US1594589A - Continuous furnace - Google Patents

Description

Aug. 3 1926.

T. F. BAILY CONTINUOUS FURNACE Filed Jan. 2, 1925 MWM %w; H H H mo .3

abtouwua rial to be treated ative the chambers at ends of the hood or tunnel over the material Patented at. 3, 1926.

:rrmnnnus r. BAILY, or ALLIANCE, onro.

PATENT. OFFICE com'muous' ro'anaca.

- Application filed January 2, 1925. 'Serial No. 153.

This invention relates to continuous furnaces, and more particularly to a recupertype of furnace especially designed for annealing sheets and the like although equally adaptable for many forms of heat treating ,or heating at intense temperatures and is susceptible of use not only for heating or heat treating metals but for burning brick or the like.

The objects of the invention are to provide means for continuously passing the material to be treated through a preheating chamber, a heated chamber and a cooling chamber communicating with each other in the order named, and passinggas over the material in the opposite direction to the travel of the material.

The aboveand other objects may be attained by providing an elongated hood or tunnel divlded into three communicating chambers or compartments, the central chamber being provided with heating means, means being provided for passing the matecontinuously through the circulating a gas through the inlet and discharge chambers and for in a direction opposite to the travel thereof,

whereby the material is pre-heated in the first chamber, brought to the desired temperature in the intermediate chamber and cooled in the third chamber, the pro-heating being accomplished by the gas circulating over the cooling material and absorbing heat therefrom and delivering-the heat to the incoming material in the pre-heating chamber, while the cooling in the outgoing chamber is. accomplished by returning the gas, which has been cooled in the pre-heatmg chamber, to the cooling or outgoing chamber, auxiliary means being provided for further cooling the gas if desired before returning the same from the pre-heating to the cooling chamber.

Thus the material is pre-heated in the incoming ,or pre-heating chamber bywaste heat absorbed from the outgoing material in the cooling chamber and also radiated from the walls of the heated chamber, the

addi ional heat necessary, for bringing the 0 material to the desired temperature being supplied in the central or heated chamber by heating means", preferably electric resistors, and the cooling of the material being accomplished by returning the gases from the pre-heating chamber to the outgoing or cooling chamber.

Means may also be provided for impinging the cooled gas upon the outgoing sheets Immediately after they emerge from the heated chamber in orderto rapidly cool the material, as may be desired in some cases. In order to insure a reducing or non-oxidizing atmosphere Within the furnace, and to compensate for leakage, a reducing gas or oil suitable for creating a reducing gas may be injectedinto the heated chamber.

Especially. in the process of annealing it may be desirable to rapidly heat the sheets up to nearly the desired temperature as they enter the heated chamber and to then slowly bring the sheets to the desired temperature as they continue to pass through the heated chamber, and for this purpose the heated chamber may be divided into compartments maintained at different temperatures. n embodiment ofjhe invention is illustrated in the accompanying drawing, in which,

Figure 1 is a longitudinal sectional view s through the improved furnace, and,

Fig. 2, a transverse section on the line 22, Fig. 1. e

Similar numerals of reference indicate corresponding parts throughout the draw The improved furnace comprises an elongated hood or tunnel indicated generally at 1, and provided in its central portion with a heated chamber or compartment 2, heated as by the electric resistor troughs 3. This heated chamber communicates on one side with the pre-heating chamber 4 i and upon the other side with the cooling chamber 5, the roofs of which are preferably inclined from the central heated chamber toward the ends of the hood or tunnel. The material to be heated or-heat treated in the furnace is adapted to be continuously passed through the furnace, entering at the pre-heating chamber and passing through the same into'the heated chamber, and then through the cooling chamber. For the purpose of illustration, the drawing shows a furnace especially adapted for annealing sheets, and for this purpose endless conveyor chains 6.may be provided for continuously moving the sheets through the furnace, although any other well known conveying means is within the scope of the, invention.

These conveyor chains are illustrated as passing through longitudinal grooves 7 in the hearth 8 of the furnace, and provided with spaced fingers 9 arranged to support the sheets 10 above the hearth. The chains pass downward over sprockets 11 located near each end of the furnace,'one or both of which may be continuously driven in any suitable manner, the lower strands of the chains returning beneath the hearth, guide channels 12 being preferably provided for supporting the same.

or the purpose of pre-heating the sheets in'the chamber 4, a circulation of gas is maintained in the direction opposite to the travel of the sheets through the furnace. the gas passing through a cooling chamber, and being impinged upon the outgoing sheets as by the bafiie walls 13, and absorbing heat given off by the sheets; the gasthen being carried around the wall of the central heated chamber-2, and then, through the pre-heating chamber, in the direction of the arrows shown in Fig. 1, the baflie walls 14 in the pre-heating chamber serving to impinge the heated gas upon the sheets to pre-heat the same.

It will be seen that the baflle walls in the pre-heating and cooling chambers divide the chambers into a number of compartments of some considerable height; the gas being retained for a period in each chamber, thus increasing the efficiency of the apparatus in giving off its heat in the pre-heating chamber and absorbing heat in the cooling chamber As it is desirable to maintain a closed circuit ofthe gas to preserve a reducing or non-oxidizing atmosphere within the furnace, a duct 15 preferably connects the entrance end of the pre-heating chamber with the exit end of the cooling chamber, a fan heing provided in the duct as indicated at 16, to create a circulation of the gas in the manner above described, returning the cooled gas from the pre-heating chamber to the cool ing chamber to assist in quickly cooling the sheets before they pass out of the furnace atmosphere.

In annealing sheets, it may bedesirable in some cases to rapidly cool the sheets. as soon as they emerge from the heated chamber, and in order to accomplish the same a communimain portion cation may be provided between the duct and the cooling chamber, at this point, as indicated at' 17, a valve 18 being provided for controlling the same,-whereby all or a part of the cooled gas may be returned to either end portion of the cooling chamber as desired. i

, Doors 19, arranged to remain normally closed, are providedat the entrance and exit ends of the furnace to minimize leaking of the reducing gasfrom the furnace. In the event it is desirable to further cool the gas from the ,pre-heating chamber before it is returned to the cooling chamber, auxiliary cooling means such as the cooling coils 20, may be provided in-the duct 15, preferably adjacent to the fan as shown in Fig.. 1 of the drawing. V

In order -to insure a reducing or nonoxidizing atmosphere within the furnace,

and to compensate for leakage, a reducirg chamber, and to then slowly bring the sheets to the desired temperature as they continue to pass through the heated chamber. For this purpose the heated chamber may be di-.

vided into compartments as by the partition wall 22, the compartments being maintained at diiferent temperatures. As illustrated, the small compartment 23 at the entrance end of the heated chamber may be main tained at a considerably higher temperature than the main body of the heated chamber, whereby the sheets are quickly brought up to nearly the desired temperature as they pass through the compartment 23, after which they are more slowly brought to the desired temperature as they pass through the of the heated chamber 2.

From the above it will be seen that the material to be treated is continuously: passed in succession through a pre-heating chamber, a heated chamber and a cooling cham- Although the invent on is illustrated and described as designed for continuousl an nealing sheets, it should be understoo that the furnace and method described. are equally adaptable for many forms of heat treating or heating metals and other materials such as brick and the like.

, Iclaim:

1. An annealing furnace comprising an elongated chamber, rial continuously means for subjecting mum temperature at in .the chamber,

means for passing matethrough thechamber, the material to a maxian intermediate point means for passing a nonoxidizing'or reducing gas through the chamber in the opposite direction to the travel of the material and means for returning the gas in a closed circuit to the opposite end of the chamber. 2. An annealing furnace comprising an elongated chamber,

rial continuously means for passing matethrough the chamber,

means for subjecting the material to a maxiin the chamber,

.mum temperature at an intermediate point means for passing a non oxidizing or reducing gas through the chamber in the gas in a closed opposite direction 'to the impinging and means for circuit to the opposite end of the chamber.

furnace including a pre-heating chamber, a heated chamber and a cooling chamber, means for continuously moving nnaterial through said chambers, and means for passing a non-oxidizing or reducing gas through "i'the cooling chamber, around the heated chamber and through the pre heating chamber in the opposite direction to the travel of the material.

4. A furnace including a pre-heating chamber, a heated.- chamber and a cooling chamber, means for continuously moving material through said chambers, and means for passing through the coo a non-ioxidizing or reducing gas ling chamber, around the heated chamber and through the pre-heating chamber in the opposite direction to the travel of. the material and returning the gas in a closed circui 5. The method t to the cooling chamber. of

annealing sheets or the like which consists in moving the sheets continuously through a pre-heating chamber,

then through a heated chamber in which the sheets are first subjected to the maximunr temperature, and then to ture substantially and then through 6; A furnace a lower temperathat desired in the sheet, a cooling chamber.

of the character described including an elongated tunnel containing a preheating cham her, a heated chamber and a cooling chamber communicating with each ously passing other in the order named, means for continumaterial through. the tunnel, means for passing reducmgor non-oxidlzlng gas through the tunnelin the opposite direc tion to'the travel for maintaining and I chamber to the 'ZJAn annealing elongated tunnel returning the same from the of the material, and means the gas in a closed circuit preheating cooling chainber.

having heating 'ifieans at a furnace including an" point intermediate its ends, means for contlnuously moving material through the tunnel in one direction and means for continuously circulating a non-oxidizing or reducing gas in'a closed circuit through certain portions of the tunnel in the opposite direction to the travel of the material.

8. An annealing furnace including an elongated tunnel point intermediate its ends, means for. continuously moving material through the tunnel in one direction and means for continuously circulating a non-oxidizing or reducing gas in a closed circuit portions of the tunnel in the opposite direction to the travel of the material and for returning the gas to the opposite end of the tunnel in a closed circuit.

having heating means at a through certain 9. The method of annealing sheets or the like which consists in moving the sheets continuously through a pre-heating chamber, then through a heated chamber in which the sheets are first subjected to the maximum temperature, and then to a lower temperature substantiallv that desired in the sheet, and

then through a cooling chamber the presn the desired temperature, then slowly bringing the sheets to the desired temperature and then ,quickly cooling the sheets in a reducing atmosphere.

12. The method of annealing sheets or the like'which consists in moving the sheets continuously through a heated chamber in which the sheets are brought to the desired temperature, then.

quickly cooling. thesheets below a critical temperature, in the presence of a reducing gas, then slowly-cooling the sheets below an oxidizing temperature.

13. The method of annealing sheets or the like which consists in moving the sheets con tinuously through a pre-heating chamber,- then through an electrically heated chamber .in which the sheets are first subjected to the maximum temperature and then to a lower temperature substantially that desired in the sheet, and then through a cooling chamber. a

the like which consists in moving the sheets continuously through a pro-heating chamher, then through an electrically heated chamber in which thesheets are first sub-; jected to. the maximum temperature and then to a lower temperature substantially that de, sired in the sheet, and then'through a cooling 14. The method of annealing sheets oi tinuously passing material through the tun chamber, in the presence of areducing gas.

15. A furnace of the character described including an elongated tunnel containing a pre-heating chamber, aheated chamber, and

a cooling chamber, communicating with each other in the order named, means for connel, and means for passing gas through the tunnel in the opposite direction to the travel of the material and for returning the gas to the opposite end of the tunnel in a closed circuit.

16. A furnace of the character described including an elongated tunnel containing a pre-heating chamber, a heated chamber, and a cooling chamber, communicating witheach other in the order named, means for continuously passing material through the tunnel, means for passing gas through the tunnel in the opposite direction to the travel of the material, and means for maintaining the gas in a closed circuit and returning the same from the pre-heating chamber to the cooling chamber.

17. A furnacesof the character described including an elongated tunnel containing a pre-heating chamber, a heated chamber, and a cooling chamber, communicating with each other inthe order named, means for con- 'tinuously passing material through the tuneach, other in the order named, means for continuously passing material through the tunnel, means for passing gas through the tunnel in the opposite direction to the travel of the material, and depending bafiie walls in the pre-heating and cooling chambers for impinging the gas upon the material, certain of said baflle walls having openings to permit a portion of the gasgto pass therethrough.

19. A furnace including a central chamber, an electric resistance element therein, a preheating chamber communicating with v one end ofthe central chamber, a cooling chamber communicating with the other end of the central chamber, means for passing material continuously through the preheating, central and cooling chambers and means for transferring a cooling medium from the preheating chamber to the cooling chamber.

- 20. A furnace including a central chamber, an electric resistance element therein,

a reheating chamber communicating with one end of the central chamber, a cooling chamber communicating with the other end of the central chamber, means for passing material continuously through the preheating, central and cooling chambers, means for abstracting heat from the material in the cooling chamber and, transferring it to the preheating chamber and means for transferring a cooling medium from the preheat- 7 ing chamber to the cooling chamber.

21. A furnace including a central chamber, an electric resistance element therein, a preheating chamber communicating with one end of the central chamber, a coohng chamber communicating with the other end of the central chamber, means for passing material continuously through the preheating, central and cooling chambers, means for abstracting heat from the material in the cooling chamber and transferring it to the preheating chamber, and means for maintaining a reducing or non-oxidizing atmosphere in all three of the chambers/ 22. A furnace including a central cham- I ber. an electric resistance element therein, a preheating chamber communicating with one end of the central chamber, a coohng chamber communicating with the other end of the central chamber, means for passing material continuously through the preheating, central and cooling chambers, means for transferring a cooling medium from the preheating chamber to the cooling chamber, and means for maintaining a reducing or non-oxidizing atmosphere in all three of the chambers.

'23. A furnace including a central chamher, an electric resistance element therein; a preheating chamber communicating with one end of the central chamber, a cooling chamber communicating with the other end of the central chamber, means for passing material continuously through the preheating, central and cooling chambers, means for. abstracting heat from the material in the cooling chamber and transferring it to.

the preheating chamber, means for transferring a cooling medium from the preheating chamber to the cooling chamber, and means for maintaininga reducing or nonoxidizing atmosphere in all three of the chambers.

24. furnace including a central chamber, an electric resistance. element therein, a preheating chamber communicating with one end of the central chamber, a cooling chamber communicating with the other end of the central chamber. means for passing material continuously through the preheating, central and cooling chambers, and means for circulating a reducing or non-. oxidizing gas through the cooling chamber. .then thro h the preheating chamber and returning t e gas to the cooling chamber in a closed circuit.

25. An annealing furnace including a preculating a non-oxidizing or reducing gas in heating chamber, a heated chamber and a a closed circuit through certain of the chamcooling chamber communicating with each bers in opposite direction to the travel of 10 other in the order named, means for conthe material.

'tinuously moving material through the pre- In testimony that I claim the above, I

heating, heated and cooling chambers in one have hereunto subscribed my name. direction and means for continuously cir- THADDEUS F. BAILY.

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