Bituminous froth inline steam injection processing

Abstract

An inline bitumen froth steam heater system is comprised of steam injection and static mixing devices. The steam heater system heats and de-aerates an input bitumen froth without creating downstream processing problems with the bitumen froth such as emulsification or live steam entrainment. The inline bitumen froth steam heater is a multistage unit that injects and thoroughly mixes the steam with bitumen resulting in an output bitumen material having a homogenous temperature of about 190° F. The heating system conditions a superheated steam supply to obtain saturated steam at about 300° F. The saturated steam is contacted with a bitumen froth flow and mixed in a static mixer stage. The static mixers provide a surface area and rotating action that allows the injected steam to condense and transfer its heat to the bitumen froth. The mixing action and the increase in temperature of the bitumen froth results in reduction in bitumen viscosity and also allows the release of entrapped air from the bitumen froth.

Description

FIELD OF THE INVENTION

This invention relates to bitumen processing and more particularly is related to heating bituminous froth using inline steam injection.

BACKGROUND TO THE INVENTION

In extracting bitumen hydrocarbons from tar sands, one extraction process separates bitumen from the sand ore in which it is found using an ore washing process generally referred to as the Clark hot water flotation method. In this process, a bitumen froth is typically recovered at about 150° F. and contains residual air from the flotation process. Consequently, the froth produced from the Clark hot water flotation method is usually described as aerated bitumen froth. Aerated bitumen froth at 150° F. is difficult to work with. It has similar properties to roofing tar. It is very viscous and does not readily accept heat. Traditionally, processing of aerated bitumen froth requires the froth to be heated to 190° to 200° F. and deaerated before it can move to the next stage of the process.

Heretofore, the aerated bitumen froth is heated and de-aerated in large atmospheric tanks with the bitumen fed in near the top of the vessel and discharged onto a shed deck. The steam is injected below the shed deck and migrates upward, transferring heat and stripping air from the bitumen as they contact. The method works but much of the steam is wasted and bitumen droplets are often carried by the exiting steam and deposited on nearby vehicles, facilities and equipment.

SUMMARY OF THE INVENTION

The invention provides an inline steam heater to supply heated steam to a bitumen froth by direct contact of the steam to the bitumen froth resulting in superior in efficiency and environmental friendliness than processes heretofore employed.

In one of its aspect, the invention provides an inline bitumen froth steam heater system including at least one steam injection stage, each steam injection stage followed by a mixing stage. Preferably, the mixing stage obtains a mixing action using static mixing devices, for example, using baffle partitions in a pipe. In operation, the invention heats the bitumen froth and facilitates froth deaeration by elevating the froth temperature. In operation the bitumen froth heating is preferably obtained without creating downstream problems such as emulsification or live steam entrainment. The froth heater is a multistage unit that injects and thoroughly mixes the steam with bitumen resulting in solution at homogenous temperature. Steam heated to 300 degrees Fahrenheit is injected directly into a bitumen froth flowing in a pipeline where initial contact takes place. The two incompatible substances are then forced through a series of static mixers, causing the steam to contact the froth. The mixer surface area and rotating action of the material flowing through the static mixer breaks the components up into smaller particles, increasing contact area and allowing the steam to condense and transfer its heat to the froth. The reduction in bitumen viscosity also allows the release of entrapped air.

Other objects, features and advantages of the present invention will be apparent from the accompanying drawings, and from the detailed description that follows below. As will be appreciated, the invention is capable of other and different embodiments, and its several details are capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and description of the preferred embodiments are illustrative in nature and not restrictive

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional block diagram of a preferred embodiment of a bitumen froth heating process arrangement of the invention.

FIG. 2 is a cross section elevation view of an inline steam heater and mixer stage of FIG. 1.

FIG. 2 a is an elevation view of a baffle plate of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with a preferred embodiment of the process two inputs components, namely, bitumen froth and steam, are contacted to produce an output homogenous bitumen product heated to a temperature of 190° F. The input bitumen froth component 10 is supplied at about 150° F. In a pilot plant implementation the input bitumen froth component is supplied via a 28 inch pipeline at a rate of about 10,000 barrels per hour. The input steam component 12 is supplied as a superheated steam at about 500° F. and at 150 psi.

FIG. 1 shows a functional block diagram of a preferred embodiment of a bitumen froth heating apparatus arranged in accordance with the invention. The input steam component 12 is supplied to a pressure control valve 14 which reduces the pressure to a set point pressure, which is typically about 90 psi. A pressure transmitter 16 is provided to monitor the pressure of the steam downstream from the pressure control valve 14 to provide a closed loop control mechanism to control the pressure of the steam at the set point pressure. The pressure controlled steam is supplied to a temperature control valve 18 that is used to control the supply of condensate 20 to cool the steam to its saturation point, which is about 300° F. at the controlled pressure of 90 psi. A temperature sensor 22 monitors the steam temperature downstream from the temperature control valve to provide a closed loop control mechanism to control the temperature of the steam at the temperature set point setting.

The optimum parameters for steam injection vary so a computer 24 executes a compensation program to review the instantaneously supplied instrumentation pressure 26 and temperature 28 measurements and adjusts inlet steam pressure and temperature set point settings as required. A pressure sensor 29 measures the pressure of the input bitumen component 10 to provide the compensation program executing on computer 24 with this parameter to facilitate optimum control of the parameters for steam injection.

To provide a greater capacity for supply or transfer of heat to the bitumen froth component, the pressure and temperature controlled steam 30 is split into two steam sub-streams 30a, 30b. Each steam sub-stream is supplied to a respective steam injector 32a, 32b and the steam injectors 32a and 32b are arranged in series to supply heat to the bitumen froth component stream 10. While two steam injectors arranged in series are shown in the figure, it will be understood that the bitumen froth component stream 10 could equally well be split into two sub-streams and each bitumen froth component sub-stream supplied to a respective steam injector arranged in parallel. Moreover, it will be understood that more than two sub-streams of either the steam component or the bitumen component streams could be provided if process flow rates require. A suitable inline steam injector 32a, 32b is manufactured by Komax Systems Inc. located in Calif., USA.

An inline steam injection heater works well in heating water compatible fluids but bitumen is not water compatible so additional mixing is advantageous to achieve uniform fluid temperature. Consequently, in the preferred embodiment depicted in FIG. 1, the bitumen and steam material flow mixture is passed through an inlet baffle 34a, 34b downstream from the respective steam injector 32a, 32b. The inlet baffle, which is shown more clearly in FIG. 2a, directs the material flow mixture downward to initiate the mixing action of the steam component with the bitumen froth component. Mixing of the material flow continues by passing the material flow through static mixers 36a and 36b respectively.

As seen most clearly in FIG. 2, the static mixers provide baffles 40 arranged along the interior volume of each static mixer to effect a mixing action of the material flowing through the static mixer. The mixing action of the material flow through the static mixer is provided by arranging the baffles 40 within the static mixer to impart a lateral, radial, tangential and/or circumferential directional component to the material flow that changes repeatedly along the length of the static mixer. Different static mixer designs and baffle arrangements may be used to advantage in mixing the steam component with the bitumen froth component.

A temperature transmitter 42 is located downstream of the mixers 36. The temperature of the material flow exiting the static mixer is measured by the temperature transmitter 42 and is used to control the rate of supply of steam to the inline steam injector 32 by the associated flow control valve 44. In this manner, a closed loop control system is provided to control the supply of the steam component to the bitumen froth component to obtain a set point or target output temperature of the material flow leaving the static mixer 36.

Referring again to FIG. 1, the heating system shown in FIG. 2 is arranged with a temperature transmitter 42a, 42b located downstream of each respective mixer 36a, 36b. The temperature of the material exiting each static mixer is measured by the temperature transmitter and is used to control the rate of supply of steam to the inline steam injectors 32a, 32b by the associated flow control valve 44a, 44b respectively. In this manner, a closed loop control system is provided to control the supply of the steam component to the bitumen froth component to obtain a set point or target output temperature of the material flow leaving each static mixer stage 36a, 36b. The water content of the bitumen froth component 10 can range form 30% to 50%. In a pilot plant implementation of the preferred embodiment, each inline steam heater 32a, 32b was found to be capable of heating about 10,000 barrels per hour of bitumen froth by about 30° F. utilizing about 80,000 pounds per hour of steam. By way of comparison to conventional process apparatus, the atmospheric tank method would use about 125,000 pounds of steam to achieve a similar heat transfer.

After heating, the heated bitumen froth is delivered to a plant for processing. To facilitate material flow rate co-ordination with the processing plant, the heated bitumen froth may be discharged to a downstream holding tank 46, preferably above the liquid level 48. The heated, mixed bitumen froth releases entrained air, preferably, therefore, the holding tank is provided with a vent 50 to disperse the entrapped air released from the bitumen froth. To maintain the temperature of the heated bitumen froth in the holding tank 46, a pump 50 and recycle line 52 are provided, which operate to recycle the hot bitumen froth from the holding tank to the process inlet of the heaters.

The invention has been described with reference to preferred embodiments. Those skilled in the art will perceive improvements, changes, and modifications. The scope of the invention including such improvements, changes and modifications is defined by the appended claims.

Claims

1. Apparatus to heat a bitumen froth by steam comprising: i. a source of steam; ii. an inline heater body forming a bitumen inlet, a steam inlet in communication with the source of steam and a mixture outlet all in common communication with each other; iii. a baffle disposed across the mixture outlet; and iv. an elongate static mixer body forming a passageway therethrough, one end of the passageway in communication with the mixture outlet, the body supporting a plurality of baffles disposed to effect a mixing action of material flowing through the passageway thereof.

2. The apparatus of claim 1 wherein the baffles are disposed within the static mixer body to impart a lateral, radial, tangential or circumferential directional component to a material flow through said static mixer passageway that changes repeatedly along the length of the passageway.

3. The apparatus of claim 1 further including a steam flow control valve to control the rate of steam supply to the steam inlet.

4. The apparatus of claim 3 further including a temperature transmitter disposed to measure the temperature of material flowing through the passageway of the static mixer forming a closed loop control system of the steam flow control valve responsive to the measured temperature.

5. The apparatus of claim 1 further including a steam flow pressure control valve to control the pressure of steam supply to the steam inlet from the steam source.

6. The apparatus of claim 5 further including a pressure transmitter disposed to measure the pressure of steam supply from the pressure control valve forming a closed loop control system of the steam flow pressure control valve to maintain the pressure of the steam supplied to the steam inlet.

7. The apparatus of claim 1 further including: i. a condensate source; ii. means to mix the condensate with steam from the steam source; and iii. a condensate flow control valve to control the supply of condensate to the mixing means.

8. The apparatus of claim 7 further including a temperature transmitter disposed to measure the temperature of steam supply to the steam inlet forming a closed loop control system of the condensate flow control valve to control the supply of condensate to the steam supply to the steam inlet responsive to the measured temperature.

9. Apparatus to heat a bitumen froth by steam comprising: i. a source of steam; ii. an inline heater body forming a bitumen inlet, a steam inlet in communication with the source of steam and a mixture outlet all in common communication with each other; iii. a steam pressure flow control valve to control the pressure of steam supply to the steam inlet from the steam source; iv. a condensate source; v. means to mix the condensate with steam from the steam source; vi. a condensate flow control valve to control the supply of condensate to the mixing means; vii. a steam flow control valve to control the rate of steam supply to the steam inlet from the steam source; viii. a baffle disposed across the mixture outlet; and ix. an elongate static mixer body forming a passage therethrough, one end of the passage in communication with the mixture outlet, the body supporting a plurality of baffles disposed to effect a mixing action of material flowing through the static mixer.

10. The apparatus of claim 9 wherein the baffles are disposed within the static mixer body to impart a lateral, radial, tangential or circumferential directional component to a material flow through said passage that changes repeatedly along the length of the static mixer passage.

11. The apparatus of claim 9 further including a temperature transmitter disposed to measure the temperature of material flowing through the passage of the static mixer proximal to the end of the passage remote from the end in communication with the mixture outlet forming a closed loop control system with the steam flow control valve to control the supply of steam to the material to obtain a target output temperature of the material flow leaving the static mixer.

12. The apparatus of claim 9 further including a pressure transmitter disposed to measure the pressure of steam supply to the steam inlet from the steam source forming a closed loop control system of the steam pressure flow control valve to control the supply of steam to the steam inlet responsive to the measured pressure.

13. The apparatus of claim 9 further including a temperature transmitter disposed to measure the temperature of steam supply to the steam inlet forming a closed loop control system of the condensate flow control valve to control the supply of condensate to the mixing means responsive to the measured temperature.

14. A method to heat a bitumen froth by steam comprising: i. providing a source of steam; ii. contacting the steam with a bitumen froth flow within an inline heater body; iii. mixing the steam and bitumen froth flow to obtain a uniform temperature of the mixture material flow.

15. The method of claim 14 further including the step of controlling the rate of steam supply of the steam contacting the bitumen froth to control the uniform temperature of the mixture material obtained in the mixing step.

16. The method of claim 15 further including the steps of: i. measuring the uniform temperature of the mixture material flow; and ii. varying the rate of steam supply of the steam contacting the bitumen froth flow to obtain a target uniform temperature of the mixture material flow.

17. The method of claim 14 further including the step of controlling the pressure of the steam supply of the steam contacting the bitumen froth.

18. The method of claim 17 further including the steps of: i. measuring the controlled pressure of the steam supply; and ii. varying the rate of the steam supply to obtain a target pressure of the steam contacting the bitumen froth.

19. The method of claim 14 further including the step of providing a condensate to the steam supply to control the temperature the steam contacting the bitumen froth.

20. The method of claim 19 further including the steps of: i. measuring the controlled temperature of the steam supply contacting the bitumen froth; and ii. varying the rate of providing condensate to the steam supply to obtain a target temperature of the steam contacting the bitumen froth.

21. A method to heat a bitumen froth by steam comprising: i. providing a source of steam; ii. controlling the pressure of the steam; iii. controlling the temperature of the steam; iv. controlling the rate of supply of the steam; v. contacting the steam with a bitumen froth flow within an inline heater body; and vi. mixing the steam and bitumen froth flow to obtain a uniform temperature of the mixture material flow.

22. The method of claim 21 further including the steps of: i. measuring the uniform temperature of the mixture material flow; and ii. varying the rate of steam supply of the steam contacting the bitumen froth flow responsive to the measured temperature.

23. The method of claim 21 further including the steps of: i. measuring the controlled pressure of the steam supply; and ii. varying the rate of the steam supply responsive to the measured pressure.

24. The method of claim 21 further including the steps of: i. measuring the controlled temperature of the steam supply contacting the bitumen froth; and ii. varying the rate of providing condensate to the steam supply responsive to the measured temperature.