Patent Application
20080000810
The present invention relates generally to a system and process for concentrating hydrocarbons in a bitumen feed comprising bitumen, water and solids.
Oil sands deposits are found in over seventy countries throughout the world. However, a substantial portion of these deposits are located in the Alberta oil sands. In fact, Alberta's oil sands deposits contain the largest known reserve of oil in the world. The vast quantities of oil in these deposits creates a tremendous incentive to develop and improve upon techniques and systems for recovering them.
Oil sands are a geological formation, which are also known as tar sands or bituminous sands. Oil sands deposits are primarily composed of solids (generally mineral components such as clay, silt and sand) plus bitumen and water. The bitumen content typically constitutes up to about 21 wt. % of the bitumen-bearing formation material, with the remainder of the formation material composed of about 70 to 85 wt. % solids and about 4 to 10 wt. % water. The solids content typically includes clay and silt ranging from about 5 to 50 wt. %. Technically speaking, the bitumen is neither oil nor tar, but a semisolid form of oil which will not flow toward producing wells under normal conditions, making it difficult and expensive to produce.
Oil sand deposits are mined using strip mining techniques or persuaded to flow into producing wells by techniques such as steam assisted gravity drainage (SAGD) or cyclic steam stimulation (CSS) which reduce the bitumen's viscosity with steam, solvents or a combination of steam and solvents.
In order to produce an appropriate quality of bitumen-based product for use by a refinery, the hydrocarbons in the bitumen-bearing formation material removed from oil sands deposits need to be concentrated. Concentrating the hydrocarbon content of a bitumen-bearing material (also known as bitumen recovery) is typically carried out through primary and secondary treatment processes that are well known in the art.
In conventional primary treatment facilities, the bitumen-bearing formation material is processed to produce a bitumen-enriched froth stream, which typically has a bitumen content of about 50 to 60 wt. %, a solids content of about 10 to 15 wt. % and a water content of about 30 to 40 wt. %. The bitumen-enriched froth stream that is produced through primary treatment is typically transported to a secondary treatment facility to increase its hydrocarbon concentration further in order to make it suitable for processing by an upgrader or specialized refinery facility. In order to make use of the bitumen-enriched froth stream in an upgrader or refinery, secondary treatment facilities process the stream in order to produce a hydrocarbon-rich product having a hydrocarbon concentration typically in the range of at least about 90% to 97% wt. % or more. Various techniques may be used to enhance the hydrocarbon concentration of the bitumen-enriched froth stream produced by primary treatment processes, examples of which can be found in Canadian Patent Nos. 873,854, 882,667 and 2,400,258.
Although various treatment processes exist to produce a bitumen-enriched product suitable for use by an upgrader or refinery, there continues to be a need for further treatment processes and systems that offer enhancements or alternatives to the manner in which a bitumen-enriched froth stream from primary treatment is processed.
In one aspect of the present invention there is provided a process for concentrating hydrocarbons in a bitumen feed comprising bitumen, water and solids. With this process the bitumen feed is separated, in an inclined plate separator, into a first overflow stream and a first underflow stream, with the first overflow stream having a first bitumen concentration greater than that of the first underflow stream. The first underflow stream is processed by a first cyclone, which separates the first underflow stream into a second overflow stream and a second underflow stream. The second overflow stream is processed by a first centrifuge, which separates the second overflow stream into a third overflow stream and a third underflow stream. With this process, the third overflow stream has a third bitumen concentration that is greater than that of the third underflow stream. In addition, the first overflow stream and the third overflow stream each are suitable for use by an upgrader.
In another aspect of the present invention, there is provided a system for concentrating hydrocarbons in a bitumen feed comprising bitumen, water and solids. The system comprises means for separating, in an inclined plate separator, the bitumen feed into a first overflow stream and a first underflow stream, the first overflow stream having a first bitumen concentration greater than that of the first underflow stream. The system also comprises means for separating, in a first cyclone, the first underflow stream into a second overflow stream and a second underflow stream, the second overflow stream having a second bitumen concentration greater than that of the second underflow stream. In addition, the system comprises means for separating, in a first centrifuge, the second overflow stream into a third overflow stream and a third underflow stream, the third overflow stream having a third bitumen concentration that is greater than that of the third underflow stream.
In yet another aspect of the present invention, there is provided a system for concentrating hydrocarbons in a bitumen feed comprising bitumen, water and solids, the system comprising an inclined plate separator, a cyclone and a centrifuge. With this aspect, the inclined plate separator separates the bitumen feed into a first overflow stream and a first underflow stream, the first overflow stream having a first bitumen concentration greater than that of the first underflow stream. The first cyclone separates the first underflow stream into a second overflow stream and a second underflow stream. The first centrifuge separates the second overflow stream into a third overflow stream and a third underflow stream, wherein the first overflow stream and the third overflow stream each comprise about or less than about 1.0 wt. % solids.
In the accompanying drawings which illustrate embodiments of the invention,
Reference will now be made in detail to implementations and embodiments of various aspects and variations to the present invention, examples of which are illustrated in the accompanying drawings.
Referring to
As illustrated in
The bitumen feed stream 70 will typically have a varying degree of constituent components (bitumen, water and solids) due to, for instance, variations in the oil sands composition processed upstream of the system 10. Typically, the bitumen feed stream 70 comprises from about 45 to 65 wt. % bitumen, from about 8 to 15 wt. % solids and from about 25 to 50 wt. % water.
In the first embodiment, a solvent 14 comprising a liquid hydrocarbon is added to the bitumen feed stream 70 to reduce its hydrocarbon density and its viscosity. Preferably, the addition of the solvent 14 also helps solvate the hydrocarbons from solids in the bitumen feed stream 70 and from organic films surrounding water droplets in the bitumen feed stream 70. The solvent 14 may be any solvent capable of diluting the bitumen feed stream 70 so as to reduce the hydrocarbon density and the viscosity of the bitumen feed stream 70. In the first embodiment, the solvent 14 may comprise naphtha.
Alternatively, other solvents may be used including, for example, paraffinic or alkane hydrocarbon solvents. In this specification, the solvent 14 is also referred to as a diluent. The solvent 14 is preferably miscible with the hydrocarbon components of the bitumen feed stream 70, and preferably can be readily recovered from the hydrocarbon components of the bitumen feed stream 70.
The solvent 14 can be added at one or more addition points within or in advance of the system 10. In the first embodiment, the solvent 14 is added in advance of introducing the bitumen feed stream 70 to the inclined plate separator 20 in separation stage I. In the alternative, the solvent 14 may be added to or mixed with one or more other streams of the system 10 in addition to or instead of the bitumen feed stream 70. In this specification the term “hydrocarbons” refers to the hydrocarbons found in the bitumen, the solvent 14 (diluent) or both.
The diluted bitumen feed stream 70 is fed through line 11 to the inclined plate separator 20. The inclined plate separator 20 is a conventional inclined plate separator which processes an incoming bitumen feed stream so as to produce a bitumen-enriched product stream comprising a bitumen concentration suitable for processing by an upgrader 24, and a residual bitumen-lean stream (also referred to as a reject stream) comprising a concentration of bitumen lower than that in the product stream. Inclined plate separators are well known in the art. For illustration purposes only, inclined plate separators that may be used in system 10 include inclined plate separators available from Krebs Engineers (www.krebs.com) or from Parkson Industrial Equipment Company of Florida, U.S.A.
As illustrated in
The first overflow stream 74 typically comprises from about 55 wt. % to about 65 wt. % bitumen; from about 30 wt. % to about 40 wt. % diluent; from about 0.5 wt. % to about 2.0 wt. % solids; and from about 1.0 wt. % to about 6.0 wt. % water. Preferably, the first overflow stream 74 in
The first overflow stream 74 is fed to line 13, and may be sent directly to the upgrader 24. Alternatively, the first overflow stream 74 may be directed to a storage unit. In another aspect, the first overflow stream 74 may be further processed before being supplied to the upgrader 24.
Although the first underflow stream 76 comprises a hydrocarbon concentration which is significantly lower than that of the first overflow stream 74, the first underflow stream 76 typically will still contain bitumen that will be desirable to recover for processing by the upgrader 24. Therefore, the first underflow stream 76 is fed through line 15 to separation stage II for further treatment within the system 10.
As shown in
The first hydrocyclone 30 separates the first underflow stream 76 into a second overflow stream 78 and a second underflow stream 80. The second overflow stream 78 has a significantly higher hydrocarbon concentration (bitumen and diluent) than that of the second underflow stream 80. In addition, the second overflow stream 78 will have significantly lower solids and water contents than those of the second underflow stream 80.
The second overflow stream 78 is an intermediate stream comprising a hydrocarbon concentration which is lower than the hydrocarbon concentration of the first overflow stream 74. However, the second overflow stream 78 typically will still contain hydrocarbons that are desirable to recover as part of the final product stream that may be used by an upgrader. One of the challenges with concentrating hydrocarbons from this intermediate stream (second overflow stream 78) is the desire to efficiently produce a secondary product stream that comprises concentrated hydrocarbons (bitumen and diluent) from the intermediate stream (second overflow stream 78) while maintaining a quality of the secondary product stream suitable for further processing in the upgrader 24. In this regard, having a secondary product stream, produced by the system 10 from the processing (treatment) of the second overflow stream 78, comprising less than about 4.0 wt. % solids and less than about 6.0 wt. % water has been found to be of suitable quality for use by the upgrader 24. However, having a secondary product stream comprising even lower solids and water contents is much more preferred in order to enhance hydrocarbon concentration, improve the performance of the upgrader 24, and reduce its maintenance requirements. Preferably, the product stream to be fed to the upgrader 24 (overflow stream 74 or the secondary product stream) comprises less than about 2.0 wt. % solids, more preferably comprises less than about 1.4 wt. % solids, more preferably comprises less than about 1.2 wt. % solids and more preferably yet comprises less than about 1.1 wt. % solids and even more preferably yet comprises less than 0.5 wt. % solids. Preferably, the product stream to be fed to the upgrader 24 also comprises less than about 3.0 wt. % water, more preferably comprises less than about 1.5 wt. % water, and more preferably yet comprises about or less than about 1.0 wt. % water. It has been found that keeping the water content at about 1.5 wt. % or less in the product stream (overflow stream 74 or the secondary product stream) to be fed to the upgrader 24 is particularly preferably as this contributes to a substantial decrease in the number of erosion/corrosion events seen in the upgrader 24 due to chlorides, which advantageously results in much less wear on the upgrader equipment, significantly fewer maintenance requirements, and significantly less degredation in the operation of the upgrader and fewer undesirable interruptions in operations.
The second overflow stream 78 is preferably fed via line 17 to a filtration-based separation stage III comprising one or more filters 38, such as Cunos™ filters, which are used to filter out a portion of the solids (including tramp or trash material) in the second overflow stream 78. The filtration of the second overflow stream 78 by filters 38 results in filtered stream 79, which is fed through line 17A to separation stage IV.
Separation stage IV, comprising first centrifuge 40, forms part of the system 10 in order to further improve the quality of the secondary product stream that will be produced and eventually be available for processing by the upgrader 24. In this regard, the addition of first centrifuge 40 within the system 10 provides a mechanism for further enhancing the concentration of hydrocarbons (bitumen and diluent) from the second overflow stream 78 and for reducing the quantity of contaminants (e.g. solids and water) in the secondary product stream that is produced for eventual use by the upgrader 24.
It has been found that keeping the solids content (coarse and fine solids) at about 1.0 wt. % or less in the product stream to be fed to the upgrader 24 is particularly preferably as this contributes to a substantial decrease in the number of erosion events seen in the upgrader 24, which advantageously results in much less wear on the upgrader equipment, significantly fewer maintenance requirements, and significantly less degredation in the operation of the upgrader and fewer undesirable interruptions in operations. Achieving a product stream comprising about or less than about 1.0 wt. % solids from the processing of an intermediate stream such as second overflow stream 78 can be challenging due to the high mineral content in the second overflow stream 78 resulting from the separation techniques applied by the inclined plate separator 20 and the first hydrocyclone 30. The introduction of the first centrifuge 40 to the system 10 and the processing of second overflow stream 78 by the first centrifuge 40, preferably after filtration through filters 38, advantageously assists significantly in keeping the solids content in the secondary product stream 82 at about 1.0 wt. % or less during the extended and continuing operation of the system 10. In addition, feeding the second overflow stream 78 to the first centrifuge 40 rather than to or upstream of the inclined plate separator 20 avoids placing additional circulating load on the inclined plate separator 20 and avoids raising the solids and water content of the first overflow stream 74 and the first underflow stream 76 that would result from re-introducing to the inclined plate separator 20 additional solids-rich material downstream of the inclined plate separator 20.
In
The introduction of the first centrifuge 40 at separation stage III and the feeding of at least the second overflow stream 78 to the first centrifuge 40, preferably via filters 38, advantageously provides a configuration that not only can produce a secondary product stream (third overflow stream 82) that has about 1.0 wt % solids content or less, but in which the solids content can typically be maintained over continued operation at about 0.4 wt. % to about 0.8 wt. %. In addition, the third overflow stream 82 will have a significantly higher hydrocarbon concentration (bitumen and diluent) than that of the third underflow stream 84, and will have significantly lower solids and water contents than those of the third underflow stream 84. The third overflow stream 82 typically comprises from about 54 wt. % to about 60 wt. % bitumen; from about 33 wt. % to about 39 wt. % diluent; from about 0.4 wt. % to about 0.8 wt. % solids; and from about 5.0 wt. % to about 12.0 wt. % water. In addition, the third overflow stream 82 typically has a D/B weight ratio of about 0.6 to about 0.7 and comprises a hydrocarbon content of about 88 wt. % to about 95.5 wt. %.
The third overflow stream 82 produced in the system 10 will preferably have a sufficiently high concentration of hydrocarbons (bitumen and diluent) and a sufficiently low concentration of contaminants (e.g. solids and water) such that the third overflow stream 82 is of a quality suitable to be used by the upgrader 24. In the first embodiment, the third overflow stream 82 is fed through line 21 and combined with the first overflow stream 74 in line 13 to produce a combined product stream 100 for use by the upgrader 24.
In the first embodiment, the second underflow stream 80 and the third underflow stream 84 are reject streams, which may be combined and fed to a solvent recovery unit 36 in order to recover the residual solvent 14 (diluent) for reuse within the system 10 before the combined reject stream (80 and 84) is sent to a tailings pond (not shown).
In one aspect of the present invention, the staged system 10 shown in
Although not shown in
In addition to the various aspects and features discussed above, the system 10 and the process applied thereto can have a variety of aspects and features to further enhance operations. Furthermore, as with the aspects and features described above, each of the following aspects and features individually provides a beneficial enhancement and is an embodiment of the present invention. These additional aspects and features will now be described below.
Referring to
The fourth overflow stream 86 is fed through line 25, and is combined (blended) with the second overflow stream 78 in line 17 to form a combined stream, which preferably is fed to filters 38 to filter out a portion of the solids in the combined stream. The filtration of the combined stream formed by second overflow stream 78 and fourth overflow stream 86 by filters 38 results in filtered stream 79A, which is fed through line 17A to the first centrifuge 40 for processing as described in connection with the first embodiment shown in
Referring to
The grinder 9 grinds pieces of roots, branches, coal and other organic materials to a size small enough not to plug pumps or separation units within the system 10B, preferably down to about ¼ inch in diameter or less. By grinding down pieces of material in the deaerated bitumen froth that could obstruct parts of the system 10B, the deaerated bitumen froth can be fed to the separation units while avoiding bitumen recovery losses that would arise from the pre-treatment removal of such obstructions. The bitumen feed 70 (deaerated bitumen froth) is then fed through line 11 for further processing in the manner described in the above embodiments (systems 10 and 10A). Alternatively, grinder 9 may be situated to process diluted bitumen streams. For instance, the grinder 9 may be situated to process bitumen feed stream 70 after solvent 14 is added or to process first underflow stream 76.
As shown in
In the embodiment shown in
The overflow stream 82B will have a higher hydrocarbon concentration (bitumen and diluent) than that of the underflow stream 84B, and will have a significantly higher bitumen concentration than that of the underflow stream 84B. The overflow stream 82B will also have significantly lower solids and water contents than those of the underflow stream 84B. As compared to the first embodiment in
It will be noted that the intermediate three-stage counter-current circuit shown in
Referring to
In the embodiment shown in
Advantageously, in the system 10C, the introduction of the chemical additive 16 further enhances the quality of the product streams produced. In this regard, the first overflow stream 74 in
In another aspect of the present invention, the chemical additive 16 may be additionally or alternatively introduced at other addition points within the applicable system (e.g. system 10C). For example, in variations of the embodiment shown in
In system 10C, the third overflow stream 82C will preferably be of a quality suitable to be combined with the first overflow stream 74 to form a product stream 102C for use in the upgrader 24. Alternatively, the product stream 102C may be introduced into a further separation stage comprising a storage tank. The fourth underflow stream 88 and the third underflow stream 84C may be combined in line 23A and fed to the solvent recovery unit 36 to recover the solvent 14.
Referring to
The hydrocarbon-based components (residual bitumen and diluent) that are present in the aqueous phase which settles in the settling tank 23 form a slops-type mixture comprising bitumen, diluent (solvent), fine solids and water, which can be routed to solvent recovery unit 36 to recovery a portion of the diluent before the remaining mixture is directed to a tailings pond. However, this approach results in a significant loss of diluent and bitumen. Preferably, at least a portion of the diluent and bitumen would be recovered from the slops-type mixture that is collected, such as in the settling tank 23.
In general, the slops-type mixture may be produced from the processing of a stream within the applicable system (e.g. system 10D) downstream of the centrifuge 40 or one of the hydrocyclones (30, 32). As illustrated in
The overflow stream 82D that is produced in system 10D preferably contains a sufficiently high hydrocarbon concentration and sufficiently low water and solids contents such that it is of a quality suitable for combining with the first overflow stream 74 to form a product stream 102D. As with the earlier embodiments described above, the underflow stream 84D is a reject stream, which is fed to the solvent recovery unit 36 to recover residual solvent 14 for reuse.
Referring to
The first underflow stream 76 is processed by the hydrocyclone 30 as described in the previous embodiments (e.g. as in system 10A), producing the second overflow stream 78 and the second underflow stream 80. The second underflow stream 80 is fed through line 19 to the second hydrocyclone 32, where it is separated into the fourth overflow stream 86 and the fourth underflow stream 88.
In this embodiment, the fourth overflow stream 86 serves as an intermediate feed stream that is preferably fed through line 25 into filters 38. Filters 38 process the fourth overflow stream 86 to filter out a portion of the solids, resulting in a filtered stream 79E, which is fed through line 21 for processing by the first centrifuge 40 as was described in connection with the first embodiment shown in
In system 10E, the overflow stream 82E obtained from the first centrifuge 40 is fed through line 21 to a storage tank 22A. The storage tank 22A is separate from the storage tank 22. The underflow stream 84E is a reject stream, which is fed through line 23A to the solvent recovery unit 36 to recover the residual solvent 14 for reuse. In the system 10E, the two storage tanks 22 and 22A serve as separate initial settling facilities for the first overflow stream 74 and the overflow stream 82E respectively.
The first overflow stream 74 and the overflow stream 82E which accumulate in the storage tanks 22 and 22A respectively will typically each separate into a hydrocarbon-rich layer and a residual layer, with the hydrocarbon-rich layer having a hydrocarbon concentration significantly higher than that of the residual layer. The preferred hydrocarbon-rich layers which typically collect at about or near the top of the storage tanks 22 and 22A may be fed to the upgrader 24 for processing.
Residual layers which collect at about or near the bottom of the storage tanks 22 and 22A are preferably fed as residual streams a further separation stage comprising the settling tank 23. The residual streams entering the settling tank 23 still contain residual hydrocarbons that are desirable to concentrate. The residual streams further separate in the settling tank 23 into a hydrocarbon-rich layer near the top of the tank and an aqueous layer near the bottom of the tank, which will still comprise some residual hydrocarbons. The hydrocarbon-rich layer can be fed from the settling tank 23 to the upgrader 24. Alternatively, the hydrocarbon-rich layer in the settling tank 23 may be fed back into the storage tank 22 to enhance the separation in the settling tank 22. The aqueous layer in the settling tank 23 comprising residual hydrocarbons may be pumped as stream 96 through line 41. In system 10E, the stream 96 is fed to line 11 where it is combined with the diluted bitumen feed stream 70 and with the second overflow stream 78 for re-processing by the system 10E, beginning with the inclined plate separator 20.
Optionally, the stream 96 may also be fed through line 45 so as to be combined with the fourth overflow stream 86 prior to being further processed by filters 38 and the first centrifuge 40. In another variation, the stream 96 may be combined with the first underflow stream 76 prior to being further processed by the first hydrocyclone in separation stage II. The system 10E also may include the addition of a chemical additive in the manner described for system 10C (
Referring to
In this embodiment, the second overflow stream 78 obtained from the first hydrocyclone 30 in separation stage II is fed through line 17 preferably into filters 38, resulting in a filtered stream 79F, which is fed through line 17A to the first centrifuge 40 for processing as described in connection with the first embodiment shown in
Referring to
Optionally, the second overflow stream 78 and the fourth overflow stream 86 may be combined with a portion of the bitumen feed 70, which is fed through line 11A. The addition of a portion of the bitumen feed stream 70 to overflow stream 78 can assist in further improving the concentration of hydrocarbons in the overflow stream 82G.
The overflow stream 82G is fed through line 21 into filters 38 which process the overflow stream 82G to remove a portion of the solids, resulting in a filtered stream 90. Filtered stream 90 is fed through line 21 for processing by centrifuge 40 as was described in connection with the first embodiment shown in
As discussed earlier with reference to the first embodiment shown in
Referring to
Although separation stages I through VI are shown for illustration purposes in
Although specific embodiments of the invention have been described and illustrated, such embodiments should not to be construed in a limiting sense. Various modifications of form, arrangement of components, steps, details and order of operations of the embodiments illustrated, as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover such modifications and embodiments as fall within the true scope of the invention. In the specification including the claims, numeric ranges are inclusive of the numbers defining the range. Citation of references herein shall not be construed as an admission that such references are prior art to the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2400258 | Aug 2002 | CA | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10306003 | Nov 2002 | US |
| Child | 11486302 | Jul 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11486302 | Jul 2006 | US |
| Child | 11759151 | Jun 2007 | US |
