US2219693A - Water cooled furnace door - Google Patents

Description

o 1940- Q E. J. MODONNE LL 2,219,693

I WATER COOLED FURNACE DOOR I Filed May 9, 1939 I .15 .1? Fig. l- I 17 11 I 5M il f INVENTOR 21 Edward J.McDonneH Patented Oct. 29, 1940 PA ENT OFFICE 2,219,893 I warm coomn FURNACE noon Edward J. McDonnell,

to Blaw-Knox Company,

poration of New Jersey Fox Chapel, Pa assignor- Pittsburgh, Pa., a cor- Application May 9, 1939, Serial No. 272,605

9 Claims. 122-498) This invention relates to water cooled furnace doors such as are used in open hearth furnaces. The doors used on open hearth furnaces must withstand very severe treatment. They are subjectedv on their inner faces to extremely high temperatures. They must be strong enough to withstand the various blows and stresses to which they are subjected in service. Furnace doors were originally made of cast metal andwater cooling was resorted to at a very early date. For example, in McDonald Patent 258,095, dated May 16, 1882, there is shown a water pipe cast in a door frame.- Such' doors, however, are wholly unsuited to present day requirements. Since that time a very large number or door constructions have been devised. Doors have been made with hollow bodies and hollow rails (Knox Patent 789,550, dated May 9, 1905).- Wrought metal welded to form has been used in place 01 cast metal (Knox'Patent 1,037,778, dated Sep tember 3, 1912). Others have been made with openings through the body portion for the purpose of better tying inthe refractory lining of the door to the metallic portions thereof (Williams Reissue Patent 17,864, November 11, 1930). Experience has shown, however, that all of these doors have practical shortcomings. One of the principal difficulties encountered, despite the'water cooling which has been provided, is distortion of the door-after continued use.. Such distortion makes for a leaky door opening and may result in loosening of the refractory lining. The conditions of service are so severe that maintenance, both from the standpoint of cost and inconvenience, becomes an important factor.

I have observed that one or the most vulnerable parts of a door from the standpoint of maintenance is the lower ridge or rail. The doors on an open hearth furnace are in closed position most of the time-probably 95% or the timeand when closed the only metallic portion which is exposed directly to the heat or the furnaceis the lower rail. While attempts have been made to cool the bottom rail by supplying the,

cooling water to it in the first instance (see Knox Patent 1,037,778, above referred to), the dimculty has not heretofore been overcome. There has been a tendency to deposit dirt or sludge in the bottom of the door, 'either at the bottom of thebody portion or in the lower rail, thus decreasing the cooling efiect and increasing the likelihood of distortion. The lack of positive. circulation through the exposed rail also is likely to result in such a rise in water temperature as to cause deterioration of the metal from acidof Fig. 1;

' rail 5 'for hanging ity in the water or from other entrained substances. g I

My improved door is designed to overcome or minimize these difllculties.

In the accompanying drawing illustrating a present preferred embodiment of the invention and certain modifications thereof,

Fig. l'is an elevation of my improved door as viewed from the back or exterior side; Fig. 2 is an elevation of the door as viewed 10 from the front, that is to ay. the furnace side? Fig. 3 is a bottom view; Fig. 4 is a vertical section on the line IV-IV Fig. 5 is a view corresponding to a portion of 15 Fig. l'but showing a modified structure, and

Fig. 6 is a vertical section through the bottom portion of a. still further modification.

Referring first to Figs. -1 to 4 inclusive, the door is shown as being made of wrought metal 30 plates bent and welded to form a body 2 with integral side rails 3 and 4 and a top rail 5. The front plate 6 and the back plate I of the body are tied together by stays 8 and are both pierced and turned inwardly to form the, customary g5 peep hole 9. Hangers 10 are secured to the top the door on the 'door lifting and an eye H is provided to receive mechanism,

use, in mounting the aicrane hook or sling for door or mov n it about.

1 Within the door there is provided a partition 12 which forms a water tight barrier between the rail 4 and the water space of the door. A

water connection I3 is provided at the top 01'.

the door and inthe preferreduse of my inven- 35 tion this connection will serve as the inlet for the cooling water. Cooling water thus supplied travels downwardly along the rail 4 to the bottom of the door and.passes thence through a conduit l4 extending across the bottom of the o :door-between the rails 3 and 4. This conduit,

as illustrated in Figs. 2 and 3-, is a length of i whose ends are welded into the rails at 15. The cooling water.

heavy pipe 3 and 4, as indicated passes through the pipe l4 and is discharged through an elbow l6 into the rail 3. It circulates through the remaining .water space of the door and is taken off through a; water connection l1.

The pipe I4 is of relatively small cross section 50 as compared with the other passages through which the water must flow between the connections l3 and H. In consequence the water travels through the pipe at relatively high velocity. This increases the cooling efiect and minimizes 55 the danger of deposits tending to clog the system. It is an unfortunate fact that in practice furnace doors are not kept as free of deposited dirt or sludge as they should be, and in doors of usual construction this is likely to cause a burning out or cracking of the exposed water cooled surfaces. In my design the neglect of such cleaning out is of little consequence. Such sediment as may be deposited will lodge in the bottom portion l8 of the body, where it is subjected to relatively little heat from the furnace because this portion lies behind the pipe l4. Wash-out plugs I9 are provided for removal of this deposit.

It will be noted that the provision of a conduit of relatively small cross section insures adequate cooling in two ways. First, the velocity of the cooling water is substantially increased, and second, the area of metal exposed to the furnace heat is substantially reduced.

By reason of the facts above stated, there is very little likelihood of trouble with my improved door, but if the door should be abused and damaged it is a very simple matter to remove the pipe and weld a new one into place. This will, in all likelihood, be the only repair necessary, because even under conditions of extreme abuse, distortion of the pipe [4 fromv excessive heat will not lead to distortion of the remainder of the door.

The elbow l6 prevents accumulation of.dirt at-thebottom of the rail 3 in such manner as to insure against plugging at the end of the conduit I4. e v

. The door is provided with a refractory lining 20. Usually this lining will be built up of brickwork as shown. The rails 3, 4 and 5 are all beveled inwardly so as to help hold the brickwork in place. The-brickwork is supported in part by the pipe [4 and in part by ledges 2! which are welded to the front plate 6. If desired, these ledges can be placed at a somewhat lower level than the pipe l4 so as to give the effect of aninward bevel and thus help to key the brickwork in place.

A reinforcing plate 22 is provided around the bottom portion I8 of the door. This reinforce-- ment consists of an angle-shaped guard piece which extends across the back of the door body through the bottom and also extends beneath the bottom. This reinforces the door against blows from the charging machine and compensates in this respect for the removal of the bottom rail ordinarily employed. It has heretofore been deemed desirable to maintain the door at full thickness at the bottom in order to give the door adequate strength against blows from the charging machine. My improved door thus departs markedly from usual construction. v

It will be noted from Fig. 4 that the pipe I4 is placed above the plane of the bottom of the door. It is thus adequately protected against being struck by the charging boxes or scrap therein during the charging of the furnace.

Various modifications may be made. For instance, instead of welding the conduit l4 into place, itinay be provided with threaded connections. Generally speaking, however, I prefer to use a welded connection.

As above indicated, I prefer that the cooling water shall be fed through the rail 4 so as to pass v through the pipe I before circulatingfth rough the'rest of the door. If desired, however, this may be reversed. 3 In either case the high speed circulation through the. pipe will be attained,

but in the latter case it will enter the pipe somewhat warmerT In Fig. 5 I have showna modified door wherein the partition I2 is omitted and the water connection l3 leads to a pipe 30 extending downwardly inside the rail 4' and connects to, an elbow II to the pipe ll. 4

In Fig. 6 I have illustrated another modification in which a partition 40 is provided so as to form a conduit 4| at the bottom of the door on the furnace side. In this case the conduit 4| will be arranged in the circulatory system in the same fashion as the pipe 14 or M.

My improved door has numerous advantages. It is not unduly expensive to construct and requires a minimum of maintenance. All of the cooling water supplied to the door passes at high velocity through the bottom portion which is exposed to the flame, thus doing away with the dangers ofdistortion and deterioration from attack of acids or deposition of dirt.

v While I have illustrated and described the present preferred embodiment of my invention and various modifications thereof, it will be understood that this is by way of example only,

'and that the invention may be otherwise embodied and practiced within the scope of the following claims.

I claim:

1. A water-cooled 'furnace door comprising a hollow body, hollow topand side rails projecting from one side of the body to form an openfaced and open-bottomed recess for a refractory tom of the recess infront of the body and between the side rails and forming a water space separate from the body, the conduit being of relativelysmall cross section as compared with hollow body; hollow top and side rails projecting from one side of the body to form an open-faced and open-bottomed recess for containing a re- I lining, and a conduit extending across the botfractory lining, a water conduit of relatively small cross section separate from the body extending across the bottom of the recess, and. a supporting ledge on the body for supporting a refractory lining.

4. A water cooled furnace door comprising a hollow body, hollow top and side rails projecting from one side of "the body to form an openfaced and open-bottomed recess, a refractory lining in the recess, a conduit separate from the body extending across the bottom of the recess in front of the body and between the side rails, and a supporting ledge on the body upon which the refractory lining may rest.

5. A water cooled furnace door comprising a hollow body, hollow top and side rails projecting from one-side of the body to form an openfaced and open-bottomed recess'for a refractory .door linin-g, a water conduit separate from the 6. A water-cooled furnace door comprising a body made from two rectangular metal plates spaced apart to provide a water space therebetween, a hollow top rail and two hollow vertical tending across the bottom of the recess in front of the body and terminating in the two side rails, the pipe being adapted to support the refractory lining within the recess, and water connections for supplying cooling water to the pipe and thence to the interior of the door.

7. A water-cooled furnace door comprising a body made from two rectangular metal plates spaced apart to provide a water space therebetween, a hollow top rail and two hollow vertical side rails each of generally rectangular section and extending around three sides of the periphery of the door, the rails extending inwardly so as to form an open-faced and open-bottomed recess for containing a refractory lining, and a water pipe of generally circular'cross-section extending across the bottom of the recess in front of the body and terminating in the two side rails, the pipe being adapted'to support the refractory lining within the recess, and water connections for supplying cooling water to the pipe and thence to the interior of the door, the pipe being of smaller cross-section than any of the rails.

8. A water-cooled furnace door comprising a hollow metal body having hollow side rails extending outwardly from one face thereof so as to form a recess for a refractory lining, a pipe extending between the side rails and terminating therein, the bottom of the pipe being at a higher level than the bottom of at least one of the rails, the pipe being of smaller cross-section than said rail, and means for supplying cooling water first through the pipe and then through the said rail whereby foreign matter'is substantially precluded from settling in the pipe.

9. A water-cooled furnace door comprising a hollow metal body having hollow side rails extending outwardly from one face thereof so as to form a recess for a refractory lining, a pipe extending between the side rails and terminating therein, the bottom of the pipe being at a higher level than the bottom of at least one of the rails, the pipe being of smaller cross-section than said rails, means for supplying'cooling water first through the pipe and then through the said rail whereby foreign matter is substantially precluded from settling in the pipe, and a wash-out plug in said side rail near the bottom thereof and adjacent the outlet from the pipe into the side rail.

' EDWARD J. McDONNELL.

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