Electrochemical cell apparatus

Abstract

An electrochemical cell apparatus comprising an enclosure and a stack of electrochemical cell units, the stack being contained within the enclosure. The apparatus comprising a manifold for supply of fluid to or exhaust of fluid from the stack, wherein the manifold is fixed relative to the enclosure at a first part of the manifold, and a support structure for the manifold at a second part of manifold. The support structure configured to allow relative movement between said second part and the enclosure. A thermal insulation layer is provided inside said enclosure defining a thermally insulated space in which said stack and manifold are located. A sensor assembly penetrates the enclosure and the thermal insulation layer. A receptacle is attached to or unitary with the manifold, the stack or a branch of the manifold. The sensor assembly is fitted into the receptacle and is configured to be flexible and movable in a lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer.

Description

[0001] ELECTROCHEMICAL CELL APPARATUS

[0002] Field of the Invention

[0003] The present invention relates to an electrochemical cell apparatus, and in particular, an electrochemical cell apparatus comprising electrolyser cell units, or stacks thereof, in an enclosure. The electrochemical cell units - typically electrolyser cell units, may include cell units of solid oxide or molten carbonate electrolyser cells. The present invention more specifically relates to the integration of temperature sensors into such an electrochemical cell apparatus.

[0004] The solid oxide electrolyser cell (SOEC) units may include metal-supported solid oxide electrolyser cell (MS-SOEC) units.

[0005] Background to the Invention

[0006] Electrochemical cell units are commonly referred to as fuel cell units or electrolyser cell units, and in some instances their names are interchangeable as some fuel cell units can work as electrolyser cell units and some electrolyser cell units can operate as fuel cell units, each either as a producer of electricity or in a regenerative mode - electrolyzing a fluid to electrochemically split it into two or more component parts. For example, some fuel cell units can produce electricity by using an electrochemical conversion process that oxidises fuel to produce electricity. Some fuel cell units can also, or instead, operate as regenerative fuel cells (or reverse fuel cells) units, often known as electrolyser cell units, for example to separate hydrogen and oxygen from water, carbon monoxide and oxygen from carbon dioxide, or nitrogen monoxide and oxygen from nitrogen dioxide.

[0007] Electrochemical cell units may be tubular or planar in configuration. Planar cell units may be arranged overlying one another in a stack arrangement, for example 100-400 cell units in a stack, with the individual fuel cell units arranged, for example, electrically in series. Tubular cell units may be arranged in groups, stacks or coils thereof.

[0008] A solid oxide fuel cell (SOFC) unit that produces electricity is based upon a solid oxide electrolyte that conducts negative oxygen ions from an oxygen electrode to a fuel electrode located on opposite sides of the electrolyte. For this, a fuel, or reformed fuel, contacts the fuel electrode and an oxidant, such as air or an oxygen rich fluid, contacts the air electrode. A solid oxide electrolyser cell (SOEC) may have the same structure as an SOFC but is essentially that SOFC operating in reverse, or in its regenerative mode, to achieve the electrolysis of fuel, for example water and / or carbon dioxide, by input of electrical energy and using the solid oxide electrolyte to produce hydrogen gas and / or carbon monoxide and oxygen.

[0009] Electrolyser cell stacks commonly operate at elevated temperatures. For example, intermediate or high temperature electrolysers (such as SOEC and alkaline electrolyte cells) have operational temperatures in excess of 400 °C, typically 450 °C to 700 °C for an intermediate temperature electrolyser such as one based on an MS-SOEC, and above 700 °C for high temperature electrolysers. Electrolyser cell stack(s) can be assembled within a housing, and can be combined with heat exchangers, fluid delivery pipework, and bus bars for distribution of electrical current to the stacks or cell units therein, amongst other equipment, to form an electrolyser apparatus, and the electrolyser apparatus will be configured to supply input gas to and exhaust off-gas from the electrolyser cell stack(s) at the required operational temperatures. During operation of such an electrolyser apparatus, and similarly with other types of electrochemical cell apparatus, it is beneficial to use temperature sensors to monitor the temperatures of certain elements or regions within the apparatus to allow the system to be optimally controlled. However, an issue with intermediate and high temperature electrochemical cell units, i.e. those that operate at temperatures above 350 °C, is that their elevated operational temperatures (relative to the surrounding environment) can lead to significant changes in the size of the apparatus during start-up and cool-down due to the coefficient of thermal expansion of the materials used. This can make it difficult to locate or connect a temperature sensor within an electrochemical cell apparatus , or where it needs to be positioned, if it is being installed as a replacement part, and can lead to failures of the temperature sensors during use due to movements within the apparatus between installation and operational use of the apparatus.

[0010] The present invention seeks to provide an electrochemical cell apparatus in which temperature sensors can be installed and used within the apparatus even despite movements of parts of its installation location due to thermal expansion or contraction of the components during start-up or shut down procedures, and during use of the apparatus.

[0011] SUMMARY OF THE INVENTION

[0012] According to the present invention there is provided an electrochemical cell apparatus comprising: an enclosure; a stack of electrochemical cell units, the stack being contained within the enclosure; a manifold for supply of fluid to or exhaust of fluid from the stack, wherein the manifold is fixed relative to the enclosure at a first part of the manifold; a support structure for the manifold at a second part of the manifold, the second part of the manifold being spaced from the first part of the manifold, wherein the support structure is configured to allow relative movement between said second part and the enclosure; a thermal insulation layer provided inside said enclosure; a thermally insulated space defined inside the thermal insulation layer, in which said stack and manifold are located; a sensor assembly which penetrates the enclosure and the thermal insulation layer; and a receptacle attached to or unitary with the manifold, the stack or a branch of the manifold; wherein the sensor assembly is fitted into the receptacle and the sensor assembly is configured to be flexible and movable in a lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer.

[0013] In other words, the senor assembly may be fixed at the enclosure and fitted or held in the receptacle. There will be relative differences in the amount of thermal expansion between the enclosure and the manifolds at operational temperatures of the electrochemical cell apparatus. As a result, the receptacle (which may also be referred to as a protective receptacle) may not be (and will not always remain) directly opposite a position at which the sensor assembly penetrates an outside wall of the enclosure. Their relative positions instead will change as an internal temperature of the thermally insulated space changes. In some embodiments, the receptacle is positioned to be opposite (or substantially opposite - i.e. at least partially overlapping) the position at which (or the hole through which) the sensor assembly penetrates an outside wall of the enclosure when the electrochemical cell apparatus is at room or ambient temperature, but will likely no longer be substantially opposite - i.e. not overlapping at all, when at normal operating temperatures. As discussed below, movements of up to at least 20mm are expected to occur in a typical electrochemical cell apparatus operating at a temperature in excess of 400 °C .

[0014] The sensor assembly is configured to be flexible and movable in a lateral direction (and may move laterally in a space between the enclosure and the receptacle, e.g., between the insulation and the receptacle (a volume typically holding fluid) and or within the thermal insulation layer). The lateral direction is relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer. The sensor assembly, even if fixed at an entry point through the enclosure's outside wall, and likewise fixed at the receptacle, is able to accommodate relative movement between the manifold and the entry point. This is due to the ability for the sensor assembly to flex and move. Such relative movement between manifold and enclosure is due to thermal expansion and contraction of the materials of those components through the full range of temperatures to which they will be exposed. These can include at least all commissioning, decommissioning and normal operating temperatures of the electrochemical cell apparatus.

[0015] In some embodiments, the sensor assembly comprises a temperature sensor. It can instead, or additionally, comprise a pressure sensor, a power sensor, a current sensor or a voltage sensor.

[0016] In some embodiments, the sensor assembly comprises a thermocouple.

[0017] In some embodiments, the receptacle is a thermowell. The thermowell may be attached to the manifold, for example, to provide thermal communication between a fluid within the manifold and a temperature sensor of the sensor assembly.

[0018] In some embodiments, the thermowell is attached to the manifold or a branch therefrom and the manifold is an inlet manifold for supply of a fluid to the stack, or an exhaust manifold for exhausting off-gas from the stack. Off-gas may be fluid which is exhausted from the stack (e.g., unspent fuel, sweep gas, and / or product of reaction at the electrochemical cell units).

[0019] In some embodiments, the first part of the manifold is at a first end of the enclosure. In some embodiments, the second part of the manifold is distal from the first part - for example spaced from the first end of the enclosure.

[0020] In some embodiments, the second part of the manifold is at or adjacent to a second end of the enclosure. In some embodiments, the second part of the manifold is instead at a central region of the enclosure (e.g., a central region along the same direction as a length axis of the manifold, for example a central third of the length of the manifold (and / or enclosure)).

[0021] The enclosure is typically generally cylindrical, with rounded ends and it has a longitudinal axis along which, or parallel to which, the manifolds extend.

[0022] In some embodiments, the sensor assembly penetrates the enclosure and the thermal insulation at a sidewall location of the enclosure. In some embodiments, the sidewall location is distal from the first end of the enclosure, i.e. spaced along the longitudinal axis. The receptacle is then also distal from the first end of the enclosure, albeit not necessarily opposite thereto, as explained previously.

[0023] In some embodiments, the relative movement arises in use due to differing coefficients of thermal expansion between the manifold and the enclosure. It can also (or instead) arise due to differing temperatures therebetween. For example, due to the thermal insulation properties of the thermal insulation layer, the thermally insulated space, and the manifold therein, may be exposed to fluids at or near operational temperatures of the stack, whereas the outside wall of the enclosure may be at or close to a temperature of air or the environment surrounding the outside wall of the enclosure, with the thermal insulation layer having a varying temperature profile therebetween.

[0024] In some embodiments, there is more than one sensor assembly, each sensor assembly extending through respective sidewall locations of the enclosure.

[0025] In some embodiments, all other connections for the stack that extend out of the enclosure, i.e. including, for example, the manifold and the electrical connections, but excluding any branches from the stack, extend through an end of the enclosure.

[0026] In some embodiments, the enclosure has an open end and a removable lid closing the open end, and all said other connections for the stack pass through the removable lid.

[0027] In some embodiments, the sensor assembly is configured to be flexible and movable within the thermal insulation layer in the lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer. This can extend the length of the sensor assembly that can flex - rather than being limited to the length between the thermal insulation layer and the receptacle - and can allow the manifold to be closer to the thermal insulation layer thereby improving utilisation of space inside the enclosure.

[0028] In some embodiments, an inner skin is provided on an inside of the thermal insulation layer, and the sensor assembly additionally penetrates the inner skin.

[0029] In some embodiments, the inner skin is metallic. In some embodiments, an elongated, enlarged, rectangular or elliptical hole is provided in the inner skin for the sensor assembly to pass through. The sensor assembly, by being configured to be flexible and moveable, and thus able to flex and move, can flex and move within the elongated, enlarged, rectangular or elliptical hole by virtue of the elongated, enlarged, rectangular or elliptical hole being larger in at least one lateral direction than the corresponding width of the sensor assembly. This can further enable flexure of the sensor assembly relative to the thermal insulation layer or the inner skin.

[0030] In some embodiments, the longer direction is substantially parallel to the longitudinal axis of the manifold.

[0031] In some embodiments, the hole is larger in two orthogonal lateral directions to provide a broader degree of lateral freedom for the sensor assembly to flex and move therein.

[0032] In some embodiments, a funnel-like passageway is provided in the thermal insulation layer to accommodate this flexing and movement of the sensor assembly, with a wider end of the passageway facing the thermally insulated space. The sensor assembly will be able to flex and move within the passageway by virtue of the passageway, at its wider end, being larger in at least one lateral direction than the corresponding width of the sensor assembly. In some embodiments, the passageway, at its wider end, is larger in two orthogonal lateral directions to provide a broader degree of lateral freedom for the sensor assembly to flex and move therein.

[0033] In some embodiments, a feedthrough tube is provided through the thermal insulation layer.

[0034] In some embodiments, a feedthrough tube is provided between the thermal insulation layer and the receptacle.

[0035] The or each feedthrough tube may define a passageway for the sensor assembly. They may define together a common passageway, or a single feedthrough tube may provide both passageways.

[0036] The or each passageway may be funnel-like, as defined above.

[0037] In some embodiments, the flexibility of the sensor assembly, and any feedthrough tube through which it extends before entering the receptacle, is provided by the inherent flexibility of the materials used along the length of the sensor assembly, and any feedthrough tube through which it extends. This flexibility allows sufficient bending without breakage. In some embodiments, the materials comprise steel. In some embodiments, within the sensor assembly there is provided a ceramic or insulating material separating two conductors (for example for a thermocouple, for example made of steel) along the length of the sensor assembly that extends from the enclosure to the receptacle.

[0038] In some embodiments, the sensor assembly, once inserted, is fixed to the enclosure only at a portion of the sensor assembly that is located adjacent an outer skin of the thermal insulation layer or an outer wall of the enclosure. The length of the sensor assembly that extends inward from that portion can then slide in or out relative to the thermal insulation layer and the receptacle, and it can bend or flex for accommodating relative movement between the receptacle and the enclosure. In some embodiments, a lateral movement of the receptacle relative to the enclosure of tens of millimetres (up to around 20mm or 50mm) may need to be accommodated through flexure of the sensor assembly inside the enclosure.

[0039] In some embodiments, where more than one sensor assembly passes through the sidewall, for example each at a different respective location, which locations may be distributed or variously spaced along the enclosure, there can be different degrees of flex and movement freedom for some or each sensor assembly. For example, a shorter sensor assembly may need a wider angular degree of freedom than a longer sensor assembly. Similarly, a more distal sensor assembly (or a more distant sensor assembly from the fixed first part) may need a wider angular degree of freedom than a less distal (or less distant) sensor assembly as the amount of thermal expansion increases proportional to the length of the expanding component.

[0040] In some embodiments, there may be more than one branch from a manifold, and a sensor assembly is provided for each branch.

[0041] In some embodiments, the thermal insulation layer comprises at least an inner portion formed of a flexible or compliant material or fabric, such as wool or a mineral fibre, which material accommodates flex and movement of the sensor assembly. This removes the need for a funnellike passageway through the thermal insulation layer. The inner portion may be a portion of the thermal insulation layer that is closest to the centre of the enclosure (i.e., at lower radius or closer to the stack(s)). In some embodiments, the inner portion is about or at least 20mm thick. For a thermocouple, this is usually enough for achieving the desired flexibility of that inner portion to accommodate the flexibility and movement of the thermocouple, given the additional length therefor between the inner portion and the receptacle. For example, the prior art can provide thermocouples that can bend 20mm laterally over a 250-450mm length. This flexibility, and the size of any hole or opening in (or compliance of) the insulation and any inner skin, plus a distance between inner face of the insulation layer (or inner skin) and the receptacle / thermowell, enables a commercial sensor assembly or thermocouple to bend enough for accommodating the relative differences in thermal expansion without damage occurring to the sensor assembly or thermocouple or to the electrochemical cell apparatus.

[0042] In some embodiments, a slotted pipe is provided for use as an installation tool. It is used to penetrate the insulation, or to extend through the feedthrough tube, carrying an end portion of the sensor assembly at the slotted pipe's end. Once the sensor assembly has been inserted into the receptacle, the slotted pipe can be pulled back out of the enclosure, leaving the sensor assembly extending through the thermal insulation layer and into the receptacle. In some embodiments, the slotted pipe can be used to form a hole through the thermal insulation layer - created by the insertion thereof therethrough.

[0043] In some embodiments, the slotted pipe has a c-shaped cross section (i.e. it is not a complete circle) so that it can be removed from the sensor assembly, or from a wire at an outside end of the sensor assembly, once it is removed from the enclosure.

[0044] In some embodiments, there is a plurality of stacks.

[0045] In some embodiments, the plurality of stacks is arranged in one or more array of stacks. In some embodiments, the or each stack, or the one or more array of stacks, is mounted on the support structure within the enclosure such that it allows movement thereof along a longitudinal axis of the enclosure.

[0046] In some embodiments, the stacks may be connected to the removable lid of the enclosure by the manifold, and optionally one or more additional manifold, each for supplying fluids to or for exhausting fluids from the stacks, as well as electrical connectors.

[0047] In a typical solid oxide electrolyser apparatus, the temperature difference between the external wall of the enclosure and an internal operational temperature of the thermally insulated space is significant, and due to the coefficient of thermal expansion of the materials of the manifold, their lengths will vary considerably compared to that of the enclosure, between the time of assembly (room temperature - i.e. usually between 20 and 25 °C) and the time of normal operational use (around 550 °C for an SOEC, although operational temperatures for an intermediate temperature solid oxide electrolyser cell unit is typically anything between 400 and 700 °C). For example, if the manifold is 7m long, and if made of steel, that length of steel, when increased in temperature by 525 °C, will elongate by about 48mm. With the present invention, the sensor assembly, even if fitted into a receptacle at a branch of the manifold at the second end of the manifold, can be allowed to accommodate the expansion of the manifold (or a branch thereof) relative to the first part of the manifold as the apparatus heats up, and the contraction again as it cools down (e.g. at shut down) through the flexing and the movement of the sensor assembly.

[0048] In some embodiments, the manifolds and connections define an inlet manifold configured to provide fluid to each of said stacks and / or a product manifold configured to exhaust off-gas or product from each of said stacks. An inlet manifold for fuel may be defined. The fluid may be a fuel, which may be a combustible fluid if the electrochemical cell apparatus is operating in a power delivery mode, or a fluid for separation (e.g. one or more of water / steam, carbon dioxide and nitrogen dioxide) if operating instead in a regenerative mode. A second inlet manifold for sweep gas or oxidant (provided to an oxygen volume) may be provided. At least one product manifold, for off-gas from a fuel or oxygen volume of the stacks may be provided, in some embodiments separate product manifolds are provided for off-gas from the fuel and oxygen volumes respectively. Sensors may be needed for each manifold, and any branches therefrom.

[0049] In some embodiments, the stacks are configured as one or more arrays of stacks. Each array may have its own manifolds, channels, pipes and electrical connections, although a manifold and an electrical connection may instead connect with multiple arrays. In some embodiments a manifold is fluidically connected with multiple arrays (preferably all arrays) via branches that provide respective fluidic connections. Such fluidic connections may be of a flexible type.

[0050] In some embodiments, each array is one or more pair of stacks, arranged side by side, and multiple pairs may be spaced along the length of the enclosure, e.g. in rows. For example, each row may have one or more than one pairs of stacks, and there may be multiple rows.

[0051] In some embodiments, the electrochemical cell apparatus is an electrolyser apparatus. However, it may instead be a fuel cell apparatus. The electrochemical cell units may be electrolyser cell units, and they may be based on a solid oxide electrolyte and so are solid oxide electrolyser cells (SOEC). The electrolyser cell units may be metal-supported electrolyser cells (e.g., MS-SOEC), which aids stability of said cell units.

[0052] In some embodiments the electrochemical cell units operate at a target operational temperature in excess of 400 °C. In some embodiments, operational temperatures do not exceed 800 °C, or more preferably 700 °C. As such, normal operating temperatures will be in the range of 400 to 700 °C, or more preferably 450 to 650 °C. The temperatures referred to may be a temperature of the stack(s) - for example, the temperature of the product or off-gas (from the fuel or oxygen volumes of the stack(s)) may be used as the temperature of the stack(s) or the temperature of the stack(s) derived therefrom.

[0053] In some embodiments, the plurality of stacks are arranged in the enclosure in sets of at least 6 stacks, optionally at least 10 stacks, and optionally at least 20 stacks. For example, if supplied in pairs that are arranged side by side, the stacks may be arranged in an array of stacks that is two wide and in 3, 5 or 10 rows. In some embodiments they may instead be four wide. For example an array may feature a four wide, six row, set of stacks, and thus totalling 24 stacks. Instead there may be 2, 3, 4, 5 or 7 (or more) rows. Each stack and or each manifold for these stacks, or branches from those manifolds, may require sensor assemblies.

[0054] In some embodiments the enclosure is a pressure vessel.

[0055] Preferably, the enclosure is a pressure vessel configured to withstand a pressure difference between the inside of the pressure vessel and an ambient pressure surrounding the enclosure.

[0056] The present invention also provides a method of accommodating relative movements due to thermal expansion or thermal contraction within an electrochemical cell apparatus, the apparatus comprising: an enclosure; a stack of electrochemical cell units, the stack being contained within the enclosure; a manifold for supply of fluid to or exhaust of fluid from the stack, wherein the manifold is fixed relative to the enclosure at a first part of the manifold; a support structure for the manifold at a second part of the at least one manifold, the second part of the manifold being spaced from the first part of the manifold, wherein the support structure is configured to allow relative movement between said second part and the enclosure; a thermal insulation layer provided inside said enclosure; a thermally insulated space defined inside the thermal insulation layer, in which said stack and manifold are located; a sensor assembly which penetrates the enclosure and the thermal insulation layer; and a receptacle attached to or unitary with the manifold, the stack or a branch of the manifold; wherein the sensor assembly is fitted into the receptacle through a sidewall of the enclosure, and the sensor assembly is configured to be flexible and movable in a lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer, whereby upon movement of the second part of the manifold due to thermal expansion or contraction, relative movement between ends of the sensor assembly is accommodated by flexing and movement of the sensor assembly between the enclosure and the receptacle.

[0057] The apparatus of this method may be as defined above or below.

[0058] Particular and preferred aspects of the invention are set out in the accompanying independent claims. Combinations of features from the dependent claims may be combined with features of the independent claims as desired and appropriate and not merely as explicitly set out in the claims. The term "comprising" as used herein to specify the inclusion of components also includes examples in which no further components are present.

[0059] An enabling disclosure of the present invention, to one of ordinary skill in the art, is provided herein. Reference now will be made in detail to examples of the invention, one or more examples of which are set forth below. Each example is provided by way of explanation of the invention, and not limitation of the invention.

[0060] Brief Description of the Drawings

[0061] Features of the present invention will now be described in further detail, by way of various embodiments, and just by way of example, with reference to the accompanying drawings (which drawings are not to scale), in which:

[0062] Figs. 1 and 2 are simplified schematic views of an electrolyser apparatus;

[0063] Fig. 3 is a simplified control device for controlling an electrolyser apparatus;

[0064] Figs. 4 and 5 are side elevation and top plan, cut-away schematic views of an electrochemical cell apparatus;

[0065] Fig. 6 is a side elevation, cut-away schematic view of an alternative electrochemical cell apparatus;

[0066] Fig. 7 shows a temperature sensor installed through a sidewall of an electrochemical cell apparatus;

[0067] Fig. 8 is a radially outward facing schematic view of the inner skin along the longitudinal axis of the sensor assembly;

[0068] Fig. 9 is an alternative embodiment, similar to Figure 7, in which an innermost region of the thermal insulation layer is formed of a soft or compliant fabric; and Fig. 10 is an alternative embodiment, similar to Figure 7, in which a funnel-like (or tapering) passageway is formed through the thermal insulation layer.

[0069] Detailed Description

[0070] In the following figures and description, like reference numerals will be used for like elements in different figures.

[0071] In the following description, the electrochemical cell apparatus of each embodiment will be described as if it is an electrolyser apparatus (which could be a reversible fuel cell operating in a regenerative mode), for ease of reference. However, it is to be appreciated that the electrochemical cell apparatus could also be configured as a fuel cell apparatus operating in a power delivery mode, as both forms of system will require temperature sensors.

[0072] Fig. 1 is a simplified schematic of an electrolyser apparatus 100 including a plurality of electrolyser stacks 10 in an enclosure 105. The enclosure 105 may be a pressure vessel 105 configured to withstand a pressure difference between its interior and exterior.

[0073] An array 110 of four stacks 10 is shown in Fig. 1, but it will be understood that any number of stacks 10 may be present, including fewer and greater than four, for example 1, 2, 10, 12 and so forth.

[0074] Each stack 10 comprises a stack of electrolyser cell units. A typical stack may have 100 to 500 electrolyser cell units.

[0075] The electrolyser cell units each comprise a first fluid volume (for a first fluid - typically fuel for the electrolysis process - e.g. at least one of steam, carbon dioxide and nitrogen dioxide) and a second fluid volume (for a second fluid - typically oxygen as a product of the electrolysis process), which fluid volumes are fluidically separated from one another such that the first and second fluids therein cannot mix.

[0076] Each stack 10 has a first fluid inlet 115 and a first fluid outlet 116, each of which is in fluidic communication with the first fluid volumes of each electrolyser cell unit 10. Supply of the first fluid to the first fluid volume is via the first fluid inlet 115 and exhaust from the first fluid volume is by the first fluid outlet 116. The first fluid is provided to the first fluid volume of the stacks 10 from a first fluid source 143 via the respective first fluid inlets 115 of the stacks 10.

[0077] In the example of Fig. 1, the first fluid is fully manifolded within the apparatus. That is, there is a manifold enclosing the fluid within the apparatus and providing fluidic communication between the first fluid source 143, external to the enclosure 105, and the first fluid inlets 115 of the stacks 10. Likewise, there is a manifold providing fluidic communication between the first fluid outlets 116 of the stacks 10 and a first fluid volume off-gas collection 163, external to the enclosure 105.

[0078] Each stack 10 may have a second fluid inlet 122 and a second fluid outlet 123, which, where present, is in fluidic communication with the second fluid volume of each cell unit 10. Exhaust from the second fluid volume is by the second fluid outlet 123, and an optional supply of a second fluid to the second fluid volume is via the optional second fluid inlet 122. The optional second fluid is provided, in this example, as a sweep flow gas to the second fluid volume of the stacks 10 from a second fluid source 144 via respective second fluid inlets 122 to assist in sweeping product (e.g. oxygen) from the cell units.

[0079] In the example of Fig. 1, the second fluid is open manifolded within the apparatus. That is, there is a vessel inlet 120 to the enclosure 105 for delivery of the second fluid to the interior of the enclosure 105 from the second fluid source 144, but there is no branched manifold to deliver the second fluid to respective second fluid inlets 122 of each stack 110.

[0080] Exhaust from the second fluid volume of the stacks 110 is also open manifolded. That is, there is a vessel exhaust 121 from the enclosure 105 for exhaust of second fluid volume off-gas from the interior of the enclosure 105 to the second fluid off-gas collection 164 - in this example the offgas or product, mixed with the second fluid, but there is no branched manifold between the respective second fluid outlets 123 of each stack 110 and the vessel exhaust 121.

[0081] In some cases the second fluid may be partially manifolded within the enclosure - i.e. there may exist a manifold between the vessel inlet 120 and the respective second fluid inlets 122 of the stacks 110, or there may exist a manifold between the respective second fluid outlets 123 of the stacks 110 and the vessel exhaust 121.

[0082] In some cases both the inlet and exhaust of the second fluid may be manifolded, as depicted in Fig. 2, to ensure that any second fluid (herein in this example a sweep gas) that is supplied to the second fluid volume is effective at sweeping through the cell units, such that the product / off-gas released into the second fluid volume can then be removed therefrom. This will occur particularly during start up, shut down and standby modes.

[0083] Each of the inlets and outlets, each of the fluid volumes and each of the manifolds, exhausts and mechanisms for providing fluidic communications, may require temperature sensors, which temperature sensors may be connected to a control system of the apparatus.

[0084] In Fig. 2 the electrolyser apparatus 101, which is otherwise similar to the electrolyser apparatus 100 of Fig. 1, includes inlet and exhaust manifolds for the second fluid which communicate with the second fluid source 144 and second fluid collection 164, respectively. Further, electrolyser apparatus 101 has a vessel inlet 120 and a vessel exhaust 121 for a vessel fluid supplied to a common volume 24 of the enclosure 105, that contains the stacks 10, from a common volume supply 165.

[0085] Optionally the vessel fluid can be supplied via a heater 152. Heaters may optionally also be provided for the first and second fluids supplied from the first and second fluid sources 143, 144.

[0086] The vessel fluid may thereafter be exhausted from the common volume to a common volume collection 166 through the vessel exhaust 121. As such, in this embodiment the common volume of the enclosure 105 is in fluid communication with neither the first nor the second fluid volumes. When the stacks are operated at elevated pressures, the vessel fluid in the common volume may be regulated to balance the pressure in the common volume with the pressure in the first and / or second fluid volumes. Similarly, the pressures may be balanced between the first and second fluid volumes.

[0087] As with the previous embodiment, each of the inlets and outlets, each of the fluid volumes and each of the manifolds and mechanisms for providing fluidic communication, may require temperature sensors, which temperature sensors may be connected to a control system of the apparatus. Similarly, they may require pressure sensors, again connected to a control system of the apparatus. With the output signals from these sensors (temperature and / or pressure), the control system can properly monitor and control the system.

[0088] The vessel fluid may be a relatively inert gas to avoid corrosion of the components within the enclosure, and to minimized the possibility of a reaction between the vessel fluid and any leakage of product (e.g. hydrogen, carbon monoxide, nitrogen or oxygen) or first and second fluids from the manifolded passages elsewhere within the enclosure. For example, the vessel fluid may be air or nitrogen.

[0089] It will be appreciated that it is sometimes preferable for the second fluid to be open manifolded, as in Fig. 1, or partially manifolded as discussed above, such that there exists fluidic communication between the second fluid volume of the stacks and the interior of the enclosure 105 for pressure equalisation therebetween - in turn simplifying control strategies and pipework required for the respective fluids.

[0090] It will be understood that similar partial or fully manifolded arrangements to those shown schematically in Figs. 1 and 2 are known in the art, albeit not with the stacks being provided in an enclosure.

[0091] In the examples of Figs. 1 and 2, the first fluid volume is typically a fuel volume and, during steady operation, is for fuel - usually steam and / or carbon dioxide, but possibly other compounds for electrolysing, such as nitrogen dioxide. In cases where the electrolyser cell units in the stacks 10 comprise an oxygen ion conducting electrolyte (e.g., solid oxide electrolyte cell units), the first fluid volume off-gas exhausted to the first fluid off-gas collection 163 comprises hydrogen and / or carbon monoxide and / or nitrogen monoxide (dependent on the fuel used). This off-gas is generated in the electrolysis reaction, and is mixed with unspent fuel in the off-gas. The second fluid volume off-gas exhausted to the second fluid off-gas collection 164 instead comprises oxygen that is generated in the electrolysis reaction. The second fluid off-gas may be pure oxygen or oxygen enriched sweep gas if mixed with a sweep gas.

[0092] The second fluid volume off-gas is preferably controlled through selective use of a sweep gas such that it may comprise at least 50% by weight of oxygen generated by the cell units. In some embodiments, the second fluid volume off-gas 164 may be substantially pure oxygen, if purely the product of the electrolysis process, although it might more normally be oxygen enriched air or nitrogen if a sweep gas (air or nitrogen) is also being used. Ideally, however, the oxygen is at least 90% (by weight) pure oxygen when the apparatus 20 is operating at a steady state operation, as the present invention is ideally operated without an externally sourced sweep gas. In such a configuration the stacks are just supplied the first fluid, i.e. one fluid to the first fluid input 115 for each stack 10.

[0093] Other than the fluid inlet(s) and outlets, the stack / electrolyser / vessel will have inputs (terminals, not shown) for power (for applying a current across the electrolyser cell units in the stacks 110).

[0094] Operationally, a stack will usually want to avoid large pressure differentials across the cell units, so a threshold pressure differential between the first and second fluid volumes can be set appropriately, or the first fluid volume's pressure (on a first side of each cell unit) can be controlled to balance the pressures across the cell units. In one example, the pressure differential can be controlled (and is kept as small as possible) by use of a common regulator apparatus across or between the two sides of the cell units (the anode side and the cathode side). However, in operation it is sometimes advantageous to control the pressure differential to be positive on the second fluid volume's side to ensure that any oxygen leaks leak into the fuel side, rather than the other way around, which could instead be hydrogen leaking to the oxygen side. This is better for the stack's operational lifetime as there will be less degradation of the electrochemically active layers of the cell units, and less opportunity for an abrupt failure of the cell unit due to combustion of the hydrogen with the oxygen.

[0095] The electrolyser apparatus 100 typically operates at an elevated temperature, for example 400- 700 °C for cell units based on a solid oxide electrolyte. It will be appreciated that heat in the first fluid off-gas and the second fluid off-gas will typically be exchanged with (transferred to) the first fluid and, if present, second fluid prior to their delivery to the stacks 10, typically prior to their entry into the enclosure 205 using one or more heat exchangers (but typically two or more heat exchangers such that heat is recovered from the first fluid volume off-gas and the second fluid volume off-gas). In steady state operation said heat exchange may be sufficient to maintain an operating temperature of the electrolyser apparatus 100 when practiced alongside electrical temperature control by varying a power level applied to the electrolyser cell units. Heaters 150 and / or 151 (e.g., an electric heater and / or a trim heater) may be provided in an input stream of the first and / or second fluid, respectively, to provide additional heat to said fluids and for providing additional heat control flexibility within the apparatus. Said heaters may be sized for steady state requirements only, or may also be used for other operational modes, e.g. warm-up or standby.

[0096] In steady state operation, the first and second fluid volume off-gases will usually be at a similar temperature to the operational temperature of the electrolyser cell units. However, a specific delta from the input temperature will depend upon the amount of electrical power supplied to the electrolyser apparatus / stacks / cell units, and the internal resistance of the cell units.

[0097] The electrical power is generally supplied to the stacks with a constant current. The stack is thus operated in galvanostatic conditions. The electrical resistance of the stack thus controls the voltage applied across the stack, and there is thus a variable power draw from each stack and cell unit as the resistance changes. Alternatively the power supplied to the stacks is controlled potentiostatically. In addition to temperature and pressure sensors, it is possible that electrical power, current or voltage sensors may be provided within the apparatus to check circuit continuity or power levels, or voltage and / or current levels, within the system, again to allow the control system to properly monitor and control the system.

[0098] Operational efficiency can be best improved by reducing the amount of external heat supplied to the apparatus via its fluid temperature control apparatus - i.e. via the heaters. Where that external heat is provided for free - for example as a waste product of another industrial process, then that external heat can be usefully used without cost - i.e. it provides added financial efficiencies. However, if that external heat has an associated cost, then operational efficiencies would be better improved instead by reducing the need for such external heating. At steady state this is achieved by using both galvanostatic conditions within the stacks, i.e. a constant electrical current (constant amps), and by adopting thermoneutral voltages across the stack to avoid heat wastage in the stacks, as at a thermoneutral condition the electrolyser is in an adiabatic state, i.e. it is balanced energetically, which effectively means no heat is consumed or released.

[0099] In the prior art, it is known to use either constant voltages or constant currents on a stack, and then to control the current or the voltage, respectively, to maintain the stack at a substantially thermoneutral condition. This then allows the stack to avoid overcooling or overheating, as when at under-voltage (for a galvanostatic stack - i.e. constant current), the stack shows endothermic characteristics, and it thus cools the fluid (and likewise the operational temperature of the stack), whereby the fluid output temperature is lower than the fluid input temperature, whereas when at over-voltage (for a galvanostatic stack - i.e. constant current), the stack shows exothermic characteristics, and it thus heats the fluid (and likewise the operational temperature of the stack), whereby the fluid output temperature is higher than the fluid input temperature.

[0100] At steady state, the present invention may use a galvanostatic condition for the stack, but fluctuates as necessary between thermoneutral conditions, over-voltage conditions and undervoltage conditions, in response to input fluid temperature control that aims to maintain a fluid input temperature equal to a fluid output temperature. This is done since the present inventors realised that it is relatively straightforward to measure temperature at an inlet and an outlet of the stack and thus to instead control the thermoneutral voltage automatically. In other words, at steady state the temperature delta between the fluid output temperature from the stack and the fluid input temperature for the stack is minimised, aiming for a zero delta. This then allows extended use of a galvanostatic condition for the stack, alongside a thermoneutral voltage condition, even while the stack, or one or more of the cell units therein, degrades.

[0101] Galvanostatic and thermoneutral (and galvanostatic thermoneutral) conditions such as those discussed above apply in steady state when the electrolyser apparatus is at an operational temperature. Other steady state conditions or operating strategies, such as potentiostatic, endothermic or exothermic may also be used depending upon characteristics of the cell units and / or of input and exhaust fluids available or desired, respectively.

[0102] Other strategies are required in order to raise the electrolyser apparatus to the operational temperature. Further, in cases where the heaters 150 and / or 151 are present, they may only have the capacity for a provision of trim heating at operational temperatures, e.g. to raise the heat of the input stream by 10-40 °C. Such heaters are unable to provide sufficient heat to the electrolyser apparatus to warm the same from ambient to operational temperatures in a reasonable timeframe. However, provision of larger capacity heaters for the two heaters 150 and / or 151, to provide warm up heat, would result in oversized heaters for steady state operation, and thus unnecessary capex costs. Nonetheless, in each of the examples subsequently discussed, the heaters 150 and / or 151 - if in the form of trim heaters - may be used to assist warm up of the apparatus when efficient to do so.

[0103] The abovementioned steady state operation is one mode of operation of an electrolyser apparatus. Other modes of operation, including warm up, standby, and shutdown may be used with transitions therebetween. The electrolyser apparatus may transition to a standby mode from a steady state (also referred to as a product-generating mode) or a warm up mode. As used herein, reference to supply / supplying or provide / providing to a volume also involves exhaust from that volume unless the context requires otherwise.

[0104] Referring next to Fig. 3, there is shown a control device 400 for controlling an electrolyser cell stack of an electrolyser in an electrolyser apparatus. The control device 400 comprises an input device 402 for receiving input from sensors 404 so as to determine at least one of: a stack operating voltage across the electrolyser stack(s), an inlet temperature at a fluid inlet, an outlet temperature at a fluid outlet and a common volume temperature. The control device 400 thus comprises a voltage monitoring system 406 for determining a stack operating voltage across the electrolyser stack(s), an inlet temperature monitoring and / or control system 408 for determining an inlet temperature at the fluid inlet and an outlet temperature monitoring and / or control system 410 for determining an outlet temperature at the at least one fluid outlet of the electrolyser stack(s). These systems may utilize sensors and data transmission devices or wiring. The control device receives sensor data relating to each of these measurements. The control device may control the electrolyser apparatus by controlling valves for supply to and exhaust from each fluid volume and power supplies for non-fluid heating. A suitably programmed processor 412 and associated memory 414 is provided for processing such inputs.

[0105] The control device's inlet temperature monitoring and / or control system 408 may comprise an output device for controlling the identity and temperature of a fluid entering the electrolyser stack(s) at a fluid inlet. A current control system 416 is also provided for controlling a current supply to (and in some cases from) the electrolyser stack. As mentioned above, during normal operation this is adapted to provide a constant current to the electrolyser cell stack, but the current / voltage may be reduced or turned off to automatically shut down the stack or increased to warm-up the electrolyser stack(s).

[0106] The controller may also control non-fluid heat sources (heaters and such like described above), recirculation loops, and temporary warm up configurations as described above.

[0107] In such a way, the controller 400 is adapted to control an electrolyser stack(s) and the electrolyser apparatus 100 - for example that shown in any of Figures 1, 2, or 4 to 10 as appended hereto. Referring next to Figs. 4 and 5, an example of an electrochemical cell apparatus in the form of an electrolyser apparatus 200 is shown. In this embodiment, the electrolyser apparatus 200 comprises an electrolyser assembly 12 within an enclosure 14, which enclosure 14 has an inner thermal insulation layer 16 on its inside wall. The thermal insulation layer 16 covers an inner sidewall and inner end wall of the enclosure 14.

[0108] The enclosure 14 has an opening at its end that opposes the inner end wall, which opening is closed by a removable lid 18. The removable lid 18 is also thermally insulated by an insulation layer 20.

[0109] The electrolyser apparatus 200 comprises a plurality of stacks 10 of electrolyser cell units mounted on a support bed 22 within a common volume 24 inside the enclosure 14. The support bed 22 has a first support leg 26 and a second support leg 28. The first support leg 26 supports and fixes the support bed 22 to the enclosure 14 at a first position. The second support leg 28 supports the support bed 22 within the enclosure at a second position, spaced along a length of the enclosure 14 from the first position, in a manner such that the support bed 22, via its second support leg 28, can articulate relative to the enclosure 14. This second support leg 28 is thus not a fixed mounting. Instead, it has hinges 50 or pivoting / flexible connections for permitting movement of the support bed 22 relative to the enclosure 14. In this example, the second support leg 28 has a pivot arm 30 mounted between two parallel hinge axes 50, which hinge axes extend perpendicular to a longitudinal length of the enclosure, such that the pivot arm 30 can rotate relative to both the enclosure 14 and the support bed 22, thus allowing the articulation of the support bed 22 relative to the enclosure 14. Other forms of articulating joint can also instead be used.

[0110] Connecting between stacks 10, there is also provided a manifold 32 for providing fluidic connection to the stacks 10, via the removable lid 18, to the outside of the enclosure 14. In this example, the manifold 32 is shown to connect to the removable lid 18. Connections beyond that connection to external fluid subsystems can be as known in the art.

[0111] As shown in figure 5, the manifold 32 also connects to the stacks 10 via links or branches 36. Such branches 36 can be any form of fluidic and / or electrical connection as well known in the art. The branches 36 are typically flexible connections to allow relative movement to occur between the manifolds and the stacks, as may occur due to the variable temperatures within the electrolyser apparatus 200, and the different materials used within the electrolyser apparatus 200.

[0112] The connection of the manifold 32 to the removable lid 18 provides support for the manifold 32 relative to the removable lid 18 such that the manifold is 32 fixed to the removable lid 18 in a first location - at a first end 38 of the enclosure 14. The other end 40 of the manifold 32 is instead supported, and articulated relative to the enclosure at a second location within the enclosure, distal from the first end of the enclosure, by a support frame 34. As with the support bed 22, this articulated connection allows relative movement between the manifold 32 and the enclosure 14 - and between the manifold 32 and the support bed 22. This can be via a pivotable or flexible connection. For example, as shown in figure 6, a pivoted support frame 34 can be provided. As shown in figure 6, this pivoted support frame 34 provides hinged connections 42 between the manifold 32 (in this case formed of three separate manifolds 44, 46, 48, each designating a different fluid manifold) and the support frame 34 and between the support frame 34 and the support bed 22. In other embodiments, a flexible frame may be provided, whereby the frame itself can flex. In other embodiments, the frame may connect directly to the enclosure 14 (and be articulated thereto), rather than to the support bed 22. Three manifolds 44, 46, 48 are shown in figure 6. The manifolds are provided between the enclosure (inner face of the insulation) and the stacks 10. In this example, one set of three manifolds 44, 46, 48 is fluidically coupled to the stacks along one side of the central axis and a second set of three manifolds is fluidically coupled to the stacks along the other side of the central axis, but it need not be the case that there are multiple sets of manifolds - there may be only one set along one side of the central axis or indeed the set(s) may be along the central axis, inbetween rows of stacks. It will be understood that each set of manifolds may communicate with more than one stack, if, for example, there are four stacks provided across the width of the enclosure (e.g., a 4 by 4 arrangement rather than the 2 by 4 arrangement shown in figure 6). It will also be understood that three manifolds are exemplary, other numbers of manifolds (e.g., 1, 2, 3, or 4, preferably at least 3) may be provided depending upon the level of internal manifolding required (as discussed with reference to figures 1 and 2).

[0113] Because of the thermal insulation layers 16, 20, an outer wall of the enclosure 14 is maintained at a lower temperature than an inside volume of the enclosure 14 (i.e. the common volume 24) during operational use of the electrolyser apparatus 100. During that operational use, the stacks 10, and thus the common volume 24, may be operating at a temperature of around 550 °C, whereas the outer wall of the enclosure 14 may be at a temperature only slightly elevated above ambient temperatures - for example at a temperature below 60 °C. Given these temperature differences, and the coefficient of thermal expansion of the various materials used in the apparatus 100, there can be a significant relative movement between the end of the manifold 32 (distal from the lid 18) and the second location in the enclosure (and / or the end of the support bed 22 at the second location). As one end of each of the support bed 22 and the manifold 32 is fixed - to the enclosure 14 or the removable lid 18, the other ends thereof expand away from that fixed end. However, as the enclosure's external wall is not changing temperature to the same extent as the common volume 24 (including the manifolds 32 and the support bed 22), the enclosure 14 does not expand to the same extent as the manifold 32 and the support bed 22. Likewise, during use the manifolds and support bed may experience different temperatures, for example during warm up or shut down when fluids transported through the manifolds may be used to raise or lower the temperature of the apparatus. As a result, the manifolds and support expand by different amounts. The articulated connections for each of the manifold 32 and the support bed 22 thus permit the relative movements to be accommodated within the enclosure 14.

[0114] Referring next to Figure 5, it can be seen that the stacks 10 are arranged in pairs and in lines along the inside of the enclosure 14. This forms an array - 2 by 4 - of stacks within the common volume 24. Other embodiments may have fewer or more rows and columns of stacks.

[0115] Each stack 10 is connected by a link or branch 36 to a manifold 32. In this embodiment there are manifolds down both sides of the array. Referring next to Figure 6, there are multiple manifolds 44, 46, 48 down both sides of the array, each manifold 44, 46, 48 being similar to manifold 32. For example, there can be a fluid input manifold 44 for feeding fuel to the (fuel volume of the) stacks 10, an oxygen volume off-gas line 46 for removing oxygen volume off-gas from the oxygen volume of each of the stacks and a fuel volume off-gas manifold 48 for removing fuel volume offgas from the fuel volume of each of the stacks. Multiple stacks can be connected to the same manifold, or separate manifolds for each stack can be provided, although it is simpler to have one manifold connecting with multiple stacks.

[0116] In some embodiments the stacks are mounted directly onto the support bed. In other embodiments the or each stack is mounted onto the support bed by a sled. For example, the stacks 10 may be fixed to and supported by the sled on the support bed. The sled can be configured to sit on the support bed, or one of the support beds if more than one is provided. In some embodiments the sled is configured to be movable relative to the or each support bed - for example it may slide or glide relative thereto. In some embodiments the sled or support bed comprises a plurality of rollers configured to allow lateral movement of at least part of said sled, and the stacks thereon, within said enclosure. This is to allow relative movement between the sled (and the stacks thereon) and the or each support bed, for example in a direction between the first end and the second end of the enclosure.

[0117] In these embodiments the enclosure is shown in a horizontal configuration so that the opening is to a side of the enclosure and the electrolyser assembly is inserted in and out of the enclosure 14 in a horizontal direction. It is possible, however, for the enclosure and the electrolyser assembly to be instead configured for vertical insertion of the electrolyser assembly in and out of the enclosure.

[0118] Referring next to Figure 7, an embodiment of the present invention is shown, in which a electrochemical cell apparatus 100 (in this example an electrolyser apparatus) comprises a single line of stacks 10 of cell units within an enclosure 14, the enclosure 14, as per the previous examples, extending lengthwise parallel to a longitudinal axis.

[0119] During start-up, for example, of the electrochemical cell apparatus, there will be a significant change of temperature within the enclosure 14, as previously discussed. This change of temperature will cause movement of the stacks 10 within the enclosure 14 as the manifolds 32 and the support bed 22 will all expand in size.

[0120] Referring next to Figure 7, and embodiment of the present invention is shown. This embodiment can be implemented for any or each manifold 32, stack 10 or branch 36 discussed above.

[0121] As shown in Figure 7, this embodiment illustrates a single stack 10 within an enclosure 14, with a manifold 32 for providing fluids to (or exhaust from) the stack via a branch 36. Although only a single stack 10 is shown, as per the previous embodiments it is possible to have more than one stack 10 within the enclosure 14, for example an array of stacks 10. The stacks 10 can all be mounted on the support bed 22 (optionally via a sled), as per the previous embodiments.

[0122] This embodiment also has a pair of support legs 26, 28 (only one visible) for supporting the support bed 22. This may be as previously described for the previous embodiments. The enclosure 14 in this embodiment also comprises a thermal insulation layer 16, which as per the previous embodiments is inside an outside wall 68 of the enclosure 14. In this embodiment, however, there is also an inner skin 58 inside the thermal insulation layer 16. The thermal insulation 16 and the inner skin 58 together define the common volume 24 within which the stack or stacks 10 are positioned, although the enclosure defines a fluidic boundary of the common volume 24 given that it fluidically seals that common volume to maintain elevated pressures therein.

[0123] Since it will be desirable to use a sensor to determine various parameters within the enclosure 14, such as the temperature of the fluids entering the stack 10, the temperature of the fluids exiting the stack 10, pressures within the enclosure 14 and the stack 10, and power usage or current / voltage across the stack 10, in this embodiment a mechanism for installing and allowing servicing of sensors for the electrochemical cell apparatus is shown.

[0124] In this embodiment, attached to a side of the branch 36 is provided a receptacle 62, which in this embodiment is a thermowell for receiving a temperature sensor. The receptacle 62 comprises a cup like opening into which an end of a sensor assembly 60 (in this embodiment comprising a temperature sensor) can be inserted for correctly positioning that end of the sensor assembly 60 relative to the branch 64 for taking sensor readings from the branch 64, such as temperature readings in this embodiment. It is to appreciated, however, that alternative receptacles may be instead provided for pressure sensors, power sensors, or current or voltage sensors.

[0125] In figure 7, the inserted sensor assembly 60 is shown inserted into the receptacle (thermowell) 62. Surrounding of that sensor assembly 60, however, is a feedthrough tube 66, which extends through the outside wall 68, the thermal insulation layer 16 and the inner skin 58 of the enclosure 14 and extends down through to the receptacle 62 to provide a guide path for insertion of the sensor assembly 60 into the receptacle 62. The feedthrough tube is sealed to the outside wall 68 and the sensor assembly is fluidically sealed to the feedthrough tube to fluidically seal the opening through the outside wall 68 (i.e. to maintain a fluid and a pressure thereof within the volume).

[0126] In this embodiment, the sensor assembly 60 and the feedthrough tube 66 are made to be flexible. By being flexible, it is possible to move the end of the sensor assembly 60 that is within the receptacle 62 laterally with respect to the longitudinal axis of the sensor assembly when straight. As a result, despite inevitable movement of the stack 10, the manifold 32 and the branch 36 relative to the outside wall 68 of the enclosure 14 due to thermal expansion and contraction as the common volume 24, the stack 10, the branch 36 and the manifold 32 heat up from a start-up temperature towards and into an operational temperature, flexure of the feedthrough tube 66 and the sensor assembly 60 accommodates that inevitable relative movement.

[0127] In some circumstances, the distance between the receptacle 62 and the inner skin 58 of the enclosure 14 will be sufficiently long that merely the flexibility of the sensor assembly 60 and the feedthrough tube 66 is enough to accommodate that inevitable relative movement. However, due to the cost of heating up the common volume 24, it is generally the case that the size of the common volume 24 will want to be kept relatively small, and thus the distance between the receptacle 62 and the inner skin 58 of the enclosure 14 can be relatively short. See, for example, figure 5 where the distance in the right-hand (top) half is shorter than that of the left-hand (bottom) half, but the distances may alternatively be substantially equal. Relying, therefore, on the flexibility of the sensor assembly 60 and the feedthrough tube 66 can thus then require significant degrees of bending to be required by both the sensor assembly 60 and the feedthrough tube 66 in order for that inevitable relative movement to be accommodated. This can be enough. However, the inventors have realised that many sensor assemblies 60, and some feedthrough tubes 66, that are designed to operate at the elevated temperatures of a solid oxide electrolyser, i.e. above 400° C, may struggle to have the necessary degree of flexibility. According to the present invention, therefore, the feedthrough tube 66 can be sized to be larger than the sensor assembly 60 so as to accommodate additional lateral movement of the sensor assembly 60 therein. In addition, some flex within the thermal insulation layer can also be accommodated in some embodiments, thus enabling the invention to accommodate additional relative movement.

[0128] Referring next to Figure 8, which is a radially outward facing schematic view of the inner skin along the longitudinal axis of the sensor assembly, in this embodiment the inner skin 58 where it surrounds the feedthrough tube 66 is provided with an elongated, enlarged or elliptical hole 74 through which the sensor assembly 60 extends, and in this embodiment the feedthrough tube 66 too, although that is optional - for example if the feedthrough tube fixes against an inside surface of the inner skin. Due to the elongated shape of this hole 74, additional lateral movement of the sensor assembly 60 and the feedthrough tube 66 within the inner skin 58 is possible, whereby they can flex relative to the hole, and thus also within the thermal insulation layer (visible through the hole 74, which is itself preferred to have some flexibility as well - see the discussion below in respect of Figure 9). In this embodiment, the feedthrough tube can flex within the thermal insulation layer as it is not retained in a fixed position by the inner skin 58. Four moved positions 76 are shown in broken lines, and the starting position is shown in solid lines.

[0129] Instead of an elliptical shape, the hole may be an elongated rectangle, a slot, a circle, or any other desired shape that is larger than, and that thus allows lateral movement of, the feedthrough tube (when provided) or the sensor assembly (when the feedthrough tube is not provided).

[0130] It is preferred that the longer length of the hole extends generally parallel to the longitudinal axis of the enclosure 14 as that is the predominant direction of expansion for the manifold as it heats up. The initial position at one end of the hole may be the position at ambient temperature.

[0131] Referring next to Figure 9, another embodiment is shown, in which there is no feedthrough tube (although one can be included if desired, as it can help guide a sensor assembly into the receptacle when fitting a sensor assembly). In this embodiment, an innermost region 70 of the thermal insulation layer 16 (for example a region that is 20mm thick, although other thicknesses are possible) can be formed of a soft or compliant fabric to allow lateral movement of the sensor assembly's 16 extending therethrough to simply move the compliant material along with the sensor assembly. This enables a longer length of the sensor assembly to flex laterally, and thus reduces the amount of bending at any one point. The compliant fabric may be wool or a mineral fibre material, for example a silicate and / or glass fibre wool. The thermal insulation may be compliant through a majority of or entirety of its depth, and may comprise layers of differing composition. In this embodiment, the inner skin is not present, although an inner skin 58 can be provided, inside the innermost region, with a suitable hole therein for allowing lateral flexing of the sensor assembly 60.

[0132] In this case, the sensor assembly is fluidically sealed to the outside wall 68 to fluidically seal the opening through the outside wall 68 (i.e. to maintain a fluid and a pressure thereof within the volume).

[0133] In this embodiment, a slotted pipe may be provided for use as an installation tool. It is used to drive the sensor assembly 60 through the thermal insulation layer 16, and the innermost region 70 thereof, and to thus carry an end portion of the sensor assembly 60, located at the slotted pipe's end, through to the receptacle 62. Once the sensor assembly 60 has been inserted into the receptacle 62, the slotted pipe can be pulled back out of the enclosure 14, leaving the sensor assembly 60 extending through the thermal insulation layer 16 and into the receptacle 62. Although the slotted pipe can be used to form a hole through the thermal insulation layer - created by the insertion thereof therethrough - it is also possible instead for a hole to be preformed therein for the insertion tool, or for the sensor assembly without an insertion tool.

[0134] The slotted pipe may have a c-shaped cross section (i.e. it is not a complete circle) so that it can be removed from the sensor assembly, or from a wire at an outside end of the sensor assembly, once the slotted pipe is removed from the enclosure.

[0135] Referring next to Figure 10, another embodiment is shown in which a funnel-like (or tapering) passageway 72 is formed through the thermal insulation layer 16, with a narrow end at the outside wall 68 and a wider end facing towards the receptacle 62. In this embodiment, again the inner skin is omitted, but if provided the wider end of the passageway 72 would extend to or through a suitably sized or shaped hole in the inner skin 58, such as that shown in figure 8, or as discussed above, to allow lateral flexing of the sensor assembly 60 within the funnel-like passageway 72.

[0136] It is to be noted, therefore, that the inner skin 58 is optional, as per the previous embodiments of figures 9 and 10, and 4, 5 and 6. Furthermore, any one or more of the funnel-like passageway 72, the softer compliant portion 70 for the thermal insulation layer 16 or the oversized feedthrough tube 66 can be utilized individually or in unison to enhance the available lateral flexibility of the sensor assembly 64, for thus accommodating the inevitable lateral movement of the receptacle 62 relative to the outside wall 68 of the enclosure 14.

[0137] The present invention has therefore been described above by way of example. However, the present invention is not limited to only the above examples. Other examples will be readily apparent to one of ordinary skill in the art without departing from the scope of the appended claims.

[0138] These and other features of the present invention have been described above purely by way of example. Modifications in detail may be made to the invention within the scope of the claims.

Claims

CLAIMS1. An electrochemical cell apparatus comprising: an enclosure; a stack of electrochemical cell units, the stack being contained within the enclosure; a manifold for supply of fluid to or exhaust of fluid from the stack, wherein the manifold is fixed relative to the enclosure at a first part of the manifold; a support structure for the manifold at a second part of the manifold, the second part of the manifold being spaced from the first part of the manifold, wherein the support structure is configured to allow relative movement between said second part and the enclosure; a thermal insulation layer provided inside said enclosure; a thermally insulated space defined inside the thermal insulation layer, in which said stack and manifold are located; a sensor assembly which penetrates the enclosure and the thermal insulation layer; and a receptacle attached to or unitary with the manifold, the stack or a branch of the manifold; wherein the sensor assembly is fitted into the receptacle and the sensor assembly is configured to be flexible and movable in a lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer.

2. The electrochemical cell apparatus of claim 1, wherein the sensor assembly comprises a temperature sensor.

3. The electrochemical cell apparatus of claim 1 or claim 2, wherein the receptacle is a thermowell.

4. The electrochemical cell apparatus of claim 3, wherein the thermowell is attached to the manifold or a branch therefrom and the manifold is an inlet manifold for supply of a fluid to the stack, or an exhaust manifold for exhausting off-gas from the stack.

5. The electrochemical cell apparatus of any one of the preceding claims, wherein the first part of the manifold is at a first end of the enclosure.

6. The electrochemical cell apparatus of any one of the preceding claims, wherein the second part of the manifold is at or adjacent to a second end of the enclosure.

7. The electrochemical cell apparatus of any one of claims 1 to 5, wherein the second part of the manifold is at a central region of the enclosure.

8. The electrochemical cell apparatus of any one of the preceding claims, wherein the sensor assembly penetrates the enclosure and the thermal insulation at a sidewall location of the enclosure.

9. The electrochemical cell apparatus of any one of the preceding claims, wherein the sensor assembly is configured to be flexible and movable within the thermal insulation layer in the lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer.

10. The electrochemical cell apparatus of any one of the preceding claims, wherein there is more than one sensor assembly, each sensor assembly extending through respective sidewall locations of the enclosure.

11. The electrochemical cell apparatus of claim 10, wherein all other connections for the stack that extend out of the enclosure, but excluding any branches from the stack, extend through an end of the enclosure.

12. The electrochemical cell apparatus of any one of the preceding claims, wherein an inner skin is provided on an inside of the thermal insulation layer, and the sensor assembly additionally penetrates the inner skin.

13. The electrochemical cell apparatus of claim 12, wherein an elongated, enlarged, rectangular or elliptical hole is provided in the inner skin for the sensor assembly to pass through, the sensor assembly.

14. The electrochemical cell apparatus of claim 13, wherein the longer direction is substantially parallel to the longitudinal axis of the manifold.

15. The electrochemical cell apparatus of any one of the preceding claims, wherein a funnellike passageway is provided in the thermal insulation layer to accommodate flexing and movement of the sensor assembly, with a wider end of the passageway facing the thermally insulated space.

16. The electrochemical cell apparatus of any one of the preceding claims, wherein a feedthrough tube is provided through the thermal insulation layer.

17. The electrochemical cell apparatus of any one of the preceding claims, wherein a feedthrough tube is provided between the thermal insulation layer and the receptacle.

18. The electrochemical cell apparatus of any one of the preceding claims, wherein the thermal insulation layer comprises at least an inner portion formed of a flexible or compliant material or fabric.

19. The electrochemical cell apparatus of any one of the preceding claims, wherein the electrochemical cell apparatus is an electrolyser apparatus.

20. The electrochemical cell apparatus of any one of the preceding claims, wherein the electrochemical cell units are electrolyser cell units based on a solid oxide electrolyte.

21. The electrochemical cell apparatus of any one of the preceding claims, wherein the electrochemical cell units operate at a target operational temperature in excess of 400 °C.

22. The electrochemical cell apparatus of any one of the preceding claims, wherein the enclosure is a pressure vessel.

23. A method of accommodating relative movements due to thermal expansion or thermal contraction within an electrochemical cell apparatus, the apparatus comprising: an enclosure; a stack of electrochemical cell units, the stack being contained within the enclosure; a manifold for supply of fluid to or exhaust of fluid from the stack, wherein the manifold is fixed relative to the enclosure at a first part of the manifold; a support structure for the manifold at a second part of the at least one manifold, the second part of the manifold being spaced from the first part of the manifold, wherein the support structure is configured to allow relative movement between said second part and the enclosure; a thermal insulation layer provided inside said enclosure; a thermally insulated space defined inside the thermal insulation layer, in which said stack and manifold are located; a sensor assembly which penetrates the enclosure and the thermal insulation layer; and a receptacle attached to or unitary with the manifold, the stack or a branch of the manifold; wherein the sensor assembly is fitted into the receptacle through a sidewall of the enclosure, and the sensor assembly is configured to be flexible and movable in a lateral direction, relative to the sensor assembly's direction of penetration through the enclosure and the thermal insulation layer, whereby upon movement of the second part of the manifold due to thermal expansion or contraction, relative movement between ends of the sensor assembly is accommodated by flexing and movement of the sensor assembly between the enclosure and the receptacle.

24. The method of claim 23, wherein the electrochemical cell apparatus is in accordance with any one of claims 1 to 22.

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