A multi-stage coupled steam thermal storage spherical tank

Abstract

This utility model discloses a multi-stage coupled steam thermal storage spherical tank. The tank body has a main steam delivery pipe connected to an inlet pipe and an internal steam header. The steam header is fixedly connected to upper and lower steam distribution pipes via connecting pipes, and the steam pipes are interconnected. Each steam distribution pipe includes an inner pipe and an outer pipe, which are fixed together by fins. A high-temperature phase change material is arranged inside the inner pipe at the center of the steam distribution pipe. Steam nozzles are provided on the outer wall of the steam distribution pipe. The steam distribution pipes are supported by brackets at the bottom, and low-temperature phase change material is arranged inside the brackets. This utility model, through the design of a double-layer steam distribution pipe and a hollow support, rationally arranges phase change energy storage materials with different melting points, aiming to achieve tiered storage and release of sensible and latent heat, improve the thermal density of the spherical tank, and address the problem of poor heat transfer performance during phase change energy storage. Simultaneously, it reduces the tank volume, saves costs, and meets the needs of more application scenarios.

Description

Technical Field

[0001] This utility model relates to the field of heat storage technology, specifically to a multi-stage coupled steam heat storage spherical tank. Background Technology

[0002] A steam accumulator is a thermal device that stores the heat energy of steam. Steam accumulator technology stores the heat energy of surplus steam as saturated water and releases it when steam demand increases. It is an important means of achieving efficient energy utilization and load regulation in industrial fields. Used in steam supply systems with large fluctuations in heat load, it can balance the steam supply to stabilize the boiler's operating load and transform intermittent fluctuating steam loads into stable steam loads for recovery and reuse. By using steam accumulators to recover and reuse waste steam from boilers, the problem of resource waste can be greatly improved, and energy utilization efficiency can be increased.

[0003] Traditional steam accumulators use steam as a source to store thermal energy in the form of high-pressure saturated water by utilizing the heat storage capacity of the water inside the container. They have advantages such as readily available materials, simple principles, mature technology, low cost, and long service life. However, due to disadvantages such as low energy density, short storage time, and excessively large scale of the energy storage system, they have certain limitations in large-scale applications.

[0004] In recent years, spherical steam accumulators have gradually become a research hotspot due to their advantages such as compact structure, small footprint, and good pressure resistance, which have a wider range of applications compared to horizontal and vertical accumulators. However, there is still room for improvement in terms of uniform steam distribution and enhanced condensation. They also have disadvantages such as low energy storage density, short energy storage time, and excessively large scale of energy storage systems. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a novel sensible-latent heat multi-stage coupled steam thermal storage spherical tank, also known as a sensible-latent heat multi-stage coupled steam thermal storage spherical tank system. This system aims to improve the energy storage density of the spherical tank, reduce its volume, save costs, and meet the needs of more application scenarios. This invention utilizes a double-layer steam distribution pipeline and hollow support design to rationally arrange phase change energy storage materials with different melting points, achieving tiered storage and release of sensible and latent heat. This maximizes the heat storage density of the spherical tank and improves the poor heat transfer performance during phase change energy storage by increasing the heat-receiving area of ​​the phase change material.

[0006] To achieve the above objectives, this utility model designs a multi-stage coupled steam thermal storage spherical tank. A steam outlet pipe and an inlet pipe are installed at the top of the tank body. An external main steam input pipe is connected to the inlet pipe, and an external main steam output pipe is connected to the outlet pipe via flanges. Inside the tank body, a main steam delivery pipe is connected to the inlet pipe and to an internal steam header. The steam header is fixedly connected to an upper steam distribution pipe and a lower steam distribution pipe via connecting pipes, and the steam pipes communicate with each other. The steam distribution pipe includes an inner pipe and an outer pipe, which are fixed together by fins. A phase change material is arranged inside the inner pipe at the center of the steam distribution pipe, and a steam channel exists between the inner and outer pipes. The fins also enhance the heat exchange effect. The steam distribution pipe is generally located below the water medium surface for easy heat exchange. Steam nozzles are provided on the outer wall of the steam distribution pipe. The upper and lower steam distribution pipes are supported by brackets at their bottoms and welded together, ensuring no interference between the upper and lower steam distribution pipes and the brackets.

[0007] Furthermore, the steam header is fixedly connected to the upper steam distribution pipe and the lower steam distribution pipe via connecting pipes, including welding.

[0008] Furthermore, the upper steam distribution pipe consists of n1 annular pipes, and the lower steam distribution pipe consists of n2 annular pipes, where n1 > n2. The radial spacing of the annular pipes is uniform, and the annular pipes include double-layer concentric pipes. This design mainly considers the uniform steam distribution and sufficient heat exchange in the lower half of the spherical tank, as well as the physical location of the upper and lower layers.

[0009] Furthermore, n1 = 5, n2 = 3.

[0010] Furthermore, the support includes a hollow support, which is fixedly connected to the inner wall of the spherical tank by welding.

[0011] Furthermore, the support includes a horizontal support and a vertical support.

[0012] Furthermore, the upper steam distribution pipe and the lower steam distribution pipe are both evenly arranged inside the spherical tank in a manner perpendicular to the central axis of the main steam conveying pipeline.

[0013] Furthermore, the steam distribution pipe is arranged in segments, and the segments are located at the gaps where the steam distribution pipe and the support alternately contact.

[0014] Furthermore, a phase change material is also arranged inside the support.

[0015] Furthermore, the interior of the central inner tube of the steam distribution pipe is lined with a high-temperature (i.e., high-melting-point) phase change material, and the interior of the support is lined with a low-temperature (relatively low-melting-point) phase change material.

[0016] The advantages and beneficial effects of this utility model are as follows:

[0017] 1) Through the synergistic effect of high-melting-point (central tube) and low-melting-point (support tube) phase change materials, cascaded storage and release of sensible and latent heat are achieved. High-temperature and high-pressure steam is used for primary heat storage, while phase change materials are used for subsequent heat storage. In particular, in the preferred embodiment, high-melting-point materials are responsible for heat storage in the high-temperature segment, while low-melting-point materials play a role in the medium and low-temperature segments, covering a wider temperature range. The overall heat storage density is significantly improved compared to a single sensible heat or single-stage latent heat system.

[0018] 2) The isothermal properties of phase change materials, combined with a multi-stage coupling design, effectively buffer temperature fluctuations during the charging / discharging process, making them particularly suitable for industrial processes with stringent requirements for heat source stability.

[0019] 3) The concentric tube steam jet design allows high-temperature steam to directly contact the central phase change tube, enhancing initial heat exchange; the low-melting-point material inside the support absorbs residual heat simultaneously, avoiding local overheating.

[0020] 4) The phase change material is encapsulated in an independent pipe to reduce the risk of chemical corrosion with steam; the hollow support has both structural support and heat storage functions and can disperse mechanical stress.

[0021] 5) Multi-stage phase change materials cover a wide temperature range of melting points (customizable according to requirements), which can not only cope with fluctuations in steam parameters, but also achieve precise control of the heat charge and release rate by adjusting the ratio of materials at each stage. They are particularly suitable for intermittent heat source scenarios such as renewable energy coupling and industrial waste heat recovery. Attached Figure Description

[0022] Figure 1 This is a partial sectional view of the thermal storage spherical tank of this utility model in the vertical direction;

[0023] Figure 2 This is a horizontal mid-section view of the spherical tank;

[0024] Figure 3 This is a cross-sectional view of a ring-shaped pipe.

[0025] Marked in the image:

[0026] 1. Spherical tank body; 2. Steam outlet pipe; 3. Steam inlet pipe; 4. Main steam delivery pipe; 5. Steam header pipe; 6. Connecting pipe; 7. Upper steam distribution pipe; 8. High-temperature phase change material; 9. Support frame; 10. Low-temperature phase change material; 11. Lower steam distribution pipe; 12. Fins; 13. Steam injection port. Detailed Implementation

[0027] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solution of this utility model and should not be construed as limiting the scope of protection of this utility model.

[0028] Example 1:

[0029] Considering that the principle of latent heat storage is to store heat by absorbing or releasing heat when a substance undergoes a phase change, it has advantages such as high energy storage density and compact device, and is considered to be one of the most promising heat storage technologies at present. By combining steam heat storage with phase change heat storage, the volume of the heat storage tank can be effectively reduced and the energy storage density can be increased.

[0030] like Figures 1-3 As shown, this utility model designs a multi-stage coupled steam thermal storage spherical tank. A steam outlet pipe 2 and an inlet pipe 3 are installed at the top of the spherical tank body 1. An external main steam input pipe is connected to the inlet pipe 3, and an external main steam output pipe is connected to the outlet pipe 2 via flanges. Inside the spherical tank body 1, a main steam delivery pipe 4 is installed, connected to the inlet pipe 3 and to an internal steam header pipe 5. The steam header pipe 5 is fixedly connected to an upper steam distribution pipe 7 and a lower steam distribution pipe 11 via connecting pipes 6, and the steam pipes are interconnected. The steam distribution pipe includes an inner pipe and an outer pipe, which are fixed together by fins 12. High temperature... The high-melting-point phase change material 8 is arranged inside the inner tube of the steam distribution pipe. The inner tube and the outer tube form a steam channel. The fins also enhance the heat exchange effect. The steam distribution pipe is generally located below the water medium liquid level to facilitate heat exchange. Steam nozzles 13 are provided on the outer tube wall of the steam distribution pipe. The upper steam distribution pipe 7 and the lower steam distribution pipe 11 are supported by brackets 9 and welded to each other. The upper and lower steam distribution pipes and the brackets do not interfere with each other. The low-temperature (melting-point) phase change material 10 is arranged inside the bracket 9 to realize three-stage heat storage of high-temperature phase change material, low-temperature phase change material and water.

[0031] When heat storage is required: Initially, the spherical tank is pre-filled with about 60% liquid water. During steam charging, external high-pressure steam enters through the steam inlet pipe 3 and then passes through the main steam delivery pipe 4, the steam header pipe 5, and the connecting pipe 6 to enter the upper steam distribution pipe 7 and the lower steam distribution pipe 11. The high-temperature steam first exchanges heat with the high-temperature phase change material 8 in the steam distribution pipe. The phase change material changes from a solid state to a molten state. Then, the steam is injected into the water through the steam injection port 13. The liquid water in the spherical tank and the low-temperature phase change material 10 inside the support 9 absorb the residual heat of the steam. As the charging time increases, the pressure and temperature inside the spherical tank gradually rise to the target level, and the charging stops.

[0032] When heat release is required: Open steam outlet pipe 2, and the high-temperature and high-pressure liquid water inside the spherical tank undergoes flash evaporation to generate high-temperature and high-pressure steam. As the temperature inside the spherical tank decreases, the two phase change materials 8 and 10 inside the spherical tank begin to release heat, changing from a molten state to a solid state, until the pressure inside the spherical tank drops to the target pressure, at which point heat release stops.

[0033] This embodiment takes saturated steam with a maximum heat storage pressure of 2.5 MPa and a target pressure of 0.6 MPa as an example, designing a spherical tank with a volume of 500 m³. For the phase change materials, a high-temperature phase change material is a mixed nitrate salt with a melting point of 190°C, and a low-temperature phase change material is a mixed nitrate salt with a melting point of 170°C. The total steam storage capacity of the spherical tank reaches 55 tons, reducing the volume by more than 10% compared to conventional water-based thermal storage spherical tanks, effectively reducing the footprint and manufacturing cost. Simultaneously, the use of double-layer concentric pipes in the steam distribution pipe, hollow supports, and both high- and low-temperature phase change materials improves the heat storage effect and capacity. Due to the natural phase change process characteristics of the materials, temperature stability during the charging and discharging process is ensured, guaranteeing a constant temperature and pressure output of high-grade steam.

[0034] Preferably, the steam header 5 is fixedly connected to the upper steam distribution pipe 7 and the lower steam distribution pipe 11 via the connecting pipe 6, including by welding.

[0035] Preferably, the upper steam distribution pipe 7 consists of n1 annular pipes, and the lower steam distribution pipe 11 consists of n2 annular pipes, where n1>n2. The radial spacing of the annular pipes is uniform, and the annular pipes include double-layer concentric pipes. This design mainly considers the uniform steam distribution and sufficient heat exchange in the lower half of the spherical tank, as well as the physical location of the upper and lower layers.

[0036] Preferably, in this embodiment, n1=5, n2=3, the inner diameter of the double-layer concentric pipe is 65mm, the outer diameter is 108mm, the distance between adjacent steam distribution pipes is 630mm, and the distance between the upper and lower layers is 1200mm.

[0037] Preferably, the support 9 includes a hollow support, which may be a square tube or a round tube, and the hollow support is fixedly connected to the inner wall of the spherical tank by welding.

[0038] Preferably, the support includes horizontal and vertical supports to ensure the installation stability of the steam distribution pipe and sufficient and uniform heat exchange. Figure 1 The outer tube of the vertical low-temperature (melting point) phase change material 10 shown is the vertical support. Two vertical supports and two horizontal supports are illustrated. In this embodiment, the spherical tank actually has two layers of horizontal supports corresponding to the upper and lower steam distribution pipes. Each layer of horizontal supports extends radially from the innermost annular double-layer concentric pipe to the inner wall of the spherical tank. Figure 2 As shown, if the steam header 5 is regarded as a support, the angle between adjacent horizontal supports is 30 degrees, and 5 horizontal supports are arranged on both sides of the steam header 5. Each horizontal support is provided with at least 2 vertical supports to the inner wall of the spherical tank, which ensures both the support effect and the heat transfer distribution and heat transfer effect of the low temperature phase change material.

[0039] Preferably, the upper steam distribution pipe (7) and the lower steam distribution pipe (11) are evenly arranged in the spherical tank in a manner perpendicular to the central axis of the main steam conveying pipe (4).

[0040] Preferred, such as Figure 3 As shown, the steam distribution pipe in this embodiment is arranged in sections, with each section having 3 steam injection ports, one at the bottom center and one on each side. The opening shape includes square holes, strip holes or circular holes. In this embodiment, the circular hole nozzle has an included angle of 60 degrees. The section is located at the gap where the steam distribution pipe and the support alternately contact.

[0041] Example 2:

[0042] The difference from Example 1 is that this example uses saturated steam with a maximum heat storage pressure of 2.5 MPa and a target pressure of 0.6 MPa in the spherical tank, a tank volume of 1000 m³, and a total steam storage capacity of 100 t. The design incorporates n1 = 6, n2 = 4, an inner pipe diameter of 70 mm, an outer pipe diameter of 120 mm, a spacing of 750 mm between adjacent steam distribution pipes, and a spacing of 1500 mm between upper and lower layers. Each segment of the steam distribution pipe is evenly arranged with at least two sets of circular holes, each set including one at the bottom center and one on each side. Each horizontal support is equipped with three vertical supports extending to the inner wall of the spherical tank.

[0043] Example 3:

[0044] The difference from Example 1 is that this example only arranges high-temperature phase change material inside the inner tube of the central steam distribution pipe to achieve two-stage heat storage of phase change material and high-temperature and high-pressure steam.

[0045] Example 4:

[0046] The difference from Example 3 is that the same phase change material is arranged inside the inner tube of the central tube of the steam distribution pipe and inside the support 9 at the same time, which can better realize the two-stage heat storage of phase change material and high temperature and high pressure steam.

[0047] The above description is only a partial and relatively comprehensive embodiment of a multi-stage coupled steam thermal storage spherical tank system of this utility model. In fact, the steam distribution pipe can also be designed as three layers: upper, middle and lower. Three horizontal supports can be arranged on both sides of the steam main pipe 5. Other heat exchange and support designs can also be adapted. There can be a variety of fin shapes (straight, spiral, etc.) and connection methods (single-piece connection, group connection of inner and outer pipes). These combinations or preferred solutions should also be considered within the protection scope of this utility model, and will not be listed one by one here.

Claims

1. A multi-stage coupled steam thermal storage spherical tank, wherein a steam outlet pipe (2) and an inlet pipe (3) are provided at the top of the spherical tank body (1), characterized in that, The main steam conveying pipe (4) is provided inside the spherical tank body (1) and connected to the air inlet pipe (3), and connected to the internal steam header (5). The steam header (5) is fixedly connected to the upper steam distribution pipe (7) and the lower steam distribution pipe (11) through the connecting pipe (6), and the steam pipes are connected. The steam distribution pipe includes an inner pipe and an outer pipe. The inner and outer pipes are fixed together by fins (12). The phase change material is arranged inside the inner pipe in the center of the steam distribution pipe. A steam nozzle (13) is opened on the outer pipe wall of the steam distribution pipe. The upper steam distribution pipe (7) and the lower steam distribution pipe (11) are supported by brackets (9) below.

2. The multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The steam header (5) is fixedly connected to the upper steam distribution pipe (7) and the lower steam distribution pipe (11) respectively through the connecting pipe (6), including welding.

3. The multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The upper steam distribution pipe (7) consists of n1 annular pipes, and the lower steam distribution pipe (11) consists of n2 annular pipes, where n1> n2. The radial spacing of the annular pipes is uniform, and the annular pipes include double-layer concentric pipes.

4. A multi-stage coupled steam thermal storage spherical tank according to claim 3, characterized in that, n1 = 5, n2 = 3.

5. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The support (9) includes a hollow support, which is fixedly connected to the inner wall of the spherical tank by welding.

6. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The support system includes horizontal supports and vertical supports.

7. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The upper steam distribution pipe (7) and the lower steam distribution pipe (11) are both evenly arranged in the spherical tank in a manner perpendicular to the central axis of the main steam conveying pipe (4).

8. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, The steam distribution pipe is arranged in sections, and the sections are located at the gaps where the steam distribution pipe and the support alternately contact.

9. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, Phase change material is also arranged inside the support (9).

10. A multi-stage coupled steam thermal storage spherical tank according to claim 1, characterized in that, High-temperature phase change material (8) is arranged inside the central inner tube of the steam distribution pipe, and low-temperature phase change material (10) is arranged inside the support (9).

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