US1311978A - Process for burning brick - Google Patents

Description

F. B. LAMBERT.

PROCESS FOR BURNING BRICK. APPLICATION man MAR. s. 1912.

a sHEETs-HEET I.

AVAVAZ! a;

Patented Aug. 5, 1919.

F. B. LAMBERT.

PROCESS FOR BURNING BRICK.

APPLICATION FILED MAR. 5. 1912.

3 SHEETSSHEET 2.

Patented Aug.

.Zhue/rfan' F. B. LAMBERT.

PROCESS FOR BURNING BRICK.

APPLICATION FILED MAR. 5. l9l2. v

m ,J JMM WM e P w .v Fm W W fi m 1% 9 1 L Z2 UNITED STATES PATENT OFFICE.

FRANK B. LAMBERT, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

PROCESS FOR BURNING BRICK.

Specification of Letters Patent.

Patented Aug. 5, 1919.

Application filed March 5, 1912. Serial No 681,720.

- ful Improvements in Processes for Burning Brick, of which the following is a specification.

The principal object of my invention is to provide a new and improved method for burning bricks in kilns. Another object of my invention is to provide a method ofv burning bricks with an economical use of fuel. A further object of my invention is to provide a method of burning bricks that shall cause the heat to be advantageously distributed in the kiln.

The fundamental and important conception of my invention is the double use of the heat. Heretofore when it was desired to burn a kiln of brick, it was considered necessary to supply enough heat to bring the whole kiln to the vitrifying temperature at one time. According to my invention only enough heat is supplied from the burning fuel to heat one part, for instance the bottom, of the kiln, and this heat is employed in a dual capacity. After it has brought the bottom of the kiln to the right temperature it is driven from the bottom to the top to raise the temperature of the rest of the stackto the proper point successively- According to my method of procedure I heat the lower part of the kiln by forcing oi] flames thereinto and-after suflicient heat has been stored in the bottom of the kiln and after the lower courses have come to the right temperature, firing of further fuel is discontinued; To this end I turn off the oil burners completely and supply and burn no more fuel, but use only the heat which has been put into the kiln thus far to finish the entire kiln.

The matter of shutting off the supplying and burning of fuel is, however, incidental only to the main feature of my invention, which is a double use of the heat. It may be observed that certain conditions are re quired in order to make it possible to carry out my invention. These will appear more fully from the detailed description follow,-

v ing. It may also beobserved that complete and absolute shutting off of the burning of the fuel is not a strict requirement of my invention as the addition of a small amount of heat after the main body of heat is supplied and is being driven into the top of the kiln is a matter of no consequence. .Such slight addition of heat might be useful in tempering the incoming air and the like,'but would be of no consequence considering the process as a whole.

For the purpose of illustrating and exlaining the nature of my invention, I shall in the following specification describe in some detail one particular seriesof operations and the apparatus used in connection therewith, all of which exemplify the invention. This will make the foregoing stated objects more apparent and other objects will also .become apparent from the following specification and claims, taken with the accompanying drawings.

Referring to the drawings Figure 1 is a general perspective view partlybroken away showing a kiln in readi ness to be burned.

Fig. 2 is a transverse section of the same.

Fig. 3 is a plan view of one of the burner nozzles.

Fig. 4 is a longitudinal section of the same.

Fig. 5 is a fragmentary vertical "section through one of the arches of the kiln.

Fig. 6 is a vertical section taken at a right angle to Fig. 5.

Fig. 7 is an elevation of a blower tube.

Fig. 8 is a perspective view of the end thereof.

Fig. 9 is a top plan view of a portion of the blower tube.

Fig. 10 is a vertical section of the same.

The kiln shown in the drawings is a socalled temporary clamp kiln. It is constructed under a shed roof 15 supported at its eaves by posts 16 and 17 braced together so as to resist lateral thrusts as well as to sustain the weight of the roof. The boards of the roof 15 are removable so as to facilitate the escape of the gases and vapors from the kiln as desired. Tie rods 18 are provided for the roof 15, and the posts 17 support rails 19, which constitute a crane track. The shed has extension roofs 20 at the sides and under thesethe side walls comprise removable panels 21 of wooden boards. A permanent steam pipe 22 with steam at about one hundred pounds pressure is car. ried above the ground along one side of the' cool, and then the burned bricks constituting.

' the kilns are taken down and hauled away.

Under one long shed 15 there may be several of these temporary clamp kilns at different stages of construction and burning.

One kiln may be under theprocess of burning while another is being built up and still another is being torn down and hauled away. In biiilding one of these kilns a la er of previously burned bricks 24' is laid at on the ground. Then the dried bricks are piled above. These dried bricks are handled by cranes which run on the tracks 19. The bricks come from the driers on cars piled eight brick widths deep, and the cranes pick up a cart-load at a time and place it in the proper position for building up the kiln- The first installments of bricks 25 are spaced apart so as to leave transverse channels or spaces between them. Then men working with their hands draw the.toplay ers of bricks over to form jets 27 and thus form the arches 26.v After the arches are formed the spaces behind the jets are filled in with extra brick placed by hand and then additional dried; unburned bricks 25" are piled on top by the crane. The bricks 25 and 25, are all built up in. the kiln so that they stand on edge crisscross with narrow spaces between them. On the sides of the kiln above the arches and on the ends of the kiln from the ground up there is placed a wall 28 of double coal bricks, the thickness of this wall being equal to the length of a single brick. These double coal bricks are made by mix'ing'anthracite coal screenings with the clay in the proportion roughly of eighty pounds to a thousand brick. Untside of the double coal brick 28 a wall of previously burned brick 29 is built up all around the sides and ends of the kiln. The thickness of this wall 29 is a brick length for the lower half. but only abrick width for the upper half. The outside face of this side and end wall 29 is then plastered over or .scoved with a daubing made of sand and black loam so as to close the cracks between the bricks! Then a layer of previbusly. burned brick 30, the platting, is laid flat wise. allover the top of the kiln as closely as the brick can conveniently be laid, but

gases and vapors between them.

the top brick 30 are not scored, and the from the kiln can escape a In completed form each kiln has the folv lowing dimensions: There are thirty arches .in the kiln with about forty-two thousand brick per arch. The width of the kiln at the bottom is fifty-four brick lengths and at the top is fifty-one brick lengths. The height of the kiln is forty-eight brick widths exelusive of the bottom brick 24: and the top platting 30. The crane places the brick in loads each eight brick widthsdeep and then loads are. placed sixdeep in the height of the kiln. Each pillar or leg between the arches has a horizontal thickness of four the arches 26, but so asflto leave openings to the lower parts of these arches. Then little extensions'31 called dog houses are built out from the open ends of the arches 26. Above each dog house there is left a peep hole 61 normally'iclosed by a brick bat;

The side walls'of the completed kiln are i bracedby struts 32 and bricks 33 against the side posts 17, and'the end walls of the kiln are braced by struts '35 between the" ground and the vertical bars. 34. that lie against the end walls ofthe'kiln.

-On top of the kiln at regular intervals,

brick-bats or piles of brickbats 36 are placed and rods 37 are-hung from the tie rods 18;

the lower end of the hangerfrods' 37 barely touching the brick. bats This is so that later on the settle? can be observed. a 4

1 05 A temporary steam pipe 38,- branchin'gf;

from the overhead steam main -22jis laidall f along the sides ofthe kiln just above: and

beside the dog houses 31.,- This steampipe's 38 is paralleled by a-temporary'oil supply pipe 39 connected to the buried; oil main 23.--

Beside eachdog house each pipeSSand-BSL- I has respective valves 40. and iii controllingi branch outlets. An oil injector nozzle 445s connected by i the pipes 41and 43 and elbow 42 forming an L. to. the steam outlet 40, and it is also connected by a flexible tubing 47' and the end pipes'ti and 48 tothe oil outlet 45. Thus it will be seen that the injector nozzle 44: can be swung up and down about the pipe 41 as an axis and with the pipe 43 as a radial arm. The injector nozzle 44 has a central conical oil outlet 49 controlled by the-needle valve 50, which is adjusted by the hand wheel 51. The steam outlet 52 is annular surrounding theioil outlet 49. The form of this burner, nozzle may be varied.

For the Purpose of blowiniin steam and? 130.

air at a certain pressure in t is practice of fires burn rather close to the do my improved method, as I shall describe presently, I provide the pipes 53. Each pipe 53 consists of four sections successively decreasing in diameter. Each section has an opening 55, just before the joint 54 with the next smaller section, and around each arch 26 at each end thereof, the oil being injected by the annular steam jet issuing from the nozzle 52. At first only a moderate supply of oil and steam is injected and the houses. As the bricks adjacent to the en 5 of the arches get dried out and hot the fire is forced, using more steam and oil, and at the end of about six hours the flames are driven way back intothe arches so that the two flames coming in at the ends of each 'arch meet or nearly meet at the middle of the arch and thus the whole arch is filled from end to end with the oil flames. The kiln is burned in this way for about six hours more, the fire being forced to the utmost during this time. By this time all the bricks ad acent to the arches are beginning to be red hot;

thereafter the operator begins to shut off the steam and Oll supplies, tapering down for the next eight to twelve hours.

The burners are careful to force the fires at the ends of the intermediate arches and throughout the arches at the ends of the kiln. Also they burn with considerable air at first so that there is uncombined oxygen in. the gases going up through the kiln. This oxygen enters the pores of the double coal brick 28 and burns the coal therein, thus affording a local supply of heat around the walls of the kiln. The more intense burning at the ends of the intermediate arches and throughout the end arches and the combustion of the anthracite coal in the outside wall of double coal brick, all insure proper burning of the dried brick adjacent to the side and end walls of the kiln. The ideal state which the burners try to attain, say afterthey have been burning from ten to twenty hours, is to have an isothermal surface or zone extending horizontally across the body of the kiln just above the arches, but rising a little all around its This has been indicated dia ramedges.

otted matically on Fig. 1 by means of the line 59'.

At the end of from twenty to twenty-four the ent of the hanger rods 37. This settle may be only a fraction of an inch, but it probably indicates that the bricks above the arches have become so softened by the heat that they are crushin together slightly by reason of the load of file bricks above them. Wherever the operators notice. this settle, they promptly shut off the flames in the arch or arches directly beneath the settling point or points and swing the corresponding nozzles 44 up above the dog houses 31. Then they shove the tubes 53 into the arches at which the flames have been shut off, puttin the small end 57 of each tube or pipe 53 in first and in such position that all the flaring nozzles 56 and 57 are directed upwardly, also so that the bracket or frame 58 lies directly below the nozzle 44. Then the nozzle 44 1S swung down so that it rests on the frame 58 and the steam valve 40 is opened. The steam blast going from the nozzle 44 axially into the pipe 53 has an ejector action and draws inwith it a large amount of air through the large open end of the pipe 53 around the nozzle 44. This mixed air and steam issue from the pipe 53 through the flaring- nozzles 56 and 57 and then ascend up through the bri'k-work 25 and 25'.

This blowing of steam and air is continued for about twenty-four hours after the fires are shut off. Very soon after the blowing of steam and air commences the mcandescence disappears. when looking into the arches through the .peep holes. force with which the steam is blown is regulated by the operators in accordance with the settle. The more tendency the kiln shows in any place to settle the harder the The steam and air are blown in all the arches under that place.

At the end of about twenty-four hours'of blowin that is, about forty-eight hours after t e fires were started, the blowing is stopped and the dog houses are knocked down so as to give a good opportunity for air to go into the arches by natural draft. After about twenty-four hours more. that is, about seventy-two hours after burning is started, the zone of incandescence in the kiln gets up to the top so that the red hot brick can be seen through the cracks between the brick 30 on top of the kiln. This marks the completion of the burning and it only remains for the kiln to cool down by its natural draft so that it can be taken down and the bricks hauled away. I employ the term vitrification to designate the burning of bricks, or similar clay product, to such 'a condition that they are finished products.

in a certain type of clay product, but to conception is the double use of heat in this cover the broad idea of burning to the finish required for the particular product.

While the bricks piled in the kiln are largely freed from their moisture by the preliminary drying, it is true that they have a considerable quantity of moisture in them which is driven oif by the burning especially in the earlier stages. Soon after the fire is started a dense cloud of water smoke comes off from the top of the kiln escaping through the openings in the top layer of brick 30. At the time the fire is shut off this water smoke is still issuing from the kiln in some instances and continues to do so for a considerable time thereafter. But about the time the blowing is stopped, that is, at the end of the second twenty-four hours, the quantity of water smoke becomes less and when the zone of incandescence reaches the top of the kiln is has ceased entirely.

lVhile I have practised the method defined in the appended claims in various ways, and

with various clays, and at various places, I.

have given a specific description of only one particular series of operations v according thereto. This description is for kilns built and burnt by me at yard No. 22 of the Illi nois Brick Company just west of Blue Island I The clay of'which these bricks are made is so-called hardpan, a stratum about twenty or twenty-five feet thick overlaid by blue clay and underlaid by boulders and gravel. The overlying blue clay at this yard has all been taken oil and burned, in past years. In

- burning the hard-pan I have found that my method is advantageous for the reason that the bricks made from the hard-pan had a tendency to clinker if burned by previously .known methods, but they do not clinker when burned in accordance with my system. But my method of burning has other advantages, among which is the shortness of time required for the complete operation of burning, and the saving of fuel. I have burned many thousand brick by my method with a consumption of only eight gallons of oil per thousand of brick, whereas I know that it is not uncommon by other methods to consume as much as. twenty to twenty-five gal-' lons of oil er thousand of brick.

In th f0 lowing claims I employ the term elastic fluid to comprehend gases or vapors, or mixtures thereof.

In many instances it may be desirable to vary the rate and quality of burning and the times stated above for the various steps in my process merely illustrate one method of carrying out the latter, and I do not wish to be restricted to the exact method and application of the same beyond the scope oil-the appended claims.

As I have-above indicated, the important particular connection. The specific method of procedure which I prefer to follow-requires absolute discontinuing of the supply and burning of fuel This is because the oil burners are used as injectors, and in order to get the injector pipe into place it is necessary to shut oil the oil burners. Such complete shutting off of the fuel is in all cases desirable from the standpoint of saving fuel and of practising the process. Burning of further fuel thereafter'would, so far as carrying out the process is concerned, be merely a waste of heat, but I wish it clearly understood that all of the advantages of my invention may be gained without complete and absolute discontinuance of the fire so long as the double useof the heat is gained. A small fire might be permitted to burn after the period of blowing the body ofheat has begun, but such small fire would be merely an evasion of the term .discontinuing." I

intend, therefore, to cover broadly the double use of the heat even where absolute and complete cessation of burning is avoided by.

adding a small amount of heat.

I claim: a a

1. A process for burning clay products consisting in first arranging the same in a kiln, next applying heat to said kiln and the products for a time sufiicient to create a heating zone of the-required temperature, then discontinuing the application of such heat and next applying gaseous fluid to said kiln and permitting said heating zone to traverse a portion thereof. 1

2. A process for burning clay products consisting in first arranging the same-in a kiln, next applying heat to sa'idkilnand "products for a time suflicient to create a" heating zone of the required temperature, then discontinuing the application of such heat, next applying gaseous fluid to said kiln and permitting sald heating zone to traverse" a portion of saidkiln, and then discontinuing such supply of gaseous fluid and permitting said zone' to travel the balance of said kiln.

A process for burning clay products consisting of first arranging the same in a kiln with a heating chamber therein, next in supplying and burning fuelin said chamber under pressure until a heating zone of the required temperature is established through- Ollhstlld clay products adjacent said chamber, then discontinuing such fuel supply,

'- and next supplying heated air under pressure in said chamber until said zone has traveled through a portion of said kiln.

5. A process for burning clay products, consisting in first arranging the same in a kiln with a heating chamber therein, next in supplying and burning fuel in said chamber under pressure until a heating zone of the required temperature is established throughout said clay products adjacent said chamber, then discontinuing such fuel supply and burning, and next supplying air and steamunder pressure in said chamber until said zone has traveled through a portion of said iln.

6. A process for burning bricks which consists in piling them into a kiln, then firing a part of them for a time with carbonaceous fuel, then shutting off said fuel and thereafter blowing elastic fluid into said kiln to burn the remainder of the bricks.

7. A process for burning bricks which.

consists in piling them into a kiln, then firing only a part of them for a time with carbonaceous fuehand then shutting off said fuel and thereafter blowing elastic fluid into said kiln, said elastic fluid being introduced adjacent the points of previous firing.

8. A process of burning bricks which consists of piling them into a kiln, then firing them for a time with carbonaceous fuel until they reach the vitrifying temperature in a portion'of said kiln only, and then blowing an excess-of elastic fluid into said kiln and discontinuing firing with said fuel before all the bricks have reached the vitrifying temperature.

9. The process of burning bricks which consists of piling them into a kiln, then firing them for a time with carbonaceous fuel until they reach the desired vitrifying temperature in'the part of the kiln adjacent to the fire, then discontinuing firing with fuel and then blowing elastic fluid into said kiln while the zone of vitrifying temperature travels to other parts of said kiln.

10. The process of burning bricks which consists in forming them into a kiln with arches adjacent the bottom thereof and extending therethrough, then burning fuel in said arches adjacent each end thereof until a zone of vitrifying temperature is established only in the stratum adjacent the said arches,

troducin a burning fuel under pressure in v said arches until a zone of vitrifying temperature is established only in the stratum adjacent said kiln, then discontinuing such fuel burning, and supplying gaseous fluid under pressure to said arches.

12. The process for burning bricks which consists in setting the bricks in a kiln, then firing the kiln with fuel to bring a part only of the bricks t0 the temperature of vitrification, then blowing elastic fluid in excess of the amount required for firing into the kiln until all the bricks are burned and discontinuing firing before all of the bricks are brought to the temperature of vitrification.

13. The process for burning bricks which consists in setting the same in a kiln, then firing the kiln with fuel to heat a part only of said bricks to the temperature required for burning, then discontinuing the firing with fuel and blowing elastic fluid into said kiln until all the bricks have reached the temperature required for burning.

14. The process for burning bricks which consists in setting the same in a kiln, then firing the kiln with fuel to heat a part only of said bricks to the temperature of vitrification, then discontinuing the heating effect of firing with fuel and blowing air in excess of the amount required for burning into said kiln till all the bricks have reached kiln until all the bricks have reached the temperature of vitrification. v

16. The process of burning bricks which consists in setting the bricks in a kiln, then heating a stratum of said bricks to drive out the moisture and to bring said stratum to the'temperature of vitrification, then shutting off the fuel supply and forcing elastic fluid under pressure through said "stratum and into the adjacent stratum of unburned bricks, thereby causing the heat of said stratum to be carried to the unburned bricks.

17. The process of burning bricks'which consists in settin the green bricks into a kiln having an internal heating. chamber therein, then burning fuel under forced draft to drive oil the moisture from the green bricks and to bring to the temperature of vitrification, a stratum of said bricks adjacent said heating chamber, then cuttin off the fuel and continuing the forced dra t to drive the heat from said heated stratum to the adgacent strata of unburned bricks driving 0 the moisture and bringin to the temperature of vitrification the u h bricks in progression. I

18. The process of burning brickswhich consists in setting the bricks in a kiln with an internal furnace, then burning fuel under urned jacent the furnace, and directing the fire in' forced draft, said burning being conducted to drive off the moisture and to bring to the temperature of vitrification a stratum only of bricks adjacent said furnace, then discontinuing the fuel supply and continuing to force the pressure draft to cause the heat to travel to an adjacent stratum of unburned bricks and to bring the same to the desired temperature. j

19. The process of burning brick which consists in setting the bricks in a kiln having an internal furnace, then firing said furnace with fuel under a forced draft sufficient to cause the water smoke and other vapors to move from the stratum adsaid furnace to extend the heating in a'su'bstantially isothermal zone across the kiln to heat the bricks in said zone, to thetemperature of vitrification, then discontinuing the firing and continuing the forced draft to drive the water smoke forward from adjacent strata, and. causing said heated-zone to travel successively to said strata to bring to the temperature of vitrification the adjacent unburned brick in said kiln.

20. The-process of burning. bricks which consists in setting the bricks in a kiln having an internal furnace, then heating the furnace with fuel burned under a forced draft, said draft being great enough to force the water smoke from the lower stratumof bricks adjacent the furnace through the remaining bricks, said firing being continued until said entire stratum is brought to the temperature of vitrification, then discontinuing the firing and continuing the forced draft sufficient to drive the heat from said stratumginto successive adjacent strata con tinuously until said desired temperature shall havebeen attained by said adjacent strata.

21. The process of burning bricks which consists in setting said bricks in a kiln with a furnace therein, then firing said furnace under a forced draft until a highly-heated substantially isothermal Zone is attained adj acent said furnace, the bricks adjacent said zone being still at the temperature at which theygive off water smoke, then discontinuin firing and maintaining the forced draft y discharging jets of steam in said furnace to entrain large volumes of air, thereby causin said highly-heated zone to travel to the adjacent bricks.

22. The process of burning bricks which consists in piling them into akiln, then firing apart of them for a time with carbonaceous fuel to vitrify said part, then blowing elastic fluid in excess'into said kiln to vitrify the remaining bricks in the kiln, said firing being discontinued prior to the-vitrification of said remainder.

23. The process of burning bricks which consists in pilingthem into a kiln, then firing only a part of them for a time with carbonaceous fuel to vitrify said part, and then blowing air in excess into said fuel to vitrify the remainder of the bricks, said firing being discontinued prior to-the vitrification of said remainder.

24. The process of burning clay products which consistsin arrangingthe same in a kiln, burningfuel to heat a stratum of said products to substantially the temperature of vitrification, injecting air in excess into said kiln and discontinuing the burning of said heating fuel before all of said products ave attained the temperature of vitrification.

25. The process of burning clay products which consists in arranging the same in a kiln having a heating chamber therein, burning fuel in said heating chamber to heat a. stratum of said products to substantially the temperature of vitrification, injecting large quantities of elastic-fluid, into said kiln and discontinuing the burning of said heating fuel before all'of the strata of-saidproducts have attained thetemperature of vitrification; I

26. "The process of burning bricks or the :quired to burn said fuel, and discontinuing the heating effect of said firing prior to the I time when all of said bricks have reached the temperature of vitrification. I V

27. The process of burning bricks or the like which consists in piling said bricks into a kiln, then firing a part of said bricks to bring the same substantially to the temperature of vitrification, injecting air? under pressure into said kiln in excess of the amount required for the burning of said fuel and reducing the fire and discontinuing the heating effect of the same beforegall of said bricks have been brought to the desired temperature of vitrification.

28. The process of manufacturing and burning bricks, which consists in mixing carbonaceous material with the clay, their forming the clay into bricks, then piling the bricks into a kiln, then firing said bricks with an excess of air to bring a part only of said bricks .to the temperature of vitrification and to burn out the carbonaceous material, then discontinuing the heating effect of firing and blowing air through said heated bricks'to said unburned bricks in order to burn out the carbonaceous material and to vitrify the same. 1

v 29. The process of. manufacturing and burning bricks, which consists in mixing finely divided coal withclay then forming the: clay containing the coal into bricks, then iling said bricks into a kiln, then firing said rlcks with an excess of air to bring a part only of said bricks to the temperature of vitrification and to burn out the carbonaceous material, then discontinuing the heating effect of firing and blowing air in excess through said heated bricks to said unburned bricks in order to burn out the carbonaceous material and to vitrify all of the bricks.

30. The process of manufacturing bricks which consists in mixing carbonaceous material with part of the clay, then forming the clay into bricks, then iling the bricks into a kiln, then firing said bricks to bring the lower strata to the temperature of vitrification and to burn the carbonaceous material in said bricks, then discontinuing the heating effect of said firing and blowing excess of air through said heated bricks to said unburned bricks in order to burn out the carbonaceous material and to vitrify all of the bricks. I

31. The process of burning bricks which consists of setting the bricks into a kiln for burning, then heating one extreme of said kiln by blowing flames under forced draft into said kiln under as great a pressure as is required to force the major portion of the gases and products of combustion out of the opposite end of the kiln, said fire being directed to cause the formation of a zone of incandescence extending completely across said extremity of the kiln, thereafter shutting off the fuel and blowing gaseous fluid through said kiln in the same general direction as the line of movement of the products of combustion through the kiln, to move said zone of incandescence through the length of the kiln to the other extremity thereof.

32. In a process for burning brick, the following steps, setting the brick in a kiln in close relation. then applying a limited quantity of heat from an external source to the lower part of the kiln only, to bring said lower partto the temperature required for vitrification, and also to store a large body of heat in said lower part, then carrying said large body of heat as a body from the lower part to the upper part of the kiln and thereby bringing the upper part to the required ten'iperature of vitrification by means of the stored heat in said lower part only.

33. In a process for burning brick, which comprises setting the brick in close relation to each other in a stack, applying heat from an external source to the lower part of the stack only, to heat the bricks in said lower plying heat from an external source to the bottom of the kiln only to burn the lower portion of the kiln and Store a body of internal heat in said lower portion while the upper portion is still green and wet. then burning the other portion of the kiln by the application of the internal heat contained in the lower burned portion and finally driving lall of the body of heat out of the top of the (iln.

The process of burning bricks, which comprises stacking the bricks in a kiln, burning fuel adjacent the stack and applying the heat thereof to the bottom of the stack only, until a large enough portion of the lower part of the kiln has been brought to the temperature of vitrification, to store enough heat to burn the top of the kiln, then moving the heat from the lower heated portion up through the upper portion to complete the burning of said upper portion with said stored heat, and simultaneously cooling down the lower part of the stack.

In testimony whereof, I have subscribed my name.

FRANK B. LAMBERT.

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