US3460819A - Gas draft apparatus - Google Patents

Description

Aug. 12, 1969 o. E. FIKE GAS DRAFT APPARATUS Filed July 25. 1967 INVENTOR. DANIEL E. PIKE ATTORNEY United States Patent 3,460,819 GAS DRAFT APPARATUS Daniel E. Pike, Louisville, Ky., assignor to American Air Filter Company, Inc., Louisville, Ky., a corporation of Delaware Filed July 25, 1967, Ser. No. 655,815 Int. Cl. C21b 7/08; F23j /00; F231 17/16 U.S. Cl. 266--31 3 Claims ABSTRACT OF THE DISCLOSURE Apparatus for drafting hot gases in a metallurgical system including an improved wet cap arrangement cooperating with the discharge end of a hot gas conduit to selectively provide a gas treating liquid curtain and a liquid seal.

BACKGROUND OF THE INVENTION The present invention pertains to metallurgical apparatus and finds particular utility at the top and off-takes of metallurgical furnace shafts.

In metallurgical furnace shafts, such as shafts of metal melting cupolas, it is common to provide a wet cap arrangement adjacent the discharge end of the shaft to cool the metal surfaces exposed to hot cupola gases. To selectively prevent emission of gases from the discharge end of cupola and thereby permit bypass of such gases to a gas cleaning system, it also has been common to provide a mechanical damper arrangement at the stack discharge. For the most part, such arrangements have been comparatively complex in construction, installation, and operation, not only requiring a substantial amount of costly construction materials, but in addition, requiring a considerable amount of time in fabrication, construction and maintenance. Further, in such past arrangements when hot gases have been allowed to pass from the discharge end of the stack into the atmosphere, such gases have been heavily laden with gas contaminant materials.

SUMMARY OF THE INVENTION In accordance with the present invention, a new, useful, and unobvious draft apparatus for metallurgical furnaces is provided which lends itself to ready and economical fabrication, construction and maintenance, utilizing a minimum amount of materials and requiring a minimum of time for installation. Further, the apparatus of the present invention, in addition to providing a wet cap to cool the metal surfaces exposed to hot cupola gases, provides a means for selectively and alternatively affording a wet curtain through which the hot gases must pass to necessarily be scrubbed prior to entering the atmosphere. The apparatus of the present invention further provides means for insuring that the hot gases pass through the liquid curtain and a liquid seal to alternatively deter the hot gases from entering the atmosphere by way of the discharge end of the stack.

Various other features of the present invention will become obvious to one skilled in the art upon reading the disclosure set forth hereinafter.

More particularly, the present invention provides apparatus for drafting hot gases comprising: shaft means having a discharge end for flow of hot gases to atmosphere; liquid receiving chamber means surrounding the shaft means below the discharge end thereof; cap means posiice tioned in spaced relationship from the discharge end of the shaft means to permit passage of gases therebetween; liquid discharge means cooperating with the cap means to provide a liquid curtain through which gases flow to atmosphere; the cap means having a lower depending skirt portion extending therefrom into the liquid receiving chamber means; and liquid level control means cooperating with the liquid receiving chamber means to selectively maintain a liquid level therein above the depending skirt portion of the cap means to selectively provide a liquid curtain and a liquid seal at the discharge end of the shaft means.

It is to be understood that various changes can be made in the arrangement, form and construction of the apparatus disclosed herein by one skilled in the art without departing from the scope or spirit of the present invention.

Referring to the drawing, there is disclosed a partially broken away elevational view of one advantageous embodiment of the present invention incorporated with a cupola-type furnace.

Cupola 1 includes a metal charging inlet 2 and stack shaft 3, the shaft 3 having a hot gas bypass conduit 4 through which hot gases can be by-passed from stack 3 to suitable gas treating equipment known in the art and not shown. Since the present invention can be utilized with any one of several types of metallurgical furnaces, cupola 1 is disclosed in its broadest form without details.

Arranged to surround shaft 3 below discharge end 6 thereof is liquid receiving chamber 7. Disposed within chamber 7 in spaced relationship about discharge end 6 of shaft 3 is wet cap 8. Cap 8 includes an upper conical portion 9 and a lower depending skirt portion 11, which skirt portion extends above and below the discharge end 6 of the shaft into liquid receiving chamber 7.

Positioned above conical portion 9 of cap 8 is liquid discharge conduit 12, the conduit being arranged to discharge a suitable liquid such as water at the apex of conical portion 9 of wet cap 8. Further positioned above cap 8 in spaced relationship above liquid discharge conduit 12 is ejector conduit 13. Ejector conduit 13 which can be connected in a suitable manner not shown to hot blast air from the cupola system or to some other suitable hot blast air source is arranged to eject such blast of air along the direction of gas flow away from wet cap 8 as to provide additional pressure to the hot gases emitted from stack 3 and thus overcome the resistance occasioned by wet cap 8 above the shaft.

As will be noted in the drawing, liquid chamber 7 is provided with a liquid level control means in the form of an upper valve 14 and a lower valve 16. Valve 14 is selectively positioned above the bottom edge of lower depending skirt portion 11 of cap 8, while valve 16 is selectively positioned well below the bottom edge of skirt portion 11. By controlling the relative open and closed positions of valves 14 and 16 and the pressure through ejector 13, it is possible to selectively provide a liquid seal for shaft 3, or alternatively, a wet scrubbing curtain through which the hot gases necessarily must pass before being emitted to atmosphere.

The invention claimed is:

1. Apparatus for drafting hot gases comprising shaft means having a discharge end for flow of gases to atmosphere; liquid receiving chamber means surrounding said shaft means below said discharge end thereof; cap means positioned in spaced relation from said discharge end of said shaft means to permit passage of gases therebetween; liquid discharge means cooperating with said cap means to provide a liquid curtain through which gases flow to atmosphere; said cap means having a lower depending skirt portion extending therefrom into said liquid receiving chamber means; and liquid level control means cooperating with said liquid receiving chamber means to selectively maintain a liquid level therein above said depending skirt portion of said cap means to selectively provide a liquid curtain and a liquid seal at said discharge end of said shaft means.

2. The apparatus of claim 1 and aspirating means to selectively induce the flow of gas around the depending skirt portion of said cap means.

3. The apparatus of claim 1, the upper portion of said cap means being of conical configuration, said liquid discharge means being positioned to discharge liquid above the apex of said conical upper portion of said cap means.

References Cited J. SPENCER OVERHOLSER, Primary Examiner JOHN S. BROWN, Assistant Examiner US. Cl. X.R.

l19, 26ll7, 121

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