US2856172A

US2856172A - Sectional continuous furnace-kiln

Info

Publication number: US2856172A
Application number: US614919A
Authority: US
Inventors: Kautz Karl
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-10-09
Filing date: 1956-10-09
Publication date: 1958-10-14
Anticipated expiration: 1975-10-14

Description

Oct. 14, 1958 K. KAUTZ SECTIONAL CONTINUOUS FURNACE-KILN 6 Sheets-Sheet 1 Filed Oct. 9, 1956 INVENTOR. KAUTZ KARL ATTORNEYS Oct. 14, 1958 K. KAUTZ SECTIONAL CONTINUOUS FURNACE-KILN e Sheets-Sheet 2 Filed Oct. 9, 1956 FIG. 3

iiiif INVENTOR. KARL KAUTZ BY l ATTORNEYS Oct. 14, 1958 K. KAUTZ SECTIONAL conwmvous FURNACE-KILN 6 Sheets-Sheet 3 Filed Oct. 9, 1956 FIG. 3A

INVENTOR. KARL KAUTZ BY L % j fiw ATTORNEYS Oct. 14, 1958 KAUTZ 2,856,172

SECTIONAL CONTINUOUS FURNACE-KILN Filed 001,. 9, 1956 6 Sheets-Sheet FIG. 4

INVENTOR. KARL KA TZ BY L ATTORNEYS Oct. 14, 1958 KAUTZ 2,856,172

SECTIONAL CONTINUOUS FURNACE-KILN Filed Oct. 9, 1956 6 Sheets-Sheet 5 KARL ii??? ATTORNEYS Oct. 14, 1958 K. KAUTZ SECTIONAL CONTINUOUS FURNACE-KILN 6 Sheets-Sheet 6 Filed Oct. 9, 1956 FIG. 6

KARL

FIG. 7

ATTORNEYS United States Patent SECTIONAL CONTINUOUS FURNACE-KEN Karl Kautz, Pittsburgh, Pa.

Application October 9, 1956, Serial No. 614,919

121 Claims-n (Cl. HES- 6) Theinvention' relates generally to: continuous furnaces andkilh's for1heating, firing and heat treatingivarious prod? nets and materials. More'particularly, theinvention relates to an improvedsectional furnace or kiln adapted for treating various glass and ceramic products over a wide range of temperatures and with controlled atmospheres.

Conventional furnaces and kilns for continuously heating and treating glass and ceramic products are massive and are expensively constructed in place to suit particular products and other specific requirements; e. g. high or low temperatures, mufile firing or direct firing, ordinary atmospheres or controlled atmospheres, etc.

" It is an object of the present invention to provide an improved furnace-kiln made up of prefabricated sections.

which are.easily assembled to provide any desiredlength of furnace, and which are easily disassembled to change the overall length as desired.

Another object is to. provide an improved. sectional.

furnace-kiln which is adapted to be used over a wide range of temperatures for treating a variety ofv products.

A further object is to provide an improvedsectional furnace-kiln which is easily adaptable for. direct or indirect firing.

Another and more specific object is to provide an im proved sectional furnace-kiln having sectional and removable mufile plates.

A stillfurther object is to provide an improved sectional furnace-kiln having a novel conveyor roll construction.

Still another object is to provide an improved furnacekiln having upper and lower muflie plates closely adjacent to.the.conveyor hearth, and means for recirculating the furnace atmosphere through the mulfie chamber below the lower mufile plates to increase thermal efiiciency by convection heating.

These and other objects are accomplished bythe improved furnace-kiln comprising the present invention, a preferred embodiment of which is shown by way of example. in the accompanying drawings and described in detail'herein. Various modifications and changes in detailsofconstruction are comprehended within the scope ofthe invention defined in the appended claims.

The present improved furnace-kiln is particularly adapted for enameling and refractory coating metalsand heat treating such products; for annealing, decorating and forming glassproducts; and for firing, decorating and treatingvarious ceramic products.

Referring .to the :drawings:

Fig. l is a sideelevation of a continuousfurnaceor kilnmaccordingtothe invention having five prefabricated sections, comprising two end sections and three intermedi-. ate sections, connected .togetherin end-.to-end relation;

Fig. v2 isa detached elevationalview, partly insection,

of .one ofthe. improved. conveyor rolls. journaled in the sections.

, Fig... 3 is. an. enlargedlongitudinal sectional. view of thesection: at -the discharge; end of. the a furnace.

Fig. 3A is a similar view in continuation of Fig. 3

showing a part of the furnace intermediate the ends.

Fig. 4 is a similar view in continuation of Fig. 3A showingthe entrance end of the furnace.

Fig. 5 is a transverse sectional view online 5--5 of Fig. 3A.

Fig. 6 is a fragmentary transverse sectional view of' a modification.

Fig. 7 is an enlarged vertical sectional view of one of the refractory rings makingup the'conveyor roll shown in'Fig. 2.

Fig. 8 is an end elevation of said ring.

The assembled furnace" or kiln shown in Fig. 1 com' prises a discharge end section indicated as a WhOlfifit 10, an entrance end section indicated at 11, and three identical intermediate sections indicated at 12. All of these sections are preferably the same length which may be three feet, and they are all prefabricated tubular sections consisting of a steel framework lined with insulating refractory brickwork. The'sections are adapted readily to. be connected end-to-end, so that a furnace-kiln of any desired length can quickly be constructed and disassembled for changing the overall length or for transportation to another location.

The intermediate sections or units 12 will be described first because the end sections are the same basically plus Referring first to Figs. 3A. and 5, each tubular section 12 is rectangular in plan and a few additional features.

transverse section, and has four steel angles 13 extending vertically along its four-vertical corners, one leg of each angle abutting the side of the section and the other leg.

the brickwork lining of the section is supported. The

flanges of abutting angles 13 of adjoining sections are de tachably connected by bolts 20. Between the

horizontal angles

16 and 17 are horizontal angles 21 for supporting the bearings 22 for the roll shafts 23, and horizontal reinforcing channels 24 may connect the corner angles 13 at points spaced above the roll bearings. The top ends of opposite angles 13 are preferably connected by tie bolts 25.

The refractory sidewalls lining the framework are indicated generally at 27, and mainly constitute insulating.

refractory brick capable. of withstanding high tempera-. tures and laid up with insulating cement. The roll mounts ing blocks28 and 29 are preferably of fire clay and accurately located to properly position the roll shafts 23-. Above the roll blocks are two vertically spaced

ledges

30 and 31 for supporting upper muifie plates, and these ledges are preferably formed by courses offirebrick to reduce'breakage. Belowthe roll blocks are similar Vertically spaced

ledges

32 and 33 for supporting lower muffle.

plates.

A central longitudinal supporting wall 340i .open construction is preferably of firebrick and the furnace bottom. 35 between the side walls 27 and central wall 34 maycon sist of insulating refractory castable material supported: on the bottom. plate. 19. The top of the furnace is closed:

between the side walls by, aroof blockassembly of: in-:

sulating refractory blocks 36 held" together. by. tie: bolts. 37. connected. at their ends'to. angles 38 resting on the tops. of the-side Walls; Thisrzroofiassembly can be removed as a unit when necessary, to replace or relocate the upper mufile plates.

A ware or conveyor chamber enclosing the rolls carried on shafts 23 is formedby horizontal upper and

lower muffie plates

41 and 42 respectively. These plates may be of heat-resistant alloy such as stainless or Inconel and are supported on ledges formed in the refractory side walls. As shown in Figs. 3A and 5, the upper plates 41 may be supported on ledges 31 and the lower plates on ledges 32. Another series of lower muflle plates 43 may be supported on the lowermost ledges 33 for a purpose to be described. These plates 43 may be of lighter gauge than plates 42 because they carry no load. To meet certain requirements the upper muffie plates 41 may be supported on the upper ledges 30. Fig. 6 shows silicon carbide mufile plates 141 supported on the upper ledges 30. Sectional muffle plates, arranged in the form of an arch may also be used. The steel framework supporting the refractory lining in Fig. 6 would be the same as in Fig. 5, but has not been shown.

Preferably, the upper muffle plates 41 have their central portions suspended on the lower flanged ends of vertical rods 45 extending through the roof block assembly, two such rods being shown for each section. The upper flanged ends of the rods 45 may be yieldingly suspended on spring steel strips 46 adjustably supported at their ends on bolts 47 projecting upwardly from the roof blocks 36. By using the suspending rods 45 a substantially lighter gauge of muffle plate can be used, representing a substantial saving in the high cost of heat-resistant alloy plates. Adjusting the nuts on bolts 47 applies enough tension to the rods 45 to prevent sagging of the mufile plates.

The

mufile plates

41, 42 and 43 may have grooves along one edge receiving the edges of adjoining plates to form joints which can be sealed with a suitable refractory cement, by welding overhanging metal strips along the top and bottom edges of the plates. Silicon carbide strips 148 of H cross section can be used to connect silicon carbide muflle plates 141, as shown in Fig. 6, and thus substantially prevent failure of the plates by cracking or breaking in any direction. Additional precaution against failure of such plates may be obtained by suspending the central portions of said plates on silicon carbide rods 145 supported at their upper ends on spring strips 146 carried on bolts 147.

As shown in Figs. 3A and each section 12 has two transverse roll shafts 23 which extend through the

roll mounting blocks

28 and 29 in the side walls 27. These shafts are preferably hollow and of heat-resistant alloy. Between the side walls, each shaft has secured thereon end caps 49 (Fig. 2) of heat-resistant alloy, and between the end caps the roll casing may be of heat-resistant alloy for temperatures up to 1900 F. For higher temperatures a silicon carbide casing is used, comprising abutting refractory rings 50 of silicon carbide forming a hollow roll 51. Each ring 50, as shown in Figs. 7 and 8, has an annular core of insulating refractory 52 having a center bore 53 for fitting the shaft 23. Each ring has a concentric groove 54 on one face and a concentric rib 55 on the other face for fitting in the groove 54 of the adjoining ring. Both faces of the rings are provided with V-shaped grooves 56 to match the grooves on adjoining rings and form interconnecting ring joints when filled with insulating cement or the like to lock the rings together.

An air-setting cement weaker than silicon carbide is preferred to minimize cracking along the roll, because if one ring should crack, the Weaker cement in the joints would fail before the stress is carried over to adjoining rings, so that a number of rings could crack in misaligned locations without making the roll ineffective. The roll may be made up by placing a shaft on end and laying the successive rings with cement on one end cap, to the desired length, and the other end cap- 4 installed. After curing and drying the roll can be dressed to size. Thus, rolls of varying lengths may be built using multiples of one standard size ring.

These rolls are suitable for relatively high temperatures of the order of 1900 F. to 2400 F. and the silicon carbide rings are extremely abrasion resistant and have a long life when used to convey ceramic slabs and the like. If metal plates, cables or belts are passed over the rolls at somewhat lower temperatures, the silicon carbide rings will cause abrasion of the metal, and this can be avoided by spirally wrapping the rolls with a metal ribbon of heat-resistant alloy, say about 2" wide, thus eliminating the need for replacing the rolls with expensive rolls having casings of heat-resistant alloy such as Inconel.

The end sections 10 and 11 of the furnace are generally similar in construction to intermediate sections 12, except for the addition of a refractory brick wall in one end. Referring to Fig. 3, the exit or discharge end section 10 has the refractory upper end wall 56 extending from the upper mufiie plates 41 to the roof blocks 36, and the lower refractory end wall 57 extending from the bottom wall 35 to the upper row of lower muffle plates 42. These

end walls

56 and 57 close the end section above and below the conveyor opening in which the rolls 51 are located.

Burner blocks 58, preferably two in number, are built into end wall 56 above the ledge 30, and similar burner blocks 59 are built into end wall 57 between

lower mufiie plates

42 and 43. Thus, the burner blocks 58 fire into the upper muffle chamber M whether the upper muffle plates 41 are supported on the ledge 31 as shown or on the ledge 30. The burner blocks 59 fire into the lower muffle chamber M formed between the

mufile plates

42 and 43. Intake blocks 60 are built into end wall 57 below the mufile plates 43 to introduce hot air or gas into the chamber R formed below the muflle plates 43 for a purpose to be described.

A framework extension is attached to the outer end of discharge section 10, and may comprise vertical angles 13A and horizontal angles 62 supporting a horizontal plate 63 at a level just below that of the muflie plates sections indicated generally at 68 may be connected to the discharge end section 10 when the furnace is used as a kiln. The cooling section adjoining the furnace end section 10 encloses the upper portion of the drum 64 and preferably has one conveyor roll 51A journaled in its side walls. Additional cooling sections having vertical angles 13A may be attached in a manner similar to the manner of connecting the

furnace sections

10, 11 and 12.

The conveyor passing over the drum may consist of a number of strands of heat-resistant metal cables 70 in side-by-side relation as shown in the drawings, or one or more wire mesh belts. In using cables, a plurality of pulley grooves may be provided in the drum surface, and cables 70A can be carried on the drum 64 between the cables 70 to extend the conveying surface through the cooling sections 68, as indicated in chain lines in Fig. 3. Where a wire mesh conveyor is used in the furnace, a separately driven conveyor would be required in the cooling sections. The return run of conveyor cables 70 passes under an idler roll 71 on the framework of the end section 10 and is supported on suitable idler rolls 72 on the lower part of the framework of

sections

10, 11 and 12.

Referring to Fig. 4 the entrance end section 11 of the furnace has a refractory brick end wall comprising upper and

lower portions

56 and 57 similarto the" endxwall in:

Means for tightening individual cables 70 mayconsist ofa series of pulleys 78, one for each cable, carried on take-up bolts '79 movably mounted on cross bars 80 attached to the vertical framemembers 75, and having springs 81 applying tensionto said. bolts. Thereturn runs of the cables pass. throughupper and lower thrust rolls 82 and 83 and then to the take-up pulleys 78. From the take-up pulleys the .cablesarewrapped around a thrust drum 34 and thence go. tov the vidlerdrum 74.

On the top members 77 of :the framework is carried an exhaust fan 85. and its driving motor 86. The intake duct 37 to the fan is connected by-suitableducts 88', extending vertically downward around the sides offurnace section 11, to exhaust

ducts

89 and 90 connected into the endsof the mufile chambersM and M (see Figs. land 4). The exhaust ducts serve to exhaust the products of combustion from the mufiie chambers as fired by the

burners

58 and 59 at the other end of the furnace.

A furnace of variable length, such as shown in Fig. 1, and built up of

sections

10, 11 and 12. is adapted for firing enameled aluminum or steel products, for decoratinggglass or china, and for firing other ceramic products, requiring temperatures from about 900 F. to.1900 F. The close spacing of the

muffie plates

41 and 42 provides for efiicient heating of the ware by radiation in the low temperature ranges. For firing ware requiring'temperatures from about 1900 to 2300" F., the silicon carbide muftleplates 141 supported by silicon carbide suspension rods 145, as shown in Fig. 6, could housed, and refractory slabs 170 carrying the ware could be moved through the furnace on the silicon carbide rolls .51.

If direct firing of the conveyor chamber is desired, this is easily accomplished by removing one or two of the: upper muffle plates 41 at both ends of the furnace and blocking off the rest of the upper muflle chamber M Thus the products of combustion from the burners are forced to travel below the muffle chamber and through the conveyor chamber to the exhaust ducts 89 at the opposite end. The lower muffie chamber need. not be used if completely direct firing is desired.

When firing in the low temperatures where heating by radiation is not very efficient, additional thermal efiiciency can be obtained by providing convection, heating in addition to the radiation heating. This may be accomplished easily by introducing hot air or gas intothe lower chamber R below muffie plates 43through the inlets 60 at the ends of the furnace. The air isforced toward the central part of chamber R where it passesupwardly through the vertical pipes 91 (Figs. 3A and 5) and flows therefrom in opposite directions over and under the conveyor toward the ends of the conveyor chamber. Near the ends of the chamber, the hot air or gas is collected by exhaust ducts 92, preferably in the side walls of the end furnace sections, and returned to the intake blocks 60 by suitable blowers and duct work (not shown) to recirculate it through the furnace. The exhaust ducts 92 are located near to, but not at, the extreme ends of the conveyor chamber so that very little cold air is drawn in while only a small amount of hot air is lost, without requiring doors at the ends of the chamber.

The improved furnace is easily adapted for using con trolled atmospheres in the conveyor chamber, by providing gas-tight seals around the roll shafts in the roll mounting blocks, and sliding doors at both ends of the furnace for retaining any desired atmosphere therein. Thus adapted, the furnace would be capable of operating at reducing temperatures of 2200 F. to 2400 F., and

chamber R in place of hot air;

Theprescnt invention comprises a multi-purpose combination continuous furnace-kiln which is readily adapted; for. heating andtreating a large variety. of productsiover; The overall length. is

a wide range of temperatures. quickly and easily varied by merely changing the. num:

ber of prefabricated sections. The furnace-kiln is ideally, suited, for example, for firing aluminum enamelsat 900 F; to l000 F., for decorating glass or china M13509. F., or for firing ceramic wareat temperatures; up to. 1900 F, without changing anything except conveyors speed and temperature. For highentemperatures', theufew changes required, such as substituting silicon. carbide mufile plates and ware-conveying slabs,.are quicklyyand: The cooling sections 68.at'-the.discharge:.=

easily made. end are easily added or removed, asrequired.

What is claimedv is:

1. A continuous furnace-kiln comprising a plurality of. substantially identical tubular sections detachably. joined: together in end-toend relation, the sections at opposite;

ends having and walls, each of the sections having refractory walls and a steel frameworkadapted for connection. with the framework of an adjoining section, each section having a transverse conveyor roll journaled in op:- posite walls, upper and lower muffle plates substantially coextensive with each section and supported on. said walls above and below said roll forming upper and lower mufile chambers, burners in the end wall of, one end 860-.

tion for firing into one end of said muffle chambers,.and exhaust means communicating with the opposite ends of said chambers.

2. A continuous furnace-kiln comprising a pluralityof substantially identical tubular sections joined together in end-to-end relation, the sections at opposite ends having; end walls, each of the sections having refractory walls and a steel framework adaptedifor connection with the.

framework of an adjoining section, each section having a transverse conveyor roll journalediin opposite walls, up-

means communicating with the opposite ends of said chambers.

3. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections joined. together. in end-mend relation, the sections at opposite ends having end walls, each section having refractory side, top and. bottom walls lining a steel framework adapted for con-.-

nection with the framework of an adjoining section, the

top wall of each section being separatelyrernovable as. a unit, a transverse conveyor roll journaled in the side; walls of each section, upper and lower muffie plates supported on said side walls above and below said roll andforming upper and lower muffle chambers, burners in the end wall of one section for firing into one. end of said mufile chambers, and exhaust means communicating with the opposite ends of said chambers.

4. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections joined together in end-to-end relation, the sections at opposite ends having end walls, each section having refractory side, top and bottom walls lining a steel framework adapted for connection with the framework of an adjoining section, the top wall of each section being separately removable as a unit, a transverse conveyor roll journaled in the side walls of each section, upper and lower mufile plates supported on said side walls above and below said roll and form ing upper and lower mufile chambers, spring suspension means supporting the central portion of each upper muffie plate from the top wall of each section, burners in the end wall of one section for firing into one end of said muffle chambers, and exhaust means communicating with the opposite ends of said chambers.

5. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections detachably joined together in end-to-end relation, each of the sections having refractory walls and a steel framework adapted for connection with the framework of adjoining sections, a transverse conveyor roll journaled in opposite walls, and upper and lower muffie plates supported on said walls and forming mutfie chambers above and below said roll, said mufile plates being horizontaly coextensive with said section and adapted to have their edges abut the edges of adjoining mufile plates.

6. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections detachably joined together in end-to-end relation, each of the sections having refractory walls and a steel framework adapted for connection with the framework of adjoining sections, a transverse conveyor roll journaled in opposite walls, upper and lower muffle plates supported on said walls and forming muflle chambers above and below said roll, said mufiile plates being horizontally coextensive with said section and adapted to have their edges abut the edges of adjoining muflle plates, and spring suspension means supporting the central portion of the upper muffle plate from the top wall of the section.

7. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections detachably joined together in end-to-end relation, each of the sections having refractory walls and a steel framework adapted for connection with the framework of adjoining sections, the top wall of the section being separately removable as a unit, a transverse conveyor roll journaled in opposite walls, and upper and lower muflle plates supported on said walls and forming muffle chambers above and below said roll, said muflle plates being horizontally coextensive with said section and adapted to have their edges abut the edges of adjoining muffle plates.

8. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections joined together in 'end-to-end relation, each of the sections having refractory walls and a steel framework adapted for connection with the framework of adjoining sections, the top wall of the section being separately removable as a unit, a transverse conveyor roll journalled in opposite walls, upper and lower mufile plates supported on said walls and forming mufile chambers above and below said roll, said mufile plates being horizontally coextensive with said section and adapted to have their edges abut the edges of adjoining muffle plates, and spring suspension means supporting the central portion of the upper muffle plate from the top wall of the section.

9. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections joined together in end-to-end relation, each of the sections having refractory walls and a steel framework adapted for connection with the framework of adjoining sections, a transverse conveyor roll journaled in opposite walls, and upper and lower muffle plates supported on said walls and forming muffle chambers above and below said roll, each section having a second lower muffie plate spaced below the first and forming a recirculating chamber along the bottom wall of the section, all of said muffle plates being horizontally coextensive with said section and adapted to have their edges abut the edges of adjoining muffle plates, vertical pipes in at least one of the intermediate sections connecting said recirculating chamber with the space between the upper muffle plate and the first lower muffle plate for conducting air from said recirculating chamber into said space.

10. A continuous furnace-kiln comprising a plurality of substantially identical tubular sections joined together in end-to-end relation, the sections at opposite ends having end walls, each of the sections having refractory walls and a steel framework adapted for connection with the framework of an adjoining section, each section having a transverse conveyor roll journaled in opposite walls, upper and lower mufiie plates supported on the walls and forming a conveyor roll chamber between upper and lower muffle chambers, a second lower muffle plate spaced below the first and forming a recirculating chamber above the bottom wall of the section, a vertical pipe in at least one of the intermediate sections connecting said recirculating chamber with said conveyor roll chamber, air intake means in the end walls of said end sections communicating with said recirculating chamber, and air exhaust means in the side walls of said end sections communicating with said conveyor roll chamber.

11. The method of recirculating heated air through a continuous furnace having a conveyor chamber extending longitudinally therethrough and a muffle chamber parallel with said conveyor chamber, comprising withdrawing heated air from said conveyor chamber adjacent to its ends, forcing said air through the ends of said furnace along the outer side of said muffle chamber, and conducting said air through the central portion of said muffle chamber to the central portion of said conveyor chamber.

12. The method of recirculating heated air through a continuous furnace having a conveyor chamber extending longitudinally therethrough and a mufile chamber parallel with said conveyor chamber, comprising withdrawing heated air from said conveyor chamber adjacent to its ends, forcing said air through the ends of said furnace along the outer side of said mufile chamber, and conducting said air to the central portion of said conveyor chamber.

References Cited in the file of this patent UNITED STATES PATENTS 651,461 Jenkins June 12, 1900 1,285,750 Lewis et al. Nov. 26, 1918 1,296,122 Roth Mar. 4, 1919 1,525,130 Hinsdale Feb. 3, 1925 1,808,152 Bailey June 2, 1931 2,135,175 Fallon Nov. 1, 1938 2,428,344 Stookey Sept. 30, 1947 2,468,456 Ness Apr. 26, 1949 2,729,872 Peterson Jan. 10, 1956 FOREIGN PATENTS 605,501 Germany Nov. 29, 1934