Patent Application
20140020675
This disclosure relates to improvements in solar receivers.
A concentrated solar power tower system collects solar radiation for the purpose of heating a working fluid to generate electrical power. The system typically includes solar receivers that are mounted on a tower. Heliostats direct concentrated solar radiation toward the solar receivers. The solar radiation heats working fluid that circulates through tubes of the solar receivers.
A solar receiver according to an exemplary aspect of the present disclosure includes a manifold, a sealed enclosure around the manifold, and a plurality of tubes connected to the manifold and extending through the sealed enclosure.
In a further non-limiting embodiment, the sealed enclosure defines a volume between the sealed enclosure and the manifold, the sealed enclosure substantially sealing the volume from convective air flow between the volume and an exterior of the sealed enclosure.
In a further non-limiting embodiment of any of the foregoing examples, the volume is at a lower pressure than the exterior.
In a further non-limiting embodiment of any of the foregoing examples, the volume includes an insulating gas different than air.
In a further non-limiting embodiment of any of the foregoing examples, the insulating gas is selected from the group consisting of nitrogen-based gas, helium-based gas, carbon dioxide-based gas and combinations thereof.
In a further non-limiting embodiment of any of the foregoing examples, the sealed enclosure includes at least one seal element.
In a further non-limiting embodiment of any of the foregoing examples, the sealed enclosure includes at least one seal element between a panel of the sealed enclosure and the plurality of tubes.
In a further non-limiting embodiment of any of the foregoing examples, the sealed enclosure includes a top wall above the manifold, a bottom wall below the manifold, a forward wall in front of the manifold, a back wall behind the manifold, and side walls adjacent ends of the manifold.
A further non-limiting embodiment of any of the foregoing examples includes a thermal shield arranged adjacent the sealed enclosure.
In a further non-limiting embodiment of any of the foregoing examples, the thermal shield includes a support and ceramic panels mounted in an array on the support.
In a further non-limiting embodiment of any of the foregoing examples, the ceramic panels include respective openings there-through and fasteners arranged partially within the respective openings and securing the ceramic panels on the support, and plugs arranged at least partially within corresponding ones of the openings.
In a further non-limiting embodiment of any of the foregoing examples, the sealed enclosure includes a heater.
In a further non-limiting embodiment of any of the foregoing examples, the sealed enclosure includes an insulator panel sealed against the plurality of tubes.
A method for use with a solar receiver according to an exemplary aspect of the present disclosure includes sealing an enclosure around a manifold that is connected with a plurality of tubes such that there is a volume between the enclosure and the manifold that is sealed from an exterior of the enclosure.
A further non-limiting embodiment includes substantially sealing the enclosure around the manifold from convective air flow with the exterior of the enclosure.
A further non-limiting embodiment of any of the foregoing examples includes establishing the volume to be at a lower pressure than the exterior.
In a further non-limiting embodiment of any of the foregoing examples, the volume has an insulating gas different than air.
In a further non-limiting embodiment of any of the foregoing examples, the insulting gas is selected from the group consisting of nitrogen-based gas, helium-based gas and carbon dioxide-based gas.
A thermal shield according to an exemplary aspect of the present disclosure includes a support and ceramic panels mounted in an array on the support. The ceramic panels include respective openings there-through. Fasteners are arranged partially within the respective openings and secure the ceramic panels on the support. Plugs are arranged at least partially within corresponding ones of the openings.
In a further non-limiting embodiment of any of the foregoing examples, the plugs are ceramic plugs.
In a further non-limiting embodiment of any of the foregoing examples, the ceramic panels include lap joints.
In a further non-limiting embodiment of any of the foregoing examples, the array is planar.
The various features and advantages of the present disclosure will become apparent to those skilled in the art from the following detailed description. The drawings that accompany the detailed description can be briefly described as follows.
Referring to
Molten salt or other working fluid circulates, such as by pumping, from a cold storage tank system 28 through the solar receiver system 22. The heated working fluid then circulates to a hot storage tank system 30. When power is required, the hot working fluid is pumped to a steam generator system 32 to produce steam. The steam drives a steam turbine/generator system 34 that generates electricity for communication to a power grid. The working fluid is returned to the cold storage tank system 28 and is eventually reheated in the solar receiver system 22. It should be understood that although a particular arrangement is disclosed in the illustrated embodiment, any arrangement with a solar receiver system 22 will also benefit from this disclosure.
Referring to
The design of the tubes 50 also provides a relatively low number of different parts and reduces manufacturing costs and assembly or maintenance time. For example, the arrangement and geometry of the tubes 50 are symmetric about a vertical plane VP. Thus, each tube 50 has a corresponding tube 50 on an opposite side of the vertical plane VP that is a mirror image.
Any thermal losses from the solar receiver 40 can debit the overall efficiency of the solar receiver system 22. In this regard, as shown in
The tubes 50 are connected to the manifold 52 by quick connectors (not shown). The quick connectors permit the tubes 50 to be easily removed and attached to the manifold 52. The tubes 50 extend through the sealed enclosure 58 and thus the sealed enclosure 58 surrounds the manifold 52 and a portion of the plurality of tubes 50. In this example, the sealed enclosure 58 includes a top wall 58a above the manifold 52, a bottom wall 58b below the manifold 52, a forward wall 58c in front of the manifold 52, a back wall 58d behind the manifold 52 and sidewalls 58e/58f adjacent the ends of the manifold 52. Thus, the sealed enclosure 58 surrounds the manifold 52 on all sides. The sealed enclosure 58 can be made of or include an insulating material, such as a ceramic material or flexible insulating material.
The forward wall 58c includes an insulator panel 58c′, such as an organic or polymeric panel, that is compressed against the outer surfaces of the tubes 50, to facilitate sealing and insulating. At least the inner surface of the insulator panel 58c′ is in contact with the tubes 50 and may have grooves 59 that correspond to the shape of the tubes 50. The grooves 59 provide a close fit between the insulator panel 58c′ and the tubes 50 for sealing and insulating.
The sealed enclosure 58 defines an interior volume 60 that is sealed from the exterior 62 of the solar receiver 40. To facilitate sealing, and also allow access to the interior volume 60, the sealed enclosure 58 includes seals 64a/64b. The seal 64a is arranged between the top wall 58a and the forward wall 58c. The seal 64b is arranged between the bottom wall 58b and the tubes 50/forward wall 58c. For example, the seal 64b is compressed against the tubes 50 to provide a substantially air-tight closure that reduces convective gas flow between the interior volume 60 and the exterior 62. For example, there is no open, free gas flow between the interior volume 60 and the exterior 62 and any gas within the sealed enclosure 58 is substantially stagnant. The seals 64a/64b also provide the sealed enclosure 58 with compliance to accommodate thermal expansion and contraction from heating and cooling cycles, which facilitates maintaining the tubes 50 in a proper, sealed position.
The sealed, interior volume 60 thermally insulates the manifold 52 and a portion of the tubes 50 that are within the sealed enclosure 58. In one example, the interior volume 60 is evacuated and maintained at a pressure that is lower than the exterior 62. In another example, the interior volume 60, at the low pressure or at ambient pressure, includes an insulating gas. For example, the insulating gas is a helium-based gas, a carbon dioxide-based gas, a nitrogen-based gas or combinations thereof. In a further example, the environment in the interior volume 60 has a composition of greater than 90% by volume of the selected insulating gas. In a further example, the insulating gas has a composition that is different than air, which for purposes of this disclosure has a composition of 78% nitrogen, 21% oxygen, less than 1% argon, less than 0.05% carbon dioxide and a remainder of trace elements. The low pressure, and/or insulating gas, facilitates the reduction in thermal losses from the manifold 52 and portion of the tubes 50 that are within the sealed enclosure 58.
In this example, the sealed enclosure 58 also includes a heater 66 mounted on the bottom wall 58b. In other examples, the heater 66 may be excluded, or additional heaters can be provided on other walls of the sealed enclosure 58. For example, the heater 66 is an electric resistance heater and is used to heat the interior volume 60 and manifold 52. The heater 66 can also be used to heat the manifold 52 for the purpose of preventing or limiting freezing of the working fluid in the manifold 52 and portion of the tubes 50 within the sealed enclosure 58.
As can be appreciated, the arrangement of the solar receiver 40 also embodies a method for use with the solar receiver 40. The method includes sealing the enclosure 58 around the manifold 52 (or alternatively the manifold 54) that is connected with the tubes 50 such that the interior volume 60 between the enclosure 58 and the manifold 52 is sealed from the exterior 62.
Referring to
Although a combination of features is shown in the illustrated examples, not all of them need to be combined to realize the benefits of various embodiments of this disclosure. In other words, a system designed according to an embodiment of this disclosure will not necessarily include all of the features shown in any one of the Figures or all of the portions schematically shown in the Figures. Moreover, selected features of one example embodiment may be combined with selected features of other example embodiments.
The preceding description is exemplary rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this disclosure. The scope of legal protection given to this disclosure can only be determined by studying the following claims.
