U.S. patent application number 14/601146 was filed with the patent office on 2015-05-14 for method for producing base lubricating oil from waste oil.
The applicant listed for this patent is VEROLUBE, INC.. Invention is credited to Martin R. MacDonald.
Application Number | 20150129412 14/601146 |
Document ID | / |
Family ID | 36953831 |
Filed Date | 2015-05-14 |
United States Patent
Application |
20150129412 |
Kind Code |
A1 |
MacDonald; Martin R. |
May 14, 2015 |
METHOD FOR PRODUCING BASE LUBRICATING OIL FROM WASTE OIL
Abstract
A method for recovering base oil from waste lubricating oil by
separating base oil range constituents from a waste lubricating oil
mixture, thereafter separating higher quality base oil constituents
and lower quality base oil constituents from the base oil recovered
from the waste lubricating oil mixture and thereafter treating the
lower quality base oil constituents to produce marketable base oil.
The total base oil produced from a waste lubricating oil mixture by
this process is greater than the quantity producible by previous
processes using only base oil separation from the waste lubricating
oil mixture or processes which use only treatment of the base oil
recovered from the waste lubricating oil mixture to produce the
product base oil.
Inventors: |
MacDonald; Martin R.;
(Plano, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VEROLUBE, INC. |
Calgary |
|
CA |
|
|
Family ID: |
36953831 |
Appl. No.: |
14/601146 |
Filed: |
January 20, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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13108979 |
May 16, 2011 |
8936718 |
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14601146 |
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12421002 |
Apr 9, 2009 |
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13108979 |
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11076436 |
Mar 8, 2005 |
8366912 |
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12421002 |
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Current U.S.
Class: |
203/6 ;
203/23 |
Current CPC
Class: |
C10G 53/04 20130101;
C10G 67/04 20130101; B01D 3/065 20130101; C10G 2300/44 20130101;
C10G 2300/4081 20130101; C10G 71/00 20130101; C10G 21/24 20130101;
C10G 21/16 20130101; C10G 7/12 20130101; C10G 2300/301 20130101;
C10M 175/005 20130101; C10G 7/006 20130101; C10G 2300/1007
20130101; B01D 3/10 20130101; B01D 3/40 20130101; C10G 2300/1003
20130101; C10G 21/20 20130101; C10G 2400/10 20130101; C10G 21/006
20130101; C10G 2300/308 20130101; C10G 67/14 20130101; C10G 21/06
20130101; C10G 21/18 20130101; C10G 21/02 20130101; C10G 7/003
20130101; C10G 45/04 20130101 |
Class at
Publication: |
203/6 ;
203/23 |
International
Class: |
C10M 175/00 20060101
C10M175/00; B01D 3/40 20060101 B01D003/40; B01D 3/06 20060101
B01D003/06; B01D 3/10 20060101 B01D003/10 |
Claims
1. A method for separating a liquid stream comprising a plurality
of constituents of varied boiling points by in-situ flash
distillation in at least one distillation zone comprising at least
one flash distillation vessel to produce at least one overhead
stream and at least one bottom stream, the method comprising: a)
passing the liquid stream into a heated liquid layer contained in a
flash distillation vessel and producing an overhead stream and a
bottom stream and having up to one theoretical plate; b) heating
the bottom stream to a selected temperature and passing a portion
of the heated bottom stream to the flash distillation vessel to
maintain the heated liquid layer at a selected temperature and at a
selected level in the flash distillation vessel in a lower portion
of the vessel; c) heating the heated liquid layer in the flash
distillation vessel at a temperature sufficient to flash a portion
of the liquid feed stream to the flash distillation vessel thereby
producing the bottom stream and the overhead stream; d) passing at
least a portion of the distillate overhead stream out of the
distillation vessel.
2. The method of claim 1 wherein a plurality of flash distillation
vessels are used.
3. The method of claim 1 wherein at least one of the flash
distillation zones is operated under vacuum.
4. The method of claim 1 wherein two flash distillation vessels are
used.
5. The method of claim 1 wherein three flash distillation vessels
are used.
6. The method of claim 1 wherein four flash distillation vessels
are used.
7. The method of claim 1 wherein five or mere distillation vessels
are used.
8. The method of claim 1 wherein the liquid stream is a liquid
prone to fouling.
9. The method of claim 1 wherein the liquid stream is a hydrocarbon
stream.
10. The method of claim 1 wherein the liquid stream is waste
oil.
11. The method of claim 5 wherein an overhead stream having a
boiling range from about 500 to about 600.degree. F. and an
overhead stream having a boiling point from about 600 to about
1100.degree. F. are produced.
12. The method of claim 1 wherein the bottom stream is heated and a
portion returned to the distillation zone, at a temperature
sufficient to heat the liquid layer in the distillation zone to a
temperature sufficient to flash a Portion of the liquid stream to
produce an overhead stream from the distillation zone.
13. The method according to claim 1 whereby the liquid stream is
treated with an alkali or base to condition the liquid stream prior
to distillation.
14. The method according to claim 13 whereby the alkali or base is
one of sodium carbonate, sodium hydroxide, and potassium
hydroxide.
15. The method according to claim 1 whereby the liquid stream is
treated to remove water, light hydrocarbons and low boiling point
materials prior to flash distillation.
16. The method according to claim 11 wherein the liquid stream is
treated using distillation to remove water and low boiling point
constituents prior to in-situ flash distillation.
17. The method according to claim 1 whereby the liquid stream is
both treated with an alkali or a base and treated to remove water
and light hydrocarbons prior to distillation.
18. A method for separating a liquid stream comprising a plurality
of constituents of varied boiling points by in-situ flash
distillation: the method comprising: a) charging the liquid stream
into a heated liquid layer in a flash vessel having at least a top
and a bottom, a liquid stream inlet, a distil late outlet near the
top of the vessel, a lower portion and a bottom stream outlet near
the bottom of the vessel and up to one theoretical plate, the
vessel containing a heated liquid layer in its lower portion, to
produce an overhead stream through the overhead outlet and a bottom
stream from the bottom stream outlet; and b) heating the bottom
stream from the flash vessel to produce a heated bottom stream and
passing a portion of the heated bottom stream back to the liquid
layer in the flash distillation zone,
19. The method of claim 18 wherein a plurality of flash
distillation vessels are used to produce a plurality of distillate
streams and a plurality of product bottom streams.
20. The method of claim 18 wherein at least one of the flash
distillation vessels is operated under vacuum.
21. The method of claim 19 wherein two flash distillation vessels
are used.
22. The method of claim 19 wherein three flash distillation vessels
are used.
23. The method of claim 19 wherein four flash distillation vessels
are used.
24. The method of claim 19 wherein five or more distillation
vessels are used.
25. The method of claim 18 wherein the liquid stream is a
hydrocarbon stream.
26. The method of claim 18 wherein the liquid stream is a waste
oil.
27. The method of claim 21 wherein a distillate stream having a
boiling range from about 500 to about 650.degree. F. and a
distillate stream having a boiling point from about 650 to about
1100.degree. F. are produced.
28. The method of claim 18 wherein the bottom stream is heated and
a portion returned to the flash zone, at a temperature sufficient
to heal the liquid layer in the first flash distillation to a
temperature sufficient to flash a portion of the liquid stream to
produce a distillate stream from the first distillation zone.
29. The method of claim 21 wherein the bottom stream from the
second flash distillation zone is heated and a portion returned to
the flash zone, at a temperature sufficient to heat the liquid
layer in the second flash distillation zone to a temperature
sufficient to flash a portion of the bottom stream from the first
flash distillation zone to produce a distillate stream from the
second distillation zone.
30. The method according to claim 18 whereby the liquid stream is
treated with an alkali or base to condition the oil prior to
distillation.
31. The method according to claim 30 whereby the alkali or base is
one of sodium carbonate, sodium hydroxide, potassium hydroxide.
32. The method according to claim 18 whereby the liquid stream is
treated to remove water and light hydrocarbons prior to
distillation.
33. The method according to claim 18 whereby the liquid stream is
both treated with an alkali or a base and treated to remove water
and light hydrocarbons prior to distillation.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is continuation of prior application Ser.
No. 12/421,002, filed Apr. 9, 2009, which is a divisional
application of prior application Ser. No. 11/076,436, filed Mar. 8,
2005, both of which applications are hereby incorporated herein by
reference, in their entirety.
FIELD OF THE INVENTION
[0002] The present invention relates to producing marketable base
oil from waste oil by a process comprising separating base oil
range constituents from the other components of the waste oil,
thereafter separating the high quality base oil constituents from
lower quality base oil constituents to produce a first high quality
marketable grade base oil and a second lower quality base oil
stream, then treating the lower quality base oil stream to produce
a second marketable grade base oil product. The total base oil
yield of the first and second products and fraction of high quality
base oil produced from the waste oil by this process is greater
than the quantity producible by previous processes.
BACKGROUND OF THE INVENTION
[0003] This invention relates to a high efficiency method for
refining waste oils to produce base oil and other valuable
products, which includes the steps of separating at least a portion
of the base oil constituents (base oil fraction), typically mineral
oil suitable for lubrication service with a boiling point usually
between 500 and 1100.degree. F., from the various physical
contaminants and other hydrocarbon fractions of the waste oil,
separating from the base oil fraction a portion of the lower
quality molecules such as those containing hetero atoms,
unsaturates, polars and aromatics, thereby creating a first high
quality marketable base oil stream and a stream wherein the lower
quality molecules have been concentrated and thereafter further
treating the lower quality base oil stream to at least partially
convert the constituents containing hetero atoms, unsaturates,
polars and aromatics to higher quality molecules by removing
sulfur, oxygen, nitrogen, chlorine constituents and the like and
more fully saturating the molecules thereby producing a second
marketable quality base oil stream.
[0004] Annually large volumes of finished lubricating oils are
produced worldwide. Finished lubricating oils are produced by
combining base oil (also known as base stock, base lube stock, lube
stock, lube oil, lubrication oil and the like) typically a mineral
oil with between 18 to 40 carbon atoms and a boiling point between
500 to about 1050.degree. F. with chemical additives which enhance
the properties of the base oil making it more suitable for its
intended service. The quality, quantity and type of base oil used
depend upon the service for which the finished lubricating oil is
made.
[0005] The quality of the base oil component is typically
determined by several factors related to the oil's compositional
and physical properties. The American Society for Testing and
Materials (ASTM) has compiled ASTM D-6074-99 Standard Guide for
Characterizing Hydrocarbon Lubricant Base Oils as a guide for
testing the quality of base oil. Similarly, the American Petroleum
Institute (API) has prepared Specification API 1509, Engine Oil
Licensing and Certification Systems Specification in order to help
quantify and categorize base oil quality. The compositional
properties relate to actual chemical composition of the base oil,
such as the presence of certain contaminants other than hydrogen
and carbon in the base oil molecules and the configuration, form or
structure of the base oil molecules. The physical properties relate
to the performance of the base oils when tested in predefined ways
and include such properties as viscosity, flash point, volatility
and the like.
[0006] API 1509 currently has designated six classifications
("Groups") of base oil. Groups I, II and III typically classify
base oils in accordance with their physical and compositional
properties. Groups IV, V and VI typically classify base oil by
type; include synthetic oils and the like. Mineral oils derived
from waste oil will typically be classified in Groups I, II or III.
These Groups are principally distinguished by the concentration of
sulfur, percent saturates and viscosity index.
[0007] Typically, base oils and finished lubricating oils, by usage
and/or handling, become contaminated with oxidation and degradation
products, water, fuels, solvents, antifreeze, other oils, fine
particulates, additive products and the like. Service can also
result in changes in the molecular structure of the oil and/or the
chemical additives thereby changing the original nature of the oil.
These contaminants or changes may reduce the desired performance of
the oils or render the oils unsuitable for use in their intended
services and necessitate disposal or replacement with new,
uncontaminated oil. Once deemed unfit for use or service, these
contaminated oils are typically called waste oil or used oil. Waste
oil can be either petroleum or synthetically based oil, that may or
may not have been in service and include oils that typically are
used as lubricants for engines, turbines and gears, hydraulic
fluids, metal working fluids, insulating or cooling fluids, process
fluids or the like.
[0008] Waste oil is typically collected by a large number of
regional waste oil gatherers who collect it from the local sites of
utilization or production. In the collection process, a great
variety of oils, which were formulated for numerous types of
service, are mixed together thereby forming a composite of
different types and qualities of base oil, chemicals, contaminants
and the like.
[0009] With the ever-increasing desire to conserve and manage our
petroleum resources in a responsible way, there is renewed focus on
the need to recover and re-refine waste oils to recover the base
oil contained therein. Currently, the vast majority of the
collected waste oil is combined with industrial fuel oils and
burned as a combustion fuel. This practice not only contributes
significant pollutants to the environment, but also wastes energy
and contributes to our dependence on foreign oil. Those most
familiar with the problem, including the U.S. Environmental
Protection Agency and the American Petroleum Institute, have
recognized that re-refining to produce base oil is the highest and
best use of the waste oil and the industry has long sought an
efficient, economic and environmentally friendly process which is
capable of recovering a high percentage of the base oil from the
waste oil (high efficiency) and producing a high percentage of high
quality products therefrom (high quality).
[0010] Several treatment processes have been proposed for creating
cleaner burning fuel oils or diesel oils from the waste oil which
employ various forms of processing including; thermal cracking U.S.
Pat. Nos. 5,362,381, 5,382,328, 5,885,444; distillation U.S. Pat.
Nos. 4,101,414, 4,342,645, 5,306,419, 5,814,207, 5,980,698,
RE38,366; pyrolysis U.S. Pat. No. 6,132,596; coking U.S. Pat. Nos.
5,143,597, RE36,922 and the like. However, creating fuel oils is
not the highest and best use for the waste oil since the energy and
intense processing that was undertaken to originally produce the
base oil from crude oil or through synthesis processes is lost when
the oil is consumed by combustion. Furthermore, the resource itself
is lost. Hence, waste oil burning does not fully meet the ultimate
objectives of conservation and recovery.
[0011] The ideal re-refining process would produce a high
percentage of base oil, produce high quality products--both base
oil and byproducts, be environmentally friendly and economically
viable and commercially sound. While several processes have been
proposed for re-refining waste oil into base oil, none are
currently capable of meeting all the desired objectives as
effectively as the method described hereinafter.
[0012] For example, waste oil has long been re-refined to base oil
using sulfuric acid to separate contaminants from useful
hydrocarbon components followed by treatment with clay, however,
few facilities of this type remain due to poor base oil product
quality and the generation of large amounts of highly toxic,
environmentally hazardous, acid and clay sludge. This type of
process has been banned from use in many westernized countries
because of these shortcomings.
[0013] Waste oils have also been re-refined to base oil utilizing a
process known as hydrotreating or hydrofinishing. Several patents
describe various derivatives of the process including U.S. Pat.
Nos. 4,431,524; 4,432,856; 4,512,878; 4,941,967; 5,045,179 and
5,447,625. This treatment method typically employs some form of
distillation to separate a base oil fraction from other
contaminants, followed by treatment with hydrogen at elevated
temperatures and pressures over a catalyst. While this method has
been successful in saturating some aromatics and non-saturated
compounds, severe hydrotreating (higher temperatures, pressures,
hydrogen concentrations, residence time, etc) is required to
sufficiently saturate oil molecules and achieve the physical and
compositional properties of higher quality base oils.
Unfortunately, these severe processing conditions can result in
molecular cracking, which consequently results in base oil yield
loss thereby lowering the amount of base oil produced. Therefore,
this process is not capable of producing both high quality products
(high quality) and high quantity yields (high efficiency). Further,
hydrotreating all the base oil fraction is expensive typically
resulting in marginal economics.
[0014] Another method of re-refining waste oil to base oil utilizes
solvent extraction. This process also suffers from a yield/quality
trade-off. U.S. Pat. Nos. 4,021,333; 4,071,438; 4,360,420;
6,117,309; 6,319,394; 6,320,090 and 6,712,954 describe various
processes involving some form of distillation followed by solvent
extraction. U.S. Pat. Nos. 4,302,325 and 4,399,025 describe
extraction processes on base oil fractions, however derived. In
these processes, a portion of the contaminated base oil molecules
(polars, aromatics, heteroatoms, unsaturates) are separated from
the base oil fraction using liquid/liquid extraction. This creates
a purified base oil stream (raffinate) and an extract oil stream
(extract) wherein some of the contaminated molecules are
concentrated. The efficacy of separation of quality base oil from
contaminated molecules is determined by several variables including
temperature, treatment ratio, residence time, contact, and the
presence of other fluids added to the oil and solvent. In the
extraction process there is continual trade-off between selectivity
(the amount of good base oil taken with the extract) and purity
(percent of contaminated base oil molecules left in the
raffinate).
[0015] Typically solvent extraction processes are effective at
removing some of the aromatics, polars and unsaturated compounds.
However, to reach the desired level of purification necessary for
higher quality standards using known processes, the selectivity of
the solvent must be reduced whereby both contaminated molecules as
well as good molecules are taken by the solvent, which
significantly reduces the yield of base oil. Therefore, there is an
inherent trade-off between quality and yield so that in order to
get high quality base oil, yield quantity may be reduced (see U.S.
Pat. No. 6,712,954).
[0016] As previously noted, known processes of this type are
capable of producing either high quality or high yield, but not
both. This is due to the nature of the waste oil, which consists of
a wide variety of types, qualities and contaminants and the
consequential trade-off between quality and quantity that is
typically inherent in these processes. Furthermore, most known
process of this type typically can only produce a Group I base oil.
An additional disadvantage of this process is that the extract
formed by solvent extraction of waste oil is also prone to
reformation assumed to be polymerization. This polymerization is
believed to be catalyzed by acid and can be reduced through
addition of base or blending with fuel oil or other anti-polymer
chemicals thereby adding to the overall production cost.
Furthermore, the resulting product is a low quality base oil, which
may be difficult to market.
SUMMARY OF THE INVENTION
[0017] According to the present invention, a method for efficiently
producing a high yield of high quality base oil from a waste oil
comprises: separating at least a portion of the base oil
constituents from the waste oil to produce a base oil fraction;
treating the base oil fraction to separate the base oil fraction
into a high quality base oil stream and a lower quality base oil
stream; and, treating the lower quality base oil stream to improve
or remove undesirable constituents of the lower quality base oil
stream thereby upgrading the lower quality base oil stream to a
marketable quality base oil stream.
[0018] The invention further comprises a method for producing a
highly purified base oil stream wherein the high quality base oil
stream produced above is tfurther treated to upgrade or remove
undesirable constituents and increase the degree of saturation
thereby producing a highly purified base oil that has a wider
potential market for use and value. The highly purified base oil
can be made to white oil quality thereby becoming suitable for use
in the pharmaceutical and food processing industries as well as
being suitable as a high quality base stock for use in high quality
or specialty lubricants.
[0019] The invention still further comprises a method for
efficiently producing a highly purified base oil from a waste oil,
the method comprising: separating at least a portion of the base
oil constituents from the waste oil to produce a base oil fraction;
treating the base oil fraction to separate it into a high quality
base oil stream and a lower quality base oil stream; and treating
the high quality base oil stream to upgrade or remove undesirable
constituents to create a highly purified base oil. The highly
purified base oil stream is typically API Group II or Group III
quality.
[0020] The invention further comprises a method for efficiently
producing ultra high quality base oil from a waste oil, the method
comprising; separating at least a portion of the base oil
constituents from the waste oil to produce a base oil fraction;
treating the base oil fraction using the severe solvent extraction
described herein, to separate it into an ultra high quality base
oil stream and a lower quality base oil stream. By this method it
is possible to produce an API group III base oil which is suitable
for use in high quality and specialty lubricants.
[0021] The invention further comprises a method for separating a
liquid stream comprising a plurality of constituents of varied
boiling points by in-situ flash distillation in at least one
distillation zone to produce at least one overhead stream and at
least one bottom stream, the method comprising: passing the liquid
stream into a heated liquid layer contained in a distillation zone
and producing an overhead stream and a bottom stream; continuously
heating the liquid layer in the distillation zone to a temperature
sufficient to vaporize a portion of the liquid feed stream thereby
producing a bottom stream and a vaporized distillate stream;
passing a portion of the overhead stream out of the distillation
zone; passing a portion of the heated bottom stream to use as a
charge liquid stream to another distillation zone or to use as a
product stream.
[0022] The invention further comprises a system for separating a
liquid stream comprising a plurality of constituents of varied
boiling points by in-situ flash distillation; the method
comprising: charging the liquid stream into a heated liquid layer
in a flash vessel having at least a top and a bottom, a liquid
stream inlet, a distillate outlet near the top of the vessel, a
lower portion and a bottom stream outlet near the bottom of the
vessel, the vessel containing a heated liquid layer in its lower
portion, to produce an overhead stream through the overhead outlet
and a bottom stream from the bottom stream outlet; continuously
heating the bottom stream from the flash vessel to produce a heated
bottom stream and passing a portion of the heated bottom stream
back to the liquid layer in the flash distillation zone.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1. is a generalized schematic of the process of the
present invention;
[0024] FIG. 2. is a schematic diagram of a preferred distillation
process, combined with a solvent extraction process and a
hydrogenation process in an embodiment of the invention;
[0025] FIG. 3. is a generalized schematic of a second embodiment of
the process of the present invention;
[0026] FIG. 4. is a generalized schematic of a third embodiment of
the process of the present invention; and
[0027] FIG. 5. is a generalized schematic of a fourth embodiment of
the process of the present invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0028] In FIG. 1, a generalized embodiment of the present invention
is shown. In the embodiment shown, a waste oil stream 12 is charged
to a base oil separation zone 14 where a portion of the base oil
constituents (base oil fraction), line 20, is separated from the
other physical contaminants, line 16, in the waste oil. In actual
practice, the various physical contaminants are typically removed
from the base oil fraction in such a way as to produce more than
one stream but for simplicity are shown herein to be separated
collectively and recovered through line 16 and may include low
molecular weight materials such as light hydrocarbons, water,
glycols and the like typically having a boiling range generally
below about 500.degree. F., although it may be desirable to include
all materials below 650.degree. F., and high molecular weight
materials and materials with low volatility including,
particulates, polymers, salts and the like typically having a
boiling point greater than about 1050.degree. F. The base oil
fraction recovered through a line 20 typically consists of
hydrocarbon molecules suitable for use or manufacture into base oil
typically with 18 to 40 carbon atoms and having a boiling range
between about 500 to about 110.degree. F. In a high quality base
oil separation zone 22, a portion of the higher quality base oil
molecules (high quality base oil) is separated from the lower
quality base oil molecules (lower quality base oil) and recovered
through a line 24 for sale as product base oil. This high quality
base oil typically meets at least one of Groups I, II or III as set
forth by API 1509, The lower quality base oil is recovered through
a line 26 and passed to a lower quality base oil treatment zone 28
where it is more fully saturated and treated for the removal of
various elemental contaminants which are recovered through a line
32, to produce a marketable quality base oil which meets the
requirements of at least one of API 1509, Group I, II or III which
is recovered through a line 30. Various materials contaminants,
derivatives and products thereof and the like are recovered via a
line 32. This is a relatively generalized showing of the process of
the present invention. However, it shows an important feature of
the present invention.
[0029] In the first stage, zone 14, the base oil fraction is
separated from physical contaminants in the waste oil. Typically,
such contaminants include water, light hydrocarbons, solvents,
solids, polymers, high molecular weight hydrocarbons, lubricating
oil additives, chemicals, salts and the like. Several processes or
combination of processes can be used to effect this separation
including various forms of extraction, distillation, filtration,
centrifugation, absorption and adsorption and the like as known to
those skilled in the art. Typically, the separation will take place
based upon differences in the physical or chemical properties of
the base oil fraction and the various contaminating materials.
[0030] In the second stage, the oil base fraction is then fed to
zone 22 of the process where a portion of the lower quality base
oil molecules are separated. These molecules may comprise polars,
aromatics, olefins, unsaturates, heteroatoms and the like, which
are separated from the higher quality base oil molecules, which are
typically saturated, paraffinic and non-aromatic. The higher
quality base oil molecules in line 24 are a high quality base oil
stream typically having a percent of saturates greater than 90% and
a sulfur content less than about 0.3 weight percent. The stream in
line 26 will typically have a higher concentration of sulfur,
oxygen, nitrogen, olefins, aromatics and the like. Various
processes or combinations thereof can be used to effect separation
of these materials from the high quality base oil. These processes
include various forms of extraction, filtration, ultrafiltration,
absorption, adsorption, molecular sieves and the like, as known to
those skilled in the art.
[0031] In the third stage, this stream is processed in zone 28 by
hydrogenating, alkylating, molecular reforming, molecular
substituting or the like or a combination thereof, as known to
those skilled in the art to remove undesirable elements such as
sulfur, nitrogen, oxygen and the like and increase the percent
saturation of at least a portion of the hydrocarbon molecules in
the lower quality base oil stream. The resulting base oil produced
through line 30 is typically of a quality sufficient to meet the
requirements for Groups I, II, or III of API 1509.
[0032] FIG. 2 shows an embodiment of the invention, In stage 1 a
flash distillation system zone 40 is shown for separating the base
oil fraction from the other components of the waste oil stream. A
waste oil stream is charged through a line 42 through a heater 44
and a line 46 to a first flash distillation vessel 52. Flash
distillation vessel 52 includes a top 53 and a bottom 57 and
includes a distillate outlet line 54 and a bottom outlet line 56. A
distillate stream having a boiling point range up to about
350.degree. F. is recovered via line 54 and passed to use as a fuel
or the like. A bottom stream is withdrawn via bottom outlet line 56
and passed to a second in-situ flash distillation vessel 70.
[0033] In-situ flash distillation vessel 70 includes a top 72 and a
bottom 74 with a distillate outlet line 76 positioned to recover a
distillate stream from the top 72 and a bottom outlet line 78 for
recovering a portion of a liquid layer maintained in the lower
portion of vessel 70 at a liquid level shown at 88. The stream
recovered from line 76 has a boiling range generally from about 350
to about 500.degree. F. and is typically used for fuel and the
like. The bottom stream recovered through line 78 is passed to a
pump 80 and then through a feed inlet line 82 and a heater 84 and
returned through line 83 to vessel 70. A portion of the heated
bottom stream in line 82 is withdrawn through a line 86 and fed to
a third in-situ flash distillation vessel 90.
[0034] In-situ flash distillation vessel 90 includes a top 92 and a
bottom 94 and a distillate recovery outlet 96 through which
distillate is recovered through the top portion of vessel 90. A
bottom stream 98 is recovered from the bottom of vessel 90 and
passed via a line 98 through a pump 100 and to a line 102 and
passed via a heater 104 to line 108 as a return stream to vessel
90. A portion of stream 102 is passed through a line 106 as a feed
to a fourth flash distillation vessel 112. A liquid layer having a
liquid level 110 is maintained in the lower portion of vessel 90.
Vessel 90 produces a distillate stream having a boiling range from
about 500 to about 650.degree. F.
[0035] The return streams for vessels 70 and 90 are used to
maintain the temperature in the liquid layer in the bottom of the
vessels. The oil fed into vessels 70 and 90 is heated to the
temperature necessary to effect the desired separation of the
distillate by direct contact with the liquid layer in the bottom of
the vessels.
[0036] Vessel 112 includes a top 114, a bottom 116 and receives
feed from vessel 90 via a line 106. This vessel produces a
distillate stream through a distillate outlet 118 having a
temperature from about 650 to about 1050.degree. F. A liquid level
is also maintained in this vessel at a level shown at 130. The
bottom stream is withdrawn through a line 120, passed via pump 122
to a discharge line 124 through which a portion of this stream is
recovered as a product. A portion of this stream is also returned
via a line 126 and a heater 128 to join the feed stream in inlet
line 106. This heated bottom steam 126 is used to maintain the
desired feed temperature to vessel 112.
[0037] The product stream recovered through line 124 typically
comprises asphalt range materials and includes polymers, high
boiling point hydrocarbons, salts, solids, other high boiling range
materials, typically having a boiling point greater than
1050.degree. F., and the like which are included in the waste oil
stream 42 in FIG. 1.
[0038] Vessel 112 may well be a vacuum distillation vessel if
required to prevent degradation of the base oil stream in this
vessel. Steam or gas stripping may also be used in this vessel to
enhance distillation.
[0039] The distillate stream recovered from vessel 112 through line
118 is passed to stage 2, zone 50, a solvent extraction section.
The stream in line 118 is passed through a heat exchanger 132 and
to a solvent treating vessel 140. This solvent treating vessel is
shown with a top 144 and a bottom 142. A contact section 146 is
shown schematically in the center portion of the vessel. A solvent
processing and storage system is shown at 148 and supplies solvent
to an upper portion of vessel 140 near its top via a line 150. The
solvent typically moves downwardly, counter-currently to the oil,
which is introduced near the bottom of contact section 146. The
high quality base oil molecules are recovered with a portion of the
solvent from the top of vessel 140 and passed via a line 157 to a
vessel 152 having a top 158 and a bottom 160 where the solvent is
separated from the base oil and the base oil is passed via a line
156 to product, This stream is high quality oil, which typically
will meet the requirements for Group I, II or III as specified by
API 1509.
[0040] The solvent is recovered through a line 164 and returned to
the solvent processing and storage system where it is typically
treated to remove water, low boiling point contaminants, neutralize
acidity and the like as known to those skilled in the art and
returned to solvent storage ready for repeated use. A bottom stream
155 is recovered from base oil separation vessel 140 and passed to
a solvent separation vessel 154 having a top 168 and a bottom 170.
Solvent is separated from the lower quality base oil in this
vessel, typically by distillation and passed via a line 166 back to
the solvent processing and storage system 148. The lower quality
base oil recovered from the bottom of vessel 154 is passed via a
line 172 to the third stage, zone 60, a hydrogenation section.
[0041] In the hydrogenation section, hydrogen is added to stream
172 via line 176 as shown. The stream is then passed through a
heater 174 and into a vessel 178, which acts as a guard bed to
remove contaminants in the oil that might otherwise poison the
hydrotreating catalyst. This vessel has a top 180 and bottom 182
and includes a contact zone 184 containing a catalyst, spent
catalyst, activated clay or the like as know to those skilled in
the art. It will be understood that hydrogen could be injected into
line 172 at a plurality of points or into vessel 178 at a plurality
of points. The product from vessel 178 is recovered through a line
186 and passed to a hydrogenation reactor vessel 190.
[0042] Vessel 190 has a top 192, a bottom 194 and includes a
catalytic bed 196. Hydrogen may be added at various points along
line 186 as shown by a line 188 or at various points along the
length of vessel 190. To some extent, the olefins and molecules
containing contaminants such as sulfur, nitrogen, oxygen,
hetroatoms and the like are hydrogenated forming more saturated
hydrocarbon molecules and volatile compounds of hydrogen. The
product stream is recovered through a line 200 to a vessel 202
where volatile materials containing most of the contaminants are
flashed via a line 204 and passed to use as fuel, discharged after
suitable treatment to the atmosphere or the like. The lower quality
oil, which has now been upgraded, is recovered through a line 206.
This oil is typically suitable for sale as base oil under Group I,
II or III of API 1509.
[0043] In the practice of the present invention, it may be
desirable in some instances to chemically treat the waste oil with
a base or alkali material such as sodium carbonate, sodium
bicarbonate, sodium hydroxide, potassium hydroxide, or the like as
known to those skilled in the art in heater 44. This step
conditions, stabilizes and otherwise neutralizes the waste oil
stream to reduce the tendency to foul, to facilitate separation of
the waste oil stream into its constituent parts and to enhance the
quality of the non-base oil products. In certain instances it may
also be desirable to add an alkali or base to one or more of the
distillation vessels either in the feed stream, recycle stream or
directly into the vessel.
[0044] In the embodiment described above, four vessels are used to
separate the base oil fraction from the other waste oil
constituent. In the practice of this invention it may be desirable
to use as few as two vessels or as many as eight vessels to effect
this separation.
[0045] In the embodiment described above, flash vessels are used to
separate various constituents from the base oil fraction. These
vessels include any vessel or system that affects a single stage of
separation including simple evaporators, thin or wiped film
evaporators, columns, vessels, tanks, pipes and the like as known
to those skilled in the art.
[0046] In the embodiment described above steam or a gas may added
to vessels 52, 70, 90 and 112 to help strip the light distillates
from the waste oil thereby enhancing separation. Steam stripping is
well known to those in the art as a means of enhancing distillation
processes.
[0047] In vessel 52, no heated recycle bottom stream is used
because it is possible to heat the inlet feed stream in heater 44
to a desired temperature without unusual concern for fouling. This
vessel could be operated in the same fashion as vessel 70 by
heating and returning a portion of the bottom stream in line 56 to
vessel 52 and maintaining a bottom layer in vessel 52.
[0048] In the practice of the present invention, it may be
desirable in some instances to bring the stream recovered through
line 96, which has a boiling range typically from about 500 to
about 650.degree. F. into combination with the stream in line 172
for hydro-treatment since this stream is suitable for use as base
oil. This stream is not used in all instances for a supplement to
the stream in line 172 but may be used if desired. The boiling
point range of the material recovered through line 96 can be
modified if desired to produce material having a slightly higher
initial boiling point or the like. This stream is also useful as
base oil but in prior processes has not been recovered in many
instances.
[0049] The embodiment for stage 2 described above applies to
solvents that have a specific gravity greater than the base oil. In
cases where the solvent has a specific gravity less than base oil
the solvent would be introduced into the solvent treating vessel in
the bottom and the base oil would be introduced into the top of the
vessel. Vessels 152 and 154 would still be configured to remove
solvent from the raffinate and extract respectively.
[0050] While FIG. 2 shows one guard bed, vessel 178, and one
hydrogenation reactor, vessel 190, two or more guard beds,
configured in series or in parallel, could be used prior to vessel
190. The guard beds in parallel would be operated one at a time to
enable regeneration or clean out and recharging of either of the
vessels without interrupting flow to vessel 190. Similarly, more
than one hydrogenation reactor could be operated in series or
parallel to enhance operation.
[0051] In the embodiment described above it may also be desirable
to incorporate a hydrogen recovery system to recover hydrogen from
process stream 204. The hydrogen recovery system would purify and
recover the hydrogen in this stream and recycle it back for use in
stream 176 and/or 188.
[0052] It may also be desirable to employ steam or gas stripping in
vessel 202 to help strip non-base oil light contaminates from the
base oil. An additional vessel could also be added to further
process the base oil in line 206 by further fractionating it to
create different viscosity cuts or stripping it to reduce
volatility.
[0053] In the embodiment described above in stage two is used to
separate a portion of the higher quality base oil molecules from
the lower quality base oil molecules thereby creating a first high
quality base oil stream 156 wherein the concentration of aromatics,
polars, unsaturates, heteroatoms and the like is lower and a second
lower quality base oil stream 172 wherein the concentration of
aromatics, polars, unsaturates, heteroatoms and the like is higher.
It is also possible to further upgrade the high quality base oil
stream using processes similar to those described in stage 3, by
converting a portion of the aromatic, polar, unsaturated,
heteroatom molecules and the like remaining in the high quality
base oil stream, to higher quality molecules thereby further
purifying it, increasing the degree of saturation and thereby
producing an highly purified base oil. This oil may be suitable for
use as a white oil in the medicinal or food processing industries
as well as a lubricating base oil in the industrial lubrication
markets.
[0054] In the embodiment shown above, the solvent recovered from
the lower and high quality base oils, streams 164 and 166, is
combined and purified in the solvent processing and storage unit by
removing water and other low boiling point contaminants prior to
re-use. The solvent can also be treated at this stage with bases
and the like as known to those skilled in the art, to neutralize
organic acids that may have built up in the solvent.
[0055] In the embodiment of the present invention as discussed
above, a flash distillation system is used to separate the base oil
fraction from the other waste oil constituents. The treated waste
oil stream is heated to between 250 and 450 F and preferably to
between 300 and 400.degree. F. in heater 44 and flashed across a
valve (not shown) into flash distillation vessel 52 where a
distillate stream 54 is recovered from the waste oil. The
distillate stream typically will be burned as a process gas or
condensed, separated from any water, glycols and the like, and used
as a fuel or the like. The bottom waste oil outlet stream is passed
or pumped to in-situ flash distillation vessel 70 wherein it passes
into a pool of oil resident in the bottom of the vessel. The pool
of oil is kept at a temperature between 400 and 600.degree. F. and
preferably between 450 and 550.degree. F. by heating it through a
recirculation heater whereby the oil is pumped from the bottom of
vessel 70, heated in heater exchanger 84 and passed back into
vessel 70. Typically, the flow rate of this recirculation stream is
sufficient to provide adequate heat exchange in heater exchanger 84
to keep the liquid layer (pool of oil resident in the bottom of the
vessel) at the desired temperature, thereby creating the desired
distillate fraction 76, and maintaining turbulent flow and a high
Reynolds number through the tubes of heater 84.
[0056] The waste oil stream entering vessel 70 from vessel 52 is
heated by direct contact with this liquid layer thereby vaporizing
constituents of the waste oil with a boiling point less than the
temperature of the liquid layer and creating distillate stream 76.
Distillate stream 76 typically has a boiling range generally from
about 350 to about 500.degree. F. and is typically condensed and
used for fuel and the like. A portion of the bottom stream in line
82 is passed to a third in-situ flash distillation vessel 90.
[0057] Vessel 90 operates on a similar principal as vessel 70 using
a hot liquid layer to heat the incoming stream by direct contact.
The liquid layer of oil is kept at a temperature between 550 and
750.degree. F. of and preferably between 600 and 700.degree. F. by
heating it through a recirculation heater 100 whereby the oil is
pumped from the bottom of vessel 90, heated in the heater 100 and
passed back into vessel 90. A portion of the recirculation stream
82 is passed to flash distillation vessel 112. A liquid layer
having a liquid level 110 is maintained in the lower portion of
vessel 90. Vessel 90 produces a distillate stream 96 having a
boiling range from about 500 to about 650.degree. F.
[0058] In the embodiment described above vessels 52, 70 and 90 are
operated at atmospheric pressure. These vessels could also be
operated at pressure or under vacuum as known to those skilled in
the art, to effect similar separation of the base oil fraction from
the waste oil.
[0059] Vessel 112 is typically a flash distillation vessel, which
is operated under vacuum ranging from full vacuum to 500 mmHg and
preferable between 2 and 30 mmHg. The feed stream 106 from vessel
90 is combined with a recirculation stream 126 from the bottom of
vessel 112 which has been heated to between 550 and 700.degree. F.
and preferably between 600 and 650.degree. F. whereby the mass
ratio is between 1:2 to 1:40 feed stream flow rate to the
recirculation stream flow rate and preferably between 1:10 and
1:20. A distillate stream is produced and passes through a
distillate outlet 118 having a boiling point range from about 650
to about 1050.degree. F. A liquid level 130 is also maintained in
vessel 112. The bottom stream is withdrawn through a line 120,
passed via pump 122 to a discharge line 124 through which a portion
of this stream is recovered as a product. A portion of this stream
is also returned via a line 126 and a heater 128 to join the stream
in inlet line 106. This heated bottom stream is used to maintain
the desired feed temperature to vessel 112.
[0060] In the embodiment shown above it may be advantageous to add
a stripping gas such as steam to one or more of vessels 52, 70, 90
and 112 to strip light components from the oil and aid the
distillation and separation process. The stripping gas may be added
at various points in the bottom half of the vessel or to the oil
feed stream to these vessels.
[0061] The extraction process used in vessel 140 may be any
separation process known to those skilled in the art for the
separation of high quality base oil molecules from lower quality
base oil molecules. Such processes include solvent extraction, with
materials such as ethanol, diacetone-alcohol,
ethylene-glycol-mono(low alkyl)ether, di-ethylene-glycol,
diethylene-glycolmono(low alkyl) ether, o-chlorophenol furfural,
acetone, formic acid, 4-butyrolacetone, low-alkyl-ester of low
mono- and dicarbonic acids, dimethylformamide, 2-pyrrolidone and
N-(low alkyl)-2-pyrrolidone, N-methyl-2-pyrolodone,
epi-chlorohydrin, dioxane, morpholine, low-alkyl- and
amino(low-alkyl)morpholine, benzonitrile and
di-(low-alkyl)sulfoxide and phosphonate and the like.
[0062] N-methyl-2-pyrolodone is a preferred solvent for the process
of the present invention. In a preferred embodiment, extraction is
undertaken at a temperature at which the solvent and oil are at
least partially miscible, typically between about 100 and about
250.degree. F. and preferably between about 130 and about
190.degree. F. Typically, both the solvent and oil are fed into the
extraction column within this temperature range although not
necessarily at the same temperature. The solvent dosage (percent of
solvent relative to feed) fed to the extraction column is typically
between 50 and 1000% by volume and preferably between 100 and 500%.
Typically, extraction is undertaken in a packed or trayed column
whereby the solvent is fed into the top of the column and base oil
is fed into the bottom. The packed column can contain either
structured or random packing of a conventional type known to those
skilled in the art. Water may be injected into the solvent or
extraction column as desired to control solvent selectivity.
Similarly, temperature gradients or regional heating or cooling can
be used at various points along line 50 or across the extraction
column to affect performance and selectivity as known to those
skilled in the art. Recycles of both raffinate and extract at
similar or different temperatures can also be employed. In some
instances it may be beneficial to remove a side stream from the
extraction column, cool raffinate or extract streams, cool the side
stream, separate a portion of the solvent from the oil and return
the oil to the column. The solvent may be recovered from the
raffinate stream in line 157 and the extract stream in line 155
using distillation. The distillation can be undertaken
atmospherically or by using vacuum. One or more flash separators,
multi-stage columns and the like, or combinations thereof either
operated atmospherically, under pressure or vacuum, can be used in
order to separate the solvent from the base oil.
[0063] In a preferred embodiment of the present invention as
discussed above, hydrofinishing is used to purify and saturate the
lower quality base oil stream as a final step. The lower quality
base oil stream is mixed with 50 to 2000 scf of hydrogen per barrel
of base oil feed, preferable between 70 and 150 scf of hydrogen per
barrel of base oil feed, heated to between about 500 and about
1200.degree. F., preferably between about 650 and about 850.degree.
F. and pressurized to between about 100 and about 3000 psig and
preferably between about 500 and about 800 psig. The mixture is
passed through a guard bed consisting of activated clay or spent
catalyst and then through a hydrogenation reactor containing one or
more hydrogenation catalysts with metal components from Groups
V(b), VI(b) and VIII of the Periodic Table, as known to those
skilled in the art. Preferably compounds of nickel, molybdenum,
vanadium, tungsten or cobalt metal supported on carriers such as
activated carbon, kieseiguhr, silica, alumina and the like such as
a cobalt-molybdenum on alumina, nickel-molybdenum on alumina or
nickel-tungsten on silica/alumina. Typically, the hydrogenation is
undertaken at a space velocity of about 0.1 to about 10 and
preferably between 0.5 and 2 volumes of liquid feed per volume of
catalyst per hour. Typically, only one reactor stage is used.
However, several stages can be used if desired by using multiple
reactors in a series. After the hydrogenation treatment, the base
oil fraction is separated from the hydrogen gas and volatile
reaction products in a flash vessel, which may be operated at
reduced pressure. Typically, the pressure is between a fill vacuum
and about 100 psig, although wide variations in the suitable
pressure are possible.
[0064] With both oil streams 156 and 206, if desired, a
distillation column can be used to fractionate the base oil into
different viscosity cuts. Many variations and schemes are possible
to incorporate regenerative or recuperative heat exchangers to
recover heat from process streams and optimize the thermal
efficiency of the process.
[0065] Additional processing may be undertaken on the distillate
stream 54 from vessel 52 such as further separating the
constituents of this stream such as water, glycols, solvents, light
hydrocarbons and the like, thereby creating separate products which
may be used or further upgraded to higher quality products. These
product streams may also be further treated to improve their
quality as known to those skilled in the art.
[0066] In the preferred embodiment only one distillate cut is taken
from vessel 112 for further processing in stage #2. It is also
possible to take a second cut or add another fractionation vessel
(not shown) after vessel 112 to further fractionate the base oil
distillate to produce different viscosity grades and the like of
base oil, which can then be processed separately in stage 2 and
stage 3.
[0067] The preferred embodiment described above shows continuous
flow between the three stages. It may be desirable in certain
instances to have intermediate storage vessels between the stages
to allow for process surges, contain off specification material,
smooth operations, quality control purposes, allow for more than
one cut of base oil distillate and the like as known to those
skilled in the art.
[0068] It may also be preferred in some instance to use a phase
transfer catalyst or the like as known to those skilled in the art,
to enhance the operation of the second stage of the process whereby
the efficiency, selectivity and the like of the process are
enhanced thereby providing for better separation of the high
quality base oil molecules from the lower quality base oil
molecules.
[0069] In the third stage of the process presented in the
embodiment it may be advantageous to have multiple guard beds, run
reactors in parallel or series to utilized phase separators or the
like between reactors or between guard beds and reactors.
Furthermore, in some instances it may be advantageous to strip the
base oil of light contaminants or further fractionate it into
different viscosity cuts. Although the system described herein does
not utilize a hydrogen recovery system one could be employed to
recovery and purify un-reacted hydrogen and reaction products after
separation from the product base oil.
[0070] In certain instances it may be desirable to upgrade the
distillate stream 54 and/or 76 by hydrotreating these in a separate
hydrotreating stage as know to those skilled in the art.
Alternatively, it is possible to combine these streams with stream
172 and/or stream 96 and hydrotreat the combined streams. If this
later approach is employed it may be desirable to include a further
fractionation stage to produce a base oil cut and a fuel oil
cut.
[0071] In FIG. 3, a generalized embodiment of the present invention
is shown. In the embodiment shown, a waste oil stream 312 is
charged to a base oil separation zone 314 where a portion of the
base oil constituents (base oil fraction), line 320, is separated
from the other physical contaminants, line 316, in the waste oil.
In actual practice, the various physical contaminants typically may
be removed from the base oil fraction in such a way as to produce
more than one stream, but for simplicity are shown herein to be
separated collectively and recovered through line 316 and may
include low molecular weight materials such as light hydrocarbons,
water, glycols and the like typically having a boiling range
generally below about 500.degree. F., although it may be desirable
to include all materials below 650.degree. F., and high molecular
weight materials and materials with low volatility including,
particulates, polymers, salts and the like typically having a
boiling point greater than about 1050.degree. F. The base oil
fraction recovered through a line 320 typically consist of
hydrocarbon molecules suitable for use or manufacture into base oil
typically with 18 to 40 carbon atoms and having a boiling range
between about 500 to about 1050.degree. F.
[0072] In a high quality base oil separation zone 322, a portion of
the higher quality base oil molecules (high quality base oil) is
separated from the lower quality base oil molecules (lower quality
base oil) and recovered through a line 324 and passed to a high
quality base oil treatment zone 325 where it is more fully
saturated and treated for the removal of various elemental
contaminants which are recovered through a line 327, to produce a
highly purified base oil which meets the requirements of at least
one of API 1509, Group I, II or III which is recovered through a
line 326. Various materials, contaminants, derivatives and products
thereof and the like are recovered via a line 327.
[0073] The lower quality base oil is recovered through a line 323
and passed to a lower quality base oil treatment zone 328 where it
is more fully saturated and treated for the removal of various
elemental contaminants which are recovered through a line 332, to
produce a marketable quality base oil which meets the requirements
of at least one of API 1509, Group I, II or III which is recovered
through a line 330. Various materials contaminants, derivatives and
products thereof and the like are recovered via a line 332. This is
a relatively generalized showing of a further process of the
present invention. However, it shows an important feature of the
present invention.
[0074] In the first stage, zone 314, the base oil fraction is
separated from physical contaminants in the waste oil. Typically,
such contaminants include water, light hydrocarbons, solvents,
solids, polymers, high molecular weight hydrocarbons, lubricating
oil additives, chemicals, salts and the like. Several processes or
combination of processes can be used to effect this separation
including various forms of extraction, distillation, filtration,
centri fugation, absorption and adsorption and the like as known to
those skilled in the art. Typically, the separation will take place
based upon differences in the physical or chemical properties of
the base oil fraction and the various contaminating materials.
[0075] In the second stage, the oil base fraction is then fed to
zone 322 of the process where a portion of the lower quality base
oil molecules are separated from the high quality base oil. These
molecules may comprise polars, aromatics, olefins, unsaturates,
heteroatoms and the like, which are separated from the higher
quality base oil molecules, which are typically saturated,
paraffinic and non-aromatic. The stream in line 323 will typically
have a higher concentration of sulfur, oxygen, nitrogen, olefins,
aromatics and the like. Various processes or combinations thereof
can be used to effect separation of these materials from the high
quality base oil. These processes include various forms of
extraction, ultrafiltration, absorption, adsorption, molecular
sieves and the like, as known to those skilled in the art.
[0076] In the third stage, stream 323 is processed in zone 323 by
hydrogenating, alkylating, molecular reforming, molecular
substituting or the like or a combination thereof, as known to
those skilled in the art to remove undesirable elements such as
sulfur, nitrogen, oxygen and the like and increase the percent
saturation of at least a portion of the hydrocarbon molecules in
the lower quality base oil stream. The resulting base oil produced
through line 330 is typically of a quality sufficient to meet the
requirements for Groups I, II, or III of API 1509.
[0077] In the fourth stage, stream 324 is processed in zone 325 by
hydrogenating, alkylating, molecular reforming, molecular
substituting or the like or a combination thereof, as known to
those skilled in the art to remove undesirable elements such as
sulfur, nitrogen, oxygen and the like and increase the percent
saturation of at least a portion of the hydrocarbon molecules in
the lower quality base oil stream. The resulting base oil produced
through line 326 is typically of a quality sufficient to meet the
requirements for Groups I, II, or III of API 1509.
[0078] In FIG. 4, a generalized embodiment of the present invention
is shown. In the embodiment shown, a waste oil stream 412 is
charged to a base oil separation zone 414 where a portion of the
base oil constituents (base oil fraction), line 420, is separated
from the other physical contaminants, line 416, in the waste oil.
In actual practice, the various physical contaminants may typically
be removed from the base oil fraction in such a way as to produce
more than one stream, but for simplicity are shown herein to be
separated collectively and recovered through line 416 and may
include low molecular weight materials such as light hydrocarbons,
water, glycols and the like typically having a boiling range
generally below about 500.degree. F., although it may be desirable
to include all materials below 650.degree. F., and high molecular
weight materials and materials with low volatility including,
particulates, polymers, salts and the like typically having a
boiling point greater than about 1050.degree. F. The base oil
fraction recovered through a line 420 typically consists of
hydrocarbon molecules suitable for use or manufacture into base oil
typically with 18 to 40 carbon atoms and having a boiling range
between about 500 to about 1100.degree. F.
[0079] In a severe ultra high quality base oil separation zone 422,
a portion of the higher quality base oil molecules (high quality
base oil) is separated from the lower quality base oil molecules
(lower quality base oil) and recovered through a line 424 for sale
as product base oil. This high quality base oil typically meets at
least one of Groups I, II or III as set forth by API 1509. The
lower quality base oil is recovered through a line 26 and are sold
as a fuel oil or further treated to upgrade the oil to a marketable
quality base oil.
[0080] In the first stage, zone 414, the base oil fraction is
separated from physical contaminants in the waste oil. Typically,
such contaminants include water, light hydrocarbons, solvents,
solids, polymers, high molecular weight hydrocarbons, lubricating
oil additives, chemicals, salts and the like. Several processes or
combination of processes can be used to effect this separation
including various forms of extraction, distillation, filtration,
centrifugation, absorption and adsorption and the like as known to
those skilled in the art. Typically, the separation will take place
based upon differences in the physical or chemical properties of
the base oil fraction and the various contaminating materials.
[0081] In the second stage, the oil base fraction is then fed to
zone 422 of the process where a portion of the lower quality base
oil molecules are separated via a line 526. These molecules may
comprise polars, aromatics, olefins, unsaturates, heteroatoms and
the like, which are separated from the higher quality base oil
molecules, which are typically saturated, paraffinic and
non-aromatic. The higher quality base oil molecules in line 424 are
a high quality base oil stream typically having a percent of
saturates greater than 90% and a sulfur content less than about 0.3
weight percent. The stream in line 426 will typically have a higher
concentration of sulfur, oxygen, nitrogen, olefins, aromatics and
the like. Various processes or combinations thereof can be used to
effect separation of these materials from the high quality base
oil. These processes include various forms of extraction,
ultrafiltration, absorption, adsorption, molecular sieves and the
like, as known to those skilled in the art.
[0082] In FIG. 5, a generalized embodiment 500 of the present
invention is shown. In the embodiment shown, a waste oil stream 512
is charged to a base oil separation zone 514 where a portion of the
base oil constituents (base oil fraction), line 520, is separated
from the other physical contaminants, line 516, in the waste oil.
In actual practice, the various physical contaminants may typically
be removed from the base oil fraction in such a way as to produce
more than one stream, but for simplicity are shown herein to be
separated collectively and recovered through line 516 and may
include low molecular weight materials such as light hydrocarbons,
water, glycols and the like typically having a boiling range
generally below about 500.degree. F., although it may be desirable
to include all materials below 650.degree. F., and high molecular
weight materials and materials with low volatility including,
particulates, polymers, salts and the like typically having a
boiling point greater than about 1050.degree. F. The base oil
fraction recovered through a line 520 typically consist of
hydrocarbon molecules suitable for use or manufacture into base oil
typically with 18 to 40 carbon atoms and having a boiling range
between about 500 to about 1100.degree. F.
[0083] In a high quality base oil separation zone 522, a portion of
the higher quality base oil molecules (high quality base oil) is
separated from the lower quality base oil molecules (lower quality
base oil) and recovered through a line 524 and passed to a high
quality base oil treatment zone 528 where it is more fully
saturated and treated for the removal of various elemental
contaminants which are recovered through a line 525, to produce a
highly purified base oil which meets the requirements of at least
one of API 1509, Group I, II or III which is recovered through a
line 526. Various materials contaminants, derivatives and products
thereof and the like are recovered via, a line 527. The lower
quality base oil is recovered through a line 523 are sold as a fuel
oil or further treated to upgrade the oil to a marketable quality
base oil.
[0084] In the first stage, zone 514, the base oil fraction is
separated from physical contaminants in the waste oil. Typically,
such contaminants include water, light hydrocarbons, solvents,
solids, polymers, high molecular weight hydrocarbons, lubricating
oil additives, chemicals, salts and the like. Several processes or
combination of processes can be used to effect this separation
including various forms of extraction, distillation, filtration,
centrifugation, absorption and adsorption and the like as known to
those skilled in the art. Typically, the separation will take place
based upon differences in the physical or chemical properties of
the base oil fraction and the various contaminating materials.
[0085] In the second stage, the oil base fraction is then fed to
zone 522 of the process where a portion of the lower quality base
oil molecules are separated from the higher quality base oil
molecules. These lower quality molecules may comprise polars,
aromatics, olefins, unsaturates, heteroatoms and the like, which
are separated from the higher quality base oil molecules, which are
typically saturated, parfinic and non-aromatic. The stream in line
523 will typically have a higher concentration of sulfur, oxygen,
nitrogen, olefins, aromatics and the like. Various processes or
combinations thereof can be used to effect separation of these
materials from the high quality base oil. These processes include
various forms of extraction, ultrafiltration, absorption,
adsorption, molecular sieves and the like, as known to those
skilled in the art.
[0086] In the third stage, stream 524 is processed in zone 525 by
hydrogenating, alkylating, molecular reforming, molecular
substituting or the like or a combination thereof, as known to
those skilled in the art to remove undesirable elements such as
sulfur, nitrogen, oxygen and the like and increase the percent
saturation of at least a portion of the hydrocarbon molecules in
the lower quality base oil stream. The resulting base oil produced
through line 526 is a highly purified base oil typically of a
quality sufficient to meet the requirements for one of Groups I,
II, or III of API 1509.
[0087] By the process of the present invention, the base oil stream
is separated from the waste oil stream and thereafter separated
into a high quality base oil stream and a lower quality base oil
stream with the lower quality base oil stream then being upgraded
to produce a saleable base oil stream. The combination of these
steps has produced a surprisingly superior process that yields a
surprisingly high quantity of high quality base oil.
[0088] The use of this multi-stage process provides several
significant advantages over existing process methodologies. The
invention of this patent enables both of the objectives of
manufacturing products that meet the demands of the market for
quality useable products and the desire to maximize the amount of
base oil produced from the waste oil. Exiting processes can only
produce high quality base oil at the expense of the process
efficiency or yield loss.
[0089] The total base oil produced through lines 156 and 206 in
FIG. 2 is more than has been produced by previous processes and is
of higher overall quality. When previous extraction processes are
used to separate the base oil from other undesirable components,
the extraction treatment is required to be relatively intense in
order to produce high quality base oil and consequently results in
a base oil yield loss due to over extraction. Similarly, when
previous hydrotreating processes are used relatively intense
treatment is again required in order to produce high quality base
oil. This severe treatment results in cracking of some of the base
oil molecules into smaller non-base oil molecules resulting in
yield loss. Thus neither of these processes alone are capable of
producing a high yield and high quality base oil
[0090] According to the present invention, a base oil material is
charged to extraction and intense extraction can be used to
separate the lower quality base oil, containing contaminants, from
the high quality base oil since the extracted oil is recovered and
upgraded in the next stage without concern for yield loss. Through
the use of the multi-stage process described herein, it is possible
to produce a high yield and high quality base oil due to the
removal of the threat of yield loss. This surprising result has not
heretofore been achieved using known processing methods.
[0091] A further advantage of the present invention is its ability
to produce a high yield of base oil with an overall high quality.
Typically from about 45 to about 65 percent of the oil content of
the waste oil stream, depending on the desired base quality of base
oil is recovered in stage 2 through stream 156 and an addition 10
to 30 percent of base oil is produced in stage 3 through stream
206. Typically, over 90 percent of the base oil contained in the
waste oil stream 42 is recovered and/or upgraded through the
process described herein resulting in an overall base oil yield of
between 75 and 85%. Typically known process only yield between 60
and 65 percent base oil.
[0092] Another unexpected advantage of the current invention over
existing technologies is its ability to process waste oils of
varying specification and quality and still produce a high yield of
high quality base oil. Existing processes are highly influenced by
feedstock quality and their product quality and/or yield are highly
influenced by feedstock quality. The invention outlined herein is
capable of processing a wide variety of waste oils and still
manufacturing a high quality base oil and maintain a high yield of
total base oil product.
[0093] The present invention also has the unexpected benefit of
reducing capital expenditures. In known processes the good base oil
molecules are typically treated with the contaminated base oil
molecules, even though upgrading of the good base oil molecules may
not be necessary. Because of this the upgrading process must be
sized larger to process all of the base oil molecules together.
Typically upgrading equipment is very expensive to build and
operate. In the current invention the good base oil molecules are
separated from the contaminated base oil molecules prior to
upgrading the contaminated molecules. By doing so the upgrading
processing equipment can be sized smaller thereby saving capital
and operating costs.
[0094] The use of the type of distillation system disclosed herein
is considered to provide substantial advantages over previous
systems. The process provides additional efficiency and economic
benefits since it uses simple flash vessels enabling more effective
separation with less complicated equipment at each stage.
Similarly, it enables excellent separation of the contaminants
typically found in waste oil yielding a base oil distillate
suitable for further processing and upgrading. The sequential
removal of physical contaminants also enables good control over the
separation of contaminants yielding valuable products in addition
to the base oil distillate such as fuel oil, asphalt and the like.
The in-situ distillation system described herein does not have
mechanical means such as those found in film evaporators and the
like resulting in lower capital maintenance and operating costs. A
further advantage of the in-situ distillation system is that it
avoids the typical problems of packing fouling, which can be
experienced when processing used oil through packed columns. Flash
vessels do not have any packing and thus have minimal surfaces and
contact points for fouling deposits to occur. When packed column
are used to effect distillation the packing can become fouled with
tarry deposits reducing packing efficiency and eventually
restricting the flow and material in the column again resulting in
increased operational and maintenance costs.
[0095] A surprising benefit of the process is its ability to avoid
the problem of heat exchanger fouling typically experienced in
waste oil processing facilities utilizing hot surfaces to affect
heat exchange. The return streams for vessels 70 and 90 are used to
maintain the temperature in the liquid layer in the bottom of the
vessels. The oil fed into vessels 70 and 90 is heated to the
temperature necessary to effect the desired separation by direct
contact with the liquid layer in the bottom of the vessels. The
benefit is achieved by heating and vaporizing the oil through
direct contact with the hotter fluid residing in the bottom layer
of the vessel. Fouling reactions and the like which typically occur
when evaporation occurs at the boundary layer of the hot surfaces
of heat exchangers and result in deposits, reduced efficiency and
maintenance are reduced due to the absence of a hot metal surfaces
in which to deposit fouling products. Thus the current invention
increases the efficiency of heat exchange, reduces maintenance and
ultimately increases equipment availability.
[0096] The solvent extraction system employed herein has produced
surprising results by producing API Group III Base oil. No other
re-refining technology heretofore has been able to produce base oil
of this high quality.
[0097] While the present invention has been described by reference
to certain of its preferred embodiments, it is pointed out that the
embodiments described are illustrative rather than limiting in
nature and that many variations and modifications are possible
within the scope of the present invention. Many such variations and
modifications may be considered obvious and desirable by those
skilled in the art based upon a review of the foregoing description
of preferred embodiments.
* * * * *