CA1322275C - Method and apparatus for controlling thermal environment in a glass fiber forming process - Google Patents
Method and apparatus for controlling thermal environment in a glass fiber forming processInfo
- Publication number
- CA1322275C CA1322275C CA000586221A CA586221A CA1322275C CA 1322275 C CA1322275 C CA 1322275C CA 000586221 A CA000586221 A CA 000586221A CA 586221 A CA586221 A CA 586221A CA 1322275 C CA1322275 C CA 1322275C
- Authority
- CA
- Canada
- Prior art keywords
- heat
- fin
- heat transfer
- transfer fluid
- water
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F3/00—Plate-like or laminated elements; Assemblies of plate-like or laminated elements
- F28F3/12—Elements constructed in the shape of a hollow panel, e.g. with channels
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
- C03B37/0203—Cooling non-optical fibres drawn or extruded from bushings, nozzles or orifices
- C03B37/0209—Cooling non-optical fibres drawn or extruded from bushings, nozzles or orifices by means of a solid heat sink, e.g. cooling fins
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F1/00—Tubular elements; Assemblies of tubular elements
- F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
- F28F1/12—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only outside the tubular element
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F27/00—Control arrangements or safety devices specially adapted for heat-exchange or heat-transfer apparatus
-
- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Abstract
ABSTRACT OF THE DISCLOSURE
A method and apparatus for controlling a glass fiber forming environment is disclosed. A fin cooler having a plurality of hollow cooling fins, each provided with a coolant liquid flow passage and further having a header block provided with separate coolant liquid inflow and outflow channels, is placed in a closed loop coolant liquid circulation network. Water may be employed as the coolant, but preferably a heat transfer liquid having a boiling point higher than water, low vapor pressure, and a high specific heat values is used as the coolant liquid. The heat transfer liquid takes on heat from the glass fibers as it passes through the cooling fins, and gives up this heat in a heat exchanger which may use plant process water or forced air as the secondary heat transfer medium. By regulating fluid flow, fin temperature can be manipulated to improve process control and product uniformity. The cooling fins operate at a temperature high enough to prevent glass volatiles form condensing on the fin surfaces and to prevent the formation of fin corroding acids. The closed loop cooling path prevents fin coolant passage occlusion or clogging.
A method and apparatus for controlling a glass fiber forming environment is disclosed. A fin cooler having a plurality of hollow cooling fins, each provided with a coolant liquid flow passage and further having a header block provided with separate coolant liquid inflow and outflow channels, is placed in a closed loop coolant liquid circulation network. Water may be employed as the coolant, but preferably a heat transfer liquid having a boiling point higher than water, low vapor pressure, and a high specific heat values is used as the coolant liquid. The heat transfer liquid takes on heat from the glass fibers as it passes through the cooling fins, and gives up this heat in a heat exchanger which may use plant process water or forced air as the secondary heat transfer medium. By regulating fluid flow, fin temperature can be manipulated to improve process control and product uniformity. The cooling fins operate at a temperature high enough to prevent glass volatiles form condensing on the fin surfaces and to prevent the formation of fin corroding acids. The closed loop cooling path prevents fin coolant passage occlusion or clogging.
Description
~ ~3~227~
Field of the Invention The present invention is direc~ed ~etlerally to a method and appaLatus for controlling a glass fiber forming process. More particularly, the present invention i~ directed to a method and apparatus for controlling the thermal envi~onment in a forming process by utiliza~ion of fin coolers having heat transfer liquid flow channe~s therein. Still more particularly, the present invention is dlrected to a method and apparatus for cooling glass fiber~ utilizing a heat exchange flu~d which ls passed in a closed loop system through heat transfer fins and heat exchange equipment.
In the preferred embodiment of the invention, the heat transfer fluid employed i9 one that has a boiling point above that of water A~ though water can be employed if its operating temperatures are controlled within certain limits. The preferred heat transfer fluid is also one having a speci~lc heat of at least 0.5 calories per degree Centigrade per g~ (cal/C/gm) and a vapor pressure below 1 atmosphere at temperatures of 400F and below. Each heat transfer fin has an elonga~ed flow pas~age formed withln it so that the hea~ exchange fluid can flow through the full length of each fin in the fin cooler assemhly. When high fin temperatures are es~ablished and maintained in accordance with ~3~227~
the metllods and apparatus of the present invention, i.e., temperatures above 150F, fin cooler life ls prolonged and heat transfer fin fouling from corrosion products is substantially reduced. Uniform and controlled fin temperatures at and above 150F which are obtained in accordance with ~he method and apparatus of the present invention further resu]t in improved product uniformity. i.e., consistent fiber diameters, improved running efiiciency, improved yardage uniformity and higher productivity.
_ scri~tion of the Prior Art Glass flbers sre typically formed by 1Owing molten glass through a large number of closely spaced orifices located in a container which holds the molten glass. Such containers or bushings often have 2000, 4000, or even up to 6000 of such glass fiber forming tips or orifices. The molten glass which flowa out through these arràys of bushing tips must be cooled in a controlled manner so that the glass fibers or filaments which are formed from the molten glass will be substantlally uniform in diameter.
A plurality oL generally planar, solid, elongated cooling fins are placed beneath the bushing tip plate and extend generally perpendicularly to the elongated rectangular bushing with the glass fibers or filaments passing between adjacent cooling fins and giving up heat to the fins. This heat transferred to the usually solid ~lat metal cooling fins is then transferred along the fins by conduction to a header block in whieh one end of the fin is embedded and whlch header block typically is provided with flow passages through whlch a relatively colcl cooling fluid such as the plant cooling water passes. Heat is removed from the header blocks by the transfer of heat to the cooling water ~3~227~ -passing through them and the cooling flns are then kept at a relatively low temperaturc at their junction with the header. The free ends of the Eins on the other hand are substantially ~armer than the ends in the header block thereby giving rise to large temperature variations across the fin surfaces.
With the advent of longer and wider bushing assemblies having 4000 to as many as 6000 glass forming orifices, heat removal has become more difficult necessitating the use of cooling fins that have been made longer 80 that they eY~tend across the width of the bushing assembly.
This increased cooling fin length has given rise to even higher free end fin temperatures in presently used commercial solid fins. These high free end fin temperatures that are caused by inadequate heat transfer rates from ~he free end of the fin to ~he fin cooler header block have caused excessive free fin end oxidation and distortion that leads to a short fin cooler life. The cooler portion of the fin surfaces also accumulate solids which corrode surfaces and require cleaning. Frequent fin cooler cleaning or replacement is expensive and disruptive of bushing operation with its concomitant 106s of productivity.
In addition, textile fiber glass strand products typically require higher levels of product uniformity than strand products used to provide rovings for resin reinforcement, Eor example. Textile glass fiber strands are used to manufacture cloth used for reinforcing high pressure laminates typically employed in circuit boards or for manufacturing decorative fabrics. These glass Piber strands have to be produced at a high level of product uniformity, consistent yardage per pound oL glass fiber being one criteria. Consistent yardage i5 one indicator of uniform fiber diameters in a given strand. The use of the ,1~2~P~
current commercia] solid cooling fins has not provided the deslred properties to textile fibers in many instances on a reproducible basis.
Further, slnce the cooling capabilities of the current solid fins are son~ewhat limitedl forming tensions for textile fibers tend to be high and the glass throughput from the bushings making these fibers is low.
Attempts have been made to provide fin cooler assemblies in which the lndividual fins are hollow so that plant cooling water can be pas~e~l throu~h the fins. Exemplary of prior art patents which disclose s~h cooled fln coolers are U.S. patents 3,251,665; 3~695,85O; and 3,746,525. Past attempts at operating cooled fin coolers have me~ with only marginal success and these fin coolers have not been wldely used by the glass fiber forming industry. Several general problems appear to be typical of prior art water cooled fin coolers. The flow of pla~t p~ocess or cooling water through the fins has produced fin temperatures which are una~ceptably low, i.e~. temperatures in the range of 70F to 100F on portions of the fins. These low temperatures on fin surfaces cause glass volatiles to condense out on the surfaces of the cooling fins causing unaccep~ably hlgh corrosJon rates and short fin life. Contamlnant build Up Otl the surfaces of the cooling fins also alters their heat transfer characteristics and creates noDuniformity in the glass fibers produced since the glass cooling is not uniform or consistent. The low temperature of the cooling fins caused by flow of coolant water through passages in the fins also allows the glass volatiles to mix with water in the environment nor~2ally present around a bushing to form corrosive acids that shorten fin llfe.
Further, ordinary plant (~ooling water may not be completely free of entrained solid particles and contaminants. As this water flows 2 ~ ~
through the relatively small paBSageS in the fins of the prlor art water cooled fin coolers, t~le flow passages may also become plugged or occluded. Such passage plugging in a ~in renders the cooling fin inoperative and causes rapid failure of such a fin. In a large bushing assembly havlng a correspondingly large number of water cooled fins, the inoperativeness of random cooling fins caused by coollng water flow passage fouling will cause the heat transfer rates to vary from cooling fin to cooling fin. Strand slzes wlll thus vary, the product formed will have non-uniform filament diameters as a consequence and will therefore be unacceptable. Water coolant flow passage clogging ln indivldual cooling fins is difficult to correct and requires the entire fin cooler be removed from the bushing assembly and repaired. These shutdowns are, of course, disruptive of production schedules and interfere with plant productivity.
As can thus be appreciated, there is a need in the glass fiber forming industry for a fin cooler which will be operable in a controlled.
dependable manner so that fin surface temperature can be maintained high enough to reduce corrosion effects to acceptable levels and insure that temperatures be more uniform across the entire surface of the fln.
Further, the cooled fin cooler must be able to operate free from distortions caused by inadequate cooling and must not be susceptible to failure due to Elow passage clogging.
It is an ob~ect of the pre9ent disclosure to provide a method and apparatus for controlling a glass flber forming process.
1 3 ~
Another object i~ to provlde a method of controlling glass fiber forming environment using a fin cooler with substantially unlform temp~ture fins.
A further object is to provide a fin cooler having heat transfer liquid flow passages therein and a heat transfer fluid system connected thereto and flowing through tbe passages to thereby maintain fln temperatures sufficiently high to minimi~e fin corrosion due to the condensation of volatiles ad~acent to the fins.
Still another ob;ect i~ to provide a method of controlling glass fiber forming utilizing a high specific heat fluid at controlled temperatures and rates of flow to provide a uniform environment around the fiber glass forming orifices or tips and uniform fin temperatures in the fin coolers used therein.
Yet a further ob;ect is to provide a method and apparatus for controlling a glass fiber forming environment utilizing a closed loop heat exchange fluid flow path at preselected operating temperatures, flow rates and heat removal rates.
Still yet another object is to provide a method of control~ing a glass fi~er forming process using a heat transfer fluid having a higher boiling point than water and a heat ex hanger to remove heat from the system.
As will be presented in greater detail in the description of the preferred embodiment which is set forth subsequently, the present disclosure is directed to a method and apparatus fo~1- rontrolling glass fiber forming by attenuating molten glass fibers formed by a multiple orifice bushing assembly, A plurality of generally flat cooling fins, which are attached at first ends to header blocks to form fin coolers, ~
.
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are placed benctlth the bushing tip plate. As the glass fibers pass between the spaced fins, the thermal environment area around the fins is controlled by transferring heat from the glass to the cooling fins while stabilizlng the surface temperature of the fins. Each of these fins includes an interior, generally elongated U-shaped flow passage with an inlet port of this fin flow passage being in communicatlon with a heat transfer fluid inflow channel in the fin cooler header block and with an out]et port from each fin heat transfer fluid flow passage being in communication with a separate outflow channel in the header block.
A heat transfer fluid having a hlgh specific heat and which has a boiling point substantially higher than that of water and a vapor pressure at its operatlng temperature of less than 1 atmosphere is prefer~bly used and is caused to flow in a closed loop through the fins and out. The outgoing fluid is then passed through a heat exchanger.
Thus, heat i5 extractPd from the glass fiber filaments by the flns adJacent thereto, transferred from the fin surface to a heat transfer fluid and the heat is then transferred to a secondary heat exchange fluid such as plant process water in a separate heat exchanger connected to the fln cooler.
"High specific heat" as used herein means a specific heat of at least .5 cal/C/gm, preferably in the range of .6 cal/C/gm to .7 cal/C/gm. "Low vapor pressure" as used herein, means a vapor pressure at operating temperatures of less than 1 atmosphere.
Selection of the heat exchange fluid and lts rate of circulation through the cooling fins and the rate at which heat is removed from it in the heat exchanger are parameters that are adjusted to insure that the surface portions of the cooling fins are maintained at a ~322~7~
temperature oE 150 to 400F, preferably in the range of 150 to ~00F.
Surface temperatures in the pre~erred range are high enough to prevent Lhe formation of glass volatile contaminants on the surfac~ of the cool.ing fIns by condensation from the adJacent environment. In contrast to prior water ~ooled fins, the use of heat transfer fluid in a c].ose~l loop F.ystem here descrlbed will maintain the fin surfaces at a temperature higher than pnssible with water passing in the pr~or art non-cl.osed loop s~stem because of the abili~y to precise].Y
control the temperature of the heat transfer fl~id ln the fins. Aeid formation due to the mixing of glass vo~atile components with water condensate on the fin surfaces should thereby be minimlzed due to the elevated fin surface operating temperatures that are provided hv the ose of a high specific heat, high boiling temperatllre heat exchange fluid and the closed loop system while adequate heat removal from the glass filaments ad~jacent the fins is still accomplished.
The heat exchange fluid flows in a closed loop This flow path is continuous and extends between the flow path in the individual coollng flns, through the header block, to a heat exchanger unit that removes the heat from the heat transfer fluid through a filter and back through the cooling fins for further thermal treatment. This closed flow path prevents the clogging or plugging of flow passages in the cooling fins as was apt to be the situation with prior art open loop water cooled fins that generally u~ilized plant process water for cooling. Since the individual coolant flow paths in the various coollng fins are no longer apt to become plugged by inorganic o~ide deposits, the frequency of in cooler failure and failure related production interruptions are .~ - 8 -~3~2~
substantially reduced. When water is employed as the cooling fluid, utillzation of distilled water is preferred, The fin cooler here described in a preferred embodiment of the present invention and :Lts method of usage with a high speciflc heat, high boiling temperature heat transfer f].uid f].owing in a cl.osed loop provldes a fin cooler which has a reduced tendency to accumulate glass vo].ati].e contaminants thereon or to be subjected to attack by corrosive ncids l~ecause of its ahility to m~i.nta~ll elevated surface temperatures, while still acting as a cooling surface for the glass fibers. SimlJ.ar].y, where water is employed, the same benefits accrue so long as temperatures of the circu]ating water are ma-lntained above 150F. lJniform fin temperature Is provided by clrculat-Lon of the heat transfer fluid throllgh the fin so that fin distortion and oxidation is not a concern. The closed loop fluid circulatlon system allows the heat transfer fluid to remain clean and provides a means for controlling fin surface temperatures bv contro].].ing the heat transfer fluid temperature through contro~led heat removal at the heat exchanger to provide a given fin surface temperature. A controlled fin temperature is achieved by accurately controlling the secondary or plant water coolant flow throu~h the hea~ exchanger. Thus the new method and apparatus of glass fiber cooling overcomes the disadvantages of the prior art while providing a system that is effective yet remains uncomplicated and reliable.
_ g_ ~ 3~2~
Brlef Description of the Drawin~
While the novel features of the method and apparatus of cooling glass fibers in accordance with the present invention are set forth with partLcularity in the appended clalms, a full and complete understanding of the invention may be had with reference to the detailed description of the preferred embodiments as set forth hereinafter and as ~ay be seen in the accompan~ving drawings in which:
Fig. 1 is a pers~ective view of one embodiment of a fin cooler constr~lcted generally embodying the present invention;
Fi~. 2 is a cross-sectional view of the header block of the fin coo~er of Fig. 1 taken along line II-II thereof;
Fig. 3 is a side elevation view of the fin coo]er of Fig. ]y partly in section and taken along line JII-III thereof;
Fig, 4 is a cross-sectional view of one cooling fin taken along l.ine IV-IV of Fig. 3; and Fig. 5 is a schematic side elevation view of a fin cooler embodying the present invention showing the closed loop circulation path of the heat transfer fluid through the fin cooler and a heat exchanger.
Flg. 6 Ls a front elevation of a preferred embodiment of the instant invention showing the cooling fins, the header and their re]ationship to the bushing tips.
Fig. 7 is a plan view of two fin coolers of the preferred embodiment showing their positioning in the headers.
Fig. 8 is a slde elevation in cross-section of header, fin and header fluid inlet and out]et.
] I) _ .
:~22~
DescriDtion of the Preferred_Embodiments Referring initally to Fig. 1, there may be seen generally at 10 a cooled fin cooler. Cooled fin cooler 10 includes a header block generally at 12 to which are attached a plurality of outwardly extending cooling flns 14. As is known generally in the art, fin coolers of this general type are typically placed beneath the tip pl te of a glas~ fiber fllament forming bushing assembly (not shown). I~divldual glass ~ibers, which are pulled from molten glass cones formed at the bushing tip plate, are attenuated by a suitable winder or the like. Groups of these lndividual fibers pass generally downwardly between the spacsd cooling fins 14 which ~ake heat away from the glass so that the glass will be properly cooled.
In the cooled fin cooler the header block 12 is generally in the shape of an elongated rectangular bar having a top surface 16? an opposed bottom surface 18, a front face 20 and an opposed rear face 22. Each of the plurality of cooling fins 14 is attached at a first end 24 to front face 20 of header block 12 in any generally conventional manner, such as by welding or brazing, and extends outwardly therefrom in a can~ilever fashion to a second, free end 26.
As may be seen in Figs. 2 and 3, header block 12 includes a pair of spaced, separate, Plongated coolant flow channels. A coolant liquid inflow channel 28 i9 formed in the interior of header block 12 generally closer to bottom surface 18 and e~tends the length of header block 12. A
coolant liquid inflow line 30 is secured to header block 12 and supplies coolant liquid to inflow channel 28. A separate coolant liquid outflow channel 32 is formed ln header block 12 and extends the length of header block 12 ad~acent the top surface 16 thereof. Inflov ` 132227~
channel 28 and outflow channel 32 are generally parallel to each other but are completely separate from each other. A coolant liquld outlet line 34 is ln fluid communication with outflow channel 32 and provides a means for coolant liquid egress from header block 12.
Referring again to Fi.g. 3, and as may al50 bP SeeD in F~g. 4, each cooling fin 14 is provided with a generally elongated ~-shaped coolant liquid flow passage 36. Flow passage 36 in each cooling fin 14 I-as an inlet port 38 which is placed in coolant liquid inflow chamlel 28 ln header block 12. An outlet port 40 of each coolant liquid flow passage 3~ is disposed in coolant liquid outflow channel 32 of header block 12. Each coolant liquid flow passage 36 in each cooling fin 14 extends from the first end 24 of fin 14 along a lower leg portion 42 adjacent bottom portion 44 of fin 14, to ~he free end 26 of fin 14 and then back through a top leg portion 46 of fin 14, ad~acent upper edge 48 of fin 14 and back to the first end 24 of the fin 14. Coolant liquid flows into header block coolant liquid inflow channel 28 and into the lower leg 42 of coolant liquid flow passage 36 through inlet port 38.
The coolant liquid flows out to the free end 26 of fin 14 and then back through top leg 48 of flow passage 36. back through outlet port 40 and into coolant liquid outflow channel 32 in header block 12. While coolant liquid inflow channel 28 and coolant liquid outflow channel 32 in header block 12 are not in direct fluid co~munication, they are in fact in contact with each other through the plurality of coolant liquid flow passages 36 in cooli.ng fins 14.
A preferred structure of a cooling fin 14 is shown in Fig. 4 as being comprised of two similar, but opposed stamped metal panels SO and 52, each of which is formed as one side of the cooling fin 14. Each ~3222~
stamped panel 50 and 52 includes a generally elongated U-shaped recess.
When the two panels 50 and 52 are placed together and joined to each other by securement of peripheral and intermediate flange sections 54 and 56. re6pectively, by welding or the like there is formed cooling fin 14 having cooling liquid flow passage 36 therewithin. Each cooling fin 14 could be formed in one of several alternative ways to provide a generally rectangular hollow fin having a coolant liquid flow passage 36. For example, two planar metal panels could be secured together with peripheral and intermediate spacers to again define a generally U-shaped flow passage 36 in each cooling fin 14.
Turning now to Fig. 5 there may be seen a schematic re~resentation of a fin cooler and heat exchanger closed circuit for a cooled fin cooler embodyi~g the present invention. A coolant liquid, which flows through flow passage 36 in coollng fin 14, enters header block 1~ through coolant liquid inflow llne 30 and exits through coolant liquid outflow line 34 as has previously been dlscussed. During its passage through cooling fin 14, the coolant liquld takes on heat through indirect heat transfer from the glass fiber filaments which pass between the cooling fins 14. This heat must be removed from the coolant liquid and this is accomplished by passing the hot liquid through a lleat exchanger generally at 60. The hot llquid from the fin cooler lO flows through a heat excllange core 62 around which continually circulates a seccndary heat exchange fluid such as plant process water by means of a water inlet 66 and a water outlet 68 or by forced air cooling. The hot coolant liquid is cooled, and upon exiting from heat exchanger 60, is reused. The coolant liquid can thus be seen to be flowing in a closed loop in which it takes on heat in the cooling fins and gives off heat in the exchanger.
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Turning to Figs. 6, 7 and 8, there is shown the preferred embodiment of the fin cooler system. In fig. 6, a fin cooler header 71 and 72 are shown po~itioned behind and below a bufihing, 80 which has a multiplicity of Liber forming tips 81 on the bottom thereof. The tips 81 are arranged in rows and as shown, two rows of tips, 81 are positioned between the fins 74 of header 71 and fins 75 of header 72. Eluid is introduced lnto headers 71 and 72 tl)rough inlets 82 and 83 respectively. Fluid exits the header 71 and 72 through outlets 84 and 85 respectively. Flns 74 and 75 are formed of two sheets of metal which are plnched toward each other along their center line and welded together to form the U-shaped channel 86 shown in Fig. 8. The solid metal center 87 divides the fin to provide that channel 86. In the header 71 shown in Fi~. 8, a rectangular configuration is provided with a dividlng wall 88 therein to prov:lde an upper chamber 89 and a lower chamber 90. As will be readily understood, the inlets 82 and 83 and outlets 84 and 85 are connected to a heat exchanger 60 such as shown in Flg. S so that fluid circulating in the fins 74 and 75 can be treated to extract heat and supply cooled ~luid during operation.
As has been alluded to previous1y, in the preferred embodiment, the heat exchange liquid or coolant liquid which flows in the closed loop and wh~ch thus passes through tlle cooling fins 14 i9 selected from one of a number of heat exchange fluids that have a boiling point higher than water> a vapor pressure of below 1 atmosphere and a high specific heat value at operating temperature, i.e., at least 0.5/C/gm. Exemplary of heat exchange fluids which would be sui~able for such use are Hydrotherm 700-160 and Hydrotherm 750-200, manufactured by ~nerican Hydrotherm Corporation, or Dowtherm A or Dowtherm E which are made by Dow Chemical * Trademark ~322~
Company. ~lCernatively, various mineral oils or other heat exchange fluids may be used in the closed loop~ cooled fin cooler in accordance with the present invention so long as they conform to the specific heat and vapor pressure requirements. Thus, hlgh boiling alcohols such as glycerol, ethylene glycol, propylene glycol, 1,3-propanol may be used alone or diluted slightly with water, i.e.~ up to 15 to 20 percent so long as the boiling point of any such diluted alcohol is higher than water and the specific heat remains at a value of at least 0.5 cal/C/gm with a vapor pressure below 1 atmosphere at an operating fin temperature of 150F or above, preferably 150F to 200~F. These heat exchange flulds have bolling points substantially higher than water and allow the cooling fins to operate at a temperature of 150-400~ or higher, preferably 150F
to 200F.
In lnstances where water alone is employed, it should be free of contaminants, maintained at or above 150F and below its boiling point as it circulates through the fins. This temperature is controlled by the heat removal in the heat exchanger and the rate of flow of water through the closed loop in which the water flows.
The upper limit of temperatures used with material liquids other than water alone is determined by the failure polnt of the materials used in the fin and the boiling point of that liquid.
Operation in temperature ranges of this magnitude reduces the deposition amounts of glass volatiles on the fin surfaces and also reduces the tendency to form corrosive acids on the cooling fin surfaces. Although the fins operate at a higher temperature than would be the case if they were operating in accordance with the teachings of the prior art with water used in an open system as a heat transfer fluid, the difference 3. 3 2 2 2 r7 ~j between the fin temperature of 150-400F and the typical 2200~F bushing tip exit temperature o~ the glass affords good heat ~ran~fer to the fins. It has been found furtl1er that by maintainirlg a margin of generally 25 to 1~0F, preferably 50 to 100F or more between the operating temperature of the system in the fins and the boiling point of the heat transfer fluid used therèin insures th~t the fluids employed will remain in liquid form at all times in all parts of the closed system. The specific operating temperature of -he fin cooler can be controlled by proper selection of the desired heat transfer fluid and by control of the flow rate of the heat transfer fluid through the heat exchanger.
The method and apparatus for glass fiber cooling in the preferred embodiment of the present invention makes use of a heat transfer liquid having a boiling point higher than water and a high specific heat to allow the cooling fins to operate at a temperature of generally about 150 to 400F, preferably 150 to 200F. Operating in this temperature range helps prevent glass contaminant deposition on the cooling fins, provides even fin temperature distribution, and prolongs fin llfe by impeding the formation of fin corroding acids. The closed loop path of the heat ~ransfer flui~ through the cooling fins and the heat exchanger allows the use of a contaminant free heat transfer medium which will remain contaminant free during use and will not occlude or plug the coolant liquid flow passages in the cooling fins. Thus the method and apparatus for cooling glass fibers provides a substantial advance in the art. Further, benefits are provided in that, by adjustment of the fluid employed and the circulation rates through the fins and its conseguen~
effect on fin :.
11 ~22~7~
temperature, the for~ning process itself can be adjusted to alter ~la~s viscosities in the area of glass formlng cones to ad~t fiber diameters.
In a preferrecl mode operation a fin cooler was used on an 800 tip fiber glass forming bushing in a laboratory ~urnace forehearth with a 90 percent ethylene glycol - ]O
percent water mixture used as the heat tran~fer media. The media was p~mped through the fins of the fin cooler at a rate of about 500 milli]Jters per minute per fln. The fin surface temper~tures were maintained at IhOF by re~oving heat fr~m the heat transfer fluid in the fluid heat exchanger which was operated with water as the heat exchange fluid at inlet temperatures of 80F and outlet temperatures of about 15~F.
In another preferred mode of operating ten 800-tip fiber glass forming bushings were operated off a fiber glass furnace forehearth in a manufacturing plant utilizing the fin cooler system, each fin cooler having 38 fins per position. The ethylene glycol, the primary heat transfer media, circulating through the fins was a 70 percent ethylene glycol - 30 percent water mixture. This ethylene glycol-water mixture was pumped through the fins of the fin coolers on all bushings at a rate of between O.l and 0.15 gallons per minute per lndividual fin. The fin surface temperature of the fins on th~ lO bushing positionq was maintained at 160F by removing heat from the primary heat transfer media, i.e., the 70/30 ethylene glycol water mixture in a heat exchange fluid in the heat exchanger. Plant process water at approximately 80F waq fed to the heat exchanger, and the outlet temperature of the water from the heat ~3~22~
exchanger un~t was about 150F. Operating in this manner the ~ins were maintalned at the approximate 160F surface temperature during the operatlon. The fins~ except for a minor leak problem on three fins associated with the fln coolers, which were leaks at ~h~ braizing ~ointure of the fin with the fln cooler header, the operation o~ the fin system has been satisfactory and no system failures have occurred.
During the course of this run which was conducte~ on a produc~ion furnace, two bushings and associated fins were utlll~ed at the be~innin~, and as the trlal progressed, fl1rther bushings and flns were adde~ until the total number of 10 bushlngs and associated fins was achieved. One of the fin cooler posltions employed durlng the course of the ~rlal ha~
ach1eved a servlce o~ 34 week~ wltl~out any failure. It has also been obaerved when the system was utllized on these positions that a lower broken filament levels were experie~ced during the operation of the bushings than was experienced with the normal solid fins previously employed for production from bushings of this design.
While preferred embodiment~ of the present invention have been set forth fully and completely hereinabove, it will be ob~ious to one of skill in the art that a number of changes in, for example, the shape of the header block, the various fittings and connections, the structure of the heat exchanger and the like could be made without departing from the true spirit and scope of the sub~ect inventlon which is accordlngly to be limited only by the following claims. Similarly, in lieu of the preferred glycol-water used in the preferred mole various olls such as were described above can also be used. Thusl the invention is not to be limited except insofar as appears in the accompanying claims.
Field of the Invention The present invention is direc~ed ~etlerally to a method and appaLatus for controlling a glass fiber forming process. More particularly, the present invention i~ directed to a method and apparatus for controlling the thermal envi~onment in a forming process by utiliza~ion of fin coolers having heat transfer liquid flow channe~s therein. Still more particularly, the present invention is dlrected to a method and apparatus for cooling glass fiber~ utilizing a heat exchange flu~d which ls passed in a closed loop system through heat transfer fins and heat exchange equipment.
In the preferred embodiment of the invention, the heat transfer fluid employed i9 one that has a boiling point above that of water A~ though water can be employed if its operating temperatures are controlled within certain limits. The preferred heat transfer fluid is also one having a speci~lc heat of at least 0.5 calories per degree Centigrade per g~ (cal/C/gm) and a vapor pressure below 1 atmosphere at temperatures of 400F and below. Each heat transfer fin has an elonga~ed flow pas~age formed withln it so that the hea~ exchange fluid can flow through the full length of each fin in the fin cooler assemhly. When high fin temperatures are es~ablished and maintained in accordance with ~3~227~
the metllods and apparatus of the present invention, i.e., temperatures above 150F, fin cooler life ls prolonged and heat transfer fin fouling from corrosion products is substantially reduced. Uniform and controlled fin temperatures at and above 150F which are obtained in accordance with ~he method and apparatus of the present invention further resu]t in improved product uniformity. i.e., consistent fiber diameters, improved running efiiciency, improved yardage uniformity and higher productivity.
_ scri~tion of the Prior Art Glass flbers sre typically formed by 1Owing molten glass through a large number of closely spaced orifices located in a container which holds the molten glass. Such containers or bushings often have 2000, 4000, or even up to 6000 of such glass fiber forming tips or orifices. The molten glass which flowa out through these arràys of bushing tips must be cooled in a controlled manner so that the glass fibers or filaments which are formed from the molten glass will be substantlally uniform in diameter.
A plurality oL generally planar, solid, elongated cooling fins are placed beneath the bushing tip plate and extend generally perpendicularly to the elongated rectangular bushing with the glass fibers or filaments passing between adjacent cooling fins and giving up heat to the fins. This heat transferred to the usually solid ~lat metal cooling fins is then transferred along the fins by conduction to a header block in whieh one end of the fin is embedded and whlch header block typically is provided with flow passages through whlch a relatively colcl cooling fluid such as the plant cooling water passes. Heat is removed from the header blocks by the transfer of heat to the cooling water ~3~227~ -passing through them and the cooling flns are then kept at a relatively low temperaturc at their junction with the header. The free ends of the Eins on the other hand are substantially ~armer than the ends in the header block thereby giving rise to large temperature variations across the fin surfaces.
With the advent of longer and wider bushing assemblies having 4000 to as many as 6000 glass forming orifices, heat removal has become more difficult necessitating the use of cooling fins that have been made longer 80 that they eY~tend across the width of the bushing assembly.
This increased cooling fin length has given rise to even higher free end fin temperatures in presently used commercial solid fins. These high free end fin temperatures that are caused by inadequate heat transfer rates from ~he free end of the fin to ~he fin cooler header block have caused excessive free fin end oxidation and distortion that leads to a short fin cooler life. The cooler portion of the fin surfaces also accumulate solids which corrode surfaces and require cleaning. Frequent fin cooler cleaning or replacement is expensive and disruptive of bushing operation with its concomitant 106s of productivity.
In addition, textile fiber glass strand products typically require higher levels of product uniformity than strand products used to provide rovings for resin reinforcement, Eor example. Textile glass fiber strands are used to manufacture cloth used for reinforcing high pressure laminates typically employed in circuit boards or for manufacturing decorative fabrics. These glass Piber strands have to be produced at a high level of product uniformity, consistent yardage per pound oL glass fiber being one criteria. Consistent yardage i5 one indicator of uniform fiber diameters in a given strand. The use of the ,1~2~P~
current commercia] solid cooling fins has not provided the deslred properties to textile fibers in many instances on a reproducible basis.
Further, slnce the cooling capabilities of the current solid fins are son~ewhat limitedl forming tensions for textile fibers tend to be high and the glass throughput from the bushings making these fibers is low.
Attempts have been made to provide fin cooler assemblies in which the lndividual fins are hollow so that plant cooling water can be pas~e~l throu~h the fins. Exemplary of prior art patents which disclose s~h cooled fln coolers are U.S. patents 3,251,665; 3~695,85O; and 3,746,525. Past attempts at operating cooled fin coolers have me~ with only marginal success and these fin coolers have not been wldely used by the glass fiber forming industry. Several general problems appear to be typical of prior art water cooled fin coolers. The flow of pla~t p~ocess or cooling water through the fins has produced fin temperatures which are una~ceptably low, i.e~. temperatures in the range of 70F to 100F on portions of the fins. These low temperatures on fin surfaces cause glass volatiles to condense out on the surfaces of the cooling fins causing unaccep~ably hlgh corrosJon rates and short fin life. Contamlnant build Up Otl the surfaces of the cooling fins also alters their heat transfer characteristics and creates noDuniformity in the glass fibers produced since the glass cooling is not uniform or consistent. The low temperature of the cooling fins caused by flow of coolant water through passages in the fins also allows the glass volatiles to mix with water in the environment nor~2ally present around a bushing to form corrosive acids that shorten fin llfe.
Further, ordinary plant (~ooling water may not be completely free of entrained solid particles and contaminants. As this water flows 2 ~ ~
through the relatively small paBSageS in the fins of the prlor art water cooled fin coolers, t~le flow passages may also become plugged or occluded. Such passage plugging in a ~in renders the cooling fin inoperative and causes rapid failure of such a fin. In a large bushing assembly havlng a correspondingly large number of water cooled fins, the inoperativeness of random cooling fins caused by coollng water flow passage fouling will cause the heat transfer rates to vary from cooling fin to cooling fin. Strand slzes wlll thus vary, the product formed will have non-uniform filament diameters as a consequence and will therefore be unacceptable. Water coolant flow passage clogging ln indivldual cooling fins is difficult to correct and requires the entire fin cooler be removed from the bushing assembly and repaired. These shutdowns are, of course, disruptive of production schedules and interfere with plant productivity.
As can thus be appreciated, there is a need in the glass fiber forming industry for a fin cooler which will be operable in a controlled.
dependable manner so that fin surface temperature can be maintained high enough to reduce corrosion effects to acceptable levels and insure that temperatures be more uniform across the entire surface of the fln.
Further, the cooled fin cooler must be able to operate free from distortions caused by inadequate cooling and must not be susceptible to failure due to Elow passage clogging.
It is an ob~ect of the pre9ent disclosure to provide a method and apparatus for controlling a glass flber forming process.
1 3 ~
Another object i~ to provlde a method of controlling glass fiber forming environment using a fin cooler with substantially unlform temp~ture fins.
A further object is to provide a fin cooler having heat transfer liquid flow passages therein and a heat transfer fluid system connected thereto and flowing through tbe passages to thereby maintain fln temperatures sufficiently high to minimi~e fin corrosion due to the condensation of volatiles ad~acent to the fins.
Still another ob;ect i~ to provide a method of controlling glass fiber forming utilizing a high specific heat fluid at controlled temperatures and rates of flow to provide a uniform environment around the fiber glass forming orifices or tips and uniform fin temperatures in the fin coolers used therein.
Yet a further ob;ect is to provide a method and apparatus for controlling a glass fiber forming environment utilizing a closed loop heat exchange fluid flow path at preselected operating temperatures, flow rates and heat removal rates.
Still yet another object is to provide a method of control~ing a glass fi~er forming process using a heat transfer fluid having a higher boiling point than water and a heat ex hanger to remove heat from the system.
As will be presented in greater detail in the description of the preferred embodiment which is set forth subsequently, the present disclosure is directed to a method and apparatus fo~1- rontrolling glass fiber forming by attenuating molten glass fibers formed by a multiple orifice bushing assembly, A plurality of generally flat cooling fins, which are attached at first ends to header blocks to form fin coolers, ~
.
22~
are placed benctlth the bushing tip plate. As the glass fibers pass between the spaced fins, the thermal environment area around the fins is controlled by transferring heat from the glass to the cooling fins while stabilizlng the surface temperature of the fins. Each of these fins includes an interior, generally elongated U-shaped flow passage with an inlet port of this fin flow passage being in communicatlon with a heat transfer fluid inflow channel in the fin cooler header block and with an out]et port from each fin heat transfer fluid flow passage being in communication with a separate outflow channel in the header block.
A heat transfer fluid having a hlgh specific heat and which has a boiling point substantially higher than that of water and a vapor pressure at its operatlng temperature of less than 1 atmosphere is prefer~bly used and is caused to flow in a closed loop through the fins and out. The outgoing fluid is then passed through a heat exchanger.
Thus, heat i5 extractPd from the glass fiber filaments by the flns adJacent thereto, transferred from the fin surface to a heat transfer fluid and the heat is then transferred to a secondary heat exchange fluid such as plant process water in a separate heat exchanger connected to the fln cooler.
"High specific heat" as used herein means a specific heat of at least .5 cal/C/gm, preferably in the range of .6 cal/C/gm to .7 cal/C/gm. "Low vapor pressure" as used herein, means a vapor pressure at operating temperatures of less than 1 atmosphere.
Selection of the heat exchange fluid and lts rate of circulation through the cooling fins and the rate at which heat is removed from it in the heat exchanger are parameters that are adjusted to insure that the surface portions of the cooling fins are maintained at a ~322~7~
temperature oE 150 to 400F, preferably in the range of 150 to ~00F.
Surface temperatures in the pre~erred range are high enough to prevent Lhe formation of glass volatile contaminants on the surfac~ of the cool.ing fIns by condensation from the adJacent environment. In contrast to prior water ~ooled fins, the use of heat transfer fluid in a c].ose~l loop F.ystem here descrlbed will maintain the fin surfaces at a temperature higher than pnssible with water passing in the pr~or art non-cl.osed loop s~stem because of the abili~y to precise].Y
control the temperature of the heat transfer fl~id ln the fins. Aeid formation due to the mixing of glass vo~atile components with water condensate on the fin surfaces should thereby be minimlzed due to the elevated fin surface operating temperatures that are provided hv the ose of a high specific heat, high boiling temperatllre heat exchange fluid and the closed loop system while adequate heat removal from the glass filaments ad~jacent the fins is still accomplished.
The heat exchange fluid flows in a closed loop This flow path is continuous and extends between the flow path in the individual coollng flns, through the header block, to a heat exchanger unit that removes the heat from the heat transfer fluid through a filter and back through the cooling fins for further thermal treatment. This closed flow path prevents the clogging or plugging of flow passages in the cooling fins as was apt to be the situation with prior art open loop water cooled fins that generally u~ilized plant process water for cooling. Since the individual coolant flow paths in the various coollng fins are no longer apt to become plugged by inorganic o~ide deposits, the frequency of in cooler failure and failure related production interruptions are .~ - 8 -~3~2~
substantially reduced. When water is employed as the cooling fluid, utillzation of distilled water is preferred, The fin cooler here described in a preferred embodiment of the present invention and :Lts method of usage with a high speciflc heat, high boiling temperature heat transfer f].uid f].owing in a cl.osed loop provldes a fin cooler which has a reduced tendency to accumulate glass vo].ati].e contaminants thereon or to be subjected to attack by corrosive ncids l~ecause of its ahility to m~i.nta~ll elevated surface temperatures, while still acting as a cooling surface for the glass fibers. SimlJ.ar].y, where water is employed, the same benefits accrue so long as temperatures of the circu]ating water are ma-lntained above 150F. lJniform fin temperature Is provided by clrculat-Lon of the heat transfer fluid throllgh the fin so that fin distortion and oxidation is not a concern. The closed loop fluid circulatlon system allows the heat transfer fluid to remain clean and provides a means for controlling fin surface temperatures bv contro].].ing the heat transfer fluid temperature through contro~led heat removal at the heat exchanger to provide a given fin surface temperature. A controlled fin temperature is achieved by accurately controlling the secondary or plant water coolant flow throu~h the hea~ exchanger. Thus the new method and apparatus of glass fiber cooling overcomes the disadvantages of the prior art while providing a system that is effective yet remains uncomplicated and reliable.
_ g_ ~ 3~2~
Brlef Description of the Drawin~
While the novel features of the method and apparatus of cooling glass fibers in accordance with the present invention are set forth with partLcularity in the appended clalms, a full and complete understanding of the invention may be had with reference to the detailed description of the preferred embodiments as set forth hereinafter and as ~ay be seen in the accompan~ving drawings in which:
Fig. 1 is a pers~ective view of one embodiment of a fin cooler constr~lcted generally embodying the present invention;
Fi~. 2 is a cross-sectional view of the header block of the fin coo~er of Fig. 1 taken along line II-II thereof;
Fig. 3 is a side elevation view of the fin coo]er of Fig. ]y partly in section and taken along line JII-III thereof;
Fig, 4 is a cross-sectional view of one cooling fin taken along l.ine IV-IV of Fig. 3; and Fig. 5 is a schematic side elevation view of a fin cooler embodying the present invention showing the closed loop circulation path of the heat transfer fluid through the fin cooler and a heat exchanger.
Flg. 6 Ls a front elevation of a preferred embodiment of the instant invention showing the cooling fins, the header and their re]ationship to the bushing tips.
Fig. 7 is a plan view of two fin coolers of the preferred embodiment showing their positioning in the headers.
Fig. 8 is a slde elevation in cross-section of header, fin and header fluid inlet and out]et.
] I) _ .
:~22~
DescriDtion of the Preferred_Embodiments Referring initally to Fig. 1, there may be seen generally at 10 a cooled fin cooler. Cooled fin cooler 10 includes a header block generally at 12 to which are attached a plurality of outwardly extending cooling flns 14. As is known generally in the art, fin coolers of this general type are typically placed beneath the tip pl te of a glas~ fiber fllament forming bushing assembly (not shown). I~divldual glass ~ibers, which are pulled from molten glass cones formed at the bushing tip plate, are attenuated by a suitable winder or the like. Groups of these lndividual fibers pass generally downwardly between the spacsd cooling fins 14 which ~ake heat away from the glass so that the glass will be properly cooled.
In the cooled fin cooler the header block 12 is generally in the shape of an elongated rectangular bar having a top surface 16? an opposed bottom surface 18, a front face 20 and an opposed rear face 22. Each of the plurality of cooling fins 14 is attached at a first end 24 to front face 20 of header block 12 in any generally conventional manner, such as by welding or brazing, and extends outwardly therefrom in a can~ilever fashion to a second, free end 26.
As may be seen in Figs. 2 and 3, header block 12 includes a pair of spaced, separate, Plongated coolant flow channels. A coolant liquid inflow channel 28 i9 formed in the interior of header block 12 generally closer to bottom surface 18 and e~tends the length of header block 12. A
coolant liquid inflow line 30 is secured to header block 12 and supplies coolant liquid to inflow channel 28. A separate coolant liquid outflow channel 32 is formed ln header block 12 and extends the length of header block 12 ad~acent the top surface 16 thereof. Inflov ` 132227~
channel 28 and outflow channel 32 are generally parallel to each other but are completely separate from each other. A coolant liquld outlet line 34 is ln fluid communication with outflow channel 32 and provides a means for coolant liquid egress from header block 12.
Referring again to Fi.g. 3, and as may al50 bP SeeD in F~g. 4, each cooling fin 14 is provided with a generally elongated ~-shaped coolant liquid flow passage 36. Flow passage 36 in each cooling fin 14 I-as an inlet port 38 which is placed in coolant liquid inflow chamlel 28 ln header block 12. An outlet port 40 of each coolant liquid flow passage 3~ is disposed in coolant liquid outflow channel 32 of header block 12. Each coolant liquid flow passage 36 in each cooling fin 14 extends from the first end 24 of fin 14 along a lower leg portion 42 adjacent bottom portion 44 of fin 14, to ~he free end 26 of fin 14 and then back through a top leg portion 46 of fin 14, ad~acent upper edge 48 of fin 14 and back to the first end 24 of the fin 14. Coolant liquid flows into header block coolant liquid inflow channel 28 and into the lower leg 42 of coolant liquid flow passage 36 through inlet port 38.
The coolant liquid flows out to the free end 26 of fin 14 and then back through top leg 48 of flow passage 36. back through outlet port 40 and into coolant liquid outflow channel 32 in header block 12. While coolant liquid inflow channel 28 and coolant liquid outflow channel 32 in header block 12 are not in direct fluid co~munication, they are in fact in contact with each other through the plurality of coolant liquid flow passages 36 in cooli.ng fins 14.
A preferred structure of a cooling fin 14 is shown in Fig. 4 as being comprised of two similar, but opposed stamped metal panels SO and 52, each of which is formed as one side of the cooling fin 14. Each ~3222~
stamped panel 50 and 52 includes a generally elongated U-shaped recess.
When the two panels 50 and 52 are placed together and joined to each other by securement of peripheral and intermediate flange sections 54 and 56. re6pectively, by welding or the like there is formed cooling fin 14 having cooling liquid flow passage 36 therewithin. Each cooling fin 14 could be formed in one of several alternative ways to provide a generally rectangular hollow fin having a coolant liquid flow passage 36. For example, two planar metal panels could be secured together with peripheral and intermediate spacers to again define a generally U-shaped flow passage 36 in each cooling fin 14.
Turning now to Fig. 5 there may be seen a schematic re~resentation of a fin cooler and heat exchanger closed circuit for a cooled fin cooler embodyi~g the present invention. A coolant liquid, which flows through flow passage 36 in coollng fin 14, enters header block 1~ through coolant liquid inflow llne 30 and exits through coolant liquid outflow line 34 as has previously been dlscussed. During its passage through cooling fin 14, the coolant liquld takes on heat through indirect heat transfer from the glass fiber filaments which pass between the cooling fins 14. This heat must be removed from the coolant liquid and this is accomplished by passing the hot liquid through a lleat exchanger generally at 60. The hot llquid from the fin cooler lO flows through a heat excllange core 62 around which continually circulates a seccndary heat exchange fluid such as plant process water by means of a water inlet 66 and a water outlet 68 or by forced air cooling. The hot coolant liquid is cooled, and upon exiting from heat exchanger 60, is reused. The coolant liquid can thus be seen to be flowing in a closed loop in which it takes on heat in the cooling fins and gives off heat in the exchanger.
~32~
Turning to Figs. 6, 7 and 8, there is shown the preferred embodiment of the fin cooler system. In fig. 6, a fin cooler header 71 and 72 are shown po~itioned behind and below a bufihing, 80 which has a multiplicity of Liber forming tips 81 on the bottom thereof. The tips 81 are arranged in rows and as shown, two rows of tips, 81 are positioned between the fins 74 of header 71 and fins 75 of header 72. Eluid is introduced lnto headers 71 and 72 tl)rough inlets 82 and 83 respectively. Fluid exits the header 71 and 72 through outlets 84 and 85 respectively. Flns 74 and 75 are formed of two sheets of metal which are plnched toward each other along their center line and welded together to form the U-shaped channel 86 shown in Fig. 8. The solid metal center 87 divides the fin to provide that channel 86. In the header 71 shown in Fi~. 8, a rectangular configuration is provided with a dividlng wall 88 therein to prov:lde an upper chamber 89 and a lower chamber 90. As will be readily understood, the inlets 82 and 83 and outlets 84 and 85 are connected to a heat exchanger 60 such as shown in Flg. S so that fluid circulating in the fins 74 and 75 can be treated to extract heat and supply cooled ~luid during operation.
As has been alluded to previous1y, in the preferred embodiment, the heat exchange liquid or coolant liquid which flows in the closed loop and wh~ch thus passes through tlle cooling fins 14 i9 selected from one of a number of heat exchange fluids that have a boiling point higher than water> a vapor pressure of below 1 atmosphere and a high specific heat value at operating temperature, i.e., at least 0.5/C/gm. Exemplary of heat exchange fluids which would be sui~able for such use are Hydrotherm 700-160 and Hydrotherm 750-200, manufactured by ~nerican Hydrotherm Corporation, or Dowtherm A or Dowtherm E which are made by Dow Chemical * Trademark ~322~
Company. ~lCernatively, various mineral oils or other heat exchange fluids may be used in the closed loop~ cooled fin cooler in accordance with the present invention so long as they conform to the specific heat and vapor pressure requirements. Thus, hlgh boiling alcohols such as glycerol, ethylene glycol, propylene glycol, 1,3-propanol may be used alone or diluted slightly with water, i.e.~ up to 15 to 20 percent so long as the boiling point of any such diluted alcohol is higher than water and the specific heat remains at a value of at least 0.5 cal/C/gm with a vapor pressure below 1 atmosphere at an operating fin temperature of 150F or above, preferably 150F to 200~F. These heat exchange flulds have bolling points substantially higher than water and allow the cooling fins to operate at a temperature of 150-400~ or higher, preferably 150F
to 200F.
In lnstances where water alone is employed, it should be free of contaminants, maintained at or above 150F and below its boiling point as it circulates through the fins. This temperature is controlled by the heat removal in the heat exchanger and the rate of flow of water through the closed loop in which the water flows.
The upper limit of temperatures used with material liquids other than water alone is determined by the failure polnt of the materials used in the fin and the boiling point of that liquid.
Operation in temperature ranges of this magnitude reduces the deposition amounts of glass volatiles on the fin surfaces and also reduces the tendency to form corrosive acids on the cooling fin surfaces. Although the fins operate at a higher temperature than would be the case if they were operating in accordance with the teachings of the prior art with water used in an open system as a heat transfer fluid, the difference 3. 3 2 2 2 r7 ~j between the fin temperature of 150-400F and the typical 2200~F bushing tip exit temperature o~ the glass affords good heat ~ran~fer to the fins. It has been found furtl1er that by maintainirlg a margin of generally 25 to 1~0F, preferably 50 to 100F or more between the operating temperature of the system in the fins and the boiling point of the heat transfer fluid used therèin insures th~t the fluids employed will remain in liquid form at all times in all parts of the closed system. The specific operating temperature of -he fin cooler can be controlled by proper selection of the desired heat transfer fluid and by control of the flow rate of the heat transfer fluid through the heat exchanger.
The method and apparatus for glass fiber cooling in the preferred embodiment of the present invention makes use of a heat transfer liquid having a boiling point higher than water and a high specific heat to allow the cooling fins to operate at a temperature of generally about 150 to 400F, preferably 150 to 200F. Operating in this temperature range helps prevent glass contaminant deposition on the cooling fins, provides even fin temperature distribution, and prolongs fin llfe by impeding the formation of fin corroding acids. The closed loop path of the heat ~ransfer flui~ through the cooling fins and the heat exchanger allows the use of a contaminant free heat transfer medium which will remain contaminant free during use and will not occlude or plug the coolant liquid flow passages in the cooling fins. Thus the method and apparatus for cooling glass fibers provides a substantial advance in the art. Further, benefits are provided in that, by adjustment of the fluid employed and the circulation rates through the fins and its conseguen~
effect on fin :.
11 ~22~7~
temperature, the for~ning process itself can be adjusted to alter ~la~s viscosities in the area of glass formlng cones to ad~t fiber diameters.
In a preferrecl mode operation a fin cooler was used on an 800 tip fiber glass forming bushing in a laboratory ~urnace forehearth with a 90 percent ethylene glycol - ]O
percent water mixture used as the heat tran~fer media. The media was p~mped through the fins of the fin cooler at a rate of about 500 milli]Jters per minute per fln. The fin surface temper~tures were maintained at IhOF by re~oving heat fr~m the heat transfer fluid in the fluid heat exchanger which was operated with water as the heat exchange fluid at inlet temperatures of 80F and outlet temperatures of about 15~F.
In another preferred mode of operating ten 800-tip fiber glass forming bushings were operated off a fiber glass furnace forehearth in a manufacturing plant utilizing the fin cooler system, each fin cooler having 38 fins per position. The ethylene glycol, the primary heat transfer media, circulating through the fins was a 70 percent ethylene glycol - 30 percent water mixture. This ethylene glycol-water mixture was pumped through the fins of the fin coolers on all bushings at a rate of between O.l and 0.15 gallons per minute per lndividual fin. The fin surface temperature of the fins on th~ lO bushing positionq was maintained at 160F by removing heat from the primary heat transfer media, i.e., the 70/30 ethylene glycol water mixture in a heat exchange fluid in the heat exchanger. Plant process water at approximately 80F waq fed to the heat exchanger, and the outlet temperature of the water from the heat ~3~22~
exchanger un~t was about 150F. Operating in this manner the ~ins were maintalned at the approximate 160F surface temperature during the operatlon. The fins~ except for a minor leak problem on three fins associated with the fln coolers, which were leaks at ~h~ braizing ~ointure of the fin with the fln cooler header, the operation o~ the fin system has been satisfactory and no system failures have occurred.
During the course of this run which was conducte~ on a produc~ion furnace, two bushings and associated fins were utlll~ed at the be~innin~, and as the trlal progressed, fl1rther bushings and flns were adde~ until the total number of 10 bushlngs and associated fins was achieved. One of the fin cooler posltions employed durlng the course of the ~rlal ha~
ach1eved a servlce o~ 34 week~ wltl~out any failure. It has also been obaerved when the system was utllized on these positions that a lower broken filament levels were experie~ced during the operation of the bushings than was experienced with the normal solid fins previously employed for production from bushings of this design.
While preferred embodiment~ of the present invention have been set forth fully and completely hereinabove, it will be ob~ious to one of skill in the art that a number of changes in, for example, the shape of the header block, the various fittings and connections, the structure of the heat exchanger and the like could be made without departing from the true spirit and scope of the sub~ect inventlon which is accordlngly to be limited only by the following claims. Similarly, in lieu of the preferred glycol-water used in the preferred mole various olls such as were described above can also be used. Thusl the invention is not to be limited except insofar as appears in the accompanying claims.
Claims (32)
1, In a method of cooling glass fibers formed from molten glass, wherein heat is extracted from the glass fibers as they are formed through a fin cooler assembly by indirect heat. exchange through the fin surfaces, the improvement comprising: circulating in a closed loop, through each fin, a heat transfer fluid having a specific heat of at least 0.5 cal/°C/gm and a vapor pressure not over l atmosphere at operating temperature, at a rate sufficient to maintain the fin surfaces above about 150°F and not above about 400°F which extracts heat from the filament forming environment into said heat transfer fluid.
2. The method of claim 1, wherein the extracted heat in said heat transfer fluid is removed at a location remote from said fin cooler.
3. The method of claim 1, wherein the fin surfaces are maintained at temperatures between 150°F and 200°F.
4. The method of claim 1, wherein the fin surfaces are maintained at temperatures above 200°F.
5. A method of cooling glass fibers formed from molten glass in a glass forming bushing having a plurality of glass forming tips comprising the steps of:
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing a heat transfer fluid having a boiling point higher than water and a high specific heat and low vapor pressure through flow passages in said spaced cooling fins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said heat transfer fluid;
cooling said heat transfer fluid in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled heat exchange fluid is flowed at a temperature of between 150-400°F; and circulating said heat transfer fluid in a closed loop continuously between said fin cooler and said heat exchanger.
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing a heat transfer fluid having a boiling point higher than water and a high specific heat and low vapor pressure through flow passages in said spaced cooling fins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said heat transfer fluid;
cooling said heat transfer fluid in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled heat exchange fluid is flowed at a temperature of between 150-400°F; and circulating said heat transfer fluid in a closed loop continuously between said fin cooler and said heat exchanger.
6. The method of claim 5, wherein the temperature of the cooling fins is above about 200°F.
7. The method of claim 5, wherein the temperature of the cooling fins is between 150°F and 200°F.
8. The method of claim 5 further including providing separate coolant liquid inflow and outflow channels in a header block of said fin cooler, and flowing said heat transfer fluid from said heat exchanger to said coolant liquid inflow channel and flowing said heat transfer fluid from said coolant liquid outflow channel to said heat exchanger.
9. The method of claim 8 further including providing a generally elongated U-shaped fluid flow path as said flow passage of each of said cooling fins. connecting an inlet port of said flow passage to said coolant liquid inflow channel and connecting an outlet port of said flow passage to said coolant liquid outflow channel.
10. A cooled fin assembly suitable for use in cooling glass fibers formed from molten glass in a glass fiber forming bushing having a plurality of glass forming tips, said cooled fin cooler assembly comprising:
a fin cooler header positionable generally beneath said glass forming bushing, said header including separate spaced coolant liquid inflow and coolant liquid outflow channels a plurality of spaced cooling fins secured at first ends to said header block and extending outwardly therefrom beneath the plurality of glass forming tips to remove heat from glass fiber filaments which pass between said space cooling fins;
a coolant liquid flow passage in each of said cooling fins, each of said flow passages including an inlet port in fluid communication with said coolant liquid inflow channel and an outlet port in fluid communication with said coolant liquid outflow channel;
a heat exchanger remote from said fin cooler header block and in fluid communication therewith to form a closed loop fluid flow path; and a heat transfer fluid circulatable in said closed loop fluid flow path between said heat exchanger and said header block and through said coolant liquid flow passages in said cooling fins to remove heat from said cooling fins and give up heat to said heat exchanger, said heat transfer fluid having a boiling point higher than water and having a specific heat of at least 0.5 cal/°C/gm and vapor pressure of below 1 atmosphere when the heat transfer fluid is at a temperature of 150°F and above.
a fin cooler header positionable generally beneath said glass forming bushing, said header including separate spaced coolant liquid inflow and coolant liquid outflow channels a plurality of spaced cooling fins secured at first ends to said header block and extending outwardly therefrom beneath the plurality of glass forming tips to remove heat from glass fiber filaments which pass between said space cooling fins;
a coolant liquid flow passage in each of said cooling fins, each of said flow passages including an inlet port in fluid communication with said coolant liquid inflow channel and an outlet port in fluid communication with said coolant liquid outflow channel;
a heat exchanger remote from said fin cooler header block and in fluid communication therewith to form a closed loop fluid flow path; and a heat transfer fluid circulatable in said closed loop fluid flow path between said heat exchanger and said header block and through said coolant liquid flow passages in said cooling fins to remove heat from said cooling fins and give up heat to said heat exchanger, said heat transfer fluid having a boiling point higher than water and having a specific heat of at least 0.5 cal/°C/gm and vapor pressure of below 1 atmosphere when the heat transfer fluid is at a temperature of 150°F and above.
11. The cooled fin assembly of claim 10, wherein the heat transfer fluid has a boiling point higher than water and a specific heat of at least 0.5 cal/°C/gm and a vapor pressure below 1 atmosphere when the heat transfer fluid is at a temperature of between 150°F and 200°F.
12. The cooled fin assembly of claim 10, wherein the heat transfer fluid has a boiling point higher than water and a specific heat of at least 0.5 cal/°C/gm and a vapor pressure below 1 atmosphere when the heat transfer fluid is at a temperature of between 150°F and 400°F.
13. The cooled fin cooler assembly of claim 10, wherein said coolant liquid flow passage in each of said cooling fins is generally an elongated V-shaped passage.
14. The cooled fin cooler assembly of claim 10, wherein said heat exchanger utilizes plant process water as a secondary heat transfer fluid.
15. The method of claim 1, wherein there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
16. The method of claim 2, wherein, there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
17. The method of claim 3, wherein there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
18. The method of claim 5, wherein there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
19. The method of claim 6, wherein there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
20. The method of claim 7, wherein there is a temperature differential of 50 to 100°F between the fin surfaces and the boiling point of the heat transfer fluid.
21. In a method of cooling glass fibers formed from molten glass, wherein heat is extracted from the glass fibers as they are formed through a fin cooler assembly by indirect heat exchange through the fin surfaces, the improvement comprising: circulating in a closed loop, through each fin, a heat transfer fluid at a temperature of at least 150°F and below its boiling point, extracting heat from the environment and transferring it to the heat transfer fluid, passing the heat transfer fluid to a heat exchanger remote from the fins, extracting heat from the heat transfer fluid in the heat exchanger and balancing the heat removal in the heat exchanger and the flow rate of the heat transfer fluid to maintain the temperature of the heat transfer fluid in the fins at 150°F
or greater but below the boiling point of the heat transfer fluid.
or greater but below the boiling point of the heat transfer fluid.
22. In a method of cooling glass fibers formed from molten glass wherein that is extracted from the glass fibers as they are formed through a fin cooler assembly by indirect heat exchange through fin surface, the improvement comprising: circulating in a closed loop system water through each fin at a temperature of at least 150°F and below its boiling point, extracting heat from the environment adjacent the fins and transferring it to the water in the fins, passing the water from the fins to a heat exchanger connected to the closed loop and remote from the fins, extracting heat from the water in the heat exchanger and balancing the rate of heat removal from the water in the heat exchanger and the rate of flow of water through the fins to maintain the water in the fins at 150°F or more but below its boiling point.
23. The method of claim 21, wherein the fin surfaces are maintained at temperatures between 150°F and 200°F.
24. The method of claim 22, wherein the fin surfaces are maintained at temperatures between 150°F and 200°F.
25. A method of cooling glass fibers formed from molten glass in a glass forming bushing having a plurality of glass forming tips comprising the steps of:
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing heat transfer fluid through flow passages in said spaced cooling f ins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said heat transfer fluid;
cooling said heat transfer fluid in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled heat exchange fluid is flowed at a temperature of between 150-400°F; and circulating said heat transfer fluid in a closed loop continuously between said fin cooler and said heat exchanger.
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing heat transfer fluid through flow passages in said spaced cooling f ins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said heat transfer fluid;
cooling said heat transfer fluid in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled heat exchange fluid is flowed at a temperature of between 150-400°F; and circulating said heat transfer fluid in a closed loop continuously between said fin cooler and said heat exchanger.
26. The method of claim 25, wherein the temperature of the cooling fins is between 150°F and 200°F.
27. The method of claim 25 further including providing separate coolant liquid inflow and outflow channels in a header block of said fin cooler, and flowing said heat transfer fluid from said heat exchanger to said coolant liquid inflow channel and flowing said heat transfer fluid from said coolant liquid outflow channel to said heat exchanger.
28. The method of claim 27 further including providing a generally elongated U-shaped fluid flow path as said flow passage of each of said cooling fins. connecting an inlet port of said flow passage to said coolant liquid inflow channel and connecting an outlet port of said flow passage to said coolant liquid outflow channel.
29. A method of cooling glass fibers formed from molten glass in a glass forming bushing having a plurality of glass forming tips comprising the steps of:
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing water through flow passages in said spaced cooling fins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said water;
cooling said water in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled water is flowing at a temperature of at least 150°F and below its boiling point; and circulating said water in a closed loop continuously between said fin cooler and said heat exchanger.
positioning a fin cooler having a plurality of spaced cooling fins adjacent the glass forming tips and passing the formed glass fibers between the spaced cooling fins;
flowing water through flow passages in said spaced cooling fins;
removing heat from said glass fibers as said fibers pass between said cooling fins and transferring the removed heat to said water;
cooling said water in a heat exchanger to an extent sufficient to maintain the temperature of the cooling fins through which the cooled water is flowing at a temperature of at least 150°F and below its boiling point; and circulating said water in a closed loop continuously between said fin cooler and said heat exchanger.
30. The method of claim 29, wherein the temperature of the cooling fins is maintained between 150°F and 200°F.
31. The method of claim 29 further including providing separate coolant water inflow and outflow channels in a header block of said fin cooler. and flowing said water from said heat exchanger to said coolant water inflow channel and flowing said water from said coolant liquid outflow channel to said heat exchanger.
32. The method of claim 31 further including providing a generally elongated U-shaped fluid flow path as said flow passage of each of said cooling fins, connecting an inlet port of said flow passage to said coolant water inflow channel and connecting an outlet port of said flow passage to said coolant water outflow channel.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US170,203 | 1988-03-18 | ||
| US07/170,203 US4824457A (en) | 1987-06-05 | 1988-03-18 | Method and apparatus for controlling thermal environment in a glass fiber forming process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1322275C true CA1322275C (en) | 1993-09-21 |
Family
ID=22618978
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000586221A Expired - Fee Related CA1322275C (en) | 1988-03-18 | 1988-12-16 | Method and apparatus for controlling thermal environment in a glass fiber forming process |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4824457A (en) |
| EP (1) | EP0333180B1 (en) |
| JP (1) | JPH0653591B2 (en) |
| CN (1) | CN1036550A (en) |
| CA (1) | CA1322275C (en) |
| DE (1) | DE68906438T2 (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4995892A (en) * | 1989-12-19 | 1991-02-26 | Ppg Industries, Inc. | Process and apparatus for controlling the thermal environment of glass fiber forming |
| US5979192A (en) * | 1998-06-23 | 1999-11-09 | Owens Corning Fiberglas Technology, Inc. | Fin blade assembly |
| US6408654B1 (en) | 1999-06-09 | 2002-06-25 | Owens Corning Fiberglas Technology, Inc. | Filament forming apparatus and a cooling apparatus for and method of inducing a uniform air flow between a filament forming area and the cooling apparatus |
| US6192714B1 (en) | 1999-08-31 | 2001-02-27 | Owens Corning Fiberglas Technology, Inc. | Filament forming apparatus and a cooling apparatus for and method of cooling a filament forming area |
| US6546758B1 (en) | 2000-08-16 | 2003-04-15 | Alcatel | Multi-chamber fiber cooling apparatus |
| JP4860053B2 (en) * | 2001-05-28 | 2012-01-25 | オーウェンスコーニング製造株式会社 | Continuous glass filament manufacturing equipment |
| US20030145631A1 (en) * | 2002-02-04 | 2003-08-07 | Sullivan Timothy A. | Support for fiber bushing and bushing with same |
| FR2849848B1 (en) * | 2003-01-15 | 2007-04-27 | Saint Gobain Vetrotex | THERMAL EXCHANGE DEVICE FOR FIBER CAB |
| US7293431B2 (en) * | 2003-04-30 | 2007-11-13 | Owens Corning Intellectual Capital, Llc | Apparatus for cooling a filament forming area of a filament forming apparatus |
| US20050092031A1 (en) * | 2003-11-05 | 2005-05-05 | Johnson Walter A. | Cooling members for fiberizing bushings and method |
| US7726155B2 (en) | 2006-07-07 | 2010-06-01 | Johns Manville | Cooling apparatus for fiberizing bushings |
| US8820123B2 (en) | 2006-10-12 | 2014-09-02 | Johns Manville | Apparatus and method for cooling molten glass and fibers |
| US8091388B2 (en) * | 2006-12-28 | 2012-01-10 | Owens Corning Intellectual Capital, Llc | Cooling ring for use in manufacturing of fiberglass wool |
| US20090045714A1 (en) * | 2007-08-13 | 2009-02-19 | Claeys Michael L | Uv module shutter extrusion with internal cooling fins |
| KR102482437B1 (en) | 2015-02-04 | 2022-12-28 | 코닝 인코포레이티드 | Glassware Forming System |
| DE102021126318A1 (en) * | 2021-10-11 | 2023-04-13 | Valeo Klimasysteme Gmbh | Heat exchanger device for cooling battery cells in a vehicle |
Family Cites Families (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| USRE24060E (en) * | 1948-12-14 | 1955-09-06 | G russell | |
| US2947028A (en) * | 1954-11-19 | 1960-08-02 | Owens Corning Fiberglass Corp | Apparatus for manufacture of fibrous glass |
| US2908036A (en) * | 1954-11-22 | 1959-10-13 | Owens Corning Fiberglass Corp | Apparatus for production of glass fibers |
| US3251665A (en) * | 1963-05-31 | 1966-05-17 | Pittsburgh Plate Glass Co | Method for the production of glass fibers |
| NL130415C (en) * | 1965-06-01 | 1900-01-01 | ||
| FR1448153A (en) * | 1965-06-17 | 1966-01-28 | Verre Textile Soc Du | Further training in the sectors for the production of threads of thermoplastic materials, in particular glass |
| FR1521200A (en) * | 1966-05-02 | 1968-04-12 | Fibreglass Ltd | Improvements made to the cooling cores |
| US3647382A (en) * | 1970-06-15 | 1972-03-07 | Certain Teed Prod Corp | Glass fiber cooling means made of palladium |
| JPS4824412B1 (en) * | 1970-07-16 | 1973-07-20 | ||
| US3695858A (en) * | 1971-10-29 | 1972-10-03 | Owens Corning Fiberglass Corp | Method and apparatus for production of glass fibers |
| US3759681A (en) * | 1972-07-11 | 1973-09-18 | Ferro Corp | Cooling means for forming glass fibers |
| US3868494A (en) * | 1973-12-04 | 1975-02-25 | Armand Pepin | Electric space heating system |
| US4059145A (en) * | 1975-06-05 | 1977-11-22 | Sid Richardson Carbon & Gasoline Co. | Method and apparatus for controlling surface temperature |
| DE2839837A1 (en) * | 1978-09-13 | 1980-03-27 | Thermal Waerme Kaelte Klima | Vehicle engine heat exchanger - has row of liq. carrying tubes with max. internal dia. of 6.7 mm. |
-
1988
- 1988-03-18 US US07/170,203 patent/US4824457A/en not_active Expired - Lifetime
- 1988-12-16 CA CA000586221A patent/CA1322275C/en not_active Expired - Fee Related
-
1989
- 1989-02-06 JP JP1027320A patent/JPH0653591B2/en not_active Expired - Fee Related
- 1989-03-15 EP EP89104638A patent/EP0333180B1/en not_active Expired - Lifetime
- 1989-03-15 CN CN89101364A patent/CN1036550A/en active Pending
- 1989-03-15 DE DE89104638T patent/DE68906438T2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| US4824457A (en) | 1989-04-25 |
| JPH01242437A (en) | 1989-09-27 |
| DE68906438D1 (en) | 1993-06-17 |
| EP0333180B1 (en) | 1993-05-12 |
| CN1036550A (en) | 1989-10-25 |
| EP0333180A3 (en) | 1990-09-19 |
| DE68906438T2 (en) | 1993-11-25 |
| EP0333180A2 (en) | 1989-09-20 |
| JPH0653591B2 (en) | 1994-07-20 |
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