A method, apparatus, and SOFC power generation system for starting up a cascaded reformer.

Abstract

This application discloses a startup control method, apparatus, and SOFC power generation system for cascaded reformers. The startup control method determines the control command based on the SOFC stack's demand for reforming gas. Based on the control command and the available gas supply to each reformer stage, the reformers are started sequentially, distributing the SOFC stack's reforming gas flow demand to different stages of the reformers. This maximizes the protection of the reformers and the SOFC stack, significantly improves the overall reliability of the SOFC power generation system, and extends the service life of each system component. The sequential startup of each reformer stage based on the available gas supply results in a shorter overall system response time to reforming gas fluctuations, greatly improving system efficiency.

Description

Technical Field

[0001] This invention pertains to reformer control technology, and particularly relates to a start-up control method and device for a cascaded reformer and an SOFC power generation system. Background Technology

[0002] With the rapid development of society and the economy, the environmental pollution and energy security issues caused by the use of traditional fossil fuels have continued to worsen, leading to the rise of clean energy technologies worldwide. Solid oxide fuel cells (SOFCs) are a type of fuel cell with high overall thermal efficiency and a wide range of fuel options. SOFC stack systems are particularly suitable for applications requiring efficient energy conversion and clean energy, such as distributed energy systems, stationary power stations, and grid peak-shaving power plants.

[0003] Hydrogen has high combustion efficiency and is a clean energy source, making it widely used in fuel cells. However, due to the stringent conditions for hydrogen storage and transportation, methanol reforming is now commonly used to produce hydrogen for SOFC batteries or stack systems.

[0004] SOFC stacks exhibit different states during actual operation due to varying operating strategies. Furthermore, SOFC stack systems experience different power fluctuations. This necessitates that the reforming gas flow rate of the methanol reformer fluctuate in accordance with the power fluctuations of the SOFC stack system. However, repeated thermal changes are detrimental to the catalyst and reactor of the methanol reformer. Currently, there are few control strategies for reformer startup and a lack of effective handling of the thermal inertia of the stack system, resulting in the reformer's untimely response to the stack system. Summary of the Invention

[0005] Based on this, the present invention aims to provide a start-up control method and apparatus for a cascaded reformer and an SOFC power generation system, so as to at least overcome the shortcomings of the prior art.

[0006] In a first aspect, the present invention provides a start-up control method for a cascaded reformer, the cascaded reformer comprising at least two stages of reformers, wherein each stage of the cascaded reformer is configured according to the available gas volume, and the start-up control method includes:

[0007] Obtain the reforming gas requirements for SOFC stacks;

[0008] Control commands for the cascaded reformer are generated based on the reformer gas demand.

[0009] Based on control commands and the available gas supply to each stage of the reformer, the reformers are started up one after another to supply gas to the SOFC stack.

[0010] Furthermore, controlling the sequential startup of each stage of the reformer based on control commands and the available gas supply to each stage includes:

[0011] Obtain the available gas volume for each stage of the reformer;

[0012] Based on control commands, each stage of the reformer is activated sequentially from low to high gas supply.

[0013] Furthermore, based on control commands, the reformers at each stage are activated sequentially from low to high gas supply, including:

[0014] The reformer with the lowest available gas volume is activated based on control commands;

[0015] When the gas supply of the smallest-level reformer cannot meet the reforming gas requirements of the SOFC stack, the next-level reformer is started until the total gas supply of each level of reformer meets the reforming gas requirements of the SOFC stack.

[0016] Furthermore, the above-mentioned startup control method also includes:

[0017] Obtain temperature change information of SOFC stack;

[0018] The reforming gas requirement of the SOFC stack is determined based on temperature change information.

[0019] Furthermore, the above-mentioned startup control method also includes:

[0020] The high-temperature flue gas is controlled to be introduced into each stage of the reformer in stages, from low to high, according to the available gas volume.

[0021] Furthermore, the above-mentioned startup control method also includes:

[0022] The flow rate of high-temperature flue gas is controlled to control the preheating temperature of the reformer, so that the start-up time of each stage of the reformer matches the temperature switching time of the SOFC stack.

[0023] In a second aspect, the present invention provides a start-up control device for a cascaded reformer, comprising:

[0024] The reforming gas acquisition unit is configured to acquire the reforming gas demand of the SOFC stack.

[0025] The instruction generation unit is configured to generate control instructions for the cascaded reformer based on the reformer gas demand.

[0026] The control unit is configured to control the sequential startup of each stage of the reformer according to control commands and the available gas supply of each stage of the reformer, so as to achieve gas supply to the SOFC stack.

[0027] Furthermore, the aforementioned start-up control device also includes:

[0028] The temperature information acquisition unit is configured to acquire temperature change information of the SOFC stack.

[0029] Thirdly, the present invention provides an SOFC power generation system based on a cascaded reformer, including a cascaded reformer, a controller, and an SOFC stack system;

[0030] A cascaded reformer includes at least two stages of reformers. Each stage of the cascaded reformer is set according to the available gas volume. Reformers of the same stage are connected in parallel. The reformed gas produced by each stage of the reformer is controlled and distributed to the SOFC stack system by the controller.

[0031] The controller is connected to both the cascaded reformer and the SOFC stack system.

[0032] The controller uses the above-described startup control method to start up each stage of the cascaded reformer, thereby enabling the startup of the SOFC stack system.

[0033] Furthermore, the gas supply range of each reformer is set according to the reforming gas demand corresponding to the operating status of the SOFC stack and the number of SOFC stacks in the SOFC stack system.

[0034] As can be seen from the above technical solutions, the present invention has the following beneficial effects:

[0035] This invention provides a startup control method, apparatus, and SOFC power generation system for a cascaded reformer. For a cascaded reformer with a stepped design, the startup control method starts the reformers step by step according to the reforming gas demand of the SOFC stack and the available gas supply of each reformer. This distributes the reforming gas flow demand to different levels of reformers, maximizing the protection of the reformers and the SOFC stack, significantly improving the overall reliability of the SOFC power generation system, and extending the service life of each system component. The step-by-step startup of each reformer according to the available gas supply results in a shorter overall system response time to reforming gas fluctuations, greatly improving system efficiency. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0037] Figure 1 A schematic diagram of the structure of an SOFC power generation system based on a cascaded methanol reformer is provided for an embodiment of the present invention;

[0038] Figure 2 A flowchart illustrating the implementation of a startup control method for a cascaded reformer provided in this embodiment of the invention;

[0039] Figure 3 This is a schematic diagram of the start-up control device for a cascaded reformer provided in an embodiment of the present invention;

[0040] Figure 4 This is a schematic diagram of the start-up control device structure for another cascaded reformer provided in an embodiment of the present invention; Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] Solid oxide fuel cells (SOFCs) are a type of fuel cell that uses a solid oxide electrolyte, which conducts negative oxygen ions from the cathode to the anode. At the anode, these negative oxygen ions electrochemically oxidize hydrogen or carbon monoxide. The hydrogen in the fuel primarily comes from fuel reforming of natural gas, while the oxygen originates from air. Typically, the fuel reacts with air and steam in an upstream unit of the SOFC anode. The reforming products include hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), and methane vapor (CH4). SOFCs can utilize the exothermic electrochemical oxidation within the fuel cell to power the endothermic steam reforming reaction, thereby improving efficiency. SOFC stack systems using methanol as fuel produce almost no waste, resulting in cleaner emissions.

[0043] The fuel typically undergoes a reforming reaction to produce hydrogen in a reforming reactor. The combustion reaction in the burner or combustion chamber provides a certain amount of energy for the reforming reaction. The high-temperature flue gas generated by combustion in the burner or combustion chamber enters the reforming reactor and exchanges heat with the fuel, allowing the fuel to react with air and steam to produce hydrogen under the action of a catalyst.

[0044] In actual operation, SOFC stack systems mainly have four states: normal operation, standby, shutdown, and startup. During operation, various power fluctuations need to be switched according to the state transitions. Consequently, the reformed gas flow rate generated by the methanol reforming module also needs to fluctuate with the power fluctuations of the SOFC stack system. However, currently used are often large-scale methanol reformers. All gas flow changes caused by power fluctuations in the stack system are handled by a single level or the same reformer. In particular, from the startup and gas supply of the reformer to the first startup of the SOFC stack system, i.e., the entire SOFC stack system from shutdown to operation, there is a lack of corresponding startup strategies. This results in a lack of effective handling of the system's thermal inertia, which adversely affects the startup response of the stack system.

[0045] To address the aforementioned technical problems, this application provides a cascaded reformer start-up control method, apparatus, and SOFC power generation system through the following series of embodiments. The cascaded reformers are configured according to the gas supply capacity of each reformer stage. The start-up control of the cascaded reformers enables the first-round start-up of the SOFC stack system, namely, the process of starting the reformer, supplying gas to the reformer, and triggering the start-up of the SOFC stack.

[0046] In one embodiment, this application provides a SOFC power generation system based on a cascaded reformer, including a cascaded reformer, a controller, and an SOFC stack system.

[0047] The cascaded reformer includes at least two stages of reformers. Each stage of the cascaded reformer is set according to the available gas volume. Reformers of the same stage are connected in parallel. The reformed gas generated by each stage of the reformer is controlled and distributed to the SOFC stack system by the controller.

[0048] The controller is connected to the SOFC stack system via the cascaded reformers. The controller controls the gas supply to each stage of the cascaded reformers to start the SOFC stack.

[0049] Specifically, an SOFC stack system typically includes more than one SOFC stack, which are electrically connected and each SOFC stack is connected to a controller. The controller can read the intrinsic parameters and timing variables of each SOFC stack to determine the operating status of the SOFC stack, and calculate the required reforming gas inlet flow rate for each SOFC stack based on the power fluctuation data of the SOFC stack.

[0050] When the system is working, each level of reformer provides reforming gas of a corresponding flow rate to each SOFC stack according to the control command of the controller.

[0051] For example, the reformed gas generated by each stage of the reformer flows into the central pipeline, and is then uniformly controlled and distributed by the controller before flowing into each SOFC stack to generate electricity.

[0052] In a further embodiment, the gas supply range of each stage of the reformer is set according to the reforming gas demand corresponding to the SOFC stack operating state and the number of SOFC stacks.

[0053] Specifically, the gas flow rate of the reformer is positively correlated with its volume, and the reforming gas demand varies for different operating states of the SOFC stack. In addition to meeting the safe variable range of gas flow rate, the gas supply of each stage of the reformer can also meet the needs of step-by-step start-up by designing reformers of different volumes. Taking a three-stage reformer as an example, the maximum gas supply of the lowest stage reformer can meet the reforming gas flow rate required for the operation of two SOFC stacks, the maximum gas supply of the secondary stage reformer can meet the reforming gas flow rate required for the operation of five SOFC stacks, and the maximum gas supply of the highest stage reformer can meet the reforming gas flow rate required for the operation of ten SOFC stacks. Under this setting, the controller can determine which stage of reformer to start based on the actual number of SOFC stacks to be started and the operating state of the stacks.

[0054] For example, Figure 1 A schematic diagram of an SOFC power generation system based on a cascaded methanol reformer is provided. Figure 1 The SOFC power generation system 100 shown includes an SOFC stack system 110, a controller 120, and a cascaded methanol reformer 130. The SOFC stack system includes n SOFC stacks connected in parallel. The controller 120 and the cascaded methanol reformer 130 are electrically connected to the SOFC stack system 110. The cascaded methanol reformer 130 is a three-stage cascaded configuration, including a first-stage reformer 131, a second-stage reformer 132, and a third-stage reformer 133. The first-stage reformer 131 has the largest gas supply capacity, and the third-stage reformer 133 has the smallest gas supply capacity.

[0055] In a further embodiment, considering that the different gas supply volumes of each stage of the reformer result in varying equipment sizes, the gas flow rates of multi-stage linked reformers have a large range of variation, and the burner also needs to supply heating and insulation for multiple fuel cell stacks, if the existing internal burner design is still adopted, the required burner size would be large because the reformer with a large gas supply volume needs to produce a large gas flow rate. Placing the burner inside the reformer might lead to an even larger reformer size. Therefore, the burner can be externally mounted. There are various methods for burner ignition, such as electric spark ignition; the burner and reformer are connected via a gas flow pipe; the reformer has a high-temperature flue gas passage, and the high-temperature flue gas enters the connected high-temperature flue gas passage from the external burner outlet, thereby heating the reformer and providing the thermal conditions for the reforming reaction.

[0056] The startup process of the cascade methanol reformer controlled by the controller in the above example in this application embodiment refers to the management of the reformer startup sequence, timing, etc. during the reformer startup process by instructions containing abstract and detailed levels for a set of programmable hard automation devices. This management is time-ordered and has a form of expression suitable for and understood by computer control elements.

[0057] The control device or controller mentioned in the embodiments of the present invention can control physical systems such as reformers or SOFC stacks through control signals, thereby allowing components in the physical system to establish, modify and adapt motion profiles, thereby successfully executing the expected motion profiles and processing commands.

[0058] The following section will further detail the object manipulation part of the start-up control process of the cascade methanol reformer. It can be mainly described as the control device or controller generating control signals according to control instructions to control the reformers in each stage of the cascade methanol reformer to start up step by step, and further complete the execution steps of the SOFC stack.

[0059] Figure 2 This application provides an optional execution flow for a cascaded reformer startup control method, which may include the following steps:

[0060] Step S21. Obtain the reforming gas requirement of the SOFC stack.

[0061] Step S22. Generate control commands for the cascaded reformer based on the reformer gas demand.

[0062] Step S23. Control each stage of the reformer to start up sequentially according to the control command and the available gas supply of each stage of the reformer, so as to achieve gas supply to the SOFC stack.

[0063] Specifically, step S23, which involves controlling the sequential startup of each stage of the reformer based on control commands and the available gas supply to each stage, includes:

[0064] Step S231. Obtain the available gas volume for each stage of the reformer.

[0065] Step S232. Based on the control command, start each stage of the reformer in order of increasing gas supply.

[0066] For example, step S232 includes:

[0067] The reformer, with the lowest available gas volume, is activated based on control commands.

[0068] When the gas supply of the smallest-level reformer cannot meet the reforming gas requirements of the SOFC stack, the next-level reformer is started until the total gas supply of each level of reformer meets the reforming gas requirements of the SOFC stack.

[0069] Specifically, when starting up a reformer, the reformer with the smaller available gas volume is started first, such as the one mentioned above. Figure 1 The schematic cascaded reformer 130 includes a three-stage reformer 131. When the gas supply from a lower-stage reformer fails to meet the SOFC stack's requirement for reformed gas flow, a higher-stage reformer is then activated. This prevents excessive gas flow fluctuations within the cascaded reformers and avoids wasting equipment resources. For example, if only two SOFC stacks need to be started up to operating status during the initial system startup, directly responding to this gas demand with a single-stage reformer would result in a slow response time and inevitably waste equipment resources due to a high-flow-rate reformer responding to a low-flow-rate demand. During the reformer startup process, a reforming reaction occurs in the reformer, producing hydrogen-containing gas, and the SOFC stack starts up.

[0070] In a further embodiment, step S231 further includes:

[0071] Obtain temperature change information of SOFC stack;

[0072] The reforming gas requirement of the SOFC stack is determined based on temperature change information.

[0073] Specifically, generally speaking, the operating temperature of an SOFC stack is constant. However, during the initial startup of an SOFC stack, it cannot immediately reach the operating temperature. Assuming the stack is started from a shutdown state, i.e., a cold start, the temperature of the SOFC stack needs to rise from room temperature to the set operating temperature, such as 600°C. This process involves passing through multiple temperature ranges to reach 600°C, which usually takes several hours. The required reforming gas flow rate for SOFC stacks at different temperatures can vary. Therefore, during these several hours, multiple temperature ranges can be divided between room temperature and 600°C. The controller determines the reforming gas demand based on each temperature range and then, in conjunction with the gas supply capacity of each stage of the reformer, starts the reformers one by one to achieve gas supply.

[0074] In a further embodiment, the above-described startup control method further includes the following steps:

[0075] The high-temperature flue gas is controlled to be introduced into each stage of the reformer in stages, from low to high, according to the available gas volume.

[0076] Specifically, when preheating the reformer, high-temperature flue gas is introduced into the lower-level reformer from the burner outlet. After being preheated, it enters the higher-level reformer in sequence. The high-temperature flue gas, which has cooled down due to heat exchange in the lower-level reformer, continues to exchange heat with the reforming fuel (e.g., H2) in the higher-level reformer, thus avoiding the situation where the fuel is difficult to burn due to low temperature when starting the reformer.

[0077] Typically, the required flow rate of high-temperature flue gas for each stage of the reformer is determined based on the volume of the reformed gas, the heating rate, and the heat exchange effect between the high-temperature flue gas and the reformer. The model (or size) of the reformer usually determines the upper limit of the high-temperature flue gas flow rate entering the reformer. To ensure the system's lifespan, the heating rate of the reformer is not too fast, which also limits the upper limit of the high-temperature flue gas flow rate. The heat exchange effect between the high-temperature flue gas and the reformer refers to the heat transfer coefficient between them. Since the heat utilization efficiency is not 100%, this heat transfer coefficient is often less than 1, and can be expressed as: high-temperature flue gas flow rate * heat transfer coefficient = required high-temperature flue gas flow rate for the reformer. The specific value can be adjusted flexibly according to different reformers, as long as the normal operation of the reformer is guaranteed.

[0078] In a further embodiment, the above-described startup control method further includes the following steps:

[0079] The flow rate of high-temperature flue gas is controlled to control the preheating temperature of the reformer, so that the start-up time of each stage of the reformer matches the temperature switching time of the SOFC stack.

[0080] Specifically, as high-temperature flue gas flows into each stage of the reformer, when a lower-level reformer is started, the higher-level reformer has already been preheated to a certain temperature. When the start-up of the SOFC stack is divided into several temperature ranges, the controller often needs to start a higher-level reformer to ensure the intake flow of reformed gas when the SOFC stack is heated to a higher temperature range. The reformer is usually heated from room temperature to operating temperature, for example, from room temperature to 250°C, with a temperature range of 225°C. Assuming that the start-up of the third-stage reformer can only meet the requirement of heating the SOFC stack to 150°C, the second-stage reformer has not started to operating temperature during this temperature period and cannot undergo a reforming reaction. However, due to the preheating of the high-temperature flue gas, the second-stage reformer is preheated to a certain temperature. As long as this temperature reaches at least 100°C, the start-up time of the reformer can be matched with the temperature switching timing of the stack, so that the process of starting the reformers stage by stage matches the temperature switching timing of the SOFC stack.

[0081] by Figure 1 Taking the three-stage cascaded methanol reformer shown as an example, and assuming that the SOFC stack system consists of 10 SOFC stacks connected in parallel, the start-up control of the cascaded methanol reformer will be further introduced below.

[0082] The operating states of SOFC stacks are divided into four types: normal operation, standby, shutdown, and startup, with required reformer gas flow rates of V1, V2, V3, and V4 for each state, respectively. For a single SOFC stack, under normal circumstances, V1 > V2 > V3 ≈ V4. The required reformer gas flow rates during shutdown and startup may be the same (V3 = V4) or different (V3 ≈ V4).

[0083] Assuming a standard reformer has a safe variable gas flow rate range of 50%-100%, and the reformer is configured as a three-stage cascade structure, the relationship between the maximum gas supply capacity and the safe variable range of gas supply capacity of each stage of the reformer and the gas flow rate ratio of a standard reformer is as follows:

[0084] The first-stage reformer can supply a maximum gas volume of 100%, which is sufficient for the normal operation of all SOFC stacks, and its safe range of gas volume variation is 50%-100%. In actual operation, the maximum gas flow rate of the first-stage reformer can be greater than 100%, and its actual flow rate only needs to meet the safe range of 50%-100%. Typically, the reforming gas flow rate required for SOFC stack operation is greater than or equal to the lower limit of the gas supply capacity of the first-stage reformer.

[0085] The second-stage reformer can supply a maximum gas volume of 50%, which is sufficient to meet the normal operation requirements of 50% of the SOFC stacks. Simultaneously, its maximum outlet gas flow rate is greater than or equal to the reforming gas flow rate required for all SOFC stacks in hot standby mode, and its safe range of gas supply variation is 25%-50%. Similarly, in actual operation, the maximum flow rate of the second-stage reformer can exceed 50%, as long as the actual flow rate meets the safe variation range of 25%-50%.

[0086] The maximum gas supply capacity of the three-stage reformer is 25%. Its maximum outlet gas flow rate is greater than or equal to the reforming gas flow rate required when all SOFC stacks are shut down, and its safe range of gas flow rate variation is 12.5%-25%. Since V3≈V4 under normal circumstances, the three-stage reformer also meets the reforming gas flow rate required for all SOFC stacks to reach startup. Similarly, in actual operation, the maximum flow rate of the three-stage reformer can be greater than 25%, and its actual flow rate only needs to meet the safe range of 12.5%-25%.

[0087] It is important to note that the above settings are merely for a visual comparison with the gas flow rate of a hypothetical standard reformer, to facilitate understanding of the differences between different stages of the reformer, and should not be considered as limitations on the absolute volume and gas flow rate of the reformer. In practical applications, the assumed gas flow rate of the standard reformer can be specifically designed according to the actual needs of the SOFC stack system it is connected to.

[0088] (1) Start the three-stage reformer

[0089] Based on the size of the three-stage reformer, the heating rate limit, and the heat exchange effect between the high-temperature flue gas and the reformer, the flow rate N1 of the high-temperature flue gas entering the three-stage reformer is calculated. The flow rate of the high-temperature flue gas entering the three-stage reformer from the burner outlet is controlled. The high-temperature flue gas flowing through the three-stage reformer enters the two-stage reformer and the first-stage reformer in sequence for preheating.

[0090] The high-temperature flue gas heats the third-stage reformer to its operating temperature T0, causing it to start up and undergo a reforming reaction. At this point, the maximum allowable flow rate of the reformed gas produced by the third-stage reformer is Q1. Flow rate Q1 can support all SOFC stacks to reach startup. That is, if the system has 10 SOFC stacks, the gas flow rate required for a single SOFC stack to reach startup is V. s Then Q1≥n*V s For ease of adjustment, Q1 is usually V. s Integer multiples of.

[0091] The reformed gas generated during the startup of the three-stage reformer is condensed through a heat exchanger and then introduced into the anode channel of the SOFC stack, initiating the SOFC stack startup. At this time, the burner needs to supply heat not only for the reformer startup but also for the SOFC stack startup.

[0092] (2) Start the secondary reformer

[0093] Assuming the first round of startup involves three SOFC stacks that need to be brought to operational status, and that each SOFC stack undergoes three temperature stages from cold start to operational status, the reforming gas flow rate required for one stack to reach the first temperature stage is V. t1 The reforming gas flow rate required for the two SOFC stacks to start up to the first temperature stage is 2V. t1 The reforming gas flow rate required for the three SOFC stacks to start up to the first temperature stage is 3V1, and so on, assuming 3V... t1 =Q1, which means that the maximum allowable flow rate Q1 of the three-stage reformer can support the heating of three fuel cell stacks to the first temperature stage.

[0094] When all three SOFC stacks need to be heated to the second temperature stage, assuming the reforming gas flow rate required for one SOFC stack to be heated to the second temperature stage is V. t2 At this time, 3V t2 >Q1, if 3V t2 The quotient of / Q1 is 2, indicating that the third-stage reformer can only meet the heating needs of two SOFC stacks to the second temperature stage. Therefore, the third-stage reformer needs to prioritize the heating and startup of the two SOFC stacks. If there is excess reformed gas, it will still be introduced into the third SOFC stack. However, the flow rate of reformed gas introduced into the third SOFC stack does not support its continued heating to the second temperature stage. Therefore, other reformers must be put into operation and output reformed gas normally to make up for the insufficient reformed gas of the third SOFC stack. Thus, the controller will start the second-stage reformer according to the reformed gas demand.

[0095] Similarly, when the temperature needs to be increased to the third stage, the reforming gas flow rate required for the startup of one SOFC stack increases to V. t3 If V t3=Q1 indicates that the three-stage reformer can only support the heating of one fuel cell stack, and the reforming gas required for the startup of the other two fuel cell stacks needs to be supplied by a higher-level reformer.

[0096] Taking the aforementioned three temperature stages as an example, the second-stage reformer must be started in the first temperature stage to ensure the continuous power generation of the SOFC stack. If the duration of the first temperature stage is t1, that is, within a time ≤ t1, the controller must start the second-stage reformer.

[0097] The secondary reformer is preheated to a certain temperature when the tertiary reformer starts up; this temperature is denoted as T1. Based on the size of the secondary reformer, the heating rate limit, and the heat exchange effect between the high-temperature flue gas and the reformer, the flow rate N2 of the high-temperature flue gas entering the secondary reformer is calculated. The secondary reformer is then controlled to heat up to the reforming reaction operating temperature T0 at a certain rate. At this point, the high-temperature flue gas is prioritized to ensure the flow rate required for the secondary reformer's startup. The high-temperature flue gas exiting the secondary reformer is used to maintain the temperature stability of the tertiary reformer and to preheat the primary reformer.

[0098] Assuming the heating rate of both the SOFC stack and the reformer is 5℃ / min, and the upper limit of the first temperature stage of the stack is 150℃, then the SOFC stack heats up from room temperature to 150℃, a temperature span of 125℃. The reformer typically heats up from room temperature to the operating temperature T0, for example, from room temperature to 250℃, a temperature span of 225℃. At the end of the first temperature stage of the stack, the secondary reformer has not yet started to the operating temperature and cannot supply reforming gas. However, through the preheating of the tertiary reformer, the secondary reformer is preheated to temperature T1. As long as T1 ≥ 100℃, the start-up time of the secondary reformer can match the reforming gas flow rate required for the temperature switching of the SOFC stack.

[0099] After the secondary reformer starts up, a reforming reaction occurs to produce reforming gas, which is then introduced into the SOFC stack to support SOFC startup.

[0100] (3) First-stage reformer

[0101] Similar to the start-up control of the secondary reformer, if the start-up of both the tertiary and secondary reformers still cannot meet the reforming gas flow requirements of the SOFC stack, the controller needs to start the primary reformer. If the secondary and tertiary reformers can meet the requirements, the primary reformer will not be started.

[0102] In some embodiments, when all levels of reformers are started, the gas supply task is preferentially allocated to the higher-level reformers according to the target operating state of the SOFC stack. That is, for example, after all three levels of reformers are started, since the first-level reformer has a stronger gas supply capacity, if the gas supply of the first-level reformer can meet the reforming gas flow required for all SOFC stacks to maintain the target operating state, the second-level and third-level reformers can be controlled to stop supplying gas to the SOFC stack.

[0103] After the secondary and tertiary reformers stop outputting reformed gas, they do not cool down to room temperature. The high-temperature flue gas used to keep the primary reformer warm also flows through the secondary and tertiary reformers for insulation, so that the reformers can respond promptly to changes in reformed gas flow caused by changes in SOFC stack power.

[0104] The three-stage cascade methanol reformer mentioned in the above embodiments is only an example of a three-stage ladder configuration. The system can be designed as other multi-stage linked reformer structures, such as two-stage, four-stage, five-stage or even more.

[0105] Regarding the design of the temperature stages, the embodiments provided in this application only use three temperature stages as examples. In practical applications, the temperature stage design can be multiple temperature stages, as long as the reforming gas provided by the highest-level reformer can support at least one SOFC stack to start up to the working state.

[0106] When referring to fuels used for hydrogen production and SOFC power generation, any SOFC stack or stack system that has fluctuating requirements for intake flow rate is acceptable. It is not limited to methanol reforming; it can be the reforming of other compounds, such as natural gas.

[0107] See Figure 3 An embodiment of this application also provides a start-up control device 300 for a cascaded reformer, comprising:

[0108] The reforming gas acquisition unit 310 is configured to acquire the reforming gas demand of the SOFC stack.

[0109] The instruction generation unit 320 is configured to generate control instructions for the cascaded reformer based on the reformer gas demand.

[0110] Control unit 330 is configured to control the sequential startup of each stage of the reformer according to control commands and the available gas supply of each stage of the reformer, so as to achieve gas supply to the SOFC stack.

[0111] In some embodiments, such as Figure 4 As shown, the above-mentioned start-up control device 300 also includes a temperature information acquisition unit 340, which is configured to acquire temperature change information of the SOFC stack, so that the reforming gas acquisition unit 310 determines the reforming gas demand of the SOFC stack based on the temperature change information.

[0112] The cascaded reformer start-up control device 300 adopts the start-up control method provided in the above embodiments. The specific implementation logic can be referred to the relevant introduction of the start-up control method provided in the foregoing embodiments, and will not be repeated here.

[0113] The invention has been described in particular detail above with respect to possible scenarios, and those skilled in the art will recognize that the invention can be practiced through other embodiments. Specific naming of components, capitalization of terms, attributes, data structures, or any other programming or structural aspects are not mandatory or important, and the mechanisms or features of implementing the invention may have different names, forms, or procedures. The system can be implemented through a combination of hardware and software (as described), entirely through hardware elements, or entirely through software elements. The specific division of functions among the various system components described herein is merely exemplary and not mandatory; rather, the functions performed by a single system component can be performed by multiple components, or the functions performed by multiple components can be performed by a single component.

[0114] Those skilled in the art should understand that the various steps of the disclosed methods can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. Optionally, they can be implemented using device-executable program code, which can then be stored in a storage device for execution by the computing device. Alternatively, they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Therefore, the embodiments disclosed in this invention are not limited to any specific hardware and software combination.

[0115] The programs (also referred to as programs, software, software applications, or code) executable by these computing devices include machine instructions of a programmable processor and can be implemented using high-level procedural and / or object-oriented programming languages, and / or assembly / machine languages. As used herein, the terms “machine-readable medium” and “computer-readable medium” refer to any computer program product, device, and / or apparatus (e.g., disk, optical disk, memory, programmable logic device (PLD)) used to provide machine instructions and / or data to a programmable processor, including machine-readable media that receive machine instructions as machine-readable signals. The term “machine-readable signal” refers to any signal used to provide machine instructions and / or data to a programmable processor.

[0116] Certain aspects of this invention include the process steps and instructions described herein in algorithmic form. It should be noted that the process steps and instructions of this invention can be implemented in software, firmware, and / or hardware, and when implemented in software, they can be downloaded, stored on various operating systems and operated from said platforms.

[0117] Those skilled in the art will understand that the structures shown in the figures are merely block diagrams of some structures related to the present application and do not constitute a limitation on the terminal device to which the present application is applied. Specific terminal devices may include more or fewer components than those shown in the figures, or combine certain components, or have different component arrangements.

[0118] In the description of this specification, the use of terms such as "one embodiment," "some embodiments," "example," "specific example," or "possible design," etc., refers to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is 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.

[0119] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A startup control method for a cascaded reformer, characterized in that, The cascaded reformer includes at least two stages of reformers, and each stage of the cascaded reformer is configured according to the available gas volume. The start-up control method includes: Obtain the reforming gas requirements for SOFC stacks; Control commands for the cascaded reformer are generated based on the required reformer gas quantity. According to the control commands and the available gas supply of each reformer, the reformers at each stage are started up one by one to supply gas to the SOFC stack. The step-by-step startup of each stage of the reformer based on the control command and the available gas supply of each stage of the reformer includes: Obtain the available gas volume for each stage of the reformer; Based on the control command, each stage of the reformer is started sequentially from low to high according to the available gas volume; The step of activating each stage of the reformer in ascending order of gas supply based on the control command includes: The reformer with the lowest available gas volume is activated based on control commands; When the gas supply of the smallest-level reformer cannot meet the reforming gas demand of the SOFC stack, the next-level reformer is started until the total gas supply of the cascaded reformers meets the reforming gas demand of the SOFC stack. The startup control method further includes: Obtain temperature change information of SOFC stack; The reforming gas requirement of the SOFC stack is determined based on temperature change information. The high-temperature flue gas is controlled to be introduced into each stage of the reformer from low to high according to the available gas volume; The flow rate of high-temperature flue gas is controlled to control the preheating temperature of the reformer, so that the start-up time of each stage of the reformer matches the temperature switching time of the SOFC stack.

2. A start-up control device for a cascaded reformer, used to execute the start-up control method as described in claim 1, characterized in that, include: The reforming gas acquisition unit is configured to acquire the reforming gas demand of the SOFC stack. The instruction generation unit is configured to generate control instructions for the cascaded reformer based on the reformer gas demand. The control unit is configured to control the sequential startup of each stage of the reformer according to the control commands and the available gas supply of each stage of the reformer, so as to supply gas to the SOFC stack.

3. The start-up control device according to claim 2, characterized in that, The start-up control device further includes: The temperature information acquisition unit is configured to acquire temperature change information of the SOFC stack.

4. A SOFC power generation system based on a cascaded reformer, characterized in that, This includes cascaded reformers, controllers, and SOFC stack systems; The cascaded reformer includes at least two stages of reformers, and each stage of the cascaded reformer is set according to the available gas volume. Reformers of the same stage are connected in parallel, and the reformed gas generated by each stage of the reformer is controlled and distributed to the SOFC stack system by the controller. The controller is connected to the cascaded reformer and the SOFC stack system, respectively. The controller uses the start-up control method as described in claim 1 to control the start-up of each stage of the cascaded reformer in order to supply gas to the SOFC stack system.

5. The SOFC power generation system according to claim 4, characterized in that, The gas supply range of each stage of the reformer is set according to the reforming gas demand corresponding to the operating state of the SOFC stack system and the number of SOFC stacks in the SOFC stack system.

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