A high temperature water vapor production system based on air Brayton cycle

Abstract

This invention provides a high-temperature steam production system based on the Brayton cycle, relating to the field of energy recycling technology. The system includes a heat exchanger, a steam generator, and a replenishment subsystem connected to a Brayton cycle subsystem. The heat exchanger heats a low-temperature, low-pressure air medium using a low-temperature heat source to obtain medium-temperature, low-pressure air. The Brayton cycle subsystem heats medium-temperature, low-pressure air with medium-temperature, high-pressure air to obtain high-temperature, low-pressure air and low-temperature, high-pressure air, and then compresses the high-temperature, low-pressure air to obtain high-temperature, high-pressure air. The steam generator heats a saturated water medium with high-temperature, high-pressure air to obtain medium-temperature, high-pressure air and high-temperature steam. The replenishment subsystem replenishes the Brayton cycle subsystem with air medium according to the air flow rate of the Brayton cycle subsystem. This invention effectively solves the problems of low COP, inability to directly utilize 90°C low-temperature waste heat to generate 400°C steam, and high cost of replenishing the circulating working fluid in existing technologies.

Description

Technical Field

[0001] This invention relates to the field of energy recycling technology, and more specifically, to a high-temperature steam production system based on the air Brayton cycle. Background Technology

[0002] Industrial parks, as the core clusters of industrial production activities, undertake the important functions of large-scale production and centralized resource allocation for various industries, and are key engines for regional economic development. Currently, low-carbon transformation has become the core direction for the high-quality development of industrial parks. One of the core demands of zero-carbon industrial parks is to achieve efficient and clean energy utilization, especially by tapping into the value of idle energy sources such as low-temperature waste heat. Through technological innovation, low-grade energy can be converted into high-grade industrial energy. Utilizing low-temperature waste heat (around 90℃) to produce high-temperature steam (above 400℃) is a crucial link in meeting the needs of industrial production in the park (such as process heating and power supply), reducing dependence on fossil fuels, and achieving carbon emission reduction targets.

[0003] In related technologies, a 90°C low-temperature heat source is typically used to drive a heat pump to generate medium-temperature steam at around 200°C, which is then compressed and heated to 400°C by a compressor. This method has low energy conversion efficiency; the COP (coefficient of performance) of heat pump systems is generally below 1.6, and the overall COP of the entire process is close to 1, resulting in economic benefits far less than traditional electric heating. Furthermore, air leakage occurs during the compressor compression process, requiring air replenishment during system operation. Existing circulating working fluids are costly, leading to high maintenance costs for maintaining system operation through air replenishment. Summary of the Invention

[0004] The problem addressed by this invention is how to improve energy conversion efficiency, thereby increasing economic benefits.

[0005] To address the above problems, this invention provides a high-temperature steam production system based on the air Brayton cycle, comprising a heat exchanger, a steam generator, and a gas supply subsystem, all of which are connected to the Brayton cycle subsystem. The heat exchanger is used to heat the low-temperature, low-pressure air medium through a low-temperature heat source, and convert the low-temperature, low-pressure air medium into medium-temperature, low-pressure air. The Brayton cycle subsystem is used to heat the medium-temperature low-pressure air with the remaining medium-temperature high-pressure air from the steam generator to obtain high-temperature low-pressure air, and to compress the high-temperature low-pressure air to obtain high-temperature high-pressure air. The steam generator is used to heat the saturated water medium with the high-temperature and high-pressure air to obtain the medium-temperature and high-pressure air and high-temperature steam; The air replenishment subsystem is used to replenish the low-temperature, low-pressure air medium to the Brayton cycle subsystem according to the air flow rate of the Brayton cycle subsystem.

[0006] Optionally, the Brayton cycle subsystem is specifically used for: The medium-temperature low-pressure air is heated and compressed by the medium-temperature high-pressure air generated by the steam generator, thereby converting the medium-temperature low-pressure air into high-temperature high-pressure air, and then converting the medium-temperature high-pressure air into low-temperature high-pressure air. The low-temperature, high-pressure air is expanded to obtain the low-temperature, low-pressure air medium.

[0007] Optionally, the Brayton cycle subsystem includes an air compressor and an air expander, both of which are connected to the regenerator, and the regenerator is also connected to the heat exchanger and the steam generator respectively; The regenerator is used to heat the medium-temperature low-pressure air through the medium-temperature high-pressure air from the steam generator, convert the medium-temperature low-pressure air into high-temperature low-pressure air, and convert the medium-temperature high-pressure air into low-temperature high-pressure air; The air compressor is used to compress the high-temperature, low-pressure air to obtain the high-temperature, high-pressure air; The air expander is used to expand the low-temperature, high-pressure air to obtain the low-temperature, low-pressure air medium.

[0008] Optionally, the heat exchanger is specifically used for: The low-temperature, low-pressure air medium is heated by the low-temperature heat source, converting the low-temperature, low-pressure air medium into medium-temperature, low-pressure air, and the low-temperature heat source is converted into a low-temperature cold source.

[0009] Optionally, the gas replenishment subsystem is specifically used for: When the air flow rate decreases to a preset threshold, the low-temperature, low-pressure air medium is replenished to the Brayton cycle subsystem.

[0010] Optionally, the process of determining the heat requirement of the low-temperature heat source includes: Obtain initial design parameters; Based on the initial design parameters, iterative calculations are performed according to the pinch temperature difference of the regenerator to determine the node state parameters and the flow parameters based on the Brayton cycle. The heat demand is determined based on the node status parameters and the flow rate parameters.

[0011] Optionally, the step of determining the node state parameters and Brayton cycle-based flow parameters by iterative calculation based on the initial design parameters and the pinch temperature difference of the regenerator includes: When the pinch temperature difference is greater than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the first adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is less than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the second adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is greater than the preset temperature difference threshold, and the absolute value of the difference between the pinch temperature difference and the preset temperature difference threshold is less than the preset difference, the node status parameters and the flow parameters are determined based on the initial design parameters and the cold end outlet temperature of the regenerator at the current step size.

[0012] Optionally, the node status parameters include compressor inlet and outlet status parameters, expander inlet and outlet status parameters, steam generator hot end outlet status parameters, and heat exchanger hot end outlet status parameters. The process of determining the node status parameters and the flow rate parameters based on the initial design parameters and the current step size of the regenerator cold end outlet temperature includes: Based on the initial design parameters, and according to the current step size of the regenerator cold end outlet temperature and the compressor calculation model, the compressor outlet state parameters are determined. Based on the compressor outlet state parameters and the steam generator calculation model, the hot end outlet state parameters of the steam generator and the flow parameters are determined. The hot end outlet state parameters of the regenerator are determined by iterative calculation based on the pinch temperature difference of the regenerator. Based on the expander calculation model, the expander outlet state parameters and the heat exchanger hot end outlet state parameters are determined.

[0013] Optionally, the initial design parameters include the pinch temperature difference of the regenerator, the hot end inlet state parameters of the heat exchanger, the cold end outlet state parameters of the heat exchanger, the cold end inlet and outlet state parameters of the steam generator, the cold end inlet and outlet flow rates of the steam generator, the system compression ratio, and the system expansion ratio.

[0014] Optionally, determining the heat demand based on the node status parameters and the flow parameters includes: The cold end inlet state parameters of the heat exchanger are determined based on the hot end outlet state parameters of the regenerator and the expansion machine calculation model. The heat demand is determined based on the inlet state parameters of the heat exchanger cold end, the flow rate parameters, and the outlet temperature of the heat exchanger cold end.

[0015] The beneficial effects of the high-temperature steam production system based on the Brayton cycle of the present invention are: By using a heat exchanger connected to the Brayton cycle subsystem, a 90°C low-temperature heat source is used to heat the low-temperature, low-pressure air medium and convert it into medium-temperature, low-pressure air. This successfully and efficiently introduces low-temperature waste heat into the system, providing a suitable initial energy carrier for the subsequent generation of high-temperature steam. This solves the prerequisite problem that existing technologies cannot directly rely on 90°C low-temperature waste heat to generate 400°C high-temperature steam. Next, the Brayton cycle subsystem uses the remaining medium-temperature, high-pressure air from the steam generator to heat the aforementioned medium-temperature, low-pressure air to obtain high-temperature, low-pressure air, which is then compressed to obtain high-temperature, high-pressure air. This not only recovers the waste heat from the steam generator, reduces energy loss, and improves energy utilization efficiency, avoiding the low COP problem caused by energy waste in existing technologies, but also eliminates the cumbersome process of first generating approximately 200°C steam and then performing secondary compression, thus paving the way for the direct production of high-temperature steam. The steam provides a crucial high-temperature, high-pressure heat source. Subsequently, the steam generator, connected to the Brayton cycle subsystem, uses this high-temperature, high-pressure air to heat the saturated water medium, directly producing high-temperature steam. This precisely solves the core problem of existing technologies that cannot directly generate high-temperature steam above 400°C using 90°C low-temperature waste heat. Moreover, the energy conversion efficiency during heat exchange is higher, further contributing to the improvement of the system's COP. Finally, the air replenishment subsystem replenishes the Brayton cycle subsystem with low-temperature, low-pressure air medium according to the air flow rate, specifically addressing the gas leakage problem that exists during compressor operation. This enables on-demand air replenishment, avoiding indiscriminate air replenishment and the additional economic cost waste caused by high-cost circulating working fluids. This ensures stable system operation while controlling costs. Through the sequential connection and coordination of each step, the technical difficulties of low COP, inability to directly utilize low-temperature waste heat to generate 400°C high-temperature steam, and high air replenishment costs in existing technologies are effectively solved. Attached Figure Description

[0016] Figure 1 One of the structural schematic diagrams of a high-temperature steam production system based on the air Brayton cycle provided in an embodiment of the present invention; Figure 2 This is the second schematic diagram of a high-temperature steam production system based on the air Brayton cycle provided in an embodiment of the present invention. Detailed Implementation

[0017] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0018] It should be understood that the various steps described in the method embodiments of the present invention may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of the present invention is not limited in this respect.

[0019] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used only to distinguish different devices, modules, or units, and are not intended to limit the order of functions performed by these devices, modules, or units or their interdependencies.

[0020] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0021] The names of the messages or information exchanged between the multiple devices in the embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of these messages or information.

[0022] like Figure 1 As shown in the figure, an embodiment of the present invention provides a high-temperature steam production system based on the air Brayton cycle, including a heat exchanger, a steam generator, and a gas supply subsystem, all of which are connected to the Brayton cycle subsystem.

[0023] Specifically, heat exchangers ( Figure 2 HR), steam generator ( Figure 2 The SG and the air replenishment subsystem are connected to the Brayton cycle subsystem via high-temperature resistant pipelines. The connection method can be flange connection or welding fixation to ensure the sealing and pressure resistance of the system during operation. The heat exchanger can be a type that is suitable for heat transfer from a low-temperature heat source of about 90°C, and the steam generator can be a device with high-efficiency heat exchange capacity. The air replenishment subsystem is connected to the Brayton cycle subsystem via branch pipelines to ensure that the replenished low-temperature and low-pressure air medium can be smoothly connected to the circulation process.

[0024] The heat exchanger is used to heat the low-temperature, low-pressure air medium through a low-temperature heat source, and convert the low-temperature, low-pressure air medium into medium-temperature, low-pressure air.

[0025] Specifically, the heat exchanger is supplied with 90°C industrial low-temperature waste heat (adaptable to various low-temperature waste heat resources within the 85-95°C range, such as industrial exhaust waste heat, wastewater waste heat, etc.) as a low-temperature heat source. Dry, clean, low-temperature, low-pressure air is introduced to the cold end of the heat exchanger. As the low-temperature, low-pressure air flows through the cold end of the heat exchanger, it fully exchanges heat with the low-temperature heat source at the hot end, raising the temperature of the low-temperature, low-pressure air from its initial temperature (e.g., 90°C). Figure 2 Node 7 (approximately -20.264℃) is heated to approximately 80℃ (this temperature can be adjusted within the 75-85℃ range, corresponding to...). Figure 2 Node 8) ultimately converts the air into medium-temperature, low-pressure air with a stable pressure of 1.5-1.6 MPa and a flow rate suitable for subsequent circulation needs. The heat exchanger in this embodiment can also be replaced with a plate heat exchanger or a spiral plate heat exchanger depending on the spatial layout and heat exchange efficiency requirements of the actual application scenario. Plate heat exchangers offer higher heat exchange efficiency and smaller size, making them suitable for space-constrained conditions. Spiral plate heat exchangers, on the other hand, have better anti-fouling performance and are suitable for low-temperature heat sources containing a small amount of impurities. Both can achieve the core function of heating low-temperature, low-pressure air media through a low-temperature heat source and converting it into medium-temperature, low-pressure air.

[0026] The Brayton cycle subsystem is used to heat the medium-temperature low-pressure air with the remaining medium-temperature high-pressure air from the steam generator to obtain high-temperature low-pressure air, and then compress the high-temperature low-pressure air to obtain high-temperature high-pressure air.

[0027] Specifically, the Brayton cycle subsystem integrates a regenerator, compressor, and expander. The compressor's compression ratio can be set to 4 (fine-tuned within the range of 3.8-4.2 to adapt to different pressure requirements), and the expander's expansion ratio can be set to 4 to match the compression ratio. During operation, this subsystem first receives medium-temperature, high-pressure air (approximately 195.6℃, 8MPa) discharged from the steam generator via the regenerator. Figure 2 Node 4 parameters), and utilize this air to supply medium-temperature, low-pressure air from the heat exchanger (corresponding to Figure 2 Node 8 parameters) are heated to fully recover the waste heat from the medium-temperature, high-pressure air, yielding high-temperature, low-pressure nitrogen (corresponding to Figure 2 Node 6 parameters); High-temperature, low-pressure air enters the compressor, which compresses the air to approximately 433.25℃ according to the set compression ratio (adjustable within the range of 430-435℃, corresponding to...). Figure 2 The high-temperature, high-pressure air (node ​​3 parameters) with a pressure of 8MPa is compressed. During the compression process, the compressor's power consumption is precisely controlled based on the compressor's calculation model, combined with the changes in air enthalpy and isentropic efficiency. At the same time, the expander operates according to the set expansion ratio, expanding the air in the circulation to do work, which helps the system's energy balance. The entire subsystem achieves the function of preheating medium-temperature, low-pressure air with medium-temperature, high-pressure air and compressing it to obtain high-temperature, high-pressure air through the coordinated operation of various components.

[0028] The steam generator is used to heat the saturated water medium with the high-temperature and high-pressure air to obtain the medium-temperature and high-pressure air and high-temperature steam.

[0029] Specifically, the hot-end inlet of the steam generator is supplied with high-temperature, high-pressure air (approximately 433.25℃ and 8MPa) from the Brayton cycle subsystem. Figure 2 Node 3), the cold end inlet is supplied with industrial saturated water medium (temperature around 180℃, pressure 1.56MPa, corresponding to...). Figure 2 Node 2). During operation, high-temperature, high-pressure air flows at the hot end, while saturated water flows at the cold end, resulting in efficient heat exchange. The heat exchange area and fluid velocity can be precisely controlled according to the steam generator calculation model, heating the saturated water to 400℃ (adjustable within the range of 400-420℃). Figure 2 Node 1) High-temperature superheated steam with a pressure of 1.56 MPa (adaptable to the 1.5-1.6 MPa range) meets industrial steam requirements; simultaneously, the high-temperature, high-pressure air cools to approximately 195.6℃ after heat exchange (it can fluctuate within the 190-200℃ range, corresponding to...) Figure 2 At node 4, the pressure is maintained at around 8 MPa, forming medium-temperature high-pressure air that flows back to the regenerator of the Brayton cycle subsystem, realizing the recycling and utilization of heat.

[0030] The air replenishment subsystem is used to replenish the low-temperature, low-pressure air medium to the Brayton cycle subsystem according to the air flow rate of the Brayton cycle subsystem.

[0031] Specifically, such as Figure 2 As shown, the air replenishment subsystem is installed in the pipeline between the Brayton cycle subsystem and the heat exchanger. It monitors the air flow rate in the system in real time and compares it with the preset standard flow rate range to determine if there is a problem of insufficient flow caused by gas leakage. When the air flow rate in the circulation system is detected to be lower than the preset value, dry and clean low-temperature and low-pressure air medium is replenished into the pipeline between the Brayton cycle subsystem and the heat exchanger. The replenishment amount is adaptively adjusted according to the flow rate difference and controlled within the range of 1%-5% of the circulation flow rate to ensure sufficient low-temperature and low-pressure air medium in the circulation system and maintain stable system operation. At the same time, since the low-temperature and low-pressure air medium is readily available, no additional working fluid procurement costs are required.

[0032] In this embodiment, a heat exchanger connected to the Brayton cycle subsystem heats the low-temperature, low-pressure air medium using a 90°C low-temperature heat source, converting it into medium-temperature, low-pressure air. This successfully and efficiently introduces low-temperature waste heat into the system, providing a suitable initial energy carrier for the subsequent generation of high-temperature steam. This solves the prerequisite problem of existing technologies being unable to directly generate 400°C high-temperature steam using 90°C low-temperature waste heat. Next, the Brayton cycle subsystem uses the remaining medium-temperature, high-pressure air from the steam generator to heat the aforementioned medium-temperature, low-pressure air to obtain high-temperature, low-pressure air, which is then compressed to obtain high-temperature, high-pressure air. This recovers the waste heat from the steam generator, reduces energy loss, improves energy utilization efficiency, and avoids the low COP problem caused by energy waste in existing technologies. Furthermore, the "waste heat preheating + direct compression" method eliminates the cumbersome process of first generating approximately 200°C steam and then performing secondary compression, providing a direct production... High-temperature steam provides a crucial high-temperature, high-pressure heat source. Subsequently, a steam generator connected to the Brayton cycle subsystem uses this high-temperature, high-pressure air to heat a saturated water medium, directly producing high-temperature steam. This precisely solves the core problem of existing technologies being unable to directly generate high-temperature steam above 400°C using 90°C low-temperature waste heat, and also achieves higher energy conversion efficiency during heat exchange, further contributing to the improvement of the system's COP. Finally, the air replenishment subsystem replenishes the Brayton cycle subsystem with low-temperature, low-pressure air medium according to the air flow rate, specifically addressing the gas leakage problem that exists during compressor operation. This enables on-demand air replenishment, avoiding indiscriminate air replenishment and the additional economic cost waste caused by high-cost circulating working fluids. This ensures stable system operation while controlling costs. Through the sequential connection and coordination of each step, the technical challenges of low COP, inability to directly utilize low-temperature waste heat to generate 400°C high-temperature steam, and high air replenishment costs in existing technologies are effectively solved.

[0033] Optionally, the Brayton cycle subsystem is specifically used for: The medium-temperature low-pressure air is heated and compressed by the medium-temperature high-pressure air generated by the steam generator, thereby converting the medium-temperature low-pressure air into high-temperature high-pressure air, and then converting the medium-temperature high-pressure air into low-temperature high-pressure air. The low-temperature, high-pressure air is expanded to obtain the low-temperature, low-pressure air medium.

[0034] Specifically, the Brayton cycle subsystem performs the following operations: First, it receives medium-temperature, high-pressure air (approximately 195.6397°C, 8 MPa, adaptable to a range of 190-200°C and 7.5-8.5 MPa) discharged from the steam generator. This medium-temperature, high-pressure air is then used to heat medium-temperature, low-pressure air (approximately 80°C, 2 MPa, adjustable to a range of 75-85°C and 1.8-2.2 MPa) from the heat exchanger. Sufficient heat transfer is ensured during the heating process. Subsequently, the heated high-temperature, low-pressure air is converted into high-temperature, high-pressure air through compression. The temperature of this high-temperature, high-pressure air can reach 433.252 °C. The temperature is around 3℃ and the pressure is stabilized at 8MPa (which can be finely adjusted within the range of 430-435℃ and 7.8-8.2MPa). At the same time, the medium-temperature high-pressure air that has participated in the heating releases heat, and its temperature drops to around 89.3873℃ while the pressure is maintained at 8MPa, thus transforming into low-temperature high-pressure air (which can be adapted within the range of 85-90℃ and 7.6-8.1MPa). Finally, this low-temperature high-pressure air is expanded to obtain a low-temperature low-pressure air medium with a temperature of approximately -20.264℃ and a pressure of 2MPa (which can be adjusted within the range of -25 to -18℃ and 1.9-2.1MPa), so that it can be reintroduced into the heat exchanger to participate in the next cycle. By heating medium-temperature low-pressure air with medium-temperature high-pressure air and then compressing it, the waste heat of the air discharged from the steam generator is effectively recovered, reducing the energy consumption of the compression process. At the same time, the medium-temperature high-pressure air is converted into low-temperature high-pressure air and expanded to recover energy, forming a recycling of the low-temperature low-pressure air medium, avoiding the waste of working fluid, further improving the system's energy utilization rate, and helping the system's COP to remain stable at a relatively high level of 1.6867.

[0035] Optionally, such as Figure 2 As shown, the Brayton cycle subsystem includes an air compressor and an air expander, both of which are connected to the regenerator. The regenerator is also connected to the heat exchanger and the steam generator, respectively. The regenerator is used to heat the medium-temperature low-pressure air through the medium-temperature high-pressure air from the steam generator, convert the medium-temperature low-pressure air into high-temperature low-pressure air, and convert the medium-temperature high-pressure air into low-temperature high-pressure air; The air compressor is used to compress the high-temperature, low-pressure air to obtain the high-temperature, high-pressure air; The air expander is used to expand the low-temperature, high-pressure air to obtain the low-temperature, low-pressure air medium.

[0036] Specifically, the Brayton cycle subsystem includes a regenerator ( Figure 2 RHA), air compressor ( Figure 2 CA) and air expander ( Figure 2The regenerator (TA) is connected to the heat exchanger, steam generator, air compressor, and air expander via pressure-resistant sealed pipes (the connection method can be flange connection or welding fixation to ensure sealing under high-pressure conditions). The regenerator can be a plate regenerator or, depending on the waste heat recovery requirements, a regenerative regenerator. The air compressor is a screw compressor, which can be replaced by a centrifugal compressor (compression ratio controlled at around 4, adjustable within the range of 3.8-4.2). The air expander is an axial flow expander, which can be replaced by a centrifugal expander (expansion ratio and compression ratio matched and set at 4). In operation, the regenerator receives medium-temperature, low-pressure air (approximately 80°C, 2MPa) from the heat exchanger and medium-temperature, high-pressure air (approximately 195.6397°C, 8MPa) from the steam generator. Through counter-current heat exchange between the two types of air within the regenerator, the medium-temperature, low-pressure air is heated to approximately 190.5768°C and 2MPa, converting it into high-temperature, low-pressure air (adjustable within the range of 185-195°C and 1.9-2.1MPa). Simultaneously, the medium-temperature, high-pressure air is cooled to approximately 89.3873°C and 8MPa, converting it into low-temperature, high-pressure air. Compressed air (adaptable to 85-90℃, 7.8-8.2MPa range); the air compressor receives high-temperature, low-pressure air from the regenerator and compresses it according to a set compression ratio, converting it into high-temperature, high-pressure air at approximately 433.2523℃ and 8MPa; the air expander receives low-temperature, high-pressure air from the regenerator and expands it to produce low-temperature, low-pressure air at approximately -20.264℃ and 2MPa (adjustable within the range of -25 to -18℃, 1.9-2.1MPa), which is then circulated back to the heat exchanger. Through the clear division of labor and coordinated connection of the regenerator, air compressor, and air expander, the orderly conversion of the low-temperature, low-pressure air medium between different states is achieved. The regenerator's waste heat recovery function further reduces the compressor's compression load, the air expander's expansion work assists in system energy balance, and the adaptable connection of each component ensures smooth circulation, significantly improving system stability and energy utilization efficiency.

[0037] Optionally, the heat exchanger is specifically used for: The low-temperature, low-pressure air medium is heated by the low-temperature heat source, converting the low-temperature, low-pressure air medium into medium-temperature, low-pressure air, and the low-temperature heat source is converted into a low-temperature cold source.

[0038] Specifically, the heat exchanger performs the following operations: It receives industrial low-temperature waste heat at approximately 90°C as a low-temperature heat source (suitable for various low-temperature waste heat sources within the 85-95°C range, such as waste heat from industrial wastewater and exhaust gas), while simultaneously introducing low-temperature, low-pressure air from an air expander (temperature approximately -20.264°C, pressure 2MPa). The heat exchanger adopts a shell-and-tube structure (which can be replaced by a plate heat exchanger or a spiral plate heat exchanger; plate heat exchangers have higher heat exchange efficiency, while spiral plate heat exchangers have better anti-fouling performance). Heat exchange is conducted through counter-current flow (which can be replaced by co-current flow heat exchange; counter-current flow heat exchange is more efficient). This process improves heat exchange efficiency, enabling full heat transfer between the low-temperature heat source and the low-temperature, low-pressure air medium. The low-temperature, low-pressure air medium is heated to approximately 80°C and 2MPa, converting it into medium-temperature, low-pressure air (adjustable within the range of 75-85°C and 1.9-2.1MPa). Simultaneously, the low-temperature heat source releases heat, causing its temperature to drop to approximately -15.2636°C and its pressure to 1.56MPa, transforming it into a low-temperature cold source (adjustable within the range of -18 to -12°C and 1.5-1.6MPa). This cold source can be directly used for industrial refrigeration or recycled for storage. By simultaneously heating and converting the low-temperature, low-pressure air medium, the low-temperature heat source is transformed into a usable low-temperature cold source, achieving cascaded utilization of low-temperature waste heat, improving overall energy efficiency, and avoiding waste caused by solely using the low-temperature heat source for energy supply. This further aligns with the energy efficiency requirements of zero-carbon industrial parks.

[0039] Optionally, the gas replenishment subsystem is specifically used for: When the air flow rate decreases to a preset threshold, the low-temperature, low-pressure air medium is replenished to the Brayton cycle subsystem.

[0040] Specifically, the air replenishment subsystem is equipped with a flow monitoring module (which can be a vortex flow sensor or a differential pressure flow sensor) to monitor the air flow rate within the Brayton cycle subsystem in real time and preset an air flow rate threshold (this threshold is set at 95% of the system's standard circulation flow rate and can be adjusted within the range of 90%-98% according to actual operating conditions). When the flow monitoring module detects that the air flow rate within the Brayton cycle subsystem is lower than this preset threshold, or that the air flow rate has decreased by 5%, it determines that there is a gas leak in the system causing insufficient working fluid. The air replenishment subsystem then initiates the air replenishment procedure, replenishing the Brayton cycle subsystem with dry, clean, low-temperature, low-pressure air medium through the air replenishment pipeline. During the air replenishment process, the flow rate changes are monitored in real time. When the air flow rate rises above the preset threshold, the air replenishment subsystem automatically stops replenishing the air. The air replenishment control method can be PLC automatic control or manual control (suitable for small experimental devices or special operating conditions). Precise triggering of air replenishment is achieved by setting a preset flow threshold, avoiding the waste of working fluid and increased costs caused by indiscriminate continuous air replenishment. Air is replenished only when the flow is insufficient, which not only ensures the sufficiency of working fluid in the Brayton cycle subsystem and maintains the stable operation of the system, but also minimizes the additional air replenishment cost, which is in line with the advantage of easy access to air as a working fluid.

[0041] Optionally, the process of determining the heat requirement of the low-temperature heat source includes: Obtain initial design parameters; Based on the initial design parameters, iterative calculations are performed according to the pinch temperature difference of the regenerator to determine the node state parameters and the flow parameters based on the Brayton cycle. The heat demand is determined based on the node status parameters and the flow rate parameters.

[0042] Specifically, the initial design parameters of the system are first obtained (such as compression and expansion ratios, pinch point temperature differences, and basic parameters related to the temperature, pressure, and flow rate of the heat exchanger and steam generator). Based on these initial design parameters, iterative calculations are performed using the pinch point temperature difference of the regenerator. By continuously adjusting the relevant parameters, the state parameters of each node in the system (such as the temperature, pressure, and flow rate of each node) and the flow rate parameters based on the Brayton cycle (the flow rate of the circulating air) are gradually determined. After the node state parameters and flow rate parameters are determined, the heat demand required by the low-temperature heat source is further derived using relevant calculation models. The iterative calculations can be performed automatically using computer programming. This logical flow of initial parameter preparation, iterative calculation to determine key parameters, and derivation of heat demand ensures a precise match between the heat supply from the low-temperature heat source and the system's operational needs. This avoids insufficient heat supply leading to the system failing to reach its designed capacity, or excessive heat supply causing energy waste, thus improving the system's compatibility with the low-temperature heat source and ensuring efficient and stable system operation.

[0043] Optionally, the step of determining the node state parameters and Brayton cycle-based flow parameters by iterative calculation based on the initial design parameters and the pinch temperature difference of the regenerator includes: When the pinch temperature difference is greater than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the first adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is less than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the second adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is greater than the preset temperature difference threshold, and the absolute value of the difference between the pinch temperature difference and the preset temperature difference threshold is less than the preset difference, the node status parameters and the flow parameters are determined based on the initial design parameters and the cold end outlet temperature of the regenerator at the current step size.

[0044] Specifically, based on the initial design parameters, the process of iteratively calculating the node status parameters and flow parameters according to the pinch temperature difference of the regenerator is as follows: the preset temperature difference threshold is 5K (which can be adjusted in the range of 4-6K according to the heat exchange efficiency requirements), and the preset difference is 0.01K (which can be adjusted in the range of 0.005-0.02K to meet the accuracy requirements). When the pinch temperature difference of the regenerator is detected to be greater than the preset temperature difference threshold, the first adjustment strategy (i.e., increasing the cold end outlet temperature of the regenerator by 1°C per step, which can be replaced by an adjustment of 0.5°C or 2°C per step) is adopted to adjust the cold end outlet temperature of the regenerator. The new pinch temperature difference is then recalculated and determined based on the adjusted cold end outlet temperature. When the pinch temperature difference is detected to be less than the preset temperature difference threshold, the second adjustment strategy (i.e., decreasing the cold end outlet temperature of the regenerator by 1°C per step, which can be replaced by an adjustment of 0.5°C or 2°C per step) is adopted to adjust the cold end outlet temperature of the regenerator. The pinch temperature difference is recalculated again. The above adjustment process is repeated until the pinch temperature difference is greater than the preset temperature difference threshold, and the absolute value of the difference between the pinch temperature difference and the preset temperature difference threshold is less than the preset difference value. At this point, the adjustment stops, and the node state parameters and the flow parameters based on the Brayton cycle are finally determined based on the initial design parameters and the cold end outlet temperature of the regenerator at the current step size. By employing differentiated adjustment strategies for different pinch temperature differences, the iterative calculations are made precise and efficient, ensuring that the pinch temperature difference of the regenerator remains stable within the optimal range. This improves the heat exchange efficiency of the regenerator and lays the foundation for improving the overall energy utilization of the system. At the same time, the iteration accuracy can be flexibly adjusted through preset differences to adapt to the needs of different scenarios.

[0045] Optionally, the node status parameters include compressor inlet and outlet status parameters, expander inlet and outlet status parameters, steam generator hot end outlet status parameters, and heat exchanger hot end outlet status parameters. The process of determining the node status parameters and the flow rate parameters based on the initial design parameters and the current step size of the regenerator cold end outlet temperature includes: Based on the initial design parameters, and according to the current step size of the regenerator cold end outlet temperature and the compressor calculation model, the compressor outlet state parameters are determined. Based on the compressor outlet state parameters and the steam generator calculation model, the hot end outlet state parameters of the steam generator and the flow parameters are determined. The hot end outlet state parameters of the regenerator are determined by iterative calculation based on the pinch temperature difference of the regenerator. Based on the expander calculation model, the expander outlet state parameters and the heat exchanger hot end outlet state parameters are determined.

[0046] Specifically, inlet and outlet state parameters refer to the inlet state parameters and outlet state parameters. State parameters include parameters such as temperature, pressure, flow rate, and enthalpy, which represent the node state. Furthermore, the compressor and expander each have only one set of inlet and outlet. The heat exchanger, regenerator, and steam generator each have hot-end and cold-end inlet and outlet, respectively. The expander outlet is the cold-end inlet of the heat exchanger, the hot-end outlet of the regenerator is the expander inlet, the compressor inlet is the cold-end outlet of the regenerator, and the compressor outlet is the hot-end inlet of the steam generator. Node state parameters include compressor inlet and outlet state parameters, expander inlet and outlet state parameters, steam generator hot-end outlet state parameters, and heat exchanger hot-end outlet state parameters. Based on the initial design parameters, the process of determining the node state parameters and flow parameters according to the current step size of the regenerator cold end outlet temperature is as follows: First, using the initial design parameters and the current step size of the regenerator cold end outlet temperature as input conditions, substitute them into the compressor calculation model (this model uses isentropic efficiency and enthalpy change as the core calculation basis, and can be replaced by a compressor calculation model that includes variable efficiency), and calculate the compressor outlet temperature, pressure, enthalpy, and other state parameters; then, substitute the compressor outlet state parameters into the steam generator calculation model (which uses heat transfer balance and fluid flow characteristics as the core calculation, and can be replaced by a steam generator calculation model that includes heat transfer coefficient correction), and calculate the... The state parameters of the steam generator's hot-end outlet, such as temperature, pressure, and enthalpy, along with airflow parameters based on the Brayton cycle, are used. Combined with the system's loop logic, the temperature and pressure parameters of the heat exchanger's cold-end outlet and hot-end outlet are derived and determined. Then, based on the regenerator pinch-point temperature difference, iterative calculations are performed to derive and determine the regenerator's hot-end outlet state parameters. Next, based on the expander calculation model, the expander outlet state parameters are determined, along with the heat exchanger's hot-end outlet state parameters, i.e., the temperature and pressure parameters of the heat exchanger's hot-end outlet. The determination of these state parameters is performed simultaneously with the regenerator's iterative calculations. When the regenerator's pinch-point temperature difference meets a preset value, the state parameters for each node are obtained. This embodiment clarifies the specific types of node state parameters and determines each parameter step-by-step through a targeted calculation model, ensuring the accuracy and logic of the parameter calculations. This provides reliable data support for determining subsequent heat demand. Furthermore, the calculation model can select alternative schemes based on actual operating conditions, improving the adaptability of the parameter calculations.

[0047] For example, the compressor calculation model includes: ; in, The isentropic efficiency of the compressor, expressed as a percentage. h out,is This represents the enthalpy of the outlet under isentropic efficiency, expressed in J / g. h in The enthalpy value at the inlet. h outThe enthalpy value for exports. The power consumption of the compressor is expressed in watts (W). The flow rate parameter of the compressor based on the Brayton cycle is expressed in kg / s.

[0048] The calculation model for the steam generator includes: ; in, Heat, measured in W. This refers to the hot-end flow rate parameter, in kg / s. h hot,in The enthalpy value at the hot end inlet. h hot,out The enthalpy value at the hot end outlet. This refers to the cold end flow rate parameter, in kg / s. h cold,out The enthalpy value at the cold end outlet. h cold,in Let be the enthalpy of the cold end inlet, n be the number of differentials in the heat exchanger, and i be each part of the differential. Let be the enthalpy value of the i-th difference portion. Let be the enthalpy of the (i+1)th difference portion. For the pinch point temperature difference, Let be the hot-end temperature of the i-th differential part. Let be the cold end temperature of the i-th differential part. For unknown flow parameters, Given flow parameters.

[0049] For example, the pinch temperature difference can be determined based on a regenerator calculation model, which includes: ; in, This represents the enthalpy difference.

[0050] For example, Figure 2 Node 1 is the cold end outlet of the steam generator SG, Node 2 is the cold end inlet of the steam generator SG, Node 3 is the hot end inlet of the steam generator SG, which is also the CA outlet of the air compressor, Node 4 is the hot end outlet of the steam generator SG, which is also the hot end inlet of the regenerator RHA, Node 5 is the hot end outlet of the regenerator RHA, which is also the TA inlet of the air expander, Node 6 is the cold end outlet of the regenerator RHA, which is also the CA inlet of the air compressor, Node 7 is the cold end inlet of the heat exchanger HR, which is also the TA outlet of the air expander, Node 8 is the cold end outlet of the heat exchanger HR, which is also the cold end inlet of the regenerator RHA, Node 9 is the hot end inlet of the heat exchanger HR, and Node 10 is the hot end outlet of the heat exchanger HR.

[0051] For example, Figure 2The state parameters of each node are shown in the table below:

[0052] Optionally, the initial design parameters include the pinch temperature difference of the regenerator, the hot end inlet state parameters of the heat exchanger, the cold end outlet state parameters of the heat exchanger, the cold end inlet and outlet state parameters of the steam generator, the cold end inlet and outlet flow rates of the steam generator, the system compression ratio, and the system expansion ratio.

[0053] Specifically, the initial design parameters include: the inlet state parameters of the heat exchanger (e.g., the temperature, pressure, and flow rate of the low-temperature heat source entering the heat exchanger, i.e.) Figure 2 Temperature, pressure, and flow rate at node 9), and cold-end outlet state parameters of the heat exchanger (e.g., temperature, pressure, and flow rate of the low-temperature, low-pressure air medium leaving the heat exchanger, i.e.) Figure 2 Temperature, pressure, and flow rate at node 8), and cold-end inlet state parameters of the steam generator (i.e., temperature, pressure, and flow rate when saturated water medium enters the steam generator, i.e.) Figure 2 Temperature, pressure, and flow rate at node 2), and cold-end outlet state parameters of the steam generator (i.e., temperature, pressure, and flow rate of the saturated water medium leaving the steam generator, i.e.) Figure 2 The initial design parameters include the temperature, pressure, and flow rate at node 1; the inlet flow rate of the steam generator at the cold end (e.g., the flow rate when saturated water enters, which can be preset based on flow rate and pipe diameter); the outlet flow rate of the steam generator at the cold end (e.g., the flow rate when saturated water leaves, which can be preset based on flow rate and pipe diameter); the system compression ratio; and the system expansion ratio. The initial design parameters can be preset using theoretical calculations or, alternatively, using preset methods based on experimental data under similar operating conditions. The advantages of this claim are: it clarifies the specific composition of the initial design parameters, providing clear and accurate basic inputs for iterative calculations and subsequent parameter calculations, avoiding calculation errors caused by ambiguity in the initial parameters, ensuring the smoothness of the entire parameter determination process and the reliability of the results, and allowing for flexible preset of the initial parameters, thus improving the adaptability of the system design.

[0054] Optionally, determining the heat demand based on the node status parameters and the flow parameters includes: The cold end inlet state parameters of the heat exchanger are determined based on the hot end outlet state parameters of the regenerator and the expansion machine calculation model. The heat demand is determined based on the inlet state parameters of the heat exchanger cold end, the flow rate parameters, and the outlet temperature of the heat exchanger cold end.

[0055] Specifically, the determined hot-end outlet state parameters of the regenerator (i.e., the inlet state parameters of the expander) are first extracted. These parameters are then substituted into the expander calculation model (which uses the expansion ratio and enthalpy change as the core calculation basis and can be replaced by an expander calculation model that includes adiabatic efficiency). The cold-end inlet state parameters of the heat exchanger (i.e., the temperature and pressure of the low-temperature, low-pressure air medium when it enters the heat exchanger, such as -20.264℃ and 2MPa) are calculated. Then, based on the cold-end inlet state parameters, flow parameters, and the determined cold-end outlet temperature of the heat exchanger (e.g., 80℃), the heat demand required by the low-temperature heat source is calculated using methods such as the heat balance formula. This ensures that the heat supply of the low-temperature heat source can meet the heat demand of the low-temperature, low-pressure air medium from the inlet temperature of the heat exchanger to the outlet temperature. By accurately deriving the inlet state parameters of the heat exchanger cold end using an expander calculation model, and then combining this with the outlet temperature of the heat exchanger cold end to calculate the heat demand, a logical closed-loop calculation process is formed. This ensures the accuracy of the heat demand calculation, avoids the problem of heat supply being out of sync with actual demand, provides a reliable basis for the selection and matching of low-temperature heat sources, and further ensures that the system can stably produce high-temperature steam above 400℃.

[0056] For example, the expander computational model includes: ; in, The isentropic efficiency of the expander, expressed as %. h out,is This represents the enthalpy of the outlet under isentropic efficiency, expressed in J / g. h in The enthalpy value at the inlet. h out The enthalpy value for exports. The power consumption of the expander is expressed in watts (W). The flow parameters for the expander, based on the Brayton cycle, are expressed in kg / s.

[0057] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc. In this application, the units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of the embodiments of the present invention according to actual needs. Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units can be implemented in hardware or as software functional units.

[0058] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A high-temperature steam production system based on an air Brayton cycle, characterized in that, This includes heat exchangers, steam generators, and make-up gas subsystems, all of which are connected to the Brayton cycle subsystem. The heat exchanger is used to heat the low-temperature, low-pressure air medium through a low-temperature heat source, and convert the low-temperature, low-pressure air medium into medium-temperature, low-pressure air. The Brayton cycle subsystem is used to heat the medium-temperature low-pressure air with the remaining medium-temperature high-pressure air from the steam generator to obtain high-temperature low-pressure air, and to compress the high-temperature low-pressure air to obtain high-temperature high-pressure air. The steam generator is used to heat the saturated water medium with the high-temperature and high-pressure air to obtain the medium-temperature and high-pressure air and high-temperature steam; The air replenishment subsystem is used to replenish the low-temperature, low-pressure air medium to the Brayton cycle subsystem according to the air flow rate of the Brayton cycle subsystem.

2. The high-temperature steam production system based on the Brayton cycle according to claim 1, characterized in that, The Brayton cycle subsystem is specifically used for: The medium-temperature low-pressure air is heated and compressed by the medium-temperature high-pressure air generated by the steam generator, thereby converting the medium-temperature low-pressure air into high-temperature high-pressure air, and then converting the medium-temperature high-pressure air into low-temperature high-pressure air. The low-temperature, high-pressure air is expanded to obtain the low-temperature, low-pressure air medium.

3. The high-temperature steam production system based on the Brayton cycle according to claim 2, characterized in that, The Brayton cycle subsystem includes an air compressor and an air expander, both of which are connected to the regenerator. The regenerator is also connected to the heat exchanger and the steam generator, respectively. The regenerator is used to heat the medium-temperature low-pressure air through the medium-temperature high-pressure air from the steam generator, convert the medium-temperature low-pressure air into the high-temperature low-pressure air, and convert the medium-temperature high-pressure air into the low-temperature high-pressure air; The air compressor is used to compress the high-temperature, low-pressure air to obtain the high-temperature, high-pressure air; The air expander is used to expand the low-temperature, high-pressure air to obtain the low-temperature, low-pressure air medium.

4. The high-temperature steam production system based on the Brayton cycle according to claim 1, characterized in that, The heat exchanger is specifically used for: The low-temperature, low-pressure air medium is heated by the low-temperature heat source, converting the low-temperature, low-pressure air medium into medium-temperature, low-pressure air, and the low-temperature heat source is converted into a low-temperature cold source.

5. The high-temperature steam production system based on the Brayton cycle according to claim 1, characterized in that, The gas replenishment subsystem is specifically used for: When the air flow rate decreases to a preset threshold, the low-temperature, low-pressure air medium is replenished to the Brayton cycle subsystem.

6. The high-temperature steam production system based on the Brayton cycle according to claim 3, characterized in that, The process of determining the heat requirement of the low-temperature heat source includes: Obtain initial design parameters; Based on the initial design parameters, iterative calculations are performed according to the pinch temperature difference of the regenerator to determine the node state parameters and the flow parameters based on the Brayton cycle. The heat demand is determined based on the node status parameters and the flow rate parameters.

7. The high-temperature steam production system based on the Brayton cycle according to claim 6, characterized in that, The process of determining node state parameters and Brayton cycle-based flow parameters through iterative calculations based on the initial design parameters and the pinch temperature difference of the regenerator includes: When the pinch temperature difference is greater than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the first adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is less than the preset temperature difference threshold, the cold end outlet temperature of the regenerator is adjusted using the second adjustment strategy, and the pinch temperature difference is re-determined based on the adjusted cold end outlet temperature of the regenerator. When the pinch temperature difference is greater than the preset temperature difference threshold, and the absolute value of the difference between the pinch temperature difference and the preset temperature difference threshold is less than the preset difference, the node status parameters and the flow parameters are determined based on the initial design parameters and the cold end outlet temperature of the regenerator at the current step size.

8. The high-temperature steam production system based on the Brayton cycle according to claim 7, characterized in that, The node status parameters include compressor inlet and outlet status parameters, expander inlet and outlet status parameters, steam generator hot end outlet status parameters, and heat exchanger hot end outlet status parameters. The process of determining the node status parameters and the flow rate parameters based on the initial design parameters and the current step size of the regenerator cold end outlet temperature includes: Based on the initial design parameters, and according to the current step size of the regenerator cold end outlet temperature and the compressor calculation model, the compressor outlet state parameters are determined. Based on the compressor outlet state parameters and the steam generator calculation model, the hot end outlet state parameters of the steam generator and the flow parameters are determined. The hot end outlet state parameters of the regenerator are determined by iterative calculation based on the pinch temperature difference of the regenerator. Based on the expander calculation model, the expander outlet state parameters and the heat exchanger hot end outlet state parameters are determined.

9. The high-temperature steam production system based on the Brayton cycle according to claim 8, characterized in that, The initial design parameters include the pinch temperature difference of the regenerator, the hot end inlet state parameters of the heat exchanger, the cold end outlet state parameters of the heat exchanger, the cold end inlet and outlet state parameters of the steam generator, the cold end inlet and outlet flow rates of the steam generator, the system compression ratio, and the system expansion ratio.

10. The high-temperature steam production system based on the Brayton cycle according to claim 9, characterized in that, Determining the heat demand based on the node status parameters and the flow parameters includes: The cold end inlet state parameters of the heat exchanger are determined based on the hot end outlet state parameters of the regenerator and the expansion machine calculation model. The heat demand is determined based on the inlet state parameters of the heat exchanger cold end, the flow rate parameters, and the outlet temperature of the heat exchanger cold end.

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