US2931631A - Mechanical seal assembly and method of operation - Google Patents

Description

April 5, 1960 E. s. HARRISON 2,931,631

MECHANICAL SEAL ASSEMBLY AND METHOD oF OPERATION Filed Oct. 28, k1954 4 Sheets-Sheet 1 1N VEN TOR. EDM/AED 5. #AEE/60N ATTORNEYS April 5, 1960 E. s. HARRISON 2,931,631

MECHANICAL SEAL ASSEMBLY AND METHOD OF OPERATION Filed om. 2a, 1954 4 sheets-sheet 2 INVENTOR. Dn/ABD s, HABE/50N BY P/CHE); WA rr's, @D ro/v e M NENNY NAI A TTOENEYS April 5, 1960 E. s. HARRISON 2,931,631

MECHANICAL SEAL ASSEMBLY AND METHOD 0E OPERATION Filed oct. 28, 1954 4 sheets-sheet s INVENTOR. DMLPD 5. HAze/SQN April 5, 1960 E. s. HARRISON 2,931,631

MECHANICAL SEAL ASSEMBLY AND METHOD oF OPERATION Filed Oct. 28, 1954 4 Sheets-Sheet 4 INVENTOR. D14/AED S. HABE/30N BY E/CHE); WA 771s, kaer e MWENNY MECHANICAL SEAL ASSEMBLY AND METHOD QF OPERATIQN Edward S. Harrison, La Grange, Ohio, assigner to rEhe liYfarller Co., Rochester, vN.Y. a corporation of New or A Y.

Application October 28, 1954, Serial No. 465,390 s Clarins. (ci. 257-7305) The present invention relates to the heat exchange art and is more particularly concerned with unique apparatus for use in controlling rthe temperatureof a liquid, for example a liquid in a mechanical seal. l

In general, in the operation of any mechanical seal, -it is necessary to maintain a uid at the seal faces. For high-pressurel and high-temperature operation of any reactor .or autoclave with Va double mechanical seal assembly, it is generally necessaryto maintain the seal chamber duid at a pressure substantially'above the reactor pressure lbutwata temperature not in excess of about '2502 F. In the past, it has been the general practice, in meeting these requirements, to provide a circulating `liquid with a reseryoirfand a pump being used to keep the sealing 'liquid moving through the seal chamber at a suicie'nt irate that .the temperature of the liquid `will not exceedva predetermined limit regardless of reactor 4temperature 4and `the temperature of the adjacent and surrounding elements of the seal assembly. This .practice, however, is not satisfactory from the standpoint of the initial equipment cost Vand the costs of operation and maintenance. In (addition, this ,type of equipment is not flexible enough 4for adaptation generally and accordingly custom building of the yunits has become general practice. l

Inaccordance with our present invention, the foregoing diiculties and shortcomings of the prior art have been completely 4eliminated or materially diminished and additional important advantages are obtained. T-hus,`the pump unit, `which was always heretofore essential, is not vrequired :in `the apparatus and method `of `this invention.

Consequently, the ,cost of the .pump and the attending cost l,of installation; including wiring of Vthe pump motor and plumbing of the pump system, have herebybeen eliminated. Furthermore, the various apparatus and as'- se-mblies of .this im/ention can be `used without special adaptation or modification in a wide variety'of mechan- -ical seal systems. AStill further, `there is an almost unlimited .variety of uids which can be usedto effect seal- -ing in accordance `with .the present method and apparatus and no consideration need be given v.the problem of selecting a particular ,fluid Aon the basis of .pump requirements or ,similar problems. In addition, because there are no moving parts inthe apparatus of this invention .for causing the ',uid to circulate in the system and because this v apparatus depends .upon .no outside power source ,for .maintaining sealpressure, there is no likeli-l hood of the Idanger of failure in use. Also, there is no possibility, in accordance with this invention, of a y'large amount of sealing fluid Yentering a reactor, the amount .of uid used .being ,limited lto .a relatively ,small quantity .suicient merely `to .producethe circulating effects essential to proper sealing.

i' arent Our .present invention is, toa large degree, predicated ,upon our discovery that under certain circumstances, a .fluid .suitable lforiuse ,in mechanical seal assemblies may be caused .to ,circulate in a natural way and this circulation .continuous yand substantially uniform ,over

section, of an assemblyv including a reactor vessel equipped Awithan agitator and a rotary seal;

Patented Apr, 5, i960 videthe temperature control over the uid necessary` to assure the sealing effects desired. This invention is also based upon our discovery that such circulation of the seal uid will not be signiiicantly effected adversely by changes in pressure upon the fluid.

Briefly, the method of this invention comprises the steps of'circulatiug a iiuid through a circuit which includes a seal housing and a fluid reservoir and establishing and maintaining a pressure on uid in the reservoir substantially above the pressure to besealed and 'thereby establishing and maintaining substantially the same elevated pressure upon fluid within the seal housing throughout the period of operation of the seal.

In accordance with a preferred practice of this invention, the fluid is circulated through a circuit in a closed system. However, i-t will be understood that the system may be open to the atmosphere under certain circumstancesv throughout lthe period of operation. lf, for eX- amp-le, the reactor is being operated under a partial vacuum, the method and apparatus of this invention will be effective to establish and maintain the desired mechanical seal although operating under substantially normal atmospheric pressure. ln any event, however, in the preferred practice of this invention the pressure to which the sealing liquid is subject throughout the sealing period will be between about ten pounds per square inch and `about l0() pounds per square inch greater than the pressure of the system to be sealed. Generally, for practicalV purposes, a pressure difference of about 25 pounds per square inch will be found satisfactory.

When the present method is carried out in a closed system, the object in accordance with our preference, is primarily to impose an elevated pressure upon the sealing fluid throughout the system and particularly at Vthe seal faces. This may be accomplished by substantially diminishing the volume of the system While maintaining substantially constant the amount of fluid in the system. Alternatively, this result is obtained by substantially increasing the amount of fluid in the system while maintaining the system volume substantially constant. In any event, by the nature of the present method and apparatus, it will be understood that whatever method is used for elevating pressure of the fluid, an increase of pressure upon any portion of the uid will be uniformly distributed `throughout the fluid and it is thus possible to regulate over wide ranges and within narrow limits, .the pressure of the uid at the kcritical seal face locations by means operating directly only at ther'emotest end of the apparatus from that location.

Ordinarily, the uidernployed for actual sealing will be a' liquid, but a liquid and gas will be contained in `the reservoir of the system, while only liquid will be present in the seal housing. The gas may be acted on directly or indirectly for the purpose of adjusting and maintaining pressure of the iiuid. Also, the gas may serve as a cushion against shocksin the system and thus operate as a safety device. Still further, the gas may be selected for specific chemical effects which it may lexert upon the liquid for purposes of corrosion resistance such as inhibition of autocatalytic decomposition. v'On yconsideration ofthe following detailed description, read in conjunction with the following drawings, accomfpanying and forming a part of the specification, those skilled in the art will gain va better understanding of the method and apparatus aspects ofv our present invention andthe important advantages of which it holds over the priorart.

In the drawings:

Fig. 1 is a fragmentary, elevational view, partly in asian Fig. 2 is an elevational view, partly in section, of an assembly including the rotary seal of Fig. l and an aplfnaratus embodying the present invention in a preferred orm;

Fig. 3 is a view similar to Fig. 2 showing another form of apparatus of this invention;

Fig. 4 is a fragmentary, enlarged sectional view of a portion of the pressure-regulating sub-assembly of the Fig. 3 apparatus; and,

Fig. 5 is an elevational view, partly in section, of still another form of apparatus of this invention.

As indicated in the drawings, apparatus of this invention generally comprises a vessel to contain a liuid, an inlet port in the vessel, an outlet port in alower portion of the vessel, and means consisting essentially of tubes for separately connecting the inlet and outlet ports to a mechanical seal housing for free circulation of the fluid between the vessel and the housing.

The apparatus of this invention illustrated in Fig. 1, is applied to and used with equipment commonly employed in the chemical industry including an autoclavetype reactor vessel V which has a flanged nozzle formed at its top to receive an agitator shaft 12. Nozzle 10 and shaft 12 are sealed in accordance with this invention for maintenance of any desired pressure within the reactor by means of a seal assembly S and the associated equipment shown in Figs. 2, 3 or 5.

Assembly S comprises an outer shell or housing 15 in the form of a generally cylindrical body open at its ends to receive shaft 12 and provided with anges 16 and 17 having a plurality of transverse openings for registry with apertures in a drive bearing 19 and an annular ring 20. By means of a plurality of bolts 21 and 22, housing 15 is securely fastened to bearing 19 and vessel V. An annular ceramic seat 27 disposed in housing 15 bears upon a sealing ring assembly 29 which is deformed by pressure exerted in drawing up ring to produce a gas-tight seal between assembly S and vessel V.

A reduced diameter portion 31 of bearing-19 extends downwardly within the upper end of housing 15 closing the housing at its upper end. Thus, an annular chamber 33 is defined within the shell of assembly S, surrounding shaft 12 and extending from adjacent to the upper end of the housing to adjacent its lower end. To provide fluid coolant for parts to be disposed within chamber 33, an inlet passageway 35 is formed in a portion of housing 15 adjacent to liange 17 and an outlet passageway 36 is formed in upper flange 16. For convenience in making conduit connections to these passageways, screw threads are formed in their external openings.

The lower end of chamber 33 is sealed against escape of fluid into vessel V and vessel V is likewise sealed against loss of liuid around shaft 12 by means of an annular, wedge-shaped Teflon body 40 and a carbon ring 41 having a tapered end for engagement with wedge 40 which is held in place against an abutment wall 42 formed on the agitator shaft and extending radially outwardly therefrom. A spring assembly including a compression spring 45 in a metal cage 46 carried by shaft 12 constantly resiliently urges ring 41 into firm engagement with wedge 40, holding the wedge in sealing position against abutment 42.

The upper end of seal chamber 33 is sealed by similar means including a wedge body 48, a carbon ring 49, an abutment wall 51 and a spring assembly. Ring 49 is of slightly different physical form in order to provide firm anchorage against a stationary annular seat 53 situated within the lower end of the drive bearing. CarbonV ring 41 derives its support from ceramic seat 27 bearing against the upper surface portion thereof.

The apparatus of this invention illustrated in Fig. 2 in operative relation to seal housing S comprises an elongated, generally cylindrical or tubular vessel 55, the lower end of which is closed by means of a metal plate or disc 56 which is welded to the vessel. The upper 'end of the cylinder has welded Huid-tightly secured to it a dome-like body 58 of enlarged inside diameter which is sealed except for communication with the cylinder. A standpipe 59 is disposed within the cylinder extending upwardly through an opening in plate 56 to a point well above the mid-section of vessel 55. The upper end of standpipe 59 is open and while it is fluid-tightly secured in place to the bottom plate, pipe 59 extends therethrough and opens into a coupling 61 which in turn leads into a tube 62, an elbow 64 and another tube 65, which communicates with seal chamber 33 through outlet passageway 36. A coil 70 of tubing of substantially reduced diameter is disposed within vessel 55 around standpipe 59 from which it is spaced. Coil 70 has an upper end Vportion 71 which extends outwardly to an opening provided for that purpose in the upper end portion of vessel 55 and has a lower end portion 72 which extends downwardly through an opening in plate 56 likewise provided for this purpose. Where it enters the vessel, the coil is gas-tightly secured to the vessel to prevent leakage during the operation of the apparatus of this invention.

In the side wall of the cylindrical vessel near the lower end thereof, an outlet port 75 is provided to permit ow of uid from the vessel to seal chamber 33 by means of a conduit assembly 77 fluid-tightly connected to the vessel and to seal assembly S in which it communicates with passageway 35.

In the upper portion of the vessel, an inlet opening 80 is provided and a conduit 81 is connected to the vessel wall Huid-tightly in communication with this opening for filling the vessel with heat exchange fiuid to be used in maintaining the desired temperature in chamber 33 and in maintaining the desired seal throughout the period of use of the reactor vessel. A valve 83 is provided to close fluid tightly the inlet conduit during operation of this apparatus.

Above opening 80, an aperture 85 is formed in the vessel wall and a needle valve 86 and a pressure gauge 87 are connected to the vessel by means of a pipe assembly 89 fluid-tightly welded to the vessel for communication with the vessel chamber to enable detection and regula.- tion of fluid pressure in the vessels.

For the purpose of regulating pressure in the vessel chamber and for adding make-up amounts of heat exchange liquid, an Alemite gun 90 is disposed adjacent to the vessel and held in position by means of supporting bars 92 welded to the vessel and to the gun cylinder. A tube 94 of reduced diameter connects gun 90 to vessel 55 through an opening provided for this purpose near the bottom of the vessel. Manipulation of gun 90 in the usual manner results in the introduction of heat exchange liquid under pressure into vessel 55.

In operation of the apparatus of Fig. 2, a suitable heat Vexchange liquid is run into the vessel through valve 83,

pipe 81 and opening 80, needle valve 86 being open to permit free liow of liquid to approximately the desired level in the vessel. The needle valve and inlet control valve 83are closed when the desired amount of liquid has been charged into the system and gun 90 is operated to add still more liquid to the vessel, thereby increasing the gas pressure in the upper part of vessel 55 and dome 58 to a desired level, as lindicated by pressure gauge 87.

`Before reactor vessel V is brought up to operating temperature, the supply system serving the cooling coil 70 is started so that ow of coolant through the coil is begun in time to assure the desired heat exchangewith vessel liquid contents to produce the circulating flow characteristic of the novel method of this invention. With the system brought to this stage, no minor attentionis rcquired of the operator during the period of reactor operation and sealing of the reactor around the agitator shaft is assured throughout the period of operation, assuming the selection of a heat exchange liquid meeting the requirements of the service. In other words, no moving parts, such as pumps or the like, are required to maintain the desired liquid sealing' pressure in the sealing chamber" orf tonantaii' tlie desired` temperte in the liquid effecting this seal throughout" the period of operation of the reactor dueto the vc'vontinu, Substantial circulation resulting from the thermal"differentialv between liquid entering passageway 35 anddiquid' leavingcliamber 33 through passageway 36;v j l j With referenceto Figs. 3- and 4',:thealternative."l form of apparatus of this'invention therein; illustratedl cornprises an elongated cylindricalve'ss'el 98 similar to; vessel 55, having an endV plate 99V closing' its lower end.` An inlet opening is provided in said plate for receipt of; a standpipe 101 which extends upvi/arcl'ly'L to near thetop of the vessel. An outlet opening 1035 is' provided in the side wall of the vessel adjacentV toitslower end aridfby means of conduit assemblies^104^and-1`tl5, standpipeiltll and outlet opening 103 are ciiected to passages 36 and 35, respectively, for' circulatioii of sealing liquida between vessel 98 and seal assembly Siin the manner generally described above irirefeieiice to Fig. 2.

The upperl end portion of thevessel' 98 is'clsedf by means of a metal plug 110 which is'welded ti'- the: top of the vessel and providedwith'aceritral bre 111 to receive a plunger or piston 113 for maintaining predetermined pressure in vessel 98. A bracket 11S comprising a metal bar is welded to the outer side of plug 110 and extends upwardly from the plug to support pivotally a lever 116 which is connected to an upward extension of piston 113. The free end of lever 116 is maintained in place during operation of the apparatus of this invention by means of a Weight 117 which is connected by means of a chain 11S to the lever through an opening provided for the purpose in the said free end of the lever. formed on the upper end of the plug, an upstanding portion of predetermined length such that lever 116, when in the down position, is supported against weight 117 in a substantially horizontal position with piston r113 in its advanced or down position.

A cooling coil 120 of reduced diameter tubing, like coil 70 of Fig. 2, is disposed within vessel 93 surrounding standpipe 161 and spaced therefrom. Lower end 121 of the coil is run out through bottom wall 99 of the cylinder to which it is fluid-tightly connected for communication with a supply of cooling water (not shown). Upper end 122 ofcoil 120 is run out through the top Diametrically opposed to bracket 115, there is of the assembly through an opening provided in plug and it is similarly secured thereto gas-tightly to prevent ioss of pressure in the Vvessel during operation. This coil outlet line communicates suitably with a drain (not shown).

An aperture 125 is located in the upper portion of the vessel for connection of apressure gauge V127 to the vessel interior through a pipe 128 duid-tightly attached to the outside of the said vessel.

Alemite-type grease gun 130 is supportedby cylinder 98 in a position adjacent thereto by means of suspension bars 131 which are welded to the vessel and the cylindrical portion of the gun. Gun 1.3i) communicates with vessel 98 through tube 133 and an opening 134 in the lower portion of the vessel. The gun also communicates .with the vessel through a tube 135 and a passageway 136 formed in plug 110 above the mid-section of the plug.

The apparatus illustrated in Figs. 3 and 4 is used to establish and maintain the desired sealing pressure and the desired temperature in the sealing chamber by irst charging into vessel 98, the desired amount of suitable sealing liquid. Filling of the vessel is accomplished by removing piston 113 from plug 110 and charging the liquid into the vessel through plug bore 111. When the level of the liquid in the vessel reaches the desired point, piston 113 is replaced in its bore and weight 117 is connected to lever 116 so that the piston is moved into Vits advanced position. Gun 1311 is then operated to bring the pressure in vessel 98 to the desired level as indicated origaugel 127 i andv flow ofcooling- Watev thrciughcoil 120 isv begun. Circulation` of theY sealing liquid` through" seal chamber 33 and vessel 98V and the linescbnnecting thm begins as soon astlie temperature differential betweenthe liquid in inletl and" outlet passageways 35 and 36 is'suificient to produce thisl effect. This circulationwill coni tinue, as those skilledin' the art will understand, throughout the operating period' so long as i't is necessary to elec'tcooling withinY the seal chamber.

The assembly of Figs. 3 and 4 has a special feature, in that there is a safety release'built'into the assembly i so that pressure inthe vessel cannot exceeda certain pre- -determined limit which is sufficient to cause motion of the piston` away from its advanced position sufiiciently tofl uncover port 136; Accordingly, the pistonand lever 116 and weight 117 may be desired with respect to each other and to the pressure" vessel and' with regard t'o the temperatures and vapor pressures to be `carried irivessel '98' so'that emergency release may be automatically` accomplished to insure against dain'age resulting from exfces'sive pressure developing anywhere in this vessel-sealing assembly system.

The apparatus shown in Fig. 5 comprises a cylindrical vessel 140 which is closed at its lower end by a plate 141 provided with a central opening to receive a standpipe 142 generally as described above. An outlet opening 144 is provided near the lower end of the vessel and as in the foregoing embodiments of thisY invention, the inlet and outlet openings are served by suitable conduit means 147 and 148 for connection to seal assembly S.

A jacket 150 is provided on vessel 140 forcooling uid to exert a heat exchange eiiect on the liquid of the seal system contained in the said vessel and in standpipe 142. Cooling tluid is introduced into jacket 150 through inlet port 151 and is discharged through outlet port 152.

It will be understood that this Fig. 5 device is not intended to be operated under superatmospheric pressure and is therefore designed especially for use with rotary seal assemblies or reactors to be operated under vacuum. The circulation of cooling liquid to maintain the desired temperature within chamber 33 will begin and continue in this apparatus substantially as described above in reference to the other devices of this invention herein illustrated. A

Having thus described the present invention so thatl those skilled in the art may be able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

1. Heat exchange apparatus which comprises a vessel to contain a fluid under pressure and having an outlet port in its lower portion and inlet port in the vessel above the outlet port, means comprisingtubes for separately connecting the inlet and outlet ports to a liquid reservoir below the vessel, means for causing circulation ofliquid through said vessel including means in said vessel between its inlet and outlet ports for cooling said liquid, and means for increasing the pressure on liquid in the vessel.

2. Heat exchange apparatus which comprises a vessel to contain a uid under l pressure and having an outlet port in its lower portion and inlet port in the i, vessel above the outlet port, means comprising tubes for liquid, and means associated with said vessel for diminishing the volume of said vessel and thereby increasing the pressure on liquid in the vessel.

3. Heat` exchange apparatus which comprises a vessel to contain a uid under pressure and having an outlet port in its lower portion and inlet port in the vessel above the outlet port, means comprising tubes for separately connecting the inlet and outlet ports to a liquid reservoir below the vessel, means for causing circulation of liquid through said vessel including means in said vessel between its inlet and outlet ports for cooling said liquid, and means comprising a source of uid under pressure communicating with the interior of the vessel for increasing the fluid pressure on liquid in said vessel.

4. Heat exchange apparatus which comprises a vessel to contain a Huid under pressure and having an outlet port in its lower portion, a standpipe in the vessel and having an open ,end above the outlet port, means comprising tubes for separately connecting the standpipe and the outlet port to a liquidreservoir below thevessel,v

means for causing circulation of liquid through said vessel including a coil in said vessel about said standpipe for conducting cooling fluid through liquid in the vessel, and means for introducing fluid under pressure into the vessel and thereby increasing the pressure on the liquid in the vessel.

5. The combination of elements set forth in claim 4 in which the means for introducing fluid under pressure Ainto the vessel include a tube opening into the interior of said standpipe.

References Cited in the le of this patent UNITED STATES PATENTS Stitzel Aug. 4, 1885 Short Aug. 5, 1902 McClellan Oct. 10, 1916 Meyer Mar. 10, 1931 La Bour Dec. 24, 1940 Fairlie et al. Nov. 11, 1941 Wincman Dec. 26, 1944 Anderson Aug. 14, 1945 Roshong Dec. 16, 1947 Fausek May 24, 1949 Voytech Feb. 17, 1953 Skillman Aug. 18, 1953 Weedman May 22, 1956 Brumagim May 27, 1958 FOREIGN PATENTS Great Britain Apr. 24, 1930 Great Britain July 10, 1945 Great Britain Apr. 25, 1951

Images