Process and system for solvent addition to bitumen froth

Abstract

The field of the invention is oil sands processing. A solvent treatment system and process for treating a bitumen-containing stream include contacting that stream with a solvent-containing stream to produce an in-line flow of solvent diluted material; supplying the solvent diluted material into a separation vessel with axi-symmetric phase and velocity distribution and/or particular mixing and conditioning features. The solvent addition, mixing and conditioning may be performed with particular CoV, Camp number, co-annular pipeline reactor, pipe wall contact of low viscosity fluid, flow diffusing and/or flow straightening. The processes enable improved performance of downstream unit operations such as separation of high diluted bitumen from solvent diluted tailings.

Claims

1. A solvent treatment process for treating a high viscosity bitumen-containing stream, comprising: contacting the high viscosity bitumen-containing stream with a solvent-containing stream having a lower viscosity in a pipeline section comprising interior pipe walls, such that the solvent-containing stream flows downstream along the interior pipe walls prior to mixing between the high viscosity bitumen-containing stream with the solvent-containing stream; mixing the high viscosity bitumen-containing stream with the solvent-containing stream sufficiently downstream of the pipeline section to produce a mixed in-line flow of a solvent diluted material; supplying the solvent diluted material into a separation vessel; and withdrawing from the separation vessel a high diluted bitumen component and a solvent diluted tailings component.

2. The process of claim 1, wherein the bitumen-containing stream is provided at a flow rate between about 0.5 m/s and about 1.5 m/s and the solvent-containing stream is provided at a flow rate between about 2.0 m/s and about 4.0 m/s.

3. The process of claim 1, wherein the in-line flow of the solvent diluted material is provided at a flow rate sufficient to avoid minerals from settling prior to introduction into the separation vessel.

4. The process of claim 1, comprising providing a static mixer downstream of the pipeline section to perform the mixing.

5. The process of claim 1, wherein the pipeline reactor is a first pipeline reactor and the contacting of the bitumen-containing stream with the solvent-containing stream comprises: adding a first amount of the solvent-containing stream to the bitumen-containing stream in the first pipeline reactor to produce an intermediate mixture; and adding a second amount of the solvent-containing stream to the intermediate mixture in a second pipeline reactor, wherein the second amount is sufficient to produce the in-line flow of solvent diluted material.

6. The process of claim 5, comprising pumping the intermediate mixture prior to adding the second amount of the solvent-containing stream.

7. The process of claim 1, wherein the solvent-containing stream comprises paraffinic solvent and the bitumen-containing stream is a bitumen froth stream.

8. The process of claim 1, wherein the separation vessel is a first stage gravity settler vessel, the bitumen-containing stream is a bitumen froth stream and the solvent-containing stream is a first stage solvent-containing stream, the process further comprising: subjecting the high diluted bitumen component to solvent separation to produce a recovered solvent component; contacting the solvent diluted tailings withdrawn from the first stage gravity settler vessel with a second stage solvent stream containing the recovered solvent to form a second stage solvent diluted material; supplying the second stage solvent diluted material to a second stage gravity settler vessel; withdrawing from the second stage gravity settler vessel a second stage solvent diluted tailings component and a second stage solvent diluted bitumen component; recycling the second stage solvent diluted bitumen component as at least part of the first stage solvent-containing stream; subjecting the second stage solvent diluted tailings component to solvent recovery to produce a second stage recovered solvent component; and providing the second stage recovered solvent component as part of the second stage solvent stream.

9. A solvent treatment process for treating a bitumen-containing stream, comprising: contacting the bitumen-containing stream with a solvent-containing stream to produce an in-line flow of solvent diluted material comprising immiscible aqueous and hydrocarbon components; transporting the in-line flow of solvent diluted material toward a separation vessel using a pipeline comprising at least one fitting causing at least some of the immiscible aqueous and hydrocarbon components of the solvent diluted material to separate in-line and have a velocity gradient therebetween; diffusing the solvent diluted material to redistribute the velocity gradient created by the at least one fitting, prior to introduction into the separation vessel, to produce a diffused solvent diluted material stream flowing in-line, the diffused solvent diluted material stream having a reduced velocity gradient between the immiscible aqueous and hydrocarbon components compared to the velocity gradient prior to diffusing; introducing the diffused solvent diluted material stream into the separation vessel; and withdrawing from the separation vessel a high diluted bitumen component and a solvent diluted tailings component.

10. The process of claim 9, wherein at least one fitting comprises an elbow.

11. The process of claim 9, wherein the transporting of the solvent diluted material induces pre-mature separation or acceleration of the immiscible aqueous and hydrocarbon components with respect to each other.

12. The process of claim 9, wherein the diffusing is performed outside of the separation vessel.

13. The process of claim 12, comprising flowing the diffused solvent diluted material stream in a substantially linear manner into the separation vessel.

14. The process of claim 13, wherein the flowing of the diffused solvent diluted material stream is performed in a substantially vertically downward manner.

15. The process of claim 14, comprising feeding the diffused solvent diluted material stream to the separation vessel while avoiding contact with fittings.

16. The process of claim 9, wherein the bitumen-containing stream is a bitumen froth stream.

17. A paraffinic treatment process for treating a bitumen-containing stream, comprising: an in-line mixing stage to produce an in-line flow of paraffin diluted material containing precipitated aggregates comprising asphaltenes, fine solids and water, the in-line mixing stage comprising: mixing the bitumen-containing stream with a paraffinic solvent-containing stream to produce the in-line flow of paraffin diluted material; an in-line conditioning stage comprising imparting sufficient energy to the in-line flow to allow build-up and densification of the precipitated aggregates while avoiding overshear breakup thereof; a discharge stage comprising discharging the in-line flow into a separation vessel to allow separation of the precipitated aggregates in a solvent diluted tailings component from a high diluted bitumen component; and pressurizing the separation vessel at a separation vessel pressure, wherein low pressure points and cavitations are avoided from the in-line mixing stage to the discharge stage by tying the separation vessel pressure and a pressure of the in-line flow downstream of the in-line mixing stage to each other.

18. The process of claim 17, wherein the bitumen-containing stream comprises a bitumen froth stream or an underflow stream from a bitumen froth separation vessel.

19. The process of claim 18, wherein the in-line mixing stage comprises: introducing the solvent-containing stream into the bitumen-containing stream via a tee junction to form a mixture; and then passing the mixture through an in-line static mixer.

20. The process of claim 17, wherein the in-line mixing stage comprises: adding a first amount of the solvent-containing stream to the bitumen-containing stream to produce an intermediate mixture; and adding a second amount of the solvent-containing stream to the intermediate mixture sufficient to produce the in-line flow of solvent diluted material.

21. The process of claim 20, comprising pumping the intermediate mixture prior to adding the second amount of the solvent-containing stream.

22. The process of claim 17, wherein the separation vessel is a first stage gravity settler vessel, the bitumen-containing stream is a bitumen froth stream and the solvent-containing stream is a first stage solvent-containing stream, the process further comprising: subjecting the high diluted bitumen component to solvent separation to produce a recovered solvent component; contacting the solvent diluted tailings withdrawn from the first stage gravity settler vessel with a second stage solvent stream containing the recovered solvent to form a second stage solvent diluted material; supplying the second stage solvent diluted material to a second stage gravity settler vessel; withdrawing from the second stage gravity settler vessel a second stage solvent diluted tailings component and a second stage solvent diluted bitumen component; recycling the second stage solvent diluted bitumen component as at least part of the first stage solvent-containing stream; subjecting the second stage solvent diluted tailings component to solvent recovery to produce a second stage recovered solvent component; and providing the second stage recovered solvent component as part of the second stage solvent stream.

23. The process of claim 9, wherein the fitting comprises a pipe curvature.

24. The process of claim 9, wherein the diffused solvent diluted material stream is discharged into the separation vessel via a discharge nozzle that is formed as a single aperture at an end of a feedwell located in the separation vessel.

25. The process of claim 24, wherein the feedwell is vertically oriented such that the diffused solvent diluted material stream is discharged vertically downward into the separation vessel via the discharge nozzle.

26. The process of claim 17, wherein the discharge stage comprises discharging the in-line flow from a discharge nozzle that is formed as a single aperture at an end of a feedwell located in the separation vessel, the feedwell being vertically oriented within the separation vessel and the discharge nozzle being located within a chamber of the separation vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a plan cross-sectional view of a solvent addition pipeline reactor according to an embodiment of the present invention.

(2) FIG. 2 is a plan cross-sectional view of a paraffinic froth treatment (PFT) system including a froth settling vessel (FSV) according to another embodiment of the present invention.

(3) FIG. 3 is a process flow diagram of a paraffinic froth settling system for a PFT process, according to another embodiment of the present invention.

(4) FIG. 4 is a plan cross-sectional view of a solvent addition pipeline reactor according to another embodiment of the present invention.

(5) FIG. 5 is a plan cross-sectional view of a solvent addition pipeline reactor according to yet another embodiment of the present invention.

(6) FIG. 6 is a plan cross-sectional view of a solvent addition pipeline reactor according to a further embodiment of the present invention.

(7) FIGS. 7a-7c are plan cross-sectional views of solvent addition pipeline reactor configurations according to variants of embodiments of the present invention.

(8) FIG. 8 is a plan cross-sectional view of a PFT system including a froth settling vessel (FSV) according to a further embodiment of the present invention.

DETAILED DESCRIPTION

(9) Referring to FIGS. 1, 4, 5 and 6, which illustrate embodiments of a pipeline reactor 10 according to the present invention, a main input fluid 12 is provided for combination with an additive fluid 14. The main input fluid 12 may be bitumen froth derived from an oil sands mining and extraction operation (not illustrated) or an in situ recovery operation (not illustrated) or a blend of both. The main input fluid 12 may also be an underflow stream of a froth treatment process, which may use paraffinic or naphthenic solvent. The pipeline reactor 10 may be used in a variety of different stages within the froth treatment process, which will be further discussed herein below.

(10) Referring particularly to FIG. 1, which illustrates a “basic” pipeline reactor 10 according to an embodiment of the present invention, the bitumen froth or underflow 12 is supplied via a pipe 16 to the pipeline reactor 10. The pipeline reactor 10 includes a mixer section 18 to which the bitumen froth or underflow 12 is supplied. In the mixer section 18, the bitumen froth or underflow 12 flows through an orifice 20 or similar baffle arrangement to accelerate the froth or underflow 12 such that the discharge out of the orifice 20 develops turbulence eddies in a mixing zone 22. The additive fluid 14, which is this case is paraffinic solvent 14, is introduced through an annular region 24 for distribution via at least one solvent aperture 26, which may be defined as a restriction that jets the solvent 14 into the mixing zone 22.

(11) Two preferred criteria regarding the configuration of the annular region 24 and operation of the fluid flowing there-through are the following. Firstly, in the case of mixing miscible components with a large difference in viscosities and different viscosities, preferred mixing is achieved if the high viscosity medium is introduced into the low viscosity medium such that the low viscosity medium remains predominantly in contact with the pipe walls until mixing is achieved, i.e. the main input fluid 12 is the low viscosity medium and the additive fluid 14 is the high viscosity fluid. Secondly, the solvent 14 is preferably introduced into the annular region 24 in such a manner as to prevent a non-uniform flow profile leaving the annular region through the solvent apertures 26 when entering the mixing zone 22. This may be ensured by a number of means, including hydraulic analysis and basic engineering principles of fluid dynamics. Computation fluid dynamics (CFD) is a tool that may be used to ensure the design meets both requirements in a timely and cost effective manner. The preferred configuration and operation of the fluid flowing through the annular region account for these variables to ensure uniform three-dimensional feed from the annular region to the mixing zone. CFD methods permit testing for achieving, for example, jetting of the solvent, mixing and dispersion levels within the mixing zone, or axi-symmetric flow.

(12) Referring still to FIG. 1, in one embodiment of the present invention, the orifice 20 and the apertures 26 induce a combined turbulence on the bitumen froth 12 and the paraffinic solvent 14, causing an initial dispersion of solvent 14 into the bitumen froth 12 resulting in a rapid mixing of the two streams into a solvent diluted froth stream.

(13) Referring to FIGS. 7a-7c, the pipeline reactor 10 may have a variety of different generally co-annular configurations to achieve addition of the solvent 14 into the bitumen froth 12.

(14) Referring briefly to FIGS. 2 and 3, the solvent diluted froth stream is supplied to a froth settler vessel 28, which may be a first stage froth settler vessel 28a or a second stage froth settler vessel 28b.

(15) In one preferred aspect of the present invention used in PFT, the rapid mixing of the bitumen froth and paraffinic solvent is performed by providing froth velocity such that turbulence exists to effect the mixing without imparting shear in sufficient quantity or duration that would damage coalesced or flocculated structures in the solvent diluted froth stream. Coalesced or flocculated structures directly impact the separation in the froth separation vessel 28. For flocculation processes involving long chain polymers, shear at the appropriate level creates entanglement of the flocculating chains and consolidation of the structures without breakage. For PFT coalesced or flocculated structures, this kind of entanglement does not exist; rather, structures may stick and compress or existing structures with high voidage may comprises to form denser and higher settling structures. One may refer to such PFT structures as densified settling structures. Even among such structures, there are higher density settling structures and lower density settling structures. Excessive shear can break apart the lower density settling structures, which have higher voidage and are held together weakly by precipitated asphaltene bonds and viscous forces. Breakage of such lower density settling structures may decrease settling efficiency and re-suspend the broken material in the fluid, thus decreasing the efficiency of the settling separation operation.

(16) Referring now to FIGS. 1, 4, 5, and 6 the solvent diluted froth stream flows through a pipeline conditioning zone 30 of the pipeline reactor 10 prior to being introduced into the settling vessel (28 in FIGS. 2 and 3). More regarding the pipeline conditioning zone 30 will be discussed herein-below.

(17) Referring to FIG. 1, the pipeline reactor 10 is preferably constructed to have a cylindrical pipe section 32 having an internal diameter D and length L that provides energy input by hydraulic shear stresses. Such energy input by hydraulic shear stresses enables coagulation of free water droplets and flocculation of asphaltene droplets together with finely dispersed water droplets and minerals linked to asphaltene molecules, to produce a conditioned PFT settler feed stream 34. With optimum conditioning, the settling vessel produces a clean high diluted bitumen product. Of course, it should be understood that the pipe section 32 and other sections and components of the pipeline reactor may have different forms and orientations not illustrated in the Figs, and are not restricted to cylindrical, straight or horizontal configurations. The pipe section 32 preferably includes fittings and in some cases baffles in situations where layout may constrain the length of the pipeline reactor such that the equivalent length of pipe can provide the energy input for forming the coalesced or flocculated paraffin-asphaltene-water structures while avoiding overshear of those structures.

(18) Referring to FIG. 2, the conditioned settler feed stream 34 is fed into the FSV 28 via a discharge nozzle 36. The discharge nozzle 36 preferably comprises a single aperture at the end of the feedwell located within the vessel 28. The discharge nozzle may be an end of pipe or custom made nozzle. In the preferred cost-effective design, the discharge nozzle is robust and structurally simple providing advantageous predictability, balanced fluid flow and distribution and effective treatment to avoid upsetting floc structure in the froth treatment process. The discharge nozzle 36 is preferably located within the vessel 38 in a central location that is equidistant from the surrounding side walls. It should nevertheless be understood that the discharge arrangement could alternatively include multiple inlets which may be located and controlled in a variety of ways.

(19) Referring now to FIG. 1, internal diameters of the components of the pipeline reactor 10, including the bitumen froth pipe 16, orifice 20, annular region 24, apertures 26, and mixing and conditioning pipe 32, are based on fluid volumes and are in part offset by fluid velocities due to particular fluid properties. Bitumen froth pipelines preferably operate at about 0.5 m/s to about 1.5 m/s due to high fluid viscosities, which limits settling of minerals while increasing pressure losses. Solvent pipelines preferably operate at about 2.0 m/s to about 4.0 m/s reflecting the low fluid viscosity and associated pressure losses. Solvent diluted froth pipelines typically operate over about 2.5 m/s as minerals can settle from diluted froth in horizontal or vertical up-flow piping sections which could lead to operational issues.

(20) In one embodiment of the present invention, the mixture is blended to have a preferred coefficient of variation (CoV) to maximize both bitumen recovery into the high diluted bitumen product and the quality of the product. The preferred CoV may be determined, pre-set or managed on an ongoing basis. CoV is a measure of the relative uniformity of the blended mixture. In one optional aspect, CoV may be up to about 5% and optionally about 1% as lower target. With uniform blending, both asphaltene rejection and water coalescence occur in a generally uniform manner across the pipe diameter D of the pipeline reactor 10. Poor mixing can result in over-flocculation or over-coalescence in high solvent concentration zones and little to no flocculation or coalescence in low solvent concentration zones that pass through the conditioning zone of the pipeline reactor 10. For rapid mixing, which is preferred, CoV is to be achieved within ten diameters of the orifice 20 and preferably less than five diameters of the orifice 20.

(21) Referring to FIG. 2, the discharged solvent diluted bitumen froth 36 is separated into solvent diluted tailings 38 and high diluted bitumen 40. Purge gas 42 may also be introduced into the vessel 28 to mitigate phase separation, for instance due to elevation of high point of the mixer 10 above the froth separation vessel 28. Vent gases 44 may also be removed.

(22) In another optional aspect, the blending of the mixture is performed to achieve a desired density differential between the solvent diluted bitumen and the aqueous phase to enhance bitumen recovery in the froth separation vessel. As the density of bitumen is similar to that of water, undiluted bitumen in the feed will tend to stay with the aqueous phase rather than the high diluted bitumen phase which has a density differential with respect to the aqueous phase, resulting in reduced overall bitumen recovery. The amount of undiluted bitumen depends on the mixing and thus can be represented by the CoV. The CoV may therefore be managed and controlled to a sufficiently low level so as to reduce undiluted bitumen in the settler feed which, in turn, results in improved recovery of the bitumen in the high diluted bitumen stream. For instance, in a two-stage settler arrangement, the mixing for the feed provided to the first stage vessel may have a sufficiently low first stage CoV.sub.1 to achieve bitumen recovery ranging from about 90% to about 97%, preferably about 95%, and the mixing for the feed provided to the second stage vessel may have a sufficiently low second stage CoV.sub.2 to achieve an overall bitumen recovery ranging above 98%. In another aspect, the CoV is sufficiently low, for instance around 1% or lower, to use a single settler vessel to effect the separation with adequate recovery.

(23) In another optional aspect, the solvent and the bitumen froth are sufficiently blended based on their initial temperatures so that the solvent diluted bitumen mixture introduced into the separation vessel is discharged at a generally consistent temperature within the stream to avoid temperature variations within a same portion of discharged solvent diluted bitumen. The bitumen froth or underflow stream temperature may differ from the solvent temperature and thus, without sufficient blending to a consistent mixture temperature, there can be thermal gradients in the discharged solvent diluted bitumen and in the froth separation vessel, which would adversely impact the separation performance. The settler vessels are large vessels whose performance can be susceptible to thermal upsets. Thus, controlling the mixing to provide consistent temperature of throughout the feed allows effective operational performance of the settler vessel.

(24) Referring now to FIG. 3, illustrating an overall two-stage froth settling process, the bitumen froth 12 is supplied to a first pipeline reactor 10a where it is mixed with a recovered solvent stream 46 to form the conditioned PFT settler feed for the first stage vessel 28a. In another optional aspect, the recovered solvent 46 maybe supplemented by trim diluent/solvent 48 to permit adjusting the S/B ratio in the froth settler feed without modifying operating conditions on the second stage settling vessel, facilitating start up or shut down operations of the froth settling process, or a combination thereof. The conditioned PFT settler feed is introduced into the first stage froth settler vessel 28a via the discharge 36a, which is preferably configured as in FIG. 2.

(25) Referring now to FIGS. 1, 4, 5 and 6, the solvent addition pipeline reactor has the discharge 36 for discharging conditioned PFT settler feed 34 into the froth settling vessel. The discharge 36 of the pipeline reactor is preferably provided at the end of a feedwell which provides axi-symmetrical distribution of PFT settler feed 34 into the settler vessel 28. The diluted froth discharged from the pipeline reactor as conditioned PFT settler feed 34 is suitable for gravity separation of diluted bitumen from water, minerals and precipitated asphaltenes in a froth settling vessel 28, for example as illustrated in FIG. 2.

(26) Alternatively, as shown in FIG. 6, there may be several mixing zones. More particularly, the pipeline reactor 10 may include a pre-blending zone 22a where a first amount solvent 14a is mixed into the froth or underflow 12 and subsequently another mixing zone 22b where a second amount of solvent 14b is introduced into the oncoming solvent pre-diluted bitumen froth to produce the solvent diluted froth that then flows through the conditioning zone 30 and eventually to the discharge 40 as conditioned PFT settler feed 34. The premix zone 22a may use a standard pipe tee or “tee mixer” followed by a pipeline to blend the streams to an acceptable first CoV.sub.1 unless layout considerations limit the length of the pipeline to less than 100 pipe diameters, in which case a static mixer (not illustrated) may assist in blending the streams. Preferably, this embodiment of FIG. 6 allows blending the first portion of the solvent 14a into the feed 12 at a level below that required to initiate asphaltene precipitation and the second portion of the solvent 14b is subsequently mixed into the pre-diluted mixture in an amount to effect asphaltene precipitation. This staging of solvent addition may improve the addition and blending of solvent into the feed. In another aspect, the staged mixing is performed to minimize hydraulic losses associated with the pipelining of bitumen froth. In addition, for underflow from a froth settler, there may also be a pump (not illustrated) in the pre-mix section 22 to assist dispersing aggregated bitumen-asphaltene globules prior to a second amount of solvent addition.

(27) Furthermore, referring to FIG. 4, the pipeline reactor 10 may include a standard pipe tee or “tee mixer” 50 followed by a static mixer 52, in lieu of the co-annular type mixer illustrated in FIG. 1, for blending the bitumen froth 12 with the solvent 14. In such a case, it is preferable that the large viscosity difference between the input streams is taken into account for the static mixer. For detailed design of tee and static mixer configurations, one may look to “Handbook of Industrial Mixing: Science and Practice” E. Paul, V Atemio-Obeng, S Krestra. Wiley Interscience 2004. The rapid mixing and blending permits tubular plug flow for development of densified asphaltene floc settling structures and coalesced water within the length L of the conditioning section 30 of the PFT pipeline reactor 10. Static mixers may effectively mix and blend fluids with acceptable shear rates and can be assessed by CFD techniques. Depending on the length L and the pipe configuration upstream of the discharge into the settling vessel, the static mixer may be arranged at various locations. For instance, if L is particularly short, the static mixer may be arranged in the feedwell inside the vessel. Preferably, the static mixer is provided outside the vessel for ease of maintenance and monitoring.

(28) Referring now to FIG. 1, the solvent diluted bitumen or underflow 12 passes from the mixing zone directly to the pipeline conditioning zone 30. More regarding the pipeline conditioning zone will be discussed below in connection with the operation of the present invention.

(29) FIG. 2 shows a more detailed embodiment of the froth settler vessel 28 used in connection with the present invention. The conditioning section of the PFT pipeline reactor is also part of the feedwell pipe to froth settling vessel 28 discharging at an elevation to preferably provide axis-symmetrical flow into the froth settling vessel 28. In the froth setting vessel 28, the conditioned feed separates into the overflow product stream 40 or high diluted bitumen and an underflow stream 38. It is also noted that the vapor space of the froth settler vessel 28 is preferably supplied with the purge gas 42 to maintain a sufficient pressure in the froth settling vessel 28 that prevents phase separation within the PFT reactor 10. Phase separation in the PFT reactor may adversely affect the asphaltene floc structure.

(30) FIG. 3 shows a more detailed embodiment of the two-stage PFT process used in connection with the present invention with PFT pipeline reactors 10a and 10b conditioning the feed to the 1.sup.st and 2.sup.nd stage forth settler vessels respectively. In addition, the trim diluent 48 may be added to the solvent to the 1st stage PFT reactor 10a to permit close control of the S/B ratio and facilitate start up or shut down operations.

(31) FIG. 5 shows further embodiments of the pipeline reactor and settler vessel combinations, with optional elements, used in connection with the present invention. For instance, as shown in FIG. 5, the conditioning section of the reactor downstream of the solvent injection and mixing zones may include an expansion reducer 54 and/or flow diffuser 56. More regarding the flow diffuser will be discussed in greater detail herein-below.

(32) In one embodiment of the present invention, the Camp number may be used to determine preferred operating conditions and equipment configurations for mixing. The Cumulative Camp number is a dimensionless term developed in water treatment flocculation systems as a measure of the extent of coagulation of aggregates and combines shear rates with duration. Camp numbers are associated with increasing aggregate coagulation provided that shear rates are below a critical value that causes the aggregates to break up. Duration reflects the time exposure of the fluid to shear to produce optimum flocculated aggregates for separation.

(33) Pilot test scale of PFT reactors coupled to a froth settling vessel demonstrated acceptable separation of high diluted bitumen from diluted froth with cumulative Camp numbers between 5,000 and 12,000. Shear and pipe fittings such as elbows, bypass tees and isolation valves contribute to cumulative Camp number. As the shear in piping is directly related to the velocity in the pipe, an expansion reducer 54 as illustrated in FIG. 5 provides an option to manage the cumulative Camp number provided the layout incorporates provisions to mitigate settling of minerals and excessive coalescence of free water.

(34) In one aspect, the PFT pipeline reactor discharges via a discharge nozzle 36 directly into the settler vessel 28 with sufficient axi-symmetric phase and velocity distribution to promote integrity and settling of the precipitated aggregates and water drops with suspended minerals. In an optional aspect, flow diffusers 56 are provided and configured to redistribute coalesced water and poor flow velocity patterns from upstream pipe fittings, such as elbows, to promote consistent axi-symmetric flow and velocity into the settling vessel. Other flow conditioning arrangements and configurations may also be used to achieve axi-symmetry of the settler feed flow.

(35) In this regard, when the solvent containing stream is added to the bitumen froth or underflow stream, the two streams initially mix together as substantially miscible components. After the solvent dilutes the bitumen components, and in the case of paraffinic solvent reacts to form asphaltene flocs and water drops, the solvent diluted mixture forms stream containing immiscible components. The immiscible components may tend to separate in-line, particularly when the pipeline leading to the settler vessel has elbows and curvatures and the like which may accelerate one component relative to another, intensifying in-line separation and increasing the relative velocity differential between some of the immiscible components. For example, in some cases, an aqueous component may separate and form a slip stream along one side of the pipe conduit while the hydrocarbon component occupies the other side and the aqueous and hydrocarbon components move at different velocities. In other cases, due to pipeline configuration, a component may be induced to have a spiral-like trajectory along the pipeline resulting in inconsistent discharge into the settler vessel. If the feed into the settling vessel has irregular velocity distributions of immiscible components such as the hydrocarbon and aqueous components, the separation performance can be significantly decreased.

(36) In order to mitigate the separation of the immiscible components of the solvent diluted bitumen froth or underflow prior to introduction into the settling vessel, the feed line to the vessel may be configured or provided with means in order to redistribute the velocity and composition gradients that may have developed from various upstream pipeline geometries and fittings.

(37) Referring to FIGS. 5 and 8, a flow diffuser 56 is provided prior to introducing the solvent diluted bitumen froth into the settler vessel. In certain plant setups, it is necessary to have pipelines with arrangements that are non-linear and sometimes winding from the solvent addition point and the settler vessel discharge. By employing a flow diffuser, the negative effects of upstream pipeline bends and elbows can be mitigated. Preferably, the flow diffuser is provided proximate to the settler. Also preferably, the pipeline downstream from the flow diffuser that feeds the settler is substantially linear and avoids curvatures, elbows or fitting that would induce phase separation or phase velocity differentials.

(38) In another optional aspect, the feed line may be configured so as to avoid significant separation inducing arrangements, such as elbows or significant curvatures, between the solvent addition point and the settler discharge point. It should also be noted that the feed line may be configured so as to avoid significant separation inducing arrangements, such as elbows or significant curvatures, between the point at which the immiscible components form (which would be a distance downstream from the solvent addition point) and the settler discharge point.

(39) Referring to FIG. 8, in another optional aspect, a straightener 59 may be provided downstream of the diffuser 56 for straighten stray flow currents. The diffuser redistributes the velocities of the components of the in-line flow, but the resulting diffused flow may still have circular or rotational flow patterns which, if allowed to persist until the discharge, can negatively impact the separation performance and reliability. The straightener 59 may comprise at least one plate spanning the diameter of the pipe and extending a certain length along the pipe. The straightener 59 may be located proximate the discharge of the feedwell and may be located inside or outside of the separation vessel 28. Preferably, the straightener 59 comprises at least two crossed plates forming at least four quadrants for straightening the fluid flow prior to discharge. It should be understood that there may be additional plates or structures for effecting the straightening. The straightener 59 may be sized to have a length sufficient to allow straightening while minimizing fouling. Thus, the diffuser restricts larger bulk movements such as slip streams while the straightener removes residual circular or eddy-like flow patterns.

(40) In another optional aspect, various sections of the pipeline extending from the solvent addition device 10 to the discharge nozzle 36 may be sized to achieve preferred conditioning of the solvent diluted material and its various components including hydrocarbon, aqueous and gas phases.

(41) According to an embodiment of the invention, the pipeline reactor combines knowledge of the difference between mixing of miscible components and their mass transfer limitations as well as mixing of non-miscible components with rapid stream mixing and coalescence/flocculation of diluted froth streams to produce an improved diluted froth or underflow tailings stream for separating a high diluted bitumen stream from a bottoms stream comprising minerals, water and asphaltenes. Implementation of the pipeline reactor in paraffinic froth treatment provides advantages related to improved product quality and bitumen recovery.

(42) According to some embodiments of the solvent pipeline reactor, the specification of the orifice and associated solvent injection limit contact of the froth or underflow with the interior pipe wall to avoid non-symmetrical flow patterns that inhibit rapid mixing. If the high viscosity media, i.e. the froth or underflow, contacts the walls it tends to mix slowly with the lower viscosity solvent due to the presence of the wall preventing low viscosity media from blending from all sides. Mixing time would thus be increased as blending is impeded on the side on which the high viscosity fluid is against the interior pipe wall.

(43) The blending specification to CoV also promotes recovery of bitumen to the froth settler product. If bitumen is not diluted when mixed with solvent, the high density of bitumen inhibits the separation from aqueous systems in the froth settler vessel.

(44) The specification on CoV also blends froth or underflow stream temperature with the solvent temperature to a consistent temperature of the blended streams feeding the froth settling vessel to promote thermal stable conditions in the froth separation vessel.

(45) According to an embodiment of the invention, the system uses knowledge of the cumulative Camp Number to design a PFT reactor system to improve the coalescence/flocculation of contaminants in the feed supplied to a paraffinic froth treatment settler. This knowledge overcomes various drawbacks and inefficiencies of known techniques, in part by accounting for conditioning times for the reactions both in terms of shear magnitude, shear time, time and flow regime upon introduction into the froth settler vessel. For instance, exceeding the cumulative Camp number increases the problem and frequency of breakdown of the coalesced water droplets and aggregated asphaltenes, leading to reduced separation performance in terms of recovery or product quality or both.

(46) In addition, the distribution pattern from the pipeline reactor into the settler preferably provides a substantially axi-symmetrical flow feeding and loading in the settler. Non-axi-symmetrical loading causes upsets and unpredictable settler performance. More regarding the operation of the PFT pipeline reaction and other embodiments of the present invention will now be discussed.

(47) Froth or underflow is preferably be supplied from a dedicated pumped supply to maintain the hydraulic pressure at the PFT pipeline reactor inlet such that no additional pumping which may overshear PFT flocculated asphaltenes or coalesced water required to overcome both static and differential pipe head losses prior to the froth settling vessel.

(48) The froth or underflow supplied to the pipeline reactor is envisioned as being instrumented (not shown) with a continuous flow meter, a continuous density meter, and/or analyzer and means to control the froth or underflow flow by any standard instrumentation method. An algorithm from the density meter or analyzer would input to the flow meter to determine the mass flow of froth or underflow to the given PFT pipeline reactor.

(49) The solvent solution supplied to the reactor is preferably a pumped liquid and instrumented (not shown) with a continuous flow meter, a continuous density meter, and or analyzer. The delivery pressure of the solvent solution at the pipeline reactor would preferably reflect the hydraulic properties of the solvent and the nozzle or aperture configuration to achieve the initial mixing.

(50) The froth separation vessel pressure is preferably tied to the pipeline reactor pressure to ensure that no low pressure points at undesirable places exist in the feed system that would compromise floc formation. One example of an outcome would be that pressure is maintained to prevent cavitations which may cause pressure fluctuations at elevated points in the reactor system due to differences in density and differences in friction loss between bulk fluids and their individual components. The design and operation thus preferably accounts for these factors to produce an optimum overall design to ensure the feed is conditioned appropriately and that the separation can occur in an optimum manner.

(51) The injected solvent solution is preferably ratio controlled to the quantity of feed froth for first stage settler and underflow for second stage settlers. Trim solvent may be added to the first stage settler solvent-containing stream in upset or startup modes. In normal operation, the solvent added upstream of the first stage settler consists of the overflow stream from the second stage settler. Downstream from the mixing zone, an in-line meter or a small slip stream of diluted froth is continuously analyzed for solvent/bitumen ratio, which may then provide feedback to control the solvent dilution for a specific settler performance. The analytical methods to continuously monitor the solvent/bitumen ratio may be refractive index metering instrumentation such as disclosed in Canadian patent No. 2,075,108 with alternate methods such as deriving the solvent/bitumen ratio from blended hydrocarbon density temperature corrected to reference densities for bitumen and solvent and/or comparing the feed solvent/bitumen ratio to the overflow product solvent/bitumen ratio.

(52) Rapid mixing of solvent solution into froth is preferred for flocculating reactions. Some theories have these reactions occurring at a molecular scale and occur in distinct stages. Firstly, the solvent as mixed into the froth reduces the viscosity of the hydrocarbon phase that allows free water and mineral to start coalescing. The solvent causes the asphaltenes to precipitate together with dispersed water and minerals (bound to bitumen). Secondly, both the water coalesces and the asphaltenes flocculate to larger particles in the initial conditioning stage, where rearrangement reactions increase the strength of the flocculated asphaltenes. Thirdly, if excess energy is input by too long a pipe, high velocities or over aggressive mixing apparatuses, over-shearing disperses the flocculated asphaltenes and coalesced water structures.

(53) Rapid mixing thus quickly establishes the starting point for the flocculation and coalescing reactions to occur. The pipeline provides the conditioning time for the reactions to maximize the separation of the high diluted bitumen from the feed stream. The instrumentation identified in the operation description permits process control to deliver conditioned feed. The critical Camp number where shear adversely affects flocculation may be determined or estimated to establish preferred design parameters of the system.

(54) Referring to FIG. 8, the pipeline reactor 10 may also have a bypass line 60 for bypassing the reactor 10 in order to repair, replace or conduct maintenance or cleaning on the pipeline reactor 10. The diffuser 56 may also have a bypass line 62 for similar reasons. In addition, the separation vessel 28 may have a recirculation line 64 for recycling a portion of the discharged underflow back into the feed of the separation vessel 28, either upstream or downstream of the reactor 10, mixer 52 and/or diffuser 56, and/or directly back into the vessel 28, depending on the given scenario. Recirculation may be desirable during startup, downtimes, upset or maintenance operation modes, for example. Recirculation of a portion of the underflow may also have various other advantageous effects.

(55) It should be noted that embodiments of the present invention described herein may be used in other applications in the field of oil sands fluids mixing and processing, for instance for inducing precipitation, chemical reaction, flocculation, coagulation, pre-treatments for gravity settling, and the like, by injecting in-line injection of one fluid into another. In one example, polymer flocculent can be injected into mature fine tailings to induce flocculation prior to depositing the flocculated material to allow dewatering and drying. In another example, a demulsifying or conditioning agent can be injected into froth or high viscosity underflow streams such as from froth settling vessels, thickeners to promote flocculation and or coalesce separations in subsequent separation vessels.

(56) Recognizing initial simple blending model used in naphthenic froth treatment was incomplete or inapplicable in paraffinic froth treatment as asphaltene aggregation is a flocculation process, led to the development of paraffinic embodiments of the present invention. By way of examples, it is noted that various hydraulic investigations of feed piping systems for pilot and commercial paraffinic froth treatment process were conducted and identified that various fittings commonly encountered in piping networks such as valves, tees and elbows create high turbulence levels translating to high shear zones and non axi-symmetric flow regimes. These investigations revealed several advantageous aspects of embodiments of the present invention.

(57) It should also be noted that embodiments of the co-annular pipeline reactor and other mixing and conditioning configurations described herein may have a number of other optional or preferred features, some of which are described in Canadian patent application Nos. 2,701,317 and 2,705,055, which are incorporated herein by reference.

(58) Finally, it should be understood that the present invention is not limited to the particular embodiments and aspects described and illustrated herein.