CA1321556C

CA1321556C - Liquid separator

Info

Publication number: CA1321556C
Application number: CA000615165A
Authority: CA
Inventors: Charles Michael Kalnins
Original assignee: Conoco Specialty Products Inc
Current assignee: Baker Hughes Ltd
Priority date: 1989-09-29
Filing date: 1989-09-29
Publication date: 1993-08-24
Anticipated expiration: 2010-08-24

Abstract

LIQUID SEPARATOR

ABSTRACT
Liquid Separator and method of separating liquids, such as oil and water in a mixture thereof by use of a hydrocyclone (10). A less dense component of the mixture separated by the hydrocyclone is passes to a filter device (100) for further separation.

Description

~IQUID 8EPARATOR

This invention relates to a li~uid separator.

The invention generally envisages the use of a h~drocyclone to ~ra-condition a mi~ture before admission to a filter device, ~uch as an act~ated charcoal reverse osmosi8 filtex device.

In one aspect, there i~ provided a liquid separator comprising a hydrocyclone having a separat~ng chamber with an ~nlet for inlet o mi2ture to be separated, an over10w outlet for outlet of a le~s dense component of tha misture and an underflow outlet for outlet of a more dense component of said misture, and a filter device coupled to receive outlet from saia underflow outlet. The hydrocyclone i8 in this case effecti~e in u~e to effect a pres3ure reauction in the material emergin~ from said underflow outlet, a8 compared to presJure of said mi~ture at said inlet, whereby to acilitate any of said less den~e component present in ~olution in sai~
more dense component breaking out of solution to be either carriod to said overflow outlet or to emerge from the underflow outlet with the more dense component, as droplets thereof in the more dense component, the filter aevice effecting further separation of 8ai~ aroplets from the more den~e component.

The mi~ture to be separated may be passea to a mi~ing and~or resiaence vessel, such as a coalescer or precoalescer, for e~ample a cross plate interceptor s~immer before pa~age to the hy~rocyclone. In such case, provision may be maae for in~ection of heatea fluia, such as water, to the ~essel, such as periodically.

The invention also proviaes a method for separating component~ of a liquia mi~ture one fr~m the other by use of hyarocyclone to which the mi~ture i~ admitt8d, the hydrocyclone being operated whereby ~ less dense component of the mi~ture emerges from an outlet of the hydrocyclono in the form o ~roplets in a more aense component of the mi~ture, the material emerging from the outlet being admitted to a filter devico to effoct further separatlon thereof.

The invention is further aescribea ffl way of e~amplo only with reference to the accompanyinq ar~wlng~ ln whlch:

Figure I i8 a flow diagram of a liquid ; 1 32 1 556 separator construct~d in accordance with the invention; and Figure 2 i8 a diagram showing a hydrocyclone used in the ap~aratus of Figure l; and.
Figure 3 is a flow diagram of a further liquid separator constructed in accordance with the invention.

~ he liquid separator shown in Figure 1 compri~es a m~ing and~or residence ve~sel.9O to whieh a misture of oil in water is admitted sueh as on the line 92 ~hown. The mi~ture is then taken on line 42 to a hydrocyclone 10 to pro~ide at an outlet line 44 separated oil and at an outlet line 46 ~eparated water whieh may, however, still contain 80me residual oil. The water component i~ passed on line 46 through a presæure reducing de~ica 50 and thenee on a line 52 to a filter device 100. Here, further separation occurs with the water component be~ng taken on a line 58 from the device 100.

The hydrocyclone 10 may be eonstructed in known fash~cn, such as in accordance with the teachings of United States patent 4,237,006, Australian patent application 84713~79, or in my International application~ PCT~AU83~00028 or PCT~AV85~00010. Figure 2 shows, diagrammatically, a 8eparator of thi~ gener~l type. Thi~ is shown as ha~ing a tapered elongate ~eparating chamber 25 which 18 of eireular eross-seetion ha~ing, at it~ larger diameter end, a irst cylindrieal portion 12, a tangential inlet 26 ha~ing an inlet opening 30, and an asial o~erflow outlet 34 which communicates w~th an outlet opening 32. A tapered portlon 12a of separating chamber 25 i8 provided ad~acent port~on 12, this leading to a second, also slightly tapered, portion 14 of the separating chamber 25, this in turn leading to an elongate cylindrical portion 16 of the separating chamber which open~ to an a~ial underflow outlet 23 for the separator.

Olly wator misture to be separated is pas~ed on the inlet 26 through the inlet opening 30 into the portion 12 of the separatins chamber 25 80 as to generate a vortes within the ~eparating chamber. The oil component emerges from the outlet 34 via opening 32 and the water component emerges from the underflow outlot 23.

As shown, the first portion 12 ha~ a length ll and a diameter dl, the second portion has a length 12 and diameter d2 at its larger diameter end, port~on 16 has a lenqth 13 and a diameter d3, whilst the overflow outlet has a diameter do~ A~ de~cribed in Australian patent application 847l3~79, two or more strictly tangent~al inlets 26 may for e~ample be provided or, as shown in International application PCT~AU85~00010, a single inlet 26 of involute form may be provided.

In ~ccordance with the above described construction, the cyclone separator may be con~tructed in accordanco with any one or more or all of the following dimensional constraints.

12~d2 ~ 10, such as 10 ~ 12~d2 ~ 25 ~ ~i d2 ~ 30 ~.
such as 3 ~ ~ d~ d2 ~ 20 4Ai do~d2 ~ 0.25~ ~uch as do~2 ~ 0.1 dl > a2 d2 a d3 where Ai i8 th~ total inlet area of all o the inl~t openingæ combined or the ~nlet opening i~ there i8 only one. ~, the half angle of th~ taper of ~he second portion, may ba 20' to 2, such as 1-.
Portion 12a is optional. If provided, it may h~
half angl~, a, of 10-. ~

Other ~uitable constructions for hydrocyclone 10 flre shown, for ~ample/ in the specification of Australian patent application 77610~87 and of International ~pplications PCT~AU87~00402, PCr~AU86/00313, PCT~AU86~00173 and PCT~AU85~00181.

In the constructlon shown in Figure 2, the overflow outlat 23 communic~te~ with a fourth portlon 18 of the separator, whlch ha8 the effect of providing a back pres3ure to acilitate the 132~556 separating action. Such a fourth portion 18 aescribed in IntornationJl application PCT~AU83~00028 and may, a8 shown, comprise a ~rst fru~toconical port~on 18a which leads from outlet 23 followed by a second cylindrical portion 18b. When used in the apparatus of Figure 1, this arrangement provide~ a pressure roducing action and permits omi~sion of the pres~ure reducing de~ice 50, line 46 in that case communicating direetly with line 52 to admit material from the separator 10 direetly to the filter device 100 .

The hydrocyclone 10 acts, as described, to effect removal of an oil componont from an oily-water misture when admitted thereto. Generally, the separator 10 is designea for use where there i8 a substantially smaller amount of oil than water in the incoming misture. However, the concentration of oil may bo of the order of several percent for esample.

After admission through vessel 90, the hydrocyclono 10 is able to reduce the oil concentration to a guite low level in the water component which emerges from the outlot thereof, such a8 below S00 ppm. Thon, after passage through the pressuro reducing device 50 or through the portion 18 of the described hydrocyclone, the oily water a8 then passed to the filter device 100 is furthor separated to rd uce the oil eomponent to an even lower level.
~hu~, the emergent water from line 58 may be r-latively very pure indeed, such as having an oil concentration of only a few parts per milllon.

The filter deYice 100 may of any suitable type such as an activated charcoal and~or reverse osmosis type. Activated clay filters may also be used.

The prov~sion of the hydrocyclone 10, in add~tion to providing a separ~ting action, al80 a~4i~t8 ~n that a sub~tantial prs~surs dro~ will no~mally esist as between th~ inlet line 42 an~ the outlet 23 from the separator. Thls reduction in pre~ure, which may for esample be 50%, has the efect that oil in ~olution in the water will tend to come out of ~olution snd form ~roplets which, even if they are not separated totally in the cyclone 10, emer~e from the outlet line 44, and can be mor~
read$1y saparated from the water component in the de~ice 100.

The pressuro reducing devlce 50, although preferable, may be omitted in some instances, as indicated. It i8 al80 possible to u~e, a~ the pressure reducing devic~e, ~ suitable valve or, lf ~esired, another hydrocyclone, particularly one designsd to remove solids from admitted liquid. The vessel gO may al80 be elimlnated in some instances.

Ths ~escr~bed mi~ing an~or residence vessel 90 may comprise a precoalescar or coalescer, for example a cross-plate lnterceptor skimmer. It i8 al~o posslble in some instances to facilitate operation by positioning a low shear pressure increaslng flevice either in line 92, to ~ct on the lnlet misture prior to entering the vessel 90, or in .

; ~

line 42 to act on mi~ture having left vessel 90 prior to entry into hydrocyelone 10. By the term ~low shear pressure increasing device~ is meant any pre~suro increasing devico, such a~ a pump effectivo to inerease liquid pre~sure without inducing substantial shear ~tress in the liquid.

Figure 3 shows a further apparatus eonstrueted in aeeor~anee with the in~ntion. Thi~
i~ similar to the previou~ly deseribed apparatus, but i~ de~igned speeifieally for roeovery of water from an oily water misture. The oily water mi~ture is first passed to a free water knoekout tank 200, which effeets partial separation of water and oil eomponents by settlement. The more dense water, typieally eontaining 2000 ppm oil, is taken on a line 202 to a mising and~or residence vessel in the form of a cross plate intereeptor skimmer 204. A heater treater 207 is also provided, this providing heated water, such a8 water recovered from oil-water misturos elsewhere in a processing plant. The treated water is passed, ~uch a5 periodically, on a line 206 to mis with the water from tank 200 on lino 202. The ~o mised water is that which i5 passed to the ~kimmor 204. The skimmer has provision for take-off of ro~eet oil on a line 208 through ~
~uitable valvo 210. 8eparated water, typically eontaining 160 ppm i8 taken out on a line 212 and pumped, via a pump 214, to the inlet of a hydroeyelone 216, on a line 218. Removed oil from the water ontering the hydrocyclone is taken via a valvo 220 on a line 222 to be taken, toqether with the removed oil passing from valve 210, from the apparatus, on a line 224. The water emerging from i321556 the hydrocyclone 16, typically haYing an oil content of 10 ppm, i8 passea on a line 226 via a ~al~e 228 to a filter de~iee 100, ~s p~e~iously described.
Removed water i8 then taken on a line 228 to a suitable so~tener devioe 230 and may be then used, for esample, in ~ ~team generator 232 to which the water i8 applied on a l~ne 234.

The apparstus shown in Figure 3 i8 controll~ ueh a8 eleetronieally, from a suitable control dev~ce 250 which, in addition to controlling ~alves 210, 220 and 228, also controls the rate of pumping of the pump 214 and i8 effective via a suitable level control device 256 to control the liquia le~el in the skimmer 204.

The provision of heater treater 207 has been found to be particularly useful in providing a supply of hoated water which facilitates the action of the sk~mmer 204. ~he heater treater may, in particular, apply heated water periodically to the skimmer.

~ he deseribed arrangement has been advaneed merely by way of e~planation ana many modificatio~8 may be made thereto without ~eparting from the spirit and scope of the invention as defined in the appended elaims.

Claims

Claim 1. A separator for separating oil and water components of a fluid mixture wherein the oil component is comprised of droplets of a less dense phase in a more dense water phase, and wherein it is desired to ultimately provide a water phase which is substantially free of oil, comprising: a hydrocyclone designed, constructed and arranged to effect separation of an oil component form a water component of an inletted fluid mixture, having a separating chamber with an inlet for inlet of the fluid mixture to be separated, an overflow outlet means for outlet of less dense components of the mixture and an underflow outlet means for outlet of a more dense component of said mixture, and a filter device coupled to receive outlet from said underflow outlet means and designed for removing any remaining less dense components of the mixture from the more dense component to provide a water phase that is substantially free of oil, with the outlet of less dense and more dense components from said overflow and underflow outlet means, respectively, being arranged to follow separated flow paths so that the less dense components outletting from the overflow outlet means is not passed into said filter device for contact with the more dense component of the mixture outletting from the underflow outlet means, and outlet passage which remaining less dense components of the mixture have been substantially removed.
Claim 2. A separator system comprising a hydrocyclone designed, constructed and arranged to effect separation of an oil component from a water component of an inletted fluid mixture, having a separating chamber with an inlet for inlet of mixture to be separated, an overflow outlet means for outlet of a less dense component of the mixture and an underflow outlet means for outlet of a more dense component of said mixture, and a filter device coupled to receive outlet from said underflow outlet means whereby the hydrocyclone is in use effective to effect a pressure reduction in the material emerging from said underflow outlet means, as compared to pressure of said mixture at said inlet, thereby being designed to facilitate any of said less dense component present in solution in said more dense component breaking out of solution to be either carried to said overflow outlet means or to emerge from the underflow outlet means with the more dense component, as droplets thereof in the more dense component, the filter device being designed to effect further separation of said droplets from the more dense component, said separator system being arranged to pass the less dense component from said overflow outlet means without being received by said filter device, and outlet passage means on said filter device for passing the water component from which remaining less dense components of the mixture have been substantially removed.
Claim 3. A liquid separator as claimed in Claim 1 including a pressure reducing device arranged so that the material from said underflow outlet means is passed therethrough before admission to said filter device.
Claim 4. A liquid separator for separating oil and water components of a liquid mixture wherein the oil component is comprised of droplets of a less dense phase in a more dense water phase, and wherein it is desired to ultimately provide a water phase which is substantially free of oil, comprising; a hydrocyclone having a separating chamber with an inlet means for inlet of a liquid mixture to be separated, an overflow outlet means for outlet of less dense components of the mixture and an underflow outlet means for outlet of a more dense component of said mixture, and filter device means coupled to receive outlet from said underflow outlet means for removing any remaining less dense components of the mixture from the more dense component to provide a water phase that is substantially free of oil, and further including a residence vessel through which the liquid mixture to be separated is passed, prior to admission to the hydrocyclone, for coalescing in part at least one of the components of the mixture upstream of the hydrocyclone inlet means.
Claim 5. A liquid separator as claimed in Claim 1,2 or 3 wherein said filter device comprises one or more of the following: a reverse osmosis filter, an activated clay filter or an activated charcoal filter.
Claim 6. A liquid separator as claimed in Claim 4 wherein said residence vessel, included means for inlet into the liquid mixture therein of heated fluid.
Claim 7. A method for separating oil and water components of a liquid mixture one from the other by use of a hydrocyclone to which the mixture is admitted, the hydrocyclone having overflow and underflow outlets and being operated whereby a less dense oil component of the mixture emerges from the underflow outlet of the hydrocyclone in the form of droplets in a more dense water component of the mixture, the material emerging from the underflow outlet being admitted to a filter device to effect further separation thereof; and passing a less dense component of the mixture from the overflow outlet through a flowpath that does not admit a less dense component emerging from the overflow outlet to the filter device.
Claim 8. A method as claimed in Claim 7 wherein said filter device comprises one or more of the following: an activated charcoal filter, a reverse osmosis filter, or an activated clay filter.
Claim 9. A method as claimed in Claim 7 wherein said material emerging from the hydrocyclone underflow is passed through a pressure reducing device before entering said filter device.
Claim 10. A method for separating oil and water components of a liquid mixture one from the other by use of a hydrocyclone to which the mixture is admitted, the hydrocyclone being operated whereby a less dense oil component of the mixture emerges from an outlet of the hydrocyclone in the form of droplets in a more dense water component of the mixture, the material emerging from the outlet being admitted to a filter device to effect further separation thereof, wherein said mixture is passed through a residence vessel before admission to said hydrocyclone, and coalescing, in part, at least one component of the mixture in the residence vessel.
Claim 11. A method as claimed in Claim 10 wherein said residence vessel comprises a mixing device and further including mixing the mixture therein the aid in coalescence.
Claim 12. A method as claimed in claim 10 and further comprising introducing into the mixture in said residence vessel, chemicals to coalesce the mixture.
Claim 13. A method as claimed in Claim 10 and further comprising inletting into the residence vessel, heated liquid or other heated fluid, to mix with the mixture therein.
Claim 14. A method for separating oil and water components of an oil and water mixture wherein the oil component is comprised of droplets of a less dense phase and the water component represents a more dense phase of the mixture, and wherein it is desired to ultimately provide a water phase which is substantially free of oil, comprising the steps of:
passing the mixture to a separation vessel to effect partial gravity separation of the mixture into at least an oil phase an oily water phase;
passing the oily water phase from the separation vessel to further separation processes including a hydrocyclone downstream of said separation vessel, said hydrocyclone having outputs of a less dense oil component and more dense water component with droplets of oil therein to form an oily water outlet stream;
passing the oily water outlet stream from the hydrocyclone to a filter device to further remove oil droplets therefrom and thereby provide a water phase that is substantially free of oil.
15. The method of Claim 14 and further including passing the oily water phase from the separation vessel to a residence vessel for at least partially coalescing droplets of the less dense phase of the mixture prior to passing the mixture to said hydrocyclone.
16. The method of Claim 14 and further including reducing the pressure of the oily water outlet stream downstream of the hydrocyclone to aid in removing any remainder of the less dense phase out of the more dense water phase.
17. The method of Claim 15 and further including passing heated fluids to the said residence vessel for aiding in the coalescing of droplets of the less dense phase of the mixture.