US2222809A

US2222809A - Heating furnace

Info

Publication number: US2222809A
Application number: US294532A
Authority: US
Inventors: Curran John
Original assignee: Individual
Current assignee: Individual
Priority date: 1938-09-20
Filing date: 1939-09-12
Publication date: 1940-11-26
Anticipated expiration: 1957-11-26

Description

J.CURRAN Nov. 26, 1940.

HEATING FURNACE Filed Sept. 12, 1939 2.22am Ame eon @ardifl, Wales Application September 12, 1939, Serial No. 294,532

In Great Bri September 20, 1938 a (lie (oi. 283-8) This invention relates to heating furnaces and especially to annealing furnaces.

An object of the invention is to provide a device for usefully employing the heat contained in a charge which has'passed out of the furnace.

This object is effected according to the invention by providing means for circulating a stream of gas over the charge which has emerged from the furnace proper and passing this gas to the charge awaiting entry to the furnace over a path exterior to the furnace interior.

By a further feature of the invention damper means are provided to regulate the relative proportions of heated gas reaching the part of an entry chamber through which the charge passes before entering the furnace which is nearest the furnace door and the part which is nearest the outer door of the entry chamber. Thermally responsive devices of known kind may be provided to operate the damper means in accordance with the temperature of the circulating gas and to reduce the quantity of gas entering the part of the entry chamber nearest the furnace door, or stop such admission, when the temperature of the gas falls below a predetermined value. Preferably, this feature of the invention is employed in comunction with means for heating the part of the entry chamber adjacent the furnace door. The charge nearest the furnace door will attain a higher temperature than that nearest the outer door of the entry chamber and by passing all or a greater part of the circulating gas over the.

charge nearestthe outer door when the tempera ture of the circulating gas falls, the temperature of the charge actually entering the furnace can be maintained more nearly at a constant desired value, whilethe amount of heat imparted to the cold charge is as great as possible. In the case of an annealing furnace maintained at a constant temperature and where the operation of the conveyer to discharge and load the furnace occurs at fixed times-the maintenance of the entering charge at a fixed temperature is important.

The heating is preferably electrical and the furnace may be divided into as many zones or chambers as is desired.

The invention is illustrated by way of example in the accompanying drawing, in which- Fig. 1 is a section of the furnace, and

Fig. 2 is a diagram of the electrical circuit for controlling the dampers.

The charge which may be, for example, cartridge cases, is. adapted to be moved into and through the furnace l by a conveyer 2 driven by drums I9. The furnace is provided with doors 3, t at eachend of the furnace space proper and further doors 5, 6 which afiord access to an entry chamber 1 and an exit chamber 8 in which the charge rests before entering the furnace proper and after emerging therefrom respectively. The

doors are counterbalanced by weights 28 suspended by chains Zl passing over pulleys 22, and

are arranged to be opened and closed together to permit the charge to be carried into and through the furnace. A lagged duct 9 isflformed in the masonry of the furnace below the upper run of the conveyer 2, which communicates with the entry and exit chambers through openings it in the floors thereof. A further lagged duct Hi arranged above the furnace opens to the upper spaces of the entry and exit chambers, and afan H is arranged in this duct to cause air to pass from the upper part of the entry chamber to the upper part of the exit chamber, over a heated charge in this chamber and through theopenings in the floor to the openings in the floor of the entry chamber, returning over the cold charge to the fan. The flow of air is indicated by the arrows.

The entry chamber 7 is divided by a door 5A into an inner compartment l2 and an outer compartment i3. Access to the compartment l2 M by the hot air from the exit chamber 8 is controlled by pivoted dampers I5 and to which are operated thermostatically in such a manner that they open or close simultaneouslyto isolate or connect the compartment H from or with the compartment 8 in dependence on the temperature of the hot air and the compartment if. The compartment l2 of the entry chamber is provided with electrical heating elements l6 similar to the heating elements I! of the furnace proper.

The dampers l5 and It also serve to control the circulation of gas in the ducts 9 and It. A gas other than air may, of course, be .circulated when desired. I

Referring to Fig. 2, the dampers I5 and i8 (not motor indicated diagrammatically as a motor at 24. supplied from mains 2'! and 28 through contacts 25 and a thermostat C. The arrangement is such ,that the dampers I5 and I8 are closed when contacts 25 are in the off position. Suitable means mesh with pinions 15b and [8b respectively. The

pinions are fixed respectively to the hinged ends of the dampers l5 and I8. The thermostat C-is placed in the compartment l2 and completes a The current for the solenoid or motor is shown in Fig. 2) are actuated by a solenoid or circuit for opening the dampers I5 and I8, when w the temperature in compartment I2 is sumciently high, provided the contacts 26 are closed. Current forthe heaters i6 is supplied through contacts 25 which are operated by a circuit including thermostats A and B situated respectively in the chamber 8 and the compartment 12. The

contacts are held in by a circuit including contacts 32 and thermostat B, so that once closed, the contacts 25 remain closed independently of the temperature in the chamber 8 until the temperature of the compartment l2 rises abovea predetermined value. When once opened, however, contacts 25 will not be again closed until the temperature in both chamber 8 and compartment I2 falls. Opening of the contacts 32 causes interlocked contacts 33 to close, thus completing a circuit for closing contacts 26. Closure of contacts 28 completes a circuit for supplying the fan H with current by way of the

leads

29 and 30.

I claim:

1. A heating furnace having an entry and an exit, an entry chamber, closure means between the entry chamber and the furnace, further closure means dividing the entry chamber into a part adjacent to the furnace and a part remote from the furnace, an exit chamber adjacent to the furnace exit, a duct closed to. the interior of the furnace and connecting the two said parts of the entry chamber with the exit chambenmeans for passing a gas through the duct from the exit chamber to the entry chamber, damper means for controlling the relative proportions. of .the gas reaching the part of the entry chamber adjacent to the furnace and the part remote from the furnace respectively, and means for controlling the damper in dependence on the temperature of the part of the entry chamber adjacent to the furnace to reduce the proportion of gas entering the part of the entry chamber adjacent to the furnace when the temperature thereof falls.

2. A heating furnace having an entry and an exit, an entry chamber, closure means between the entry chamber and the furnace. further closure means dividing the entry chamber into a part adjacent to the furnace and a part remote from the furnace, an exit chamber adjacent to the furnace exit, a duct closed to the interior of the furnace and connecting the-two said parts of the entry chamber with the exit chamber, means for passing a gas through the duct from the exit chamber to the entry chamber, damper means for shutting off from the said duct the part of the entry chamber adjacent to the furnace, and means for actuating said damperimeans to shut oi! the part of the entry chamber adjacent to the furnace when the temperature of the last-named part of the entry chamber falls below a prede termined value. k

3. A heating furnace having an entry and an exit, an entry chamber, closure means between the entry chamber and the furnace, further closure means dividing the entry chamber into a nace, means for closing the damper means when the temperature of the last-named part of the entry chamber falls below a predetermined value, and means for opening said damper means when the temperature of the part of the entry chamber adjacent to the furnace and the temperature of the exit chamber rise above respective predetermined values.

4. A heating furnace having an entry and an exit, an entry chamber, closure means between the entry chamber and the furnace, further closure means dividing the entry chamber into a part adjacent to the furnace and a part remote from thefurnace, an exit chamber adjacent to the furnace exit, a duct closed to the interior of the furnace and connecting the two said parts of the entry chamber with the exit chamber, means for passing a gas through the duct from the exit I chamber to the entry chamber, damper means for shutting off from the said-duct the part of the entry chamber adjacent to the furnace, means for actuating said damper means to shut off the part of the entry chamber adjacent to the furnace when the temperature of the last-named part of the entry chamber falls below a predetermined value, heating means in the part of the entry chamber adjacent to the furnace, and means for switching said heating means on when the temperature of the exit chamber and that of the part of theve'ntry chamber adjacent to the.

furnace fall below respective predetermined val ues and for maintaining said heating means on so long as the temperature of the last-named part ofthe entry chamber remains below said lastmentloned predetermined value thereof.

5. A heatingfurnace as claimed in claim 3 comprising heating means in the part of the entry chamber adjacent to. the furnace, and means for switching said heating means on when the temperature of the exit chamber and that of the part of the entry chamber adjacent to the furnace fall below said last-mentioned respective predetermined values and for maintaining said heating means on so long as the temperature of the last-named part of the entry chamber remains below said last-mentioned predetermined value thereof.

6. A heating furnace as claimed in claim 2 comprising heating means in the part of the entry chamber adjacent to the furnace, and means for switching said heating means on when the temperature of the part of the entry chamber adjacent to the furnace falls below a predeter mined value.

7. A heating furnace having an entry chamber, an exit chamber, closure means between the entry chamber and the furnace, further closure means dividing the entry chamber into a part adjacent to the furnace and a part remote from -the furnace, an exit chamber adjacent to the furnace exit, a duct closed to the interior of the furnace and connecting the two said parts of the entry chamber with the exit chamber, means for passing a gas through the duct from the exit chamber to the entry chamber and damper means for controlling, the relative proportions of gas reaching the part of the entry chamber adjacent to the furnace and the part remote from the furnace respectively. 3

8. A heating furnace as claimed in claim 7 comprising heating means in-the part of the entry chamber adjacent to the furnace, and means