Patent Application
20180331384
The present disclosure relates to systems and methods of insulating and compressing high temperature devices.
Current solutions for insulating and compressing a high temperature device can be bulky and mechanically unsound. There exists a need for an improved system and method of insulating and compressing high temperature device.
Embodiments are illustrated by way of example and are not limited in the accompanying figures.
Skilled artisans appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the invention.
The following description in combination with the figures is provided to assist in understanding the teachings disclosed herein. The following discussion will focus on specific implementations and embodiments of the teachings. This focus is provided to assist in describing the teachings and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other embodiments can be used based on the teachings as disclosed in this application.
The terms “comprises,” “comprising,” “includes,” “including,” “has,” “having” or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, “or” refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).
Also, the use of “a” or “an” is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the invention. This description should be read to include one, at least one, or the singular as also including the plural, or vice versa, unless it is clear that it is meant otherwise.
For example, when a single item is described herein, more than one item may be used in place of a single item. Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent not described herein, many details regarding specific materials and processing acts are conventional and may be found in textbooks and other sources within the high temperature system arts.
High temperature devices, such as fuel reformers, heat exchangers, filters, reactors, electrochemical devices, and the like, can operate at temperatures of about 500° C. and up to 1000° C. or greater. Such high temperature devices may require compression, for example, to provide a seal, to maintain an electrical contact, or to maintain structural integrity. Some existing compression systems have used ceramic materials for various parts of a compression system, such as alumina or zirconia bolts and silicon nitride springs, specialty metals, or conventional metals with specialty coatings having high oxidation resistance and closely matched thermal expansion coefficients. Although ceramics and specialty metals can avoid corrosion and deformation under the extreme conditions, they can be brittle and fracture during high temperature compression. Other technologies have used a fully external compression system using stronger materials but require bulky insulation layers to reduce the temperature sufficiently to use those materials. However, the bulky insulation can increase the overall weight and size of the system, and in the case of electrochemical devices, can reduce volumetric power density and power-to-weight ratio (power/kg). As will be discussed in more detail below, certain embodiments of the systems disclosed herein have the advantage of allowing for using stronger, low temperature materials without reducing volumetric power density and power-to-weight ratio.
In certain embodiments, the high temperature device 20 can include a device having a maximum operating temperature of at least 500° C. In particular embodiments, the high temperature device 20 can have an operating temperature in a range of from about 500° C. to about 1000° C., or about 700° C. to about 900° C.
In particular embodiments, the high temperature device 20 can include a fuel reformer, a heat exchanger, a filter, a reactor, or an electrochemical device. In more particular embodiments, the high temperature device can include an electrochemical device, such as a battery or a fuel cell. In more particular embodiments, the electrochemical device can include a solid oxide fuel cell. In more particular embodiments, the electrochemical device can include a monolithic solid oxide fuel cell stack in which the directions of the air and gas flows are orthogonal to the direction of current flow and impinge on the exterior surfaces.
In certain embodiments (see, for example,
In certain embodiments, as illustrated in
In further embodiments, the fluid delivery and distribution manifold can comprise a high temperature, non-yielding material, such as a material that maintains structural integrity at the operating temperature of the high temperature device. In particular embodiments, the high temperature, non-yielding material can include a ceramic. The ceramic can include, for example, an alumina, a stabilized zirconia, an MgO-doped MgAl2O4 spinel, or any combination thereof.
In further embodiments, the high temperature system 20 can include a seal 90 disposed between the fluid delivery and distribution manifold 80 and the high temperature device 20 such that the fluid delivery and distribution manifold 80 is separated from the high temperature device 20 by seal 90. In particular embodiments, the seal 90 can include a compressible gasket or a non-compressible gasket. The compressible gasket can include, for example, a phlogophite mica, a muscovite mica, a vermiculite, or any combination thereof. In particular embodiments, the vermiculite can include a chemically exfoliated vermiculite, such as a Thermiculite 866 or a Thermiculite 866 LS (available from Flexitallic, LP at Deer Park, Tex., USA). The non-compressible gasket can include, for example, a viscous glass, a glass ceramic, or a combination thereof. The seal 90 can be compressed against a surface of the high temperature device 20, for example, by the compression device 30, to maintain an essentially leak-free seal as fluid flows into or out of the high temperature device 20. Further, the seal 90 can be supported by compressing the seal against the high temperature device 20, for example, via the compression device 30, to prevent a leak-inducing creep.
It is recognized that any of the embodiments of the high temperature device, though not illustrated, can include a fluid delivery distribution 80, a seal 90, or both, as described above.
Referring again to
The biaxial compression can be used for a solid oxide fuel cell stack. A planar solid oxide fuel cell stack can include a planar geometry comprising a sandwich-type configuration where a series of electrolyte cells and interconnect plates are stacked in the vertical, z-axis direction from top to bottom. In such a configuration, the air and fuel can flow up and down the z-axis of the stack and requires compression between the top and bottom plates along the z-axis direction relative to the electrochemical device. In other configurations, the fuel and air flow could instead pass through the sides of the fuel cell along the x-y plane. Thus, in particular embodiments, horizontal-horizontal compression can be applied where the first direction F1 and the second direction F2 can lie along the x-y plane relative to the electrochemical device 20. In a more particular embodiment, the electrochemical device 20 can include a third plurality of opposite surfaces having an intersecting z-axis orthogonal to the first and second directions, and the compression device 30 does not or is not adapted to exert a compression force on the third plurality of opposite surfaces.
In other embodiments, the third plurality of opposite surfaces can function as the surface from which a current is collected, such as in the case of an electrochemical device, such as a fuel cell or battery. As will be discussed in more detail further below the compression device 30 can exert or be adapted to exert a compressive force on the third plurality of opposite surfaces and at least one of the first and second plurality of surfaces, using the vertical-horizontal compression. In an embodiment, force is applied on two of the pluralities of opposite surfaces, and in another embodiment, force is applied on each of the three pluralities of opposite surfaces.
The compression device 30 can include a spring compression device having a spring mechanism to assist in exerting the compression forces. In particular embodiments, the spring mechanism can comprise a first spring mechanism 32 and a second spring mechanism 33. The first spring mechanism 32 can be adapted to exert a first compression force F1 along a first direction intersecting the first opposite surfaces 22 and 24, and the second spring mechanism 33 can be adapted to exert a second compression force F2 along a second direction intersecting the second opposite surfaces 23 and 25.
In certain embodiments, the spring mechanisms can include spring elements 60 of the compression device 30, which can include compression springs, extension springs, or both. In particular embodiments, the spring elements 60 can include a bolt and spring assembly. In further embodiments, the springs 60 of the compression device can comprise a metal. In particular embodiments, the metal can include a nickel-iron alloy, a nickel-chromium alloy, or any combination thereof.
Further, the compression device 30 can include a load spreading device. The load spreading device can distribute the compressive force of the compression device onto, for example, the insulation, the manifold, or other components of the high temperature system. In an embodiment, the load spreading device can transfer the compressive force of the compression device onto the high temperature insulation such that stress on the high temperature insulation is less than its cold crush strength.
In an embodiment, the load spreading device can include a compression plate. For example, the compression device can include a first plurality of compression plates 34, 36 corresponding to the first plurality of opposite surfaces 22, 24 of the high temperature device, and can include a second plurality of compression plates 35, 37 corresponding to the second plurality of opposite surfaces 23, 25 of the high temperature device. In certain embodiments, the compression plates 34, 35, 36, 37 can be adapted to transmit and disperse load from a compressive source, such as the spring elements 60 discussed above, individually or interconnected, and provide the compression necessary for a gas seal, in the case of a fuel cell, or for current collection compression, in the case of a fuel cell or a battery. In further embodiments, the compression plates 34, 35, 36, 37 of the compression device 30 can comprise a metal. In particular embodiments, the metal can include a stainless steel alloy, a nickel-chromium alloy, or any combination thereof.
In further embodiments, the spring mechanisms can include at least one spring 60 disposed on opposite ends of each compression plate. To improve control over the compression levels, the spring elements 60 can include at least two, at least three, at least four, or at least five springs disposed on an end or on opposite ends of each compression plate. Springs have the advantage of compensating for a coefficient of thermal expansion mismatch, but in certain circumstances can be limited in the levels of force they can generate.
Different compression geometries are possible for an improved force generation depending on the desired application.
As illustrated in
As illustrated in
As illustrated in
As illustrated in
In further embodiments, as illustrated in
In a further embodiment, the compression device can include any one of the configurations in
In an embodiment, the compression plates can be coupled to each other to exert a force in the vertical and horizontal directions. The compression plates can be coupled using a spring 60 or a band 160, as described above. In a particular embodiment, the compression plates can be coupled via springs 60 such that increasing the load on one axis can decrease the load on the other axis.
In an embodiment, the vertical-horizontal compression device can be disposed on a high temperature device, such as a planar solid oxide fuel cell. The planar solid oxide fuel cell can be configured in a stack, where planar cells are separated by planar electrical interconnect components that conduct electricity between the cells. A current collector can be disposed on the stack to facilitate current collection. In a particular embodiment, a current collector can be disposed between the stack and a compression plate. For example, as illustrated in
Further, certain embodiments of the high temperature system 10 described herein can allow for the use of conventional, low temperature, high strength materials at an intermediate temperature by decoupling the thermal and mechanical requirements of the insulation. Separating the insulation into high temperature and low temperature insulations can reduce bulkiness and provide a more compact and efficient structure. As illustrated in
In certain embodiments, the high temperature insulation 40 can be disposed between the spring compression device 30 and the high temperature device 20. In certain embodiments, the high temperature insulation 40 can be adapted to withstand a high operating temperature, exhibit a high compressive strength, and reduce the external temperature from a high temperature to an intermediate temperature such that a conventional low temperature, high strength material can be used to generate and transmit a compressive load.
As discussed above, the high temperature insulation 40 can be adapted to reduce a temperature from a high operating temperature to an intermediate temperature. In certain embodiments, the high operating temperature can be in a range of from about 500° C. to about 1000° C., or about 700° C. to about 900° C. In further embodiments, the intermediate temperature can be in a range of from about 400° C. to about 600° C., such as less than 500° C., or no greater than the higher end of the temperature range of the low temperature, high strength material of the compression device 30.
In certain embodiments, the high temperature insulation can have a thermal conductivity TCH at 800° C. of at least 90, at least 95, or even at least 100 mW/m*K. In further embodiments, the high temperature insulation may have a thermal conductivity TCH at 800° C. of no greater than 500, no greater than 400, or even no greater than 350 mW/m*K. Moreover, the high temperature insulation can have a thermal conductivity TCH at 800° C. in a range of any of the above minimum and maximum values, such as in a range of 90 to 500, 95 to 400, or even 100 to 350 mW/m*K. The thermal conductivity can be measured according to the axial heat flow method (ASTM E1225-13).
In certain embodiments, the high temperature insulation 40 can be a structural insulation having a high compression strength and a high density. In particular embodiments, the high temperature insulation 40 can have a compression strength (or cold crush strength) at 20° C. of at least 0.02, or at least 0.025, or at least 0.03 MPa. In further embodiments, the high temperature insulation 40 may have a compression strength at 20° C. of no greater than 8, no greater than 6.5, or no greater than 5 MPa. Moreover, the high temperature insulation 40 can have a compression strength at 20° C. in a range of any of the above maximum and minimum values, such as in a range of 0.02 to 8, 0.025 to 6.5, or 0.03 to 5 MPa. The compression strength can be measured according to standard EN ISO 8895:2004 (Heat-insulating shaped refractory).
In certain embodiments, the high temperature insulation 40 can have a density at 20° C. of at least 0.2, at least 0.23, or at least 0.25 g/cm3. In further embodiments, the high temperature insulation 40 may have a density at 20° C. of no greater than 9, no greater than 8, or no greater than 7.5 g/cm3. Moreover, the high temperature insulation 40 can have a density at 20° C. in a range of any of the above minimum and maximum values, such as in a range of 0.2 to 9, 0.23 to 8, or 0.25 to 7.5 g/cm3. The density can be measured according to Archimedes' Principle.
In certain embodiments, the high temperature insulation 40 can include a ceramic material, such as a ceramic material comprising an alumina. In particular embodiments, the high temperature insulation 40 can include the insulation materials listed in Table 1 below.
Further, as illustrated in
In further embodiments, the low temperature insulation 50 can be disposed external to the compression device 30 such that the compression device 30 is disposed between the high temperature insulation 40 and the low temperature insulation 50. In certain embodiments, the low temperature insulation 50 can be adapted to surround the compression device 30 and reduce the external temperature to an ambient temperature. In particular embodiments, the low temperature insulation 50 can be a non-structural insulation, for example, providing little or no mechanical strength.
The low temperature insulation 50 can be disposed external to the compression device 30. The low temperature insulation can be adapted to have a low thermal conductivity TCL and a low density. In certain embodiments, the low temperature insulation has a thermal conductivity TCL at 500° C. of at least 15, at least 17, or at least 20 mW/m*K. In further embodiments, the low temperature insulation may have a thermal conductivity TCL at 500° C. of no greater than 400, no greater than 300, or no greater than 250 mW/m*K. Moreover, in certain embodiments, the low temperature insulation may have a thermal conductivity TCL at 500° C. in a range of any of the above minimum and maximum values, such as in a range of 50 to 400, 55 to 300, or 60 to 250 mW/m*K. In very particular embodiments, the low temperature insulation can have a thermal conductivity TCL at 500° C. in a range of 20 to 250 mW/m*K.
In certain embodiments, the low temperature insulation comprises a non-structural insulation having a low density, to provide a less bulky, more compact design. In other embodiments, the low temperature insulation can be a structural insulation. In particular embodiments, the low temperature insulation may have a density at 20° C. of no greater than 1, no greater than 0.7, or no greater than 0.5 g/cm3. In more particular embodiments, the low temperature insulation can have a density at 20° C. of at least 0.05, at least 0.07, or at least 0.1 g/cm3. Moreover, in certain embodiments, the low temperature insulation can have a density at 20° C. in a range of 0.05 to 1, 0.07 to 0.7, or 0.1 to 0.5 g/cm3.
In particular embodiments, the low temperature insulation can comprise an aerogel, a carbon nanofoam, an alumina fiberboard, an encapsulated cavity, an air gap, or any combination thereof. A non-limiting list of examples of the low temperature insulation are provided below in Table 2.
The high temperature and low temperature insulation can work in concert to provide sufficient temperatures to use conventional metals while reducing bulk. In certain embodiments, the ratio of TCH:TCL is in a range of 1 to 11, where TCH is a thermal conductivity of the high temperature insulation and TCL is a thermal conductivity of the low temperature insulation.
An advantage of certain embodiments described herein is that the electrochemical system can have an improved volumetric power density and in improved power/kg. In certain embodiments, the electrochemical system can have a volumetric power density of at least 58,000 W/m3, at least 70,000 W/m3, or even at least 90,000 W/m3. The volume can be measured via Archimedes' Principle. For an electrochemical device, power is measured by a current voltage curve under electrical load at given operating conditions. The volumetric power density is thus the ratio of the operating power divided by the displaced volume. Further, the electrochemical system can have a power-to-weight ratio (power/kg) of at least 18 W/kg. Weight, or more correctly, mass is measured using a standard scale. The power-to-weight ratio is thus the ratio of the operating power divided by the mass of the high temperature device.
Also described herein is a method of compressing an electrochemical device. In certain embodiments, the method can comprise providing the electrochemical device; providing a layer of high temperature insulation adjacent the electrochemical device; and biaxially compressing the layer of high temperature insulation against the electrochemical device. Biaxially compressing the layer of high temperature insulation can include providing the compression device previously described herein. The method can further include providing a layer of low temperature insulation external to the compression device and the layer of high temperature insulation, low temperature insulation, or both, can include the low temperature insulation, high temperature insulation, or both, previously described herein. Further, the electrochemical device can include the electrochemical device previously described herein.
Many different aspects and embodiments are possible. Some of those aspects and embodiments are described below. After reading this specification, skilled artisans will appreciate that those aspects and embodiments are only illustrative and do not limit the scope of the present invention. Embodiments may be in accordance with any one or more of the embodiments as listed below.
Note that not all of the activities described above in the general description or the examples are required, that a portion of a specific activity may not be required, and that one or more further activities may be performed in addition to those described. Still further, the order in which activities are listed is not necessarily the order in which they are performed.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any feature(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature of any or all the claims.
The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Separate embodiments may also be provided in combination in a single embodiment, and conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination. Further, reference to values stated in ranges includes each and every value within that range.
Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US16/61658 | 11/11/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62255318 | Nov 2015 | US |
