CA1124185A - Permeator apparatus - Google Patents

Abstract

PERMEATOR APPARATUS

ABSTRACT OF THE DISCLOSURE
An end closure is disclosed wherein a single end closure cap can be in a fluid-tight relationship with both an external container and at least one internal container. The at least one internal container is moveably positioned within the external container, and a resilient means cooperates between the internal container and the external container such that the internal container contacts the end closure cap to provide the desired fluid-tight relationship. A particularly attractive use of the end closure is to provide permeators containing hollow fiber membranes suitable for the selective permeation of at least one fluid in a fluid mixture in which the tube sheet is in a fluid-tight relationship in the permeator such that fluid communication between the shell side and bore side of the hollow fiber membranes is only through the walls of the hollow fibers. In these permeators, a resilient means cooperates between a tubular shell containing the hollow fiber membranes and at least one tube sheet through which bores of the hollow fiber membranes communicate wherein a force directing the tube sheet longitudinally outward from the shell is provided. An end closure cap is adapted to be removably fastened to the end of the shell proximate to the tube sheet. A first sealing means is positioned between the end closure cap and the shell to provide an essentially fluid-tight relationship, and a second sealing means is positioned between the end closure cap and the tube sheet wherein the resilient means provides a sufficient force on the tube sheet that the second sealing means provides an essentially fluid-tight seal.

Description

07-52-0418~
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This invent~on pertains to end closures and also ~o apparatus for separating at least one :Eluid ~om a fluid mixture containing at least one other componen~ by se:lec~ive permea~ion of the at least on~ fluid through membralles which S apparatus u~ilize n end closure o~ ~his invention, More advantageously, ~his invention relates to improved separa~lon apparatus utilizing hollow fiber membranes in which ~he hollow fiber membranes are embedded in a tube sh et and t~e bores of t~e hollow i~ers ex~end in a fluid co~muni~ation ralationship through the tu~e sheet.
Th~ use of membranes for separating at leas~ one 1uid from a fluid mixture containing at leask one other component has long ~een suggested. In these membrane separations, permeable fluids in t~e fluid mixture (feed mixture) pass, lS under the Influence of a driving force such as concen~ration, par~ial pressure/ total pressure, etc,, Cdepending on the nature o the membrane separation. operationa from a feed side of the membrane to a permea~e exit side of the mem~ran~. The 1uid may pass t~rough the mem~rane ~ interactioII with the 20 material of the mem~rane or by flow in the interstices or pores presen~ in th~ mem~ran~ Separa~ions e:Efected by mem~ranes can include gas-gas, gas~liquid, and lîquid-lîquid (includLing liquid~dissol~Ted solids~ eeparations.
The ~iabilit~ o~ ~e use of m~branes for ~luid separatîons as compared to other separation procedures such a~ a~sorptîon, adsorption, dis~illation, and liquifaction of~en depends upon ~e cost (including installation and operat~ng cos~ of the apparatus for conducting separatîon procedure, the degree of selec~ivity o separation whieh i5 desired, the total pressure losses caused ~ such apparatus whic~ can ~e tolerated, the useful life of such apparatus, and f~

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the siz~ and ease o~ use of such apparatus. Film membranes may frequently not be as attractive as other separation apparatus due to the need for film membranes to be supported to wl~hstand operating conditions and ~he o~erall complexi~y of apparatus containing ~ membranes, Membranes in the oonfiguxation of hollow ibers, or ~ollow filaments, may overcome som~ of the deficiencles of film membran~s for many ~eparation nperation~ in that the hollow ibers are generally self-supporting, aven during operating conditions, and provide a greater amount of m~mbrane surface area per unit volume of separatîon apparatus than that which may be provlded by fi~m - membranes. Thus, separation apparatus oontaining hollow fibers may be attractive from the standpoint of convenience and size and reduced complexity of design.
Separation apparatus (permeators~ utiliæing hollow fiber membranes general~y comprise an essentially 1uid impermeable tubular shell containing a plural;ty of hollow fibers which ma~ ~e arranged in one or more ~undles. In order to separate the ex~eriox side of the hollow ibers Cshell side~ from the bore side of the ~ollow fi~ers SllC~ t~at t~ onl~ fluid communication across the walls of the hollow fi~ers is through the wall~ of the hollow i~ers which walls effect the desired separation, the hollow fi~ers are generally embedded in an essen~all~ ~luid ~mpermea~l~ tu~je s~eet in which essentially onl~ the ~ores o~ t~e hollow fibers extend ~roug~ the tu~e s~eet In a ~luid communica~ion relations~ip. W~ile the ~ollow fibers may ~e em~edded in th~ material of thQ tu~e sheet in an essentially fluid~tig~t manner, it is also necessary that the.
tube she~t ~e in an essentially fluid-tight relationship in the permea~or such that fluid does no~ paæs between the shell side and bore side o the hollow fi~ers except by passage through the walls of th~ ~ollow fi~ers, Even small leakage3 around the tube sheet can have serious efects on the perror~ance of the permeator.
Most advantageously, the tube sheet and bundle assembly should be capable of being acilel~ installed and removed ~rom the shell. In man~ instancest especially for permeators ~3~ 07-52-0418A

utilized to separate fluids at high pressur2s, the shell represen~s a significant capital expenditure and thus is pr~ferably capable o being re-used upon expiration of the use~ul life of the hollow fiber membxanes, Accordingly, the S tube shae~ and bundle assembly should be eapable of being quickly and easily r~moved from the permeator, and the new tube sheet and bundle assembly ~hould be capable of being readily ins~alled in a shell without difficulties in obtaining -the desired fluid-tight relation~hip o the tube sheet in ~he permeator.
One of the often disclosed means for providing the desired fluid-tight relationship between the tube sheet and the shell involves the use of O-rings which surround the tube shee~ and are positioned ~etween the tu~e sheet and the interior surfa~e of the she:Ll. The use of such O-rings are disclosed, for instance, by McLain in United States patent 3,422,008;
MacN~mara, et al ., in United States patent 3,702,658; and Clark in United S~ates patent 4,061,574. The presence of 0-rings between the si~e of the tube sheet and the in~erior 20 side o tEle shell can provide undue difficulties in the in~ertion and removal of the tub~3 sheet and hollow fiber membrane assembly ~rom the shell4 Moreover, the interior surface of the shell and the lateral surface o the tu~e sheet must be machined to sufficiently close tolerances such that the desired fluid-tight relationship can be achieved.
Furthermore,.since the achievemen~ of the fluid tigh~
relationshlp may be dependent upon close tolerancing~
unavoidable differentials in expansions of t~e tube sheet and s~ell, e.g., ~ue to changes in t~mperature, swelling age~ts in the fluids being processed, etc., may resul~ in substantial difficulties, By this in~ention permeators containing hollow fiber membranes and utilizing essentially fluid impermea~le tube sheets are provided wherein subs~antially the only fluid communi~ation between the shell side and bore side of the hollow fiber membranes is through the walls of the hollow fibers, Advantageously, the permeators of this inYention _4_ 07-52-0418A

can permi~ facile ins~allation and removal (including replac~ment) o ~he tube sheet and hollow ~iber me~brane asqembly. Moreover, the advantages provided by ~his in~ention can be obtained without undue machining of the interior surface of the shell or the tube sheet, yet an essentially fluid-tight relationship can be ob~ained. The permeators of this in~ention axe able to ~mploy high pressure di~feren~ials between the shell and the bore sides o the hollow fiber membranes. Furthermore; all sealing members can be readily 10 exposed such that ~perfections, dirt, or other debris which ma~ adversely affect the fluid-tight relationship can be easily obviated~ Additionally, differentials in expansions of the tube sheet or shell can be tolerated without deleterious effect to the fluid-tigh~ relationship, even when the expansions occur during use o~ the permeator. The highly desirable benefits provided by the permeators of this in~ention can readily be achieved withsut undue fabrication effort~, and in many instances, the fabrication of the permeators of thi~
inven~on may be acllitated as compared to previously suggested pe~meator designs, While substa1ntial ad~antages with respect to penmeators are provided by th:is invention/ it is clear tha~
other ~pparatu~ comprising an c2ternal container and a~ least one inter~al container, e.g,, tube-in-shell ~eat exchangers, vessels holding two separate flu:ids , etc ., can also be 25 significantly bene~ited.
An apparatus comprising an end closure of this iIlvell~ior comprises an external container having a~ least one opening;
an end closure cap removably fastened to and covering a said opening of the external container in a fluid-tight rela~ionship;
at least one intern~l container having a~ least one opening, a said internal container being positioned within said external ontainer with the internal container being adapted to contact said end closure cap to cover a said opening o the internal container; and at leas~ one resilient means cooperating between the external container and a said internal container to provide a suficient force on a said internal container to provide an essentially fluid-tight relationship between the end closure cap and a said internal container.

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In an aspect of this invention, a permeator comprises an elongated tubular shell having at least one open end; an essentially fluid impermeable end closure cap removably fastened ~o and covering said elongated tubular shell at said open end, said end closure cap having at least one 1uid communication port; a plurality of hollow fiber~, whîch hollow fibers exhibi~ selectivity to the p~rmeatlon of at least one fluid in a fluid mixture co~taining at least one other component, said ~ollow fibers being generally parallel and extending longitudinally ~o form at least one bundle in the elongated tubular shell; an essentially ~luid-impermeable tube sheet having an outside face wherein the hollow ~ibers in said at least one bundle are embedded in the tube sheet such that ~he boxes of the ho~low fibers provide ~luid communication throu~h the tube sheet, wherein said outside face extends later lLy beyond the periphery of said at least one bundle ~mbedded in the tube sheet and is proximate to the end closure cap; at lea6t one resilient member cooperatin~ be~ween the shell and tu~e sheet and being adapted to provide a force on ~he tube sheet, which force is generally directed longitudinally outward ~rom said open end of the shell to said end closure cap; a first sealîng means between the end closure cap and the shell which is adapted to provide an essentially fluid-tight seal ~etween the end closure cap and the shell; and a second sealing means between the end closure cap a~d the outside face of th~ tuge sheet, said second sealing means substantially suxrounding said at least one bundle embedded in said tube s~eet, wherein said a~ least one resilient m~mber provides sufficient force on the tube sheet such that said second 30 sealing means provides an essentially fluid-tight seal between t~e ou~side face of ~he tu~e sheet and the end closure cap.
Convenientl~, the fastening of the end closure cap ~o the shell can simultan~ously effect the fluid-tight relationship between the end closure cap and the shell as well ~s the end closure cap and the tu~e sheet.

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The permeator of this invention may be any suitable design for effec~ing fluid separations and ma~ ~e a single~
ended or double-ended permea~or. A single-ended permea~or has a tube sheet at only one end, and one or both ends o S the hollow fibers are embedded in the tube sheet. When only one e~d o~ each of the hollow fibers is em~edded in the tube shee~, the other end ~ust be plugged or othe~wise closed. In a double-ended module, a tube sheet is provided at each end of the shell and the hollow fibers may extend from one ~ube shee~
~, 10 to the other ~ube sheet, or the permea~ors may contain at least two distinct bundles of hollow ~ibers where a~ least one bundle extends into only one tube sheet. 0ne or both ~ube sheets of a double ended module may be in a fluid-tight relationship in accordance with this invention. The tubular qhell of the permeator may have any suitable cross-sec~ional configuration and suficient volume to provide a desired amount of membrane surface area in th~ permeator. Generally shells having a circular cro~s-section21 configuration ar employed because of their availa~ility, handling convenience9 and strength; however, shells of other cross-sec~ional configurations, e.g., rectangular, may be highly suitable for many permea~ors.
Often, shells hava a major cross~sectional dim~nsion of at least about 0.02, or preferably at least about 0~05 metar, say, up ~o about 1 or 2 or more meters, The length of the shell conta~n~ng th~ hollow fibers is frequ~ntly at least about 0.2 or 0.3, say, at least about 0.5, meter, up to 10 or more meters .
The permeator may be opera~ed in any desired manner9 e.g., the 1uid feed mixture may be introduced into the shell and initially contact the shell side of the hollow fibers, or it may ~e introduced into the ~ores of the hollow fibers. The flow pat~erns of fluid on the shell side of t~e hollow fibers may be primarily transverse to the longitudinal orientation of the hollow ~i~ers or may be primarily axial to the orientation of the hollow fibers. When the flow on the shell side of the hollow fibers is axial, it may ~e generally concurrent or countercurrent with the flow in the ~ores of the hollow fibers.

In an advan~ageous mode of operation of the permeator, the fluid feed mixture is introduced to the shell side of the hollow fibers. Since oten the fluid feed mixture is at a higher total pressur~ than the pressure o~ the permeating S fluid, the pressure diffexential from the shell side to bore side assists in maintaining the desired fluid~tight relationship between the tube sheet and the end closure cap. Also, ~his mode of operation can provide a safe~y ~Talve ~o protec~ the hollow fiber membranes. For example, if the shall side total 10 pressure were decreased without a decrease in bore side total pressure, a substantially higher pressure may exis~ inside the bores of the hollow fibers which could deleteriously af~ec~ the hollow fiber membranes. However, this higher pressuxe may be sufficient to force the tube sheet from its ~luid-tigh~ relationship with the end closure cap and thereby release the pressure on the bore side of the hollow fibers prior to any undue deleterious effects on the hollow fiber mem~ranes, The hollow fiber membranes may be fabricat d from any suitable synthe~ic o~ natural material suitable for fluid separations or as supports or ~aterials which effect the fluid separations. The sele~ion of the ma~erial for the hollow fiber may be based on heat resistance, ~hemical resistance, and/or mechanical stren~th of th~ hollow fibex 25 as well as other fac~ors dictated by the intended ~luid separatlon for which ~t will be used and thP operating conditions to which i~ will be subjected. The material for fonming the hollow fibers mRy be inorganic, organic or mixed inorganic and organic. TYPICa1 inorganic materials include glasses, ceramics, cermets, metals and the like. The orga~ic materials are uslaally polymers. The hollow :Eiber diameters may be selected over a wide range: however, the hollow iber should have suficient wall thickness to provide adequate ~trength to the hollow fiber. Frequently, the outside diameter of the hollow fiber is at least about 20, say, at least about 30 microns, and the same or di~ferent outside di~meter fibers may be con~ained in a bundle. Of~en, ~he outside diameter o~

'~r'~

the hollow fibers do not exceed about ~00 or 1000 microns since larger diameter hollow fibers may provide less desirable ratios of hollow fiber surface area pex unit volume of permeator. Preferably, the outside diameter of the hollow fibers is about 50 to 800 microns. Generally, the wall thickness of the hollow fibers is at least about 5 microns, and in some hollow fiberc, the wall thickness may be up to about 200 or 300 micron~, say, about 50 to 200 micron~. With hollow fibers fabricated f~om materials having lesser strength, it may be necessary to employ larger hollow fiber di~meters and wall thicknesses to impart sufficien~ strength to ~he hollow fiber. The walls of the hollow fibers may be essentially solid or may contain a substantial void volume. When voids are desired, the density of the hollow fiber can be essentially the same throughout its wall thickness, i.e., the hollow fiber is isotropic, or the hollow fiber can be characterized by having at least one relatively.dense region within its wall thickness in barrier flow relationship in the wall o~ ~he hollow ~iber, i.e., the hollow fi.ber ls anisotropic.
The hollow fibers are generaLlly parallelly arranged in the fonm of one or more bundlas i.n the shell. Ge~erally, at least about 10,000 and often substantially greater numbers, e.g,, up to 1 million or more hol.low fibers are ontained in a permea~or. T~e fibers in the bundle, for ins~ance, ma~.be relatively straight. or they may be spirally wound such as disclosed by McLain in ~nited Sta~es paten~ No. 3,422,008~
In many instances, a single bundle of hollow fibers employed i~ a permeator and al: least o~Le end of the hollow fibers in the bundle îs embedded in a ~ube sheet. The opposite end of the hollow fibers may be looped back, i.e,, the bundle is generally in a U shape, and embedded in the same tube sheet, or the opposite end o~ the hollow fibers may be plugged or embedded in another tube sheet. ~hen the hollow fibers in the bundle are in a "U" shape, the ends may be segmented sueh that diferent regions on the tube sheet contain each end of the hollow fibers. Each of these regions on a tube sheet can be maintained in an essentially fluid impermeable relationship 9 ~ 0 7 - 5 2 - 0 ~ 1 ~A

such that fluid communication between the regions can only occur by passage of flui.d through the bores of ~he hollow fibers.
The tube sheet containing at least one end of at least one bundle of hollow fibers may be in any suitable con~iguration for assembly in the permeator. Sufficient surface area should be provided on the outside face of the tube sheet which surface surrounds at least one bundle embedded in the tube ~heet, such that the sur~ace can receive a se~ling means and provlde an essentially fluld-tight contact with the sealing means.
Preferably, sufficient surface area is provided such that fluid communication with the bores of the hollow fibers in the bundle is substantially unhindered. For example, in a permeator containing a single bundle of hollow ~ibers having a generally circular ~ransverse cross-section, the tube sheet may have a generally circular cross-section with a larger diameter than that of the bundl2 such that a sealing means can contact the outside ~ace of ~he tube sheet without substantially blocking fluid ~om~unication to or from the bores of ~he ~mbedded hollow fibers. In permeators in which more than one bundle o hollow fibers extends through the tube sh~et, a sealing means may surrotmd all of the bundles at the outsîde face of the tube sheet, or a sealing means can extend around a portion of the bundles a~ the outside face. Frequently, the zone to be contacted by the sealing means is at least about 0`.005, e.g,, at least a~ut 0.01, meter in wid~h. The outside face may be continuous or non-continuous, i.e., the tube sheet sur~ace may be u~itary or the tu~e sheet may ha~e a separate lateral extension which can provide area for contact with the sealing means. 0 course any lateral extension which is in contact with the sealing mean~ should itself be in a fluid-tight relationship with the tube sheet. The outside face of the tube sheet may be substantially perpendicular to the orientation of the hollow fibers; however, it is clear that the ~enefits of this invention can be achieved utilizing outside faces which are, e.g., bevelled, curved, uneven (e.g. J indented, stepped, etc.) or the like. The hollow fibers -10~ 07-52-0418A

may extend through the outside ~ac~ of the tube sheet, or more frequently, the hollow ~i~ers are flush.wit~ th~ outside face of the tube sheet.
The tube sheet may extend at least partially into the shell, or, if desired, it may reside outside the shell at the open end. When the tube sheet is intended to at least partially be placed inside the shell, it is preferred that the cross sec~ional dimenslons of the ~ube sheet be suf~iciently less than the cross-seetional dimen~ions of the shell that the tube sheet can be slidea~ly positioned within t~e shell. Since a fluld-tight rPlationæhip need not exist between the interior of the shell and the la~eral wall of ~he ~ube sheet, close tolerancing of the d~mensinns of the shell and the tube sheet need not be provided. Hence, if the tube sheet needs to be severed to expose open hollow fiber bores, the severing operation can be conducted to provide desirable openness to the bores o~ the hollow fibers without undue concern to the dlmension of the tube sheet~ The tube sheet containing at least one end o at least one bu~dle o~ hollow ~ibers may be formed in any suitable manner, e,gO, ~y casting a potting m~terial around the end of the bundle such a~ disclosed in l~nited S~ates patent Nos.

3,339,341 (Maxwell, et al.) and 'i,442,389 (McLain3 or by impregnating the ends of the ibers with pott~ng material while assembling the hollow ~ibers to orm a bundle quch as disclosed in United States patent Nos. 3,455,460 (Mahon) and 3,690,46S
(~cGin~is, et al.).
Suitable pot~ing ma~erials include set~able liquid polymerie compositions Csuch as epoxies, urethanes, etc.) J solders, c~ments, waxes and the like. The thickness of the tube sheet is generally sufficient to provide suitable strength for withstanding the ~otal pressure differentials to which the tube sheet may be su~jected in separation operations, Thus, the thickness employed may depend upon the strength of the potting material.
Also, the tube sheet should be sufficiently thick that ample contact is provided between the hollow fibers and the potting material such that they are in an essentially fluid-tight relationship, Often, tube sheets are at least about 0.01, e.g,, about 0.01 to 0.25 meter in thickness.

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At least one resilient member cooperates between the shell and the tube sheet ~o provide a force on the tube sheet generally directed longitudinally outward rom the open end of the shell and toward the end closure cap. The resilient member may, for example, be a spring, such as a coil spring, leaf spring, wa~e spring, metal strip sprin~, ball ~pring plunger, etc., or a resiliently deformable material such as 1exible plastics, and the like. Sufficien~ force is prefexably generated ~y the resilient member that the second sealing means -. 10 posi~ioned ~etween the outside face of the tube sheet and the end closure cap can provide an esse~tially fluid-~ight relation-ship between the end closure and ~he outside ~a~-e of the tube sheet under expected operating conditions, In many instances, the resilient means generates a pressure of at least about 5, more frequently at least about 10, or even 100 or more, kilograms per square centimeter on the second sealing means. Preferably, the shelI side o the hollow fibers is at a higher ~otal pressure than ~he total pressure on the bore side of th~ hollow ibers.
Thu~ ~he total pressure differenti 1 acxoss the tube sheet can assist in providing the essentia~ly fluid-tight relationship between the tube eheet and end closure, Advantageously, the pressure generated by the resilient mean~ is below a pressure differential which could deleteriously affect the hollow fiber membrane when t~e hlgher pressure is on the bore side of the hollow fibers such that a safety valve can be provided by ~he end elosure structure.
The resilient mem~er cooperates betwee~ the shell and the tu~e sheet. Advantageously ~he resilien~ means has su~ficient flexi~ility that the desired fluid-tight seal can be maintained even though the dlmensions of, for instance, the second sealing means or ~he tube sheet or the shell may change over a period o~ t;me due to mechanical fatigue, deleterious effacts by constituents in t~e feed and/or permeate streams from the permea~or, ~emperature changes, and the like. Mo~eover, i~ is particularly desira~le that the resilient means has su~ficient resiliency such that the tube sheet need not be precisely machined to fit within the permeator. Accordingly, in a given permeator and in accordance with this invention, tube sheets having dimensions varying by, e,g,, up to several milli~eters or more, may be employed while still providing the desired force to pro~ide the fluid-tight contact. The resilient member may be in con~act with the interior of the shell or the surface at the open end of the shell. The point of contact of the resilient member with the shell may also be variable such that tube sheets having larger variations and dimensions can be accommodated. The resilient means may contact the tube sheet in any sui~able manner such that the desired forces on the tube sheet are provided. For ins~ance, the resilient mean~ may contact the inner face of the ~ube sheet or may contact a protrusion extending generally outward from the sides of the tube sheet. Preferably, ~he r~silient means is easily removed from the tube sheet such that replacement of the tube sheet and hollow fiber mPmbrane assembly is facilitated.
The first sealing means and the second sealing means may be composed of the same or different ma~erial and each may be in a sui~able con~iguration to~effect desired 1uid-tight relationship~. Often the sealing means are composed o~ natural or synthetic polymerlc material which may, i:E desired, contain organic or inorganic fillers. ~le material o~ the sealing means should be sufficiently inert to the fluids ~o which it may become contacted such that it i~ not deleteriously ef~ected during the separation operations. Preferably, the material o the sealing means has sufficient flexibility that a suitable fluid-~ight seal can be obtained even in the presence o minor ~mperfection~ in the surfaces to which it is eontacted.
Suitable sealing means thus often include gaskets, O-rings, and the like.
The end closure cap is adapted to be removably attached to the shell. A particularly convenient means for attachi~g the end closure to the shell includes the use of flanges attached by bolts. Advantageously, the first sealing means i~ positioned be~ween the shell and the end closure cap such that when the end closure cap is securely tightened ~o the shell a seal~ng contact is made by both the end closure cap and the shell wi~h the sealing means. Also, when the end closure cap is securely fastened to the shell, the resilient ~ 13- 07-52-0418 member provides sufficient force on the tube sheet that the second sealing means maintains an essentially fluid-tight seal between the outside face of the tube sheet and the end closure cap. It should be understood that the ~irst sealing means and the second sealin~ means may be composed of, e.g,, a single gaske~. One surface of the gasket partially contacts the shell and the other part of that surface of the gasket con~acts the outer ~ace o ~he ~ube sheet. O~ course, the ~xst sealing means and the sècond sealing means may be comprised of more than one, e,g., gasket or O-ring.

IN THE DRAWINGS:

FIGU~E 1 îs a schematic representation of a longitudinal cross-seetion o a permeator in accordance with this invention wherein the resîlient means is positioned at the open end of the shell.
.

FIGURE ~ is a schematic representation o~ a par~ial view : o~ a longitudinal cross-section of a permeator in accordance with this in~ention wherein the t:u~e sheet is positioned outside of ~he longitudinal shell.

FIGURE 3 is a schematic representation oX a partial view of a longîtudinal cross-section o~ a permeator in accordance with ~his invention wherein the resilie~t member is positioned within the shell.
.

FIGURE 4 is a schemati~ representation of a partial view o a longitudinal cross-section of a permeator in accordance with this invention wherein a spacer is employed between the end closure cap and the tube sheet.

The permeator depicted in Figure 1 is generally designated by the numeral 100. PermPator 100 comprises shell 102 Conly the head and tail ends are depicted) which is adapted to receive a tu~e sheet at one end. Shell 102 may be comprised of any suitable, fluid impervious material such as metals and `35 plastics. In many pe~m~?ators, metals such as steel are employed due to their ease of fabrication, durability, and strength. The shell may be in any suitable cross-sectional configurations; however, generally circular cross sections are preferred. Shell 102 has head flange 104 a~ the end adapted ~o recelve the tube sheet and tail flange 106 at the opposite end. As shown, shell 102 is provided with port 108 adjacent ~o the head flange 104. Port 108 ca~ pro~ide ~or fluid communication with the interior o the shell. While . 10 only a singl~ port 108 is depicted, it should be understood that a plurality of ports 108 may be posi~ioned around the periphery of shell 102. End cap 110 is positioned at the tail end of shell 102 and is fastened by bol~s (not shown) ~o tail flange 106. Gasket 112 is positioned between end cap 110 and tail flange 106 to provide an Pss~ntially fluid impermeable seal. End cap 110 i~ provided with port 114 for fluid comm~ni~ation through ~he end eap.
Bundle 116 (not sh~wn in cross-section) is composed of a plurality of hollow fi~ers is positioned within shell 102.
Ofte~ ~he bundle comprises o~er 10~000 hollow fibers, and wîth smaller diameter hollow fibers and larger diameter shells, there may be an excess o~ 100,000 or even an exce~s of 1,000,000 fibers. A~ depicted, the bundle has essentially the same cross-sectional configuration as that of the shell. One end 2~ of each of the hollow fibers in bundle 116 is embedded in tube sheet 118 (not sho~n in eross-sec~ion). The bores of the hollow ibers communicate ~hrough tube sheet 118 to the open end of shell 102. The other end of each of the hollow ~ibers is em~edded in plug 120 (.not shown in cross-section). The bores of ~he hollow fibers do not communicate through plug 120, The tu~e sheet and plug may be formed in any suitable manner, e.g., by casting a potting material or by impregnating th~
ends of th~ fibers with potting material while assembling the hollow fibers to form the bundle.
As shown in Figure 1 tube sheet flange 122 Cillus~rated in a partial break-away view) surrounds the side of tube sheet 118 and is securely affixed to tube sheet 118 by a plurali~y of screws 124. Tube sheet flange 122 has laterally extending flange member 123 which partially overhangs the end of shell 102. Extending rearwardly from flange number 123 are a plurality of positioning pins 125 which are received by bores 5 127 in the end o shell 102. Surrounding each positioning pin - 125 is spring 126. Positioned on head flange 104 of shell lOZ
is head end closure cap 128. Head end closure cap 128 is adap~ed to be fastened to the head rClange 104 by bolts (not illustrated). Positioned between head end closure cap 128 10 and head flange 104 is g~sket 130 which is adapted to provide a fluid tight seal. Head end closure cap 128 is also prov~ded with an annular groove 132 which is adapted to receiYe O-ring 134, Groove 132 has a larger minimum dîameter than the minimum diameter o~ O-ring 134 such that the û-ring is stre~ched when fit~ed into the groove and can thus easily be maintained in place during and after assem~ly. 0-ring 134 provides a fluid-tight seal between head end closure 128 and tube sheet 1~8. It is also clear that by attaching tube sheet flange 122 to tube shee~ 118 in an essentially 1uid imper~eable 20 man~ex, 0-rl~g 134 may suitably contact tube sheet flange 122 in an essentially fluid impermeable manner in order to provide a permeator of this invention~ The force to pro~ide the de~ired fluid-tight seal is provided by spring 126 which forces tube sheet 118 longitudinally outward from the shell.
25 Head end closure cap 128 is also provided with port 136 for 1uid communica~ion with thP bores of the hollow fibers, - In operation of permeator lOa, a fluid feed mix~ure may be intrGduced into the shell side of the permeator through port 114 or, preferably, port 108 with the non-permeating fluid ~eing r~moved from the shell side of the permeator - thxough the other port. Permeating fluid enters the bores of the hollow fibers and communicates through tube sheet 118 and is exhausted from the permeator through port 136 in head end closure cap 128.
Figure 2 illustrates ~he head portion o~ a penmeator generally designa~ed by the numeral 200 Permea~or 200 comprises shell 202 which has a circular transverse cross~

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sectional configuration. Shell 202 is provided ~ith head end 1ange 204 and fluid communication por~ 208. Within shell 202 is posi~ioned bundle 216 (not shown in cross~section) which is composed of a plurality of hollow fiber membranes. The bundle has the same generaL transverse cross-sectional con~iguration as the in~erior o the shell. Bundle 216 is ~erminated at th~ head ~nd with tube sheet 218 ~not shown in cross-section). As depicted tube sheet 218 has an outer face ~stepped) i~ which a concentric cen~ral portion exte~ds b~yond the surrounding annular por~ion. Wa~e spring 226 is posi~ioned between the end of shell 202 and the inside ~ace o~ tube sheet 218. Wave spring 226 provides a resilient force adapted to direct tube sheet 218 longitudinally outward fr~m shell 202.
Head end closure cap 228 is adapted to be securely fastened to shell 202 by use of bolts (not shown). Gasket 230 is positioned between head end closure cap 228 and head flange 204 of shell 202 such that when h~ad end cl~sure cap 2~8 is securely at~ached to shell 202 a fluid-tight relati.onship is achieved, 0-ring 234 con~act~ the out~ide face of tube sheet 218 a~ the annular portion and is maintained in a ~luid-tight reLationship with head end closure 223 when head end closure cap 228 and shell 202 are fastened due to the longitudinally outward orces exerted by a wa~e spring 226. Head end closure cap 2~8 is provided with port 236 for 1uid communica~ion through permeator 200 with th~ bores o~ the hollow fiber membranes, Figure 3 illustrates the head portion of a permeator gene~ally designated by the numeral 300. Permeator 300 c~mprises shell 302. 5hell 302 comprises head flange 304 and bundle restraining tube 303 which extends ~herefrom.
Xead flange 304 has a large central bore and the end portion o bundle constraining tu~e 303 extends in~o the bore such that an annular region exists between the exterior surfaee of tube 303 and the surface of the bore in head 1ange 304.
Spacing member 305 is position d within the bore and head flange 304 in order ~o sec~re tube 303 therein~ Spacing member 305 has a longitudinal extending portion which is adapted to ~e affixed to tube 303 and extends longitudinally beyond tu~e 303~ At the end of spacing member 305 distant L~ 3 S

from tube 303, a laterally extending portion is provided which contacts the surace defining the ~ore in head flange 304. Head flange 304 is provided with port 308 for fluid communication into the annular region surrounding tube 303.
S The longitudinal surface of spacing member 305 has fluid entry ports 307 for communication of gases ~etween the interior of tu'~e 303 and the annular region surrounding tu~e 303, and thus spacing member 305 serves as a fluid distribution plenum.
Bundle 316 Cnot shown in cross-section), which is composed of a plurality o hollow fiber membranes, is positioned within tube 303 and extends beyond tube 303 and spacing member 305 into tube sheet 318 (not shown ;n cross-section). Tube shee~
318 is positioned within the bore of head flange 304 and wave spring 326 is positioned between the inside face of tube sheet 318 and the laterally extending surface of spacing member 305, ~ 'he end closure cap of permeator 300 comprises two members, the ~irst being tube sheet sealing member 335 which is adjacent to head flange 304, and fluid distri~ution member 329 which îs positioned on the other side of sealing member 335, Sealing member 335 has a sufficiently small concentric ~ore such that ample surface is provided to contact O-ring 334 in a fluid-tight manner w~ich in turn contacts the outside face . o tube sheet 318. The bore of sealing mem~er 335 is suflcie~tly large in diameter that no undue restriction to flow from t~e ~ores of the hollow fibers occurs. Fluid distribution mem~er 3~9 is provided with port 336 for fluid communication from the permeator. Gasket 330 ;s positioned between head flange 304 and sealing member 335, and gasket 331 is positioned between sealing member 335 and fluid distribution mem~er 32~. The gaskets are adapted-to provide a fluid-tight relationship between the members when the mem~ers are secured together> e.g., ~y t~e use of bolts (not shown~.
Figure 4 illustrates the head portion of a permeator generally designated by the numeral 40Q. Permeator 400 comprises shell 402 h~ving a head end of increased diameter and head flange 404 and fluid communication port 408. Within ~` shell 402 is positioned bundle 416 (not shown in cross-section) which is composed of a plurality of hollow iber membranes.
The bundle has the same general transverse cross~sectional con~iguration as the interior of the shell. Bundle 416 pas~es through plenum 405 having fluid distribution ports (not shown).
Plenum 405 is positioned withi~ ~he head end of shell 402 and serves to distribute fluîd passing to or from fluid comm~nication por~ 408. Bundle 416 is tenminated at the head end wi~h tubeæ
sheet 418 (no~ shown in cross-section). Wave springs 42~a and 426b are separated by washer 427 and ser~e to provide the resilient member between plenum 405 and tube sheet 418. By utilizing alternating wave springs and washers, a desixed spacing and flexibili~y can be achieved. Accordingly, suitable forces can be obtained without concern fo~ close tolerancing of the thickness of the tube ~heet. At the face of tube sh~et 418 is positioned.an~ular sealing spacer 435. Annular sealing spacer has 0-ring 437 positioned on i~s ~ace adi acent the face of tube sheet 418 and 0-ring 439 positioned on its opposite faee. Head end closure cap 428 is adapted to be securely fastened to shell 402 by the use of bolts (not s~own) and cover the bore in the shellO 0-ring 430 is positioned between head end closu~e cap 428 and head. flange 404 such that when head end closure cap 42~ having fluid com~unication port 436 is securely attached to the shell a fluid-tight relationship is achle~ed. O ring 439 contacts head end closure cap 428 when attached to the shell. A fl.uid-tight relationship is provided by the forces exerted on tu~e sheet 418 by wave washers 426a and 426b. These forces also provide a fluid~tight seal o~ 0-ring 437 with the face of tu~e shee~ 418. The wid~h of annular sealing spacer 435 can be chosen to provide the desired compression of wave springs 426a and 426b and thus enable desired pressures to be provided by the wa~e springs,

Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A permeator comprising an elongated tubular shell having at least one open end; an essentially fluid impermeable end closure cap removably fastened to and covering said elongated tubular shell at said open end, said end closure cap having at least one fluid communication port; a plurality of hollow fibers exhibiting selectivity to the permeation of at least one fluid in a fluid mixture containing at least one other component which hollow fibers are generally parallel and extend longitudinally to form at least one bundle in the elongated tubular shell; an essentially fluid impermeable tube sheet having an outside face wherein the hollow fibers in said at least one bundle are embedded in the tube sheet such that the bores of the hollow fibers provide fluid communication through the tube sheet, wherein said outside face extends beyond the periphery of said at least one bundle embedded in the tube sheet and is proximate to the end closure cap; at least one resilient member cooperating between the shell and tube sheet and being adapted to provide a force on the tube sheet, which force is generally directed longitudinally outward from said open end of the shell; a first sealing means between the end closure cap and the shell which is adapted to provide an essentially fluid-tight seal between the end closure cap and the shell; and a second sealing means between the end closure cap and the outside face of the tube sheet, said second sealing means substantially surrounding said at least one bundle embedded in said tube sheet, wherein said at least one resilient member provides sufficient force on the tube sheet such that said second sealing means provides an essentially fluid-tight seal between the outside face of the tube sheet and the end closure cap.

2. The permeator of claim 1 in which the tube sheet is at least partially within the shell and is longitudinally slideably positioned within the shell.

3. The permeator of claim 2 in which the resilient member contacts the interior surface of the shell and contacts the tube sheet.

4. The permeator of claim 2 in which the resilient member contacts the end surface of the shell and contacts the tube sheet.

5. The permeator of claim 3 or 4 in which the tube sheet is adapted to be removed from the permeator.

6. The permeator of claim 3 or 4 in which the resilient member is a spring.

7. The permeator of claim 1 in which the tube sheet is outside of the shell.

8. The permeator of claim 3, 4 or 7 in which the outside face of the tube sheet is substantially perpendicular to the orientation of the hollow fibers.

9. The permeator of claim 1 having a single open end.

10. The permeator of claim 1 or 9 having a single bundle.