U.S. patent application number 12/728674 was filed with the patent office on 2010-09-30 for extraction of aromatics from hydrocarbon oil using n-methyl 2-pyrrolidone and co-solvent.
This patent application is currently assigned to Indian Oil Corporation Limited. Invention is credited to B. Basu, I. Devotta, P. Mohanasundaram, N. S. Raman, S. K. Singhal.
Application Number | 20100243533 12/728674 |
Document ID | / |
Family ID | 42782805 |
Filed Date | 2010-09-30 |
United States Patent
Application |
20100243533 |
Kind Code |
A1 |
Raman; N. S. ; et
al. |
September 30, 2010 |
EXTRACTION OF AROMATICS FROM HYDROCARBON OIL USING N-METHYL
2-PYRROLIDONE AND CO-SOLVENT
Abstract
The present invention provides a process for extraction of
aromatic material from hydrocarbon oil by using a solvent mixture
comprising N-Methyl-2-Pyrrolidone (NMP), at least one co-solvent
and optionally water, to obtain a raffinate. The process of the
present invention lowers operating cost as the cost of the
co-solvent employed is lower than that of neat NMP. Another feature
of the present invention is that it produces the same quality
raffinate as those of neat NMP-water measured by the refractive
index but produces higher yield of raffinate at same feed to
solvent mixture ratio.
Inventors: |
Raman; N. S.; (Faridabad,
IN) ; Mohanasundaram; P.; (Faridabad, IN) ;
Devotta; I.; (Faridabad, IN) ; Singhal; S. K.;
(Faridabad, IN) ; Basu; B.; (Faridabad,
IN) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Assignee: |
Indian Oil Corporation
Limited
Faridabad
IN
|
Family ID: |
42782805 |
Appl. No.: |
12/728674 |
Filed: |
March 22, 2010 |
Current U.S.
Class: |
208/326 |
Current CPC
Class: |
C10G 21/20 20130101;
C10G 21/16 20130101; C10G 21/02 20130101 |
Class at
Publication: |
208/326 |
International
Class: |
C10G 21/20 20060101
C10G021/20 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 25, 2009 |
IN |
584/DEL/2009 |
Claims
1. A process for extraction of aromatic material from hydrocarbon
oil, said process comprising: contacting the hydrocarbon oil with a
solvent mixture to obtain an extract phase and a raffinate product
phase, wherein the solvent mixture comprises N-Methyl-2-Pyrrolidone
(NMP) and at least one co-solvent capable of facilitating phase
separation; and separating the extract phase from the raffinate
product phase, wherein the extract phase contains the aromatic
material.
2. The process as claimed in claim 1, further comprising: obtaining
the raffinate from the raffinate product phase by removing the
solvent from the raffinate phase.
3. The process as claimed in claim 1, wherein the hydrocarbon oil
is a lube oil distillate.
4. The process as claimed in claim 1, wherein the hydrocarbon oil
has a boiling point in the range of 150.degree. C. to 600.degree.
C.
5. The process as claimed in claim 1, wherein the co-solvent is a
N,N-dimethyl amide.
6. The process as claimed in claim 1, wherein the co-solvent is
selected from the group consisting of formamide, N-methyl
formamide, N,N-dimethyl formamide, acetamide, N-methyl acetamide,
N,N-dimethyl acetamide, Propionamide, N-methyl propionamide and
N,N-dimethyl propionamide or mixtures thereof.
7. The process as claimed in claim 1, wherein the ratio of NMP and
co-solvent in the solvent mixture is in the range of 40:60 (w/w) to
90:10 (w/w).
8. The process as claimed in claim 1, wherein the hydrocarbon oil
and the solvent mixture are in the weight ratio in the range of
1:0.8 to 1:2.5.
9. The process as claimed in claim 1, wherein the process is either
a continuous counter current extraction process or a batch
extraction process.
10. The process as claimed in claim 1, wherein the solvent mixture
is recovered and reused in the process.
11. A process for extraction of aromatic material from hydrocarbon
oil, said process comprising: contacting the hydrocarbon oil with a
solvent mixture to obtain an extract phase and a raffinate product
phase, wherein the solvent mixture comprises N-Methyl-2-Pyrrolidone
(NMP), water and at least one co-solvent capable of facilitating
phase separation; and separating the extract phase from the
raffinate product phase, wherein the extract phase contains the
aromatic material.
12. The process as claimed in claim 11, further comprising:
obtaining the raffinate from the raffinate product phase by
removing the solvent from the raffinate phase.
13. The process as claimed in claim 11, wherein the hydrocarbon oil
is a lube oil distillate.
14. The process as claimed in claim 11, wherein the hydrocarbon oil
has a boiling point in the range of 150.degree. C. to 600.degree.
C.
15. The process as claimed in claim 11, wherein the co-solvent is a
N,N-dimethyl amide.
16. The process as claimed in claim 11, wherein the co-solvent is
selected from the group consisting of formamide, N-methyl
formamide, N,N-dimethyl formamide, acetamide, N-methyl acetamide,
N,N-dimethyl acetamide, Propionamide, N-methyl propionamide and
N,N-dimethyl propionamide or mixtures thereof.
17. The process as claimed in claim 11, wherein the solvent mixture
comprises water in the range of 0.1 wt % to 5.0 wt %.
18. The process as claimed in claim 11, wherein the weight ratio of
NMP with water and co-solvent in the solvent mixture is in the
range of 50:50 (w/w) to 95:5 (w/w).
19. The process as claimed in claim 11, wherein the hydrocarbon oil
and the solvent mixture are in the weight ratio in the range of
1:0.8 to 1:2.5.
20. The process as claimed in claim 11, wherein the process is
either a continuous counter current extraction process or a batch
extraction process.
21. The process as claimed in claim 11, wherein the solvent mixture
is recovered and reused in the process.
Description
[0001] This application claims priority benefit from Indian
Provisional Application No. 584/DEL/2009, filed on Mar. 25, 2009,
the entire content of which is hereby incorporated by reference in
its entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to a process for extraction of
aromatic material from hydrocarbon oil by addition of a solvent
mixture comprising N-Methyl-2-Pyrrolidone (NMP), at least one
co-solvent and optionally water, to obtain a raffinate.
[0003] The raffinate obtained by the process of the present
invention is of a higher yield than that obtained by conventional
process at the same solvent mixture to feed ratio. The raffinate
obtained also maintains the same quality as those obtained by
process using neat NMP-water which is measured by the refractive
index.
BACKGROUND OF THE INVENTION
[0004] Solvent extraction process is a process employed for the
removal of constituents that would have an adverse effect on the
performance of the product in use. In petroleum refining industry,
all automobile lubricating oils/hydrocarbon oils are subjected to
solvent extraction process, to extract the undesirable constituents
such as aromatic materials (having low hydrogen to carbon ratio)
from the more desirable paraffinic hydrocarbons (having relatively
high hydrogen to carbon ratio). Lube distillates rich in aromatic
hydrocarbons like benzene, toluene, and the xylenes but with higher
carbon number are separated from the paraffinic hydrocarbons with
suitable solvents. The process separates the hydrocarbon oil into
two phases, a raffinate phase, which contains the paraffinic
hydrocarbons and an extract phase, which contains the aromatic
materials.
[0005] The process involves the use of solvents such as furfural,
phenol and N-methyl-2-pyrrolidone (NMP) which are selective for the
aromatic materials present in the hydrocarbon oils feed stream.
N-methyl-2-pyrrolidone (NMP) has been used to selectively extract
aromatic components from hydrocarbon oils, as disclosed in U.S.
Pat. No. 3,929,616, U.S. Pat. No. 4,013,549, U.S. Pat. No.
4,909,927 and U.S. Pat. No. 5,041,206.
[0006] U.S. Pat. No. 4,013,549 discloses an upgradation of
lubricating oil stocks by contacting them with a solvent comprising
a mixture of N-methyl-2-pyrrolidone (NMP) and phenol. The solvent
also contains a minor amount of water. However in this prior art,
the increase in raffinate yield is not disclosed. U.S. Pat. No.
4,909,927 discloses use of combination of extraction solvent, such
as N-methyl pyrrolidone, phenol, furfural, ethyl benzene or
morpholine for removal of aromatic hydrocarbon components from
hydrocarbon oils, particularly petroleum oils, lube, transformer,
white oil and other specialty oils.
[0007] In U.S. Pat. No. 3,415,743, use of dimethyl formamide and
water solvent solution for extraction of cracked cycle oil is
disclosed. U.S. Pat. No. 3,929,617 discloses the use of mixture of
solvent including furfural, phenol, N-methyl 2-pyrrolidone,
dimethyl formamide for extraction of hydrocrackate. However, in
both the prior arts, increase in the raffinate yield from
hydrocarbon oil on the addition of a co-solvent is not
disclosed.
[0008] U.S. Pat. No. 5,922,193 discloses addition of ethers or
aldehydes to furfural to improve the solvent capacity for debottle
necking the extraction unit. It also claims 2 to 3 volume %
increase in the raffinate yield during the process. In U.S. Pat.
No. 4,273,645, additives such as, sodium dodecylbenzene sulfonate
or high molecular weight polyethylene oxide resin is added to
improve the selectivity of furfural. It claims less than 3 volume %
increase in the raffinate yield at solvent dosage of 250 volume %.
Further, in the said patent document, the recovery and material
balance of the additive employed is not disclosed. U.S. Pat. No.
6,866,772 discloses use of co-solvent for furfural extraction
process to increase raffinates yield but the use of co-solvent with
NMP is not discussed.
[0009] Hence there is a need for a process for producing a
raffinate by removal of aromatic material from hydrocarbon oil, in
a higher yield and a low operational cost.
SUMMARY OF THE INVENTION
[0010] The present invention relates to a process for extraction of
aromatic material from hydrocarbon oil, said process comprising
contacting the hydrocarbon oil with a solvent mixture to obtain an
extract phase and a raffinate product phase, wherein the solvent
mixture comprises N-Methyl-2-Pyrrolidone (NMP), with or without
water and at least one co-solvent capable of facilitating phase
separation; and separating the extract phase from the raffinate
product phase, wherein the extract phase contains the aromatic
material.
[0011] The present invention further relates to obtaining the
raffinate from the raffinate product phase by removing the solvent
from the raffinate phase.
[0012] These and other features, aspects, and advantages of the
present subject matter will become better understood with reference
to the following description and appended claims. This summary is
provided to introduce a selection of concepts in a simplified form.
This summary is not intended to identify key features or essential
features of the claimed subject matter, nor is it intended to be
used to limit the scope of the claimed subject matter.
DETAILED DESCRIPTION OF THE INVENTION
[0013] The present invention relates to a process for extraction of
aromatic material from hydrocarbon oil, said process comprising
contacting the hydrocarbon oil with a solvent mixture to obtain an
extract phase and a raffinate product phase, wherein the solvent
mixture comprises N-Methyl-2-Pyrrolidone (NMP), and at least one
co-solvent capable of facilitating phase separation; and separating
the extract phase from the raffinate product phase, wherein the
extract phase contains the aromatic material.
[0014] The present invention further relates to obtaining the
raffinate from the raffinate product phase by removing the solvent
from the raffinate phase.
[0015] In the present invention, the term `aromatic material`
refers to aromatic compounds having low hydrogen to carbon ratio.
These materials may be aromatic hydrocarbons like benzene, toluene,
and the xylenes but with higher carbon number. The term `aromatic
material` will also encompass a single type of aromatic material or
a combination of different aromatic materials.
[0016] In the present invention the term `raffinate` is the used to
define the hydrocarbon oil lean in the aromatic materials, wherein
the aromatic materials have been extracted from the hydrocarbon oil
by the process of the present invention.
[0017] The process of the present invention provides an increased
yield of raffinate with the use of at least one co-solvent along
with N-Methyl-2-Pyrrolidone (NMP) by more than 6 wt % than the
raffinate obtained by using NMP in an extraction process without
the addition of any co-solvent.
[0018] In an embodiment of the present invention, the hydrocarbon
oil is a lube oil distillate.
[0019] In another embodiment of the present invention, the
hydrocarbon oil is a lube oil distillate comprising 25 wt % to 80
wt % of aromatic material.
[0020] In still another embodiment of the present invention, the
hydrocarbon oil is a lube oil distillate comprising 30 wt % to 60
wt % of aromatic material.
[0021] In yet another embodiment of the present invention, the
hydrocarbon oil has a boiling point in the range of 150.degree. C.
to 600.degree. C.
[0022] In another embodiment of the present invention, the
hydrocarbon oil has a boiling point in the range of 240.degree. C.
to 565.degree. C.
[0023] In an embodiment of the present invention, the co-solvent
used in the process is an N,N-dimethyl amide.
[0024] In another embodiment of the present invention, the
co-solvent used in the process is selected from the group
consisting of formamide, N-methyl formamide, N,N-dimethyl
formamide, acetamide, N-methyl acetamide, N,N-dimethyl acetamide,
Propionamide, N-methyl propionamide and N,N-dimethyl propionamide
or mixtures thereof.
[0025] In still another embodiment of the present invention, the
co-solvent used in the process is N,N-dimethyl formamide.
[0026] In yet another embodiment of the present invention, the
ratio of NMP and co-solvent in the solvent mixture is in the range
of 40:60 (w/w) to 90:10 (w/w).
[0027] In another embodiment of the present invention, the ratio of
NMP and co-solvent in the solvent mixture is in the range of 50:50
(w/w) to 85:15 (w/w).
[0028] In an embodiment of the present invention, the hydrocarbon
oil and solvent mixture are taken in the weight ratio in the range
of 1:0.8 to 1:2.5, referred as solvent mixture dosage in the range
of 80 wt % to 250 wt %.
[0029] In another embodiment of the present invention, the
hydrocarbon oil and solvent mixture are taken in the weight ratio
less than 1:2.2, referred as solvent mixture dosage less than 220
wt %.
[0030] In yet another embodiment of the present invention, the
hydrocarbon oil and solvent mixture are taken in the weight ratio
less than 1:1.8, referred as solvent mixture dosage less than 180
wt %.
[0031] In still another embodiment of the present invention,
hydrocarbon oil and solvent mixture are taken in the weight ratio
less than 1:1.5, referred as solvent mixture dosage less than 150
wt %.
[0032] In an embodiment of the present invention, the process of
extraction is a continuous counter current extraction process.
[0033] In another embodiment of the present invention, the process
of extraction is a batch extraction process.
[0034] In an embodiment of the present invention, the solvent
mixture comprises NMP and co-solvent with or without water.
[0035] In another embodiment of the present invention, the water in
the solvent mixture is in the range of 0.0 wt % to 5.0 wt %.
[0036] In still another embodiment of the present invention, the
water in the solvent mixture is in the range of 0.0 wt % to 3.0 wt
%.
[0037] In yet another embodiment of the present invention, the
water in the solvent mixture is in the range of 0.0 wt % to 1.5 wt
%.
[0038] In an embodiment of the present invention, the solvent
mixture comprises NMP, co-solvent and water.
[0039] In another embodiment of the present invention, the water in
the solvent mixture is in the range of 0.1 wt % to 5.0 wt %.
[0040] In still another embodiment of the present invention, the
water in the solvent mixture is in the range of 0.1 wt % to 3.0 wt
%.
[0041] In yet another embodiment of the present invention, the
water in the solvent mixture is in the range of 0.3 wt % to 1.5 wt
%.
[0042] In an embodiment of the present invention, the weight ratio
of NMP with water and co-solvent in the solvent mixture is in the
range of 50:50 (w/w) to 95:5 (w/w).
[0043] In another embodiment of the present invention, the weight
ratio of NMP with water and co-solvent in the solvent mixture is in
the range of 65:35 (w/w) to 85:15 (w/w).
[0044] In an embodiment of the present invention, the solvent
mixture is recovered and reused in the process.
[0045] In an embodiment of the present invention, the yield of
raffinate increases by more than 2 wt % with addition of at least
one co-solvent compared to a N-Methyl-2-Pyrrolidone (NMP)
extraction process without the addition of any co-solvent.
[0046] In another embodiment of the present invention, the yield of
raffinate increases by more than 6 wt % with addition of at least
one co-solvent compared to a N-Methyl-2-Pyrrolidone (NMP)
extraction process without the addition of any co-solvent.
[0047] The present invention relates to an improved NMP extraction
process for the removal of aromatic material from hydrocarbon oil,
more particularly from lube oil distillate containing aromatic
material by addition of a solvent mixture comprising NMP and at
least one co-solvent with or without addition of water.
[0048] NMP is mainly employed because of its high solvent power and
complete miscibility with water. Moreover, it is environmental
friendly and the miscibility temperature is low. It can be used for
the extraction process at lower solvent to feed ratio as compared
to the extraction process where furfural is used. Also the
operating temperature is lower when NMP is used in the solvent
mixture as compared to furfural.
[0049] It is a feature disclosed in the present invention that
addition of the co-solvent in NMP and water, conducted in a batch
process or a continuous countercurrent extraction column
facilitates phase separation and increases raffinate yield while
maintaining the same raffinate quality as those of neat NMP-water
measured by the refractive index but producing higher yield of
raffinate at same solvent mixture to feed ratio. It also lowers the
operating cost as the cost of the co-solvent employed is lower than
that of neat NMP.
[0050] In this process, addition of co-solvent, preferably a
mixture of N,N-dimethyl amides to NMP and water is done to
facilitate phase separation and selectivity, wherein the raffinate
yield increases by more than 5 wt % for Inter neutral distillate
(IN), feed at solvent mixture dosage less than 250 wt %, preferably
at solvent mixture dosage less than 150 wt %.
[0051] Similarly, addition of the co-solvent in NMP and water,
conducted in a batch extraction setup results in an increase in
raffinate yield by more than 2 wt % for Heavy neutral (HN)
distillate feed at solvent mixture dosage less than 250 wt %,
preferably at solvent mixture dosage less than 180 wt %.
[0052] Also, addition of the co-solvent in NMP without water,
conducted in a batch extraction setup results in an increase in
raffinate yield by more than 3 wt % for IN distillate feed and by
2% in HN distillate at solvent mixture dosage less than 250 wt %,
preferably at solvent mixture dosage less than 180 wt %.
[0053] The process is applicable to hydrocarbon oils, preferably
lube oil distillates. The feedstock typically comprises hydrocarbon
oils having initial boiling point of greater than 150.degree. C.
and a final boiling point of about 600.degree. C., preferably those
fractions having a boiling point in the range of about 240.degree.
C. to 565.degree. C. These lube oil distillate stocks namely,
spindle oil (SO), light neutral (LN), inter neutral (IN) and heavy
neutral (HN) and deasphalted oil (DAO) are used in this process and
these distillates are fractions of vacuum tower.
[0054] The extraction of the present invention is conducted by
contacting the lube oil distillate with a selective solvent, NMP.
Since the feed stock contains aromatic material usually ranging
from at least 25 wt %, preferably from 25 wt % to 80 wt % and more
preferably from 30 wt % to 60 wt %, the feed stock is initially
subjected to an extraction step. Extraction process utilizes a
solvent, which is selective for aromatic material, such as a
mixture of NMP and at least one co-solvent, and removes the
aromatic material, which contributes to poor stability and
viscosity index. Removal of aromatic material improves the
viscosity index, colour, oxidative stability, thermal stability and
inhibition response of the base oil. The solvent extraction is
conducted with hydrocarbon oil to solvent mixture in the weight
ratio in the range of from about 1:0.8 to 1:2.5, more preferably in
the range from about 1:1.2 to 1:1.8, depending on the feed stock.
The operating conditions for NMP extraction cover a temperature
range of about 25.degree. C. to 250.degree. C., more preferably
from 50 to 200.degree. C.
[0055] The characteristics of the product of solvent extraction are
very important and consideration of the solvent extraction
conditions coupled with the choice of the feed is necessary to
achieve a product with desired viscosity and Viscosity Index (VI).
Maximum yield of high VI product is achieved by adjusting the
extraction severity. The resulting raffinate has a VI of at least
about 85, preferably 90 or above. The raffinate (after extraction
of aromatic material) contains at the most about 40 wt % of
aromatic material, preferably ranging from about 10 to 30 wt %,
more preferably from 10 to 20 wt %. The extraction is performed by
conventional means, such as in a batch extraction column or
multistage counter current system, in a column with packing
material or provided with perforated plates or in a column with
rotating shaft provided with discs.
[0056] The process of the present invention involves the addition
of at least one co-solvent to NMP and water or NMP alone to
facilitate phase separation, selectivity and increase in raffinate
yield. The co-solvent is selected from N,N-dimethyl amides,
preferably selected from the group consisting of formamide,
N-methyl formamide, N,N-dimethyl formamide, acetamide, N-methyl
acetamide, N,N-dimethyl acetamide, propionamide, N-methyl
propionamide and N,N-dimethyl propionamide or mixtures thereof,
more preferably N, N-dimethyl formamide. The properties of the
co-solvent employed for the present invention is listed in Table
I.
TABLE-US-00001 TABLE I Melting Boiling Refractive
Density@20.degree. C. S. No Name of Solvent Point (.degree. C.)
point (.degree. C.) Index @ 20.degree. C. gm/ml 1 Formamide 2-3 210
1.447 1.134 2 N-Methyl -4 198-199 1.432 1.001 Formamide 3 N,N-Di
Methyl -61 153 1.431 0.945 Formamide 4 Acetamide 79-91 221 -- -- 5
N-Methyl 26-28 204-206 1.433 0.957 Acetamide 6 N,N-Di Methyl -20
164.5-166 1.438 0.937 Acetamide 7 Propionamide 80-83 213 -- 1.042 8
N-Methyl -43 79 1.377 0.915 Propionamide 9 N,N-Di Methyl -45
174-175 1.440 0.920 Propionamide
[0057] Generally, the co-solvent is added in an amount less than
about 60 weight % based on total solvent mixture, less than about
50 wt % based on total solvent mixture, less than about 40 wt %
based on total solvent mixture; less than about 30 wt % based on
total solvent mixture, less than about 20 wt % based on total
solvent mixture; depending on the feedstock.
[0058] For example, a 30 wt % co-solvent, 0.75 wt % water and NMP
blend as solvent mixture is used in the extraction process of the
present invention when the feedstock is Arab Mix Inter-Neutral
distillate. For example, in the solvent mixture comprising NMP and
co-solvent (without water), 50 wt % co-solvent and 50 wt % NMP
blend is used in the extraction process of the present invention
when the feedstock is Arab Mix Inter-neutral distillate.
Co-solvents used in the process of the present invention have a
boiling point in the range of from about 70.degree. C. to
225.degree. C., preferably in the range of from about 140.degree.
C. to 200.degree. C. Use of co-solvents in NMP extraction process
increases the raffinate yield at the same raffinate refractive
index (RI) compared to NMP-water system at the same operating
condition.
Advantages
[0059] The previously described versions of the subject matter and
its equivalent thereof have many advantages, including those which
are described below.
[0060] The advantage of the present invention allows for
retrofitting existing equipments. Another advantage of the present
invention is use of solvent mixture comprising NMP and at least one
co-solvent with water or without water which lowers operating cost
as the cost of the co-solvent employed is lower than that of neat
NMP. Another additional advantage of using solvent mixture is that
it produces same quality raffinate as those of neat NMP-water
measured by the refractive index but produces higher yield of
raffinate at same feed to solvent mixture ratio. Yet another
advantage of using solvent mixture is the flexibility in extraction
of various feedstocks. It can be employed for lighter lube
distillate namely, spindle oil extraction to heavier oil namely,
deasphalted oil extraction.
EXAMPLES
[0061] The disclosure will now be illustrated with working
examples, which is intended to illustrate the working of disclosure
and not intended to take restrictively to imply any limitations on
the scope of the present disclosure.
Example 1
[0062] Liquid-liquid equilibrium (LLE) batch extraction was
performed using NMP and water as the solvent mixture in lab scale
jacketed glass extraction apparatus batch. The feed, Arab Mix Inter
neutral (IN) distillate was preheated. 150 gm of feed, whose
properties are given in Table 2, and 180 gm of solvent mixture were
fed into the extraction apparatus. The temperature of the
equilibrium setup is kept at 70.degree. C. The feed and solvent
were mixed well using a stirrer. The stirrer speed was kept
constant throughout the 90 minutes of mixing time. After mixing the
content, it was kept for 3 hours to settle i.e. allow complete
phase separation. After the settling of phases, the extract and
raffinate phases were separated accurately and collected
separately. The raffinate and extract phases were weighed
accurately with precision balance to ensure material balance. The
solvent was stripped both from the extract and raffinate with
nitrogen under vacuum. The stripped raffinate and extract phases
were weighed and the raffinate yield was obtained based on the
feed. Final raffinate samples were analyzed for refractive
index.
TABLE-US-00002 TABLE 2 S. No Properties Result 1 Density @
15.degree. C., gm/ml 0.9409 2 Refractive Index @ 50.degree. C.
1.51587 3 Kinematic viscosity, cSt @ 100.degree. C. 14.10 4
Distillation (ASTM-1160), .degree. C. 5 Vol % Recovery 456 50/90
496/526 95 529
Example 2
[0063] The same experiment as in example 1 was performed with NMP,
water and at least one co-solvent as the solvent mixture.
[0064] The comparative results from the Liquid-Liquid Equilibrium
(LLE) studies on Inter neutral distillate of example 1 and example
2 are shown in the Table 3.
TABLE-US-00003 TABLE 3 (Feed to Solvent mixture ratio is 1:1.2 w/w)
Co-solvent Composition Raffinate Solvent system (wt %) Yield (wt %)
RI @ 50.degree. C. NMP + 1.5% Water 0 64.7 1.49680 NMP + Co-solvent
+ 20 66 1.49625 0.75% Water 30 68.6 1.49664
[0065] Commercially, lube extraction units are operated to a
Refractive Index (RI) specification since for a particular lube
crude and type of refining process, raffinate RI correlates with
the viscosity index (VI) of the de-waxed oil (DWO), with lower RI
corresponding to higher VI.
[0066] Analysis of the data in Table 3 shows that for extraction
conducted at feed to solvent mixture weight ratio of 1:1.2, the
NMP, water and 30 wt % co-solvent mixture was more effective than
NMP and water alone, resulting in more than 3 wt % improvement in
raffinate yield at the same raffinate RI.
Example 3
[0067] LLE extraction was performed in batch extraction apparatus
using NMP and water as the solvent mixture. The feed, Arab Mix
Heavy Neutral (HN) distillate, properties of which are shown in
Table 4, was preheated. 150 gm of feed and 225 gm of solvent
mixture were fed in to the extraction setup. The temperature of the
content was kept at 80.degree. C. The feed and solvent were mixed
with the help of a stirrer. The stirrer speed was kept constant
throughout the 90 minutes of mixing period. After mixing, the
content was kept for 3 hours to allow complete settling. After the
settling of phases, the extract and raffinate phase were collected
separately. The raffinate and the extract phase were weighed
accurately with precision balance to ensure material balance. The
solvent was stripped from the extract and raffinate with nitrogen
purging under vacuum. The stripped raffinate and extract phases
were weighed and the raffinate yield was determined. Final
raffinate samples were analyzed for refractive index.
TABLE-US-00004 TABLE 4 S. No Properties Result 1 Density @
15.degree. C., gm/ml 0.9521 2 Refractive Index @ 50.degree. C.
1.52549 3 Kinematic viscosity, cSt @ 100.degree. C. 28.05 4
Distillation (ASTM-1160), .degree. C. 5 Vol % Recovery 491 50/90
549/573 95 575
Example 4
[0068] The same experiment as in example 3 was performed with NMP,
water and at least one co-solvent as the solvent mixture.
[0069] The results from the LLE studies of Heavy neutral Distillate
of example 3 and example 4 is shown in the Table 5.
TABLE-US-00005 TABLE 5 (Feed to Solvent mixture ratio is 1:1.5 w/w)
Co-solvent Composition Raffinate Solvent system (wt %) yield (wt %)
RI @ 50.degree. C. NMP + 1% Water 0 65.0 1.50232 NMP + Co-solvent +
0.5% 30 67.3 1.50256 Water NMP + Co-solvent + 30 67.0 1.50203 0.3%
Water
[0070] Analysis of the data in Table 5 shows that for extraction
conducted at feed to solvent mixture weight ratio of 1:1.5, the
NMP, water and 30 wt % co-solvent mixture was more effective than
NMP and water alone, resulting in more than 2 wt % improvement in
raffinate yield at same raffinate RI.
Example 5
[0071] LLE extraction was performed in batch jacketed glass
extraction apparatus using NMP and water as the solvent mixture.
The feed, Arab Mix Inter Neutral (IN) distillate was preheated. 150
gm of feed and 180 gm of solvent mixture were fed in to the
extraction setup. The temperature of the column was maintained at
70.degree. C. The experimental procedure was same as in Example 1.
Final raffinate samples were analyzed for refractive index.
Example 6
[0072] The same experiment as in example 5 was performed with NMP,
water and at least one co-solvent as the solvent mixture.
[0073] The results from the LLE Extraction of Inter neutral
distillate of example 5 and example 6 is shown below in Table
6.
TABLE-US-00006 TABLE 6 (Feed to Solvent mixture ratio is 1:1.2 w/w)
Co-solvent Composition Raffinate Yield Solvent system (wt %) (wt %)
RI @ 50.degree. C. NMP + 1.5% Water 0 64.7 1.49680 NMP + co-solvent
40 68 1.49606 (without water) 50 70.7 1.49626
[0074] Analysis of the data in Table 6 shows that for extraction
conducted at feed to solvent mixture weight ratio of 1:1.2, the NMP
and 50% co-solvent mixture was more effective than NMP and water
alone, resulting in more than 6 wt % improvement in raffinate yield
at same raffinate RI.
Example 7
[0075] LLE extraction was performed in batch extraction in a lab
scale jacketed glass column extraction apparatus using NMP and
water as solvent mixture. The feed, Arab Mix Heavy Neutral (HN)
distillate was preheated. 150 gm of feed and 225 gm of solvent
mixture were fed into the extraction setup. The temperature of the
column was kept at 80.degree. C. The experimental procedure was
same as in Example 3. Final raffinate samples were analyzed for
refractive index.
Example 8
[0076] The same experiment as in example 7 was performed with NMP,
water and at least one co-solvent as the solvent mixture.
[0077] The results from the LLE Extraction of Heavy neutral
Distillate of example 7 and example 8 is shown below in Table
7.
TABLE-US-00007 TABLE 7 (Feed to Solvent mixture ratio is 1:1.5 w/w)
Co-solvent Composition Raffinate Solvent system (wt %) yield(wt %)
RI @ 50.degree. C. NMP + 1% Water 0 65 1.50232 NMP + Co-solvent 40
65 1.50144 (without water) 50 67 1.50228
[0078] Analysis of the data in Table 7 shows that for extraction
conducted at feed to solvent mixture weight ratio of 1:1.5, the NMP
and 50 wt % co-solvent mixture was more effective than NMP and
water alone, resulting in 2 wt % improvement in raffinate yield at
same raffinate RI.
Example 9
[0079] Continuous counter current extraction was performed in 4
meter height extraction column using NMP and water as solvent
mixture. The feed, Arab Mix distillate was pre-heated and pumped
for example at 3 kg/hr from bottom of the extractor (feed inlet)
and the solvent mixture, NMP, water with or without co-solvent were
heated and pumped for example, at 3.6 kg/hr at the top of the
extractor (solvent inlet). The solvent mixture rate was varied
accordingly to the desired feed to solvent mixture weight ratio of
1:1.8 (The ratio is typically referred to as 180 weight % solvent
mixture dosage). The extraction studies were performed with column
top temperature for example, 70.degree. C. and column bottom
temperature for example, 60.degree. C. After the mixture of
solvents and oil pumping started, the raffinate phase from the top
of the column (raffinate product phase outlet) and extract phase
from the bottom of the column (extract phase outlet) were drawn
continuously.
[0080] The interface position between the lighter raffinate phase
and heavier extract phase was maintained constant. After steady
state, i.e. after about 12 to 16 hrs, indicated by constant
interface level and constant raffinate and extract phase flows, the
raffinate phase and the extract phase were collected simultaneously
for a given period of time, i.e. about 30 to 40 minutes. The two
phases collected were weighed to ensure material balance. The
solvent was stripped from the extract and raffinate with nitrogen
under vacuum. The stripped raffinate and extract phases were
weighed and the raffinate yield was obtained. Final raffinate
samples were analyzed for density and refractive index (RI).
Example 10
[0081] The same experiment as in example 9 was performed with NMP,
water and at least one co-solvent as the solvent mixture.
[0082] The results from the continuous counter current extraction
of example 9 and example 10 are shown in Table 8.
TABLE-US-00008 TABLE 8 NMP + Water + Properties NMP + Water
Co-solvent Column Top 70 70 70 70 Temperature (.degree. C.) Column
Bottom 60 60 60 60 Temperature (.degree. C.) Solvent to Feed Ratio
1.2 1.8 1.2 1.8 (w/w) Raffinate Yield (wt %) 65.5 63.5 71.1 69.8
Raffinate RI@50.degree. C. 1.4844 1.4825 1.4840 1.4825
[0083] Analysis of the data in Table 8 shows that for extraction
conducted at feed to solvent mixture weight ratio 1:1.8, the NMP,
water and at least one co-solvent mixture are more effective than
NMP water alone, resulting in more than 6 wt % improvement in
raffinate yield at same raffinate RI.
[0084] Although the subject matter has been described in
considerable detail with reference to certain preferred embodiments
thereof, other embodiments are possible. As such, the spirit and
scope of the appended claims should not be limited to the
description of the preferred embodiment contained therein.
* * * * *