedback of the pressure measuring point of the pressurized hot water storage tank 1, shut-off valve 1 (SV1), shut-off valve 2 (SV2), shut-off valve 3 (SV3), shut-off valve 6 (SV6), and shut-off valve 4 (SV4) are opened, and the phase change heat storage device 3 is started. The saturated steam enters the phase change heat storage device 3 to absorb heat, and is mixed with the hot water in the pressurized hot water storage tank 1 through the water jet steam ejector 4 and the mixing heater 5 to achieve the effect of circulating heating, thereby increasing the pressure of the pressurized hot water storage tank 1 to maintain its steam supply capacity to the outside. This stage is defined as the coupled operation stage. When superheated steam needs to be supplied to the outside, by opening shut-off valve 8 (SV8), the superheated steam is output to the outside through pipeline 3 (L3).

[0046] 3. Variable operating condition mode.

[0047] The variable operating condition mode is divided into two modes: the side storage and side discharge mode and the mode of adjusting the output power. For the former, by replenishing water to the pressurized hot water storage tank 1 on-site and simultaneously performing auxiliary electric heating on the phase change heat storage device 3, the heating duration can be flexibly adjusted. For the latter, by changing the frequency of the circulating water pump 2, and then changing the circulating heating amount of the phase change heat storage device 3, the flexible regulation of the external heating power can be achieved.

[0048] The present invention has the following control logic.

[0049] (1) Control of the heat storage completion degree: When the liquid level of the pressurized hot water storage tank 1 reaches the design value, shut-off valve 5 (SV5) is closed through the liquid level signal interlock. When the wall temperature of the phase change heat storage device 3 reaches the design value, the electric heater is cut off or the waste heat heating path is closed through the pressure signal interlock.

[0050] (2) Control of the pressure of the pressurized hot water storage tank 1: The maintenance of the pressure of the pressurized hot water storage tank 1 directly affects the stability of the external heating parameters. Therefore, it is crucial to effectively control the pressure of the pressurized hot water storage tank 1. When the pressure in the steam side space of the pressurized hot water storage tank 1 drops to the set value, pipeline 5 (L5) is opened, and the superheated steam enters the inside of the pressurized hot water storage tank 1 through the circulating water pump 2 and the water jet steam ejector 4 to achieve the reboiling effect, so as to increase the pressure of the pressurized hot water storage tank 1 to meet the operation requirements.

[0051] (3)Regulation and control of the external steam supply flow: In the initial stage, since there is no external heat source for heating, the external output flow is directly controlled by pressure regulating valve 1 (RV1) and pressure regulating valve 2 (RV2). In the coupled operation stage, flowmeter 1 (F1) and flowmeter 2 (F2) monitor the flow changes in real time. The flow changes will cause the pressure change in the pressurized hot water storage tank 1. Through the feedback control of the pressure signal, the frequency modulation of the circulating pump 2 is adjusted, and then the suction volume of the heating steam in pipeline 7 (L7) is changed, so as to realize the control of the heating quantity.

[0052] (4)Control of the steam temperature at the outlet of the phase change heat storage device 3: Since the heat release of the phase change heat storage device 3 includes two processes: sensible heat release and latent heat release, the latent heat release process is a constant temperature and steady state heat release process, and the sensible heat release process is a variable temperature and unsteady state heat release process. Therefore, pipeline 5 (L5) is set up. By adjusting the opening of the regulating valve RV3 to control the bypass flow, the "hot and cold" steam mixing is carried out by using the temperature mixer 27, so that the steam temperature at the outlet of the phase change heat storage device 3 can be stably controlled, and then the stable and reliable system control can be realized.

[0053] An example of the application scheme is described.

[0054] Example: There are a large number of industrial heat users in an industrial park. There is a coal-fired cogeneration heat source point in the park, which provides industrial steam to heat-using enterprises through the park's heating pipe network. At the same time, in response to the national new energy policy, the park is equipped with distributed photovoltaics and wind power.

[0055] Existing problems: The heat load in the park fluctuates greatly day and night. The frequent deep load regulation of the heat source point unit leads to low unit operation efficiency. At the same time, the frequent start-stop opportunities will accelerate the aging and damage of the equipment. Moreover, there are newly relocated enterprises far away from the regional heating pipe network or the steam pressure parameters supplied by the regional heating pipe network cannot meet the enterprise's requirements. At the same time, distributed photovoltaics are restricted by weather conditions and cannot be used as a continuous and stable power source, resulting in serious "light and wind abandonment" phenomena. Furthermore, according to policy requirements, thermal power units will also be gradually incorporated into the power grid peak shaving and frequency modulation. At this time, it is required that thermal power units must achieve "thermal power decoupling".

[0056] Solution: Adopt the coupled pressurized water heat storage and phase change heat storage solution. Step 1: During the low load period of the power grid, increase the use of plant steam to heat demineralized water and store it in the pressure-bearing hot water storage tank 1 of the fixed or mobile pressurized water heat storage, thereby improving the unit load rate and further enhancing the unit operation efficiency. This step realizes the pressurized water heat storage process. Step 2: When the thermal power unit operates at low load and there is curtailment of distributed photovoltaic and wind power, use electricity to heat the phase change heat storage device 3, which helps with "thermal power decoupling" and reduces the waste of energy from "curtailment of photovoltaic and wind power". This step realizes the metal phase change heat storage process. Step 3: Connect the pressure-bearing hot water storage tank 1 and the phase change heat storage device 3 on the side of the heat-consuming enterprise to generate steam locally to meet the development needs of the enterprise. This step realizes the heat release process of the heat storage system. According to different application scenarios, the above three steps can adopt the decentralized mobile energy storage heat release mode, the integrated mobile energy storage heat release mode or the fixed energy storage heat release mode.

[0057] In addition, it should be noted that for the specific embodiments described in this specification, the shapes, names of the components, etc. can be different. The above content described in this specification is only an example of the structure of the present invention. Any equivalent changes or simple changes made according to the structure, features and principles described in the inventive concept of the present invention are included in the protection scope of the present invention. Those skilled in the technical field to which the present invention pertains can make various modifications, supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the structure of the present invention or exceed the scope defined by this claim, they should fall within the protection scope of the present invention.

Claims

1. A steam generation system coupling pressurized water heat storage and phase change heat storage, comprising a pressure-bearing hot water storage tank and a phase change heat storage device, characterized in that: It also includes a circulating water pump, a jet air ejector, a mixing heater, a temperature mixing tank, pipeline one, pipeline two, pipeline three, pipeline four, pipeline five, pipeline six, pipeline seven, pipeline eight and pipeline nine; a shut-off valve two is installed at the steam inlet of the phase change heat storage device, and a shut-off valve three is installed at the steam outlet; pipeline one is connected to the water inlet of the pressure-bearing hot water storage tank, and a shut-off valve five is installed on pipeline one; pipeline two is connected to the steam outlet of the pressure-bearing hot water storage tank, and a shut-off valve seven and a pressure regulating valve one are installed on pipeline two; the water outlet of the pressure-bearing hot water storage tank is connected to the water inlet of the circulating water pump through pipeline eight, and the water outlet of the circulating water pump is connected to the water inlet of the jet air ejector through pipeline nine, and a shut-off valve six is installed on pipeline nine; the mixing heater is arranged in the water side space of the pressure-bearing hot water storage tank, and its inlet is connected to the outlet of the jet air ejector; the steam outlet of the pressure-bearing hot water storage tank is connected to the steam inlet of the phase change heat storage device through pipeline four, and a shut-off valve one is installed on pipeline four; one inlet of the temperature mixing tank is connected to the steam outlet of the phase change heat storage device through pipeline six, and the other inlet is connected to pipeline four through pipeline five, and a regulating valve is installed on pipeline five; the outlet of the temperature mixing tank is connected to the steam inlet of the jet air ejector through pipeline seven, and a shut-off valve four is arranged on pipeline seven; pipeline three is connected to pipeline seven, and a shut-off valve eight and a pressure regulating valve two are installed on pipeline three.

2. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: A thermometer one, a pressure gauge one and a safety valve are arranged in the steam side space of the pressure-bearing hot water storage tank.

3. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: A liquid level gauge is arranged in the water side space of the pressure-bearing hot water storage tank.

4. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: The phase change heat storage device is internally provided with a phase change energy storage material.

5. The steam generation system integrating pressurized water heat storage and phase change heat storage according to claim 1, characterized in that: A flowmeter one is installed on pipeline two, and a flowmeter two is installed on pipeline three.

6. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: The phase change heat storage device is provided with an auxiliary electric heater.

7. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: A flowmeter three, a thermometer two, a pressure gauge two and a check valve are arranged on pipeline seven.

8. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: A flowmeter four is installed on pipeline nine.

9. The steam generation system coupling pressurized water heat storage and phase change heat storage according to claim 1, wherein: Connecting flanges are arranged on pipeline four and pipeline six.

10. The steam generation system for coupling pressurized water heat storage and phase change heat storage according to claim 1, characterized in that: The circulating water pump is arranged below the pressure-bearing hot water storage tank.

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