DE102009054280A1 - Method for dissolving oil from an oil / water / solid mixture, associated device and use of the method - Google Patents

Abstract

In the usual mining process of oil sand with above-ground excavation, the oil sand is mined in a mill after being excavated and transported to the processing plant by means of trucks and then slurried with water to transport the hydrated material to the extraction plant. In any case, the hydration transport already leads to a reduction in the surface tension of the bitumen around the individual grains. In the prior art, flotation or separation boilers are used, steam being used. According to the invention, spontaneous emulsion splitting of the oil-water-sand mixture is forced, producing three different material phases, of which the first phase essentially contains the oil. A pressure cell is provided for this in the associated device.

Description

The invention relates to a method for dissolving oil from an oil / water / solid mixture by forced spontaneous demulsification. In addition, the invention also relates to the apparatus for carrying out the method. Furthermore, the invention relates to related use of this method and the device constructed according to the invention.

The invention relates in detail to the preparation of specifically oil-water-sand mixtures and emulsions. These include mixtures and emulsions with high oil contents (oil = mineral oils, bitumen, tars, etc. up to a high proportion by mass up to 99%) as well as emulsions with predominant water content (mass fraction up to about 99%, ie aqueous solutions) , The mixtures and emulsions may additionally have a high mineral solids content, ie. H. Sand or particles of the order of up to 50% by weight, which is generally referred to as oil sands or oil shale.

As is known, a preparation of such mixtures or emulsions can be effected predominantly by mixing in an adjuvant, in particular propane, at elevated pressure, the emulsion having previously been temporarily exposed to higher temperatures of up to 100 ° C. (so-called preconditioning). The result is a spontaneous separation into an oily phase, a water-containing phase and an aqueous phase with a high solids content. This phenomenon is known in the art and is also commonly referred to as "spontaneous emulsion cleavage".

As an area of application, the technique treated in the present context particularly but not exclusively aims at the mining and recovery of bitumen and / or heavy oil from naturally occurring oil sands. Alternatively, with the same procedure, the treatment of oil-contaminated wastewater is possible, as they arise in particular during the degradation of oil sands.

In the current degradation of oil sands, as he z. For example, in northern Canada in the province of Alberta, mixtures of oil, sand and water containing high levels of high-viscosity oil and sand are produced at an early stage of mining or subsequent treatment. At a later stage of the treatment, these are mixtures of aqueous solutions with still comparatively high oil content, in the single-digit percentage range, as well as mineral and other impurities. These aqueous mixtures, some of which are in the form of an emulsion, are currently disposed of in so-called "tailing ponds", regardless of the raw material oil still contained. The oil contained therein becomes a problematic commodity.

Particular problems occur in the latter approach in that it is rather poorly soluble hydrocarbons with high surface tension. In order to be able to separate the bitumen, which encloses each grain of sand, the surface tension must be overcome.

Auxiliaries, in particular auxiliary gases, are used in the prior art. As auxiliary gas, for example, CO ₂ comes into question, which is not considered in this context. As alternative auxiliary gases, volatile hydrocarbon compounds are relevant. For example, this describes WO 2004/080567 ( DE 10 31 1283 A1 ) a process for emulsion splitting of oil-water mixtures under elevated pressure and temperature by means of a fissile material. However, from this only the use of aliphatic hydrocarbons is generally removable. Besides that is from the WO 1996/011043 A1 a high-pressure spray extraction for the recovery of recyclables removed.

A supercritical extraction by means of propane gas is mentioned in the publication by Eisenbach (1980). This method proposes a combination of extraction and distillation using a supercritical gas for extraction.

From the WO 2003/008524 A1 is a method for the purification of waste oils / oily residues by means of supercritical gases removable. Furthermore, from the DE 100 15 049 C1 (= EP 1 272 253 B1 ) a process for the treatment of resulting in the metalworking, consisting of a mixture of fine scale and water rolling sludge by separating the water and oil components from the Feinzunder specified, wherein the sludge in a container with a introduced in supercritical phase into the container destruktionsmittels brought into contact becomes.

Further information on the prior art with supercritical gas extraction are from the US Pat. No. 6,821,413 B1 , from the US 2002/0011442 A1 and the WO 2001/072394 A1 and the secondary literature there removable.

Based on the above prior art, it is an object of the invention to provide an improved method for dissolving oil from an oil / water / solid mixture, as well as to provide an associated device. Furthermore, should specific applications for the new method and associated apparatus.

The object is achieved by the measures of claim 1. An associated device is specified in claim 9. Specific advantageous uses emerge from the claims 12 and 13. Further developments of the method, the device and the associated uses are given in the respective dependent claims.

The invention particularly relates to the use of an adjuvant in subcritical conditions (pressure and temperature) for splitting off oil from oil sand mixtures, oil sands mixtures meaning all mixtures of oil and / or sand and / or water. In this case, the excipient is dissolved in a certain concentration in the emulsion under pressure. It was recognized that the emulsionsbrechende effect by the addition of the excipient based on the fact that the alkane acts as a solvent and removes oil from the emulsion extractively. Furthermore, the viscosity of the phases decreases when saturated with the excipient and in addition decreases the interfacial tension at the phase boundary, whereby the phase separation is significantly accelerated.

It is particularly advantageous if an alkane, for example propane, or a mixture of alkanes is used as adjuvant. Subcritical conditions may exist, for example, by processing at room temperature and pressures of less than 100 bar. Suitably, the excipient or the mixture which constitutes the excipient is gaseous.

A distinct advantage is achieved when a second adjuvant is used in addition to the adjuvant. If toluene is used as the second auxiliary, an increase in the separated oil content is achieved at constant temperature and pressure conditions. As an alternative or in addition to toluene, it is also possible to use another aromatic hydrocarbon, for example an ortho or meta-xylene. Again, it is possible to use a mixture of aromatic hydrocarbons.

Further details and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the drawing in conjunction with the claims. This show schematically

1 the dependence on cumulated extracted amount of oil as a function of the addition of auxiliaries,

2 a flow chart for the extraction of oil fractions from oil / sand / water emulsions and

3 an apparatus realization of the flow chart after 2 ,

Exemplary embodiments which include an addition of propane as an adjuvant or an addition of propane as an adjuvant and toluene as a second adjuvant are considered below. The addition takes place in subcritical conditions, ie at pressures and temperatures that are below the critical conditions for the propane. The addition of the excipients propane alone or propane and toluene causes a spontaneous demulsification of an oil / solid / water emulsion in three phases 24 ... 26 , In this case, a pressure of p = 90 bar is required.

The first phase 24 is an oil-enriched C ₃ H ₈ phase. This is yellowish in experimental experiments, but clear because it exists as a solution. The second phase 25 By contrast, it contains mostly water, which is clear. The third phase 26 contains the part insoluble in C ₃ H ₈ and water, which contains sand, so that a sand / water mixture is present. In all phases 24 ... 26 is missing - with the exception of minimal residual amounts, for example, in the per mille range - one or two of the original components of the oil sands or oil shale.

The addition of a second adjuvant, optionally to the oil / water / sand emulsion or the propane excipient, further achieves some improvements: After the addition of small amounts of, for example, toluene as the second adjuvant is already at room temperature and under critical conditions, again at a pressure of 90 bar achieved a significantly improved solubility or loading of hydrocarbons contained in the oil in the propane. The load is more than twice as high as in tests at the same pressure and temperature, but without toluene. The achievable load and the rate of mass transfer in propane of hydrocarbons is even higher than in tests with supercritical propane (for example at a pressure of 90 bar and a temperature of 127 ° C) without toluene.

The results of these experiments are in part in 1 played. Plotted on the abscissa is the mass of propane in grams and on the ordinate the mass of oil in grams. The pressure used was 90 bar in all experiments shown. A first graph 11 shows the result when using propane as an excipient at room temperature. A second graph 12 shows the result at 67 ° C, also with propane as an excipient. A third graph 13 shows the result at 127 ° C, also with propane as an excipient. A fourth graph 14 shows the result at room temperature, about 20-22 ° C, with the addition of a small proportion of toluene as the second auxiliary. It is essential that - as already explained above - even a slight addition of toluene noticeably improves the yield of oil, as in the fourth graph 14 seen.

In 2 a flow diagram for carrying out the method according to which from the oil sands is shown 27 as input material individual phases 24 . 25 . 26 different composition can be obtained as a result. The oil sands 27 gets into a stage 21 introduced for Anmaischung, in the same time water 28 is added. Optionally, this mashing is heated to a predetermined temperature. About a hydrotransport 29 The mixture thus pretreated is placed in a unit for processing 23 given. The unit 23 has means for mixing 30 the substances and an associated unit for compaction 22 , Furthermore, a unit for separation 31 integrated. The propane 32 is about the unit for compaction 22 added. Optionally, toluene 33 added. After discharge from the unit for compaction 22 and relaxation 34 This results in the phases already defined above 24 . 25 and 26 with oil, water and sand.

Essentially the same is based on the 3 shown for the individual material flows. Mean 40 the suspension / emulsion of the mixture oil / sand / water. 41 means the extracted oil fraction and 42 the water fraction. 43 is the sand fraction. With 44 is the optional addition of toluene referred to as a second excipient. It is essential that the reaction apparatus as a closed pressure cell 50 is executed, the part 51 a so-called decanter is. The decanter is advantageously integrated in the pressure cell itself.

Furthermore, a separation stage 52 for solid / liquid present, which is designed as a hydrocyclone. Further, a separation stage 54 for oil / excipient, which is designed as a simple pressure relief stage.

In the apparatus described above based 3 individual zones result: one zone 61 the mixing of the supplied emulsion of oil / sand / water and the first auxiliary, a settling zone 62 ie rest zone for the third phase 26 from sand / water, a settling zone 63 , ie quiet zone for the first phase 24 ie water, and a settling zone 64 in the sense of a rest area for the second phase 25 ie the oil fraction. There is also a zone for the excipient 65 which is returned, a zone for the settled sand 66 and the purified water 68 , Another zone for the liquid phase from the oil fraction is 67 in the separation stage 54 ,

The streams from the hydrocyclone 52 and the decanter 51 can be removed either separately or combined.

The pressure-tight cell is expedient 50 Valves upstream and downstream, via the upstream three-way valve, the different fractions of the oil sand extraction, such as the oil sand itself or the residues of primary separation and the so-called tailings are entered. Furthermore, here also a bitumen / water / emulsion from a SAGD (= Steam Assisted Gravity Drainage) method is added. Furthermore, it is expedient to supply the auxiliary gas or gases by means of a pump. By way of example, a four-way outlet valve, in particular the product and the waste, ie water / sludge, can be led away.

In the method described above, the state of the art is simplified in that a one-step extraction can take place. The adjuvant is used in subcritical conditions. Advantageously, an additional adjuvant can be used. In this case, the oil-sand-water mixture can be heated after the hydrotransport and be applied in a closed cell with moderate pressure of the excipient, so that it is the spontaneous formation of the three phases 24 ... 26 comes. This process benefits from the fact that the viscosity of the suspension is reduced by the mixed propane under pressure and thus the settling of phases of different density, for. B. of solids, is accelerated. The deduction of the different phases 24 ... 26 takes place advantageously by means of a decanter. This allows the three phases directly 24 ... 26 to be provided. After the separation of the phases 24 ... 26 can from the first phase 24 the excipient by simple pressure release, z. B. in a closed container, recovered. Propane goes into the gaseous state at room temperature during relaxation. The oil content remains as a high-boiling liquid phase 25 back and can then be fed almost anhydrous further processing. The excipient propane is advantageously returned to the circulation.

Due to the viscosity-reducing effect of the propane, it may be advantageous to relax the pressure only at the location of the further processing of the oil fraction and thus exploit the improved transport properties due to the reduced viscosity. The regenerated excipient can be transported as gas or liquefied in a simple manner over greater distances.

Since "in situ" bitumen production methods usually employ methods in which bitumen-water emulsions are produced, eg. B. in the SAGD process or in the CSS process, the sand remains in the reservoir. Thus, the delivery pipe, the pressure cell described above 50 dine directly. Usually, the water-bitumen emulsion arrives already at temperatures of 25 to 70 ° C at the treatment plant, so that the step of further warming does not appear mandatory.

In summary, it is assumed that in the usual mining process of oil sands with over-excavation the oil sands after excavating and transporting to the treatment plant by means of trucks crushed in a mill and then slurried with water for transport of the hydrated material to the extraction plant. In any case, hydration transport already leads to a reduction in the surface tension of the bitumen around the individual grains. In the prior art, flotation or separation boilers are used, with steam being used. According to the invention, spontaneous demulsification of the oil-water-sand mixture is forced, resulting in the three described different material phases, the first phase of which substantially contains the oil. In the associated device is a pressure cell for this purpose 50 available.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2004/080567 [0007]
• DE 10311283 A1 [0007]
• WO 1996/011043 A1 [0007]
• WO 2003/008524 A1 [0009]
• DE 10015049 C1 [0009]
• EP 1272253 B1 [0009]
• US 6821413 B1 [0010]
• US 2002/0011442 Al [0010]
• WO 2001/072394 A1 [0010]

Claims (13)

Method for extracting oil from a mixture of a mixture of oil, water and solid fractions by forced spontaneous demulsification with the following process steps: Introducing at least one first auxiliary into the mixture, Mixing the first adjuvant with the mixture until a spontaneous demulsification of the emulsion takes place in three phases, of which the first phase is essentially oil and the adjuvant, the second phase is essentially water and the third phase is essentially water and the solid is - mechanical separation of the three phases and - Separation of the oil from the first phase of the first excipient. Process according to Claim 1, in which the first auxiliary used is propane or another alkane or a mixture of alkanes. The method of claim 2, wherein the propane is introduced at pressures below 100 bar and room temperature. Method according to one of the preceding claims, wherein in addition to the propane, a second excipient is used. Process according to Claim 4, in which the second auxiliary used is an aromatic hydrocarbon, in particular toluene or an ortho / meta-xylene. Process according to any one of the preceding claims, in which the auxiliary agent (s) are recovered by the action of pressure from the separated first phase. A method according to claim 6, characterized in that the pressure is released only at the location of further processing of the first phase. Method according to one of the preceding claims, in which the second and third phases are treated by filtration or by means of a hydrocyclone. Device for carrying out the method according to one of the preceding claims with a unit for mixing oil sands ( 27 ) with water ( 28 ) and for the supply of heat energy, wherein furthermore a unit ( 30 . 50 ) are present for mixing the water / solid mixture with a first excipient and separate output units, wherein the unit ( 30 . 50 ) mixed for mixing the first excipient with subcritical conditions and the first excipient, a separation of individual material phases ( 24 ... 26 ), of which the first phase ( 24 ) mainly oil, the second phase ( 25 ) predominantly water and the third phase ( 26 ) contain predominantly solid, and wherein the individual material phases ( 24 ... 26 ) are in the separate output units gebbar. Device according to claim 11, comprising means ( 33 ) for the addition of the second excipient. Apparatus according to claim 10, characterized in that the unit for mixing a closed pressure cell ( 50 ). Use of a method according to any one of claims 1 to 8 or an apparatus according to claims 9 to 11 for the separation of oil from naturally occurring oil sands or oil shales. Use of a method according to one of claims 1 to 8 or a device according to claim 9 to 11 for the treatment of oil-contaminated water.

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