US1956959A - Damper - Google Patents

Description

May 1, 1934- E. J. MmoNNi-:LL`

DAMPER Filed March 12, 1931 2 Shee'S-Shet l I I l I I I IIIIIHI INVENTOR EW J n" May 1, 1934. E. J. MCDONNELL DAMPER Filed March 1 2, 1931 2 Sheets-Sheet 2 INVENTOR EM 4 w 0M.

l nfkwyww Z, entire area of the damper.

Patented May i, 1934 DAMPER Edward J. Mclloirnell, Pittsburgh, Pa., assignor to BlaW-Knox Company, Pittsburgh, Pa., a corporation of Pennsylt'ania Application March 12, 1931, Serial No. 521,968

1 Claim.

This invention relates to darnpers for the regulation of the flow of hot gases. Such dampers are used, for example, in open-hearth furnaces for controlling the flow of gas and air to and from the checker chambers. The term damper is used herein as a term of general definition and not of limitation and is intended to include dampers which work against metal seats (and sometimes termed Valves) as well as dampers working loosely in slots.

The temperatures encountered in this class of service range from S00 to 2008* F. It is necessary to cool the damper in order to prevent its warping, and water-Cooling has been found to be the most feasible method. The damper bears on its seat only around the rim and therefore the cooling of the rim only Would be sufficient to prevent the warping. I-Iowever, another problem enters in that of making the damper gas-tight over` its entire area. It is unsatisfactory to simply make a cooled rim and fill it in with brickwork, as the brickwork is not impervious to gases. Moreover, where the damper Works against a metal seat, both the dan'iper and the seat are inclined so as to insure proper seating contact and under these conditions there is danger of brick- Work falling out. It has therefore been customa-ry to make the dampers in the form of watercooled boxes With the cooling extending over the The metal face of the damper is impervious to the air or gas and the desired function is therefore obtained. However, numerous difiiculties are still encountered. A large amount of cooling water is required and the circulation within the damper is such that there is always danger of deposits of scale being built up, or of mud being deposited, so that a part of the damper eventually becomes unduly heated and burns out.

Another serious difficulty encountered arises from the fact that there is sufiicient tarry mater in the gases being handled to cause tar condensation on the cooled face of the damper. This tar deposit builds up to great thickness and eventually is likely to interfere with the proper sliding of the damper on its seat.

I overcome all of these difficulties by forming a damper from a rigid cooled rim which encloses a thin metallic uncooled diaphragm. This diaphragrn is preferably made of a metal having high heat-resisting characteristics such as socalled chrome steel containing from 12 to 30% chrcrnium. Steele of this Character are not appreciably affected by oxidation or corrosion at temperatures up to 20G0 F. The diaphragm is preferably secured to the cooled rim along the entire line of contact between the same by welding, or some other suitable method, whereby a gas-tight joint is insured.

With this arrangement the water-cooling is ccnfined to the rim and there is therefore no danger of tar deposits being built up. The damper is relatively light and may be easily raised and lowered on this account. It is not subject to warping and since a defined channel is provided in the rim for the cooling water, there is no danffer of portions of the rim being filled with scale or mud and causing burning out. The water may be forced through the rim at high Velocity so as to fiush out the water passage if desired.

In certain cases it may be desirable to cover the diaphragm with a refractory on one or both faces. This may be done by applying holding devices to the diaphragm and spreading on a plastic refractory. The diaphragm is preferably made with corrugations therein so as to minimize its bulging under varying temperatures.

In the accompanying drawings illustrating the present preferred embodiment of my invention and certain modifications thereof;

Figure 1 is a front elevation of my improved damper with a part of the refractory broken away,

Figure 2 is a top plan View thereof,

Figura 3 is a transverse Vertical section taken on the line III-III of Fig. 1,

Figures and 5 are views corresponding to Fig. 3, but showing modified dampers, and

Figure 6 is a view corresponding to a portion of Fig. 8 but showing a still further modification.

Referring first to Figures 1 to 3, inclusive, there is shown a. damper comprising an outer rim forL -ed of a piece of pipe 2 bent to the Shape of the damper and having its ends welded together. A bafile is inserted at 3 and inlet and Outlet fittings 4 are provided so as to allow of circulating Cooling water through the rim. Lugs 5 are pro- Vided for attaching the damper to the raising and lowering mechanism.

The opening within the rim is closed off by a diaphragm 6 made of thin sheet metal of a composition adapted to withstand high temperatures. As above stated, it is preferred to use a chrome steel or solne other alloy steel which is resistant to corrosion or oxidation at the temperatures encountered. The rim 6 is welded to the pipe 2 as indicated at W in Figure 3. It is provided With corrugations "1 so as to minimize its bulging or buckling under varying temperatures. It will be appreciated that the diaphragm may buckle or bulge to some extent due to temperature Variations, but by reason of the corrugations 7 and by reason of the thinness of the diaphragm, the strains on the weld will be relatively low and the diaphragm 6 is so thin as compared with the rim that the tendency to warp or twist the rim is so small as to be negligible.

Loops 8 are welded to the face of the diaphragm 'to retain a refractory facing 9. This facing is applied in the form of a plaster and is traveled on.

A bar 10 bent to conform to the Contour of the pipe 2 is welded to one face thereof as best shown in Figs. 2 and 3. The face F of this bar is planed and forms the face which slides on the valve seat. It will be noted that the bar 1G is placed on the side opposite the refractory 9. The reason for this is that ordinarily the damper will be inclined slig'htly so that the weight of the damper will cause it to bear upon its seat. When the damper is in this position the refractory 9 lies above the diaphragm 6 and therefore even if it cracks it is not likely to fall out. Of course the loops 8 serve to hold the refractory in place, but the placing of the refractory on the side opposite the valve face is an additional precaution.

In Fig. 4 there is shown a modified form of damper wherein the rim consists of a U-shaped member 11 having a plate 12 bent therearound and welded to the U-shaped member 11. This provides a water channel 13 and either edge of the plate 12 may be used for the valve face. It will be understood of course that water connections are provided and that the ends of the plate 12 and the ends of the U-shaped member 11 are welded together.

In Fig. 5 the rim consists of a U-shaped member 14 bent so that its legs terminate to one side of the damper, thus giving a double valve face. The legs of the U are bridged by a plate 15, thus providing a water channel 16.

The damper shown in Fig. 6 is similar to that shown in Figs. 1 to 3, except that instead of the circular pipe 2, a square pipe 17 is used.

In all of these dampers the danger of the circulation being impeded at any point by deposits of Scale or mud is reduced to a minimum. The water conduits may be flushed out whenever desired, thus eliminating any danger of the dampers burning out. Uniform circulation of the Cooling water is provided and this makes it possible to maintain the cooling water at all points below a temperature at which precipitation and scale forming will occur. The Cooling of the gases being Controlled :s reduced to a minimum and there is no condensation of tarry matter from the gas with a resulting unseating of the damper. The damper is materially lighter in weight and hence requires less power for its movement. The liability of water leakag'e is materially reduced since the water is confined in a tube formed with a minimum number of welds. The damper may be readily emptied of water, as is necessary in freezing weather when the damper is not in use. It is only necessary to apply air or steam under pressure to the inlet pipe to thus blow out the water.

The damper may be used for an extended period and then the bar 10 (or its equvalent in the other forms of the inventicn) may be again machined to present a new plane valve seating surface, and the damper returned to service. The life of the damper may thus be indefinitely prolonged.

It will be understood that where no seat is used, and the damper is employed only for the throttling of gas or air, the invention still possesses many of the above advantages recited. The present dampers, which operate in Vertical brick slots, Z?

require that the slot be materially greater in width than the damper, because the uncooled dampers often employed in such work have a tendency to Warp to such a degree that binding occurs. Where water-ccoled dampers of the old type are employed, much more heat is absorbed from the gas than is desirable and the damper is lilrely to become partially filled with deposts and to burn out on this account.

I have illustrated and described the present J preferred embodiment of the invention and certain modifications thereof. It will be understocd, however, that it is not limited to such forms, but may be otherwise embodied within the scope of the following claim.

I Claimr- A damper comprising a rim definingr an opening, the rim being in the form of a hollow rigid annulus adapted to contain Cooling water, a diaphragm extending over and closing off the opening, the diaphragm being made of sheet metal and lying between the planes of the opposite faces of the rim, and a refractory coating over at least one surface of the diaphragm, the refractory material lying within the zone defined by the planes of one face of the diaphragm and the adjacent face of the rim.

EDWARD J. MCDONNELL.

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