US3481047A

US3481047A - Method of and apparatus for cooling retorts rapidly and under negative pressure

Info

Publication number: US3481047A
Application number: US708418A
Authority: US
Inventors: William E Engelhard
Original assignee: Owego Heat Treat Inc
Current assignee: Owego Heat Treat Inc
Priority date: 1968-02-26
Filing date: 1968-02-26
Publication date: 1969-12-02
Anticipated expiration: 1986-12-02

Description

v 3,481,047 METHOD OF AND APPARATUS FOR COOLING RETORTS RAPIDLY Dec. 2. 1969 w. E'. ENGELHARD AND UNDER NEGATIVE PRESSURE Filed Feb. 26, 1968 III/III FiG. 2

INVENTOR w 5. ENGELHARD ATTORNEYS 3,481,047 METHOD OF AND APPARATUS FOR COOLING RETORTS RAPIDLY AND UNDER NEGATIVE PRESSURE William E. Engelhard, Apalachin, N.Y., assignor to Owego Heat Treat, Inc., Apalachin, N.Y., a corporation of New York Filed Feb. 26, 1968, Ser. No. 708,418 Int. Cl. C21d 1/74 U.S. C]. 34-20 8 Claims ABSTRACT OF THE DISCLOSURE A procedure for rapidly cooling a previously heated retort and metal parts assembly containing the same, said procedure including novel means for maintaining positive pressure interiorly of the retort during the cooling cycle, so that, if leakage occurs through the retort wall, the protective positive pressure atmosphere interiorly of the retort will leak outwardly through the retort walls, and into the chamber in which the retort is positioned, said chamber being supplied with ambient air channelled for scrubbing action around the retort and thence exhausted to the atmosphere, the chamber being maintained under negative pressure.

This invention is adapted for the cooling of articles, for example, for rapidly cooling parts previously heated in a retort, the retort being then lifted out of the furnace and positioned elsewhere for cooling. Such retorts are subject to leakage in practice, and it is diflicult to maintain them sealed from the ambient atmosphere.

It is desirable to rapidly cool the retorts and parts therein. It has been the practice heretofore to do so by directing blasts of air against the outer wall of the retort. That is objectionable since leakage into the retort is bound to ensue, with resultant exposure of the parts to the direct contact with cooling air, with ensuing oxidation and discoloration, scaling, shock and other harmful results. Both the static and ram pressures resulting can be higher than the pressure within the retort thus introducing air inside the retort. This results in discoloring or scaling of the work. In extreme cases of air leakage, where the protective atmosphere is combustible, such as pure dry hydrogen, an explosive condition can be created as well. Blowing air against the retort also resulted in temperature elevation, and contamination and great discomfort to personnel in the area.

Pursuant to the invention, the parts in the retort are maintained under positive pressure greater than atmospheric pressure, the retort being positioned in a cooling chamber wherein it is separated from the area of activity of personnel. A neutral or slightly reducing gas is pumped into the retort during the cooling cycle and ambient air is drawn around the retort in a predetermined scrubbing fiow contact pattern, and is then exhausted, thus maintaining negative pressure in the chamber-that is, less than atmospheric pressure, and preventing back flow or diffusion of moisture, air, unwanted vapors and gases into the retort and onto the work.

The drawings, illustrating procedures and devices useful in carrying out the invention, and the description below, are exemplary of the invention, which shall be deemed to cover all other procedures within the scope and purview of the appended claims.

In the drawings, wherein similar reference characters indicate like parts:

FIG. 1 is a fragmentary, vertical sectional view of a device embodying the invention,

FIG. 2 is a partly fragmentary, top plan view, taken at line 2-2 of FIG. 1, and

United States Patent 3,481,047 Patented Dec. 2, 1969 FIG. 3 is a vertical sectional view, taken at line 33 of FIG. 1.

As shown in the drawings, the device 10 of the invention comprises upper and lower walls 11, 12, and intermediate wall 14 (which may be circular) defining, with the upper and lower walls, chamber 13 enclosing the retort 16 positioned therein and onto the bottom wall 12 (FIG. 1) through opening 15 in the upper wall. The retort 16 (preferably cup-shaped, upwardly opening) previously heated with the (typically steel parts) parts 17 therein, for example, in a furnace, is positioned in chamber 13 and rapidly cooled pursuant to the invention.

In the rapid cooling procedure of this invention, preferably the last step in the heat treating operation, the parts 17 in retort 16 may be bathed or enveloped in an inert gas, admitted through a pipe such as 18, from a suitable source and discharged into the retort under pressure so that the parts 17 will be enveloped in neutral or slightly reducing atmosphere or of such other characteristics as desired. It is customarily desirable, for example, in the heat treatment of steel or alloy steel parts, to guard against oxidation of the parts. The procedure of this invention assures the maintenance within the retort of a protective atmosphere greater than atmospheric pressure, so that, if the retort is porous or leaks, leakage will be out of rather than inwardly of the retort. This invention provides rapid air cooling (air quenching) of retorts wherein the cooling air is always at a lower pressure than that of the gases within the retortassuring that any gas flow through cracks or other retort openings will be outward of the retort.

The chamber 13 is defined, as above noted, by the wall 14 and upper and lower walls 11 and 12. Upper wall 11 may for example, be a floor level wall, in a room having one or more units of the invention for cooling retorts and their contents. The retort is positioned in the chamber 13 to rest on the lower wall 12, the upper end of the retort being disposed just Slightly above the floor or upper wall 11 of chamber 13. In any case, the top of the retort preferably is approximately level with the wall 11 so that gas leaking from the retort may readily burn outwardly at that point rather than burn downwardly and into the chamber 13. The gaS supply pipe 18 may be welded to or otherwise formed as part of a cup-shaped closure member 20 for closing the upper end of the retort and providing a gas supply thereto. Gas supply pipe 18 may be welded thereto as at 19 and the closure member 20 may be sealed to the top of retort 16 by a thermal insulation or other sealing layer 21. The retort 16 preferably has upwardly extending ears 22 which may be apertured as at 23 so that elevating and lowering mechanism may be coupled thereto to facilitate the procedures herein described for positioning the retort into the chamber through aperture 15 of upper wall 11. Aperture 15 is further closed by a sealing ring which may comprise

segments

24, 24a, 24b, connected in any desired fashion as at 31 with two of the segment ends (32, 33) being free to facilitate uncovering the opening 15 and closing in abutment. The

ring segments

24, 24a, 24b are connected swivelly at 31 and positioned on upper wall 11 of chamber 13 at the opening 15 to close said opening; said segments are opened at their

free edges

32, 33 to expose opening 15, as for lifting retort 16 out of the opening 15. The chamber 13 is closed except for the air admission and discharge ports 25, 26 (FIG. 1) below described. Wall 14 may be provided with a slot or aperture 25 for admission of air into the chamber 13 and, spaced therefrom, with a discharge slot or aperture 26, which may have connected thereto or abutting the same, a cone or funnel shaped discharge port 27 leading to air discharge pipe 28 connected at its opposite end with a discharge point which may, for example, be outside the building wherein the rest of the device, above described, is located. Thus the discharge of air from chamber 13 may be calculated to occur at a remote point and the air in chamber 13 will not heat or contaminate the room atmosphere above the Wall 11.

Pursuant to the invention, ambient cooling air will enter through entry opening 25 into chamber 13 and circulate within the chamber around the retort 16 to cool the same and then pass out of discharge port 26 of air exhaust duct 28 which may contain a blower pump etc., 29. A series of bafiies 30 (FIGS. 3, 1) of tubular or of other form, may be secured in spaced relation to the interior of cooling chamber side or outer wall 14 so that air drawn through chamber 13 will be deflected and moved to turbulence and into scrubbing action along the retort, and will then be discharged from the chamber, elfectuating heat exchange Without leakage into the retort.

It will be noted from the foregoing that the exhaust of heat from retort 16 will be effective and continuous (due to pump 29) without elevating or contaminating ambient air above upper wall 11, maintaining the chamber 13 at negative pressure and the interior of the retort 16 at positive pressure greater than the (negative) pressure of chamber 13, preventing reverse leakage (from chamber 13)into retort 16.

Closure member 20 is prferably of smaller transverse cross-sectional proportions than the retort 16 so that (FIG. 1) a space 37 is provided therebetween for the flow of gases from the lower end of closure member 20 upwardly through said space 37 and thence above the floor 11. The gases may then burn harmlessly, as noted at 36, FIG. 1, above the interface between the insulation layer 21 and the retort 16 which is thus sealed from the flames at the level of the upper wall avoiding, the risk of explosion which might occur, if burning of the protective atmosphere occurred in the chamber 13.

The baffles 30 which (FIG. 1) are preferably secured to the inner face of Wall 14, which may be solid except for the entry and

discharge openings

25, 26 therein; said baffles 30 may be of such number and so spaced as is desired.

While the foregoing disclosure of exemplary embodiments is made in accordance with the patent statutes, it is to be understood that the invention is not limited thereto or thereby, the inventive scope being defined in the appended claims.

I claim:

1. In an apparatus for attaining rapid air cooling of metal parts previously heated in a retort, without exposure of the retort and said parts to said cooling air,

said apparatus comprising a chamber having an outer wall and spaced top and bottom walls, said top wall having an opening to receive the retort for positioning the same on the bottom wall,

4 and means for closing the space intermediate the chamber wall opening and the retort, proportioned to be positioned on the upper wall of the chamber at said opening, to close said opening,

said chamber side wall being provided with an opening for admitting ambient air,

and further provided with an air discharge opening spaced from the air admission opening, for connection with an air exhaust member for exhausting the air at a remote point.

2. In an apparatus as set forth in claim 1, baflles positioned on the interior of the chamber outer wall, for deflecting air in passage intermediate said openings.

3. In an apparatus as set forth in claim 1, said means for so closing the space intermediate the chamber wall opening and the retort comprising a ring, proportioned to be positioned on the upper Wall of the chamber at said opening, to close said opening.

4. In an apparatus as set forth in claim 3, said ring being formed of parts, and means movably connecting said parts.

5. In an apparatus as set forth in claim 1, an opening in said outer wall of the chamber for admission of ambient air into the chamber for thereby cooling the retort therein.

6. In an apparatus as set forth in claim 5, means for exhausting the air so moving into the chamber, to thereby impose a negative air pressure in said chamber.

7. In an apparatus as set forth in claim 5, a second opening in said outer wall of the chamber, and means for exhausting air connected to said second opening to thereby impose a negative air pressure in said chamber.

8. In an apparatus as set forth in claim 1, said retort being of cup-shaped, upwardly opening cross-section and a closure member proportioned to be received in the retort, to close the opening thereof and an insulating layer on the closure member and extending to the retort for sealing the top of the retort and means for admitting gas under greater than atmospheric pressure into the retort.

References Cited UNITED STATES PATENTS 1,185,280 11/1916 Beardsley. 1,727,192 9/1929 Baily. 2,985,551 5/1961 Todd.

WILLIAM J. WYE, Primary Examiner US. Cl. X.R.