JP5319371B2 - Oil component extraction method and method for producing oily material - Google Patents

Description

  The present invention relates to an oil extraction method and an oily material manufacturing method, and more particularly, to an oil extraction method from a target material containing a large amount of water in addition to the oil and a method of manufacturing an oily material using such a target material as a raw material.

  Conventionally, for the purpose of obtaining a product with a reduced oil content by removing the oil content from the oil-containing material, or for using the oil content obtained by extracting the oil content from the oil-containing material as the oil-based material As an example, an oil component is extracted from a target material containing an oil component using an extraction solvent.

  When performing such extraction, if the target material contains a large amount of moisture in addition to the oil, it is very difficult to extract the oil. Further, when substances such as acetone and isopropanol are used as the extraction solvent, there arises a problem that these substances remain in the processed material and cause contamination different from the substances removed by extraction.

  For example, when soil containing harmful oils such as heavy oil, benzene, and cyanide and containing a large amount of moisture is treated to be rendered harmless, there is a problem that moisture in the soil hinders extraction. In addition, if the extraction solvent remains in the soil, soil contamination will occur.

  Also, for example, algae such as cuttlefish have the ability to produce a large amount of oil, and can be cultivated in water and do not require farmland. Therefore, oil from such algae can be extracted and used as biofuel. Proposed. However, the cultivated algae contain a large amount of water in the state of being taken out from the water, and still contain a large amount of water such as 50% by mass or more even when subjected to treatment such as centrifugation or mechanical pressing. When oil is extracted from such a large amount of water-containing algae, a large amount of energy is required, which is not practical for fuel production. Further, if a harmful extraction solvent remains in the deoiled algae, the deoiled algae must be treated as harmful waste, which increases the load for treatment.

  By the way, the present inventors have proposed dehydrating with low energy by using dimethyl ether as a water extraction solvent and circulating it in a specific manner as a method for dehydrating a material containing water (patent) Reference 1). If this dehydration method is applied to extract oil and moisture from a target material containing a large amount of moisture in addition to the oil, extraction of the oil requires a large amount of energy.

International Publication No. 2003/101579

  An object of the present invention is to extract an oil from a target material containing a large amount of water in addition to the oil, and to efficiently perform the extraction of an oil and a method for producing an oil-based material with less contamination of a processed product. And providing a system for such a method.

According to the present invention, the following (1) to (12) are provided.
(1) A method for extracting oil from a target material containing moisture and oil,
(A) The target material is brought into contact with dimethyl ether in a liquid state, the oil in the target material is transferred into dimethyl ether, a mixture (i) of dimethyl ether and the oil, and a deoiled target material ( ii) and (B) vaporizing dimethyl ether in said mixture (i), thereby separating dimethyl ether from said mixture (i),
In the step (A), at least a part of the contact operation between the target material and the liquid dimethyl ether is performed in a state where a saturated amount of water is dissolved in the dimethyl ether.
(2) (C) liquefying the dimethyl ether separated in the step (B) and sending it to the step (A) again,
In the step (B), the method further includes recovering work performed in the external environment by vaporization of dimethyl ether, and supplying the work to the step (C) as all or part of the power of the step (C). The method according to 1).
(3) The method according to (1) or (2), wherein the mixture (i) supplied to the step (B) contains an oil component having a concentration higher than the oil content in the target material.
(4) The method according to any one of (1) to (3), wherein the target material subjected to the step (A) contains 50% by mass or more of moisture.
(5) The method according to any one of (1) to (4), wherein in the step (A), dimethyl ether in a liquid state is supplied in a state where a saturated amount of water is dissolved.
(6) A method for producing an oily material,
(A) A mixture of dimethyl ether and the oil (i) by bringing the target material containing moisture and oil as the oily material into contact with dimethyl ether in a liquid state and transferring the oil in the target material into dimethyl ether. And (B) evaporating dimethyl ether in said mixture (i), thereby separating dimethyl ether from said mixture (i), and obtaining deoiled target material (ii)
In the step (A), at least a part of the contact operation between the target material and the liquid dimethyl ether is performed in a state where a saturated amount of water is dissolved in the dimethyl ether.
(7) (C) liquefying the dimethyl ether separated in the step (B) and sending it to the step (A) again.
In the step (B), the method further includes recovering work performed in the external environment by vaporization of dimethyl ether, and supplying the work to the step (C) as all or part of the power of the step (C). The method according to 6).
(8) The method according to (6) or (7), wherein the target material subjected to the step (A) includes an aquatic plant having an ability to fix carbon dioxide by photosynthesis or a processed product thereof.
(9) The method according to (8), wherein the aquatic plant is an algae capable of producing oil.
(10) A deoiling system for extracting oil from a target material containing moisture and oil,
Dimethyl ether,
A liquefier that liquefies dimethyl ether in a gaseous state to form a liquid state;
Liquid dimethyl ether is brought into contact with the target substance, the oil content in the target material is transferred into dimethyl ether, and a mixture (i) of dimethyl ether and the oil content and the deoiled target material (ii) A deoiler that is configured to perform at least a portion of the contact in a state where a saturated amount of water is dissolved in dimethyl ether; and
An evaporator for vaporizing dimethyl ether in the mixture (i);
A separator for separating gaseous dimethyl ether from the mixture (i);
An oil removing system comprising: an expander that expands dimethyl ether in a gaseous state.
(11) The liquefier includes a compressor that pressurizes dimethyl ether in a gaseous state, and a condenser that condenses the pressurized gaseous dimethyl ether into a liquid state,
The compressor, the condenser, the deoiler, the evaporator, the separator, and the expander are connected in series in this order, and the expander is connected to the compressor to form a circuit, and the circuit Dimethyl ether circulates, and
The condenser and the evaporator are connected by a heat exchanger, and work performed to the outside in the expander is collected, and the work is configured to be input as all or part of the power of the compressor. The deoiling system according to 10).
(12) The control device according to (10) or (11), further including a control device that controls the mass ratio of oil to water in the mixture (i) supplied from the deoiler to the evaporator to be a predetermined value or more. system.

  According to the oil extraction method of the present invention, the method of producing an oily material of the present invention, and the system of the present invention, the step of contacting the target material with dimethyl ether in a liquid state in a specific manner, and then vaporizing and liquefying dimethyl ether. By including, even if the target material is a material containing a large amount of water in addition to the oil, the oil can be extracted efficiently from it with low energy. Furthermore, the deoiled target material can be easily obtained as a processed product with little contamination.

FIG. 1 is a block diagram schematically showing an example of a deoiling system of the present invention that implements the method of the present invention.

(Target material)
The oil extraction method of the present invention is a method for extracting oil from a target material containing water and oil.

The target material to which the method of the present invention is applied can be any material containing moisture and oil. The oil contained in the target material may be a substance that is not desired to be contained in the target material and is required to be removed from the target material. It may be.
As an example of the former, soil containing harmful oils such as heavy oil, benzene, and cyanide and containing a large amount of water is used as a target material, and harmful oils are removed by the method of the present invention to obtain deoiled soil. Application examples can be given.
As an example of the latter, there can be mentioned an application example in which a mixture containing organisms containing a lot of moisture and oil is used as a target material, and the oil is extracted from the mixture to produce an industrially useful oily material such as biofuel.

  Specific examples of the organism include algae that can produce oil such as squid, sunflower, sesame seeds, sugar cane, corn, and the like. Moreover, as a mixture containing the said living organism | raw_food, the mixture containing various substances required for these living organisms and its culture | cultivation can be mentioned. For example, when a living organism that can be cultured in the sea such as algae is used as the living organism, a mixture of the living organism and seawater can be used in the method of the present invention. Such a mixture may be subjected to processing such as cell crushing and dehydration (mechanical pressing, centrifugation, etc.) as necessary, and the processed material may be used as a target material.

  The content of water in the target material is preferably smaller from the viewpoint of energy efficiency, but in the present invention, the content of water in the target material (total amount of target material in the stage immediately before being subjected to the step (A)) The ratio of the water content to 50% by mass or more may be 70% by mass or more. Even in such a target material containing a large amount of moisture, the method of the present invention can efficiently extract oil. Therefore, efficient extraction can be performed even from a target material obtained by simplifying the preliminary dehydration treatment before being subjected to the method of the present invention or a target material that has not been performed.

In the present invention, the oil contained in the target material is a substance other than moisture and a substance that can be dissolved in liquid dimethyl ether at a concentration equal to or higher than the saturation solubility of water. Preferably, the solubility of oil in dimethyl ether is at least 10 times the solubility of water in dimethyl ether, and more preferably, the oil is compatible with dimethyl ether in any proportion. Many oily materials are compatible with liquid dimethyl ether in any proportion, so any of these can be applied to the method of the present invention.
More specific examples of oils include such oils in soil contaminated with harmful oils such as heavy oil, benzene, and cyanide, and such oils in organisms containing oils that can be used as biofuels. Can do.

(Process (A))
In the method for extracting oil according to the present invention, the target material is brought into contact with dimethyl ether in a liquid state, the oil in the target material is transferred into dimethyl ether, and the mixture (i) of dimethyl ether and the oil is removed. A step of obtaining an oiled target material (ii) (step (A)).

  Examples of the production method and production apparatus of dimethyl ether used in the step (A) include, for example, JP-A-11-130714, JP-A-10-195090, JP-A-10-195008, and JP-A-10-182535 to JP-A-10-10. Nos. 182527, 09-309852 to 09-309850, 09-286754, 09-173863, 09-173848, 09-173845, and the like. .

  In the step (A), at least a part of the contact operation between the target material and the liquid dimethyl ether is performed in a state where a saturated amount of water is dissolved in the dimethyl ether. Since dimethyl ether in a liquid state can dissolve about 8% by mass of water (8 parts by mass with respect to 100 parts by mass of dimethyl ether), dimethyl ether in which such a saturated amount of water is dissolved is used in at least a part of the operation step. By using it, the operating conditions can be achieved.

Specifically, the operating conditions can be achieved by the following (a) or (b).
(A) The liquid dimethyl ether supplied to the step (A) is preliminarily made to contain a saturated amount of water.
(B) As a liquid dimethyl ether to be supplied to step (A), a dimethyl ether having a water content of less than a saturation amount is supplied, and moisture is transferred from the target material by contact between the target material and dimethyl ether, and a saturated concentration of water is dissolved. As a result, the contact is further continued thereafter.

  Of the above (a) and (b), (b) is usually preferable from the viewpoint of ease of implementation, but the method of the present invention is applied to applications where it is desirable to remove only the oil from the target material and not to remove moisture. In this case, (a) is preferred. Such applications can include applications such as low fat food processing.

  The mode of contact in the step (A) is not particularly limited, and is a mode in which the extraction medium containing dimethyl ether and the target material are mixed and stirred, a mode in which the target material is immersed in the extraction medium, and the flow of the extraction medium is circulated as a solid. It can be set as the arbitrary aspects employ | adopted with the normal extraction method, such as the aspect passed to this object material, and can be suitably selected according to the property of the object material.

  In the step (A), other substances other than these may be mixed in the mixed system in which the target material and dimethyl ether are brought into contact with each other. For example, an auxiliary extraction solvent may be mixed. Such a substance is preferably a substance which is a gas at 25 ° C. and 1 atm, like dimethyl ether. Further, it is preferably a substance having one or more properties such as low toxicity, easy oil dissolution, and easy availability. Specifically, substances such as ethyl methyl ether, formaldehyde, ketene, acetaldehyde, butane and propane can be exemplified. Among these, butane and propane, which are advantageous in terms of easy availability (low cost), low toxicity, and low danger in handling, can be preferably used.

  After the contact is completed in the step (A), the mixture (i) of dimethyl ether and the oil component and the deoiled target material (ii) are separated by any method, and the mixture (i) is separated into the next step (B ). Here, the mixture (i) subjected to the step (B) contains an oil component whose oil content is higher than the oil content in the target material before being subjected to the step (A). can do. The mixture (i) preferably contains 1 part by mass or more, more preferably 10 parts by mass or more of oil, with respect to 1 part by mass of water contained from the viewpoint of increasing the energy efficiency of the entire method of the present invention.

  The mixture (i) having such a high oil content can be obtained by continuing the above-described contact operation until the oil content is sufficiently high. Moreover, when the content rate of the oil content in the mixture (i) taken out from the container which performs the step (A) is insufficient, the mixture (i) is returned to the container again, and the content rate of the oil content is sufficiently increased. It can also be obtained by feeding the mixture (i) to step (B).

  Ideally, the mixture (i) preferably contains a large amount of oil among the moisture, oil and residual components in the target material, but preferably does not contain the remaining components, but contains some of the remaining components. In this case, the remaining components can be separated in a later step.

  On the other hand, the deoiled target material (ii) separated from the mixture (i) is composed of all or a part of the moisture and all of the remaining components among the moisture, oil and residual components in the target material. Although it is preferable that the oil component is not contained, depending on the use, a part of the oil component present in the target material, and dimethyl ether and, if present, any other extraction solvent may be further contained. In this case, the remaining dimethyl ether can be volatilized and removed by any method as necessary. The deoiled target material (ii) thus obtained can be obtained as a by-product of the production of the product or oily material, or can be appropriately discarded as waste, depending on the application. Since dimethyl ether is a gas at normal temperature and pressure, it is easily separated and has low toxicity. Therefore, in the method of the present invention, the deoiled target material can be easily obtained as a treated product with little contamination.

(Process (B))
The oil extraction method of the present invention includes a step (step (B)) of vaporizing dimethyl ether in the mixture (i) and thereby separating dimethyl ether from the mixture (i).
The step (B) can be performed by heating the mixture (i) or reducing the pressure to vaporize dimethyl ether in the mixture (i) and further separating the gas and liquid with a separator. In one-stage gas-liquid separation, dimethyl ether may remain in the liquid phase, but the residual ratio can be reduced by performing further gas-liquid separation.

  In step (B), the remaining mixture obtained by separating dimethyl ether from mixture (i) (including water and oil, hereinafter referred to as “mixture (iii)”) can be further processed as necessary. For example, when the method of the present invention is carried out for the purpose of removing harmful oil from the target material, it can simply be discarded. Also, for example, when the method of the present invention is carried out for the purpose of extracting oil from the target material and making it a useful oily material, moisture and other impurities are removed from the obtained mixture (iii) as necessary, The material can be purified.

  If the volatility of the oil is high, in the step (B), it is also possible to carry out a fractionation operation so as to separate the water and the oil at the same time when separating the dimethyl ether and obtain the separated products of the three. However, since separation of water and oil is often not easy as compared with separation of dimethyl ether from mixture (i), usually after separating dimethyl ether from mixture (i) to obtain mixture (iii), Separating this as necessary further facilitates implementation. Further separation of the mixture (iii) can be performed by a known method such as fractional distillation. In the method of the present invention, since the mixture (iii) having a low water content can be obtained, such separation can be performed with low energy.

(Process (C))
The oil extraction method of the present invention preferably includes a step of liquefying the dimethyl ether separated in the step (B) and sending it again to the step (A) (step (C)).

  Dimethyl ether can be liquefied by any method such as compression, cooling, or a combination thereof.

  In particular, in the step (B), it is preferable to recover work performed to the outside by vaporization of dimethyl ether, and to input this work to the step (C) as all or part of the power of the step (C). For example, it is preferable that the gas expansion and other work in the step (B) are transmitted to the compressor in the step (C) and used as all or a part of the compression power.

  Furthermore, in step (C), the dimethyl ether in a gaseous state is compressed by a compressor and then condensed by a condenser, and heat exchange is performed so that the heat energy from the condensation is used for evaporation in step (B). The method of the invention can be carried out.

  By sending the dimethyl ether obtained by liquefaction to step (A), dimethyl ether can be circulated and oil extraction can be performed efficiently.

(Deoiling system)
The deoiling system of the present invention is a deoiling system for extracting oil from a target material containing moisture and oil, and is composed of dimethyl ether, a liquefier that liquefies gaseous dimethyl ether into a liquid state, and a liquid state Deoiling to obtain dimethyl ether and oil mixture (i) and deoiled target material (ii) by bringing dimethyl ether into contact with the target substance and transferring the oil content in the target material into dimethyl ether A deoiler configured to perform at least a part of the contact in a state where a saturated amount of water is dissolved in dimethyl ether, an evaporator for vaporizing dimethyl ether in the mixture (i), and A separator for separating the gaseous dimethyl ether from the mixture (i); and an expander for expanding the gaseous dimethyl ether.

  In the deoiling system of the present invention, preferably, the liquefier includes a compressor that pressurizes gaseous dimethyl ether, and a condenser that condenses the pressurized gaseous dimethyl ether into a liquid state, and the compression The condenser, the condenser, the deoiler, the evaporator, the separator, and the expander are connected in series in this order, and the expander is connected to the compressor to form a circuit. Circulates. These components (compressor, condenser, deoiler, evaporator, separator, expander) may be directly connected by a conduit, and any component other than the conduit interposed between them may be connected. May be included. For example, an arbitrary heat exchanger, a valve, a compressor, etc. for adjusting the temperature and pressure of the fluid introduced into each component can be further provided.

  In a preferred aspect of the deoiling system of the present invention, the condenser and the evaporator are connected by a heat exchanger, work to be performed to the outside in the expander is recovered, and the work is all of the power of the compressor or Configured to be injected as part. By having such a configuration, the oil extraction method and the oily material production method of the present invention described above can be carried out efficiently.

  The deoiling system of the present invention preferably further includes a control device for controlling the mass ratio of oil to water in the mixture (i) supplied from the deoiler to the evaporator to be a predetermined value or more. As a specific example of such a control device, the mixture (i) is connected to the outlet of the mixture (i) of the deoiler until the amount of oil in the mixture (i) in the deoiler reaches a predetermined amount or more. And a device for returning the mixture (i) to be returned to the deoiler for further contact.

(Concrete example)
Hereinafter, specific examples of the deoiling system of the present invention and the deoiling method using the same suitable for practicing the oil extraction method of the present invention will be described with reference to the drawings. The drawings are merely schematic representations of the shape, size and arrangement of the components to the extent that the present invention can be understood. The present invention is not limited by the following description, and each component can be appropriately changed within the scope of the claims and the equivalents thereof.

  FIG. 1 is a block diagram schematically showing an example of such a deoiling system. In FIG. 1, the flow of dimethyl ether, moisture, oil, and the remaining components of the target material (the components other than moisture and oil among the components of the target material) are indicated by a solid line, a double line, a dashed line, and a broken line, respectively. Shown with arrows.

  In the system 100 shown in FIG. 1, the 1st compressor 111 and the 2nd compressor 112 as a compressor which pressurizes gaseous dimethyl ether, the condensation which condenses the pressurized gaseous dimethyl ether into a liquid state A vessel 121, a deoiler 131, an evaporator 124 for vaporizing dimethyl ether in the mixture (i), a separator 161 for separating gaseous dimethyl ether from the mixture (i), and expanding the gaseous dimethyl ether. The expander 171 is connected in series via a conduit and other optional components, and the expander 171 is connected to the first compressor 111 to form a circuit.

  In the operation of this system, the dimethyl ether in the gas state in the circuit is converted into dimethyl ether in the liquid state by the first compressor 111, the second compressor 112, and the condenser 121, and is supplied to the deoiler 131. . In this example, the compressor has two stages, and the first compressor 111 connects the expander 171 to collect work performed by the expander 171 and uses it as power for the first compressor 111. Reference numeral 113 denotes an electric motor, and input of work from the outside is performed only for the second compressor 112.

  A device (not shown) for adding water to dimethyl ether and dissolving a saturated amount of water in advance may be provided between the condenser 121 and the deoiler 131 as necessary.

The deoiler 131 also introduces a target material containing moisture, oil, and the remaining components via the conduit C1. In the deoiler 131, the target material and liquid dimethyl ether come into contact with each other, whereby moisture and oil in the target material are transferred into dimethyl ether, and deoiling of the target material is achieved. When a part of dimethyl ether is vaporized during deoiling, dimethyl ether vapor can be discharged from deoiler 131 via conduit C3 and returned to any place in the circuit for reuse.
Conditions such as temperature and pressure in the deoiler 131 can be appropriately determined within a range in which dimethyl ether can maintain a liquid state. Specifically, the pressure is in a range of 0.25 to 1.14 MPa and a temperature of 0 to 50 ° C. Can be set as appropriate.

  The deoiled target material (ii) is discharged from the deoiler 131 via the conduit C2. The deoiled target material (ii) discharged here usually contains all or a part of the moisture and almost all of the remaining components of the moisture, oil and residual components in the target material. .

  From the deoiler 131, the mixture (i) containing dimethyl ether, water (saturated concentration) dissolved therein, and oil is discharged through the conduit C4. At this time, if the oil content in dimethyl ether has reached a sufficient concentration, the mixture can be led from point 191 to conduit C5 and sent to the next step, but the oil content in dimethyl ether has not reached the predetermined concentration. Can guide the mixture from point 191 to C6 and return to the deoiler 131 to further contact the mixture with the target material. Thereby, dimethyl ether can be reused without vaporizing, and the mixture (i) with a high oil content rate can be obtained.

  The mixture (i) is subsequently sent to the evaporator 124 via the cooler 122 and the pressure reducing valve 123. The cooler 122 and the pressure reducing valve 123 adjust the temperature and pressure when vaporizing liquid dimethyl ether, and perform vaporization in cooperation with the evaporator. The evaporator 124 receives heat energy from the condenser 121 by the heat exchanger 125 and vaporizes dimethyl ether. As a result, the latent heat of vaporization of the liquid dimethyl ether is recovered and used effectively.

  The dimethyl ether in a gaseous state is separated from moisture and oil by the separator 161 and adiabatically expands in the expander 171. The expanded gaseous dimethyl ether is sent to the compressor 111. A cooler 126 can be provided between the expander 171 and the compressor 111 as necessary. The cooler 126 is installed as necessary according to the conditions of the medium to be used, and adjusts the gas temperature from the expander 171 to the optimum temperature at the inlet of the compressor 111.

In addition, the work performed to the outside during expansion in the expander 171 is collected and transmitted to the compressor 111, and is input as power for liquefaction of dimethyl ether.
The work performed to the outside in the expander 171 mainly refers to what dimethyl ether in a gas state performs with volume expansion, but also includes the following work. The dimethyl ether in the gaseous state generated in the evaporator 124 and led to the expander 171 may contain dimethyl ether droplets in the liquid state accompanying the gas flow. For this reason, in the expander 171, the work by vaporization of the mixed splash may be obtained. In the present invention, the work performed by the expander 171 includes not only work by volume expansion of gas but also this.

  The operating conditions of the expander and other devices for vaporizing dimethyl ether are set such that the pressure of dimethyl ether brought into a gaseous state by the expander is set to a range of 0.25 to 1.14 MPa and a temperature of 0 to 50 ° C. Can be adjusted as appropriate.

  The mixture separated from the dimethyl ether in the gas state in the separator 161 (including water, oil, and a part of the dimethyl ether remaining in the liquid state) is sent to the deaeration tower 181. By reducing the pressure inside the deaeration tower 181 with the pressure-retaining valve 182, dimethyl ether in the mixture can be vaporized and recovered. The gaseous dimethyl ether recovered and discharged from the conduit C7 can be returned to any place in the circuit and reused as necessary.

  On the other hand, the mixture (including moisture and oil) discharged from the deaeration tower 181 is further led to a separation tower 183 which is an optional component in the present invention, where moisture and oil content are obtained by any operation such as distillation. Separated.

  Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

<Example 1> (benzene removal test from wet soil contaminated with benzene using a mixture of liquefied dimethyl ether, water and benzene)
In the deoiler 131 of the deoiling system 100 shown in FIG. 1, a test was conducted to examine whether dimethyl ether in a liquid state can extract oil from the target material and implement the method of the present invention.

(1-1: Target material)
Take 2-82 g of soil (moisture 15.7% by weight) at 2-6-1 Nagasaka, Yokosuka City, Kanagawa Pref., Add benzene and stir well. Wet soil 1 containing 5.3 mg / l of test solution 1 L of benzene, which is 530 times the environmental standard value defined by No. 1, was prepared and used as a target material for oil extraction. The method for measuring the benzene concentration conformed to the provisions of Ministry of the Environment Notification No. 46.

  According to the benzene concentration measurement method stipulated by the Ministry of the Environment Notification No. 46, a sample conical water is put in a glass conical flask with a screw cap so that the weight-volume ratio is 10%, and the mixture is sealed with a magnetic stirrer for 4 hours. After placement, the solution is filtered through a membrane filter having a pore diameter of 0.45 μm to obtain a test solution. The amount of benzene in this test solution is measured by headspace-gas chromatograph mass spectrometry (conforming to JIS K 0125 5.2). According to Environmental Agency Notification No. 46, the environmental standard value is defined as 0.01 mg / liter of test solution or less.

(1-2: Extractant)
138.0 g of liquefied dimethyl ether, 12.00 g of water and 0.10 g of benzene were mixed to prepare an extractant for removing benzene. Since the maximum amount of water that can be dissolved in 138.0 g of liquefied dimethyl ether at 20 ° C. is 9.94 g, this extractant already contains more water than can be dissolved in liquefied dimethyl ether. In the deoiler 131 of the deoiling system 100, this extractant is brought into contact with dimethyl ether in a liquid state with the target material, and a saturated amount of water is already dissolved in the dimethyl ether. The higher concentration of benzene than the moist soil 2) corresponds to the liquid that has already been dissolved.

(1-3: Extraction)
The extraction operation was performed at room temperature. 7.82 g of wet soil 1 was weighed and packed into a cylindrical column having an inner diameter of 11 mm and a volume of 10 ml, and 125.9 g of the extract obtained in (1-2) was passed through the column at a rate of 10 ml / min. Allowed to circulate for 18 minutes.

(1-4: Evaluation of oil removal amount)
After the operation of (1-3), the benzene concentration of the deoiled wet soil 1 was measured by the same procedure as the measurement performed in (1-1). As a result, the benzene concentration was 0.50 mg / l of test solution. Therefore, it was found that the benzene concentration in the wet soil 1 can be reduced to 1/10 or less and effective deoiling can be achieved.

<Example 2>
(2-1: Target material)
Except having changed the amount of benzene to add, it operated similarly to (1-1) of Example 1, and produced the wet soil 2 containing the benzene of 0.608 mg / test solution 1L. This was the target material.

(2-2: Evaluation of extraction and deoiling amount)
The same operation as in (1-2) to (1-4) of Example 1 except that 7.82 g of wet soil 2 was used instead of wet soil 1 and the amount of the extractant was changed to 129.2 g. Then, extraction was performed and the amount of deoiling was evaluated. As a result, the benzene concentration was below the detection limit (0.001 mg / 1 L of test solution). Therefore, it was found that effective deoiling can be achieved.

Claims (10)

A method for extracting oil from a target material containing moisture and oil,
(A) The target material is brought into contact with dimethyl ether in a liquid state, the oil in the target material is transferred into dimethyl ether, a mixture (i) of dimethyl ether and the oil, and a deoiled target material ( ii) and (B) vaporizing dimethyl ether in said mixture (i), thereby separating dimethyl ether from said mixture (i),
In the step (A), at least a part of the operation of contact with dimethyl ether of said liquid with said target material, no line in the state in which the saturation amount of water dissolved in ether,
The oil extraction method , wherein the target material provided in the step (A) includes algae having an ability to fix carbon dioxide by photosynthesis and produce oil, or a processed product thereof . (C) further comprising the step of liquefying the dimethyl ether separated in the step (B) and sending it again to the step (A),
In the step (B), the method further includes recovering work performed to the outside by vaporization of dimethyl ether and supplying the work to the step (C) as all or part of the power of the step (C). Item 2. The method according to Item 1.   The method according to claim 1 or 2, wherein the mixture (i) supplied to the step (B) contains an oil component having a concentration higher than the oil content in the target material.   The method according to any one of claims 1 to 3, wherein the target material subjected to the step (A) contains 50% by mass or more of moisture.   The method according to any one of claims 1 to 4, wherein in the step (A), dimethyl ether in a liquid state is supplied in a state where a saturated amount of water is dissolved. A method for producing an oily material,
(A) A mixture of dimethyl ether and the oil (i) by bringing the target material containing moisture and oil as the oily material into contact with dimethyl ether in a liquid state and transferring the oil in the target material into dimethyl ether. And (B) evaporating dimethyl ether in said mixture (i), thereby separating dimethyl ether from said mixture (i), and obtaining deoiled target material (ii)
In the step (A), at least a part of the operation of contact with dimethyl ether of said liquid with said target material, no line in the state in which the saturation amount of water dissolved in ether,
The said target material provided to the said process (A) contains the algae which have the capability to fix a carbon dioxide by photosynthesis, and produce an oil component, or its processed material, The manufacturing method characterized by the above-mentioned. (C) further comprising the step of liquefying the dimethyl ether separated in the step (B) and sending it again to the step (A),
In the step (B), the method further includes recovering work performed to the outside by vaporization of dimethyl ether and supplying the work to the step (C) as all or part of the power of the step (C). Item 7. The method according to Item 6.   The method according to claim 6 or 7, wherein the mixture (i) supplied to the step (B) contains an oil component having a higher concentration than the oil content in the target material.   The method according to any one of claims 6 to 8, wherein the target material subjected to the step (A) contains 50% by mass or more of moisture.   The method according to any one of claims 6 to 9, wherein in the step (A), dimethyl ether in a liquid state is supplied in a state where a saturated amount of water is dissolved.

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