CA2000984C - Mixer circuit for oil sand - Google Patents
Mixer circuit for oil sandInfo
- Publication number
- CA2000984C CA2000984C CA002000984A CA2000984A CA2000984C CA 2000984 C CA2000984 C CA 2000984C CA 002000984 A CA002000984 A CA 002000984A CA 2000984 A CA2000984 A CA 2000984A CA 2000984 C CA2000984 C CA 2000984C
- Authority
- CA
- Canada
- Prior art keywords
- slurry
- vessel
- oil sand
- mixer
- vortex
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B9/00—General arrangement of separating plant, e.g. flow sheets
- B03B9/02—General arrangement of separating plant, e.g. flow sheets specially adapted for oil-sand, oil-chalk, oil-shales, ozokerite, bitumen, or the like
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/50—Mixing liquids with solids
- B01F23/56—Mixing liquids with solids by introducing solids in liquids, e.g. dispersing or dissolving
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/10—Mixing by creating a vortex flow, e.g. by tangential introduction of flow components
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/20—Jet mixers, i.e. mixers using high-speed fluid streams
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F25/00—Flow mixers; Mixers for falling materials, e.g. solid particles
- B01F25/50—Circulation mixers, e.g. wherein at least part of the mixture is discharged from and reintroduced into a receptacle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
- B28C5/02—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions without using driven mechanical means effecting the mixing
- B28C5/06—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions without using driven mechanical means effecting the mixing the mixing being effected by the action of a fluid
Abstract
"MIXER CIRCUIT FOR OIL SAND"
ABSTRACT OF THE DISCLOSURE
The mixer circuit comprises a vertically oriented, open-topped mixer vessel having a cylindrical side wall terminating with a shallow conical bottom. The bottom wall forms a central bottom outlet. Recycled slurry and fresh water streams are fed tangentially to the inner surface of the vessel, thereby forming a vortex. The oil sand enters as a continuous, free-flowing stream moving along a downward trajectory; the stream impinges the vortex, wherein it is dispersed and mixed to create slurry. The slurry exits through the bottom outlet, is screened to remove oversize material, and enters a holding vessel. Part of the slurry in the holding vessel is recycled to the mixer vessel through a pipe loop incorporating a pump. The slurry is energized by the pump and functions to maintain and partly create the rapidly moving vortex that carries out the mixing and lump-disintegration actions. The balance of the slurry in the holding vessel is pumped out as product. The circuit is adapted to consistently produce a dense slurry.
ABSTRACT OF THE DISCLOSURE
The mixer circuit comprises a vertically oriented, open-topped mixer vessel having a cylindrical side wall terminating with a shallow conical bottom. The bottom wall forms a central bottom outlet. Recycled slurry and fresh water streams are fed tangentially to the inner surface of the vessel, thereby forming a vortex. The oil sand enters as a continuous, free-flowing stream moving along a downward trajectory; the stream impinges the vortex, wherein it is dispersed and mixed to create slurry. The slurry exits through the bottom outlet, is screened to remove oversize material, and enters a holding vessel. Part of the slurry in the holding vessel is recycled to the mixer vessel through a pipe loop incorporating a pump. The slurry is energized by the pump and functions to maintain and partly create the rapidly moving vortex that carries out the mixing and lump-disintegration actions. The balance of the slurry in the holding vessel is pumped out as product. The circuit is adapted to consistently produce a dense slurry.
Description
2 This invention relates to a circuit for mixing oil sand 3 in hot water to produce a slurry suitable for conveyance in a 4 pipeline.
S BACKGROUND OF THE INVENTIQ~
6 The invention has been developed in connection with 7 mixing oil sand in hot water. While not limited to that 8 application, it will now be described in connection therewith.
9 Bitumen, a heavy oil, is currently being extracted on a commercial basis from oil sand. Presently, two very large 11 scale commercial operations are producing synthetic crude oil 12 from oil sand in the Fort McMurray district of Northern Alberta.
13 At each of these operations, the oil sand is strip-14 mined and conveyed on conveyor belts, often several kilometers in length, to an extraction plant. At the extraction plant, the 16 bitumen is separated from the solids and recovered. This is 17 accomplished using a process known as the 'hot water process'.
18 The hot water process involves mixing the oil sand with 19 hot water (95C) and a small amount of caustic in a rotating horizontal drum (or 'tumbler'). Steam is added to the mixture 21 as it moves through the tumbler, to ensure that its exit 22 temperature is about 80C. In the tumbler, the bitumen is 23 separated from the solids, lumps of the cohesive oil sand are 24 ablated and disintegrated and minute flecks of freed oil coalesce to form larger globule. In addition air bubbles are entrained 26 in the slurry. Some of the oil flecks contact air bubbles and 27 coat them, whereby the oil (or bitumen) is aerated. The term 28 "conditioning" is used to denote thy sum of the mechanisms 1 occurring in the tumbler. On leaving the tumbler, the slurry is 2 diluted with additional hot water and retained under quiescent 3 conditions for a prolonged period in a thickener-like vessel 4 referred to as a primary separation vessel ("PSV"). In the PSV, other bitumen lobules attach to and film around bubbles of air 6 entrained in the slurry. Much of the aerated bitumen rises to 7 form froth on the surface of the vessel contents. This froth is 8 recovered. drag stream is withdrawn from the central part of 9 the PSV and this drag stream is processed in a bank of sub-aerated flotation cells to produce a secondary yield of boatmen froth. The froth streams are combined and further processed to 12 remove entrained water and solids and yield essentially pure 13 bitumen.
14 Now, the belt conveyors extending between the mine and the extraction plant are characterized by a number of problems.
16 They are expensive to install, operate and maintain. And their 17 use requires that the solids, which have no value, must be 18 conveyed to the extraction plant and then returned by truck to 19 the mine pits for disposal. In addition, the tumblers cannot be increased in size to permit of improvement of the system. They 21 are presently so large that it would be technically difficult to 22 manufacture them in a larger size and convey them to the plant 23 site. As a result, it is difficult to reduce the heat 24 requirements of the process by lowering the slurry temperature, because such a step would require increasing the tumbler 26 retention time, which would necessitate larger tumblers.
27 In a co-pending application, applicants teach use of 28 a pipeline to convey an aqueous slurry of the oil sands from the 29 mine site to the extraction plant. The pipeline slurry may be 1 fed directly to the PSV, thereby eliminating the need for the 2 tumbler. The invention in the co-pending application is based 3 on the discovery that the slurry will undergo adequate 4 conditioning in the pipeline over a distance that is significantly shorter than the length of pipeline needed to get 6 Kit to the extraction plant. In addition, the slurry will not be 7 over-conditioned if it continues to move through the pipeline 8 after conditioning is complete. conditioning is considered to 9 be complete if good bitumen recovery in the form of good quality froth can be achieved in the downstream PSV.) This pipeline 11 scheme has the further advantage that most of the coarse solids 12 may be removed in a settler positioned part way along the length 13 of the pipeline.
14 So pipe lining of the oil sand in slurry form between the mine and the PSV is now considered by applicants to be a 16 viable procedure.
17 The present invention is directed toward providing a 18 mixer circuit which satisfactorily blends the oil sand with hot 19 water and entrains air to yield a consistent, dense (e.g. about 60% - 65% by weight solids) aerated slurry, preferably having a 21 relatively low temperature (e.g. 50C), that is amenable to 22 pipeline conveyance.
23 In this connection, it needs to be appreciated that oil 24 sand is tacky, cohesive, erosive material incorporating a significant content of "oversize". Oversize is a term applied I to the rocks, oil sand lumps, and clay lumps that occur in oil 27 sand (often up to a size of 20 inches.
28 If one were to feed a stream of oil sand into a tank 29 containing hot water and proceed to withdraw a mixture from the 1 base of the tank with a pump, the oil sand would simply pipe up 2 in the kink, fill it, and plug the pump. So a mixer circuit for 3 this purpose must be capable of suspending the oil sand in the water with which it is mixed.
It has been mentioned that it is desirable to produce 6 a dense slurry. This need arises from the fact that one wants 7 to minimize the amount of hot water supplied at the mine site 8 for this purpose. Heating water is expensive and there are many 9 reason why these plants need to conserve water to the maximum.
And of course the mixer circuit has to be capable of 11 coping with the oversize material. Equipment having moving 12 parts, such as a tank equipped with paddle mixers, would be 13 inappropriate for use with the erosive sand associated with 14 oversize chunks.
SUMMARY OF THE INVENTION
16 In accordance with the invention, as-mined but 17 preferably processed oil sand is mixed with streams of recycled 18 slurry and fresh hot water in the cylindrical chamber of a I vertically oriented, open-topped mixer vessel, to produce a I slurry. The slurry exits the mixing chamber through a centrally 21 positioned bottom outlet and is screened to remove oversize, 22 thereafter entering the chamber of a holding vessel. Part of the 23 slurry moving through the holding vessel is recycled, to provide 24 the previously mentioned recycled slurry stream entering the I mixer vessel. This is done by pumping it through a pipe loop ~26 that communicates with the mixing chamber through an inlet that 27 feeds the slurry tangentially to the inner surface of the mixer 28 vessel wall.
1 queue recycled slurry is therefore controllable and 2 mechanically given energy by the pump in the recycle loop. Due 3 to its tangential entry into the mixing chamber, the slurry adopts the form of a rotating vortex, into which the oil sand and fresh water are added and into which air is entrained. The oil 6 sand is fed into the vortex as a free-flowing stream that moves 7 along a downwardly extending trajectory. The trajectory is 8 directed to cause the stream of oil sand to impinge and enter the 9 vortex adjacent the latter's upper end. The added oil sand and fresh water mix with the rotating recycled slurry to produce a 11 satisfactorily consistent, dense, aerated slurry leaving the 12 mixer vessel through its bottom outlet. The intensity of the 13 vortex can be varied by adjusting the output of the recycle loop 14 pump.
In a preferred feature, the fresh water stream is 16 injected into the mixing chamber tangentially to the inner 17 surface of the mixer vessel wall. This incrementally increases 18 the energy supplied to the vortex, although the main energy 19 contributor retains the dense, pumped, recycled slurry.
The proportion of the slurry, produced by the mixer 21 vessel, which is recycled is quite large. The rate of 22 recirculation is maintained so as to ensure that the vortex is 23 capable of accepting and suspending the dry oil sand. typically 24 the rate of recirculation is 2 to 3 times the discharged slurry rate.
26 The mixer circuit is characterized by the following 27 features:
I - the mixer vessel's upright circular bounding 29 surface of relatively small diameter is coupled 1 with a pumped, dense, tangentially-directed 2 recycle stream to create a relatively thick and 3 fast-moving vortex that has been found to be 4 capable of dispersing and suspending the dry oil sand while only about 35 to 40% by weight fresh 6 water is consumed in creating the slurry;
7 - the recycle loop, having a pump, is used to 8 contribute most of the energy needed to carry out 9 the mixing function;
- the screen is provided between the two vessels to 11 remove the oversize, so that recycle and product 12 pumping can be accomplished; and 13 - the mixer vessel does not incorporate moving parts 14 and can accommodate the passage there through ox the oversize.
17 Figure 1 is a schematic sectional side view of the 18 mixer circuit.
The mixer circuit 1 comprises a vertically orientated 21 mixer vessel 2 forming a cylindrical, open-topped mixing chamber 22 3. The mixer vessel 2 has a conical bottom which forms a 23 centrally positioned bottom outlet 4.
24 A vibrating screen 5 is positioned beneath the outlet 4, to retain and reject oversize material 6 unsuitable for 26 subsequent pumping.
1 A holding vessel 7, forming an open-topped chamber 8, 2 is positioned beneath the screen 5, to receive the slurry passing 3 through the latter.
4 A recycle pipe loop 9 connects the holding vessel chamber 8 with the mixing chamber 3. The loop 9 connects with 6 an inlet port 10 adapted to feed recycled slurry tangentially to 7 the lower end of the inside surface 11 of the mixer vessel wall 8 12.
9 A variable pump 15 is connected into the recycle loop 9, for pumping slurry from the holding vessel chamber 8 into the 11 mixing chamber 3.
12 A conveyor 16 is provided to feed oil sand 17 from a 13 point spaced to one side of the vertical axis of mixer vessel 2.
14 The oil sand forms a frilling stream that follows a downward and lateral trajectory and penetrates into the slurry vortex 18, 16 which has been formed by pumping slurry through the inlet port 17 10 and into the mixing chamber 3.
18 A line 19, connected with a source (not shown) of hot 19 water, is connected with a port 20 adapted to feed the water tangentially to the mixer vessel inner surface 11.
21 In practice, the rate at which the oil sand is fed to 22 the mixer vessel 1 tends to be irregular. As a result, the 23 swirling vortex 18 can overflow the rim of the vessel. To cope 24 with this problem, an inwardly projecting flange 21 is provided around the rim, to serve as an annular dam. If slurry vises 26 about the dam, an overflow conduit 22 is provided to drain it 27 into the holding vessel chamber 8.
1 A line 23 and outlet pump 24 withdraw product slurry 2 from the holding vessel 7, for conveyance to the pipeline (not 3 shown).
4 The operation and performance of the mixer circuit 1 are exemplified by the following test results from a pilot run 6 using the circuit.
7 Example 8 A mixer circuit in accordance with Figure 1 was tested 9 in the field. Roy cylindrical section of the mixer vessel had a 4 foot diameter and 4 foot height, with a 15 conical section 11 at its base. A 12 inch bottom outlet was provided. A vibrating 12 screen was positioned beneath the outlet, for rejecting plus 1 13 inch material.
14 Oil sand, pre-crushed to -5 inches, was introduced at 90 tons/hour and mixed with fresh hot water (90C), added at the 16 rate of 360 gallons/minute, and recycled slurry. The slurry was 17 recycled at a rate sufficient to maintain the vortex.
18 The product from the holding vessel had a density of 19 about 1.6 (about 60% by weight solids) and temperature of about 50C. The density was consistently maintained within 10% for a 21 period of more Han 2 hours.
S BACKGROUND OF THE INVENTIQ~
6 The invention has been developed in connection with 7 mixing oil sand in hot water. While not limited to that 8 application, it will now be described in connection therewith.
9 Bitumen, a heavy oil, is currently being extracted on a commercial basis from oil sand. Presently, two very large 11 scale commercial operations are producing synthetic crude oil 12 from oil sand in the Fort McMurray district of Northern Alberta.
13 At each of these operations, the oil sand is strip-14 mined and conveyed on conveyor belts, often several kilometers in length, to an extraction plant. At the extraction plant, the 16 bitumen is separated from the solids and recovered. This is 17 accomplished using a process known as the 'hot water process'.
18 The hot water process involves mixing the oil sand with 19 hot water (95C) and a small amount of caustic in a rotating horizontal drum (or 'tumbler'). Steam is added to the mixture 21 as it moves through the tumbler, to ensure that its exit 22 temperature is about 80C. In the tumbler, the bitumen is 23 separated from the solids, lumps of the cohesive oil sand are 24 ablated and disintegrated and minute flecks of freed oil coalesce to form larger globule. In addition air bubbles are entrained 26 in the slurry. Some of the oil flecks contact air bubbles and 27 coat them, whereby the oil (or bitumen) is aerated. The term 28 "conditioning" is used to denote thy sum of the mechanisms 1 occurring in the tumbler. On leaving the tumbler, the slurry is 2 diluted with additional hot water and retained under quiescent 3 conditions for a prolonged period in a thickener-like vessel 4 referred to as a primary separation vessel ("PSV"). In the PSV, other bitumen lobules attach to and film around bubbles of air 6 entrained in the slurry. Much of the aerated bitumen rises to 7 form froth on the surface of the vessel contents. This froth is 8 recovered. drag stream is withdrawn from the central part of 9 the PSV and this drag stream is processed in a bank of sub-aerated flotation cells to produce a secondary yield of boatmen froth. The froth streams are combined and further processed to 12 remove entrained water and solids and yield essentially pure 13 bitumen.
14 Now, the belt conveyors extending between the mine and the extraction plant are characterized by a number of problems.
16 They are expensive to install, operate and maintain. And their 17 use requires that the solids, which have no value, must be 18 conveyed to the extraction plant and then returned by truck to 19 the mine pits for disposal. In addition, the tumblers cannot be increased in size to permit of improvement of the system. They 21 are presently so large that it would be technically difficult to 22 manufacture them in a larger size and convey them to the plant 23 site. As a result, it is difficult to reduce the heat 24 requirements of the process by lowering the slurry temperature, because such a step would require increasing the tumbler 26 retention time, which would necessitate larger tumblers.
27 In a co-pending application, applicants teach use of 28 a pipeline to convey an aqueous slurry of the oil sands from the 29 mine site to the extraction plant. The pipeline slurry may be 1 fed directly to the PSV, thereby eliminating the need for the 2 tumbler. The invention in the co-pending application is based 3 on the discovery that the slurry will undergo adequate 4 conditioning in the pipeline over a distance that is significantly shorter than the length of pipeline needed to get 6 Kit to the extraction plant. In addition, the slurry will not be 7 over-conditioned if it continues to move through the pipeline 8 after conditioning is complete. conditioning is considered to 9 be complete if good bitumen recovery in the form of good quality froth can be achieved in the downstream PSV.) This pipeline 11 scheme has the further advantage that most of the coarse solids 12 may be removed in a settler positioned part way along the length 13 of the pipeline.
14 So pipe lining of the oil sand in slurry form between the mine and the PSV is now considered by applicants to be a 16 viable procedure.
17 The present invention is directed toward providing a 18 mixer circuit which satisfactorily blends the oil sand with hot 19 water and entrains air to yield a consistent, dense (e.g. about 60% - 65% by weight solids) aerated slurry, preferably having a 21 relatively low temperature (e.g. 50C), that is amenable to 22 pipeline conveyance.
23 In this connection, it needs to be appreciated that oil 24 sand is tacky, cohesive, erosive material incorporating a significant content of "oversize". Oversize is a term applied I to the rocks, oil sand lumps, and clay lumps that occur in oil 27 sand (often up to a size of 20 inches.
28 If one were to feed a stream of oil sand into a tank 29 containing hot water and proceed to withdraw a mixture from the 1 base of the tank with a pump, the oil sand would simply pipe up 2 in the kink, fill it, and plug the pump. So a mixer circuit for 3 this purpose must be capable of suspending the oil sand in the water with which it is mixed.
It has been mentioned that it is desirable to produce 6 a dense slurry. This need arises from the fact that one wants 7 to minimize the amount of hot water supplied at the mine site 8 for this purpose. Heating water is expensive and there are many 9 reason why these plants need to conserve water to the maximum.
And of course the mixer circuit has to be capable of 11 coping with the oversize material. Equipment having moving 12 parts, such as a tank equipped with paddle mixers, would be 13 inappropriate for use with the erosive sand associated with 14 oversize chunks.
SUMMARY OF THE INVENTION
16 In accordance with the invention, as-mined but 17 preferably processed oil sand is mixed with streams of recycled 18 slurry and fresh hot water in the cylindrical chamber of a I vertically oriented, open-topped mixer vessel, to produce a I slurry. The slurry exits the mixing chamber through a centrally 21 positioned bottom outlet and is screened to remove oversize, 22 thereafter entering the chamber of a holding vessel. Part of the 23 slurry moving through the holding vessel is recycled, to provide 24 the previously mentioned recycled slurry stream entering the I mixer vessel. This is done by pumping it through a pipe loop ~26 that communicates with the mixing chamber through an inlet that 27 feeds the slurry tangentially to the inner surface of the mixer 28 vessel wall.
1 queue recycled slurry is therefore controllable and 2 mechanically given energy by the pump in the recycle loop. Due 3 to its tangential entry into the mixing chamber, the slurry adopts the form of a rotating vortex, into which the oil sand and fresh water are added and into which air is entrained. The oil 6 sand is fed into the vortex as a free-flowing stream that moves 7 along a downwardly extending trajectory. The trajectory is 8 directed to cause the stream of oil sand to impinge and enter the 9 vortex adjacent the latter's upper end. The added oil sand and fresh water mix with the rotating recycled slurry to produce a 11 satisfactorily consistent, dense, aerated slurry leaving the 12 mixer vessel through its bottom outlet. The intensity of the 13 vortex can be varied by adjusting the output of the recycle loop 14 pump.
In a preferred feature, the fresh water stream is 16 injected into the mixing chamber tangentially to the inner 17 surface of the mixer vessel wall. This incrementally increases 18 the energy supplied to the vortex, although the main energy 19 contributor retains the dense, pumped, recycled slurry.
The proportion of the slurry, produced by the mixer 21 vessel, which is recycled is quite large. The rate of 22 recirculation is maintained so as to ensure that the vortex is 23 capable of accepting and suspending the dry oil sand. typically 24 the rate of recirculation is 2 to 3 times the discharged slurry rate.
26 The mixer circuit is characterized by the following 27 features:
I - the mixer vessel's upright circular bounding 29 surface of relatively small diameter is coupled 1 with a pumped, dense, tangentially-directed 2 recycle stream to create a relatively thick and 3 fast-moving vortex that has been found to be 4 capable of dispersing and suspending the dry oil sand while only about 35 to 40% by weight fresh 6 water is consumed in creating the slurry;
7 - the recycle loop, having a pump, is used to 8 contribute most of the energy needed to carry out 9 the mixing function;
- the screen is provided between the two vessels to 11 remove the oversize, so that recycle and product 12 pumping can be accomplished; and 13 - the mixer vessel does not incorporate moving parts 14 and can accommodate the passage there through ox the oversize.
17 Figure 1 is a schematic sectional side view of the 18 mixer circuit.
The mixer circuit 1 comprises a vertically orientated 21 mixer vessel 2 forming a cylindrical, open-topped mixing chamber 22 3. The mixer vessel 2 has a conical bottom which forms a 23 centrally positioned bottom outlet 4.
24 A vibrating screen 5 is positioned beneath the outlet 4, to retain and reject oversize material 6 unsuitable for 26 subsequent pumping.
1 A holding vessel 7, forming an open-topped chamber 8, 2 is positioned beneath the screen 5, to receive the slurry passing 3 through the latter.
4 A recycle pipe loop 9 connects the holding vessel chamber 8 with the mixing chamber 3. The loop 9 connects with 6 an inlet port 10 adapted to feed recycled slurry tangentially to 7 the lower end of the inside surface 11 of the mixer vessel wall 8 12.
9 A variable pump 15 is connected into the recycle loop 9, for pumping slurry from the holding vessel chamber 8 into the 11 mixing chamber 3.
12 A conveyor 16 is provided to feed oil sand 17 from a 13 point spaced to one side of the vertical axis of mixer vessel 2.
14 The oil sand forms a frilling stream that follows a downward and lateral trajectory and penetrates into the slurry vortex 18, 16 which has been formed by pumping slurry through the inlet port 17 10 and into the mixing chamber 3.
18 A line 19, connected with a source (not shown) of hot 19 water, is connected with a port 20 adapted to feed the water tangentially to the mixer vessel inner surface 11.
21 In practice, the rate at which the oil sand is fed to 22 the mixer vessel 1 tends to be irregular. As a result, the 23 swirling vortex 18 can overflow the rim of the vessel. To cope 24 with this problem, an inwardly projecting flange 21 is provided around the rim, to serve as an annular dam. If slurry vises 26 about the dam, an overflow conduit 22 is provided to drain it 27 into the holding vessel chamber 8.
1 A line 23 and outlet pump 24 withdraw product slurry 2 from the holding vessel 7, for conveyance to the pipeline (not 3 shown).
4 The operation and performance of the mixer circuit 1 are exemplified by the following test results from a pilot run 6 using the circuit.
7 Example 8 A mixer circuit in accordance with Figure 1 was tested 9 in the field. Roy cylindrical section of the mixer vessel had a 4 foot diameter and 4 foot height, with a 15 conical section 11 at its base. A 12 inch bottom outlet was provided. A vibrating 12 screen was positioned beneath the outlet, for rejecting plus 1 13 inch material.
14 Oil sand, pre-crushed to -5 inches, was introduced at 90 tons/hour and mixed with fresh hot water (90C), added at the 16 rate of 360 gallons/minute, and recycled slurry. The slurry was 17 recycled at a rate sufficient to maintain the vortex.
18 The product from the holding vessel had a density of 19 about 1.6 (about 60% by weight solids) and temperature of about 50C. The density was consistently maintained within 10% for a 21 period of more Han 2 hours.
Claims (6)
1. A mixing circuit for slurring oil sand in water, comprising:
a vertically oriented open-topped mixer vessel forming a circular mixing chamber, said vessel having a centrally positioned bottom outlet leading from the chamber;
means for feeding a free-falling stream of oil sand into the upper end of the mixing chamfer;
means for introducing heated fresh water into the mixing chamber;
an open screen for screening the freely discharged slurry stream leaving the bottom outlet, to remove oversize solids;
an open-topped holding vessel for receiving the screened slurry and providing positive suction to an output pump;
and a pipe loop, incorporating a pump, connecting the holding vessel with the mixing chamber, said loop being adapted to feed recycled slurry, passing there through, tangentially to the inner surface of the mixer vessel wall to form a slurry vortex therein.
a vertically oriented open-topped mixer vessel forming a circular mixing chamber, said vessel having a centrally positioned bottom outlet leading from the chamber;
means for feeding a free-falling stream of oil sand into the upper end of the mixing chamfer;
means for introducing heated fresh water into the mixing chamber;
an open screen for screening the freely discharged slurry stream leaving the bottom outlet, to remove oversize solids;
an open-topped holding vessel for receiving the screened slurry and providing positive suction to an output pump;
and a pipe loop, incorporating a pump, connecting the holding vessel with the mixing chamber, said loop being adapted to feed recycled slurry, passing there through, tangentially to the inner surface of the mixer vessel wall to form a slurry vortex therein.
2. The mixing circuit as set forth in claim 1 wherein:
the means for introducing heated fresh water is adapted to feed it tangentially to the inner surface of the mixer vessel wall.
the means for introducing heated fresh water is adapted to feed it tangentially to the inner surface of the mixer vessel wall.
3. A continuous process for mixing oil sand with water to produce an aerated slurry, comprising:
introducing a stream of recycled slurry into a circular mixing chamber formed by an open-topped mixer vessel, so that the stream tangentially contacts the inner surface of the mixer vessel wall and forms a swirling vortex comprising a body of slurry and a central air core;
adding fresh water to the vortex;
feeding a free-falling stream of oil sand into the upper part of the vortex, whereby the oil sand, fresh water and recycled slurry mix in the vortex and entrain air to form an aerated slurry;
removing the so-produced slurry through a central outlet at the base of the mixing chamber;
screening the slurry leaving the central outlet to remove oversize solids;
collecting the slurry leaving the mixer vessel outlet in a holding vessel;
withdrawing a first stream of slurry form the holding vessel and pumping it through a pipe loop communicating with the mixing chamber, to provide the aforesaid stream of recycled slurry; and withdrawing a second stream of slurry from the holding vessel, for conveyance to a pipeline.
introducing a stream of recycled slurry into a circular mixing chamber formed by an open-topped mixer vessel, so that the stream tangentially contacts the inner surface of the mixer vessel wall and forms a swirling vortex comprising a body of slurry and a central air core;
adding fresh water to the vortex;
feeding a free-falling stream of oil sand into the upper part of the vortex, whereby the oil sand, fresh water and recycled slurry mix in the vortex and entrain air to form an aerated slurry;
removing the so-produced slurry through a central outlet at the base of the mixing chamber;
screening the slurry leaving the central outlet to remove oversize solids;
collecting the slurry leaving the mixer vessel outlet in a holding vessel;
withdrawing a first stream of slurry form the holding vessel and pumping it through a pipe loop communicating with the mixing chamber, to provide the aforesaid stream of recycled slurry; and withdrawing a second stream of slurry from the holding vessel, for conveyance to a pipeline.
4. The process as set forth in claim 3 wherein the rates of oil sand and fresh water addition and the rate of slurry recycle are controlled to produce a slurry containing in the order of 60 percent by weight solids.
5. The mixing circuit as set forth in claim 1 wherein:
a conduit interconnects the upper end of the mixing chamber with the holding vessel for draining overflow from the former to the latter.
a conduit interconnects the upper end of the mixing chamber with the holding vessel for draining overflow from the former to the latter.
6. The mixing circuit as set forth in claim 1 wherein:
the means for introducing fresh water is adapted to feed it tangentially to the inner surface of the mixer vessel wall; and a conduit interconnects the upper end of the mixing chamber with the holding vessel for draining overflow from the former to the latter.
the means for introducing fresh water is adapted to feed it tangentially to the inner surface of the mixer vessel wall; and a conduit interconnects the upper end of the mixing chamber with the holding vessel for draining overflow from the former to the latter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002000984A CA2000984C (en) | 1989-10-18 | 1989-10-18 | Mixer circuit for oil sand |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002000984A CA2000984C (en) | 1989-10-18 | 1989-10-18 | Mixer circuit for oil sand |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2000984A1 CA2000984A1 (en) | 1991-04-18 |
| CA2000984C true CA2000984C (en) | 1994-11-08 |
Family
ID=4143354
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002000984A Expired - Lifetime CA2000984C (en) | 1989-10-18 | 1989-10-18 | Mixer circuit for oil sand |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2000984C (en) |
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| CA2520821C (en) | 2005-09-23 | 2012-08-21 | Canadian Oil Sands Limited | Relocatable oil sand slurry preparation system |
-
1989
- 1989-10-18 CA CA002000984A patent/CA2000984C/en not_active Expired - Lifetime
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| JP2009145036A (en) * | 2007-08-03 | 2009-07-02 | Daher Aerospace | Airflow mixing apparatus |
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Also Published As
| Publication number | Publication date |
|---|---|
| CA2000984A1 (en) | 1991-04-18 |
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