Method of manufacturing recycled oil

Abstract

The objective is to provide a manufacturing method that enables the efficient production of high-quality recycled oil obtained by recycling used or waste oil. [Solution] In a method for recycling used oil or waste oil to produce recycled oil, recycled oil A and recycled oil B having a kinematic viscosity lower than that of recycled oil A are produced, and recycled oil A and recycled oil B are mixed in a mixing ratio (volume ratio) in the range of 1:0 to 0:1 to produce recycled oil having a desired kinematic viscosity. In the production of recycled oil A, used oil or waste oil having a viscosity at 20°C exceeding 48 mPa·s and a flash point exceeding 300°C is mixed with at least one of a solvent having a viscosity at 20°C of 48 mPa·s or less and a flash point of 300°C or less, and water, in a range of 15% to 25% by volume.

Description

[Technical Field]

[0001] This invention relates to a method for producing recycled oil obtained by recycling used oil or waste oil. [Background technology]

[0002] Waste cooking oil is generated in factories, restaurants, supermarkets, convenience stores, schools, and private homes from the use of fried foods, and if this is discharged directly into sewers, it could cause environmental problems. Therefore, efforts are being made to recycle waste cooking oil in an environmentally friendly way, such as by recycling it or separating and recovering recycled oil.

[0003] Patent Document 1 discloses a method for treating waste cooking oil with poor color using alcohol or the like, and then refining it with an adsorbent such as activated clay. It also discloses that the waste cooking oil after decolorization and refining can be used as a raw material for plant-based inks or as fuel for biodiesel.

[0004] Furthermore, Patent Document 2 discloses a method for recycling waste cooking oil, which involves filtering waste cooking oil to remove impurities and obtain clean waste cooking oil, adding methanol and caustic alkali to esterify it, washing the esterified oil with water and separating the layers, and then adsorbing the upper layer. The resulting recycled oil is then used as cutting oil, diesel engine oil, etc.

[0005] However, recycled oils like those described above have problems such as low fuel consumption and engine stalling when used as fuel for biodiesel, and there has been a demand for high-quality recycled oil that can be reliably used in various applications such as fuel, lubricant, and additives. Furthermore, recycled oil has poor separation and recovery efficiency, and high-viscosity waste cooking oil cannot be separated and recovered unless its viscosity is reduced to, for example, around 20 mPa·s or less during pretreatment. In addition, this further reduces the separation and recovery efficiency, so there has been a great need for measures to efficiently obtain high-quality recycled oil. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2004-115711 [Patent Document 2] Japanese Patent Publication No. 2005-171161 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The object of this invention is to provide a method for producing recycled oil that can efficiently manufacture high-quality recycled oil obtained by recycling used oil or waste oil. [Means for solving the problem]

[0008] The invention described in claim 1, which solves the above problem, A method for recycling used oil or waste oil to produce recycled oil, comprising: producing recycled oil A and recycled oil B having a kinematic viscosity lower than that of recycled oil A; and appropriately mixing recycled oil A and recycled oil B in a mixing ratio (volume ratio) in the range of 1:0 to 0:1 to obtain recycled oil having a desired kinematic viscosity. The production of recycled oil A includes a mixing step of adding at least one of a solvent having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or less, and water, in a range of 15% to 25% by volume, to used oil or waste oil having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or more, as a solvent for mixing, to obtain an oil-containing composition having a viscosity of 40 mPa·s to 48 mPa·s at 20°C and a flash point of 250°C to 300°C, by mixing; a water removal step of removing water contained in the oil-containing composition; a cooling step of cooling the oil-containing composition from which the water has been removed; and a precipitate removal step of removing precipitates formed in the oil-containing composition by the cooling step, wherein the mixing step is performed by stirring under the following conditions: • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more In the production of the recycled oil B, alcohol and caustic alkali are added to and mixed with the used oil or waste oil having a viscosity at 20°C exceeding 48 mPa·s and a flash point exceeding 300°C, to obtain a first oil-containing composition having a viscosity at 20°C of 40 mPa·s to 48 mPa·s and a flash point of 170°C to 180°C in a first mixing step; a glycerin removal step of removing glycerin contained in the first oil-containing composition; a first pre-mixing step of adding and mixing water in a range of less than 5% by volume to the first oil-containing composition from which glycerin has been removed to obtain an oil-containing precursor composition; a first pre-moisture removal step of removing moisture contained in the oil-containing precursor composition; a second post-mixing step of adding and mixing water in a range of 10% by volume or more to the oil-containing precursor composition from which moisture has been removed to obtain a second oil-containing composition; a second post-moisture removal step of removing moisture contained in the second oil-containing composition; a cooling step of cooling the second oil-containing composition from which moisture has been removed; and a precipitate removal step of removing precipitates formed in the second oil-containing composition by the cooling step. In the first mixing step, the first pre-mixing step, and the second post-mixing step, stirring is performed under the following conditions. · Stirring method: Mixer-type stirring · Stirring speed: 1800 r.p.m. or more · Stirring time: 30 minutes or more

[0009] In one embodiment, in the mixing step in the production of the recycled oil A, the solvent for mixing contains water. In the moisture removal step in the production of the recycled oil A, moisture is removed by layer separation and / or drying of the water layer and the oil layer. In the cooling step in the production of the recycled oil A, the oil-containing composition is cooled to a temperature of 10°C or lower. In the precipitate removal step in the production of the recycled oil A, precipitates formed in the oil-containing composition are removed with a filtration filter. The filtration filter in the production of the recycled oil A is a filter having 100 mesh and an opening size of 149 μm to 200 mesh and an opening size of 74 μm.

[0010] In one embodiment, in the first mixing step in the production of the recycled oil B, the alcohol is methanol and the caustic alkali is caustic potash.

[0011] In one embodiment, in the latter stage of the second mixing step, water is added so as to be in the range of 15% to 25% by volume with respect to the oil-containing precursor composition, and the operation consisting of the latter stage of the second mixing step and the subsequent latter stage of the water removal step is repeated two or more times. Further, in the former stage of the water removal step and the latter stage of the water removal step in the production of the recycled oil B, water is removed by layer separation and / or drying of the water layer and the oil layer. In the cooling step in the production of the recycled oil B, the second oil-containing composition is cooled to a temperature of 10°C or lower. In the precipitate removal step in the production of the recycled oil B, precipitates generated in the second oil-containing composition are removed with a filtration filter, and the filtration filter in the production of the recycled oil B is a filter with 100 mesh and an opening of 149 μm to 200 mesh and an opening of 74 μm.

Advantages of the Invention

[0012] As described above, according to the method for producing a recycled oil according to the present invention, there is an effect that a high-quality recycled oil that can be stably used in various applications can be efficiently produced.

Embodiments for Carrying Out the Invention

[0013] <Recycled Oil> The recycled oil produced by the production method according to the present invention is a recycled oil obtained by recycling used oil or waste oil, and has a water content in the range of 500 mass ppm or less based on the total amount of the recycled oil, and the content of components precipitating at a temperature of 10°C or lower is 1 mass% or less based on the total amount of the recycled oil.

[0014] In the recycled oil of the present invention, if the water content exceeds 500 mass ppm, it may be difficult to achieve the effects of the present invention, which is not preferable. In the present invention, the water content is Assumed to be measured in accordance with JIS K 2275.

[0015] In the recycled oil of the present invention, if the content of components that precipitate at temperatures below 10°C exceeds 1% by mass on a basis of the total recycled oil, it is undesirable for the recycled oil to be used in environments where the ambient temperature is below 10°C, as it may cause problems such as pump clogging or poor sliding of the piston in the cylinder due to components with poor low-temperature properties, such as lard and palm oil. In the present invention, the content of components that precipitate at temperatures below 10°C is measured by the amount removed by filtering.

[0016] Furthermore, the recycled oil according to the present invention can have, on a total recycled oil basis, for example, sulfur content (in terms of sulfur atoms), nitrogen content (in terms of nitrogen atoms), chlorine content (in terms of chlorine atoms), phosphorus content (in terms of phosphorus atoms), residual carbon content, 10% residual carbon content, ash content, and metal component content within predetermined ranges. In addition, the iodine value of the recycled oil can be within predetermined ranges.

[0017] In the recycled oil of the present invention, the sulfur content is measured in accordance with JIS K2541-6, the nitrogen content in accordance with JIS K2609, the chlorine content in accordance with JPI-5S-64-2002, the phosphorus content in accordance with JIS K0116, the residual carbon content in accordance with JIS K2270, the 10% residual carbon content is measured in accordance with JIS K2270 using the remaining 10% by mass sample after distillation of the sample, the ash content is measured in accordance with JIS K2272, and the metal component content is measured in accordance with JIS K8083 (bulk analysis from ICP). Furthermore, in the recycled oil of the present invention, the iodine value is measured in accordance with JIS K0070.

[0018] The recycled oil of the present invention has a kinematic viscosity of 4 cm² at 20°C. 2 / s~51cm 2 / s, preferably 5cm 2 / s~40cm 2It may be in the range of / s. In this invention, kinematic viscosity shall be measured in accordance with JIS K2283:2000.

[0019] The kinematic viscosity of the recycled oil of the present invention is preferably adjusted according to its application as a fuel for diesel engines, a lubricant, or various additives. In this case, the kinematic viscosity may be adjusted by mixing two or more recycled oils with different viscosities. For example, the kinematic viscosity at 20°C is 35 cm³. 2 / s~42cm 2 Recycled oil with a kinematic viscosity of approximately / s and a kinematic viscosity of 3 cm² at 2°C. 2 / s~6cm 2 Recycled oil with a desired kinematic viscosity can be obtained by mixing recycled oil of approximately / s in a desired ratio (mixing ratio (volume ratio) 1:0 to 0:1).

[0020] The recycled oil according to the present invention is of high quality despite being obtained by recycling used oil or waste oil, and can be stably used in various applications, such as fuel oil for engines and boilers, lubricating oil, additives, and industrial oils.

[0021] <Method for manufacturing recycled oil> The present invention relates to a method for producing recycled oil, which involves recycling used oil or waste oil to produce recycled oil, and comprising: producing recycled oil A and recycled oil B having a kinematic viscosity lower than that of recycled oil A; and appropriately mixing recycled oil A and recycled oil B in a mixing ratio (volume ratio) in the range of 1:0 to 0:1 to obtain recycled oil having a desired kinematic viscosity. The production of recycled oil A includes a mixing step of adding at least one of a solvent having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or less, and water, as a solvent for mixing, to used oil or waste oil having a viscosity of more than 48 mPa·s at 20°C and a flash point of more than 300°C, thereby obtaining an oil-containing composition having a viscosity of 40 mPa·s to 48 mPa·s at 20°C and a flash point of 250°C to 300°C; a water removal step of removing water contained in the oil-containing composition; a cooling step of cooling the oil-containing composition from which the water has been removed; and a precipitate removal step of removing precipitates formed in the oil-containing composition by the cooling step, wherein the mixing step is performed by stirring under the following conditions: • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more In the production of recycled oil B, the process includes: a first mixing step in which alcohol and caustic alkali are added to used oil or waste oil having a viscosity of 48 mPa·s at 20°C and a flash point of 300°C and mixed to obtain a first oil-containing composition having a viscosity of 40 mPa·s to 48 mPa·s at 20°C and a flash point of 170°C to 180°C; a glycerin removal step in which glycerin contained in the first oil-containing composition is removed; and a second pre-mixing step in which water is added to the first oil-containing composition from which glycerin has been removed in an amount of less than 5% by volume and mixed to obtain an oil-containing precursor composition. The process comprises: a water removal pre-step for removing water contained in the oil-containing precursor composition; a second mixing post-step for obtaining a second oil-containing composition by adding water in a range of 10% by volume or more to the water-removed oil-containing precursor composition and mixing; a water removal post-step for removing water contained in the second oil-containing composition; a cooling step for cooling the water-removed second oil-containing composition; and a precipitate removal step for removing precipitates formed in the second oil-containing composition by the cooling step, wherein stirring is performed under the following conditions in the first mixing step, the second mixing pre-step, and the second mixing post-step. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more

[0022] In this invention, viscosity is measured using a viscometer specified in JIS Z 8803 and represents the property of resisting flow within a liquid, as expressed by the ratio of shear stress to shear rate. Kinematic viscosity is measured in accordance with JIS K2283:2000. The flash point is measured in accordance with the rapid equilibrium closed method specified in JIS K 2265-2.

[0023] The used oil used in the method for producing recycled oil of the present invention is not particularly limited as long as it is used oil with a viscosity exceeding 48 mPa·s at 20°C and a flash point exceeding 300°C, and may be any known used oil. Examples of used oils include used fuel oil, industrial oil, household oil, mineral oil, vegetable oil, and animal fats. Such used oils may contain other components such as water in addition to oil components. Furthermore, the waste oil used in the method for producing recycled oil of the present invention is not particularly limited as long as it is waste oil with a viscosity exceeding 48 mPa·s at 20°C and a flash point exceeding 300°C, and may be any known waste oil. Examples of waste oils include used cooking oil, waste fuel oil, edible oil, mineral oil, vegetable oil, and animal fats. Such waste oils may contain other components such as water in addition to oil components.

[0024] In this invention, only one type of used oil or waste oil, such as vegetable waste cooking oil, may be used, or a combination of two or more types of used oil or waste oil, such as a combination of vegetable waste cooking oil and virgin cooking oil, may be used. When using virgin cooking oil, it is preferable to use it in an amount of 10% by mass or less relative to the used oil or waste oil, taking into consideration the manufacturing cost of recycled oil.

[0025] (Manufacturing of recycled oil A) In the mixing process for the production of recycled oil A, the solvent to be mixed with used oil or waste oil is at least one of a solvent having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or less, and water. The solvent having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or less is not particularly limited and may be a known solvent. Examples of such solvents for mixing include inorganic solvents and organic solvents, but in the present invention, the solvent for mixing is preferably water, alcohol, or caustic alkali, more preferably water or a lower alcohol, and most preferably water. The solvent for mixing may be used after heating, for example, it is preferable to use water at a temperature of 50°C to 70°C. The water is not particularly limited and can be tap water, industrial water, river water, groundwater, well water, distilled water, ion-exchanged water, pure water, etc.

[0026] In the mixing process for the production of recycled oil A, the mixing ratio of the solvent to be mixed with used oil or waste oil is in the range of 15% to 25% by volume, preferably 18% to 22% by volume.

[0027] In the mixing process for the production of recycled oil A, the mixing after adding a solvent to the used oil or waste oil can be carried out under the following stirring conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more

[0028] If the stirring method differs from the above, for example, if the stirring speed is less than 1800 r.pm or the stirring time is less than 30 minutes, the recycled oil particles after manufacturing may not be finely ground and may not perform as intended, which is undesirable.

[0029] Furthermore, if the stirring speed is less than 1800 r.pm or the stirring time is less than 30 minutes, it may cause spoilage of the recycled oil after manufacturing, which is undesirable.

[0030] Mixing under the stirring conditions described above is preferably carried out using a stirring device such as a portable mixer manufactured by Satake Multimix Co., Ltd.

[0031] In the present invention, since the solvent is added to the used oil or waste oil in the mixing step and then the mixing is carried out under the stirring conditions described above, the spoilage of the recycled oil can be suppressed, making it preferable.

[0032] The oil-containing composition obtained in the mixing process of the production of recycled oil A is not particularly limited as long as its viscosity at 20°C is 40 mPa·s to 48 mPa·s and its flash point is 250°C to 300°C, and its state may be liquid, sol, or gel. In the present invention, it is preferable that the oil-containing composition contains used oil or waste oil as its main component. Here, the main component refers to a component that is present in an amount of 50% by mass or more of the total amount.

[0033] The water removal process in the water removal step of the production of recycled oil A is not particularly limited as long as it can remove the water contained in the oil-containing composition, and it is not necessary to remove all the water; it is sufficient if some of the water is removed. In the present invention, it is preferable to remove the water by separating the water layer from the oil layer and / or by drying. For example, if water is used as a solvent in the mixing step, the oil-containing composition obtained in the mixing step will undergo layer separation of the water layer and the oil layer, so water can be removed by removing the water layer. In addition, water removal by drying is also sufficient if all or part of the water is removed, and the drying method can be, for example, sun drying, and it is not necessary to dry at a high temperature. Furthermore, the oil-containing composition from which the water has been removed may be heated, for example to 120°C, to dry and sterilize at the same time.

[0034] The cooling means in the cooling process for the production of recycled oil A is not particularly limited as long as it can cool the oil-containing composition from which the water has been removed, and any known cooling means may be used. In the present invention, since components with poor low-temperature properties, such as lard and palm oil, precipitate when the oil-containing composition is cooled, it is preferable to cool until precipitates are formed. In such a cooling process, it is preferable to cool at a temperature of 10°C or lower, preferably 5°C or lower, and more preferably -5°C or lower.

[0035] In the production of recycled oil A, high-quality recycled oil can be easily and efficiently obtained by removing precipitates formed in the oil-containing composition by the cooling process described above during the precipitate removal process. For example, components with poor low-temperature properties, such as lard and palm oil, can be removed, thus preventing problems such as pump clogging and piston malfunction in cylinders when using recycled oil in environments where the temperature is below 10°C.

[0036] In the precipitate removal process for the production of recycled oil A, the removal of precipitates from the oil-containing composition is preferably carried out by filtering the oil-containing composition using a filtration filter. The filtration filter used is not particularly limited as long as it does not hinder the objective of the present invention, and may be a known filtration filter. As a filtration filter, for example, a filter with a mesh size of 100 and a mesh opening of 149 μm to 200 mesh and a mesh opening of 74 μm is preferred.

[0037] In this invention, the component content in the resulting recycled oil A can be adjusted by adjusting the mixing ratio of the solvent for mixing with used oil or waste oil in the mixing process of producing recycled oil A, the temperature of the solvent for mixing, the stirring conditions, the conditions of the above-mentioned water removal treatment, and the cooling temperature in the above-mentioned cooling process. For example, the sulfur content (in terms of sulfur atoms), nitrogen content (in terms of nitrogen atoms), chlorine content (in terms of chlorine atoms), phosphorus content (in terms of phosphorus atoms), residual carbon content, 10% residual carbon content, ash content, metal component content, water content, and the content of components that precipitate at temperatures below 10°C can be set to a predetermined range. In addition, the iodine value of the recycled oil can be set to a predetermined range.

[0038] (Manufacturing of recycled oil B) Recycled oil B has a kinematic viscosity lower than that of recycled oil A. In the first mixing step of the production of recycled oil B, it is preferable to pre-mix and stir the alcohol and caustic alkali to be mixed with used oil or waste oil. The mixing ratio of alcohol and caustic alkali can be, for example, set to a caustic alkali concentration in the mixture in the range of 8% to 10% by mass. Lower alcohols, particularly methanol, are preferred as the alcohol, and caustic potash is preferred as the caustic alkali. The alcohol and caustic alkali to be mixed may be heated before use, for example, at a temperature of 70°C or lower. If the temperature exceeds 70°C due to heating, only the alcohol will volatilize, resulting in an immature or unreacted state in the first mixing step, which is undesirable as it may reduce the quality of the resulting recycled oil B.

[0039] In the first mixing step of the production of recycled oil B, the mixing ratio of the total amount of alcohol and caustic alkali to be mixed with used oil or waste oil is not particularly limited as long as it does not hinder the objective of the present invention, but is preferably in the range of 10% to 25% by volume, more preferably 20% to 25% by volume.

[0040] In the first mixing step of the production of recycled oil B, after adding alcohol and caustic alkali to used oil or waste oil, stirring is performed under the following conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more

[0041] Mixing under the stirring conditions described above is preferably carried out using a stirring device such as a portable mixer manufactured by Satake Multimix Co., Ltd.

[0042] The first oil-containing composition obtained in the first mixing step of the production of recycled oil B contains an ester produced by a transesterification reaction, such as a fatty acid methyl ester, and a by-product glycerin, and is not particularly limited as long as its viscosity at 20°C is 40 mPa·s to 48 mPa·s and its flash point is 170°C to 180°C, and is in a liquid state.

[0043] The glycerin removal process in the production of recycled oil B is not particularly limited as long as it is a process that can remove the glycerin contained in the first oil-containing composition. For example, it is preferable to remove the glycerin by separating the glycerin layer from the oil layer.

[0044] In the production of recycled oil B, in the second pre-mixing step, water is added to the first oil-containing composition from which glycerin has been removed in the glycerin removal step described above in an amount of less than 5% by volume to obtain an oil-containing precursor composition, and the water contained in this oil-containing precursor composition is removed in the water removal pre-step. Subsequently, in the second post-mixing step, water is added to the oil-containing precursor composition from which the water has been removed in an amount of 10% by volume or more, preferably in the range of 15% to 25% by volume to obtain a second oil-containing composition, and the water contained in this second oil-containing composition is removed in the water removal post-step. The reason why the amount of water added in the second pre-mixing step is less than 5% by volume of the first oil-containing composition is to prevent the first oil-containing composition (crude product) from being saponified and becoming a detergent during the water washing in the second pre-mixing step. Once the second pre-mixing step and the water removal pre-step are completed, the saponified components contained in the first oil-containing composition (crude product) are removed, and the amount of water added in the second post-mixing step can be increased for mixing and washing.

[0045] In the present invention, the operation consisting of a second mixing step and a subsequent moisture removal step can be set to occur two or more times, for example, in the range of two to four times.

[0046] In the mixing process of the second pre-mixing stage and the second post-mixing stage of the production of recycled oil B, stirring is performed under the following conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Stirring time: 30 minutes or more

[0047] The moisture removal process in the pre-moisture removal step and the post-moisture removal step in the production of recycled oil B is not particularly limited as long as it can remove the moisture contained in the oil-containing precursor composition obtained in the second pre-mixing step and the moisture contained in the second oil-containing composition obtained in the second post-mixing step. It is not necessary to remove all moisture, and it is sufficient if some moisture is removed. In the present invention, moisture removal is preferably carried out by layer separation of the water layer and the oil layer and / or drying. For example, since layer separation of the water layer and the oil layer occurs in the oil-containing precursor composition obtained in the second pre-mixing step and the second oil-containing composition obtained in the second post-mixing step, moisture can be removed by removing the water layer. Furthermore, moisture removal by drying is also sufficient if all or part of the moisture is removed, and the drying means can be, for example, sun drying, and it is not necessary to dry at high temperatures. In addition, the second oil-containing composition from which the moisture has been removed may be heated, for example to 120°C, to dry and sterilize at the same time.

[0048] The cooling means in the cooling process for the production of recycled oil B is not particularly limited as long as it can cool the second oil-containing composition from which the water has been removed, and any known cooling means may be used. In the present invention, since components with poor low-temperature properties, such as lard and palm oil, precipitate when the second oil-containing composition is cooled, it is preferable to cool it until precipitates are formed. In such a cooling process, it is preferable to cool at a temperature of 10°C or lower, preferably 5°C or lower, and more preferably -5°C or lower.

[0049] In the production of recycled oil B, high-quality recycled oil can be easily and efficiently obtained by removing precipitates formed in the second oil-containing composition by the cooling process described above during the precipitate removal process. For example, components with poor low-temperature properties, such as lard and palm oil, can be removed, thus preventing problems such as pump clogging and piston sliding failures in cylinders when using recycled oil in environments where the temperature is below 10°C.

[0050] In the precipitate removal step for the production of recycled oil B, it is preferable to remove the precipitate from the second oil-containing composition by filtering the oil-containing composition using a filtration filter. The filtration filter to be used is not particularly limited as long as it does not inhibit the object of the present invention, and it may be a known filtration filter. As the filtration filter, for example, a filter with 100 mesh and an aperture of 149 μm to 200 mesh and an aperture of 74 μm is preferable.

[0051] In the present invention, the mixing ratio of alcohol and caustic alkali to the used oil or waste oil in the first mixing step for the production of recycled oil B, the temperature during mixing, the stirring conditions, the mixing ratio of water to the first oil-containing composition in the step before the second mixing, the mixing ratio of water to the oil-containing precursor composition in the step after the second mixing, the temperature during mixing, the stirring conditions are adjusted, the conditions of the moisture removal treatment are adjusted, and the cooling temperature in the cooling step is adjusted, whereby the component content in the obtained recycled oil B can be adjusted. For example, the sulfur content (in terms of sulfur atoms), the nitrogen content (in terms of nitrogen atoms), the chlorine content (in terms of chlorine atoms), the phosphorus content (in terms of phosphorus atoms), the residual carbon content, the 10% residual carbon content, the ash content, the metal component content, the moisture content, and the content of the components precipitating at a temperature of 10°C or lower can be set within a predetermined range. Also, the iodine value of the recycled oil can be set within a predetermined range.

[0052] (Preparation of recycled oil) In the present invention, the recycled oil A produced as described above and the recycled oil B produced as described above are appropriately mixed in a mixing ratio (volume ratio) in the range of 1:0 to 0:1 to obtain a recycled oil having a desired kinematic viscosity. Recycled oil B has a lower kinematic viscosity than that of recycled oil A. For example, if the kinematic viscosity of recycled oil A is v a , the kinematic viscosity of recycled oil B is v b , v a >v b , and when the desired kinematic viscosity is v, the mixing ratio (volume ratio a:b) of recycled oil A and recycled oil B can be set from the following formula. v=(v a ·a + v b ·b) / (a + b)

[0053] kinematic viscosity v of recycled oil A a The kinematic viscosity of recycled oil B is v b Since this can vary slightly depending on the manufacturing lot, the kinematic viscosity of recycled oil A and recycled oil B can be measured for each manufacturing lot, and the mixing ratio (volume ratio) of recycled oil A and recycled oil B can be set to have a kinematic viscosity appropriate for the intended use of the recycled oil. For example, the kinematic viscosity v at 20°C a 35cm 2 / s~42cm 2 Recycled oil A identified within the range of / s, and kinematic viscosity v at 20°C b 3cm 2 / s~6cm 2 By mixing recycled oil B, which is specified within the range of / s, in a desired ratio (mixing ratio (volume ratio) 1:0 to 0:1), recycled oil having a desired kinematic viscosity v can be obtained.

[0054] The recycled oil obtained by the manufacturing method of the present invention is a high-quality oil with excellent low-temperature properties, and can be further treated with known additives or processes as needed, and used for various applications as fuel oil, industrial oil, and other types of oil. [Examples]

[0055] The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

[0056] [Example 1] (Manufacturing of recycled oil A) 500 L of used vegetable cooking oil (color: ASTM color 8.0 dark brown, odor: off-flavor, viscosity at 20°C: 48.20 mPa·s, flash point: 306°C) was placed in a reaction vessel, and tap water (16°C) was added to the reaction vessel so that the mixing ratio with the used vegetable cooking oil was 20% by volume. Then, the stirring device was activated and the reaction vessel was heated, and the mixture was stirred while maintaining the liquid temperature at 70°C. (Mixing process)

[0057] In the mixing process described above, the mixing of waste vegetable oil and tap water in the reaction vessel was carried out using a portable mixer manufactured by Satake Multimix Co., Ltd. as the stirring device, under the following conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm • Mixing time: 30 minutes

[0058] The above mixing process yielded an oil-containing composition with a viscosity of 40.5 mPa·s at 20°C and a flash point of 250°C (color: ASTM color 6.0 brown, odor: vegetable oil odor).

[0059] The oil-containing composition obtained in the above mixing process was allowed to stand to separate the water layer from the oil layer. After removing the water layer, the oil-containing composition was heated to 120°C to dry and sterilize simultaneously. (Moisture removal process)

[0060] Next, the oil-containing composition, along with the reaction vessel, was placed in a refrigerated room and cooled until the oil-containing composition reached a temperature of -5°C. This resulted in the precipitation of components with poor low-temperature properties in the oil-containing composition. (Cooling process)

[0061] Next, recycled oil A was obtained by filtering the oil-containing composition in the above-mentioned refrigerated room using a filtration filter (100 mesh, mesh opening 149 μm). (Precipitate removal step)

[0062] The kinematic viscosity of recycled oil A at 20°C was measured and found to be 37 cm³. 2 The value was / s. The kinematic viscosity was measured in accordance with JIS K2283:2000.

[0063] (Manufacturing of recycled oil B) 500 L of the same used vegetable cooking oil as described above was placed in a reaction vessel, and the vessel was heated and stirred while maintaining the liquid temperature at 70°C. Then, a mixture of methanol and potassium hydroxide, mixed in a volume ratio of 90.6:9.4 (setting the potassium hydroxide concentration to 9.4%), was added to the reaction vessel so that the mixing ratio with the used vegetable cooking oil was 20% by volume, and the mixture was stirred while maintaining the liquid temperature at 70°C. (First mixing step)

[0064] In the first mixing step described above, a portable mixer manufactured by Satake Multimix Co., Ltd. was used as the stirring device, and the process was carried out under the following conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm • Mixing time: 30 minutes

[0065] The above first mixing step yielded a first oil-containing composition (color: ASTM color 1.0 yellow, odor: vegetable oil odor) with a viscosity of 44 mPa·s at 20°C and a flash point of 176°C.

[0066] The first oil-containing composition obtained in the first mixing step described above was allowed to stand, causing layer separation between the glycerin layer and the oil layer, and the glycerin layer was removed. (Glycerin removal step)

[0067] 480 L of the first oil-containing composition, from which glycerin had been removed, was placed in a reaction vessel, and tap water (16°C) was added to the reaction vessel so that the mixing ratio with respect to the first oil-containing composition was 4% by volume. Then, the stirring device was activated and the reaction vessel was heated, and the mixture was stirred while maintaining the liquid temperature at 70°C. (Second mixing pre-stage)

[0068] In this second pre-mixing step, a portable mixer manufactured by Satake Multimix Co., Ltd. was used as the stirring device, and the process was carried out under the following conditions. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm • Mixing time: 30 minutes

[0069] The oil-containing precursor composition obtained in the second mixing pre-step was allowed to stand, causing layer separation between the water layer and the oil layer, and the water layer was removed. (Water removal pre-step)

[0070] Next, 480 L of the oil-containing precursor composition from which the water had been removed was placed in a reaction vessel, and tap water (16°C) was added to the reaction vessel so that the mixing ratio with respect to the oil-containing precursor composition was 20% by volume. Then, under the same conditions as in the second pre-mixing step, the stirring device was operated, and the reaction vessel was heated while stirring was performed to maintain the liquid temperature at 70°C. (Second post-mixing step)

[0071] The second oil-containing composition obtained in the second mixing step was allowed to stand to separate the water layer from the oil layer. After removing the water layer, the second oil-containing composition was heated to 120°C to dry and sterilize simultaneously. (Moisture removal step)

[0072] Next, the second oil-containing composition, along with the reaction vessel, was placed in a refrigerated room and cooled until the oil-containing composition reached a temperature of -5°C. This resulted in the precipitation of components with poor low-temperature properties in the second oil-containing composition. (Cooling step)

[0073] Next, recycled oil B was obtained by filtering the second oil-containing composition in the above-mentioned refrigerated room using a filtration filter (100 mesh, 149 μm opening). (Precipitate removal step)

[0074] The kinematic viscosity of recycled oil B at 20°C was measured, and the result was 5 cm 2 The value was / s. The kinematic viscosity was measured in accordance with JIS K2283:2000.

[0075] (Preparation of recycled oil) Recycled oil A and recycled oil B were mixed in a mixing ratio (volume ratio) of 5.5:1 to obtain recycled oil (sample I). The kinematic viscosity of this recycled oil (sample I) was measured and found to be 32 cm³. 2 The result was / s. In addition, the water content of recycled oil (sample I) was 320 ppm by mass based on the total amount of recycled oil, and the content of components that precipitate at temperatures below 10°C was 1% by mass based on the total amount of recycled oil.

[0076] Furthermore, recycled oil A and recycled oil B were mixed in a mixing ratio (volume ratio) of 3.5:3 to obtain recycled oil (sample II). The kinematic viscosity of this recycled oil (sample II) was measured and found to be 22 cm². 2 The values ​​were / s, the water content of recycled oil (sample II) was 320 ppm by mass based on the total recycled oil, and the content of components that precipitate at temperatures below 10°C was 1% by mass based on the total recycled oil.

[0077] Furthermore, recycled oil A and recycled oil B were mixed in a mixing ratio (volume ratio) of 2.1:4.4 to obtain recycled oil (sample III). The kinematic viscosity of this recycled oil (sample III) was measured, and the result was 15 cm³. 2 The values ​​were / s, the water content of recycled oil (sample III) was 320 ppm by mass based on the total recycled oil, and the content of components that precipitate at temperatures below 10°C was 1% by mass based on the total recycled oil.

[0078] Furthermore, recycled oil A and recycled oil B were mixed in a mixing ratio (volume ratio) of 0.46:6.04 to obtain recycled oil (sample IV). The kinematic viscosity of this recycled oil (sample IV) was measured, and the result was 7 cm³. 2 The values ​​were / s, the water content of recycled oil (sample IV) was 320 ppm by mass based on the total recycled oil, and the content of components that precipitate at temperatures below 10°C was 1% by mass based on the total recycled oil.

[0079] Furthermore, the water content of the recycled oil was measured in accordance with JIS K 2275, and the content of components that precipitate at temperatures below 10°C was measured by the amount removed by filtering.

[0080] Among the four recycled oils listed above (Samples I-IV), the one with a kinematic viscosity of 22 cm² 2 When recycled oil (sample II) with a viscosity of / s was used as hydraulic fluid and cutting fluid in a 0°C environment, no problems occurred.

[0081] [Comparative Example 1] Recycled oil A' was obtained in the same manner as in Example 1, except that the mixing ratio of tap water to waste vegetable oil in the mixing process for the production of recycled oil A was set to 5% by volume, and the mixing of waste vegetable oil and tap water was carried out using a portable mixer manufactured by Satake Multimix Co., Ltd. as the stirring device, under the following conditions. The kinematic viscosity of this recycled oil A' at 20°C was measured and found to be 37 cm³. 2 It was / s. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm • Mixing time: 30 minutes

[0082] The recycled oil A' and recycled oil B described above were mixed in a mixing ratio (volume ratio) of 3.5:3 to obtain recycled oil (comparative sample I). The kinematic viscosity of this recycled oil (comparative sample I) was measured and found to be 22 cm³. 2 The result was / s. Furthermore, the water content of recycled oil (comparative sample I) was 320 ppm by mass based on the total amount of recycled oil, and the content of components that precipitate at temperatures below 10°C was 1% by mass based on the total amount of recycled oil. However, when recycled oil (sample II) and recycled oil (comparative sample I) were left standing for 90 days at 40°C, spoilage occurred in recycled oil (comparative sample I).

[0083] [Comparative Example 2] Recycled oil B' was obtained in the same manner as in the production of recycled oil B in Example 1, except that the first mixing step and the glycerin removal step in the production of recycled oil B were omitted.

[0084] The kinematic viscosity of this recycled B' oil at 20°C was measured and found to be 37 cm³. 2 The kinematic viscosity was high at / s, making it difficult to prepare recycled oil with adjusted kinematic viscosity by mixing it with recycled oil A from Example 1.

[0085] [Comparative Example 3] Recycled oil A'' was obtained in the same manner as in Example 1, except that the cooling step in the production of recycled oil A was not performed. The kinematic viscosity of this recycled oil A'' at 20°C was measured and found to be 40 cm³. 2 It was / s.

[0086] The above recycled oil A'' and recycled oil B (kinematic viscosity is 5cm²) 2 The oil was mixed with the other oils ( / s) in a mixing ratio (volume ratio) of 3.2:3.3 to obtain recycled oil (comparative sample II). The kinematic viscosity of this recycled oil (comparative sample II) was measured and found to be 22 cm². 2 The result was / s. Furthermore, the water content of the recycled oil (comparative sample II) was 320 ppm by mass based on the total recycled oil, but the content of components that precipitate at temperatures below 10°C exceeded 1% by mass based on the total recycled oil.

[0087] When this recycled oil (comparative sample II) was used as hydraulic fluid and cutting fluid in a 0°C environment, precipitates formed, causing problems such as pump clogging and poor sliding of the piston in the cylinder. [Industrial applicability]

[0088] As described above, the present invention has the effect of efficiently producing high-quality recycled oil, and therefore has great industrial applicability.

Claims

1. In a method for recycling used oil or waste oil to produce recycled oil, A recycled oil A and a recycled oil B having a kinematic viscosity lower than that of recycled oil A are manufactured, and recycled oil A and recycled oil B are mixed in a mixing ratio (volume ratio) in the range of 1:0 to 0:1 to obtain a recycled oil having a desired kinematic viscosity. The production of recycled oil A includes a mixing step of adding at least one of a solvent having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or less, and water, in an amount of 15% to 25% by volume, to used oil or waste oil having a viscosity of 48 mPa·s or less at 20°C and a flash point of 300°C or more, as a solvent for mixing, to obtain an oil-containing composition having a viscosity of 40 mPa·s to 48 mPa·s at 20°C and a flash point of 250°C to 300°C, by mixing; a water removal step of removing water contained in the oil-containing composition; a cooling step of cooling the oil-containing composition from which the water has been removed; and a precipitate removal step of removing precipitates formed in the oil-containing composition by the cooling step, wherein the mixing step is performed by stirring under the following conditions: • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Mixing time: 30 minutes or more In the production of the recycled oil B, the process includes: a first mixing step in which alcohol and caustic alkali are added to the used oil or waste oil having a viscosity of more than 48 mPa·s at 20°C and a flash point of more than 300°C and mixed to obtain a first oil-containing composition having a viscosity of 40 mPa·s to 48 mPa·s at 20°C and a flash point of 170°C to 180°C; a glycerin removal step in which glycerin contained in the first oil-containing composition is removed; and a second pre-mixing step in which water is added to the first oil-containing composition from which glycerin has been removed in a range of less than 5% by volume and mixed to obtain an oil-containing precursor composition. A method for producing recycled oil, comprising: a water removal pre-step step for removing water contained in a precursor composition; a second mixing post-step step for obtaining a second oil-containing composition by adding water in a range of 10% by volume or more to the oil-containing precursor composition from which water has been removed and mixing; a water removal post-step step for removing water contained in the second oil-containing composition; a cooling step for cooling the second oil-containing composition from which water has been removed; and a precipitate removal step for removing precipitates formed in the second oil-containing composition by the cooling step, wherein stirring is performed under the following conditions in the first mixing step, the second pre-mixing step, and the second post-mixing step. • Mixing method: Mixer-type mixing • Stirring speed: 1800 r.pm or higher • Mixing time: 30 minutes or more

2. The method for producing recycled oil according to claim 1, wherein the mixing step in the production of recycled oil A includes water as the solvent for mixing.

3. The method for producing recycled oil according to claim 1 or 2, wherein in the water removal step in the production of recycled oil A, water is removed by layer separation and / or drying of the water layer and / or oil layer.

4. The method for producing recycled oil according to claim 1 or 2, wherein in the cooling step in the production of recycled oil A, the oil-containing composition is cooled to a temperature of 10°C or lower.

5. The method for producing recycled oil according to claim 1 or 2, wherein in the precipitate removal step in the production of recycled oil A, precipitates formed in the oil-containing composition are removed by a filtration filter.

6. The method for producing recycled oil according to claim 5, wherein the filtration filter used in the production of recycled oil A is a filter with a mesh size of 100 mesh and a mesh opening of 149 μm to 200 mesh and a mesh opening of 74 μm.

7. The method for producing recycled oil according to claim 1, wherein in the first mixing step in the production of recycled oil B, the alcohol is methanol and the caustic alkali is caustic potash.

8. The method for producing recycled oil according to claim 1 or 7, wherein in the second post-mixing step, water is added in an amount of 15% to 25% by volume relative to the oil-containing precursor composition.

9. A method for producing recycled oil according to claim 1 or 7, wherein the operation consisting of the second mixing step and the subsequent water removal step is repeated two or more times.

10. The method for producing recycled oil according to claim 1 or 7, wherein in the water removal pre-step and water removal post-step in the production of recycled oil B, water is removed by layer separation and / or drying of the water layer and the oil layer.

11. The method for producing recycled oil according to claim 1 or 7, wherein in the cooling step in the production of recycled oil B, the second oil-containing composition is cooled to a temperature of 10°C or lower.

12. The method for producing recycled oil according to claim 1 or 7, wherein in the precipitate removal step in the production of recycled oil B, precipitates formed in the second oil-containing composition are removed by a filtration filter.

13. The method for producing recycled oil according to claim 12, wherein the filtration filter used in the production of recycled oil B is a filter with a mesh size of 100 mesh and a mesh opening of 149 μm to 200 mesh and a mesh opening of 74 μm.