Supercritical carbon dioxide Brayton cycle working medium purification system

Abstract

The invention discloses a supercritical carbon dioxide Brayton cycle working medium purification system. The system comprises a first filtering unit, a catalytic conversion unit and a parallel adsorption unit group, the inlet end of the first filtering unit is communicated with a pipeline at the front end of a high-temperature side inlet of a heat regenerator in the supercritical carbon dioxide Brayton cycle system, and is configured to intercept solid particle impurities in a cycle working medium; the inlet end of the catalytic conversion unit is communicated with the outlet end of the first filter unit, and the catalytic conversion unit is configured to catalytically convert carbon monoxide contained in the cycle fluid treated by the first filter unit into carbon dioxide; the parallel adsorption unit group comprises at least two adsorption units which are arranged in parallel, the inlet end of each adsorption unit is communicated with the outlet end of the catalytic conversion unit, and the outlet end of each adsorption unit is communicated with a rear-end pipeline of a cooler in the supercritical carbon dioxide Brayton cycle system; and the removal unit is configured to remove residual oxygen, water vapor and carbon monoxide in the cycle fluid treated by the catalytic conversion unit.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of working medium purification system, and particularly relates to a supercritical carbon dioxide Brayton cycle working medium purification system. BACKGROUND

[0002] As a new generation of high-efficiency thermodynamic cycle technology, the supercritical carbon dioxide Brayton cycle has a broad application prospect in the fields of nuclear energy, solar thermal power generation, industrial waste heat recovery, etc. due to its high cycle efficiency, compact equipment structure and low environmental impact. The cycle uses supercritical carbon dioxide as the working medium, and realizes energy conversion through turbine expansion. However, the purity of the working medium directly affects the long-term stability, equipment life and safety of the system.

[0003] In the supercritical carbon dioxide Brayton cycle system, long-term flow of the working medium may cause wear and tear of the inner wall of the equipment, and corrosion products may fall off to form solid impurities such as metal particles and oxide debris. If these particles enter the key components such as the turbine and the regenerator, they may cause flow passage blockage, impeller wear and even system leakage, significantly reducing the reliability of the equipment. At the same time, the working medium may undergo thermal decomposition or chemical reaction to generate carbon monoxide under the action of a catalyst at high temperature. Carbon monoxide is not only an "inert diluent" of the cycle working medium, which reduces the cycle efficiency, but also may accumulate in the dead angle of the equipment and form an explosive gas mixture with oxygen, posing a safety hazard. In addition, oxygen and water vapor may be introduced during the preparation of the cycle system or the working medium due to poor sealing. SUMMARY

[0004] Therefore, the application provides a supercritical carbon dioxide Brayton cycle working medium purification system, which mainly purifies carbon monoxide, oxygen, water vapor and solid particle impurities in the cycle working medium.

[0005] To achieve the above-mentioned purpose, the application mainly provides the following technical solutions:

[0006] The application provides a supercritical carbon dioxide Brayton cycle working medium purification system, which comprises:

[0007] A first filtering unit, an inlet end of the first filtering unit being connected in communication with a high-temperature side inlet front end pipeline of a regenerator in a supercritical carbon dioxide Brayton cycle system, and being configured to trap solid particle impurities in the cycle working medium;

[0008] a catalytic conversion unit, an inlet end of the catalytic conversion unit being in communication with an outlet end of the first filter unit, the catalytic conversion unit being internally provided with a catalyst bed, and being configured to catalytically convert carbon monoxide contained in the circulating working medium processed by the first filter unit into carbon dioxide;

[0009] a parallel adsorption unit group, the parallel adsorption unit group comprising at least two adsorption units arranged in parallel, an inlet end of each of the adsorption units being in communication with an outlet end of the catalytic conversion unit, an outlet end of each of the adsorption units being in communication with a pipeline at a rear end of a cooler in the supercritical carbon dioxide Brayton cycle system, the adsorption units being internally provided with an adsorbent bed, and being configured to remove residual oxygen, water vapor and carbon monoxide in the circulating working medium processed by the catalytic conversion unit.

[0010] Optionally, a flow regulating valve is arranged on a communication pipeline between the outlet end of the first filter unit and the high-temperature side inlet of the regenerator, the flow regulating valve being configured to regulate the flow of the purification branch to 5% of the gas filling amount of the main loop;

[0011] wherein the gas filling amount of the main loop is the total mass flow of the circulating working medium when the supercritical carbon dioxide Brayton cycle system is stably operated.

[0012] Optionally, a second filter unit is arranged on a communication pipeline between the outlet end of the parallel adsorption unit group and the pipeline at the rear end of the cooler, the second filter unit being configured to trap adsorbent particles or catalytic reaction byproducts remaining in the circulating working medium processed by the parallel adsorption unit group.

[0013] Optionally, the supercritical carbon dioxide Brayton cycle working medium purification system further comprises:

[0014] a heat exchange unit, the heat exchange unit comprising a first flow channel and a second flow channel, an inlet end of the first flow channel being in communication with an outlet end of the first filter unit, an outlet end of the first flow channel being in communication with an inlet end of the catalytic conversion unit, the heat exchange unit being configured to exchange heat between the circulating working medium in the first flow channel and a fluid in the second flow channel, so as to cool the circulating working medium processed by the first filter unit.

[0015] Optionally, an outlet end of the catalytic conversion unit is in communication with an inlet end of the second flow channel of the heat exchange unit, and an outlet end of the second flow channel is in communication with an inlet end of the parallel adsorption unit group, and the heat exchange unit is configured to perform counter-flow heat exchange between the circulating working medium in the second flow channel after being treated by the catalytic conversion unit and the circulating working medium in the first flow channel, so as to reduce the temperature of the circulating working medium in the first flow channel to a threshold temperature of a carbon monoxide conversion reaction in the catalytic conversion unit.

[0016] Optionally, a cooling unit is arranged on a communication pipeline between the outlet end of the second flow channel and the inlet end of the parallel adsorption unit group, and the cooling unit is configured to cool the circulating working medium after heat exchange by the heat exchange unit.

[0017] Optionally, the at least two parallel adsorption units include a first adsorption unit and a second adsorption unit, the first adsorption unit is configured with a first regeneration heating unit, and the second adsorption unit is configured with a second regeneration heating unit, and the first regeneration heating unit and the second regeneration heating unit are used for regenerative heating of the first adsorption unit and the second adsorption unit, respectively.

[0018] Optionally, the supercritical carbon dioxide Brayton cycle working medium purification system further comprises:

[0019] a control system configured to execute adsorption-regeneration switching logic, including:

[0020] When the first adsorption unit is in an adsorption state, the second adsorption unit synchronously enters a regeneration state, the second regeneration heating unit is started and delivers regeneration gas to the second adsorption unit;

[0021] When the second adsorption unit reaches a preset regeneration degree, the control system switches the first adsorption unit to enter a regeneration state, and simultaneously switches the second adsorption unit to an adsorption state, so as to realize continuous purification of the circulating working medium through an alternating cycle.

[0022] Optionally, the adsorption-regeneration switching logic further includes:

[0023] The circulating working medium after being treated by the parallel adsorption unit group is sampled and analyzed, and whether the adsorption unit reaches a preset regeneration degree is determined according to a sampling analysis result, so as to trigger switching of the adsorption-regeneration state.

[0024] Optionally, the catalytic conversion unit and the at least two adsorption units constituting the parallel adsorption unit group are both pressure vessels, and are both provided with safety valves.

[0025] By means of the above technical solutions, the present application has at least the following beneficial effects:

[0026] The supercritical carbon dioxide Brayton cycle working medium purification system provided in the embodiments of the present application is composed of a first filtering unit, a catalytic conversion unit and a parallel adsorption unit group to form a multi-stage purification process, systematically solving the pollution problems of solid particle impurities, corrosive gases (such as oxygen and water vapor) and harmful components (such as carbon monoxide) in the circulating working medium, realizing multiple goals of equipment protection, safety improvement and efficiency optimization, thereby ensuring that the supercritical carbon dioxide Brayton cycle system can operate safely and stably. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 FIG. 1 is a structural schematic diagram of a supercritical carbon dioxide Brayton cycle working medium purification system according to an optional embodiment of the present application;

[0028] Figure 2 FIG. 2 is a structural schematic diagram of a supercritical carbon dioxide Brayton cycle system according to an optional embodiment of the present application.

[0029] The reference signs are as follows:

[0030] 1, first filtering unit; 2, catalytic conversion unit; 3, heat exchange unit; 4, cooling unit; 5, first adsorption unit; 6, second adsorption unit; 7, first regeneration and reheating unit; 8, second regeneration and heating unit; 9, second filtering unit; 10, purification branch; 11, flow regulating valve; 12, main circuit; 13, regenerator; 14, cooler. DETAILED DESCRIPTION

[0031] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0032] In addition, the terms "first" and "second" are only for descriptive 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" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0033] In this application, unless specifically defined and limited otherwise, the terms "mounting", "connected", "connection", "fixed", and the like, should be construed broadly and do not necessarily mean fixedly connected, but can also mean detachably connected, or integrally connected; can be mechanical connection, can also be electrical connection; can be directly connected, can also be indirectly connected through an intermediate medium, and can be internal communication of two elements. For those skilled in the art, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0034] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0035] Referring to Figure 1 and Figure 2 As shown, according to the embodiments of the present application, a supercritical carbon dioxide Brayton cycle working medium purification system is provided, comprising a first filtering unit 1, a catalytic conversion unit 2 and a parallel adsorption unit group; the inlet end of the first filtering unit 1 is connected in communication with the high-temperature side inlet front end pipeline of the regenerator 13 in the supercritical carbon dioxide Brayton cycle system, and is configured to trap solid particle impurities in the circulating working medium; the inlet end of the catalytic conversion unit 2 is connected in communication with the outlet end of the first filtering unit 1, and the catalytic conversion unit 2 is internally provided with a catalyst bed, and is configured to catalytically convert carbon monoxide contained in the circulating working medium treated by the first filtering unit 1 into carbon dioxide; the parallel adsorption unit group comprises at least two parallel arranged adsorption units, the inlet end of each adsorption unit is connected in communication with the outlet end of the catalytic conversion unit 2, and the outlet end of each adsorption unit is connected in communication with the rear end pipeline of the cooler 14 in the supercritical carbon dioxide Brayton cycle system, and the adsorption unit is internally provided with an adsorbent bed, and is configured to remove residual oxygen, water vapor and carbon monoxide in the circulating working medium treated by the catalytic conversion unit 2.

[0036] The supercritical carbon dioxide Brayton cycle working medium purification system provided in the embodiment, the first filtering unit 1 as a primary purification link, is responsible for trapping mechanical impurities (such as solid particle impurities) in the circulating working medium; the catalytic conversion unit 2 as an intermediate treatment link, eliminates harmful gas components (such as carbon monoxide) through chemical reaction; and the parallel adsorption unit group as a deep purification link, removes residual impurities (such as oxygen, water vapor and carbon monoxide) through physical adsorption, to realize fine purification of the circulating working medium.

[0037] The supercritical carbon dioxide Brayton cycle working medium purification system provided in the embodiment solves the pollution problems of solid particle impurities, corrosive gases (such as oxygen and water vapor) and harmful components (such as carbon monoxide) in the circulating working medium, realizes multiple goals of equipment protection, safety improvement and efficiency optimization, and thus ensures that the supercritical carbon dioxide Brayton cycle system can operate safely and stably.

[0038] The supercritical carbon dioxide Brayton cycle working medium purification system provided in the embodiment draws the circulating working medium from the high-temperature side inlet front pipeline of the regenerator 13 in the supercritical carbon dioxide Brayton cycle system, so that the circulating working medium does not need to be reheated before entering the catalytic conversion unit 2, and the reaction requirement of catalytically converting carbon monoxide into carbon dioxide can be met by using the temperature of the circulating working medium itself, thereby reducing energy consumption.

[0039] The inlet end of the first filter unit 1 is connected in communication with the high-temperature side inlet front pipeline of the regenerator 13 in the supercritical carbon dioxide Brayton cycle system. It can be understood that, in the supercritical carbon dioxide Brayton cycle system, the regenerator 13 is used to recover the heat of turbine exhaust gas to heat the circulating working medium entering the combustion chamber, and the working medium in the high-temperature side inlet front pipeline of the regenerator 13 is in a high-temperature and high-pressure state.

[0040] Specifically, the first filter unit 1 can trap mechanical impurities such as metal particles, oxide debris and welding residues in the circulating working medium by using a filter element (such as a metal screen or a ceramic filter element), to prevent the mechanical impurities from entering the subsequent catalytic conversion unit 2 and key circulating equipment (such as a turbine and a regenerator 13), and to avoid the solid particle impurities from wearing or clogging the flow channel.

[0041] The inlet end of the catalytic conversion unit 2 is connected in communication with the outlet end of the first filter unit 1, and the outlet end of the catalytic conversion unit 2 is connected in communication with the inlet end of the parallel adsorption unit group.

[0042] Specifically, the catalytic conversion unit 2 includes a catalyst bed filled with a catalyst (such as a noble metal catalyst such as platinum and palladium, or a metal oxide catalyst such as copper oxide / zinc oxide) suitable for a high-temperature environment. In the embodiment, the catalytic conversion unit 2 can convert carbon monoxide in the circulating working medium into carbon dioxide by catalytic oxidation reaction by using the high temperature (heat from the front pipeline of the regenerator 13) of the circulating working medium itself. Thus, the reaction can be directly driven by using the heat in the circulating system without an additional heating device, thereby reducing energy consumption.

[0043] The inlet end of the parallel adsorption unit group is connected in communication with the outlet end of the catalytic conversion unit 2, and the outlet end of the parallel adsorption unit group is connected in communication with the rear end pipeline of the cooler 14 in the circulating system, so that the purified circulating working medium returns to the low-temperature section of the circulating system.

[0044] Specifically, the parallel adsorption unit group includes at least two adsorption units arranged in parallel. Each adsorption unit is provided with an adsorbent bed filled with a multifunctional adsorbent. The multifunctional adsorbent may include molecular sieves, activated alumina and activated carbon. Molecular sieves are mainly used to remove water vapor; activated alumina is mainly used to remove moisture and oxygen; activated carbon is mainly used to adsorb organic matter or residual carbon monoxide. The above configuration can achieve the following: inhibiting oxidative corrosion by removing residual oxygen and reducing oxidative corrosion caused by contact between metal parts and oxygen; avoiding acidic corrosion by removing water vapor and preventing it from reacting with carbon dioxide to form carbonic acid, thereby reducing the risk of equipment corrosion; and ensuring the purity of the circulating working fluid by removing carbon monoxide twice to ensure that the residual carbon monoxide after catalytic conversion is completely removed, so that the purity of the circulating working fluid meets the ppm level standard requirements.

[0045] Furthermore, in this embodiment, the catalytic conversion unit 2 and the at least two adsorption units constituting the parallel adsorption unit group are all embedded in the purification branch 10 in a constant-diameter side-line configuration. Therefore, the flow rate can be adjusted arbitrarily within a range of 0 to 100%, enabling the purification system to be switched in and out at any time as needed, thereby achieving safe and efficient purification of the circulating fluid. Here, the purification branch 10 refers to a parallel branch line extending from the main circulation pipeline of the supercritical carbon dioxide Brayton cycle system. Its function is to introduce some or all of the circulating fluid into the purification system for purification, and then return the purified circulating fluid to the main circulation pipeline.

[0046] In some possible implementations disclosed in this application, see Figure 1 and Figure 2 As shown, a flow regulating valve 11 is provided on the connecting pipeline between the outlet end of the first filter unit 1 and the high-temperature side inlet of the regenerator 13. The flow regulating valve 11 is configured to adjust the flow of the purification branch 10 to 5% of the gas filling amount of the main loop 12; wherein the gas filling amount of the main loop 12 is the total mass flow of the circulating working fluid when the supercritical carbon dioxide Brayton cycle system is in stable operation.

[0047] In this embodiment, only 125% of the working fluid in the main loop is extracted for purification, significantly reducing the volume of circulating fluid required for treatment compared to full-flow purification. Because the circulating working fluid in the purification branch 10 must sequentially pass through the catalytic conversion and adsorption units (which may involve pressure losses and process delays), the smaller flow rate can reduce the overall energy consumption of the purification system, avoiding excessive energy consumption in the purification process itself, which would affect the efficiency of the Brayton cycle.

[0048] Here, the main loop 12 refers to the main circulation pipeline of the supercritical carbon dioxide Brayton cycle system.

[0049] In this embodiment, the flow rate of the purification branch 10 is specifically 5% of the total mass flow rate of the circulating working medium in the main circulation pipeline per hour when the supercritical carbon dioxide Brayton cycle system is stably running.

[0050] In some possible implemented embodiments disclosed in the present application, referring to Figure 1 As shown in the figure, a second filter unit 9 is arranged on the communication pipeline between the outlet end of the parallel adsorption unit group and the rear end pipeline of the cooler 14, and the second filter unit 9 is configured to trap the adsorbent particles or catalytic reaction by-products remaining in the circulating working medium after being processed by the parallel adsorption unit group.

[0051] It can be understood that the adsorbent bed (such as molecular sieve, activated alumina, activated carbon) of the parallel adsorption unit group may fall off fine particles due to vibration, airflow scouring and the like in long-term operation; and a small amount of by-products (such as metal oxide debris or reaction polymerization products) may be generated in the catalytic reaction of the catalytic conversion unit 2. Here, the second filter unit 9 traps these particulate impurities through a filter element (such as a precision metal filter screen, a porous ceramic filter element, etc.), which can avoid the particulate impurities from returning to the main circulation pipeline with the purified circulating working medium, and further protect the purity of the circulating working medium.

[0052] In some possible implemented embodiments disclosed in the present application, referring to Figure 1 As shown in the figure, the supercritical carbon dioxide Brayton cycle working medium purification system further includes a heat exchange unit; the heat exchange unit includes a first flow channel and a second flow channel, the inlet end of the first flow channel is in communication with the outlet end of the first filter unit 1, and the outlet end of the first flow channel is in communication with the inlet end of the catalytic conversion unit 2; the heat exchange unit is configured to exchange heat between the circulating working medium in the first flow channel and the fluid in the second flow channel, so as to cool the circulating working medium processed by the first filter unit 1.

[0053] It can be understood that the catalyst (such as noble metal or metal oxide such as platinum, palladium, etc.) of the catalytic conversion unit 2 usually has a specific optimal active temperature range. If the temperature of the circulating working medium is too high, the catalyst may be deactivated or its aging may be accelerated. In this scenario, the circulating working medium introduced by the purification branch 10 is in a high-temperature and high-pressure state because it is taken from the high-temperature side inlet end pipeline of the regenerator 13, and is easy to exceed the optimal active temperature range of the catalyst. By setting the heat exchange unit to cool the circulating working medium, the temperature of the circulating working medium can be adjusted to the appropriate working interval of the catalyst, so as to avoid performance degradation or shortening of the service life of the catalyst due to high temperature.

[0054] Here, the heat exchange unit can adopt a double-flow structure of counterflow or parallel flow, including a first flow channel and a second flow channel; the first flow channel serves as a main path, with its inlet connected to the outlet of the first filtering unit 1 and its outlet connected to the inlet of the catalytic conversion unit 2, for conveying the high-temperature circulating working medium to be cooled; the second flow channel serves as a heat exchange medium channel, with low-temperature fluid (such as cooling water, circulating system low-temperature section working medium, etc.) flowing inside and exchanging heat with the working medium in the first flow channel through the pipe wall.

[0055] In the above embodiment, referring to Figure 1 illustred, the outlet end of the catalytic conversion unit 2 is connected in communication with the inlet end of the second flow channel of the heat exchange unit, and the outlet end of the second flow channel is connected in communication with the inlet end of the parallel adsorption unit group, and the heat exchange unit is configured to cause the circulating working medium in the second flow channel, which has been treated by the catalytic conversion unit 2, to exchange heat with the circulating working medium in the first flow channel in counterflow, so as to reduce the temperature of the circulating working medium in the first flow channel to the threshold temperature of the carbon monoxide conversion reaction in the catalytic conversion unit 2.

[0056] It can be understood that the circulating working medium in a high-temperature and high-pressure state will have its temperature reduced due to heat radiation to the surrounding environment when flowing through the catalytic conversion unit 2 and the connecting pipeline thereof. Therefore, the temperature of the circulating working medium entering the second flow channel after passing through the catalytic conversion unit 2 is lower than the temperature of the circulating working medium not entering the catalytic conversion unit 2 (i.e., in the first flow channel). In this embodiment, the heat exchange unit cools the high-temperature circulating working medium in the first flow channel by utilizing the waste heat of the low-temperature circulating working medium in the second flow channel, thereby saving the cooling energy consumed in the traditional cooling mode, avoiding the device investment of separately setting the cooler 14 and the preheater, and realizing the recycling of heat and the improvement of system energy efficiency.

[0057] Here, the high-temperature circulating working medium in the first flow channel is about 500-600℃, and the low-temperature circulating working medium entering the second flow channel after the outlet of the catalytic conversion unit 2 is cooled due to heat dissipation is about 350-400℃, forming a stable temperature difference. Among them, the threshold temperature is the highest effective temperature of the carbon monoxide conversion reaction in the catalytic conversion unit 2 (usually 400-500℃, depending on the type of catalyst).

[0058] In the above embodiment, referring to Figure 1 illustrated, the connecting pipeline between the outlet end of the second flow channel and the inlet end of the parallel adsorption unit group is provided with the cooling unit 4, and the cooling unit 4 is configured to cool the circulating working medium after heat exchange by the heat exchange unit.

[0059] It can be understood that the adsorbent (such as molecular sieve, activated alumina, activated carbon, etc.) in the adsorption unit is generally sensitive to temperature and has an optimal working temperature range. The temperature of the circulating working medium after heat exchange by the heat exchange unit can still be higher than the optimal working temperature of the adsorbent. By further reducing the temperature by the cooling unit 4, the temperature of the circulating working medium can be adjusted to the appropriate working temperature range of the adsorbent, so as to ensure that the adsorbent can efficiently remove the impurities such as oxygen, water vapor and carbon monoxide remaining in the circulating working medium, and improve the purification effect of the adsorption unit.

[0060] Here, if the temperature of the circulating working medium is too high, it can affect the adsorption performance of the adsorbent, and even cause the adsorbent to be inactivated or accelerate its aging. By reducing the temperature of the circulating working medium to the appropriate working temperature of the adsorbent, the damage of high temperature to the adsorbent can be reduced, the service life of the adsorbent can be prolonged, and the replacement frequency and cost of the adsorbent can be reduced.

[0061] In this embodiment, by the cooling unit 4, the circulating working medium is ensured to be at a suitable temperature when entering the adsorption unit, so that the adsorption unit can fully play a role and more thoroughly remove the impurities in the circulating working medium, thereby ensuring that the purity of the circulating working medium meets the ppm level standard requirement, further improving the purification effect of the entire supercritical carbon dioxide Brayton cycle working medium purification system, and ensuring that the supercritical carbon dioxide Brayton cycle system can be safely and stably operated.

[0062] In some possible implementation embodiments disclosed in the present application, referring to Figure 1 As shown in the figure, the at least two parallelly arranged adsorption units include a first adsorption unit 5 and a second adsorption unit 6, the first adsorption unit 5 is configured with a first regeneration heating unit, and the second adsorption unit 6 is configured with a second regeneration heating unit 8, and the first regeneration heating unit and the second regeneration heating unit 8 are used for respectively regenerating and heating the first adsorption unit 5 and the second adsorption unit 6.

[0063] In this embodiment, each adsorption unit can be individually regenerated and heated without synchronization with other units. For example, when the first adsorption unit 5 is saturated and needs to be regenerated, the second adsorption unit 6 can continue to operate the adsorption process, avoiding the overall shutdown of the purification system and improving the continuous operation capability of the purification system.

[0064] When the purification system includes the cooling unit 4, the inlet ends of the first adsorption unit 5 and the second adsorption unit 6 are connected to the outlet pipeline of the cooling unit 4, and the outlet ends are commonly connected to the main circulation pipeline of the circulating working medium return circulation system, thereby forming two parallel processing channels. The circulating working medium can flow into the two adsorption units for purification treatment, and the two adsorption units cooperatively undertake the purification task of the circulating working medium.

[0065] The purification system further comprises a regenerating gas inlet pipeline, and the inlet ends of the first and second regenerating heating units 8 are connected to the regenerating gas inlet pipeline. The outlet end of the first regenerating heating unit is connected to the pipeline where the first adsorption unit 5 is located, and is in communication with the first adsorption unit 5 during operation. The outlet end of the second regenerating heating unit 8 is connected to the pipeline where the second adsorption unit 6 is located, and is in communication with the second adsorption unit 6 during operation.

[0066] The purification system further comprises a regenerating gas outlet pipeline. The regenerating gas generated by the first and second adsorption units 5 and 6 during the regeneration process is collected through the respective pipelines and then discharged from the purification system through the regenerating gas outlet pipeline, so as to be subjected to subsequent treatment or discharged.

[0067] It can be understood that valves are arranged on the following pipelines to control the flow path and flow rate of the circulating working medium and the regenerating gas: the pipelines connecting the first and second adsorption units 5 and 6 to the outlet pipeline of the cooling unit 4; the pipelines connecting the first and second adsorption units 5 and 6 to the main circulating pipeline of the circulating system; the pipelines connecting the first and second adsorption units 5 and 6 to the regenerating gas outlet pipeline; and the pipelines connecting the regenerating gas inlet pipeline to the first and second regenerating heating units 8.

[0068] Specifically, taking the first adsorption unit 5 in the adsorption state and the second adsorption unit 6 in the regeneration state as an example, the valve states and the flow directions of the circulating working medium and the regenerating gas are described as follows: the valve between the outlet of the cooling unit 4 and the first adsorption unit 5 is opened to allow the circulating working medium to flow from the cooling unit 4 to the first adsorption unit 5; the valve between the first adsorption unit 5 and the circulating system return pipeline is opened to allow the purified circulating working medium to return to the main circulating pipeline of the circulating system; the valve between the regenerating gas inlet pipeline and the first regenerating heating unit is closed to prevent the regenerating gas from mixing with the purified circulating working medium; the valve between the first adsorption unit 5 and the regenerating gas outlet pipeline is closed to prevent the circulating working medium from flowing through the regenerating gas outlet pipeline and being accidentally discharged; the valve between the outlet of the cooling unit 4 and the second adsorption unit 6 is closed to suspend the adsorption process of the second adsorption unit 6 and prevent the unregenerated adsorbent from contacting the circulating working medium; the valve between the second adsorption unit 6 and the circulating system return pipeline is closed to prevent the regenerating gas and impurities in the regeneration process from entering the main circulating pipeline of the circulating system; the valve between the regenerating gas inlet pipeline and the second regenerating heating unit 8 is opened, and the regenerating gas flows into the second regenerating heating unit 8 through the regenerating gas inlet pipeline, is heated to the required temperature for regeneration, and then enters the second adsorption unit 6 for regeneration; and the valve between the second adsorption unit 6 and the regenerating gas outlet pipeline is opened to discharge the impurities and regenerating gas desorbed from the second adsorption unit 6 during the regeneration process.

[0069] Further, to realize automatic control of the purification system, all the above-mentioned valves are electromagnetic valves.

[0070] In the above embodiment, the supercritical carbon dioxide Brayton cycle working fluid purification system further comprises a control system; the control system is configured to execute adsorption-regeneration switching logic, including: when the first adsorption unit 5 is in the adsorption state, the second adsorption unit 6 synchronously enters the regeneration state, and the second regeneration heating unit 8 starts and delivers regeneration gas to the second adsorption unit 6; when the second adsorption unit 6 reaches the preset regeneration degree, the control system switches the first adsorption unit 5 to enter the regeneration state, and simultaneously switches the second adsorption unit 6 to the adsorption state, to realize continuous purification of the circulating working fluid through alternating circulation.

[0071] In this embodiment, when one adsorption unit needs to be regenerated due to saturation, the other adsorption unit can still maintain the adsorption process, ensuring that the purification process of the circulating working fluid is not interrupted, guaranteeing the continuous and stable operation of the supercritical carbon dioxide Brayton cycle system, and avoiding the decline in efficiency or failure of the main system due to the shutdown of the purification system. At the same time, through the "adsorption-regeneration" alternating mode, the two adsorption units realize continuous purification of the circulating working fluid, greatly improving the purification processing capacity per unit time compared to the design of a single adsorption unit that needs to be shut down for regeneration, and ensuring that the purity of the working fluid always meets the ppm-level standard requirements. At the same time, the regeneration heating unit is only started when the corresponding adsorption unit needs to be regenerated, avoiding the energy waste caused by frequent start-stop or long-term heating in the regeneration process of the traditional single-adsorption-unit system, and reducing the overall energy consumption of the system.

[0072] Here, based on the preset adsorption-regeneration switching logic, the control system precisely controls the opening and closing states of the electromagnetic valves and the regeneration heating unit, to realize the switching of the flow direction and the flow distribution of the circulating working fluid and the regeneration gas, thereby ensuring the automatic and collaborative operation of the two adsorption units. Specifically, when the first adsorption unit 5 is in the adsorption state, the control system opens the inlet and outlet pipeline electromagnetic valves of the first adsorption unit 5, so that the circulating working fluid flows in for purification; at the same time, the control system closes the adsorption path of the corresponding electromagnetic valve of the second adsorption unit 6, and opens the regeneration heating and regeneration gas path, to start the regeneration process. When the second adsorption unit 6 reaches the preset regeneration condition, the control system immediately performs valve state switching, so that the working states of the two adsorption units are exchanged, to form an alternating cycle. The specific logic and parameter settings of the valve state control have been described in detail in the foregoing description in combination with different working conditions and switching processes of adsorption and regeneration, and will not be repeated here.

[0073] In the above embodiment, as shown in Figure 1 The adsorption-regeneration switching logic further includes: sampling and analyzing the circulating working fluid processed by the parallel adsorption unit group, and judging whether the corresponding adsorption unit reaches the preset regeneration degree according to the sampling and analysis results, to trigger the switching of the adsorption-regeneration state.

[0074] In this embodiment, the purification system can adapt to different sources and different pollution levels of the circulating working medium through the feedback mechanism of sampling analysis, and effectively control the purification degree. At the same time, the sampling analysis results can be used as monitoring parameters of the running state of the purification system to find potential problems such as performance degradation of the adsorption unit and fault of the regeneration heating unit in advance, and provide data support for preventive maintenance.

[0075] Here, if the impurity concentration in the circulating working medium after adsorption is detected to be lower than the first preset concentration threshold, it indicates that the adsorbent of the corresponding adsorption unit still has adsorption capacity, and the current state is maintained; if the concentration reaches or exceeds the first preset concentration threshold, the logic is triggered: the corresponding adsorption unit stops working and enters the regeneration state, and the other adsorption unit in parallel is switched to the adsorption state. For example, when the water content is > 50ppm, it is determined that the adsorbent is invalid.

[0076] In addition, the exhaust gas discharged during the regeneration process can be sampled and analyzed, and the concentration of the desorbed impurities and the regeneration efficiency are detected to further optimize the adsorption-regeneration switching logic. Specifically: if the impurity concentration in the regeneration exhaust gas is detected to be higher than the second preset concentration threshold, it indicates that the adsorption unit is not fully regenerated, at which time the system automatically prolongs the regeneration time or increases the regeneration heating power to ensure that the adsorbent fully restores activity; if the impurity concentration is lower than the second concentration threshold, it is determined that the regeneration is completed, and the switching logic is triggered, the adsorption unit is switched to the adsorption state, and replaces the other adsorption unit which has reached the adsorption saturation state, thereby forming a dynamic balance purification cycle. This mechanism realizes precise control of the working state of the adsorption unit by real-time monitoring of the regeneration effect, and ensures the continuity and efficiency of the purification process of the circulating working medium.

[0077] It should be noted that the adsorption-regeneration switching logic can also combine the above two sampling analysis mechanisms to realize precise control of the working state of the adsorption unit throughout the process. In this control logic, the sampling analysis of the circulating working medium after adsorption has higher priority than the sampling analysis of the regeneration exhaust gas.

[0078] In some possible implemented embodiments disclosed in the present application, the control system is further configured to perform a purification strategy pre-adjustment program, which includes: based on the sampling analysis data of the circulating working medium at the inlet of the purification branch 10 (such as impurity type, concentration, and working medium temperature, pressure, etc.), combining historical operation data and a preset model, dynamically adjusting the operation parameters of each purification unit (such as the first filter unit 1, the catalytic conversion unit 2, and the adsorption unit group) in advance to adapt to the change of the pollution condition of the circulating working medium in the circulating system; and based on the sampling analysis data of the circulating working medium after being treated by the catalytic conversion unit 2 (such as carbon monoxide conversion rate, catalyst activity attenuation trend, circulating working medium temperature fluctuation, etc.), real-time evaluation of the catalytic reaction efficiency, and fine adjustment of the reaction conditions (such as increasing the catalyst bed residence time, optimizing the air flow distribution) of the catalytic conversion unit 2.

[0079] In order to grasp the initial pollution condition of the circulating medium in the circulating system in real time and dynamically optimize the purification strategy, the purification device further comprises sampling and analyzing the circulating medium at the inlet of the purification branch 10. Specifically, the types and concentrations of impurities (such as solid particle content, carbon monoxide, oxygen, water vapor, etc.) in the circulating medium at the inlet of the purification branch 10 are detected to determine whether the pollution degree of the circulating system exceeds the design expectation. According to the pollution concentration of the inlet circulating medium, the flow of the purification branch 10 (such as from 5% to 10% of the flow of the main loop 12) is automatically adjusted, or the number of operating parallel adsorption units (such as from 2 units to 3 units) is switched, to ensure that the purification capacity matches the pollution load.

[0080] In order to monitor the reaction efficiency of the catalytic conversion unit 2 in real time and ensure the processing effect of the subsequent adsorption unit, the purification device further comprises sampling and analyzing the circulating medium after being processed by the catalytic conversion unit 2. Specifically, the carbon monoxide concentration in the circulating medium after catalytic conversion is detected to confirm whether it is fully converted to carbon dioxide through catalytic oxidation reaction, so as to avoid the unreacted carbon monoxide entering the adsorption unit and increasing the processing load thereof. In this case, the change trend of the carbon monoxide concentration after catalysis is continuously monitored, and if the carbon monoxide conversion rate is found to decrease (such as from 90% to 70%) under the same working condition, problems such as catalyst aging, poisoning or bed blockage can be warned in advance, so that the catalyst can be replaced or regenerated in time to avoid a sharp decrease in the purification efficiency of the system.

[0081] In some possible implementation embodiments disclosed in the present application, referring to FIG. 2, Figure 1 As shown in FIG. 2, the catalytic conversion unit 2 and the at least two adsorption units constituting the parallel adsorption unit group are both pressure vessels, and are both provided with safety valves.

[0082] In this embodiment, the pressure vessel structure of the catalytic conversion unit 2 and the adsorption unit can withstand the high-temperature and high-pressure environment of the supercritical carbon dioxide medium, and is fully compatible with the operating pressure of the circulating system. Therefore, the circulating medium does not need to be depressurized when flowing in the purification branch 10, and always maintains a supercritical state, avoiding energy loss and performance fluctuations of the medium due to phase change. At the same time, since the purification unit and the main circulating system maintain the same pressure, the purified medium can be directly returned to the back-end pipeline of the cooler 14 through the pipeline without the need for additional pressurization equipment (such as a compressor). This design simplifies the system process, reduces energy consumption, and at the same time avoids the risk of secondary pollution that may be introduced due to pressurization.

[0083] Here, the safety valves of each unit can automatically release pressure when the internal pressure exceeds the design threshold (such as 1.1 times the working pressure), preventing the risk of overpressure due to valve malfunction, pipeline blockage or uncontrolled reaction heat release, and providing safety redundancy for long-term stable operation in a high-temperature and high-pressure environment.

[0084] Those skilled in the art can easily understand that the above-mentioned advantageous modes can be freely combined and superimposed without conflict.

[0085] The above is only the preferred embodiment of the present application, and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above is only the preferred embodiment of the present application, and should not be used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A supercritical carbon dioxide Brayton cycle working medium purification system, characterized in that: include: a first filter unit, wherein the inlet end of the first filter unit is connected to the high-temperature side inlet front end pipeline of the regenerator in the supercritical carbon dioxide Brayton cycle system, and is configured to intercept solid particle impurities in the circulating working fluid; a catalytic conversion unit, wherein the inlet end of the catalytic conversion unit is connected to the outlet end of the first filter unit, the catalytic conversion unit is provided with a catalyst bed layer inside, and is configured to catalytically convert carbon monoxide contained in the circulating working fluid after being treated by the first filter unit into carbon dioxide; A parallel adsorption unit group, wherein the parallel adsorption unit group includes at least two adsorption units arranged in parallel, the inlet end of each adsorption unit is connected to the outlet end of the catalytic conversion unit, and the outlet end of each adsorption unit is connected to the rear end pipeline of the cooler in the supercritical carbon dioxide Brayton cycle system. An adsorbent bed is provided inside the adsorption unit and is configured to remove residual oxygen, water vapor and carbon monoxide in the circulating working fluid after treatment by the catalytic conversion unit.

2. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 1, characterized in that: A flow regulating valve is provided on the connecting pipe between the outlet end of the first filter unit and the high-temperature side inlet of the regenerator, and the flow regulating valve is configured to regulate the flow of the purification branch to 5% of the gas filling volume of the main circuit; The main loop gas filling amount is the total mass flow rate of the circulating working fluid when the supercritical carbon dioxide Brayton cycle system is operating stably.

3. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 1, characterized in that: A second filter unit is provided on the connecting pipeline between the outlet end of the parallel adsorption unit group and the rear end pipeline of the cooler, and the second filter unit is configured to intercept the adsorbent particles or catalytic reaction byproducts remaining in the circulating working fluid after being processed by the parallel adsorption unit group.

4. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 1, characterized in that: Also includes: A heat exchange unit, the heat exchange unit includes a first flow channel and a second flow channel, the inlet end of the first flow channel is connected to the outlet end of the first filter unit, and the outlet end of the first flow channel is connected to the inlet end of the catalytic conversion unit. The heat exchange unit is configured to allow the circulating working fluid in the first flow channel to exchange heat with the fluid in the second flow channel to cool the circulating working fluid after being processed by the first filter unit.

5. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 4, characterized in that: The outlet end of the catalytic conversion unit is connected to the inlet end of the second flow channel of the heat exchange unit, and the outlet end of the second flow channel is connected to the inlet end of the parallel adsorption unit group. The heat exchange unit is configured to allow the circulating working fluid in the second flow channel, which has been treated by the catalytic conversion unit, to perform countercurrent heat exchange with the circulating working fluid in the first flow channel to reduce the temperature of the circulating working fluid in the first flow channel to the threshold temperature of the carbon monoxide conversion reaction in the catalytic conversion unit.

6. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 5, characterized in that: A cooling unit is provided on the communication pipeline between the outlet end of the second flow channel and the inlet end of the parallel adsorption unit group, and the cooling unit is configured to cool the circulating working medium after heat exchange by the heat exchange unit.

7. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 1, characterized in that: At least two adsorption units arranged in parallel include a first adsorption unit and a second adsorption unit, the first adsorption unit is configured with a first regeneration heating unit, and the second adsorption unit is configured with a second regeneration heating unit, and the first regeneration heating unit and the second regeneration heating unit are used to regenerate and heat the first adsorption unit and the second adsorption unit respectively.

8. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 7, characterized in that: Also includes: A control system configured to execute adsorption-regeneration switching logic, comprising: When the first adsorption unit is in the adsorption state, the second adsorption unit enters the regeneration state synchronously, and the second regeneration heating unit starts and delivers regeneration gas to the second adsorption unit; When the second adsorption unit reaches a preset regeneration level, the control system switches the first adsorption unit to a regeneration state and simultaneously switches the second adsorption unit to an adsorption state, thereby achieving continuous purification of the circulating working medium through alternating cycles.

9. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 8, characterized in that: The adsorption-regeneration switching logic also includes: The circulating working fluid after being processed by the parallel adsorption unit group is sampled and analyzed, and it is determined whether the corresponding adsorption unit has reached a preset regeneration level based on the sampling and analysis results, so as to trigger the switching of the adsorption-regeneration state.

10. The supercritical carbon dioxide Brayton cycle working medium purification system according to claim 1, characterized in that: The catalytic conversion unit and the at least two adsorption units constituting the parallel adsorption unit group are all pressure vessels and are provided with safety valves.

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