A method of solvent dewaxing of lubricating oil, especially a method of solvent dewaxing of oil using additives for lubrication. The method of the present invention is suitable for solvent dewaxing of vacuum distillate oil and solvent dewaxing of heavy distillate oil, and is particularly suitable for decompression. The vacuum heavy distillate oil mentioned in the present invention includes reduced fourth-line distillate oil and vacuum residual oil. of light asphalt oil.
Background technique
There are two main types of dewaxing for lubricating oil: solvent dewaxing and catalytic dewaxing. The traditional solvent dewaxing method is to add solvent fractions to the dewaxed raw material, cool it to low temperature to crystallize and precipitate the wax, and then filter it to separate the oil and wax. .
In waxy petroleum fractions, the petroleum waxes contained are mainly long-chain normal alkanes and isoparaffins. As the boiling point increases, the content of isoparaffins increases. When normal alkanes precipitate out of a solvent, they form large intact crystals, whereas isoparaffins do not form perfect crystals of any size when they crystallize from a solvent.
In the solvent dewaxing of lubricating oils, especially during the heavy fraction solvent dewaxing process, isoparaffins form tiny crystals, which increase the filtration speed and reduce the filter cake, thus affecting the dewaxed oil yield and the processing capacity of the production equipment.
The role of the dewaxing agent is to take the lead in forming "seed crystals" with good crystallization during the cooling process of the wax oil. Through nucleation, absorption, eutectic and other functions, the wax can form crystals with uniform size and good discreteness, thereby improving the filterability of the dewaxed oil. speed and output.
A method of solvent dewaxing of lubricating oil using a dewaxing agent is disclosed. The method uses a mixture of olefin polymer and alcohol-based polymer as the dewaxing agent, which can increase the filtration speed and the dewaxed oil yield. However, the oxygen molecular additives and two bonds in the auxiliary agent are mixed into the wax, which has an adverse effect on the stability of the wax. It must be removed before it can be used in some strict wax application fields. It will be more difficult to separate the auxiliary agent from the wax. crafting process.
Contents of the invention
The invention provides a solvent dewaxing method using auxiliaries. In increasing the filtration speed and dewaxing oil yield, the auxiliaries used do not need to be separated from the wax and the properties of the wax are not affected. had a negative impact.
The solvent dewaxing method using a dewaxing agent of the present invention includes the following contents: mixing the molten dewaxing raw material and the dewaxing agent, then adding the dewaxing solvent and cooling it to the dewaxing temperature. The solvent can be added by using a multi-point dilution method. Or use a full dilution process to obtain the pressed oil and dewaxed residual wax by filtration and separation at the dewaxing temperature.
The dewaxing agent is a high melting point Fischer-Tropsch synthetic wax. For any fraction of Fischer-Tropsch synthetic wax greater than 530°C, with a carbon number of 40 to 100, and a molecular weight of 560 to 1350, the added dewaxing agent accounts for 10% of the dewaxing raw material. The weight percentage is 0.02% to 5%, preferably 0.05% to 2%.
The dewaxed raw material is generally vacuum distillate oil, including light lubricating oil, reduced third-line distillate oil, reduced fourth-line distillate oil and light asphalt wet products of vacuum residual oil.
The solvent may be a C 3 to C 6 aliphatic ketone or a mixture thereof, or a mixture of a ketone and a C 6 to C 8 aromatic hydrocarbon. More suitable solvents are methyl ethyl ketone, methyl isobutyl ketone (MIBK), methyl ethyl ketone/methyl isobutyl ketone (MIBK) and methyl ethyl ketone/toluene. The recommended solvent is a mixture of methyl ethyl ketone and toluene. The ketone content in the methyl ethyl ketone/toluene mixed solvent is usually 40wt%~90wt%, and a more suitable ratio is 60wt%~85wt%. Other processes and conditions for operating solvent dewaxing are well known to those skilled in the art. As for the amount of solvent, dewaxing temperature, etc., according to the nature of the dewaxing raw material and the type of solvent, those skilled in the art will choose the weight ratio of the total amount of fresh solvent to the total amount of waxy raw oil in the existing solution. It is 2:1~10:1, preferably 3:1~6:1, and the dewaxing temperature is -30~0°C.
According to the method of the present invention, the filtration speed of solvent dewaxing can be significantly increased, the yield of dewaxed oil can be greatly improved, and the oil and wax separation effect is good.
