US3237687A - Heat transfer chamber - Google Patents

Description

4 Sheets-Sheet 1 Filed Feb. 8. 1963 7 05 a T. W? mag w 4 V M M Y B March 1, 1966 co s 3,237,687

HEAT TRANSFER CHAMBER Filed Feb. 8, 1963 4 Sheets-Sheet 2 //VI/ENTOR MAR VIN 6. COMBES March 1, 1966 M. G. COMBES 3,237,687

HEAT TRANSFER CHAMBER Filed Feb. 8, 1963 4 Sheets-Sheet 5 FlEi-ZEI- W/////////// /W A INVENTOR M/Y/iV/N 6. COM5E'5 BY i March 1, 1966 COMBES 3,237,687

HEAT TRANSFER CHAMBER Filed Feb. 8, 1963 4 Sheets-Sheet 4 O O O O O O O O O O O O o o o o O O O 0 o o o M o o o 0 m0 O o O O 06 o o o O I? O o O O y 32 O O 0 O /04 26 o O O O "Y //6 o o o 0 j /0o FIE-1alNVE/VTOR MARVIN 6 COMBES 14 r ran A// United States Patent 3,237,687 HEAT TRANSFER CHAMBER Marvin G. Combes, Castro Valley, Calif., assignor to Grove Valve and Regulator Company, Oakland, Calif., a corporation of California Filed Feb. 8, 1963, Ser. No. 257,144

'3 Claims. (Cl. 165-145) This invention relates to a vacuum chamber arid, more particularly, to a chamber in an evacuation system containing cold panels for freezing and settling out certain components of the gaseous molecules therein.

It is an object of this invention to provide a multiwalled chamber conditioned to withstand the effects of extreme differential temperatures as well as pressure differential resulting from the vacuum maintained therein.

It is a further object of this invention to provide a plurality of cold panels or baffles through which a cold medium is circulated.

It is a further object of this invention to provide a plurality of cold panels comprising a thick wall and a thin wall welded together in spots arranged in spaced intervals with the thin wall being expanded outwardly between such spots to provide flow passages for a coolant while the thick wall presents a smooth, regular surface.

It is a further object of this invention to provide an insulated wall comprising two sheets welded together at spaced spots with one sheet being more susceptible to deformation by bending than the other and being expanded outwardly between such spots.

It is a further object of this invention to provide an elbow vacuum duct of relatively thin wall construction having reinforcement means adapted to withstand compressive forces both radially and circumferentially.

Other objects and advantages of this invention will become apparent from the specification following when read in conjunction with accompanying drawings where- FIG. 1 is a side view in partial section of a vacuum duct forming part of this invention together with a gate valve forming a part of an evacuation system;

FIG. 2 is an enlarged section view of the vacuum duct with cold trap therein;

FIG. 3 is a fragmentary view of the vacuum chamber wall;

FIG. 4 is a section view taken along the line 4-4 of FIG. 3;

FIGS. 5 to 7 are section views in more or less schematic form showing the method of fabricating a cold baflle;

FIG. 8 is a fragmentary view of a modified form of Cold panel;

FIG. 9 is a section view in reduced scale of the form of cold panel shown in FIG. 8;

FIG. 10 is an isometric view of the form of cold panel shown in FIG. 8;

FIG. 11 is a view in partial section of a cold panel mounting clip;

FIG. 12 is a view in partial section taken along line 12-12 of FIG. 11;

FIG. 13 is a section view of a mounting with alternate form of cold panel; and

FIG. 14 is a section view showing a valve bonnet with circulating means for cooling bonnet seals forming part of this invention.

Referring now to FIG. 1, the vacuum chamber of this invention 10 is adapted to be connected at 12 to a chamber to be evacuated and at 14 to a vacuum pump, neither the pump nor the chamber being shown here. As illustrated, the chamber 10 comprises an elbow duct which may be of rectangular cross section having parallel side walls 16 of generally quarter circle configuration and a 3,237,687 Patented Mar. 1, 1966 See convex intermediate wall 18, or in the alternative it may be of circular or oval cross section. In any event, the walls are preferably reinforced by angle members 20 welded thereto which are disposed on the side and intermediate walls to give the rigidity of the triangle, with the angle most remote from the walls and the legs 22 welded directly thereto. Consequently the legs of the angle member provide beams of maximum thickness along two axes extending from the wall being reinforced. Thus, with the chamber 10 under high vacuum, compressive forces are exerted both radially and circumferentially and these forces are resisted by the legs of the angle reinforcement members.

Secured in the duct and associated therewith is a suitable valve 24 such as the gate valve shown having end and side walls 26 and 28. The valve body formed by the end and side walls 26 and 28 is reinforced by hoop like members 30 and is closed at one end by a bonnet structure 32 through which extends a stem or the like for operating the valve closure member (not shown).

Supported within the elbow duct 10 is a similar elbow cold trap 40 preferably conforming to the cross-section of the duct 10, in this case having parallel side Walls 42 and an arcuate intermediate wall 44. Extending between the side walls 42 is a series of panels or baffles 46 to 52 (FIG. 2) connected by tubes 54 to an intake manifold 56 conducting a coolant thereto, and by tubes 58 to outlet manifold 60. The inlet and outlet manifolds 56 and 60 are in communication at 62 and 63 respectively to the cold trap 40 so that a cryogenic fluid such as liquid nitrogen may be introduced at inlet 64, circulated to and through the cold trap and baflles 46 to 52 to outlet conduct 65. The liquid nitrogen can cool the surfaces of the cold trap wall and panels to the order of 300 F. to freeze and settle out molecules of oil vapor which might back-stream from the vacuum pump and water vapor or the like that might be traversing the chamber 10 and impinge upon one of the cold surfaces.

Referring now to FIGS. 3 and 4 the construction of outer chamber 10 and the cold trap 40, as well as the various bafiles is illustrated in detail. The description immediately following relates particularly to the outer chamber and cold trap side walls 16 and 42, but it is to be understand that it applies also to the arcuate intermediate walls 18 and 44. as well as to the walls of the baffles 46 to 52, subject of course to modification necessitated by variations in cross-section configuration. Welded to the inside surface of the side wall 16 at spaced intervals 70' is a thin liner sheet 16a. The welding may be accomplished simply by heating the sheets at spaced spots 70 so that they fuse into each other. Similarly a thin sheet 42a is welded to the outer surface of the cold trap wall 42 at intervals 72. The spot welding with respect to both cold chamber and the cold trap 40 extends over both side walls and intermediate walls and, in the case of a circular cross-section elbow, over the circumferential surface. In each case a unitary, double walled shell is produced. Then a fluid, such as water, compressed air or the like is introduced between the walls at a pressure sufficient to buckle the thin sheet 16a 0r 42a outward producing a waffle effect with a series of blisters between the weld points 70 or 72. However, the fluid pressure is limited so that it is not sufiicient to distort the thicker sheet 16 or 42, leaving it in a smooth regular configuration. As shown in FIGS. 1 to 4 the blister surface of the outer shell 10 is preferably on the inside to facilitate attachment of the reinforcing angle ribs 20 and for assembly. However, the blisters of the cold trap 40 are preferably on the outside so that smooth, even surface is presented to molecules passing therethrough, it being desired not to entrap or lodge molecules that are not taken from the gas being evacuated byfreezing. For similar reasons, the radially inner surface of the baffie plates are preferably the thicker, smooth wall, and the outer surface away from the path of the molecule is of the blister configuration.

Besides ease of manufacture, the waffle construction of the walls and panels provide a number of advantages. For example, contact, and hence heat conduction between the two sheets is minimal, and particularly in the case of the outer wall 10 where an intermediate vacuum is maintained to minimize danger of vacuum loss through leakage, this provides an excellent insulating wall against the temperature extremes to which it is subjected between inside and outside. Further the waffie construction provides a series of passageways through which hot gases may be passed to bake out the chamber before operation. Additionally, the thin blisters can bend to function as a plurality of expansion joints between the two sheets for accommodation of differential thermal expansion and contraction between the sheets.

A further advantage is illustrated in FIGS. 5 to 7 in connection with the fabrication of a multi-panelled baffle such as 48. As there shown the thin sheet 48a is welded to the thick sheet 48b as flat sheets before they are bent into their ultimate configuration. Then, after they are bent to the configuration of FIG. 6 a fluid under pressure is introduced through an intake 75 to expand the thin sheet between the welds 73 into its waffle configuration. It is apparent that this method is also applicable to the formation of the duct and cold trap 40. That is, the sheets from which they are formed may be welded together first, formed into square or round elbows, and then expanded into the waffle pattern.

Referring to FIGS. 8 to 10a modified form of wall structure is shown with its method of formation illustrated schematically. As shown in FIG. 8, the welds 76 are formed in parallel rows with the spacing between rows being much greater than spacing between welds of the individual rows. Thus, there is much greater tendency for the thin sheet 78 to be buckled over the longer span between rows under pressure of a fluid introduced through a suitable inlet 80 to the space between the thin sheet 78 and the thicker sheet 82. Moreover, once bending occurs along one axis a sheet becomes increasingly resistant to bending along the other axis. The result is that the thin sheet forms a series of parallel conduits 83 formed by the corrugations which present few crevices or corners to molecules moving in directions parallel to the corrugations.

In FIGS. 11 to 13 I have illustrated a method for mounting the bafile panels on the side walls 42 of the cold trap 40. As shown there, a pin 86 is welded or otherwise secured to each cold trap side wall 42 with pairs of pins on opposite side walls being in alignment. A C- clip or retaining member 88 which is welded on the top of the pin 86 to open vertically for reception of the lower edge and corner of a vertical panel of a tri-panel baffie, such as baffles 46, may open at an angle for single panel baflles 52. Consequently, since the panels are connected into an assembly by fairly rigid tubing 54, the clips present a series of supports for the lower edge of the panel assembly which hold the panels in proper disposition but permit expansion and contraction thereof such as may be occasioned by temperature increase and desired, be closed at the open end to grip the panel but they should not grip it so tightly as to prevent a panel 52 from expanding and contracting in accordance with temperature differences. Preferably also the bafile assembly is supported additionally within the cold trap by means of a hanger 90 secured to the upper wall of the cold trap.

Referring now to FIG. 14 a further use for the blister type construction is illustrated in connection with the bonnet construction 32 for the valve 24. There,afiange plate 92 is secured to the ends of the side wall 26 which are preferably of double walled construction for insulation, particularly since it is desirable to heat them in order to drive off absorbed vapor molecules or the like. A series of bolt holes 94 are aligned with similar bolt holes 96 in a bonnet plate 98 so that the bonnet plate may be secured to the flange. It is desirable to have all inner surfaces of stainless steel while, for purposes of economy, some of the thicker members such as the flange Q2 and bonnet plate 98 are of a heavy carbon steel. Consequently, a liner plate 100 is welded to the under side of the bonnet flange and a stainless steel gasket 102 is secured around the flange 92 with O-rings 104, 166 being provided to seal between the flange and the bonnet plate. Because the inner surfaces are exposed to heat, a coolant such as water is desirably introduced through inlet pipe and circulated through an elongated tubing 112 extending around the gasket 102.111 order to cool the seals 104, 106.to prevent deterioration thereof.

Additionally, a thin metal 114 may be welded at 116 at spaced intervals to the. liner sheet 100 and expanded as previously described in order to provide a conduit for circulation of cooling fluidto assist in cooling both the seals 1'04 and those seals 117, 118, that seal around the stem 34 and bearing member 120. I 1

While this invention has been described inconnection with preferred embodiment thereof, it is to be understood that modifications and changes therein maybe made by those skilled in the art without departing from the spirit and scope of this invention which is defined by the claims appended hereto.

Having described my invention I claim:

1. In a vacuum system, a cryogenic chamber for conneetion between a vacuum source and a chamber to be evacuated for settling out vapor molecules or the like, said cryogenic chamber comprising:

a series of walls joined to form a duct for the flow therethrough of fluid from the chamber to be evacuated to the vacuum source,

at least one panel disposed transversely across said duct with a first side thereof facing upstream,

said panel comprising a relatively smooth sheet forming said first side and a second sheet coextensive therewith on the downstream side thereof,

said sheets being secured together face to face at spaced points in a fixed pattern over the surfaces thereof and said second sheet being buckled outward immediate said spaced points to provide a flow conduit between said sheets, duct means connected to said panel for delivering a cryogenic fiuid to and from said flow conduit, and a plurality of clip members in ,said duct loosely supporting the edges of said panel while permitting expansion and contraction thereof.

2. The combination defined by claim 1 wherein:

at least one of said duct-forming walls is formed by inner and outer sheets secured together at spaced points in a fixed pattern over the surfaces thereof,

said inner sheet having a relatively smooth, regular surface and said outer sheet being buckled outward intermediate said spaced points to provide flow conduits between said inner and outer sheets, and

conduit means connected to said wall for conducting a cryogenic fluid to and from said flow conduits.

3. In a vacuum system, a cryogenic chamber for connection between a vacuum source and a chamber to be evacuated for settling out vapor molecules or the like, said cryogenic chamber comprising:

a series of walls joined to form a duct for the flow therethrough of fluid from the chamber to be evacuated to the vacuum source,

insulating means surrounding said duct for insulating the same,

at least one of said walls comprising inner and outer sheets secured together in face to face relationship at spaced points arranged in a fixed pattern over the surfaces thereof,

said inner sheet comprising a relatively smooth, regular surface and said outer sheet being buckled outward intermediate spaced points to provide flow conduits between said sheets, at least one panel disposed transversely across said duct and formed With a flow conduit therein,

conduit means connected to said one Wall and to said panel for conducting a cryogenic fluid to and from said flow conduits,

and a plurality of clip members in said duct loosely supporting the edges of said panel While permitting expansion and contraction thereof.

References Cited by the Examiner UNITED STATES PATENTS Schmidt 165-143 Muffiy 29-1573 Smith 165-145 Moore 165-75 Schoellerman 29-1573 Neel et a1. 29-1573 Grenell 29-1573 Burtt et a1. 165-166 Piva 285-183 Kuehl 165-166 Abramson 211-172 ROBERT A. OLEARY, Primary Examiner.

CHARLES SUKALO, Examiner.

Claims (1)

1. IN A VACUUM SYSTEM, A CRYOGENIC CHAMBER FOR CONNECTION BETWEEN A VACUUM SOURCE AND A CHAMBER TO BE EVACUATED FOR SETTLING OUT VAPOR MOLECULES OR THE LIKE, SAID CRYOGENIC CHAMBER COMPRISING: A SERIES OF WALLS JOINED TO FORM A DUCT FOR THE FLOW THERETHROUGH OF FLUID FROM THE CHAMBER TO BE EVACUATED TO THE VACUUM SOURCE, AT LEAST ONE PANEL DISPOSED TRANSVERSELY ACROSS SAID DUCT WITH A FIRST SIDE THEREOF FACING UPSTREAM, SAID PANEL COMPRISING A RELATIVELY SMOOTH SHEET FORMING SAID FIRST SIDE AND A SECOND SHEET COEXTENSIVE THEREWITH ON THE DOWNSTREAM SIDE THEREOF, SAID SHEETS BEING SECURED TOGETHER FACE TO FACE AT SPACED POINTS IN A FIXED PATTERN OVER THE SURFACES THEREOF AND SAID SECOND SHEET BENG BUCKLED OUTWARD IMMEDIATE SAID SPACED POINTS TO PROVIDE A FLOW CONDUIT BETWEEN SAID SHEETS, DUCT MEANS CONNECTED TO

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