U.S. patent application number 12/174816 was filed with the patent office on 2010-02-11 for mercury removal from crude oil.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. Invention is credited to Joseph B. Cross, John M. Hays, Randall L. Heald, Scott D. Love, Probjot Singh.
Application Number | 20100032344 12/174816 |
Document ID | / |
Family ID | 41651910 |
Filed Date | 2010-02-11 |
United States Patent
Application |
20100032344 |
Kind Code |
A1 |
Cross; Joseph B. ; et
al. |
February 11, 2010 |
MERCURY REMOVAL FROM CRUDE OIL
Abstract
A process for decreasing the level of elemental mercury
contained in a crude oil at the well site by separating the crude
oil stream into a gaseous hydrocarbon stream containing
hydrocarbons, mercury and water, and a liquid hydrocarbon stream
containing hydrocarbons and elemental mercury; removing mercury
from the gaseous hydrocarbon stream in a mercury removal unit,
thereby forming a treated gas stream; contacting a recycle gas
stream comprising a portion of the treated gas stream with at least
a portion of the liquid hydrocarbon stream for transfer of at least
a portion of the elemental mercury contained in the liquid
hydrocarbon stream to the recycle gas stream; thereby forming a
mercury rich gas stream, and a treated liquid hydrocarbon stream;
and passing the mercury rich gas stream, along with the gaseous
hydrocarbon stream, to the mercury removal unit, is disclosed.
Inventors: |
Cross; Joseph B.;
(Bartlesville, OK) ; Singh; Probjot;
(Bartlesville, OK) ; Heald; Randall L.;
(Bartlesville, OK) ; Hays; John M.; (Bartlesville,
OK) ; Love; Scott D.; (Bartlesville, OK) |
Correspondence
Address: |
ConocoPhillips Company - IP Services Group;Attention: DOCKETING
600 N. Dairy Ashford, Bldg. MA-1135
Houston
TX
77079
US
|
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
41651910 |
Appl. No.: |
12/174816 |
Filed: |
August 11, 2008 |
Current U.S.
Class: |
208/251R |
Current CPC
Class: |
E21B 43/34 20130101;
C10G 25/00 20130101; B01D 2257/602 20130101; B01D 53/64 20130101;
B01D 2259/401 20130101; B01D 2256/24 20130101 |
Class at
Publication: |
208/251.R |
International
Class: |
C10G 17/00 20060101
C10G017/00 |
Claims
1. A process comprising: a) extracting a crude oil stream
comprising elemental mercury, hydrocarbons and water from a crude
oil well; b) separating said crude oil stream into a gaseous
hydrocarbon stream comprising hydrocarbons, mercury and water, and
a liquid hydrocarbon stream comprising hydrocarbons and elemental
mercury; c) charging a mercury-containing gas feed, including in
part at least a portion of said gaseous hydrocarbon stream, to a
mercury removal unit for removal of mercury from said
mercury-containing gas feed, thereby forming a treated gas stream;
d) contacting a recycle gas stream comprising a portion of said
treated gas stream with at least a portion of said liquid
hydrocarbon stream for transfer of at least a portion of the
elemental mercury contained in said liquid hydrocarbon stream to
said recycle gas stream; thereby forming a mercury rich gas stream,
and a treated liquid hydrocarbon stream; and e) passing said
mercury rich gas stream to said mercury removal unit as a portion
of said mercury-containing gas feed.
2. A process in accordance with claim 1 wherein water is removed
from said mercury-containing gas feed prior to charging to said
mercury removal unit in step c).
3. A process in accordance with claim 1 wherein said contacting of
step d) occurs in a vessel, and wherein said recycle gas stream is
charged to said vessel below the location said liquid hydrocarbon
stream is charged to said vessel, and wherein said mercury rich gas
stream is removed from said vessel at a location above the location
said liquid hydrocarbon stream is charged to said vessel, and
wherein said treated liquid hydrocarbon stream is removed from said
vessel at a location below the location said liquid hydrocarbon
stream is charged to said vessel.
4. A process in accordance with claim 1 wherein said gaseous
hydrocarbon stream comprises hydrocarbons containing from about 1
to about 6 carbon atoms per molecule.
5. A process in accordance with claim 1 wherein the temperature of
said crude oil in step (a) is at least about 50.degree. C., and
wherein the pressure of said separation step (b) is at least about
0.5 Bars.
6. A process in accordance with claim 1 wherein the temperature of
said crude oil in step (a) is at least about 60.degree. C., and
wherein the pressure of said separation step (b) is at least about
1 Bars.
7. A process in accordance with claim 1 wherein said mercury
removal unit has a fixed bed comprising a mercury sorbent
material.
8. A process in accordance with claim 1 wherein said treated gas
stream comprises less than about 20 wt. % of the mercury contained
in said mercury-containing gas feed.
9. A process in accordance with claim 1 wherein said treated gas
stream comprises less than about 10 wt. % of the mercury contained
in said mercury-containing gas feed.
10. A process in accordance with claim 1 wherein said treated
liquid hydrocarbon stream comprises less than about 50 wt. % of the
elemental mercury contained in said liquid hydrocarbon stream.
11. A process in accordance with claim 1 wherein said treated
liquid hydrocarbon stream comprises less than about 20 wt. % of the
elemental mercury contained in said liquid hydrocarbon stream.
12. A process in accordance with claim 1 wherein said liquid
hydrocarbon stream comprises at least about 10 ppb elemental
mercury.
13. A process in accordance with claim 1 wherein said liquid
hydrocarbon stream comprises at least about 200 ppb elemental
mercury.
14. A process in accordance with claim 1 wherein said contacting of
step d) occurs at a temperature in the range of from about
70.degree. C. to about 300.degree. C., and a pressure in the range
of from about 0.5 Bars to about 15 Bars, and a gas to liquid ratio
in the range of from about 50 to about 300 SCF/bbl.
15. A process in accordance with claim 1 wherein said contacting of
step d) occurs at a temperature in the range of from about
150.degree. C. to about 200.degree. C., and a pressure in the range
of from about 1 Bar to about 10 Bars, and a gas to liquid ratio in
the range of from about 100 to about 200 SCF/bbl.
16. A process in accordance with claim 1 wherein said contacting of
step d) occurs at a temperature in the range of from about
150.degree. C. to about 200.degree. C., and a pressure in the range
of from about 2 Bars to about 7 Bars, and a gas to liquid ratio in
the range of from about 100 to about 200 SCF/bbl.
17. A process in accordance with claim 3 wherein said liquid
hydrocarbon stream comprises hydrocarbons, elemental mercury and
water; and wherein water is separated from said liquid hydrocarbon
stream and removed from said vessel at a location below the
location said treated liquid hydrocarbon stream is removed from
said vessel.
Description
[0001] The present invention relates to a process for the removal
of mercury from crude oil. In another aspect, this invention
relates to a process for the removal of mercury from crude oil at
the well site using produced gas.
[0002] Since the presence of mercury in crude oil can cause
problems with downstream processing units, as well as health and
environmental issues, there is an incentive to remove mercury from
crude oil.
[0003] Therefore, development of an improved process for
effectively removing mercury from crude oil before downstream
processing into products would be a significant contribution to the
art.
BRIEF SUMMARY OF THE INVENTION
[0004] In accordance with a first embodiment of the present
invention, a process is provided including the following:
[0005] a) extracting a crude oil stream comprising elemental
mercury, hydrocarbons and water from a crude oil well;
[0006] b) separating the crude oil stream into a gaseous
hydrocarbon stream comprising hydrocarbons, mercury and water, and
a liquid hydrocarbon stream comprising hydrocarbons and elemental
mercury, and which can also include water;
[0007] c) charging a mercury-containing gas feed, including in part
at least a portion of the gaseous hydrocarbon stream, to a mercury
removal unit for removal of mercury from the mercury-containing gas
feed, thereby forming a treated gas stream;
[0008] d) contacting a recycle gas stream comprising a portion of
the treated gas stream with at least a portion of the liquid
hydrocarbon stream for transfer of at least a portion of the
elemental mercury contained in the liquid hydrocarbon stream to the
recycle gas stream; thereby forming a mercury rich gas stream, and
a treated liquid hydrocarbon stream; and
[0009] e) passing the mercury rich gas stream to the mercury
removal unit as a portion of the mercury-containing gas feed.
[0010] In accordance with a second embodiment of the present
invention, a process is provided including the following:
[0011] a) extracting a crude oil stream comprising elemental
mercury, hydrocarbons and water from a crude oil well;
[0012] b) separating the crude oil stream into a gaseous
hydrocarbon stream comprising hydrocarbons, mercury and water, and
a liquid hydrocarbon stream comprising hydrocarbons and elemental
mercury, and which can also include water;
[0013] c) removing water from a mercury-containing gas feed,
including in part at least a portion of the gaseous hydrocarbon
stream, prior to charging to a mercury removal unit for removal of
mercury from the mercury-containing gas feed, thereby forming a
treated gas stream;
[0014] d) contacting a recycle gas stream comprising a portion of
the treated gas stream with at least a portion of the liquid
hydrocarbon stream for transfer of at least a portion of the
elemental mercury contained in the liquid hydrocarbon stream to the
recycle gas stream; thereby forming a mercury rich gas stream, and
a treated liquid hydrocarbon stream; and separating water from the
liquid hydrocarbon stream; and
[0015] e) passing the mercury rich gas stream to the mercury
removal unit as a portion of the mercury-containing gas feed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a simplified schematic flow diagram presenting an
embodiment of the present invention.
[0017] FIG. 2 is a simplified schematic flow diagram presenting an
embodiment of the present invention.
[0018] FIG. 3 is a graphic illustration of a temperature vs.
pressure curve, resulting from a simulation, above which
temperature 90% mercury removal from a crude oil is predicted.
[0019] FIG. 4 is a graphic illustration of results from experiments
concerning the removal of mercury from decane using methane as a
sparging media.
DETAILED DESCRIPTION OF THE INVENTION
[0020] According to the first embodiment of the present invention,
the process of the present invention will be described with
reference to FIG. 1.
[0021] Referring to FIG. 1, crude oil is removed from a crude oil
well by line 100 and is passed to separator 102 for separation into
a gaseous hydrocarbon stream comprising, consisting of, or
consisting essentially of hydrocarbons, mercury and water, which is
removed from separator 102 by line 104, and into a liquid
hydrocarbon stream: 1) comprising, consisting of, or consisting
essentially of hydrocarbons and elemental mercury, or 2)
comprising, consisting of, or consisting essentially of
hydrocarbons, elemental mercury and water, which is removed from
separator 102 by line 106. A mercury-containing gas feed, including
in part at least a portion of the gaseous hydrocarbon stream, is
charged to a mercury removal unit (MRU) 108 by line 110 for removal
of mercury from the mercury-containing gas feed, thereby forming a
treated gas stream, which is removed from MRU 108 by line 112. A
recycle gas stream comprising a portion of treated gas stream from
line 112 is charged to a contactor 114 by line 116 for contact with
at least a portion of the liquid hydrocarbon stream charged to
contactor 114 by line 106. Through such contacting, at least a
portion of the elemental mercury contained in the liquid
hydrocarbon stream is transferred to the recycle gas stream,
thereby forming a mercury rich gas stream, which is removed from
contactor 114 by line 118, and a treated liquid hydrocarbon stream,
which is removed from contactor 114 by line 120. The recycle gas
stream is charged to contactor 114 by line 116 below the location
line 106 charges the liquid hydrocarbon stream to contactor 114.
The mercury rich gas stream is removed from contactor 114 by line
118 at a location above the location line 106 charges the liquid
hydrocarbon stream to contactor 114. The treated liquid hydrocarbon
stream is removed from contactor 114 by line 120 at a location
below the location line 106 charges the liquid hydrocarbon stream
to contactor 114. The mercury rich gas stream is passed to the MRU
108 as a portion of the mercury-containing gas feed by lines 118
and 110.
[0022] According to the second embodiment of the present invention,
the process of the present invention will be described with
reference to FIG. 2.
[0023] Referring to FIG. 2, crude oil is removed from a crude oil
well by line 200 and is passed to separator 202 for separation into
a gaseous hydrocarbon stream comprising, consisting of, or
consisting essentially of hydrocarbons, mercury and water, which is
removed from separator 202 by line 204, and into a liquid
hydrocarbon stream comprising, consisting of, or consisting
essentially of hydrocarbons, elemental mercury and water, which is
removed from separator 202 by line 206. Along with a mercury rich
gas stream described later, the gaseous hydrocarbon stream is
charged to a separator 207 wherein water is removed and exits
separator 207 by line 208. The overhead gases leaving separator 207
by line 209 are charged to a mercury removal unit (MRU) 210 as a
mercury-containing gas feed for removal of mercury from the
mercury-containing gas feed, thereby forming a treated gas stream,
which is removed from MRU 210 by line 212. A recycle gas stream
comprising a portion of the treated gas stream from line 212 is
charged to a contactor 214 by line 216 for contact with at least a
portion of the liquid hydrocarbon stream charged to contactor 214
by line 206. Through such contacting, at least a portion of the
elemental mercury contained in the liquid hydrocarbon stream is
transferred to the recycle gas stream, thereby forming a mercury
rich gas stream, which is removed from contactor 214 by line 218,
and a treated liquid hydrocarbon stream, which is removed from
contactor 214 by line 220. In addition, water is separated from the
liquid hydrocarbon stream (and from the recycle gas stream, if
water is present in such) and removed from contactor 214 by line
222. The recycle gas stream is charged to contactor 214 by line 216
below the location line 206 charges the liquid hydrocarbon stream
to contactor 214. The mercury rich gas stream is removed from
contactor 214 by line 218 at a location above the location line 206
charges the liquid hydrocarbon stream to contactor 214. The treated
liquid hydrocarbon stream is removed from contactor 214 by line 220
at a location below the location line 206 charges the liquid
hydrocarbon stream to contactor 214. Water is removed from
contactor 214 by line 222 below the location line 220 removes the
treated liquid hydrocarbon stream from contactor 214. The mercury
rich gas stream is passed to the separator 207 along with the
gaseous hydrocarbon stream by lines 218 and 204.
[0024] The crude oil stream of the present invention comprises,
consists of, or consists essentially of a broad range crude oil.
More particularly, the crude oil stream comprises hydrocarbons
containing at least one carbon atom per molecule.
[0025] The gaseous hydrocarbon stream comprises, consists of, or
consists essentially of hydrocarbons containing from about 1 to
about 6 carbon atoms per molecule.
[0026] The temperature at which the crude oil stream is separated
into the gaseous hydrocarbon stream and the liquid hydrocarbon
stream is preferably at least about 50.degree. C., more preferably
at least about 60.degree. C. The pressure at which the crude oil
stream is separated into the gaseous hydrocarbon stream and the
liquid hydrocarbon stream is preferably at least about 0.5 Bars,
more preferably at least about 1 Bars.
[0027] The mercury removal unit has a fixed bed comprising any
mercury sorbent material capable of removing mercury from
gases.
[0028] The treated gas stream preferably comprises less than about
20 wt. % of the mercury contained in the mercury-containing gas
feed, and more preferably less than about 10 wt. % of the mercury
contained in the mercury-containing gas feed.
[0029] The treated liquid hydrocarbon stream preferably comprises
less than about 50 wt. % of the elemental mercury contained in the
liquid hydrocarbon stream, and more preferably less than about 20
wt. % of the elemental mercury contained in the liquid hydrocarbon
stream.
[0030] The liquid hydrocarbon stream typically comprises at least
about 10 ppb elemental mercury, and more particularly comprises at
least about 200 ppb elemental mercury.
[0031] The recycle gas stream is contacted with the liquid
hydrocarbon stream at a temperature in the range of from about
70.degree. C. to about 300.degree. C., preferably from about
150.degree. C. to about 200.degree. C., a pressure in the range of
from about 0.5 Bars to about 15 Bars, preferably from about 1 Bar
to about 10 Bars, and more preferably from about 2 Bars to about 7
Bars; and a gas to liquid ratio in the range of from about 50 to
about 300 standard cubic feet of gas/bbl of liquid (SCF/bbl),
preferably from about 100 to about 200 SCF/bbl.
[0032] The following examples are provided to further illustrate
this invention and are not to be considered as unduly limiting the
scope of this invention.
EXAMPLES
Example 1
[0033] To test the idea, a simulation of the liquid/gas contactor
was constructed using an equation of state thermodynamic prediction
model for mercury partitioning between gas and liquid using data
for elemental mercury in a commercially obtained crude oil blend.
The results of the calculation are shown in FIG. 3, wherein the
temperature of the crude oil is plotted against the pressure to
achieve 90% removal of mercury from the liquid oil feed to the
contactor. A gas to oil ratio of 80 SCF/bbl was used in the
model.
[0034] This simulation shows that 90% mercury removal is achievable
at the temperature and pressure conditions commonly present at the
crude oil well site. That is, wherein the pressure of the Low
Pressure Coalescer/Separator typically present at the well site
(which is redeployed in the invention as a gas/oil contactor)
ranges from about <1 to .about.3 Bars, and the reservoir
temperature of high mercury crude oils is normally greater than
about 150.degree. C.
Example 2
[0035] An experiment was run to test the removal of Hg (elemental)
from a hydrocarbon by sparging with a lighter hydrocarbon.
Elemental mercury was dissolved in decane at about 1,300 ppbw. FIG.
4 shows the results of the experiment, plotting residual Hg in the
decane vs. liters of methane sparged through the decane for two
different runs, Runs 1 and 2.
[0036] A third experiment was run wherein, prior to adding the
elemental mercury, the decane was water washed and passed over a
silica gel column to remove trace levels of chloride, oxide or
sulfur compounds that could, at the conditions of the experiment,
oxidize the mercury and cause it to form non-spargable mercury
compounds.
[0037] Also shown in FIG. 4 is a plot of the results of a
theoretical calculation of the mercury removal process, and shows
that the experimental results for Runs 1 and 2 are in good
agreement with such, and that the experimental results for Run 3 is
in excellent agreement with the theoretical calculations.
[0038] While this invention has been described in detail for the
purpose of illustration, it should not be construed as limited
thereby but intended to cover all changes and modifications within
the spirit and scope thererof.
* * * * *