US2569824A - Heating device for molten materials - Google Patents

Description

Oct. 2, 1951 R. L. NALL 2,569,824

HEATING DEVICE FOR MOLTEN MATERIALS Filed Feb. 12, 1948 2 Sheets-Sheet 1 m T la 24 7 /90 INVENTOR 4 05527" I A1414 ATTORNEY Oct. 2, 1951 R. L. NALL 2,569,824

HEATING DEVICE FOR MOLTEN MATERIALS Filed Feb. 12, 1948 2 Sheets-Sheet 2 Tia a.

INVENTOR &es:? 4. A4444.

ATTORN EY Patented Oct. 2, 1951 UNITED STATES QFFICE 2,569,824 HEATING DEVICE FOR. MOLTEN MATERIALS Robert L. Nall, New Orleans, La.) assignor to The Patent and Licensin g Corporation, New York,

N. Y., a corporation of Massachusetts Application February 12, 1948, Serial No. 7,812

4 Claims. 1

This invention relates to a device for heating liquid materials. Although not confined thereto, the invention is particularly concerned with a device which is adapted for use as a superheater for heating liquefied bitumens, such as asphalt, to relatively high temperatures.

In the manufacture of asphalt-impregnated floor coverings and roofing materials such as roll roofing, shingles and the like, a continuous web or foundation sheet of fibrous felt is saturated by immersion in a bath of molten asphalt. When the impregnated web isto be used for the preparation of roof coverings, it is further processed to provide the web with a coating of relatively high melting point asphalt and a weather surface of mineral particles embedded in the coating. In thecourse of the saturation step the felt web is guided through a bath of molten saturant by passing the web over upper and lower sets of guide rolls, the lower set being submerged in. the saturant adjacent the bottom of the saturator tank. In order to obtain rapid and eiieictive saturation of the web, the asphalt saturant in the tank is maintained at a relatively high .temperature, i. e., 450 to 525 F. The felt web being continuously introduced into the hot molten asphalt, however, has a markedzcooling effect on the saturant and, of course, the continuous absorption of asphalt from the saturator bath by the web consistently depletes the supply of .saturant. It is accordingly necessary to provide heating means which will continuously .and rapidly reheat the cooled asphalt to the desired elevated temperature and which will also heat the make.- up asphalt added to the saturator system.

Heating units which are commonly used in roofing plants for maintaining the saturant at elevated temperatures are tube-type refractory heaters wherein the asphalt is pumped through a tube positioned in a heated chamber. Such heating units have the disadvantage of being comparatively large and requiring extensive floor areas to accommodate them. Further, the refractory brick work involved in the construction of such heaters places a heavy weight upon the foundation and cracking of the brick due to settling is frequently encountered.

It is an object of this invention to provide an improved heating device adapted to heat molten liquids continuously and efficiently to relatively high temperatures and which requires a minimum of floor space, is relatively light upon its foundation and is not susceptible to injury from normal settling. l

Itis a furtherobject of the invention to pro- (c1. nit-343.5)

2 vide a heating :device .ofvthe character indicated which. is adapted to bensed'in conjunction ,th the saturator unit of aroofin machine to main tain the saturant therein at a temperature of 450 to 525 F.

Other objects and advantages of the invention will be apparent .from' the'detailed description which is to follow and from therdrawings :in which,

Fig. 1 is a diagrammatic view ofa heater con,- structed according to the invention. showingthe manner in which it may be -,associate c l.with a i felt saturator. and witha makeeupasp halt supply; a

Fig. 2 is a view in elevation: of the heater with a portion thereof broken away to show the ar rangementiof the .flues;

Fig. 3 is a horizontalsection taken along the line 33 of Fig. 2;

Fig. 4 is a sectional view along theline ;44 of :Fig. 3 showing: the a rangement of names and Fig; 5 is a: sectional view ,showing the method .ofsecuring the fines tosthe supporting structures.

Referring to the drawings, the numeral Ii) designates generally atankwhich forms the body or casing of theiheater and-which comprises a mdricalwall l2. proyided with heads formed by hemispherical walls. and l Ssecured as by welding to :theupper and lower ends, respectively, of wall 12; A'supporting structure for the tank in is provided b e gird ll e ur -t t e ut sideof wall 12 and vertical columns 18 jointed to girder. Flanged inletnozzles 22 and {Bare providedin hemispherical wall 15 and cylindricalwall 12, respectively, and a flanged outlet nozzle 24 is provided in hemispherical iwalll 114. In order to; prevent surging of the liquid-being heated .asrit ,is pumped through the heater the tank It is providedw i bei g 5 and 'vbish extend w rdl adiac n l .22 ou l t 5 respectively, each hafiie being .formedby two .outwardly diverging perforated plate's'ianda' liorizontal perforated circul arflplate secured to the outerendsthereotflas shown in Fig. 2'. To permit access to. the inte jiq of tank H), cov red manholes 21 and 2,8 are termed in wall 14, and

covered manholes 129 and 30 areprovidedi'n wall I 2 and wall 15, respectively.

The liquid; gasphai p as itpasses upwardly through the tank l 0 is heated by direct contact with a series ofparallel, horizontally-disposed sinuous flues through which hot. .combustion gases are passed. Theseiflues inthe embodiment illustrated are .arrangedwin .three banks:;of= four fluesreach; the fines the .upper, intermediate and lower bankszbeing. de'signatedailil, 34 ands,

respectively. It is a feature of the invention that each flue has an independent source of heat and that each flue passes through the tank in the same plane and substantially in a plane parallel to the planes of the other flues. The ends of the flues 32 are provided with flanges 3'8 and 39, the flanges 38 being bolted to flanged ends 4| of flue outlets 42, which are secured asby welding in suitable'openings in wall 12, and flanges 39 being bolted to flanged ends 44 of flue inlets 45, also secured in openings in wall l2. Flues 34 and 36 are similarly attached to flue outlets 50 and 52, respectively, and flue inlets 54 and'56, respectively. Parallel angle irons 58 and 59 which extend across the interior of tank Ill-support the flues 32, 34 and 36 which are secured to the angle irons by U-bolts 60.

Hot combustion gases are received in the flues 32 from burners 62, an individual burner being positioned adjacent each flue inlet 45. Similarly, each of the flues 34 and 36 is heated by gases from burners 64 and 66, respectively, positioned adjacent each flue inlet 54 and 56, respectively. The burners 62, 64 and 66 are not per se a part of the invention and may be any suitable gas or oilflred burner or the like. The combustion gases as they are discharged from the flues enter stacks which vent the gases to the atmosphere, an independent stack being provided for each bank of flues. The gases leaving flues 32 pass through flue outlets 42 into a stack 16 and the gases in flues 34 and 36 are vented through stacks Ill and 12, respectively. Additional stacks may be provided, if desired, as for example, an individual stack for each flue. A forced draft is induced in the banks of flues by suitable blowers 16a, Ila and 12a positioned in stacks 10, H and I2, respectively.

It will be observed that each of the three banks of flues is slightly offset horizontally with respect to the other two banks. This arrangement of the flues insures more intimate contact of the liquid with the flues as it progresses upwardly through the'tank Iii. Exteriorly of tank 10, the banks of flue inlets and flue outlets are, of course, similarly offset with respect to one another.

Referring particularly to Figs. 3 and 4, it will be observed that two oblique bafiles areprovided to direct the liquid onto the flues in that-portion of the tank where the flues are furthest from the wall 12. A baffie 15, having a flange 16 which is bolted to the inner side of wall I I, is positioned just below the upper bank of flues 32 and a baflle I1 having a flange 18 is similarly placed 'just below flues 34. 7

Referring particularly to Fig. l, the numeral 80 designates a saturator unit in which is maintained a pool of liquid asphalt 82 through which a web 83 is guided in the usual manner by upper rollers 85 and lower rollers 86. The asphalt in the saturator 80 is returned to tank ID to be reheated'througha pipe 88 which extends from the lower part of the saturator 80 to inlet 23, the asphalt being pumped through the pipe by a positive pressure pump 89. A pipe'90 connected to outlet 24 conducts the heated asphalt back to saturator 80 after it has'passed through the tank Ill and has been heated by the flues therein. An asphalt supply tank 92 which furnishes molten make-up asphalt to replace the asphalt absorbed by, the web passing through the saturator is connected to inlet122 bya pipe 94 which is provided .with a positive pressure pump. 93. ,The. asphalt. from makeeup tank92 4 may be continuously or intermittently pumped into tank H).

An asphalt heatin and circulating system is thus provided in which the heating device of the invention continuously heats the cooled asphalt from the saturator and at the same time heats the make-up asphalt as it is supplied to the system. In operating the heater, one or more banks of flues may be fired, depending upon the amount of heat to' be supplied to the liquid being pumped through the heater. When heavy grades of felt are being saturated, for example, the temperature drop caused by the cooling effect of the felt is greater than that caused by a light weight felt, and accordingly, all three banks must generally be fired, particularly when the felt is being run through the saturator at a high rate of speed. When a light weight felt is being saturated, firing of a single bank may be sufficient to keep the asphalt at the desired temperature. Since each flue is fired by an independent burner it will be apparent that the heater of the invention has great flexibility and maybe utilized to accommodate a large variety of operating conditions. When the heater is in operation, the tank I0 is filled with liquid and the flues are, therefore, submerged at all, times whereby efficient heating is promoted.

While the drawings and the foregoing descrip-; tion of one embodiment of the invention relate to a heater having a vertical casing, the device of the invention may also be effectively embodied in a horizontal casing. It will be apparent that various other changes may be made without departing from the scope of the invention as defined in the appended claims and it is therefore intended that the foregoing shall be interpreted in an illustrative and not in a limiting sense.

I claim:

l. A device for continuously heating molten asphalt and the like to temperatures of the order of 450 F. to 525 F., comprising a tank'adapted for continuous upward pass-age therethrough of the molten material to be heated, and a plurality of individually-fired, sinuous heating flues horizontally disposed in said tank in substantially parallel vertically-spaced relationship, the said flues being arranged in at least two verticallyspaced banks, the flues of one bank being horizontally offset with respect to the flues of the adjacent bank, and each of said flues being arranged to extend over a substantial portion of the internal horizontal cross-sectional area of said tank whereby to permit intimate contact between the exterior surface of the flues and the inolllien material passing upwardly through said 2. A device for continuously heating molten asphalt and the like to temperatures of the order of 450 F. to 525 F., comprising a tank adapted for continuous upward passage therethrough of the molten material to be heated, a plurality of individually-fired, sinuous heating flues horizontally disposed in said tank in substantially parallel vertically-spaced relationship, the said flues being arranged in at least two verticallyspaced banks, and a, stack adjacent each bank of flues adapted to receive the exit gases therefrom, each of said flues being arranged to extend over a substantial portion of the internal horizontal cross-sectional area of said tank whereby to permit intimate contact between the exterior surface of the flues and the molten material passing upwardly through said tank.

3. A device for continuously heating molten asphalt and the like to temperatures of the order of 450 F. to 525 F., comprising a vertical tank adapted for continuous upward passage therethrough of the molten material to be heated, an inlet for the liquid in the lower portion of said tank, an outlet for the liquid in the upper portion of said tank, a plurality of individuallyfired, sinuous heating flues horizontally disposed in said tank in substantially parallel verticallyspaced relationship, the said flues being arranged in at least two vertically-spaced banks, the tines of one bank being horizontally oifset with respect to the fines of the adjacent bank, and each of said flues bein arranged to extend over a substantial portion of the internal horizontal crosssectional area of said tank whereby to permit intimate contact between the exterior surface of the hues and the molten material passing upwardly through said tank.

4. A device for continuously heating molten asphalt and the like to temperatures of the order of 450 F. to 525 F., comprising a, vertical tank adapted for continuous upward passage there through of the molten material to be heated, an inlet for the liquid in the lower portion of said tank, an outlet for the liquid in the upper portion of said tank, a plurality of individuallyfired, sinuous heating flues horizontally disposed in said tank in substantially parallel verticallyspaced relationship, the said flues being arranged in at least two vertically-spaced banks, the flues of one bank being horizontally offset with respect to the fines of the adjacent bank, and a stack tank.

ROBERT L. NALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 793,472 Thorbus June 27, 1905 1,016,411 Isaacs Feb. 6, 1912 1,226,379 Riley May 15, 1917 1,249,480 Pfiugfelder Dec. 11, 1917 1,579,193 Chipman Mar. 30, 1926 1,908,932 Tiburtius May 16, 1933 1,932,793 Lough Oct. 31, 1933 1,949,471 Hildebrand et a1. Mar. 6, 1934 2,137,693 Lundt Nov. 22, 1938 2,176,869 Childs Oct. 24, 1939 2,321,109 Sellers June 8, 1943 2,367,018 Gerges a- Jan. 9, 1945 FOREIGN PATENTS Number Country Date 271,567 Great Britain May 26, 1927

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