WO2016004503A1

WO2016004503A1 - Apparatus and method for solvent recovery

Info

Publication number: WO2016004503A1
Application number: PCT/CA2014/050653
Authority: WO
Inventors: William Nicholas Garner; Saba Moetamed-Shariati; Ali Milani; Guillaume VIGUIE; Elizaveta GINGRAS; Sam PUN
Original assignee: Total E&P Canada Ltd.
Priority date: 2014-07-09
Filing date: 2014-07-09
Publication date: 2016-01-14

Abstract

A system and method is described for separating solvent from a solvent-diluted bitumen feedstream from oil sands froth treatment processing. A distillation tower receives a first feedstream portion intermediate the tower at or above the solvent bubble point and a second feedstream portion at an upper end of the tower at temperature at about or lower than the dew point of bitumen. A bitumen liquid product is recovered from a tower bottom and a solvent product is recovered from an upper end as recycle solvent to the upstream froth treatment process. Prior to splitting into first and second portions, the feedstream may be flashed, the underflow forming the tower feedstream while the overhead vapor is available directly as recycle solvent. The two feedstream portions and temperatures thereof enable solvent recovery without the use of a reflux or a bottom reboiler.

Description

"APPARATUS AND METHOD FOR SOLVENT RECOVERY"

FIELD

Embodiments disclosed herein relate to systems for recovering of hydrocarbon solvents from solvent-diluted bitumen formed during bitumen recovery from oil sands. BACKGROUND

Bitumen is produced from oil sand such as is found in the Fort McMurray region of Alberta, Canada. The oil sand is mined and recovered using hot water processes to produce bitumen-rich froth. The bitumen froth is diluted with a hydrocarbon diluent, such as a naphthenic or paraffinic solvent, to reduce the viscosity and density of the bitumen, and to aid in separating the diluted bitumen from water and solids contained in the froth. As a result, such separation procedures result in an underflow component (containing water, fine solids etc.) and a diluted, bitumen-rich overflow stream that also contains solvent and water. The overflow undergoes subsequent separation procedures in various vessels, known as solvent recovery units (SRUs), to recover and recycle the solvent and to produce a bitumen product ready for upgrading or pipelining.

To date, conventional SRUs operate as flash and distillation towers to separate solvent from solvent-diluted bitumen feed using common countercurrent exchange techniques of stripping the more volatile solvent fraction of the feed from the less volatile bitumen and rectification of the rising vapor to deliver purified overhead solvent vapor. At temperatures conducive to solvent vaporization, vapor progresses up the tower for overhead recovery becoming ever more enriched in the lower bubble point component. Liquid progresses down the tower becoming ever more enriched in the higher bubble point component as it descends for eventual recovery from the tower bottom. Through an equilibrium of bubble and dew points, a simultaneous exchange of heat and material occurs, between the rising solvent vapor and descending liquid. Descending liquid provides cooling and a partial condensation of the upflowing vapors. Temperature regulation within the tower, and particularly towards the upper end of the tower has conventionally demanded the application of the reflux of condensed overhead product and heat addition through bottom product reboilers to achieve the design separation.

Having regard to a conventional distillation of Fig. 1 , and to a variation thereof set forth in Canadian Patent Application 2,733,332, standard SRUs are pure distillation columns 100 equipped with an overhead condenser 120 to capture, cool and condense vaporized solvent ascending up the tower (upward squiggly arrows), a reflux 140 of the overhead distillate portion to return a fraction of the condensed and cooled liquid solvent back into the upper end of the SRU, a bottom discharge 160 to remove liquid bitumen (LB) having downwardly traversed the tower (downward linear arrows) to the lower end or bottom, and a bottoms reboiler 200 to provide heat to the lower end of the tower 100. Such conventional SRU columns 100 necessitate the distillate reflux 140 as a cooling stream to control temperature within the top portion of the column 100, and to provide partial condensation for removing remaining high boiling point bitumen from the solvent so as to minimize the amount thereof captured in the solvent vapors and purifying said vapors. This continuous process of distillation with distillate reflux 140 employs the difference in bubble points between the solvent and the bitumen at the operating pressure of the SRU 100, and serves to further purify the refluxed liquid solvent of the solvent product.

The use of distillate reflux, however, is expensive and can be complex to operate and maintain. Reflux increases the volume of circulating solvent vapors within the SRU resulting in larger tower diameters, additional energy cost in re- vaporization of the reflux stream (cooled liquids) and re-condensation of the vapor from the reflux stream in the overhead condenser, and the installation of additional circulation equipment. Further, in an emergency, the column contents may need to be flared, requiring accommodation and design for flaring correspondingly large volumes of excess vapors (e.g. re-vaporized reflux stream) during an emergency pressure release. In such instances, where the cooling mechanisms fail or break down, larger volumes of increasingly hot solvent vapors must be flared off entirely. As a result, known SRUs are equipped with extremely large flares, requiring sizable footprint and clearance, at substantial cost. There is thus great incentive in the industry to remove or at least reduce the reflux load.

As disclosed in CA 2,733,332, a known SRU can implement one or more flash vessels 180, 180a to initially remove a first vaporized portion of the diluted bitumen feedstream (F), thereby providing a preliminary separation of solvent-rich overhead vapor stream (S) that may be condensed and fed as a low boiler reflux to the column 100. Use of a second flash vessel, and as shown in Fig. 1 , the bitumen-rich liquid bottom stream (B) from first vessel 180 is further pre- separated in a second flash vessel 180a for producing two distinct feedstreams, a solvent-rich vapor stream (S ) directed to the upper end of the column, and a bitumen-rich liquid stream (B ) directed to a location intermediate the column. As a result, known SRU columns having a reflux 140 are often designed with upper portions having larger diameters to handle the increased vapors loads near the top of the column.

Standard SRUs 100 also commonly require bottom reheating through steam or reboilers 200, introducing heated vapor below the bitumen feedstream for stripping residual solvent from the cooling liquid bitumen product as it descends and is removed the column. Reboilers 200 add further capital and operational costs.

There is still an opportunity for further reducing capital and operational cost for solvent recovery column design and operational costs. BRIEF DESCRIPTION OF DRAWINGS

Figure 1 is a schematic representation of one form of known prior art solvent recovery unit having a flash vessel, a condensed overhead liquid reflux and a reboiler;

Figure 2 is a schematic representation of a solvent recovery tower according to an embodiment taught herein, without a reflux or a reboiler; and

Figure 3 provides sample modeling data relating to the operation of a solvent recovery tower according to an embodiment taught herein, without a reflux or a reboiler. SUMMARY

Using embodiments described herein, paraffinic solvent, such as butane, pentane, hexane, heptane, and octane, is used in a bitumen froth treatment process or operation. Economics require recovery and recycling of such solvents for reuse in the upstream froth treatment process. Solvent is recovered for recycle from a solvent-containing bitumen feedstream for production of a dry bitumen product that is mostly free of solvent. Final recovery is completed in a continuous distillation vessel known in the industry as a solvent recovery unit or SRU. In one embodiment, a dilute bitumen feedstream is fed to the SRU tower at two different feed locations on the tower. A first, lower feed location, at a location intermediate the height of the tower, receives a first portion of the feedstream. An upper feed location, adjacent to a location near the top of the tower, receives a second and remaining portion of the feedstream at lower temperature than the temperature of the first portion. The SRU is equipped for one or more distillation stages between the upper feed location and the intermediate feed location.

Prior to the embodiment wherein the feedstream is split or apportioned into two portions, the dilute bitumen feedstream can be introduced to a known flash drum for initial vapor reduction. A flashed low boiler portion, which is primarily solvent, can be deemed to be a first solvent product for use as solvent recycle to the earlier, upstream froth treatment process or for other uses. The first solvent product is recovered without further participation in further distillation processes such as at the SRU. The remaining bottoms or flash drum underflow can be fed to the present SRU tower at the two different feed locations. The first feedstream portion is provided at a first elevated temperature, and the second feedstream portion, introduced higher in the tower, is provided at a second temperature being lower than the first elevated temperature of the first feedstream portion. Stripping steam may be added adjacent the tower bottom, reducing the partial pressure of the downcoming liquids and stripping low boilers therefrom for forming the bitumen product.

Temperature management of the intermediate and bottom of the tower is managed by adjusting the temperature of the lower feedstream and the amount of stripping stream introduced below the first feedstream. The elevated temperature of the lower feedstream is balanced against the feed rate of the stripping steam, a higher first elevated temperature allowing for the elimination of a reboiler, and reduction of the steam requirement, mitigating moisture reporting to the bitumen product. Overhead vapors are condensed and removed from the tower as a solvent product. In an embodiment implementing a flash drum, this overhead solvent product is a second solvent product, typically combined with the first solvent product from the flash drum, for recycle to the upstream froth treatment process. The solvent product is not refluxed back to the SRU, minimizing vapor loads in the tower and the economic and process cost associated therewith.

A system for recovering solvent from a solvent-diluted bitumen feedstream containing at least bitumen and solvent is provided, the system comprising a distillation tower, having an upper end and a lower end, for receiving the feedstream in at least two feed portions, a first feed inlet, located intermediate the tower, for receiving a first feed portion of the feedstream at a first temperature, a second feed inlet, located above the first feed inlet, for receiving a second feed portion of the feedstream at a second temperature, said second temperature being lower than the first temperature, and wherein vaporized solvent is recovered at the upper end as a solvent product and liquid bitumen is recovered from the lower end as a bitumen product.

In one embodiment, the present system comprises introducing the first feed portion at a first temperature sufficient to vaporize the solvent. The first temperature may be at least the bubble point of the solvent.

In another embodiment, the present system comprises locating the first feed inlet adjacent the upper end of the tower.

In yet another embodiment, the present system may comprise a heat exchanger for pre-heating the first feed portion to the first temperature.

In yet another embodiment, the present system may further comprise an overhead condenser for receiving captured solvent vapors from the upper end of the tower and cooling said vapors to produce the solvent product as a liquid.

In yet another embodiment, the present system may comprise a steam inlet, said steam inlet may be located adjacent the lower end of the tower.

In yet another embodiment, the present system may further comprise a flash vessel or drum for first receiving the feedstream and producing a flashed solvent product from the solvent-diluted bitumen bottoms feedstream provided to the present system.

In another aspect, a method is provided for recovering solvent from a solvent-diluted bitumen feedstream by splitting the feedstream into a first feedstream portion and a second feedstream portion, introducing the first feedstream portion at a first feed inlet and at a first temperature to a distillation tower, the first feed inlet at intermediate location along a height thereof, and introducing the second feedstream portion at a second feed inlet and at a second temperature, the second feed inlet being located above the first feed inlet and said second temperature being lower than the first temperature. Further, products are recovered by recovering solvent vapors at an upper end of the tower as a solvent product, and recovering liquid bitumen from a lower end of the tower as a bitumen product.

Further the feedstream can be at the second temperature, the method further comprising heating the first feedstream portion from the second temperature to an elevated first temperature. Prior to portioning the feedstream into first and second feedstream portions one can perform the step of flashing the feedstream for separating the feedstream into a first solvent product and a dilute bitumen product, and wherein the dilute bitumen product forms the feedstream to the tower, and the solvent product recovered at the upper end of the tower is a second solvent product. The solvent is recovered with the requirement for reflux to the tower, wherein the solvent-diluted bitumen feedstream is from an upstream froth treatment process and the method further comprises recycling the first solvent product to the upstream froth treatment process; and recycling the second solvent to the upstream froth treatment process, in neither case is the solvent product refluxed at the tower. DESCRIPTION OF THE EMBODIMENTS

A system is provided for recovering solvent from a solvent-containing bitumen feedstream generally produced in a froth treatment facility. Having reference to Fig. 2, as is known, the diluted feedstream can be initially fed to a flash vessel 2 at a flash drum temperature and pressure for flash separation of the low boiler solvent, being primarily solvent, as a first solvent product 4 for use as solvent recycle back to froth treatment. The first solvent product can be recovered without further participation in further solvent recovery. The remaining bottoms stream from the flash vessel 2 can be fed as a dilute bitumen feedstream 6 to a form of solvent recovery unit SRU or the present distillation tower 10.

As set forth above, the implementation of one or more flash vessels 2 in advance of SRUs is known. It is contemplated that the present tower 10 can receive a diluted bitumen feedstream 6 from prior art flash vessel operations or directly from froth treatment facilities. Herein however, a pre-tower flash separation and recovery of the low boiler solvent is not further utilized as a low boiler reflux, with the negative process costs associated therewith, and instead, is recovered as the first solvent product 4.

The dilute bitumen feedstream 6 is directed to the tower 10 and split into portions for delivery at two different feed locations on the tower. Each feedstream portion is provided at different temperatures, via feed inlets positioned at upper and intermediate locations along the height of the tower, so as to strip the dilute bitumen feedstream into vaporized solvent and a liquid bitumen bottom product. The vaporized solvent is recovered as a distillate from the overhead or upper end of the tower, and the liquid bitumen bottom product is recovered from the bottom or lower end of the tower.

Using embodiments herein, the present tower 10 provides sufficient counter-current exchange of the feedstream hydrocarbon fractions to achieve effective rectification of solvent from the bitumen, without requiring reflux of the distillate or use of a bottom liquid reboiler. A skilled person may design the size and shape of the present tower 10 to achieve the desired results. Removal of the reflux stream is counterintuitive because it results in the removal of the conventional means for purifying the solvent.

Herein, unless the context sets forth otherwise, when discussing locations of various feeds to the SRU, such as above or below, the locations are separated by a theoretical stage so as to establish a distillation equilibrium for the separation of low and high boilers. Reference to terms "upper", "top", "lower", "bottom", and "intermediate" are used for the purposes of describing the present system only. Such terms are relative and are not intended, in any way, to narrow or limit the scope of the present system. Generally, as with known distillation processes, temperatures are highest at or near the lower end 14 of tower 10 and gradually decrease upwardly. In embodiments herein, temperature ranges at the upper end 12 enable rectification of bitumen from vaporized solvent. Higher temperatures in the lower end 14 enable stripping of the solvent vapor from the bitumen descending the tower 10 and withdrawn as an underflow product stream. Thus, towards the upper end 12 of the tower 10, the concentration of solvent in the liquid phase is less, while the solvent concentration in the vapor phase is greater. Likewise, towards the lower end 14 of the tower 10, the concentration of bitumen in the liquid phase increases.

A first, intermediate feed location 20, at an intermediate height along the tower 10, receives a first portion 22 of the feedstream 6. An upper feed location 24, adjacent a top of the tower 10, receives a second and remaining portion 26 of the feedstream 6. The tower 10 is equipped for one or more distillation stages between the upper feed location 24 and the intermediate feed location 22.

The first feedstream portion 22 is provided at a first elevated temperature T1 . The second feedstream portion 26 is provided at a second temperature T2, said second temperature being less than the first elevated temperature of the first feedstream portion 22. Stripping steam or gas 30, or a conventional reboiler, can be used adjacent the tower bottom 14, to provide heat for stripping low boilers from the downcoming liquids, reducing the partial pressure thereof, for forming a bitumen product 32 from the tower bottom 14. Where desirable, the use of stripping steam or gas 30 can allow for the elimination of a conventional reboiler, thereby further reducing capital and operating costs.

The first elevated temperature T1 of the lower feedstream 22 is balanced with the feed rate of stripping steam 30; a higher temperature of the first elevated temperature T1 allowing for a reduction in the overall steam requirement, mitigating the quantity of moisture that could report to the bitumen product 32. Overhead vapors from the top 12 of the tower are removed therefrom and condensed at condenser 40 and stored as a solvent product in an overhead drum 42. This overhead solvent product is a second solvent product 44 that, in an embodiment, can be combined with the first solvent product 4 from the flash drum 2, where applicable, for comprising the recovered solvent used as recycle to the froth treatment process. The second solvent product 44 is not refluxed back to the tower 10, minimizing vapor loads in the tower and the economic and process cost associated therewith.

The first temperature T1 of first feedstream portion 22 may be sufficient to vaporize solvent, being at or higher than the bubble point of the solvent fraction of the diluted bitumen feedstream 6, wherein at least some portion of the solvent is vaporized therefrom upon entering the tower 10. For example, where the solvent is pentane, the first temperature T1 is set to a pre-determined temperature between about 170°C and about 200°C at a pressure of approximately 400 KPaa. Temperatures greater than 200°C may be avoided so as to mitigate cracking of the bitumen, although a skilled person would be able to determine the pressure and temperature of the tower 10 based upon solvent type, separation efficiency, and other process conditions such as steam temperature and overhead condenser temperature.

In instances where the first temperature T1 is below the pre- determined range set forth above, the first feedstream portion 22 is pre-heated to the desired temperature using an exchanger or heater 50 prior to introduction to the tower 10.

The remaining second feedstream portion 26 at the second temperature T2, can be at or near the temperature of the feedstream 6. The second feed inlet 24 is positioned at least above first feed inlet 20, and in an embodiment herein, located adjacent the top or upper end 12 of tower 10. The second temperature T2 is at or near the dew point of bitumen, such that said portion may serve, at least in part, as a downflowing liquid load for further condensing and separating the bitumen from the upflowing vaporized solvent ascending up the tower 10.

The second temperature T2 of the second upper feed portion 26 is lower than the first temperature T1 , thereby providing a cooling stream to the upper end 12 of tower 10. As stated, the second temperature T2 may be consistent with temperature of the underflow from the feedstream 6, or other such vessel from which feedstream 6 is received. In one embodiment, the second temperature is at least greater than about 70°C, and preferably greater than about 100°C.

The second feedstream portion 26 serves as a cooling stream and eliminates the need for any reflux of the second solvent product 44, reducing the overall amount of solvent vapor being removed from tower 10 and captured by the overhead condenser 40, thereby reducing vapor loads on the tower 10 and design capacity for emergency pressure release equipment including flares. A smaller flares allows for less heat radiation allowance, saves on capital costs and land footprint.

Applicant has determined that the elimination of conventional reflux of the condensed overhead vapor allows the overall temperature of the tower 10 to be hotter, thereby reducing the amount of heat input required at or near the lower end of the tower 10. For example, the amount of stripping steam or gas 30, provided via a steam inlet positioned below intermediate inlet feed 20 can be reduced. Alternatively, where required, the amount or temperature of stripping steam or gas 30 can be increased to compensate where a somewhat cooler first feedstream portion 22 is utilized. As above, a conventional reboiler may be used in embodiments herein.

The liquid bitumen product 32 is removed from the bottom 14 of the tower 10. It is contemplated that residual solvent within said liquid bitumen product 32, if any, may be removed using a downstream bitumen stabilizer vessel 52, shown in dotted lines, and operated at low pressures. Such a stabilizer 52 can be an elongated horizontal vessel providing a shallow liquid pool with a large surface area to evaporate the residual solvent therefrom. Recovered residual solvent 54 is condensed and combined with at least the second solvent product 44.

As discussed above, distillation occurs across as series of theoretical stages so as to establish a distillation equilibrium for the separation of low and high boilers components. Stages can be provided by a series of devices such as plates, trays, other traditional internals, or combinations thereof. The placement and number of trays 60 spaced along the height of the tower 10 can be provided based upon common industry practice, as adapted for the purposes of the present solvent recovery system. Solvent to bitumen ratios can be targeted and designed at the tray level, and can be used to determine at which tray the first and second feedstream portions 22,26 are introduced to the tower 10.

In the event that the second feed is at or near the tower's upper end 12, the possibility of "bitumen mist" reporting to the overhead needs is managed. Conventional demisting technology is known in the art, however, when combined with novel coatings, such as fluoropolymers, demisters can be effectively used at low temperatures, even with difficult constituents such as bitumen. This presents a credible mist management method and allows the upper feed location 24 to be at or near the top of the tower 10, without resulting in substantial amounts of this particular type of contamination to the product. In this embodiment, there is provision for the periodic introduction of diesel and/or steam to clean the fluoropolymer coated demister system.

Energy advantages are also recognized in the provision of process flow cooling heat exchangers, such as for respective heat recovery during the cooling of overhead vapors and subsequent and optional cooling of the second feedstream portion 26. A conventional water chiller can provide water cooling to the overhead condenser 40, recovering heat with a resultant increase in water temperature. Without a need for intermediate cooling, the warmer water cooling stream can still be effectively used in an optional heat exchanger for controlling the second temperature to at the upper end 12 of the tower. For example, in the course of reducing the overhead temperature from 109°C to 70°C, the cooling water may rise from a nominal 70°C to 100°C. The 100°C cooling water could be applied in a heat exchanger to cool the second feedstream portion 26 from about 150°C to 130°C.

The heat exchanger 50 provides a primary control over the first temperature T1 of the first feedstream portion 22, intermediate the tower 10. Further control can be provided through portioning control of the respective rates of the first and second feedstream portions 22,26 such as through control valves at the inlets 20,24 respectively. For example, if the first temperature T1 is too hot, then the portion of the first feedstream portion 22 can be reduced, increasing the portion of the second feedstream portion 24.

The present solvent recovery system may involve a plurality of distillation towers configured in series, the liquid bitumen product discharged from a first tower being introduced to a secondary tower for further separation.

The present solvent recovery system may be adapted and operable at vacuum distillation conditions.

The present disclosure provides a detailed description of various elements required to operate a solvent recovery system, but many other known elements such as valves, pumps, piping or other units connected to tower 10, and required to operate the present system, have not been described herein.

Exemplary embodiments of the present invention are described in the following Example, which is set forth to aid in the understanding of the present solvent recovery unit, and should not be construed to limit in any way the scope of the system as defined in the claims which follow thereafter. EXAMPLE 1

Simulation analyses were performed to assess the capacity of one embodiment of the present solvent recovery system at an operating pressure of 435 kPa (Fig. 3). The present tower 10 resulted in various differences, when compared to a standard prior art solvent recovery unit ("PRIOR ART"), including the present tower 10 having:

· a hotter first intermediate feedstream portion 22 of 193°C, compared to the standard practice of providing bottom feed of the prior art at a temperature of 182.5°C,

· a cooler second and upper feedstream portion 26 at 98°C, compared to the prior art flash vessel feedstream temperature of 107°C;

· no reflux at all, compared to the prior art overhead drum reflux at 76°C · hotter upper end 12 captured overhead vapors at 109°C, compared to the captured overhead solvent vapors in the prior art system at a temperature of 87°C, and

· cooler bottoms liquid bitumen product 32 at a temperature of 170°C, compared with the prior art bottoms bitumen product at a temperature of 179°C.

Due to the apportionment of feedstream 6, the present solvent recovery system 10 allows for a smaller feed heat exchanger 50 having a duty of only 51 .2MW, compared to the standard 75.9MW required to heat the full feedstream fed to conventional SRUs. Due to less overhead vapor capture resulting from the elimination of reflux (578.6 T/h, compared to the standard 862.2 T/h), the present system 10 also allows for a smaller overhead heat exchanger 40 having a duty of only 79.3MW, compared to the standard 93MW. Further, the present solvent recovery system 10 requires more stripping steam gas 30, at about 27 T/h, compared to the prior art at 19.1 T/h. Although a few embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention. The terms and expressions used have been used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the invention is defined and limited only by the claims that follow.

Claims

THE EMBODIMENTS OF THE INVENTION FOR WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS: 1 . A system for recovering solvent from a solvent-diluted bitumen feedstream containing at least bitumen and solvent comprising: a distillation tower, having an upper end and a lower end; a first feed inlet, located intermediate the tower, for receiving a first feedstream portion of the feedstream at a first temperature; a second feed inlet, located above the first feed inlet, for receiving a second feedstream portion of the feedstream at a second temperature, said second temperature being lower than the first temperature; and wherein solvent vapors are recovered at the upper end as a solvent product and liquid bitumen is recovered from the lower end as a bitumen product.

2. The system of claim 1 , wherein the first temperature is at least the bubble point of the solvent.

3. The system of claim 1 or 2, wherein the second feed inlet is adjacent the upper end of the tower.

4. The system of claim 1 , 2, or 3, wherein the second feed inlet is located above the first feed inlet by at least one theoretical stage.

5. The system of any one of claims 1 to 4, wherein the system further comprises a steam inlet, located below the first feed inlet, for introducing steam for stripping solvent from at least the first feedstream portion.

6. The system of claim 5, wherein the steam inlet is adjacent the lower end of the tower.

7. The system of claim 5 or 6, wherein the steam inlet is located below the first feed inlet by at least one theoretical stage.

8. The system of any one of claims 1 to 7, wherein the system further comprises a heat exchanger for heating the first feedstream portion to the first temperature.

9. The system of any one of claims 1 to 8, further comprising flow control for portioning flow of the feedstream between the first and second feed inlets.

10. The system of any one of claims 1 to 9, wherein the system is operable without a reflux of the solvent product.

1 1 . The system of any one of claims 1 to 10, wherein the system is operable without a reboiler for the liquid bitumen.

12. The system of any one of claims 1 to 1 1 , wherein the feedstream is the solvent-diluted bitumen underflow of a flash drum.

13. The system of claim 12, wherein the second temperature is consistent with the temperature of the underflow from the flash drum.

14. The system of any one of claims 1 to 13, further comprising a condenser for receiving and cooling the vaporized solvent and producing the solvent product as a liquid.

15. The system of any one of claims 1 to 14, wherein the system further comprising a demister at the tower's upper end.

16. The system of claim 15, wherein the demister further comprises a fluoropolymer coating.

17. The system of any one of claims 1 to 16, wherein the solvent- diluted bitumen feedstream is from an upstream froth treatment process, the solvent product recovered at the upper end of the tower being recycled to the upstream froth treatment process.

18. The system of any one of claims 1 to 17, further comprising: a flash vessel for separating the feedstream into a first solvent product and a dilute bitumen product, and

wherein

the dilute bitumen product forms the feedstream to the tower, and

the solvent product recovered at the upper end of the tower is a second solvent product.

19. The system of any one of claims 1 to 18, wherein the solvent- diluted bitumen feedstream is from an upstream froth treatment process, wherein the first solvent product and the second solvent product are recycled to the upstream froth treatment process.

20. A method for recovering solvent from a solvent-diluted bitumen feedstream containing at least bitumen and solvent comprising:

splitting the feedstream into a first feedstream portion and a second feedstream portion;

introducing the first feedstream portion at a first feed inlet and at a first temperature to a distillation tower, the first feed inlet at intermediate location along a height thereof;

introducing the second feedstream portion at a second feed inlet and at a second temperature, the second feed inlet being located above the first feed inlet and said second temperature being lower than the first temperature;

recovering solvent vapors at an upper end of the tower as a solvent product; and

recovering liquid bitumen from a lower end of the tower as a bitumen product.

21 . The method of claim 20 wherein the after splitting the feedstream, further comprising heating the first feedstream portion to elevate the first temperature from the second temperature.

22. The method of claim 20 or 21 wherein, prior to splitting the feedstream into first and second feedstream portions, further comprising:

flashing the feedstream for separating the feedstream into a first solvent product and a dilute bitumen product, and wherein

the dilute bitumen product forms the feedstream to the tower, and

23. The method of claim 20, 21 , or 22, wherein the solvent-diluted bitumen feedstream is from an upstream froth treatment process, further comprising:

recycling the first solvent product to the upstream froth treatment process; and

recycling the second solvent to the upstream froth treatment process.