Method for refining light fraction oil of waste lubricating oil with composite solvent

Abstract

The present application belongs to the technical field of distillate oil regeneration, and particularly discloses a method for refining light distillate oil of waste lubricating oil by using a composite solvent. The light distillate oil is recycled and reused by means of solvent refining and the assistance of a centrifuge, and the traditional process of sulfuric acid white clay is not needed. The solvent can also be recycled and reused, and the method is simple, efficient, green and environmentally friendly, and the yield can reach 83% or more.

Description

Technical Field

[0001] This invention relates to the field of distillate oil regeneration technology, and in particular to a method for refining waste lubricating oil light distillate oil using a composite solvent. Background Technology

[0002] Solvent refining of lubricating oil distillates mainly employs furfural refining, NMP refining, or phenol solvent refining. Current solvent refining techniques primarily utilize dual-solvent compound extraction, altering the solubility and polarity of the solvent system, reducing interfacial tension, and increasing mass transfer rate and refined oil yield by expanding the mass transfer surface area. However, due to low yield and poor selectivity, there are usually few reports on solvent refining processes for light distillate oils. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a method for refining light distillate oil from waste lubricating oil using a composite solvent.

[0004] To achieve the above objectives, the present invention is implemented according to the following technical solution:

[0005] A method for refining waste lubricating oil light distillate using a composite solvent includes the following steps:

[0006] S1. Preparation of composite solvent: Take one of diethylene glycol dimethyl ether, diethylene glycol methyl ether, propylene glycol dimethyl ether, dipropylene glycol butyl ether, and diethylene glycol butyl ether, add N,N-dimethylacetamide to obtain a mixed solvent, and then add a co-solvent to the mixed solvent and mix evenly to obtain a composite solvent.

[0007] S2. Mix the composite solvent with the waste lubricating oil light distillate at a mass ratio of (1-3):1, stir at 30-110℃ for 10-100 min, and then let it stand to settle for 20-40 min.

[0008] S3. After sedimentation, the upper layer is separated using a separatory funnel, and the upper layer is then centrifuged to separate the oil phase and the solvent phase.

[0009] S4. Distill the oil phase under vacuum conditions of -99 to -97 kPa and temperature of 100-170°C to remove the solvent, and obtain refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications.

[0010] Furthermore, the amount of co-solvent added is 5%-10% of the mass of the mixed solvent.

[0011] Furthermore, the co-solvent is ethanolamine or triethanolamine.

[0012] Furthermore, the mass ratio of diethylene glycol dimethyl ether or diethylene glycol methyl ether or propylene glycol dimethyl ether or dipropylene glycol butyl ether or diethylene glycol butyl ether to N,N-dimethylacetamide in the composite solvent is 1:(2-4).

[0013] Preferably, the mass ratio of the composite solvent to the waste lubricating oil light distillate is (1.5-2):1.

[0014] Preferably, in step S3, the centrifuge used for centrifugal separation of the upper liquid has a rotation speed of 3000-8000 r / min.

[0015] Compared with existing technologies, this invention recycles and reuses light distillate oils through solvent refining and centrifugation, eliminating the need for traditional processes such as sulfuric acid bleaching clay. The solvent can also be recycled and reused, making it simple, efficient, green, and environmentally friendly, with a yield of 83% or more. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0017] Example 1

[0018] 1) Preparation of composite solvent: Weigh N,N-dimethylacetamide and diethylene glycol methyl ether at a mass ratio of 2.5:1 and mix to obtain a mixed solvent. Then add 5% of the co-solvent ethanolamine to the mixed solvent and mix evenly to obtain a composite solvent.

[0019] 2) Mix 50g of waste lubricating oil light distillate with 75g of composite solvent, stir at 60℃ for 30min, and then let stand for 30min to settle. Pour the mixture into a separatory funnel and centrifuge at 6000r / min to separate the oil phase and solvent phase. Distill the oil phase under -97KPa vacuum conditions at 140℃ to remove the solvent, thus obtaining refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications. Weigh the oil; the yield of light oil meeting the specifications is 86%.

[0020] Example 2

[0021] 1) Preparation of composite solvent: Weigh N,N-dimethylacetamide and propylene glycol dimethyl ether at a mass ratio of 2:1 and mix them to obtain a mixed solvent. Then add 5% of the cosolvent triethanolamine to the mixed solvent and mix evenly to obtain a composite solvent.

[0022] 2) Mix 50g of waste lubricating oil light distillate with 75g of composite solvent, stir at 60℃ for 30min, and then let stand for 30min to settle. Pour the mixture into a separatory funnel and centrifuge at 6000r / min to separate the oil phase and solvent phase. Distill the oil phase under -97KPa vacuum conditions at 100℃ to remove the solvent, thus obtaining refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications, weigh it, and the yield is 85.5%.

[0023] Example 3

[0024] 1) Preparation of composite solvent: Weigh N,N-dimethylacetamide and diethylene glycol dimethyl ether at a mass ratio of 2:1 and mix them to obtain a mixed solvent. Then add 5% of the co-solvent ethanolamine to the mixed solvent and mix evenly to obtain a composite solvent.

[0025] 2) Mix 50g of waste lubricating oil light distillate with 75g of composite solvent, stir at 60℃ for 30min, and then let stand for 30min to settle. Pour the mixture into a separatory funnel and centrifuge at 6000r / min to separate the oil phase and solvent phase. Distill the oil phase under -97KPa vacuum conditions at 120℃ to remove the solvent, thus obtaining refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications, weigh it, and the yield is 84.1%.

[0026] Example 4

[0027] 1) Preparation of composite solvent: Weigh N,N-dimethylacetamide and dipropylene glycol butyl ether at a mass ratio of 2:1 and mix them to obtain a mixed solvent. Then add 5% of the co-solvent ethanolamine to the mixed solvent and mix evenly to obtain a composite solvent.

[0028] 2) Mix 50g of waste lubricating oil light distillate with 75g of composite solvent, stir at 60℃ for 30min, and then let stand for 30min to settle. Pour the mixture into a separatory funnel and centrifuge at 6000r / min to separate the oil phase and solvent phase. Distill the oil phase under -97KPa vacuum conditions at 165℃ to remove the solvent, thus obtaining refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications, weigh it, and the yield is 83%.

[0029] Example 5

[0030] 1) Preparation of composite solvent: Weigh N,N-dimethylacetamide and diethylene glycol butyl ether at a mass ratio of 2:1 and mix them to obtain a mixed solvent. Then add 5% of the cosolvent triethanolamine to the mixed solvent and mix evenly to obtain a composite solvent.

[0031] 2) Mix 50g of waste lubricating oil light distillate with 75g of composite solvent, stir at 60℃ for 30min, and then let stand for 30min to settle. Pour the mixture into a separatory funnel and centrifuge at 6000r / min to separate the oil phase and solvent phase. Distill the oil phase under -97KPa vacuum conditions at 170℃ to remove the solvent, thus obtaining refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications, weigh it, and the yield is 83.2%.

[0032] The waste lubricating oil light distillate from Example 1 and the refined light oil were tested for oil quality indicators, and the test results are shown in Table 1.

[0033] Table 1

[0034]

[0035] As shown in Table 1, the waste lubricating oil light distillate can fully meet the standards after being treated by the present invention.

[0036] The technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made in accordance with the technical solutions of the present invention fall within the protection scope of the present invention.

Claims

1. A method for refining light distillate oil from waste lubricating oil using a composite solvent, characterized in that, Includes the following steps: S1. Preparation of composite solvent: Take one of diethylene glycol dimethyl ether, diethylene glycol methyl ether, propylene glycol dimethyl ether, dipropylene glycol butyl ether, and diethylene glycol butyl ether, and add N,N-dimethylacetamide to obtain a mixed solvent. The mass ratio of diethylene glycol dimethyl ether, diethylene glycol methyl ether, propylene glycol dimethyl ether, dipropylene glycol butyl ether, or diethylene glycol butyl ether to N,N-dimethylacetamide in the composite solvent is 1:(2-4). Then add a co-solvent to the mixed solvent and mix evenly to obtain a composite solvent. The co-solvent is ethanolamine or triethanolamine, and the amount of co-solvent added is 5%-10% of the mass of the mixed solvent. S2. Mix the composite solvent with the waste lubricating oil light distillate at a mass ratio of (1-3):1, stir at 30-110℃ for 10-100 min, and then let it stand to settle for 20-40 min. S3. After sedimentation, the upper layer is separated using a separatory funnel, and the upper layer is then centrifuged to separate the oil phase and the solvent phase. S4. Distill the oil phase under vacuum conditions of -99 to -97 kPa and temperature of 100-170℃ to remove the solvent, and obtain refined oil. Filter the refined oil through diatomaceous earth to obtain light oil that meets the specifications.

2. The method for refining waste lubricating oil light distillate with a composite solvent according to claim 1, characterized in that: The mass ratio of the composite solvent to the waste lubricating oil light distillate is (1.5-2):

1.

3. The method for refining waste lubricating oil light distillate with a composite solvent according to claim 1, characterized in that: In step S3, the centrifuge used for centrifugal separation of the upper liquid has a speed of 3000-8000 r / min.

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