Method and device for extracting oil from oil-containing substances using solvent and recovering solvent

Abstract

A method for extracting oil from an oil-containing substance using a solvent and recovering the solvent, comprising: (a) mixing the oil-containing substance with a solvent, and separating to obtain a liquid mixture containing the solvent and the oil, and other substances; (b) mixing the liquid mixture with water to obtain a first aqueous mixture; (c) flashing the first aqueous mixture to obtain gas-phase oils and a second aqueous mixture; (d) performing a first liquid-liquid separation on the second aqueous mixture to obtain liquid-phase oils and a third aqueous mixture; and (e) performing a second liquid-liquid separation on the third aqueous mixture to obtain recovered water and recovered solvent. The present invention also relates to a corresponding device.

Description

Technical Field

[0001] The invention relates to the technical field of separation of mixtures, and in particular to a method and a device for extracting oil from oil-containing substances using a solvent and recovering the solvent. Background Art

[0002] Chemical solvent extraction is a common method for separating oil from oil-containing substances. Specifically, the extraction process includes: using a chemical solvent that is miscible with oil, fully mixing the chemical solvent with the oil-containing substance, combining the oil in the oil-containing substance with the chemical solvent to obtain an oil-containing solvent, then separating the oil-containing solvent from the remaining substance after extraction, and then separating the oil and solvent in the oil-containing solvent to obtain a recovered solvent (or regenerated solvent) and recovered oil, wherein the recovered solvent can be used again in the extraction process.

[0003] Chemical solvent extraction can be used to treat various forms of oily substances, such as solid, slurry, viscous liquid, suspended solid, or liquid. Examples of oily substances include: municipal sludge, sewage treatment plant sludge, oily substances generated during crude oil extraction, storage, transportation, and processing (including drilling cuttings, water-based drilling mud, oil-based drilling mud, ground oil spills, ground oil sludge, oil field produced water, tank bottom oil sludge, tank cleaning oil sludge, refinery "three muds", oil-contaminated soil, etc.), oil sands, oil sand tailings, cutting fluid waste used in mechanical processing, catering waste (also known as kitchen waste), animal and plant bodies (such as peanuts and other nuts, fruit peels, petals, meat, algae), and microorganisms.

[0004] Solvent extraction has been widely used for the separation or extraction of oils. In the step of separating the oil and solvent in the oil-containing solvent, evaporation or distillation is usually used according to the difference in boiling points between the oil and the solvent to obtain the recovered solvent and the recovered oil. However, when the boiling points of the extracted oil and the solvent are not much different, conventional evaporation or distillation operations often cannot effectively separate the oil and the solvent. If the recovered solvent with a high oil content is reused in the extraction operation, the extraction efficiency will also be affected. Therefore, in view of the above problems, a solution is needed, which can effectively separate the solvent and oil with similar boiling points after using a solvent to extract the oil in the oil-containing substance, so as to obtain a recovered solvent with higher purity. Summary of the invention

[0005] The present invention provides a method and a corresponding device for extracting oil from oil-containing substances using a solvent and recovering the solvent. A special organic solvent is selected to separate the solvent and the oil with similar boiling points to obtain a high-purity recovered solvent.

[0006] The method of the present invention comprises the following steps:

[0007] (a) mixing an oil-containing substance with a solvent and separating to obtain a liquid mixture comprising the solvent and the oil, and other substances, wherein the miscibility of the solvent with water decreases with increasing temperature;

[0008] (b) mixing the liquid mixture with water to obtain a first aqueous mixture, wherein the weight ratio of the water to the solvent in the liquid mixture is in the range of 2:1 to 10:1;

[0009] (c) flashing the first aqueous mixture at a temperature in the range of 0°C to 45°C to obtain gas phase oil and a second aqueous mixture;

[0010] (d) subjecting the second aqueous mixture to a first liquid-liquid separation at a temperature in the range of 0° C. to 45° C. to obtain a liquid phase oil and a third aqueous mixture; and

[0011] (e) subjecting the third aqueous mixture to a second liquid-liquid separation at a temperature in the range of 50° C. to 85° C. to obtain recovered water and recovered solvent.

[0012] The device of the present invention is used to carry out the above-mentioned method of using a solvent to extract oil from an oil-containing substance and recovering the solvent, and the device comprises: an extraction unit, comprising an oil-containing substance inlet, a solvent inlet, a liquid mixture outlet and other substance outlets, the liquid mixture outlet being used to discharge a liquid mixture containing solvent and oil, wherein the miscibility of the solvent with water decreases with increasing temperature; a mixing unit, connected to the liquid mixture outlet of the extraction unit, receiving the liquid mixture, and used to mix the liquid mixture with water to obtain a first aqueous mixture, wherein the weight ratio of the water to the solvent in the liquid mixture is in the range of 2:1 to 10:1; a flash unit, connected to the The mixing unit is connected to the mixing unit, receiving the first aqueous mixture, and is used to flash the first aqueous mixture in the range of 0°C to 45°C to obtain gas-phase oil and a second aqueous mixture; the first liquid-liquid separation unit is connected to the flash unit, receiving the second aqueous mixture, and is used to perform liquid-liquid separation on the second aqueous mixture in the range of 0°C to 45°C to obtain liquid-phase oil and a third aqueous mixture; and the second liquid-liquid separation unit is connected to the first liquid-liquid separation unit, receiving the third aqueous mixture, and is used to perform a second liquid-liquid separation on the third aqueous mixture in the range of 50°C to 85°C to obtain recovered water and recovered solvent.

[0013] The technical solution of the present invention aims at the problem that in the process of extracting oils or organic matter with organic solvents, the extracted substances and the solvent have similar boiling points and are difficult to separate, and the recovered solvent has low purity. By creatively selecting the solvent and designing the separation process, the solvent and the extracted oil can be effectively separated to obtain a recovered solvent with higher purity, so that the recovered solvent can be reused in the extraction process. The solvent used in the technical solution of the present invention has the characteristic that its miscibility with water decreases with increasing temperature. Thus, by changing the temperature and thus the miscibility between the solvent and water, the separation of oil, water and solvent can be achieved through liquid-liquid separation operation. The technical solution of the present invention is easy to operate, has low separation energy consumption, does not require complex equipment, and has low investment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The accompanying drawings and the following detailed description are used to help understand the features and advantages of the present invention. Figure 1 The figure shows a schematic diagram of a device for extracting oil from oil-containing substances using a solvent and recovering the solvent according to one embodiment of the present invention, wherein the direction of the arrow represents the direction of material flow. DETAILED DESCRIPTION

[0015] Unless otherwise clearly defined in this application, the meaning of the scientific and technical terms used is the meaning commonly understood by those skilled in the art of the technology described in this application. The words "include", "comprise", "have" or "contain" and similar words used in this application mean that in addition to the items listed thereafter and their equivalents, other items may also be within the scope.

[0016] Approximate terms in this application are used to modify quantity, indicating that the present invention is not limited to the specific quantity, but also include the part of the modification that is close to the quantity, acceptable, and does not cause the change of the relevant basic function. Accordingly, a numerical value is modified with "about", "approximately", "about", etc., meaning that the present invention is not limited to the exact numerical value. In certain embodiments, the approximate terms may correspond to the accuracy of the instrument for measuring the numerical value. The numerical range in the present invention can be combined and / or interchanged, and unless otherwise clearly stated, the numerical range includes all numerical subranges covered therein.

[0017] In the specification and claims, unless clearly otherwise indicated, the singular and plural forms of all items are not limited. The words "first", "second" and similar words used in the specification and claims of this application do not indicate any order, quantity or importance, but are only used to distinguish different materials or embodiments.

[0018] Unless the context clearly indicates otherwise, the terms "or" and "alternatively" do not mean exclusive but rather mean that at least one of the mentioned items (eg, components) is present and include the case where combinations of the mentioned items can be present.

[0019] References to "some embodiments" and the like in this specification indicate that a specific element (e.g., feature, structure, and / or characteristic) related to the present invention is included in at least one embodiment described in this specification, and may or may not appear in other embodiments. In addition, it should be understood that the inventive elements may be combined in any appropriate manner.

[0020] The "oil" or "oils" mentioned in this application refers to a hydrophobic substance that is liquid at room temperature, and can refer to all organic compounds that are insoluble in water, not limited to hydrocarbons. In some embodiments, the oil present in the oil-containing substance can be one or more, including but not limited to: any one or more of petroleum, asphalt, animal oil, vegetable oil, silicone oil or lubricating oil.

[0021] The "oil-containing substance" or similar terms mentioned in this application refer to substances containing oil and other substances (such as water, solids, etc.), which exist in solid, slurry, viscous liquid, suspension, or liquid form, and the oil content therein is generally measured by weight percentage, for example, substances with an oil content greater than 1%. In some embodiments, the oil-containing substance includes drilling cuttings, water-based drilling mud, oil-based drilling mud, ground oil spills, ground oil mud, oil field produced water, tank bottom oil mud, tank cleaning oil mud, refinery "three muds", oil-contaminated soil, etc., generated during crude oil production, storage, transportation, processing and use, among others, wherein the refinery "three muds" include oil separator bottom mud, flotation tank scum and residual activated sludge. In some embodiments, the oil-containing and water-containing substance includes sedimentary sand rich in natural asphalt in nature, called oil sand or asphalt sand, and the method and device for treating oil-containing substances of the present invention can be used for oil sand mining or the treatment of oil sand tailings. In some embodiments, the oil-containing substance includes cutting fluid waste generated during metal processing. In some other embodiments, the oil-containing substances include catering waste, municipal sludge, animals and plants, microorganisms, etc., wherein the animals and plants may include meat, fur, nuts, spice crops, traditional Chinese medicine, algae, etc., and examples of extracting microorganisms include extracting antibiotics from bacteria.

[0022] The embodiments of the present invention are described below with reference to the accompanying drawings. Figure 1 The schematic diagram of a device for extracting oil from oil-containing substances and recovering solvent using a solvent according to an embodiment of the present invention is shown. The device mainly includes: an extraction unit 101, a distillation unit 103, a mixing unit 105, a flash unit 107, a first liquid-liquid separation unit 109, a second liquid-liquid separation unit 111, and some connecting pipes and material storage tanks. The structure, connection method and function of each device unit are described in detail below.

[0023] The extraction unit 101 includes an oil-containing substance inlet, a solvent inlet, a liquid mixture outlet and other substance outlets, wherein the liquid mixture outlet is used to discharge a liquid mixture containing solvent and oil. The oil-containing substance inlet and the solvent inlet may be the same inlet. The extraction unit 101 has two functions of mixing and separation. Therefore, in some embodiments, the extraction unit 101 includes a mixing element (e.g., a stirring rod) and a separation element (e.g., a centrifugal device, a filter press device, a suction filter device, a sedimentation device, etc.), etc. These elements may exist independently and be interconnected, or may be integrated into a whole.

[0024] The distillation unit 103 is connected to the extraction unit 101 through a pipeline, and receives the liquid mixture from the extraction unit 101. The distillation unit 103 includes a common distillation device, which heats the liquid mixture containing the solvent and the oil, and separates it into at least two components according to different boiling points, wherein the component with a higher solvent content (i.e., the oil-containing solvent, including the solvent and the oil with a boiling point close to that of the solvent) is passed into the subsequent mixing unit 105, and the other components can enter the oil storage tank 104. In some embodiments, the distillation unit 103 can be replaced by an evaporation unit and a condensation unit, and the evaporation unit and the condensation unit are connected through a pipeline. For example, when the liquid mixture contains heavy oil with a higher boiling point, the light hydrocarbons with a lower boiling point evaporate together with the solvent and enter the condensation unit to obtain a mixture of light hydrocarbons and solvent (i.e., the oil-containing solvent).

[0025] The mixing unit 105 is connected to the distillation unit 103 through a pipeline, and receives the oil-containing solvent from the distillation unit 103. Water is introduced into the mixing unit 105 to mix the oil-containing solvent with the water to obtain a first water-containing mixture.

[0026] The flash unit 107 is connected to the mixing unit 105 through a pipeline, and receives the first aqueous mixture from the mixing unit 105. In the flash unit 107, the first aqueous mixture is flashed at a temperature in the range of 0°C to 45°C to obtain gaseous oil and a second aqueous mixture, wherein the gaseous oil is stored in the gaseous oil storage tank 108.

[0027] The first liquid-liquid separation unit 109 is connected to the flash unit 107 through a pipeline, and receives the second aqueous mixture from the flash unit. In the first liquid-liquid separation unit 109, the temperature is controlled within the range of 0°C to 45°C, and the second aqueous mixture is subjected to liquid-liquid separation to obtain liquid phase oil and a third aqueous mixture.

[0028] The second liquid-liquid separation unit 111 is connected to the first liquid-liquid separation unit 109 through a pipeline, and receives the third aqueous mixture from the first liquid-liquid separation unit 109. In the second liquid-liquid separation unit 111, the temperature is controlled within the range of 50°C to 85°C, and the third aqueous mixture is subjected to a second liquid-liquid separation to obtain recovered water and recovered solvent. The recovered water can be refluxed to the mixing unit 105 through the reflux pipeline 121 for reuse. The recovered solvent can also be refluxed to the extraction unit 101 through the reflux pipeline 123 for reuse.

[0029] The first liquid-liquid separation unit 109 and the second liquid-liquid separation unit 111 can independently select various liquid-liquid separation devices well known to those skilled in the art.

[0030] In some embodiments of the present invention, in the extraction unit 101, the boiling point of the oil extracted by the solvent is close to the boiling point of the solvent used. At this time, if the liquid mixture from the extraction unit 101 is still distilled by the distillation unit 103, it is basically impossible to separate it. In this case, the liquid mixture can be directly introduced into the mixing unit 105 without passing through the distillation unit 103. Therefore, in some embodiments of the present invention, the device for extracting oil from oil-containing substances using a solvent and recovering the solvent does not include a distillation device.

[0031] Through the description of the above embodiments, it can be seen that the method of using a solvent to extract oil from an oil-containing substance and recovering the solvent in the embodiment of the present invention generally includes the following steps:

[0032] (a) mixing an oily substance with a solvent and separating to obtain a liquid mixture comprising the solvent and the oil, and other substances;

[0033] (f) evaporating or distilling the liquid mixture to obtain at least one recovered oil and an oil-containing solvent, wherein the oil-containing solvent includes oils having a boiling point similar to and / or lower than the boiling point of the solvent;

[0034] (b) mixing the oil-containing solvent with water to obtain a first aqueous mixture;

[0035] (c) flashing the first aqueous mixture at a temperature in the range of 0°C to 45°C to obtain gas phase oil and a second aqueous mixture;

[0036] (d) subjecting the second aqueous mixture to a first liquid-liquid separation at a temperature in the range of 0° C. to 45° C. to obtain a liquid phase oil and a third aqueous mixture;

[0037] (e) subjecting the third aqueous mixture to a second liquid-liquid separation at a temperature in the range of 50° C. to 85° C. to obtain recovered water and recovered solvent;

[0038] (g) returning the recovered water to step (b) to mix with the liquid mixture; and

[0039] (h) refluxing the recovered solvent into step (a) to mix with the oil-containing substance.

[0040] Among them, the above steps (a), (b), (c), (d), (e) are necessary steps, while steps (f), (g), (h) are optional steps.

[0041] One of the important key points that the technical solution of the present invention can achieve the recovery of high-purity solvents is that the solvent used has the characteristic that the solubility with water decreases as the temperature increases. Therefore, when separating the solvent and the oils with a boiling point close to the solvent, it can be achieved by adding water, changing the temperature, and separating the liquid and liquid. The amount of water added in step (b) is related to the amount of solvent in the liquid mixture or the oil-containing solvent, that is, the water added needs to be sufficient to bring out the solvent therein. In an embodiment of the present invention, the amount of water added needs to satisfy: the weight ratio of water to the solvent in the liquid mixture or the oil-containing solvent is in the range of 2: 1 to 10: 1, preferably in the range of 2: 1 to 6: 1. The solvent of the embodiment of the present invention includes an amine solvent, such as diisopropylamine or triethylamine.

[0042] The flash evaporation in step (c) is carried out at a relatively low temperature, the main purpose of which is to separate the oils with a relatively low boiling point. The temperature and pressure of the flash evaporation can be adjusted to carry out the flash evaporation with relatively low energy consumption. The temperature of the flash evaporation is generally in the range of 0°C to 45°C, preferably in the range of 0°C to 30°C.

[0043] The first liquid-liquid separation in step (d) is carried out at a relatively low temperature, generally in the range of 0° C. to 45° C., preferably in the range of 0° C. to 20° C. The second aqueous mixture contains three components: water, oil, and solvent. Since the solvent has a high miscibility with water at low temperatures, the solvent and water mixture are one phase, and the oil is another phase. The first liquid-liquid separation is performed to obtain liquid phase oil and the third aqueous mixture.

[0044] The second liquid-liquid separation in step (e) is carried out at a relatively high temperature, generally in the range of 50° C. to 85° C., preferably in the range of 70° C. to 75° C. The third aqueous mixture contains two components, water and solvent. Since the solvent has a low miscibility with water at high temperature, it is separated into two phases. The liquid phase oil and the third aqueous mixture are obtained by the second liquid-liquid separation.

[0045] In an embodiment of the present invention, the purity of the solvent recovered by the above method is greater than 90%, preferably greater than 92%.

[0046] Experimental Example

[0047] In this experimental example, diisopropylamine is used as a solvent, and the boiling point of diisopropylamine is 84°C. Naphtha with a boiling point range of 60°C to 120°C is used as the extracted oil substance. The two are mixed in a certain proportion as the oil-containing solvent to be separated. The technical solution proposed by the present invention is used to perform separation treatment in four steps: adding water for mixing, flash evaporation, first liquid-liquid separation, and second liquid-liquid separation.

[0048] Example 1: The oil-containing solvent composition is 50wt% naphtha+50wt% diisopropylamine. The data and results are shown in Table 1.

[0049] Table 1

[0050]

[0051] Example 2: The oil-containing solvent composition is 40wt% naphtha+60wt% diisopropylamine. The data and results are shown in Table 2.

[0052] Table 2

[0053]

[0054] Example 3: The oil-containing solvent composition is 30wt% naphtha+70wt% diisopropylamine. The data and results are shown in Table 3.

[0055] Table 3

[0056]

[0057] The above three examples are respectively used to separate three types of diisopropylamine containing naphtha with oil contents of 50wt%, 40wt% and 30wt%. The purity of the final recovered solvent is more than 90%, which is much higher than the separation efficiency of traditional distillation, and the energy consumption is also low.

[0058] The above-mentioned device and method for treating oily and water-containing substances are only preferred embodiments of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for extracting oil from an oily substance using a solvent and recovering the solvent, characterized in that: The method comprises the following steps: (a) mixing an oil-containing substance with a solvent and separating to obtain a liquid mixture comprising the solvent and the oil, and other substances, wherein the miscibility of the solvent with water decreases with increasing temperature; (b) mixing the liquid mixture with water to obtain a first aqueous mixture, wherein the weight ratio of the water to the solvent in the liquid mixture is in the range of 2:1 to 10:1; (c) flashing the first aqueous mixture at a temperature in the range of 0°C to 45°C to obtain gas phase oil and a second aqueous mixture; (d) subjecting the second aqueous mixture to a first liquid-liquid separation at a temperature in the range of 0° C. to 45° C. to obtain a liquid phase oil and a third aqueous mixture; and (e) subjecting the third aqueous mixture to a second liquid-liquid separation at a temperature in the range of 50° C. to 85° C. to obtain recovered water and recovered solvent; wherein the solvent is diisopropylamine or triethylamine.

2. The method according to claim 1, characterized in that The method further comprises a step (f), located between steps (a) and (b): (f) evaporating or distilling the liquid mixture to obtain at least one recovered oil and an oil-containing solvent, wherein the oil-containing solvent includes oils having a boiling point close to and / or lower than the boiling point of the solvent, such that the oil-containing solvent is mixed with water in step (b).

3. The method according to claim 1, characterized in that The method further comprises step (g): (g) returning the recovered water to the step (b) to mix with the liquid mixture.

4. The method according to claim 1, characterized in that: The purity of the recovered solvent is greater than 90%.

5. The method according to claim 1, characterized in that The operating temperature of step (c) is in the range of 0°C to 30°C, the operating temperature of step (d) is in the range of 0°C to 20°C, and the operating temperature of step (e) is in the range of 70°C to 75°C.

6. The method according to claim 1, characterized in that The oil-containing substances include one or more selected from municipal sludge, sewage treatment plant sludge, drilling cuttings, water-based drilling mud, oil-based drilling mud, ground oil spills, fallen oil sludge, oil field produced water, tank bottom oil sludge, tank cleaning oil sludge, refinery "three muds", oil-contaminated soil, oil sands, oil sand tailings, cutting fluid waste used in mechanical processing, catering waste, animals and plants, and microorganisms.

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