METHOD FOR RECYCLING WASTE ENGINE OIL

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims the priority and benefit of Chinese patent application serial no. 202310692567.9, filed on Jun. 12, 2023. The entirety of Chinese patent application serial no. 202310692567.9 is hereby incorporated by reference herein and made a part of this specification.

TECHNICAL FIELD

The present application relates to a technical field of recycling a waste engine oil, and in particular, relates to a method for recycling a waste engine oil.

BACKGROUND ART

In recent years, more and more additives are added to the lubricating oil, such as a decontaminant, a pour point depressant, an antioxidant, and a viscosity index improver. These additives significantly improve the properties of the lubricating oil, but increase the difficulty of recycling the waste lubricating oil. The waste engine oil added with additives not only have impurities such as a carbon, a sludge, a worn metal, and the like, but also have impurities suspended in the oil, such as calcium salts and barium salts generated from the decontaminant. The waste engine oil can be recycled efficiently only by removing various impurities in the waste engine oil first, so that the waste engine oil may be recycled as a base oil for the lubricating oil. Then the impact on subsequent processes can be reduced, and a qualified and high grade lubricating oil can be produced.

Most of the current method for treating the waste engine oil includes centralized collection, storage, sedimentation, and removing the insoluble matters in lower portion and collecting the oily product in upper portion as the base oil; or includes a simple pretreatment for the waste engine oil, distilling, condensing, and obtaining a refined oil. With an expansion of the market, an improvement of the engine oil quality, and particularly an increasing requirement of multi-grade lubricating oil, there exists a requirement for the properties of the lubricating base oil, such as kinematic viscosity, chroma, and oxidation stability. However, the base oil obtained by above treatment method has a poor quality and cannot meet the standard requirement of a high quality product.

SUMMARY

In order to solve the problem that a refined oil obtained by the existing waste engine oil treatment method has a poor quality, the present application provides a method for recycling a waste engine oil, which may be operated efficiently and stably, has a wider application range, and improves the quality of the refined oil effectively.

In a first aspect, the present application provides a method for recycling a waste engine oil, which adopts the following technical solution:

• • a method for recycling a waste engine oil, including the following steps:
  • adding an alkaline solution to the waste engine oil for treating the waste engine oil, maintaining a treating temperature of 80-120° C., to obtain a raw material oil;
  • performing a first distillation for the raw material oil at a temperature of 240-270° C. to obtain an intermediate oil;
  • performing a second distillation for the intermediate oil at an absolute pressure of 0-3 kPa and a temperature of 300-350° C., to obtain an unevaporated intermediate oil as a residual oil product and an evaporated intermediate oil;
  • fractionating the evaporated intermediate oil to obtain a first base oil component, a second base oil component and a third base oil component; and
  • refining the first base oil component, the second base oil component and the third base oil component individually, to obtain a first refined oil, a second refined oil and a third refined oil.

In particular, the first base oil component is a component from the top of fractionation column, the second base oil component is a component from the side line of the fractionation column, and the third base oil component is a component from the bottom of the fractionation column.

In the present application, the alkaline solution is added to the waste engine oil for neutralization reaction, which may significantly reduce the amounts of ash content, carbon residue, asphaltene and mechanical impurity in the waste engine oil; and the water, light hydrocarbon and diesel fuel is removed sufficiently by distillation, so that the flash point of the obtained refined oil reaches the standard. Temperatures for the first distillation and the second distillation are controlled strictly, so that the first distillation and the second distillation may remove targeted impurities, thereby improving the product quality effectively. When the temperatures of the first distillation and the second distillation are unduly high, the oil product may be decomposed into diesel fuel, and when the temperatures of the first distillation and the second distillation are unduly low, which is not conducive to distillation, and cannot remove the impurities effectively. The raw material oil may be evaporated at a lower absolute pressure and a lower temperature during the second distillation, so as to reduce the energy consumption effectively. The unevaporated intermediate oil and the evaporated intermediate oil are separated via the second distillation, and the evaporated intermediate oil is further separated, so as to ensure a separation accuracy of the product, and improve the quality of the refined oil.

The method for recycling the waste engine oil described above may be operated efficiently and stably, and has a wider application range, so that the whole process has a higher product quality under a lower energy consumption, thereby saving the energy and reducing the emission, and reducing the production cost of an enterprise.

In some embodiments, the alkaline solution is added in an amount of 0.5-1% by mass of the waste engine oil. In particular, the alkaline solution may be added in an amount of 0.5%, 0.6%, 0.75%, 0.9% or 1%, etc. by mass of the waste engine oil, and may be adjusted according to the specific technical index of the waste engine oil.

In some embodiments, the alkaline solution includes at least one of sodium hydroxide solution and potassium hydroxide solution. The alkaline solution may be sodium hydroxide solution, potassium hydroxide solution, or a combination of sodium hydroxide solution and potassium hydroxide solution. In order to further reduce an impurity ion, sodium hydroxide solution is preferred.

In the above technical solution, the alkaline solution can provide a good reaction environment for the neutralization reaction, and controlling the mass concentration and the amount of the alkaline solution is conducive to the neutralization reaction and removing the impurities, thereby improving the product quality. The alkaline solution may react with organic acidic substances such as naphthenic acids, hydroxy acids, fatty acids, and phenols in the waste engine oil, to generate salts or soaps, and water. If the waste engine oil is an acidic waste oil refined by sulfuric acid, the alkaline solution also reacts with the sulfuric acid and sulfonic acid in the waste engine oil, in which a flocculation products are salts. And the salts and the soaps reacted from the neutralization reaction may be dissolved in the alkaline solution and be removed. The waste engine oil is treated by the alkaline solution at a suitable treating temperature, so that useful components of the oil product are retained, and asphaltene, the carbon residue and sulphides in the waste engine oil are removed, thereby improving the quality of the refined oil.

In some embodiments, the sodium hydroxide solution has a mass concentration of 0.5%-1%. In particular, the sodium hydroxide solution may has a mass concentration of 0.5%, 0.65%, 0.85%, 0.9% or 1%, etc.

When the mass concentration of the sodium hydroxide solution is unduly low, the impurities may not be removed effectively, and when the mass concentration of the sodium hydroxide solution is unduly high, the sodium hydroxide solution may adversely affect the quality of the oil product, and the cost is relatively high. The reaction may be carried out under a better condition by controlling the mass concentration of the sodium hydroxide solution, which is conducive to the neutralization reaction, increase the reaction efficiency, and improves the treatment effect for the waste engine oil and the quality of the refined oil.

In some embodiments, the purification includes adding an adsorbent to the first base oil component, the second base oil component and the third base oil component, respectively, under stirring, and filtering to obtain the first refined oil, the second refined oil and the third refined oil.

The absorbent is used to adsorb the undesired components in the oil such as sulphides, alkaline nitrides, and aromatic hydrocarbons, so as to improve the color of the oil product, reduce the contents of sulfur and nitrogen, and improve the oxidation resistance, corrosion resistance and demulsibility of the refined oil.

In some embodiments, the adsorbent is an activated clay.

In some embodiments, the refining includes stirring at a temperature of 110-120° C. and an absolute pressure of 10-30 kPa for 30-60 min. In particular, the temperature may be 110° C., 112° C., 115° C., or 118° C., etc. And the absolute pressure may be 10 kPa, 15 kPa, 22 kPa or 28 kPa, etc.

In some embodiments, the activated clay is added in an amount of 3-8 wt % of the base oil component.

The undesired components are sufficiently absorbed by adopting the activated clay as the absorbent, controlling the temperature and the pressure of during the refining, and stirring, thereby improving the chroma and the quality of the oil product effectively, and improving the refining effect of the oil product.

In some embodiments, the adsorbent is a decolorizing sand.

In some embodiments, the refining includes stirring at room temperature for 40-60 min.

The decolorizing sand is adopted as the absorbent, such that the refining step may be performed at room temperature under stirring, and the process is simple.

In a second aspect, the present application provides a system for recycling a waste engine oil, which adopts the following technical solution:

• • the system for recycling a waste engine oil is applied to above method for recycling the waste engine oil, the system for recycling the waste oil includes a pretreatment system, a heating-distillation system, a second distillation system, a product collecting system and a refining system, successively connected; the pretreatment system is configured to pretreat the waste engine oil, the heating-distillation system is configured to perform a first distillation to the raw material oil, the second distillation system is configured to perform a second distillation to the intermediate oil, the product collecting system is configured to collect the product after the second distillation, and the refining system is configured to refine the intermediate oil evaporated from the product collecting system.

The waste engine oil enters to the pretreatment system first, reacts with the alkaline solution in the pretreatment system, and enters to the heating-distillation system to remove the water, the light hydrocarbon and the diesel oil sufficiently. The intermediate oil component is heated and evaporated, enters to the second distillation system to be redistilled and separated to obtain the first base oil component, the second base oil component and the third base oil component. The whole system needs only one set of a heat-conducting oil boiler, which may be operated effectively and stably, and reduces the energy consumption effectively.

In some embodiments, the system for recycling a waste engine oil also includes a heat exchange system configured to exchange heat before the raw material oil enters to the heating-distillation system.

The raw material oil is pre-heated by the heat exchange system before entering to the heating-distillation system, which is conducive to ensure the product quality in a subsequent process of heating and distilling and reduces the energy consumption.

In summary, the present applicant achieves at least one of the following technical effects.

• • 1. In the present application, the alkaline solution is added to the waste engine oil for pretreating first; a first distillation is performed to remove the water, the light hydrocarbon and the diesel oil sufficiently, and the first distillation at a specific temperature ensures that the raw material oil can be evaporated at a lower absolute pressure and a lower temperature in a second distillation, which may reduce the energy consumption. The unevaporated intermediate oil and the evaporated intermediate oil is separated by the second distillation, and the evaporated intermediate oil is further separated, so that a separation accuracy of the oil product is ensured, and the whole technology has a better product quality with a lower energy consumption.
  • 2. The first base oil component, the second base oil component and the third base oil component are individually refined, which may improve the color of the oil product, reduces the contents of sulfur and nitrogen, and improves the oxidation resistance, corrosion resistance and demulsibility of the refined oil, and is conducive to improving the quality of the refined oil.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of the pretreatment system, the heating-distillation system and the second distillation system of the system for recycling a waste engine oil according to an embodiment of the present application;

FIG. 2 is a structural diagram of the product collecting system and the refining system of the system for recycling a waste engine oil according to an embodiment of the present application;

DETAILED DESCRIPTION

The present application is further described in detail below in combination with FIGS. 1-2. It should be noted that, in the following embodiments, if the specific conditions are not specified, the reaction may be performed under conventional conditions or conditions recommended by the manufacturers; and all raw materials used in the following embodiments are commercially available unless otherwise specified.

The present application provides a method and a system for recycling a waste engine oil, in which the method for recycling the waste engine oil is achieved by the system for recycling a waste engine oil.

Main properties of the waste engine oil in the present application are as follows: a density (20° C.) of 885-895 kg/m³; a viscosity (40° C.) of 65-72 mm²/s; a viscosity index of 140-145; an acid value of 4.3-4.5 mg KOH/g; and a saponification number of 10-11 mg KOH/g.

In the present application, the first refined oil is a light base oil product (150SN) from the top line of the fractionation column, a second refined oil is a medium base oil product (250SN) from the side line of the fractionation column, and a third refined oil is a heavy base oil (350SN) from the bottom line of the fractionation column.

In particular, main properties of the light base oil product are as follows: a kinematic viscosity (40° C.) of 28-34 mm²/s; a flash point (open cup) of equal to or higher than 200° C., a oxidation stability not less than 200 min, and a chroma not greater than 1.5; main properties of the medium base oil product from the side line of the fractionation column are as follows: a kinematic viscosity (40° C.) of 38-42 mm²/s; a flash point (open cup) of equal to or higher than 210° C., a oxidation stability not less than 180 min, and a chroma not greater than 2; and main properties of the bottom line heavy base oil product from the bottom line of the fractionation column are as follows: a kinematic viscosity (40° C.) of 65-72 mm²/s; a flash point (open cup) of equal to or higher than 220° C., a oxidation stability not less than 180 min, and a chroma not greater than 3.

A System for Recycling a Waste Engine Oil

The system for recycling a waste engine oil includes: a pretreatment system, a heat exchange system, a heating-distillation system, a second distillation system, a product collecting system and a refining system, successively connected. The system for recycling a waste engine oil is further described in combination with FIGS. 1-2.

Referring to FIG. 1, the pretreatment system includes a pretreatment tank 11 and an additive tank 12, in which the pretreatment system is configured to pretreat the waste engine oil, and the additive tank 12 is configured to store an alkaline solution. The heat exchange system includes a waste engine oil/medium base oil heat exchanger 21 and a waste engine oil/heavy base oil heat exchanger 22, in which the heat exchange system is configured to exchange heat before a raw material oil enters to the heating-distillation system. The heating-distillation system includes a heater 31 and a primary tower 32, and is configured to perform a first distillation for the pretreated waste engine oil. The heater 31 is in communication with the primary tower 32, the primary tower 32 is in communication with a light hydrocarbon condenser 33, the light hydrocarbon condenser 33 is in communication with an oil water separator 34, the oil water separator 34 is in communication with a light oil tank 35 and a water tank 36, and the light oil tank 35 and the water tank 36 are in communication with a first light oil gas buffer tank 37. An inlet of the waste engine oil/medium base oil heat exchanger 21 is in communication with an outlet of the pretreatment tank 11, an inlet of the waste engine oil/heavy base oil heat exchanger 22 is in communication with an outlet of the waste engine oil/medium base oil heat exchanger 21, and an outlet of the waste engine oil/heavy base oil heat exchanger 22 is in communication with the heater 31.

Referring to FIGS. 1-2, the second distillation system includes a thin film evaporator 41 and a fractionating tower 42, and is configured to redistill an intermediate oil. An inlet of the thin film evaporator 41 is in communication with an outlet of the primary tower 32, a transferring tank 43 is provided between the primary tower 32 and the thin film evaporator 41, an outlet of the thin film evaporator 41 is in communication with an inlet of the fractionating tower 42. The thin film evaporator 41 is in communication with a buffer tank 47, and the buffer tank 47 is in communication with the transferring tank 43. The top of the fractionating tower 42 is in communication with an overhead condenser 44, an overhead cooler 45 and a reflux accumulator 46 successively, and the reflux accumulator 46 is in communication with the top of fractionating tower 42.

Referring to FIG. 2, the product collecting system is configured to collect a redistilled product, and the product collecting system includes a residual oil tank 51, a light base oil tank 52, a medium base oil tank 53 and a heavy base oil tank 54. The residual oil tank 51 is in communication with the thin film evaporator 41, the light base oil tank 52 is in communication with an upper section of the fractionating tower 42; the medium base oil tank 53 is in communication with a middle section of the fractionating tower 42, a medium base oil cooler 55 is provided between the medium base oil tank 53 and the fractionating tower 42. The heavy base oil tank 54 is in communication with a lower section of the fractionating tower 42, a heavy base oil cooler 56 is provided between the heavy base oil tank 54 and the lower section of the fractionating tower 42. The light base oil tank 52 is in communication with a base oil gas buffer tank 64, and the reflux accumulator 46 and the residual oil tank 51 both are in communication with the base oil gas buffer tank 64.

Referring to FIG. 2, the refining system is configured to refine the intermediate oil evaporated from the product collecting system, and the refining system includes an adsorbent mixing tank 61, a plate and frame filter 62 and the refined oil tank 63; the adsorbent mixing tank 61 is in communication with the light base oil tank 52, the medium base oil tank 53 and the heavy base oil tank 54 simultaneously, an upper end of the adsorbent mixing tank 61 is in communication with the refined oil tank 63 directly, an lower end of the adsorbent mixing tank 61 is in communication with an inlet of the plate and frame filter 62, and an outlet of the plate and frame filter 62 is in communication with the refined oil tank 63. The adsorbent mixing tank 61 is in communication with a second light oil gas buffer tank 65, and the refined oil tank 63 is in communication with a gas purification tank 66.

An implementing principle of above embodiment is as follows. The waste engine oil enters to the pretreatment tank 11 first, the alkaline solution is transferred to the pretreatment tank 11, and reacts with an organic acid of the waste engine oil for neutralization reaction to obtain a raw material oil. The raw material oil is transferred to and heated in the waste engine oil/medium base oil heat exchanger 21, the waste engine oil/heavy base oil heat exchanger 22, and the heater 31 successively, and is distilled in the primary tower 32 to obtain an intermediate oil.

The water, hydrocarbons and diesel oil in the raw material oil after the first distillation may be removed by the light hydrocarbon condenser 33, the oil water separator 34 and the light oil tank 35, so as to improve the purity of the intermediate oil. After the second distillation, the unevaporated intermediate oil enters to the residual oil tank 51 from the thin film evaporator 41, and is stored in the residual oil tank 51; and the evaporated intermediate oil enters to the fractionating tower 42 to be separated, so as to obtain a first base oil component, a second base oil component and a third base oil component. The first base oil component passes through the overhead condenser 44, the overhead cooler 45 and a reflux accumulator 46, and enters to the light base oil tank 52, and a portion of the first base oil component is refluxed through the reflux accumulator 46, and enters to the primary tower 32.

The second base oil component cooled by the medium base oil cooler 55 enters to the medium base oil tank 53, and the third base oil component cooled by the heavy base oil cooler 56 enters to the heavy base oil tank 54. The first base oil component in the light base oil tank 52, the second base oil component in the medium base oil tank 53 and the third base oil component in the heavy base oil tank 54 enter to corresponding adsorbent mixing tanks 61, respectively, to be mixed with adsorbents, the refined oil in upper section of the adsorbent mixing tank 61 directly enters to the refined oil tank 63 and is stored in the refined oil tank 63, and the refined oil in lower section of the adsorbent mixing tank 61 is filtered in the plate and frame filter 62, and is stored in the refined oil tank 63.

A method for recycling a waste engine oil

Example 1

A method for recycling a waste engine oil includes the following steps:

• • S1, pretreating the waste engine oil: transferring the waste engine oil to the pretreatment tank 11, adding the sodium hydroxide solution with a mass concentration of 0.5% to the waste engine oil for neutralization reaction at 80° C., to obtain a raw material oil; the sodium hydroxide solution is added in an amount of 1% of the amount of the waste engine oil.
  • S2, feeding the raw material oil to the primary tower 32, performing a first distillation at a temperature of 240° C. to obtain an intermediate oil;
  • S3, feeding the intermediate oil to the thin film evaporator 41, performing a second distillation at an absolute pressure of 0.1 kPa and a temperature of 300° C.;
  • S4, transferring an unevaporated intermediate oil as a residual oil product to the residual oil tank 51, fractionating an evaporated intermediate oil to obtain a first base oil component, a second base oil component and a third base oil component;
  • S5, refining: transferring the first base oil component, the second base oil component and the third base oil component to the adsorbent mixing tanks 61, respectively, mixing the first base oil component, the second base oil component and the third base oil component with an activated clay in the adsorbent mixing tank 61, in which the mass of the activated clay is 3 wt % of the corresponding base oil component, stirring at an absolute pressure of 10 kPa and a temperature of 110° C. for 30 min, transferring the refined oil in the upper section of the adsorbent mixing tank 61 to the refined oil tank 63 directly for being stored, and transferring the refined oil in the lower section of the adsorbent mixing tank 61 filtered via the plate and frame filter 62 to the refined oil tank 63 for being stored.

The first base oil component is refined to obtain the first refined oil, the second base oil is refined to obtain the second refined oil, and the third base oil component is refined to obtain the third refined oil.

Example 2

A method for recycling a waste engine oil includes following steps:

• • S1, pretreating the waste engine oil: transferring the waste engine oil to the pretreatment tank 11, adding a potassium hydroxide solution with the mass concentration of 1% to the waste engine oil for neutralization reaction at 120° C., to obtain a raw material oil; the potassium hydroxide solution is added in an amount of 0.5% of the amount of the waste engine oil.
  • S2, feeding the raw material oil to the primary tower 32, performing a first distillation at a temperature of 270° C. to obtain the intermediate oil;
  • S3, feeding the intermediate oil to the thin film evaporator 41, performing a second distillation at an absolute pressure of 3 kPa and a temperature of 350° C.;
  • S4, transferring an unevaporated intermediate oil as a residual oil product to the residual oil tank 51, fractionating an evaporated intermediate oil to obtain a first base oil component, a second base oil component and a third base oil component;
  • S5, refining: transferring the first base oil component, the second base oil component and the third base oil component to the adsorbent mixing tanks 61, respectively, mixing the first base oil component, the second base oil component and the third base oil component with an activated clay in the adsorbent mixing tank 61, in which the mass of the activated clay is 8% of the total mass of the first base oil component, the second base oil component and the third base oil component, stirring at an absolute pressure of 30 kPa and a temperature of 120° C. for 60 min, transferring the refined oil in the upper section of the adsorbent mixing tank 61 to the refined oil tank 63 directly for being stored, and transferring the refined oil in the lower section of the adsorbent mixing tank 61 filtered via the plate and frame filter 62 to the refined oil tank 63 for being stored.

The first base oil component is refined to obtain the first refined oil, the second base oil is refined to obtain the second refined oil, and the third base oil component is refined to obtain the third refined oil.

Example 3

This example is same as example 1 except that, the mass concentration of the sodium hydroxide solution is 0.8%, the sodium hydroxide solution is added in an amount of 0.6% of a mass of a waste engine oil.

Example 4

This example is same as example 3 except that, in S2, the first distillation is performed at 260° C.

Example 5

This example is same as example 4 except that, in S3, the second distillation is performed at an absolute pressure of 1 kPa and a temperature of 325° C.

Example 6

This example is same as example 5 except that, in S5, the activated clay is added in an amount of 5.5 wt % of the total weight of the first base oil component, the second base oil component and the third base oil component.

Example 7

This example is same as example 6 except that, in S5, the refining includes stirring at a temperature of 115° C. and an absolute pressure of 15 kPa for 45 min.

Example 8

This example is same as example 5 except that, in S5, the refining includes the following steps: transferring the first base oil component, the second base oil component and the third base oil component to the adsorbent mixing tanks 61, respectively, mixing the first base oil component, the second base oil component and the third base oil component with a decolorizing sand in the adsorbent mixing tank 61, in which the decolorizing sand is added in an amount of 7 wt % of the corresponding base oil component, stirring at room temperature for 50 min, transferring the refined oil in the upper section of the adsorbent mixing tank 61 to the refined oil tank 63 directly for being stored, and transferring the refined oil in the lower section of the adsorbent mixing tank 61 filtered via the plate and frame filter 62 to the refined oil tank 63 for being stored.

COMPARATIVE EXAMPLE

Comparative Example 1

This example is same as example 7 except that, in S1, equal amount of polyacrylamide is used to replace the sodium hydrocarbon solution.

Comparative Example 2

This example is same as example 7 except that, in S2, the first distillation is performed at 310° C.; and in S3, the second distillation is performed at an absolute pressure of 1.5 kPa and a temperature of 400° C.

Comparative Example 3

This example is same as example 7 except that, in S2, the first distillation is performed at 200° C.; and in S3, the second distillation is performed at an absolute pressure of 0.1 kPa and a temperature of 250° C.

Property Test

The refined oil obtained from examples 1-8 and comparative examples 1-3 were tested for the quality, according to general lubricating base oil standard (Q/SY44-2009);

The first refined oil products obtained from examples 1-8 have a kinematic viscosity range (40° C.) of 28-30 mm²/s, have a flash point range (open cup) of 212-220° C., have a chroma range of 1.2-1.4, and have an oxidation stability range of 226-233 min.

The second refined oil products obtained from examples 1-8 have a kinematic viscosity range (40° C.) of 38-41 mm²/s, have a flash point range (open cup) of 213-218° C., have a chroma range of 1.5-1.8, and have an oxidation stability range of 196-204 min.

The third refined oil products obtained from examples 1-8 have a kinematic viscosity range (40° C.) of 67-70 mm²/s, have a flash point range (open cup) of 232-240° C., have a chroma range of 2.1-2.5, and have an oxidation stability range of 203-210 min.

The test results of the first refined oil, the second refined oil and the third refined oil obtained from example 7 and comparative examples 1-3 are shown in Table 1.

TABLE 1
Comparison of the properties of different refined oils

	Kinematic	Flash		Oxidation
	viscosity	point ° C.		stability
Samples	(40° C.) mm2/s	(open cup)	Chroma	min

First refined oil

Example 7	30	220	1.4	233
Comparative	38	200	1.6	200
example 1
Comparative	/	/	/	/
example 2
Comparative	36	203	1.5	203
example 3

Second refined oil

Example 7	40	218	1.6	204
Comparative	45	210	2.1	185
example 1
Comparative	/	/	/
example 2
Comparative	48	214	1.9	188
example 3

Third refined oil

Example 7	68	240	2.2	210
Comparative	75	220	3	181
example 1
Comparative	/	/	/	/
example 2
Comparative	74	223	2.8	190
example 3

Comparing the main properties of the refined oil obtained from examples 1-8 and referring to Table 1, it can be seen that the refined oil of the present application has an excellent quality, and the temperature required for preparation of the refined oil of the present application is low, compared with the existing preparation process, so that the energy consumption is reduced, the emission is reduced, and the cost of the enterprise is reduced.

Comparing example 7 and comparative examples 1-3 and referring to Table 1, it can be seen that, since a high molecular organic flocculant polyacrylamide is added to pretreat the waste engine oil in comparative example 1, the refined oil prepared in comparative example 1 has worse property parameters, which may be caused by an incomplete removal of ash content, carbon residue, asphaltene and mechanical impurity in the waste engine oil, and a high impurity content. In comparative example 2, the temperature for the first distillation is unduly high and the temperature and the pressure for the second distillation are high; the oil products of the comparative example 2 does not meet corresponding technical standards basically, which may be caused by the unduly high temperatures for the first distillation and the second distillation, and that oil products are decomposed into the diesel oil. In comparative example 3, the temperature for the first distillation is unduly low and the temperature and the pressure for the second distillation are low; the quality of various refined oil prepared by the comparative example 3 is lower than that of example 7 significantly, because the unduly low temperature is not conducive to the distillation, the impurity cannot be remove effectively, and the quality of the oil products are declined significantly.

The above are the preferred embodiments of the present application, which are not intended to limit the protection scope of the present application. Therefore, all equivalent changes made according to the structure, shape and principle of the present application should be covered within the protection scope of the present application.

LISTING OF REFERENCE SIGNS

• • 11. pretreatment tank;
  • 12. additive tank;
  • 21. waste engine oil/medium base oil heat exchanger;
  • 22. waste engine oil/heavy base oil heat exchanger;
  • 31. heater;
  • 32. primary tower;
  • 33. light hydrocarbon condenser;
  • 34. oil water separator;
  • 35. light oil tank;
  • 36. water tank;
  • 37. first light oil gas buffer tank;
  • 41. thin film evaporator;
  • 42. fractionating tower;
  • 43. transferring tank;
  • 44. overhead condenser;
  • 45. overhead cooler;
  • 46. reflux accumulator;
  • 47. buffer tank;
  • 51. residual oil tank;
  • 52. light base oil tank;
  • 53. medium base oil tank;
  • 54. heavy base oil tank;
  • 55. medium base oil cooler;
  • 56. heavy base oil cooler,
  • 61. adsorbent mixing tank;
  • 62. plate and frame filter;
  • 63. refined oil tank;
  • 64. base oil gas buffer tank;
  • 65. second light oil gas buffer tank;
  • 66. gas purification tank.