Fuel cell generator module with fuel cell stack assembly

Abstract

The invention relates to a fuel cell generator module (10) comprising a fuel cell stack assembly for generating electrical power. According to the invention, a supply corridor (4) is arranged in a central region, extending substantially in a vertical direction (V) and a horizontal direction (H) through the fuel cell generator module (10). In addition, a stack direction (S) of the stack (1) extends horizontally through the fuel cell generator module (10), and stack ends (14) of at least two stacks are oppositely directed towards one another from both side of the supply corridor. The flow paths of an anode supply lines (20) and a cathode supply lines (30) are arranged between the stack ends (14) of the two stacks (1) that are pointing towards one another within the supply corridor (4).

Description

[0001] AVL List GmbH

[0002] 1

[0003] Fuel cell generator module with fuel cell stack arrangement

[0004] The present invention relates to a fuel cell generator module for generating electrical power with a thermally enhanced fuel cell stack arrangement.

[0005] The fuel cell generator module according to the invention is used as a stand-alone device or as part of a fuel cell generator system in energy generation for feeding renewable energy into supply grids or self-sufficient island networks.

[0006] Efficient fuel cell systems in stationary applications of the SOFC type (Solid Oxide Fuel Cells) and SOEC (Solid Oxide Electrolyzer Cell) are known, which are used in large-scale applications, such as grid feed-in, and are operated at a relatively constant operating point or with low power dynamics.

[0007] Solid oxide fuel cells operate at high temperatures. Due to these high temperatures, the temperature gradient from the fuel cell generator module to the surroundings is high, resulting in a correspondingly inhomogeneous temperature distribution. The position of fuel cell stacks within the fuel cell generator module relative to their distance from the outside has a significant influence on the dissipation of waste heat into the surroundings.

[0008] Furthermore, due to the high temperatures and temperature gradients across areas of the fuel cell generator module, challenges arise for optimizing media flows to supply the fuel cell stacks, particularly with regard to heat distribution and heat exchange between the media, which influence the overall efficiency of the fuel cell generator module.

[0009] One approach to preheating fresh media involves the use of heat exchangers, in which waste heat from the discharged media streams is transferred to the incoming media streams. While the use of such components has become standard, concepts for static solutions regarding the arrangement of system components remain to be developed. Accordingly, there is a need for an optimized arrangement of the system components relative to one another in the context of efficient heat distribution in the media streams. It is an object of the invention to create a technology that improves the thermal efficiency or overall energy efficiency of a fuel cell generator module.It is a more specific object of the invention to provide a design of such a fuel cell generator module or an arrangement of system components therein, which more efficiently designs an optimized heat distribution among the media flows in the fuel cell generator module in a static manner and thus in a simple and cost-effective manner, without additional system components.

[0010] The above object is achieved by a fuel cell generator module having the features of claim 1. Further features and details of the invention emerge from the subclaims, the description and the drawings.

[0011] The fuel cell generator module with a fuel cell stack assembly is used to generate electrical power. The fuel cell generator module includes a plurality of fuel cells stacked one upon another in a stacking direction and electrically connected; anode supply lines including an anode gas supply line for supplying a fuel gas to anode sections of the fuel cells and an anode gas discharge line for discharging an anode exhaust gas therefrom; and cathode gas supply lines including a cathode gas supply line for supplying an oxidizing gas to cathode sections of the fuel cells and a cathode gas discharge line for discharging a cathode exhaust gas therefrom.

[0012] According to the invention, the fuel cell generator module has a supply corridor in a central region, which extends essentially in a vertical direction and a horizontal direction through the fuel cell generator module. The stacks are stacked one above the other, i.e., the stacking direction of the stacks extends vertically through the fuel cell generator module, and stack ends of at least two stacks face each other on both sides of the supply corridor. Advantageously, several stacks can be arranged or provided next to one another. The individual fuel cells are, in particular, always flat and lie one above the other or are stacked vertically upward.In particular, flow paths of the anode supply lines and flow paths of the cathode supply lines are arranged between the mutually facing stack ends of the at least two stacks within the supply corridor.

[0013] The invention thus provides a vertical stacking of fuel cells in a fuel cell generator module, the arrangement of fuel cell stacks of which is centrally divided by a vertical plane, essentially a plane of symmetry, as well as the establishment of a corridor along the division in which the media distribution runs.

[0014] According to the invention, control and operability components, i.e., components of a "balance of plant" (BoP), such as an air compressor, a fuel gas control valve, etc., are advantageously arranged in the supply corridor. Consequently, the components of the BoP are not arranged in the so-called manifold between the fuel cell stacks, but rather between the mutually facing stack ends of the at least two stacks within the supply corridor.

[0015] The arrangement according to the invention takes advantage of the fact that waste heat from power generation or electrochemical reactions in the fuel cells is more concentrated in a central area of ​​the module due to a lack of dissipation via the module's outer surfaces. This creates a locally higher temperature zone in a central section during module operation, in which the supply corridor according to the invention is located.

[0016] As an advantage of the invention, the media distribution is arranged in a central region of the fuel cell generator module, which, due to the lowest dissipation of waste heat via an external surface, has the highest local temperature in a heat distribution across the fuel cell generator module. Due to the high operating temperature of solid oxide fuel cells (SOFCs), it is advantageous for thermally efficient operation if the freshly supplied media streams of the fuel gas and the oxidation gas are preheated as intensively as possible before entering the fuel cell stack. The arrangement of the supply corridor in the central, warmest region and the very short inlet paths, which are made possible by the vertical stacking direction, ensure the greatest possible preheating of fresh media streams by static means of the arrangement. In particular, cooling of the supply lines by an external region of the module is avoided.

[0017] Furthermore, further advantages of the invention compared to a known point-symmetric media flow and a radial stack arrangement are that standard components with an available design and substantially rectangular dimensions can be used in the arrangement according to the invention.

[0018] According to an advantageous aspect of the invention, the plurality of fuel cells can be divided into at least four stacks, the stack ends of which face each other on both sides of the supply corridor, with at least two stacks arranged side by side in a horizontal direction orthogonal to the stacking direction. Thus, the arrangement of fuel cell stacks can be continued in one plane of the module while maintaining the thermally advantageous effects. A number of stack pairs on both sides of the supply corridor can be extended horizontally as desired, depending on the dimensions of the module.

[0019] According to an advantageous aspect of the invention, the plurality of fuel cells can be divided into at least four stacks, the stack ends of which face each other on both sides of the supply corridor, with at least two stacks arranged one above the other in a vertical direction orthogonal to the stacking direction. Accordingly, the arrangements of fuel cell stacks can also be arranged one above the other in several levels, while maintaining the orientation of the stacking direction and the supply corridor, as well as their thermally advantageous effects.

[0020] According to an advantageous aspect of the invention, the anode supply line and the cathode supply line, as well as the anode discharge line and the cathode discharge line, can each be fluidly connected to the at least two stacks at the mutually facing stack ends. This minimizes potentially cooler paths of the inlet paths between the supply corridor and the stacks. According to an advantageous aspect of the invention, the cathode discharge line can exit the fuel cell generator module in a substantially vertical direction in the supply corridor. Thus, the buoyancy of the warmer exhaust gas toward an outlet is utilized in a fluid-dynamic manner.

[0021] According to an advantageous aspect of the invention, the cathode discharge line of a stack can be routed through an oxidation catalyst for the oxidative aftertreatment of a cathode exhaust gas, wherein the oxidation catalyst is arranged in the supply corridor. Since the oxidation catalyst requires a predetermined minimum operating temperature, which must be maintained, its arrangement in the locally higher temperature zone of the supply corridor has a positive effect on more efficient temperature control of the media flows in a mutual heat exchange.

[0022] According to an advantageous aspect of the invention based on this, at least two opposing stacks can pass through the same oxidation catalyst. The shared use of system components for adjacent stack arrangements results in further efficiency improvements, simplifications, and space and cost savings.

[0023] According to an advantageous aspect of the invention, the anode discharge line of a stack can lead to a reformer device for enriching an unreacted portion of the fuel gas in an anode exhaust gas with fresh fuel gas, wherein the reformer device is arranged in the supply corridor. Since the reformer device also requires a predetermined minimum operating temperature, which must be maintained, its arrangement in the locally higher temperature zone of the supply corridor in a mutual heat exchange also has a positive effect on more efficient temperature control of the media flows. For this purpose, a recirculation section is provided, which comprises a recirculation line to convey at least a portion of the anode exhaust gas back toward the anode section. The fresh fuel gas is supplied to this recirculation line, so that, in particular, a mixture of anode exhaust gas and fresh fuel gas is supplied to the anode section.

[0024] According to an advantageous aspect of the invention based on this, the anode discharge lines of at least two opposing stacks can run through the same reformer device. The shared use of system components for adjacent stack arrangements results in increased efficiency, simplification, and space and cost savings.

[0025] According to an advantageous aspect of the invention, the anode gas supply line and the cathode gas supply line can enter the fuel cell generator module in a substantially horizontal direction. As a result, the flow paths of the media supply extend as far as possible through the locally higher temperature zone of the supply corridor, which has a positive effect on more efficient temperature control of the media flows through the greatest possible mutual heat exchange.

[0026] According to an advantageous aspect of the invention, an oxidation gas heat exchanger can be arranged in the supply corridor between the cathode discharge line and the cathode supply line of the same stack. The arrangement of the oxidation gas heat exchanger in the locally higher temperature zone of the supply corridor increases thermal efficiency in preheating the fresh oxidation gas.

[0027] According to an advantageous aspect of the invention, a fuel gas heat exchanger can be arranged in the supply corridor between the anode discharge line and the anode supply line of the same stack. The arrangement of the fuel gas heat exchanger in the locally higher temperature zone of the supply corridor also increases the thermal efficiency of fuel gas preheating.

[0028] According to an advantageous aspect of the invention, the anode gas supply line can pass through a preheating device arranged upstream of the fuel gas heat exchanger in the supply corridor. The arrangement of the preheating device in the locally higher temperature zone of the supply corridor further increases the thermal efficiency of preheating the fuel gas.

[0029] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments are described in detail with reference to the drawings. They show schematically:

[0030] Fig. 1 is a schematic block diagram in a plan view of a fuel cell generator module according to an embodiment of the invention, with a temperature distribution shown; Fig. 2 is a perspective section of system components of a fuel cell generator module according to an embodiment of the invention; and

[0031] Fig. 3 shows a perspective section of system components and a wiring network of a fuel cell generator module according to an embodiment of the invention.

[0032] Fig. 1 is a schematic plan view of a fuel cell generator module 10 in which ten stacks 1 (A to J) are arranged on a base surface in two opposite groups (A to E) and (F to J), wherein the individual stacks 1 within each group are adjacent to one another in a horizontal direction (V). The same configuration of stacks 1 is further arranged in the above and below levels of the fuel cell generator module 10 (not shown in further detail). The fuel cells are stacked in a horizontal stacking direction S; in other words, the stacks 1 are arranged horizontally with respect to the illustrated plan view.

[0033] The fuel cell generator module 10 can be used independently as a stand-alone device for power generation, or alternatively can be a unit in a system environment (not shown further) of a fuel cell generator system with a plurality of electrically connected fuel cell generator modules 10.

[0034] As illustrated by hatching, the fuel cell generator module 10 includes outer, cooler regions exposed to a cooler ambient temperature. These outer regions facilitate the dissipation of waste heat from the fuel cells of the stack 1, resulting in a temperature gradient from the inside to the outside. In a central region of the fuel cell generator module 10, which is not exposed to an outer surface, a higher local temperature exists due to the correspondingly low dissipation of waste heat from the fuel cells.

[0035] In this locally higher temperature zone, a supply corridor 4 is arranged, which extends parallel to the opposing groups (A to E) and (F to J) of stacks 1 between them in the sense of a horizontally and vertically spanned plane. Within the supply corridor 4, the flow paths of a media distribution are arranged through anode supply lines 20 and cathode gas supply lines 30. In addition, components of a control and operability system (not shown in detail), i.e., components of a "balance of plant" (BoP), such as an air compressor, a fuel gas control valve, etc., are arranged in the supply corridor 4.

[0036] Depending on the requirements for the power dimensioning and reliability of the fuel cell generator module 10, the anode supply lines 20 and cathode gas supply lines 30 as well as components of the BoP are provided separately or redundantly for each of the illustrated levels of the fuel cell generator module 10, or are used jointly for all levels or in a connected line network of stacks 1 on different levels of the fuel cell generator module 10.

[0037] Fig. 2 shows, in perspective, a schematic arrangement of all system components of the fuel cell generator module 10 through which the media distribution flows with respect to a temperature control of the media flows by means of heat exchange and exhaust gas treatment.

[0038] Thus, on a left side and a right side of the supply corridor 4, the stack ends 14 of two opposite stacks 1 facing each other are representatively shown. The system components for temperature-controlled media distribution mentioned in the supply corridor 4 include oxidation heat exchangers 34 for preheating supplied air by a cathode exhaust gas stream, an oxidation catalyst 33 for oxidizing hydrogen concentrations in the cathode exhaust gas flowing from a pressure tank, and a symbolically represented recirculation 26 of the anode exhaust gas including a preheating device 25 for preheating the fresh fuel gas and a reformer device 23 for enriching an unreacted portion of the fuel gas in an anode exhaust gas with fresh fuel gas.

[0039] With the exception of two fuel gas heat exchangers 24 arranged adjacent to the supply corridor 4, all of the aforementioned system components are arranged in the temperature zone of the supply corridor 4, whereby they additionally heat the supply corridor 4 from waste heat from the exhaust gases absorbed from the fuel cells, support the maintenance of their own operating temperature, or absorb heat to preheat freshly supplied media via concentrated waste heat from the stack 1. Fig. 3 shows the structure from Fig. 2 from a different perspective, including a network of the anode supply lines 20 and the cathode gas supply lines 30. The anode gas supply line 21 and the cathode gas supply line 31 for supplying fresh or cold fuel gas and oxidation gas extend horizontally through the supply corridor in order to be preheated, if possible, via heat exchange between the lines.The cathode gas discharge line 32 runs vertically from an outlet at the stack end 14 through the oxidation catalyst 33 and through the oxidation gas heat exchanger 34, which preheats the freshly supplied air before it enters the stack end 14. The cathode exhaust gas exiting the stack end 14 flows through the reformer unit 23 and, via the preheating device 25 and the fuel gas heat exchanger 24, heats the freshly supplied fuel gas before it enters the stack end 14.

[0040] The system components for temperature-controlled media distribution, representatively shown on a stack 1 or a stack end 14, extend equally to several adjacent stacks 1, which are vertically adjacent and arranged vertically one above the other in tiers. In particular, it is provided that two opposing stacks 1 on either side of the supply corridor 4 are jointly connected to the same heat exchange components or share their functionality.

[0041] The above explanations of the embodiments describe the present invention exclusively by way of examples. Of course, individual features of the embodiments can be freely combined with one another, provided they are technically feasible, without departing from the scope of the present invention.

[0042] List of reference symbols

[0043] 1 stack of fuel cells

[0044] 4 Supply corridor

[0045] 10 Fuel cell generator module

[0046] 14 Stack end

[0047] 20 anode supply lines

[0048] 21 Anode gas supply line

[0049] 22 Anode gas discharge line

[0050] 23 Reformer Institution

[0051] 24 fuel gas heat exchangers

[0052] 25 Preheating device

[0053] 26 Anode gas recirculation

[0054] 30 cathode gas supply lines

[0055] 31 Cathode gas supply line

[0056] 32 Cathode gas discharge line

[0057] 33 Oxidation catalyst

[0058] 34 oxidation gas heat exchangers

[0059] H horizontal direction

[0060] V vertical direction

[0061] S Stacking direction

Claims

Patent claims 1. A fuel cell generator module (10) having a fuel cell stack arrangement for generating electrical power, comprising: a plurality of fuel cells stacked one on top of the other in stacks (1) in a stacking direction (S) and electrically connected; Anode supply lines (20) comprising an anode gas supply line (21) for supplying a fuel gas to anode sections of the fuel cells and an anode gas discharge line (22) for discharging an anode exhaust gas therefrom; Cathode gas supply lines (30) comprising a cathode gas supply line (31) for supplying an oxidizing gas to cathode sections of the fuel cells and a cathode gas discharge line (32) for discharging a cathode exhaust gas therefrom; characterized in that the fuel cell generator module (10) has, in a central region, a supply corridor (4) which extends substantially in a vertical direction (V) and a horizontal direction (H) through the fuel cell generator module (10); and the stacking direction (S) of the stacks (1) extends horizontally through the fuel cell generator module (10), and stack ends (14) of at least two stacks (1) face each other on both sides of the supply corridor (4); wherein Flow paths of the anode supply lines (20) and flow paths of the cathode supply lines (30) are arranged between the mutually facing stack ends (14) of the at least two stacks (1) within the supply corridor (4).

2. Fuel cell generator module (10) according to claim 1, wherein the plurality of fuel cells is divided into at least four stacks (1), the stack ends (14) of which are arranged opposite one another on both sides of the supply corridor (4). assign, wherein at least two stacks (1) are arranged next to one another in a horizontal direction (H) orthogonal to the stacking direction (S).

3. Fuel cell generator module (10) according to claim 1 or 2, wherein the plurality of fuel cells is divided into at least four stacks (1), the stack ends (14) of which face each other on both sides of the supply corridor (4), at least two stacks (1) are arranged one above the other in a vertical direction (V) orthogonal to the stack direction (S).

4. Fuel cell generator module (10) according to one of the preceding claims, wherein the anode supply line and the cathode supply line as well as the anode discharge line and the cathode discharge line are each in fluid communication with the at least two stacks (1) at the stack ends (14) facing one another.

5. Fuel cell generator module (10) according to one of the preceding claims, wherein the cathode discharge line exits the fuel cell generator module (10) in the supply corridor (4) in a substantially vertical direction (V).

6. Fuel cell generator module (10) according to one of the preceding claims, wherein the cathode discharge line of a stack (1) leads through an oxidation catalyst (33) for the oxidative aftertreatment of a cathode exhaust gas, wherein the oxidation catalyst (33) is arranged in the supply corridor (4).

7. Fuel cell generator module (10) according to one of the preceding claims, wherein the cathode discharge lines of at least two opposite stacks (1) lead through the same oxidation catalyst (33).

8. Fuel cell generator module (10) according to one of the preceding claims, wherein the anode discharge line of a stack (1) leads into a reformer device (23) for enriching the anode exhaust gas with fresh fuel gas, wherein the reformer device (23) is arranged in the supply corridor (4).

9. Fuel cell generator module (10) according to claim 8, wherein the anode discharge lines of at least two opposite stacks (1) lead through the same reformer device (23).

10. Fuel cell generator module (10) according to one of the preceding claims, wherein the anode gas supply line (21) and the cathode gas supply line (31) enter the fuel cell generator module (10) in a substantially horizontal direction (H).

11. Fuel cell generator module (10) according to one of the preceding claims, wherein an oxidation gas heat exchanger (34) is arranged in the supply corridor (4) between the cathode discharge line and the cathode supply line of the same stack (1).

12. Fuel cell generator module (10) according to one of the preceding claims, wherein a fuel gas heat exchanger (24) is arranged in the supply corridor (4) between the anode discharge line and the anode supply line of the same stack (1).

13. Fuel cell generator module (10) according to one of the preceding claims, wherein the anode gas supply line (21) leads through a preheating device (25) which is arranged upstream of the fuel gas heat exchanger (24) in the supply corridor (4).

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