US3808120A

US3808120A - Tar sands bitumen froth treatment

Info

Publication number: US3808120A
Application number: US00377239A
Authority: US
Inventors: R Smith
Original assignee: Atlantic Richfield Co
Current assignee: Atlantic Richfield Co
Priority date: 1973-07-09
Filing date: 1973-07-09
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: CA993827A

Abstract

A METHOD FOR TREATING TAR SANDS BITUMEN FROTH WHEREIN THE FROTH IS TREATED IN AT LEAST ONE CYCLONE ZONE AFTER WHICH IT IS TREATED IN AT LEAST TWO CENTRIFUGE ZONES, THEREBY SEPARATING FROM THE FROTH AT LEAS WATER AND SOLID MINERAL PARTICLES AND LEAVING A BITUMEN PRODUCT FOR FURTHER PROCESSING.

Description

April 30, 1974 R, H, SWTH' v 3,803,120

' TAR SANDS BITUMEN FROTH- TREATMENT I Filed July 1975 2 Sheets-Sheet 1' D/LUENT B/TUMEN D/LUENT 6 PRODUC/ FIRST 11 CYCLONE THIRD FEED CENTR/FUGE B/TUMEN ZONE 2 ZONE UNDERFLOW- nFROTH FIRST SECOND UNDERFLOW UNDERFLOW FIG. 7

PRODUCT.

THIRD FIRST {UNDERFLO 23 CENTR/FUGE g I CYCLONE FEED N 2/. SECOND 3 V UNDERFLOW D/LUENT FIG. 2

D/LUENT FIRST UNDERFLOW FIG. 5 52 41 April 30, 1974 Filed July 1973 D/LUENT FIRST CE N TR/F U GE ZONE CYCLONE R. H. SMITH TAR SANDS BITUMEN FROTH TREATMENT 2 Sheets-Sheet 2 Rooucr SECOND CENTRI- F UGE ZONE THIRD CENTR/FUGE ZONE FIG. 4

FIRST CENTR/FUGE ZONE A FIRST CENTR/FUGE ZONE B- FIG. 6

46 SECOND CENTRI- FUGE T ZONE 47 SECOND CENTRI- FUGE ZOAVE 45 United States Patent O 3,808,120 TAR SANDS BITUMEN FROTH TREATMENT Robert H. Smith, Richardson, Tex., assignor to Atlantic Richfield Company, Los Angeles, Calif. Filed July 9, 1973, Ser. No. 377,239 Int. Cl. C10g 1/04 U.S. Cl. 208-11 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to an improvement in the separation of at least water and solid particles from the froth produced in a hot Water process for separating bitumen from bituminous tar sands.

The froth from this hot Water process generally contains from about 35 to about 45 weight percent water and from about to about weight percent solid mineral particles (coarse and fine) before any dilution. The water content of this froth is normally reduced to from about 4 to about 6 weight percent and the particles to from about 1 to about 2, weight percent to produce a bitumen product suitable for further processing. This reduction of water and solids can be accomplished by a plural stage centrifuging system which uses mechanical centrifuges operated by powerful motors to create a strong centrifugal force to separate water and solid particles, and diluent if present and different from water, from the bitumen froth.

In such a system the first stages of centrifuging are conducted by the application of relatively low forces to remove coarse mineral particles, e.g., greater than about 5 microns in size, while relatively higher forces are applied in the later stages of centrifugation to remove fine mineral particles, e.g., generally equal to or less than 5 microns in size, and most of the water. The particles and water discharged from the centrifuges are removed from the system and are treated for the separation therefrom of any diluent present (if different from water) and for disposal.

In this invention, reference to particle size means the diameter of the particle if it is essentially round or the largest cross-sectional dimension of the particle if it is not essentially round.

Thus, heretofore, separation of water and particles has been achieved in its entirety by the use of large expensive centrifuges which require a large amount of energy input as well as capital expense. Such centrifuges include discnozzle centrifuges, solid-bowl centrifuges, and the like, and are normally employed in the industry to remove solids from liquids.

SUMMARY OF THE INVENTION According to this invention, part of the centrifuges heretofore used in the treatment of tar sands froth are eliminated thereby providing a substantial savings in capital expense and operating expense. This is accomplished by subjecting the froth, upstream of any centrifuging zone, to at least one cyclone settling zone in which the froth is tangentially injected into the cyclone zone so that it moves in a circular manner as it also moves downwardly under the force of gravity thereby using a centrifugal force, which is not mechanically generated as with centrifuges, to amplify the settling rate of solids and water p CC from the froth. Cyclones are not in the industry considered to be centrifuges, for example, see Unit Operations of Chemical Engineering, by McCabe and Smith, McGraw-Hill Book Company, Inc., New York, 1956, page 394. Also, although it is known to use cyclones in the separation of solids from liquids, cyclones are normally used to remove solid particles or liquid drops from gases.

In this way, substantial amounts of the more easily separated water and solid particles, particularly coarse particles, are removed by cyclone settling prior to treatment in centrifuging zones thereby decreasing the volume of material which the centrifuging zones must operate on. This allows the use of smaller numbers and/or smaller sizes of centrifuges in each centrifuging zone as hereinafter described.

This invention also provides a method for reducing bitumen losses by the use of countercurrent washing of cyclone underflows with diluent which is lower boiling than bitumen. Bitumen is thus replaced by the diluent which can be recovered by distillation.

Accordingly, it is an object of this invention to provide a new and improved method for treating tar sands bitumen froth. It is another object to provide a new and improved method for separating solid particles from bitumen froth. It is another object to provide a new and improved method for treating a bitumen froth prior to centrifuging of same. It is another object to provide a new and improved method for removing water, solid particles, and diluent if any, from a bitumen froth. It is another object to reduce bitumen losses.

Other aspects, objects and advantages of this invention will be apparent to those skilled in the art from this disclosure and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows one embodiment within this invention wherein a cyclone settling zone precedes first and second centrifuging zones.

FIG. 2 shows another embodiment within this invention wherein a plurality of cyclone settling zones precedes first and second centrifuging zones.

FIG. 3 shows another embodiment within this invention wherein a cyclone settling zone precedes three centrifuging zones.

FIG. 4 shows an embodiment within this invention wherein a plurality of first and second centrifuging zones are employed in lieu of single first and second centrifuging zones as shown in FIGS. 1 and 2.

FIG. 5 shows an embodiment within this invention wherein a plurality of centrifuges are employed as can be done in any of the centrifuging zones shown for FIGS. 1 through 4.

-FIG. 6 shows a simplified form of a cyclone separator.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a feed bitumen froth passing by way of pipe 1 into cyclone settling zone 2. The froth contains bitumen, water, coarse and fine mineral particles, diluent if different from water (e.g., a hydrocarbon diluent such as naphtha). Diluent is added by way of pipe 3. Cyclone zone 2 separates out from the froth some particles, particularlycoarse particles, and some water to produce a first underflow in pipe 4. The underflow is removed from the froth thereby creating a bitumen enriched material which remains and is removed by way of pipe 5 as a first overhead. Diluent may or may not be added to this first overhead by way of pipe 6. There can be one or more cyclone zones 2 and each zone can contain one or more cyclone devices as desired. Thus, a substantial amount of relatively easily removable solids and water is settled from the froth feed prior to passing that froth into any centrifuge zone. This way the bitumen enriched material in pipe 5 is already reduced in materials to be separated so that first centrifuge zone 7 which feeds on material in pipe 5 can be sized and operated to more efficiently remove a certain class of materials such as remaining coarse particles and some water. The particles and water, and any diluent if present, are removed in a second underflow by way of pipe 8 thereby forming a bitumen rich overhead which is removed as second overhead in pipe 9 and passes as feed to a second centrifuge zone 10.

There can be one or more first centrifuge zones 7 and each can contain one or more centrifuge machines. Preferably, first zone 7 removes most of the remaining coarse particles and is a centrifuge of the solid-bowl or scrolltype.

Second centrifuge zone 10 is preferably designed to remove a substantial amount of the remaining fine particles and a substantial amount of water and therefore can employ centrifuges of the disc-nozzle type. As with zone 7, there can be one or more zones 10 and each zone can contain one or more centrifuges. Zone 10 removes a substantial amount of water and fine particles, and possibly some residual coarse particles and diluent if any, from the process by way of pipe 11 thereby leaving a bitumen product as the overhead from zone 10. This product is removed separately by way of pipe 12 from the third underflow in pipe 11 for further processing as desired.

FIG. 2 shows a modification within this invention wherein three cyclone zones A, B, and C are employed in series so that the underflow from zone A in pipe 20 is employed as feed for zone B and the underflow from zone B in pipe 21 is employed as feed for zone C, diluent being added to pipe 21 by way of pipe 22 if desired. The overhead from zone A is passed by way of pipe 23 as feed for first centrifuge zone 7. The overhead from zone B is returned as at least part of the feed for zone A by way of pipe 24. The overhead from zone C is returned by way of pipe 25 as at least part of the feed for zone B. The second underflow from first zone 7 is passed by way of pipe 26 to be combined with the first underflow from zone C in pipe 27 and these combined underflows pass by way of pipe 28 to be combined with the third underflow in pipe 11 to produce a final combined underflow in pipe 29 which is removed from the process and disposed of as desired. Again, each of cyclone settling zones A through C can contain one or more cyclone settlers hooked in series in the same manner as the series hookup shown for zone A through C of this FIG. 2.

This configuration of cyclone zones provides a method of countercurrent washing to reduce the loss of bitumen in the tailings stream 29. At each cyclone stage, except the last, the feed is mixed with the overflow stream from the succeeding cyclone zone. Fresh diluent is added to the feed to the last cyclone zone. The overflow streamwhich is combined with each feed has a lower bitumen content than the feed. As a result, most of the bitumen is dissolved in diluent and removed in the overflow of the liquid cyclone. The bitumen content in the underflow from each zone is therefore lower than that from the preceding zone. Bitumen in the feed to each zone is replaced by diluent in the underflow, and the diluent can be easily recovered by distillation and the like.

FIG. 3 shows apparatus similar to that of FIG. 1 except that a third centrifuge zone 30 is employed to operate on the underflow 31 from first centrifuge zone 7. Diluent may or may not be added to the underflow from zone 7 by way of pipe 32. The underflow from third zone 30 is removed by way of pipe 33, e.g., combined with the underflow in pipe 4 for joint disposal. The fourth underflow in pipe 33 will contain yet additional amounts of water, particles, and diluent if any, and the more purified material remaining in third zone 7 is removed as overhead therefrom by way of pipe 34 for further treatment in second centrifuge zone 10. Thus, in this embodiment, part of the valuable bitumen in the underflow in pipe 31 is reclaimed by third centrifuge zone and returned to the process by way of pipe 34. Since zone 30 is employed as a cleanup zone, part or all of the third underflow in pipe 11 can be returned by way of pipe 35 as at least part of the feed for zone 30 thereby reclaiming residual bitumen from the third underflow in pipe 11 for return to the process by way of pipe 34. Any part of the third underflow in pipe 11 not returned by way of pipe 35 to zone 30 is removed from the system by way of pipe 36.

FIG. 4 shows an alternative which can be employed in any of FIGS. 1 through 3 or any other embodiments within this invention wherein a plurality of first centrifuge zones and/or a plurality of second centrifuge zones are employed. In this figure the overflow from a cyclone zone such as pipe 5 of FIGS. 1 and 3, pipe 23 of FIG. 2, and the like, is represented as a feed for first centrifuge zone A in pipe 40 of FIG. 4. Zone A produces an underflow in pipe 41 and an overflow in pipe 42. Overflow 42 is used as feed for first centrifuge zone B which in turn produces an underflow in pipe 43 and an overflow in pipe 44. The overflow in pipe 44 is used as feed for second centrifuge zone A which produces an underflow in pipe 45 and an overflow in pipe 46. O'verfiow 46 is used as feed for second centrifuge zone b which produces an underflow in pipe 47 and a bitumen product in pipe 48.

,FIG. 5 shows a series coupling of two centrifuge machines which is similar to the series coupling of cyclone zones A through C in FIG. 2. The series coupling of two or more centrifuge machines as shown in FIG. 5 can be employed in any centrifuge zone shown in FIGS. 1 through 4. For example, taking the apparatus of FIG. 5 as that which is within first centrifuge zone A of FIG. 4, the feed to the first centrifuge 50 is in pipe 40. Centrifuge 50 produces an overflow which is passed into pipe 42 for transmittal to first centrifuge zone B of FIG. 4, and also produces an underflow in pipe 52 which is passed to the second centrifuge 53 in zone A. Centrifuge 50 produces an underflow in pipe 41, which is the under-flow for zone A as shown in FIG. 4, and an overflow in pipe 55 which is returned as at least part of the feed for centrifuge 50. This sort of series hookup with two or more machines can also be employed in first centrifuge zone B, second centrifuge zone A, and/or second centrifuge zone B, of FIG. 4. Similar reasoning also applies to the other centrifuge zones in FIGS. 1 through 3.

FIG. '6 shows a simplified apparatus for a cyclone device wherein the froth feed 60 passes into the cyclone at the top of a spiral chamber 61 so that as the froth moves downwardly under the force of gravity some centrifugal force is applied to the froth to amplify the settling rate of the solids and water from the froth. Therefore, at the bottom of chamber 61, by use of a physical divider 62, a stream of water and solids 63 is removed separately from the bitumen enriched stream 64. Other known cyclone devices can be employed, for example, those disclosed starting at page 366 of Unit Operations of Chemical Engineering, supra.

Example Bitumen froth feed composed of 63 weight percent bitumen, 9 weight percent solid particles (coarse and fine), 28 weight percent water, all weight percents being based on the total weight of the feed, is treated in the system shown in FIG. 1 wherein naphtha diluent is added to the froth and passed first through a cyclone settling zone 2 produce a first underflow 4 containing, based on the first underflow, 51 weight percent coarse particles, 6 weight percent bitumen, 3 weight percent naphtha and the remainder water. The bitumen enriched overhead in pipe 5 passes into a scroll-type centrifuge which constitutes first centrifuge zone 7 and hich produces a second underflow 8 which contains, based on the second underfiow, 63 weight percent coarse solids, 4 weight percent bitumen, 2 weight percent naphtha, and the remainder water. The bitumen rich overhead from zone 7 is then passed to second centrifuge zone which contains a disc-nozzle centrifuge and which produces a third underflow 9 containing, based on the third underflow, 6 weight percent fine particles, 2 weight percent bitumen, 1 weight percent naphtha and the remainder water. The bitumen product in the overhead from second centrifuge zone 10 contains, based on the bitumen product, 60 weight percent bitumen, 36 weight percent naphtha, 0.6 weight percent solid mineral particles (coarse and fine) and 3 weight percent water, all weight percents being based on the total weight of the overhead in pipe 12.

By use of cyclone settling zone 2, a single centrifuge machine of modest size is employed in each of

zones

7 and 10 the desired degree of removal of water and solids from the bitumen froth still obtained.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from the spirit and scope of this invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

1. A method for treating a tar sands bitumen froth which includes bitumen, water, coarse mineral particles, and fine mineral particles to separate substantial amounts of at least water and coarse and fine particles from the bitumen comprising passing said froth through at least one cyclone settling zone to remove a first underflow which includes water and coarse particles and to leave a bitumen enriched first overflow, passing said first overflow through at least one first centrifuging zone to remove a second underfiow which includes additional water and coarse particles and to leave a second bitumen rich overflow, passing said second overflow through at least one second centrifuge zone to remove a third underfiow which includes water and fine particles and to leave a bitumen product, and removing said bitumen product separate from said third underflow.

2. A method according to claim 1 wherein a hydrocarbon diluent is added to the process upstream of said cyclone zone, upstream of said first centrifuge zone, or upstream of both said zones.

3. A method according to claim 1 wherein at least two cyclones are employed in each cyclone zone, said zones being employed in series so that the overflow from any cyclone subsequent to the first cyclone in the series is recycled as at least part of the feed for the next preceding cyclone.

4. A method according to claim 3 wherein the underflow from the last cyclone of said series is removed from the process.

5. A method according to claim 3 wherein diluent is added to the feed of the first cyclone in said series, to the feed of the last cyclone in said series, or to both such feeds.

6. A method according to claim 1 wherein each first centrifuge zone employs at least one solid bowl centrifuge and each second centrifuge zone employs at least one discnozzle centrifuge.

7. A method according to claim 1 wherein there is employed at least one third centrifuge zone, the feed for said third centrifuge zone being said second underflow, the overflow from said third centrifuge zone being employed at least in part as feed for said second centrifuge zone, the underfiow from said third centrifuge zone being removed from the process.

8. A method according to claim 7 wherein diluent is added to the feed of said cyclone zone, the feed of said third centrifuge zone, or both said feeds.

9. A method according to claim 7 wherein the underflow from said second centrifuge zone is at least in part returned as at least part of the feed to said third centrifuge zone.

10. A method according to claim 7 wherein at least two cyclones are employed in each cyclone zone, said cyclones being employed in series so that the overflow from any cyclone subsequent to the first cyclone in the series is recycled as at least part of the feed for the next preceding cyclone.

11. A method according to claim 10 wherein the underflow from the last cyclone of said series is removed from the process.

12. A method according to claim 10 wherein diluent is added to the feed of the first cyclone in said series, to the feed of the last cyclone in said series, or to both such feeds.

References Cited UNITED STATES PATENTS 3,338,814 8/1967 Given et al. 20811 3,558,469 1/1971 White et a1. 20811 3,607,720 9/1971 Paulson 20811 CURTIS R. DAVIS, Primary Examiner