CA2227667C - Agitated slurry pump box for oil sand hydrotransport - Google Patents
Agitated slurry pump box for oil sand hydrotransport Download PDFInfo
- Publication number
- CA2227667C CA2227667C CA002227667A CA2227667A CA2227667C CA 2227667 C CA2227667 C CA 2227667C CA 002227667 A CA002227667 A CA 002227667A CA 2227667 A CA2227667 A CA 2227667A CA 2227667 C CA2227667 C CA 2227667C
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- Canada
- Prior art keywords
- lumps
- pump box
- slurry
- oversize
- pipeline
- 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.)
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Classifications
-
- 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
- B01F23/53—Mixing liquids with solids using driven stirrers
-
- 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
- B01F23/70—Pre-treatment of the materials to be mixed
- B01F23/71—Grinding materials
-
- 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
- B01F23/70—Pre-treatment of the materials to be mixed
- B01F23/713—Sieving materials
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
- B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
- B01F27/86—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis co-operating with deflectors or baffles fixed to the receptacle
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/80—Mixing plants; Combinations of mixers
- B01F33/83—Mixing plants specially adapted for mixing in combination with disintegrating operations
- B01F33/831—Devices with consecutive working receptacles, e.g. with two intermeshing tools in one of the receptacles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/80—Mixing plants; Combinations of mixers
- B01F33/836—Mixing plants; Combinations of mixers combining mixing with other treatments
- B01F33/8361—Mixing plants; Combinations of mixers combining mixing with other treatments with disintegrating
- B01F33/83613—Mixing plants; Combinations of mixers combining mixing with other treatments with disintegrating by grinding or milling
Abstract
A large, mechanically agitated pump box is used between a mixer, for mixing oil sand and water to produce a slurry, and a pipeline for conveying the slurry to a processing facility. Prior to the aqueous slurry being discharged into the pump box from the mixer, it is screened to reject large solids. The oversize is directed to an impactor where it is comminuted and the comminuted product is screened again prior to being discharged into the pump box. The pump box is designed to increase the residence time of the slurry in the pump box and to separate the slurry into two phases, the suspended slurry and the larger lumps that cannot be suspended. The larger lumps that settle in the pump box are recycled to the impactor for comminution.
Description
2 This invention relates to an assembly and process for forming an 3 aqueous oil sand slurry, screening it to remove oversize solids, mechanically 4 agitating it and conditioning it, to produce a slurry ready for pipelining.
7 Tree McMurray oil sands of Alberta constitute one of the largest 8 deposits of hydrocarbons in the world. The oil sands are first mined at a mine 9 site and then transported to an extraction plant in order to extract the bitumen.
In recent years the preferred mode of transport of mined oil sands has been 11 by way of a slurry pipeline. The oil sand is mixed with water to form a slurry 12 that is capable of being pumped down a pipeline to the extraction plant.
13 One needs to provide a suitable means for slurrying the oil sand with 14 water and entraining air to produce a slurry that is suitable for pumping down the pipeline. The as-mined oil sand contains a variety of lumps including 16 rocks, clay and oil sand lumps. Therefore a mixer means is required that not 17 only slurries the oil sand but also ensures that oversize lumps that are 18 unsuitable for pumping and feeding into the pipeline are rejected. A
typical 19 aqueous slurry comprises the following: bitumen froth, sand, smaller lumps of oil sand, clay andlor rocks (between 0 and 2 inches in diameter) and larger 21 lumps of oil sand, clay andlor rock (between 2 and 4 inches in diameter).
22 In United States patent No. 5039227, issued to Leung et al and 23 assigned to the owners of the present application, one mixer circuit for this 24 purpose has been disclosed.
1 In the Leung et al mixer circuit, an oil sand stream is dropped from the 2 end of a conveyor into a mixer tank. The mixer tank is open-topped, has a 3 cylindrical body and conical bottom and forms a central bottom outlet. A
4 swirling vortex of slurry is maintained in the tank and the incoming oil sand and added water is fed into it. Slurry leaves the tank through the bottom 6 outlet, is screened using vibrating screens to reject oversize, and is 7 temporarily collected in an underlying pump box. Some of the slurry in the 8 pump box is withdrawn and pumped back through a return line to be 9 introduced tangentially into the mixer tank to form the swirling vortex. The balance of slurry in the pump box is withdrawn and pumped into the pipeline.
11 In Canadian patent 2,227,667, a second-generation mixer circuit in the 12 form of a vertically oriented stack of components, functions to slurry the oil 13 sand with water. The oil sand is initially dropped from the end of a conveyor 14 and is contacted in mid-air with a stream of water. The mixture drops into a downwardly slanted trough and the water and oil sand mixes as they move 16 turbulently through the open-ended trough. The slurry is deflected as it leaves 17 the trough and is spread in the form of a thin sheet on an apron. It is then fed 18 over screens to reject oversize lumps. The screened slurry drops into a pump 19 box where it is temporarily retained. The rejected lumps are comminuted in an impactor positioned at the end of the screens. The comminuted oil sand is 21 screened to remove remaining oversize lumps and the screened comminuted 22 oil sands are delivered into the pump box. The slurry in the pump box is 23 withdrawn and pumped into the pipeline.
;ET056789. D~C;1 }3 1 Both of the prior art mixer circuits routinely produce a slurry that 2 contains lumps ranging from 0 to 4 inches in diameter. Before the slurry is 3 pumped 1:o the pipeline, it is temporarily stored in a pump box. The pump box 4 is restricted to a certain volume because if the volume of retained slurry is too great, settling of the sand and lumps will occur. As a result, the residence 6 time of the slurry in the pump box is relatively short (in the order of 1 minute) 7 and the slurry is quickly pumped from the pump box to the pipeline.
8 As. the slurry travels down the pipeline, slurry conditioning or digestion 9 takes place. Adequate conditioning is critical for good bitumen recovery in a downstream separation vessel and is especially important when extracting 11 bitumen from low grade oil sand. Basically what conditioning means is that 12 the larger oil sand lumps are ablated into smaller lumps and bitumen flecks 13 coalesce and coat or attach to air bubbles. The lumps need to be dispersed 14 in water to promote the release of oil droplets and the attachment of air.
Conditioning also benefits from turbulent pipeline flow and is dependent upon 16 the length of the pipeline, hence, the length of time that the slurry resides in 17 the pipeline before reaching the separation vessel. The larger the oil sand 18 lumps, the more time required to digest or ablate these lumps to release the 19 bitumen flecks. Therefore if a slurry is routinely produced that contains large lumps, there will be a need for long pipelines or residence time.
21 An ideal slurry for fast conditioning (i.e. under 10 minutes) would be 22 one that consists of lumps that are less than 2 inches in diameter. But 23 producing such a slurry is impractical due to limitations of the prior art mixer 24 circuits. For example, in the second-generation mixer circuit, slurry routinely 2.5 contains lumps that are 2 to 4 inches in diameter. This is as a result of 1 limitations in the mixer circuit with respect to the screening process.
These 2 circuits roust accommodate large throughputs of oil sand. Therefore, the 3 screen openings must be considerably larger than 2 inches, hence, larger 4 lumps (i.~~. 2 to 4 inches in diameter) are introduced into the pipeline.
This means that the pipeline has to be a certain length to ensure sufficient 6 residencE~ time of such a slurry (preferably a minimum of 4 km to give a 7 residencE: time of approximately 12 to 15 minutes) for proper conditioning to 8 occur.
9 There may be times, however, when it is unnecessary to have such a long pipeline. But if the pipeline is too short, the residence time of the slurry in 11 the pipeline will be too short for proper conditioning of the slurry to occur.
12 This will result in a decrease in bitumen recovery. However, a pump box can 13 be designed whereby the harder to digest 2 to 4 inch lumps are segregated 14 from the rest of the slurry and are directed to an impactor where they are comminuted to small lumps. Therefore the length of the pipeline becomes 16 less critical.
18 This invention relates to an assembly and process for forming an 19 aqueous oil sand slurry whereby the slurry contains preferably lumps that are about 2 inches or less in diameter prior to the slurry being pumped to the 21 pipeline.
22 In the prior art, a pump box is used to temporarily store the aqueous 23 slurry prior to being pumped through the pipeline. In the current invention, the 24 cross-sectional area of the pump box is increased relative to what was conventional and a mixing means is added to the pump box. This 1 accomplishes two things. First, the slurry is separated into two phases: a 2 suspendE=d slurry with lumps 2 inches in diameter or less and larger lumps 3 that cannot be suspended and therefore settle to the bottom of the pump box.
4 In a preferred feature, the larger lumps that settle to the bottom are pumped out of the pump box, directed to a 2 inch screen deck and the reject lumps are 6 comminuted in an impactor. The comminuted product is delivered back to the 7 pump bo:x. Over time, the overall effect is that the slurry being introduced into 8 the pipeline contains only lumps that are about 2 inches or less. Hence, 9 conditioning of the slurry occurs much faster, thereby eliminating the need for long pipelines for conditioning.
11 Second, the actual residence time of the slurry in the pump box is 12 increased relative to the prior art due to the fact that the cross-sectional area 13 of the pump box has been increased relative to the prior art. Therefore, some 14 conditioning of the slurry will take place in the pump box itself, rather than in the pipeline. Both the volume of the pump box and the flow rate of the slurry 16 will determine the residence time of the slurry in the pump box. The following 17 equation can be used to determine the residence time:
18 volume (m3) I flow rate (m3lmin) = residence time (min).
19 In practice, it is desirable to keep the slurry flow rate relatively constant.
Thereforf~, the optimal way to increase residence time is to increase the 21 volume of the pump box. This can be achieved by increasing the cross-22 sectional area of the pump box.
1 In one broadly stated aspect of the invention, a process is 2 provided for producing an aqueous slurry of oil sand, suitable for introduction 3 into a pipeline, comprising:
4 ~ mixing oil sand and water to form an aqueous slurry containing lumps;
6 ~ screening the slurry to remove oversize lumps and produce a 7 screened slurry containing undersize lumps;
8 ~ temporarily retaining the screened slurry in a pump box for a pre-9 determined retention time;
~ mechanically agitating the slurry contained in the pump box; and 11 ~ withdrawing slurry from the pump box and pumping it into a 12 pipeline.
13 In another broadly stated aspect of the invention, a downwardly 14 sequenced assembly is provided for producing an aqueous slurry of oil sand, ready for introduction into a pipeline, comprising:
16 ~ means for mixing oil sand with water to produce a slurry containing 17 lumps;
18 ~ means for screening oversize lumps from the slurry to produce a 19 screened slurry containing undersize lumps suitable for pumping through a pipeline; and 21 ~ a pump box for receiving the screened slurry, said pump box having 22 means for mechanically agitating the slurry within the pump box, 23 said pump box being associated with a means for withdrawing 24 slurry from the pump box and pumping it into a pipeline.
{ET056789. DOC;1 }7 1 More specifically, in a preferred form, the downwardly sequenced 2 assembly for producing an aqueous slurry of oil sand, ready for introduction 3 into a pipeline, comprises:
4 ~ A conveyor having a discharge end for delivering a continuous stream of oil sand that falls through air into a trough;
6 ~ A pipe for delivering a stream of water which contacts and wets the 7 falling oil sand in mid-air;
8 ~ The trough being downwardly slanted, open-topped and positioned 9 in spaced relation below the conveyor discharge end and the water pipe. The trough is operative to receive the mixture of oil sand and 11 water and confine it temporarily to allow the oil sand and water to 12 turbulently mix and form a slurry. stream as they flow along its 13 length and discharge from its open lower end;
14 ~ An upstanding wall positioned adjacent the trough's lower end and spaced therefrom so that the slurry stream hits it and is deflected, 16 with the result that its direction of flow is changed and further mixing 17 is induced;
18 ~ An apron providing a broad surface for receiving the deflected 19 stream, whereby the stream is spread out and thinned to form a slurry sheet adapted to efficiently utilize the screen area;
21 ~ A first screen assembly for receiving and screening the slurry sheet 22 to reject oversize and produce a screened slurry stream;
23 ~ A pump box for receiving and temporarily retaining the screened 24 slurry;
1 ~ A mechanical agitator in the pump box for separating the screened 2 slurry into two phases, the slurry containing suspended lumps and 3 the larger lumps that cannot be suspended; and 4 ~ A means for withdrawing suspended slurry from the pump box and delivering the slurry into the pipeline.
6 In a preferred extension of the invention, the rejected oversize lumps 7 from the first screen assembly are fed directly into an impactor and 8 comminuted. The comminuted product is screened by a second screen 9 assembly to reject remaining oversize. The comminuted, screened product is then delivered into the mechanically agitated pump box.
11 In a second preferred extension of the invention, the mechanically 12 agitated pump box is equipped with a means for recycling lumps reaching the 13 bottom of the pump box, preferably by withdrawing them tangentially from the 14 bottom of the pump box. These lumps are delivered to a third screen which may be attached to the first screen assembly. The rejected oversize lumps 16 are then fed directly into the impactor to be comminuted in the impactor.
The 17 comminuted product is then delivered into the mechanically agitated pump 18 box.
DESCRIPTION OF THE DRAWLNGS
21 Figure 1 is a schematic side view showing the preferred embodiment of 22 the invention.
2 As-mined oil sand to be pipelined is first crushed before conveying it to a 3 mixer circuit 1. This is commonly done by passing it through a set of double 4 rolls, producing 24-inch product. This pre-treatment (which forms no part of the invention;l is done to break down the very large contained lumps.
6 The crushed oil sand contains lumps of varying size and composition.
7 The mixer circuit 1 comprises a series of downwardly arranged 8 components.
9 The uppermost component is a conveyor 2 for continuously delivering a stream of crushed oil sand 3. The oil sand cascades or falls from the discharge 11 end 4 of the conveyor 2 - it drops downwardly through an air space 5.
12 A horizontal pipe 6 is positioned opposite to the conveyor discharge end 13 4. The pipe discharges a stream 7 of water into the falling oil sand in mid-air at 14 a sufficient rate so that the water/oil sand ratio is equivalent to that of the pipeline slurry. Typically this ratio is about 1:3 by weight. The stream 7 16 contacts ~:he downwardly descending oil sand and is distributed through it and 17 wets it.
18 The oil sand and water drop into a downwardly slanted, open-topped, 19 open-ended trough 8. The trough is formed of plate steel.
As the oil sand and water move through the trough, they mix turbulently 21 and form a slurry.
22 A solid, vertical wall 10 formed of steel is positioned adjacent the lower 23 end 11 of the trough 8. The wall 10 is spaced from the trough's lower end 2.4 and extends across the trajectory path of the slurry stream 13 discharging from the trough.
i A downwardly slanted apron 14 extends downwardly from the wall 10 in 2 a direction opposite to that of the trough 8.
3 The slurry stream 13 hits the wall 10, is deflected and changes its 4 direction of movement, being discharged onto an apron 14. In the course of these movements, further turbulent mixing of the oil sand and water occurs. On 6 reaching a second apron 31, the slurry spreads out laterally and is thinned, to 7 form a slurry sheet 15 of comparable width to the screen 16.
8 The slurry sheet 15 flows from the second apron 31 onto a contiguous 9 first vibrating screen 16. It is sized to retain +4 inch material.
The oversize lumps 20 retained by the vibrating screen 16 are delivered 11 into an impactor 24. The lumps 20 are largely oii sand in composition and 12 many disintegrate when impacted by the rotating arms of the impactor, 13 producing comminuted product 27. This product discharges from the outlet of 14 the impactor onto a second vibrating screen 30. The oversize lumps retained by screen 30 are discarded. The screened comminuted product, containing 16 undersize lumps that passed through the screen 16, is discharged into pump 17 box 18.
18 Pump box 18 is equipped with a vertical shaft agitator 21 that 19 mechanically agitates the collected screened slurry such that a vortex 22 is created. The pump box is further equipped with at least one vortex breaker 21 plate 23 positioned so as to allow the vortex 22 to form at the bottom of the 22 pump box. Much of the slurry remains in suspension and only the larger lumps 23 25 (between 2 and 4 inches in diameter) settle to the bottom of the pump box 24 18. The larger lumps are pumped from a tangential outlet 26 and are delivered to a third vibrating screen 28 that is sized to retain +2 inch material. The SEross7as.~oc;i}11 1 oversize lumps 29 retained by the screen 28 are delivered into the impactor 24.
2 Most of the oversize lumps are disintegrated when impacted by the rotating 3 arms of the impactor 24. The comminuted product is discharged into the pump 4 box 18. Ultimately, the suspended slurry in the pump box is pumped from an outlet 19 into a pipeline.
6 The foregoing describes our best mode of carrying out the invention.
7 As will be realized, the invention is capable of other and different 8 embodiments and its several details are capable of variation, all without 9 departing from the invention. The scope of the invention is established in the claims now following.
(ET056789.DOC;1 }12
7 Tree McMurray oil sands of Alberta constitute one of the largest 8 deposits of hydrocarbons in the world. The oil sands are first mined at a mine 9 site and then transported to an extraction plant in order to extract the bitumen.
In recent years the preferred mode of transport of mined oil sands has been 11 by way of a slurry pipeline. The oil sand is mixed with water to form a slurry 12 that is capable of being pumped down a pipeline to the extraction plant.
13 One needs to provide a suitable means for slurrying the oil sand with 14 water and entraining air to produce a slurry that is suitable for pumping down the pipeline. The as-mined oil sand contains a variety of lumps including 16 rocks, clay and oil sand lumps. Therefore a mixer means is required that not 17 only slurries the oil sand but also ensures that oversize lumps that are 18 unsuitable for pumping and feeding into the pipeline are rejected. A
typical 19 aqueous slurry comprises the following: bitumen froth, sand, smaller lumps of oil sand, clay andlor rocks (between 0 and 2 inches in diameter) and larger 21 lumps of oil sand, clay andlor rock (between 2 and 4 inches in diameter).
22 In United States patent No. 5039227, issued to Leung et al and 23 assigned to the owners of the present application, one mixer circuit for this 24 purpose has been disclosed.
1 In the Leung et al mixer circuit, an oil sand stream is dropped from the 2 end of a conveyor into a mixer tank. The mixer tank is open-topped, has a 3 cylindrical body and conical bottom and forms a central bottom outlet. A
4 swirling vortex of slurry is maintained in the tank and the incoming oil sand and added water is fed into it. Slurry leaves the tank through the bottom 6 outlet, is screened using vibrating screens to reject oversize, and is 7 temporarily collected in an underlying pump box. Some of the slurry in the 8 pump box is withdrawn and pumped back through a return line to be 9 introduced tangentially into the mixer tank to form the swirling vortex. The balance of slurry in the pump box is withdrawn and pumped into the pipeline.
11 In Canadian patent 2,227,667, a second-generation mixer circuit in the 12 form of a vertically oriented stack of components, functions to slurry the oil 13 sand with water. The oil sand is initially dropped from the end of a conveyor 14 and is contacted in mid-air with a stream of water. The mixture drops into a downwardly slanted trough and the water and oil sand mixes as they move 16 turbulently through the open-ended trough. The slurry is deflected as it leaves 17 the trough and is spread in the form of a thin sheet on an apron. It is then fed 18 over screens to reject oversize lumps. The screened slurry drops into a pump 19 box where it is temporarily retained. The rejected lumps are comminuted in an impactor positioned at the end of the screens. The comminuted oil sand is 21 screened to remove remaining oversize lumps and the screened comminuted 22 oil sands are delivered into the pump box. The slurry in the pump box is 23 withdrawn and pumped into the pipeline.
;ET056789. D~C;1 }3 1 Both of the prior art mixer circuits routinely produce a slurry that 2 contains lumps ranging from 0 to 4 inches in diameter. Before the slurry is 3 pumped 1:o the pipeline, it is temporarily stored in a pump box. The pump box 4 is restricted to a certain volume because if the volume of retained slurry is too great, settling of the sand and lumps will occur. As a result, the residence 6 time of the slurry in the pump box is relatively short (in the order of 1 minute) 7 and the slurry is quickly pumped from the pump box to the pipeline.
8 As. the slurry travels down the pipeline, slurry conditioning or digestion 9 takes place. Adequate conditioning is critical for good bitumen recovery in a downstream separation vessel and is especially important when extracting 11 bitumen from low grade oil sand. Basically what conditioning means is that 12 the larger oil sand lumps are ablated into smaller lumps and bitumen flecks 13 coalesce and coat or attach to air bubbles. The lumps need to be dispersed 14 in water to promote the release of oil droplets and the attachment of air.
Conditioning also benefits from turbulent pipeline flow and is dependent upon 16 the length of the pipeline, hence, the length of time that the slurry resides in 17 the pipeline before reaching the separation vessel. The larger the oil sand 18 lumps, the more time required to digest or ablate these lumps to release the 19 bitumen flecks. Therefore if a slurry is routinely produced that contains large lumps, there will be a need for long pipelines or residence time.
21 An ideal slurry for fast conditioning (i.e. under 10 minutes) would be 22 one that consists of lumps that are less than 2 inches in diameter. But 23 producing such a slurry is impractical due to limitations of the prior art mixer 24 circuits. For example, in the second-generation mixer circuit, slurry routinely 2.5 contains lumps that are 2 to 4 inches in diameter. This is as a result of 1 limitations in the mixer circuit with respect to the screening process.
These 2 circuits roust accommodate large throughputs of oil sand. Therefore, the 3 screen openings must be considerably larger than 2 inches, hence, larger 4 lumps (i.~~. 2 to 4 inches in diameter) are introduced into the pipeline.
This means that the pipeline has to be a certain length to ensure sufficient 6 residencE~ time of such a slurry (preferably a minimum of 4 km to give a 7 residencE: time of approximately 12 to 15 minutes) for proper conditioning to 8 occur.
9 There may be times, however, when it is unnecessary to have such a long pipeline. But if the pipeline is too short, the residence time of the slurry in 11 the pipeline will be too short for proper conditioning of the slurry to occur.
12 This will result in a decrease in bitumen recovery. However, a pump box can 13 be designed whereby the harder to digest 2 to 4 inch lumps are segregated 14 from the rest of the slurry and are directed to an impactor where they are comminuted to small lumps. Therefore the length of the pipeline becomes 16 less critical.
18 This invention relates to an assembly and process for forming an 19 aqueous oil sand slurry whereby the slurry contains preferably lumps that are about 2 inches or less in diameter prior to the slurry being pumped to the 21 pipeline.
22 In the prior art, a pump box is used to temporarily store the aqueous 23 slurry prior to being pumped through the pipeline. In the current invention, the 24 cross-sectional area of the pump box is increased relative to what was conventional and a mixing means is added to the pump box. This 1 accomplishes two things. First, the slurry is separated into two phases: a 2 suspendE=d slurry with lumps 2 inches in diameter or less and larger lumps 3 that cannot be suspended and therefore settle to the bottom of the pump box.
4 In a preferred feature, the larger lumps that settle to the bottom are pumped out of the pump box, directed to a 2 inch screen deck and the reject lumps are 6 comminuted in an impactor. The comminuted product is delivered back to the 7 pump bo:x. Over time, the overall effect is that the slurry being introduced into 8 the pipeline contains only lumps that are about 2 inches or less. Hence, 9 conditioning of the slurry occurs much faster, thereby eliminating the need for long pipelines for conditioning.
11 Second, the actual residence time of the slurry in the pump box is 12 increased relative to the prior art due to the fact that the cross-sectional area 13 of the pump box has been increased relative to the prior art. Therefore, some 14 conditioning of the slurry will take place in the pump box itself, rather than in the pipeline. Both the volume of the pump box and the flow rate of the slurry 16 will determine the residence time of the slurry in the pump box. The following 17 equation can be used to determine the residence time:
18 volume (m3) I flow rate (m3lmin) = residence time (min).
19 In practice, it is desirable to keep the slurry flow rate relatively constant.
Thereforf~, the optimal way to increase residence time is to increase the 21 volume of the pump box. This can be achieved by increasing the cross-22 sectional area of the pump box.
1 In one broadly stated aspect of the invention, a process is 2 provided for producing an aqueous slurry of oil sand, suitable for introduction 3 into a pipeline, comprising:
4 ~ mixing oil sand and water to form an aqueous slurry containing lumps;
6 ~ screening the slurry to remove oversize lumps and produce a 7 screened slurry containing undersize lumps;
8 ~ temporarily retaining the screened slurry in a pump box for a pre-9 determined retention time;
~ mechanically agitating the slurry contained in the pump box; and 11 ~ withdrawing slurry from the pump box and pumping it into a 12 pipeline.
13 In another broadly stated aspect of the invention, a downwardly 14 sequenced assembly is provided for producing an aqueous slurry of oil sand, ready for introduction into a pipeline, comprising:
16 ~ means for mixing oil sand with water to produce a slurry containing 17 lumps;
18 ~ means for screening oversize lumps from the slurry to produce a 19 screened slurry containing undersize lumps suitable for pumping through a pipeline; and 21 ~ a pump box for receiving the screened slurry, said pump box having 22 means for mechanically agitating the slurry within the pump box, 23 said pump box being associated with a means for withdrawing 24 slurry from the pump box and pumping it into a pipeline.
{ET056789. DOC;1 }7 1 More specifically, in a preferred form, the downwardly sequenced 2 assembly for producing an aqueous slurry of oil sand, ready for introduction 3 into a pipeline, comprises:
4 ~ A conveyor having a discharge end for delivering a continuous stream of oil sand that falls through air into a trough;
6 ~ A pipe for delivering a stream of water which contacts and wets the 7 falling oil sand in mid-air;
8 ~ The trough being downwardly slanted, open-topped and positioned 9 in spaced relation below the conveyor discharge end and the water pipe. The trough is operative to receive the mixture of oil sand and 11 water and confine it temporarily to allow the oil sand and water to 12 turbulently mix and form a slurry. stream as they flow along its 13 length and discharge from its open lower end;
14 ~ An upstanding wall positioned adjacent the trough's lower end and spaced therefrom so that the slurry stream hits it and is deflected, 16 with the result that its direction of flow is changed and further mixing 17 is induced;
18 ~ An apron providing a broad surface for receiving the deflected 19 stream, whereby the stream is spread out and thinned to form a slurry sheet adapted to efficiently utilize the screen area;
21 ~ A first screen assembly for receiving and screening the slurry sheet 22 to reject oversize and produce a screened slurry stream;
23 ~ A pump box for receiving and temporarily retaining the screened 24 slurry;
1 ~ A mechanical agitator in the pump box for separating the screened 2 slurry into two phases, the slurry containing suspended lumps and 3 the larger lumps that cannot be suspended; and 4 ~ A means for withdrawing suspended slurry from the pump box and delivering the slurry into the pipeline.
6 In a preferred extension of the invention, the rejected oversize lumps 7 from the first screen assembly are fed directly into an impactor and 8 comminuted. The comminuted product is screened by a second screen 9 assembly to reject remaining oversize. The comminuted, screened product is then delivered into the mechanically agitated pump box.
11 In a second preferred extension of the invention, the mechanically 12 agitated pump box is equipped with a means for recycling lumps reaching the 13 bottom of the pump box, preferably by withdrawing them tangentially from the 14 bottom of the pump box. These lumps are delivered to a third screen which may be attached to the first screen assembly. The rejected oversize lumps 16 are then fed directly into the impactor to be comminuted in the impactor.
The 17 comminuted product is then delivered into the mechanically agitated pump 18 box.
DESCRIPTION OF THE DRAWLNGS
21 Figure 1 is a schematic side view showing the preferred embodiment of 22 the invention.
2 As-mined oil sand to be pipelined is first crushed before conveying it to a 3 mixer circuit 1. This is commonly done by passing it through a set of double 4 rolls, producing 24-inch product. This pre-treatment (which forms no part of the invention;l is done to break down the very large contained lumps.
6 The crushed oil sand contains lumps of varying size and composition.
7 The mixer circuit 1 comprises a series of downwardly arranged 8 components.
9 The uppermost component is a conveyor 2 for continuously delivering a stream of crushed oil sand 3. The oil sand cascades or falls from the discharge 11 end 4 of the conveyor 2 - it drops downwardly through an air space 5.
12 A horizontal pipe 6 is positioned opposite to the conveyor discharge end 13 4. The pipe discharges a stream 7 of water into the falling oil sand in mid-air at 14 a sufficient rate so that the water/oil sand ratio is equivalent to that of the pipeline slurry. Typically this ratio is about 1:3 by weight. The stream 7 16 contacts ~:he downwardly descending oil sand and is distributed through it and 17 wets it.
18 The oil sand and water drop into a downwardly slanted, open-topped, 19 open-ended trough 8. The trough is formed of plate steel.
As the oil sand and water move through the trough, they mix turbulently 21 and form a slurry.
22 A solid, vertical wall 10 formed of steel is positioned adjacent the lower 23 end 11 of the trough 8. The wall 10 is spaced from the trough's lower end 2.4 and extends across the trajectory path of the slurry stream 13 discharging from the trough.
i A downwardly slanted apron 14 extends downwardly from the wall 10 in 2 a direction opposite to that of the trough 8.
3 The slurry stream 13 hits the wall 10, is deflected and changes its 4 direction of movement, being discharged onto an apron 14. In the course of these movements, further turbulent mixing of the oil sand and water occurs. On 6 reaching a second apron 31, the slurry spreads out laterally and is thinned, to 7 form a slurry sheet 15 of comparable width to the screen 16.
8 The slurry sheet 15 flows from the second apron 31 onto a contiguous 9 first vibrating screen 16. It is sized to retain +4 inch material.
The oversize lumps 20 retained by the vibrating screen 16 are delivered 11 into an impactor 24. The lumps 20 are largely oii sand in composition and 12 many disintegrate when impacted by the rotating arms of the impactor, 13 producing comminuted product 27. This product discharges from the outlet of 14 the impactor onto a second vibrating screen 30. The oversize lumps retained by screen 30 are discarded. The screened comminuted product, containing 16 undersize lumps that passed through the screen 16, is discharged into pump 17 box 18.
18 Pump box 18 is equipped with a vertical shaft agitator 21 that 19 mechanically agitates the collected screened slurry such that a vortex 22 is created. The pump box is further equipped with at least one vortex breaker 21 plate 23 positioned so as to allow the vortex 22 to form at the bottom of the 22 pump box. Much of the slurry remains in suspension and only the larger lumps 23 25 (between 2 and 4 inches in diameter) settle to the bottom of the pump box 24 18. The larger lumps are pumped from a tangential outlet 26 and are delivered to a third vibrating screen 28 that is sized to retain +2 inch material. The SEross7as.~oc;i}11 1 oversize lumps 29 retained by the screen 28 are delivered into the impactor 24.
2 Most of the oversize lumps are disintegrated when impacted by the rotating 3 arms of the impactor 24. The comminuted product is discharged into the pump 4 box 18. Ultimately, the suspended slurry in the pump box is pumped from an outlet 19 into a pipeline.
6 The foregoing describes our best mode of carrying out the invention.
7 As will be realized, the invention is capable of other and different 8 embodiments and its several details are capable of variation, all without 9 departing from the invention. The scope of the invention is established in the claims now following.
(ET056789.DOC;1 }12
Claims (11)
1. A downwardly sequenced assembly for producing an aqueous slurry of oil sand, ready for introduction into a pipeline, comprising:
means for mixing oil sand with water to produce a slurry containing lumps;
means for screening oversize lumps from the slurry to produce a screened slurry containing undersize lumps suitable for pumping through a pipeline; and a pump box for receiving the screened slurry, said pump box having means for mechanically agitating the slurry within the pump box, said pump box being associated with a means for withdrawing slurry from the pump box and pumping it into a pipeline.
means for mixing oil sand with water to produce a slurry containing lumps;
means for screening oversize lumps from the slurry to produce a screened slurry containing undersize lumps suitable for pumping through a pipeline; and a pump box for receiving the screened slurry, said pump box having means for mechanically agitating the slurry within the pump box, said pump box being associated with a means for withdrawing slurry from the pump box and pumping it into a pipeline.
2. The assembly as set forth in claim 1 comprising:
an impactor, associated with the screening means, for receiving the screened oversize lumps, comminuting them to produce comminuted solids and screening the comminuted solids to reject remaining oversize and pass solids suitable for pumping through the pipeline; and means for downwardly transferring the screened comminuted solids into the pump box.
an impactor, associated with the screening means, for receiving the screened oversize lumps, comminuting them to produce comminuted solids and screening the comminuted solids to reject remaining oversize and pass solids suitable for pumping through the pipeline; and means for downwardly transferring the screened comminuted solids into the pump box.
3. The assembly as set forth in claim 2 comprising:
means for recycling a stream of slurry from the base of the pump box, said stream containing lumps that have reached the bottom of the pump box;
a screening means for processing the recycled slurry to remove oversize lumps, feeding said oversize lumps to the impactor and returning screened slurry to the pump box.
means for recycling a stream of slurry from the base of the pump box, said stream containing lumps that have reached the bottom of the pump box;
a screening means for processing the recycled slurry to remove oversize lumps, feeding said oversize lumps to the impactor and returning screened slurry to the pump box.
4. A process for producing an aqueous slurry of oil sand, suitable for introduction into a pipeline, comprising:
mixing oil sand and water to form an aqueous slurry containing lumps;
screening the slurry to remove oversize lumps and produce a screened slurry containing undersize lumps;
temporarily retaining the screened slurry in a pump box for a pre-determined retention time;
mechanically agitating the slurry contained in the pump box; and withdrawing slurry from the pump box and pumping it into a pipeline.
mixing oil sand and water to form an aqueous slurry containing lumps;
screening the slurry to remove oversize lumps and produce a screened slurry containing undersize lumps;
temporarily retaining the screened slurry in a pump box for a pre-determined retention time;
mechanically agitating the slurry contained in the pump box; and withdrawing slurry from the pump box and pumping it into a pipeline.
5. A process as set forth in claim 4 comprising:
comminuting rejected oversize lumps from the screening step and screening the comminuted solids to reject residual oversize lumps; and discharging the comminuted solids into the pump box.
comminuting rejected oversize lumps from the screening step and screening the comminuted solids to reject residual oversize lumps; and discharging the comminuted solids into the pump box.
6. A process as set forth in claim 5 comprising:~
recycling lumps reaching the bottom of the pump box back to a screening means;
re-comminuting rejected oversize lumps from the screening means;
and discharging the re-comminuted product into the pump box.
recycling lumps reaching the bottom of the pump box back to a screening means;
re-comminuting rejected oversize lumps from the screening means;
and discharging the re-comminuted product into the pump box.
7. A process for producing an aqueous slurry of oil sand, ready for introduction into a pipeline, comprising:
dropping the oil sand through the air from the discharge end of a conveyor onto a downwardly slanted surface spaced below the conveyor discharge end;
contacting the oil sand with a steam of water as the oil sand moves through the air between the conveyor discharge end and the surface, to wet the oil sand;
mixing the oil sand and water as they move together along the surface, to form a slurry stream;
discharging the slurry stream onto a first screen means and screening it to reject oversize lumps;
directing the oversize lumps to an impactor, comminuting the oversize lumps and discharging the comminuted product onto a second screen means and screening it to reject oversize lumps;
directing the screened slurry into a pump box prior to pumping it into a pipeline;
mechanically agitating the slurry in the pump box by means of a vertical shaft agitator such that the smaller lumps, sand and bitumen are kept in suspension but the larger lumps settle to the bottom of the pump box;
pumping the larger lumps out of the pump box, delivering the larger lumps onto a third screen assembly, and screening the lumps to reject oversize lumps;
directing the recycled oversize lumps to an impactor, comminuting the oversize lumps and discharging the comminuted product back into the mechanically agitated pump box;
pumping the produced slurry out of the mechanically agitated pump box and into the pipeline.
dropping the oil sand through the air from the discharge end of a conveyor onto a downwardly slanted surface spaced below the conveyor discharge end;
contacting the oil sand with a steam of water as the oil sand moves through the air between the conveyor discharge end and the surface, to wet the oil sand;
mixing the oil sand and water as they move together along the surface, to form a slurry stream;
discharging the slurry stream onto a first screen means and screening it to reject oversize lumps;
directing the oversize lumps to an impactor, comminuting the oversize lumps and discharging the comminuted product onto a second screen means and screening it to reject oversize lumps;
directing the screened slurry into a pump box prior to pumping it into a pipeline;
mechanically agitating the slurry in the pump box by means of a vertical shaft agitator such that the smaller lumps, sand and bitumen are kept in suspension but the larger lumps settle to the bottom of the pump box;
pumping the larger lumps out of the pump box, delivering the larger lumps onto a third screen assembly, and screening the lumps to reject oversize lumps;
directing the recycled oversize lumps to an impactor, comminuting the oversize lumps and discharging the comminuted product back into the mechanically agitated pump box;
pumping the produced slurry out of the mechanically agitated pump box and into the pipeline.
8. The process as set forth in claim 4 wherein the retained oversize lumps are larger than about 4 inches and retention time in the pump box is sufficient to allow lumps in the size range of about 2 - 4 inches to settle to the bottom of the pump box while lumps smaller than about 2 inches remain suspended and are pumped into the pipeline.
9. The process as set forth in claim 4 wherein the retained oversize lumps are larger than about 4 inches and retention time in the pump box is sufficient to allow lumps in the size range of about 2 - 4 inches to settle to the bottom of the pump box while lumps smaller than about 2 inches remain suspended and are pumped into the pipeline; and recycling lumps reaching the bottom of the pump box back to a screening means;
re-comminuting rejected oversize lumps from the screening means;
and discharging the re-comminuted product into the pump box.
re-comminuting rejected oversize lumps from the screening means;
and discharging the re-comminuted product into the pump box.
10. The assembly as set forth in claim 1 wherein:
the screening means is adapted to retain oversize lumps greater than about 4 inches in size; and the pump box and agitation means are selected so as to maintain lumps smaller than about 2 inches in size in suspension while lumps of about 2 to 4 inches in size settle to the bottom of the pump box.
the screening means is adapted to retain oversize lumps greater than about 4 inches in size; and the pump box and agitation means are selected so as to maintain lumps smaller than about 2 inches in size in suspension while lumps of about 2 to 4 inches in size settle to the bottom of the pump box.
11. The assembly as set forth in claim 10 comprising:
an impactor, associated with the screening means, for receiving the screened oversize lumps, comminuting them to produce comminuted solids and screening the comminuted solids to reject remaining oversize and pass solids suitable for pumping through the pipeline; and means for downwardly transferring the screened comminuted solids into the pump box;
means for recycling a stream of slurry from the base of the pump box, said stream containing lumps that have reached the bottom of the pump box;
and a screening means for processing the recycled slurry to remove oversize lumps, feeding said oversize lumps to the impactor and returning screened slurry to the pump box.
an impactor, associated with the screening means, for receiving the screened oversize lumps, comminuting them to produce comminuted solids and screening the comminuted solids to reject remaining oversize and pass solids suitable for pumping through the pipeline; and means for downwardly transferring the screened comminuted solids into the pump box;
means for recycling a stream of slurry from the base of the pump box, said stream containing lumps that have reached the bottom of the pump box;
and a screening means for processing the recycled slurry to remove oversize lumps, feeding said oversize lumps to the impactor and returning screened slurry to the pump box.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002227667A CA2227667C (en) | 1998-01-22 | 1998-01-22 | Agitated slurry pump box for oil sand hydrotransport |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002227667A CA2227667C (en) | 1998-01-22 | 1998-01-22 | Agitated slurry pump box for oil sand hydrotransport |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2227667A1 CA2227667A1 (en) | 1999-07-22 |
| CA2227667C true CA2227667C (en) | 2002-11-05 |
Family
ID=4162008
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002227667A Expired - Lifetime CA2227667C (en) | 1998-01-22 | 1998-01-22 | Agitated slurry pump box for oil sand hydrotransport |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2227667C (en) |
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| US7914670B2 (en) | 2004-01-09 | 2011-03-29 | Suncor Energy Inc. | Bituminous froth inline steam injection processing |
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