Stack modules and how to use them

Abstract

The object of the present invention is a stack module for a solid oxide cell stack comprising a fuel inlet manifold (150) and a fuel outlet manifold (152) between two adjacent stacks (103). The stack module comprises at least two stack bundles, each stack bundle comprising a row or matrix of stacks (103) together with a fuel inlet manifold (150) that supplies fuel to the stacks and a fuel outlet manifold (152) that collects fuel gas from the stacks (103), connected in parallel to the manifolds (150, 152) with respect to the fuel inlet and fuel outlet, the stack module is housed within an airtight cover (169) and includes the necessary interfaces to and from the airtight cover (169), the fuel gas flow characteristics within the manifolds (150, 152) are determined based on the pressure drop characteristics of the manifolds (150, 152) and the stacks connected in parallel thereto, the manifolds and The stack is optimized for the size of the holes connecting the stacks, electrically isolated from the fuel manifold structures (150, 152) by an electrically insulating structure (172), the other end of the stack is electrically isolated from other structures, the stack module includes a side seal structure (166) between adjacent stacks (103a) in the stack bundle and between the stacks (103b) at the end of the bundle and an airtight cover (169) to prevent air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stack, the side seal structure is electrically insulating, and the stack bundle includes at least one of an integrated structure of the air inlet section (106) and an integrated structure of the air outlet section (176) of an adjacent parallel-connected cell stack (103) bundle.

Description

[Technical Field]

[0001] The present invention relates to a stack module and a method for using the same. [Background technology]

[0002] The majority of the world's energy is produced by oil, coal, natural gas, or nuclear power. All of these production methods have their own unique problems, for example, in terms of availability and environmental friendliness. As far as the environment is concerned, oil and coal, in particular, cause pollution when they are burned. The problem with nuclear power, at the very least, is the storage of spent fuel.

[0003] In particular, due to environmental concerns, new energy sources are being developed that are more environmentally friendly and, for example, more efficient than conventional energy sources.

[0004] Solid oxide cells, operating through chemical reactions in an environmentally friendly process, represent a highly promising future energy conversion device. The intermittency of renewable energy sources presents challenges to the stability of the electric grid, necessitating increased flexibility on both the demand and supply sides, as well as new energy storage and conversion technologies.

[0005] Electrochemically active solid oxide batteries can be used as fuel cells or electrolytic cells. Fuel cells generate electricity and heat from various fuels, while electrolytic cells generate electricity and heat from chemicals such as hydrogen, methane, ammonia, and carbon monoxide from water vapor, CO2, and nitrogen. Batteries that operate in both modes as fuel cells and electrolytic cells are called solid oxide electrochemical batteries (SOECs), reversible solid oxide batteries (rSOCs), or simply solid oxide batteries (SOCs).

[0006] As shown in Figure 1, a solid oxide cell (SOC) comprises a fuel side 100, an oxygen-rich side 102, and an electrolyte material 104 between them. In a solid oxide fuel cell (SOFC), oxygen 106 is supplied to the oxygen-rich side 102 and reduced to negative oxygen ions by receiving electrons from the oxygen-rich side. The negative oxygen ions are transported through the electrolyte material 104 to the fuel side 100, where they react with fuel 108 to produce water, carbon monoxide (CO), and carbon dioxide (CO2), typically. The fuel side 100 and the oxygen-rich side 102 are connected via an external electrical circuit 111, which includes a load 110 for the fuel cell operating mode, drawing electrical energy from the system. The fuel cell also generates heat in the reactant exhaust flow. In the electrolytic operating mode, the current flow is reversed, and the solid oxide cell acts as an electrically supplied load. Depending on the operating conditions of the electrolytic reaction, the cell operation can be endothermic, exothermic, or thermally neutral.

[0007] The fuel cell reactions for methane, carbon monoxide, and hydrogen fuels are shown below. Fuel side: CH4 + H2O = CO + 3H2 CO + H2O = CO2 + H2 H2 + O 2- =H2O+2e - Oxygen-rich side: O2 + 4e - =2O 2- Net reaction: CH4 + 2O2 = CO2 + 2H2O CO + 1 / 2O2 = CO2 H2 + 1 / 2O2 = H2O

[0008] In the electrolytic operation mode (solid oxide electrolytic cell, (SOEC)), the reaction is reversed; that is, electrical energy from source 110 is supplied to the cell, where water and often carbon dioxide are reduced on the fuel side to form oxygen ions. These oxygen ions then move through the electrolyte material to the oxygen-rich side, where the oxidation reaction takes place. It is possible to use the same solid oxide cell in both SOFC mode and SOEC mode.

[0009] Conventional solid oxide electrolytic cells operate at temperatures that allow high-temperature electrolytic reactions to occur, typically between 500 and 1000°C, although temperatures exceeding 1000°C may also be useful. These operating temperatures are similar to those of solid oxide fuel cells (SOFCs). The net cell reaction produces hydrogen and oxygen gases. The reaction with 1 mole of water is shown below. Fuel side: H2O + 2e - →H2+O 2- Oxygen-rich side: O 2- → 1 / 2O2 + 2e - Net reaction: H2O → H2 + 1 / 2O2

[0010] In co-electrolysis, carbonaceous species are supplied to the cell in proportions favorable for subsequent purification of the resulting gas, typically, for example, by the Fischer-Tropsch process, in addition to vapor. Carbon dioxide can be directly reduced to carbon monoxide or interact with hydrogen via a water-gas shift reaction to form carbon monoxide and vapor. Solid oxide cells can also be used to produce other types of chemicals directly or via chemical reactions by electrochemical reactions. Such chemicals may include, for example, methane and ammonia. Methane can be produced when water vapor and carbonaceous species are supplied to the solid oxide electrolytic cell, and ammonia can be produced when water vapor and nitrogen are supplied. The reaction rate of chemical production depends on the supply current, the flow rates on the fuel and air sides, the gas concentrations on the fuel and air sides, the pressures on the fuel and air sides, and the temperatures on the fuel and air sides.

[0011] In solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOEs) stacks, where the flow direction of the fuel-side gas is relative to the oxygen-rich gas within each cell and relative to the gas flow direction between adjacent cells, the stacks are combined through different cell layers of the stack. Furthermore, the fuel-side gas, the oxygen-rich gas, or both can pass through two or more cells before being discharged, and multiple gas flows can be split or merged after passing through the primary cells and before passing through the secondary cells. These combinations help increase current density and minimize the thermal gradient across the cells and stack as a whole.

[0012] High operating temperatures in SOC cells and systems present material-related challenges concerning thermomechanical forces, material properties, chemical stability, and uniformity of operating conditions. These aspects impose practical constraints on feasible SOC cell, stack, and module sizes. Therefore, scaling technology for large-scale installations typical of SOEC applications depends primarily on increasing the number of cells, stacks, and SOC modules. Consequently, minimizing the cost of each multiplicative unit at all levels is crucial for reducing overall costs.

[0013] SOFCs typically supply a voltage of approximately 0.8 V during normal operation, while the typical operating voltage of an SOE cell is approximately 1.3 V. To increase the total voltage output, SOCs are usually assembled into stacks where cells are electrically connected via flow path plates (also known as interconnector plates or bipolar plates). The desired voltage level determines the number of cells required.

[0014] A bipolar plate separates the anode and cathode sides of adjacent cell units while simultaneously enabling electron conduction between the anode and cathode. The interconnect, or bipolar plate, typically has multiple channels allowing fuel gas to pass through one side of the interconnect plate and oxidizer gas through the other. The direction of fuel gas flow is defined as the substantial direction from the fuel inlet to the fuel outlet of the cell unit. Similarly, the direction of oxidizer gas (i.e., air) flow is defined as the substantial direction from the inlet to the outlet of the cell unit.

[0015] Conventionally, cells are stacked on top of each other so as to completely overlap, resulting in a parallel flow stack, for example, with all fuel and oxidizer inlets on one side of the stack and all fuel and oxidizer outlets on the opposite side. One feature that affects the temperature of the structure during operation is the vapor reforming of the fuel supplied to the cells. Vapor reforming is an endothermic reaction and cools the fuel inlet edge of the battery. Due to the exothermic nature of the electrochemical process, the outlet gas exits at a higher temperature than the inlet gas. When endothermic and exothermic reactions are combined within an SOFC stack, a significant temperature gradient is created throughout the stack. At the same time, it is desirable to minimize the flow rates on both the fuel side and the high-concentration oxygen side to maximize the overall system efficiency. A large thermal gradient induces highly undesirable thermal stress within the stack, accompanied by differences in current density and electrical resistance. The performance and lifespan of an SOC stack can be maximized if the temperature profile can be maintained as uniformly as possible throughout the stack. Therefore, the thermal management problem for SOFC stacks lies in avoiding unacceptable stresses and reducing the thermal gradient sufficiently to maximize electrical efficiency through a uniform current density profile.

[0016] In prior art embodiments, it is often necessary to protectively coat the flow path plates to slow down metal corrosion. Generally, there are two corrosion mechanisms that cause aging in solid oxide fuel cells and electrolytic cells. One mechanism is the formation of an oxide layer on the metal surface that does not conduct electricity well, and the other is the precipitation of chromium compounds evaporating from the metal onto the active surface of the unit cell and their reaction with electrochemically active materials, weakening the electrochemical, chemical, electrical conductivity and / or gas permeability properties of the active material. Oxide structures are generally used as protective coatings that, on the one hand, slow down the diffusion of oxidizing agents onto the metal surface, and on the other hand, slow down the diffusion of alloy atoms and compounds through the oxide structure. The cost of protective coatings is typically significant in the total cost of the cell stack, and the cost of protective coatings is influenced by the manufacturing process, materials used for the protective coating, and the surface being protected. Furthermore, glass, ceramic, or mineral materials commonly used as sealants may react with the protective coating, potentially causing an aging effect on the cell stack structure, for example, due to increased gas leakage and / or undesirable increases in electrical conductivity. Therefore, extending the protective coating to the area used to seal the cell stack is undesirable.

[0017] A SOC module may comprise tens to hundreds of SOC stacks, support structures, thermal insulation, reactant transport and distribution structures, instrumentation, and electrical and reactant interfaces to applications or other modules. Since high-temperature interfaces are expensive, space-consuming, and can constitute ignition sources, it is also beneficial to include heat exchange within the module to lower the reactant interface temperature. Furthermore, SOC modules require internal or external means to facilitate safe startup and shutdown.

[0018] U.S. Patent No. 5,298,341 presents the arrangement of manifolds and stacks of ion-conducting electrolyte elements in an ion-conducting device having two or more stacks arranged at regular intervals around a central plenum having a plenum longitudinal axis.

[0019] U.S. Patent Application Publication No. 2011 / 269042 discloses a multi-stack fuel cell system that enables efficient interconnection of multiple fuel cell stacks. The stack includes internal manifold channels for supplying fuel and air to the fuel cells within the stack and for removing tail gas and spent air from the fuel cells within the stack.

[0020] In the embodiments of the prior art, the air inlet channel and the air outlet channel are separated. This is because it has been considered a conventional, well-functioning structure without realizing that a more beneficial system structure can be achieved. [Overview of the project]

[0021] An object of the present invention is to achieve a solid oxide type battery system in which energy production capacity is increased and energy production efficiency is improved, and its operation. This is achieved by a stack module of a solid oxide cell stack, each stack including a unit cell having a fuel side, an oxygen-rich side, and an electrolyte material between the fuel side and the oxygen-rich side, each stack including a flow path plate made of a material having high conductivity at high temperature, each stack having a four-angle configuration, each stack including a gas seal structure made of an electrically insulating material, the stack module including a fuel inlet manifold for delivering supply fuel gas to the stack and a fuel outlet manifold for collecting fuel exhaust gas from the stack. The stack module includes at least two stack bundles, each stack bundle including a row or matrix of stacks together with a fuel inlet manifold for supplying fuel to the stacks and a fuel outlet manifold for collecting fuel gas from the stacks, which are connected to the manifold in parallel with respect to their fuel inlets and fuel outlets, the stack module being located inside an airtight cover and including the necessary interfaces into and out of the airtight cover, the fuel gas flow characteristics in the manifold being optimized by the size of the holes connecting the fuel manifold and the stacks based on the pressure drop characteristics of the manifold and the stacks connected in parallel thereto, the stacks being electrically insulated from the manifold structure using an electrical insulation structure, the other end of the stack being electrically separated from other structures, the stack module including a side seal structure between adjacent stacks in the stack bundle and the stacks at the ends of the bundle and an airtight cover for preventing air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stack, the side seal structure being electrically insulating, the stack bundle including at least one of an integrated structure of an air inlet section and an integrated structure of an air outlet section of adjacent parallel-connected cell stack bundles.

[0022] The focus of the present invention is also a stack module method for solid oxide cell stacks, where each stack comprises a unit cell having a fuel side, an oxygen-rich side, and an electrolyte material between the fuel side and the oxygen-rich side, wherein each stack uses a flow path plate made of a material having high conductivity at high temperatures, and each stack uses a gas seal structure made of an electrically insulating material, wherein fuel gas is supplied to the stack and fuel exhaust gas is discharged from the stack. In the stack module method, at least two stack bundles are used, each stack bundle comprising a row or matrix of stacks connected in parallel to a manifold with respect to a fuel inlet and fuel outlet, the stack module is housed within an airtight cover and has the necessary interfaces to and from the airtight cover, the method optimizes the fuel gas flow characteristics within the manifold with the size of the holes connecting the manifold and the stacks based on the pressure drop characteristics of the manifold and the stacks connected in parallel thereto, the stacks are electrically insulated from the manifold structure with an electrically insulating structure, the other end of the stacks is electrically isolated from other structures, the method prevents air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stacks with side seal structures between adjacent stacks within the stack bundle and between the stacks and the airtight cover at the ends of the bundle, forming at least one of an integrated structure for the air inlet compartment and an integrated structure for the air outlet compartment of adjacent parallel connected cell stack bundles.

[0023] The present invention is based on a stack module comprising at least two stack bundles, each stack bundle including a stack of columns or a matrix of stacks together with a fuel inlet manifold for supplying fuel to the stack and a fuel outlet manifold for collecting fuel gas from the stack, and being connected in parallel to the manifold with respect to the fuel inlet and the fuel outlet. The present invention is also based on, for example, the stack module being located inside an airtight cover with the necessary interfaces into and out of the airtight cover, and the stack module having a side seal structure between adjacent stacks within the stack bundle and the stacks at the ends of the bundle, the airtight cover preventing air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stack, and the side seal structure being electrically insulating. Further, the present invention is based on the stack bundle comprising at least one of an integrated structure of air inlet compartments and an integrated structure of air outlet compartments of adjacent parallel-connected cell stack bundles.

[0024] An advantage of the present invention is that it can reduce the cost of the generated electricity and chemicals by enabling the use of a higher power density in the same reaction area.

Brief Description of the Drawings

[0025] [Figure 1] An exemplary repetitive cell structure is shown. [Figure 2] An exemplary arrangement of flow path plates for a fuel cell stack is shown. [Figure 3] An exemplary cross-sectional perspective view of a stack module having a common outlet and inlet air compartment inside an airtight cover is shown. [Figure 4] An exemplary cross-sectional side view of a stack module having a common outlet and inlet air compartment inside an airtight cover is shown. [Figure 5] An exemplary cross-sectional side view of a stack module having a common outlet and inlet air compartment integrated with balance of plant components inside an airtight cover is shown. [Modes for carrying out the invention]

[0026] In embodiments of the present invention, the volumetric power density of the solid oxide stack assembly is maximized by integrating the air inlet and air outlet sections of adjacent stack assemblies.

[0027] According to the present invention, a fuel cell or electrolytic cell stack includes at least two single repeating structures. The single repeating structure includes a fuel side, an electrolyte between them, and an oxygen-rich side, and includes at least one electrochemically active unit cell structure positioned between at least two flow path plates, the other for distributing oxygen-rich gas to the oxygen-rich side of the unit cell structure, the other for distributing fuel gas to the fuel side of the unit cell structure, and at least one sealing means for sealing the gas atmosphere in its intended enclosure. The flow path plates have at least one inlet opening for the fuel gas and / or oxygen-rich gas, and at least one outlet opening for the spent fuel gas and / or oxygen-rich gas. The flow directions of the fuel gas and oxygen-rich gas can be arranged in a parallel flow configuration where both gases flow in essentially the same direction on each side of the unit cell, or in a counterflow configuration where the flow directions are essentially opposite between the fuel gas and the oxygen-rich gas, or in a direct-to-alternating configuration where the flow directions are essentially at a 90° angle between the fuel gas and the oxygen-rich gas, or in a combination thereof.

[0028] Figure 2 shows the flow path plates 121 of a fuel cell stack. A complete fuel cell stack comprises several plates 121 arranged in a continuous manner with respect to each other as shown. The plates in this embodiment are rectangular and symmetrical. A unit cell structure 174, which includes an electrolyte layer 104 between the anode electrode and the cathode electrode, is located between the plates 121, generally in the center of the plates. The electrolyte element structure 174 may be any suitable electrolyte element structure and is therefore not described in further detail herein. The flow path plates 121 and the unit cell structures 174 are sealed with a gas seal structure 128, which is preferably made of a compressible material, such as ceramic, mineral, or glass material. The gas seal structure 128 according to the present invention is compressed when the cells are assembled to form a stack. Two opposing flow path plates 121 and the unit cell structure 174 and gas seal structure 128 between them form a single repeating structure.

[0029] The fuel cell stack module in Figure 2 includes flow-limiting orifices 135 and 136 opening in the flow distribution and flow outlet regions. A gas seal structure 128 is compressed over the flow-limiting orifices 135 and 136. The flow-limiting orifices 135 and 136 ensure a uniform fuel flow distribution across the active region of the fuel cell electrodes by forming an additional pressure sink in the flow path. The gas seal structure 128 also creates similar pressure loss conditions between the iterative structures of the fuel cell, ensuring uniform flow distribution characteristics for each iterative structure of the fuel cell. A uniform flow distribution within the fuel cell stack also ensures uniform thermal distribution conditions within the fuel cell stack, i.e., similar thermal gradients between cells within the stack. This improves the duty cycle of the fuel cell stack and extends the lifespan of the fuel cell stack.

[0030] The purpose of the gas seal structure 128 is further to ensure that the oxidizer and fuel are not directly mixed within the electrochemically active region without fuel cell reaction, that the fuel and oxidizer do not leak from the electrochemical cell, that adjacent electrochemical cells do not come into electronic contact with each other, and that the oxidizer and fuel are supplied to the desired flow path plate 121. The flow path plate 121 is a flat, thin plate made from a metal alloy, ceramic material, cermet material, or other material capable of withstanding the chemical, thermal, and mechanical stresses present in the fuel cell. The oxygen-rich gas may be any gas or gas mixture containing a measurable amount of oxygen.

[0031] A preferred manufacturing method for forming the contoured surface of the flow path plate 121 is one that uses plastic deformation such as stamping, molding, or pressing, in which the shape of the material changes but no material is added or removed, or in which the material is added by welding, sintering, and laser sintering, or removed by etching and machining. If the flow field material is brittle, other manufacturing methods such as extrusion, casting, printing, and molding can be used. Gas orifices can usually be made using the same manufacturing process.

[0032] Each flow path plate 121 can be fabricated similarly in the stack assembly structure, and therefore, only a desired amount of one type of plate is required to produce a fuel cell stack having a desired amount of repeating unit cell structures 174. This simplifies the structure of the fuel cell and facilitates its manufacture.

[0033] Solid oxide electrolytic stacks differ from solid oxide fuel cell stacks only in that electricity is used to produce fuel through a reaction that is the reverse of the fuel cell reaction described in the prior art.

[0034] The single largest energy-consuming device in a fuel cell system is the blower or compressor used to supply air to the cathode compartment of the fuel cell stack. The power consumption of the air supply device is proportional to the pressure level to which the air must be compressed. Also, in a solid oxide electrolysis system, air is typically supplied to the anode to control the heat balance of the electrolysis stack and maintain a defined oxygen partial pressure on the anode compartment. One of the main sources of pressure loss in fuel cell and electrolyzer systems is the stack itself. It is advantageous to design the device such that the air side of the device has a passage open to the ambient atmosphere.

[0035] Figures 3 - 5 show exemplary cell stack modules according to the present invention in a fuel cell system or an electrolyzer cell system. In a stack module of a solid oxide cell stack according to the present invention, stack 103 includes unit cells 174 having a fuel side 100, an oxygen-rich side 102, and an electrolyte material 104 between the fuel side and the oxygen-rich side. Stack 103 further includes flow path plates 121 made of a material having high conductivity at high temperatures and a gas seal structure 128 made of an electrically insulating material. Preferably, the high electrical conductivity means an area specific resistance value of less than 0.1 ohm cm 2 and preferably less than 0.01 ohm cm. 2 Each stack 103 preferably includes a four-angle configuration. Stack 103 can be arranged in a matrix configuration or a column configuration together with one or more fuel gas manifolds that supply fuel to the individual stacks and collect the exhaust fuel gas from the stacks. Stack 103 is connected to fuel inlet manifold 150 and fuel outlet manifold 152 in parallel with respect to the fuel inlet and fuel outlet.

[0036] The stack module according to the present invention comprises a fuel inlet manifold 150 for supplying a supply fuel gas 108 to the stack and a fuel outlet manifold 152 for collecting fuel exhaust gas 177 from the stack. The manifolds 150 and 152 are preferably made of ferritic steel. In a preferred embodiment, the manifolds 150 and 152 and the cover portion of the stack 103 are made of at least one material with similarly close coefficients of thermal expansion. The stack module preferably comprises electrical connections between the stacks 103 configured to achieve a voltage level of 600 V to 1200 V, i.e., a target voltage level for the system or application. In this configuration, the cell stacks 103 are assembled within the manifolds 150 and 152 in parallel connection from the viewpoint of the combustion gas inlet and outlet. The cell stack module comprises an integrated structure of air inlet compartments 106 and / or air outlet compartments 176 of adjacent parallel-connected cell stack 103 assemblies. An integrated structure means, for example, a gas volume shared between adjacent stack bundles.

[0037] The inlet manifold 150 according to the present invention is provided with controllably sized gas outlets 133 relative to the stack 103 to form a uniform gas flow into the stack. The outlet manifold 152 is provided with controllably sized gas outlets 137 from the stack 103 to form a uniform gas flow from the stack. In a preferred embodiment, the stack module includes means for controlling the size of the individual gas outlets 133, 137 based on the pressure drop characteristics of the manifold, and stacks 103 connected in parallel to the manifolds 150, 152 to form a uniform gas flow between the stacks 103. In one embodiment, the manifolds 150, 152 may be provided with controllably sized gas outlets 133, 137 in the stack 103 to form a uniform gas flow into and from the stack based on the pressure difference between the inlet pipe connection 160 and the outlet pipe connection 162 of the manifolds 150, 152. Pressure loss may require different hole sizes between the holes 133, 137.

[0038] The stack module according to the present invention is housed inside an airtight cover 169 and includes the necessary interfaces to and from the airtight cover 169. In one preferred embodiment shown in Figure 5, the airtight cover 169 can enclose the entire stack module, including the stack assembly, the balance of plant components 212, and instrumentation that ensures air leakage to the environment is minimized. The airtight cover 169 includes the necessary interfaces for air inlet and outlet flows, fuel inlet and outlet flows, current leads for individual stacks or stack rows, measurement connections, and compression system connections. The airtight cover 169 may be fabricated from or enclosed in an insulating material. An exemplary perspective section 3 shows a fuel manifold opening for fuel exhaust gases 177 from the stack 103 to the fuel outlet manifold 152. Figure 3 also shows a fuel inlet interface 208, a fuel outlet interface 204, an air inlet interface 206, and an air outlet interface 210. In a preferred embodiment, at least two cell stacks 103 can be arranged in electrical series connection. The advantage of an electrical series connection is that it minimizes the need for interfaces to and from airtight covers.

[0039] In a preferred embodiment, the stack module may comprise a first gas seal 155, a first electrical insulation plate 119, and a second gas seal 156 between the manifolds 150, 152 and the stack 103. On the upper 122 and bottom 124 of the cell stack 103, the stack module may comprise a second electrical insulation plate 114, a compression structure 116 for the stack 103, and an air-side sealing structure 166 between the stacks, and each stack end plate 170 may be connected to an electrical connection 173. The stack module may comprise a compensation structure on at least one of the upper 122 and bottom 124 of the cell stack 103 to compensate for height tolerances between the stacks 103. In one preferred embodiment, the stack module may comprise a stack 103 electrically isolated from the manifold 150, 152 structure using an electrical insulation structure 172 made of an airtight material. The other end of the stack 103 is electrically isolated from other structures. In one preferred embodiment, the stack 103 may have openings in the end plate 202 facing the electrical insulation structure 172 for supplying gas to the fuel inlet manifolds 150, 152 of the stack 103.

[0040] The stack 103 according to the present invention can be sealed to a ceramic isolation plate using a gasket made of glass, ceramic, or mineral material, and the isolation plate can be sealed to fuel manifolds 150, 152 using similar materials. The other end of the stack 103 can be electrically isolated from other structures using another ceramic plate. This plate does not need to be airtight. A compression structure is connected to the ceramic plate, and the compressive force is applied to at least the upper part of the stack 103, including all ceramic and gas seal portions.

[0041] According to the present invention, side seal structures 166 can be applied between adjacent stacks 103a within a stack bundle, and between stacks 103b at the ends of the bundle and the airtight cover 169. The side seal structures 166 prevent air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stacks. The side seal structures 166 are electrically insulating structures and preferably conform to the shape of the stack sides. The side seal structures can be made of a ceramic material having compressible properties with respect to its outer surface. Stacks 103 can be electrically connected to their negative end plates using negative current lead structures and to their positive end plates using positive current lead structures. Multiple stacks 103 connected in series can be connected to increase the output voltage and to minimize the number of current-through structures by connecting the positive current leads of one stack to the negative current lead structures of another stack. The number of stacks connected in series is not limited, but not all stacks in one stack assembly need to be connected in the same series connection.

[0042] Figure 5 shows an exemplary preferred embodiment according to the present invention, in which the stack module comprises a balance of plant components 212 integrated within a single structure. The air inlet 106 and air outlet 176 compartments forming the integrated structure can host the balance of plant components 212 to facilitate, for example, system safety, thermal management, and increased volumetric energy density. These balance of plant components 212 may include, for example, reforming or decomposition reactors, heat exchangers, (catalytic) burners, and gas recycling equipment including ejectors, pump heads, and compressor heads. The air compartments 106, 176 can also host current lead structures, such as instrumentation wiring for voltage and temperature measurement, and instrumentation piping for pressure and gas composition measurement.

[0043] One exemplary stack module according to the present invention comprises a stack 103 arranged in a 2 × N matrix, where N is any natural number. This configuration includes a fuel inlet manifold 150 for supplying a supply fuel gas 108 to the stack and a fuel outlet manifold 152 for collecting fuel exhaust gas 177 from the stack. The stacks are arranged in parallel within the manifolds in terms of fuel gas supply and fuel exhaust gas connection.

[0044] In a further exemplary embodiment, the stack module may comprise a pair of at least two cell stacks 103 electrically arranged in series. In a further embodiment, the module array may comprise X cell stacks 103 arranged in series, where X is a natural number and satisfies 2N / X=Y, where N and Y are natural numbers.

[0045] In embodiments of the present invention, the stack module may have a compression structure 116 inside the airtight structure 169. In other embodiments of the present invention, the module arrangement may have a compression structure 116 outside the airtight structure 169. The stack module may preferably have such gas flow structures in the manifolds 150, 152 to form pressure conditions in which the pressure loss in the inlet manifold 150 and outlet manifold 152 is less than the pressure loss in a single cell 174. Exemplary manifolds 150, 152 may include connections to the inlet and outlet pipes, as well as gas outlets to and from the stack. In preferred embodiments, the fuel inlet manifold 150 and fuel outlet manifold 152 may be joined together by welding to increase structural rigidity and strength.

[0046] In one embodiment (for example, Figure 2), the height of the flow orifice can be determined by the distance from at least one of the bottoms of the flow distribution region and the flow outlet region to the bottom of the gasket structure in order to stabilize the flow distribution in the repeating structure of the stack having tolerance variations in the thickness of the electrolyte element structure. Similar pressure loss conditions between cells are achieved by utilizing a gasket structure that is compressed and can be pre-compressed at least from the flow portion in order to achieve a uniform heat distribution, i.e., a similar heat gradient between cells in the stack. This improves the duty cycle of the solid oxide fuel cell stack and extends the life of the stack.

[0047] The cell stack module according to the present invention may include flow-limiting orifices opening into flow distribution and flow outlet regions. In one embodiment, means can be used to guide the fuel supply flow from the side of the fuel cell to the flow distribution region. The gasket structure is compressed over the flow-limiting orifice. The flow-limiting orifice ensures a uniform fuel flow distribution across the active region of the fuel cell electrodes by forming an additional pressure sink in the flow path. The gasket structure also creates similar pressure loss conditions between the iterative structures of the fuel cell, ensuring uniform flow distribution characteristics for each iterative structure of the fuel cell. The uniform flow distribution within the fuel cell stack also ensures uniform thermal distribution conditions within the fuel cell stack, i.e., similar thermal gradients between cells within the stack. This improves the duty cycle of the fuel cell stack and extends the lifespan of the fuel cell stack.

Claims

1. A stack module for a solid oxide cell stack, wherein each stack comprises a unit cell having a fuel side, an oxygen-rich side, and an electrolyte material between the fuel side and the oxygen-rich side, each stack comprises a flow path plate made of a material having high conductivity at high temperatures, each stack comprises a configuration with four angles, each stack comprises a gas seal structure made of an electrically insulating material, the stack module comprises a fuel inlet manifold for delivering supply fuel gas to the stack and a fuel outlet manifold for collecting fuel exhaust gas from the stack. The stack module includes at least two stack bundles, each stack bundle including a row or matrix of stacks, together with the fuel inlet manifold for supplying fuel to the stack and the fuel outlet manifold for collecting fuel gas from the stack, they are connected to the manifold in parallel with respect to their fuel inlets and fuel outlets, the stack module is located inside an airtight cover and includes the necessary interfaces to and from the airtight cover, the fuel gas flow characteristics in the manifold are based on the size of the holes connecting the fuel manifold and the stack, and the pressure drop characteristics of the manifold and the stack connected in parallel thereto, the stack is an electrically insulating structure made of airtight material A stack module for a solid oxide cell stack, characterized in that it is electrically isolated from a manifold structure, the stack includes an opening in an end plate facing the electrically insulating structure for supplying gas to the manifold of the stack, the other end of the stack is electrically isolated from other structures, the stack module includes side seal structures between adjacent stacks in a stack bundle and between the stacks at the ends of the bundle and the airtight cover to prevent air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stack, the side seal structures are electrically insulating, and the stack bundle includes at least one of an integrated structure for the air inlet compartment and an integrated structure for the air outlet compartment of adjacent parallel-connected cell stack bundles.

2. A stack module for a solid oxide cell stack according to claim 1, characterized in that at least one manifold and the cover portion of the stack are made of at least one material having similar coefficients of thermal expansion.

3. The stack module for a solid oxide cell stack according to claim 1, characterized in that the stack module comprises balance of plant components integrated within at least one integrated structure.

4. The stack module for a solid oxide cell stack according to claim 1, wherein the stack module comprises a first gas seal, a first electrical insulating plate, and a second gas seal between the manifold and the stack, and above and below the cell stack, the stack module comprises a second electrical insulating plate, a compression structure for the stack, and an air-side sealing structure located between the stacks, and each stack end plate is connected to an electrical connection.

5. The stack module for a solid oxide cell stack according to claim 1, characterized in that the stack module is provided with a compensation structure on at least one of the upper and lower sides of the cell stack for compensating for height tolerances between the stacks.

6. The stack module for a solid oxide cell stack according to claim 1, characterized in that the stack module provides electrical connections between the stacks for voltage levels of 600 V to 1200 V.

7. A stack module method for a solid oxide cell stack, wherein each stack includes a unit cell having a fuel side, an oxygen-rich side, and an electrolyte material between the fuel side and the oxygen-rich side, and in the method, each stack uses a flow path plate made of a material having high conductivity at high temperatures, and each stack uses a gas seal structure made of an electrically insulating material, and in the method, fuel gas is supplied to the stack and fuel exhaust gas is discharged from the stack. In the stack module method, at least two stack bundles are used, each stack bundle comprising a row or matrix of stacks connected to a fuel inlet and outlet manifold in parallel with respect to the fuel inlet and fuel outlet, the stack module is located within an airtight cover and has the necessary interfaces to and from the airtight cover, the fuel gas flow characteristics within the manifold are based on the size of the holes connecting the fuel manifold and the stack, the pressure drop characteristics of the manifold and the stack connected in parallel thereto, and the stack is electrically isolated from the manifold structure by an electrically insulating structure made of an airtight material. A stack module method for solid oxide cell stacks, characterized in that, in the method, gas is supplied to the manifold of the stack through an opening in an end plate facing an electrically insulating structure, the other end of the stack is electrically isolated from other structures, and in the method, side seal structures between adjacent stacks in a stack bundle and between the stack and the airtight cover at the end of the bundle prevent air from flowing directly from the inlet chamber to the outlet chamber without flowing through the stack, and at least one of an integrated structure for the air inlet section and an integrated structure for the air outlet section of adjacent parallel-connected cell stack bundles is formed.

8. The stack module method for a solid oxide cell stack according to claim 7, characterized in that at least one manifold and the cover portion of the stack are made of at least one material having similar coefficients of thermal expansion.

9. A stack module method for a solid oxide cell stack according to claim 7, characterized in that the balance of plant components are integrated inside at least one integrated structure.

10. A stack module method for a solid oxide cell stack according to claim 7, characterized in that, in the method described above, a first gas seal, a first electrical insulating plate, and a second gas seal are arranged between the manifold and the stack; a second electrical insulating plate and a compression structure for the stack are arranged above and below the cell stack; an air-side sealing structure is arranged between the stacks; and each stack end plate is connected to an electrical connection.

11. The method for stacking solid oxide cell stacks according to claim 7, characterized in that, in the method described above, a compensation structure is arranged on at least one of the upper and lower sides of the cell stack to compensate for the height tolerance between the stacks.

12. The method for stacking solid oxide cell stacks according to claim 7, characterized in that the connection between the stacks is configured to achieve a voltage level of 600 V to 1200 V.

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