US1079443A - Continuous kiln. - Google Patents

Description

r. I). SHAW. CONTINUOUS KILN. APPLICATION FILED FEB/16, 19 10.

Patented Nov. 25, 1913.

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F 0% 2 W020? .1 w W n06 5 Inventor F. D. SHAW.

CONTINUOUS KILN.

. APPLICATION IILI-ID FEB. 16, 1910.

1,079,443, Patented NOV. 25, 1913.

3 SHEETS-SHEET 2. J F W Wfifinesses: [77997-71507;

F. D. SHAW.

CONTINUOUS KILN.

APPLICATION FILED PEB.16, 1910.

1,079,443, Patented Nov. 25, 1913.

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FRANCES n. snhw, or (intense, imitators, hssremoa 'ro snllw mm? comm-NY, or

ATLANTA, enomm, A conromtrm'n or GEORGIA.

conmmnotrs KILN.

Specification 6! Letters Patent.

Patented Nov. 25, 1913.

Application filefi res-mew 16', ion. Serial No. 544,183.

a part of this specification.

My invention relates "to continuous kilns, and has special reference to kilns which are adapted to burn brick and various forms of pottery.

Many attem ts have been made, particularly in the brick industry, to decrease the time which is necessary for the proper burning of brick. According to the system which has been most generally employed, the brick are piled up in a kiln which is slowl heated in order to drive out the water which is mechanically contained in the clay or other substance of which the bricks are manufactured. The heat of the kiln is gradually raised until finally the maximum temperature is attained, and the fires are then drawn and the kiln with its contained brick is gradually allowed to 'cool. This method of burning necessitates the use of a large amount of time, and has the further objection that the brick are not burned uniformly. Each brick of course remains in exactly the same position throughout the entire burning oper ation, and inasmuch as it is impossible to obtain the same heat in all parts of the kiln there is great lack of uniformity in the product which is obtained.

It has long been recognized that the two inherent disadvantages of the ordinary form of kiln, namely, the excessive heat required in burning and the lack of uniformity in the product obtained, might be overcome by the useof continuous kins. 1 It is necessary, in order to provide an efliclent continuous kiln, that there 'should be a combinationof, various features. The brick to be burned should be placed on a car or other movable sup ort, and with a steady movement passed t rough-the kiln, first entering a drying chamber, here the water mechanically held inthe clay or other material of which the brick is formed, is driven off: The brick are then passed'intoa zone" of the kiln where they are gradually subjected to, an increasing temperature until temperature necessary to effect the vitriiying action-is attained.

e third zone consists of that portion of the kiln Where the heat gradually decreases the brick are finally delivered from "the I order that the heat in the kil may be readily controlled, have found it of advantage to employ a plurality ofstacks addi'ti'onfto the main stack of the kiln. By means of these subsidiar stacks it is possible to withd'raw the hot gases from the kiln as desired, and thus obtain a more e finally the maximum cient regulation of the temperature than would b possible if reliance were plac d entirely on the regulation of the "source of heat and the damper in the main stack.

It has been recognized by those skilled in the art that the most eilioient method known up to the present time for transporting the brick through the kilnconsists in the use of cars on which the brick ma be piled. In order to prevent the cars iiom warping excessively and being und'ul'y heated b the action of the flame, these cars have been provided with a heat-insulating portion which forms the bottom of the heating chamber of the kiln, and means have been provided for sealing communication between the heatin chamber and that'portion of the kiln which lies below the cars. In order to obtain eflicient results I have found that it is essential'that the seal between the heating chamber and the lower portion of the kiln should be as eflectiv'e as possible. I have found that a sand seal betweenthe sides of the cars and the walls, of the kiln gives excellent results, it often be;

advisable to mix a certain percentage of ta c with the sand in order to allow the downwardly projecting sealing members of the cars. to pass easily through the sand seal.

the ends of the cars, I have einployed a special form of brick, so that a tongue. on one car will fit into a, correspondi groove of the brick on the adjacent car. y means of the seals which have "just been mentioned, cold air is prevented from being drawn from the lower part of the'kiln intothe heating chamber. I114 or" er to propel the cars (ion- In order to provide an efiicient seal bet-ween its tiniio'usly through the kiln I have found that the best resultsare obtained by the use of a 'c'ontlnuous cable'lwhich passes over suit able sheaves near the ends of the kiln. The

carsare individually gripped to this cable \by means of a special form-"of grip which will be described hereafter, and on reaching the eduction end of the kiln the cars are 5 automatically ungripped from the cable,

and by meansof any of the well-known transfer cars may be moved to a second. re-

' turn'track, and after the burned brickshave been removed, the various cars may be returned-to the entrance of the kiln by a cable running in the opposite direction from that which is within the kiln, and after being loaded with brick are ready to again pass through the kiln.

Great difliculty has been experienced in properly drying the brick as they pass through the first or drying zone within the kiln. It is evident that a considerable v amount of water must be driven from the brick, and in order to prevent the condensation of the resulting steam in the main stack I have found that condensing means in con-' nection with the drying chamber itself should be employed. In order to effect the desired rqsult I construct the condensing chamber of sheet-iromsteel or other suitable metal, the roof of the chamber consisting of two straight sides which come to- .gether at a comparatively acute angle. The steam which has been formed from the water within the bricks, on striking this metallic roof, condenses, and by means of suitable troughs it is caused to flow out of the drying chamber. In order to still further facilitate this action and also to prevent the roof from warping, I have found it of advantage to water-cool the outside of the roof, thus keeping the metal at a comparatively constant temperature.

40 As pointed out above, one of the disadvantages of the stationary'kiln is the lack of uniformity which is obtained in the heat to which the brick are subjected. Similar results will be obtained in a continuous kiln unless suitable means are provided by which the heat is evenly distributed across the kiln.

' That is, it is necessary that the bricks toward the outside of the heating chamber should be subjected to the same heat as those nearer the center line. To attain this result I employ a special form of damper in connection with the main stack. This damper operates across the entire kiln and serves to cause the .hot gases to pass to substantially the same extent on the sides and through the central line of the kiln; A damper. is provided on each side of the ,stack so that the flow of gases may be regulated, as desired, through the portions of the kiln lying on either side so of the stack. p

It/has been customary in many forms of to employ an oil burner which has a flame direct ass through the k1 Such a method of 5' Beating is very unsatisfactory, in that it line 7-7 of Fig. 1. Fig. 7 is a detail sec- 3 of the side walls of chamber B, these walls y impin%illlg .on the brick as they water is introduced in the gas generator with the oil, the gasesare caused to burn comparatively slowly, and after being introduced into the kiln the slowly burning gases afford heat through a much greater length of kiln than is possible by the use of the ordinary form of burner.

These and other advantages of my invention will be more apparent by reference to the accompanying drawings, in which- Figure 1 is a diagrammatic plan view of my continuous kiln. Fig. 2 is an enlarged sectional view on the line 2-2 of Fig. 1. Fig. 3 is an enlarged sectional view on the line 3-3 of Fig. 1 showing a car of brick in position within the kiln. Fig. 4 is a fragmentary side elevationof a portion of the kiln showing the gas generators and burning chambers. Fig. 5 1s a sectional view on the line 55 of Fig. 4:. Fig. 6 is a side elevation showing the method of preventing the passage 0 air between adjacent cars. Fig. 7 is an enlarged sectional view on the tion on line 7 a of Fig. 7. Fig. 8 is a plan view showing the method for automatically removing a car from itsconnection with the cable. Fig. 9 is a pers ective view of certain metallic strips 0 inverted V-shaped cross-section. I

As shown most clearly in Fig. 1, the kiln has two distinct portions, first, the portion A, which forms the drying chamber, and second, the portion B, which consists of a heating and cooling chamber, and extends from the chamber A to the eduction end of the kiln. The portion 13 of the kiln has the side walls 1 and the arch 2. At the portion are considerably thickened in order to alford suflicient space for the burning chambers which will be described hereafter.

As shown in Figs. 1 and 7, the main stack 4 communicates through the roof 2 with the inside of the kiln. A damper 5 is provided on each side. of the stack 4, and is operated by means of the wheel 6, which is rigidly mounted on the end of shaft 7. The pinions 8, 8 are suitably mounted on the shaft 7, and cooperate with the racks 9, 9 which are mounted on the damper 5. It is thus evi-.

damper 5 may be raised or lowered as desired,-'and the, passage of gases from the kiln to the stack may thus be regulated. By the use of such dampers it is evident that the draft is distributed evenly across. the kiln, and for this reason all of the bricks which are in any given transverse plane are subjected to the same amount of heat. 7

v The general construction of the inside of the kiln is clearly shown in Figs. 2 and 3. A sheave 10 is provided near each end of the kiln, and a cable 11 passes over these two sheaves. One of the sheaves is mechanically driven by any of the well-known means, so

that the cable 11 is continuously in motion.

The construction of the inside of thekiln is such that a pit 12 is formed, through which the cable 11 passes. This pit is made of suflicient size, so that it is readily possible for a man to walk through the same. The brickwork of the inside of the kiln is built above the pit 12 in such manner that the' ledges 13, 13 and 14, 14 are formed. On the ledges 13, 13, are mounted the rails 15, 15, considerable space being left between the ends of adjacent rails in order to allow for expansion and contraction caused by variations in temperature. These rails are not rigidly fastened to the ledges 13, 13, but are so fastened with spikes that the rail is, allowed to expand and contract longitudiw nally without displacing the spikes. To the ledges 14, 14 is secured the inverted V- shaped strip of sheet metal 16, which forms a trough between one of its sides and the side of the kiln, in which the sand 17 is placed. Through the length of the kiln there are a number of thesesho'rt inverted V-shaped strips 16, which overlap each other and are attached to the ledge 14 by means of nails or other suitable fastening means, which pass through slots 16 in the metallic strips, as shown in Fig. 9. In this way the expansion and contraction of the strips 16 is provided for, with no danger of causing buckling when the temperature is increased.

Mounted on the tracks 15, 15 is the car 18, from .the sides of which there are downwardly projecting flanges 19, 19, which pass into the sand seals 17, and in this way prevent passage of gases from the portion of the kiln chamber lying below the car 18' to the portion of the chamber lying above the car. In order to allow an easy passage of the flanges 19, 19 through the sand 17 as the car is being moved, I find it of advantage to mix a considerable percentage of tale with the sand. The car 18 .is provided on its upper surface, with a plurality of fire bricks 20, 20, these bricks having corrugations 21 on their upper surfaces, as best shown in Fig. 3. These corrugations extend longitudinally of the car, so that the hot gases passing through the kiln are allowed to go underthe bricks 22.which are placed on the corrugations 21 of the fire bricks 20. The fire bricks on the two sides of the car ferent vertical are provided with lateral projections 23, which extend under shelves 24, 24 projecting from the side of the kiln. A small amount of sand 25 may be placed on the projections 23 in order to still further add tot-he efficiency of the sand seals. As shown in Figs. 3 and 6, the fire bricks 20 are joined by means of tongue-and-groove joints. In order to aid in keeping the bricks 20 cool, holes 26 pass longitudinally through the bricks and register with each other on ad- ,jacent cars.

position by means of one of the grooves 30.

It'is clear that as the cable exerts its pull on the car, the cam 29 will be forced to grip the cable 11 more firmly as more and more pressure is exerted) When the car approaches the end of the kiln, the handle 31 strikes a trip 32 which is rigidly mounted on the kiln. The effect of this trip is to automatically turn the cam 29 so that the pressure on the cable 11 is released and the car is no longer moved by means of the cable, but by means of the pressure of the next car behind. At the point where the curve, as shown most clearly in Fig. 8, and

in this way the hook 28 is moved into a difplane from that occupied by the cable 11. In this way the car is automatically entirely freed from'the cable. As

explained in the preamble of this specification, after the car passesthrough the kiln ,it is moved by a transfer car to a second track which returns it to the entrance end of the kiln. This operation is well known in the art, however, and it is unnecessary to describe it further in this connection.

As explained above, the portions 3, 3 of the Walls 1, 1 are constructed somewhat thicker than the remaining portions of these walls in order to allow sufficient space for the gas generators and burning chambers which are placed therein. The exact relation of these. parts is shown most clearly in Figs. 4 and 5.

The gas generator consists of a pan or dish-shaped vessel 33 having flaring edges 34. This pan rests on the bottom of chainber 35 within the wall 3, the front of this collar 36 having the flange 37 is-supported from thebrick-work ofthe kiln, so that the chamber being open to the atmosphere. A l

lower edge of the collar 36 is within the dish-shaped vessel 33, but with the lower edge of the collar somewhat above the bottom of vessel 33. The main oil pipe 38 is supplied with branch pipes 39, in which are placed the valves 40. The oil coming through the pipe 39 enters the funnel 41 and;

passes downwardly through pipe 42 into the dish-shaped vessel 33. The upper end of the collar 36 communicates with the opening 43 leading into the burning chamber 44, which in turn communicates through the port 45 with the heating chamber of the kiln. The burning chamber 44 is supplied with a front wall 46, in which there is ordinarily placed a peep-hole 47, closed by the brick 48. A pipe 49-is supplied with water, in which a small amount of ammonium nitrate or other similarchemical is dissolved,

by means of the pipe 50 communicating with the barrel 51 in which the solution is placed. A great variety of salts may be used to form the solution above mentioned, the object of which is, first, to make the combustion of gas slower by introducing Water into the oil which is being gasified,

' and, second, the presence of a salt has the effect of facilitating the vitrifying action.

I have found that a very small amount of the salt is sutlicient, and ordinarily I use about a half pound in a barrel of water, but I do not wish to confine myself to this particular amount, as it may be varied within very wide limits. Communicatin with pipe 49 are the pipes 52 supplied with valves 53, the solution from the main pipe 49 thereby being conducted through pipes 52 into the funnels 41. The oil and the wardly into the combustion chamber 44, the

products of combustion thence passing into the burning chamber of the kiln itselfx As shown in Fig. 4, a considerable number of gas generators of the type which I have described are used on each side of the furnace, the burners on opposite'sides preferably being placed opposite to each other rather than in staggered positions, although the latter arrangement may be used. I'Vhen the gases enter the main burning chamber of the kiln itself, the presence of steam delays the combustion so that the heat is distributed along the length of the furnace to a much greater extent than in the case of furnaces of prior construction.

In order to afford regulation of the heat in the kiln the stacks 54, 54 are provided in thewalls 1, 1, these stacks being equipped with dampers of any well-known type. When it is desired to lower the temperature between the stacks 54, 54 and the main stack 4, the dampers of stacks 54, 54 are opened, and the hot gases pass from the kiln into these stacks, thereby bringing about the desired action. The connection between the main kiln chamber and these stacks is shown in Fig. 2. A further regulation of heatis obtained by means of stacks 55, 55 placed near the point of junction of the main kiln B and the dryingchamber A. These stacks may be used to withdraw the gases from the drying chamber A when it is not desired to have all of such gases pass into the main stack 4. It will be evident that by means of the dampers 5, 5 used in connection with the main stack 4 and the stacks 54, 54 and 55, 55 an excellent regulation of the heat in the kiln is obtained.

The drying chamber A is preferably constructed as shown in Fig. 3, the roof consisting of' two mctallicsheets 56, 56, preferably of iron or steel, which are joined at the peak 57. The troughs 58, 58 and 59, 59 are provided in connection with the sheets 56, 56, and have a slope toward the entrance end of the drying chamber A. As the water is driven out of the bricks 22, the steam thus formed condenses on the inside of the sheets 56, 56, and-the moisture runs down and is collected in the troughs 58 58 and 59, 59, and thus conducted out of the drying chamber A. In order to further facilitate this operation and prevent the metallic roof of the drying chamber from warping, the plpes 60 are provided, these, pipes connecting w th the main 61 These pipes are provided with perforations 62 so that when water is turned on,- this water will flow through the perforations in thepipes 60, 60, and serve to keep the roof water-cooled.- Although I have described this particular form of roof as being very advantageous, it is by no means necessary that the drying chamber should be constructed in the way that I have described, inasmuch as I have found that it is feasible to have the drying chamber of the same construction as the mam portlon of the kiln, the water which is expelled from the drying bricks bein partly absorbed by the fire brick of the rying chamber and partly passing outwardly through the stacks of the kiln. When'such a construction is used, however, I have found that more or travel through the kiln varies greatly accord ingto the length-01f the kiln, the kind ofbrick which are being burned, the temperature employed, and the distribution of the heat. In; ordinary practice, however, with a kiln having atotal' length oftwo hundredfeet,

including the drying chamber, I have found that aspeed of about one foot per minute gives excellent results when burning brick of sandand-lime. As the car enters the drylug-chamber A, the heatgradually increases as the car travels onward in its course. The effect of this heat is to gradually dry the brick, the water which is expelled being formed into steam, which, as explained above, condenses on the metallic sheets 56,

. iififorming the roofof the drying chamber.

It is very important that the drying opera- $10!) should be thoroughly performed, mas much as when the brick pass to the burning portion B of the kiln, if the mechanically held water has not been thoroughly expelled, the sudden increase of heat will cause steam to be formed withinthe brick, and a violent disruption or explosion ofthe brick is apt toltake place. In many of the kilns of the prior art it has been customary to use a comparatively narrow kiln and pile a great many bricks on the cars which are travelmg through the kiln. In this way it has been impossible to conduct a proper drying operation in the drying chamber, for the reason that the amount of' Water to be expelled from the brick is so excessive that the heat available and the time during which the bricks remain in. the drying chamber are insuiiicient to rop'erly perform the operation. In my served that the kiln is comparatively broad,

preferably not less than twice the height ofthe arch above the car top, and when burnmg sand lime brick only a single layer of brick is placed on the car. When ,burning clay brick, on the other hand, more than one layer will be built up on the car, but even under such conditions the construction of the kiln is such that the gases obtain free access to the brick, anchthe amount of water to be evaporated is not so excessive but that it IS readily taken care of in the drying chamber. From the drying chamber A, the car next passes into the main burning zone of the portion B of the kiln. As explained above, the distribution of the heat may be regulated by means of the dampers 5, 5 of the main stack 4 and the dampers of the stacks 54, 54 and 55, 55. The heat gradually increases in the kiln until the car reaches a of the walls 1, 1. In this portion of the kiln 1111, however, it will be obposition opposite the portions 3, 3

will be evident; that on account of the loca tion of the main stack 4, none of the gases passing from the gas generators in the thickened walls 3, 3 will pass into the cooling zone, althougha large/amount of heatpasses into this zone by radiation and onaceount,v

of absorption of heat by the walls of the kiln from the hot brick which have passed from the heating zone of the furnace. When the car reaches a position near the eduction end ofthe kiln, the handle 31 of the grip29 strikes the trip 32, and inasmuch as the car passes slightly in a lateral direction on accountof' the curve in the track, the cable 11 is freed from the book 28. After being freed from the cable 11 the car is pushed onwardly by means of the adjacent car to its rear, which is still attached to the cable 11.. The brick are next unloaded from the car, andv by any of the well-known means the car is once more returned to the entrance end of the kiln, where it is loaded with brick and once more passes through thekiln. In order to facilitate passage of the cars through the kiln. and to lessen the eifect, of the sand seals in the resistance which they offer to the downwardly rojectinoflanges of the cars, I prefer to have a slight pitch in the kiln, which ordinarily amounts to from nine inches-to a foot per hundred feet ofkiln length.

In this's ecifioation I have given a somewhat broa is evident that many changes could be made in the detailed construction without departing from the spirit of my, invention.

Although I- have described my kiln particularly with reference to its use in connection with burning brick, it is evident that the same form of kiln could be used for burningany kind of ceramic material, or can be used for the treatment of metals, as, for example, in annealing or other similar processes.

What I claim as new and desire to cover by United States Letters Patent is:

1. In a continuous kiln, the combination of a kiln chamber in the form of a rectilinear passageway open at the ends and provided with a main exhaust passage opening from the top of the kiln chamber into the outside atmosphere at a point toward one end of the. kiln chamber, a furnace receiving its air supply from the outside atmosphere and discharging into the kiln chamber approximately midway between the ends thereof, and two. dampers one immediately adjacent to each side of the opening from the kiln chamber into the exhaust passage, each damper extending across and ardescription of my kiln, and it v ranged to be adjusted in a vertical plane within the kiln chamber to restrict the kiln passageway but to permit a constant draft therethrough.

1 ing fastened at one .point in its length to the tunnel wall, the said strips on either side of the tunnel forming with the tunnel wall a trough into which the aprons depending from the car tops extend, the saidtroughs being adapted to contain sand to constitute a sand seal between the car top and the tunnel walls.

3. In a continuous kiln, in combination, a kilnchamber in the'form of a tunnel, a shoulder on each side of said tunnel, a car forpassing through said tunnel, said car being constructed and mounted so that a part thereof will pass under said shoulder, and sand disposed upon the-parts of said car passing under said shoulders.

4. In a continuous brick kiln, the combination of a rectilinear tunnel of substan tially uniform cross-section from end to end, a plurality of closely adjacent but in-' dependent furnaces openinginto the upper part of said tunnel at or near the center of the length thereof, an exhaust flue opening from the top of the tunnel at or near one end thereof, a vertically adjustable damper at either side of the opening from the tunnel into the said exhaustflue, the said dampers being immediately adjacent to either side of the said exhaust flue opening, a plurality of cars with tops of fire-resisting material, means for moving the said cars continuously in close juxtaposition to one anotherthrough the said tunnel from end to end thereof, the direction of movement being from the exhaust flue end of the tunnel towardthe said furnaces, and means for sealing the joint between the car tops and theside walls of the tunnel.

5. In a continuous brick kiln, the combination of a rectilinear tunnel of fire-resist- 1ng material having vertical side walls and an arched roof, a plurality of furnaces arranged on either side of the tunnel at or near the middle of the length thereof, and each opening into the said tunnel, an exhaust flue opening from the said tunnel at or near one end thereof, a plurality of abutting cars,-. the wldth of the car tops being substantially eqilal to the width between the walls of the tunnel and adapted to form the floor of the tunnel, and the width of the tunnel between the walls being more than twice as great as the height of the'arch above the car tops, and means for moving said cars through the tunnel from end to end thereof in a direction toward the furnaces from the exhaust flue end of the tunnel.

. 6. In a continuous kiln, a substantially rectilinear tunnel-like kiln chamber, a plurality of cars adapted to travel through the tunnel, metal aprons depending from either side of the car tops, and a. plurality of de? tached sheet-metal angle-plates mounted at either side of the tunnel, successive angleplates overlapping one another, each angle- .plate being fastened at one point in its length to the adjacent tunnel wall, the said angle-plates on either side of the tunnel forming a trou h into which the aprons depending from t e car tops extend, the said troughs thus formed being adapted to contain sand to constitute a sand seal between the car tops and the tunnel walls.

7. In a continuous kiln, a substantially rectilinear tunnel-like kiln chamber, a plurality of cars adapted to travel through the tunnel, metal aprons depending from either side of the car tops, troughs mounted upon the side walls of the tunnel and into which troughs the said metal aprons depend, and a mixture of sand and talc contained in the said troughs to constitute with the said metal aprons a seal between the car tops and the tunnel walls.

8. In a continuous kiln, a rectilinear tunnel-like kiln chamber havin side walls and of each car top registering with the corrugations of the adjoining car-tops, the said corrugationsproviding openings through which gases' may be passed under the wares mounted'upon the car tops.

In witness whereof, I hereunto subscribe my name this 14th day of February, 1910.

FRANCES D. SHAW.

Witnesses:

ARTHUR H. Bon'r'rormn, LEONARD W. NOVANDER.

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