CN108690656B - Refining method of synthetic ester lubricating oil crude product - Google Patents
Refining method of synthetic ester lubricating oil crude product Download PDFInfo
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- CN108690656B CN108690656B CN201710218390.3A CN201710218390A CN108690656B CN 108690656 B CN108690656 B CN 108690656B CN 201710218390 A CN201710218390 A CN 201710218390A CN 108690656 B CN108690656 B CN 108690656B
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G53/00—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes
- C10G53/02—Treatment of hydrocarbon oils, in the absence of hydrogen, by two or more refining processes plural serial stages only
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
- C10G2300/10—Feedstock materials
- C10G2300/1037—Hydrocarbon fractions
- C10G2300/1062—Lubricating oils
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- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
- C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
- C10G2400/10—Lubricating oil
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Abstract
The invention provides a refining method of a crude product of synthetic ester lubricating oil. The refining method of the synthetic ester lubricating oil crude product comprises the following steps: 1) sequentially carrying out first molecular distillation and second molecular distillation on the crude product of the synthetic ester lubricating oil; 2) carrying out third molecular distillation on the heavy component formed by the second molecular distillation; 3) and (4) carrying out nitrogen gas stripping on the light component formed by the distillation of the third molecule to obtain the synthetic ester lubricating oil. The refining method has the advantages of high production efficiency, low refining cost and environmental protection, the synthetic ester lubricating oil refined by the method is nearly colorless, the acid value and the moisture of the synthetic ester lubricating oil meet the relevant requirements, and the ester yield is high.
Description
Technical Field
The invention belongs to the technical field of synthetic ester lubricating oil, and particularly relates to a refining method of a crude synthetic ester lubricating oil product.
Background
Compared with the traditional mineral lubricating oil, the synthetic ester lubricating oil has the characteristics of excellent viscosity-temperature performance, good thermal stability, low volatility, biodegradability, good abrasion resistance and friction resistance, environmental friendliness and the like, can be mixed and dissolved with mineral oil and most other synthetic oils, and is widely applied to the fields of airplane turbine engine lubricating oil, precision instrument and meter oil, synthetic compressor oil, refrigerating machine oil and the like.
The synthetic ester lubricating oil is generally prepared by heating reaction of alcohol and organic acid under the action of acidic catalysis, and the low esterification rate of the reaction and the residue of the acidic catalyst can increase the refining difficulty of the subsequent synthetic ester lubricating oil crude product. In the traditional alkaline washing deacidification method, 5-10 wt% of alkaline solution is usually adopted to wash a crude ester product, so that impurities such as free fatty acid, an acidic catalyst and the like in the crude ester product can be effectively removed through a neutralization reaction, and a decoloration effect can be achieved through water phase separation to a certain extent. Although the deacidification method has good deacidification effect, the problems of increased ash content of the product, overhigh metal ion content, reduced electrical insulation performance of the ester and the like can be caused by introducing external alkali metal impurities; in addition, in the refining deacidification process, emulsification is easy to occur, so that the problems of high fatty acid consumption, low ester yield and the like are caused.
The reduced pressure distillation is also used for refining the crude ester product, the method removes the non-ideal components such as free fatty acid, acid catalyst and the like in the crude ester product by a low vacuum degree reduced pressure distillation mode, although the method is simple and easy to implement, the removal efficiency is low, and the related quality requirements of the synthetic ester lubricating oil cannot be met. In addition, vacuum distillation can be further combined with alkaline washing deacidification, which can improve the deacidification effect, but the problems existing in the prior art can not be solved.
In recent years, there have been reports on a method for deacidification and decolorization by solid adsorption, which has a certain effect by adsorbing and decolorizing with a decolorizer and simultaneously adsorbing and deacidifying with a deacidification agent, but has a limited acid reduction value and a relatively low ester yield. Therefore, a purification method which can make the purified synthetic ester lubricating oil meet the requirements of acid value and water content and has high ester yield is needed.
Disclosure of Invention
The invention provides a refining method of a crude product of synthetic ester lubricating oil, which has the advantages of high production efficiency, low refining cost, environmental protection, nearly colorless synthetic ester lubricating oil refined by the method, acid value and moisture meeting relevant requirements, and high ester yield.
The invention provides a refining method of a crude product of synthetic ester lubricating oil, which comprises the following steps:
1) sequentially carrying out first molecular distillation and second molecular distillation on the crude product of the synthetic ester lubricating oil;
2) carrying out third molecular distillation on the heavy component formed by the second molecular distillation;
3) and (4) carrying out nitrogen gas stripping on the light component formed by the distillation of the third molecule to obtain the synthetic ester lubricating oil.
In the invention, the crude product of the synthetic ester lubricating oil is simply called crude ester; the light component formed by the third molecular distillation is called ester intermediate product for short; the obtained synthetic ester lubricating oil is called ester product for short.
The invention does not strictly limit the crude synthetic ester lubricating oil, and can be crude polyol ester lubricating oil and the like. In the invention, the crude product of the polyol ester lubricating oil is an esterification product generated by esterification reaction of polyol and organic acid in the presence of a catalyst. Specific kinds of the polyhydric alcohol and the organic acid are not particularly limited, and the polyhydric alcohol may be pentaerythritol, for example, and the organic acid may be isooctanoic acid, for example; at the moment, the crude product of the polyol ester lubricating oil is an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst. The crude polyol ester lubricating oil can be obtained by a conventional method in the field.
It can be understood that the crude polyol ester lubricating oil contains a certain amount of ternary, binary and monobasic unsaturated esters, a certain amount of unreacted free acid and water generated by the reaction, besides the main quaternary saturated ester product. Therefore, the refining method aims to remove ternary, binary and monobasic unsaturated esters, unreacted free acid and water generated by reaction in the crude synthetic ester lubricating oil product as far as possible, so that the refined product meets the corresponding quality requirements of acid value, moisture and the like.
In the present invention, molecular distillation refers to the separation of materials containing different substances in a liquid-liquid state by utilizing the difference of the free paths of molecular motion of the different substances, which enables the liquid to separate the different substances contained therein at a temperature far lower than the boiling point thereof. The molecular distillation is usually carried out under high vacuum, has the characteristics of low distillation pressure, short heating time, high separation degree and the like, can greatly reduce the separation cost of high-boiling-point materials, and can well protect the quality of heat-sensitive substances.
In the invention, nitrogen gas stripping is to use nitrogen as a medium to destroy the original gas-liquid two-phase balance, thereby establishing a new gas-liquid balance state, and desorbing a certain component in the solution due to the reduction of partial pressure, thereby achieving the purpose of separating substances. Nitrogen stripping has the following advantages: 1) the operation temperature is low and is lower than the boiling point under the corresponding pressure; 2) the material heating time is short, and the heating medium is milder (the two aspects are particularly important for high-boiling-point and heat-sensitive materials); 3) the industrial production capacity is large and is not limited by scale; 4) the nitrogen is recycled, and no extra consumption is needed; 5) the heating is easy, and high-temperature media (such as heat conduction oil, molten salt and the like) are not needed.
The inventor of the invention has found through a great deal of research that the refining of the crude synthetic ester lubricating oil by independently using more than two stages of molecular distillation processes has relatively poor removal rate for ternary, binary and unitary unsaturated esters with close boiling points contained in the crude synthetic ester lubricating oil, particularly for quaternary ester and ternary ester with close molecular weights and small molecular free path difference; if the removal rate is ensured, more stages of molecular distillation treatment are necessary, so that the defects of small treatment amount, low productivity, low yield, high requirement on equipment processing precision, high investment and running cost of a vacuum system, poor economy and the like exist. In contrast, if only the unit production period and product economy of the industrial product are considered, the undesired components in the crude synthetic ester lubricating oil cannot be completely removed. In addition, a vacuum system of the molecular distillation equipment must be gradually opened after separation so as to enable the equipment to recover the normal pressure state, a large amount of air can be sucked in the process, and the ester synthetic oil molecules are polar and are easy to absorb water, so that the ester oil after separation is easy to absorb water again to cause the water content to exceed the standard. Therefore, the contradiction of the overproof water content, the separation effect and the economy is the biggest difficulty faced by the crude product refining method of the synthetic ester lubricating oil.
However, the inventor researches and discovers that the problem of low production efficiency of molecular distillation can be solved and the defect of poor separation precision of nitrogen gas stripping can be overcome by combining three-stage molecular distillation with nitrogen gas stripping; the three-stage molecular distillation can remove most of ternary, binary and unitary unsaturated esters, unreacted free acid and reaction water in the crude product of the synthetic ester lubricating oil, remove kettle residues generated by the ester oil and condensation compounds in the reaction and decolor, and the oil product refined by the three-stage molecular distillation cannot meet the corresponding index requirements, but the refining time is greatly reduced, the production efficiency is greatly improved, the product yield is greatly improved, and the energy consumption is greatly reduced; the light components after the tertiary molecular distillation can be removed with a small amount of residual non-ideal components through nitrogen gas stripping, and particularly, the nitrogen gas stripping can keep low nitrogen flux until the temperature of the oil product is reduced to the filling temperature, so that the refined oil product is prevented from contacting with air, and the condition that the water content of the product exceeds the standard due to the absorption of water in the air by polar ester synthetic oil is avoided. That is, the present invention has been accomplished in view of the fact that the present invention overcomes the contradiction between the reduction of acid value and water content and the improvement of product yield, as well as the long time and low efficiency in the prior art of refining esters by combining the three-stage molecular distillation with nitrogen gas stripping.
In the invention, the first molecular distillation is used for removing water, catalyst with lower boiling point and unreacted organic acid in the crude product of the synthetic ester lubricating oil; the second molecular distillation is used for removing pentaerythritol half-ester and organic acid and catalyst which are not removed by the first molecular distillation; third molecular distillation for decolorization; the skilled person can select suitable molecular distillation conditions for each stage according to the above purpose.
In the embodiment of the invention, the temperature of the first molecular distillation can be 170-180 ℃, and the absolute pressure can be 5.5-10 Pa; the temperature of the second molecular distillation can be 170-180 ℃, and the absolute pressure can be 1-5.5 Pa; the temperature of the third molecular distillation can be 190-200 ℃, and the absolute pressure can be 0.5-1 Pa. In addition, the condensation temperature of the first molecular distillation, the second molecular distillation and the third molecular distillation can be 15-30 ℃; the condensation temperature can be selected according to the requirements of the yield of light and heavy components after each molecular distillation and the acid value.
In the present invention, the nitrogen stripping can be carried out in a conventional manner. Specifically, the nitrogen stripping is carried out on the light components formed by the third molecular distillation, and comprises the following steps:
preheating nitrogen and light components formed by the third molecular distillation to 175-190 ℃, and then sending the light components to a stripping tower for nitrogen stripping; wherein the absolute pressure in the stripping tower is controlled to be 0-0.5 MPa. The nitrogen and the light components formed by the third molecular distillation are reversibly contacted in a stripping column.
The inventor finds that when the nitrogen gas stripping temperature exceeds 190 ℃, trace substances in light components formed by the third molecular distillation are oxidized, so that the product chromaticity is increased, and the product color is changed from colorless to light yellow.
Further, nitrogen gas is introduced at a flow rate of 40 to 80L/h per kg of light components formed by the third molecular distillation; preferably 50-70L/h, for example 60L/h.
In addition, the stripping tower is filled with a filler, and the filler can be stainless steel filler, pall ring filler, ceramic ball filler or Raschig ring filler. More specifically, the packing may be structured packing or irregular packing, wherein the structured packing may be stainless steel structured packing, which may be in the form of corrugated sheets or non-corrugated sheets; the irregular packing can be stainless steel packing or ceramic regular packing, and can be packed in a random packing mode, and the packing mode can be pall ring packing, Raschig ring packing, ceramic ball packing and the like.
Further, the product at the top of the stripping tower can be subjected to heat exchange and gas-liquid separation, and nitrogen is recovered. The recovered nitrogen can be recycled for nitrogen stripping.
The acid value of the synthetic ester lubricating oil obtained by the refining method is less than or equal to 0.05 mgKOH/g; in addition, the water content of the synthetic ester lubricating oil is less than or equal to 100 mg/kg; the yield is more than or equal to 80 percent.
The implementation of the invention has at least the following advantages:
1. the method has low refining cost, compared with the traditional refining process, the energy consumption is greatly reduced compared with vacuum deacidification, and simultaneously, the separated unreacted raw material acid has high purity and can be recycled as the raw material of the esterification reaction, thereby reducing the consumption of the raw material and the production cost.
2. The refining method is green and environment-friendly, the traditional alkali washing and water washing process is omitted by adopting the process of combining three-stage molecular distillation and nitrogen gas stripping, and three wastes are not generated.
3. According to the refining method, the operation pressure and temperature are low in the separation process, the heating time is short, the molecular structure of the product is kept complete in the separation process, and the obtained product is good in color and close to colorless; in addition, the method of the invention can not influence the quality of the ester products due to the introduction of impurities.
4. The refining method has short process operation time and high efficiency, and can simultaneously ensure the acid value and the water content of the refined product, wherein the acid value is less than or equal to 0.05mgKOH/g, the water content is less than or equal to 100mg/kg, and in addition, the product yield is more than or equal to 80 percent.
Drawings
Fig. 1 is a process flow diagram of a refining method of crude synthetic ester lubricating oil according to an embodiment of the present invention.
Description of the symbols:
1: a crude ester storage tank; 2: a first stage of molecular distillation equipment; 3: a second stage of molecular distillation apparatus; 4: a third stage of molecular distillation equipment; 5: an intermediate product storage tank; 6: a stripping column; 7: an ester product storage tank; r1: most of the isooctanoic acid and catalyst; d1: a deacidified crude ester formed by a first molecular distillation; r2: most of the half-fat with a small amount of acid; d2: removing the crude ester after the half ester is removed by the second molecular distillation; r3: ester intermediate products after the third-stage molecular distillation decoloration; d3: pigment impurities.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Pumping the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 170 ℃, the condensation temperature is controlled to be 30 ℃, and the absolute pressure is 7.4Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 6.22%, and the color is light yellow; the yield of crude ester D1 was 93.78%, the color was yellow, and the acid number was 1.67 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 was then pumped to a second molecular distillation apparatus 3 for a second molecular distillation at a distillation temperature of 170 c, a condensation temperature of 15 c and an absolute pressure of 5.5Pa to further remove most of the half-esters and a small amount of acid (i.e. R2) to give a crude ester D2 after removal of the half-esters by the second molecular distillation. Wherein, the yield of R2 is 5.87%, and the color is colorless; the yield of the crude ester D2 was 94.13%, the color was yellow, and the acid value was 0.083 mgKOH/g.
3. Third molecular distillation
The crude ester D2 is then pumped into a third molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled at 195 ℃, the condensation temperature is controlled at 15 ℃, and the absolute pressure is 0.52Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of D3 is 3.63%, and the color is brown; the yield of R3 was 96.07%, the color was colorless, and the acid value was 0.085 mgKOH/g.
4. Stripping of nitrogen
Filling stainless steel structured packing in a corrugated plate form in a stripping tower 6, preheating an ester intermediate product R3 to 180 ℃, and introducing the ester intermediate product into a distributor from the upper part of the stripping tower 6; meanwhile, nitrogen is preheated to 180 ℃, and is introduced into the stripping tower 6 from the bottom of the stripping tower 6 at the flow rate of 60L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0.1MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.034 mgKOH/g; the water content is 70 mg/kg; the yield of the synthetic ester lubricating oil was 83.5%.
Example 2
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Pumping the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 175 ℃, the condensation temperature is controlled to be 30 ℃, and the absolute pressure is 7.4Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 8.51 percent, and the color is light yellow; the yield of crude ester D1 was 91.49%, the color was yellow, and the acid number was 1.55 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 was then pumped to a second molecular distillation apparatus 3 for a second molecular distillation at a distillation temperature of 175 c, a condensation temperature of 20 c and an absolute pressure of 5.5Pa to further remove most of the half-esters and a small amount of acid (i.e. R2) to give a crude ester D2 after removal of the half-esters by the second molecular distillation. Wherein, the yield of R2 is 8.98%, and the color is colorless; the yield of crude ester D2 was 91.02%, the color was yellow, and the acid number was 0.077 mgKOH/g.
3. Third molecular distillation
And the crude ester D2 enters a third-stage molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled to be 190 ℃, the condensation temperature is controlled to be 20 ℃, and the absolute pressure is 0.52Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third-stage molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of R3 is 1.38%, and the color is brown; the yield of D3 was 98.62%, the color was colorless, and the acid value was 0.075 mgKOH/g.
4. Stripping of nitrogen
Filling pall ring packing in a random packing manner in a stripping tower 6, then preheating an ester intermediate product R3 to 190 ℃, and introducing the ester intermediate product into a distributor from the upper part of the stripping tower 6; meanwhile, nitrogen is preheated to 190 ℃, and is introduced into the stripping tower 6 from the bottom of the stripping tower 6 at the flow rate of 50L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0.25MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.029 mgKOH/g; the water content is 55 mg/kg; the yield of the synthetic ester lubricating oil was 80.5%.
Example 3
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Adding the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 180 ℃, the condensation temperature is controlled to be 30 ℃, and the absolute pressure is 10Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 9.69 percent, and the color is light yellow; the yield of crude ester D1 was 90.31%, the color was yellow, and the acid number was 1.89 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 then enters a second-stage molecular distillation device 3 for second molecular distillation, wherein the distillation temperature of the second molecular distillation is controlled to be 180 ℃, the condensation temperature is controlled to be 15 ℃, and the absolute pressure is 3Pa, most of half ester and a small amount of acid (namely R2) are further removed, and the crude ester D2 after half ester is removed by the second molecular distillation is obtained. Wherein, the yield of R2 is 5.45%, and the color is colorless; the yield of crude ester D2 was 94.55%, the color was yellow, and the acid value was 0.091 mgKOH/g.
3. Third molecular distillation
And the crude ester D2 enters a third-stage molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled to be 200 ℃, the condensation temperature is controlled to be 15 ℃, and the absolute pressure is 0.7Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third-stage molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of R3 is 4.21%, and the color is brown; the yield of D3 was 95.79%, the color was colorless, and the acid value was 0.084 mgKOH/g.
4. Stripping of nitrogen
Filling irregular ceramic ball fillers in a stripping tower 6, preheating an ester intermediate product R3 to 180 ℃, and introducing a distributor from the upper part of the stripping tower 6; meanwhile, nitrogen is preheated to 180 ℃, and is introduced into the stripping tower 6 from the bottom of the stripping tower 6 at the flow rate of 70L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0.5MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.038 mgKOH/g; the water content is 62 mg/kg; the yield of the synthetic ester lubricating oil is 80 percent.
Example 4
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Adding the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 170 ℃, the condensation temperature is controlled to be 15 ℃, and the absolute pressure is 5.5Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 5.65%, and the color is light yellow; the yield of the crude ester D1 was 94.35%, the color was yellow, and the acid value was 1.90 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 was then fed into a second stage molecular distillation apparatus 3 for a second molecular distillation, wherein the distillation temperature of the second molecular distillation was controlled at 170 ℃, the condensation temperature was controlled at 15 ℃ and the absolute pressure was 5.5Pa, to further remove most of the half-esters and a small amount of acid (i.e. R2), yielding crude ester D2 after the half-esters were removed by the second molecular distillation. Wherein, the yield of R2 is 7.25%, and the color is colorless; the yield of the crude ester D2 was 92.75%, the color was yellow, and the acid value was 0.112 mgKOH/g.
3. Third molecular distillation
And the crude ester D2 enters a third-stage molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled to be 195 ℃, the condensation temperature is controlled to be 15 ℃, and the absolute pressure is 1.0Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third-stage molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of R3 is 4.56%, and the color is brown; the yield of D3 was 95.44%, the color was colorless, and the acid value was 0.081 mgKOH/g.
4. Stripping of nitrogen
Filling regular stainless steel packing in a non-corrugated plate form in a stripping tower 6, preheating an ester intermediate product R3 to 180 ℃, and introducing the ester intermediate product into a distributor from the upper part of the stripping tower 6; meanwhile, nitrogen is preheated to 180 ℃, and is introduced into the stripping tower 6 from the bottom of the stripping tower 6 at the flow rate of 60L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0.5MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.048 mgKOH/g; the water content is 80 mg/kg; the yield of the synthetic ester lubricating oil was 82.1%.
Example 5
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Adding the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 175 ℃, the condensation temperature is controlled to be 25 ℃, and the absolute pressure is 5.5Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 7.82%, and the color is light yellow; the yield of crude ester D1 was 92.18%, the color was yellow, and the acid value was 0.82 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 was then fed to a second stage molecular distillation apparatus 3 for a second molecular distillation, wherein the distillation temperature of the second molecular distillation was controlled at 175 ℃, the condensation temperature was controlled at 25 ℃ and the absolute pressure was 1.0Pa, to further remove most of the half-esters and a small amount of acid (i.e. R2), yielding crude ester D2 after the half-esters were removed by the second molecular distillation. Wherein, the yield of R2 is 5.91%, and the color is colorless; the yield of crude ester D2 was 94.09%, the color was yellow, and the acid value was 0.172 mgKOH/g.
3. Third molecular distillation
And the crude ester D2 enters a third-stage molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled to be 195 ℃, the condensation temperature is controlled to be 25 ℃, and the absolute pressure is 0.5Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third-stage molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of R3 is 4.02%, and the color is brown; the yield of D3 was 95.98%, the color was colorless, and the acid value was 0.108 mgKOH/g.
4. Stripping of nitrogen
Filling irregular packing stainless steel packing in a stripping tower 6, preheating an ester intermediate product R3 to 175 ℃, and introducing the intermediate product into a distributor from the upper part of the stripping tower 6; simultaneously, preheating nitrogen to 175 ℃, and introducing the nitrogen into the stripping tower 6 from the bottom of the stripping tower 6 at the flow rate of 40L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.042 mgKOH/g; the water content is 88 mg/kg; the yield of the synthetic ester lubricating oil was 82.05%.
Example 6
In the embodiment, an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst is used as a crude raw material for synthesizing ester lubricating oil, the acid value of the crude raw material is 12.01mgKOH/g, and the crude raw material is stored in a crude ester storage tank 1; the process flow of the crude ester refining method is shown in figure 1, and the refining steps are as follows:
1. first molecular distillation
Adding the crude synthetic ester lubricating oil in the crude ester storage tank 1 into a first-stage molecular distillation device 2 for first molecular distillation, wherein the distillation temperature of the first molecular distillation is controlled to be 180 ℃, the condensation temperature is controlled to be 20 ℃, and the absolute pressure is 8.5Pa, so that most isooctanoic acid and a catalyst (namely R1) in the crude synthetic ester lubricating oil raw material are removed, and the deacidified crude ester D1 formed by the first molecular distillation is obtained. Wherein, the yield of R1 is 8.79 percent, and the color is light yellow; the yield of the crude ester D1 was 91.21%, the color was yellow, and the acid value was 0.95 mgKOH/g.
2. Second molecular distillation
The deacidified crude ester D1 was then fed into a second stage molecular distillation apparatus 3 for a second molecular distillation, wherein the distillation temperature of the second molecular distillation was controlled at 175 ℃, the condensation temperature at 30 ℃ and the absolute pressure at 2.5Pa, to further remove most of the half-esters and a small amount of acid (i.e. R2), and to obtain crude ester D2 after half-esters were removed by the second molecular distillation. Wherein, the yield of R2 is 7.14 percent, and the color is colorless; the yield of the crude ester D2 was 92.86%, the color was yellow, and the acid value was 0.093 mgKOH/g.
3. Third molecular distillation
And the crude ester D2 enters a third-stage molecular distillation device 4 for third molecular distillation, wherein the distillation temperature of the third molecular distillation is controlled to be 190 ℃, the condensation temperature is controlled to be 30 ℃, and the absolute pressure is 0.8Pa, pigment impurities (namely D3) are further removed, and an ester intermediate product R3 which is decolorized by the third-stage molecular distillation is obtained and stored in an intermediate product storage tank 5. Wherein, the yield of R3 is 3.32%, and the color is brown; the yield of D3 was 96.68%, the color was colorless, and the acid value was 0.097 mgKOH/g.
4. Stripping of nitrogen
Filling Raschig ring packing in a stripping tower 6 in a random mode, preheating an ester intermediate product R3 to 175 ℃, and introducing the ester intermediate product into a distributor from the upper part of the stripping tower 6; simultaneously, preheating nitrogen to 175 ℃, and introducing the nitrogen into the stripping tower 6 from the bottom of the stripping tower 6 at a flow rate of 80L/h per kg of light components; wherein, the absolute pressure in the stripping tower 6 is controlled to be 0.3MPa, and the synthetic ester lubricating oil is obtained and stored in an ester product storage tank 7.
5. Nitrogen recycling
And (4) carrying out heat exchange and separation on the product at the top of the stripping tower 6, wherein the separated nitrogen can be recycled for nitrogen stripping.
And measuring the acid value and the water content of the synthetic ester lubricating oil by adopting GB/T7304-2014 oil acid value execution standard and SH/T0255-92 oil water content execution standard. The results show that: the acid value of the synthetic ester lubricating oil is 0.045 mgKOH/g; the water content is 75 mg/kg; the yield of the synthetic ester lubricating oil is 80 percent.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (5)
1. A refining method for a crude product of synthetic ester lubricating oil is characterized by comprising the following steps:
1) sequentially carrying out first molecular distillation and second molecular distillation on the crude product of the synthetic ester lubricating oil;
2) carrying out third molecular distillation on the heavy component formed by the second molecular distillation;
3) carrying out nitrogen gas stripping on the light component formed by the distillation of the third molecule to obtain synthetic ester lubricating oil;
the synthetic ester lubricating oil crude product is a polyol ester lubricating oil crude product; the crude product of the polyol ester lubricating oil is an esterification product generated by esterification reaction of pentaerythritol and isooctanoic acid in the presence of a catalyst;
the temperature of the first molecular distillation is 170-180 ℃, and the absolute pressure is 5.5-10 Pa; the temperature of the second molecular distillation is 170-180 ℃, and the absolute pressure is 1-5.5 Pa; the temperature of the third molecular distillation is 190-;
and (3) carrying out nitrogen stripping on light components formed by the third molecular distillation, wherein the nitrogen stripping comprises the following steps:
preheating nitrogen and light components formed by the third molecular distillation to 175-190 ℃, and then sending the light components to a stripping tower for nitrogen stripping; wherein the absolute pressure in the stripping tower is controlled to be 0-0.5 MPa;
the acid value of the synthetic ester lubricating oil is less than or equal to 0.05mgKOH/g, the water content is less than or equal to 100mg/kg, and the yield is more than or equal to 80 percent.
2. The purification process according to claim 1, wherein the condensation temperatures of the first molecular distillation, the second molecular distillation and the third molecular distillation are each 15 to 30 ℃.
3. The refining method according to claim 1, wherein nitrogen gas is introduced at a flow rate of 40 to 80L/h per kg of the light components formed by the third molecular distillation.
4. The refining method of claim 1, wherein the stripping column is filled with a packing material, and the packing material is a stainless steel packing material, a pall ring packing material, a ceramic ball packing material or a Raschig ring packing material.
5. The refining method of claim 1, wherein the nitrogen is recovered by heat exchange and gas-liquid separation of the top product of the stripping column.
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| CN1594274A (en) * | 2004-07-01 | 2005-03-16 | 江南大学 | Synthesis and purification method of medium chain triglycerides |
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