A transversely arranged parallel type double-tank supercritical carbon dioxide

Abstract

The application provides a transversely-arranged parallel double-tank body of supercritical carbon dioxide, which comprises a hot storage tank and a cold storage tank arranged in parallel, the hot storage tank and the cold storage tank each comprise a tank body, an inlet pipe is arranged in the inner cavity of the tank body, one end of the inlet pipe is connected with an inlet of the tank body, the other end of the inlet pipe is sequentially connected with a transition pipe, a tapered pipe and an outlet pipe, the outlet pipe is connected with an outlet of the tank body, and a plurality of circular holes are arranged on the transition pipe along the axial direction of the transition pipe; the application adopts the design of a drainage pipe combined by the inlet pipe, the transition pipe, the tapered pipe and the outlet pipe in the tank body, and strong relative motion is avoided, so that the pressure loss is reduced.

Description

Technical Field

[0001] This invention belongs to the field of supercritical working fluid storage tanks, specifically relating to a horizontally arranged parallel double tank for supercritical carbon dioxide. Background Technology

[0002] With the continuous growth of global energy demand and the pursuit of sustainable development goals, improving energy efficiency has become a focus of attention for governments, research institutions, and industries worldwide. Against this backdrop, the supercritical carbon dioxide Brayton cycle, as a novel power generation technology, has attracted widespread attention due to its high efficiency, economic benefits, and environmental friendliness. Compared to traditional Brayton cycle technology, the supercritical CO2 cycle has significant advantages. One key factor is the high fluid density of supercritical carbon dioxide, which allows researchers to design compact turbines and compressors. The compactness of the power generation system not only effectively reduces material manufacturing costs but also meets the demands of modern industry for miniaturization and lightweighting. Furthermore, the supercritical carbon dioxide power cycle possesses many other advantages, such as high-efficiency operation, low noise and vibration, and emission-free closed-loop operation. Its application power range is wide, ranging from 100 kW to 100 MW, and it can adapt to different types of heat sources, thus being considered a revolutionary next-generation power technology.

[0003] As a key component, the storage tank plays a crucial role in the supercritical carbon dioxide power generation cycle. Given the specific temperature and pressure requirements of the supercritical carbon dioxide power cycle, the storage tank stores and supplies carbon dioxide as the working fluid throughout the entire cycle system, ensuring the normal operation of the entire system and its key core power components. In particular, it provides adjustable dynamic response throughout the entire process of startup, acceleration, high-efficiency operation, and shutdown, playing a stabilizing role.

[0004] In the development of supercritical carbon dioxide power cycles, near-critical point operation has proven to have many advantages. However, the thermophysical properties of carbon dioxide working fluid near the critical point are extremely unstable, and its density and other physical quantities are extremely sensitive to temperature and pressure changes. Therefore, precise temperature and pressure control through storage tanks and valves is a necessary prerequisite for the development of this technology. Furthermore, the carbon dioxide working fluid in the storage tank undergoes significant phase transitions and stratification due to temperature and pressure fluctuations. This reduces the heating and insulation effects of the tank, negatively impacting the safety of the tank itself and the entire system. Additionally, during the inflow and outflow of the carbon dioxide working fluid, it interacts with the existing stationary working fluid, creating highly complex flow phenomena such as vortex structures and secondary flows, resulting in significant pressure losses and reduced cycle efficiency. This is also an area that needs improvement in supercritical carbon dioxide storage tanks. Summary of the Invention

[0005] The purpose of this invention is to provide a horizontally arranged parallel double tank for supercritical carbon dioxide, which solves the problem that existing supercritical carbon dioxide storage tanks are prone to significant phase changes and stratification due to temperature and pressure fluctuations, resulting in poor tank safety.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The present invention provides a horizontally parallel dual-tank supercritical carbon dioxide storage tank, comprising a hot storage tank and a cold storage tank arranged horizontally in parallel. Both the hot storage tank and the cold storage tank include a tank body. An inlet pipe is arranged in the inner cavity of the tank body. One end of the inlet pipe is connected to the inlet of the tank body, and the other end is connected in sequence to a transition pipe, a converging pipe and an outlet pipe. The outlet pipe is connected to the outlet of the tank body.

[0008] Preferably, the transition pipe has several small circular holes along its axial direction.

[0009] Preferably, the transition pipe has a spiral structure.

[0010] Preferably, the inlets of the hot storage tank and the cold storage tank are connected in parallel via a first tee pipe, and a one-way valve is provided on the first tee pipe.

[0011] Preferably, the outlets of the hot storage tank and the cold storage tank are connected in parallel via a second three-way pipe, and a three-way regulating valve is provided on the second three-way pipe.

[0012] Preferably, a thermometer and a pressure gauge are provided on the second three-way pipe.

[0013] Preferably, a safety valve is installed at the inlet of both the hot storage tank and the cold storage tank.

[0014] Preferably, the hot storage tank and the cold storage tank are arranged side by side on a fixed base.

[0015] Preferably, the tapering pipe is a hollow frustum-shaped structure, with its small end connected to the outlet pipe and its large end connected to the transition pipe.

[0016] Preferably, an electric heat tracing cable is arranged on the outer wall of the heat storage tank.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention provides a horizontally arranged parallel double-tank system for supercritical carbon dioxide. The design addresses numerous problems arising from the unique characteristics of supercritical carbon dioxide as a working medium in a supercritical state, and is fundamentally different from traditional liquid or gas storage tanks. The specific differences are as follows:

[0019] Traditional storage tanks, due to the different densities of gaseous and liquid states, are arranged vertically and designed with either top-inlet / bottom-outlet or bottom-inlet / top-outlet configurations based on density to achieve optimal storage efficiency. However, due to the unique characteristics of the supercritical state, its physical properties are extremely unstable, and its density is drastically affected by temperature. Furthermore, since engineering practices typically involve operation near the critical point, changes in temperature and pressure can easily cause the working fluid to undergo a phase transition from the supercritical state to either the gaseous or liquid state.

[0020] This invention adopts a horizontally positioned tank for the reasons mentioned above. Due to the unstable physical properties of the supercritical state, the supercritical state and the gas-liquid two-phase coupling and mixing will occur when the fluid flows in and out of the tank. This flowing working fluid and the original stationary working fluid inside will generate complex relative motion, forming a vortex structure and secondary flow, resulting in highly complex flow phenomena and significant pressure loss, which leads to a decrease in circulation efficiency. This invention adopts a diversion pipe design in the tank, which is a combination of an inlet pipe, a transition pipe, a converging pipe and an outlet pipe, to avoid strong relative motion and thus reduce pressure loss.

[0021] Because the thermophysical properties of the aforementioned supercritical state are extremely sensitive, phase transitions and stratification are prone to occur within the storage tank. Furthermore, if this phase transition occurs within the drainage pipe, it is highly likely to cause blockage. This invention innovatively designs a transition pipe with small holes in its wall, allowing for material exchange between the fluid in the pipe and the fluid in the storage tank. Simultaneously, the flowing working fluid within the pipe also achieves a certain degree of mixing and stirring of the working fluid in the storage tank, thereby effectively mitigating adverse phenomena such as stratification and even phase transitions caused by temperature sensitivity. Attached Figure Description

[0022] Figure 1 This is a top view of the device of the present invention;

[0023] Figure 2 This is a diagram of the internal structure of the storage tank of the present invention;

[0024] Among them: 1-Hot storage tank, 2-Cold storage tank, 3-One-way valve, 4-Safety valve, 5-Three-way regulating valve, 6-Thermometer, 7-Pressure gauge, 8-Fixed base, 9-Electric heating tape, 10-Tank inlet, 11-Inlet pipe, 12-Transition pipe, 13-Gradual narrowing pipe, 14-Outlet pipe. Detailed Implementation

[0025] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods have been omitted so as not to obscure the description of this application with unnecessary detail.

[0026] It should be understood that, when used in this application specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or a collection thereof.

[0027] It should also be understood that the term “and / or” as used in this application specification and the appended claims means any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0028] As used in this application specification and the appended claims, the term "if" may be interpreted, depending on the context, as "when," "once," "in response to determination," or "in response to detection." Similarly, the phrase "if determined" or "if detected [the described condition or event]" may be interpreted, depending on the context, as meaning "once determined," "in response to determination," "once detected [the described condition or event]," or "in response to detection [the described condition or event]."

[0029] Furthermore, in the description of this application and the appended claims, the terms "first," "second," "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0030] References to "one embodiment" or "some embodiments" as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized.

[0031] Example 1

[0032] This embodiment provides a horizontally parallel dual-tank system for supercritical carbon dioxide, including a hot storage tank 1 and a cold storage tank 2, wherein the hot storage tank 1 and the cold storage tank 2 are horizontally arranged side by side on a fixed base 8.

[0033] The inlets of the hot storage tank 1 and the cold storage tank 2 are connected by a first tee pipe, and the outlets of the hot storage tank 1 and the cold storage tank 2 are connected by a second tee pipe.

[0034] The second three-way pipe is equipped with a three-way regulating valve 5, a thermometer 6 and a pressure gauge 7.

[0035] Both the hot storage tank 1 and the cold storage tank 2 are equipped with a safety valve 4 at their inlets to ensure the safety of the equipment in case of an accident.

[0036] A one-way valve 3 is installed on the first three-way pipe. The one-way valve is located at the inlet of the whole set of devices to ensure that the working fluid flows in one direction in the circulation after the device is connected to the system. After the working fluid flows through the one-way valve, it enters the hot storage tank and the cold storage tank through the three-way structure respectively.

[0037] The hot storage tank 1 and the cold storage tank 2 have the same structure, both including a tank body. An inlet pipe 11, a transition pipe 12, and a converging pipe 13 are arranged in the inner cavity of the tank body. One end of the inlet pipe 11 is connected to the tank body inlet 10, and the other end of the inlet pipe 11 is connected to the transition pipe 12. The free end of the transition pipe 12 is connected to the large end of the converging pipe 13, and the small end of the converging pipe 13 is connected to the outlet pipe 14. The outlet pipe 14 is located at the outlet of the tank body and is connected to the tank body outlet.

[0038] The transition pipe 12 has a spiral structure.

[0039] The heat storage tank 1 is equipped with an electric heating cable 9, which can heat and keep the working fluid inside the heat storage tank warm; the inlet pipe and outlet pipe of the working fluid are respectively connected to both sides of the tank.

[0040] The working process of this embodiment:

[0041] When the working fluid enters the device, it flows through the one-way valve 3 into the first three-way pipe, and then splits into two paths, flowing into the hot storage tank 1 and the cold storage tank 2 respectively. After entering the tanks, it first flows through the inlet pipe 11 and then into the transition pipe 12. In the transition pipe 12, the working fluid that has undergone a phase change exchanges substances with the original working fluid in the tank through a small circular orifice, and further reaches the outlet pipe 14 under the guidance of the converging pipe 13. The small circular orifice reduces the stratification of the working fluid in the tank.

[0042] In a hot storage tank, the fluid is fully heated by the electric heating tape 9 as it flows through the transition pipe 12. The working fluid avoids losses caused by relative motion and reduces pressure resistance through the guiding pipe consisting of the inlet pipe 11, the transition pipe 12, and the converging pipe 13. After flowing out of the tank outlet, the hot and cold working fluids enter the second three-way pipe and mix under the action of the three-way regulating valve 5, finally flowing out from the device outlet and into subsequent components of the circulation system.

[0043] Example 2

[0044] Based on Example 1, this example provides a horizontally parallel dual-tank supercritical carbon dioxide system. The central axis of the transition pipe inlet is aligned with the inlet pipe. The transition pipe itself is smooth and spirals around the inside of the tank. It has several small circular holes. The central axis of its outlet section is aligned with the central axis of the converging pipe and the outlet pipe.

[0045] The tapering pipe is located before the outlet pipe. Its overall structure is a hollow frustum, and its central axis is aligned with the ends of the inlet pipe, the transition pipe, and the outlet pipe.

[0046] Example 3

[0047] Based on Example 1, this example provides a horizontally parallel dual-tank supercritical carbon dioxide system, wherein the transition pipe 12 has several small circular holes along its axial direction.

[0048] Because the thermophysical properties of the supercritical state are extremely sensitive, phase transitions and stratification are prone to occur within the storage tank. Furthermore, if this phase transition occurs within the drain pipe, it is highly likely to cause blockage. This embodiment innovatively designs a transition pipe with small holes in its wall, allowing for material exchange between the fluid in the pipe and the fluid in the storage tank. Simultaneously, the flowing working fluid within the pipe also achieves a certain degree of mixing and stirring of the working fluid in the storage tank, effectively mitigating adverse phenomena such as stratification and even phase transitions caused by temperature sensitivity.

[0049] Example 4

[0050] This embodiment provides a control method for a horizontally parallel dual-tank supercritical carbon dioxide system, including the following steps:

[0051] Step 1: Obtain temperature and pressure information at the outlets of the two tanks;

[0052] Step 2: Adjust the three-way regulating valve 5 at the outlet according to the collected temperature and pressure. The three-way regulating valve 5 adjusts the opening of the two tank outlets to adjust the ratio of high-temperature carbon dioxide working fluid and low-temperature carbon dioxide working fluid, and mixes them at the outlet to control the temperature of the working fluid flowing out of the device outlet.

[0053] In the heat storage tank, the start and stop of the electric heating tape are adjusted in real time according to the collected temperature to ensure that the working medium in the heat storage tank 1 is heated to 50°C.

[0054] In the event of an accident, the safety valves at the front end of the two storage tanks will be activated to ensure the safety of the equipment and circulation.

[0055] Because the physical properties of the aforementioned supercritical state are unstable, the supercritical state and the gas-liquid two-phase coupling and mixing will occur when the fluid flows in and out of the tank. This flowing working medium generates complex relative motion with the original stationary working medium inside, forming a highly complex flow phenomenon such as vortex structure and secondary flow, resulting in a large pressure loss and reduced circulation efficiency. The present invention adopts a diversion pipe design in the tank, which is a combination of inlet pipe, transition pipe, tapering pipe and outlet pipe, to avoid strong relative motion and thus reduce pressure loss.

[0056] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A horizontally arranged parallel double-tank system for supercritical carbon dioxide, characterized in that, The system includes a horizontally arranged hot storage tank and a cold storage tank, each comprising a tank body. An inlet pipe is arranged in the inner cavity of the tank body. One end of the inlet pipe is connected to the inlet of the tank body, and the other end is sequentially connected to a transition pipe, a converging pipe, and an outlet pipe. The outlet pipe is connected to the outlet of the tank body. Several small circular holes are formed along the axial direction of the transition pipe. The transition pipe has a spiral structure.

2. The supercritical carbon dioxide horizontally parallel double-tank system according to claim 1, characterized in that, The tapering pipe is a hollow frustum-shaped structure, with its small end connected to the outlet pipe and its large end connected to the transition pipe.

3. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 2, characterized in that, The inlets of the hot storage tank and the cold storage tank are connected in parallel via a first tee pipe, and a one-way valve is installed on the first tee pipe.

4. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 1, characterized in that, The outlets of the hot storage tank and the cold storage tank are connected in parallel via a second three-way pipe, and a three-way regulating valve is installed on the second three-way pipe.

5. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 1, characterized in that, The hot storage tank and the cold storage tank are placed side by side on a fixed base.

6. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 4, characterized in that, A thermometer and a pressure gauge are installed on the second three-way pipe.

7. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 1, characterized in that, Safety valves are installed at the inlet of both the hot and cold storage tanks.

8. The horizontally arranged parallel double-tank supercritical carbon dioxide reactor according to claim 1, characterized in that, The outer wall of the heat storage tank is equipped with an electric heat tracing cable.

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