Natural gas SOFC coupling waste heat regenerative drying air and water recovery system

Abstract

The application discloses a natural gas SOFC coupling waste heat regenerative drying air and water recovery system and belongs to the technical field of solid oxide fuel cells. The system comprises an SOFC stack, a combustion reforming system, a fuel supply system, a drying gas supply system, a tail gas condenser and an electric energy conversion system. The drying gas supply system comprises two drying towers connected through a valve switching assembly, and the two towers are alternatively used as an adsorption tower and a regeneration tower. An air preheater air inlet is communicated with an air outlet of the adsorption tower through a dust filter. A tail gas condenser, a water outlet of the tail gas condenser and a drying tower drain valve outlet are communicated with a reforming water tank. The application regenerates the adsorbent by using the tail gas waste heat of the SOFC system for free, dries the raw material air without additional power consumption, recovers the air condensate water as reforming water for free, reduces the system energy consumption, prolongs the service life of the stack, and can adapt to the desert island environment with high temperature and scarce water resources.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of solid oxide fuel cell (SOFC) distributed energy technology, in particular to a natural gas SOFC coupled waste heat regenerative air drying and water recovery system. BACKGROUND

[0002] SOFC (Solid Oxide Fuel Cell) is a high-temperature electrochemical power generation device. A natural gas SOFC system usually converts natural gas into hydrogen-rich fuel through reforming before entering the power stack for power generation. Due to the multiple high-temperature heat exchange links such as combustion, reforming and power generation during the operation of the system, the tail gas still contains a relatively high amount of heat. In particular, after heat exchange through components such as natural gas reformer, air preheater and vaporizer, the tail gas temperature is usually still within a usable range. However, the existing system often does not fully utilize this part of waste heat, resulting in energy waste.

[0003] On the one hand, the cathode side of the SOFC power stack has a high requirement for the quality of the incoming air. In the prior art, the cathode air is usually directly delivered by an air blower to the power stack with ambient air. The high humidity of the air can adversely affect the strontium-containing cathode material and the ferritic stainless steel connecting components, resulting in a decrease in the catalytic activity of the cathode, deterioration of the protective film of the metal connecting plate and generation of red rust, which in turn causes performance degradation and life reduction of the power stack. Therefore, reducing the humidity of the cathode inlet air and improving the degree of air drying are important technical requirements for improving the operational stability and service life of the SOFC system.

[0004] On the other hand, for SOFCs used in desert and island environments, the traditional water recovery system uses an air-cooled condenser, which will cause the tail gas condensation to fail when the ambient temperature is higher than 40℃, posing a great challenge to the reforming water circulation of the SOFC.

[0005] The common air dehumidification methods currently include cyclone separation, silica gel adsorption, micro-thermal regeneration, freeze drying and waste heat regeneration, etc. Among them, cyclone separation can only remove liquid water and is difficult to reduce air humidity; silica gel adsorption requires regular replacement of adsorbent, which has a high operation and maintenance cost; micro-thermal regeneration and freeze drying usually rely on external electric energy, which can easily reduce the overall power generation efficiency of the SOFC system. In comparison, waste heat regeneration drying utilizes the available heat in the tail gas to regenerate the adsorbent, which is more suitable for coupling with the SOFC system. However, the linkage utilization of SOFC tail gas waste heat and air drying system in the prior art is still insufficient, especially lacking an overall scheme for using tail gas waste heat for double-tower switching type air drying and simultaneously recovering and regenerating the condensate water of the exhaust gas.

[0006] Therefore, how to utilize the waste heat of the SOFC tail gas after multi-stage heat exchange to regenerate and dry the raw air, and realize the alternate work of the drying tower, the condensation recovery of the tail gas water vapor, and the low humidification of the cathode inlet air, so as to complete the drying of the raw air and the water cycle of the air condensate water without additional power consumption, becomes a problem to be solved in the field. SUMMARY

[0007] The present application aims to overcome the defects of insufficient utilization of SOFC tail gas waste heat, high humidity of cathode inlet air, additional power consumption for drying agent regeneration, and non-recovery of regeneration condensate water in the prior art, and provides a natural gas SOFC coupled waste heat regeneration drying air and water recovery system, which utilizes the waste heat of the SOFC tail gas after multi-stage heat exchange to regenerate the adsorbent without additional power supply, completes the drying of the raw air, realizes the deep drying of the cathode inlet air, and collects pure water from the air for free, thereby improving the reforming water cycle ability, the comprehensive energy efficiency, and the operation life of the natural gas SOFC power generation. The present application provides a natural gas SOFC coupled waste heat regeneration drying air and water recovery system, which comprises, SOFC stack: provided with an anode gas inlet, a cathode gas inlet, an anode tail gas outlet, and a cathode tail gas outlet; Combustion reforming system: comprising a burner, a natural gas reformer, and an air preheater, the burner being in communication with a natural gas pipeline, the anode tail gas outlet, and the cathode tail gas outlet, respectively, the outlet of the burner being in communication with the heat source inlet of the natural gas reformer, the outlet of the natural gas reformer being in communication with the anode gas inlet, and the outlet of the air preheater being in communication with the cathode gas inlet; Fuel supply system: comprising a reforming water tank and a vaporizer in communication with each other, the vaporizer being in communication with the natural gas pipeline and the combustion reforming system, respectively; Drying gas supply system: comprising an air blower, a cold-blowing air blower, a first drying tower, and a second drying tower, the first drying tower and the second drying tower being connected through a valve switching assembly; the valve switching assembly is configured to: in one working cycle, make the first drying tower as an adsorption tower in communication with the air blower, the second drying tower as a regeneration tower in communication with the regeneration heat source cathode tail gas pipeline, and in the next working cycle, interchange the working conditions of the first drying tower and the second drying tower and the pipeline connection relationship; the outlet of the drying tower in the adsorption working condition is switched to communicate with a dust filter through the valve switching assembly, the dust filter being in communication with the air inlet of the air preheater; the drain valve outlet of the drying tower is in communication with the reforming water tank; Tail gas condenser: in communication with the exhaust outlets of the first drying tower and the second drying tower, and the water outlet being in communication with the reforming water tank; Electric energy conversion system: electrically connected with the SOFC stack.

[0008] Compared with existing technologies, this invention integrates the SOFC stack, fuel supply system, combustion reforming system, drying gas supply system, exhaust gas condenser, and power conversion system to regenerate the desiccant waste heat free of charge by utilizing the medium-temperature exhaust gas waste heat that the SOFC system would otherwise directly emit. This eliminates the need for additional electricity consumption for the drying process and requires no additional drying equipment. It achieves deeply dried cathode intake gas and simultaneously recovers the regenerated exhaust gas and condensate from the air to supply the fuel supply system. This reduces energy consumption, alleviates the corrosion and deterioration of SOFC cathode components by water vapor, effectively improves system power generation efficiency, and extends the overall service life of the stack.

[0009] In one possible implementation, the first drying tower and the second drying tower may function as an adsorption tower and a regeneration tower at any given time, and switch their operating states within adjacent working cycles.

[0010] Compared with the prior art, the present invention uses the first drying tower and the second drying tower to alternate between adsorption and regeneration conditions, so that a single system can continuously produce dry air. This avoids the drawback of single-tower drying equipment needing to be shut down for regeneration, and ensures that SOFC stacks can receive a continuous and stable supply of dry raw material air to meet the requirements of continuous operation of the stack.

[0011] In one possible implementation, the regeneration process of the first or second drying tower, which serves as the regeneration tower, includes a waste heat desorption stage and a cold air regeneration stage. The cold air blower is used to introduce cold air into the regeneration tower after waste heat desorption to reduce the temperature of the adsorbent bed.

[0012] Compared with the prior art, the present invention uses a cold air blower to force the regeneration tower bed to cool down after the waste heat desorption is completed, so that the adsorbent after high temperature desorption can quickly restore its adsorption capacity, ensuring that it still has excellent water vapor adsorption performance when switching to adsorption mode, preventing the bed temperature from being too high and causing the adsorption effect to decrease, and ensuring the low dew point index of the output air.

[0013] In one possible implementation, after the regeneration tower completes cold blowing regeneration, it is pressurized through a valve switching assembly to achieve pressure balance between the first drying tower and the second drying tower.

[0014] Compared with the prior art, the present invention completes the dual-tower pressure boosting and equalization through the valve switching component after the cold blowing regeneration, reduces the airflow impact at the moment of operating condition switching, reduces the probability of adsorbent being pulverized and broken by airflow impact, and at the same time reduces system pressure fluctuations, protecting the SOFC stack inlet pressure stability.

[0015] In one possible implementation, the exhaust gas temperature of the burner, which flows sequentially through a natural gas reformer, an air preheater, and a vaporizer for heat exchange, is 120-140°C.

[0016] Compared with the prior art, the present invention uses the exhaust gas at 120-140°C after multi-stage heat exchange as the heat source for desiccant regeneration. This temperature range matches the regeneration temperature of activated alumina desiccant, making full use of the waste heat of the exhaust gas. No additional electric heating device is required, and the system's net power output is not consumed, which helps to maintain the system's high power generation efficiency.

[0017] In one possible implementation, both the first and second drying towers are filled with activated alumina adsorbent and molecular sieves, and the mass ratio of the molecular sieve to activated alumina is 1:3.

[0018] Compared with existing technologies, this invention uses a molecular sieve and activated alumina composite adsorbent in a specific ratio, which takes into account both large water absorption capacity and deep dehydration capability. Under waste heat regeneration conditions, it can stably remove water vapor from the raw material air, ensuring the drying effect of the cathode air intake. At the same time, the adsorbent can withstand a regeneration temperature of 120-140℃, resulting in a longer cycle life.

[0019] In one possible implementation, the fuel supply system further includes a reforming water pump disposed between the reforming water tank and the vaporizer, for delivering water from the reforming water tank to the vaporizer.

[0020] Compared with the prior art, the present invention uses a reforming water pump to transport water from the reforming water tank to the vaporizer, overcoming pipeline resistance and internal pressure of the vaporizer to achieve stable water supply, ensuring a continuous supply of reforming water, ensuring the stable progress of natural gas steam reforming reaction, and realizing the recycling of reforming water in conjunction with the condensate recovered by the tail gas condenser.

[0021] In one possible implementation, both the first and second drying towers are provided with flow equalization plates at the bottom gas inlet to ensure uniform distribution of air or exhaust gas entering the tower.

[0022] Compared with the prior art, the present invention uses a flow equalization plate at the bottom of the tower to allow the inlet gas and regeneration hot exhaust gas to pass evenly through the adsorbent bed, avoiding the phenomenon of airflow deviation and local short circuit, giving full play to the adsorption and desorption capacity of all adsorbents, and improving the overall drying and regeneration effect.

[0023] In one possible implementation, both the first drying tower and the second drying tower are vertical pressure tank structures, with an upper gas distributor, an adsorbent bed, and a bed support structure arranged sequentially from top to bottom inside the tower.

[0024] Compared with the prior art, the present invention configures the internal structure of the drying tower, relies on the gas distributor to distribute gas evenly, and the bed support structure prevents the adsorbent particles from being lost, preventing the adsorbent from shifting and pulverizing under the scouring of the airflow, thus ensuring the reliable operation of the drying tower under long-term pressure and circulation conditions.

[0025] In one possible implementation, the dry air output from the first or second drying tower, which serves as an adsorption tower, has an atmospheric dew point of less than or equal to -40°C.

[0026] Compared with the prior art, the present invention treats the cathode raw material air to an atmospheric pressure dew point of ≤-40℃, which greatly reduces the moisture content of the air entering the SOFC stack cathode, reduces the corrosion of LSC cathode material by water vapor and the problems of chromium volatilization and corrosion of metal connecting plates, significantly slows down the irreversible performance degradation of stack components, and extends the service life of SOFC stack. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the natural gas SOFC coupled waste heat regeneration drying air and water recovery system of the present invention.

[0028] Explanation of reference numerals in the attached diagram: 1. SOFC stack; 2. Burner; 3. Natural gas reformer; 4. Air preheater; 5. Reformer water pump; 6. Reformer water tank; 7. Vaporizer; 8. Air blower; 9. Cold air blower; 10. First drying tower; 11. Second drying tower; 12. Dust filter; 13. Exhaust gas condenser; 14. DC / DC converter; 111. First switching valve; 112. Second switching valve; 113. Third switching valve; 114. Fourth switching valve; 115. Fifth switching valve; 116. Sixth switching valve; 117. Seventh switching valve; 118. Eighth switching valve; 119. Ninth switching valve; 120. Tenth switching valve; 121. Eleventh switching valve; 122. First drain valve; 123. Second drain valve. Detailed Implementation

[0029] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0030] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0031] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0032] The purpose of this invention is to provide a natural gas SOFC coupled waste heat regeneration and drying air and water recovery system. Through the coordinated operation of various systems, the waste heat of the tail gas after multi-stage heat exchange in SOFC is used to regenerate the desiccant, resulting in deeply dried cathode intake air. At the same time, the regenerated exhaust gas and air condensate are recovered as reforming water, thereby improving the overall energy efficiency of the system and extending the service life of the fuel cell stack.

[0033] like Figure 1 As shown, a natural gas SOFC coupled waste heat regeneration drying air and water recovery system includes an SOFC stack 1, a combustion reforming system, a fuel supply system, a drying gas supply system, a tail gas condenser 13, and an energy conversion system; each system is connected through pipelines and valve switching components to form a complete closed loop of material and energy flow.

[0034] The SOFC stack 1 is provided with an anode inlet, a cathode inlet, an anode exhaust outlet, and a cathode exhaust outlet.

[0035] The combustion reforming system includes a burner 2, a natural gas reformer 3, and an air preheater 4. The burner 2 is connected to the natural gas pipeline, the anode exhaust gas outlet of the SOFC stack 1, and the cathode exhaust gas outlet. The outlet of the burner 2 is connected to the heat source side inlet of the natural gas reformer 3, and the reformed gas outlet of the natural gas reformer 3 is connected to the anode inlet of the SOFC stack 1. The outlet of the air preheater 4 is connected to the cathode inlet of the SOFC stack 1. Residual hydrogen and carbon monoxide in the anode exhaust gas, excess oxygen in the cathode exhaust gas, and the added natural gas are mixed and fully combusted inside the burner 2. The combustion products are water vapor and carbon dioxide. The high-temperature flue gas generated by combustion serves as the heat source for the natural gas reformer 3, providing heat for the endothermic reaction of natural gas water vapor reforming. The resulting reformed gas, rich in hydrogen and carbon monoxide, is transported to the anode of the SOFC stack 1.

[0036] The fuel supply system includes a reforming water tank 6, a reforming water pump 5, and a vaporizer 7. The reforming water tank 6 is connected to the liquid inlet of the vaporizer 7 via the reforming water pump 5. The gas inlet of the vaporizer 7 is connected to a natural gas pipeline, and the steam mixing outlet of the vaporizer 7 is connected to the feed inlet of the natural gas reformer 3. The reforming water pump 5 pressurizes the reformed water inside the reforming water tank 6 and delivers it to the vaporizer 7. In the vaporizer 7, the water absorbs the waste heat of the exhaust gas and vaporizes into steam. The steam is then thoroughly mixed with the natural gas and sent to the natural gas reformer 3 for reforming and hydrogen production.

[0037] The drying air supply system includes an air blower 8, a cold air blower 9, a first drying tower 10, a second drying tower 11, a dust filter 12, an exhaust gas condenser 13, a DC / DC converter 14, and a valve switching assembly consisting of multiple programmable valves; the valve switching assembly includes a first switching valve 111, a second switching valve 112, a third switching valve 113, a fourth switching valve 114, a fifth switching valve 115, a sixth switching valve 116, a seventh switching valve 117, an eighth switching valve 118, a ninth switching valve 119, a tenth switching valve 120, an eleventh switching valve 121, a first drain valve 122, and a second drain valve 123.

[0038] The first drying tower 10 and the second drying tower 11 are vertical pressure tank structures. A flow equalization perforated plate is installed at the gas inlet at the bottom of each tower. Inside the tower, from top to bottom, are an upper gas distributor, an adsorbent bed, and a bed support structure. The adsorbent bed is filled with a mixture of molecular sieve and activated alumina, with a mass ratio of molecular sieve to activated alumina of 1:3. The tops and bottoms of the two drying towers are interconnected via pipelines and the aforementioned valve group, forming switchable adsorption flow paths, waste heat regeneration flow paths, cold blowing flow paths, and exhaust flow paths.

[0039] The dry air output from the drying tower under adsorption conditions is delivered to the dust filter 12 through the valve switching assembly. After the dust filter 12 removes solid particles from the air, it is connected to the air inlet of the air preheater 4.

[0040] The exhaust gas condenser 13 is connected to the regeneration exhaust pipes of the first drying tower 10 and the second drying tower 11 respectively, and the condensate outlet of the exhaust gas condenser 13 is connected to the reforming water tank 6. The high-temperature humid exhaust gas discharged during the regeneration stage of the drying tower enters the exhaust gas condenser 13, where water vapor in the exhaust gas is condensed into liquid water, and the condensate flows back to the reforming water tank 6, realizing the recycling and reuse of reforming water.

[0041] The power conversion system includes a DC / DC converter 14 and a battery. The power output terminal of the SOFC stack 1 is electrically connected to the input terminal of the DC / DC converter 14, and the output terminal of the DC / DC converter 14 is electrically connected to the battery. The DC power output from the SOFC stack is stored in the battery after being regulated and converted, thereby achieving power buffering and stable output.

[0042] In this embodiment, the combustion exhaust gas discharged from the heat source side of the natural gas reformer 3 flows sequentially through the vaporizer 7 and the air preheater 4 to complete staged heat exchange. After heat exchange, the exhaust gas temperature is maintained at 120℃-140℃. This part of the exhaust gas belongs to the waste heat exhaust gas that the system originally intended to directly discharge. This system uses this part of the waste heat as the regeneration heat source cathode exhaust gas free of charge. It is introduced into the drying tower in regeneration mode through the second switching valve 112 and the third switching valve 113 to provide a heat source for the desorption of the adsorbent waste heat. The desiccant regeneration can be achieved without consuming any additional electrical energy, and it does not occupy the net power generation output of SOFC. The eleventh switching valve 121 is an exhaust gas bypass valve. When the drying tower does not receive regeneration exhaust gas, the 120-140℃ exhaust gas is directly introduced into the exhaust gas condenser 13. Furthermore, this specific embodiment also provides the working process: After the system starts up, natural gas is introduced into the gas inlet of the vaporizer 7. The reformed water in the reformed water tank 6 is pumped into the vaporizer 7 by the reformed water pump 5. In the vaporizer 7, the waste heat of the exhaust gas is used to vaporize the water into steam. The steam and natural gas are mixed and sent to the natural gas reformer 3. Natural gas is introduced into the burner 2 for ignition and start-up. The anode exhaust gas and cathode exhaust gas discharged from the SOFC stack 1 are combined into the burner 2 for combustion. The high-temperature flue gas generated enters the heat source side of the natural gas reformer 3 to supply heat for the natural gas reforming reaction. The reformed gas rich in hydrogen and carbon monoxide is sent to the anode inlet of the SOFC stack 1.

[0043] Meanwhile, air blower 8 draws in ambient air and sends it into the drying tower, which is in adsorption mode. Inside the adsorption tower, a molecular sieve-activated alumina composite adsorbent removes moisture from the air, outputting deeply dry air with a dew point ≤-40℃ at atmospheric pressure. The dried raw material air passes through dust filter 12 to remove impurities and is then sent to air preheater 4. Air preheater 4 uses the waste heat from the reformed exhaust gas to preheat the dry air. The preheated dry air is then introduced into the cathode inlet of SOFC stack 1. The reformed gas and the preheated dry air undergo an electrochemical reaction inside SOFC stack 1 to produce direct current (DC). The DC is then regulated by DC / DC converter 14 and stored in a battery. The anode exhaust gas generated after the reaction flows back to burner 2 for combustion, while the cathode exhaust gas serves as a regeneration heat source for the drying tower, thus constructing a closed-loop energy system.

[0044] The cathode tail gas flowing from the heat source side of the natural gas reformer 3 flows successively through the vaporizer 7 and the air preheater 4 to release heat and cool down to 120-140℃ to form regenerated heat source cathode tail gas. The valve switching assembly operates on an 8-hour standard cycle, enabling the dual towers to work alternately. The complete cycle consists of four stages: (1) The first drying tower 10 is used for adsorption, and the second drying tower 11 is used for desorption and regeneration due to residual heat. The tail gas from the 120℃-140℃ regeneration heat source cathode enters the second drying tower 11 via the third switching valve 113, where it undergoes residual heat desorption of the adsorbent inside the tower. The desorbed water is discharged through the second condensate valve 123 and recycled into the reforming water tank. The regeneration exhaust gas is sent to the tail gas condenser 13 via the tenth switching valve 120. The raw material air output from the air blower 8 enters the first drying tower 10 via the seventh switching valve 117. After being dehydrated by bed adsorption, the dried air is output through the fifth switching valve 115, flows through the dust filter 12, and is then sent to the air preheater 4.

[0045] (2) Adsorption operation of the first drying tower 10, and cold blowing and pressure balancing stage of the second drying tower 11. The third switching valve 113 for waste heat regeneration is closed, and the bypass eleventh switching valve 121 is opened. The 120-140℃ exhaust gas directly enters the exhaust gas condenser 13 through the eleventh switching valve 121. The cold air blower 9 is interlocked and started, and the fourth switching valve 114 and the tenth switching valve 120 are opened. Outside cold air is introduced into the second drying tower 11 to cool the adsorbent bed. The exhaust gas after cooling enters the exhaust gas condenser 13 through the tenth switching valve 120. After the bed in the second drying tower 11 has finished cooling, the tenth switching valve 120 is closed, and the pressure in the second drying tower 11 is increased through the fourth switching valve 114 to achieve pressure balance between the two towers. This half-cycle process ends.

[0046] (3) The second drying tower 11 is in adsorption operation, and the first drying tower 10 is in residual heat desorption and regeneration operation. Switching valve status, the 120℃-140℃ regeneration heat source cathode tail gas enters the first drying tower 10 via the second switching valve 112, where it desorbs the residual heat of the adsorbent inside the tower. The desorbed moisture is discharged through the first condensate valve 122, and the regeneration exhaust gas is sent to the tail gas condenser 13 via the ninth switching valve 119. The raw material air output from the air blower 8 enters the second drying tower 11 via the eighth switching valve 118. After adsorption and dehydration, the dried air is output through the sixth switching valve 116, passes through the dust filter 12, and is sent to the air preheater 4.

[0047] (4) Adsorption operation of the second drying tower 11, and cold blowing and pressure balancing stage of the first drying tower 10. The second switching valve 112 for waste heat regeneration is closed, and the bypass eleventh switching valve 121 is opened, allowing high-temperature exhaust gas to directly enter the exhaust gas condenser 13 via the eleventh switching valve 121. The cold-blowing air blower 9 is interlocked and started, opening the first switching valve 111 and the ninth switching valve 119, allowing cold-blowing air to enter the first drying tower 10 to cool the bed. The cold-blowing exhaust gas is then sent to the exhaust gas condenser 13 via the ninth switching valve 119. After the first drying tower 10 has finished cooling, the ninth switching valve 119 is closed, and the pressure in the first drying tower 10 is increased via the first switching valve 111 to achieve pressure balance between the two towers. This complete cycle ends, and the system automatically enters the next cycle.

[0048] The cycle repeats continuously, ensuring a constant supply of low-dew-point dry air to the SOFC stack cathode 1. Water vapor carried by the regenerated exhaust gas condenses in the exhaust gas condenser 13, and the condensate in the steam trap continuously flows back to the reforming water tank 6, replenishing the water consumed in the reforming reaction and reducing the system's consumption of external water resources. The entire system utilizes the waste heat from the SOFC combustion exhaust gas to regenerate the desiccant free of charge, without adding electrical energy consumption for the drying process. It eliminates the need for additional electric heating or refrigeration dehumidification equipment, significantly reducing system auxiliary power consumption. The humidity of the air supplied to the stack cathode is greatly reduced, alleviating the corrosive damage of water vapor to the LSC cathode material and metal connecting plates, and extending the overall operating life of the SOFC stack.

[0049] In the description of the embodiments of this application, it should be noted that the terms "inner" and "outer" and other terms indicating direction or positional relationship are based on the direction or positional relationship shown in the drawings. This is only for the convenience of description and does not indicate or imply that the device or component must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation of this application.

[0050] In the description of this application, the references to terms such as "an embodiment," "some embodiments," "in this embodiment," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system, characterized in that, include, SOFC stack: It is equipped with an anode gas inlet, a cathode gas inlet, an anode exhaust gas outlet, and a cathode exhaust gas outlet; Combustion reforming system: includes a burner, a natural gas reformer and an air preheater. The burner is connected to a natural gas pipeline, an anode tail gas outlet and a cathode tail gas outlet respectively. The outlet of the burner is connected to the heat source inlet of the natural gas reformer. The outlet of the natural gas reformer is connected to the anode inlet. The outlet of the air preheater is connected to the cathode inlet. Fuel supply system: includes an interconnected reforming water tank and a vaporizer, the vaporizer being connected to the natural gas pipeline and the combustion reforming system respectively; Drying air supply system: includes an air blower, a cold-blowing air blower, a first drying tower, and a second drying tower. The first and second drying towers are connected by a valve switching assembly. The valve switching assembly is configured to: in one working cycle, connect the first drying tower as an adsorption tower to the air blower, and connect the second drying tower as a regeneration tower to the cathode exhaust gas pipeline of the regeneration heat source; in the next working cycle, switch the operating conditions and pipeline connections of the first and second drying towers. The outlet of the drying tower in adsorption mode is switched to a dust filter via the valve switching assembly, and the dust filter is connected to the air inlet of the air preheater. The outlet of the drying tower's condensate drain valve is connected to the reforming water tank. Exhaust gas condenser: It is connected to the exhaust ports of the first drying tower and the second drying tower, and its water outlet is connected to the reforming water tank; Power conversion system: electrically connected to the SOFC stack.

2. The natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, The first drying tower and the second drying tower can each function as an adsorption tower and a regeneration tower at any given time, and switch their operating states within adjacent working cycles.

3. The natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, The regeneration process of the first or second drying tower, which serves as the regeneration tower, includes a waste heat desorption stage and a cold air regeneration stage. The cold air blower is used to introduce cold air into the regeneration tower after waste heat desorption in order to reduce the temperature of the adsorbent bed.

4. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 3, characterized in that, After the regeneration tower completes cold blowing regeneration, it is pressurized through a valve switching assembly to achieve pressure balance between the first drying tower and the second drying tower.

5. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, The exhaust gas temperature is 120-140℃, which flows from the burner and sequentially through the natural gas reformer, air preheater and vaporizer for heat exchange.

6. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, Both the first and second drying towers are filled with activated alumina adsorbent and molecular sieves, and the mass ratio of the molecular sieve to activated alumina is 1:

3.

7. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, The fuel supply system also includes a reforming water pump, which is located between the reforming water tank and the vaporizer, and is used to transport water from the reforming water tank to the vaporizer.

8. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, Both the first and second drying towers are equipped with flow equalization plates at the bottom gas inlet to ensure uniform distribution of air or exhaust gas entering the tower.

9. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, Both the first and second drying towers are vertical pressure tank structures, with an upper gas distributor, an adsorbent bed, and a bed support structure arranged sequentially from top to bottom inside the tower.

10. A natural gas SOFC coupled waste heat regeneration drying air and water recovery system according to claim 1, characterized in that, The dry air output from the first or second drying tower, which serves as an adsorption tower, has an atmospheric dew point of less than or equal to -40°C.

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