CA3077725C - Froth pump system and method - Google Patents

Abstract

An improved froth pump system, such as for pumping bitumen froth, is provided. The froth pump system has a primary pump configured to receive froth and vent a low density portion of the froth out of a vent port. At least one jet pump can be configured to expel a motive fluid to draw in the low density portion from the primary pump and impart momentum thereto. The jet pump can be configured to direct the mixture of the vented portion and motive fluid back to the pump box, reducing the amount of lost product and diluent due to the mixture being directed to an EDP. The improved pump system mitigates air locking and increases the amount of bitumen recovered while reducing the likelihood of blockage of the vent pipes of the pump system when compared to conventional systems using a vented primary pump.

Description

"Froth Pump System and Method"
FIELD
[0001] Embodiments herein relate to the processing of bitumen. In particular, embodiments herein relate to an improved pump system for pumping bitumen froth.
BACKGROUND

[0002] The extraction of bitumen from oil sands slurry involves the gravity separation of bitumen from solids in a gravity separation vessel known as a flotation cell, wherein air is added to the oil sands slurry to separate bitumen from solids such as sand and clays. During gravity separation in an initial primary separation cell (PSC), bitumen attaches to free air bubbles in the vessel and floats to the top thereof as a bitumen froth, while solids settle at the bottom of the vessel as PSC
tailings or underflow. The bitumen froth is then pumped from the gravity separation vessel to be further processed into a saleable product, such as diluted bitumen, which can be refined into various hydrocarbons. The PSC underflow can be pumped to a secondary flotation cell for further separation by adding air to the PSC
underflow to produce a secondary bitumen froth, also known as flotation froth, at the surface of the secondary flotation cell. This secondary froth typically flows via a weir system from the top of the secondary flotation cell into a launder, pump box, and/or surge tank, and can be pumped back to the PSC for further recovery.

Date Recue/Date Received 2021-09-24

[0003] Centrifugal pumps are often used to pump bitumen froth, for example from the PSC to storage/downstream process, or from the pump box receiving flotation froth from the secondary flotation cell back to the PSC. However, centrifugal pumps can suffer from a phenomenon known as "air lock", wherein pockets of air and low density portions of the froth can become trapped at the outer radial extremities of the pump housing and prevent bitumen froth from being pumped out of the outlet of the pump.

[0004] As shown in Fig. 1, a vented impeller design, such as the Continuous Air Removal System by Warman , may be used to mitigate air locking in froth-circulating centrifugal pumps by incorporating one or more openings near the center of the shroud of the pump impeller. The impeller is designed to promote movement of the low density portion of the bitumen froth, comprising air, low density fluid, and the like, towards the eye or center of the impeller. Holes or openings formed through the impeller permits the low density portion to migrate from an intake side of the impeller to a vent side thereof. A secondary inducer located at the vent side of the impeller opposite the pump inlet is configured to create low pressure near the one or more openings relative to the pressure on the intake side of the shroud, which promotes the flow of the low density portion accumulated near the center of the impeller from the intake side to the vent side and thereafter out of the pump via a vent port located at the rear of the pump housing and into a vent conduit in communication therewith. The amount of air and froth vented is controlled by a vent Date Recue/Date Received 2021-09-24 control valve, such as a globe valve, positioned in-line with the vent conduit.
Opening the vent control valve results in less flow restriction and greater venting.

[0005]
While the use of a vented impeller and vent port can assist in mitigating air lock, if the vent control valve is not opened enough, the pump may continue to become air locked due to the small amount of air expelled.
Conversely, when the control valve is opened further to permit air to be vented at a sufficient rate to mitigate air lock, a significant amount of bitumen froth may also be vented, as the low density of highly aerated bitumen froth causes it to accumulate near the center of the impeller and be vented with air. This vented bitumen froth is typically directed back to the pump box via a standpipe. However, accumulation of froth in the standpipe creates a back pressure to the vent port of the centrifugal pump.
Due to the pressure head required to overcome the back pressure and transport the vented froth back to the pump box, which can be over 50 kPag for a typical pump box, the rate at which air and low density froth can be vented from the pump is limited. The venting rate can be increased by instead directing the vented froth to a trench at atmospheric pressure and grade and subsequently flushed, for example using water, to an emergency dump pond (EDP). While venting to an EDP at atmosphere increases the maximum venting rate in comparison with directing the vented froth back to the pump box, the vented froth becomes lost product, including any bitumen that is vented with the air. Additionally, it may not always be practical to vent froth to an EDP.

Date Recue/Date Received 2021-09-24

[0006] Moreover, vented bitumen froth can plug the vent line, preventing additional air from being vented from the centrifugal pump and causing further air locking.

[0007] It is also common in conventional froth pumping systems to use a two-stage pump system to achieve the requisite total dynamic head (TDH) to pump the froth back to the PSC or to another desired location. While a two-stage pump system provides the requisite TDH, it is expensive due to the cost of purchasing and maintaining multiple pumps, and introduces another point of failure in the pump system. Further, performance of the first pump stage can be so poor due to air locking that even a two-stage system does not provide the required TDH

[0008] Additionally, conventional froth pumping systems require relatively tall pump boxes, for example over 10m tall, to provide the requisite net positive suction head (NPSH) for the centrifugal pump to operate without cavitating or air locking. If the fluid in the pump box drops below a requisite height, the pump may no longer have sufficient NPSH to pump effectively and will begin to experience air locking. A
lower pump box height is desirable as the height of the PSC must be adjusted proportionally to the height of the pump box to maintain desired gravity flow thereto.
Increasing the height of the PSC requires additional support structure with a commensurate cost increase.

[0009] The height of pump boxes is also increased due to the need for a measure of surge capacity to prevent inadvertent overfilling of the pump box.
If the Date Recue/Date Received 2021-09-24 pump box begins to reach capacity, the flow of upstream processes may need to be reduced such that the pump box overflows. Such reduction of process flow results in less efficient operation and decreased throughput. Thus, a measure of surge capacity is desirable to reduce the need for adjustments to upstream processes.

[0010] It is also often required to introduce a diluent, for example water, into the pump box to dilute the froth therein in order to reduce the air volume content of the froth.

[0011] There remains a need for a froth pump system capable of mitigating air locking in centrifugal pumps while reducing the amount of wasted product and addressing other disadvantages of conventional froth pumping using vented pumps.
SUMMARY

[0012] Generally, an improved froth pump system, such as for pumping bitumen froth, is provided. The froth pump system comprises a primary pump such as a centrifugal pump with a vent port, and at least one jet pump configured to receive a vented low density portion of the froth from the vent port and expel a motive fluid to impart momentum thereto. In embodiments, the at least one jet pump can be configured to direct the mixture of the vented portion and motive fluid back to the pump box, thus reducing the amount of lost product and diluent due to the mixture being directed to an EDP.
Date Recue/Date Received 2021-09-24

[0013] The improved pump system mitigates air locking and increases the amount of bitumen recovered while reducing the likelihood of blockage of the vent pipes of the pump system when compared to conventional systems using a vented primary pump.

[0014] In a general aspect, a pump system for pumping froth comprises:_a primary pump comprising a pump housing having an inlet for receiving froth, a discharge outlet, and a vent port;_an impeller located within the pump housing configured to direct a low density portion of the froth out of the vent port as a vented portion and a remaining portion of the froth out of the discharge outlet;
and_at least one jet pump comprising a jet pump housing having a motive fluid inlet for receiving a motive fluid, a vented portion inlet, and a jet outlet in communication with each other via a main bore, and a nozzle located within the main bore and in communication with the motive fluid inlet;_wherein the vented portion inlet is in communication with the vent port of the primary pump.

[0015] In an embodiment, the vented portion inlet is in communication with the vent port via a vent conduit having a length.

[0016] In an embodiment, the pump system comprises two or more jet pumps

[0017] In an embodiment, at least two of the two or more jet pumps are arranged in parallel.

[0018] In an embodiment, at least two of the two or more jet pumps are arranged in series.

Date Recue/Date Received 2021-09-24

[0019] In an embodiment, the motive fluid is warm.

[0020] In an embodiment, a temperature of the motive fluid is about the same as a temperature of the vented portion.

[0021] In an embodiment, the pump system further comprises a control valve located upstream of the motive fluid inlet.

[0022] In an embodiment, the motive fluid is water.

[0023] In an embodiment, the motive fluid is a hydrocarbon.

[0024] In an embodiment, the froth is received at the inlet from a pump box, and the jet pump is configured to deliver a fluid mixture comprising the motive fluid and the vented portion to the pump box.

[0025] In an embodiment, the jet pump is configured to deliver the fluid mixture to the pump box via a line terminating under a fluid level of the pump box.

[0026] In an embodiment, the jet pump is configured to deliver a fluid mixture comprising the motive fluid and the vented portion to a froth launder.

[0027] In an embodiment, the primary pump is a centrifugal pump.

[0028] In an embodiment, a diameter of the main bore of the jet pump increases towards the jet outlet.

[0029] In an embodiment, a diameter of the main bore of the jet pump decreases toward a constriction located along the main bore and increases from the constriction toward the jet outlet.

Date Recue/Date Received 2021-09-24

[0030] In another broad aspect, a method of pumping froth comprises:
receiving the froth at a primary pump; venting a low density portion of the froth as a vented portion; directing a remaining portion of the froth to downstream processes or storage; directing the vented portion to at least one jet pump; and flowing a motive fluid through a nozzle of the jet pump.

[0031] In an embodiment, the step of receiving the froth comprises receiving the froth from a pump box, and further comprising directing a fluid mixture comprising the motive fluid and the vented portion from the jet pump to the pump box.

[0032] In an embodiment, the step of directing the fluid mixture comprises directing the fluid mixture to a point under a fluid level of the pump box.

[0033] In an embodiment, the step of directing the fluid mixture comprises directing the fluid mixture to a froth launder upstream of the pump box.

[0034] In an embodiment, the method further comprises heating the motive fluid to a temperature of about a temperature of the vented portion.

[0035] In an embodiment, the step of directing the vented portion to at least one jet pump comprises directing the vented portion to two or more jet pumps.

[0036] In an embodiment, the method further comprises arranging at least two of the two or more jet pumps in parallel.

[0037] In an embodiment, the method further comprises arranging at least two of the two or more jet pumps in series.

Date Recue/Date Received 2021-09-24

[0038] In an embodiment, the method further comprises adjusting one or both of pressure and rate at which the motive fluid is flowed through the nozzle according to a measured discharge pressure of the primary pump.
BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a cross-sectional representation of a prior art froth pumping system;

[0040] Figure 2A is a schematic representation of a froth pumping system;

[0041] Figure 2B is a schematic representation of a froth pumping system having two jet pumps arranged in parallel;

[0042] Figure 2C is a schematic representation of a froth pumping system having two jet pumps arranged in series;

[0043] Figure 2D is a schematic representation of a froth pumping system having two vent lines and two jet pumps arranged in series along each line

[0044] Figure 3 is an elevation cross-sectional representation of an embodiment of a centrifugal primary pump;

[0045] Figure 4A is a cross-sectional representation of an embodiment of a froth pumping system having a centrifugal primary pump and a jet pump;

[0046] Figure 4B is a cross-sectional representation of another embodiment of a froth pumping system having a centrifugal primary pump and a jet pump;

Date Recue/Date Received 2021-09-24

[0047] Figure 4C is a cross-sectional representation of an embodiment of a froth pumping system having a centrifugal primary pump and two jet pumps arranged in parallel;

[0048] Figure 4D is a cross-sectional representation of an embodiment of a froth pumping system having a centrifugal primary pump and two jet pumps arranged in series; and

[0049] Figure 5 is a flow diagram illustrating the flow path of bitumen froth in an exemplary process incorporating the pumping system disclosed herein.
DESCRIPTION

[0050] With reference to Figs. 2A-4D, an improved pump system 10 for pumping froth F, such as bitumen froth, is provided herein for mitigating air locking, while increasing the maximum venting rate and amount of bitumen recovered and reducing the likelihood of blockage of the vent pipes of the pump system 10.
Embodiments of the pump system 10 disclosed herein are advantageous over conventional bitumen froth pump systems as it provides increased bitumen recovery, increased maximum venting rate, reduced lost product, and reduced pump maintenance costs.

[0051] In general, the pump system 10 comprises a primary pump 12, such as a centrifugal pump, and at least one jet pump 14. The centrifugal pump 12 is configured to receive bitumen froth F from a froth source 8 such as a pump box or Date Recue/Date Received 2021-09-24 surge tank, vent a low density portion of the froth FL, and pump a remaining portion of the froth FR to a PSC or other equipment. The jet pump 14 is configured to receive vented fluids FL from the centrifugal pump 12 and emit water or another suitable motive fluid FM through a nozzle therein to create a suction to draw in the vented portion FL from the centrifugal pump 12 and impart a motive force thereto to discharge it out of an outlet end of the jet pump 14. The motive fluid FM
generates a positive pressure towards the outlet end to further assist in conveying the discharged bitumen-containing mixture FO of vented portion FL and motive fluid FM back to the pump box 8 to be stored with the rest of the bitumen froth F. The froth F is therefore recovered instead of disposed of, and can be pumped by the centrifugal pump 12 to the PSC or other downstream equipment. In other embodiments the jet pump 14 can pump the fluid mixture FO elsewhere, such as to a froth launder, storage tank, or another process.

[0052]
In detail, with reference to Fig. 2A and 3, the centrifugal pump 12 can have a housing 20 with an inlet 22 located at an inlet side 24 of the pump 12 and configured to receive bitumen froth F from a froth source 8, such as a pump box receiving secondary froth from a secondary flotation cell, a discharge outlet 26, and a vent port 28 located at a rear or vent side 30 of the pump 12 opposite the inlet side 24. An impeller 32 is rotatably mounted in the housing 20 to rotate about an axis of rotation X. In embodiments, the axis of rotation X is substantially aligned with the inlet 22 of the pump 12. The impeller 32 is operatively coupled at its axis of rotation Date Recue/Date Received 2021-09-24 to a drive means 34, for example via a driveshaft 36 connected to a motor, configured to drive the impeller 32 at sufficient speed to draw bitumen froth F from the bitumen froth source 8 and convey the froth F out of the discharge outlet 26 to processing equipment downstream, such as back to a primary separation cell (PSC).
The impeller 32 is further configured to direct a low density portion of the froth FL, such as a portion containing air and low density fluid, towards the vent port 28, for example by using the impeller design as described in US Patent No. 9,879,692.
For example, in an embodiment, the impeller can have a plurality of vanes located at an inlet side of an impeller shroud and configured to direct a low density portion of the froth FL towards an eye or center of the impeller, and a flow inducer located at a venting side of the shroud configured to draw the low density portion FL to the venting side through a plurality of openings in the shroud and direct the low density portion FL out of the vent port 28. The low density portion is thereby vented from the pump 12 as vented portion FL. As one of skill in the art would understand, the above described centrifugal pump 12 is merely one possible embodiment, and other pump designs configured to vent air and low density fluid from the pump 12 may be used in the pumping system 10 without deviating from the scope of the invention described herein.

[0053]
In exemplary embodiments herein, the bitumen froth source 8 will be assumed to be a pump box 8, and centrifugal pump 12 will be assumed to be configured to deliver bitumen froth F from the pump box 8 back to the PSC.

Date Recue/Date Received 2021-09-24 However, one of skill in the art would understand that embodiments of the pumping system 10 described herein may be used in a variety of applications to deliver froth F from any froth source 8 to any destination, for example to deliver froth F
from the PSC to storage or downstream processes.

[0054]
With reference to Figs. 2A, 4A, and 4B, a jet pump 14 is located downstream of the vent port 28 of the centrifugal pump 12 and is in communication therewith via vent conduit 16, and is configured to receive vented portion FL
from the centrifugal pump 12 and provide positive pressure to convey the vented portion FL
back to the pump box 8 or another destination. The jet pump 14 comprises a jet pump housing 40 having a main or axial bore 46, a motive fluid inlet 48 located at a first end 42 of the housing 40 in communication with the axial bore 44 and connected to a motive fluid source 50, a jet pump outlet 52 in communication with the axial bore 46 and located at a second end 44 of the housing opposite the first end 42, and a vented portion inlet 54 in communication with the axial bore 46 and configured to receive vented portion FL from the centrifugal pump 12. A nozzle 56 in communication with the motive fluid inlet 48 is located in the axial bore 46.
A motive fluid pump 51 can be configured to pump motive fluid FM from the motive fluid source 50 through the nozzle 56. A control valve 49 can be located between the motive fluid pump 51 and the motive fluid inlet 48 for controlling the flow and/or maximum pressure of the motive fluid.

Date Recue/Date Received 2021-09-24

[0055] In embodiments, the nozzle 56 is axially coincident with, or upstream of, the intersection between the vented portion inlet 54 and the axial bore 46, such that vented portion FL entering the axial bore 46 from the vented portion inlet 54 will become entrained in the motive fluid FM discharged from the nozzle 56. In embodiments, the nozzle 56 is a converging nozzle that reduces the pressure, and increases the velocity, of the motive fluid FM flowing therethrough into the axial bore 46. The pressure reduction created by the converging nozzle 56 creates a venturi effect that assists in drawing vented fluid FL from the primary pump 12.

[0056] As shown in Fig. 4A, in an embodiment, the inner diameter D of the axial bore 46 of the jet pump 14 increases toward the second end 44. The increase in inner diameter D towards the outlet end 44 creates a positive pressure that assists in transporting the motive/vented portion mixture FO towards downstream equipment, such as the pump box 8.

[0057] In another embodiment, with reference to Fig. 4B the inner diameter D
of the axial bore 46 of the jet pump 14 decreases from the first end 42 of the jet pump to a constriction 58 located between the first end 42 and second end 44 of the jet pump 14. The inner diameter D of the axial bore 46 can then increase from the constriction 58 towards the second end 44. The decrease in inner diameter D
towards the constriction 58 creates a secondary venturi effect as the motive fluid/vented portion mixture FO flows therethrough and draws vented portion FL
and motive fluid FM towards the second end 44 of the pump. The increase in inner Date Recue/Date Received 2021-09-24 diameter D towards the outlet end 44 creates a positive pressure to assist in transporting the motive/low density portion mixture FO towards downstream equipment, such as the pump box 8.

[0058] The size and dimensions of the jet pump 14 may be selected to adjust the venting capacity and available pressure head thereof. The axial bore 46 and other internal surfaces of the jet pump 14 can be lined with a durable wear resistant material, for example chrome white iron, carbide weld overlays, or other wear resistant liners, to mitigate corrosion or erosion due to the flow of motive fluid and/or vented portion FM, FL, FO.

[0059] In embodiments, with reference to Figs. 2B and 4C, multiple jet pumps 14a,14b,... may be configured in parallel to further increase the venting capacity of the primary pump 12. Increasing the number of jet pumps 14 in parallel creates additional suction in the vent conduit 16 and increases the rate at which vented portion FL may be drawn out of the vent port 28.

[0060] With reference to Figs. 2C and 4D, multiple jet pumps 14a,14b,... may also be configured in series to increase the maximum pressure head available to transport the vented portion FL. Such a series configuration can be used to transport the vented portion FL greater distances and/or heights, such as when it is desired to direct the fluid mixture FO to another location besides the pump box 8 so as to not dilute the froth in the pump box 8.
Date Recue/Date Received 2021-09-24

[0061] As shown in Fig. 2D, the jet pumps 14a,14b,... can also be arranged in series on parallel venting lines to provide both greater venting rates and maximum pressure head.

[0062] In embodiments, the length of vent conduit 16¨ in other words the fluid travel distance ¨ between the primary pump 12 and the jet pump 14 can be selected to improve the performance of the pumping system 10. For example, reducing the distance between the jet pump 14 and centrifugal pump 12 reduces pressure at the vent port 28 which allows vented portion FL to be vented from the pump 12 at a higher rate. Reducing the length of the vent conduit 16 is also advantageous as a short length permits greater venting capacity while reducing the effects of plugging or fouling of the conduit 16. It may also be desirable to heat trace the vent conduit 16 and other sections of the pump system to mitigate potential fouling issues.

[0063] In embodiments, the line leading from the jet pump outlet 52 to the pump box 8 can terminate underneath the liquid level of the pump box 8 to provide a siphoning effect and further assist in transporting the fluid mixture FO from the jet pump 14 to the pump box 8. For example, with reference to Fig. 2A to Fig. 2D, the line can run from the jet pump outlet 52 up over a lip of the pump box 8 and down into the pump box 8 below the fluid level thereof in a gooseneck fashion. An advantage of such a design is that vented portion FL will continue to be drawn into the pump box 8 in the event the motive fluid pump 51 fails and motive fluid FM
is not flowed through the jet pump 14.

Date Recue/Date Received 2021-09-24

[0064] In embodiments, as shown in Fig. 2A to Fig. 2D, a flow control valve 49 can be located along the motive fluid line to permit adjustment of the fluid pressure and flow of the motive fluid FM. This in turn adjusts the rate at which vented portion FL is vented from the pump 12. The flow control valve can be manually adjusted, or automated to adjust pressure / flow rate in response to parameters of the pumping system such as the discharge pressure of the primary pump 12. For example, the expected discharge pressure of the primary pump 12 can be calculated based on froth flow and pump speed. If the measured discharge pressure of the pump 12 is lower than the expected discharge pressure, this may be indicative of air locking in the primary pump 12. The flow of motive fluid FM through the jet pump 14 can then be increased to increase the draw of the jet pump, in turn increasing the rate at which vented portion FL is drawn from the primary pump 12. The flow of motive fluid FM can also be decreased if the measured discharge pressure is within the expected range in order to reduce dilution of the vented portion FL.

[0065] In embodiments, the motive fluid FM can be warm water, for example water at a temperature of about 40 C to 95 C, which lowers the viscosity of the vented portion FL of the bitumen froth F. The motive fluid FM can also be heated to be about the same pressure as the vented portion FL. Lowering the viscosity of the vented portion FL further assists in mitigating plugging of the vent pipes 16, jet pump 14, and/or equipment and conduits downstream. In other embodiments, the motive fluid FM is a light hydrocarbon such as naphtha, paraffin solvent, tailings water, and Date Recue/Date Received 2021-09-24 the like. Such motive fluids can also be warmed to provide a viscosity-reducing effect.

[0066] In use, with reference to Fig. 5, in an exemplary embodiment, bitumen froth F is pumped from a pump box 8 back to a PSC using a centrifugal pump 12.

The centrifugal pump 12 is configured to vent air and a low density portion of the froth F as a vented portion FL to a jet pump 14 as described above for delivery back to the pump box 8 or froth launder upstream of the pump box 8. Motive fluid FM
is pumped from a motive fluid source 50 to the motive fluid inlet 48 of a jet pump 14 and is discharged out of a nozzle 56 located within a main bore 46 of the jet pump 14. The discharged motive fluid FM mixes with vented portion FL entering into the jet pump 14 and imparts momentum thereto, directing the motive fluid/vented portion mixture FO towards the second end 44 and out the outlet 52 of the jet pump 14.

[0067] In embodiments wherein the axial bore 46 of the jet pump 14 increases in inner diameter D towards the second end 44, the fluid pressure of the fluid mixture FO increases with the inner diameter D as it flows towards the jet pump outlet 52.
The positive pressure created by the fluid mixture FO as the axial bore 46 expands towards the outlet end 44 provides additional impetus to assist in transporting the fluid mixture FO to the pump box 8.

[0068] In embodiments wherein the axial bore 46 of the jet pump 14 has a constriction 58, as the fluid mixture FO passes through the constriction 58, the low pressure created by the constriction 58 draws additional vented low density portion Date Recue/Date Received 2021-09-24 FL into the axial bore 46 of the jet pump. The fluid pressure of the fluid mixture FO
increases inner diameter D of the axial bore 46 increases towards the outlet end 44 of the jet pump 14, thus also providing additional impetus to assist in transporting the fluid mixture FO to the pump box 8.

[0069] Use of the jet pump 14 in the embodiments of the froth pumping system 10 disclosed herein is advantageous over conventional systems, as bitumen vented from the centrifugal pump 12 that would have otherwise been disposed of in the EDP can now be recovered in the pump box 8. Additionally, the suction created by the jet pump 14 assists in drawing the vented portion FL from the centrifugal pump 12 while the motive fluid FM pushes the vented portion FL drawn into the jet pump 14 towards the jet pump outlet 52, thereby reducing the likelihood that low density portion of the froth F will plug the vent conduit 16 or other components and cause further air locking in the centrifugal pump 12.

[0070] A further advantage of the pump system 10 disclosed herein is that it mitigates the need for a two-stage pump system, as venting air and low density portion FL from the first pump stage (i.e. the primary pump 12) to a jet pump using the system disclosed herein allows the first stage pump 12 to operate at higher speeds and total dynamic head (TDH). As a result, the second stage pump can be turned down to add a reduced amount of additional head, or potentially bypassed altogether.

Date Recue/Date Received 2021-09-24

[0071] Additionally, the disclosed pump system 10 reduces the need for oversized pump boxes 8. Conventional froth pumping systems require taller pump boxes, for example over 10m tall, to provide the requisite net positive suction head (NPSH) for the centrifugal pump to operate without cavitating or air locking.
Venting to the jet pump reduces the likelihood of air locking such that required NPSH
is lower, in turn permitting a shorter pump box to be used.

[0072] The improved operation provided by the present pumping system 10 also allows greater surge capacity to be provided by the pump box 8 due to the reduced NPSH requirement, thus enabling a greater operational range of flow from upstream processes and reducing the likelihood that said upstream processes will be required to reduce flow to avoid overfilling of the pump box 8.

[0073] Another advantage of the present pumping system is that the motive fluid FM flowed through the jet pump also serves to dilute the bitumen froth F
in the pump box 8 when the motive fluid / vented low density portion mixture FO is returned thereto. In conventional pumping systems, diluent is added directly to the pump box 8 to dilute the bitumen froth F therein. Thus, less water is used overall in embodiments of the pumping system 10 disclosed herein compared to conventional systems, as the motive fluid FM used for the jet pump 8 is recycled into the process and doubles as a diluent in the pump box 8.
Date Recue/Date Received 2021-09-24 Exam pie

[0074] In an exemplary embodiment, a bitumen froth pumping system 10 comprises a centrifugal pump 12 configured to receive and pump bitumen froth F

containing about 7.5-15% bitumen, 7.5-10% solids, and 75-85% water to a downstream process at rate of 1000-1500 m3/hrt. The froth F comprises about 40 vol.% air. The centrifugal pump 12 suffers from significant de-rating due to the relatively high air content in the bitumen froth F. To counteract air locking and improve pump performance, the centrifugal pump 12 is configured to vent a low density portion FL of the bitumen froth F out of a vent port 28 as vented portion FL to a trench, which directs the vented fluid FL to an EDP. A vent valve 29 operable to control the volume of vented portion travelling out of the centrifugal pump 12 through the vent port 28 may be opened to allow more vented portion FL to be vented.
However, about 1-10 m3/h of bitumen is lost to the EDP due to bitumen being vented together with the low density vented portion FL. Additionally, about 40m3/h of warm water must be continuously flowed through the trench to evacuate the vented portion FL to the EDP. Said water and vented portion FL, along with the bitumen contained therein, are lost product unless they can be separated and recovered using further processes at additional cost.

[0075] To address these issues, a jet pump 14 is located downstream of, and in communication with, the vent port 28 of the centrifugal pump 12 to assist in drawing vented portion FL from the centrifugal pump 12 and providing motive force Date Recue/Date Received 2021-09-24 and positive pressure to deliver the motive/vented portion mixture FO to a pump box 8 rather than disposing of the fluid mixture in the EDP. About 150-170 m3/h at kpag of warm water can be pumped through the jet nozzle 56 of the jet pump 14 as motive fluid FM to impart a motive force to the vented portion FL. In this particular example, the motive fluid header pressure is 400kpag. The motive/vented fluid mixture FO flows through the axial bore 46 of the jet pump 14 at a velocity of about 20m/s or greater and the discharge pressure of the jet pump 14 is about 100-kpag. The incorporation of the jet pump 14 in the pumping system 10 resulted in the recovery of about 1-10 m3/h of bitumen froth that would have otherwise been lost to the EDP, as well as about 20 m3/h of warm water, as warm water no longer needs to be continuously flowed through the trench and lost to the EDP, but is instead recovered in the pump box 8.

[0076]
In other applications, Applicant has found that an average of 60m3/h of vented bitumen froth was recovered by incorporating one or more jet pumps 14 downstream of the vent port 28 of the primary pump 12.

Date Recue/Date Received 2021-09-24

Claims (25)

WE CLAIM:

1. A pump system for pumping froth, comprising:
a primary pump comprising a pump housing having an inlet for receiving froth, a discharge outlet, and a vent port;
an impeller located within the pump housing configured to direct a low density portion of the froth out of the vent port as a vented portion and a remaining portion of the froth out of the discharge outlet; and at least one jet pump comprising a jet pump housing having a motive fluid inlet for receiving a motive fluid, a vented portion inlet, and a jet outlet in communication with each other via a main bore, and a nozzle located within the main bore and in communication with the motive fluid inlet;
wherein the vented portion inlet is in communication with the vent port of the primary pump.

2. The pump system of claim 1, wherein the vented portion inlet is in communication with the vent port via a vent conduit having a length.

3. The pump system of claim 1 or 2, wherein the pump system comprises two or more jet pumps.

4. The pump system of claim 3, wherein at least two of the two or more jet pumps are arranged in parallel.

5. The pump system of claim 3 or 4, wherein at least two of the two or more jet pumps are arranged in series.

6. The pump system of any one of claims 1 to 5, wherein the motive fluid is at a temperature between 40 C to 95 C.

7. The pump system of any one of claims 1 to 6, wherein a temperature of the motive fluid is about the same as a temperature of the vented portion.

8. The pump system of any one of claims 1 to 7, further comprising a control valve located upstream of the motive fluid inlet.

9. The pump system of any one of claims 1 to 8, wherein the motive fluid is water.

10. The pump system of any one of claims 1 to 8, wherein the motive fluid is a hydrocarbon.

11. The pump system of any one of claims 1 to 10, wherein the froth is received at the inlet from a pump box, and the jet pump is configured to deliver a fluid mixture comprising the motive fluid and the vented portion to the pump box.

12. The pump system of claim 11, wherein the jet pump is configured to deliver the fluid mixture to the pump box via a line terminating under a fluid level of the pump box.

13. The pump system of any one of claims 1 to 10, wherein the jet pump is configured to deliver a fluid mixture comprising the motive fluid and the vented portion to a froth launder.

14. The pump system of any one of claims 1 to 13, wherein the primary pump is a centrifugal pump.

15. The pump system of any one of claims 1 to 14, wherein a diameter of the main bore of the jet pump increases towards the jet outlet.

16. The pump system of any one of claims 1 to 15, wherein a diameter of the main bore of the jet pump decreases toward a constriction located along the main bore and increases from the constriction toward the jet outlet.

17. A method of pumping froth, comprising:
receiving the froth at a primary pump;
venting a low density portion of the froth as a vented portion;
directing a remaining portion of the froth to downstream processes or storage;
directing the vented portion to at least one jet pump; and flowing a motive fluid through a nozzle of the jet pump.

18. The method of claim 17, wherein the step of receiving the froth comprises receiving the froth from a pump box, and further comprising directing a fluid mixture comprising the motive fluid and the vented portion from the jet pump to the pump box.

19. The method of claim 18, wherein the step of directing the fluid mixture comprises directing the fluid mixture to a point under a fluid level of the pump box.

20. The method of claim 18, wherein the step of directing the fluid mixture comprises directing the fluid mixture to a froth launder upstream of the pump box.

21. The method of any one of claims 17 to 20, further comprising heating the motive fluid to a temperature of about a temperature of the vented portion.

22. The method of any one of claims 17 to 21, wherein the step of directing the vented portion to at least one jet pump comprises directing the vented portion to two or more jet pumps.

23. The method of claim 22, further comprising arranging at least two of the two or more jet pumps in parallel.

24. The method of claim 22 or 23, further comprising arranging at least two of the two or more jet pumps in series.

25. The method of any one of claims 17 to 24, further comprising adjusting one or both of pressure and rate at which the motive fluid is flowed through the nozzle according to a measured discharge pressure of the primary pump.