Patent ID: 12258522

DETAILED DESCRIPTION OF THE INVENTION

It is to be understood that the disclosure is not limited in its application to the details of the embodiments as set forth in the following description. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. By way of example only, preferred embodiments of the present invention are described hereinafter with reference to the accompanying drawings.

Furthermore, it is to be understood that the terminology used herein is for the purpose of description and should not be regarded as limiting. Contrary to the use of the term “consisting”, the use of the terms “including”, “containing”, “comprising”, or “having” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of the term “a” or “an” is meant to encompass “one or more”. Any numerical range recited herein is intended to include all values from the lower value to the upper value of that range.

The present invention focuses on replacing the production of hot water shown in the hatched box inFIG.1with an improved process designed to overcome some of the problems associated with the existing technology.

The present invention provides many benefits, inter alia, it:reduces green house gas emission,reduces criteria air contaminants generated,uses mature fine tailings thereby allowing the drainage of the tailings pond while producing a dry tailing material suitable of terrestrial sequestration and with near zero fresh water requirements,provides a pathway to a near zero green house gas emission approach,allows for the recovery of extra bitumen currently contained within mature fine tailings,improves energy efficiency by using direct contact approaches, andreplaces high capital cost items (boilers and heat exchangers) with more economical equipment thereby improving the economics.

The present invention is an improved method for supplying hot water for primary extraction in a more economic and environmentally sustainable manner than what is used in the current practice.

The method disclosed in the present invention has the advantage of using mature fine tailings to achieve the results, thus depleting the use of tailings ponds which are massive structures that require high maintenance.

FIG.2is a schematic representation of an embodiment of a process of oil sands bitumen extraction according to the present invention.

The process according to the present invention replaces the heat exchanger/steam boiler used in the existing technology (shown inFIG.1within the hatched box) and replaces the water heating function with a different process shown inFIG.2within the hatched box.

The new process uses a new hot water technology (shown inFIG.2within the hatched box) capable of using fuel and a high fraction of the mature fine tailings from the tailings pond while producing a dry tailing from that material.

The following describes three embodiments of the invention depending on what is required by the process.1. For situations where less drying (dry to <50% solids) of mature fine tailings are required and no hydrocarbon destruction is needed, the double stage submerged arrangement as described inFIG.3is adequate. The limitation on drying is due to the need to keep the vessels from plugging and keep the slurry transportable as the water is removed past 50%.2. For situations where mature fine tailings are required to be dried from 50-100% solids and when there is a requirement to remove residual hydrocarbon, the flash submerged arrangement as described inFIG.4can be used. The disadvantage is that there may be increased carryover of solids to the hot water vessel and the arrangement will be slightly less efficient. This arrangement will be able to destroy hydrocarbon but will be unable to recover hydrocarbon/bitumen if that is a requirement.3. For situations where mature fine tailings are needed to be dried to 50-100% solids and when there is a requirement to both recover residual hydrocarbon and destroy any remaining residual hydrocarbon with the dry solid, the triple cascading arrangement as described inFIG.5is most suitable. This arrangement maximizes the contact between the flue gas and the mature fine tailings baths and therefore has the advantages of making each stage as efficient as possible and minimizing solids travelling towards the hot water vessel. This arrangement would also be best used in situations where hydrocarbon destruction is required in order to better remediate the dry solid stream.

All three arrangements have the option to use either air or oxy-firing for the fuel burners. The oxy-firing route will render a relatively pure CO2stream that is capable of being sequestered or utilized. This means that these technologies can all have near zero green house gas emissions.

Double Stage Submerged Arrangement

FIG.3is a schematic representation of an embodiment of the double stage submerged arrangement according to the present invention.

As shown inFIG.3, this arrangement consists of equipment arranged in a unique configuration that benefits operations and the environment. It uses two submerged fuel burners20and40in tandem within two separate unit operations.

In the first stage, mature fine tailings have been pumped into a thickener vessel10from a tailing pond (not shown), the mature fine tailings have approximately 30% solids at 25° C. A fuel burner20is submerged in the thickener vessel10. Fuel (natural gas, mostly CH4) is introduced into the submerged fuel burner20which then through combustion produces a flue gas comprising mostly CO2, H2O and nitrogen. The flue gas comes out of the bottom of submerged fuel burner20and bubbles through mature fine tailings bath50is used to evaporate water from within the mature fine tailings in a direct contact mode. The resulted more concentrated mature fine tailings are then discharged as a thick paste suitable for terrestrial sequestration or further processing. The amount of thickening of mature fine tailings is dictated by the need for the thickened slurry to flow and not accumulate in bottom of the thickener vessel10which will potentially plug the thickener vessel10. Using mature fine tailings, the upper limit on thickening is approximately 50% solid and therefore if further drying is required the other arrangements as described below may be more suitable.

In the second stage, another fuel burner40is submerged within a hot water vessel30, the submerged fuel burner40is used to heat water fed in from pond effluent water (PEW) from the tailing pond (not shown). The pond effluent water contains >99% H2O. Meanwhile, the moisture in the flue gas/steam coming out from the thickener vessel10is also fed into the hot water vessel30to condense to liquid and recover its latent heat in heating the pond effluent water.

Mature fine tailings contain small amounts of bitumen that slipped through the system. This bitumen could be a valuable commodity. In the thickener vessel10, as the mature fine tailings bath50is heated by the submerged fuel burner20, some of the bitumen contained in the mature fine tailings will float to the top of the mature fine tailings bath50. The mature fine tailings will stratify to produce relatively clean top water at the top and a heavier solid-rich layer towards the bottom. The floated bitumen along with the clearer top water can be skimmed. The remaining clearer top water can then be reintroduced into the hot water vessel30making the clearer top water part of the hot water to the primary separation process. In this manner, previously not captured bitumen contained in the mature fine tailings will also be added to the freshly mined bitumen, thereby increasing the overall bitumen recovery rate.

By placing the thickener vessel10and hot water vessel30in tandem, relatively pure H2O vapour generated in the thickener vessel10is fed through to the hot water vessel30and re-condensed, which increases the amount of clean water generated by the hot water vessel30by capturing both the evaporation from flue gas/steam from the thickener vessel10as well as the H2O generated from the combustion reaction. As well, it captures the latent heat in the flue gas/steam from the thickener vessel10and transfers the heat to the hot water vessel30, improving overall energy consumption of the two-stage process.

Since the latent heat in the flue gas/steam from the thickener vessel10from the first stage is fully utilized within the process, the only losses from the system are radiant/convective losses from the surface of the vessels. This makes the invention much more energy efficient than the current existing processes. The simplicity and reduced size of this arrangement improve the economics of this process.

Pond Effluent Water (PEW) compared with the mature fine tailings contains very few solids. However, it does contain small amounts of solids that add to the solids loading through the entire bitumen mining process. By using the hot water vessel30to heat the pond effluent water solids contained in the pond effluent water will gather in the bottom of the hot water vessel30. In the lower portions of the hot water vessel30, where the solids are most likely to deposit, water will be drawn from these specific areas (called “blowdown” inFIG.3). This process will transfer the solids once contained in the pond effluent water to the thickener vessel10where eventually the thickened solids are permanently removed from the system.

Although the double stage submerged arrangement can be done using air-fired systems, the operation can also be realized by using an oxy-firing mode, thus the exhaust gas will be highly concentrated CO2, ready for sequestration or for use in any other industrial applications.

The submerged fuel burners20,40are typically air fired. Air contains 79% N2and 21% O2by volume with some other very minor components. When hydrocarbon fuels such as fuel (mostly CH4) are combusted, oxygen is consumed from the air to produce flue gas, so the overall reaction is as follows:
CH4+2 O2(from the air)→CO2+2H2O

The flue gas will comprise CO2, H2O and nitrogen from the air. To use the flue gas sequestration some means (usually amine) would need to be used to separate the N2from the CO2in order to obtain a 100% CO2stream for sequestration (H2O can be removed simply by condensation).

With the option to be fired with straight O2(from an ASU), once the H2O is condensed, the flue gas is nearly 100% pure CO2and therefore capture ready by being pumped underground (sequestration).

The efficiency gain (and subsequent GHG/CAC reduction) of the present invention compared to the previous art are summarized in Table 1.

TABLE 1Efficiency gain of the present invention compared to thecurrent art of steam boiler/heat exchanger technologyExisting Technology(using steam boiler/Technology usingheat exchanger)present inventionHot water produced (t/h)1,198.01,198.0Fuel Feed (GJ/h)354.5310.5MFT feed (t/h)—139.5Efficiency gain (%)—12.4

As the mature fine tailings are processed, certain amounts of the water locked in the mature fine tailings is recovered, the water recycle rate in bitumen extraction plant is significantly improved.

Several scenarios for the water recycle rate have been tested. As the mature fine tailings are concentrated more with the present invention, the water recycle rate increases from the 80% range to more than 95%.

Flash Submerged Arrangement

FIG.4is a schematic representation of an embodiment of a flash submerged arrangement according to the present invention.

As the mature fine tailings thicken, their viscosity increases, making them prone to solidifying causing plugging. It also becomes more problematic to pump the mature fine tailings using the conventional technology.

For situations where mature fine tailings are required to be dried to 50-100% solids and when there is a requirement to remove residual hydrocarbon from the concentrated mature fine tailings stream, the flash submerged arrangement may be more suitable.

Referring toFIG.4, the flash submerged arrangement uses the two stage arrangement; however, in this arrangement, during the first stage, mature fine tailings, pumped from a tailing pond (not shown), with approximately 30% solids at 25° C., are sprayed into a flash concentrator vessel60, as opposed to using the submerged fuel burner20during the first stage in the double stage submerged arrangement. This process may be useful in situations where the mature fine tailings prove to be too viscous to be penetrated by the submerged fuel burner or should the frothing induced by the bitumen contained within the mature fine tailings prove to be more than can be adequately managed within the flash concentrator vessel. The spray drying approach may also allow the bitumen (hydrocarbon) contained within the mature fine tailings to reach higher temperatures and thereby be burnt and consumed within the process.

Within the flash submerged arrangement, mature fine tailings are sprayed into the flash concentrator vessel60near a burner or series of burners70to supply the required heat. A baffle divides the flash concentrator vessel60so as to minimize the opportunity of the flue gas to short circuit the system and become underutilized. Multiple mature fine tailings nozzles can also be installed in the flash concentrator vessel60for a larger scale application. The exhaust gas (flue gas) resulted from a burner or series of burners70near the flash concentrator vessel60needs to be kept over approximately 650° C. in order to destroy any residual hydrocarbon if that is a requirement.

The mature fine tailings slurry will most likely be preheated with the flue gas/steam exhaust from the flash concentrator vessel60. The mature fine tailings slurry would be sprayed in through a nozzle or series of nozzles near the top of the flash concentrator vessel60.

The bottom of the flash concentrator vessel60provides volume for the concentrated solids to accumulate and facilitates its continuous removal from the system.

Solids are removed from the bottom of the flash concentrator vessel60by using gravity and mechanical means, such as being pumped, augured, etc.

The flash concentrator vessel60can be elevated to allow for disposal vehicles to be loaded beneath it.

In the second stage, a fuel burner40is submerged within a hot water vessel30, the submerged fuel burner40is used to heat water fed in from pond effluent water (PEW) from the tailing pond (not shown). The pond effluent water contains >99% H2O. Meanwhile, the moisture in the flue gas/steam coming out from the flash concentrator vessel60is fed into the hot water vessel30to condense its moisture to liquid and recover its latent heat in heating the pond effluent water.

The flue gas from the flash concentrator vessel60would be mostly steam as in the double stage submerged arrangement. The hot water vessel30would be similar to what is in the double stage submerged arrangement (except that a baffle is added to reduce the short circuiting). Blowdown (with solids) from the hot water vessel30in a similar manner to the double stage submerged arrangement would be added to the flash concentrator vessel60.

Spray dryers by their very nature produce fine particulate that will travel out of the flue gas pipe. This means a dust collection is usually required. The flash submerged arrangement takes the flue gas and bubbles it through the hot water vessel30, equivalent to using a scrubber. Dust in the exhaust will fall to the bottom of the hot water vessel30and be removed by the blowdown.

The disadvantage of the flash submerged arrangement is that there may be increased carryover of solids to the hot water vessel30and the arrangement will be slightly less efficient. Since flue gas/steam is fed into the hot water vessel30, solids carryover will be transferred to the hot water vessel30. Should further solids removal be required, a dust collecting cyclone can be installed in between the flash concentrator vessel60and the hot water vessel30. The flash submerged arrangement will be able to destroy hydrocarbon but be unable to recover hydrocarbon using a skimming operation if that is a requirement.

If the mature fine tailings are dried fully, water locked in the mature fine tailings is 100% recovered, and the process energy efficiency is pushed to the highest possible level. Also dry powder is easier to be transported away for disposal.

The flash submerged arrangement is not conducive to skimming residual bitumen from the process in the same manner as the other arrangements.

Triple Cascading Arrangement

FIG.5is a schematic representation of an embodiment of the triple cascading arrangement according to the present invention.

For situations where the mature fine tailings are needed to be dried to 50-100% solids and when there is a requirement to recover residual hydrocarbon and destroy any remaining hydrocarbon in the dried solid, the triple cascading arrangement is most suitable.

In the triple cascading arrangement, a flash concentrator vessel60, a thickener vessel10and a hot water vessel30are arranged sequentially in a three-stage process. The hot water vessel30in the triple cascading arrangement behaves similarly to that described in the double submerged arrangement. The thickener vessel10behaves similarly to the thickener vessel10in the double submerged arrangement, except that the thickener vessel10also receives hot flue gas from the flash concentrator vessel60that is bubbled through the mature fine tailings bath50. The thickened mature fine tailings from the thickener vessel are pumped into the flash concentrator vessel60.

Referring toFIG.5, mature fine tailings have been pumped into a thickener vessel10from a tailing pond (not shown), the mature fine tailings have approximately 30% solids at 25° C. A fuel burner20is submerged in the thickener vessel10. Fuel (mostly CH4) is introduced into the submerged fuel burner20which then through combustion produces a flue gas comprising CO2, H2O and nitrogen. The flue gas comes out of the bottom of submerged fuel burner20and bubbles through mature fine tailings bath50is used to evaporate water from within the mature fine tailings in a direct contact mode.

The resulted more concentrated mature fine tailings (50% solid) are then pumped and sprayed into a flash concentrator vessel60near a burner or series of burners70to supply the required heat. A baffle divides the flash concentrator vessel60so as to minimize the opportunity of the flue gas to short circuit the system and become underutilized. Multiple mature fine tailings nozzles can also be installed in the flash concentrator vessel60for a larger scale application. The exhaust gas (flue gas) resulted from a burner or series of burners70near the flash concentrator vessel60needs to be kept over approximately 650° C. in order to destroy any residual hydrocarbon if that is a requirement.

A fuel burner40is submerged within a hot water vessel30, the submerged fuel burner40is used to heat water fed in from pond effluent water (PEW) from the tailing pond (not shown). The pond effluent water contains >99% H2O. Meanwhile, the moisture in the flue gas/steam coming out from the thickener vessel10is also fed into the hot water vessel30to condense its moisture to liquid and recover its latent heat in heating the pond effluent water.

Meanwhile, the thickener vessel10also receives hot flue gas/steam from the flash concentrator vessel60that is bubbled through the mature fine tailings bath50. Blowdown (with solids) from the hot water vessel30in a similar manner to the double stage submerged arrangement and similar to the flash submerged arrangement would be added to the flash concentrator vessel60.

There is the option to skim residual bitumen from the thickener vessel10and reintroduce the residual bitumen and hot water from the skimming operation back into the hot water vessel.

Should further solids removal be required, a dust collecting cyclone can be installed in between the flash concentrator vessel60and the thickener vessel30.

Within the flash concentrator vessel60, thickened mature fine tailings slurry is sprayed in near (or part of) a burner or a series of burners70. The mature fine tailings fall down through the flash concentrator vessel60while evaporation is taking place. By operating the flash concentrator vessel60at various temperatures, different levels of drying can be achieved. Operating at higher temperatures will oxidize and destroy the hydrocarbon remaining in the sand which may be desirable depending upon how the sand is used or stored after this process.

Solids are removed from the bottom of the flash concentrator vessel60by using gravity and/or mechanical means, such as being pumped, augured, etc. The flash concentrator vessel60can be elevated to allow for disposal trucks to be loaded beneath it.

Multiple mature fine tailings spray nozzles and burners can also be installed into each vessel for a larger scale application.

The triple cascading arrangement maximizes the contact between the flue gas and the mature fine tailings baths and therefore has the advantages of making each stage as efficient as possible and minimizing the solids travelling towards the hot water vessel.

The triple cascading arrangement would also be best used in situations where both hydrocarbon recovery and residual hydrocarbon destruction is required in order to better remediate the dry solid stream.

In all three arrangements, where a fuel burner, an injector or spray is used, a plurality or a series of fuel burners, injectors and sprays may be used depending on the scale of the processes. A burner could also contain a spray as an integral part thereof.

The above-described processes are also suitable for treating the other high solid streams such as fluid fine tailings (FFTs) within the bitumen process, which tend to be smaller intermediary stream that are formed within the process before the streams are sent to the tailings ponds.

There are many examples of high solids effluent streams with other industrial applications. Examples of these include:Tailings from Mining OperationsHigh solid blowdown streamsSludge from pulp and paper, municipal solid waste, etc.Red mud from the aluminum industryWastewater from other industries

The processes described in the present application are applicable to these industries.