Thermal energy storage system and method based on temperature stratification and dynamic isothermal layer control

Abstract

The invention relates to a thermal energy storage system and method based on temperature stratification and dynamic isothermal layer control. The system comprises a pressure-resistant shell internally provided with a tower-type layered heat storage unit, the unit is composed of a plurality of heat storage cavities which are stacked up and down, and the temperature gradient with the high temperature at the upper part and the low temperature at the lower part is naturally formed by utilizing the characteristic that the water temperatures are different and the densities are different; a partition plate with a water passing structure is arranged between every two adjacent cavities so as to balance the water level and prevent turbulent flow. And each chamber is provided with a water outlet valve and a water return inlet valve which are independently controlled. According to the method, opening and closing of valves of corresponding temperature layers are dynamically controlled according to the real-time temperature of external thermal equipment through a homothermal layer control strategy, synchronous movement of a water taking layer and a water returning layer along with process temperature changes is achieved, and therefore accurate storage and taking and gradient cyclic utilization of heat energy are completed. The problems that in the prior art, a system is redundant, and the heat energy mixing and single-time utilization efficiency is low are solved, the structure is simplified, heat energy is stably stored, the energy efficiency is maximized, and the energy-saving effect is remarkable.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thermal energy storage and recovery, in particular to an energy storage system and method for industrial thermal energy management (such as printing and dyeing equipment), specifically a thermal energy storage system and method based on temperature stratification and dynamic stratosphere control, including structural design based on the physical properties (density difference and low thermal conductivity) of water to achieve temperature stratification storage, dynamic stratosphere control method and its application in the re-dyeing vat thermal energy cycle. BACKGROUND

[0002] In the field of industrial thermal energy management, especially in the process of dyeing textiles, dyeing vats need to be continuously heated or cooled (usually between 40℃ and 130℃). This process consumes a large amount of high-temperature steam and cooling water, resulting in low energy efficiency. Thermal energy recovery technology aims to capture the waste heat discharged from the dyeing vat, store and reuse it to reduce energy consumption. An ideal thermal energy storage system needs to solve two core problems: 1. Maximize the recovery of water at the highest possible temperature for storage, and 2. Maximize the utilization of stored water at different temperatures to maximize utilization.

[0003] Current thermal energy storage technology mainly falls into two categories: Single-temperature storage system: such as conventional hot water storage tanks, which only store water at a single temperature, cannot achieve multi-temperature gradient heat energy utilization, resulting in waste of heat energy quality.

[0004] Multi-tank discrete storage system: such as Chinese patent CN204000282U (energy-saving dyeing vat), which uses separate high-temperature water, medium-temperature water, and low-temperature water storage devices connected to the dyeing vat through heat exchangers. This technology partially recovers heat energy, but has significant drawbacks: 1. Each storage device is independent, without an organic combination of structure and function, resulting in a complex system and large space occupation.

[0005] 2. Low thermal energy recycling efficiency: high-temperature water and medium-temperature water cannot be naturally stratified during storage, requiring external equipment to control temperature, increasing energy loss.

[0006] 3. Lack of dynamic gradient recovery mechanism: existing technologies focus on single recovery of heat energy, and cannot achieve multiple, step-by-step, and cyclic utilization of heat energy within the system and between the system and external equipment. The water taking and returning process is often static and isolated, failing to build a closed-loop, dynamically adjustable gradient energy recovery chain according to process requirements, resulting in a large amount of low-grade heat energy being discharged into the environment without being fully utilized, and the energy utilization efficiency ceiling being low.

[0007] In summary, the prior art fails to effectively solve the problems of temperature stratification stability and dynamic control efficiency in thermal energy storage: Patent CN204000282U realizes multi-temperature storage through separate storage tanks, but each tank operates independently, resulting in ineffective gradient utilization of thermal energy, and the heating of the dye vat is not random heating, but needs to follow a strict temperature rise curve, such as a temperature rise of 0.8℃ or 1.1℃ per minute, etc. to meet the process requirements. Simply using high-temperature water to heat is difficult to control the temperature rise rate; therefore, this technology has not been applied since it was proposed in 2006, and most importantly, this technology only connects high-temperature low-grade high-temperature water to a steam heat exchanger, and the steam heat exchanger shares a heat exchanger, which cannot meet the temperature rise rate of the dye vat. After all, the heat exchange of steam is much larger than the heat enthalpy of water.

[0008] Therefore, the technical problem to be solved by the present application is: how to provide an energy storage system with compact structure, stable thermal energy storage and realizing thermal energy gradient recovery and recycling, by organically combining temperature stratified storage and dynamic isothermal layer control, to build a closed-loop system that can adapt to external process temperature changes, access and release thermal energy step by step, thereby solving the problems of thermal energy mixing, low efficiency and inability to gradient efficient utilization in the prior art.

[0009] It should be noted that the information disclosed in this background section is only intended to deepen the understanding of the overall background of the present application, and should not be regarded as acknowledging or implying in any form that this information constitutes prior art known to those skilled in the art. SUMMARY

[0010] Based on the background technology described above, the purpose of the present application is to overcome the defects of the prior art, and to provide a thermal energy storage system and method based on temperature stratification and dynamic isothermal layer control. The system and method aim to solve the problems of system redundancy, thermal energy mixing caused by multiple separate tanks in the prior art, and the problems of inability to gradient cyclic utilization of thermal energy multiple times and low overall energy efficiency caused by lack of precise control strategy. Thus, stable, by grade storage and efficient, gradient recovery and utilization of thermal energy are achieved.

[0011] The present application is based on a deep understanding and creative application of two key physical properties of water: 1. Temperature-density property: water has different densities at different temperatures, and the higher the temperature, the smaller the density (as shown in Table 1). This property causes water at different temperatures to naturally stratify in a gravitational field, with high-temperature water at the top and low-temperature water at the bottom, and the interface is clear, and there is no violent convection mixing due to density difference in static state. This phenomenon is common in nature, such as the thermocline of deep water lakes.

[0012] 2. Low thermal conductivity: water is a poor conductor of heat, with a low thermal conductivity (about 0.6 W / (m·K) at room temperature). This means that the process of heat transfer by conduction is very slow, allowing the temperature gradient after stratification to be maintained for a long time.

[0013] Table 1: Relationship between temperature and density of water at standard atmospheric pressure Temperature (°C) Density (g / liter) 100 958.37 95 961.92 90 965.31 85 968.55 80 971.64 75 974.59 70 977.37 65 979.99 60 982.46 Stability theory calculation: Assuming the height difference between the high 100℃ water layer and the low 90℃ water layer is 1 meter, taking the 20cm thick 100℃ water layer at the high position as the heat source, and the container diameter is 1 meter.

[0014] According to the heat transfer formula: Where k (thermal conductivity) = 0.6 W / (m·K); ; Temperature difference = 10K; Heat transfer distance = 1m.

[0015] The calculation is: Heat transfer per hour is about 4.71 watts.

[0016] The total available heat enthalpy difference of this part of 100℃ water relative to 90℃ water is about: .

[0017] If the temperature difference is maintained, the time required to completely conduct heat from the 100℃ water layer to the 90℃ water layer is theoretically more than 233 hours.

[0018] This calculation proves that at the macroscopic scale, the heat exchange rate between water layers of different temperatures is extremely slow by relying on heat conduction alone, and temperature stratification has excellent natural stability. Therefore, it is theoretically and experimentally feasible and stable to inject water of different temperatures into corresponding height layers in the same container. The design of the present invention is based on the above two physical principles, breaking the traditional technical prejudice that water of different temperatures must be stored in separate tanks.

[0019] The present invention is based on the application of the above-mentioned physical properties of water, and its core design idea is to build a "thermal energy bank" that not only can "save" thermal energy by temperature (temperature) zoning, but also can "precise spending" and "recycle investment" through intelligent strategies, realizing the gradient recovery and maximum utilization of thermal energy.

[0020] Based on the above design principles, the present invention adopts the following core technical solutions: In a first aspect, the present application provides a thermal energy storage system based on temperature stratification and dynamic isotherm control. The system comprises a shell as a pressure-resistant container, and the core of the shell is that a tower-type stratified heat storage unit is arranged in the shell, the unit is composed of at least two heat storage chambers arranged in a stack, and a temperature gradient distribution from high temperature to low temperature is naturally formed in the unit by using the density difference of water at different temperatures.

[0021] Each of two adjacent heat storage chambers is separated by a partition plate, and a water passing structure is arranged on the partition plate. The flow cross section of the water passing structure is specially designed, and the core function is to balance the water level between adjacent chambers, and at the same time, the water passing structure can effectively inhibit the violent convection mixing between temperature layers, so as to maintain the stability of temperature stratification.

[0022] Each of the heat storage chambers is independently provided with a water outlet valve and a water inlet valve. The valves of the heat storage chambers are connected in parallel to the water outlet main pipe and the water return main pipe through pipelines, and are connected to external thermal equipment through a water pump and a heat exchanger, thereby forming a complete thermal energy exchange circuit.

[0023] The system further comprises a control unit, which is the core of intelligent control.

[0024] The tower-type stratified structure, the partition plate with the water passing structure, and the valves of the chambers for independent control jointly constitute the physical basis for realizing the method of the present application. Based on the special system structure, the present application provides a thermal energy gradient recovery method in a second aspect.

[0025] The core of the method is a "dynamic gradient energy recovery strategy" executed by the control unit, which includes a cycle process. 1. Heat release and gradient storage process: monitoring the current temperature of the external thermal equipment; according to the temperature, selecting a first heat storage chamber in which water with a temperature matching the temperature is stored as a water taking layer; opening the water outlet valve of the water taking layer to deliver water to the heat exchanger to release heat and heat the external thermal equipment; and storing the water with a reduced temperature after heat release in a second heat storage chamber with a temperature matching the reduced temperature.

[0026] 2. Heat storage and gradient storage process: monitoring the temperature of the waste heat water discharged from the external thermal equipment; according to the temperature of the waste heat water, selecting a third heat storage chamber with a temperature matching the temperature of the waste heat water as a water return layer; opening the water inlet valve of the water return layer to deliver the waste heat water to the heat exchanger to absorb heat, and then storing the waste heat water in the third heat storage chamber.

[0027] The key of the method is that the water taking layer and the backwater layer dynamically synchronously move downward or upward according to the real-time temperature change of the external thermal equipment in a continuous heating or cooling process cycle of the external thermal equipment. For example, in the cooling cycle, the operation layer synchronously moves downward from the high-temperature layer to the low-temperature layer; in the heating cycle, the operation layer synchronously moves upward from the low-temperature layer to the high-temperature layer. The mode of the'synchronous movement of the operation layer' realizes the stepwise recycling and recycling of thermal energy.

[0028] Compared with the prior art, the present application has the following remarkable beneficial effects: 1. Simplified structure and high integration: the multi-chamber design in a single tower container replaces multiple separate storage tanks, greatly simplifying the system structure, reducing the land area and equipment cost, and improving the system integration and reliability.

[0029] 2. Thermal energy storage efficiency and stability greatly improved: the density difference and low thermal conductivity of water are creatively utilized to realize spontaneous heat stratification, and the stability of stratification is maintained through special water passing structure design, which significantly reduces energy loss and enables long-term stable storage of thermal energy.

[0030] 3. Realize the stepwise recycling and recycling of thermal energy, and the energy utilization rate is very high: through the 'dynamic stepwise energy recovery strategy' and the'synchronous movement of the operation layer', the traditional 'one-time thermal energy utilization' mode is innovated into the'multi-cycle, step-by-step utilization' mode. A high-grade thermal energy can be extracted and utilized multiple times, its available energy can be maximized, and the overall energy efficiency is greatly improved.

[0031] 4. High system adaptability and intelligence: by integrating temperature sensors and intelligent control units, the system can automatically respond to changes in the working state of the external thermal equipment, adjust the operation strategy in real time, and realize the intelligentization and automation of the thermal energy management process. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 : shows the overall structure schematic diagram of the thermal energy storage system of the present application; Figure 2 : shows the system working schematic diagram of the thermal energy storage system of the present application connected with the external thermal equipment; Figure 3 : shows another embodiment schematic diagram of the thermal energy storage system connected with the external thermal equipment; Figure 4 : shows the schematic diagram of the partition plate and the water passing structure; Figures 5-8 : shows the example diagram of the thermal energy storage system of the present application taking water and backwater; Figure 9 : shows the control method flow chart of the present application; Figure 10 : shows temperature stratification stability test graph; Figure 11 : shows temperature fluctuation range schematic diagram; Figure 12 : shows thermal energy cycle timing diagram. DETAILED DESCRIPTION

[0033] Before the implementation of the technical solutions of the present application, the core physical principle on which the present application works needs to be clarified again, which is detailed in the second part of the summary of the invention of the present specification and the detailed discussion of the design principle of the present application. This principle ensures that the scheme of "storing water bodies of different temperatures at different height layers in the same container" described in the present application has sufficient scientific basis and feasibility.

[0034] The technical features and advantages of the present application are described in more detail below in conjunction with the drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the scope of protection of the present application can be more clearly and explicitly defined.

[0035] Embodiments of the present application provide a thermal energy storage system and method based on temperature stratification and dynamic thermocline control. By combining structural design and intelligent control methods, the physical properties of water are fully utilized to achieve stable stratified storage and stepwise recycling of thermal energy.

[0036] Please refer to Figures 1-4 The schematic diagram of the thermal energy storage system based on temperature stratification and dynamic thermocline control provided by the embodiments of the present application is as follows: 1. Pressure-resistant container (shell 1): The shell 1 is the main structure of the system, which is usually made of carbon steel or stainless steel, and the design pressure can be set according to the application scenario, for example, for dye vat applications, the design pressure is usually not less than 0.4 MPa. The shape of the shell 1 is preferably a vertically placed cylinder, and the ratio of its height (H) to diameter (D) is used to enhance the temperature stratification effect, and the height-diameter ratio (H / D) is preferably between 3:1 and 8:1. This design aims to utilize height to enhance temperature stratification effect, and a too small ratio is not conducive to forming a stable temperature gradient, and a too large ratio increases the manufacturing cost and no longer significantly improves the stability.

[0037] 2. Towered stratified thermal storage unit: The shell 1 is provided with a towered stratified thermal storage unit. The unit is composed of several (usually no less than 3) thermal storage chambers 2 stacked vertically. Each thermal storage chamber 2 is used to store water at different temperatures, forming a temperature gradient distribution from high to low (e.g. 5-10℃ per level). Taking 10℃ as an example, if the water temperature of the uppermost thermal storage chamber 2 is 120℃, then the water temperature of the second thermal storage chamber 2 is 110℃, and the water temperature of the third thermal storage chamber 2 is 100℃, and so on. If 5℃ is taken as an example, if the water temperature of the uppermost thermal storage chamber 2 is 120℃, then the water temperature of the second thermal storage chamber 2 is 115℃, and the water temperature of the third thermal storage chamber 2 is 110℃, and so on. In some embodiments, if the number of same-temperature layers is too large, the height of the shell 1 will be too large, which will greatly increase the processing difficulty and stability. At this time, multiple thermal energy storage systems can be used in series, such as shown in Figure 3 which shows a connection diagram of two thermal energy storage systems 11, 12 used in series, such as the first thermal energy storage system 11 used to distribute 120℃-80℃ same-temperature layers, and the second thermal energy storage system 12 used to distribute 75℃-40℃ same-temperature layers.

[0038] 3. Partition 3 and water passage structure 18: The thermal storage chambers 2 are physically separated by horizontal partitions 3. The partitions 3 are fixed to the inner wall of the shell 1, and the outer edge is sealed and welded with the inner wall of the shell 1 to ensure the sealing between the chambers 2. Specific water passage structures 18 are provided on the partitions 3 to realize hydraulic connection, as shown in Figure 4 .

[0039] The core function of the partition 3 and the water passage structure 18 is to balance the hydrostatic pressure between adjacent chambers, and to allow slow water replenishment to maintain system pressure balance during water taking / replenishing operation. Due to its limited flow cross section, it can effectively suppress the violent convection mixing between temperature layers caused by water flow disturbance, thereby maintaining the stability of temperature stratification in dynamic operation and preventing flow disturbance. The total flow cross-sectional area of the water passage structure 18 ( ) needs to be calculated accurately. The design principle is: when the water level of the lower chamber decreases due to water taking, the water of the upper chamber can slowly flow into the lower chamber through the water passage structure 18 to maintain the system pressure balance; under normal storage conditions, the presence of the water passage structure 18 is not enough to cause violent mixing of the upper and lower layers due to natural convection or slight disturbance.

[0040] As a preferred embodiment, the ratio of the total flow cross-sectional area of the water passage structure 18 ( ) to the total area of the partition 3 ( ) (i.e. the opening rate) should be controlled between 1% and 30%. More preferably, it can be designed according to the following empirical formula to ensure that both water level balance and convection suppression can be achieved: wherein, is the maximum water intake or return flow of a single chamber (m³ / s), g is the acceleration due to gravity (9.8 m / s²), H is the height of the chamber (m). For example, for a chamber with a height of 5 meters and a diameter of 1.5 meters, the maximum design flow is 10 m³ / h (about 0.0028 m³ / s), and the formula calculation can be obtained The ideal range of the water passage structure 18 is about 3 cm² to 90 cm². The water passage structure 18 can be realized by opening a plurality of small holes with a diameter of 2 mm uniformly distributed on the baffle 3, or by opening a single water passage hole. This design can effectively suppress Rayleigh-Benard convection and ensure the stability of temperature stratification under static and dynamic operation.

[0041] The present application lays a physical foundation for temperature stratification stability through the innovative tower-type multi-chamber structure, supplemented by a baffle with a precisely calculated opening rate; on this basis, a dynamic isothermal layer control strategy is introduced, realizing precise access to thermal energy at the operation level. The deep integration of structure and control is the key to successfully overcoming the defects of the prior art.

[0042] 4. Valve and piping system: At least one water outlet valve 4 and a water return inlet valve 5 are independently arranged on each of the heat storage chambers 2. All water outlet valves 4 are connected in parallel to a water outlet main pipe 21 through a pipeline, and all water return inlet valves 5 are connected in parallel to a water return main pipe 22 in the same way. This parallel piping design is the core structural basis for realizing the function of "independent access to any temperature layer" and further realizing the "step-by-step recovery" method. These valves are preferably electric regulating valves or solenoid valves to facilitate precise opening and closing in response to signals from the control unit 20. A first water pump 10 is installed on the water outlet main pipe 21 to pump water to an external heat exchanger 12. The outlet thereof is connected to the primary side inlet of an external heat exchanger 12. The water return main pipe 22 is connected to the primary side outlet of the external heat exchanger 12. The secondary side of the heat exchanger 12 is connected to an external thermal equipment 15 (such as a dye vat). In this way, the system and the external equipment form a complete heat exchange circuit.

[0043] 5. Control and control unit: the control unit 20 (such as PLC) is the intelligent core of the system. It is signal connected with temperature detection device (such as PT100 temperature sensor installed on the heat storage chamber 2 and the pipeline of the equipment 15). The control unit 20 is configured to execute the core of the application "isothermal layer control strategy" algorithm, and its function is to realize the "thermal energy cascade recovery method" defined in the claims. The control unit 20 prewrites or learns the "isothermal layer control strategy" algorithm, and receives temperature signals from two aspects: one is the temperature sensor (such as PT100, not shown in the figure) installed in each heat storage chamber 2, which is used to monitor the temperature of each layer in real time; the second is the first temperature sensor 18 and the second temperature sensor 19 installed on the inlet and outlet pipelines of the external thermal equipment 15 connected with the system. The control unit 20 determines which outlet valve 4 of a chamber 2 and which inlet valve 5 of a chamber 2 should be opened at a certain time through logical operation.

[0044] Considering that there is still a certain temperature difference between the upper and lower water layers in one isothermal layer, in the preferred embodiment, two outlet valves 4 and two inlet valves 5 are arranged on the same heat storage chamber 2, and the two outlet valves 4 and the two inlet valves 5 are arranged at the upper and lower positions of the isothermal layer, respectively. In actual use, the water temperature on the upper side of the isothermal layer is slightly higher than that on the lower side. When the control unit 20 selects the isothermal layer for water taking or water returning, it can select the valve with a temperature closer to the upper valve of the previous isothermal layer or the lower valve of the next isothermal layer.

[0045] In addition, the shell 1 is also provided with auxiliary components for ensuring the safe and stable operation of the system, including: a pressure relief valve 8 for pressure relief when the pressure exceeds the standard; a steam check valve 9 for preventing steam backflow; a cold water inlet valve 6 for system water replenishment; and a drain pipe 7 at the bottom for emptying the system.

[0046] The working principle of the application and the implementation of the method are as follows: The operation logic of the isothermal layer control strategy is as follows: when the external thermal equipment 15 needs to be cooled (heat is released to the system): the control unit 20 reads the high-temperature return water temperature at the outlet of the thermal equipment 15 ( ). Then, it finds the heat storage chamber (i.e. "isothermal layer") closest to the temperature inside the system, and opens the return water inlet valve 5 of the chamber, preparing to return the cooled water in it. At the same time, in order to replace the cold water to cool the thermal equipment 15, the control unit 20 will select a temperature lower than but closest to according to the cooling temperature required by the thermal equipment 15 ( the chamber, open its outlet valve 4. The first water pump 10 works, pumping cold water into the heat exchanger 12 to absorb the heat of the dye vat circulating water, and after being heated, it is stored back to the previously selected high-temperature return water layer. As the temperature of the dye vat continues to drop, the control unit 20 will dynamically and synchronously switch the water taking layer and the return water layer down (for example, from "taking 90°C layer and storing back to 100°C layer" to "taking 80°C layer and storing back to 90°C layer"), realizing the step-by-step storage of heat energy.

[0047] When the external thermal equipment 15 needs to be heated (absorbing heat from the system): the process is reversed. The control unit 20 monitors the low-temperature return water temperature of the thermal equipment 15 ( ), and selects the low-temperature layer closest to the temperature as the storage layer. At the same time, a chamber with a temperature higher than and closest to the target heating temperature is selected as the water taking layer, and hot water will be pumped out by the first water pump 10 to heat the thermal equipment 15. After absorbing heat and cooling down, the water is stored back to the low-temperature layer. As the temperature of the thermal equipment 15 rises, the water taking layer and the return water layer are switched up synchronously.

[0048] The essence of the isothermal layer control strategy is a dynamic, closed-loop step-by-step heat recovery process. The control unit 20 receives signals from temperature sensors, and through logical operations (for example, comparing the temperature of the external equipment with the set temperature of each heat storage chamber, and selecting the one with the smallest temperature difference as the target operating layer), it dynamically determines which valves to open to achieve "isothermal storage and taking" and "step-by-step utilization".

[0049] Take the cooling of the dye vat as an example (refer to Figures 5-8 ): Initial stage: the temperature of the dye vat is 100°C. The control unit 20 opens the return water inlet valve 5 of the 100°C layer (ready to receive 100°C return water) and the outlet valve 4 of the 90°C layer. The 90°C cold water is pumped out, heated to nearly 100°C after cooling the dye vat, and stored back to the 100°C layer. This step completes the first heat recovery.

[0050] Step-down: when the temperature of the dye vat drops to 95°C, the control unit 20 synchronously moves down the operating layer. Close the valves of the 100°C and 90°C layers, and open the return water inlet valve 5 of the 95°C layer and the outlet valve 4 of the 85°C layer. The 85°C cold water is pumped out and stored back to the 95°C layer after heat exchange. This step completes the second heat recovery.

[0051] This process is repeated, and the "water taking layer" and "return water layer" are shifted down one by one (such as switching to "taking 80°C and storing back to 85°C" later), until the cooling process is completed. This process perfectly embodies the "dynamic synchronous step-down" step-by-step recovery method defined in claims 9 and 10.

[0052] The process is the opposite of the cooling period.

[0053] The control unit 20 will monitor the low-temperature backwater of the dye vat and select the low-temperature layer closest to the temperature as the back storage layer, while taking water from the adjacent layer with higher temperature to heat the dye vat.

[0054] The water after heating and cooling is stored in the low-temperature layer. As the temperature of the dye vat gradually rises, the water taking layer and the backwater layer will move up synchronously (for example, from "taking 60℃ water, storing 50℃ water" to "taking 70℃ water, storing 60℃ water"), until the heating process is completed. This process supports the "dynamic synchronous upward movement" method defined in claim 11.

[0055] Figure 12 The timing diagram clearly shows the whole process of the water taking layer and the backwater layer moving up or down synchronously with the temperature change of the external equipment during a complete process cycle, and intuitively reveals the core feature of the "dynamic step energy recovery" of the present application. In the figure, the X-axis represents the time of the process, and the Y-axis represents the temperature value. The upper curve represents the actual temperature of the external thermal equipment 15 (such as the dye vat) over time. The curve shows a complete process cycle, including heating from low temperature to peak temperature, and then cooling. The middle band represents the set value of the temperature of the water taking layer, which gradually increases over time during the heating stage; and gradually decreases over time during the cooling stage. The lower band represents the set value of the temperature of the backwater layer, which changes synchronously with the water taking layer, but is always lower than the temperature of the water taking layer throughout the process. The timing diagram clearly shows that at different time points, when the temperature of the external equipment changes across a certain threshold, the water taking layer and the backwater layer move up (during heating) or down (during cooling) synchronously. The timing diagram intuitively reveals the "dynamic synchronous adjustment" method of the present application. It proves that the present application can intelligently and automatically match the real-time temperature requirements of the external equipment, realize the step-by-step and efficient use of thermal energy, and maximize the energy saving effect, which is a key advantage that the prior art does not have.

[0056] Figure 9 The control flow chart of the thermal energy storage and release method described in the embodiments of the present application. The figure shows how the control unit 20 dynamically executes the isothermal layer control strategy according to the real-time temperature of the external thermal equipment 15, including the complete logic closed loop of judging the mode, selecting the water taking layer and the backwater layer, executing the operation, and dynamically adjusting according to the temperature change.

[0057] To verify the effectiveness of the present application, long-term tests and applications were carried out (see Figure 10 , Figure 11 ). Figure 10 The test curve of the temperature layering stability of the system of the present application, Figure 11 is a schematic diagram of the temperature fluctuation range of each temperature layer.

[0058] The test conditions are as follows: after the system is initially injected with water at different temperatures to form a gradient layer, it enters a static storage state for 240 hours (10 days). During this period, slight environmental disturbance is simulated, and short access cycles are performed 4 times a day.

[0059] During the 240-hour test, the maximum fluctuation range of each temperature layer is less than ±2.5℃, demonstrating excellent static and dynamic layering stability. In the graph, the upper curve represents the temperature change of the high-temperature layer (about 105℃) in the system, the middle curve represents the temperature change of the middle layer (about 80℃), and the lower curve represents the temperature change of the low-temperature layer (about 55℃). During the entire test period, the curves of each temperature layer are very smooth, with a small fluctuation range (the maximum fluctuation range is less than ±2.5℃). The maximum temperature and the minimum temperature always maintain a significant temperature difference of about 50℃.

[0060] The experimental results strongly demonstrate that, based on the structure (partition plate 3 of special water passage structure 18) and physical principles (density difference and low thermal conductivity of water) of the present application and the isothermal layer control strategy, the temperature layering inside the system has excellent static and dynamic stability. Despite frequent access operations, the temperature of each temperature layer remains highly stable during long-term operation, with a small fluctuation range, which can meet the long-term and efficient industrial energy storage application requirements, fully verifying the effectiveness and reliability of the technical solution of the present application. This solves the core problem of heat energy mixing and grade decline mentioned in the background art.

[0061] The technical effects of the present application will be described in detail through several specific examples below.

[0062] Example 1: Energy-saving system applied to dyeing vat The heat energy storage system of the present application is applied to a non-woven fabric dyeing production line with an annual output of 5000 tons. The shell 1 of the system has a diameter of 1.8 meters and a height of 9 meters, and is internally divided into 11 heat storage chambers by 10 stainless steel partition plates 3, with a temperature gradient designed from top to bottom as follows: 105℃, 100℃, 95℃, 90℃, 85℃, 80℃, 75℃, 70℃, 65℃, 60℃, and the bottom layer is a mixed zone below 55℃. The opening rate of the partition plate 3 is set to 2%, the water passage hole diameter is 15mm, and a total of 8 holes are provided.

[0063] Experimental data and effects: During the stable operation of the production line for one month, data collection and analysis were performed: 1. Temperature stability test: After the system is statically stored for 12 hours, the center point temperature of each chamber is measured. The results show that the temperature deviation of each layer is less than ±1.5℃, and the maximum temperature difference between the highest temperature layer (105℃) and the lowest temperature layer (55℃) is maintained at 50℃, demonstrating excellent temperature layering stability.

[0064] 2. Energy saving rate calculation: compare the energy consumption of dyeing the same specification of cloth before and after installing the system. Before installation, the average consumption of steam for dyeing per ton of cloth is 1.8 tons, and the consumption of cooling water is 50 tons. After installation, the steam consumption is reduced to 1.1 tons / ton of cloth, and the cooling water consumption is reduced to 15 tons / ton of cloth.

[0065] Energy saving rate calculation (steam): (1.8 - 1.1) / 1.8 * 100% ≈ 38.9% Water saving rate calculation (cooling water): (50 - 15) / 50 * 100% = 70% 3. Investment return analysis: the total investment of the system is about 450,000 yuan, and the annual benefit from saving steam and cooling water is about 280,000 yuan. The static investment recovery period is about 1.6 years, and the economic benefit is extremely significant.

[0066] Example 2: Application of the pasteurization cooling section in a food processing plant A food factory applied the present application to the cooling section after pasteurization of yogurt bottles. The pasteurized bottled yogurt needs to be cooled from 85°C to 4°C gradually. The traditional process uses a water chiller for direct cooling, which consumes a large amount of electricity.

[0067] Implementation: A smaller energy storage system is used, with a shell diameter of 1 meter and a height of 4 meters, divided into 8 chambers (temperature gradient: 80°C, 70°C, 60°C, 50°C, 40°C, 30°C, 20°C, 10°C). The overheated product at 85°C is first exchanged with the 70°C water layer in the system through a heat exchanger, and the product is pre-cooled to 70°C, while the system heats the water to 80°C for storage. The product is sequentially exchanged with the 60°C, 50°C, etc. level of cold water, and finally cooled to 4°C with a water chiller.

[0068] Effect: This scheme uses the stored cold energy of the system to pre-cool the product, greatly reducing the peak load and running time of the water chiller. The actual measurement data shows that the overall power consumption of this section has decreased by 45%, and due to the more gentle heat exchange process than direct water flushing, the product packaging breakage rate has also decreased.

[0069] Example 3: Long-term operation stability verification of the system To verify the long-term effect of the water passage structure 18 design on the stability of the layers, we monitored the system in Example 1 for 240 hours (10 days). During this period, we simulated the actual working conditions and performed 4 complete "heating-cooling" cycles every day.

[0070] Results: The temperature of each layer was recorded every 24 hours. The data showed that, although frequent access operations were experienced, the temperature change curves of the highest temperature layer and the lowest temperature layer were highly coincident, and the temperature fluctuation range of each intermediate layer did not exceed ±2.5℃. After the experiment ended, the system was at rest for 24 hours, and the temperature of each layer basically returned to the initial set value. This fully proves that, under the reasonable water passage structure design and the same temperature layer control strategy, the temperature stratification of the system has good dynamic and static stability, and can meet the needs of long-term industrial application.

[0071] In summary, through the deep integration of ingenious structure design and intelligent control strategy, the present application successfully solves the long-existing pain points in the field of industrial heat storage, provides an efficient, stable and energy-saving comprehensive solution, and has great market application prospects.

[0072] In the description of the embodiments of the present application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "straight", "horizontal", "center", "top", "bottom", "top", "bottom", "inside", "outside", "inside", "outside" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of description of the present application and simplification of description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore cannot be understood as a limitation on the present application. Among them, "inside" refers to the inside or enclosed area or space. "Periphery" refers to the area around a particular component or a particular area.

[0073] In the description of the embodiments of the present application, the terms "first", "second", "third", "fourth" are only used for description purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second", "third", "fourth" can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "multiple" is two or more.

[0074] In the description of the embodiments of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connecting", "connecting", "assembling" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected, it can be directly connected, or indirectly connected through an intermediate medium, or it can be the communication between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0075] In the description of the embodiments of the present application, specific features, structures, materials or characteristics can be combined in any one or more embodiments or examples in a suitable manner.

[0076] In the description of the embodiments of the present application, it needs to be understood that "-" and "~" represent the range of the same of two values, and the range includes the end points. For example: "A-B" represents the range of greater than or equal to A, and less than or equal to B. "A~B" represents the range of greater than or equal to A, and less than or equal to B.

[0077] In the description of the embodiments of the present application, the term "and / or" herein is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents that the associated objects before and after are an "or" relationship.

[0078] Although the embodiments of the present application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A thermal energy storage system based on temperature stratification and dynamic isothermal layer control, comprising a shell (1) serving as a pressure-resistant container, characterized in that: The shell (1) is provided with a tower-type layered heat storage unit. The layered heat storage unit includes at least two heat storage chambers (2) stacked on top of each other, which are used to store water of different temperatures in layers according to density difference to form a temperature gradient. The high-temperature water is located in the upper part and the low-temperature water is located in the lower part. Each pair of adjacent heat storage chambers (2) are separated by a partition (3), and the partition (3) is provided with a water-passing structure (18) for balancing the water level of adjacent chambers. Each of the aforementioned heat storage chambers (2) is equipped with an outlet valve (4) and a return water inlet valve (5); The system also includes a control unit (20) configured to execute a temperature-matching control strategy: based on the real-time temperature of an external thermal device (15), control the opening of the outlet valve (4) and the return water inlet valve (5) of the corresponding temperature layer, so as to extract temperature-matching water from the stratified thermal storage unit and return temperature-matching water thereto.

2. The thermal energy storage system according to claim 1, characterized in that: The aperture of the water passage (18) is set to be large enough to allow water to flow slowly between adjacent chambers to balance the water level, while being small enough to suppress violent convection mixing between temperature layers caused by water flow disturbance.

3. The thermal energy storage system according to claim 1 or 2, characterized in that: The water passage structure (18) includes at least one water passage hole, and the ratio of the total flow cross-sectional area of ​​the water passage hole to the area of ​​the partition (3) is between 1% and 30%.

4. The thermal energy storage system according to claim 1, characterized in that: The system also includes a temperature detection device for monitoring the temperature of the water in at least a portion of the thermal storage chamber (2) and / or monitoring the inlet and outlet water temperatures of the external thermal equipment (15) connected to the thermal energy storage system; the control unit (20) is signal-connected to the temperature detection device and is configured to dynamically adjust the stratosphere control strategy based on the feedback signal from the temperature detection device.

5. The thermal energy storage system according to claim 1, characterized in that: The outlet valves (4) on each of the heat storage chambers (2) are connected in parallel to a main outlet pipe (21) through outlet pipes, and a first water pump (10) is installed on the main outlet pipe (21). The return water inlet valve (5) on each of the heat storage chambers (2) is connected in parallel to a return water main pipe (22) through a return water pipe.

6. The thermal energy storage system according to claim 5, characterized in that: The main outlet pipe (21) is connected to the primary side inlet of an external heat exchanger (12) via the first water pump (10), and the main return pipe (22) is connected to the primary side outlet of the external heat exchanger (12), thereby forming a heat exchange loop.

7. The thermal energy storage system according to claim 6, characterized in that: The secondary side of the external heat exchanger (12) is used to connect to an external thermal device (15) to form a thermal energy circulation loop of the external thermal device (15).

8. The thermal energy storage system according to claim 1, characterized in that: The housing (1) is also provided with a pressure relief valve (8) and / or a steam inlet check valve (9) and / or a cold water inlet valve (6) and / or a drain pipe (7).

9. A method for cascaded recovery of thermal energy, applied to the thermal energy storage system according to any one of claims 1-8, characterized in that, The method includes the following iterative process: Heat release and cascaded return process: Monitor the current temperature of the external thermal equipment (15); select the first heat storage chamber containing water with a temperature matching the current temperature as the water intake layer; open the outlet valve (4) of the water intake layer to deliver water to a heat exchanger (12) to release heat to heat the external thermal equipment (15); return the water with a lower temperature after heat release to the second heat storage chamber with a temperature matching the lowered temperature; Heat storage and cascade storage process: Monitor the temperature of the waste hot water discharged from the external thermal equipment (15); select the third heat storage chamber with a temperature matching the waste hot water as the return water layer according to the temperature of the waste hot water; open the return water inlet valve (5) of the return water layer, and transport the waste hot water to the heat exchanger (12) to absorb heat and then store it back in the third heat storage chamber; In a continuous heating or cooling process cycle of the external thermal equipment (15), the water intake layer and the water return layer dynamically and synchronously move down or up according to the real-time temperature change of the external thermal equipment (15), thereby realizing the cascade recovery and recycling of thermal energy.

10. The method according to claim 9, characterized in that: During the cooling cycle of the external thermal equipment (15), the water intake layer and the water return layer move down dynamically and synchronously. Specifically, the process is to gradually switch from extracting water from the relatively high temperature layer and returning it to the relatively higher temperature layer, to extracting water from the relatively low temperature layer and returning it to the relatively high temperature layer, until the process ends.

11. The method according to claim 9, characterized in that: During the heating cycle of the external thermal equipment (15), the water intake layer and the water return layer move up dynamically and synchronously. Specifically, the process is to gradually switch from extracting water from the relatively low temperature layer and returning it to the relatively lower temperature layer, to extracting water from the relatively high temperature layer and returning it to the relatively low temperature layer, until the process ends.

12. The method according to claim 9, characterized in that: The control unit (20) calculates the temperature difference by comparing the real-time temperature of the external thermal equipment (15) with the set temperature of each heat storage chamber (2), and selects the heat storage chamber with the smallest temperature difference as the current water intake or return layer.

13. The method according to claim 9, characterized in that: The second heat storage chamber, where the water temperature decreases after heat release, has a lower temperature rating than the water intake layer; and / or, the third heat storage chamber, where heat is stored, has a higher temperature rating than the water intake layer.

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