US20130081797A1 - Heat exchanger having powder coated elements - Google Patents
Heat exchanger having powder coated elements Download PDFInfo
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- US20130081797A1 US20130081797A1 US13/683,516 US201213683516A US2013081797A1 US 20130081797 A1 US20130081797 A1 US 20130081797A1 US 201213683516 A US201213683516 A US 201213683516A US 2013081797 A1 US2013081797 A1 US 2013081797A1
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- elements
- component
- heat exchange
- coating
- powder coating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F7/00—Elements not covered by group F28F1/00, F28F3/00 or F28F5/00
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D19/00—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium
- F28D19/04—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier
- F28D19/041—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier with axial flow through the intermediate heat-transfer medium
- F28D19/042—Rotors; Assemblies of heat absorbing masses
- F28D19/044—Rotors; Assemblies of heat absorbing masses shaped in sector form, e.g. with baskets
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D19/00—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium
- F28D19/04—Regenerative heat-exchange apparatus in which the intermediate heat-transfer medium or body is moved successively into contact with each heat-exchange medium using rigid bodies, e.g. mounted on a movable carrier
- F28D19/047—Sealing means
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
- F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28G—CLEANING OF INTERNAL OR EXTERNAL SURFACES OF HEAT-EXCHANGE OR HEAT-TRANSFER CONDUITS, e.g. WATER TUBES OR BOILERS
- F28G9/00—Cleaning by flushing or washing, e.g. with chemical solvents
- F28G9/005—Cleaning by flushing or washing, e.g. with chemical solvents of regenerative heat exchanger
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/4935—Heat exchanger or boiler making
Abstract
Powder coated heat exchange elements for a heat exchanger. Powder coating provides improved protective coating on surfaces of heat exchange elements. In many applications, the heat exchange elements are subjected to harsh operating conditions that promote corrosion. Traditional enamel coating tends to fracture when subjected to mechanical stresses thereby allowing corrosion inducing agents to penetrate and corrode the underlying surfaces. Powder coating reduces breaches in the protective layer. Powder coating may be adapted to withstand high temperatures so as to make them suitable for use in harsh operating environments. One such environment can be found in the processing of flue gas from fossil burning power generators, where the flue gas has a relatively high temperature and high sulfur content.
Description
- This application is a continuation application of U.S. patent Ser. No. 12/911,346 filed on Oct. 25, 2010, which is a continuation application of U.S. patent application Ser. No. 11/198,406, filed Aug. 4, 2005, now U.S. Pat. No. 7,819,176, which is a continuation-in-part application of U.S. application Ser. No. 10/793,182, filed Mar. 3, 2004, now U.S. Pat. No. 7,841,390, which claims the benefit of U.S. Provisional Application No. 60/452,065, filed Mar. 3, 2003 and entitled “ROTARY HEAT EXCHANGER WITH POWDER COATED HEAT EXCHANGE ELEMENTS”, all of which are hereby incorporated by reference in their entirety and should be considered a part of this specification.
- 1. Field
- The present teachings relate to heat exchangers and, in particular, relates to a heat exchanger having powder coated elements that inhibit corrosion.
- 2. Description of the Related Art
- Heat exchangers in various forms are included in systems that control the condition of air. Conventional heat exchangers include a heater that takes input air and outputs air with a higher temperature. A cooler, generally referred to as an air conditioner, takes input air and outputs air with a lower temperature. In both cases, the change in temperature is achieved by some form of a heat exchanger. In a heater, air is typically blown past a heated element such that heat is transferred from the heated element to the air. In a cooler, air is typically blown past a chilled element such that heat is transferred from the air to the chilled element.
- A rotary heat exchanger is an apparatus that exchanges heat with relatively large volumes of air. The rotary heat exchanger typically comprises a cylindrically shaped device that permits air to flow therethrough. Typically, heat exchange is achieved by flowing both the input air and exhaust air through the rotating rotary heat exchanger at two different locations. Heat exchange elements in the exchanger remove heat from one flow of air and release the heat to the other flow of air. The rotational speed can be selected to permit efficient overall heat transfer.
- In operation, the heat exchangers are usually exposed to harsh environments that tend to induce corrosion of the metal of the heat exchanger, including the seals and the heat exchange elements. The corrosive environment leads to pitting in the degeneration of the metal in the heat exchange elements, structurally weakening the elements. To counter the corrosion problems, traditional heat exchange elements often have an enamel coating applied to the surface of the metal. Often, the enamel coating contains bubbles such that full corrosion protection is not afforded. In addition, the enamel coating is susceptible to cracking when subjected to mechanical stresses. Such breach of the coating allows corrosion inducing agents to come in contact with the metal, thereby causing corrosion, which in turn reduces the effectiveness of the heat exchanger.
- From the foregoing, it will be appreciated that there is a need for an improved method of fabricating a heat exchanger. To this end, there also exists a need for an improved method of protecting the metal of the heat exchange elements so as to provide improved corrosion resistance.
- The aforementioned needs may be satisfied by a heat exchanger comprising, in one embodiment, a heat exchanging body that rotates in a first direction with respect to a housing and a plurality of heat exchange elements disposed in the heat exchanging body so as to define a plurality of channels that allow air to flow therethrough, wherein each heat exchange element includes a powder coating to thereby resist corrosion.
- In one aspect, the heat exchanging body comprises a rotor. The rotor may be adapted to rotate about a rotational axis with respect to the housing such that a given portion of the rotor gains heat energy at a first location and gives off heat energy at a second location. In addition, the heat exchanger further comprises a first air passage assembly disposed adjacent the heat exchanging body, and wherein the air passage assembly is adapted to allow air to flow through a portion of the heat exchange body. Also, the first air passage assembly is disposed adjacent the rotor at one of the first or second locations. The air passage assembly is adapted to allow flow of air through a portion of the heat exchange body along a first direction relative to the rotational axis. The first direction is substantially parallel to the rotational axis. Moreover, the heat exchanging body is divided into a plurality of sectors, and wherein each sector includes at least one heat exchange element positioned therein.
- In another aspect, the powder coating comprises a high silica content. The powder coating is applied to the heat exchange elements with a temperature cure of approximately 400-500° F., 400-450° F. in about 15 minutes, or 400° F. in about 60 minutes. Also, the powder coating is adapted to withstand approximately 1000° F. for approximately 24 hours. The thickness of the powder coating on the heat exchange elements is between approximately 1.5-2.5 mils, or the thickness is between approximately 2-4 mils. Moreover, the powder coating comprises a layer of fused powder applied to the heat exchange elements in an electrostatically charged powder form and cured by heat.
- In still another aspect, the heat exchanger is adapted to be used in a high sulfur content air and high temperature environment. Also, the heat exchanger is adapted to be used to reduce the temperature of a flue gas being emitted from a fossil burning power generator prior to the gas being ejected into the environment.
- The aforementioned needs may also be satisfied with a heat exchanger comprising, in one embodiment, a heat exchanging body that rotates with respect to a housing and a first air passage assembly disposed adjacent the heat exchanging body, wherein the air passage assembly is adapted to allow flow of air through a portion of the heat exchange body. In addition, the heat exchanger may further comprise a plurality of heat exchange elements disposed in the heat exchanging body, wherein each heat exchange element defines a heat exchanging surface adapted to facilitate the heat exchange with the air flowing through the heat exchanging body, and wherein the heat exchanging surface includes a powder coating that resists corrosion.
- In one aspect, the heat exchanging body defines a plurality of segments, and wherein each segment defines a volume dimensioned to receive a plurality of heat exchange elements, and wherein each segment extends from a first angle to a second angle so as to generally resemble a pie-slice shape when viewed along the rotational axis. In addition, the heat exchange elements comprise shaped sheets of material dimensioned so as to be stackable along a radial direction, and wherein the shaped sheets are oriented so as to allow flow of air with a net direction that is generally parallel to the rotational axis. Also, the shaped sheets comprise a material selected from the group consisting of a sheet of metal, a sheet of stainless steel, a sheet of low carbon steel. The thickness of the shaped sheet is between approximately 18-24 gauge. Moreover, the shaped sheets define a plurality of channels for the flow of air such that, when stacked, the channels extend in a direction substantially parallel to the rotational axis. The shaped sheets comprises a first type of sheet and a second type of sheet such that the first type of sheet defines a plurality of channels that extend along a first direction relative to the rotational axis and the second type of sheet defines a plurality of channels that extend along a second direction relative to the rotational axis. The channels of the first type of sheet and the channels of the second type of sheet form crossing patterns.
- The aforementioned needs may also be satisfied by a heat exchange assembly for a heat exchanger having a heat exchanging body that rotates in a first direction with respect to a housing. In one embodiment, the assembly comprises a plurality of heat exchange members that are formed so as define a heat exchange surface, wherein the heat exchange members are positioned in the heat exchanging body to thereby facilitate heat exchange with air. In addition, the assembly further comprises a protective layer disposed on the heat exchange surface, wherein the protective layer comprises a powder coating that inhibits corrosion of the heat exchange members.
- In one aspect, the heat exchange members comprise a cross sectional shape including a plurality or undulations separated by a flat section, and wherein each undulated shape comprises an upper curved shape joined to a lower curved shape so as to form a full cycle wave like structure. In addition, the heat exchange members may comprise a corrugated configuration or a notched flat configuration. Moreover, the powder coating provides a barrier for the underlying heat exchange members to thereby resist corrosion inducing agents including water and sulfur based compounds.
- The aforementioned needs may also be satisfied by a method of fabricating a heat exchanger having a plurality of heat exchange elements adapted to allow flow of air therethrough and exchange heat with the flowing air. In one embodiment, the method comprises preparing the heat exchange elements for assembly, powder coating the heat exchange elements, and assembling the heat exchange elements. In one aspect, powder coating the heat exchange elements comprises cleaning the surface of the heat exchange elements and electrically grounding the heat exchange elements. In addition, powder coating the heat exchange elements further comprises applying electrostatically charged coating particles onto the heat exchange elements wherein the electrostatically charged coating particles are attracted to the electrically ground heat exchange elements thereby promoting adhesion of the coating particles to the surfaces of the heat exchange elements and curing the heat exchange elements, e.g. via the application of heat, so as to cause the coating particles to fuse with the surfaces of the heat exchange elements.
- The aforementioned needs may also be satisfied by a method of applying a corrosion resistant coating on a heat exchange element adapted for use in a heat exchanger. In one embodiment, the method comprises preparing the surface of the heat exchange element and electrically connecting the heat exchange element to a first potential. In addition, the method comprises applying electrostatically charged coating particles onto the heat exchange element wherein the first potential and the electrostatic charge of the coating particles are selected to promote adhesion of the coating particles to the surface of the heat exchange element and curing the heat exchange element so as to cause the coating particles to fuse with the surface of the heat exchange element. In one aspect, preparing the surface comprises cleaning the surface so as to facilitate adhesion of the coating particles. In addition, electrically connecting the heat exchange element comprises electrically grounding the heat exchange element.
- These and other advantages of the present teachings will become more fully apparent from the following description taken in conjunction with the accompanying drawings.
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FIG. 1A illustrates a side view of an exemplary rotary heat exchanger. -
FIG. 1B illustrates an end view of an exemplary rotary heat exchanger. -
FIG. 2 illustrates a segment of a rotor of the rotary heat exchanger, wherein the segment comprises a plurality of heat exchange elements stacked within a defined volume. -
FIGS. 3A-3E illustrate some of the various possible configurations of the heat exchange elements. -
FIGS. 4A-4B illustrate powder coated surfaces of the heat exchange element. -
FIG. 5 illustrates one possible method of fabricating a heat exchanger having powder coated heat exchange elements. -
FIG. 6 illustrates one possible method of powder coating a heat exchange element. -
FIG. 7 illustrates one possible application of the heat exchanger having powder coated heat exchange elements, wherein the powder coating may be adapted to operate at high temperatures. -
FIG. 8 illustrates another embodiment of a method of powder coating a component of a heat exchanger. -
FIG. 9 is a perspective view of one embodiment of a seal assembly. -
FIG. 10 is a side view of the seal assembly ofFIG. 9 in one operating position. -
FIG. 11A is a partial cross-sectional view of a heat exchanger illustrating another embodiment of a seal assembly. -
FIG. 11B is a partial cross-sectional view of a heat exchanger illustrating the seal assembly ofFIG. 11A mounted in different configuration in the heat exchanger. -
FIG. 12 is a perspective assembled view of the seal assembly ofFIG. 11A . -
FIG. 13 is a top view of the seal assembly ofFIG. 12 . - In the following detailed description, terms of orientation such as “top,” “bottom,” “upper,” “lower,” “front,” “rear,” and “end” are used herein to simplify the description of the context of the illustrated embodiments. Likewise, terms of sequence, such as “first” and “second,” are used to simplify the description of the illustrated embodiments. Because other orientations and sequences are possible, however, the present invention should not be limited to the illustrated orientation. Those skilled in the art will appreciate that other orientations of the various components described below are possible.
- Reference will now be made to the drawings wherein like numerals refer to like parts throughout.
FIGS. 1A-7 illustrate various aspects related to a heat exchanger having powder coated elements that inhibit corrosion. Various other aspects of the present teachings will be described in greater detail herein below with reference to the drawings. In general, it should be appreciated that the following description of a heat exchanger and elements comprised therein is in the context of a rotary heat exchanger. However, it should be appreciated by those skilled in the art that the novel features described herein are not limited to rotary type devices, but may be applied to various other types of generally known heat exchangers. -
FIG. 1A illustrates a perspective view of aregenerative heat exchanger 100 having one or more powder coated elements that inhibit corrosion.FIG. 1B illustrates a top view of theheat exchanger 100. As illustrated inFIGS. 1A-1B , theheat exchanger 100 comprises a heat exchanger body orrotor 102 that is positioned within aheat exchanger housing 104. In one embodiment, theheat exchanger 100 comprises a rotary heat exchanger, wherein theheat exchanger body 102 comprises a cylindrical rotor and theheat exchanger housing 104 comprises a cylindrical housing. Additionally, as further illustrated inFIGS. 1A-1B , thecylindrical rotor 102 is rotatably mounted within thecylindrical housing 104 via acenter shaft 105 so as to be coaxial therewith. Also, theheat exchanger rotor 102 further comprises a plurality ofradial walls 107 that extend radially outward from thecenter shaft 105. - In one embodiment, the
heat exchanger housing 104 comprises first andsecond sector plates housing 104. Theheat exchanger housing 104 is formed so as to define at least twoconduit openings sector plates - In one embodiment, the plurality of
radial walls 107 divides theheat exchanger rotor 102 into a plurality ofsectors 112 comprisingcore material 114. Thecore material 114 is adapted to absorb heat carried in the exhaust gas from the exhaust conduit and then transfer the absorbed heat to the intake air when theheated sector 112 is positioned in the path of the intake conduit. In one aspect, thecore material 114 may comprise thin corrugated conductive material, such as metal, that allows exhaust gases to travel therethrough. Also, heat carried within the exhaust gases heats thecore material 114 in the exhaust conduit. - Similarly, cool air passing through the
core material 114 in the intake conduit is heated by the retained heat of thecore material 114 during passage of the intake air through thecore material 114. Theheat exchanger 100 sequentially exposes eachsector 112 to hot gas in the exhaust conduit so that thecore material 114 is heated and, during rotation, exposes theheated sectors 112 ofcore material 114 to the intake conduit so that cooler air traveling through the intake conduit is heated by thecore material 114. The heated air is then exhausted from theheat exchanger 100. - It should be appreciated that the above described
heat exchanger 100 may operate in a similar manner to the operation of generally known Ljunstrom-type preheaters. It should also be appreciated from the following description that, while this particular embodiment of the perimeter seal assembly may be configured to be used with a Ljungstrom-type preheater, the perimeter seal assembly may be adapted by one skilled in the art to be used with a Rothmule-type preheater, where the rotor is stationary and the ductwork rotates with respect to the rotor, without departing from the scope of the present teachings. -
FIG. 2 illustrates one embodiment of thecore material 114 formed in the plurality ofsectors 112 of theheat exchanger rotor 102. As illustrated inFIG. 2 , thecore material 114 may comprise a wedge shaped enclosure formed by atop plate 131, abottom plate 132, and at least twoside plates 133. Theplates heat exchange elements 140 are disposed. In one aspect, theheat exchange elements 140 definechannels 142 that are stacked adjacently together so as to permit flow of air through thechannels 142. Additionally, thechannels 142 extend in a direction substantially parallel to the axis of rotation of theheat exchange rotor 102. Hence, theair flow 148 can be in a direction relative to the axis of rotation. - In the embodiment, the
heat exchange elements 140 are formed with corrugated and flat material, such as corrugated and flat sheet metal, that are joined together in a manner so as to form triangular shapedchannels 142. In addition, as illustrated inFIG. 2 , thechannels 142 are layered, stacked, or arranged within the segment 130 so as to fill thesector 112 of theheat exchange rotor 102. Advantageously, the arrangement of thelayered elements 140 allow increased surface area between the flowing air and the surface of thechannels 142. - Moreover, one aspect of the present teachings relates to the
heat exchange elements 140 having aresilient surface 144 that inhibits corrosion during harsh operating conditions and environments. For example, in one embodiment, theresilient surface 144 of theheat exchange elements 140 comprises a powder coating applied thereto so as to define a power coated surface. Advantageously, the coatedheat exchange elements 140 provide an improved resilience and reliability to thereby increase corrosion resistance more so than a typical traditional enamel coating. - In one embodiment, the powder coating of the
resilient surface 144 comprises a high silica content. Examples of the powder coating material is manufactured by TCI Powder Coatings located in Ellaville, Ga. and Alesta Powder Coatings located in Houston, Tex. In addition, the powder coating of theresilient surface 144 is formed with a low temperature cure of approximately 400-500° F. Under some circumstances, the curing process is achieved with a temperature of approximately 400-450° F. in about 15 minutes. In other circumstances, the curing process is achieved with a temperature of approximately 400° F. in about 60 minutes, such as with metal materials. Advantageously, the power coating of theresilient surface 144 of theheat exchange elements 140 is suitable for the harsh operating conditions of theheat exchanger 100. For example, in one aspect, the powder coating material can withstand 1000° F. for approximately 24 hours. Additionally, in one embodiment, the film thickness of the powder coating on theheat exchange elements 140 is between approximately 1.5-2.5 mils. In various other embodiments, the film thickness of the powder coating on theheat exchange elements 140 is between approximately 2-4 mils. - Conversely, conventional enameling of the
resilient surface 144, as in the prior art processes, requires an extremely high curing temperature of at least 1500° F. Unfortunately, this extremely high temperature can warp or deform theheat exchange elements 140, which can adversely impact the efficiency and reliability of theheat exchanger 100. - Furthermore, this extremely high curing temperature of the prior art can oxidize and corrode the surface of the
heat exchange elements 140. Also, in some circumstances, enamel is brittle and can fracture under the harsh operating conditions and stresses of theheat exchanger 100. For example, in general, coal exhaust can contain sulfur compounds. If the heat exchanger is used with coal exhaust, sulfur can combine with condensation so as to produce sulfuric acid. As a result, the sulfuric acid can corrode metal surfaces that are exposed when the enamel surface fractures or chips off. Sometimes, a low carbon steel can be used to deter corrosion. Unfortunately, the use of low carbon steel is more expensive and, thus, is not necessarily economically feasible for use inheat exchangers 100. However, the present teachings of powder coating theheat exchange elements 140 in a manner as described herein overcomes the deficiencies of the prior art. - It should be appreciated by those skilled in the art that the
heat exchange elements 140 may comprise various other geometrical shapes, such as circular, rectangular, pentagonal, hexagonal, etc., without departing from the scope of the present teachings. Therefore, it should be appreciated that the powder coating surface may be applied to heatexchange elements 140 having various cross-sectional shapes other than that illustrated inFIG. 2 without departing from the scope of the present teachings. Various configurations ofheat exchange elements 140 and the manner in which they can be powder coated will be described in greater detail herein below. -
FIGS. 3A-3E illustrate various embodiments of theheat exchange elements 140. It should be appreciated by those skilled in the art that the following embodiments of theheat exchange elements 140 comprise exemplary contours and configurations and are not meant to limit the scope of the present teachings. -
FIG. 3A illustrate one embodiment of theheat exchange elements 140 described above in reference toFIG. 2 . As illustrated inFIG. 3A , theelements 140 may comprise asection 150 having at least onecorrugated layer 164 disposed adjacent to at least oneflat layer 162. In one aspect, this illustrated contour or configuration of theelements 140 is formed so as to define a plurality of triangular shapedchannels 142 through which air flows to thereby exchange heat with theelements 140. It should be appreciated that the combination of thecorrugated layer 164 and theflat layer 162 may be repeated above and/or below the combination. For example, subsequent layering of additional sections 152 above and below thefirst section 140 can be used to form thecore material 114 and at least partially fill the plurality ofsectors 112 of theheat exchange rotor 102 as illustrated inFIGS. 1A-1B . -
FIG. 3B illustrates anotherembodiment 170 of theheat exchange elements 140 comprising anundulation layer 176 disposed on aflat layer 174. As illustrated inFIG. 3B , the sectional shape of theundulation layer 176 comprises a series ofundulations 180 spaced at selected distances apart. In addition, eachundulation 180 comprises an upper curved shape 184 joined to a lower curved shape 186 so as to define at least one cycle resembling a wave-like structure. Also, as further illustrated inFIG. 3B , two neighboringundulation sections 180 are separated by at least one flat section 188, wherein theundulation section 180 and the flat section 188 define a plurality ofchannels 182 through which air can flow. In one aspect, it should be appreciated that the combination of undulation andflat sections 180, 188 may be sequentially repeated. Alternatively, in another aspect, a serial combination of theflat section 174,undulation section 176, and anotherflat section 174 may be repeated as a group without departing from the scope of the present teachings. - In one embodiment, the undulation layers 176 may be arranged relative to each other such that the
channels 182 defined by one layer extend along a direction that is different than a direction of thechannels 182 of the other layer. Such angled configurations (sometimes referred to as a “cross” configuration) of the channels will be described in greater detail herein below in context of other possible channel contours, configurations, and shapes. -
FIG. 3C illustrates still anotherembodiment 190 of theheat exchange elements 140 comprising a notchedlayer 192 disposed on aflat layer 194. As illustrated inFIG. 3C , the sectional shape of the notchedlayer 192 comprises a series ofnotches 196 spaced at selected distances apart. In addition, the notchedlayer 192 and theflat layer 194 define a plurality ofchannels 200 through which air can flow. It should be appreciated by those skilled in the art that the configuration of theheat exchange elements 140, as illustrated inFIG. 3C , may also be referred to as a notched flat (NF) configuration without departing from the scope of the present teachings. - It should also be appreciated by those skilled in the art that the various embodiments of the
heat exchange elements 140 as previously described herein above comprise air flow channels that are generally aligned along a single direction. Therefore, it should also be appreciated that any number of different sectional shapes, contours, or configurations of theelements 140 may be used to achieve such an air flow and, in addition, may be implemented without departing from the scope of the present teachings. Moreover, the sectional shape of a givenelement 140 may depend on various factors, such as manufacturing techniques, structural requirements, air flow characteristics, heat exchange characteristics, etc. - In other embodiments, the
channels heat exchange elements 140 can be adapted to extend along various directions. For example,FIG. 3D illustrates one embodiment of theelements 140 comprising at least two notchedlayers 210 combined in a manner such that the channels of one layer extend at an angle with respect to channels of another layer. It should be appreciated by those skilled in the art that this configuration may be referred to as a notched crossed (NC) configuration. In one aspect, this angled channel direction relationship between the two layers is depicted in aplan view 214 as a plurality ofsolid lines 216 representing thenotches 212 of one layer, and a plurality of dashedlines 218 representing thenotches 212 of the other layer. The angle between thechannel directions -
FIG. 3E illustrates oneembodiment 220 of theheat exchange elements 140 having crossed channels. As illustrated inFIG. 3E , theelements 140 comprises a firstcorrugated layer 222 and a secondcorrugated layer 224. In one embodiment, the firstcorrugated layer 222 comprises a plurality ofcorrugations 226 that are larger thancorrugations 230 defined by a secondcorrugated layer 224. Thelarger corrugations 226 definechannels 232, and thesmaller corrugations 230 definechannels 234. The relative directions of thecorrugations larger corrugations 226 are represented as solid lines, and thesmaller corrugations 230 are represented as dashed lines. When such two layers of corrugations are oriented in an angled manner, thechannels elements 140. Moreover, relative channel directions between the adjacent layers may be selected in any number of ways without departing from the scope of the present teachings. - The various layers of the
elements 140 described above may be formed in any number of ways known in the art. In one embodiment, theelements 140 may be formed out of metal such as low carbon steel or stainless steel. It should be appreciated by those skilled in the art that other forms of metals, as well as any other material, may be used to form theelements 140, wherein the material can be adapted to allow powder coating thereon. For the metal based elements, the layers may be formed out of sheet metal having various depending on the application or implementation. It should be appreciated by those skilled in the art that the sheet metal may comprise various thicknesses including but not limited to 18, 22, or 24 gauge sheet metal without departing from the scope of the present teachings. -
FIGS. 4A-4B illustrate a powder coating layer formed on a base material. In one embodiment, as illustrated inFIG. 4A , the base material comprises abase layer 242, such as any of the layers described herein. Thebase layer 242 defines afirst surface 244 and asecond surface 246, on which respective first and second powder coating layers 250, 252 are formed. Additionally, the firstpowder coating layer 250 has afirst thickness 254, and the secondpowder coating layer 252 has asecond thickness 256. It should be appreciated that, in various embodiments, the first andsecond thicknesses -
FIG. 4B illustrates abase material 262 that does not have a layer-like structure. In one embodiment, parts of theelements 140 may have non-layer structural characteristics. In addition, asurface 264 defined bysuch base material 262 may also be powder coated so as to form apowder coating layer 270 having athickness 272. In various embodiments, thepowder coating layer - It should be appreciated by those skilled in the art that any number of powder coating materials may be used to form the powder coating layers for the elements without departing from the scope of the present teachings. Additionally, it should be appreciated that the type of powder coating particles and the thickness of the layer may vary depending on factors such as intended application and operating conditions of the
heat exchanger 100. -
FIG. 5 illustrates one embodiment of anoverall process 280 for fabricating a heat exchanger having power coatedelements 140. Theprocess 280 begins atstart state 282, and in astate 284 that follows, theheat exchanger elements 140 are prepared for assembly. Such preparation may include manufacturing or acquiring the elements or components of theelements 140. Instate 286 that follows, theelements 140 or the components of theelements 140 are powder coated. The powder coating step will be described in greater detail herein below. Following, in astate 288, theelements 140 are assembled. Theprocess 280 terminates in anend state 290. -
FIG. 6 illustrates one embodiment of aprocess 300 for powder coating theheat exchange elements 140. It should be appreciated by those skilled in the art that such a process may occur instate 286 of the heatexchanger fabricating process 280 described above in reference toFIG. 5 . In one aspect, thepowder coating process 300 is performed on the components of theelements 140. Advantageously, powder coating may be applied to the separate layers of theelements 140 so as to improve the uniformity of powder application. - In one embodiment, the
process 300 begins atstart state 302, and instate 304 that follows, the surface of the element is prepared for powder coating. Such preparation may include cleaning and other pre-powder application processes that are generally known in the art. Proceeding tostate 306 that follows, theprepared elements 140 are electrically connected to a selected electrical potential. In various implementations, such connection comprises electrical grounding of theelements 140. Next, instate 308, electrically charged coating particles are sprayed onto theelements 140. In one aspect, theelements 140 may be held at the selected electrical potential, which attracts the charged coating particles to the surface of theelements 140 and promotes adhesion thereto. Following, instate 310, theelements 140 with the applied coating particles are cured so as to cause the coating particles to substantially fuse with the surface of theelements 140 to thereby form a durable and resilient coating on theelements 140. Next, theprocess 300 terminates in anend state 312. - Advantageously, the Dupont based coating material, as previously described above with reference to
FIGS. 4A-4B , may be used to achieve the approximate 975° F. operational temperature limit. In this embodiment, the curing process instate 310 comprises baking the coated components of theelements 140 for approximately one hour at a temperature of approximately 1200° F. It should be appreciated by those skilled in the art that the use of different coating materials may dictate different curing procedures. - In one embodiment, the
heat exchange elements 140 and theheat exchangers 100 fabricated in the foregoing manner provides various advantages over conventional types of coatings. Traditionally, theheat exchange elements 140 are typically dipped in an enamel material to form an enamel coating. Unfortunately, this type of coating is susceptible to air pockets being trapped within the coating layer, which can adversely affect the durability and reliability of the coating layer. Additionally, the enamel coating is likely more susceptible to cracking when subjected to mechanical stresses. These mechanical stresses may arise, for example, during assembly of the heat exchanger when the elements are pressed together to form the segment, such as segment 130 inFIG. 2 , which can also be referred to as a “basket”. Moreover, additional mechanical stresses may be induced by thermal fluctuations and/or vibrations associated with the operation of the heat exchanger. Unfortunately, cracks and other breaches of the enamel coating exposes the underlying base layer to potentially corrosive materials. For example, if the heat exchanger is cleaned by a spray of water, the water can work its way into the metal and promote corrosion. The corrosive effects may be exacerbated if the air contains corrosive particulates, such as sulfur based compounds. - Advantageously, the powder coating of the
heat exchange elements 140 of the present teachings as described herein above provide improved mechanical durability, resiliency, and performance to thereby provide improved corrosion resistance.FIG. 7 illustrates one possible application of theheat exchanger 100 having powder coatedelements 140 in a harsh operating condition. For example, fossil fuel burning power generators typically comprise aboiler 320 that burns the fossil fuel to generate heat. As illustrated inFIG. 7 ,arrows 330 indicate the flow of a flue gas that results from the burning and is eventually ejected into the atmosphere. In some generators, the flue gas from theboiler 320 may pass through a selective catalytic reduction (SCR)reactor 322 to remove a substantial portion of Nox present. The flue gas, whether from theboiler 320 or from theSCR reactor 322, then typically passes through aheat exchanger 324 to lower the gas temperature prior to being processed in anexhaust processor 326. It should be appreciated that theexhaust processor 326 may comprise an electrostatic precipitator that collects particulates from the gas and a smoke stack that ejects the gas to the environment. - As further illustrated in
FIG. 7 , the gas passing through theheat exchanger 324 may comprise a relatively high temperature and a relatively high concentration of particulates including sulfur based compounds. Therefore, the particulates may likely accumulate on theheat exchange elements 140, which may likely require routine cleanings. Because the powder coating on theelements 140 provides improved mechanical durability, resiliency, and performance in a manner described above, the corrosive effects are mitigated in an improved manner. Advantageously, the powder coating of theheat exchange elements 140 may withstand high operating temperatures with selected coating materials, such as the previously described Dupont based powder coating having a relatively large operational temperature limit. Therefore, theheat exchanger 100 having the powder coatedheat exchange elements 140 of the present teachings are advantageously suited for high temperature and high sulfur environment applications, such as the fossil burning generators. - In some embodiments, powders used for coating preferably result in the coating having properties that are desirable for heat exchanger applications. These desirable properties include resiliency of the formed coating, high acid resistivity, and robust adherence to the underlying metal surface. Additionally, the powders preferably inhibit the adherence of sulfur-based particles to the powder coated surface and decrease the accumulation of particles on the surface of the
elements 140. Powders that result in such properties in the heat exchanger applications can include commercially available products such as those from Cardinal Industrial Finishes of City of Industry, California. - One such powder comprises an E305-GR533 epoxy powder coating formulation. The E305 has a specific gravity of approximately 1.56, with an average particle size of approximately 25-50 microns. The E305 powder coat can be cured by heating at approximately 400 degrees F. for approximately 10 minutes.
- An exemplary E305 coat of approximately 2.0 to 4.5 mils thickness has a direct impact value of approximately 60 in-lbs using an industry D2794 method, and an indirect impact value of approximately 60 in-lbs using the same method. The exemplary coating has a pencil hardness in the “2H” category using the industry D3363 method.
- The E305 has been designed to be applied by electrostatic spray on metals such as steel, galvanized steel, or aluminum, and the resulting coat has a good to excellent chemical resistance to most solvents, oils, acids, and alkalies. Advantageously, the E305 powder can be reclaimed, sieved, and recycled.
- Another powder available from Cardinal comprises a P004-GR16 polyester polyurethane powder coating formulation. The intended application, recyclability, chemical resistance property, and pencil hardness are similar to that of the E305 formulation. The P004 powder coat (of an exemplary coating thickness of approximately 1.5 to 3.0 mils) has direct and indirect impact values of approximately 120 in-lbs. Such a coating can be achieved by heating the powder coat for approximately 12 minutes at approximately 400 degrees F.
- Another powder available from Cardinal comprises a H305-GR10 epoxy polyester hybrid powder coating formulation. The intended application, recyclability, chemical resistance property, impact values and pencil hardness are similar to that of the P004 formulation. In addition to the chemical resistance property, the H305 coating provides an excellent resistance against salt spray and humidity. Using the industry ASTM B117 method, the H305 coating exhibits approximately 1,000 hours of salt spray with less than approximately ⅛ inch creep from a scribe. Using the industry ASTM D2247 method, the H305 coating exhibits approximately 1,000 hours of humidity exposure with substantially no loss of adhesion or blistering. Such a coating can be achieved by heating the powder coat for approximately 10 minutes at approximately 400 degrees F.
-
FIG. 8 illustrates another embodiment of aprocess 500 for powder coating components of theheat exchanger 100. In one embodiment, the powder coating is applied to theheat exchange elements 140. In another embodiment, the powder coating is applied to seals (radial 64 or axial 70) between theradial walls 107 and the housing 104 (SeeFIG. 1 ). Such seals are described in U.S. Pat. Nos. 5,950,707 and 5,881,799, the entire contents of which are incorporated by reference and should be considered a part of this specification. -
FIG. 9 illustrates one embodiment of aseal assembly 72, which can be used with theheat exchanger 100. In one embodiment, theseal assembly 72 can be theradial seal 70, wherein theseal assembly 72 is mounted on an outer surface of theradial wall 107 and provides a secure seal between theradial wall 107 and an inner surface of thehousing 104. In this embodiment, theseal assembly 72 preferably inhibits leakage or bypass flow between the cold air conduit and the hot gas conduit through the area between the outer surface of theradial wall 107 and the inner surface of thehousing 104. In another embodiment, theseal assembly 72 can be theaxial seal 64, wherein theseal assembly 72 is mounted on the outer radial edge of theradial wall 107 and provides a secure seal between the top or bottom edge of theradial wall 107 and an inner surface of thesector plates housing 104. In this embodiment, theseal assembly 72 preferably inhibits leakage or bypass flow between the cold air conduit and the hot gas conduit through the area between the top or bottom edge of theradial wall 107 and an inner surface of thesector plate housing 104 - The
seal assembly 72 includes an elongate and generally flat mountingstrip 74. Preferably, the mountingstrip 74 extends along the entire length of theseal assembly 72 and has afront surface 74 a and arear surface 74 b. A series ofelongated apertures 80 extend through the mountingstrip 74 and are distributed along the length of the mountingstrip 80. - The
seal assembly 72 also includes aresilient section 82. In one embodiment, theresilient section 82 is bellows-shaped. In the illustrated embodiment, theresilient section 82 has a series ofcorrugations 83 that extend in and out of a plane defined by the mountingstrip 74 and are configured to compress and allow theresilient section 82 to act as a spring. Theresilient section 82 has a front surface 82 a and arear surface 82 b. - The
seal assembly 72 also includes a sealingstrip 84 that extends outward from theresilient section 82 opposite the mountingstrip 74. The sealingstrip 84 preferably extends in a direction substantially parallel to a plane defined by the mountingstrip 74 and has afront surface 84 a and arear surface 84 b. The sealingstrip 84 also has a substantially straightouter edge 86. In one embodiment, where theseal assembly 72 is theradial seal 70, the sealingstrip 84 preferably seals the juncture between theradial wall 107 and an inner surface of thehousing 104. In another embodiment, where theseal assembly 72 is theaxial seal 64, the sealingstrip 84 preferably seals the juncture between the top or bottom edge of theradial wall 107 and an inner surface of one of thesector plates housing 104. -
FIG. 10 shows a side view of theseal assembly 72 used as theaxial seal 64. In the illustrated embodiment, the sealingassembly 72 is mounted to the top edge of theradial wall 107 via at least onebolt 90 extending through theapertures 80 in the mountingstrip 74 and through theradial wall 107. Anut 92 is screwed onto thebolt 90 to secure the mountingstrip 74 to theradial wall 107. However, one of ordinary skill in the art will recognize that other mechanisms can be used to secure the mountingstrip 74 to theradial wall 107, such as welds and adhesives. - As shown in
FIG. 10 , various surfaces of theseal assembly 72 are exposed to the environment, which as discussed above, can induce corrosion of the metal in theseal 72. As seen inFIG. 10 , therear surface 74 b of the mountingstrip 74 is disposed adjacent theradial wall 107, reducing the exposure of therear surface 74 b to the environment. However, the front andrear surfaces 82 a, 82 b of the resilient section, and the front andrear surfaces radial seal 70, the exposure of therear surface 74 b of the mountingstrip 74 would be reduced, while the rest of thesurfaces -
FIGS. 11A-13 illustrates another embodiment of a seal assembly. In the illustrated embodiment, the seal assembly is a perimeter orcircumferential seal assembly 430. In one configuration, shown onFIG. 11A , theseal assembly 430 is fixedly attached to therotor 102. Theseal assembly 430 can be attached to therotor 102 in any suitable manner. For example, in one embodiment theseal assembly 430 can be welded to therotor 102. In other embodiments, theseal assembly 430 can be bolted to therotor 102 or fixedly attached to therotor 102 via a clamp. Theseal 430 includes a mountingsection 432 and asealing section 434. In the illustrated embodiment, the mountingsection 432 is attached to anouter wall 422 of therotor 102 and a mountingplate 436. Theseal 430 is preferably bent so that thesealing section 434 is positioned substantially adjacent a sealingsurface 442 a which, in the illustrated embodiment, comprises aninner wall 424 of thehousing 104. The mountingsection 432 has afront surface 432 a and arear surface 432 b. In the illustrated embodiment, thefront surface 432 a is adjacent theouter wall 422 and therear surface 432 b is adjacent the mountingplate 436. Likewise, thesealing section 434 has afront surface 434 a and arear surface 434 b. In the illustrated embodiment, thefront surface 434 a faces toward theinner wall 422 and therear surface 434 b faces toward therotor 102. Preferably, theseal 430 extends substantially across abypass gap 420 so as to inhibit the ability of intake air or exhaust gas to bypass therotor 102. - As discussed above, various surfaces of the
seal assembly 430 are exposed to the harsh environment proximal theheat exchanger 100, which can induce corrosion of the metal in theseal 430. As seen inFIG. 11A , the front andrear surface strip 432 are disposed adjacent theouter wall 422 of therotor 102 and mountingplate 436, respectively. Therefore, the exposure of thesurfaces section 432 to the corrosive environment may be reduced. However, therear surface 434 b of thesealing section 434 faces therotor 102 and is exposed to the harsh corrosive environment. Thefront surface 434 a of thesealing section 434 faces away from therotor 102, which may reduce the exposure of thefront surface 434 a to the corrosive environment due to the sealing effect of thesealing section 434 against theinner surface 424 of thehousing 104. -
FIG. 11B illustrates another configuration of theperimeter seal 430 mounted in thebypass gap 420 to inhibit intake air or exhaust gas from bypassing therotor 102. In the illustrated embodiment, the mountingsection 432 is bolted to theinner wall 424 of thehousing 104, preferably adjacent the upper and lower ends of thehousing 104. However other mechanisms can be used to attach the mountingsection 432 to theinner wall 424, such as welds. In the illustrated embodiment, thesealing section 434 extends into thebypass gap 420 so as to be positioned adjacent a sealingsurface 442 b. In the illustrated embodiment, the sealingsurface 442 b is a sealingplate 456 that extends circumferentially around therotor 102. In the illustrated embodiment, thefront surface 432 a of the mountingsection 432 faces generally toward therotor 102, while therear surface 432 b is adjacent theinner wall 424. Similarly, thefront surface 434 a of thesealing section 434 faces generally toward therotor 102, while therear surface 434 b faces generally toward theinner wall 424. - As seen in
FIG. 11B , therear surface 432 b of the mountingstrip 432 is disposed adjacent theinner wall 424 of thehousing 104. Therefore, the exposure of therear surface 432 b of the mountingsection 432 to the corrosive environment may be reduced. However, thefront surface 432 a of the mountingsection 432 faces therotor 102 and is exposed to the harsh corrosive environment. Likewise, thefront surface 434 a of thesealing section 434 faces therotor 102 and is exposed to the corrosive environment. Therear surface 434 a of thesealing section 434 faces away from therotor 102, which may reduce the exposure of thefront surface 434 a to the corrosive environment due to the sealing effect of thesealing section 434 against the sealingplate 256. -
FIGS. 12 and 13 illustrate further details of theperimeter seal 430. Theseal 430 comprises afirst seal member 430 a and a second seal member 430 b, both of which include mountingsections 432 and sealingsections 434. The first andsecond seal members 430 a, 430 b each have a series of alternatingtabs recesses 447, wherein thetabs 435 a of thefirst seal member 430 are configured to fit through the slots 437 b of the second seal member 430 b to engage thetabs 435 b of the second seal member 430 b, and vice versa. - In particular, alternating
neck sections 443 of the tabs 435 are positioned in the rectangular recesses 437. Theneck sections 443 of the tabs 435 preferably do not significantly overlap, however, the sealing upper sections 442 of the tabs 435 do overlap. Each tab 435 is preferably positioned in the slots so that a firstlateral side 460 a of atab 435 a on thefirst member 430 a is positioned adjacent afirst face 452 of afirst tab 435 b on the second member 430 b. Thetab 435 a on thefirst member 430 a then has abent section 454 so that a secondlateral side 460 b of thetab 435 a is positioned adjacent asecond face 454, opposite thefirst face 452, of the second tab 235 c on the second member 430 b. Further details of theperimeter seal 430 are provided in U.S. Pat. No. 5,881,799. - With continued reference to
FIG. 8 , theprocess 500 includes thestep 510 of preparing the surface of the component to be coated. In one embodiment, where the component is a seal, the seal can be made of AISI 4130 normalized steel. However, one of ordinary skill in the art will recognize that other suitable materials can be used. In thepresent step 510, a line grain is preferably produced on the surface of the component. Said line grain preferably provides a textured finish with a porous effect to facilitate the application of the powder coating to the component surface. In one preferred embodiment, the line grain is formed on the surface in a generally linear direction to provide a brushed finish. In another embodiment, the line grain can be formed on the surface of the component in a generally non-linear direction. Preferably a 60 grit Iron Oxide Belt is used to form said line grain. However, any suitable mechanism can also be used to form the line grain. In one embodiment, where the component being coated is a large seal, the surface is preferably sandblasted following the line grain formation process. Preferably, the surface is sandblasted with aneven texture 80 grit aluminum oxide media. However, any other suitable media can be used. - Following the
surface preparation step 510, the component surface is preferably cleaned, as illustrated inStep 520. In one embodiment, an Iron phosphate wash is applied to the component surface to clean the surface. Preferably, the wash substantially removes oil and waste material generated in thesurface preparation step 510 from the component surface. In a preferred embodiment, the wash is applied so as to provide a coating of between about 300 mg/m2 and about 900 mg/m2. In a preferred embodiment, step 520 also includes application of a rinse of the component surface. In one embodiment, the component surface is rinsed with de-ionized water. In another embodiment, the component surface is rinsed with regular water. The component is then heated (i.e., baked) to remove moisture from the component surface. In one embodiment, the component is baked at a temperature of between about 50 deg. F and about 500 deg. F for a period of between about five minutes and about two hours. In another embodiment, the component is baked at a temperature of about 400 deg. F for a period of about 20 minutes. However, other suitable mechanisms known in the art can be used to remove moisture from the component surface. - The
process 500 also includes thestep 530 of applying the powder coating to the component surface. Preferably, the powder coating is sprayed onto the component surface. In one embodiment, the powder coating is epoxy resin model Resicoat R4-ES HJF14R (500547) from Akzo Nobel of The Netherlands. However, other suitable powder coating materials can be used that have similar corrosion resistance, chemical resistance, heat resistance, impact resistance, flexibility and adhesion characteristics. Preferably, the powder coating is applied using the ISO 8130-2 procedure and preferably results in a coating thickness of about 3-5 mils. In another embodiment, the procedure results in a coating area density of between about 1.55 and about 175 grams per cm2. - Following the application of the powder coating to the component surface (Step 530), the component surface is preferably cured (Step 540). In one embodiment, the component is preheated to a desired temperature. In one embodiment, the component surface is preheated to a temperature of between about 50 deg. F and about 600 deg. F for a period of between about 3 minutes and about 2 hours. In another embodiment, the component surface is preheated to a temperature of about 320 deg. F for a period of about 5 minutes. The component surface is then cured. In one preferred embodiment, the component surface is cured at a temperature of between about 50 deg. F. and about 1000 deg. F for a period of between about five minutes and about two hours. In another embodiment, the component surface is cured at a temperature of about 400 deg. F for a period of about 20 to 30 minutes. Preferably, the powder coating achieves a hardness in the range of between about HB and 5H during the curing process using, for example, an ASTM Method D3363 pencil hardness standard. One of ordinary skill in the art will recognize that the application (Step 530) and curing (Step 540) of the component surface can in some embodiments be performed intermittently.
- Following the curing of the powder coating (Step 540), the component can optionally be inspected (Step 550). In a preferred embodiment, component is inspected to ensure that the coverage and the surface texture flow of the powder coating is within a desired range. For example, the component surface can be inspected to ensure the surface texture flow meets a desired smoothness.
- In one embodiment, the
heat exchanger 100 is assembled following the powder coating of the components. For example, where the components are seals, the powder coatedseals walls 107 and theheat exchange rotor 102 mounted within thehousing 104. - Although the above-disclosed embodiments of the present teachings have shown, described, and pointed out the fundamental novel features of the invention as applied to the above-disclosed embodiments, it should be understood that various omissions, substitutions, and changes in the form of the detail of the devices, systems, and/or methods illustrated may be made by those skilled in the art without departing from the scope of the present teachings. Consequently, the scope of the invention should not be limited to the foregoing description, but should be defined by the appended claims.
Claims (19)
1. A component for use in a regenerative heat exchanger having a heat exchanging body and a housing, the component attachable to the heat exchanging body, the component comprising:
one or more elements configured to facilitate heat exchange with a gas that flows through the heat exchanging body during operation of the heat exchanger,
wherein the one or more elements include a protective coating disposed on an underlying surface thereof, the protective coating comprising a resilient powder coating having a coating thickness configured to inhibit cracking during flexion of the elements and further configured to inhibit corrosion inducing agents from contacting the underlying surface of the one or more elements to inhibit corrosion of the elements while not inhibiting heat transfer between the elements and said airflow.
2. The component of claim 1 , wherein the protective coating has a contact area density of between about 1.55 g/cm2 and about 6 g/cm2.
3. The component of claim 2 , wherein the contact area density is between about 1.55 g/cm2 and about 2.5 g/cm2.
4. The component of claim 1 , wherein the thickness of the powder coating on said underlying surface is between about 1.5 mils and about 2.5 mils, said thickness configured to inhibit said corrosion inducing agents from contacting said underlying surface of the elements to thereby resist corrosion of the one or more elements.
5. The component of claim 1 , wherein the thickness of the powder coating on said underlying surface is between about 2 mils and about 4 mils, said thickness configured to inhibit said corrosion inducing agents from contacting said underlying surface of the elements to thereby resist corrosion of the one or more elements
6. The component of claim 1 , wherein the powder coating has an operational temperature limit of up to approximately 975° F.
7. The component of claim 1 , wherein the one or more elements comprise a plurality of heat exchange elements in a heat exchange basket.
8. The component of claim 1 , wherein the coating has a hardness of between about HB and about 5H per an ASTM Method D3363 pencil hardness standard.
9. The component of claim 1 , wherein the powder coating has a direct and indirect impact value of between 60 in-lbs and 120 in-lbs using an ASTM Method D2794 impact standard.
10. The component of claim 1 , wherein the one or more elements comprise one or more radial or circumferential seals coupleable to the heat exchanging body.
11. A component for use in a regenerative heat exchanger having a heat exchanging body and a housing, the component attachable to the heat exchanging body, the component comprising:
one or more elements configured to facilitate heat exchange with a fluid that flows through the heat exchanging body during operation of the heat exchanger,
wherein the one or more elements include a protective coating disposed on a surface thereof, the protective coating comprising a resilient powder coating configured to withstand a temperature of up to approximately 1000° F., the powder coating configured to inhibit cracking during flexion of the elements and further configured to inhibit corrosion inducing agents from contacting an underlying surface of the one or more elements to inhibit corrosion of the elements while not inhibiting heat transfer between the elements and said airflow.
12. The component of claim 11 , wherein the protective coating has a coating area density on said underlying surface is between about 1.55 g/cm2 and about 175 g/cm2.
13. The component of claim 12 , wherein the protective coating has a coating area density on said underlying surface is between about 1.55 g/cm2 and about 6 g/cm2.
14. The component of claim 13 , wherein the coating area density on said underlying surface is between about 1.55 g/cm2 and about 2.5 g/cm2.
15. The component of claim 11 , wherein the thickness of the powder coating on said surface is between about 1.5 mils and about 2.5 mils, said thickness configured to inhibit said corrosion inducing agents from contacting said underlying surface of the elements to thereby resist corrosion of the one or more elements.
16. The component of claim 11 , wherein the one or more elements comprise a plurality of heat exchange elements in a heat exchange basket.
17. The component of claim 11 , wherein the powder coating has a hardness of between about HB and about 5H per an ASTM Method D3363 pencil hardness standard.
18. The component of claim 11 , wherein the powder coating has a direct and indirect impact value of between 60 in-lbs and 120 in-lbs using an ASTM Method D2794 impact standard.
19. The component of claim 11 , wherein the one or more elements comprise one or more radial or circumferential seals coupleable to the heat exchanging body.
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Also Published As
Publication number | Publication date |
---|---|
US20060254756A1 (en) | 2006-11-16 |
WO2007019256A1 (en) | 2007-02-15 |
US7819176B2 (en) | 2010-10-26 |
US8316924B2 (en) | 2012-11-27 |
US20110094716A1 (en) | 2011-04-28 |
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Owner name: SQUARE 1 BANK, NORTH CAROLINA Free format text: SECURITY AGREEMENT;ASSIGNOR:PARAGON AIRHEATER TECHNOLOGIES, INC.;REEL/FRAME:032336/0076 Effective date: 20110907 |
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