A sealed nitrogen zero-dispersion heat conducting oil heat storage system

Abstract

The application discloses a sealed nitrogen zero-dispersion heat-conducting oil heat storage system. The system comprises a cold oil tank, a hot oil tank, a cold oil pump, a heat-conducting oil heater, a hot oil pump, a heat-conducting oil heat radiator and a constant-pressure nitrogen storage device. The constant-pressure nitrogen storage device comprises a cylinder and a floating plate movably arranged in the cylinder, and a counterweight is arranged on the floating plate. The floating plate divides the cylinder into an upper cavity and a lower cavity. The upper cavity is communicated with the atmosphere, and the lower cavity stores nitrogen. The lower cavity of the constant-pressure nitrogen storage device is communicated with the upper gas side space of the cold oil tank through a pipeline. The application not only reduces the influence of nitrogen dispersion of the heat-conducting oil heat storage system on the environment, but also saves the energy consumption of nitrogen making corresponding to nitrogen supplement caused by nitrogen dispersion, and is an energy-saving, environment-friendly and economic innovative technology.

Description

Technical Field

[0001] This invention relates to a sealed, zero-venting heat transfer oil thermal storage system. Background Technology

[0002] Thermal oil storage technology, as an important direction in the field of large-scale physical energy storage, has found a certain range of applications in the thermal storage field due to its advantages such as high heat storage density, high operating temperature, low operating pressure, and long service life. A typical thermal oil storage system usually includes a cold oil tank and a hot oil tank, used to store low-temperature and high-temperature thermal oil, respectively. Because thermal oil reacts and deteriorates upon contact with oxygen and moisture in the air, high-purity nitrogen is commonly used to seal the top gas-side space of the storage tank to prevent air intrusion.

[0003] In existing nitrogen sealing processes for thermal oil storage systems, the common practice is to connect the sealed nitrogen pipelines at the top of the cold oil tank and the hot oil tank to balance the pressure at the top of the two tanks. However, in actual dynamic operation of energy storage (heat absorption) and energy release (heat expulsion), this simple connection method has significant technical drawbacks. Specifically, during energy storage, the thermal oil in the cold oil tank is pumped out to the absorber, causing the liquid level in the tank to drop, the gas volume to increase, and the pressure to decrease. At the same time, the high-temperature thermal oil after heat absorption enters the hot oil tank, causing the liquid level in the hot oil tank to rise, the gas volume to decrease, and the pressure to increase. Although the tops of the two tanks are connected, due to fluid resistance, differences in the rate of liquid level change, and the compressibility of the gas, the connecting pipeline often cannot instantly and completely balance the pressure fluctuations between the two tanks. When the pressure in the hot oil tank rises sharply due to a rapid increase in the liquid level and exceeds the system's set safety threshold, the mixed gas is often forced to be discharged into the atmosphere through the hot oil tank's breather valve or emergency relief device, resulting in ineffective nitrogen release. Conversely, during the energy release process, the outflow level of the heat transfer oil in the hot oil tank decreases, while the return level of the heat transfer oil in the cold oil tank rises. At this time, the pressure at the top of the cold oil tank will increase due to the pressure from the liquid level. If this pressure cannot be balanced to the hot oil tank side in time, it will also lead to nitrogen leakage from the cold oil tank side. When the liquid level in either tank drops too quickly due to the extraction of heat transfer oil, and the other side of the connecting pipe cannot replenish sufficient gas volume in time, a negative pressure trend will form inside the tank. In order to maintain the structural safety of the tank, the system must replenish fresh nitrogen into the tank through the nitrogen replenishment valve.

[0004] This pressure imbalance caused by dynamic changes in liquid level during energy storage and release leads to a recurring phenomenon in existing systems: "sometimes releasing nitrogen, sometimes replenishing it" during the cycle. This not only results in a continuous waste of high-purity nitrogen, increasing system operating costs, but also increases the risk of valve failure due to frequent breather valve operation, reducing the safety and reliability of the thermal storage system. Therefore, there is an urgent need to develop a thermal oil thermal storage system that can effectively solve the aforementioned pressure imbalance problem and achieve zero nitrogen replenishment and zero release. Summary of the Invention

[0005] To overcome the above-mentioned defects, the purpose of this invention is to provide a sealed heat transfer oil thermal storage system with zero nitrogen release.

[0006] To achieve the above objectives, the sealed nitrogen-free heat transfer oil thermal storage system of the present invention includes a cold oil tank, a hot oil tank, a cold oil pump, a heat transfer oil heater, a hot oil pump, a heat transfer oil heat exchanger, and a constant pressure nitrogen storage device, wherein: The cold oil tank stores cold heat transfer oil. The upper part of the cold oil tank is equipped with an air-side space, which is sealed with nitrogen to isolate it from air. The hot oil tank stores heat transfer oil. The upper part of the hot oil tank is provided with an air-side space, which is sealed with nitrogen to isolate it from air. The cold oil tank is connected to the heat transfer oil heater via a cold oil pump. The cold oil pump pressurizes the cold heat transfer oil in the cold oil tank and sends it to the heat transfer oil heater for heating. The heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the hot oil tank; The hot oil tank is connected to the heat transfer oil heat exchanger via a hot oil pump. The hot oil pump pressurizes the heat transfer oil in the hot oil tank and sends it to the heat transfer oil heat exchanger for heat release and cooling. The heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the cold oil tank, thereby realizing the closed circulation of the heat transfer oil; The constant pressure nitrogen storage device includes a cylinder and a float that is movably installed inside the cylinder. The float is equipped with a counterweight. The float divides the cylinder into upper and lower chambers. The upper chamber is connected to the atmosphere, and the lower chamber stores nitrogen. The lower chamber of the constant pressure nitrogen storage device is connected to the upper gas-side space of the cold oil tank through a pipeline.

[0007] The upper gas-side space of the cold oil tank and the upper gas-side space of the hot oil tank are connected by a nitrogen connecting pipe to achieve nitrogen exchange.

[0008] Furthermore, the constant pressure nitrogen storage device includes a cylinder, which comprises a top, a wall, and a bottom, all of which are connected as a whole. The float plate has a shallow spherical shell in the middle, and a fence is set around the perimeter of the shallow spherical shell. The counterweight is set on the float plate inside the fence.

[0009] Furthermore, a sealing ring is provided between the cylinder wall and the float plate to seal the nitrogen gas.

[0010] To address the problem of nitrogen release in current thermal oil storage systems, this invention achieves zero nitrogen release by implementing a constant-pressure nitrogen storage device. This invention not only reduces the environmental impact of nitrogen release from thermal oil storage systems but also eliminates additional power consumption, saving the energy required for nitrogen replenishment due to nitrogen release. It is an innovative, energy-saving, environmentally friendly, and economical technology. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of a structure according to an embodiment of the present invention.

[0012] Figure 2 for Figure 1 A schematic diagram of a medium-pressure nitrogen storage device.

[0013] Figure 3 This is a schematic diagram of another embodiment of the present invention.

[0014] Figure 4 This is a schematic diagram of another embodiment of the present invention. Detailed Implementation

[0015] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0016] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0017] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0018] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] Example 1 like Figure 1 and Figure 2 As shown, the sealed nitrogen-free heat transfer oil thermal storage system of this embodiment includes a cold oil tank 1, a hot oil tank 2, a cold oil pump 3, a heat transfer oil heater 4, a hot oil pump 5, a heat transfer oil heat exchanger 6, a nitrogen connecting pipe 7, and a constant pressure nitrogen storage device 8, wherein: Cold oil tank 1 stores cold heat transfer oil. The upper part of the cold oil tank is provided with an air-side space, which is sealed with nitrogen to isolate air. Hot oil tank 2 stores heat transfer oil. The upper part of the hot oil tank is provided with an air-side space, which is sealed with nitrogen to isolate air. Cold oil tank 1 is connected to heat transfer oil heater 4 via cold oil pump 3. Cold oil pump 3 pressurizes the cold heat transfer oil in cold oil tank 1 and sends it to heat transfer oil heater 4 for heating. The heat transfer oil outlet of the heat transfer oil heater 4 is connected to the heat transfer oil inlet of the hot oil tank 2; The hot oil tank 2 is connected to the heat transfer oil heat exchanger 6 via the hot oil pump 5. The hot oil pump 5 pressurizes the heat transfer oil in the hot oil tank 2 and sends it to the heat transfer oil heat exchanger 6 for heat release and cooling. The heat transfer oil outlet of the heat transfer oil heat exchanger 6 is connected to the heat transfer oil inlet of the cold oil tank 1, thereby realizing the closed circulation of the heat transfer oil. The upper gas-side space of cold oil tank 1 and the upper gas-side space of hot oil tank 2 are connected by nitrogen connecting pipe 7 to achieve nitrogen exchange.

[0020] The constant pressure nitrogen storage device is designed as a cylinder, the cylinder body including the top 8.1, the wall 8.2, and the bottom 8.3, which are connected as a whole; a float 8.6 is installed inside the cylinder, and a counterweight is installed on the float; the float divides the cylinder body into upper and lower chambers, the upper chamber is connected to the atmosphere, and the lower chamber stores nitrogen; the lower chamber of the constant pressure nitrogen storage device is connected to the upper gas side space of the cold oil tank and / or the upper gas side space of the hot oil tank through a pipeline.

[0021] The constant pressure nitrogen storage device further includes a fence 8.5; the float 8.6 has a shallow spherical shell in the middle, and the edge of the shallow spherical shell is connected to the fence 8.5. A counterweight is set inside the fence to ensure that the downward pressure applied by the float is constant; the constant pressure nitrogen storage device further includes a sealing ring 8.4, which is set between the cylinder wall 8.2 and the float to seal the nitrogen and prevent nitrogen leakage.

[0022] Example 2: Based on the above embodiments, such as Figure 3 As shown, the pipeline connecting the constant pressure nitrogen storage device 8 and the upper gas side space of the cold oil tank 1 is divided into two paths. One path is the inlet pipeline 9, which is equipped with a resistance element 11 and a check valve 12. The other path is the outlet pipeline 10, which is equipped with a check valve 14. The resistance element 11 and the check valve 12 are arranged sequentially along the direction from the cold oil tank to the constant pressure nitrogen storage device 8. The purpose of setting the resistance element 11 is to ensure that the gas side space pressure of the heat transfer oil tank reaches a certain level before entering the constant pressure nitrogen storage device 8. Within a certain pressure range, the nitrogen between the cold oil tank 1 and the hot oil tank 2 is directly interconnected, which can effectively reduce the volume requirement of the constant pressure nitrogen storage device 8.

[0023] When the nitrogen pressure on the gas side of the heat transfer oil tank is high, the check valve 14 is closed and the check valve 12 is opened, and the nitrogen on the gas side of the heat transfer oil tank enters the constant pressure nitrogen storage device 8 through the resistance element 11 and the check valve 12 in sequence; when the nitrogen pressure on the gas side of the heat transfer oil tank is low, the check valve 14 is opened and the check valve 12 is closed, and the nitrogen in the constant pressure nitrogen storage device 8 is replenished into the gas side space of the cold oil tank through the check valve 14.

[0024] A resistance element 11 and a check valve 12 are installed on the inlet pipe 9, and a check valve 14, which is opposite to the check valve 12, is installed on the outlet pipe 10. This combination cleverly realizes that the interconnection between the constant pressure nitrogen storage device 8 and the gas side of the heat transfer oil tank only occurs when the nitrogen pressure on the gas side of the heat transfer oil tank exceeds the upper limit or falls below the lower limit, effectively reducing the volume of the constant pressure nitrogen storage device 8.

[0025] The aforementioned resistance component 11 can be a regulating valve, or a reducer, orifice plate, etc.

[0026] Example 3: Based on the above embodiments, a cooler 13 is also provided on the air inlet pipe 9. The cooler 13 cools the high-temperature nitrogen gas entering the constant pressure nitrogen storage device with external cooling water. On the one hand, this significantly reduces the nitrogen volume in the constant pressure nitrogen storage device 8, thereby reducing the volume of the constant pressure nitrogen storage device 8. On the other hand, if it is not cooled, the nitrogen temperature will be high, and the temperature resistance requirements and material costs of the sealing ring 8.4 of the constant pressure nitrogen storage device 8 will be very high, and the service life will also be greatly affected. The low-temperature nitrogen gas treated by the cooler 13 before entering the constant pressure nitrogen storage device 8 can effectively solve this problem.

[0027] Example 4: Based on the above embodiments, a temperature sensor is installed on the nitrogen inlet pipe of cooler 13, and a valve is installed on the cooling water inlet pipe of cooler 13. This valve is interlocked with the temperature sensor signal on the nitrogen inlet pipe of cooler 13. If the nitrogen temperature is high, the cooling water valve opens, so that cooling water is only needed during certain periods, thus saving the total cooling water consumption. In addition, since the specific heat of cooling water is much greater than that of nitrogen, and due to the ingenious arrangement of pipes 9 and 10, only a small amount of nitrogen enters the constant pressure nitrogen storage device for a short period of time. Therefore, in reality, only a very small amount of cooling water is needed to cool the nitrogen.

[0028] Example 5: like Figure 4 As shown, the constant pressure nitrogen storage device 8 is connected to the nitrogen connecting pipe 7. Compared with the previous scheme, the nitrogen entering the constant pressure nitrogen storage device 8 has a higher temperature (high-temperature nitrogen from the hot oil tank may directly enter the constant pressure nitrogen storage device 8), and the overall effect is not as good as the aforementioned scheme of directly connecting to the gas side space of the cold oil tank. However, it is still an optional scheme.

[0029] The present invention has been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Many other changes and modifications made without departing from the concept and scope of the present invention should be considered within the scope of protection of the present invention.

[0030] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0031] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A sealed, nitrogen-free heat transfer oil thermal storage system, characterized in that, Includes cold oil tanks, hot oil tanks, cold oil pumps, thermal oil heaters, hot oil pumps, thermal oil heat exchangers, and constant pressure nitrogen storage devices, among which: The cold oil tank stores cold heat transfer oil. The upper part of the cold oil tank is equipped with an air-side space, which is sealed with nitrogen to isolate it from air. The hot oil tank stores heat transfer oil. The upper part of the hot oil tank is provided with an air-side space, which is sealed with nitrogen to isolate it from air. The cold oil tank is connected to the heat transfer oil heater via a cold oil pump. The cold oil pump pressurizes the cold heat transfer oil in the cold oil tank and sends it to the heat transfer oil heater for heating. The heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the hot oil tank; The hot oil tank is connected to the heat transfer oil heat exchanger via a hot oil pump. The hot oil pump pressurizes the heat transfer oil in the hot oil tank and sends it to the heat transfer oil heat exchanger for heat release and cooling. The heat transfer oil outlet of the heat transfer oil heater is connected to the heat transfer oil inlet of the cold oil tank, thereby realizing the closed circulation of the heat transfer oil; The constant pressure nitrogen storage device includes a cylinder and a float that is movably installed inside the cylinder. The float is equipped with a counterweight. The float divides the cylinder into upper and lower chambers. The upper chamber is connected to the atmosphere, and the lower chamber stores nitrogen. The lower chamber of the constant pressure nitrogen storage device is connected to the upper gas-side space of the cold oil tank through a pipeline; The upper gas-side space of the cold oil tank and the upper gas-side space of the hot oil tank are connected by a nitrogen connecting pipe to achieve nitrogen exchange.

2. The sealed nitrogen-free heat transfer oil thermal storage system as described in claim 1, characterized in that, The constant pressure nitrogen storage device includes a cylinder, which comprises a top, a wall, and a bottom, all of which are connected as a whole. The float plate has a shallow spherical shell in the middle, and a fence is set around the perimeter of the shallow spherical shell. The counterweight is set on the float plate inside the fence.

3. The sealed nitrogen-free heat transfer oil thermal storage system as described in claim 2, characterized in that, A sealing ring is provided between the cylinder wall and the float to seal the nitrogen gas.

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