Patent Publication Number: US-2021163826-A1

Title: High temperature paraffinic froth treatment process

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. Patent Application Ser. No. 61/105,764, filed on Aug. 20, 2018, which claims the benefit under 35 U.S.C. 119(e), of U.S. Provisional Application 62/547,278, filed Aug. 18, 2017, and the file contents of each is expressly incorporated herein by reference in their entirety. 
    
    
     FIELD 
     Embodiments taught herein relate to processing of a bitumen-containing froth to produce a bitumen product and, more particularly, are related to a high temperature paraffinic froth treatment process. 
     BACKGROUND 
     Canada has a wealth of heavy oil and bitumen available for extraction by various means and conversion into a variety of useful and valuable products: fuels, plastics, fertilizer. Some of this oil is best removed from its sandy substrate through mining techniques, which are less energy intensive than most in-situ or conventional extraction techniques. Most mined oil sands are extracted using a version of the warm water washing process described in Canadian Patent 448,231 to Clark, producing “froth”—bitumen droplets suspended in mineral laden water with a typical composition in the range of 60% bitumen, 30% water and 10% mineral. 
     Alternatives to warm water extraction include a solvent extraction process, which is described in an Environment Canada Report (1994). Alternatively, a thermal extraction process can be used, which is similar to the Alberta Taciuk Process described in U.S. Pat. No. 4,180,455. 
     A variety of technologies have been used over time for cleaning the “froth” to remove the residual water and mineral, making it suitable for further processing using conventional oil refining techniques. The conventional oil business uses custom treating for an equivalent purpose—typically heating the mixture and adding chemistry which will break emulsions and flocculate minerals, which can then settle by gravity. The most conventional froth treatment process involves the addition of a diluent (naphtha) to invert the emulsion and reduce the density and viscosity of the oil phase, followed by gravity settling in various forms (naphthenic froth treatment process). In some cases, chemistry has also been added to break emulsions or flocculate minerals from oil sand froth, as is described in a paper titled “Process reagents for the enhanced removal of solids and water” (Madge, 2005). 
     In the early 1990&#39;s, it was noted that incompatibility with some diluents, in the case of Athabasca bitumens, resulted in the precipitation of a portion of the asphaltene fraction of the oil. Further, it was noted that the incompatibility also resulted in the breaking of emulsions and the agglomeration of gangue material into readily settling particles. The process became the paraffinic froth treatment process as outlined in Canadian Patent 2,149,737 to Syncrude. In parallel, refiners have looked at partial upgrading of residues through a related precipitation in what is called the ROSE process, described in published PCT Application WO2007/001706 to Iqbal et al. Both the Syncrude and the ROSE processes use a paraffinic solvent to precipitate some, if not all, of the asphaltene present in the heavy oil (fraction), as defined by the Hildebrand or Hansen solubility parameters. 
     In practice, an early version of the paraffinic froth treatment process implemented in oil sands was a low temperature paraffinic froth treatment (LTPFT) plant installed at the Albian Sands Facility in northern Alberta, Canada. The process is described in Canadian Patent 2,588,043 to Shell Canada Energy. Further research resulted in the development of a high temperature paraffinic froth treatment (HTPFT) process, which produced better agglomerates that were tighter, denser and less susceptible to damage by shear forces, as described in Canadian Patent 2,454,942 to TrueNorth Energy Corp., currently owned by Fort Hills Energy LP. The HTPFT process is the root of a series of designs that have since been installed at Jackpine, Kearl Lake and Fort Hills, all in northern Alberta, Canada. Each of these installations has included some modifications and improvements upon the base design that suit the operators and situations of the facilities. 
     There continues to be interest in further improvements to the HTPFT process resulting in more cost effective and efficient treatment of froth. 
     SUMMARY 
     Embodiments taught herein improve upon a conventional high temperature paraffinic froth treatment process and vessels for froth separation used therein. The solvent-diluted bitumen from a countercurrent froth separation unit is stabilized against asphaltene precipitation. In a paraffinic solvent recovery unit a first stage of solvent recovery utilizes an unheated flash vessel. Stabilizing is achieved by removal of a portion of the solvent content therein. Removing solvent without heating avoids taking the mixture through a precipitation horizon. The removal of the portion of solvent reduces fouling in downstream stages of solvent recovery. Further, in a unique manner, a heat pump circuit is associated with the first stage of solvent recovery at a first temperature and a second stage of recovery at a higher temperature to provide significant heat integration. The overhead stream from the second heated stage is used to heat the underflow from the first stage as feed to the second stage of solvent recovery. More specifically, the first stage of recovery uses an unheated flash vessel and the second stage uses a heated flash vessel. The overhead solvent vapour stream from the heated flash vessel acts as an intermediate fluid in the heat pump circuit to heat the underflow from the unheated flash vessel. Further, in embodiments, a heat pump is used to heat the froth entering the froth separation unit using heat in a tailings stream from a tailings solvent recovery unit. 
     In embodiments, the froth separation vessels utilize a collector pot in combination with a conventional feedwell, or a collector ring in combination with a nozzle arrangement to reduce disturbance within the vessels for improving separation and collection of overflow therein. 
     In one broad aspect, a high temperature paraffinic process (HTPFT) utilizes a counter-current froth separation unit (FSU) having first and second FSU vessels for separating a paraffinic solvent-diluted froth stream, at an operating temperature from about 60° C. to about 130° C., into first overflow stream from the first FSU vessel, comprising at least partially de-asphalted solvent-diluted bitumen, and an underflow stream from the second FSU vessel, comprising at least solids, precipitated asphaltenes, water and residual paraffinic solvent. A paraffinic solvent recovery unit (PSRU) recovers paraffinic solvent from the first FSU&#39;s overflow stream for reuse in the HTPFT and for recovering a partially de-asphalted bitumen-containing underflow product stream for delivery downstream thereof. A tailings solvent recovery unit (TSRU) comprising at least one TSRU vessel removes at least a portion of residual paraffinic solvent from the underflow stream from the second FSU vessel for producing a solvent-containing overflow stream for reuse in the HTPFT and a tailings underflow stream for disposal. A vapour recovery unit (VRU) separates at least residual paraffinic solvent from overhead streams from the FSU vessels, the PSRU vessels and the TSRU vessels. The process in the PSRU comprises flashing the first overflow stream from the first FSU vessel in an unheated flash vessel for producing a first overhead solvent-containing stream and a first underflow stream, being a partially de-asphalted solvent-diluted bitumen stream, wherein flashing of at least a portion of the paraffinic solvent from the first overflow stream without the addition of heat shifts the solubility of asphaltenes therein for minimizing further de-asphalting thereof downstream in the PSRU. 
     In another broad process aspect, a process of heat integration in a solvent recovery unit having a first flash vessel, operating at a first temperature, and a second flash vessel, operating at a second temperature higher than the first temperature, comprises flashing a solvent-containing feed stream in the first vessel for producing a first overhead solvent vapour stream; and a first underflow stream. The first underflow stream is fed to the second flash vessel. The first underflow is flashed in the second flash vessel for producing a second, overhead solvent vapour stream; and a second underflow stream. The second, overhead solvent vapour stream is passed through a heat pump circuit for heating the first underflow stream prior to feeding the first underflow stream to the second flash vessel, wherein the second, overhead solvent vapour stream acts as an intermediate fluid in the heat pump circuit for exchanging heat therein to the first underflow stream. 
     In yet another broad aspect, a process of heat integration in a paraffinic solvent recovery unit comprises flashing a paraffinic solvent-diluted bitumen feed in a first unheated flash vessel for producing a first overhead solvent vapour stream, comprising at least a portion of the paraffinic solvent; and an underflow stream comprising residual solvent and bitumen therein. The underflow stream is flashed in a second heated flash vessel for recovering a portion of the solvent therein and producing a second overhead solvent vapour stream; and a second underflow stream comprising residual solvent and bitumen therein. The second overhead solvent vapour stream is compressed to force a temperature of condensation therein to be above a bulk evaporation temperature of the first underflow stream. The compressed second overhead solvent vapour stream is condensed against the first underflow stream for heating the first underflow stream therewith prior to feeding the heated underflow stream to the second heated flash vessel. 
     In yet another broad process aspect, a high temperature paraffinic process (HTPFT) utilizes a counter-current froth separation unit (FSU) having first and second FSU vessels for separating a paraffinic solvent diluted froth stream, at an operating temperature from about 60° C. to about 130° C., into a paraffinic solvent-diluted bitumen overflow stream from the first FSU vessel, comprising at least partially de-asphalted bitumen and the paraffinic solvent, and an underflow stream from the second FSU vessel, comprising at least solids, water and residual paraffinic solvent. A paraffinic solvent recovery unit (PSRU) recovers at least a portion of the paraffinic solvent from the paraffinic solvent-diluted bitumen overflow stream for reuse in the HTPFT and a partially de-asphalted bitumen containing product stream for delivery downstream thereof. A tailings solvent recovery unit (TSRU) comprising at least one TSRU vessel removes at least a portion of the residual paraffinic solvent from the underflow stream from the second FSU vessel for producing a solvent containing overflow stream for reuse in the HTPFT and a tailings underflow stream. A vapour recovery unit (VRU) separates at least residual paraffinic solvent from the FSU, the PSRU and the TSRU. The process comprises heating a froth stream for delivery to the first FSU vessel prior to the addition of paraffinic solvent thereto and to the first FSU vessel using a heat pump. 
     In a broad apparatus aspect, a froth separation vessel for a high temperature paraffinic froth treatment process comprises a vessel having a cylindrical portion, a conical bottom and a semispherical top. An inlet pipe extends substantially vertically within a center of the vessel from the top to about a transition between the cylindrical portion and the conical bottom. A feedwell fluidly connects to a bottom of the inlet pipe for delivering paraffinic solvent-diluted bitumen-containing froth to the vessel. A collector pot is supported concentrically about the inlet pipe, at or about a top of a separation zone in the cylindrical portion, for collecting and discharging an overflow stream therefrom. A surge volume is in the cylindrical portion above the separation zone; and an outlet is in the conical bottom for discharging an underflow stream therefrom. 
     In another broad apparatus aspect, a froth separation vessel for a high temperature paraffinic froth treatment process comprises a vessel having a cylindrical portion, a conical bottom and a semispherical top. An inlet pipe extends substantially vertically within a center of the vessel from the top to about a transition between the cylindrical portion and the conical bottom. A nozzle arrangement fluidly connects to a bottom of the inlet pipe for delivering paraffinic solvent-diluted bitumen-containing froth to the vessel. A collector ring is supported toroidally about the inlet pipe, at or about a top of a separation zone in the cylindrical portion, for collecting and discharging an overflow stream therefrom. A surge volume is in the cylindrical portion above the separation zone; and an outlet is in the conical bottom for discharging an underflow stream therefrom. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application with color drawing(s) will be provided by the Office upon request and payment of the necessary fee. 
         FIG. 1  is a schematic flowsheet illustrating a prior art, high temperature, paraffinic froth separation circuit according to Canadian Patent 2,454,942; 
         FIGS. 2A to 2E  are process flow diagrams of a high temperature, paraffinic froth treatment (HTPFT) process according to embodiments taught herein, more particularly, 
         FIG. 2A  is a process diagram of the overall HTPFT according to embodiments taught herein; 
         FIG. 2B  is a process flow diagram of the froth separation unit (FSU) of the HTPFT according to  FIG. 2A ; 
         FIG. 2C  is a process flow diagram of the paraffinic solvent recovery unit (PSRU) of the HTPFT according to  FIG. 2A ; 
         FIG. 2D  is a process flow diagram of the tailings solvent recovery unit (TSRU) of the HTPFT according to  FIG. 2A ; and 
         FIG. 2E  is a process flow diagram of the vapor recovery unit (VRU) of the HTPFT according to  FIG. 2A ; 
         FIGS. 3A to 3E  are process flow diagrams of a high temperature, paraffinic froth treatment process according to alternate embodiments taught herein, more particularly, 
         FIG. 3A  is a process diagram of the overall HTPFT according to embodiments taught herein; 
         FIG. 3B  is a process flow diagram of the froth separation unit (FSU) of the HTPFT according to  FIG. 3A ; 
         FIG. 3C  is a process flow diagram of the paraffinic solvent recovery unit (PSRU) of the HTPFT according to  FIG. 3A ; 
         FIG. 3D  is a process flow diagram of the tailings solvent recovery unit (TSRU) of the HTPFT according to  FIG. 3A ; and 
         FIG. 3E  is a process flow diagram of the vapor recovery unit (VRU) of the HTPFT according to  FIG. 3A ; 
         FIG. 4  is a cross sectional view of a conventional double pipe heat exchanger and steam injection for heating froth; 
         FIG. 5  is a schematic illustrating an embodiment taught herein for heating froth using a heat pump; 
         FIG. 6A  is cross-sectional view of a froth separation vessel according to an embodiment taught herein having a separation zone of 1.2 times the vessel diameter in height and a feed nozzle arrangement therein; 
         FIG. 6B  is a cross-section view along section lines A-A according to  FIG. 6A  illustrating the feed nozzle arrangement and, in particular, opposing nozzles and flow therefrom acting to minimize disturbance in the feed introduced to the vessel; 
         FIG. 6C  is a cross-sectional view of the froth separation vessel according to  FIG. 6A  and having a collector ring located therein for collecting and discharging a solvent/bitumen containing stream therefrom; 
         FIG. 6D  is a cross-sectional view of a bottom surface of the collector ring of  FIG. 6C , sectioned along lines A-A; 
         FIG. 7  is a cross-sectional view of a froth separation vessel having a conventional feedwell and a collector pot located therein for collecting and discharging a solvent/bitumen-containing stream therefrom; 
         FIGS. 8A and 8B  are computational fluid dynamic (CFD) simulations of froth feed flow in a vessel having the feed nozzle arrangement and collector ring as shown in  FIG. 6C ; 
         FIGS. 9A and 9B  are computational fluid dynamic (CFD) simulations of froth feed flow in a vessel having the conventional feed arrangement and collector pot as shown in  FIG. 7 ; 
         FIG. 10  is a cross-sectional view of a froth separation vessel having extra volume above an overflow collector located therein; 
         FIG. 11  is a cross-sectional view of a froth separation vessel comprising segregated wear and pressure envelopes therein; 
         FIG. 12  is a cross sectional view of each of the wear envelope and the pressure envelope according to  FIG. 11 ; 
         FIG. 13  is a cross-sectional view of a two stage FSU vessel comprising first and second stages within a single footprint, or a paired set of FSU vessels having double area within a smaller diameter pressure vessel; 
         FIG. 14  is a schematic of an embodiment taught herein having one or more hydrocyclones or a cyclopack as the second stage of the froth treatment circuit; 
         FIG. 15  is a schematic illustrating an embodiment having an IR analyzer and other conventional measurements for monitoring the overhead stream from the second stage FSU to the first FSU; 
         FIG. 16  is a compatibility diagram illustrating the effect of temperature on asphaltene solubility in various n-pentane-to-bitumen ratios by volume; and 
         FIG. 17  is an enthalpic step chart for the overhead feed heat exchange from the heated flash vessel according to the embodiment shown in  FIG. 2C . 
     
    
    
     DESCRIPTION 
     Prior Art 
     Applicant&#39;s high temperature paraffinic froth treatment process (HTPFT) is based on a similar process and process flow diagram as in the HTPFT process outlined in Canadian Patent 2,454,942 and shown in prior art  FIG. 1 , relabeled in accordance with embodiments taught herein. The first stage of the HTPFT is a counter-current solvent extraction and separation, which uses the incompatibility of asphaltenes in the bitumen with paraffinic solvents to achieve partial solvent de-asphalting of the bitumen, coalescence/settling of the water and agglomeration of the mineral separated in a counter-current manner through the first and second separation vessels  14 ,  16 . In the two-stage countercurrent separation system, the first froth separation vessel  14  receives the froth  10  combined with an overflow stream  18  from the second vessel  16 , containing at least solvent-diluted bitumen. The underflow from the first FSU vessel  14  provides the feed to the second FSU vessel  16 . Overflow from the first FSU vessel  14  comprises at least bitumen and solvent and the underflow  36  from the second FSU vessel  16  comprises solids, precipitated asphaltenes, water and residual solvent, all of which are subject to downstream processing. 
     Improvements to the prior art process, from a performance, economic and/or risk perspective, are described herein with reference to embodiments of the process shown in  FIGS. 2A to 2E and 3A to 3E . 
     Generally, with reference to  FIGS. 2A and 3A , which illustrate two different embodiments, the HTPFT process disclosed herein provides a Froth Separation Unit (FSU), a Paraffinic Solvent Recovery Unit (PSRU), a Tailings Solvent Recovery Unit (TSRU), and a Vapour Recovery Unit (VRU).  FIGS. 2B-2E and 3B-3E  are expanded drawings of the FSU, PSRU, TSRU and VRU, respectively, of  FIGS. 2A and 3A . 
     With reference to  FIGS. 2B and 3B , relative to embodiments of the FSU, froth  10  produced in an extraction and primary separation stage, is typically stored in a froth tank  12  and is pumped therefrom into the high temperature paraffinic froth treatment (HTPFT) processes described herein. Because HTPFT processes are generally more effective at removal of water and minerals than lower temperature froth treatment, froth  10  used in embodiments taught herein can be lean, having a lower amount of bitumen therein, typically less than 40%, and a higher amount of water and mineral, without materially affecting the facility product quality. HTPFT can be used to treat lean froth  10  having bitumen content between about 31% to about 55% bitumen, typically sourced from flotation froth, cyclonic extraction froth, or mechanical separation froth. 
     The stream of froth  10  is combined, as taught below, at high temperature with a paraffinic solvent, which in embodiments taught herein is a combination of n-pentane and iso-pentane, with trace amounts of butane, hexane and diesel fraction components, at temperatures in the range of from about 60° C. to about 130° C. and, more particularly, at about 90° C. 
     In embodiments, as shown in  FIG. 1 , the FSU is a two stage counter-current solvent extraction system utilizing a first froth separation vessel  14  and a second froth separation vessel  16 , as taught in Canadian Patent 2,454,942 and described above. In embodiments, the first and second separation vessels  14 , 16  are gravity separation units or vessels. 
     Fresh and/or recycled paraffinic solvent  20  is added either to the second FSU vessel&#39;s overflow stream  18  or into the second FSU vessel  16 , which receives an underflow stream  22  from the first FSU vessel  14 . In embodiments taught herein, the first FSU vessel  14  produces an overflow stream  24 , which comprises largely paraffinic solvent and product bitumen. In embodiments, a target, solvent-to-bitumen ratio, for the solvent mixture as described above, in the first separation vessel&#39;s overflow stream  24  is about 1.8 by mass. Vapor or gas, produced as an overhead stream  28  from the first and second separation vessels  14 , 16  is directed to the VRU (Stream G). Should the aromaticity of the solvent mixture increase, such as resulting from the presence of aromatic contaminants, the S:B ratio is adjusted accordingly. 
     In embodiments, gas  17 , such as natural gas NG, nitrogen N 2 , or other inert gas, is added to the first and second FSU vessels  14 ,  16 , operated at pressures of about 700 KPa(a), to ensure gases below an upper explosive composition limit are not present therein to minimize the risk of fire and/or explosion. 
     With reference to  FIGS. 2C and 3C , relative to embodiments of the PSRU, the first FSU vessel&#39;s overflow stream  24 , containing largely bitumen and solvent, is delivered to the PSRU (Stream A), which is used to recover the paraffinic solvent  20  from the overflow stream  24 . Once the paraffinic solvent  20  is removed, the remaining product bitumen  26  is delivered downstream of the HTPFT for further refining. 
     In embodiments, the product bitumen  26  is cooled and blended with a stream of naphtha  30  prior to storage and/or transport. Blending with naphtha  30  makes the cooled, stored, blended bitumen product  26  less viscous and easier to handle. In embodiments, the blending is typically done at a dilution of about 5% with naphtha  30 . In embodiments, additional naphtha and butane  31  can also be added to the bitumen/naptha stream for downstream delivery. 
     The paraffinic solvent  20  recovered in the PSRU is delivered to solvent storage  32  (Stream B), whereupon it is typically recycled back into the FSU (Stream C, D). Water  34  recovered in the PSRU (Stream I) is recycled to within the HTPFT, such as to an underflow or tailings stream  36  (Stream E) from the second froth separation vessel  16  ( FIGS. 2B and 3B ). Vapor produced in the first stage of solvent recovery in the PSRU (Stream H) is delivered to the VRU. 
     With reference to  FIGS. 2D and 3D , relative to embodiments of the TSRU, the underflow or tailings stream  36  from the second froth separation vessel  16  comprises largely minerals/fine solids (less than about 44p), precipitated asphaltenes, water and residual solvent. The tailings stream  36  is directed to the TSRU (Stream E) for recovery of the residual paraffinic solvent  20  therefrom. In embodiments, the TSRU comprises first and second TSRU vessels  38 ,  40 , operated in series. The tailings stream  36  from the second froth separation vessel  16  is delivered to the first TSRU vessel  38 . An underflow  302  from the first TSRU vessel  38  is delivered to the second TSRU vessel  40 . A solvent-containing overhead  300 , 306 , produced from the first and second TSRU vessels  38 , 40 , is ultimately processed and the solvent  20  delivered to the solvent storage  32  for recycling in the HTPFT. A solvent-depleted tailings stream  46 , produced as an underflow stream from the second TSRU vessel  40 , is ultimately sent to disposal  47  (Stream J). Vapor produced by the TSRU is directed to the VRU (Stream F) for solvent recovery. 
     With reference to  FIGS. 2E and 3E , relative to embodiments of the VRU, residual solvent vapors produced from the FSU (Stream G), TSRU (Stream F) and PSRU (Stream H) are condensed and delivered to the solvent surge and storage system  32  for recycling to the FSU (Stream C). Residual vapors that are not condensed are generally recycled for use as fuel gas FG in boilers of the HTPFT system. 
     Having provided a general overview of the HTPFT process, specific embodiments will now be discussed. IN the HTPFT process, froth  10  may be heated before it is delivered to the first FSU  14 . 
     In an embodiment, best seen in  FIG. 2B , prior to heating and the addition of paraffinic solvent  20  to the froth  10  to produce a solvent-diluted froth  11 , which is being pumped using one or more pumps  50  from a froth source, typically the froth tank  12 , the froth  10  is pushed through an inline grinder  52  to positively size solids therein. The solids, which may include environmental materials and contaminants that may have accidentally entered the froth  10 , are ground to less than about ⅜″. The froth  10  is passed through the inline grinder  52  prior to the addition of the paraffinic solvent  20 , rather than after, to simplify seal arrangements and maintenance in downstream apparatus. More particularly, the grinder  52  is located upstream of one or more first heating apparatus  54  used to increase the temperature of the froth  10  to avoid fouling and flow problems therethrough. The one or more first heating apparatus  54 , are used to ensure the froth  10  is heated sufficiently to be at the process temperature of between about 60° C. to about 130° C. in the first FSU vessel  14 . In embodiments, the process temperature in both the first and second FSU vessels  14 , 16  is about 90° C. 
     In an embodiment, the one or more first heating apparatus  54  are used to heat the froth  10  by exchanging heat from the second TSRU underflow tailings stream  46  (Stream J) to the froth  10 , prior to the addition of the paraffinic solvent  20 . The process of exchanging heat from the tailings stream  46  to the froth  10  can be achieved using different types of heat exchange apparatus  54 , including, but not limited to, double pipe heat exchangers, spiral plate exchangers, and heat pumps. 
     As shown in  FIG. 4 , in a conventional double pipe heat exchanger  56  the tailings stream  46  is pumped through an inner pipe  58 , extending through a larger diameter outer pipe  60 , to minimize high wear surface areas therein. Froth  10  is pumped in an opposing direction through the outside pipe  60  and heat is exchanged from the tailings  46  to the froth  10  through a wall  62  of the inner pipe  58 . The double pipe heat exchanger  56  may extend from a point at which the froth  10  is first pumped from the froth tank  12  to a point at which the froth  10  is trim heated, such as using steam as described below, prior to the froth  10  entering the FSU. 
     Alternatively, heat exchange can be done using a spiral plate heat exchanger. In embodiments, to properly match the velocities, gaps and materials, embodiments of a special format of spiral plate heat exchanger are used as described in Applicant&#39;s Canadian Patent Application 2,969,595, the entirety of which is incorporated herein by reference. 
     Both the conventional double pipe heat exchanger  56  and the spiral heat exchanger taught in CA  2 , 969 , 595  require further downstream trim heating for proper final froth temperature and control. For this trim heating, two options of a trim heater  64  are conventional. In a first option, the froth  10  is further heated using direct injection steam heating, such as described in the U.S. Pat. No. 8,685,210 to Suncor Energy Inc. or using direct steam injection heating using a sonic injector, such as using a Hydroqual™ unit available from Hydro-Thermal Corp. 
     As shown in  FIG. 5 , in an embodiment, as an alternative to challenges in the use of the previously described heat exchanger options, which result from a tight temperature approach, fluids with particulates therein, high viscosity and multiple phases on both sides of the heat exchanger, a heat pump  66  is used to drive heat from the tailings stream  46  into the froth  10 . The heat pump  66  utilizes an intermediate fluid  68 , such as hexane, cyclohexane, ethyl amine or heptane, as a refrigerant, evaporating against the tailings stream  46 , such as in a first spiral plate heat exchanger  70 . The intermediate fluid  68  is then compressed to increase the sensible temperature therein and is then condensed against the froth  10 , such as in a second spiral plate heat exchanger  72 . Use of the heat pump  66  provides some advantages. The intermediate fluid  68  simplifies the exchanger designs as there is only one difficult fluid, being either the tailings stream  46  or the froth  10 , in each of the first and second spiral plate heat exchanger  70 , 72 . The heat pump  66  allows for increased use of the heat in the tailings stream  46  by removing temperature pinch constraint. Further, the heat pump  66  can be optimized for capital expenditure on the heat pump  66  and the spiral exchangers  70 , 72 , based on customizing an approach temperature, which is the minimum allowable temperature difference in the temperature profiles for the froth  10  and the tailings stream  46 . As one of skill will appreciate, the cost of the heat pump, which is driven by the temperature shift that is generated wherein the higher the temperature difference the higher the cost, is balanced by the savings achieved in the heat exchangers, which are driven by the temperature approach wherein the greater the temperature difference the lower the cost. 
     Use of the heat pump  66  is advantageous as the heat pump  66  is better able to control the temperature of the froth  10 , compared to direct heat exchange. Further, any extra sensible heat, likely to be in the intermediate exchange fluid  68  following heating of the froth  10 , can potentially be rejected to the incoming solvent  20  with use of a simple heat exchanger. A further advantage, resulting as a byproduct of removing any additional sensible heat, is the further cooling of the tailings stream  46 , ensuring that any remaining volatile material therein is no longer volatile, thereby reducing fire and odour hazards. 
     As shown in  FIG. 3B , in another embodiment, the froth  10  is heated via the addition of the overflow stream  18  from the second FSU vessel  16 . The overflow stream  18  is further heated in a heat exchanger  74  using a hot condensate stream  76  produced in the PSRU, as described in greater detail below. Trim heating, using a steam heat exchanger  78 , is added to the overflow stream  18  prior to being combined with the froth  10  entering the first FSU vessel  14 , as required. Further, additional solvent  20 , as required in the first FSU vessel  14  to achieve the first FSU overflow stream&#39;s S:B ratio of 1.8, is also heated in a heat exchanger  80  ( FIG. 3C ) using residual heat generated in the PSRU, as discussed in greater detail below; 
     FSU 
     Best seen in  FIGS. 2B and 3B , the heated froth  10 , is pumped to the FSU such as from the froth tank  12 . As previously described with respect to prior art Canadian Patent 2,750,995, the froth separation circuit FSU is a two stage counter-current solvent extraction that uses the incompatibility of the asphaltenes with paraffinic solvents to achieve partial solvent deasphalting of the bitumen, coalescence/settling of the water and agglomeration of the mineral. In embodiments, the first and second stage froth separation units  14 ,  16  are operated from about 60° C. to about 130° C. 
     In the embodiments, the FSU circuit is operated at, or about, 90° C. in both a first and second stage FSU vessels  16 ,  18 . Operation is centered on the S:B ratio of about 1.8 by mass in the first FSU vessel&#39;s solvent-diluted bitumen overflow stream  24 . The S:B ratio can be varied to increase or decrease the amount of asphaltene retained or rejected as appropriate to the feed quality, final bitumen viscosity, flux rate required in the FSU vessels  14 ,  16  and agglomeration requirements. Such adjustments are made under the guidance of one skilled in the art to accommodate a variety of froth and solvent qualities. 
     Large scale conventional FSU vessels are hydraulically turbulent, unless filled with partitions which bring down the specific length. In embodiments taught herein, having reference to  FIGS. 6A to 14 , improvements to the conventional FSU circuit taught herein are generally related to modifications to the feed apparatus, to the separation vessel design or both. 
     In an embodiment, having reference to  FIGS. 6A to 6D , the FSU vessels  14 ,  16  are designed to have a separation zone  82  within the FSU vessel  14 , 16  of about 1.2 times the vessel diameter in height. The increased vertical height accommodates the turbulence and minimizes or prevents single eddy short circuiting therein, which would otherwise decrease effective gravity separation. A height  87  of a semispherical volume  81  at a top  83  of the vessel  14 ,  16  is about 0.5 times the diameter of the vessel  14 , 16 . 
     In a further embodiment, also shown in  FIGS. 6A-6D , a feed nozzle arrangement  84  acts to further minimize disturbance within the FSU vessels  14 ,  16 . The nozzle arrangement  84  comprises six nozzles  86 , positioned in the FSU vessel  14 , 16  adjacent a transition  88  from a conical bottom portion  90  therein to an upper cylindrical portion  92 . In an embodiment, the nozzles  86  are fluidly connected to a vertically extending inlet pipe  94 , such as by downwardly and radially outwardly extending feed pipes  96 , which symmetrically locate the nozzles  86  about a circumference of the FSU vessels  14 ,  16  and adjacent an outer wall  98  thereof. In an embodiment, the feed pipes are angled downwardly at about 135° relative to the inlet pipe  94 . In an embodiment having the six nozzles  86 , the nozzles  86  are arranged in three groups, each group having two opposing nozzles  86 , angled so as to create a flow of solvent-diluted froth  11  therefrom that opposes the flow of solvent-diluted froth  11  from an adjacent nozzle  86  in an adjacent group of the other two groups of opposing nozzles  86 . All of the nozzles  86  deliver the solvent-diluted froth  11  in the same horizontal entry plane. In an embodiment each of the groups of nozzles  86  are spaced circumferentially at about 120° apart. The nozzles  86  are sized to a low Richardson number, to help fully spread the solvent-diluted froth  11  through the horizontal entry plane. In embodiments, the opposing direction of the nozzles  86  acts to cancel or minimize the momentum and maximize energy dispersion in the incoming solvent-diluted froth  11 , reducing large eddies within the FSU vessels  14 , 16 , as the feed is not directed at the walls of the vessel  14 , 16 . Alternatively, a feed nozzle arrangement, such as taught in Canadian Patent application 2,867,446 to Total E&amp;P Canada Ltd., can be used. 
     A conventional FSU vessel typically comprises a launder for collection of solvent/bitumen-containing fluids, which have separated therein and have floated to a top of the FSU vessel. Launders require violent flow to remain clear of buildup and therefore are only suitable where there is sufficient violent action within the FSU vessel to ensure there is no standing liquid level on the launders side of a launder lip. 
     Having reference to  FIGS. 6C and 6D , in use the FSU vessels of  FIGS. 6A and 6B , further comprise a collector ring  85 . Best seen in  FIG. 6D , the collector ring  85  is a toroidally-mounted pipe having a plurality of inlet apertures  91  distributed at regular intervals along a bottom surface  93  thereof. The collector ring  85  acts to collect the solvent-diluted bitumen, forming overflow streams  18 , 24 , as evenly as possible from a plane at a top  89  of the separation zone  82  for discharge from a discharge conduit  108 , fluidly connected thereto. 
     In a further embodiment, as shown in  FIG. 7 , a collector pot  100  is suspended within the separation zone  82  in the cylindrical portion  92 , above a conventional feedwell  102 , such as used by Albian Sands Energy Inc. in the Athabasca Oil Sands Projects in Northern Alberta, Canada. In embodiments, the collector pot  100  is suspended about the inlet pipe  94 . The feedwell  102 , fluidly connected to the inlet pipe  94 , is located at about the transition  88 . The collector pot  100  comprises a cylindrical collection chamber  103  having a closed top  104 , an open bottom  106  and the discharge conduit  108  fluidly connected from the collection chamber  103  to discharge outside the FSU vessel  14 , 16 . Means for liquid level control, such as a level instrument and a valve, maintain a normal operating liquid level NLL within the FSU vessel  14 , 16  at or above the top  104  of the collector pot  100 . Sufficient height of the cylindrical portion  92  allows for a high liquid level HLL or surge volume  105  thereabove. Such an arrangement eliminates the conventional launder and the need for an additional overflow surge vessel. 
       FIGS. 8A and 8B  are computational fluid dynamic simulations (CFD) of the nozzle arrangement  84  of  FIGS. 6A and 6B , in combination with the collector ring  85  as shown in  FIG. 6C . 
       FIGS. 9A and 9B  are computational fluid dynamics simulations (CFD) of the collector pot  100  and feedwell  102  arrangement of  FIG. 7 . The conventional feedwell  102  produces a low disturbance in the vessel  14 , 16 , however high velocities remain at the wall. By collecting the solvent-diluted bitumen, forming overflow streams  18 , 24 , in the collector pot  100  near a center of the vessel  14 , 16 , the fluid rising along the wall must move horizontally before exiting, dramatically reducing upward velocity. 
     Applicant believes that while both embodiments of feed delivery discussed above show a similar performance, the nozzle arrangement  84  and collector ring  85  embodiment of  FIG. 6C  is more efficient, while the collector pot  100  and conventional feedwell  102  arrangement of  FIG. 7  is more robust. 
     Having reference to  FIG. 10 , in another embodiment a further alternative to the conventional FSU vessel is a separation vessel  14 , 16  comprising an additional retention volume R above an overflow collector, such as a collector pot  100  as shown in  FIG. 7  or a collector ring  85  as shown in  FIG. 6C  allowing for control of the flow from the separation vessel  14 , 16  to downstream equipment. Further, the additional retention volume R accommodates a surge volume  105  therein thereby eliminating the need for a separate surge vessel and without impacting the height of the separation zone  82  in the vessel  14 , 16 . Use of the retention volume R in the FSU vessels is particularly valuable for smaller treatment plants where the FSU vessels  14 , 16  can be shop fabricated. 
     As shown in  FIGS. 11 and 12 , in yet another embodiment of the vessel  14 , 16 , the FSU vessel  14 , 16  comprises a segregated wear envelope  110  and pressure envelope  112 . The vessel  14 , 16  provides an equivalent surge volume  105  to that of a vessel having integrated wear and pressure envelopes  110 , 112 . The segregation is achieved by mounting the wear envelope  110 , which is non-pressure retaining, and a liquid or hydraulic envelope  114 , inside a conventional pressure bullet or envelope  112 . This embodiment has the advantage of easily allowing different materials to be used for the wear and pressure management surfaces, reducing the need to include wear thickness in the pressure envelope  112 , and reducing the likelihood of an atmospheric release due to wear failure. In the embodiment as shown, should a wear failure occur despite use of the wear envelope  110 , material would be released to within the segregated pressure envelope  112 , where it is contained. The space  116  below the wear envelope  110  provides the surge volume  105 . 
     As shown in  FIG. 12 , the wear envelope  110  may comprise a thicker wear material  111  at the conical bottom portion  90  of the vessel  14 , 16  and a thinner barrier material  113  thereabove in the cylindrical portion  92  of the vessel  14 , 16  for containing the hydraulic envelope  114  therein. 
     A person skilled in the art can select an appropriate design or mixture of designs from the above described improvements to the separation vessels  14 , 16  to suit the operational, capital, maintenance and other considerations as these aspects are unique to each feed material, operator and project. 
     In a further option, as shown in  FIG. 13 , multiple wear envelopes  110 , in vertical series, can be used to either increase the equivalent cross-sectional area of the froth separation vessel  14 , 16  or can be used to combine the two stages of separation vessels  14 , 16  into a single pressure envelope  112 . 
     In the embodiment shown, the first stage FSU vessel  14  formed by a first wear envelope  118  is located in a top portion  120  of the pressure envelope  112 , while the second stage FSU vessel  16 , formed by a second wear envelope  122  is located in a bottom portion  124  of the pressure envelope  112 . The pressure envelope  112  further comprises a divider  126  between the first and second wear envelopes  118 ,  122  forming an upper storage zone  128  for the solvent-diluted bitumen overflow stream  24  from the first FSU vessel  14  and a lower storage zone  130  for the solvent-diluted bitumen overflow stream  18  from the second FSU vessel  16 . The overflow streams  24 ,  18  are delivered from the storage zones  128 , 130  through upper and lower outlets  132 , 134 . Pressure equalization lines  136  are provided between each storage zone  128 ,  130  and the top portion  120  of the pressure envelope  112  as well as between a space  138  below the divider  126  and the top portion of the pressure envelope  112 . Tailings are released from a bottom  140 , 142  of each wear envelope  118 ,  122  through tailings outlets  144 , 146 . 
     To operate in a counter-current manner, the overflow stream  18  from the second vessel  16  is fed to the first vessel  14  and the overflow stream  24  is fed to the PSRU, as previously discussed. The tailings are also discharged to the TSRU for solvent recovery as discussed below. 
     In an embodiment, as shown in  FIG. 14 , the froth separation vessels  14 ,  16  comprise the first FSU vessel and one or more hydrocyclones  150  for the second stage of separation. Substitution of the one or more hydrocyclones  150  for the second FSU vessel  16  can be effectively used to great benefit in the case of the second stage of separation. The second stage is primarily tasked with scavenging maltene, which is the non-asphaltene fraction of bitumen, remaining in the gangue material after the first stage of separation and does not produce a final product. Therefore, the sensitivity is skewed to recovery rather than quality of product. Hydrocyclones can be very effective in this service as there is a g-force advantage in gaining recovery, such as compression of agglomerate pore space. In embodiments incorporating one or more second stage hydrocyclones  150 , any segregation challenges encountered using the one or more hydrocyclones  150  are mitigated by interface-controlled separation in the first stage FSU vessel  14 . 
     The one or more hydrocyclones  150  may comprise two or more hydrocyclones  150 , typically grouped symmetrically in a cyclopack, having an integrated overflow and underflow. 
     In embodiments, an infrared (IR) analyzer  152  is used to aid in solvent management by assessing the quality of the solvent  20  being blended with the fresh froth  10  so that the dosage of the solvent  20  can be adjusted accordingly, by one skilled in the art familiar with the corrections required to the dosage based on solvent aromaticity, average molecular weight, water content and the like. 
     In embodiments, as shown in  FIG. 15 , the IR analyzer  152  scans the second FSU vessel&#39;s overflow stream  18 , referred to in this context as intermediate solvent, as the overflow stream  18  is pumped between the second FSU vessel  16  and the first FSU vessel  16 . IR analysis of the intermediate solvent  18  is used, together with other online analysis, such as density (D) and water content (W), to adjust the S:B ratio entering the first FSU vessel  14  so as to achieve the S:B ratio at about 1.8 in the first vessel&#39;s solvent-diluted bitumen overflow stream  24  and consistent product quality. 
     The overhead stream  24  from the first froth separation vessel  14 , containing largely the solvent  20  and product bitumen  26 , is fed to the PSRU (Stream A). 
     PSRU 
     With reference to  FIGS. 2C and 3C , the first separation vessel&#39;s overflow stream or partially de-asphalted, solvent-diluted bitumen  24  (Stream A) is fed from the FSU into the PSRU. As shown in  FIGS. 2C and 3C , the first stage of solvent recovery of the PSRU incorporates a flash valve  208  and an unheated flash vessel  210 . In embodiments, the solvent-diluted bitumen  24 , being at about 90° C. and having an S:B ratio of about 1.8, is at an asphaltene saturation point as it enters the PSRU. The solvent-diluted bitumen  24  passes through flash valve  208  and exits to the unheated flash vessel  210 , which has a pressure lower than the solvent-diluted bitumen  24 , causing the solvent-diluted bitumen  24  to flash without the addition of heat. 
     Having reference to  FIG. 16 , by allowing the solvent-diluted bitumen  24  to flash without heating, the solvent recovery process is improved as the removal of at least a portion of the solvent moves the solubility parameters away from the compatibility limit thereby minimizing continued asphaltene precipitation and fouling of the solvent recovery apparatus in subsequent stages. In other words, flashing the solvent-diluted bitumen without actively increasing the temperature allows at least some of the solvent  20  to separate so that the change in S:B ratio does not promote further asphaltene precipitation in the subsequent heated stages. The temperature of the outgoing liquid  24 S is also reduced sufficiently so that the underflow from the unheated flash vessel  210  can act as a fluid for condensing the overhead vapours from a subsequent, second stage heated flash, which will be described in more detail hereinbelow. Embodiments of the PSRU as taught herein allow for a significant heat integration and economy of energy. 
     Approximately 25-30% of the solvent  20  is removed from the solvent-diluted bitumen stream  24  in the first stage of flashing. In embodiments, as shown for example in  FIG. 2C , the PSRU includes an overhead separator  212  to separate the net solvent vapour  20 V from the condensed solvent  20 . The separated net vapour  20 V is fed to the VRU (Stream H) while the condensed solvent  20  is sent to the solvent storage  32  (Stream B). 
     In other embodiments, as shown for example in  FIG. 3C , the overhead solvent vapour  20 V from the unheated flash vessel  210  passes through a Joule-Thomson valve  440  in the VRU ( FIG. 3E ) for cooling (Stream H). 
     The second stage of the solvent recovery unit is the heated flash. With further reference to  FIGS. 2C and 3C , an underflow stream  24 S from the unheated flash vessel  210 , which comprises the remaining solvent-diluted bitumen  24 , exits the unheated flash vessel  210  and is heated prior to entering a heated flash column  220 . The heating is accomplished by condensing an overhead solvent vapour stream  20 V from the heated flash column  220  against the unheated flash underflow  24 S via a heat exchange apparatus  216 , followed by heat integration with the underflow product bitumen stream  26  from a subsequent, downstream steam stripping column  240  via a heat exchange apparatus  218 . 
     In some embodiments, as shown for example in  FIG. 3C , the unheated flash underflow  24 S may be strained by a strainer  214  before being heated and may be steam trimmed to a desired temperature by a trim heater  222  prior to entering the heated flash column  220 . In some embodiments, the feed (i.e. the unheated flash underflow  24 S) entering column  220  is at about 172° C. and about 1200 kPaa. The second stage heated flash column  220  flashes an additional about 60-67% of the original solvent  20  from the feed  24 S. 
     With reference to  FIGS. 2C, 3C and 17 , to permit the heat integration, the process matches overhead condensation energy from the heated flash column  220  to some sensible heat and evaporation energy on the unheated flash underflow  24 S to the heated flash column  220 . In other words, the evaporation of the unheated flash underflow  24 S is balanced with the condensation of the overhead solvent vapour stream  20 V from heated flash column  220 . In some embodiments, this is achieved by compressing the overhead solvent vapour stream  20 V from heated flash column  220  using, for example, an integration compressor  224  (shown in  FIG. 2C ), to force the temperature of condensation to be above the bulk evaporation temperature of the column feed (i.e. the unheated flash underflow  24 S). In the condensation step, the overhead solvent vapour stream  20 V from the heated flash column  220  acts as a “refrigerant” to heat the unheated flash underflow  24 S, which is the feed to the heated flash column  220 . The result is removal of a temperature pinch and the exchange of roughly 12 times the energy that the compressor  224  consumes (heat pump circuit). In the embodiment shown in  FIG. 3C , by adjusting the conditions in the heated flash, some form of heat integration can still be achieved (i.e. the solvent stream  20 V acts as a heating medium to heat the underflow  24 S) without the use of a compressor. 
     In some embodiments, as shown in  FIG. 2C , after passing through heat exchanger  216 , the overhead solvent vapour  20 V from the heated flash vessel  220  is substantially completely condensed and is delivered to a separator  226 . The separator  226  acts as a surge vessel and separates incondensible gases (e.g. N 2 ) from the solvent feed stream  20 V. The resulting condensed solvent  20  from the separator  226  is then sent to solvent storage  32  (Stream B). In alternative embodiments, as shown for example in  FIG. 3C , some or all of the overhead solvent vapour stream  20 V exiting heat exchanger  216  is sent to a hot condensate storage  230  for subsequent delivery as the hot condensate stream  76  to the FSU (Stream D) for use in heat exchanger  74  for heating solvent  20  delivered thereto ( FIG. 3B ). 
     With reference to both  FIGS. 2C and 3C , the underflow  24 H from the heated flash vessel  220  are delivered to the stripping column  240  to recover the remaining solvent  20  in the third and final stage of the PSRU. The third stage aims to recover the remainder (about 8%) of the original solvent  20 . The feed (i.e. the heated flash underflow  24 H) to stripping column  240  is heated by heat integration with the underflow product bitumen stream  26  of the stripping column  240  and also with either a steam heater or a furnace. 
     In the embodiments shown in  FIGS. 2C and 3C , prior to entering the stripping column  240 , the heated flash underflow  24 H is first heated by heat integration with the underflow product bitumen stream  26  from the stripping column  240  via a heat exchange apparatus  232 . The preheated, heated flash underflow stream  24 H exiting the heat exchanger  232  is then trimmed with steam to a desired temperature by a trim heater  234 , prior to being delivered as feed to the stripping column  240 . In a sample embodiment, the feed  24 H immediately prior to entering the stripping column  240  is at about 230° C. and about 270 kPaa. The stripping column  240  is operated at around 270 kPaa, with solvent reflux to a top portion and the addition of the stripping steam to a bottom portion. 
     The temperature of the underflow product bitumen stream  26  upon exiting the stripping column  240 , is from about 230° C. to about 250° C. The underflow product bitumen stream  26  is cooled by heat integration with the stripping column feed (i.e. the heated flash underflow  24 H at heat exchange apparatus  232 , the heated flash vessel feed (i.e. the unheated flash underflow  24 S) at heat exchange apparatus  218 , and a return solvent feed  20  at a heat exchanger  242 , respectively. In the illustrated embodiments, the return solvent feed for use in heat exchanger  242  is from the solvent storage  32  (Stream C). After cooling, the underflow product bitumen stream  26 , is blended with cool naphtha  30  and mixed using a static mixer  244 . In a sample embodiment, the bitumen-naphtha mixture is at about 100° C. In a further embodiment, the naphtha is hydrotreated naphtha. 
     The bitumen-naphtha mixture is then trim cooled by a water cooler  246  prior to being delivered to a storage tank  248 . In one embodiment, the bitumen-naphtha mixture is cooled to about 45° C. or lower for storage. Blending the bitumen with naphtha prior to storage makes the stored bitumen product more robust for handling and transportation. In embodiments, the blending is done at a dilution of about 5% with naphtha. In embodiments, butane  31  and additional naphtha  30  may be subsequently added to the bitumen-naphtha mixture for ease of transport from storage tank  248 . 
     Overheads from the PSRU are condensed against cooling water, the feed to the heated flash vessel, and cooling water for the unheated flash, the heated flash, and the stripping column, respectively. The overhead solvent vapour stream  20 V from the stripping column  240  is substantially completely condensed and may be tuned to a desired temperature by a trim heater or heat exchange apparatus  256  prior to being delivered to a separator  258  whereby water  34  in the overhead solvent vapour stream  20 V is separated from the solvent  20 . The separated water  34  is sent to the TSRU (Stream I) for mixing with the tailings stream  36  from separation vessel  16 . The separated solvent  20  from the separator  258  is divided into a reflux stream  20 F and a solvent return stream  20 R. The reflux stream  20 F is fed back into the top portion of stripping column  240  and the solvent return stream  20 R is sent to the solvent storage  32  (Stream B). In some embodiments, the ratio of the reflux stream  20 F to the solvent return stream  20 R is about 0.7:1. 
     In an embodiment, as shown for example in  FIGS. 2C and 3C , at least some solvent from solvent storage  32  (Stream C) is reheated against waste heat from the underflow bitumen product stream  26  from the stripping column  240  by heat exchanger  242  and, after exiting heat exchanger  242 , the heated solvent  20  is further trim heated against steam to a desired temperature by a trim heater or heat exchange apparatus  80  prior to being delivered to the FSU (Stream C) for mixing with the underflow stream  22  from the first froth separation vessel  14  (as shown for example in  FIG. 2B ) and/or for mixing with froth  10  as feed to the first froth separation vessel  14 , as shown for example in  FIG. 3B . 
     In an alternative embodiment, as shown in  FIG. 5 , the solvent  20  from the solvent storage  32  may be reheated using sensible heat remaining in the intermediate fluid  68  in the heat pump  66 , if used as the heating apparatus  54  for heating the froth  10  using heat in the tailings  46 . 
     In general, an unheated flash step can be used in the first stage of solvent recovery after froth separation:
         for the purpose of stabilizing the solvent-diluted bitumen, minimizing further precipitation of asphaltene from the bitumen in the PSRU; and/or   for the purpose of reducing the temperature of the solvent-diluted bitumen to allow for heat integration.       

     As described above, the unheated flash step can recover around 25% to around 30% of the solvent  20  from the solvent-diluted bitumen  24  and the underflow  24 S resulting from the unheated flash can be used to condense the overhead solvent vapour  20 V from the subsequent solvent recovery stage. 
     In embodiments, the solvent storage  32  comprises a series of the storage bullets configured for universal receipt and storage, or for segregated storage of fresh and/or recycled solvent, as required. 
     TSRU 
     Having reference to  FIGS. 2D and 3D  and as described generally above, the tailings underflow stream  36  from the second froth separation vessel  16 , or hydrocyclone  118  is fed to the TSRU (Stream E). The tailings  36  typically comprise water, asphaltenes, solids/minerals and residual solvent  20 . In embodiments, water  34  separated in the PRSU (Stream I) is combined with the tailing underflow stream  36 , allowing for further recovery of trace solvent therein. 
     In embodiments, the TSRU comprises at least one tailings solvent recovery vessel  38 . More particularly, in embodiments, the TSRU comprises first and second TSRU vessels  38 ,  40 , operated in series. Prior to delivery of the tailings stream  36  to the first TSRU vessel  38 , the tailings  36  are heated using steam. Heating the tailings stream  36  can assist in keeping the asphaltenes liquid, particularly following flashing of the residual solvent  20  therefrom. 
     In the embodiment as shown in  FIGS. 2D and 3D , the heated tailings stream  36  is pumped into the first TSRU vessel  38 , which acts as a pumpbox. The pressure in the first TSRU vessel  38  is lower than a vapour pressure of the heated tailings stream  36  causing a portion of the tailings, including residual solvent  20 , to flash therein, for removal from the pumpbox as an overhead vapour stream  300 , as described in Applicant&#39;s Canadian patent application 2,940,145. By way of example, in the embodiment shown in  FIG. 2D  the pumpbox is at about 140 kPag. 
     The flashing of the tailings in the first TSRU  38  is more violent than the flash occurring in the second TSRU vessel  40 . For this reason, internals within the first TSRU  38  are minimized, hence a pumpbox configuration is suitable. As the flash is less violent in the second TSRU, a conventional stripper column having additional internals is suitable. 
     The underflow stream  302  from the pumpbox  38 , which may comprise residual solvent  20 , is then pumped to the second TSRU vessel  40 , which is typically a steam stripper column having steam introduced at a bottom thereof, to be flashed therein. An overhead pressure in the overhead vapour stream  300  is used to drive an ejector  304 , which pulls the vapour from the stripper column  40  in a second overhead vapour stream  306  at a near neutral pressure of about 25 kPag. The ejector  304  also combines and pressurizes the overhead streams  300 , 306 . 
     The embodiments allow for control of the TSRU using the overhead streams  300 , 306 , thereby eliminating the need for modulating valves in the flashing service. Further, the overhead streams  300 , 306  are combined into one higher pressure stream for subsequent treatment. Embodiments of the TSRU reduce equipment count and result in a reduction in the flowsheet complexity. 
     Fixed pressure reduction elements can be used on the entry to the TSRU pumpbox  38  and stripper column  40  to control the feed pressure for said units, in conjunction with the overhead system pressure control. 
     Preheating of the tailings stream  36  prior to solvent recovery in the TSRU can also act to generate sufficient vapour to properly drive the ejector  304  for combining the overheads  300 , 306  from the first and second TSRU vessels  38 ,  40  at different pressures. 
     In the embodiment shown in  FIG. 2D , the overhead streams  300 ,  306  are combined prior to condensation. The net vapour is delivered to an overhead (O/H) condenser  307  and condensed against cooling water and then separated in a separation vessel  309 , such as at about 70 kPag to produce an overhead vapour stream  311  for delivery to the VRU (Stream F) for further processing and solvent  20  as an underflow stream for delivery to solvent storage  32  (Stream K). 
     In the embodiment shown in  FIG. 3D , the combined overhead streams  300 ,  306  are delivered from the ejector  304  to the VRU (Stream F), for further processing 
     In embodiments, shown in  FIGS. 2A, 2D, 3A and 3D , the first TSRU vessel  38  comprises two sets of primary nozzles, each set comprising a plurality of the nozzles therein. The primary nozzles are sized to deliver the tailings stream  36  pumped thereto into the first TSRU vessel  38 . One set of primary nozzles is redundant and is maintained for backup in case of failure of nozzles in the other set of primary nozzles. Should nozzles in the first set of nozzles fail, the second set of primary nozzles are put into service. The second TSRU vessel  40  comprises two sets of nozzles, a set of primary nozzles sized to deliver the tailings stream  36  and a set of secondary nozzles of a smaller size relative to the primary nozzles and suitable for delivering the underflow stream  302  from the first TSRU  38  to the second TSRU vessel  40 . In normal operation, the set of secondary nozzles are used deliver the underflow stream  302  to the second TSRU vessel. The set of primary nozzles in the second TSRU vessel  40  are maintained for backup should the first TSRU vessel  38  need to be taken off-line for repair, such as to replace nozzles therein. 
     In the case where the first TSRU  38  is taken offline, the tailings stream  36  is fed to a first bypass line  314 , which is fluidly connected to the primary nozzles in the second TSRU  40  to allow the tailings stream  36  to be delivered thereto, bypassing the first TSRU  38 . A second bypass line  316  delivers the overhead stream  306  from the second TSRU  40  to condenser  307 , bypassing the ejector  304 . 
     In the case where the second TSRU  40  is taken offline, a third bypass line  318  delivers the underflow  302  from the first TSRU  38  for disposal, or for heating the froth  10  in the FSU prior to disposal. 
     As a majority of the residual solvent is removed in a single stage of flash, should the first TSRU vessel be taken off-line, solvent  20  lost to the tailings underflow stream  46  from the second TSRU vessel  40  in this case is generally not significant. 
     Utility water W is sprayed into the first and second TSRU vessels  38 , 40  to wet a demister therein for efficiently separating mist therefrom. 
     As shown in  FIG. 3D , the underflow stream  302  from the first TSRU vessel  38  and the underflow stream  46  from the second TSRU  40  can be recycled back into the first and second TSRU vessels respectively using return lines  310  and  312 . 
     VRU 
     The VRU  400  collects, condenses and stores residual paraffinic solvent from the overhead (vapour) streams from the FSU, PSRU and TSRU.  FIGS. 2E and 3E  show alternative embodiments for processing vapour in the VRU. In the VRU, Applicant prefers to do most of the energic condensation (that is, the rejection of heat) to water. The alternative embodiments differ with respect to the extent to which compressors are used, as compressors are capital and maintenance intensive as compared to heat exchangers. Where low cost cooling water is readily available, the embodiment of  FIG. 3E , which relies on isothermal compression using water as the liquid coolant to absorb the heat generated, is preferred. 
     In the embodiment of the VRU  400  shown in  FIG. 2E , compression energy is minimized by sequential compression, condension and separation of the streams as the pressure increases. First, the pressure of the vapour stream (Stream I) from the TSRU is further increased by blower  402 , which in an embodiment is a lobe blower, and then by medium pressure (MP) compressor  404 , which in an embodiment is a liquid ring compressor. The net vapour stream from the unheated flash in the PSRU [Stream H] may enter the vapour stream of the VRU downstream of blower  402  and upstream of MP compressor  404 . 
     The vapour stream exiting compressor  404  may then be cooled against cooling water in exchanger  406  to partially condense the vapour and delivered to a first pressurized vertical gas-liquid separator  408 . The purge gas stream from the FSU [Stream G] may enter the vapour stream of the VRU downstream of MP compressor  404  and upstream of exchanger  406 . Thus, in embodiments the combined vapour stream from the FSU, PSRU and TSRU is cooled by exchanger  406  and delivered to the first separator  408 . 
     The pressure of the vapour stream  409  exiting first separator  408 , is again increased, for example by a High Pressure (HP) compressor  410 , which in embodiments is a screw compressor. The vapour stream is then chilled by chiller package  420  to partially condense the vapour, and separated in a second and final pressurized vertical gas-liquid separator  412 . 
     Chiller package  420  is a closed loop system that comprises a heat exchanger  422  and a vapour-compressor  424 . Coolant is evaporated through the heat exchanger  422 , to cool the vapour stream. The heated coolant is then circulated to the vapour-compressor  424  and condensed against air, for cooling. In an embodiment the coolant is propane. 
     The liquid solvent  426 , 20  from the first separator  408  is pumped and combined with the liquid solvent  428 , 20  from the second separator  412 , and delivered to the solvent surge and storage system  32 . 
     Any vapour  430  remaining after second separator  412  is delivered to the plant fuel gas FG system for use in boilers. 
     An alternative embodiment of the VRU processes, shown in  FIG. 3E , uses isothermal compression with internal cooling by water, rather than sequential compressing, condensing and separating, to recover solvent. 
     The net vapour stream from the unheated flash in the PSRU [Stream H] and the purge gas stream from the FSU [Stream G] are combined and delivered to a Joule-Thomson Valve  440  that expands the incoming vapour stream thereby reducing its pressure and temperature. The pressure is reduced to approximately the pressure of the vapour stream that is discharged from ejector  304  of the TSRU, typically about 170 KPaa. The temperature of the vapour is typically reduced by the Joule-Thomson Valve  440 , reducing downstream cooling requirements. 
     The combined overhead stream  300 , 306  from the ejector  304  is combined with the vapour stream  442  discharged from the Joule-Thomson Valve  440 , and this combined stream  444  is cooled against cooling water in exchanger  446  and partially condensed before delivery to a separator  448  (with demister). The liquid solvent  450 , 20  from demisting the separator  448  is delivered to the solvent surge and storage system  32 . In embodiments the temperature of the vapour entering and exiting the demisting condenser  448  is about 28° C. 
     The vapour stream  449  exiting the separator  448  is subjected to isothermal compression by isothermal compressor  451 , which condenses some solvent by direct contact with water and requires less compression energy as compared to some other compressors. Water is used as the liquid coolant to absorb the heat generated by compression of the vapour and condensation of the solvent during compression. The compression target is driven by the ability to condense against the downstream refrigerant at approximately 5° C. and the fuel gas system pressure requirements. The lower the exit temperature the less heat is delivered to the chiller system. In embodiments, isothermal compression increases the pressure of the vapour stream from about 126 KPaa to about 935 KPaa. 
     In one embodiment, compressor  451  is a liquid ring compressor. A liquid ring compressor comprises a vaned impeller located eccentrically within a cylindrical casing. Water is fed into the case of the compressor and forms a moving cylindrical ring against the inside of the casing. The vapour stream is drawn into the pump through an inlet port and trapped in compression chambers formed by the impeller vanes and the liquid ring. 
     In another embodiment compressor  451  is a multiphase pump, such as twin screw pump, progressive cavity pump or double acting piston pump. A twin-screw pump is preferred. These are rotary positive displacement pumps that consist of two intermeshing screws which form a series of chambers. As the screws rotate, these chambers move the multiphase fluid from the low pressure suction (inlet) ends of the pump towards the higher pressure discharge (outlet) in the center of the pump. 
     In yet another embodiment, compressor  451  is a gas-liquid ejector nozzle (e.g., obtained from Transvac Systems Ltd.). In this embodiment, high pressure water is used as the motive/primary fluid, to boost the pressure of the vapour stream. 
     The compressed vapour/water stream exiting the isothermal compressor  451  is delivered to a 3-phase pressurized separator  452  (e.g., a condensate drum) to separate liquid water from liquid solvent from residual vapour. Liquid water is cooled in exchanger  454  and recycled back to compressor  451  feed. Residual vapour  453  is delivered to a chiller package  420 . 
     Chiller package  420  is a closed loop system that comprises a heat exchanger  422  and a vapour-compressor  424 . Coolant is evaporated through the heat exchanger  422 , to cool the vapour stream. The heated coolant is circulated to the vapour-compressor  424  and condensed against air for cooling. In an embodiment, the coolant is propane. The chilled vapour is delivered to a second and final pressurized vertical liquid-gas separator  456 . 
     Liquid solvent  458 ,  20  from the 3-phase separator  452  is pumped and combined with the liquid solvent  460 ,  20  from the second separator  456 , and delivered as solvent stream  432  to the solvent surge and storage system  32 . Any vapour  430  remaining after second separator  456  is delivered to the plant fuel gas system for use in boilers. 
     Solvent surge and storage system  32  comprises one or more pressurized storage bullets  502  that receive and hold recycled solvent from the PSRU (Stream B) and from solvent stream  432  from the VRU. The solvent storage bullets  502  may also receive fresh pentane  504 ,  20  from a solvent preparation unit (SPU), may deliver solvent  506 ,  20  to the FSUs (stream C), and may receive solvent  508 ,  20  from or deliver solvent  510 ,  20  to trucks T. 
     In embodiments, a froth separation vessel for a high temperature paraffinic froth treatment process comprises: a vessel having a cylindrical portion, a conical bottom and a semispherical top; an inlet pipe extending substantially vertically within a center of the vessel from the top to about a transition between the cylindrical portion and the conical bottom; a feedwell fluidly connected to a bottom of the inlet pipe for delivering paraffinic solvent-diluted bitumen-containing froth to the vessel; a collector pot supported concentrically about the inlet pipe, at or about a top of a separation zone in the cylindrical portion, for collecting and discharging an overflow stream therefrom; a surge volume in the cylindrical portion above the separation zone; and an outlet in the conical bottom for discharging an underflow stream therefrom. In embodiments, the collector pot comprises: a cylindrical collection chamber having a closed top, an open bottom; and a discharge conduit fluidly connected from the collection chamber to outside the vessel. 
     In embodiments, the froth separation vessel of further comprises: liquid level control for controlling the liquid level in the vessel, wherein a normal liquid level is at or about the top of the collector pot. 
     In embodiments, a height of the separation zone is about 1.2 times a diameter of the cylindrical portion. 
     In embodiments, a froth separation vessel for a high temperature paraffinic froth treatment process comprises: a vessel having a cylindrical portion, a conical bottom and a semispherical top; an inlet pipe extending substantially vertically within a center of the vessel from the top to about a transition between the cylindrical portion and the conical bottom; a nozzle arrangement fluidly connected to a bottom of the inlet pipe for delivering paraffinic solvent-diluted bitumen-containing froth to the vessel; a collector ring supported toroidally about the inlet pipe, at or about a top of a separation zone in the cylindrical portion, for collecting and discharging an overflow stream therefrom; a surge volume in the cylindrical portion above the separation zone; and an outlet in the conical bottom for discharging an underflow stream therefrom. 
     In embodiments, the nozzle arrangement comprises: pairs of opposing nozzles, fluidly connected to the inlet pipe, the nozzles arranged symmetrically about a circumference of the vessel at about the transition, each nozzle being angled to create a flow of solvent-diluted froth in a horizontal plane therefrom to oppose a flow of solvent-diluted froth in the same horizontal plane from a nozzle in an adjacent pair of opposing nozzles. 
     In embodiments, the nozzle arrangement further comprises: feed pipes for fluidly connecting the pairs of opposing nozzles to the inlet pipe, each feed pipe angled downwardly from the inlet pipe at an angle of about 135 degrees relative to the inlet pipe. 
     In embodiments, the nozzle arrangement comprises three pairs of opposing nozzles, the pairs of nozzles being spaced circumferentially about the vessel spaced about 120 degrees apart. 
     In embodiments of the froth separation vessel, the collector ring comprises: a pipe supported toroidally about the inlet pipe at about a top of the collection zone; a plurality of inlet apertures in a lower surface of the pipe for collecting the overflow thereat; and a discharge outlet fluidly connected to the pipe for discharging the overflow outside the vessel.