BITUMEN PRODUCTION FROM SINGLE OR MULTIPLE OIL SAND MINES
20170081592 ยท 2017-03-23
Inventors
- Jonathan Spence (Edmonton, CA)
- Yin Ming Samson Ng (Sherwood Park, CA)
- Robert Siy (Edmonton, CA)
- Barry BARA (Edmonton, CA)
- JUN LONG (Edmonton, CA)
- Kevin Reid (Edmonton, CA)
- James LORENTZ (Fort McMurray, CA)
- Shane Hoskins (Edmonton, CA)
Cpc classification
International classification
Abstract
A process for operating multiple oil sand mine sites for extracting bitumen from oil sand is disclosed, comprising preparing a first conditioned oil sand slurry at a first location using a first oil sand slurry preparation and slurry conditioning process; preparing a second conditioned oil sand slurry at a second location using a second oil sand slurry preparation and slurry conditioning process; combining the first conditioned oil sand slurry and the second conditioned oil sand slurry in at least one slurry distributor to produce a combined oil sand slurry; and distributing the combined oil sand slurry to at least one separation vessel to produce bitumen froth.
Claims
1. A process for operating multiple oil sand mine sites for extracting bitumen from oil sand, comprising: (a) preparing a first conditioned oil sand slurry at a first location using a first oil sand slurry preparation and slurry conditioning process; (b) preparing a second conditioned oil sand slurry at a second location using a second oil sand slurry preparation and slurry conditioning process; (c) combining the first conditioned oil sand slurry and the second conditioned oil sand slurry in at least one slurry distributor to produce a combined oil sand slurry; and (d) distributing the combined oil sand slurry to at least one separation vessel to produce bitumen froth.
2. The process as claimed in claim 1, wherein the combined oil sand slurry is distributed to at least two separation vessels to produce at least two bitumen froths.
3. The process as claimed in claim 2, wherein the at least two bitumen froths from the at least two separation vessels are combined in at least one froth storage tank.
4. The process as claimed in claim 1, wherein the at least one separation vessel is a gravity separation vessel.
5. The process as claimed in claim 1, wherein the first location and the second location are at a single mine site.
6. The process as claimed in claim 1, wherein the first location and the second location are at different mine sites.
7. The process as claimed in claim 1, wherein the first slurry preparation and conditioning process and the second slurry preparation and conditioning process are the same.
8. The process as claimed in claim 1, wherein the first slurry preparation and conditioning process and the second slurry preparation and conditioning process are different.
9. The process as claimed in claim 3, wherein the at least two bitumen froths are deaerated prior to storage in the at least one froth storage tank.
10. The process as claimed in claim 1, further comprising deaerating the bitumen froth and storing the deaerated bitumen froth in at least one froth storage tank.
11. The process as claimed in claim 10, further comprising subjecting the deaerated bitumen froth to further treatment to reduce the solids and water content therein.
12. The process as claimed in claim 11, wherein the treatment comprises naphtha froth treatment.
13. The process as claimed in claim 11, wherein the treatment comprises paraffinic froth treatment.
14. The process as claimed in claim 11, wherein the deaerated froth is heated prior to further treatment to reduce the solids and water content therein.
15. A process for operating multiple oil sand mine sites for extracting bitumen from oil sand, comprising: (a) preparing a first conditioned oil sand slurry at a first mine site using a first slurry preparation and conditioning process and subjecting the first conditioned oil sand slurry to a first bitumen separation process to produce a first bitumen froth; (b) preparing a second conditioned oil sand slurry at a second mine site using a second slurry preparation and conditioning process and subjecting the second conditioned oil sand slurry to a second bitumen separation process to produce a second bitumen froth; (c) combining the first bitumen froth and the second bitumen froth in at least one froth storage tank to produce a combined bitumen froth; and (d) subjecting the combined bitumen froth to further treatment to reduce the solids and water content therein.
16. The process as claimed in claim 15, wherein the first bitumen froth and the second bitumen froth are deaerated prior to combining them in the at least one froth storage tank.
17. The process as claimed in claim 15, wherein the first bitumen froth is heated prior to combining it with the second bitumen froth.
18. The process as claimed in claim 15, wherein the first mine site is remote from the second mine site and the first bitumen froth is transported to the second mine site by means of a froth pipeline.
19. A process for operating multiple oil sand mine sites for extracting bitumen from oil sand, comprising: (a) preparing a first conditioned oil sand slurry at a first mine site using a first slurry preparation and conditioning process and subjecting the first conditioned oil sand slurry to a first bitumen separation process to produce a first bitumen froth; (b) transporting the first bitumen froth to a second mine site by means of a froth pipeline and combining the first bitumen froth with oil sand ore mined at the second mine site and water; and (c) preparing a second conditioned oil sand slurry using the combined first bitumen froth, the oil sand ore mined at the second mine site and water using a second slurry preparation and conditioning process and subjecting the second conditioned oil sand slurry to a second bitumen separation process to produce a second bitumen froth.
20. The process as claimed in claim 19, wherein the second slurry preparation and conditioning process and the second bitumen separation process combined is a warm slurry process.
21. The process as claimed in claim 19, wherein the second slurry preparation and conditioning process and the second bitumen separation process combined is a hot water process.
22. The process as claimed in claim 19, wherein the first slurry preparation and conditioning process and the first bitumen separation process combined is a low energy process.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0042] The following drawings form part of the specification and are included to further demonstrate certain embodiments or various aspects of the invention. In some instances, embodiments of the invention can be best understood by referring to the accompanying drawings in combination with the detailed description presented herein. The description and accompanying drawings may highlight a certain specific example, or a certain aspect of the invention. However, one skilled in the art will understand that portions of the example or aspect may be used in combination with other examples or aspects of the invention.
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[0045]
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[0048]
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0049] The invention is exemplified by the following description and examples.
[0050] A schematic of two different slurry preparation and conditioning process trains, train 10 and train 20, operating at two different mine sites that are integrated according to the present invention is shown in
[0051] Train 10 comprises mined oil sand being delivered by trucks 12 to a hopper 14 having an apron feeder 16 therebelow for feeding mined oil sand to a double roll crusher 18 to produce pre-crushed oil sand. Surge feed conveyor 26 delivers pre-crushed oil sand to surge facility 22 comprising surge bin 28 and surge apron feeders 30 therebelow. Air 24 is injected into surge bin 28 to prevent the oil sand from plugging.
[0052] The surge apron feeders 30 feed the pre-crushed oil sand to cyclofeeder conveyer 32, which, in turn, delivers the oil sand to cyclofeeder vessel 34 where the oil sand and water 36 are mixed to form oil sand slurry 40. Oil sand slurry 40 is then screened in screen 38 and screened oil sand slurry 41 is transferred to pump box 42. The cyclofeeder system is described in U.S. Pat. No. 5,039,227. Optionally, oversize lumps from screens 38 are sent to secondary reprocessing (not shown). Oil sand slurry 45 is then conditioned by pumping the slurry through a hydrotransport pipeline 46, from which conditioned oil sand slurry 48 is delivered to slurry distribution vessel 50 (also referred to herein as superpot). A portion of oil sand slurry 44 can be recycled back to cyclofeeder 34.
[0053] Train 20 comprises tumbler oil sand feed 13 being delivered by truck 11 and fed into tumbler 19. Tumbler hot water 15, caustic 17 (e.g., sodium hydroxide) and steam 21 are also added to tumbler 19 where the oil sand is mixed with the water to form a conditioned oil sand slurry. Residence time of the slurry in the tumbler is generally around 2.0 to 4.0 minutes. The slurry is then screened through reject screens 25 and rejects 27 are discarded. Screened conditioned oil sand slurry 29 is then transferred to a pumpbox 33 where additional water 31 may be added. The slurry 35 is then pumped to slurry distribution vessel 50.
[0054] Distribution vessel 50 is designed to mix the incoming flows, slurry 48 and slurry 35, to give a homogeneous slurry for further distribution. In one embodiment, slurry distribution vessel 50 is a passive vessel, meaning that no impellers are used. Hence, at this point, trains 10 and 20 are unified and a homogeneous slurry is formed so that bitumen separation can take place at a common bitumen separation plant to produce a more consistent quality of bitumen froth.
[0055] In one embodiment, the bitumen separation plant comprises at least one primary separation vessel, or PSV. A PSV is generally a large, conical-bottomed, cylindrical vessel. In the embodiment shown in
[0056] Some or all of tailings stream 56 and middlings 58, 58 are withdrawn, combined and sent to a secondary flotation process carried out in a deep cone vessel 61 wherein air is sparged into the vessel to assist with flotation of remaining bitumen. This vessel is commonly referred to as a tailings oil recovery vessel, or TOR vessel. The lean bitumen froth 64 recovered from the TOR vessel 61 is stored in a lean froth tank 66 and the lean bitumen froth 64 may be recycled to the PSV feed. The TOR middlings 68 may be recycled to the TOR vessel 61 through at least one aeration down pipe 70. TOR underflow 72 is deposited into tailings distributor 62, together with tailings streams 56, 56 from PSVs 54 and 54, respectively. It is understood, however, that other bitumen separation processes can be used in the present invention to unify separate mining sites. It is also understood that a bitumen separation process can be comprised of multiple pieces of equipment, for example, multiple primary separation vessels, and multiple tailings oil recovery vessels.
[0057] PSV 54 bitumen froth 60 is then deaerated in steam deaerator 74 where steam 76 is added to remove air present in the bitumen froth. Similarly, PSV 54 bitumen froth 60 is deaerated in steam deaerator 74 where steam 76 is added. Deaerated bitumen froth 78 from steam deaerator 74 is added to steam deaerator 74 and a final deaerated bitumen froth product 80 is stored in at least one froth storage tank 82 for further treatment. A typical deaerated bitumen froth comprises about 60 wt % bitumen, 30 wt % water and 10 wt % solids.
[0058] Currently, two different types of froth treatment processes are commercially employed; naphthenic froth treatment, which uses a naphtha diluent typically obtained from the downstream coking of bitumen, and paraffinic froth treatment, which uses a paraffinic diluent composed of a mixture of hexanes and pentanes. Froth treatment involves the removal of water and solids still present in the deaerated bitumen froth to produce a bitumen product for upgrading.
[0059] A naphthenic froth treatment process useful in the present invention is shown in
[0060] Overflow 83 is then filtered in a filter 93 such as a Cuno filter to remove oversize debris still present in the diluted bitumen 83. Filtered diluted bitumen 85 is further treated in a disc centrifuge 95 which separates the diluted bitumen from the residual water (and fine clays) still present. A disc machine separates the hydrocarbon from the water in a rotating bowl operating with continuous discharge at a very high rotational speed. Sufficient centrifugal force is generated to separate small water droplets, of particle sizes as small as 2 m to 5 m, from the diluted bitumen.
[0061] The final diluted bitumen product 87 typically comprises between about 0.5 to 0.8 wt. % solids and 2.0-5.0 wt. % water and bitumen recovery is about 98.5%.
[0062] Deaerated bitumen froth stream 86 from froth tank 82 is also treated with naphtha at a diluent/bitumen ratio (wt./wt.) of about 0.4-1.0, preferably, around 0.7. The underflow 96 from IPS 92 can be added to stream 86 in order to recover any residual bitumen present in this underflow stream. The diluted bitumen froth is then treated in a decanter (scroll) centrifuge 94 to remove coarse solids from naphtha diluted froth. Decanter centrifuges are horizontal machines characterized by a rotating bowl and an internal scroll that operates at a small differential speed relative to the bowl. Naphtha-diluted froth containing solids is introduced into the centre of the machine through a feed pipe. Centrifugal action forces the higher-density solids towards the periphery of the bowl and the conveyer moves the solids to discharge ports.
[0063] The solids 103 are then fed to a heavy phase tank 104. The diluted bitumen 89 is further treated with a demulsifier 90, filtered in a filter 98 and the filtered diluted bitumen 100 is further treated in a disc centrifuge 99. The resultant diluted bitumen 101 is then treated, along with filtered diluted bitumen stream 85, in disc centrifuge 95 which separates the diluted bitumen from the residual water (and fine clays) still present to give final diluted bitumen stream 87. The solids 102 are also fed to heavy phase tank 104. The solids 105 are then treated in a naphtha recovery unit 106 where naphtha 107 is separated from the froth treatment tailings 108.
[0064] Thus, despite slurry preparation and conditioning occurring at two different mine sites using different slurry preparation and conditioning processes, the blending of the conditioned oil sand slurries in the slurry distributors (superpots) gives operational flexibility and improved bitumen extraction and separation through slurry blending. Having different slurry preparation and conditioning processes operating at different temperatures allows the operator to utilize the resource more efficiently, by maximizing use of the heat available at each mine site.
[0065] Further, the combination of bitumen extraction and froth treatment allows the operator to process oil sands in multiple mines in multiple locations. The pooling of bitumen froths in froth storage tanks maintains production capacity of the froth treatment facilities to produce diluted bitumen product. It also ensures that the downstream bitumen processing capacity is fully utilized.
[0066] In some instances, particularly where mine sites are very remote, it is more economical to transport bitumen froth rather than conditioned oil sand slurry, as is the case above. In particular, froth transportation using natural froth lubricity enables slurry preparation and conditioning and bitumen separation to occur remotely and the bitumen froth to be transported to a bitumen froth treatment plant at a different location, which increases production and maximizes the use of processing equipment. This aspect of the present invention will be discussed in more detail following.
[0067] In some embodiments, a third bitumen extraction process, for example, a low energy process, can be operating at yet another mine site. The low energy process can be tied into the process shown in
[0068] Screened rejects 344 are fed to an impact crusher 346 and screened again through screen 348. Oversize rejects 358 are discarded but screened material enters pump box 350, where more water is added and then oil sand slurry is pumped into pump box 352. The oil sand slurry in pump box 352 is then pumped via pumps 360 through a hydrotransport pipeline 362 for conditioning to produce conditioned oil sand slurry.
[0069] If the mine site is very remote, i.e., it is too far away from an existing bitumen separation plant to make it economical to transport the conditioned oil sand slurry to the existing plant, a bitumen separation plant is also provided at or near the remote mine site. Conditioned oil sand slurry is transferred to slurry distributor 369 (superpot) and then pumped via pump 364 through a second section 366 of pipeline where cold flood water is added. Diluted slurry is then introduced into primary separation vessel (PSV) 368 and retained under quiescent conditions, to allow the solids to settle and the bitumen froth to float to the top. A froth underwash of hot water is added directly beneath the layer of bitumen froth to aid in heating the froth and improving froth quality.
[0070] Thus, a bitumen froth layer, a middlings layer and a solids layer are formed in the primary separation vessel 368. Middlings from primary separation vessel 368 are removed and undergo flotation in flotation cells 370 to produce secondary froth. Secondary froth is recycled back to the primary separation vessel 368. Tailings, comprising the solids, water, etc. that collects at the bottom of the primary separation vessel 368 are removed and deposited into tailings pond 376 or sent to a composite tailings plant.
[0071] Bitumen froth, or primary froth, is removed from the top of the primary separation vessel 368 and then deaerated in froth deaerator 372. Once deaerated, the primary froth can be retained in froth tank 374. The deaerated bitumen froth stored in froth tank 374 can then be pumped using froth booster pumps via froth pipeline 378. Because the deaerated bitumen froth contains about 20 to 40% by volume water and the water contains colloidal-size particles such as clay, deaerated bitumen froth can be transported for long distances through froth pipeline 378 by establishing self-lubricated core-annular flow. Water can be added to promote the transport of froth in the pipeline if insufficient water is present in the deaerated froth. Core-annular flow is described in more detail in U.S. Pat. No. 5,988,198.
[0072] In one embodiment, a portion of the deaerated bitumen froth in froth tank 374, referred to in
[0073] In addition, or, in the alternative, a portion of deaerated bitumen froth, referred to in
[0074] Thus, in this embodiment, three different bitumen extraction processes have been linked together to form a single, uniform froth product for further treatment and upgrading.
[0075] In the low energy process, the temperature of the hot slurry water used in the slurry mixing step is generally about 75 C. to about 85 C., which, when mixed with the oil sand, results in an oil sand slurry having a temperature greater than 40 C., preferably greater than 43 C., and more preferably in the range of about 40 C. to about 55 C., and a density in the range of about 1.5 g/cc to about 1.6 g/cc. Caustic soda (NaOH) and other processing aids can be also added at this step, if necessary or desired.
[0076] The conditioning step can be performed either by pumping the oil sand slurry through a pipeline of sufficient length (e.g., typically greater than about 2.5 km) so that liberation of bitumen from sand and subsequent conditioning and aeration of bitumen both require sufficient time to occur. Preferably, conditioning time is about 10 minutes or more when using a pipeline of sufficient length.
[0077] The cold flood water temperature used in the flooding step generally ranges between 5 C. and 25 C., which results in a flooded or diluted slurry having a temperature of about 25 C. to about 40 C. and a density of about 1.4 g/cc to about 1.5 g/cc. More preferably, the diluted slurry will have a density of about 1.4 g/cc to about 1.45 g/cc and a temperature in the range of about 30 C. to about 40 C., preferably, a temperature of about 35 C. Use of cold flood water for flooding eliminates the need to heat water or import heated water from other sources, and readily available, lower quality pond water can be used.
[0078] In one embodiment, at least two trains of low energy process may be operating at a single mine site to maximize separation (extraction) equipment usage.
[0079] The bitumen froths produced from primary separation vessel 368 and primary separation vessel 368 are deaerated by steam, pooled and pumped through froth pipeline 378. A portion of the deaerated bitumen froth, 380, can be optionally heated using heater 400, and then stored in froth storage tank 82. Another portion of the deaerated bitumen froth, 382, can be added to hot water process 20 as described above.
[0080]
[0081]
[0082] Slurry distributor 500, shown in
[0083] Optionally, each inlet pipe may terminate with a miter (not shown). Outer inlet pipes 502 and 506 are angled toward the central inlet pipe 504. Three conditioned oil sand slurries, which may come from three separate hydrotransport feed lines (not shown), will each be fed into one of the inlet pipes. Located at or near the closed bottom 520 of slurry distributor 500 are two outlet pipes 512 and 514, which outlets may be substantially perpendicular to central inlet pipe 504. Outlet pipes 512 and 514 distribute mixed conditioned slurry to two bitumen separation vessels, for example, two primary separation vessels (not shown), via attached outlet feed lines (not shown).
[0084] Slurry distributor 500 may be installed at ground level and the outlet streams of conditioned slurry may be pumped to the primary separation vessels' feedwells. The configuration of the inlet pipes 502, 504, 506 allows for more thorough mixing of the three conditioned slurry feed streams and having the inlet array rotated 90 degrees from the two outlets also increases mixing of the three conditioned slurries. Thus, a substantially homogeneous conditioned slurry product is formed, which contributes to a more consistent bitumen froth formation in the two primary separation vessels. It is understood, however, that not all incoming feed lines, which are attached to the inlet pipes, need to be operating at all times. Slurry distributor 500 allows the operator the flexibility to operate/switch incoming feed lines and outlet feed lines to the primary separation vessels.
[0085]
[0086] In this embodiment, there are six inlet pipes 601, 602, 603, 604, 605 and 606, located near the top 618 of the slurry distributor 600 extending substantially perpendicularly from the cylindrical upper portion 610. Slurry distributor 600 is also a closed top vessel with a vent to prevent excessive moisture venting inside the building and heating the building up, as well as contributing to corrosion. There are also six outlet pipes 612, 613, 614, 621, 622 and 623 located near the closed bottom 620 of the slurry distributor 600 extending substantially perpendicularly from the cylindrical bottom section 616.
[0087] Slurry distributor 600 may be installed above six primary separation vessels and the mixed conditioned oil sand slurry flows by gravity through outlet feed lines (not shown) which are connected to each outlet pipe of the slurry distributor 600 and feedwells of corresponding primary separation vessels. The flow to the primary separation vessels may be controlled by means of valves. The cylindrical baffle 624, which is located inside the slurry distributor 600, reduces violent mixing and short circuiting of incoming flows at low operating levels, which would result in an adverse flow distribution between the discharge ports. Thus, the presence of the skirt baffle significantly reduces the turbulent eddy scale as well as the intensity in the distributor body, but especially in the annular space and at the discharge ports.