CA2864021C - Separating a bitumen extract from solids - Google Patents

Abstract

A system and process for separating a bitumen extract from solids. The system may include a separator unit configured to receive an oil sands slurry and separate the solids in the oil sands slurry from the bitumen extract in the oil sands slurry to produce a bitumen extract stream and a solids stream; an accumulator configured to receive the solids stream and configured to remove additional bitumen extract from the solids stream to produce a concentrated solids stream; and a fluidizing unit configured to discharge the concentrated solids stream by mixing the concentrated solids stream with a washing fluid to form a low bitumen oil sands slurry.

Description

SEPARATING A BITUMEN EXTRACT FROM SOLIDS
BACKGROUND
Field of Disclosure [0001] The disclosure relates generally to oil sands processing. More specifically, the present disclosure relates to a system and process for separating a bitumen extract from solids.
Description of Related Art

[0002] This section is intended to introduce various aspects of the art, which may be associated with the present disclosure. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present disclosure.
Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of prior art

[0003] Modern society is greatly dependent on the use of hydrocarbon resources for fuels and chemical feedstocks. Hydrocarbons are generally found in subsurface formations that can be termed "reservoirs." Removing hydrocarbons from the reservoirs depends on numerous physical properties of the subsurface formations, such as the permeability of the rock containing the hydrocarbons, the ability of the hydrocarbons to flow through the subsurface formations, and the proportion of hydrocarbons present, among other things.
Easily harvested sources of hydrocarbons are dwindling, leaving less accessible sources to satisfy future energy needs. As the costs of hydrocarbons increase, the less accessible sources become more economically attractive. Recently, the harvesting of oil sands to remove heavy oil has become more economical.

[0004] Hydrocarbon removal from oil sands may be performed by several techniques.
The techniques may be referred to as oil sands extraction processes. For example, a well can be drilled to an oil sand reservoir and steam, hot air, solvents, or a combination thereof, can be injected to release the hydrocarbons. The released hydrocarbons may be collected by wells and brought to the surface. In another technique, strip or surface mining may be performed to access the oil sands, which can be treated with hot water, steam or solvents to extract the heavy oil. This other technique may be referred to as a water-based extraction process ===
(WBE). The WBE is a commonly used process to extract bitumen from mined oil sands. In another technique, a non-water-based extraction process can be used to treat the strip or surface mined oil sands. The non-water-based extraction process may interchangeably be referred to as a solvent based extraction process or an oil sands solvent extraction process.
The commercial application of a solvent based extraction process has, for various reasons, eluded the oil sands industry. A major challenge associated with the solvent based extraction process is the tendency of fine particles within the oil sands to hamper the separation of solids from the heavy oil extracted. The heavy oil extracted may interchangeably be referred to as bitumen extract. Fine particles may interchangeably be referred to as a fine solids stream or fines.

[0005] One proposed way to handle the challenge of fine particles is described in Canadian Patent No. 1,169,002 (Karnofsky). Karnofsky describes a process wherein an oil sands slurry is separated into a coarse solids stream and a fine solids stream by gravity separation. Bitumen extract is removed from the coarse solids stream by using a series of percolating beds. Bitumen extract is removed from the fines solids stream by using a complicated system of clarifiers, thickeners, and filters. Despite the process described in Karnofsky, solid-liquid separation of the fines solids stream remains a challenge.
100061 Another proposed way to handle the challenge of fine particles is described in U.S.
Patent No. 8,226,820 (Wegner). Wegner describes the use of a rinse chamber to separate the bitumen extract from solids. An oil sand slurry enters the rinse chamber through a tangential cyclone port located at the top of the rinse chamber. Since the oil sand slurry is pumped into the rinse chamber, centrifugal forces result in the solids separating from the bitumen extract.
By gravity, the solids move to the bottom of the rinse chamber. Additional oil free solvent is pumped to the bottom of the rinse chamber so that as the solids progress downward through the rinse chamber, the solvent progresses up the rinse chamber in a counter current fashion.
Despite the process described in Wegner, the bitumen extract requires additional solid-liquid separation to remove fines prior to being directed to a solvent recovery unit;
the counter-current washing of the solids within the rinse chamber is prone to back-mixing, which reduces wash efficiency.

[0007]
Another proposed way to handle the challenge of fine particles is by using a solid agglomeration process. The solid agglomeration process was coined Solvent Extraction Spherical Agglomeration (SESA). A description of the SESA process can be found in Sparks et al., "The Effect of Asphaltene Content on Solvent Selection for Bitumen Extraction by the SESA Process" Fuel 1992(71); pp 1349-1353. Previously described methodologies for SESA
have not been commercially adopted. In general, the SESA process involves mixing oil sands with a hydrocarbon solvent to form an oil sands slurry, adding a aqueous bridging liquid to the oil sands slurry to form a mixture, agitating the mixture in a slow and controlled manner to nucleate particles, and continuing such agitation so as to permit these nucleated particles to form larger multi-particle spherical agglomerates for removal. The aqueous bridging liquid may be water or an aqueous solution since the solids of oil sands are mostly hydrophilic and water is immiscible to hydrocarbon solvents. The aqueous bridging liquid preferentially wets the solids. With the right amount of the aqueous bridging liquid and suitable agitation of the slurry, the aqueous bridging liquid displaces the suspension liquid on the surface of the solids.
As a result of interfacial forces among three phases (i.e. the aqueous bridging liquid, the suspension liquid, and the solids), fine particles within the solids consolidate into larger, compact agglomerates that are more readily separated from the suspension liquid.
[00081 U.S. Patent No. 4,719,008 (Sparks) describes a process that applies SESA using a micro-agglomerate procedure. In Sparks, the SESA process occurs within a slowly rotating horizontal vessel. The conditions of the slowly rotating horizontal vessel are that which favor the formation of large agglomerates; however, a light milling action is used to continuously break down the agglomerates. The micro-agglomerates are formed by obtaining an eventual equilibrium between cohesive and destructive forces.
Since rapid agglomeration and agglomerates of large size can lead to bitumen recovery losses owing to entrapment of bitumen extract within the agglomerated solids, the level of bridging liquid is kept to as low as possible commensurate with achieving economically viable solid-liquid separations.
[0009]
With the formation of micro-agglomerates, the process of solid-liquid separation using common separation devices is easier compared to a situation where fine particles are not micro-agglomerated. Applicable separation devices include at least one of gravity separators, centrifuges, cyclonic separation devices, screens and filters. Although the separation devices have been shown to be effective in separating agglomerates from liquids, they have disadvantages that may limit their application in an oil sands solvent extraction process. For example, gravity separators, such as clarifiers and incline plate separators, can result in a bitumen extract of low solids content; the underflow from the gravity separators is expected to have a substantial amount of bitumen extract entrained within the underflow.
Because of this bitumen entrainment in the underflow, a significant amount of wash solvent and many wash stages is needed to separate the substantial amount of bitumen extract ¨
interchangeably referred to as residual bitumen -- from the solids. Cyclonic separation devices, such as hydrocyclones, are compact and allow for rapid separation of solids from liquids. However, it is difficult to use cyclonic separation devices to clarify the bitumen extract and concentrate the solids stream to, say, greater than 50 wt.% solids. In solid-liquid separation processes, paste thickeners, centrifuges or filters are known to produce solid slurries of greater than 50 wt. %.
The paste thickeners, centrifuges or filters have moving parts that may challenge their reliability in the high solids content and hydrocarbon environment of the solvent extraction process.
[0010] A need exists for improved technology, including technology that may address one or more of the described disadvantages. For example, a need exists for a system and process of separating bitumen extract from solids that address one or more of the aforementioned disadvantages.
SUMMARY
[0011] It is an object of the present disclosure to provide a system and a process for separating bitumen extracts from solids.
[0012] A system for separating a bitumen extract from solids may comprise (a) a separator unit configured to receive an oil sands slurry and to separate the solids in the oil sands slurry from the bitumen extract in the oil sands slurry to produce a bitumen extract stream and a solids stream; (b) an accumulator configured to receive the solids stream and configured to remove additional bitumen extract from the solids stream to produce a concentrated solids stream; and (c) a fluidizing unit configured to discharge the concentrated solids stream by mixing the concentrated solids stream with a washing fluid to form a low bitumen oil sands slurry.

[0013] A process for separating a bitumen extract from solids within an oil sands solvent extraction process may comprise (a) receiving an oil sands slurry, wherein the oil sands slurry comprises the bitumen extract and the solids; (b) producing a bitumen extract stream including the bitumen extract and a solids stream including the solids by separating the solids from the bitumen extract; (c) producing a concentrated solids stream by removing additional bitumen extract from the solids stream; and (d) forming a low bitumen oil sands slurry by fluidizing the concentrated solids stream by mixing the concentrated solids stream with a washing fluid.
[0014] The foregoing has broadly outlined the features of the present disclosure so that the detailed description that follows may be better understood. Additional features will also be described herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] These and other features, aspects and advantages of the disclosure will become apparent from the following description, appending claims and the accompanying drawings, which are briefly described below.
[0016] Figure 1 is a flow chart of a system for separating a bitumen extract from solids.
[0017] Figure 2 is a schematic of a single vessel solid-liquid separation system with hydrocyclones as the separator unit.
[0018] Figure 3 is a schematic of a single vessel solid-liquid separation system with a gravity separator as the separator unit.
[0019] Figure 4 is a schematic of a multi-stage solid-liquid separation system with wash stages.
[0020] Figure 5 is a schematic of a process for separating a bitumen extract from solids.
[0021] Figure 6 is a flow chart of a process for separating a bitumen extract from solids.
[0022] It should be noted that the figures are merely examples and no limitations on the scope of the present disclosure are intended thereby. Further, the figures are generally not drawn to scale, but are drafted for purposes of convenience and clarity in illustrating various aspects of the disclosure.

DETAILED DESCRIPTION
[0023] For the purpose of promoting an understanding of the principles of the disclosure, reference will now be made to the features illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the disclosure is thereby intended. Any alterations and further modifications, and any further applications of the principles of the disclosure as described herein are contemplated as would normally occur to one skilled in the art to which the disclosure relates.
It will be apparent to those skilled in the relevant art that some features that are not relevant to the present disclosure may not be shown in the drawings for the sake of clarity.
[0024] At the outset, for ease of reference, certain terms used in this application and their meaning as used in this context, are set forth below. To the extent a term used herein is not defined below, it should be given the broadest definition persons in the pertinent art have given that term as reflected in at least one printed publication or issued patent. Further, the present processes are not limited by the usage of the terms shown below, as all equivalents, synonyms, new developments and terms or processes that serve the same or a similar purpose are considered to be within the scope of the present disclosure.
[0025] A "hydrocarbon" is an organic compound that primarily includes the elements of hydrogen and carbon, although nitrogen, sulfur, oxygen, metals, or any number of other elements may be present in small amounts. Hydrocarbons generally refer to components found in heavy oil or in oil sands. However, the techniques described are not limited to heavy oils but may also be used with any number of other reservoirs to improve gravity drainage of liquids. Hydrocarbon compounds may be aliphatic or aromatic, and may be straight chained, branched, or partially or fully cyclic.
[0026] "Bitumen" is a naturally occurring heavy oil material. Generally, it is the hydrocarbon component found in oil sands. Bitumen can vary in composition depending upon the degree of loss of more volatile components. It can vary from a very viscous, tar-like, semi-solid material to solid forms. The hydrocarbon types found in bitumen can include aliphatics, aromatics, resins, and asphaltenes. A typical bitumen might be composed of:

6 19 weight (wt.) percent (%) aliphatics (which can range from 5 wt. % - 30 wt.
%, or higher);
19 wt. % asphaltenes (which can range from 5 wt. % - 30 wt. %, or higher);
30 wt. % aromatics (which can range from 15 wt. % - 50 wt. %, or higher);
32 wt. % resins (which can range from 15 wt. % - 50 wt. %, or higher); and some amount of sulfur (which can range in excess of 7 wt. %).
In addition bitumen can contain some water and nitrogen compounds ranging from less than 0.4 wt. % to in excess of 0.7 wt. %. The percentage of the hydrocarbon found in bitumen can vary. The term "heavy oil" includes bitumen as well as lighter materials that may be found in a sand or carbonate reservoir.
[0027] "Heavy oil" includes oils which are classified by the American Petroleum Institute ("API"), as heavy oils, extra heavy oils, or bitumens. The term "heavy oil"
includes bitumen.
Heavy oil may have a viscosity of about 1,000 centipoise (cP) or more, 10,000 cP or more, 100,000 cP or more, or 1,000,000 cP or more. In general, a heavy oil has an API gravity between 22.3 API (density of 920 kilograms per meter cubed (kg/m3) or 0.920 grams per centimeter cubed (g/cm3)) and 10.0 API (density of 1,000 kg/m3 or 1 g/cm3).
An extra heavy oil, in general, has an API gravity of less than 10.0 API (density greater than 1,000 kg/m3 or 1 g/cm3). For example, a source of heavy oil includes oil sand or bituminous sand, which is a combination of clay, sand, water and bitumen. The recovery of heavy oils is based on the viscosity decrease of fluids with increasing temperature or solvent concentration. Once the viscosity is reduced, the mobilization of fluid by steam, hot water flooding, or gravity is possible. The reduced viscosity makes the drainage quicker and therefore directly contributes to the recovery rate.
[0028] The term "bituminous feed" refers to a stream derived from oil sands that requires downstream processing in order to realize valuable bitumen products or fractions. The bituminous feed is one that comprises bitumen along with undesirable components.
Undesirable components may include but are not limited to clay, minerals, coal, debris and water. The bituminous feed may be derived directly from oil sands, and may be, for example,

7 raw oil sands ore. Further, the bituminous feed may be a feed that has already realized some initial processing but nevertheless requires further processing. Also, recycled streams that comprise bitumen in combination with other components for removal as described in the present disclosure can be included in the bituminous feed. A bituminous feed need not be derived directly from oil sands, but may arise from other processes. For example, a waste product from other oil sands solvent extraction processes, which comprises bitumen that would otherwise not have been recovered, may be used as a bituminous feed.
[0029] "Fine particles" are generally defined as those solids having a size of less than 44 microns (vim), that is, material that passes through a 325 mesh (44 micron (rim)). The aforementioned range includes any number within the range.
[0030] "Coarse particles" are generally defined as those solids having a size of greater than 44 microns (p.m). The aforementioned range includes any number within the range.
[0031] The terms "approximately," "about," "substantially," and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described and claimed without restricting the scope of these features to the precise numeral ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and are considered to be within the scope of the disclosure.
[0032] The term "solvent" as used herein should be understood to mean either a single solvent, or a combination of solvents.
[0033] The articles "the", "a" and "an" are not necessarily limited to mean only one, but rather are inclusive and open ended so as to include, optionally, multiple such elements.
[0034] "At least one," in reference to a list of one or more entities should be understood to mean at least one entity selected from any one or more of the entity in the list of entities, but not necessarily including at least one of each and every entity specifically listed within the list of entities and not excluding any combinations of entities in the list of entities. This definition also allows that entities may optionally be present other than the entities specifically identified

8 within the list of entities to which the phrase "at least one" refers, whether related or unrelated to those entities specifically identified. Thus, as a non-limiting example, "at least one of A
and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") may refer, to at least one, optionally including more than one, A, with no B present (and optionally including entities other than B); to at least one, optionally including more than one, B, with no A present (and optionally including entities other than A); to at least one, optionally including more than one, A, and at least one, optionally including more than one, B
(and optionally including other entities). In other words, the phrases "at least one," "one or more," and "and/or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions "at least one of A, B and C,"
"at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C" and "A, B, and/or C"
may mean A alone, B alone, C alone, A and B together, A and C together, B and C together, A, B and C together, and optionally any of the above in combination with at least one other entity.
[0035] Where two or more ranges are used, such as but not limited to 1 to 5 or 2 to 4, any number between or inclusive of these ranges is implied.
[0036] The disclosure relates to a system and process for separating a bitumen extract from solids. Figures 1-6 display various aspects of the system and process.
[0037] The system may be a solid-liquid separation system (100) (Figure 1).
The solid-liquid separation system (100) and process (600) may be for separating a bitumen extract (110) from solids (112). The solid-liquid separation system (100) and process may include a bituminous feed (102). The bituminous feed (102) may be mixed with an extraction liquor (104) in an extractor (106) to form an oil sands slurry (108). Complete or partial bitumen dissolution into the extraction liquor (104) occurs in the extractor (106).
The extractor (106) may comprise at least one of a slurry system (not shown), an extraction vessel (not shown), and an agglomerator vessel (not shown).
[0038] The extraction liquor (104) may comprise a solvent used to extract bitumen from the bituminous feed (102). The extraction liquor (104) may comprise a hydrocarbon solvent capable of dissolving the bitumen in the bituminous feed (102). The extraction liquor (104)

9 may be a solution of a hydrocarbon solvent(s) and bitumen, where the bitumen content of the extraction liquor (104) may range between 10 and 70 wt. %, or 10 and 50 wt. %.
The bitumen content of the extraction liquor may include any number within or bounded by the preceding ranges. Dissolved bitumen may be within the extraction liquor to increase the volume of the extraction liquor without an increase in the required inventory of hydrocarbon solvent(s). In cases where non-aromatic hydrocarbon solvents are used as the extraction liquor (104), the dissolved bitumen within the extraction liquor (104) may increase the solubility of the extraction liquor towards dissolving additional bitumen in the bituminous feed (102).
[0039] The extraction liquor (104) entering the extractor (106) may be recycled to the extractor (106) from a downstream step. For instance, as described in the present disclosure, solvent recovered in a solvent recovery unit, may be used to wash agglomerates, and the resulting stream may be used as the extraction liquor (104). As a result, the extraction liquor (104) may comprise residual bitumen and residual solid fines. The residual bitumen may increases the volume of the extraction liquor. The residual bitumen may increase the solubility of the extraction liquor for additional bitumen dissolution.
[0040] The solid-liquid separation system (100) and process (600) may include a separator unit (114). The separator unit (114) may be configured to receive the oil sand slurry (108), (602). The separator unit (114) may be in fluid communication with the extractor (106). The separator unit (114) may receive the oil sands slurry (108) after it exits the extractor (106).
[0041] The oil sand slurry (108) may be a mixture of the extraction liquor (104) and the bituminous feed (102). The oil sand slurry may include additional additives besides the extraction liquor (104) and the bituminous feed (102). The bitumen entrained within the bituminous feed (102) may be given an opportunity to become partially or fully extracted into the solvent phase of the extraction liquor (104) prior to further processing and solid-liquid separation within the system and process.
[0042] The extraction liquor (104) may be added in two distinct stages to the oil sand slurry (108). When the extraction liquor (104) is added in two distinct stages, the extraction liquor (104) may comprise a first extraction liquor and a second extraction liquor. In the first stage, the first extraction liquor may be used to dissolve bitumen within the bituminous feed (102). In the second stage, the second extraction liquor may be used to dilute bitumen extract within the oil sands slurry (108) to improve solid liquid separation within the system and process. The oil sand slurry (108) may be formed within a slurry system that may be at least one of a mix box, a pump, and a cyclonic device.
[0043] The oil sand slurry (108) may have a solid content in the range of 5 to 65 wt. %, 20 to 65 wt. %, or 40 to 65 wt. %. The solid content of the resulting oil sand slurry may be any number bounded or included within any of the aforementioned ranges. In the case of a solvent extraction with solids agglomeration process, a higher solids content oil sand slurry (for instance in an upper half of the aforementioned ranges) may be desired to increase the compaction forces that may help in the agglomeration process. A lower solids content oil sands slurry (for instance in a lower half of the aforementioned ranges) may be desired to reduce the energy needed in the oil sands solvent extraction processes for mixing the oil sands slurry. A lower solids content oil sands slurry (for instance in a lower half of the aforementioned ranges) may be desired for solid-liquid separation. The oil sands slurry may have a higher solids content slurry (for instance in an upper half of the aforementioned ranges) for the extraction and agglomeration processes and then may be diluted to a lower solids content slurry (for instance in a lower half of the aforementioned ranges) prior to solid-liquid separation. The diluting fluid may be a portion of the bitumen extract stream from the solid-liquid separation system and process.
[0044] The temperature of the oil sand slurry (108) may be in the range of 20-80 C, inclusively. The temperature of the oil sand slurry (108) may be any temperature included within or bounded by the preceding range. An elevated oil sand slurry temperature (for instance 60-80 C, inclusively) may be desired to increase the bitumen dissolution rate and reduce the viscosity of the slurry to promote more effective sand digestion and agglomerate formation. An elevated slurry temperature may be desired to improve the solid-liquid separation process. An elevated oil sand slurry temperature may result in a reduced slurry viscosity, which in turn, may improve solid-liquid separation. Temperatures above 80 C are generally avoided due to the complications resulting from high vapor pressures. However, one potential advantage of the process described herein is the ability to operate at higher pressures than conventional solid-liquid separation systems, such as filters.
[0045] The separator unit (114) may be configured to separate solids stream in the oil sands slurry (108) from bitumen extract in the oil sands slurry (108), (604).
The separator unit (114) may separate the solids from the bitumen extract because the separator unit (114) may include solid-liquid separation devices capable of separating solids from liquids so as to separate the solids from the bitumen extract. The separator unit (114) may be of the type that it is capable of being incorporated into a single enclosed vessel. Applicable separator units (114) include, but are not limited to one or more of at least one of a solid-liquid separator, at least one of a hydrocyclone, at least one of a gravity settler, and at least one of a centrifuge.
The separator unit (114) may contain a single solid-liquid separator. The separator unit (114) may contain more than one solid-liquid separator. When more than one solid-liquid separator and/or separation steps are conducted, it may be said that both steps are conducted within one separator unit (114). The separator unit (114) produces at least two streams when it separates the solids from the bitumen extract: the bitumen extract stream (110) and the solids stream (112). The bitumen extract stream (110) may have a solids content of less than 15 wt. %
solids. For example, the bitumen extract stream (110) may have a solids content of less than 5 wt. % solids. The solids content of the bitumen extract stream (110) may be any number within the aforementioned ranges.
[0046] If the separator unit (114) is a hydrocyclone, the hydrocyclone may comprise hydrocyclones arranged in a configuration suitable to separate the solids stream (112) from the bitumen extract stream (110). For example, the hydrocyclone may comprise hydrocyclones arranged in parallel to maximize the available throughput through the hydrocyclone unit while maintaining the desired amount of solid-liquid separation. The hydrocyclone may have the advantage of being a compact and a high throughput system that can be readily incorporated into a sealed vessel. The hydrocyclone may not generally have moving parts, thereby reducing the required maintenance of the hydrocyclone.
[0047] If the separator unit (114) is the gravity settler, the gravity settler may be a clarifier. The gravity settler may comprise a feed distribution unit that is designed to prevent or mitigate feed solids from contaminating the bitumen extract stream.
Suitable feed distribution units are known in the art for instance as described in U.S.
Patent Publication 2014/0091049 and International Patent Publication 2012/051536. The gravity settler may comprise internals to assist in the settling of solids. Additives and/or solvent may be added prior and/or within the gravity settler to increase the settling rate of solids. Suitable additives may be, but are not limited to, surfactants, flocculants, and coagulants. The solvent may be a paraffinic solvent that is added to precipitates asphaltenes. The solvent may increase the settling rate of solids.
[0048] The system (100) and process (600) may include an accumulator (118).
The accumulator (118) may be configured to receive the solids stream (112). The accumulator (118) may receive the solids from the separator unit (114) after the solids stream (112) exits the separator unit (114). The accumulator (118) may be in fluid communication with the separator unit (114). The separator unit (114) may discharge the solids stream (112) directly into the accumulator (118).
[0049] The accumulator (118) may be one of a vertically oriented vessel and a horizontally oriented vessel, with respect to inlet flow directions. A
horizontal orientation may provide superior fines removal since the solids settling velocity and superficial fluid velocity are perpendicular rather than countercurrent as in a vertical orientation. A vertical orientation may provide superior solids compaction, which, when combined with a fluidization unit, may reduce the amount of washing fluid required to hydraulically transport the solids and thus increase wash efficiency.
[0050] The accumulator (118) may be configured to remove additional bitumen extract (119) from the solids stream (112) to produce a concentrated solids stream (116), (606). The accumulator (118) may comprise a settling zone (not shown) and a compaction zone (not shown). Within the settling zone, the solids within the solids stream settle.
The solids may settle by gravity. The settling zone of the accumulator may be designed such that the solids undergo hindered settling. The settling zone may extend from the separation unit (114). In the case where a gravity settler is used as the separator unit (114), the settling zone may be an extension of the gravity settler. The compaction zone may compact the solids within the solids stream (112). The compaction zone may compact the solids within the solids stream (112) to, for example, a solids content of greater than 65 weight (wt.) % such that the concentrated solids stream (116) has a solids content of greater than 65 wt.
%. The compaction may occur simply by the weight of the solids stream (112). The compaction squeezes out fluid (bitumen/solvent mixture) and thus reduces the amount of bitumen entrained in the concentrated solids stream (116). Additional bitumen extract from the settling and compaction zones of the accumulator (118) may be discharged in one or more discharge ports (not shown) located in upper regions of the accumulator.
[0051] When the solids within the solids stream (112) compact, additional bitumen extract (119) may be separated out from the solids stream (112) such that the solids stream (112) separates into the additional bitumen extract (119) and the concentrated solids stream (116).
The additional bitumen extract (119) may percolate upwards as the solids stream (112) is compacted. After the additional bitumen extract (119) percolates upwards, the additional bitumen extract (119) may exit the accumulator (118). The additional bitumen extract (119) may be removed from an upper region of the accumulator (118). A screen (not shown) or filter (not shown) may be placed near outlet ports (not shown) of the accumulator (118) to prevent or mitigate at least some of the solids stream (112) from exiting the accumulator (118) when the additional bitumen extract (119) exits the accumulator (118). The additional bitumen extract (119) may pass through the screen or filter before being removed from the accumulator (118). The screen or filter may be constructed, such as but not limited to the size of the openings of the screen or filter, to prevent or mitigate at least some of the solids stream (112) from exiting the accumulator (118) when the additional bitumen extract (119) exits the accumulator (118).
[00521 The accumulator (118) may comprise internal structures, such as baffles, to assist in the movement of solids within the accumulator. In the case of a single vessel system, the accumulator may be located directly below the separator unit (114) in order to directly receive the solid stream (112) from the separator unit (114). The accumulator (118) may comprise the majority of the size of the single vessel in order to provide the required bed height and residence time for the desired compaction of the solids.
[0053] After exiting the accumulator (118), the additional bitumen extract (119) may be combined with the bitumen extract stream (110). The additional bitumen extract (119) may be combined with the bitumen extract stream (110) because the accumulator (118) may be in fluid communication with a line connecting the separator unit (114) to a solvent recovery unit (134).
[0054] The system 100 and process (600) may include a fluidizing unit (122). The fluidizing unit (122) may receive the concentrated solids stream (116) from the accumulator (118) when the concentrated solids stream (116) exits the accumulator (118).
The fluidizing unit (122) may receive the concentrated solids stream (116) because the accumulator (118) may be in fluid communication with the fluidizing unit (122). The fluidizing unit (122) may be one of directly below a compaction zone of the accumulator (118) and within the compaction zone of the accumulator (118). The compaction zone is illustrated in Figures 2 and 3.
[00551 The fluidizing unit (122) may be configured to discharge the concentrated solids stream (116). The fluidizing unit (122) may be used to discharge the concentrated solids stream (116) from the accumulator (118) in a controlled fashion. The fluidizing unit (122) may direct a washing fluid (120) at a pressure to the concentrated solids stream (116). The pressure may be about 8-10 psi above an operating pressure of the accumulator (118) and may be achieved using a pump. The fluidizing unit (122) and the washing fluid (120) may act to fluidize the concentrated solids stream (116) to produce a low bitumen extract slurry (124) that is discharged from the fluidizing unit (122). The fluidizing unit (122) may be sufficiently isolated from the settling zone of the accumulator (118) so as to prevent or mitigate mixing of the washing fluid (120) with the additional bitumen extract stream (119) that flows out of the accumulator (118). The low bitumen extract slurry (124) may be discharged with less than 20 wt.% of the bitumen that was dissolved within the oil sand slurry (108). The bitumen amount within the low bitumen extract slurry (124) may be any number bounded by or within the aforementioned range.
[0056] The washing fluid (120) may have a lower dissolved bitumen concentration than the bitumen extract stream (119). For example, the washing fluid (120) may be a solvent that is used to dilute the bitumen concentration within the concentrated solids stream (116). The washing fluid (120) may be a hydrocarbon liquid with a dissolved bitumen concentration lower than a dissolved bitumen concentration of the oil sand slurry (108). The washing fluid (120) may have the characteristics of the solvent as described in the present disclosure. The washing fluid (120) may displace and/or further extract/dissolve bitumen out of agglomerates.
A low boiling point (as described herein with reference to the solvent) of the washing fluid allows a lower energy consumption and/or substantial dissolving of asphaltenes.
[0057] In general, for better reliability, the fewer the moving parts in the fluidizing unit (122) the better. Suitable fluidizing units include, but are not limited to, one of an eductor, ejector, jet pump, Tore from Merpro Process Systems (National Oilwell Varco, Houston, Texas, USA), and gRay from FLSmidth gMAX Systems (Houston, Texas, USA). The fluidizing unit (122) may use the washing fluid as a motive fluid to fluidize solids and create a vortex to evacuate solids. In particular, the washing fluid may be introduced tangentially under pressure into a chamber of the fluidizing unit via a supply duct creating a vortex in the chamber. The vortex may fluidize the solids and force the solids out of the chamber via a discharge duct. An end of the supply duct may be closed when the fluidizing unit is not in use. The fluidizing unit (122) may be directly incorporated below the compaction zone of the accumulator (118). In this way, the accumulator (118) and the fluidizing unit (122) may be within a single vessel. The operational parameters of the fluidizing unit (122) may be adjusted to control a density of low bitumen extract slurry (124).
[0058] The (100) and process (600) may include a tailings solvent recovery unit (128).
The tailings solvent recovery unit (128) may receive the low bitumen extract slurry (124) from the fluidizing unit (122). The tailings solvent recovery unit (128) may be in fluid communication with the fluidizing unit (122). The tailings solvent recovery unit (128) may separate solvent (126) from a low bitumen oil sands slurry (130) within the low bitumen extract slurry (124) to output solvent (126) and a low bitumen oil sands slurry (130), (608).
The low bitumen oil sands slurry (130) may be considered a tailings stream from which one may choose to recover no further bitumen.
[0059] The system (100) and process (600) may include a solvent recovery unit (134).
The solvent recovery unit (134) may be in fluid communication with the accumulator (118).
The solvent recovery unit (134) may be in fluid communication with the separator unit (114).
The solvent recovery unit (134) may receive the bitumen extract (110) and the additional bitumen extract (119). The solvent recovery unit (134) may separate out solvent in the bitumen extract (110) and the additional bitumen extract (119) from bitumen product (136) in the bitumen extract (110) and the additional bitumen extract (119). The solvent recovery unit (134) may output solvent (132) and bitumen product (136) after the separation.
[0060] By recovering solvent, solvent may be used and re-used, even when a good deal of bitumen is entrained therein. Because an exemplary solvent to bitumen ratio of the bitumen extract may be 2:1 or lower, it is acceptable to use recycled solvent containing bitumen as the extraction liquor to achieve this ratio. The amount of re-used solvent may depend solely on solvent losses, as there is no requirement to store and/or not re-use solvent that has been used in a previous extraction step. When solvent is said to be "removed", or "recovered", this does not require removal or recovery of all solvent, as it is understood that some solvent will be retained with the bitumen even when the majority of the solvent is removed from the bitumen.
[0061] The system may contain a single solvent recovery unit for recovering the solvent in the oil sands slurry. The system may contain more than one solvent recovery unit for recovering the solvent in the oil sands slurry. Solvent may be recovered by conventional means. For example, typical solvent recovery units may comprise a fractionation tower or a distillation unit.
[0062] The solvent recovered may comprise bitumen entrained in the solvent, and can thus be re-used as the extraction liquor for combining with the bituminous feed. Other optional steps of the process may incorporate the solvent having bitumen entrained in the solvent, for example in countercurrent washing of solids. Additional solvent may be added to a solvent having bitumen entrained therein in order to adjust the solvent to bitumen ratio of the extraction liquor so as to achieve the selected ratio within the extraction vessel.
[0063] The system may be referred to as an oil sands solvent extraction process. The system may be combined with aspects of other oil sands solvent extraction processes, including but not limited to, those described above in the background section, and those described in Canadian Patent Application Serial No. 2,740,670 ("Adeyinka"), filed May 20, 2011, published June 30, 2010, and entitled "Method of Processing a Bituminous Feed using Agglomeration in a Pipeline".
[0064] Adeyinka discloses that, to extract bitumen from a bituminous feed in a manner that employs a solvent, the bituminous feed is contacted with an extraction liquor, comprising a solvent, to form an oil sand slurry. The oil sand slurry is then flowed through a pipeline.
Before introduction into the pipeline and/or at one or more points along the pipeline, an aqueous bridging liquid is added to the oil sand slurry to assist in agglomeration. Agitation within the pipeline is also used to assist agglomeration. The result of flow through the pipeline is an agglomerated slurry comprising agglomerates and a bitumen extract. The agglomerates are separated from the bitumen extract using a solid-liquid separation system.
Performing the agglomeration in a pipeline may provide certain advantages, such as improved sealing in order to contain the potentially flammable mixture of oil sands slurry from the atmosphere, production of smaller and more uniform agglomerates due to improved mixing of the aqueous bridging liquid into the oil sands slurry, and the flexibility to have long residence time for the extraction and agglomeration processes since the length of the pipeline can be readily increased to achieved the desired residence time. The use of the pipeline for the solvent extraction with solids agglomeration process described allows for an overall solvent extraction facility with an improved integration of the pipeline if used with the solid-liquid separation system (100) of the present disclosure.
[0065] The agglomeration of the solids in Adeyinka may improve the system (100) or process (600) described in the present disclosure. For example, the agglomeration of the solids stream (112) may reduce the amount of solids remaining in the bitumen extract stream (110) downstream of the separator unit (114). The larger particle sizes resulting from the agglomeration of the solids may allow for a higher rate of solid-liquid separation in the separator unit (114) than without agglomeration of the solids stream (112).
The aqueous bridging liquid within the agglomerates may displace the additional bitumen extract (119) during compaction within the accumulator (118). The displacement may allow the concentrated solids stream (116) to have less bitumen extract trapped within the concentrated solids stream (116), compared to a case where no aqueous bridging liquid is used. The aqueous bridging liquid may lubricate the concentrated solids stream (116) to lower the amount of fluid pressure needed by the fluidizing unit (122) to discharge the concentrated solids stream (116) from the accumulator (118).
[0066] The separator unit (114), the accumulator (118), and the fluidizing unit (122) may be disposed within, or form part of, a single vessel. The separator unit (114), the accumulator (118) and the fluidizing unit (122) may be isolated from a surrounding environment. The separator unit (114), the accumulator (118), and the fluidizing unit (122) may be referred to as a single solid-liquid separation step that produces a low solids bitumen extract stream and a low bitumen oil sands slurry. The system (100) and process (600) may employ a single solid-liquid separation step or may employ more than one solid-liquid separation steps. When more than one solid-liquid separation steps is employed, all of the steps may be conducted within one solid-liquid separation system. If the steps are dissimilar, or not proximal to each other, it may be said that a primary solid-liquid separation system is employed together with additional solid-liquid separation systems. For example, when primary and secondary separation systems are both employed, the primary separation system may separate a solid stream from the bitumen extract stream, while the secondary solid-liquid separation system may wash the solids to remove residual bitumen within, using a fluidizing unit (122).
100671 As a component of the solid-liquid separation system, secondary separation steps may be introduced for counter-currently washing the solids separated from the oil sand slurry.
The initial separation of the solids may be said to occur in a primary solid-liquid separation system, while the secondary steps may occur within the primary separation system, or may be conducted separately in a secondary solid-liquid separation system. The secondary solid-liquid separation system may be the same or different from the solid-liquid separation system described in the present disclosure. By "counter-currently washing", it is meant that a progressively cleaner solvent may be used to wash bitumen from the solids.
Solvent involved in the final wash of solids may be re-used for one or more upstream washes of solids, so that the more bitumen entrained with the solids, the less clean the solvent will be that is used to wash the solids at that stage. In this way, the cleanest wash of solids is conducted using the cleanest solvent. An example of counter-current washing is described with reference to Figure 4.
[00681 The additional solid-liquid separation steps for counter-currently washing solids may be included within the primary solid-liquid separation system. The additional solid-liquid separation steps may use a combination of separator units, accumulators, and fluidizing units similar to the primary solid-liquid step. The additional solid-liquid steps may be separate from the primary solid-liquid separation system. The additional solid-liquid separation systems may be the same or different from the primary separation system.
Different solid-liquid separation systems include at least one of gravity separators, cyclone, screens, and filters.
[0069] The solvent used for washing the solids may be solvent recovered from the low solids bitumen extract. A second solvent may alternatively or additionally be used for additional bitumen extraction downstream of an oil sands solvent extraction process.
[0070] Figures 2 to 5 illustrate particular system configurations by way of example.
[0071] Figure 2 is a schematic of a single vessel solid-liquid separation system with hydrocyclones as the separator unit. An oil sand slurry (202) is introduced into a series of hydrocyclones (204) arranged in parallel. Bitumen extract stream (206) is removed from the top of the hydrocyclones (204). Solids (208) settle in a settling zone (210) of the accumulator (210 and 218). The settling zone (210) comprises baffles (214). The additional bitumen extract stream (212) exits through a screen (216) and is combined with the bitumen extract stream (206). The solids (208) compact in a compaction zone (218) of the accumulator (210 and 218). A washing fluid (220) is introduced into a fluidizing unit (222) to produce a low bitumen oil sands slurry (224).
[0072] Figure 3 is a schematic of a single vessel solid-liquid separation system with a gravity separator as the separator unit. An oil sands slurry (302) is introduced into a gravity separator (304b). Bitumen extract stream (306) is removed from the gravity separator (304b).
The gravity separator (304b) comprises a baffle (314b). Solids (308) settle in a settling zone (310) of the accumulator (310 and 318). The solids (308) compact in a compaction zone (318) of the accumulator (310 and 318). A washing fluid (320) is introduced into a fluidizing unit (322) to produce a low bitumen oil sands slurry (324).
[0073] Figure 4 is a schematic of a multi-stage solid-liquid separation system with wash stages and four solid-liquid separation systems in series, namely, a first solid-liquid separation system (426a), a second solid-liquid separation system (426b), a third solid-liquid separation system (426c), and a fourth solid liquid separation system (426d). The first, second, and third solid-liquid separation systems (426a, 426b, and 426c) include first, second, and third, fluidizing units (422a, 422b, and 422c), respectively. An oil sand slurry (402) is introduced into the first solid-liquid separation system (426a). A washing fluid (420) is introduced into a third fluidizing unit (422c) of the third solid-liquid separation system (426c). First and second bitumen extract steams (406a and 406b) are removed from the first and second solid-liquid separation systems (426a and 426b), respectively. Third and fourth bitumen extract stream (406c and 406d) are recycled to the first and second solid-liquid separation systems (426a and 426b), respectively, as washing fluid. Solid streams (428a, 428b, and 428c) are directed downstream from the first to the fourth solid-liquid separation systems (426a and 426d). A
low bitumen oil sands slurry (424) is removed from the fourth solid-liquid separation system (426d). In this way, a progressively cleaner solvent is used to wash bitumen from progressively cleaner solids. Therefore, the washing fluid may comprise a downstream bitumen extract stream from a downstream process to counter-currently wash the solids.
[0074] Figure 5 is a schematic of a system for processing a bituminous feed comprising a slurry system, pipeline agglomeration, solid-liquid separation, and solvent recovery units. A
bituminous feed (502) is combined with a solvent (504) in a mix-box (506) producing an oil sands slurry (508). The oil sands slurry (508) is transported in a pipeline (510) having an extraction zone (512) and an agglomeration zone (514). The entry of the agglomeration zone is defined by the location where at least a portion of a aqueous bridging liquid is first injected.
The agglomerated slurry (516) exits the pipeline (210) and is introduced into a series of solid-liquid separation systems (530) as previously described with respect to Figure 4. The second bitumen extract stream (516b) is added to the oil sands slurry (508) transported in the pipeline (510). Solvent (534), recovered from the first bitumen extract stream (516a) in a solvent recovery unit (536) to make a bitumen product stream (538), is recycled for use as solvent (504) and washing fluid (532). A low bitumen slurry (540) is removed from the fourth solid-liquid separation system (542). Solvent is removed from the low bitumen slurry (540) in a tailings solvent recovery unit (544) to produce dry solids (546).
[0075] The performance of the single vessel solid-liquid separation system at least partially depends on the highest achievable solids content of the fluidizing unit discharge. The higher the solids content, the less the bitumen is entrained in the low bitumen oil sands slurry.
The solids content of the fluidizing unit discharge is at least partially controlled by a combination of the degree of compaction of the solids and the fluidization effectiveness of the fluidizing unit. It may be desirable to size the accumulator to provide a sufficient bed height to achieve a desired compaction of the solids. By increasing the efficiency of the fluidizing unit, one can reduce the amount of washing fluid required to hydraulically transport the solids. The performance or overall wash efficiency of the multi-stage solid-liquid separation system depends on the performance of each solid-liquid separation system and the number of solid-liquid separation systems.
[0076] As described above, the separator unit, accumulator, and the fluidizing unit may be within, or form part of, a single vessel. A single vessel system may have advantages over other systems, such as a multi-vessel system. The compact nature of the single vessel system may allow for effective sealing of the system from the environment, the ability to handle much higher pressures and/or higher temperatures, and effective heat insulation to limit heat loss than that of other systems. The fluidizing unit may provide high shear mixing, which may result in improved dispersion and/or mass transfer to scrub bitumen off the solids. The single vessel system may be made to have few or no moving parts and therefore may provide improved operability and/or easier maintenance than other solid-liquid separation systems.
The single vessel system may have a lower energy consumption compared to energy-intensive solid-liquid separation systems such as vacuum filters. The single vessel system may be more readily scaled to a size suitable to handle the large solid flow rates found in oil sands processing.
[0077] The solvents described in the present disclosure may include low boiling point solvents such as low boiling point cycloalkanes, or a mixture of such cycloalkanes, which substantially dissolve asphaltenes. The solvent may comprise a paraffinic solvent in which the solvent to bitumen ratio, the temperature, the pressure or a combination thereof are maintained at levels to avoid or limit precipitation of asphaltenes.
[0078] While it is not necessary to use a low boiling point solvent, when used, there is the extra advantage that solvent recovery through an evaporative or distillation process proceeds at lower temperatures, and requires a lower energy consumption. When a low boiling point solvent is selected, it may be one having a boiling point of less than 100 C.
The boiling point of the solvent may be any number within the aforementioned range.

[0079] The solvent may comprise an organic solvent or a mixture of organic solvents. For example, the solvent may comprise a paraffinic solvent, an open chain aliphatic hydrocarbon, a cyclic aliphatic hydrocarbon, or a mixture thereof. Should a paraffinic solvent be utilized, it may comprise an alkane, a natural gas condensate, a distillate from a fractionation unit (or diluent cut), or a combination of these containing more than 40% small chain paraffins of 5 to carbon atoms. This would be considered primarily a small chain (or short chain) paraffin mixture. Should an alkane be selected as the solvent, the alkane may comprise a normal alkane, an iso-alkane, or a combination thereof. The alkane may specifically comprise heptane, iso-heptane, hexane, iso-hexane, pentane, iso-pentane, or a combination thereof.
Should a cyclic aliphatic hydrocarbon be selected as the solvent, it may comprise a cycloalkane of 4 to 9 carbon atoms. A mixture of C4-C9 cyclic and/or open chain aliphatic solvents would be appropriate. Exemplary cycloalkanes include cyclohexane, cyclopentane, or a mixture thereof. If the solvent is selected as the distillate from a fractionation unit, it may for example be one having a final boiling point of less than 180 C. An exemplary upper limit of the final boiling point of the distillate may be less than 100 C. A mixture of C4-C10 cyclic and/or open chain aliphatic solvents would also be appropriate. For example, it can be a mixture of C4-C9 cyclic aliphatic hydrocarbons and paraffinic solvents where the percentage of the cyclic aliphatic hydrocarbons in the mixture is greater than 50%.
[0080] The process may be adjusted to render the ratio of the solvent to bitumen in the oil sand slurry at a level that avoids precipitation of asphaltenes during bitumen extraction. Some amount of asphaltene precipitation is unavoidable, but by adjusting the amount of solvent flowing into the system, with respect to the expected amount of bitumen in the bituminous feed, when taken together with the amount of bitumen that may be entrained in the extraction liquor used, can permit the control of a ratio of solvent to bitumen in the extraction vessel.
When the solvent is assessed for an optimal ratio of solvent to bitumen during agglomeration, the precipitation of asphaltenes can be minimized or avoided beyond an unavoidable amount;
costs of the oil sands solvent extraction process may be decreased due to decreased solvent when having the optimal ratio.
[0081] An exemplary ratio of solvent to bitumen to be selected as a target ratio during agglomeration is less than 2:1. A ratio of 1.5:1 or less, and a ratio of 1:1 or less, for example, a ratio of 0.75:1, would also be considered acceptable target ratios for agglomeration. For clarity, ratios may be expressed herein using a colon between two values, such as "2:1", or may equally be expressed as a single number, such as "2", which carries the assumption that the denominator of the ratio is 1 and is expressed on a weight to weight basis.
[0082] Prior to solid-liquid separation within the solid-liquid separation system and process, the oil sand slurry may be mixed with a aqueous bridging liquid in order to agglomerate the solids within the oil sand slurry and form an agglomerated slurry. The formed agglomerates within the agglomerated slurry may be sized on the order of 0.1-1.0 mm, or on the order of 0.1-0.3 mm. At least 80 wt. % of the formed agglomerates may be 0.1-1.0 mm, or 0.1 to 0.3 mm in size. The rate of agglomeration may be controlled by a balance between intensity of agitation within an agglomeration vessel, shear within the vessel which can be adjusted, for example, by changing the shape or size of the vessel, fines content of the slurry, aqueous bridging liquid addition, and residence time of the agglomeration process.
The agglomerated slurry may have a solids content of 20 to 70 wt. %.
[0083] The aqueous bridging liquid is a liquid with affinity for the solids particles in the bituminous feed, and which is immiscible in the extraction liquor. Exemplary bridging aqueous liquids may be water that accompanies the bituminous feed and/or recycled water from other aspects or steps of oil sands processing. The bridging aqueous liquid need not be pure water, and may indeed be water containing one or more salts, a waste product from conventional aqueous oil sand extraction processes which may include additives, aqueous solution with a range of pH, or any other acceptable aqueous solution capable of adhering to solid particles in such a way that permits fines to adhere to each other. The aqueous bridging liquid may be added to the slurry in a concentration of less than 20 wt. % of the slurry, less than 10 wt. % of the slurry, between 1 wt. % and 20 wt. %, or between 1 wt. %
and 10 wt. %.
The aqueous bridging liquid may comprise fine particles (for instance less than 44 pm) suspended therein. These fine particles may serve as seed particles for the agglomeration process. The aqueous bridging liquid may comprise less than 40 wt. % solid fines, or have a solids content of 20 to 70 wt.%.
[0084] The agglomeration process is assisted by some form of agitation. The form of agitation may be mixing, shaking, rolling, or another known suitable method.
The agitation of the feed need only be severe enough and of sufficient duration to intimately contact the aqueous bridging liquid with the solids in the feed. Exemplary rolling type vessels include rod mills and tumblers. Exemplary mixing type vessels include mixing tanks, blenders, and attrition scrubbers. In the case of mixing type vessels, a sufficient amount of agitation is needed to keep the formed agglomerates in suspension. In rolling type vessels, the solids content of the feed may be greater than 40 wt. % so that compaction forces assist agglomerate formation. The agitation of the slurry has an impact on the growth of the agglomerates. In the case of mixing type vessels, the mixing power can be increased in order to limit the growth of agglomerates by attrition of said agglomerates. In the case of rolling type vessels the fill volume and rotation rate of the vessel can be adjusted in order to increase the compaction forces used in the communition of agglomerates. These agitation parameters can be adjusted in the control system described herein.
[0085] The agglomeration process may occur within a pipeline. The oil sand slurry from the slurry system is fed into a pipeline where additional bitumen extraction may occur. The slurry flows within the pipeline, and at one or more point along the pipeline, an aqueous bridging liquid can be added to the pipeline to assist in the agglomeration of the solids within the pipeline. Alternatively or additionally, aqueous bridging liquid may be added to the oil sand slurry prior to the pipeline. Some form of agitation is also used to assist agglomeration.
The agitation may be provided by turbulent flow within the pipeline. The rate of agglomeration may be controlled by a balance between velocity within the pipeline (i.e. flow turbulence), fines content of the slurry, aqueous bridging liquid addition, and residence time within the pipeline. The agglomerated slurry from the pipeline, comprising of agglomerates and bitumen extract, is sent to the solid-liquid separation system to produce a bitumen extract stream and an agglomerated solids stream.
[0086] It should be understood that numerous changes, modifications, and alternatives to the preceding disclosure can be made without departing from the scope of the disclosure. The preceding description, therefore, is not meant to limit the scope of the disclosure. Rather, the scope of the disclosure is to be determined only by the appended claims and their equivalents.
It is also contemplated that structures and features in the present examples can be altered, rearranged, substituted, deleted, duplicated, combined, or added to each other.

Claims (33)

CLAIMS:

1. A system for separating a bitumen extract from solids, the system comprising:
(a) a separator unit configured to receive an oil sands slurry and to separate the solids in the oil sands slurry from the bitumen extract in the oil sands slurry to produce a bitumen extract stream and a solids stream;
(b) an accumulator configured to receive the solids stream and configured to remove additional bitumen extract from the solids stream to produce a concentrated solids stream; and (c) a fluidizing unit configured to discharge the concentrated solids stream by mixing the concentrated solids stream with a washing fluid to form a low bitumen oil sands slurry, wherein the separator unit, the accumulator, and the fluidizing unit are within, or form part of, a single vessel.

2. The system of claim 1, wherein the separator unit comprises one or more of: at least one solid-liquid separator, at least one hydrocyclone, at least one centrifuge, and at least one gravity settler.

3. The system of claim 2, wherein the separator unit comprises at least two hydrocyclones and the hydroclones are arranged in parallel.

4. The system of any one of claims 1 to 3, wherein the accumulator is one of a vertically oriented vessel and a horizontally oriented vessel.

5. The system of any one of claims 1 to 3, wherein the accumulator comprises a settling zone that settles the solids and a compaction zone that compacts the solids.

6. The system of claim 5, wherein the settling zone extends from the separator unit.

7. The system of any one of claims 1 to 5, wherein the accumulator comprises a screen or filter that is configured for the additional bitumen extract to pass through before being removed from the accumulator.

8. The system of any one of claims 1 to 7, wherein the accumulator comprises internal structures to assist in movement of the solids.

9. The system of any one of claims 1 to 8, wherein the separator unit discharges directly into the accumulator.

10. The system of any one of claims 1 to 9, wherein the fluidizing unit comprises one of an eductor, an ejector and a jet pump.

11. The system of any one of claims 1 to 8, wherein the fluidizing unit uses the washing fluid as a motive fluid to fluidize solids and create a vortex to evacuate solids.

12. The system of claim 5, wherein the fluidizing unit is one of directly below the compaction zone of the accumulator and within the compaction zone of the accumulator.

13. A process for separating a bitumen extract from solids within an oil sands solvent extraction process, the process comprising:
(a) receiving an oil sands slurry, wherein the oil sands slurry comprises the bitumen extract and the solids;
(b) producing a bitumen extract stream including the bitumen extract and a solids stream including the solids by separating the solids from the bitumen extract;
(c) producing a concentrated solids stream by removing additional bitumen extract from the solids stream; and (d) forming a low bitumen oil sands slurry by mixing the concentrated solids stream with a washing fluid, wherein steps (b), (c) and (d) are performed within a single vessel.

14. The process of claim 13, wherein the single vessel contains baffles.

15. The process of claim 13 or 14, wherein the single vessel comprises a separator unit and the separator unit comprises one or more of: at least one solid-liquid separator, at least one hydrocyclone, at least one centrifuge, and at least one gravity settler.

16. The process of any one of claims 13 to 15, wherein the separator unit comprises at least two hydrocyclones and the at least two hydroclones are arranged in parallel.

17. The process of any one of claims 13 to 16, wherein (c) comprises settling the solids in a settling zone and compacting the solids in a compaction zone.

18. The process of any one of claims 13 to 17, further comprising passing the additional bitumen extract through a screen or a filter to mitigate at least some of the solids stream from exiting the accumulator when the additional bitumen extract exits the accumulator.

19. The process of any one of claims 13 to 18, wherein the oil sands solvent extraction process is a solvent extraction with solids agglomeration process.

20. The process of claim 19, wherein the solids agglomeration process occurs within a pipeline.

21. The process of any one of claims 13 to 20, wherein (d) comprises mixing the concentrated solids stream with the washing fluid under pressure.

22. The process of any one of claims 13 to 21, wherein the washing fluid is a hydrocarbon liquid.

23. The process of any one of claims 13 to 22, wherein the washing fluid has a dissolved bitumen concentration that is lower than a dissolved bitumen concentration of the oil sands slurry.

24. The process of any one of claims 13 to 22, wherein the washing fluid comprises a downstream bitumen extract stream from a downstream process to counter-currently wash the solids.

25. The process of any one of claims 13 to 22, further comprising passing the low bitumen oil sands slurry to a downstream process to serve as the oil sands slurry.

26. The process of any one of claims 13 to 25, wherein the low bitumen oil sands slurry has less than 20 wt.% of bitumen that was dissolved in the oil sands slurry.

27. The process of any one of claims 13 to 26, further comprising heating the oil sands slurry prior to (b).

28. The process of any one of claims 13 to 27, further comprising adding at least one additive to the oil sands slurry prior to and/or during (b).

29. The process of claim 28, wherein the at least one additive comprises at least one of a surfactant, flocculant, and coagulant.

30. The process of any one of claims 13 to 29, further comprising adding a solvent to the oil sands slurry at least one of prior to and during (b).

31. The process of any one of claims 13 to 30, further comprising:
(i) forming an unagglomerated oil sands slurry by combining a bituminous feed with a first extraction liquor comprising a solvent;

(ii) flowing the unagglomerated oil sands slurry through a pipeline to extract bitumen and adding an aqueous bridging liquid to the unagglomerated oil sands slurry at least one of before and within the pipeline; and (iii) agglomerating the unagglomerated oil sands slurry to form an agglomerated slurry as the oil sands slurry.

32. The process of claim 31, further comprising passing the bitumen extract stream to the unagglomerated oil sands slurry for use as a second extraction liquor before adding the aqueous bridging liquid.

33. The process of claim 31 or 32, further comprising recovering solvent as recovered solvent from the bitumen extract stream and using the recovered solvent as the first extraction liquor or as the washing fluid.