HIGH THROUGHPUT EXPERIMENTATION METHODS
FOR PHASE SEPARATION
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates generally to testing of water-in-oil and oi -
in-water emulsion breaker chemicals, and in particular, to testing methods using reactor
blocks suitable for use in high-throughput testing programs in which chemical reactions
are conducted simultaneously using small volumes of reaction materials to efficiently
and economically screen multiple chemical materials.
Description of Related Art
[0002] Liquid hydrocarbon phase, such as crude oil, naturally contains a variety
of contaminants that have detrimental effects on process equipment and in the operation
of a refinery. These contaminants are broadly classified as salts, bottom sediment,
water, solids, and metals. The types and amounts of these contaminants vary depending
on the particular hydrocarbon phase. Additionally, native water present in the liquid
hydrocarbon phase as droplets may be coated with naturally occurring surfactants such
as asphaltenes, naphthenic acid salts, resins, or with solids including but not limited to
iron oxide, silica, carbon, carbonates, or phosphates. Removing the water from the
crude oil is essential at crude oil production facilities as it impacts the value of crude oil
and its economic transportation. The presence of salts, especially chlorides of Group I
and Group II elements of The Periodic Table of Elements causes corrosion of oil
processing equipment. In order to mitigate the effects of corrosion, it is advantageous
to reduce the salt concentration to the range of 1 to 5 ppm or less and water content to
about 0. 0 to 1 wt% by weight of the crude oil prior to transportation and processing of
the oil.
[0003] A standard treatment for removing small particles of solids and bottom
sediment, salts, water and metals is a phase separation operation commonly known as
dewatering or desalting. A fresh water wash in the range of typically 4 to 15 vol % is
injected into the crude oil. The crude oil and wash water are subjected to shear to
thoroughly mix the water and the crude oil to form an emulsion and to transfer the
contaminants from the crude oil into the fresh water. Frequently, a chemical emulsion
breaker is also added to the emulsion, and often, the emulsion is subjected to an
electrostatic field so that water droplets in the mixture of crude oil, wash water, and
chemical emulsion breaker coalesce in the electrostatic field between electrodes. The
coalesced water droplets settle below the oleaginous crude oil phase and are removed.
The treated crude oil is removed from the upper part of the separator.
[0004] One problem encountered with dewatering and desalting is that some
crude oils form an undesirable "rag" layer comprising a stable oil-water emulsion and
solids at the water-oil phase boundary in the desalter vessel. The rag layer often
remains in the vessel, but it may be removed for storage or for further processing. Rag
layers at the water-oil phase boundary result in oil loss and reduced processing capacity.
Heavy crude oils containing high concentrations of asphaltenes, resins, waxes, and
napthenic acids exhibit a high propensity to form rag layers.
[0005] Additives may be added to improve coalescence and dehydration of the
hydrocarbon phase, provide faster water separation, improve salt or solids extraction,
and generate oil-free effluent water. These additives, also known as demulsifiers, are
usually fed to the hydrocarbon phase to modify the oil/water interface. It is also
possible to feed these materials to the wash water or to both the oil and water. These
additives allow droplets of water to coalesce more readily and for the surfaces of solids
to be water-wetted. The additives reduce the effective time required for good separation
of oil, solids, and water.
[0006] Development of new chemical demulsifiers has typically been done
using glass bottles or glass tubes in a process referred to as "bottle testing". In the
simplest embodiment, an oil sample and treatment chemicals are added to a bottle and
shaken. The rate of demulsification (water removal) is then monitored as a function of
time by observing the amount of "free" water that collects at the bottom of the bottle
through visual inspection. This method has proven to be useful but is time consuming,
and it often fails to consistently reproduce test parameters so that the effectiveness of
different chemical demulsifiers can adequately be compared.
(0007] t is desired to improve high volume testing methods and equipment such
that one may select the most efficacious chemicals to optimize the emulsion breaker
process.
SUMMARY OF THE INVENTION
[0008] In one aspect, the invention is directed to a process for testing the
effectiveness of demulsifying additives on water-in-oil or oil-in-water emulsions. The
process includes adding samples containing differing combinations of oil, water and
demulsifier to a plurality of elongate reactor vials, wherein each the elongate reactor
vial has a longitudinal axis extending from its bottom to its rim. The plurality of reactor
vials are placed into a reaction block mounted on a platform of a shaker, wherein the
reactor vials are received in stations of the reaction block in a vertical orientation such
that the longitudinal axis of each reactor vial is perpendicular to the platform. The
reaction block is pivoted the so that the longitudinal axis of each reactor vial is parallel
with the platform in a horizontal orientation. The method further includes agitating the
reactor vials with the shaker to simultaneously form an oil/water emulsion in each
reactor vial while the reactor vials are in the horizontal orientation and then pivoting the
reaction block to return the reactor vials to a vertical orientation. The demulsification
of the oil/water emulsion in the plurality of reactor vials is observed with the reactor
vials in the vertical orientation. In one embodiment, the method further includes using
an imaging device to record the demulsification of the oil/water emulsion.
[0009J Another aspect of the invention is directed toward apparatus for testing
the effectiveness of demulsifying additives on oil/water emulsions. The apparatus
includes a plurality of elongate reactor vials for receiving samples containing differing
combinations of oil, water and demulsifier to a plurality of reactor vials, wherein each
elongate reactor vial has a longitudinal axis extending from its bottom to its rim. The
apparatus also includes a reaction block configured to receive the plurality of reactor
vials and a shaker having a platform for receiving the reaction block in a pivotable
configuration. The reactor vials are received in stations of the reaction block in a
vertical orientation such that the longitudinal axis of each reactor vial is perpendicular
to the platform, and the reaction block is pivoted so that the longitudinal axis of each
reactor vial is parallel with the platform in a horizontal orientation while agitating the
reactor vials with the shaker to simultaneously form an oil/water emulsion in each
reactor vial. The reaction block is then pivoted back so that demulsification of the
oil/water emulsion is monitored with the reactor vials in a vertical orientation. In one
embodiment, the apparatus also includes an imaging device used to record the
demulsification of the oil/water emulsion.
[0010] The present invention and its advantages over the prior art will become
apparent upon reading the following detailed description and the appended claims with
reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The above mentioned and other features of this invention will become
more apparent and the invention itself will be better understood by reference to the
following description of embodiments of the invention taken in conjunction with the
accompanying drawings, wherein:
[0012] FIG. 1 is a perspective view of apparatus used for testing the
effectiveness of demulsifying additives on oil/water emulsions;
[0013] FIG. 2 is a perspective view of the apparatus of FIG. 1 with a reaction
block pivoting to a horizontal orientation; and
[0014] FIG. 3 is a perspective view of the apparatus of FIG. 1 with the reaction
block pivoted to its horizontal orientation for agitation.
[0015] Corresponding reference characters indicate corresponding parts
throughout the views of the drawings.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The invention will now be described in the following detailed description
with reference to the drawings, wherein preferred embodiments are described in detail
to enable practice of the invention. Although the invention is described with reference
to these specific preferred embodiments, it will be understood that the invention is not
limited to these preferred embodiments. But to the contrary, the invention includes
numerous alternatives, modifications, and equivalents as will become apparent from
consideration of the following detailed description.
[0017] Referring now to FIG. 1, testing apparatus for simultaneously testing the
effectiveness of multiple demulsifiers for breaking an oil/water emulsion is shown. The
testing apparatus 10 contains a reaction block 12 configured to receive a plurality of
reactor vials or tubes 14. The reaction block 12 is shown to incorporate a block body 16
that is mounted on a substantially planer platform 17 and configured to receive the
reactor vials 14 in an array of stations 18. The reactor vials 14 are elongated tubular
structures which are vertically disposed within the block body 16 when the reaction
block 1 is in the orientation illustrated in FIG. 1. By vertically disposed, it is meant
that the longitudinal axis of the reactor vial is substantially perpendicular to the plane of
the platform 17. Each station 18 is desirably configured such that it securely retains an
inserted reactor vial 14 using a suitable clip (not shown) or by frictional fit so as to
discourage the reactor vial 14 from unintentionally falling out of the reactor block 12
during the testing process. In the illustrated embodiment, the stations 18 of the reactor
block 12 are arrayed in a 24-station 18 array having a rectangular 3x8 format, or three
rows 20 with eight stations 8 in each row. It should be apparent, however, that the
invention might employ any of a variety of arrays other than a 3x8 format, and the array
format need not even be rectangular. It is to be understood that each station 18 may
contain a different crude oil and demulsifier composition to facilitate comparisons of
different treatments. Therefore, testing on a specific crude oil composition can be
conducted using several different emulsion breaker chemistries and concentrations to
see which combination provides the most effective treatment. Alternately, a specific
emulsion breaker may be tested on different crude oil compositions, or any combination
crude oil and emulsion breakers may be tested simultaneously in the plurality of reactor
vials 14 in the reaction block 12.
[0018] The reaction block 12 initially holds the reactor vials 14 in a stacked or
vertical orientation. As best seen in FIG. 2, each row 20 of stations 18 in the reaction
block 12 is offset from the other rows 20 to facilitate loading of reactor vials 14 in the
reaction block 12. The reaction block 12 may be integrally formed by conventional
injection molding, with the injection material being polypropylene plastic. However, it
would be apparent that other molding and machining processes are also viable
production processes. t would also be apparent to one with ordinary skill in the art that
the reaction block 12 might be formed from other thermoplastics and from other
sufficiently inert materials such as glasses, metals, and other types of resins as well.
The block 12 might also be made from a combination of materials permanently or
removably joined or fitted together.
[0019] Each of the reactor vials 14 includes an elongate tube bore 24, the length
or height of the latter being determined from a vial bottom 26 up and to a vial rim 28.
Each station 18 has a window 30 so that the tube bore 24 along its longitudinal axis is
visible so that the oil/water separation in the reactor vial 14 may be monitored.
Although in the reactor vials 14 are shown as having a cylindrical shape (i.e., a circular
cross-section), it is understood that reactor vials having other shapes may be used. In
one embodiment, the bottom 26 of the reactor vial 14 has a conical or V-shape portion
to increase the precision of test results in this portion of the vial. n the illustrated
embodiment, each reactor vial 14 has a volume of about 5 ml. It should be apparent,
however, that the invention might employ vials 14 any of a variety of volumes, such as
100 ml, without departing from the scope of the invention. Desirably, each reactor vial
14 has a crimp cap 32 and Teflon® coated septa (not shown) rather than a screw cap,
which may loosen during heating and shaking and leak. In one embodiment, an
insulated electrode is placed outside the vials 14 to provide an electric field capable of
voltages of 100 to 10,000 volts. Desirably, the electrode is configured to run
perpendicular to the long axis of the vials 14.
[0020] The reaction block further comprises a heater 34 for controlling the
temperature of the reactor vials 14 such that samples can be tested at near actual
temperatures found in the field. The particular design for the heater 34 is not critical.
In one embodiment, the heater 34 can use cartridge heating elements (e.g., resistiveheating
element) in thermal communication with each station 18 of the reaction block
12. Alternatively, the heater 34 can use a hot gas or liquid to heat the reactor vials 14 or
the reaction black 12 can be used in an enclosure defining a heated environment (e.g.,
oven). The heater desirably maintains temperature of the reactor vials between about
100 and 200°C, and more preferably between about 120-130°C, during the testing
process.
[0021] One skilled in the art will understand that suitable temperature
controllers 36 and sensors (not shown) are used with the heater 34 depending on the
application. Desirably, surface mounted thermocouple, RTD or thermistors temperature
sensors are mounted to the reaction block 12. In the illustrated embodiment, a digital
temperature controller 36 is used to independently control the temperature of each row
20 in the reaction block such that there are three temperature zones 38A, 38B and 38C.
[0022] The reaction block 2 is mounted on the platform which is part of an
agitation device or shaker 40. The agitation device 40 is used to emulsify the oil and
water sample in each of the reactor vials 14. The particular design for the agitation
device 40 is not critical and can be an orbital or linear shaker as known in the art.
Subjecting the reaction block 12 to agitation provides a more consistent emulsion
generation in all of the reactor vials 14 held in the reaction block 2 so that effective
test comparisons can be made between each vial.
[0023] According to the invention, the reaction block 12 is mounted on the
platform 17 such that it can be pivoted about 90 degrees from the generally vertical
loading and observation array orientation shown in FIG. 1 to a generally horizontal
orientation as shown in FIGS. 2 and 3 for shaking and emulsion forming. By a
horizontal orientation, it is meant that the reactor block 12 is pivoted such that it holds
the reactor vials 14 such that the longitudinal axes of the reactor vials 14 are
substantially parallel with the plane of the platform 17. In one embodiment, the shaker
40 has a pivot member 42 to secure the reaction block 12 to the platform 17. This can
be accomplished, for example, as best seen in FIG. 3 by providing the shaker 40 with a
retaining means 44 such as an L-shaped flange fixed to or integral with platform 17 of
the shaker 40. The L-shaped flange 44 retains a first end 46 of the reaction block 12
with the pivot member 42 so as to allow the reaction block to pivot with respect to the
platform 17. However, one skilled in the art will understand that other means to
pivotally mount the reaction block 12 to the platform 17 may be used using sound
engineering judgment without departing from the scope of the invention.
[0024] The invention also encompasses the method of testing demulsifying
additives for effective treatment of oil/water emulsions in a simultaneous and consistent
manner using the testing apparatus. Reactor vials 14 containing the oil/water mixture
and demulsifying agents are loaded into the reaction block 12 with the reaction block 12
in its vertical orientation. Alternately, the reactor vials 14 may be filled while in the
reaction block 12. Desired temperature parameters are maintained with the heater 34.
In order to simultaneously create the emulsions in the reactor vials 14, the reaction
block is pivoted to a substantially horizontal orientation, and the reaction block 12 is
agitated with the shaker 40 while in the horizontal orientation. Without being limited to
any specific reasoning, it has been found that better emulsions are formed when the
reactor vials 14 are shaken in the horizontal orientation than if they were just shaken in
the vertical orientation. After the emulsions are formed, the reaction block 12 is
returned to the vertical orientation, and visual inspection of the demulsification in the
reactor vials 14 is observed.
[0025] In one embodiment, an imaging device 50 is used to record the
demulsification as seen in FIG. 1. The imaging device 50 may be a digital camera or
other recording device used to record the separation of the oil and water in the reactor
vials 14. The digital camera 50 can be operated manually or by using a controller (not
shown) to record images at desired time intervals such that the operator need not be
present during the entire time necessary to separate the emulsion. Accordingly,
photography and image analysis may be used rather than visual inspection to collect the
data. This allows all the reactor vials 14 to be assessed at the same time intervals which
is desirable, since they all have the emulsion created at the same time. Desirably, a
suitable backdrop 52 is place behind or on the back of the reaction block 12.
[0026] While the disclosure has been illustrated and described in typical
embodiments, it is not intended to be limited to the details shown, since various
modifications and substitutions can be made without departing in any way from the
spirit of the present disclosure. As such, further modifications and equivalents of the
disclosure herein disclosed may occur to persons skilled in the art using no more than
routine experimentation, and all such modifications and equivalents are believed to be
within the scope of the disclosure as defined by the following claims.

What is claimed is:
CLAIMS
1. A process for testing the effectiveness of demulsifying additives on
oil/water emulsions, the process comprising:
adding samples containing differing combinations of oil, water and demulsifier
to a plurality of elongate reactor vials, wherein each said elongate reactor vial has a
longitudinal axis extending from its bottom to its rim;
placing said plurality of reactor vials into a reaction block mounted on a
platform of a shaker, wherein said reactor vials are received in stations of the reaction
block in a vertical orientation such that the longitudinal axis of each reactor vial is
perpendicular to the platform;
pivoting the reaction block so that the longitudinal axis of each reactor vial is
parallel with the platform in a horizontal orientation;
agitating the reactor vials with the shaker to simultaneously form an oil/water
emulsion in each reactor vial while said reactor vials are in the horizontal orientation;
pivoting the reaction block to return the reactor vials to a vertical orientation;
and
observing the demulsification of the oil/water emulsion in the plurality of
reactor vials.
2. The process of claim 1 further comprising using an imaging device to
record the demulsification of the oil/water emulsion.
3. The process of claim wherein the imaging device is a digital camera
and a plurality of photographs are taken at different times to compare the effectiveness
of demulsification between the plurality of vials.
4. The process of claim 1 wherein the reactor vials are placed in the
reaction block in an array having a plurality of rows, wherein each row has a plurality
of stations.
5. The process of claim 1 wherein samples containing less than about 5 ml
of sample are added to the reactor vials.
6. The process of claim 1 further comprising heating the samples to at least
120°C.
7. The process of claim 1 wherein each sample contains a different
demulsifier or different concentration of demulsifier.
8. Apparatus for testing the effectiveness of demulsifying additives on
oil/water emulsions, the apparatus comprising:
a plurality of elongate reactor vials for receiving samples containing differing
combinations of oil, water and demulsifier to a plurality of reactor vials, wherein each
said elongate reactor vial has a longitudinal axis extending from its bottom to its rim;
a reaction block configured to receive the plurality of reactor vials; and
a shaker having a platform for receiving the reaction block in a pivotable
configuration, wherein said reactor vials are received in stations of the reaction block in
a vertical orientation such that the longitudinal axis of each reactor vial is perpendicular
to the platform and said reaction block is pivoted so that the longitudinal axis of each
reactor vial is parallel with the platform in a horizontal orientation while agitating the
reactor vials with the shaker to simultaneously form an oil/water emulsion in each
reactor vial and then pivoted back so that demulsification of the oil/water emulsion is
monitored with the reactor vials in a vertical orientation.
9. The apparatus of claim 8 further comprising an imaging device used to
record the demulsification of the oil/water emulsion.
10. The apparatus of claim 9 wherein the imaging device is a digital camera.
11. The apparatus claim 8 wherein the reaction block has a plurality of rows,
wherein each row has a plurality of stations to receive a reactor vial.
12. The apparatus claim 8 wherein the reactor vials have a volume of about 5
ml.
13. The apparatus claim 12 wherein the reactor vials are closed using septa
and metal caps crimped to the vials
14. The apparatus claim 8 further comprising a heating configured to heat
the reactor vials to at least 120°C.
15. The apparatus in claim 8 further comprising an insulated electrode
placed outside the vials to provide an electric field capable of voltages of 00 to 10,000
volts.
16. The process of claim 1 wherein samples are placed in reactor vials
having a volume of about 100 ml or less.
17. The process of claim 1 wherein samples are placed in reactor vials
having a volume of about 5 ml or less.