US2088103A - Method and apparatus for heating - Google Patents

Description

July 27, 1937. L. WILSON 2,088,103

I METHOD AND APPARATUS FOR HEATING Filed June 13, 1936 2 Sheets-Sheet l INVENTOR @QWM @MMM 2M July 27, 1937. L. wlLsoN METHODAND APPARATUS FOR HEATNG 2 Sheets-Sheet 2 NN MNl INVENTOR Filed June 13, 1936 mm wN NN NI Patented July 27,

UNITED STATES ME'rnoD AND nllntmrrus Fon. HEATING WllsomCleveland, Ohio 4 Application June 13, 1936, Serial No'. v85,091

9 (ci. zes- 14) This invention relates to a method and apparatus for heating and, in particular, to the heating of molten material disposed in a container. While the invention will be described with reference to a galvanizing pot, it has other applications as well.

Galvanizing pots. as heretofore constructed have usually been heated from below by an open flame, although the heat loss which must be made l0 up bythe heatingflame occurs at the surface of the bath, by convection and the passage therethrough of the material being coated, which `is normally at room temperature. It has thus been necessary to heat the bottom of the pot to a temperature much higher than is 4required at vthe surface of the bath, to ensure that the desired operating temperature be obtained at the surface. This problem has 'been aggravated by the fact that the dross which forms on the surface of the bath sinks to the bottom of the pot and forms a layer having relatively low thermal conductivity. Overheating of any portion of the gal- Y vanizing pot is a very serious matter because of the fact that corrosion of the vvalls of the pot (if the latterare of steel, as is usual) proceeds very rapidly at temperatures above 875 F., the

corrosion rate increasing lat higher temperatures.

Such corrosion, of course, materially shortens the life of the galvanizing pot and involves considerable expense forreplacement. r

I have inventeda method and apparatus for heating which is particularly adapted for' galvanizing pots although it has other uses as well.

My inventionovercomes the aforementionedrobjections to the previous practice in the construction and operation of such devices and-is char-.

acterized by additional advantages and features -of novelty which will be described in detail and particularly pointed out in the appended claims. In accordance with my invention, I mount a. plurality of heat exchange tubes atspaced points about a container for material adapted to be heated,.such as a galvanizing pot.

adjacent the walls'of the pot. By means of burners mounted in the upper ends ofthe tubes I supply hot iluids to the tubes whereby-they are heated to radiant condition and radiate heat to the'walls'of the container. The iluids are taken 5o ofi from the lower ends of the'tubes by an exhaust following detailed description, referring to theaccompanying drawings for illustration;

bedded in the foundation II, and plates I6.

The tubes are disposed substantially vertically and closelyV In the drawings, representing a present pre- Y ferred embodiment of the apparatus;

Figure l is a view partly in plan andpartly in section, on an intermediate horizontalplane;

Figure 2 is a view partly in side elevation and partly in section, along line 1I of Figure 1 with parts omitted; and

Figure 3 is a view partly in end elevation and partly in transverse section, along the line III-'III of Figure 1; the plane on which the sec- 1U tional part of Figure 1 is taken is indicated by line I-I of Figure 3.

Referring in detail to the drawings, a receptacle for material to be heated is indicated at I0. In the illustrated embodiment, this is a galvanizing 15 pot through which sheet material -is adapted to ,f be passed for the purpose of coating. The pot CTI has side walls and a bottom, and rests on a foundation I I'of any suitable type. A refractory wall I2 is built -up around the pot and rests on a foot- 20 ing I3. The wall is provided with a refractory layer Il removably supported on the top thereof. The wall is built up of refractory bricks within a casing formed Yby structural members I5 em- Spaced slots Il are formed in the walls I2 at the sides of the pot I0, adjacent the upper edge thereof. Elbows I8 having caps I3 extend through the holes I 'I, the caps I9 being bolted to plates 20 attached to the plates I6. Tubes 2l 30 iextend downwardly from the lower ends of the elbows I8, forming continuations thereof, to a level slightly above the top of the footing.' I3.

An exhaust duct 22 is formed in the footing I3 and is provided with a cover 23 through which 35 "extend anged sleeves 24.V 'Ihe upper ends of thesleeves 24vextend within theV lower ends of the tubes 2l and sealing material 25 such as sand disposed on the cover plate 23 seals the joints b etween the tubes and sleeves. The ducts 22 com- 40 municate-with ues 26 positioned between the walls I2 and the pot I0 adjacent the ends of the latter. Y

Each elbow I8 is provided with a burner 21. Each burner has a spark gap'28 for igniting it, 45 the electrodes forming the spark gap being mounted onvthe burners as shown, and connected to a. transformer 29 carried on a suitable frame 30, by a cable 28a. Y

Fuel is supplied to alternate burners 2'Io'n each 50 side from a header- 3l. 'I'he remaining -burners are similarly supplied with fuel from Va header 32. Individual control valves. 33 are provided for each burner in the connections extending thereto from the headers 3l and 32. 55

Fuel for combustion is' obtained from a supply main 35 whence it flows through branch connections 36 to the inlet of inspirators 31 and 38. The outlets of the inspirators 31 and 38 are connected, respectively, to mixing pipes 39 and 40. The fuel input to the inspirators may be controlled by valves 4I and the function of the inspirators, of course, is to bleed a small amount of atmospheric air into the fuel, such as gas, passing therethrough. Additional air is supplied to the pipes 39 and 40 from an air main 42 and branch connections 43. The connections from the branches 43 to the mixing pipes are shown at 44 and 45. The connections from the mixing pipes to the headers 3| and 32 are indicated at 46. By means of the connections described, a combustible mixture of air and gas is delivered to the burners 21 for combustion in the elbows I8 and the tube 2|. ing through the tubes 2| ent'er the exhaust ducts 22 and are iinally discharged from the upper ends of the flues 26.

The tubes 2| are heated to radiant condition by the passage of hot combustion gases therethrough, and-heat the side walls of the pot by radiation and convection. By reason of the location of the burners adjacent the upper edge of the pot 0, the maximum amount of heatI is liberated adjacent the surface of the material, such Aas spelter, in the pot, the level of 'which might be indicated by the dotted line 41. By the time the combustion gases reach the lower ends of the tubes 2|, they have cooled somewhat and so liberate a small amount of heat to the lower strata of the material in the pot. Baiiles 48 are disposed in the tubes 2| in accordance with the invention described and claimed in the copending application of Wilson et al., Serial No. 49,078, filed November 9, 1935. These baffles increase the amount of heat delivered by the combustion gases to the tubes.

'I'he ends of theburners 21 are bent downwardly. A hot spot appears on the tube wall where the gases from the burner impinge thereon, and by varying the angularity of the burner tip, the locationv of the area of maximum temperature on the tube wall may be so controlled as to supply the greatest amount of heat to precisely the desired point. The refractory layer I4 being removable with its top plate, permits change of radiant tubes without removing the pot and even while it is hot. Conversely, the pot may be removed without disturbing the radiant tubes.

The provision of duplicate supply headers for alternate burners affords a nice control of the amount of heat delivered to the space along the side walls o f the pot. During periods of low production or shut down, alternate burners may be extinguished; The material in the pot, such as spelter, may thus be heated to the proper temperature without danger of local overheating of any portion of the pot itself. Since the heat is delivered to the side walls of the pot, the dross accumulating in the bottom thereof does not interfere with the transmission of 'heat to the material in the pot. The maximum amount of heat is delivered to the spelter adjacent the surface of the bath where the maximum heat losses occur, i. e., by convection and passage of-the relatively cold sheet material therethrough.I By. .avoiding local overheating of the pot, corrosion of the walls thereof is reduced and a longer life assured, reducing the cost of pot replacements.

Although I have illustrated and described but one preferred form of the invention, it will be ap- The combustion products after pass- A therefrom and exteriorly of the walls of .the

vessel. Y

2. Apparatus for heating a container comprising a plurality of radiant tubes disposed side by side adjacent a wall of the container, a header connected to burners in alternate tubes, a second header connected to burners in the remaining tubes, and means for v supplying fuel to said headers. i

3. The apparatus defined by claim 2 characterized by the tubes whose burners are connected to one header being interspersed between the tubes whose burners are connected to the other header.

4. The combination with a galvanizing pot or the like open at the top, adapted to contain molten spelter and dimensioned to receive elongated sheets for coating therewith by immersion, of a plurality o f substantially vertical heat exchange tubes disposed along the side walls of the pot, extending substantially up to the level of said spelter, and in heat-radiating relation thereto, of means for causinga flow of hot uid into the l upper ends of said tubes and downwardly therethrough whereby to heat the tubes to radiant condition and thereby radiate heat to said vessel and to said spelter adjacent its surface.

5. The combination defined by claim 4 charlacteriized by said .means comprising burners disposed to deliver hot combustion gases to the open ends of said tubes for passage downwardly therethrough,

6. The apparatus defined by claim 4 characterized by said tubes being suspended ironia point adjacent their upper ends leaving their lower ends freely floating. i

-7. 'I'he combination with a galvanizing pot r the like, adapted to receive elongated sheets jdr immersion coating in molten spelter contai ed therein, of substantially 'vertical heat exchange tubes extending downwardly along the side walls of the pot and exteriorly thereof from a llevel adjacent the rim of said pot, burners extending into the upper ends of said tubes, and a duct for conveying combustion gases from the lower ends oi said tubes.

8. Heating apparatus comprising a galvanizing pot adapted to receive sheets for coating, a refractory wall extending therearound, and radiant tubes extending downwardly between the wall and pot, Asaid tubes being supported solely from their upper ends whereby they are vertically removable.

9. Heating apparatus comprising a galvanizing4 pot adapted to receive sheets for coating, a relnur: wnsoN.

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