Method for extracting base oil from waste engine oil by adding diluent

Abstract

The invention discloses a method for extracting base oil from waste engine oil by adding a diluent. The waste engine oil is converted into the base oil by adopting the steps of reducing the viscosity of the waste engine oil, filtering to remove impurities, carrying out gravity settling, carrying out centrifugal separation, recovering the diluent, carrying out low-temperature reduced pressure distillation and carrying out low-energy consumption.

Description

Technical Field

[0001] The present invention relates to the field of waste engine oil recycling, and in particular to a method for extracting base oil from waste engine oil. Background Art

[0002] Engine oil is generally used between mechanical parts to reduce friction and protect workpieces. Engine oil consists of two parts: base oil and additives. The main components of base oil are alkanes with a carbon content of 2% to 4%, aromatic hydrocarbons, and organic compounds containing nitrogen, sulfur, and oxygen. Waste engine oil is used engine oil replaced from various vehicles, machinery, and ships. During use, engine oil is gradually degraded and aged by exposure to high temperatures, oxygen, fuel combustion products, and other pollutants. The additives in the engine oil are continuously consumed, resulting in increased sediment in the oil, the production of harmful substances such as organic acids and gums, and increased corrosiveness to metals. Therefore, such engine oil is not suitable for direct reuse. The high-temperature distillation process for extracting base oil from waste engine oil in existing technologies consumes a lot of energy and suffers from secondary oxidation, which affects the quality of the oil. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to recycle and reuse waste engine oil with low energy consumption and high efficiency without polluting the environment through a simple process and a three-step treatment method for removing particulate impurities.

[0004] In order to solve the above technical problems, the technical solutions of the present invention are as follows.

[0005] A method for extracting base oil from waste engine oil by adding a diluent comprises the following steps.

[0006] Step 1: Filter the waste oil through a filter with a mesh size of 0.1mm~1mm to obtain preliminary filtered oil.

[0007] Step 2: The preliminarily filtered oil in step 1 and the diluent are mixed in a volume ratio of 1:10 to obtain a mixed oil.

[0008] Step 3: The mixed oil in step 2 is allowed to stand for gravity sedimentation to obtain a mixed oil with low turbidity and separated water.

[0009] Step 4: Centrifuge the mixed oil with low turbidity in step 3 to obtain a mixed oil with even lower turbidity.

[0010] Step 5: Prepare the commercial finished engine oil and diluent in a volume ratio of 1:10 to obtain the standard mixed oil.

[0011] Step 6: Take a certain amount of the standard mixed oil described in step 5 and the mixed oil with lower turbidity described in step 4 respectively, and compare the color.

[0012] Step 7: If the chromaticity contrast described in step 6 is consistent, proceed to step 8; otherwise, repeat step 4 until the chromaticity contrast is consistent and then proceed to step 8.

[0013] Step 8: distilling the mixed oil with lower turbidity under reduced pressure in a wiped film evaporator, collecting the diluent and obtaining the base oil at the same time.

[0014] The organic solvent is carbon tetrachloride, and the volume ratio of the organic solvent to the preliminary filtered oil is 10:1.

[0015] In step 8, the operating conditions of the reduced pressure distillation are: distillation temperature 78-80° C., and distillation pressure 0.09 MPa.

[0016] Compared with the prior art, the present invention has the following advantages: first, an organic diluent is used to reduce the viscosity of waste engine oil, thereby increasing the gravity sedimentation efficiency of particulate impurities ≥10 μm in the waste engine oil and preliminarily separating the water in the waste engine oil. Secondly, particulate impurities ≥5 μm in the waste engine oil are removed by centrifugation, and the waste engine oil is further purified. Finally, the diluent is recovered by a wiped film evaporator to obtain base oil. The diluent can be recycled. The distillation temperature of 78-80°C prevents the obtained base oil from being oxidized again at high temperatures while reducing energy consumption. The refined base oil can be directly put back into use. Therefore, the present invention, through a simple process and a three-step treatment method for removing particulate impurities, recycles waste engine oil with low energy consumption and high efficiency without polluting the environment. Implementation Method

[0017] It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0018] The present invention provides a method for extracting base oil from waste engine oil by adding a diluent, comprising the following steps:

[0019] Step S1: Filter the waste engine oil through a filter with a mesh size of 0.1 mm to 1 mm to obtain preliminary filtered oil.

[0020] Step S2: The preliminarily filtered oil in step S1 and a diluent are mixed in a volume ratio of 1:10 to obtain a mixed oil.

[0021] Step S3: The mixed oil in step S2 is allowed to stand for gravity sedimentation to obtain mixed oil with low turbidity and separated water.

[0022] Step S4: centrifuging the mixed oil with low turbidity in step S3 to obtain a mixed oil with even lower turbidity.

[0023] Step S5: prepare a mixture of commercial finished engine oil and a diluent in a volume ratio of 1:10 to obtain a standard mixed oil.

[0024] Step S6: taking a certain amount of the standard mixed oil described in step S5 and the mixed oil with lower turbidity described in step 4, respectively, and performing colorimetric comparison.

[0025] Step S7: If the chromaticity contrast in step 6 is consistent, proceed to step S8; otherwise, repeat step S4 until the chromaticity contrast is consistent and then proceed to step 8.

[0026] Step S8: distilling the mixed oil with lower turbidity under reduced pressure in a wiped film evaporator, collecting the diluent and obtaining the base oil at the same time.

[0027] Step S9: Collect the diluent in step S1 for recycling.

[0028] The filter in step S1 can be multi-layered to fully remove large solid impurities in the waste oil, such as debris, mechanical waste, carbon particles, etc. Therefore, the mesh size of the filter used in the filtration process does not need to be too small, and can range from 0.1mm to 1mm.

[0029] In step S2, an organic diluent is added to reduce the viscosity of the waste oil and improve the gravity sedimentation efficiency of particle impurities in the waste oil ≥10 μm.

[0030] In step S3, the waste oil is initially separated from the water at room temperature. After standing in a dedicated oil-water separator, the separated water is discharged at the bottom of the separator, resulting in the separation of oil at the top. This essentially removes the water from the waste oil.

[0031] In step S4, the low turbidity mixed oil is centrifuged to remove waste oil particulate impurities ≥5 μm to obtain a lower turbidity mixed oil.

[0032] In step S5, a commercial finished engine oil is prepared and mixed with a diluent in a volume ratio of 1:10 to obtain a standard mixed oil, thereby obtaining a comparison sample.

[0033] In step S6, a certain amount of the standard mixed oil described in step S5 and the mixed oil with lower turbidity described in step 4 are respectively taken for color comparison to check whether the products are qualified.

[0034] In step S7, if the color comparison is consistent with that in step 6, proceed to step S8; otherwise, repeat step S4 until the color comparison is consistent and then proceed to step 8 to control whether the product is qualified.

[0035] In step S8, the mixed oil with lower turbidity is distilled under reduced pressure in a wiped film evaporator, the diluent is collected and the base oil is obtained at the same time, the product is obtained and the diluent is recovered.

[0036] In step S9, the diluent is collected and recycled in step S1, and the diluent is recycled.

[0037] The above is a detailed description of the embodiments of the present invention, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations to these embodiments may be made without departing from the principles and spirit of the present invention, and these changes and modifications still fall within the scope of protection of the present invention.

Claims

1. A method for extracting base oil from waste engine oil by adding a diluent, characterized in that: The method comprises the following steps: step 1: filtering waste engine oil through a filter with a mesh size of 0.1 mm to 1 mm to obtain preliminary filtered oil; step 2: mixing the preliminary filtered oil in step 1 with a diluent in a volume ratio of 1:10 to obtain mixed oil; step 3: allowing the mixed oil in step 2 to stand for gravity sedimentation to obtain a low-turbidity mixed oil and separated water; step 4: centrifuging the low-turbidity mixed oil in step 3 to obtain an even lower-turbidity mixed oil; step 5: preparing a market-produced finished engine oil and mixing it with a diluent in a volume ratio of 1:10 to obtain a standard mixed oil; step 6: taking a certain amount of the standard mixed oil in step 5 and the mixed oil with even lower turbidity in step 4, respectively, and performing colorimetric comparison; step 7: if the colorimetric comparison in step 6 is consistent, proceed to step 8; otherwise, repeat step 4 until the colorimetric comparison is consistent and then proceed to step 8; step 8: distilling the even lower-turbidity mixed oil under reduced pressure in a wiped-film evaporator, collecting the diluent and obtaining the base oil at the same time.

2. The method for extracting base oil from waste engine oil by adding a diluent to reduce the viscosity of the engine oil and then performing centrifugal separation according to claim 1, characterized in that: The diluent is carbon tetrachloride solvent, and the preliminary filtered oil and the diluent are mixed in a volume ratio of 1:

10.

3. The method for extracting base oil from waste engine oil by adding a diluent to reduce the viscosity of the engine oil and then performing centrifugal separation according to claim 1, characterized in that: The diluent is a carbon tetrachloride solvent, which reduces the viscosity of the waste oil and improves the gravity sedimentation efficiency of particle impurities in the waste oil that are ≥10 μm.

4. The method for extracting base oil from waste engine oil by adding a diluent to reduce the viscosity of the engine oil and then performing centrifugal separation according to claim 1, characterized in that: The impurity removal is divided into three steps: step 1, filtration and impurity removal; step 3, gravity sedimentation; and step 4, centrifugal separation.

5. The method for extracting base oil from waste engine oil by adding a diluent to reduce the viscosity of the engine oil and then performing centrifugal separation according to claim 1, characterized in that: In step 8, the operating conditions of the reduced pressure distillation are: distillation temperature 78-80° C., and distillation pressure 0.09 MPa.