Solid oxide cell stack system including multi-stream SOC stack heat exchanger

Abstract

The SOC stack system includes one or more solid oxide cell stacks and a multi-stream solid oxide cell stack heat exchanger.

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to a solid oxide cell (SOC) stack system that includes one or more SOC stacks and a multi-stream SOC stack heat exchanger. [Background technology]

[0002] 2. Background of the Invention In a SOC stack, with an operating temperature of 600°C-1000°C, preferably 600°C-850°C, multiple cell units are assembled to form a stack and are connected to each other by interconnectors. The interconnects act as a gas barrier separating the anode and cathode sides of adjacent cell units while allowing the conduction of electrical current between adjacent cells, i.e., between the anode of one cell and the cathode of the adjacent cell. In addition, the interconnects usually have multiple flow paths for the passage of process gases on both sides of the interconnect. To optimize the performance of a SOC stack, it is necessary to maximize a range of favorable values ​​without unacceptable consequences for another range of associated unfavorable values ​​that should be minimized. These values ​​include:

[0003] Value to be maximized Value to be minimized - Process gas usage - Cost - Electrical efficiency - Dimensions - Lifespan - Manufacturing time - Defect rate - Number of parts - Material usage - Parasitic losses (heating, cooling, blowers, etc.)

[0004] Almost all of the above values ​​are interrelated, meaning that changing one value will affect the others. Here are some relationships between the process gas flow properties in the cell and the above values:

[0005] Process gas utilization: The flow paths on the interconnect should be designed to provide equal amounts of process gas to each cell in the stack, i.e. there should be no flow "shortcuts" through the stack.

[0006] Parasitic losses: The design of the process gas flow paths in the SOC stack and its cell units should strive for low pressure drop per unit volume, thereby reducing parasitic losses to the blower.

[0007] Electrical Efficiency: The interconnector conducts the electric current between the anode and cathode layers of adjacent cells, so that in order to reduce the internal resistance, the electrically conductive contacts (hereinafter simply referred to as "contacts") of the interconnector should be designed to establish good electrical contact with the electrodes (anode and cathode) and the contacts should not be separated anywhere, since in that case the current would be forced to flow through the electrodes for a longer distance, resulting in a higher internal resistance.

[0008] lifespan: It is desirable that the lifetime of the SOC stack is maximized, i.e., in SOC mode, the amount of electrolysis products (e.g., HO and / or CO) is maximized. The lifetime of the stack depends on many factors, such as the selection of interconnects and spacers, flow distribution on both process gas sides of the interconnect, uniformly distributed protective coatings on the materials, operating conditions (temperature, current density, voltage, etc.), cell design and materials, and many other factors.

[0009] cost: The cost of an SOC stack can be reduced by eliminating the use of scarce materials, reducing the manufacturing time of the SOC stack, minimizing the number of parts, and minimizing material waste (the amount of material wasted during the manufacturing process).

[0010] size: The overall dimensions of the cell stack are reduced when the design of the stack and its components ensures high utilization of the available cell area, the dead areas with low process gas flow rates should be reduced, and the inactive zones for the sealing surfaces should be minimized.

[0011] Production time: The manufacturing time of the SOC stack should be minimized, and the interconnect design should also contribute to fast assembly of the entire stack. Generally, stack design for every component is not necessary, as this would increase manufacturing time.

[0012] Defect Rate: The manufacturing methods and materials for the stack components should allow for low defect rates (e.g., undesirable holes in the interconnect gas barrier, non-uniform material thickness or properties). Furthermore, when the interconnect design reduces the total number of parts to be assembled and reduces the length and number of sealing surfaces, it can reduce the defect rate of the assembled cell stack.

[0013] Number of parts: As already mentioned, in addition to minimizing errors and assembly time, reduced part count reduces costs.

[0014] How the anode and cathode gas flows are distributed in the SOC stack is by providing a common manifold for each of the two process gases, oxygen and fuel gas. These manifolds can be either internal or external. The manifolds deliver the process gases to the individual layers in the SOC stack by way of flow paths to each layer. These flow paths are usually located in one layer of the repeating elements contained in the SOC stack, i.e. the spacer or interconnect. Internal gas manifolds are often in the form of openings in the cell and / or interconnect components, which form one or more channels and gas inlets when the cell components are stacked. On the other hand, external manifolds are often formed as covers, for example, that cover one or more sides of the SOC stack, thereby distributing the process gases to the sides of the stack and thus to the ends of each cell in the stack. Instead of a cover, the stack can also be placed in a container through which the process gases flow, allowing the process gases to access the sides of the stack.

[0015] In the following, the system is described in relation to a solid oxide electrolysis cell (SOEC). However, it should be understood that the system can also be utilized with solid oxide fuel cells (SOFCs). High temperature electrolysis (SOC) is the endothermic electrochemical conversion of H2O to H2 or CO2 to CO on the fuel side of the fuel cell. The endothermic electrochemical process is counterbalanced by heat generated inside the SOC stack from ohmic losses (Joule heating), which is proportional to the current flowing through the stack. If the endothermic process balances the ohmic losses, the stack can operate "thermally neutrally". However, at many operating points, especially at partial load, the heat generated by the ohmic losses is less than the heat consumed in the electrochemical process. This creates a temperature profile across the cell, decreasing from inlet to outlet.

[0016] The local current density (i) in a given region of the cell is controlled by the Nernst potential, which is in turn influenced by the local temperature and gas composition. The local gas composition is controlled by the stack design, for example the choice of flow paths. In this case, the goal is to have as uniform a gas distribution as possible throughout the cell, between cells in the stack and between stacks, while at the same time minimizing pressure losses. However, even with perfect flow distribution, there will always be a higher fuel concentration (lower product concentration) at the fuel inlet, which will result in a higher than average current density. If the stack is operated at an operating point (current) below thermal neutrality, the temperature at the fuel inlet will be higher than in the rest of the cell, further increasing the local current density. Thus, for most operating points, the maximum current density (imax) is located in the fuel inlet region.

[0017] Some degradation mechanisms are highly sensitive to current density and may even be accelerated above a certain "threshold" current density. For example, Chen et al. (Journal of The Electrochemical Society, 160(8)F883-F891(2013)) show that additional degradation mechanisms, such as the formation of ZrO2 nanoparticles, were observed in SOCs operated at high current densities (1A / cm2 or 1.5A / cm2 in electrolysis mode), while the same degradation mechanisms were absent in tests operated at 0.75A / cm2 or 0.5A / cm2 in electrolysis mode. In another example (Knibbe et al.,Journal of The Electrochemical Society, 157(8)B1209-B1217(2010)), increased degradation of ohmic resistance due to oxygen bubble formation and delamination at the oxygen electrode / electrolyte interface was observed when increasing the electrolysis current from 1A / cm2 to 1.5A / cm2 to 2A / cm2. Mogensen et al. reported that in SOCs based on Ni / YSZ electrodes, operation at high current densities (high electrode overpotentials) can lead to the loss of Ni from the electrochemically active anode / electrolyte interface (Fuel Cells, 17, 2017, No. 4, 434-441). In the SOFC mode, Hagen et al. (Journal of The Electrochemical Society, 153(6) A1165-A1171(2006)) demonstrated that the degradation rate increased as a function of cell polarization (current density) at all operating temperatures tested (750°C, 850°C, 950°C). The degradation rate at a constant current density increased more steeply at 750°C than at 850°C (and 950°C), suggesting that the degradation phenomenon is related to the electrode overpotentials.

[0018] Therefore, to minimize stack degradation and loss of system efficiency, it is highly desirable to keep the maximum current density (imax) as low as possible while maintaining a high production rate (iavg). In other words, it is desirable to obtain a uniform current density profile throughout the stack, especially a low imax while maintaining a constant iavg.

[0019] The production rate from a stack is linked to the active area (the area where the electrochemical processes occur), so it is desirable to maximize the active area. The active area of ​​a stack is naturally linked to the size of the cell, but the active area of ​​a cell is reduced by the area used for sealing areas and manifolds. It is therefore desirable to maximize the active area (active surface area) of a cell by reducing the area used for sealing and manifolds.

[0020] In SOC mode, the product is the transformed gas, and the quality of the transformed gas (also called product gas) is critical for downstream applications. Therefore, to obtain high purity, it is desirable to minimize the leakage of undesirable components (such as air) into the product.

[0021] Since the SOEC process operates at a high temperature level and consists of two fluids, a process fluid and an oxy fluid, the cold process and oxy feeds must be heated to the SOEC temperature. Primary heating is provided by heat exchange with the hot SOEC fluid. Balance heat is added, for example, by one or more electric heaters. Adding a heat exchanger to an SOE stack system raises issues regarding cost, defect rate, number of parts, size, manufacturing time, etc., as mentioned before.

[0022] US2021098796 discloses a modular pressurized hot box for use and replacement in a variety of pressurized electrochemical applications including reversible solid oxide electrolyzers and fuel cells, energy storage systems, renewable fuel production, solid-state hydrogen pumps and liquefaction, oxygen transport membranes, etc. This is made possible by mixed electronically and ionically conductive compositions of vanadia-yttria and vanadia-calcia stabilized zirconia and a dry powder fabrication method for the ceramic core stack.

[0023] US2021156039 describes a modular system for hydrogen production that includes a plurality of cores and a hub. Each core includes an electrolyzer and a power source. The power source is operable to manage power to the electrolyzer of the core and is redundant to the power source of at least another of the plurality of cores. The hub includes a water module, a heat exchange module, and a switch module. The water module includes a water source in fluid communication with the electrolyzer of each one of the plurality of cores, the heat exchange module includes a heat exchanger in thermal communication with the electrolyzer of each one of the plurality of cores, and the switch module includes a switch operable to electrically isolate the power source of each one of the plurality of cores.

[0024] WO15169940 discloses a core unit in the form of an integrated module for fuel cell based power generation, consisting of an inlet or inlets for fuels suitable for the fuel cell, said fuels including hydrogen, hydrocarbon based fuels, steam reformed fuels (hydrocarbons, alcohols and ethers etc.) and ammonia, one or more inlets for air, one or more off-gas outlets, a heat exchanger and a fuel cell assembly, all mounted in an insulated housing or in a number of separate insulated housings connected by associated piping. The unit is a SOFC subsystem, designed to provide a simple interface to natural gas based SOFC technology, preferably in the range of 1.5kW (DC) output. The system features a tight integration of the SOFC stack or stack modules with all hot balance of plant components. The system is designed for anode off-gas recycling, so that no external water supply is required after start-up. The reuse of anode gas results in a high overall fuel utilization and high electrical efficiency.

[0025] WO20165548 discloses an electrolysis cell for electrolytic treatment of a liquid, the electrolysis cell including: a receptacle defining an electrolysis chamber; a first set of conductive plates, a second set of conductive plates, and a third set of conductive plates disposed within the electrolysis chamber, the first set, the second set, and the third set of conductive plates extending radially relative to a longitudinal axis of the receptacle; a power source configured to supply electricity to the first, second, and third sets of conductive plates; a switching device configured to interrupt the supply of electricity to the first, second, and third sets of conductive plates and modify the electrical connection between the first, second, and third sets of conductive plates and positive and negative terminals of the power source; and a control unit configured to control the switching device according to an operating cycle. [Prior art documents] [Patent documents]

[0026] [Patent Document 1] US2021098796 [Patent Document 2] US2021156039 [Patent Document 3] WO15169940 Summary of the Invention [Problem to be solved by the invention]

[0027] None of the above-mentioned prior art documents provide a solution to the above-mentioned problems that are solved by the present invention.

[0028] Therefore, in view of the considerations listed above, there is a need for an SOC stack system that includes an improved and efficient means of heat exchange to alleviate some of the problems discussed above.

[0029] These and other objects are accomplished by the invention described below. [Means for solving the problem]

[0030] Summary of the Invention According to the present invention, there is provided a solid oxide cell stack system including one or more solid oxide cell stacks (solid oxide battery stacks). Each of the solid oxide cell stacks includes a process fluid side and an oxy-fluid side (oxygen fluid side) as described above. The process fluid side includes at least one stack process fluid inlet and at least one stack process fluid outlet, allowing the process fluid to be supplied to the stack and the process fluid to be discharged from the SOC stack. The oxy-fluid side similarly includes at least one stack oxy-fluid inlet and at least one stack oxy-fluid outlet, allowing the oxy-fluid to be provided to and discharged from the SOC stack.

[0031] Further, the SOC stack system includes a multi-stream SOC stack heat exchanger. According to the present invention, the process side fluid and the oxy side fluid are heated and cooled in a single multi-stream SOC heat exchanger. This is advantageous compared to having separate heat exchangers for the process side of the SOC stack and separate heat exchangers for the oxy side of the SOC stack. In the multi-stream SOC stack heat exchanger, the cold side and the hot side of the two fluids (process side and oxy side) are alternately heat exchanged in separate passes of the multi-stream SOC stack heat exchanger. This ensures uniform heating of both the process side and the oxy side of the fluids, and obviously allows the use of a single heater to maintain the SOC stack temperature. Thus, according to the present invention, not only is the number of components reduced in terms of the required heat exchange (and all the following advantages as mentioned above), but also in terms of the required heating by using only a single heater. Furthermore, this also reduces the need for equipment to control and maintain uniform heating of both sides (process and oxy) and protect against high temperature differences.

[0032] The multi-stream SOC stack heat exchanger has at least eight fluid connections, i.e. at least four inlets and at least four outlets. The process and oxy sides exchange heat alternately, i.e. two passes exchange heat between the cold / hot process side, then two passes exchange heat between the cold / hot oxy side. More particularly, the at least eight fluid connections include: a first heat exchanger process fluid inlet in fluid communication with an upstream process fluid source; a second heat exchanger process fluid inlet in fluid communication with the stack process fluid outlet upstream; a first heat exchanger process fluid outlet in fluid communication with the first heat exchanger process fluid inlet on the upstream side and in fluid communication with the stack process fluid inlet on the downstream side; a second heat exchanger process fluid outlet in fluid communication with the second heat exchanger process fluid inlet on the upstream side and in fluid communication with the process fluid outlet on the downstream side; a first heat exchanger oxy-fluid inlet in fluid communication with an upstream oxy-fluid source; a second heat exchanger oxy-fluid inlet in fluid communication with the stack oxy-fluid outlet upstream; a first heat exchanger oxy-fluid outlet in fluid communication with the first heat exchanger oxy-fluid inlet on the upstream side and in fluid communication with the stack oxy-fluid inlet on the downstream side; a second heat exchanger oxy-fluid outlet in fluid communication with the second heat exchanger oxy-fluid inlet on the upstream side and in fluid communication with the oxy-fluid outlet on the downstream side;

[0033] In one embodiment of the present invention, the one or more SOC stacks are SOEC stacks. As mentioned above, the present invention is applicable to SOC stacks operating in electrolysis mode as well as fuel mode, both of which may require heat exchange. Also, in one embodiment of the present invention, the SOC stack system includes both SOEC and SOFC stacks. In a further embodiment, the SOEC stack according to the present invention is a 20,000 mm 2 ~160000MM 2cell (one side of the cell), with the cell area between pr.

[0034] In one embodiment of the present invention, the multi-stream SOC stack heat exchanger is a plate type heat exchanger. This embodiment is also the embodiment shown in the figures which will be described in more detail. In one embodiment of the present invention, the relatively low temperature process fluid passage of the SOC stack heat exchanger exchanges heat with the relatively high temperature process fluid passage of the multi-stream SOC stack heat exchanger. However, in addition, the relatively low temperature oxy-fluid passage of the multi-stream SOC stack heat exchanger exchanges heat with the relatively high temperature oxy-fluid passage of the multi-stream SOC stack heat exchanger; furthermore, the process fluid side and the oxy-fluid side of the multi-stream SOC stack heat exchanger exchange heat alternately. Thus, as one of the advantages of the present invention, not only do the process oxy hot (hot) / cold (cold) streams exchange heat, but the oxy hot (hot) / cold (cold) streams also exchange heat in the same device, the multi-stream SOC stack heat exchanger, and further, the oxy process stream and the process stream are also alternately heat exchanged in this same device, resulting in very uniform temperatures for all fluid streams in a compact and efficient device that is cheaper, has less heat loss, has fewer parts, to name a few advantages when compared to known solutions.

[0035] However, this is not the only advantage, and in an embodiment of the present invention, the system further comprises at least one heater adapted to heat the process fluid, the oxy-fluid, or both the process fluid and the oxy-fluid. Since all the fluid streams pass through the multi-stream SOC stack heat exchanger, a heater that heats only one of the fluid streams upstream of the multi-stream SOC stack heat exchanger is sufficient, as this fluid stream then transfers heat to the rest of the fluid streams when exchanging heat with all of them in the multi-stream SOC stack heat exchanger. Of course, there may be more heaters or one heater may heat multiple fluid streams, whichever is most efficient and beneficial, but one advantage of the present invention is that it provides an even heat distribution to all the fluid streams, and thus the SOC stack, in an efficient, compact and simple manner, which can also be seen to ensure a more even temperature distribution than would be the case if more heat exchangers were used.

[0036] In one embodiment of the present invention, at least one heater may even be integrated into the multi-stream SOC heat exchanger, thereby reducing heat loss and the physical size of the device. In further embodiments, the heater may be integrated into one or more SOC stacks, reducing the number of parts, the physical size, and the heat loss to the surroundings. In one embodiment of the present invention, the heater may be an electric heater.

[0037] In one embodiment of the present invention, the multi-stream SOC heat exchanger further comprises at least two fluid connections: a heating fluid inlet and a heating fluid outlet. The heater comprises a heating fluid in fluid communication with the multi-stream SOC heat exchanger via the heating fluid inlet and the heating fluid outlet. Thus, the heating fluid is heated in the heater and delivers this heat to the process fluid and the oxy-fluid in the multi-stream SOC heat exchanger as the heating fluid exchanges heat in the multi-stream SOC heat exchanger.

[0038] In a further embodiment of the invention, the multi-stream SOC stack heat exchanger is arranged in a thermally insulated container that also constitutes the SOC stack or stacks, which has the advantage, among other things, of reducing heat losses. However, in one embodiment of the invention, the multi-stream SOC stack heat exchanger can also be arranged outside the thermally insulated container that constitutes the SOC stack or stacks, which can be an advantage in cases where the SOC stack needs to be replaced or where it is better to insulate it without the multi-stream SOC stack heat exchanger for other reasons.

[0039] Features of the invention Feature 1 1. A solid oxide cell stack system comprising one or more solid oxide cell stacks, each solid oxide cell stack includes a process fluid side and an oxy-fluid side, the process fluid side having at least one stack process fluid inlet and at least one stack process fluid outlet; the oxy-fluid side includes at least one stack oxy-fluid inlet and at least one stack oxy-fluid outlet; The solid oxide cell stack system further comprises: A multi-stream solid oxide cell stack heat exchanger including at least eight fluid connections: a first heat exchanger process fluid inlet in fluid communication with the stack process fluid outlet upstream; a second heat exchanger process fluid inlet in fluid communication with the upstream process fluid source; a first heat exchanger process fluid outlet in fluid communication with the first heat exchanger process fluid inlet on the upstream side and in fluid communication with the process fluid exhaust on the downstream side; a second heat exchanger process fluid outlet in fluid communication with the second heat exchanger process fluid inlet on the upstream side and in fluid communication with the stack process fluid inlet on the downstream side; a first heat exchanger oxy-fluid inlet in fluid communication with the stack oxy-fluid outlet upstream; a second heat exchanger oxy-fluid inlet in fluid communication with the upstream oxy-fluid source; a first heat exchanger oxy-fluid outlet in fluid communication with the first heat exchanger oxy-fluid inlet on the upstream side and in fluid communication with the oxy-fluid outlet on the downstream side; a second heat exchanger oxy-fluid outlet in fluid communication with the second heat exchanger oxy-fluid inlet on the upstream side and in fluid communication with the stack oxy-fluid inlet on the downstream side; The solid oxide cell stack system.

[0040] Feature 2 2. The solid oxide cell stack system of claim 1, wherein the one or more solid oxide cell stacks are solid oxide electrolysis cell stacks.

[0041] Feature 3 The cell area of ​​each solid oxide electrolysis cell stack is 20,000MM 2 ~160000MM 2 3. The solid oxide electrolysis cell stack system according to claim 2, wherein

[0042] Feature 4 2. The solid oxide cell stack system of claim 1, comprising a solid oxide electrolysis cell stack and a solid oxide fuel cell stack.

[0043] Feature 5 5. The solid oxide cell stack system according to any one of Features 1 to 4, wherein the multi-stream solid oxide cell stack heat exchanger is a plate heat exchanger.

[0044] Feature 6 6. The solid oxide cell stack system of claim 5, wherein a relatively low temperature process fluid passage of the multi-stream solid oxide cell stack heat exchanger exchanges heat with a relatively high temperature process fluid passage of the multi-stream solid oxide cell stack heat exchanger; and a relatively low temperature oxy-fluid passage of the multi-stream solid oxide cell stack heat exchanger exchanges heat with a relatively high temperature oxy-fluid passage of the multi-stream solid oxide cell stack heat exchanger, thereby alternating heat exchange between the process fluid side and the oxy-fluid side of the multi-stream solid oxide cell stack heat exchanger.

[0045] Feature 7 7. The solid oxide cell stack system of any one of features 1 to 6, wherein the system further comprises at least one heater adapted to heat the process fluid, the oxy-fluid, or both the process fluid and the oxy-fluid.

[0046] Feature 8 8. The solid oxide cell stack system of claim 7, wherein the heater is integrated within the multi-stream solid oxide cell stack heat exchanger.

[0047] Feature 9 8. The solid oxide cell stack system of claim 7, wherein the heater is integrated within one or more solid oxide cell stacks.

[0048] Feature 10 10. The solid oxide cell stack system of claim 7, 8 or 9, wherein the heater is an electric heater.

[0049] Feature 11 9. The solid oxide cell stack system of feature 7 or 8, wherein the multi-stream solid oxide cell stack heat exchanger further has two fluid connections, a heating fluid inlet and a heating fluid outlet, and the heater comprises a heating fluid in fluid communication with the multi-stream solid oxide cell stack heat exchanger via the heating fluid inlet and the heating fluid outlet.

[0050] Feature 12 The solid oxide cell stack system of any of the preceding features, wherein the multi-stream solid oxide cell stack heat exchanger is disposed within an insulated enclosure further containing one or more solid oxide cell stacks.

[0051] Feature 13 13. The solid oxide cell stack system according to any one of Features 1 to 12, wherein the multi-stream solid oxide cell stack heat exchanger is disposed outside an insulated container comprising one or more solid oxide cell stacks. [Brief description of the drawings]

[0052] BRIEF DESCRIPTION OF THE DRAWINGS The invention is further illustrated by the accompanying drawings, which show examples of embodiments of the invention, it being understood that the claimed invention covers embodiments other than those shown in the drawings, which serve the purpose of explaining the invention by way of example.

[0053] FIG. 1 is a schematic / principled side cross-sectional view of a multi-stream SOC stack heat exchanger according to one embodiment of the present invention, particularly the process fluid side.

[0054] FIG. 2 is a schematic / principled side cross-sectional view of a multi-stream SOC stack heat exchanger according to one embodiment of the present invention, specifically the oxy-fluid side.

[0055] FIG. 3 is a schematic / principal top cross-sectional view of a multi-stream SOC stack heat exchanger according to one embodiment of the present invention, specifically the hotter fluid side.

[0056] FIG. 4 is a schematic / principal top cross-sectional view of a multi-stream SOC stack heat exchanger according to one embodiment of the present invention, specifically the cooler fluid side.

[0057] Position number 01. Multi-stream SOC stack heat exchanger 02. First multi-stream SOC stack heat exchanger process fluid inlet 03. Second multi-stream SOC stack heat exchanger process fluid inlet 04. First multi-stream SOC stack heat exchanger process fluid outlet 05. Second multi-stream SOC stack heat exchanger process fluid outlet 06. First multi-stream SOC stack heat exchanger oxy-fluid inlet 07. Second multi-stream SOC stack heat exchanger oxy-fluid inlet 08. First multi-stream SOC stack heat exchanger oxy-fluid outlet 09. Second multi-stream SOC stack heat exchanger oxy-fluid outlet 10. Multi-stream SOC stack heat exchanger plate layer

[0058] Detailed Description FIG. 1 is a schematic / principle cross-sectional side view of a multi-stream SOC stack heat exchanger 01 according to an embodiment of the present invention, in particular the process fluid side. The SOC stack part of the SOC stack system is not shown, but it is understood that the SOC stack part is in fluid connection with the multi-stream SOC stack heat exchanger part of the system, as explained above and according to the claims. In this embodiment, the multi-stream SOC stack heat exchanger is of the plate heat exchanger type, such that the multi-stream SOC stack heat exchanger includes 18 individual multi-stream SOC stack heat exchanger plate layers 10, as can be seen in principle. In order to explain the principle in a more simplified manner, FIG. 1 focuses on the process fluid side, in particular the relatively high temperature parts of the process fluid side of the multi-stream SOC stack heat exchanger.

[0059] Via the first multi-stream SOC stack heat exchanger process fluid inlet 02, a relatively hot process fluid stream is led from the SOC stack (not shown) and enters and is distributed among the five single plate layers of the multi-stream SOC stack heat exchanger; before the now heat-exchanged (cooled) process fluid stream leaves the multi-stream SOC stack heat exchanger via the first multi-stream SOC stack heat exchanger process fluid outlet 04. In the multi-stream SOC stack heat exchanger, the relatively hot process fluid stream is not only heat-exchanged with the relatively cold process fluid stream, but also with the oxy-fluid, as will be further explained with reference to the remaining figures. The heated process fluid leaving the multi-stream SOC stack heat exchanger is further led to the process fluid inlet (not shown) of the SOC stack, possibly via one or more heaters. Thus, as shown in FIG. 1, the relatively high temperature process fluid stream flows only every fourth plate layer of the multi-stream SOC stack heat exchanger, while the remaining layers have relatively low temperature process fluid streams, with the relatively high temperature oxy-fluid streams flowing alternately with the low temperature oxy-fluid streams.

[0060] In Fig. 2, a schematic / principle side cross-sectional view of a multi-stream SOC stack heat exchanger 01 according to an embodiment of the invention, in particular the oxy-fluid side, is shown. Before the now heat-exchanged (cooled) process fluid stream leaves the multi-stream SOC stack heat exchanger via the first multi-stream SOC stack heat exchanger oxy-fluid outlet 08; a relatively hot oxy-fluid stream, corresponding to the process fluid side and leaving the SOC stack, is led from the SOC stack (not shown), enters via the first multi-stream SOC stack heat exchanger oxy-fluid inlet 06 and is distributed to (in this case) four single plate layers of the multi-stream SOC stack heat exchanger. In the multi-stream SOC stack heat exchanger, the relatively hot oxy-fluid stream is heat exchanged not only with the relatively cold oxy-fluid stream but also with the process fluid. The heated oxy-fluid leaving the multi-stream SOC stack heat exchanger is led further to the oxy-fluid inlet (not shown) of the SOC stack, possibly via one or more heaters. Thus, as shown in FIG. 2, the relatively high temperature oxy-fluid flows only every fourth plate layer of the multi-stream SOC stack heat exchanger, while the remaining layers have a relatively low temperature oxy-fluid stream, with the relatively high temperature process fluid stream and the low temperature process fluid stream flowing alternately.

[0061] 3 and 4 show schematic / principal top cross-sectional views of a multi-stream SOC stack heat exchanger according to an embodiment of the present invention. In order to visualize the eight fluid connections, the inlets and outlets of both the relatively cold and relatively hot fluid sides are shown. In FIG. 3, the focus is on the relatively hot fluid streams entering the multi-stream SOC stack heat exchanger via the first multi-stream SOC stack heat exchanger-process fluid inlet 02 and-oxy-fluid inlet 06. These relatively hot fluids pass through their respective separate plate layers, which cannot all be seen in this top view, but are shown here diagrammatically as thick filled arrows associated with the process fluids and unfilled arrows associated with the oxy-fluids. After passing through the plate layers, the now heat exchanged / cooled process and oxy-fluid streams exit via the first multi-stream SOC stack heat exchanger process fluid outlet 04 and oxy-fluid outlet 08.

[0062] Thus, Figure 4 focuses on the relatively cool fluid streams entering the multi-stream SOC stack heat exchanger via the second multi-stream SOC stack heat exchanger-process fluid inlet 03 and -oxy-fluid inlet 07. These relatively hot fluids pass through each separate plate layer, again shown diagrammatically as bold filled arrows for the process fluids and unfilled arrows for the oxy-fluids. After passing through the plate layers, the now heat exchanged / heated process and oxy-fluid streams exit via the second multi-stream SOC stack heat exchanger process fluid outlets 05 and 08 and the second multi-stream SOC stack heat exchanger oxy-fluid outlet 09.

Claims

1. 1. A solid oxide cell stack system comprising one or more solid oxide cell stacks, each solid oxide cell stack includes a process fluid side and an oxy-fluid side, the process fluid side having at least one stack process fluid inlet and at least one stack process fluid outlet; the oxy-fluid side includes at least one stack oxy-fluid inlet and at least one stack oxy-fluid outlet; The solid oxide cell stack system further comprises: A multi-stream solid oxide cell stack heat exchanger including at least eight fluid connections: a first heat exchanger process fluid inlet in fluid communication upstream with the stack process fluid outlet; a second heat exchanger process fluid inlet in fluid communication with an upstream process fluid source; a first heat exchanger process fluid outlet in fluid communication with the first heat exchanger process fluid inlet on an upstream side and in fluid communication with the first heat exchanger process fluid outlet on a downstream side; a second heat exchanger process fluid outlet in fluid communication with the second heat exchanger process fluid inlet on the upstream side and in fluid communication with the stack process fluid inlet on the downstream side; a first heat exchanger oxy-fluid inlet in fluid communication with the stack oxy-fluid outlet upstream; a second heat exchanger oxy-fluid inlet in fluid communication with an upstream oxy-fluid source; a first heat exchanger oxy-fluid outlet in fluid communication with the first heat exchanger oxy-fluid inlet on an upstream side and in fluid communication with the first heat exchanger oxy-fluid outlet on a downstream side; a second heat exchanger oxy-fluid outlet in fluid communication with the second heat exchanger oxy-fluid inlet on an upstream side and in fluid communication with the stack oxy-fluid inlet on a downstream side; The solid oxide cell stack system.

2. 10. The solid oxide cell stack system of claim 1, wherein the one or more solid oxide cell stacks are solid oxide electrolysis cell stacks.

3. The cell area of ​​each solid oxide electrolysis cell stack is 20,000 mm ２ ~160,000MM ２ 3. The solid oxide electrolysis cell stack system according to claim 2, wherein:

4. The solid oxide cell stack system of claim 1 , comprising a solid oxide electrolysis cell stack and a solid oxide fuel cell stack.

5. The solid oxide cell stack system according to any one of claims 1 to 4, wherein the multi-stream solid oxide cell stack heat exchanger is a plate heat exchanger.

6. 6. The solid oxide cell stack system of claim 5, wherein a relatively low temperature process fluid passage of said multi-stream solid oxide cell stack heat exchanger exchanges heat with a relatively high temperature process fluid passage of said multi-stream solid oxide cell stack heat exchanger; and a relatively low temperature oxy-fluid passage of said multi-stream solid oxide cell stack heat exchanger exchanges heat with a relatively high temperature oxy-fluid passage of said multi-stream solid oxide cell stack heat exchanger, whereby the process fluid side and the oxy-fluid side of said multi-stream solid oxide cell stack heat exchanger alternate in heat exchange.

7. 7. The solid oxide cell stack system of claim 1, wherein the system further comprises at least one heater adapted to heat the process fluid, the oxy-fluid, or both the process fluid and the oxy-fluid.

8. The solid oxide cell stack system of claim 7 , wherein the heater is integrated within the multi-stream solid oxide cell stack heat exchanger.

9. The solid oxide cell stack system of claim 7 , wherein the heater is integrated within the one or more solid oxide cell stacks.

10. 10. The solid oxide cell stack system of claim 7, 8 or 9, wherein the heater is an electric heater.

11. 9. The solid oxide cell stack system of claim 7 or 8, wherein the multi-stream solid oxide cell stack heat exchanger further has two fluid connections, a heating fluid inlet and a heating fluid outlet, and the heater comprises a heating fluid in fluid connection with the multi-stream solid oxide cell stack heat exchanger via the heating fluid inlet and the heating fluid outlet.

12. The solid oxide cell stack system according to any one of claims 1 to 11, wherein a multi-stream solid oxide cell stack heat exchanger is disposed within an insulated vessel further containing the one or more solid oxide cell stacks.

13. The solid oxide cell stack system according to any one of claims 1 to 12, wherein a multi-stream solid oxide cell stack heat exchanger is disposed outside an insulated enclosure comprising the one or more solid oxide cell stacks.

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