US1907777A - Annealing furnace - Google Patents

Description

y 1933- c. E. FRAZIER 1,907,777

ANNEALING FURNACE Fild Sept. 30, 1931 a Sheets-Sheet 1 INVENTOR May 9, 1933.

c. E. FRAZIER ANNEALING FURNACE Filed Sept. 30,- 1931 3 Sheets-Sheet 2 Patented May 9, 1933 UNITED STATES PATENT OFFICE CHAUNCEY E. FRAZIER, OF WASHINGTON, PENNSYLVANIA, ASSIGNOR TO SIMPLEX I ENGINEERING COMPANY, A CORPORATION OF DELAWARE ANNEALING FURNACE Application filed September 30, 1931. Serial No. 566,018.

My invention relates to heating furnaces in general, and more specifically it is directed to kilns and annealing furnaces used for the heat treatment of articles formed of various materials, including glass, earthenware and metal. The invention consists in furnace structure which admits of a more precise control and distribution of heat within the furnace chamber.

In general, my invention comprises improvements upon the structure disclosed in Letters Patent of the United States No. 1,525,644, granted to me February 10, 1925, and, while I have said that the invention is applicable to heating furnaces generally, and while I so claim it, I shall in the following specification, for purposes of illustration, de-

scribe it as it may be embodied in a lehr for annealing glassware. this being the particular application in which I have developed it.

In the accompanying drawings Fig. I is a view in vertical section, taken on the medial line of a lehr embodying the invention; Fig. II is a view of the lehr in horizontal section, taken on the plane 11-11 of Fig. I; and Figs. III and IV are views in cross-section, taken, respectively, on the planes IIIIII and IV--IV of Fig. I.

The lehr shown in the drawings is of muffle type and includes an annealing chamber 1 and a delivery passageway 2 continuous with the annealing charnber. Through the annealing chamber and passageway an endless conveyor is caused to advance, and in this case I employ a woven belt conveyor which is trained over rollers 4 adjacent the entering end of the lehr and extends in its upper reach above the floor 3 of the lehr where it is borne upon a line of cross supports 5. The reference numerals 6 is applied to the woven belt, which is fragmentarily indicated in Fig. I. In its lower reach the conveyor belt conveniently is supported upon rollers 7 (cf. Figs. I and IV) and is guided laterally by means of rollers 8 (cf. Fig. III), while in its upper reach the belt is guided by angle members 9 secured to the cross supports 5.

A 'muflle chamber surrounds and envelops the annealing chamber 1. The muflle chamber has a floor 10 and side walls 11. The roof of the mufile chamber comprises an arched section 12 located above the forward end of the annealing chamber, and a fiat section 13 located over the rearward end of the latter chamber. These general features of construction are well known and require no extended description here; suflice it to say, thatthe structure is built of brickwork and refractory material, framed, strengthened, braced. and tied together with iron in familiar manner. as illustrated in the drawings. It is with the arrangement and structure of the mufile chamber, and the consequent course of the burning fuel and of the products of combustion that the invention is primarily concerned.

Due to the fact that the mouth 14 0f the lehr must be uncovered during charging, whether such charging be manual or mechanical, the heat radiation and other heat losses are greater at the front of the lehr than at points rearwardly thereof. Accordingly, it is necessary to apply more heat at the front of the lehr, to compensate for these greater heat losses. hen attempting to do this in accordance with present practice. by applying heat to the bottom of the lehr, so much heat is required that the refractories are damaged and require frequent repair. Additionally the conveyor belt becomes exceedingly hot. causing it to stretch, and quite often the conveyor becomes so hot as to leave imprints on the bottoms of the articles being annealed, thus weakening their structure and destroying their marketability.

To overcome this objection, I apply heat to the top of the lehr chamber; that is, I introduce fuel to a firebox or inlet chamber 15 on top of the lehr and direct the flow of burning fuel toward the front of the lehr, in a direction opposite to that in which the articles are moved by conveyor 6.

The fire box 15 is located between the arched roof 12 and the roof 16 of the annealing chamber. and constitutes an element of the mufile chamber proper. Between the roof 16 of the annealing chamber and the flat roof 13 of the muflie chamber. there is provided an outlet or flue gas chamber 17 which is connected adjacent its rearward end to a stack Or chimney; the stack is not shown in the drawings. but the outlet 18 indicates where connection is made to it. The annealing chamber is so built within the muffle chamber that there are formed tunnel flues 19 and 20, ex-

- of the annealing chamber. as shown. In this case I show four side flues '2?) on each side of the lehr. and each side flue is connected by a passage 21 (cf. Figs. I and III) to one of the tunnel flues 19, 20. A damper 25 is organized to control the flow of gases in each side flue.

The inlet chamber or fire-box 15 is the primary combustion chamber. If producer gas is used as fuel. a suitable burner or burners may be connected to the inlet 26 in the rearward region or roof 12 of the firebox. If the fuel be natural gas or oil. the burner or burners may be placed in the opening or openings 27 in the rear wall of the fire'box. In either case the fuel is introduced in the rearward region of the tire-box and is caused to flow forwardly therein. The burning fuel and the products of combustion sweep forward, over the roof 16 of the annealing chamber 1. and thence flow down vertical flues 9.1. 22. at the front of the lehr. and enter the tunnel flues 19 and 20. In flowing along the tunnel flues the hot gases find escape through passages 24 into the several side flues S23, whence they rise and enter the outlet chamber 17. In chamber 17 the hot products of combustion flow along the roof 16 toward the rear of the lehr. and finally are drawn through opening 18 into the stack.

It will be observed that there are duplicate sets of flues symmetrically arranged on opposite sides of the mid-line of the lehr: that each set includes a longitudinal tunnel (19 or 20) beneath the floor of the annealing chamber: that a vertical flue (21 or 22) connects each tunnel flue with the tire-box. at the entering end of the lehr: and that a series of spaced side flues connect each tunnel flue with the outlet chamber 17. It will be further ob erved that the burning fuel sweeps toward the front ofthe lehr when it is introduced to the tire-box. and that during combustion the bot products are carried down the sides of the lehr adjacent the mouth of the annealing chamber 1 Where they enter the tunnel flues 19. 20 extending beneath the floor 3 of the chamber 1. The dampers 25 in the vertical side flues 23 permit selective regulation of the flow of hot gases from the tunnel flues to the outlet chamber. whereby temperature conditions at various points in bustion in the above described courses, I provide suflicient heat at the entrance of the lehr to compensate for heat radiation and other heat losses arising during the charging of ware. The heating effect is more uniform, there being no localized overheating, tending to injure the refractories and conveyor belt, and tending to mar the bottoms of the articles being treated. The control afforded by the dampered side flues 23 admits of such distribution of the flowing gases that practically any desired temperature condition may be maintained in the lehr; in the words of the art, any annealing curve or heat gradient may be established in the lehr.

Accordingly, the ware upon entering the lehr and while still in unannealed condition, is not subject to such inequalities of temperature in different parts as to break. Both the annealing efficiency and the combustion or fuel efliciency are increased in the lehr of my invention. The lehr has greatercapaeity and is effective in providing more uniform heating and cooling during the an nealing process.

I claim as my invention:

1. In an annealing furnace, the combination with a lehr chamber, of a fire-box overlying said lehr chamber, a tunnel flue extending longitudinally beneath said chamber, a front flue in each of the opposite side walls of the furnace and connecting said fire-box with said tunnel flue adjacent the entrance of said furnace, means for introducing fuel to said fire-box at such point that burning fuel and products of combustion are caused to flow forwardly of the furnace and to enter said tunnel flue by Way of said front flues, and thereby produce a concentration of heat at the mouth of the lehr chamber, a flue gas chamber immediately above said lehr cham her, and a series of side flues arranged along the opposite side walls of the lehr'to the rear of said front flues, which side flues establish communication between said tunnel flue and said gas flue chamber.

2. In an annealing furnace, the combina tion with a lehr chamber, of a fire-box overlying said lehr chamber, a tunnel flue extending longitudinally beneath said chamher, a front flue in each of the opposite side walls of the furnace and connecting said firetion with a lehr chamb flues, and thereby produce concentration of heat at the mouth of the lehr chamber, a flue gas chamber overlying the roof of said lehr chamber to the rear of said fireof side flues they rise from said side flues and enter said chamber.

3. 11 an annealing furnace, the combination with a lehr chamber, of a fire-box overlying said lehr chamber, a tunnel flue extending ongitudinally beneath said chamber, a flue in each of the opposite side Walls of the furnace and connecting said fire-box with said tunnel flue adjacent the entrance of at such point that burning fuel and products of combustion are caused to flow forwardly of the furnace and to enter said tunnel flue by way of said front flues, and thereby produce concentration of heat at the mouth of the lehr chamber, an outlet chamber overlying the roof of said lehr chamber to the rear of said fire-box, a series of side flues arranged along the opposite side walls of the d connecting said tunnel flue to said outlet chamber, dampers organized with said side flues for regulating the escape of the products of combustion at various points of the hey rise from said outlet chamber. n an annealing'furnace, the combinaer, of an inlet chamber an ber disposed symmetrically, one on each side of its medial line, each of said tunnel flues having associated therewith a front flue affording, immediately at the entrance of said furnace, communication with means for introducing uel to said inlet chamber at such point that urning fuel and products of combustion are caused to flow forwardl feet rearward movement of said products of combustion when they rise from said side flues and enter said outlet chamber.

In an annealing furnace, the combination with a lehr chamber, of an inlet chamber and a suceeeding outlet chamber above the lehr chamber, two lon 'tudinal tunnel flues beneath the lehr chamber disposed symmetrically, one on each side of its medial line, each of said tunnel flues having associated therewith a front flue afl'ording, adjacent the encommunication with burning fuel and products of comb caused to flow forwardly of the f enter said tunnel flues walls of the tion between each of said ampers organized with said side flues for regulating the escape my hand.

CHAUNCEY E. FRA ZIER.

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