CA1293465C - Purification process for bitumen froth - Google Patents
Purification process for bitumen frothInfo
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- CA1293465C CA1293465C CA 558097 CA558097A CA1293465C CA 1293465 C CA1293465 C CA 1293465C CA 558097 CA558097 CA 558097 CA 558097 A CA558097 A CA 558097A CA 1293465 C CA1293465 C CA 1293465C
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- bitumen
- mixer
- stream
- settler
- froth
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Abstract
"PURIFICATION PROCESS FOR BITUMEN FROTH"
ABSTRACT OF THE DISCLOSURE
Bitumen froth is treated in a circuit comprising a plurality of serially connected mixer and inclined plate settler units. A light hydrocarbon diluent moves countercurrently through the circuit. Thus, as the bitumen content of the stream being settled diminishes, the concentration of diluent in that stream increases.
ABSTRACT OF THE DISCLOSURE
Bitumen froth is treated in a circuit comprising a plurality of serially connected mixer and inclined plate settler units. A light hydrocarbon diluent moves countercurrently through the circuit. Thus, as the bitumen content of the stream being settled diminishes, the concentration of diluent in that stream increases.
Description
:~2~34~5 FIELD OF THE INVENTION
2 This invention relates to a process for purifying 3 bitumen froth, to thereby obtain a diluted bitumen stream of good 4 enough quality to be fed to a downstream upgrading facility. By 'purifying' is meant that water and solids present in the froth 6 are separated from the bitumen.
8 The oil sands of the Fort McMurray region of Alberta 9 are presently being exploited by two large commercial operations.
The process practised in these operations involves four broad 11 steps, namely:
12 - mining the oil sand;
13 - extracting the bitumen from the mined oil sand 14 using a process known as the 'hot water process', to produce bitumen in the form of a froth 16 contaminated with water and solids;
17 - purifying the froth to separate the water and 18 solids from the bitumen; and 19 - upgrading the purified bitumen in a coking facility to produce products which are suitable 21 for a conventional refinery.
22 The present invention has to do with the purifying 23 step. However, in order to understand the problems solved by 24 the invention, it is first necessary to review the steps of the hot water process and the conventional froth purification 26 process.
27 As a beginning point, it needs to be understood that 28 oil sands comprises relatively lar~e quartz sand grains, 29 each grain being encapsulated in a thin sheath of connate 0 water. The water contains minute clay particles ~referred to ~ g '~
~Z~39~65 1 as ~fines~). The bitumen is positioned in the interstices 2 between the water-sheathed grains of sand.
3 In the first step of the hot water process, the 4 mined oil sand is mi~ed in a rotating horizontal cylindrical drum (or 'tumbler') with hot water t80~C) and a small amount 6 of NaOH freferred to as 'process aid~). Steam is sparged 7 into the slurry at intervals along the lengt~ of the drum, to 8 ensure that the exit temperature of the resultant slurry is g a~out ~0~C.
The drum is slightly inclined along its length, so 11 that the mixture moves steadily therethrough. The retention 12 time is about 4 minutes.
13 This tumbling step is referred to as 14 'conditioning'. It involves heating of the bitumen and displacement, by water addition, of the bitumen away from the 16 sand grains. Many of the released bitumen globules become 17 aerated by forming films around air bubbles entrained in the 18 tumbler slurry. Conditioning also involves reaction between the ~aOH and bitumen to produce surfactants which facilitate the bitumen-release and subsequent flotation/settling steps.
21 On leaving the tumbler, the conditioned slurry is 22 screened, to remove oversize rocks and lumps, and diluted 23 ~ith additional hot water. The resulting water/bitumen ratio 24 is about 6:1.
The diluted slurry is then introduced into a large 26 thickener~like vessel having a cylindrical upper portion and 27 a conical lower portion. The vessel is referred to as the 28 'primary separation vessel' or 'PSV'. Here the diluted 29 slurry is retained for about 45 minutes under quiescent conditions. Under the influence of gravity, the sand grains 31 sink, are concentrated in the conical portion and are ~3~65 1 discharged as 'primary tailingsl through a valve and line 2 connected to the lower apex of the vessel. The bitumen 3 globules, rendered buoyant by air attachment, rise to the 4 surface of the PSV and form a froth. This froth is called 'primary froth' and typically comprises~
6 66.4~ by wt. bitumen 7 24.7% by wt. water 8 8.9% by wt. solids 9 The primary froth is skimmed off and recovered in a launder.
In between the layer of sand tailings in the base of the 11 vessel and the layer of froth at the top, there exists a 12 watery slurry referred to as 'middlings'. The middlings 13 contain fines and globules of bitumen which are 14 insufficiently buoyant to reach the froth layer.
A stream of middlings .is continuously withdrawn 16 from the PSV. These middlings are treated in a series of 17 sub-aerated flotation cells. In these cells, the middlings 18 are vigorously aerated and agitated, with the result that 19 contained bitumen is forced to float and form a dirty froth 20 referred to as 'secondary froth'. This secondary froth 21 typically comprises:
22 23.8% by wt. bitumen 23 58.7% by wt. water 24 l7.5% by wt. solids. ~, To reduce the concentration of water and solids in 26 the secondary froth, it may be retained in a settling tank to 27 allow some of the contaminants to settle out. ~he 'cleaned~
28 secondary froth typically comprises:
29 4l.4~ by wt. bitumen 46.2~ by wt. water 3~ 12.4% by wt. solids.
~2934~5 1 The primary and secondary froths are then combined 2 to provide the product of the hot water extraction process.
3 The ~combined froth~ typically comprises:
4 57.3% by wt. bitumen 34.2% by wt. water 6 8.4% by wt. solids.
7 This stream is too contaminated to be used as feed 8 to the downstream upgrading circuit. This latter circuit g requires a feed typically comprising:
99.0% by wt. bitumen 11 - % by wt. water 12 1.0% by wt. solids.
13 So the combined froth product requires purification 14 (or water and solids removal) before it can be fed to the upgrading circuit. Heretofore, this purification has been 16 obtained by using what is referred to as 'two stage dilution 17 centrifuging~. This operation involves:
18 1. Diluting the combined froth with naphtha.
19 This is done to reduce hydrocarbon phase viscosity and increase the density 21 difference between the hydrocar~on phase 22 (bitumen dissolved in naphtha) and the 23 water and solids phase (referred to jointly 24 as 'sludge');
2. Passing the diluted froth through a low-26 speed scroll centrifuge, to remove the 27 coarse solids and some of the water as a 28 cake , which is discarded; and .
93~L65 1 3. Passing the scroll centrifuge product 2 through a high-speed disc centrifuge to 3 remove fine solids and most of the balance of the water. The disc centrifuge product S typically analyzes at:
6 59.4% by wt. bitumen 7 37.5% by wt. naphtha 8 4.5% by wt. water 0.4% by wt. solids 1~ The naphtha diluent and any contained water iB then 11 distilled out of the disc centr.ifuge product to produae the 12 purified bitumen product for advancing to the upgrading process.
The described dilution centrifugin~ process has been used because it is capable of producing a bitumen 16 product of the desired quality. But it is an operation that 17 is exceedingly expensive to maintain and operate due to the 18 erosive nature of the feed and the rotatlng character of the 19 centrifuges. For example, in use, the flights of the scroll centrifuges wear badly, even though they are formed of 21 ceramic, and the hrittle ceramic flights commonly break and 22 put the machine out of balance. In the case of the disc 23 centrifuges, their sludge discharge no2zles are subject to 24 rapid wear and the separation interface between product and reject in the stack of discs can easily be 'lost', with the 26 result that a significant amount of bitumen is lost with the 27 tailings. In addition, a large number of the machines must 28 be used, with attendant consumption of very large amounts of 29 electrical energy.
~ILZ93~6~;
1 Thus, there has long been a need for a viable 2 alternative to the dilution centri~uging circuit for 3 purifying bitumen froth.
4 The present invention involves a circuit of interconnected known devices, namely mixers and inclined ,,, 6 plate settlers ('IPS').
7 An inclined plate settler comprises a stack of 8 parallel, spaced apart, solid plates, inclined downwardly g from the horizontal and mounted within a containing vessel.
lo Each space between a pair of plates forms a discrete settling 11 zone. The feed mixture to be separated is distributed into 12 the spaces, at a point between their longitudinal ends. The 13 light components of the mixture rise to the underside surface 14 of the upper plate. These light components then travel up said underside surface and are collected and recovered at the 16 upper ends of the plates. The heavy components of the 7 mixture sink towards the uppermost surface of the lower plate 18 and follow it downwardly, to be collected and recovered at 19 the lower ends of the plates.
A mixer can take any of various forms - the present 21 work involved simply a cylindrical container having a 22 submerged driven impellor positioned therein.
24 The present invention is based on the following experimen~ally determined observations:
26 - That bitumen froth is amenable to high quality 27 separation in a first IPS, but in that first 28 stage of separation only part of the bitumen 29 in the feed reports as overhead product;
a34~
1 - That the underflow from tAe first IPS, containing 2 a significant proportion of the bitumen in the 3 original feed, is not amenable to high quality separation in a second IPS. It appears that the first stage underflow contains stable emulsions 6 that will not readily resolve in tAe second IPS
7 or that much of the hydrocarbons that did not 8 report to the overflow in the first stage will 9 also not report to the overflow in the second stage; and 11 - That if light hydroc~rbon diluent (e.g. naphtha) 12 is mixed with the first stage underflow, then this mixture is amenable to good quality ~ 4 separation in the second IPS.
Having conceived and tried the underlying 16 experimental work that resulted in these observations, applicants conceived a purification circuit for bitumen froth 18 that would incorporate the following features:
19 - the use of a plurality of serially connected ^ inclined plate settlers, with a subsequent 21 settler being fed the underflow from a 22 preceding settler;
23 - the addition of light hydrocarbon 24 diluent or solvent, ln a progressively richer concentration, to the bitumen- -26 containing stream moving through the 27 series of settlers, said bitumen-containing 28 stream becoming progressively leaner in 29 bitumen as it moves through the circuit; and ~93~6S
1 - the use of mixers before each settler to mix 2 the added diluent with the bitumen.
3 A circuit or line consisting of three pairs of alternating mixers 4 and settlers was tested. ~he overflow stream from the first settler provided the only bitumen product stream produced from 6 the circuit. The bitumen/diluent overflow stream from the second 7 settler was recycled to the first mixer to be combined with the 8 froth feed. The low-bitumen/high-diluent overflow stream from 9 the third settler was recycled to the second mixer. Thus more diluent was supplied to the relatively bitumen-lean underflow 11 stream being supplied to the second mixer. And finally, fresh 12 diluent was supplied to the third mixer to dissolve the small 13 amount of bitumen in the underflow stream of the second settler.
14 When applied to typical combined bitumen froth this circuit demonstrated:
16 - that the bitumen product stream from the first 17 IPS was of the same order of purity as that 18 derived from a conventional dilution centrifuging 19 circuit; and - that the recovery of bitumen by the test circuit 21 was of the same order as that obtained by 22 dilution centrifuging.
23 Stated otherwise, we have made the surprising discovery 24 that a process using three mixingjIPS separation steps in series, combined with a counter flow of solvent, gives product 26 of as good quality as that obtained from the centrifuge process 27 (said qual.ity being referred to as "upgrading quality"), 28 together with comparable hydrocarbon recovery and a sludge 29 tailings that is substantially hydrocarbon-free. And the 1 components of the present circuit are without moving parts 2 (except for the pumps and impellors) and thus are 3 characterized by comparatively low maintenance costs.
4 DESCRIPTION OF T~lB DRAWINGS
Figure 1 is a block diagram showin~ the steps of 6 the process in accordance with the preferred embodiment; and 7 Figure 2 is a schematic showing the circuit of 8 processing components or units and their pipe 9 interconnections.
DESCRIPTION OF THE PREFERRED EMBODIMENT
11 The test work underlying the present invention was 12 carried out in 3-stage mixer/IPS circuit. The invention will now be described with respect to that circuit, although it 4 could also be conducted in 2, 4 or even more stages.
15 ~ More particularly, combined bitumen froth was fed 16 to a circuit A comprising: a first mixer l; a first IPS 2; a 17 second mixer 3; a second IPS 4; a third mixer 5; a third IPS
18 6; and appropriate connecting lines.
19 The combined froth was introduced into and mixed in the first mixer 1 ~ith a first recycled overhead stream from 21 the second IPS 4. This first recycled overhead stream was 22~ depleted in bitumen but enriched in naphtha, relative to the 23 combined froth f~ed.
24 ~he first mixer 1 comprised a cylindrical body la having a flat bottom lb. An impellor lc was positioned to 26 stir the contents of the mixer.
~3~5 l The mixture from the first mixer 1 was fed to the 2 inlet of the first IPS 2. The first IPS 2 was simply a box 3 2a having an inlet 2b, an overhead outlet 2c, and an 4 underflow outlet 2d. The box contained a pair of inclined spaced-apart plates 2e.
6 The dimensions of th2 mixer and IPS units used are 7 set forth in Table 1. The several mixers and IPS's in the 8 circuit were identical to the described units.
lo Length of IPS - 5 11 Spacing between plates - 1-1/2 12 Dimensions of plates - 5~ x l~
l3 Mixer vessel - 12" diameter l4 12" to 16" of liquid in the vessel during l6 operation 17 Type of impellor - 6~ diameter marine 18 propeller 19 Impellor rpm - ~20 - 680 Separation of the bitumen, water, and solids, 21 present in the mixture fed from the first mixer 1, took place 22 in the first IPS 2. A first overhead product stream, which 23 was the only bitumen-rich product from the circuit, was 24 obtained. This stream was enriched in bitumen relative to the original froth feed. (The compositions of these streams 26 are set forth in Table II below.) 27 The underflow stream from the first IPS 2 was fed 28 to the second mixer 3. ~ere it was mixed with a second 29 recycled stream from the third IPS 6. This second recycled stream was very depleted in bitumen but relatively rich in 31 naphtha.
lZ~3~S
1 The mixture from the second mixer 3 was fed to the 2 inlet of the second IPS 4. Separation occurred therein and 3 overflow and underflow streams were produced. T,he overflow 4 stream was the stream recycled to~ t'he first mixer, as previously stated.
6 The second underflow'stream, produced by the second 7 IPS 4, was fed to the third mixer 6. This second underflow S stream was quite lean in bitumen - more particularly~ it was 9 depleted in bitumen relative to the first underflow stream.
10 In the third mixer 6, the second underflow stream 11 was mixed with fresh pure naphtha. The mixture was fed to the 12 inlet of the third IPS 6 and underwent separation therein.
13 The overflow stream from the third IPS 6 was recycled to the 14 second mixer 3, as previously stated. ~he underflow stream, virtually free of bitumen, was discarded as tails.
16 The stream compositions and separation results are 17 set forth in Table II.
~293~6~;
TABLE II
2 COMPOSITION (% BY WT. ~
3 STREAN BITUMEN~ATER SOLIr)5 NAPHTHA RATE
4 k~
Combined froth 6 feed 57.334.2 8.5 - - 1.96 7 First recycled 8 ovexflow (from 9 2nd. IPS) 19.714.1 1.9 63.4 1.59 Overflow product 11 (from 1st IPS) 55.7a~.7 0.7 39.0 2.02 12 1st IPS
13 underflow 20.752.7 12.1 14.5 1.52 Second recycled l~ overflow (from 16 3rd IPSJ 2.8053.8 8.3 35.1 3.01 17 2nd IPS
18 underflow 2.913.7 74.6 9.3 2.95 19 Fresh diluent 99.5 0.81 3rd IPS
21 underf7Ow 0.2077.320.3 2.4 0.75 '~
2 This supplementary disclosure relates to a 3 variation of the circuit described in the principal 4 disclosure.
It can be advantageous to operate the separation 6 process at elevated temperature because the viscosity of the 7 hydrocarbon is thereby reduced. ~his allows the solid 8 particles to settle more rapidly. In addition, at hiyher 9 temperature the water droplets coalesce more readily, which facilitates their separation from the hydrocarbon. A high 11 purity product is thereby produced at lower residence time, 12 with the consequence that the capacity of the equipment is, 13 in effect, increased.
14 At such higher temperatures, fractions of the diluent can approach or exceed their atmospheric boiling 16 point. To prevent flashing of the diluent, and to contain the pressures generated, it is necessary to surround the 18 functioning units of the equipment with pressure-retaining lg houslngs.
This may be effected in conventional fashion by 21 closing in the components of the circuit, as indicated 22 diagrammatically in Figure 3, and operating the process at elevated temperature and pressure.
~;:
~:
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.
; - 13~ -
8 The oil sands of the Fort McMurray region of Alberta 9 are presently being exploited by two large commercial operations.
The process practised in these operations involves four broad 11 steps, namely:
12 - mining the oil sand;
13 - extracting the bitumen from the mined oil sand 14 using a process known as the 'hot water process', to produce bitumen in the form of a froth 16 contaminated with water and solids;
17 - purifying the froth to separate the water and 18 solids from the bitumen; and 19 - upgrading the purified bitumen in a coking facility to produce products which are suitable 21 for a conventional refinery.
22 The present invention has to do with the purifying 23 step. However, in order to understand the problems solved by 24 the invention, it is first necessary to review the steps of the hot water process and the conventional froth purification 26 process.
27 As a beginning point, it needs to be understood that 28 oil sands comprises relatively lar~e quartz sand grains, 29 each grain being encapsulated in a thin sheath of connate 0 water. The water contains minute clay particles ~referred to ~ g '~
~Z~39~65 1 as ~fines~). The bitumen is positioned in the interstices 2 between the water-sheathed grains of sand.
3 In the first step of the hot water process, the 4 mined oil sand is mi~ed in a rotating horizontal cylindrical drum (or 'tumbler') with hot water t80~C) and a small amount 6 of NaOH freferred to as 'process aid~). Steam is sparged 7 into the slurry at intervals along the lengt~ of the drum, to 8 ensure that the exit temperature of the resultant slurry is g a~out ~0~C.
The drum is slightly inclined along its length, so 11 that the mixture moves steadily therethrough. The retention 12 time is about 4 minutes.
13 This tumbling step is referred to as 14 'conditioning'. It involves heating of the bitumen and displacement, by water addition, of the bitumen away from the 16 sand grains. Many of the released bitumen globules become 17 aerated by forming films around air bubbles entrained in the 18 tumbler slurry. Conditioning also involves reaction between the ~aOH and bitumen to produce surfactants which facilitate the bitumen-release and subsequent flotation/settling steps.
21 On leaving the tumbler, the conditioned slurry is 22 screened, to remove oversize rocks and lumps, and diluted 23 ~ith additional hot water. The resulting water/bitumen ratio 24 is about 6:1.
The diluted slurry is then introduced into a large 26 thickener~like vessel having a cylindrical upper portion and 27 a conical lower portion. The vessel is referred to as the 28 'primary separation vessel' or 'PSV'. Here the diluted 29 slurry is retained for about 45 minutes under quiescent conditions. Under the influence of gravity, the sand grains 31 sink, are concentrated in the conical portion and are ~3~65 1 discharged as 'primary tailingsl through a valve and line 2 connected to the lower apex of the vessel. The bitumen 3 globules, rendered buoyant by air attachment, rise to the 4 surface of the PSV and form a froth. This froth is called 'primary froth' and typically comprises~
6 66.4~ by wt. bitumen 7 24.7% by wt. water 8 8.9% by wt. solids 9 The primary froth is skimmed off and recovered in a launder.
In between the layer of sand tailings in the base of the 11 vessel and the layer of froth at the top, there exists a 12 watery slurry referred to as 'middlings'. The middlings 13 contain fines and globules of bitumen which are 14 insufficiently buoyant to reach the froth layer.
A stream of middlings .is continuously withdrawn 16 from the PSV. These middlings are treated in a series of 17 sub-aerated flotation cells. In these cells, the middlings 18 are vigorously aerated and agitated, with the result that 19 contained bitumen is forced to float and form a dirty froth 20 referred to as 'secondary froth'. This secondary froth 21 typically comprises:
22 23.8% by wt. bitumen 23 58.7% by wt. water 24 l7.5% by wt. solids. ~, To reduce the concentration of water and solids in 26 the secondary froth, it may be retained in a settling tank to 27 allow some of the contaminants to settle out. ~he 'cleaned~
28 secondary froth typically comprises:
29 4l.4~ by wt. bitumen 46.2~ by wt. water 3~ 12.4% by wt. solids.
~2934~5 1 The primary and secondary froths are then combined 2 to provide the product of the hot water extraction process.
3 The ~combined froth~ typically comprises:
4 57.3% by wt. bitumen 34.2% by wt. water 6 8.4% by wt. solids.
7 This stream is too contaminated to be used as feed 8 to the downstream upgrading circuit. This latter circuit g requires a feed typically comprising:
99.0% by wt. bitumen 11 - % by wt. water 12 1.0% by wt. solids.
13 So the combined froth product requires purification 14 (or water and solids removal) before it can be fed to the upgrading circuit. Heretofore, this purification has been 16 obtained by using what is referred to as 'two stage dilution 17 centrifuging~. This operation involves:
18 1. Diluting the combined froth with naphtha.
19 This is done to reduce hydrocarbon phase viscosity and increase the density 21 difference between the hydrocar~on phase 22 (bitumen dissolved in naphtha) and the 23 water and solids phase (referred to jointly 24 as 'sludge');
2. Passing the diluted froth through a low-26 speed scroll centrifuge, to remove the 27 coarse solids and some of the water as a 28 cake , which is discarded; and .
93~L65 1 3. Passing the scroll centrifuge product 2 through a high-speed disc centrifuge to 3 remove fine solids and most of the balance of the water. The disc centrifuge product S typically analyzes at:
6 59.4% by wt. bitumen 7 37.5% by wt. naphtha 8 4.5% by wt. water 0.4% by wt. solids 1~ The naphtha diluent and any contained water iB then 11 distilled out of the disc centr.ifuge product to produae the 12 purified bitumen product for advancing to the upgrading process.
The described dilution centrifugin~ process has been used because it is capable of producing a bitumen 16 product of the desired quality. But it is an operation that 17 is exceedingly expensive to maintain and operate due to the 18 erosive nature of the feed and the rotatlng character of the 19 centrifuges. For example, in use, the flights of the scroll centrifuges wear badly, even though they are formed of 21 ceramic, and the hrittle ceramic flights commonly break and 22 put the machine out of balance. In the case of the disc 23 centrifuges, their sludge discharge no2zles are subject to 24 rapid wear and the separation interface between product and reject in the stack of discs can easily be 'lost', with the 26 result that a significant amount of bitumen is lost with the 27 tailings. In addition, a large number of the machines must 28 be used, with attendant consumption of very large amounts of 29 electrical energy.
~ILZ93~6~;
1 Thus, there has long been a need for a viable 2 alternative to the dilution centri~uging circuit for 3 purifying bitumen froth.
4 The present invention involves a circuit of interconnected known devices, namely mixers and inclined ,,, 6 plate settlers ('IPS').
7 An inclined plate settler comprises a stack of 8 parallel, spaced apart, solid plates, inclined downwardly g from the horizontal and mounted within a containing vessel.
lo Each space between a pair of plates forms a discrete settling 11 zone. The feed mixture to be separated is distributed into 12 the spaces, at a point between their longitudinal ends. The 13 light components of the mixture rise to the underside surface 14 of the upper plate. These light components then travel up said underside surface and are collected and recovered at the 16 upper ends of the plates. The heavy components of the 7 mixture sink towards the uppermost surface of the lower plate 18 and follow it downwardly, to be collected and recovered at 19 the lower ends of the plates.
A mixer can take any of various forms - the present 21 work involved simply a cylindrical container having a 22 submerged driven impellor positioned therein.
24 The present invention is based on the following experimen~ally determined observations:
26 - That bitumen froth is amenable to high quality 27 separation in a first IPS, but in that first 28 stage of separation only part of the bitumen 29 in the feed reports as overhead product;
a34~
1 - That the underflow from tAe first IPS, containing 2 a significant proportion of the bitumen in the 3 original feed, is not amenable to high quality separation in a second IPS. It appears that the first stage underflow contains stable emulsions 6 that will not readily resolve in tAe second IPS
7 or that much of the hydrocarbons that did not 8 report to the overflow in the first stage will 9 also not report to the overflow in the second stage; and 11 - That if light hydroc~rbon diluent (e.g. naphtha) 12 is mixed with the first stage underflow, then this mixture is amenable to good quality ~ 4 separation in the second IPS.
Having conceived and tried the underlying 16 experimental work that resulted in these observations, applicants conceived a purification circuit for bitumen froth 18 that would incorporate the following features:
19 - the use of a plurality of serially connected ^ inclined plate settlers, with a subsequent 21 settler being fed the underflow from a 22 preceding settler;
23 - the addition of light hydrocarbon 24 diluent or solvent, ln a progressively richer concentration, to the bitumen- -26 containing stream moving through the 27 series of settlers, said bitumen-containing 28 stream becoming progressively leaner in 29 bitumen as it moves through the circuit; and ~93~6S
1 - the use of mixers before each settler to mix 2 the added diluent with the bitumen.
3 A circuit or line consisting of three pairs of alternating mixers 4 and settlers was tested. ~he overflow stream from the first settler provided the only bitumen product stream produced from 6 the circuit. The bitumen/diluent overflow stream from the second 7 settler was recycled to the first mixer to be combined with the 8 froth feed. The low-bitumen/high-diluent overflow stream from 9 the third settler was recycled to the second mixer. Thus more diluent was supplied to the relatively bitumen-lean underflow 11 stream being supplied to the second mixer. And finally, fresh 12 diluent was supplied to the third mixer to dissolve the small 13 amount of bitumen in the underflow stream of the second settler.
14 When applied to typical combined bitumen froth this circuit demonstrated:
16 - that the bitumen product stream from the first 17 IPS was of the same order of purity as that 18 derived from a conventional dilution centrifuging 19 circuit; and - that the recovery of bitumen by the test circuit 21 was of the same order as that obtained by 22 dilution centrifuging.
23 Stated otherwise, we have made the surprising discovery 24 that a process using three mixingjIPS separation steps in series, combined with a counter flow of solvent, gives product 26 of as good quality as that obtained from the centrifuge process 27 (said qual.ity being referred to as "upgrading quality"), 28 together with comparable hydrocarbon recovery and a sludge 29 tailings that is substantially hydrocarbon-free. And the 1 components of the present circuit are without moving parts 2 (except for the pumps and impellors) and thus are 3 characterized by comparatively low maintenance costs.
4 DESCRIPTION OF T~lB DRAWINGS
Figure 1 is a block diagram showin~ the steps of 6 the process in accordance with the preferred embodiment; and 7 Figure 2 is a schematic showing the circuit of 8 processing components or units and their pipe 9 interconnections.
DESCRIPTION OF THE PREFERRED EMBODIMENT
11 The test work underlying the present invention was 12 carried out in 3-stage mixer/IPS circuit. The invention will now be described with respect to that circuit, although it 4 could also be conducted in 2, 4 or even more stages.
15 ~ More particularly, combined bitumen froth was fed 16 to a circuit A comprising: a first mixer l; a first IPS 2; a 17 second mixer 3; a second IPS 4; a third mixer 5; a third IPS
18 6; and appropriate connecting lines.
19 The combined froth was introduced into and mixed in the first mixer 1 ~ith a first recycled overhead stream from 21 the second IPS 4. This first recycled overhead stream was 22~ depleted in bitumen but enriched in naphtha, relative to the 23 combined froth f~ed.
24 ~he first mixer 1 comprised a cylindrical body la having a flat bottom lb. An impellor lc was positioned to 26 stir the contents of the mixer.
~3~5 l The mixture from the first mixer 1 was fed to the 2 inlet of the first IPS 2. The first IPS 2 was simply a box 3 2a having an inlet 2b, an overhead outlet 2c, and an 4 underflow outlet 2d. The box contained a pair of inclined spaced-apart plates 2e.
6 The dimensions of th2 mixer and IPS units used are 7 set forth in Table 1. The several mixers and IPS's in the 8 circuit were identical to the described units.
lo Length of IPS - 5 11 Spacing between plates - 1-1/2 12 Dimensions of plates - 5~ x l~
l3 Mixer vessel - 12" diameter l4 12" to 16" of liquid in the vessel during l6 operation 17 Type of impellor - 6~ diameter marine 18 propeller 19 Impellor rpm - ~20 - 680 Separation of the bitumen, water, and solids, 21 present in the mixture fed from the first mixer 1, took place 22 in the first IPS 2. A first overhead product stream, which 23 was the only bitumen-rich product from the circuit, was 24 obtained. This stream was enriched in bitumen relative to the original froth feed. (The compositions of these streams 26 are set forth in Table II below.) 27 The underflow stream from the first IPS 2 was fed 28 to the second mixer 3. ~ere it was mixed with a second 29 recycled stream from the third IPS 6. This second recycled stream was very depleted in bitumen but relatively rich in 31 naphtha.
lZ~3~S
1 The mixture from the second mixer 3 was fed to the 2 inlet of the second IPS 4. Separation occurred therein and 3 overflow and underflow streams were produced. T,he overflow 4 stream was the stream recycled to~ t'he first mixer, as previously stated.
6 The second underflow'stream, produced by the second 7 IPS 4, was fed to the third mixer 6. This second underflow S stream was quite lean in bitumen - more particularly~ it was 9 depleted in bitumen relative to the first underflow stream.
10 In the third mixer 6, the second underflow stream 11 was mixed with fresh pure naphtha. The mixture was fed to the 12 inlet of the third IPS 6 and underwent separation therein.
13 The overflow stream from the third IPS 6 was recycled to the 14 second mixer 3, as previously stated. ~he underflow stream, virtually free of bitumen, was discarded as tails.
16 The stream compositions and separation results are 17 set forth in Table II.
~293~6~;
TABLE II
2 COMPOSITION (% BY WT. ~
3 STREAN BITUMEN~ATER SOLIr)5 NAPHTHA RATE
4 k~
Combined froth 6 feed 57.334.2 8.5 - - 1.96 7 First recycled 8 ovexflow (from 9 2nd. IPS) 19.714.1 1.9 63.4 1.59 Overflow product 11 (from 1st IPS) 55.7a~.7 0.7 39.0 2.02 12 1st IPS
13 underflow 20.752.7 12.1 14.5 1.52 Second recycled l~ overflow (from 16 3rd IPSJ 2.8053.8 8.3 35.1 3.01 17 2nd IPS
18 underflow 2.913.7 74.6 9.3 2.95 19 Fresh diluent 99.5 0.81 3rd IPS
21 underf7Ow 0.2077.320.3 2.4 0.75 '~
2 This supplementary disclosure relates to a 3 variation of the circuit described in the principal 4 disclosure.
It can be advantageous to operate the separation 6 process at elevated temperature because the viscosity of the 7 hydrocarbon is thereby reduced. ~his allows the solid 8 particles to settle more rapidly. In addition, at hiyher 9 temperature the water droplets coalesce more readily, which facilitates their separation from the hydrocarbon. A high 11 purity product is thereby produced at lower residence time, 12 with the consequence that the capacity of the equipment is, 13 in effect, increased.
14 At such higher temperatures, fractions of the diluent can approach or exceed their atmospheric boiling 16 point. To prevent flashing of the diluent, and to contain the pressures generated, it is necessary to surround the 18 functioning units of the equipment with pressure-retaining lg houslngs.
This may be effected in conventional fashion by 21 closing in the components of the circuit, as indicated 22 diagrammatically in Figure 3, and operating the process at elevated temperature and pressure.
~;:
~:
:`
.
; - 13~ -
Claims (2)
1. A process for purifying bitumen froth from the hot water process for extracting bitumen from oil sand, said froth comprising bitumen, water and solids, said process being carried out in a circuit comprising first, second and third inclined plate settlers and first, second and third mixers, each settler having an inlet, an overflow outlet and an underflow outlet, each mixer having an inlet and outlet, each mixer being positioned before the corresponding settler, the outlet of each mixer being connected with the inlet of the immediately downstream settler, the inlet of the first mixer being connected with a source of bitumen froth, the inlet of the second mixer being connected with the underflow outlet of the first settler, the inlet of the third mixer being connected with the underflow outlet of the second settler, the overflow outlet of the first settler providing the diluted bitumen product from the circuit, the overflow outlet of the second settler being connected with the first mixer, the overflow outlet of the third settler being connected with the second mixer, the third mixer being connected with a source of light hydrocarbon diluent, said process comprising:
mixing the bitumen froth in the first mixer with a first recycled overflow stream from the second settler, said overflow stream being depleted in bitumen and enriched in diluent relative to the froth;
treating the mixture produced from the first mixer in the first settler to produce a first product overflow stream which is sufficiently enriched in bitumen relative to the froth to be of upgrading quality and a first underflow stream which is depleted in bitumen relative to the froth;
depleted in bitumen and enriched in diluent relative to the first overflow stream;
treating the mixture produced from the second mixer in the second settler to produce the first recycled overflow stream and a second underflow stream which is depleted in bitumen relative to the first underflow stream;
mixing the second underflow stream from the second settler in the third mixer with a stream of light hydrocarbon diluent from said source of light hydrocarbon diluent;
treating the mixture produced from the third mixer in the third settler to produce the second recycled overflow stream and a third underflow stream which is depleted in bitumen relative to the second underflow stream.
mixing the bitumen froth in the first mixer with a first recycled overflow stream from the second settler, said overflow stream being depleted in bitumen and enriched in diluent relative to the froth;
treating the mixture produced from the first mixer in the first settler to produce a first product overflow stream which is sufficiently enriched in bitumen relative to the froth to be of upgrading quality and a first underflow stream which is depleted in bitumen relative to the froth;
depleted in bitumen and enriched in diluent relative to the first overflow stream;
treating the mixture produced from the second mixer in the second settler to produce the first recycled overflow stream and a second underflow stream which is depleted in bitumen relative to the first underflow stream;
mixing the second underflow stream from the second settler in the third mixer with a stream of light hydrocarbon diluent from said source of light hydrocarbon diluent;
treating the mixture produced from the third mixer in the third settler to produce the second recycled overflow stream and a third underflow stream which is depleted in bitumen relative to the second underflow stream.
2. The process as set forth in claim 1 wherein:
the process is conducted at elevated temperature and pressure and the circuit is pressure-retaining.
the process is conducted at elevated temperature and pressure and the circuit is pressure-retaining.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 558097 CA1293465C (en) | 1988-02-04 | 1988-02-04 | Purification process for bitumen froth |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 558097 CA1293465C (en) | 1988-02-04 | 1988-02-04 | Purification process for bitumen froth |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1293465C true CA1293465C (en) | 1991-12-24 |
Family
ID=4137384
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 558097 Expired - Lifetime CA1293465C (en) | 1988-02-04 | 1988-02-04 | Purification process for bitumen froth |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1293465C (en) |
Cited By (19)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7141162B2 (en) | 2002-09-19 | 2006-11-28 | Suncor Energy, Inc. | Bituminous froth inclined plate separator and hydrocarbon cyclone treatment process |
| US7569137B2 (en) | 2004-01-08 | 2009-08-04 | Fort Hills Energy L.P. | Process and apparatus for treating tailings |
| US7736501B2 (en) | 2002-09-19 | 2010-06-15 | Suncor Energy Inc. | System and process for concentrating hydrocarbons in a bitumen feed |
| US7763166B2 (en) | 2006-06-16 | 2010-07-27 | Canadian Oil Sands Limited | Relocatable countercurrent decantation system |
| US7914670B2 (en) | 2004-01-09 | 2011-03-29 | Suncor Energy Inc. | Bituminous froth inline steam injection processing |
| US8025341B2 (en) | 2005-11-09 | 2011-09-27 | Suncor Energy Inc. | Mobile oil sands mining system |
| US8349269B2 (en) | 2007-06-27 | 2013-01-08 | H R D Corporation | High shear system and process for the production of acetic anhydride |
| US8968580B2 (en) | 2009-12-23 | 2015-03-03 | Suncor Energy Inc. | Apparatus and method for regulating flow through a pumpbox |
| US9016799B2 (en) | 2005-11-09 | 2015-04-28 | Suncor Energy, Inc. | Mobile oil sands mining system |
| US9207019B2 (en) | 2011-04-15 | 2015-12-08 | Fort Hills Energy L.P. | Heat recovery for bitumen froth treatment plant integration with sealed closed-loop cooling circuit |
| US9546323B2 (en) | 2011-01-27 | 2017-01-17 | Fort Hills Energy L.P. | Process for integration of paraffinic froth treatment hub and a bitumen ore mining and extraction facility |
| US9587176B2 (en) | 2011-02-25 | 2017-03-07 | Fort Hills Energy L.P. | Process for treating high paraffin diluted bitumen |
| US9676684B2 (en) | 2011-03-01 | 2017-06-13 | Fort Hills Energy L.P. | Process and unit for solvent recovery from solvent diluted tailings derived from bitumen froth treatment |
| US9789422B2 (en) | 2010-11-02 | 2017-10-17 | Fort Hills Energy L.P. | Apparatus and method for separating a feed material containing immiscible phases of different densities |
| US9791170B2 (en) | 2011-03-22 | 2017-10-17 | Fort Hills Energy L.P. | Process for direct steam injection heating of oil sands slurry streams such as bitumen froth |
| US10041005B2 (en) | 2011-03-04 | 2018-08-07 | Fort Hills Energy L.P. | Process and system for solvent addition to bitumen froth |
| US10226717B2 (en) | 2011-04-28 | 2019-03-12 | Fort Hills Energy L.P. | Method of recovering solvent from tailings by flashing under choked flow conditions |
| US10781375B2 (en) | 2017-09-11 | 2020-09-22 | Syncrude Canada Ltd. In Trust For The Owners Of The Syncrude Project As Such Owners Exist Now And In The Future | Froth washing prior to naphtha dilution |
| US11261383B2 (en) | 2011-05-18 | 2022-03-01 | Fort Hills Energy L.P. | Enhanced temperature control of bitumen froth treatment process |
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1988
- 1988-02-04 CA CA 558097 patent/CA1293465C/en not_active Expired - Lifetime
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| US7726491B2 (en) | 2002-09-19 | 2010-06-01 | Suncor Energy Inc. | Bituminous froth hydrocarbon cyclone |
| US7736501B2 (en) | 2002-09-19 | 2010-06-15 | Suncor Energy Inc. | System and process for concentrating hydrocarbons in a bitumen feed |
| US7141162B2 (en) | 2002-09-19 | 2006-11-28 | Suncor Energy, Inc. | Bituminous froth inclined plate separator and hydrocarbon cyclone treatment process |
| US7569137B2 (en) | 2004-01-08 | 2009-08-04 | Fort Hills Energy L.P. | Process and apparatus for treating tailings |
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| US8592620B2 (en) | 2007-06-27 | 2013-11-26 | H R D Corporation | High shear system and process for the production of acetic anhydride |
| US8349269B2 (en) | 2007-06-27 | 2013-01-08 | H R D Corporation | High shear system and process for the production of acetic anhydride |
| US8968580B2 (en) | 2009-12-23 | 2015-03-03 | Suncor Energy Inc. | Apparatus and method for regulating flow through a pumpbox |
| US9789422B2 (en) | 2010-11-02 | 2017-10-17 | Fort Hills Energy L.P. | Apparatus and method for separating a feed material containing immiscible phases of different densities |
| US9546323B2 (en) | 2011-01-27 | 2017-01-17 | Fort Hills Energy L.P. | Process for integration of paraffinic froth treatment hub and a bitumen ore mining and extraction facility |
| US10125325B2 (en) | 2011-02-25 | 2018-11-13 | Fort Hills Energy L.P. | Process for treating high paraffin diluted bitumen |
| US9587176B2 (en) | 2011-02-25 | 2017-03-07 | Fort Hills Energy L.P. | Process for treating high paraffin diluted bitumen |
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| US10041005B2 (en) | 2011-03-04 | 2018-08-07 | Fort Hills Energy L.P. | Process and system for solvent addition to bitumen froth |
| US10988695B2 (en) | 2011-03-04 | 2021-04-27 | Fort Hills Energy L.P. | Process and system for solvent addition to bitumen froth |
| US9791170B2 (en) | 2011-03-22 | 2017-10-17 | Fort Hills Energy L.P. | Process for direct steam injection heating of oil sands slurry streams such as bitumen froth |
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