CA2227807A1

CA2227807A1 - Hybrid filter system and method for filtering process fluid

Info

Publication number: CA2227807A1
Application number: CA002227807A
Authority: CA
Inventors: Norman G. Cathcart; Donald B. Stevens
Original assignee: Individual
Current assignee: Pall Corp
Priority date: 1995-07-27
Filing date: 1996-07-25
Publication date: 1997-02-13
Also published as: WO1997004852A3; WO1997004852A2; AU6687496A; US5766486A; KR19990035812A; EP0854748A2; JPH11510095A

Abstract

A hybrid filter system (10) and a method for filtering process fluid utilizing a backwash (14) containment vessel (12). Tube sheet assemblies (14) designed to hold disposable or backwashable filter elements (20) are utilized to secure either type of filter elements in the backwash containment vessel (12). The tube sheet assemblies (14) are removably mounted in the backwash containment vessel (12), and may be easily swapped for a given filtering application. The hybrid filter system (20) utilizes a backwash containment vessel (12) in conjunction with either disposable filter elements or backwashable filter elements depending upon process flow parameters.

Description

W O 97/04852 PCT~US96/12621 HYBRlll) ~ILTER ~;Y~l~;~ AND METHOD
FOR ~ILTERING PROCESS El.UID

BACKGROUND OF THE INVENTION

1. Field of the Invention The present invention relates to â hybrid filter system and method for filtering a process fluid such as a gas or liquid or ~ Lul~,S of gas and liquid. More particularly, the present invention relates to a hybrid filter system operable with disposable filter eleln~nt~ and l~ell~lable filter cl~ and a method for filtering a process fluid using either disposable filter elçm~nt~ or reg~ dble filter elements.

2. Di~r~e~ion of the Prior Art In many filtration applications, the selection of a particular type of filter el~m~nt ~resellL~. a relatively simple choice. For example, if the colu~e~ ,,lion of solids in the particular process fluid is low, a filter system having disposable filter elem~nt~ may be econolllically l-tili7~cl A disposable filter element is one which is typically removed and discarded after it becomes fouled. Where the collcellLlaLion of solids in the fluid is low, the disposable filter elçm~ t~ may be used for long periods of time before becoming fouled, thereby making it cost ~rre.;livc; to replace the fouled disposable filter ek,...t..l~;
with clean disposable filter elt~m~nt~ each time the filter elçm~nt~ becolme fouled.
Al~ll~lively, if the concellLldlion of solids in the particular process fluid is high, 20 a filter system having l~gell~lable, e.g., backwashable or backblowable filter el~n ~ont~, may be more economically llt~ od A l~gel.elable filter elem.ont is one which is typically reused after it has been cleaned by wasl~illg liquid through it or blowing gas through it, often in the direction opposite the normal flow direction. Where the SUBSTITUTE SHEET ~RULE 26) W 097/04852 PCT~US96/12621 conr~ . n~ ;-)n of solids in the process fluid is high, the filter cl( ~ x may become fouled quickly, thereby making it more cost effective to clean and reuse the fouled filter c~ x rather then replace them. In addition, replacing the filter ~ often ,ases system down time, and may expose the c~.alor to ~ kce~ y risks in the S case of filt~ring hazardous m~te-~lx.
Regenerable filter sy~,k;llls are typically diLr~ than disposable filter ,y~lellls.
For t;Y;~ ,le, both backwashable and disposable f~ter systems typically co,~ ise a fluid co.. ~;.. - -.1 vessel, but bachv~,asllable filter systems have ~ltlition~l bacLwasll-related pipes c~n~cl-Pd to the fluid co-.l;.i.. ~,1 vessel in order to supply b~c~wa~ , fluids, 10 solvents or agents, and ples~uli~d gases, all of which facilitate the back~.aslli~
operation. A fluid co-.l;~il,...~.l vessel of a disposable filter system typically has none of these pipes because the disposable filter e~ ..lx are not ba~kwar,l~d. Purther, ba~Lwasllable filter sy.,t~n,s typically require large rli~mP~t~pr fluid co..lS~in~.k~.l vessels with con~ Pr~hle spacing between filter el~nPnt~ so that ~frecli~; and err~
15 bachwà~ g may be accomplished. A fluid c~ ;.;l""Prlt vessel of a di,~osable filter system having a coll~,s~vlllillg flow rate to a bacLvvashable filter system typically has a much smaller ~ ".- t~l because the extra spacing b~ l filter cl~ is not nPcess~ry. Also, backwashing filter ~y~llls ty-pically have fluid col~ l vessels with large ~ m~tPr drain pipes so that the backv~,a~llillg fluid and filter el -..- -~1 deposits 20 can be quicLly washed and removed from the vessel with no suhst~nt~ .es~u~, drop created at the drain. The drain of a fluid cont~inmPnt vessel of a disposable filter system may be much smaller because large volumes of backwa~ g fluid and filter elPmPnt deposits are not regularly removed from the vessel. Additionally, in both bacLv~asllable and disposable filter systems the fluid co.~l;1i.. ~.~l vessels typically include a process 25 fluid ch~mher and a filtrate chamber. The process fluid ch~ hel is the chamber lll~vugll which the process fluid is introduced into the system, and the filtrate çh~mhçr is the ch~mher in which the filtrate, i.e., the filtered process fluid, is collected. In bacLv~,a~hable filter systems the filtrate ch~llbe. is generally larger to acc~ mmotl~te the fluid to be utilized in the backwashing process. The filtrate c;halllber of a disposable 30 filter may be much smaller because no filtrate needs to be retained for backwashing.
The filter elements utilized in bacLwashable filter systems are typically di SUBSTITUTE SHEET (RULE 26) W 097/04852 PCT~US96/12621 ~from the fil er elP.~mPnt~ utilized in disposable filter systems. For ex~ , bac~.asLab~e filter ck "/ ~ typically include additional cG~ O~ .. The ad~lition~l colll~ullt;llL~ may be utilized to prevent damage to the backwashable filter clc-..~ ; caused by the larger forces ge--F ~ d by the higher reverse ~ Ul-, dirL.~,nlidls caused by the reverse flow S of fluid during back~àslling. Thus, the additional colll~oll~;llL. may include robust outer su~lJulL~. such as cages, shells, sleeves, and wraps. Disposable filter ck~ genpr~l1y do not col,l~lise these ~ tion~l colll~ollellL, since they are not usually t:A~osed to larger reverse pl~ Ul'~ dirr~ ls bcca~sc they are nût bacL~hd~hed. Further, bacLv"a~.hablc filter elomPnt~ typically have smaller ~ ,". f~.~i and denser fflter media to f~rilit~tP the 10 depûsition of solids in the process fluid on or near the U~ Le~ll surface of ~e filter ~r.li~ and the removal of the solids from the filter media. In 'oack~ .~able filter systems, a reverse flow of bacL~ash fluid is utilized to remove deyo~ on the filter elotnPnt~; accordillgly, if the deposits are on ûr near the Uy~ ,alll surface of the filter ehPmPnt~, the more easily the deposits are removed. The ~ P 1~ I of di~ osable filter 15 c~ is typically larger, and the filter media is less dense in order to ~,~asc the filtration surface area and/or the removal efrlc;ell~;y. Since disposable filter el,~ ; are not cle~n~, they are usually fle~ign~d to facilitate the removal of as much solids as possible without regard to cleanability.
As stated above, there are many filtration applications in which the selection of 20 a filter system is simple; however, there are also many filtration applications that fall between the two e~ Ies, thereby maLing the choice of which type of filter system to utilize more ~1ifflrult and polelllidlly costly. Since ~;ul~"lLly used filter ~y~L~.lls are typically de~i~nPd as regenerable filter systems or disposable filter systems, there is no flexibility in terms of tailoring the filter system to the particular application. If a 25 ~ege--P, ~hle filter system is utilized where the solids collcellllalion is low enough to make disposable filters economical, money has been spent ~ fcec~. ily in in~t~lling the more e~iv~ legellelable filter system. Conversely, if a disposable filter system is utilized ~ where the solids col-re.. l~ n is high enough to make l~ge~P-,~hle filter el~mPn SUBSTITUTE SHEET (RULE 26) W O 97/04852 PCT~US96/12621 eco~ ...ir~ 1(1iti~n~1 money will be spent on unduly replacing di~osable filter r~ x or inct~llin~ a bachwa~hable filter system. Additionally, the particular filtration ~pplica~ion may change over time, e.g., change in solids col~r~ ;OI" and the filter system may not be efficient for the changed con~lition~c. In citl1~tionc where the filtr~tion S ~lica~ion may change, due for example to the changed process flow p~ n~ or even a change in the process fluid, filtrring may become e~ ce of the L~cli~,~,.less of the particular system. In addition, beca.l~e of this ;..~rr~iv~ ss of the one system due to changed conditions, two or more s~ aLe filter ~y~t~,,lls may be required, which may be prohibitively e~ ,.~ivl;.

In acco,d~lce with one aspect, the present invention is dh~Led to a hybrid filter system. The hybrid filter system colll~lises a r~e,~,able filter cc,..~ vessel having a process fluid chamber and a filtrate rh~",~ , a tube sheet, and a plurality of di~o~able filter cle-.. ~ . The r~ellc.~ble filter co-.~;~i.. ~--~ vessel also inrh~ s an inlet c~-.~.. i~tin~ with the process fluid ch,.. ~.h~" a drain co.. ~ with the process fluid rh~mh~r and sized to er~cliv~ly drain fluid and filter de~osils from the process fluid Ch~lll)e,., an outlet co.~ with the filtrate rh~...her, and a ,~g~-.r-dlion-related port c~ "i~ting with the filtrate rl~.",h~l. The ~gc~l~r..-~ion-related port is capped. The tube sheet is mounted bcLweell the process fluid cl~l~ber and 20 the filtrate ch~..ke. of the ~cgell~,rable filter cont~inm~nt vessel, and provides a barrier b~ C.1 the process fluid rh~mher and the filtrate challlb~l. The tube sheet includes a plurality of ~e~ gs for the disposable filter elements. The plurality of disposable filter el~ ..l..; are mounted to the tube sheet and extend into the process fluid cl~ll~e. of the l~,g~ ble filter co..l~ .l vessel. Each disposable filter elPm~-nt co...~ es a filter 25 ",~ and an open end which cu....n....i~ s with the filtrate chamber of the backwash filter co--~i.i~...~ell~ vessel, and each disposable filter e~ o-nt has insuffilcient structural y to wilh~ n~l one or more re~ ion cycles and/or a ~Llu~;lur~ which resists SUBSTITUTE SHEET (RULE 26) errc~;~vc le~
In acc~ cc with another aspect, the present invention is di~ d to a method for filtfrin~ process fluid CfJ../~ solids. The method COl1~1i;~eS passing the process fluid into a process fluid ch~ el of a l~gtl~able filter vessel through an inlet of the S ~ ldble filter vessel, dhc~ g the process fluid Ill..u~ll a plurality of dib~osable filter el~mt~ntc or ,e~ ,lable filter el~nl~tc mounted in the process fluid C
inrlllt1ing loading solids on or in the filter mt flillm of the filter elem-ntc, di~
filtrate from the filter e'~P!m~ntc into a filtrate rh~mber of the l~,ell~lable filter vessel and then through an outlet of the l~gelle.dble filter vessel, and cle~e~uli.~ on a preY~ d 10 loading condi~iQn, either re~lacing the loaded filter elemtnt~ with disposable fflter , or replacing the loaded filter elem~ontc with legell~,lable f~ter el~..llt'~ i and con~ cl;..~ a l~gel~lalion assembly to the l~gel~ldble filter vessel.
Hybrid filter systems and methods of the present invention provide a flexible, low ~ cost filtration system and method which exploits the advdlllages asbocid~d with 15 both lcgellelable filter systems and disposable filter systems in a single system. T~is is particularly advantageous in applications where it is initially unclear wL~ a ~g~r-~ kle filter system is pler~,llc:d or a disposable filter system is pl~f~ ;d.
For example, an exemplary hybrid filter system c-....l..; es a bac~.ash c~ vessel which may initially be equipped with disposable filter ele-.~ As20 the process fluid co..~ solids is passed through tne hybrid filter system, the solids are deposited on or in the disposable filter elements and the p .bure drop across the disposable filter elem~nt~ il~leases. D~ling on a pre-det~ - .n;..~d loading condition, such as the amount of time it takes the ~l~s:~ule drop across the disposable filter el~ .n.~nl~
to increase to a m~imllm desirable value, the fouled disposable filter cl~--..--.ls are 25 removed and replaced with either clean disposable filter e~ or ba~wasllablc filter el~om~ont.c. For example, if it takes a long period of time for the pl'eS~ul~. drop across the initial disposable filter elements to i~ ase to the m;~x;-~ --- desirable value, then it may be more e~;o~ l to continue to use disposable filter elements in the hybrid filter SUBSTITUTE SHEET (RULE 26) W097/048S2 PCT~US96/12621 system. The fouled disposable filter C1e.~f.~IX would simply be removed from thebac~wasll co--~ lll vessel and clean disposable filter f 1P -~1 -IIX would be inct~llf rl On the other hand, if it takes a short period of time for the p~ Ulc drop across the initial di~osable filter elomPnte to hl,_l.,a~f to the m~ximllm desirable value, then it would be more eu~n...ir~l to use bac~wasl~able filter cl,~-..--~lx. The fouled disposable filter el, ~.,- -.lx would be removed from the bac}~wdsll co.-l ~i""~r-,l vessel, bacl~waslldblc filter cl. -------lx would be inet~llPfl, and the bac~wash colll;~ vessel would be c~ P.'ed to a bac~wa~Lillg assembly. The bac~.asllable filter ek-..~,lc could LLc,~,ar~, be bac~wa~lled wLcll.,v~,. they become fouled.
The exPmplary hybrid filter system of the present in~rention may comprise a regenP-rahle co~ vessel and the vessel haldwalc, inrlllflin~ a)nnPcti~ n pipes such as r~2~c.~ on-related pipes, il~Ll.. r~ ic)n, manifolding, and flow control valves, as well as the filter el~mPnt~. The ,egen- Iakle co~ .- ~.1 vessel may be divided into upper and lower chambers by a partition such as a tube sheet. The tube sheet may be 15 removably mounted within the lcgel~lable c~ o~ vessel, and fimrtinn.e to secure the filter c~ x, either disposable or rcg~ able, within the l~ clable COl~ --f .ll vessel. Accoldmgly, (l~pc'~u~ upon the loading conrlitif~n, the filter c~ x, either disposable or lege.l~able, may be easily and quickly ~wd~ed by f Yr~ g;..g tube sheets having the filter el~om~ontx ~tt~rllf~(l thereto or by ~wa~ g the filter cl~ ...,..lx on a tube 20 sheet capable of supporting either type of filter element.
Exemplary hybrid filter systems of the present hl~cllLiol- may reduce system down time by providing the flexibility to tailor the system to specific applir~tione. The hybrid filter system also reduces the ~.~lclllial e~ o~ule of the system ~,ldlur to h~dous s~;~..res which may be the fluid being filtered or a by-product thereof by ..-i-.;..~i,i.~g 25 the ...A;..~P~.A.~re frequency.
The exemrl~ry hybrid filter system of the present invention may be utilized in aduplex or t~ndem allang~ l. For example, two or more hybrid filter systems may be illtel~;o..~-~ct~l through a valve ~. .d~¢r~ I such that one hybrid filter system is always SUBSTITUTE SHEET (RULE 26) in a filt~rin~ mode of operation. With this type of a..~u~gt;lll~ the filter el~ of one hybrid filter system may be l~,g~ (1 or replaced while the filt~ri~ of the process fluid contim~Ps u~iu~L~l~u~led in the second hybrid filter system. A third hybrid filter system may also be inter-co~ P~r~l into the duplex ~ r~ as a stand-by unit. For S example, if one of the hybrid filter systems should have to be shut down, e.g., during routine ...~ e, the third hybrid filter system may simply be brought on line to ensure contimloll~ and ~-..;..l~ ~.u~l~d filtPrin~ of the process fluid.

BRIEF DESCRIPTION OF THE DRAWINGS
Figure ~ is a cross-se-;liol~l view of an e~emplary embG~ltm~nt of ~e hybrid 10 filter system of the present invention.
Figure 2 is a ~let~ilP~l diag~ prese~ inn of a tube sheet and disposable filter elemPnt of the hybrid filter system of the present i-~vc; ~lio~..
Figure 3 is a ~lPt~ l diag-i~ ic .c~ s~ n of a tube sheet and a l~g~-l- ~able filter c~ ..1 of the hybrid filter system of the present invention.
Figure 4 is a ~1et~ilP~ a~ ,se--l;-linn of a tube sheet with sealed holes.
Figure 5 is a schc~ aLic l~ sP~ n of the hybrid f~ter system and a .g~ lion assembly.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
As described in the Ba~loulld section, l~elle,able f~ter e~m~nt~ may collll,.isebackwashable and backblowable filter clel..ellL~. However, for l~ul~03es of clarity and simplicity, the tlet~ilP~l description of the exemplary hybrid filter system of the present invention shall make .er~ lce to backwashable filter elPmPnt~ in ~~ llssillg the aU il,u~s and advantages of the hybrid filter system and method for filt~ring process fluids.
An exemplary hybrid filter system of the present invention utilizes a backwash ~ e.,.. li.i.. ~.l vessel which is ~ ign~ for backwasllillg, i.e., it is sized for ba~k~.aslling SUI~S l 11 ~JTE SHEET (RULE 26) WO 97/04852 PCT~US96/12621 and it in~ des the various internal hàldwaie and internal and çxtPrn~l conl-~c~i-nc utilized in backwasLillg, i.e., backwa~ related c~ l;orls. However, in accol.lallce with one aspect of the invention, the exemplary hybrid filter system may contain within the backv~a~L filter co--~ vessel either disposable filter el~om-o.ntc or bac~wasLable S filter c~ , thereby exploiting the advantages offered by each type of filterr Disposable filter cl~-..--.l~, which are typically utilized in low solids CO~ .I;O
filtration appli~?ti~ nc, are generally less ~)el~iivt: individually and have lower m~ e costs associated with them. Backwashable filter cl ~ , which are typically utilized in high solids conce.lLldlion filtration appli~ti~mc~ are generally more 10 e~e.lsiv~ individually but ma;r be reused through many filterin~ and cle~nin~ cycles.
Accoldil,gly, the exe.l~laly hybrid filter system has the fl-oxibility to run~;lioll as either a fully erÇ.,uLivt; disposable filter system or a fully effective backwashable filter system without any colll~r~mise in perf~,....;~nre. Cnneeqn~ntly, the exe~ laly hybrid filter system is ideal for the many filtration applications where it is initially unclear wh~
15 a disposable or ba~wasllable filter system is better. When lltili7ing dis~osàble filter c~ x, which may be discarded after a single filkation cycle, the various vessel L~dwale and co~ s for pclrl,lll~illg the backwash operation are closed or sealed.
Conversely, when ntili~in~ bach~ashable filter ele..~ ;, which may be cleaned and reused after a single filtration cycle, the various vessel hâl-lwdl~ and connecliolls are 20 activated and co~-n~c~d to a legt;i~lalion assembly, e.g.,a backwasllillg assembly, for ~ÇOlll~iJlg the backwash operation. The exemplary hybrid filter system may be rapidly configured for either mode of operation by simply adju~Lill~ the a~r~l;aLe system ~lwal~ and conn~octi~-rls and by ~a~hlg a tube sheet holding disposable filter el~.~.eo~x with a tube sheet holding backwa~llable filter cle-.~ or vise versa.
25 Preferably, only the filter elements are swapped with the same tube sheet fitting both types of filter elemPnf~. The term filter element as used h~,rt,arlel shall be lm~erstood to be a generic desclil,lur for both types of filter elements unless otherwise slJPe;l;P~l As illustrated in Figure 1, an exemplary hybrid filter system 10 embodying the SU~ 1 l l UTE SR __ I (RULE 26) W O 97/04852 PCT~US96/12621 present ~~ lion inr~ es a bachwash co,~ l vessel 12 which is divided by a partition 14, such as a tube sheet, into process fluid rh~mher 16 and a filtrate rl-~...hel 18. One or more filter rl~ llx 20, three of which are illll~tr~t~l, are di~osed inside the process fluid ~ h~- 16 and att~ch~od to the tube sheet 14. The bachwasl.
5 co..~ .l vessel 12 is preferably col~L u~ d so that the filter elr~ 20 may be readily ~ccessed to permit their rep~ -l or to swap one type of filter el,~ .1 for a second type of filter elçm~ont For example, the back-,vash co..~ vessel 12 may include first and second se.;lio.~ ~et~rh~hly conlle~;led to one another. ~lte. ..~ y or additionally, one or more sealable access ports may be formed in the bachwash 10 co..l~ vessel 12 to permit access to the inside of the process fluid or f~trate cl-~...bel~ 16, 18.
As stated above, the exemplary hybrid filter system 10 may be used both for filt~ring a fluid by means of disposable or bachwashâble filter e! ...~ x, and for c1e~nin~
the bacLwasl-able filter clc.~ x by backwashing. Accoldi~ly, in acc(j.da~lce with one 15 aspect of the invention, the bacLwash cont~inm~nt vessel 12 is configured as a bacL~
filter vessel. Generally the shape of the backwash co.. ~;.;.. -~.~ vessel 12 will be s~lPct~l based on :jLL~ and back~a~l- c-m~ ti- n.C so that the bacL~.ash cc,..~ vessel 12 will have sllffici~qnt strength to wi~ l the pl~ ules exerted on it during filtration or bacLwa~ g, and ~..rr~ size to lpermit err~;~ , effi~ient filtration and 20 backwashing of the backwash filter c~ .lx.
The tube sheet 14 is preferably impervious to fluid flow and is removably monntt~-l to the inner wall of the backwash co--l~;-----~nt vessel 12 belweell the process fluid cl~l~l 16 and the filtrate ch~...hel 18. The tube sheet 14 is preferably disposed in the backwash cn~ vessel 12 s~lhst~nti~lly ho..,.o.-~lly, and the proçess fluid 25 çll~.nhe~ 16 is preferably disposed below the filtrate ch~mher 18. The filtrate rh~.~.l-er 18 may be larger to ~CCnmmO~l~tt~: the fluid, e.g., filtrate, which is utilized to backwash the filter el~m~ntX 20 if backwashable filter elem~ontx are ntili7~(1 As explained ~ ~ul~se~ .ontly the backwash fluid may be an externally supplied fluid or the filtrate SUBSTITUTESHEET(RULE26) W O 97t04852 PCTAUS96/12621 retained in the filtrate ~h----h~ 18. If the system is utilized with disposable filter cle~ , then a plug or other means may be pos;l;o~-Pd in the filtrate c~ . 18 to reduce hold-up volume.
A plurality of pipes, co.~ i, and other col-..~lionc~ inrl ~~lin~ back~.~.sL-related 5 co...~;l;o..~, may be c~ P1~Prl to the backwash co.~ .l vessel 12 for introrl~ring fluids into and l~.llOVilli3, fluids from the backwash co..~ vessel 12. For ex~-..plc, in the exemplary embo~l;...- -.l, a process fluid feed pipe 22, a drain pipe 24, a solvent feed pipe 26, and a first vent pipe 28 are col~ ;lcd to the back~. ~.sll co~ vessel 12 so as to co--------.~ir~lr with the inside of the process fluid f'l~ h~- 16. The process 10 fluid feed pipe 22 is used to introduce a process fluid to '~e f~tered into the process fluid ch~....h~ 16 from an unilh~ctrated source. The drain pipe 24 is used to remove ullwalllcd m~tPri~lc from the process fluid chamber 16 and to drain the process fluid ch~...hel 16.
The drain pipe 24 has a larger ~ Plrr so that the bd~wd.-71ling fluid and f~ter e~- -.-~-.
deposits are quickly washed from the filter cl/ ~ !i 20 and removed from the backw~.i.l vessel 12 with no ~ b~ 7~UlC drop created at the drain. A large drain pipe 24 also ~ ,dScS the crr~ ivci~i,s of any back~-vash because it enh~nrPs the initial surge of back~dsll fluid through the filter elemPnt when the drain is opened during backwd;,l~ g.
The drain pipe 24 may be co....P.-Ie~l to the process fluid source such that the ~ ;"~ge may be passed through the system again, or it may be co....~c~d to a backwash 20 recept~rle for disposal of the drainage. The solvent feed pipe 26 is utilized to deliver a soaking m~teri~l, for eY~mple, a dt;l~rg~ l into the process fluid chamber 16. This so~king m~teri~l facilitates the bachwasl~illg of the filter clF-..~ 20 as is explained in more detail .7l~l~sp~lllently. The first vent pipe 28 may c~ .;r~te with the process fluid c~l~mher 16 ~-cfeldbly just below the partition 14. The first vemt pipe 28 may be 25 utilized to simply vent gases from the process fluid Gh~mher 16 or to facilitate ,l.i.;.,i.,~
of the process fluid chamber 16 by providing chase gas. The process fluid feed pipe 22, the drain pipe 24, the solvent feed pipe 26, and the vent pipe 28 may be equipped with c~ ,~ullding control valves 30, 32, 34, 36 for controlling the flow through these pipes SUIBSTITUTE SHEET (RULE 26) W O 97/04852 PCT~US96/12621 22, 24, 26, and 28, l~,~e~ ly.
A(l~litinnqlly, in the exemplary hybrid filter system, a filtrate discl~gc pipe 38, - a second vent pipe 42, and bachv~,asll-related co~ P~ ns such as a pl~ d gas feed pipe 40 and a back~d~h liquid feed pipe 44 may be c~ c~ to the bach~.à~
5 co..~ l vessel 12 so as to co.."~ .,ir~l~ with the inside of the filtrate ch~ er 18.
The filtrate ~lischàr~,c pipe 38 is used to remove filtrate, i.e., fluid which has passed through the filter ~1~ "~-"1.~ 20 from the process fluid cll~---hçr 16 into the filtrate ~ ..,h~r 18. The ple~ d gas feed pipe 40 supplies the filtrate ~ mher 18 with a cOIll~l~sséd gas from a charge vessel illustrated in Figure 5. The second vent pipe 42 is utilized to 10 simply vent gases from the filtrate cl~bel 1~ or to facilitate tlr~in~ge of the filtrate cl-....hel 18 by providing chase gas. The backwash liquid feed pipe 44 may be utilized to introduce an ç~t~rn~lly supplied backwash fluid into the filtrate cl~lber 18 for backwasl~ g the filter el~m~ontc 20 or to supplement the filtrate bac~v~,ash if the system is e~i~ed with bachwa~hable filter rl/-"~ . The filtrate dischà~e pipe 38, the 15 p~ cl gas feed pipe 40, the second vent pipe 42, and the bachwash liquid feed may be e~lui~ed with CO~ u ~ g control valves 46, 48, 50, and 52 for controlling the flow through these pipes.
All control valves for the various pipes may be controlled m~ml~lly, or they canbe autom~tir~lly controlled, e.g., made to operate accol-lhlg to a pr~c~~~ihed secluen~e by 20 an llnill..~ l control unit.
In the illnctr~tlod exemplary embo~limtont each pipe serves a single rull~;Lioll, but it is possible to have a single pipe serve a plurality of rull~;liOllS. FulLL~llllolc, the figures are merely a s~ Ic~l~se--li ~iQn, and the locations of the cûllne.;Lions on the backwash c~".l;~i"."~nt vessel 12 are not limited to those shown in the figures and 25 fewer or more cu~ onS may be provided.
The tube sheet 14 as ~iiccll~ced above functions as a fluid impervious partitionbetween the process fluid challlbcl 16 and the filtrate chal~lbcl 18 of the backwash Co~ vessel 12. The tube sheet 14 colly,lises a plurality of ~e~ 54 in which SU~ 1 l l UTE SHEET (RULE 26) WO 97/04852 PCT~US96/12621 the filter el~-..f n~; 20 are mollntf d If less than all of the openi~ 54 are utilized for reasons e~lailled sllbsequPntly, they may be sealed. The size of the opcl~in~ 54 may vary dG~cndi~g on the size of the particular filter cl~ -..- -.l~ 20 lltili7P.11 As ~ ..C~P~l above, the ~ r of the bachwà~Lable filter c~ are typically dirr~ from the S ~li ".~ of disposable filter e~PmPnt~; ~lwlcrole, adaptors may be utilized if a single tube sheet 14 is lltili7P.~l The tube sheet 14 may be formed out of any suitable rigid mqtP~riql able to support the filter el~mPntc 20, and which will not react with the process fluids or gases passed into the system, in~ in~ polymeric mqt~riql.c or mPtq~ mqtPriqlc, For each of the filter elPnlf~ntc 20, an ~ellhlg which cc,n.,~ .s ~t~n the process fluid ch~mher 16 and filtrate l~hqmher 1$ is formed in the tube sheet 14 as explained above. Each filter ek mPnt 20 is co~-i .rcl~~ at one end to the tube sheet 14 so that fluid from the process fluid cl~llbel 16 can enter the upe~ulg 54 only by f~ct passing through the filter elPmPnt 20. Preferably, the filter c~ f-.l~ are ~Pt~qch~ly mounted on the tube sheet 14 so that they hang vertically in the process fluid cl.~...l~e 16. By h~ the filter elemPntc 20 below tube sheet 14 in the process fluid cha ll~Jel 16, bac~. aslli-lg and removal of the filter element deposits through the drain pipe 24 are greatly ç..h~ .etl The filter elçmf ntc 20 generally range in size from one inch or less to two inches or more in outside ~ t~ l, however, custom sized filter cl~ f -.l!~ may also be easily 20 utili7P~. In this exemplary embo~limf nt, each filter cl~llle~ll 20 is disposed entirely within the process fluid chamber 16, although it is possible for the filter cl~ -..- -.l~ 20 to extend part way into the filtrate chamber 18. Each filter el~m~nt 20 may also beco...-~.;le~l at the other end to a porous support plate, not shown, which extends across the backwash cc,..l;~;...n~ vessel 12 parallel to the tube sheet 14. The support plate 25 functions to secure the filter elem~nt~ 20 in position, and ~ ;n them in a ~b~l;...l;A11Y
parallel ofiel~
In acco,dallce with another aspect of the invention, the filter el~m~nt~ in the backwashable filter co~ nt vessel 12 may be either disposable or bacl~wd~llable S~,~c~ ITE SHEET(RULE 26) W 097/04852 PCT~US96/12621 filter el~ . Figure 2 jS a det~ile~ ,se~ on of a di~os~ble :filter e~ l 20 monn~d to the tube sheet 14. In the exemplary illustrated emboAim~nt, an upper portion of the disposable filter elP~nPnt 20 c~ lises an adaptor 56 which is disposed within the ~C11i11,~, 54 in the tube sheet 14. The adaptor 56 for use wi~ the di~osable filter 5 elPm~nt~ 20 may have a ~ l"~l~., less than the ~ .... t~, of the disposable filter ekP.mPnt~
20. Since the tube sheet 14 may be utilized for both types of filter c~ 20 and typically the two types of filter clcllle~lL~ have difrc~ mPt~rS~ adaptors are utilized to secure the particular filter ek-..~ i20 in a ul~ivcl~ally sized O~ lg 54. The adaptor 56 has an openil.g so that filtrate may flow from the interior of the disposable filter elemen~ 2û through the ~ube sheet 14 i}l~ ~e fil~ra~e c~ ,hel 18. A tse rod 5~ may be utilized to secure the disposable filter element 20 to the tube sheet 14. A seal nut 60 may be threaded onto a lower end of the tie rod 58 and a locking CO~ C~ 62 may be threaded onto an upper end of the tie rod 58. The locking co,l.~clor 62 iS basically a wheel ~L1LU;~U1C having spokes to provide O~C11i11~,~ for filtrate to flow from disposable filter C1~ 1 20 into the filtrate rh~mher 18. The ~ r of the locking c~nl-~ o. 62 is preferably larger than the rii~ of the opening 54 in the tube sheet 14 such that the filter cl~ 20 may be secured by ti~l,t~..;.~g the locking colll~ecLol against the tube sheet 14. In addition, clips 64 on the tube sheet 14 may also secure the lockingcoll~leckJl62 to the tube sheet 14. In addition, o-rings 66 may be utilized in the annular 20 gap bcLwccn the inner wall of the openings 54 in the tube sheet 14 and the outer wall of the adaptor 56 to provide a fluid tight seal.
Figure 3 is a ~iet~ r~.csc.lL~lion of a backwashable filter element 20 mounted to the tube sheet 14. As illustrated, the backwashable filter elem~nt 20 colll~.ises an adaptor 74 which is simply inserted into the opcmillg 54 in the tube sheet 14. A lip 76 or flange on the upper portion of the adaptor 74 rests upon the upper surface of the tube sheet 14. An o-ring seal 78 may be disposed bdw~;cll the lip 76 and the tube sheet 14 to provide a fluid tight seal. In ~ lition to the tube sheet 14, a tube sheet assembly may include a hold down plate 90 positioned over the adaptors 74 to secure the filter el~m~nt.

SUBSTITUTE SHEET (RULE 26) W O 97/04852 PCT~US96/12621 20 in place. The hold down plate 90 may be mollnt~d to the tube sheet 14 by bolts 92 or any other suitable sef ~ means. Ope.~i,lgs 94 in the hold down plate 90 col.~,Dpoud to O~)elnllgS in the tube sheet 14 and the adaptor 74 for fluid flow.
Figure 4 illuDll~Les a tube sheet 14 having a blind adaptor 96 sealing one of the S o~ iul~s 54 in the tube sheet 14. Blind adaptors 96 may be utilized when fewer filter rl. ~ than U~ fillgS are ~ltili7f-f1 For example, when di~os~blc filter cl- ~.-P~ . are ntili~fyl, typically fewer filter eLPmf~ntc are employed than if bac~waDl~ble filter f~
are utilized for the reasons ~ ;u~f-f1 D~l)se~ ently. Accoldi~ly, the extra o~e~ s in the tube sheet 14 may be covered with the blind adaptors 96.
As ill~ lr~l iIl Pigures 2 ar~d 4 ~e exemplary disposable filter cl~ 20 preferably colllplises a p~lrc,laLed f yl;~ - ;c~l core 68 and a filter ..~f~f~ .. 70 mounted on the core 68. The core 68 may collll,lise any suitably rigid, ~.Çu,~lf m~tf~ri~1 which is able to support the filter ...P.l;..." 70 from coll~rcin~ from the force of the process fluid during filtration. The core 68 may colll~lise polymeric msltf~ 1.c or mf~t~llif-15 m~ltPri~lc.
The filter ",f~ " 70 may collll,~ise any suitably porous pleated or non-pleated,surface or depth f~ter "~Pf1j...~ such as a porous membrane, a fibrous sheet or mass, or a porous sheet or mass of sintered material, e.g., a sintered metal or cf~r~mir. For example, the filter m-of~ m 70 may coll~lise a ~ylllhf lic or non-synthetic microporous 20 m~tPri~l such as poly~lopylene, nylon, cellulose, Halar, aramid, Ryton, or rlbel~lass.
The filter c~ may also include an open end which co.~ ..;f-~tlQs with the filtrate f-ll~mher 18 and a blind end or an open end blinded by an end cap or co~ P~or in the process fluid c~ h~l 16.
The bac~wasllable filter el~mPnt 20 may also c-,...l.. ;~e a ~ ro,~led f yl;~fl~ ;f-~1 core 80 and a filter m~f~ m 82 llloullled on the core 80. The core 80 may colll~,ise any suitably rigid ~elro,a~e m~tPri~l which is able to support the filter ..~P~ .,. 82 from coll~psin~ from the force of the process fluid during filtration. The core 80 may Cf~ )liSC polymeric m~tPri~lc or m-ot~ m~teri~l~. The filter mf-~lillm 82 may also SUBSTITUTE SHEET (RULE 26) -W O 97/04852 PCT~US96/12621 Co~ )Lis~ any suitably porous pleated or non-pleated, surface or depth filter ~ tl;..,~, such as a porous membrane, a fibrous sheet or mass, or a porous sheet or mass of sintere~
- m~t~ri~l, e.g., a sintered metal or c~r~mir. For example, the filter ~~-f~ 70 may co...~ a ~ylllll~,LiC or non-synthetic miclu~o,~,us m~t~ri~l such as poly~ ylene, 5 nylon, polyolefin, Halar, aramid, Ryton, fll~ ;lass, or any suitable metal alloy. The bac~wasllable filter ~IPmPnt 20 may also co~ ise an outer support s~lu;lulc 84 to protect and support the f~ter ,~,~.l;,..,, 82 during backwa;.llillg. The bach~a~.llable filter cl~ may also include an open end which c~ rs with the filtrate clu--.h~r 18and a blind end or an open end blinded by an end Câp or col~lec~ 86 in the process 10 fluid rl~",hel 16. The fluid co~ l vessel described above m2y generally be ~lesçribe-l as a backwash co..~ vessel which is ~ g..;~ le from fluid C~ vessels typically utilized with disposable filter ek-..f~ ;. Backwash c- ~-~i------~-~ vessels, as ~ c~ ecl above, have ~d~itif~n~l pipes or cn~ CO...~f~ to the two ~h~--.h,L" These additional pipes may be utilized to supply solvents, bac~ .h fluids, and p.~ 1 gases to the vessel in order to ~clrol.ll the bach~a~h operation.
I~ackw-dsh c---~; i-----~-~ vessels typically have larger ~li~ . Larger bachwash co~ vessels facilitate the backwash operation by providing a~ iti~n~l room for the deposits on the filter ektn.onts to be removed by either a reverse flow of fluid or by a pl~ .U-~ pulse from a cc,.ll~lessed gas. I~achwd~.ll co~ vessels also typically have larger drain pipes. Larger .li~",~l~, dMin pipes facilitate the removal of the bach~vash m~t~ti~l from the backwash filter vessel by çn~;--- ;,lp no reverse ~l~,S~ul~, build-up. Additionally, bachwa~ll filter vessels generally have larger duw~
chambers so that filtrate may be c~)-.~;.;.-~l within the vessel for backwai,llillg or so that a bac~wasl~illg liquid may be contained in the vessel for bac~a~l g.
Backwashable filter elemPntc are typically dir~,~ than disposable filter elemPntc in a ~lu~llb~, of .~i~e~;L~. For example, bac~a~l~able filter ehPmP-ntc may colllplise litic)n~l el~mPntc for structural support. Generally, ba~;}.wasllable filter el~P-mPntc colll~,.ise outer support structures inr~ ing cages, mPchPs, sleeves, shells, and wraps.

SUBSTITUTE SHEET (RULE 26) W097/04852 PCTrUS96/12621 These outer support ~L~uclul~s are porous structures so that fluid easily flows through them in order to avoid creating large ~n,i,~ulc dirr~ ials. The outer support Sl-UClu~S
may be placed over the u~ calll region of the filter elemlonte, i.e., u~ ,alll in relation to fluid flow path during normal f;ltrz~tion The outer support ~LIu~ provides S structural support for the filter l--Fd;~ when bacl~vvashing occurs. Since backvvaslling causes larger p~CS~Ul~, dirrclc-llials in the reverse flow dircelioll, which in turn g4-~F "~
larger forces acting on the filter clc~l,-nl in the reverse flow direction, strong, robust outer support structures are used to prevent damage to the filter ",~.1;..." caused by the bachwasL flow. The outer support structure as ~~ (l above may include cages, 10 meshes, sleeves, shells, and wraps, and may be constructed from various m~t~ri~le inrl~ in~ polymeric materials and m~opllic materials. In contrast, the disposable filter cl .,,r.~l~ gFn~r~lly do not coll,~ise outer support structures because the filter el~mPnte may not be subjected to the forces g~llelaled by bac~vva~hillg.
In a~ tion~ generally, bac~washable filter elemF nte are deeignPd to facilitate the 15 removal of dc~o~iLed solids on the filter elem~onte. Accc,~illgly, it would be preferable that the solids be depo~ilcd on or near the u~sL-~a~l surface of the filter I~lF~ 11 SO that the reverse backvvasl~ing flow can easily wash away the deposits. Th_l~fol~, denser filter media are typically utilized to ensure that the solids are pl~fel~ idlly d~o~iled on or near the U~ LlCalll surface of the filter m~ m In contrast, disposable filter cl~
20 may have a structure which resists erÇcclivc bachwa~l,illg. For example, the disposable filter cl~ generally have less dense filter media so that there is i l~ ,ased filter ",~-1;"", surface area for filtration. Since the elem~nte are disposable and do not have to be cle~n~l the solids may be distributed throughout the filter mF~dillm In addition to the individual aspects ellum~lalcd above for the disposable versus 25 backwashable vessels and filter elements, the configuration of the filter clF~ within the backwash co..l ...-i..~ vessel as well as the operation of the two types of ~y~ s are dirr~rclll. Generally, the process fluid flux rate for each individual filter elem~nt is preferably lower for backwashable filter elements than disposable filter clc . .~ in order SUBSTITUTE SHEET (RIJLE 26) =

W O 97/04852 PCT~US96/12621 to p~ l solids from ~f ~ deeply within the filter mf fli--m of the backwashable f~ter elf -nf ..~ The lower flux rate tends to facilitate the preferential deposition of solids - on or near the u~ ,alll sur~ace of the filter ~f ~ -- of the bacLwàsllàble filter c~
Accold~gly, for a given set of process con~liti-~n~, e.g., flow rates, the number as well 5 as the size of bacL~ashable filter el- ..~ should be selfct-fd in order to achieve the desired flux rate. Typically, because of the lower flux rates per Clf~ 1, larger numbers of bacL~..asllable f~ter cl~..-,..-l~ may be utilized in a particular application so that the process p~l~... t.~ -~, e.g., flow rates from the input to the output of the f31ter system, are f~ Since disposable filter Clf.~ !'; have larger dialll~t~l~, typically fewer 10 ck~ are ~tili7~od Accol~ gly, if one tube sheet is utilized in co~ ;lion withdisposable filter Cl~ f~, the extra openings in the tube sheet may be sealed with blinded adaptors as e~pl~inpd above.
The hybrid filter system embodying the hlvelllioll may be o~ ated in a variety of ways. Factors ;llrll~ell. i~l~ the mode of operation p~ ipally include the particular 15 process conrlition~ for the particular application, e.g., the chal~ l ;rs of the process fluid and the solids co,l~e~ d~ions and the desired flow rate and ple~ule drop.
Accor~i~;ly, in order to more clearly set forth the operation of the hybrid filter system, a general description of the filtration operation is given and the particular diLr~.c.~ces b~ n operation with disposable filter cl~ -.Ic and backwashable filter cl~--..~nl~ is 20 given with respect to the exemplary embo-limPnt~ shown in Figures 1-5.
Upon in~t~ tion, the hybrid filter system co,~,ises a backwash c~ ....Pnt vessel 12 with disposable filter e~ nt~ 20 disposed in the vessel 12. Backwashable f~ter ck ..~ may be initially installed in the back~asll co-~ vessel 12.
However, disposable filter elem~nt~ 20 are ~ler~ d initially because they are typically 25 less e,~c;lLsivc~ than backwashable 16 filter e!emPnt~. All of the backwash-related conn.octi- n~, e.g., the plc;s~uled gas pipe 40 and the backwash fluid feed pipe 44 are closed or capped and no backwash assembly is conn~octed to the bâckwasL cul~ Pntvessel 12. During filtration, all of the control valves except the fluid feed valve 30 and SUBSTITUTE S1 5EET (RULE 26) WO 97/04852 PCT~US9~12621 the filtrate discl~e valve 46 are typically closed. A process fluid to be filtered is illLluduced into the process fluid ~h~mher 16 through the process fluid feed pipe ~ and is passed through filter media of the disposable filter cl ~ lx 20. The filtrate then passes along the hollow interior of the disposable filter elemf~nte 20, through the S openings 54 in the tube sheet 14, and into the filtrate ~ bel 18. The filtrate then leaves the filtrate ch~.-.h~l 18 through the filtrate discharg., pipe 38 and may be collPcte~
in an lmillll$trated l~,se~/oir, for example. Usually, during fi1tration, the process fluid chamber 16 will be completely filled with the process fluid, and the filtrate ch~..hf- 18 will be c~mrhPtf ly filled with filtrate.
With the backwash co~ vessel 12 equipped with disposable filter c~
20, normal filterin~ operation is initi~tPd as described above, and the system is onilo,~d to r~ f' when fouling of the f~ter elPnnPnte 20 occur. ~here are many ways to ~iP t~' ~ I I I;I IP when fouling of the filter elPnnPnf occurs, inrhl~ling lllolliloling of the ~l~,O~ule dirr~,~cl~tidl belweell the inlet and the outlet of the filter system and/or simply 15 eY;....inil-g the filter el~Pnte after a pre~t~ ....;..Pd time. Preferably, a ~ Ul't; sensor is utilized to ~lP~rl ...i..P the ~res~ule dirr~ llLial.
For a given set of process flow ~a.,.l~ for a given a~li~ , a loading condition can be clcl~ P~l for the filter ele~nPnte. The loading ct)n-lition may be ~ ;--Pd accoldillg to a variety of pala~ , but the most p-~r~able ~an~l~ are20 the ~)lCi~:iUle dirreil~lllial across the filter ~l~mPnte and the time interval. For example, the loading condition can be tl~le~ accor~il.g to an acce~Lable range of values for the ~lci,~ulc; diL~lc.lLial for a given period of time. In other words, in a particular filtratit)n applir~titm, after a given period of filtering time, for example one hour, the plcs~ul~ dirr~l~..lial across the disposable filter elements can be cOlll~al~d to a range of 25 ~l~,s~ure dirr;~ .lLials that are acceptable. If the ~ iUl~i dirrelCllLial iS on the high side of this range or higher than this range, then it may reasonably be ~ P~1 that the solids co--~e.~ ion in the fluid is so high that it would be too costly to continue using disposable filter e~ pntc. If the ~-~s~u-c ~lirr~.clllial is on the low side of the range or SUBSTITUTE SHEET (RULE 26) less than the range, then it may be reasonably ~sllmrtl that the solids col-r~ ;oll in the fluid is so low that disposable filter e~ should conLulue to be used. The range of acceptable ~lCS ,u,e dirr~ ials for a given f~tration time period may be ~efe~l~ to as a ~ d~t~-....i..~d loading conf1ition ~A~ l;v~ly~ the loading condition may be del~ rd accol.ling to a rn~ximl~m desirable p,es.,ule dirrcl.,.lLial in an acceptable range of filtration time intervals. In other words, in a particular filtration applir~fiQn, after the m~imllm desirable ~ 7~UlC
dirr~.~,llLial across the disposable filter elements is reached, the filtration tin~Le interval can be cOlll~alc;d to a range of time intervals that are ~ccept~hle. If the time interval is on the high side of ~is range or higher ~an ~is Mnge, ~en it may reasonably be ~ m~d that the solids col~re~ ;on in the fluid is so low that disposable filter elrm~ntc 20 should continue to be used. If the time interval is on the low side of the range or less than the range, then it may reasonably be ~ ...Pd that the solids co..~ n in the fluid is so high that it would be too costly to continue using disposable filter ~ le-nr ~
15 20. The range of acceptable filtration time intervals to reach the ~ .-- desi,àble e~,,ul~ dirre.~llial may also be referred to as a pre-l~t.. i.-Pd loading con-1hion Dep~ ;..g on the loading condition, the fouled disposable filter rlc...~ initially in~t~llPd in the backwash c~ nt~inmPnt vessel 12 may be replaced by clean disposable filter clr~ .lx or clean backwa;,l,able filter elements. Of course, if the loading condition 20 inrlir~tP~ that bachwashable filter elr mPntc should be in~t~ll.od in tne l)achwasl, c~ l vessel 12, it will also be desirable to open or uncap the bachv~,ash-related connections of the backwash vessel 12 and connect the bachwash c~ ont vessel 12 to a backwash assembly. It is important to note that the mol,iloling of the system may be an clllgoing process as conditions may change. For example, if the initial loading 25 con~liti--n~ in-1ic~tP that disposable filter elemPnt~ may still be used, the system may be continnP~l to be llloniLol~d in case the solids co"celll,alion cl~lges over time.
There are many well known bachwash assemblies and bacl~v~asllillg tPchni~ es ., which are erreclive and may be utilized with a hybrid filtration system. In a plt:rt~ d SUBSTITUTE SHEET (RULE 26) elllbo~ f~ the ba.,Lwd~h tçchni~ e may be a gas assisted bacLwa~L teçhniqllp ntili~ir the filtrate as the backwash fluid. Figure 5, ill~ s the hybrid filter system co~ Pclf~d to a backwa;,l~hlg assembly. However, other fluids may be utilized as the bacL~ai,l, fluid. An extF rn~lly supplied bacLwasl, fluid may be stored in a bacLwa~h holding tank 5 conl-Pcled to a backwash feed pipe.
According to one example of a suitable gas assisted bâcLwa~llillg tFe('hniqmP., the process fluid inlet pipe 22 and the filtrate di~cl,alge pipe 38 are closed via valves 30 and 46 and the process fluid is drained to an a~yr~plidle level in the process fluid c~ hfl 16, i.e., below the filter e1Fmlont~ 20. The drain valve 32 is then closed. Control valves 30, 34, 36, 46, and 50 are also closed, thereby sealing pipes 22, 26, 28, 38, and 42.
With these pipes sealed and the filtrate chamber 18 cont~ining the backwash fluid and ypl~s~ P~l, for F~mI)le, via the ylc~ d gas feed pipe 40 the bacLwa~l,able filter ç~ 20 may be backwashed. The filtrate ch~llbel 18 is y~ Pd to any suitable bacLwasl, yr~ulc~ for example, to about seventy to ninety psi. With the f~trate 15 rh~mher 18 yr~s~uli~ed and the backwash liquid ~rcum~ tPcl in the intPrior~ of the filter cl~ .,,F-~Ix 20 and the filtrate cl~...hcr 18, the lower drain valve 32 is opened, venting the process fluid r~ her 16 directly through the lower drain pipe 24, and venting the f~trate ~h~mher 18 through the lower drain pipe 24 via the bacLwasllable filter cl~...f ..l~
20. Acc~l-l~ly, the backwash liquid and the gas in the filtrate challlbcl 18 are forced ~ u2~h the backwashable filter elements 20, dislodging the particulate cake and solids from each bacLwasl,able filter elem~ont 20 and cleaning each bacLwa~l,able filter cl~
20 of particulate matter. The lower drain pipe 24 generally has a larger fli~ f~,.
Larger ~ , drain pipes facilitate the removal of the backwash mqt~ri~l from the backwash filter vessel 12.
The p,~ d gas provides the energy for backwa~hi"g. Any gas which is comp~tihle with the hybrid filter system, the bachwa~l~il,g liquid, and the process fluid may be used. Frequently, colllyl~ssed air or nitrogen is used. In particular, the ;ased yl~ ule in the ffltrate chamber 18 causes a P1~D~U1~ pulse to a~luy~ly force SlJ~g " ~ ~JTE SHEET (RULE 26) WO 97/04852 PCT~US96/12621 the bac~wai,ll liquid a~cllm~ t~l above and in the interiors of the filter c~ 20 to flow in the reverse direction through the backwashable filter ~Ir ~ 1 ~ ; 20 when the drain valve 32 is opened. The force of the uu~waldly flowing bac~wasll liquid dislodges the particulate matter trapped in or near the outer surface of the bac}~w~llal~le filter ~
5 20, and ~e solids matter is blown out the vessel through the drain pipe 24 logt;~r with the backwash liquid.
13dc~wa~1Lul~ may be continuous, rl...cl~ all of the backwash liquid co-.~ r~
in the filtrate rk~ b~ 18 through the filter elom~-nte 20 in one contimlrJlle stream, or (liscolllLl-lous. Por example, after a pre~l~ tc....i~ d period of time or after a 10 ~ .ocl amount of backwash liquid has been flushed through the filter cl~
20, the lower drain valve 32 may then be closed, allowing any backwash liquid in the filtrate rh~mher to fill the interiors of the filter elem~onte. The filtrate fh~-..hel 18 is then l~ple~ 1 and another bac~wd~ g cycle may be initi~tPd Similar bac~.c.sllillg cycles may be c~ d as long as there is sllffiri~ont bac~waslLulg liquid in the second Ch~ll~. or as long as bacLwasl~ g liquid is supplied to the filtrate chamber 18.The hybrid f~ter system of the present invention may be e-luiwed with any suitable "~r~ ;", for ;~ o~ irally (l~ when the bac~w~l~ll liquid is at a suitable level, such as a level sensor disposed in the vessel or a timer. The level of the backwash liquid in the filtrate chamber will depend upon many factors, inrl~ in~ the size 20 of the bac~wasllable filter el~m~ntc and the amount of ba~wa~ liquid which it is desired to flush through the bac~washable filter elem~ntc. For some embodim~ontc, the level of the bacl~wasll liquid may be selected so that the volume of the ba~v~dsll liquid ranges from about one to about ten times the total volume of the interiors of all of the filter cl~
The char~cterictirs of the reverse ~lCS~, pulse, e.g., the .. ~g.~ de of thedirr~ .llialpLe~ul~ b~lweell the filtrate rh~mher 18 and the process fluid challlbe. 16 and the dllration of the pulse, may vary depending on such factors as the ability of the filter elements to wilI.~ reverse ples~ule dLrr~ lials and the desired reverse flow SUBSTITUTE SHEET (RULE 26) , WO 97/04852 PCT~US96112621 velocity for cle~ the filter .ol~m~nt~.
Although what is shown and described is believed to be the most ~ 1 and ~lcÇ~,~lcd embo~ , it is a~al~ L that d~alLul~,s from specific m.~th~ and designs desclibed and shown will suggest themselves to those skilled in the art and may be used S without d~alLillg from the spirit and scope of the invention. The present L~ llion is not le~ d to the particular co~ u~;lions r1P~ ed and illll$t~tPd, but should be co~llued to cohere with all mo~lihr~tion~ that may fall within the scope of the ap~.ld~d claims.

SlJ~S 111 UTE Sl ._~1 (RULE 26)

Claims

WHAT IS CLAIMED:

1. A method for filtering process fluid containing solids comprising:
(a) passing the process fluid into a process fluid chamber of a regenerable filter vessel through an inlet of the regenerable filter vessel:
(b) directing the process fluid through a plurality of disposable filter elements mounted in the process fluid chamber, including loading solids on or in the filter medium of the disposable filter elements;
(c) directing filtrate from the disposable filter elements into a filtrate chamber of the regenerable filter vessel and then through an outlet of the regenerable filter vessel: and (d) depending on a loading condition, either (i) replacing the loaded disposable filter elements with clean disposable filter elements or (ii) replacing the loaded disposable filter elements with clean regenerable filter elements and connecting a backwash system to the regenerable filter vessel.

2. The method for filtering process fluid containing solids according to claim 1, further comprising monitoring the loading condition to determine when fouling of the disposable filter elements occur.

3. The method for filtering process fluid containing solids according to claim 2, wherein the loading condition comprises a pressure differential across the disposable filter elements after a given period of time.

4. The method for filtering process fluid containing solids according to claim 3, wherein if the pressure differential is above a set value after the given period of time, the disposable elements are replaced with clean regenerable filter elements and the regenerable system is connected to the regenerable filter vessel, and if the pressure differential is below the set value after the given period of time, the disposable filter elements are replaced with clean disposable filter elements.

5. The method for filtering process fluid containing solids according to claim 4, wherein if the disposable filter elements are replaced with clean regenerable filter elements, the loading condition continues to be monitored to determine when fouling of the regenerable filter elements occur.

6. The method for filtering process fluid containing solids according to claim 5, wherein if the pressure differential is above a set value after another given period of time, the regenerable filter elements are regenerable and if the pressure differential is substantially below the set value after the given period of time, the regenerable filter elements are replaced with clean disposable filter elements.

7. The method for filtering process fluid containing solids according to claim 2, wherein the loading condition comprises a time interval for a given pressure differential across the disposable filter elements.

8. The method for filtering process fluid containing solids according to claim 7, wherein if the time interval is below a set value for the given pressure differential, the disposable elements are replaced with clean regenerable filter elements and the regenerable system is connected to the regenerable filter vessel, and if the time interval is at or above the set value for the given pressure differential, the disposable filter elements are replaced with clean disposable filter elements.

9. The method for filtering process fluid containing solids according to claim 7, wherein if the disposable filter elements are replaced with clean regenerable filter elements, the loading condition continues to be monitored to determine when fouling of the regenerable filter elements occur.

10. The method for filtering process fluid containing solids according to claim 9, wherein if the time interval is below a set value for the given pressure differential, the regenerable filter elements are regenerated and if the time interval is substantially above the set value for the given pressure differential, the regenerable filter elements are replaced with clean disposable filter elements.

11. The method for filtering process fluid containing solids according to claim 1, wherein replacing the loaded disposable filter elements with clean regenerable filter elements includes mounting to a tubesheet which separates the process fluid chamber and the filtrate chamber of the regenerable filter vessel a plurality of regenerable filter elements greater in number than the number of disposable filter elements being replaced.

12. The method for filtering process fluid containing solids according to claim 6 wherein the regenerable filter vessel and the regenerable filter elements respectively comprise a backwashable filter vessel and backwashable filter elements and wherein regenerating comprises backwashing.

13. The method for filtering process fluid containing solids according to claim 1, wherein replacing the filter elements includes replacing a tube sheet mounted between the process fluid chamber and the filtrate chamber.

14. A method for filtering process fluid containing solids comprising:
(a) passing the process fluid into a process fluid chamber of a regenerable filter vessel through an inlet of the regenerable filter vessel;
(b) directing the process fluid through a plurality of regenerable filter elements mounted in the process fluid chamber, including loading solids on or in the filter medium of the regenerable filter elements;
(c) directing filtrate from the regenerable filter elements into a filtrate chamber of the regenerable filter vessel and then through an outlet of the regenerable filter vessel; and (d) depending on a loading condition, replacing the regenerable filter elements with clean disposable filter elements.

15. A method for filtering process fluid containing solids comprising:
(a) passing the process fluid into a process fluid chamber of a regenerable filter vessel through an inlet of the regenerable filter vessel;
(b) directing the process fluid through a plurality of disposable filter elements mounted in the process fluid chamber, including loading solids on or in the filter medium of the disposable filter elements;
(c) directing filtrate from the disposable filter elements into a filtrate chamber of the regenerable filter vessel and then through an outlet of the regenerable filter vessel; and (d) replacing the loaded disposable filter elements with clean regenerable filter elements and connecting a backwash system to the regenerable filter vessel.

16. A hybrid filter assembly comprising:
(a) a regenerable containment vessel having a process fluid chamber and a filtrate chamber, the regenerable containment vessel including an inlet communicating with the process fluid chamber, a drain communicating with the process fluid chamber and sized to drain process fluid, regeneration and filter element deposits from the process fluid chamber, an outlet communicating with the filtrate chamber, and a regeneration-related port communicating with the filtrate chamber, the regeneration-related port being capped;
(b) a tube sheet mounted between the process fluid chamber and the filtrate chamber of the regenerable containment vessel and providing a barrier between the process fluid chamber and the filtrate chamber, the tube sheet having a plurality of openings; and (c) a plurality of disposable filter elements mounted to the tube sheet and extending into the process fluid chamber of the containment vessel, each disposable filter element comprising an open end and a filter medium, each disposable filter element being associated with an opening in the tube sheet wherein the open end of the disposable filter element communicates with the filtrate chamber of the regenerable containment vessel.

17. The hybrid filter assembly according to claim 16, wherein at least one of the process fluid chamber and the filtrate chamber comprise a sealable access port.

18. The hybrid filter assembly according to claim 16, wherein the tube sheet is removably mounted to the regenerable containment vessel.

19. The hybrid filter assembly according to claim 16, further comprising a hold-down plate for securing the plurality of disposable filter elements to the tube sheet.

20. The hybrid filter assembly according to claim 16, wherein the plurality of openings in the tube sheet are sized to couple with the plurality of disposable filter elements and with a plurality of regenerable filter elements.

21. The hybrid filter assembly according to claim 20, further comprising adapters for connecting disposable and regenerable filter elements to the tube sheet.

22. The hybrid filter assembly according to claim 16, further comprising blind adapters for preventing fluid from passing through at least one of the openings in the tube sheet when the number of filter elements is less than the number of openings in the tube sheet.