High-temperature fuel cell stack for generating electrical energy

Abstract

The high-temperature fuel cell stack for generating electrical energy, comprising modules supplied with a gas stream as fuel and oxidant, which is supplied to the individual modules of two fuel cells, is characterized in that it consists of a set (2) comprising several or more identical modules (3) from two fuel cells, which are stacked in the form of a cuboid and are separably connected to one another, a heat-resistant metal base (1) on which a module set (2) rests, and a heat-resistant metal cover (5) for covering the set, which is equipped with the bushing (31) for supplying the gas fuel to the inner collecting angled channel (32) and with bushings (33) for supplying the air to the inner collecting angled channel (34), whereas the heat-resistant metal base (1) is equipped with the bushing (43),which forms the extension of the inner collecting channel (41) for the discharge of exhaust gases and bushing nozzle (40), which forms the extension of the inner collecting channel (38) for the discharge of nitrogen, wherein each of the modules (3) of two fuel cells is composed of the ceramic frame (4), which has a two-stage frame receptacle (15) around the centrally located square through-hole (14), in the lower part of which a perforated heat-resistant metal cathode plate (20) with a U-profile and angular offset (21) of the upper end is arranged, within which a double-grooved ceramic molded part (22) is located, whereas on the flat part (23) of the cathode plate (20) two single-grooved fuel cells (24) are arranged, which are oriented with their grooves (25) towards each other and separated from each other by a perforated heat-resistant metal anode plate (26) with a U-shaped bent end (27) which is at the angular offset (21) is adjacent to the cathode plate (20), be separated.

Description

[0001] The invention relates to the high-temperature solid oxide fuel cell stack based on anodes of type AS SOFC (Anode Supported Solid Oxide Fuel Cells) and on cathodes of type CS SOFC SOFC (Cathodes Supported Solid Oxide Fuel Cells) for generating electrical energy from supplied gas fuels such as: hydrogen, synthesis gas, methane, biogas, ethanol and bioethanol, methanol, gasoline and similar hydrocarbons.

[0002] Fuel cells are devices for converting chemical energy into electrical energy through an electrochemical reaction between the fuel supplied to the anode and the oxidation gas supplied to the cathode. The oxidation gas passes through the electrolyte membrane, which conducts oxygen ions, towards the anode, where it combines with the fuel to generate electrical energy and heat. The unique feature of the fuel cell lies in its conversion of chemical energy into electrical energy without a combustion process. This ensures higher efficiency (45-55%) compared to most conventional thermo-mechanical solutions (e.g., gas turbines 40-42%). In combined heat and power (CHP) systems, fuel cells can achieve thermal efficiency of up to 90%. One of the consequences of using fuel cells for energy generation is significantly lower emissions of carbon dioxide (SO2) and nitrogen oxides (NO).X Fuel cells release fewer hydrocarbons, carbon oxides, and solids into the atmosphere (especially when used as hydrocarbon fuel) than traditional power plants using conventional fuels. Their compact size and modular design allow for easier and more economical installation. They can operate continuously and independently, selecting the fuel and oxidizer in quantities appropriate to the electrical load. Furthermore, they are resistant to momentary overloads and can operate under low loads. Easy installation and the absence of moving parts (no wear and tear, no vibrations, minimal structural issues) result in high operational reliability.

[0003] In known fuel cells, hydrogen is most commonly used as fuel, although work is also carried out in conjunction with the use of methane, CO, and other hydrocarbons. Oxygen, supplied to the system in pure form or from ambient air, serves as the oxidizing agent. The individual fuel cell, either square or round, consists of two electrodes: an anode made of Y₂O₃-stabilized zirconium dioxide and nickel dioxide composite, and a cathode made of ceramic with a perovskite structure containing lantanate, strontium, cobalt, manganese, and iron dioxides. These are separated from each other by a solid electrolyte of zirconium dioxide stabilized with Y₂O₃ at a concentration of 3–10% mol or with Sc₂O₃, which is a very good conductor of the anionic oxides at high temperatures (650–900°C).

[0004] Another known fuel cell battery, also called a stack, consists of stacked heat-resistant metal frames. Individual cells are located in the center of these frames and are separated by connecting plates that carry the electrical charges. These connecting plates are equipped with horizontal grooves for supplying gaseous reagents to the electrode surfaces. The metal frames and connecting plates are separated by layers of electrical insulation and equipped with horizontal channels for supplying reagents and removing combustion products to individual cells. Solutions are also known in which thin, corrugated metal plates are used instead of the grooved connecting plates. These plates are positioned directly in the center of the metal frames and perform the same function.The extraction of electrical energy from the cell stack is achieved through the screws that press the cell stack and remain in contact with the metal plates.

[0005] The solution described in the literature (Faes et al., Fabrication of structured anode-supported solid oxide fuel cell by powder injection molding, Journal of Power Sources, Vol. 227, 2013, pp. 35-40, ISSN 0378-7753) is known in which the surface of the anode of the round fuel cell has protrusions that allow fuel to be supplied to the anode surface, and the electrical charges are collected by the mesh, which is connected to power cables. On the cathode side, solid slotted metal plates with the attached metal mesh and the power connection are used.

[0006] The fuel cell is known as a stack of cells with individual cells arranged in the center. These cells are supplied with a gas stream as fuel and oxidizer. The fuel stream is routed parallel to each cell, so that each cell receives the same portion of fuel, calculated as the total delivered stream divided by the number of cells. Similarly, the oxidizer stream is routed parallel to each cell, ensuring that each receives the same portion of oxidizer. At the output of each cell, there are the same fuel and oxidizer streams, and each cell acts as a power generator with the same voltage and output current. Nevertheless, this type of cell is characterized by low fuel consumption and, consequently, low overall efficiency.

[0007] Known from Polish patent no. PL211985B1, a fuel cell for converting the electrical energy of the fuel directly into electrical energy, without the need for flame combustion of the fuel, which forms a cell complex with individual cells forming the stack and the inlets of these cells being connected to the fuel lines and oxidizer lines, characterized in that the oxidizer line is connected in parallel to many individual cells, so that each of them is supplied with n times the flow of the oxidizer, and the fuel line is routed in series to the individual cells, each of these cells being supplied with the entire fuel flow with a gradually decreasing proportion of fuel and an increasing proportion of exhaust gases.The cells of the stack are sources of electrical energy that exhibit different voltages at the same current value. The sum of the generated voltages, resulting at the output of the fuel cell, is higher than at the output of the previously described solution. This allows for better fuel consumption and higher efficiency, but at a higher investment cost.

[0008] Furthermore, the fuel cell complex known from Polish patent application PL 363200 A1 (corresponding to US 2004086758 A1) is equipped with a manifold containing a corresponding number of connection zones for the fuel cells, some of which have different characteristic properties, including the size and arrangement of the electrical connections and the inlet and outlet openings corresponding to different current capacities. This cell complex also has one or more stacks of fuel cells, and some of these stacks have different current capacities corresponding to the different characteristic properties of the manifold zone and the correspondingly different arrangement of the electrical connections and inlet and outlet openings.The characteristic features of some of these stacks are designed such that only the stack of fuel cells with the specific power output can be connected to the corresponding section of the manifold. For connecting to the manifold section of this fuel cell complex where the absence of a fuel cell stack is desired, a locking plate is used. The design of these lines is such that it allows for a seal at the connection point when neither the locking plate nor the fuel cell stack connects to the specific manifold section, and furthermore, the design of these lines eliminates the need for the locking plate.

[0009] WO 2004 / 091023 A2 discloses an improvement in fuel cell systems through the introduction of features that make the fuel cell more efficient while simultaneously reducing the size of a fuel cell stack. Improvements to the connecting plates and the introduction of gas-permeable membranes make the fluid flow more suitable for its intended purpose. Sensors integrated into the fuel cell provide valuable data.

[0010] JP H09-45356 A relates to the simplification of a structure and improvement of reliability through the mutual arrangement of plate-shaped unit cells in which the same electrodes are opposite each other and connected at constant intervals within a cell holder. Several unit cells are held in a cell holder by keeping its perimeter airtight, with the air electrodes and fuel electrodes facing each other.An (air) distributor, which is connected to an air duct between the air electrodes, and a fuel gas distributor, which is connected to a fuel gas duct between the fuel electrodes, are insulated in an outer circumferential part of the cell holder in a mutually airtight state, and conductive elements to connect them electrically are also arranged between the opposing air electrodes and between the fuel electrodes, and current collectors, which electrically connect the conductive elements, are arranged inside the respective distributors.

[0011] WO 2013 / 093607 A2 discloses a modified planar cell comprising a solid oxide electrolyte, a gas-diffuse anode, a cathode, a metallic or oxide current path, and a current-gas supply. The supporting solid electrolyte of the cell is in the form of a corrugated plate composed of waves. In cross-section, the waves of the plate form an isosceles trapezoid of equal height, without a larger lower base containing holes. The holes are located on one side in the upper part of each wave and serve to supply one of the reagents, for example, fuel in the case of a fuel cell. The waves are connected at their base to form gas chamber channels of the cell. The gas chamber channels are in the form of inverted isosceles trapezoids without a larger upper base, and the angle α at their smaller base ranges from 0.1 to 89.9°. The corrugated plate is connected to two opposing walls, a front wall and a back wall.The latter is arranged perpendicular to the waves of the plate and is therefore at the same height and provided with holes.

[0012] The holes in one wall serve to introduce a second reagent, for example, air in the case of a fuel cell, into each channel of the electrode environment, which is shaped like an inverted isosceles trapezoid without the larger upper base. The holes in the opposite wall serve to drain the hypoxic mixture. On one side of the gas space channels, which in cross-section form an isosceles trapezoid without a larger lower base, the corrugated plate of the supporting solid electrode is coated with an electrode, for example, a nickel-cermet anode in the case of a fuel cell. On the side of the gas space channels of the electrode environment, which are shaped like inverted isosceles trapezoids without a larger upper base, the plate is coated with a second counter electrode, for example, a cathode based on strontium lanthanum manganite.The metallic, box-shaped gas supply channel, with its series of holes, ensures the supply of reagents and the removal of reaction products. The width and length of the gas supply channel correspond to those of the cell.

[0013] These holes correspond to the holes in the upper parts of the cell's corrugations, which form an isosceles trapezoid in cross-section without a significant lower base and are gas-tightly connected to the periphery of the holes. Within the planar cell, a gas-tight space is formed for the reagent introduced via a tube, for its uniform distribution through the gas space channels, and for the exhaust gases exiting through a similar exhaust gas distributor. The exhaust gas distributor is rotated 180° to the vertical axis and gas-tightly connected to the ceramic part at its edge. The perforated flat surfaces of the gas distributors are connected to the electrodes. They simultaneously serve as current collectors, and the tubes as the electrical connections for the planar cell.

[0014] WO 1998 / 035398 A1 relates to a portable fuel cell arrangement for converting liquid or gaseous hydrocarbons into direct current electricity, consisting of disc-shaped fuel cells stacked axially and secured by a tie rod, wherein the fuel cell has an opening for supplying a first gas and for receiving the tie rod.The fuel cell arrangement is characterized in that the fuel cell comprises: an ion-conducting electrolyte in the form of a high-temperature ceramic electrolyte or a low-temperature polymer electrolyte; a porous cathode layer as an oxygen electrode and a porous anode layer as a fuel electrode, one on each side of the electrolyte; a gas-permeable support with a first and a second surface and channels for the passage of gases; a small separator plate that rests at least partially on the first surface of the support; and a large electrically conductive separator plate that rests on the second surface of the support and comprises means that selectively guide the gases and interact with the channels in the support.

[0015] WO 1992 / 016029 A1 discloses a device with several high-temperature fuel cells connected in parallel for converting the chemical energy of a fuel into electrical energy, in which an absolutely uniform current transfer from one fuel cell to the adjacent fuel cell must be ensured, while simultaneously preventing cross-currents in the electrodes. The supply and removal of the gaseous media to the electrodes is carried out in such a way that the achieved operating temperature is maintained as uniformly as possible over the entire electrode surface.For this purpose, the oxygen electrode consists of SrO-doped Mn oxides with a Cr surface coating and the fuel electrode of Ni / ZrO2 cermet with a Ni surface coating; the separating plate is a hollow body that conducts, distributes and collects gaseous media; and between the separating plate and the current collectors is a highly elastic component in the form of a gas-permeable intermediate layer that acts as a high-temperature spring.

[0016] The object of the invention is to develop a simple and compact design for a high-temperature solid oxide fuel cell stack, including SOFCs, for generating electrical energy from supplied gaseous fuels such as hydrogen, synthesis gas, and hydrocarbons, especially methane, biogas, ethanol, bioethanol, and methanol. This design allows for the integration of one or more stacks within a thermally insulated segmented metal housing. This housing is positioned between the stacks, equipped with heating coils, and powered by an external energy source during startup. The invention also aims to develop a stack design that reduces the number of components, allows for the production of inexpensive materials, particularly ceramics, using cost-effective methods, and thus lowers manufacturing costs while maintaining high performance.

[0017] The essence of the high-temperature fuel cell stack according to the invention for generating electrical energy lies in the fact that it comprises a set consisting of several or more identical modules of two fuel cells, stacked in the form of a cuboid and separably connected to one another, a heat-resistant metal base on which a set of modules rests, and a heat-resistant metal base for covering the set, which is equipped with a bushing for supplying the gaseous fuel to the inner collecting channel and with bushings for supplying air to the inner collecting channel. Furthermore, the heat-resistant metal base is equipped with a bushing that forms the extension of the inner collecting channel for exhaust gases and a bushing that forms the extension of the inner collecting channel for nitrogen discharge. Each of the modules of two fuel cells consists of the ceramic frame,The assembly features a two-stage frame around the centrally located square through-hole. In the lower part of this frame, a perforated, heat-resistant metal cathode plate with a U-profile and an angled offset at the upper end is arranged. This cathode plate contains a ceramic element with grooves on both sides. On the flat part of the cathode plate, two fuel cells with grooves on one side are arranged, their grooves facing each other. These fuel cells are separated by a perforated, heat-resistant metal anode plate with a U-shaped end that rests against the angled offset of the cathode plate. Each fuel cell with grooves on one side also consists of an anode layer, 0.8–2.0 mm thick, made of a composite of NiO and ZrO2 stabilized with Y2O3.The electrolyte consists of a 5-15 µm thick layer of solid ZrO₂ stabilized with Y₂O₃ or Sc₂O₃, located on the side of the grooves and on the flat surface, and an adjacent cathode layer 100-250 µm thick, composed of a perovskite-structured material consisting of a mixture of the oxides La, Sr, Co, and Fe (LSCF) as well as the oxides La, Sr, and Mn (LSM). It is advantageous toIf the ceramic frame of each module of the fuel cell pair has two through-profile openings coaxially situated against each other on the upper surfaces of the shorter sides, namely, on one side having an opening for the supply of the gaseous fuel and an opening for the supply of air, and on the other shorter side having an opening for the discharge of nitrogen and an opening for the discharge of exhaust gases, and furthermore, a side wall of the opening for the supply of the gaseous fuel is connected to the upper side wall of the two-stage frame mount by means of the pin holes for the supply of this fuel, and a side wall of the opening for the supply of air is connected to the lower side wall of this mount by means of the pin holes for the supply of air,In contrast, the side wall of the nitrogen inlet opening is connected to the lower side wall of the two-stage frame mount by means of the nitrogen outlet pin holes, and the side wall of the exhaust gas outlet opening is connected to the upper side wall of this mount by means of the exhaust gas outlet pin holes. The lower part of the perforated, heat-resistant U-profile cathode plate advantageously contacts the heat-resistant metal base, which in turn contacts two screws insulated within the heat-resistant housing of the assembly, thus pressing this assembly in place. The upper perforated metal anode plate contacts the heat-resistant metal housing, which in turn contacts two other screws insulated within the base, thus pressing this assembly in place. It is also advantageous thatwhen the contact surfaces of the fuel cells are sealed with the wall surfaces of the two-stage frame mounts, as well as the contact surfaces of the stacked ceramic frames with the ceramic paper saturated with finely ground glass-ceramic material.

[0018] According to the invention, the use of fuel cells in a stack with single-sided grooved anodes or cathodes made it possible to dispense with the costly additional grooved connecting metal plates, corrugated plates, or ceramic spacers for distributing the gaseous fuel across the anode surface of these cells. In contrast, the use of two-stage ceramic frames in the module of this stack allowed for the arrangement of two fuel cells and double-sided grooved ceramic components for distributing air to two adjacent cathode surfaces within the frames, and the use of perforated metal plates for collecting electrical charges within the frames, thus making the construction more compact and considerably simpler.

[0019] By using a stack of universal ceramic frames in the fuel cells, it is possible to manufacture them from inexpensive ceramic raw materials and using the well-known, inexpensive thermoplastic injection molding technique, as well as to dispense with the use of additional electrical insulation between the cells and the frames, and thus to significantly reduce the manufacturing costs of the stack.Further advantages of the stack according to the invention are based on the fact that the use of circumferential tongue-and-groove connections in both the ceramic frames and in the metal base and in the metal hood significantly increases the stability and tightness of the stack and considerably simplifies the assembly of these modules in stacks; on the other hand, the sealing of the contact surfaces of the fuel cells with ceramic frames and between the frames with the aid of the ceramic paper saturated with finely ground glass-ceramic material prevents these seals from seizing up, so that the disassembly of these frames is possible without their mechanical damage.

[0020] The subject matter of the invention is presented in an exemplary embodiment, where Fig. Figure 1 shows the stack of six modules of high-temperature fuel cells for generating electrical energy in a perspective view, Fig. 2 - the same stack of cells in a top view, Fig. 3 - the same stack of cells in vertical section along line AA, Fig. 4 - the same stack of cells in vertical section along line BB, Fig. 5 - the same stack of cells in vertical section along line CC, Fig. 6 - the same cell stack in vertical section along line DD, Fig. 7 - the same cell stack in vertical section along line EE, Fig. 8 - the ceramic support frame of this cell stack in perspective view, Fig. 9 - the same ceramic frame in a top view, Fig. 10 - the same ceramic frame in vertical section along line FF in the Fig. 9, Fig. 11 - the same stack of cells in vertical section along line GG, Fig. 12 - the same stack of cells in vertical section along line HH, Fig. 13 - the same stack of cells in vertical section along line JJ, Fig. 14 - the same stack of cells in vertical section along line KK, Fig. 15 - the same stack of cells in vertical section along line LL, Fig. 16 - a double-grooved ceramic molded part for distributing air over the surface of the fuel cell from the cathode side, in a perspective view, Fig. 17 - the same ceramic molded part in vertical section along line MM, Fig. 18 - Single membrane of the fuel cell in a perspective view, Fig. 19 - the same membrane in vertical section along the line NN, Fig. 20 - Detail “Z” of an enlarged end of this membrane, which is in Fig. 19 is shown, Fig. 21 - Perforated metal plate for collecting the electrical charges from the anode surfaces of the fuel cells in a top view, Fig. 22 - the same perforated plate in vertical section along line OO, Fig. 23 - Perforated metal plate for collecting the electrical charges from the cathode surfaces of the fuel cells in a top view, Fig. 24 - the same perforated plate in vertical section along line PP, Fig. 25 - Complete module of two fuel cells with the ceramic molded parts for air distribution, arranged in a ceramic frame, in a top view, Fig. 26 - the same complete module in vertical section along line RR, Fig. 27 - the same complete module in vertical section along line SS, Fig. 28 - the same complete module in vertical section along line TT, and Fig. Figure 29 shows the second variant of the multiple high-temperature fuel cells connected together in a stack in a vertical section, omitting the middle part of the stack marked with wavy lines.

[0021] The high-temperature fuel cell stack for generating electrical energy from gaseous fuel and air in an exemplary embodiment shown in the drawing Fig. The assembly shown in Figure 1 consists of the heat-resistant metal base 1, the complex 2 resting on it consisting of six identical complete modules 3 of two fuel cells arranged in separate ceramic stacked frames 4, and the heat-resistant metal hood 5 covering this complex, with all modules having a flattened cuboid shape with rectangular bases and being connected by means of the grooves 6 and tongues 7 provided on the opposing circumferential surfaces.Each of the complete modules 3 of two fuel cells consists of the rectangular ceramic frame 4 with the lower circumferential groove 6 and the upper circumferential spring 7 with four square round mounting and through-openings 8 and 8' and between them two through-openings with rectangular profile with rounded shorter sides, which are carried out along both shorter sides, i.e. opening 9 for supplying gaseous fuel, opening 10 for supplying air, opening 11 for discharging nitrogen and opening 12 for discharging the exhaust gases.Furthermore, a two-stage frame receptacle 15 with different dimensions is provided on the upper surface 13 of the ceramic frame 4 around its centrally located square through-opening 14, the higher vertical side wall of which is connected to the opening 9 for the fuel supply by means of the pin holes 16 provided therein, and the vertical side wall of the square opening 14 arranged below this receptacle is connected to the opening 10 for the air supply by means of the pin holes 17 provided therein, whereas a higher vertical side wall on the opposite side of this receptacle is connected to the opening 11 for the nitrogen discharge by means of the pin holes 18 and the lower vertical side wall of the square opening 14 is connected to the opening 12 for the exhaust gas discharge by means of the pin holes 19 provided therein.Furthermore, a perforated, heat-resistant metal cathode plate 20 with a U-profile is arranged in the square through-opening 14 of the ceramic molded part 4 and in the lower, smaller, two-stage frame receptacle 15. The lower free end of this cathode plate has an angle offset 21, the horizontal part of which rests against the horizontal side of this smaller, two-stage receptacle 15. Within this cathode plate, a square ceramic molded part 22 with grooves 22' on both sides for air distribution is arranged. In contrast, in the upper, higher part of the frame receptacle 15, two fuel cells 24 of the module 3, each with grooves 25 on one side, are arranged on the upper part 23 of the cathode plate 20. These fuel cells are oriented with their grooves 25 towards each other and are separated from each other by a perforated, heat-resistant metal anode plate 26 with a U-shaped bent end 27, which rests against the horizontal part of the angle offset 21 of the cathode plate 20.Furthermore, the contact surfaces of the fuel cells 24 with the lateral wall surfaces of the two-stage frame mounts 15 of the ceramic frames 4 and the surfaces of the stacked ceramic frames 4 are sealed with the high-temperature ceramic paper not shown in the drawing, which is saturated with finely ground glass-ceramic material. All single-slotted fuel cells 24 have an anode layer 28 with a thickness of 1.2 mm, made of composite NiO, Y-ZrO2 (zirconium dioxide stabilized with yttrium oxide), which forms the supporting layer of this cell and a layer of solid electrolyte 29 with a thickness of 5 µm, made of ZrO2, stabilized with Y2O3, adjoining its flat surface, and a cathode layer (cathode) 30 made of the material with perovskite structure consisting of a mixture of the oxides La, Sr, Co and Fe (LCSF) with a thickness of 30 µm and oxides La, Sr, Mn (LSM) with a thickness of 200 µm.The metal hood 5 for covering the set of complete modules 3 is equipped with the socket 31 for supplying the gas fuel to the collecting angled duct 32 and with the socket 33 for supplying the air to the collecting angled duct 34 - which are formed by these modules and this hood, wherein the ends of the horizontal parts 35 and 35' which are formed in the metal hood 5 are secured with metal plugs 36 and the vertical sections 37 and 37' accordingly form the extension of the openings 9 which form the vertical part of the collecting duct 32 and the extension of the openings 10 which form the vertical part of the collecting duct 34.Furthermore, the other openings 11, which are carried out in ceramic frames 4 of set 2 of modules 3, form the collecting channel 38 for the discharge of nitrogen, on the extension of which in the metal base 1 a through-opening 39 is carried out, which is closed with a bushing stub 40, and the openings 12 of these frames form the collecting channel 41 for the discharge of exhaust gases, on the extension of which in the metal base 1 a through-opening 42 is carried out, which is closed with a bushing stub 43.Furthermore, the metal base 1, the complex 2 of five complete modules 3 of two fuel cells 24 resting on it, and the metal hood 5 covering it are connected to each other by means of four pressure screws 44 and 45, which are arranged at the corners and are located in the openings 8 and 8' of the ceramic molded parts 4, as well as in the coaxially located openings 46, which are made in the metal base 1, and in the openings 47, which are made in the metal hood 5.Furthermore, in the lower part of the metal base 1, two screws 45 are arranged at the corners of a shorter side of the complex 2 and bridged by the metal plate 48, which rests against the flanges of the ceramic flange bushings 49, which are arranged in this base along the extension of coaxially arranged openings 8' of the complex 2 and are pressed with the screw heads 50, whereas the heads 50' of the two other pressure screws 44 are arranged on the opposite side of the complex 2 and lie directly against the lower surface of this metal base.Furthermore, the upper ends of the pressure screws 44 and 45 are arranged in the ceramic spacer bushings 51, which rest on the upper surface of the metal hood 5. Additionally, the upper ends of two pressure screws 44 are positioned in the ceramic flange bushings 52, which are arranged in the openings of this hood that are coaxial with the openings 8 of the complex 2. Similarly, the ceramic spacer bushings 51, which are also placed on these screws, are located in the flanges 53 of these bushings. On the faces of these spacer bushings, the helical springs 54, which are placed on the screws 44 and 45, are located and pressed against the bushings by means of the ring washers 55 with nuts 56, which are screwed onto these screws. The openings 9, 10, 11, and 12 in the ceramic frames 4 are rectangular with rounded shorter sides.

[0022] In the second embodiment, which is shown in the drawing Fig.As shown in Figure 29, the stack according to the invention has the complex 2, which is formed from fifteen identical complete modules 3 of two identical fuel cells as previously described in the first embodiment, wherein in this stack the single-slotted fuel cells 24 are used, the anode layer 28 of which has a thickness of 2 mm, the electrolyte layer 29 the thickness of 15 µm, made of ZrO2 but stabilized with Sc2O3, and the cathode 30 adjacent to it the thickness of 200 µm.

[0023] In a further embodiment of the stack according to the invention, not shown in the drawing, CS SOFC solid oxide fuel cells are used as fuel cells 24, where the electrolyte layer 29 is zirconium dioxide stabilized with Y₂O₃ with a thickness of 8 µm, and the cathode 30 has a thickness of 1.5 mm and is grooved on one side, simultaneously forming a load-bearing layer for transmitting mechanical loads, and the anode 28 is designed as a flat layer with a thickness of 150 µm, which necessitates a change in the location of the points for supplying the fuel and air, as well as for discharging the exhaust gases and gas. Furthermore, in this embodiment, ceramic frames are used which are equipped with oval openings 9, 10, 11 and 12.

[0024] According to the invention, the principle of generating electrical energy using the cell stack is based on the fact that such a stack of fuel cells is installed in a sheet metal chamber - housing which is lined internally with the fiber layer of thermal insulation and is equipped with heating coils surrounding the stack, and electrical lines are connected to the outwardly projecting ends of the two screws 44 and 45, which are connected to the receiver of the electrical energy generated from gas, not shown in the drawing.The gaseous fuel, preferably hydrogen or a mixture of hydrogen and carbon dioxide, for example synthesis gas or products obtained from reforming carbohydrates such as: natural gas, biogas or methanol, is fed under a pressure of 30 kPa to the fuel nozzle 31, which is fixed in the heat-resistant metal hood 5 of this stack, from where the fuel passes via the horizontal channel 35 to the vertical collecting channel 32, and further passes through the pin holes 16 between the slots 25 of two opposing anode layers 28 of the fuel cells 24, which are separated from each other by the heat-resistant perforated metal anode plate 26 for the dissipation of electrical charges.The air required for combustion of the gases is simultaneously supplied to the bushing 33, which is located in the heat-resistant metal hood 5 under a pressure of 30 kPa. This air passes through the horizontal channel 35' to the vertical collecting channel 34, from where it passes through the pinholes 17 between the double grooves 22' of the ceramic molded part 22 to distribute the air to two adjacent flat cathode surfaces 30 of the fuel cells 24. At the same time, the oxygen contained in this air and delivered to the surfaces of these cathodes is ionized by the attachment of two electrons from the outer circuit, and the resulting ions O. -2The process, resulting from the differences in the partial pressure of oxygen on both sides of these cells, leads through the oxygen vacancies of the crystal structure of the solid electrolyte layer 29 towards their anodes 28, where they release two electrons through perforated anode plates 26 to the outer circuit, which is connected to the energy receiver (not shown in the drawing), while the resulting oxygen atoms combine with the hydrogen and / or carbon dioxide molecules to form the water vapor and / or carbon dioxide, which pass through the pinholes 19 of each ceramic frame 4, diagonally to the pinholes for the fuel supply 16, to the collecting exhaust gas channel 41 and further through the outlet bushing 43 of the metal base 1 outside the device containing the stack according to the invention, whereas the nitrogen remaining in the cathode surface flows with the remaining air out of the pinholes 18 of this ceramic frame,which are arranged diagonally to the pinholes for the air inlet 17, from which it is diverted through the nitrogen collection channel 38 and the bushing stub 40 of the metal base 1 outside the device.

[0025] Furthermore, the electrical charges generated on both adjacent anode layers 28 of the fuel cells 24 are collected by perforated anode plates 26, which are positioned between the pairs of grooved surfaces with anode layers 28 of two fuel cells 24 and transferred to the cathode layers 30 of the adjacent modules 3 by means of perforated metal cathode plates 20, which are in contact with the perforated anode plates 26. This series connection of the modules 3, which are formed from two fuel cells 24, allows for a gradual increase in the voltage of the stack under direct current, the value of which depends on the number of these stacked modules and the effective area of ​​the cells.Furthermore, the perforated metal cathode plates 20 contact the metal base 1 from the underside of the stack according to the invention. The base 1, in turn, contacts two screws 44, which are not insulated in this base and press against the stack. These screws are arranged on one of the shorter sides of the ceramic frames 4, and pass through the insulated ceramic flange bushings 52, which are arranged in the metal hood 5 of this stack. Additionally, the perforated metal anode plates 26 in the upper part of the stack contact the metal hood 5 and two other pressure screws 45, the lower ends of which pass through the insulated ceramic spacer bushings 49, which are arranged in the metal base 1 of the stack and are connected to the metal plate 48 from below.The electrical energy generated in the fuel cells 24 is transmitted to the corresponding receiver via electrical conductors attached to the cold top of the opposing pressure screws 44 and 45 with nuts (not shown in the drawing). A fuel cell stack, as described in the example embodiment, or several such stacks, surrounded by heating coils or separated along their longer sides, can be installed in a thermally insulated metal chamber housing equipped with heating coils. These stacks can be connected to each other in series or in parallel outside the device, depending on the current and voltage requirements. To improve the efficiency of the overall system, the device can also be equipped with nitrogen-air and / or exhaust gas-air heat exchangers. List of terms used in the drawings 1 heat-resistant metal base 2 sets of six modules of the two fuel cells 3 Module of the two fuel cells 4 ceramic frames of the module 5 heat-resistant metal hoods 6 circumferential grooves of the ceramic frame, metal base and metal hood 7 circumferential springs of the ceramic frame, metal base and metal hood 8 two openings for the screws to press the stack 8' two openings for the screws to press the stack 9 rectangular openings in the ceramic frame with rounded shorter sides or oval openings for fuel supply 10 rectangular openings in the ceramic frame with rounded shorter sides or oval openings for air supply 11 rectangular opening of the ceramic frame with rounded shorter sides or oval opening for nitrogen drainage 12 rectangular openings in the ceramic frame with rounded shorter sides or oval openings for exhaust gas venting 13 Surface of the ceramic frame 14 central square frame of the ceramic frame 15 two-stage frame shots in ceramic frames 16 pin holes for connecting the two-stage frame mount to the fuel supply opening. 17 pinholes for connecting the two-stage frame mount to the air supply opening 18 pinholes for connecting the two-stage frame mount to the opening for nitrogen drainage 19 pin holes for connecting the two-stage frame mount to the opening for exhaust gas discharge 20 perforated metal cathode plates 21 Angle offset of the perforated cathode plate 22 ceramic molded part with grooves on both sides 22' Double-sided grooves of the ceramic molded part 23 Top part of the perforated cathode plate 24 single-sided slotted fuel cell 25 grooves of the single-sided grooved cell 26 perforated metal anode plate 27 End of the perforated anode plate with U-profile 28 Anode layer of the single-slotted fuel cell 29 Solid electrolyte layer of the single-slotted fuel cell 30 Cathode layer of the single-slotted fuel cell 31 sockets of the metal hood for supplying fuel 32 Collecting angle channel for supplying the fuel 33 sockets on the metal hood for supplying air 34 Collecting angled duct for supplying air 35 horizontal nozzles of the collecting channel for supplying the fuel 35' horizontal nozzle of the collecting channel for fuel supply 36 metal plugs 37 Vertical section of the collecting angle channel for supplying the fuel 37' vertical section of the collecting angled duct for supplying air 38 Collection channel for nitrogen drainage 39 Through-hole of the metal base 40 bushings of the metal base for nitrogen drainage 41 Collection channel for the discharge of exhaust gases 42 Through-hole of the metal base 43 bushings of the metal base for the discharge of exhaust gases 44 screws for pressing the stack 45 screws for pressing the stack 46 openings for the screws of the metal base 47 openings for the screws of the metal hood 48 Metal plate for bridging the screw 49 flanged bushings of the metal base 50, 50' screw heads for pressing the stack 51 ceramic spacer bushings for the metal hood 52 ceramic flange bushings of the metal hood 53 flanges of the flange bushings 54 coil springs 55 washers for nuts 56 nuts of the pressure screws

Claims

[1] The high-temperature fuel cell stack for generating electrical energy with the modules that are supplied with gas stream as fuel and oxidant, which is supplied to the individual modules of two fuel cells characterized by, that it is composed of a set (2) consisting of some or more identical modules (3) of two fuel cells, which are stacked in the form of the cuboid body and are separably connected to one another, of a heat-resistant metal base (1) on which a module set (2) is placed and of a heat-resistant metal cover (5) for covering the set, which is equipped with the bushing (31) for supplying the gas fuel to the inner collecting angled channel (32) and with bushings (33) for supplying the air to the inner collecting angled channel (34), whereas the heat-resistant metal base (1) is equipped with the bushing (43) which forms the extension of the inner collecting channel (41) for the discharge of the exhaust gases and bushing (40) which forms the extension of the inner collecting channel (38) for the discharge of nitrogen, wherein each of the modules (3) of two fuel cells is composed of the ceramic frame (4),which has a two-stage frame (15) around the centrally located square through-opening (14), in the lower part of which a perforated heat-resistant metal cathode plate (20) with a U-profile and angular offset (21) of the upper end is arranged, within which a double-grooved ceramic molded part (22) is located, whereas on the flat part (23) of the cathode plate (20) two single-grooved fuel cells (24) are arranged, which are oriented with their grooves (25) towards each other and are separated from each other by a perforated heat-resistant metal anode plate (26) with a U-shaped bent end (27) which rests against the angular offset (21) of the cathode plate (20). [2] Stack according to claim 1 characterized by, that each of its single-slotted fuel cell (24) forms a supporting anode layer (28) with a thickness of 0.8-2.0 mm, consisting of a composite of NiO and ZrO2 stabilized with Y2O3, of the solid electrolyte layer (29) with a thickness of 5-15 µm of ZrO2 stabilized with Y2O3 or Sc2O3, adjacent to the side of the slots (25) and to the flat surface, and of the adjacent cathode layer - cathode (30) with a thickness of 100 to 250 µm, of the material with perovskite structure consisting of a mixture of the oxides La, Sr, Co and Fe (LSCF) as well as oxides La, Sr, Mn (LSM). [3] Stack according to claim 1, characterized in that the ceramic frame (4) of each module of the fuel cell pair (24) has two through-profile openings arranged coaxially to each other on the upper surfaces (13) of the shorter sides, namely having on one side an opening (9) for supplying the gaseous fuel and an opening (10) for supplying air, and on the other shorter side having an opening (11) for discharging nitrogen and an opening (12) for discharging exhaust gases, and furthermore, a side wall of the opening (9) is connected to the upper side wall of the two-stage frame receptacle (15) by means of the pin holes (16), and a side wall of the opening (10) is connected to the lower side wall of this receptacle by means of the pin holes (17).In contrast, the side wall of the opening (11) is connected to the lower side wall of the two-stage frame mount (15) using the pin holes (18), and the side wall of the opening (12) is connected to the upper side wall of this mount using the pin holes (19). [4] Stack according to claim 1 characterized by , that the lower part of the perforated heat-resistant U-profile cathode plate (20) touches the heat-resistant metal base (1), which touches two screws (44) insulated in the heat-resistant hood (5) of the set (2), which press this set, and that the upper perforated metal anode plate (26) touches the heat-resistant metal hood (5), and this touches two other screws (45) which press this set and are insulated in the base (1). [5] Stack according to claim 1 characterized by, that the contact surfaces of the fuel cells (24) are sealed with the wall surfaces of the two-stage frame mounts (15) and the contact surfaces of the stacked ceramic frames (4) are sealed with the ceramic paper saturated with finely ground glass ceramic material.

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