JPH0613713B2 - An improved method for improving the production of bright stork kraft oil - Google Patents

Description

FIELD OF THE INVENTION This invention relates to lubricating oil production and, more particularly, to improved production of bright-stuck crude oil.

Background of the Invention and Problems Bright Stutskra phenate oil is a high boiling hydrocarbon fraction produced during lubricating oil production and is well known in the art. Generally, in the art, a vacuum residual oil suitable for lubricating oil production is contacted with a propane solvent to extract and deasphalt, and then the propane solvent is stripped off and the resulting extract oil is used as an aromatic solvent. Aromatic hydrocarbons are removed by extraction with, for example, N-methylpyrrolidone (NMP). The resulting extracted, deasphalted oil phase containing predominantly saturated hydrocarbons is known in the commerce as "Brightstouts Kraffinate oil". This raffinate is then contacted with an extractant such as a ketone or alkane hydrocarbon solvent to remove waxy hydrocarbons that are unfavorable to the viscosity characteristics of the lubricating oil, and then hydrofinening to improve the appearance of the oil. And remove sulfur. The produced oil is called "bright stock oil" and serves as a lubricating oil base stock component, which is blended with other lubricating stock components to produce a large number of lubricating oils such as gear oils, machine oils and automobile engine oils.

Current practice in the industry following NMP extraction of deasphalted oil in the lubricating oil process is a residual extract that strips NMP from the extraction phase and is mostly aromatic and contains some recoverable dissolved bright-stochrafinate oil. The oil is sent to a different type of process including the catalytic cracking unit and processed to make fuel oil. Such practices result in a yield debit for the yield of Brightstock stocks, and ultimately Brightstock stocks in the lubricating oil process. This step may be acceptable in view of the fact that recycling of such extract oil through the extraction step again results in a very low recovery rate of recoverable raffinate, with associated recycling costs and process time. It is mainly performed because it is considered not to exist.

Examples of prior art in the art are US Pat. No. 2,570,0
No. 44, the patent discloses recycling aromatic extract oil derived from deasphalt oil to deasphalter feedstock during lubricating oil production. This is disclosed to be done to eliminate the formation of a third phase which tends to contaminate the deasphalt device internals.

In addition, the patent states that the overall yield of components with a higher viscosity index (VI) is increased over conventional systems that do not recycle the extract oil. The same patent also states that the amount of extract oil that is circulated to prevent the attachment of asphalt substances is 3 to 25 volume percent (LV%) based on the atmospheric distillation residual oil charged into the deasphalt treatment tower. It also teaches that. Moreover, it is stated that increasing the amount of recycled extract oil (greater than 25 LV%) does not penalize, and indeed increases the yield of high viscosity index (VI) oils.

SUMMARY OF THE INVENTION Means for Solving the Problems In direct contrast to the teachings of the above-mentioned patent, the circulation of extract oil to a deasphalting unit to produce a lubricated Brightstot Kraffinate oil within specifications. 10 to 10 based on the total atmospheric distillation residual oil (reduced crude) supply
It was found that there was a clear range of 20 LV%. Two
Adding more than 0 LV% extract oil will result in dewaxing raffinate oil Conradson residual carbon (CCR)
Will exceed 1.0 equivalent percent by weight. This is <0.7 wt% required for conventional downstream processing
It becomes an unacceptable Brightstock Stock Conradson carbon residue that exceeds the standard value of. CCR values above the standard value are caused by the high CCR content of the Brightstock Extract oil. In addition, it has been found that recycling of the extract oil accompanied by loss of extraction yield results in a considerable yield credit. These two
As a result of the operation of one feature, the highest yield of high VI oil occurs during the cycle of 10-20 LV% extract oil and adding more than 20 LV% actually lowers the overall yield. start. The subject method is particularly useful in refinery operations conducted under conditions where crude oil is limited.

According to the present invention, (a) a vacuum residue is extracted with a low molecular weight alkane hydrocarbon solvent to produce a deasphalted lubricating oil solution and an asphalt residue, (b) the deasphalted lubricating oil and the residual oil. And (c) separating the hydrocarbon solvent from the deasphalted lubricating oil, and (d) extracting the deasphalted lubricating oil obtained in step (c) with an aromatic solvent to produce a Brightstot Kraft oil. Ate oil solution and extract oil solution, the extract oil solution is composed of dissolved aromatics and recoverable raffinate, and (e) the extract oil solution obtained from step (d) from the raffinate. Separating the solution, and (f) separating the aromatic solvent from the extract oil solution obtained from step (e) comprising the step of solvent extraction of a deasphalt lubricating oil Increase quantity In the method, (g) the extract oil obtained from step (f) and having the aromatic solvent removed is recycled to step (a), and the extract oil is based on the vacuum residual oil and the residual oil. 10-20LV%
After asphalting after combining in step (h), step (a) was repeated, step (i) step (b) was repeated, step (j) step (c) was repeated, and step (j) obtained from step (j) was repeated. Deasphalted oil is extracted with the aromatic solvent to produce the bright stork krainate oil and the extract oil, and the resulting raffinate is compared to the raffinate obtained in step (d). A method is provided characterized in that it is present in a substantially large amount, based on the vacuum residue.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS An understanding of the improved method of the subject invention and details for practicing the subject invention is readily available with reference to FIG.

In FIG. 1, hydrocarbon feedstock such as atmospheric distillation bottoms suitable for lubricating oil production enters vacuum distillation zone 10 via line 12. The distillate is shown as withdrawn from zone 10 by lines 14, 16 and 18. Area 1 suitable for the production of lubricating oil
The vacuum residual oil from 0 passes through the pipe 20, is mixed with the aromatic extract oil (pipe 40) in the pipe 22, and is passed to the deasphalt region 24 (first extraction region). The raw material for the zone 24 is countercurrently contacted with a low-molecular-weight hydrocarbon solvent such as propane that enters through the pipe 26 and is subjected to deasphalt lubricating oil (DA
O) solution and asphalt residual oil are produced, the former being pipeline 2
8 and the latter through line 30. The deasphalted oil enters the second extraction zone 32 from line 28 after propane stripping, where the deasphalted oil is fed to the upper line 34.
A countercurrent contact is made with an aromatic solvent such as N-methylpyrrolidone (NMP) or phenol (for extracting aromatics including benzene, toluene and xylene) that comes from the above. A bright stockstock oil raffinate solution rich in saturates exits from zone 32 through upper line 36 and an extract oil solution consisting of dissolved extracted aromatics and recoverable raffinate is in the lower line. Exit through 38.
After separating the extraction solvent NMP from a part of the extract oil solution, this extract oil part is then passed through line 40 and in line 22 to the deasphalting unit, the reduced pressure coming from line 20. The residual oil raw material and the residual oil are mixed in an amount of 10-20 LV% based on the residual oil. The added extract oil increases the total LV% of the deasphalt unit feed to the deasphalt unit. The remaining extract oil in line 38 is passed through line 42 for cat cracker or other suitable treatment.
The bright stotkraffinate oil obtained through the circulation in the pipeline 36 has the same amount of starting material as the deasphalt unit as compared with that obtained from the vacuum residual oil in which the recycled extract oil is not mixed in the case of the base. It is present in a fairly large amount, based on the vacuum residue.

The yields of bright stork kraphinate oils obtained from vacuum resids are typically in the range of about 3.3 LV% based on resids. The use of extract oil recycle in accordance with the present invention significantly increases the amount of bright stock Tucla Krainate oil that can be recovered to values above about 3.5 LV%.

The distillation zone 10 typically comprises a vacuum distillation zone or a vacuum distillation apparatus. The distillation zone 10 is usually a packed column or a column with a tray. The bottom temperature in zone 10 is typically maintained within the range of about 350 ° to about 450 ° C, while the bottom pressure is maintained at 5 to about 1 ° C.
Keep within the range of 5 cmHg. The particular conditions used are a function of several variables, including the feed used, the distillate specification, and the relative amounts of desired distillate and bottoms oil. Typically, the resulting vacuum residue produced comprises about 10 to about 50 weight percent of all residual oil feed in line 12 and about 370.
It has a boiling point (1 atm) exceeding ° C.

Operation in the deasphalt zone is well known to those skilled in the art.
The deasphalt zone 24 typically comprises a contact zone, preferably a countercurrent contact zone, for contacting the hydrocarbon feedstock entering via line 22 with a solvent such as a liquid light alkane hydrocarbon. The deasphalt zone 24 preferably contains internals, such as sieve trays or shed draw contactors, adapted to enhance intimate liquid-liquid contact. An extract stream containing deasphalto oil and a major part of the solvent exits the deasphalt region 24 to further separate the deasphalt oil and solvent, and recycle the solvent fraction to the deasphalt region 24 via line 40. Reuse. Usually preferred solvents used in the de-asphalt is, C ₂ -C ₈ alkane,
That is, it includes ethane, propane, butane, pentane, hexane, heptane and octane, with propane being most preferred for lubricating oil processing. The operating conditions for the deasphalto zone 24 depend, in part, on the solvent used, the characteristics of the hydrocarbon feedstock, and the desired deasphalt oil or asphalt physical properties. Solvent treatment is typically
It ranges from 200 liquid volume percent (LV%) to about 1000 LV% of residual oil feed added to deasphalt zone 24. Regarding the examination of deasphalting operation, “Advance's Imperatorium Chemistry and Riff Eining” by Jiyeon Wheelie & Sons, New York 5
Vol., Pp. 284-291, the disclosure of which is incorporated herein by reference.

The operation of the lubricating oil extraction zone is well known to those skilled in the art. The extraction zone 32 typically comprises a contact zone, preferably a countercurrent contact zone, in which the hydrocarbon feed coming from line 28 is fed with an aromatic solvent such as N-methylpyrrolidone (NMP), furfural or phenol. Contact with. The extraction zone 32 preferably has internals intended to enhance uniform liquid-liquid contact. A raffinate stream containing a main part of the saturated product and a small part of the extraction solvent exits the extraction zone from the pipe 36, further separates the raffinate and the solvent fraction, and recycles the solvent fraction to the extraction zone 32 for re-production. use. An extract stream containing the main portion of the aromatic and the main portion of the extraction solvent exits the extraction zone from line 38 to further separate the aromatic and solvent fractions and recycle the solvent fraction to the extraction zone 32. And reuse.
The operating conditions for the extraction zone 32 depend, in part, on the solvent used, the characteristics of the hydrocarbon feedstock, and the physical properties of the desired raffinate oil. Solvent treatment is typically
It is in the range of 100 to 400 LV% of the amount of DAO supplied to the extraction zone 32 and contains 0.5 to 6.0 LV% of water.

The following examples illustrate the best mode of carrying out the methods of the subject invention as the inventor believes and should not be considered as limiting the scope and spirit of the invention.

Example 1 To illustrate the present invention, the deasphalt unit feed used during the propane solvent deasphalt process was Arabian Light vacuum bottoms (residue) and Arabian Light DAO (Deasphalt Oil) from the vacuum distillation zone. It was an extract oil derived from. Representative properties of the two materials are summarized in Table 1 below.

Increasing Arabian light bright stock oil production is accomplished by extracting the Arabian light extract oil stream (40), which is an extract from the solvent extraction of Arabian light deasphalt, with the Arabian light depressurization as a feedstock for the deasphalting unit. It was shown by mixing with the residual oil in the proportion of LV% listed in FIG.

Extract oil to vacuum residue 10-based on residual oil
Mixed at 20 LV%. This resulted in a higher LV% of the total feed mixture in addition to the amount of residual oil normally used. In Figure 2, the values for DAO yield in (a) are based on total vacuum residue / extract oil deasphalt feedstock; the values for raffinate yield in (b) are based on DAO to the extraction unit. The values for the increased raffinate yield, which is a bright stock base stock oil as a result of the recycle in (c), are based on total vacuum resid / extract oil deasphalt unit feed.

In the deasphalt unit, the deasphalt unit feed mixture was contacted with the propane solvent by standard procedures. The DAO was then extracted with NMP to Brightstock quality specifications, the appropriate LV% extract oil after stripping the NMP was recycled to the deasphalting unit, and the process was repeated. The yields for deasphalted, extracted and generalized Brightstock stock oil (rafuinate) are graphed in Figure 2 (a-c) as a function of the extract oil cycle of LV% added.
As can be seen in Figure 2 (a), the DAO yield increases with increasing extract oil circulation and the LV% raffinate yield based on the total extraction yield in (b) decreases. As can be seen in FIG. 2 (c), the combination of these effects results in a maximal increase in raffinate yield, ie Brightstock stocks production, in the range of 10-20 LV% recycling of extract oil, especially 15 LV%. . 10 LV
Recycling at levels less than 20% results in diminished brightstock stock yields, and recycling at levels above 20 LV% produces brightstock Conradson carbon residue (CC).
It is difficult to maintain the quality standard of R).

This latter effect is clearly seen in Table 2, which compares the quality of the dewaxed raffinate oil with 0 and 20 LV% extract oil cycle.

Conventional downstream processing (hydrofinening) reduces the CCR of dewaxed roughinate oil by 0.3% by weight. This is a 20 LV% recycling case for Brightstock CCR
Brings to 0.7% by weight, which is equal to the specification. Recycling more than 20 LV% of extract oil makes it very difficult to meet the Brightstock CCR standard and is unacceptable in conventional refinery operations.

Example 2 Using the equipment and general procedure described in Example 1, a non-recycled comparative experiment was conducted versus an experiment using 15 LV% extract oil in the deasphalting unit / extraction process. The experiment in the case of the foundation is shown by the equation 1) and the case of the circulation is shown as 2).

As can be seen from the results shown in the flow diagram of FIG. 3, 34% of the dewaxed oil (DAO) is produced after propane extraction, starting with a reduced pressure residual oil of 1.0 liquid volume (LV) in the case of the base. It came to do. Subsequent NMP solvent extraction produced raffinate in 72% yield based on DAO and 0.245 LV raffinate based on the starting vacuum resid as the deasphalt unit feed.

By way of control, a 1.0 LV vacuum residue was started with 0.175 LV extract oil, representing a recycling of 15 LV%, resulting in a 41% yield of DAO after deasphalting. Subsequent NMP extraction is D
A yield of 55% based on AO was obtained, yielding 0.265 LV rafunate. This represents an increase in production of lahuinate of 8.2%, based on the starting vacuum residue, compared to the base without recycling.

[Brief description of drawings]

FIG. 1 is a simplified process diagram showing the apparatus and connections of one embodiment for carrying out the subject invention. Figure 2 is obtained by carrying out the subject invention and includes the following: (a) Deasphalt oil (DAO) yield based on total deasphalt unit feed, (b) Raffinate yield based on total extracted unit feed. (C) Three different plots showing the variable of raffinate yield, based on total deasphalt unit feed, as a function of extract oil circulation by LV%. FIG. 3 is a schematic diagram of the process showing that the yield of raffinate is increased when using the recycle of extract oil as compared to the base case (no recycle). In Figure 3, 1) is the case of foundation (no circulation), 2) is 15L.
Represents V% recycling.

Claims (5)

[Claims] 1. A vacuum residue is extracted with a low molecular weight alkane hydrocarbon solvent to produce a deasphalted lubricating oil solution and an asphalt residual oil, and (b) the deasphalted lubricating oil and the residual oil. And (c) separating the hydrocarbon solvent from the deasphalted lubricating oil, and (d) extracting the deasphalted lubricating oil obtained from step (c) with an aromatic solvent to obtain a bright stock raffinate oil solution. And an extract oil solution, wherein the extract oil solution is composed of dissolved aromatics and recoverable raffinate, and (e) separates the raffinate solution from the extract oil solution obtained from step (d). And (f) increasing the amount of bright stock raffinate oil derived from solvent extraction of deasphalted lubricating oil, including the step of separating the aromatic solvent from the extract oil solution obtained from step (e). In the method, (g) the extract oil obtained from the step (f) and having the aromatic solvent removed is recycled to the step (a), and the extract oil is based on the vacuum residual oil and the residual oil. 10-20LV%
After assembling in step (a), (h) step (a) is repeated, (i) step (b) is repeated, (j) step (c) is repeated, and (k) step (j) is obtained. Deasphalted oil is extracted with the aromatic solvent to produce the bright stock raffinate oil and the extract oil, the raffinate obtained compared to the raffinate obtained in step (d) and the vacuum residue. A method characterized in that it is present in a considerably large amount, based on the oil. 2. The method according to claim 1, wherein in step (g) the extract oil is combined with the vacuum residue at 15 LV% and then deasphalted. 3. The method according to claim 1, wherein the hydrocarbon solvent in step (a) is propane. 4. The method according to claim 1, wherein the aromatic solvent in step (d) is N-methylpyrrolidone. 5. The method according to claim 1, wherein the obtained bright stock raffinate oil has a Conradson method residual carbon value of 1.0% by weight or less.