Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
TITLE
[0001] A process and system for recovering contaminants from production
water
FIELD
[0002] There is described a process and system for recovering contaminants
from
production water.
BACKGROUND
[0003] A by-product of oil and gas production is water that was either
trapped in the same
deep formations as the oil and gas, water that was injected to stimulate a
formation (e.g.,
hydraulic fracturing), or water that was injected to enhance oil recovery.
This water by-product
is commonly known as "production water". Production water is generally
disposed of by
injection into disposal wells.
[0004] Due to environmental concerns over the use of fresh water, there has
been pressure
placed upon the oil and gas industry to use production water. Production water
is highly saline
and contaminated with noxious compounds including B1EX (benzene, toluene,
ethyl benzene,
and xylene), alkanes, and other hydrocarbons. Untreated production water
stored in
atmospheric storage ponds creates safety and environmental risks through the
release of the
noxious emissions created by the contaminants.
[0005] Efforts are now being made to remove contaminants from production
water, so the
production water can be safely stored. Activated carbon technology is one
medium currently
being used to remove contaminants from production water. Activated carbon
saturated by
contaminants is currently being disposed of at landfill sites.
SUMMARY
[0006] According to one aspect there is provided a process for removing
contaminants from
production water, which involves passing production water through an
adsorption media in
order to capture hydrocarbon contaminants. The process then involves
subjecting the
adsorption media to a heat treatment until the contaminants undergo a phase
change to gaseous
fon'', condensing the contaminants in the gaseous form to a liquid form, and
capturing the
contaminants in the liquid form.
Date Recue/Date Received 2020-08-14
2
[0007] While the process, as described above, works with any adsorption
media capable of
adsorbing hydrocarbon contaminants, in various forms, beneficial results have
been obtained
through the use of a combination of activated and bio carbon adsorption media.
It is prefened
that the adsorption media used be in a granulated form, as the granulated form
is easier to
handle and manipulate.
[0008] While the process, as described above, will work whether the de-
contaminated
water is put to use directly after de-contamination or stored for later use,
it is anticipated that
after removal of the contaminants, the production water will be stored in
uncovered water
storage ponds in accordance with standard oil and gas industry practices.
[0009] While the process, as described above, will work to some degree as
long as the
contaminated production water is flowing through the adsorption media, it is
preferred that the
flow rate through the adsorption media be closely controlled. Controlling the
flow rate will
allow for the most optimal removal of contaminants from the production water,
as the
effectiveness of the adsorption media depends upon time exposure.
[0010] While the process, as described above, will work with some
contaminants at lower
temperature ranges, it is preferred that the adsorption media is subjected to
heat treatment at
temperatures of between 650 and 850 degrees Celsius, as some contaminants
(such as B l'EX)
will only be combusted or undergo a phase change to gaseous form at
temperatures of between
650 and 850 degrees Celsius.
[0011] While the process described above will work without any agitation,
it is preferred
that the adsorption media is agitated during the heat treatment. Agitation
will assist with
exposure of the contaminants to both heat and combustion air.
[0012] According to another aspect there is described a system that was
developed for the
purpose of implementing the method. There is provided a system for removing
contaminants
from production water, which includes an adsorption media module, an
adsorption media
rejuvenation module, and a hydrocarbon contaminants recovery module.
Date Recue/Date Received 2020-08-14
3
[0013] The adsorption media module includes one or more elongated vessels
that contain
an adsorption media capable of adsorbing hydrocarbons. The one or more
elongated vessels
have a first end and a second end. There is a water inlet at the first end and
a water outlet at the
.. second end. There is also a media inlet at the first end. The one or more
elongated vessels are
in a generally horizontal orientation. The adsorption media module also
includes a flow control
assembly for controlling a flow rate of production water through the one or
more elongated
vessels from the inlet to the outlet.
[0014] The adsorption media rejuvenation module includes a kiln for
subjecting the
adsorption media to a heat treatment until the contaminants undergo a phase
change to gaseous
form.
[0015] The hydrocarbon contaminants recovery module includes at least one
cooler-
condenser for condensing the contaminants in the gaseous form to a liquid
fonn, and a storage
container for capturing the contaminants in the liquid form.
[0016] While the one or more elongated vessels are in a substantially
horizontal orientation
to assist with flow control, it is preferred that the one or more elongated
vessels oriented at an
oblique angle relative to a horizontal plane, with the first end positioned
above the second end.
The slightly elevated horizontal position allows the water to slowly flow
through the adsorption
media by operation of gravity. The slightly elevated position also encourages
the flow of
adsorption media from the first end to the second end via the operation of
gravity. This results
in gravity assisting in loading the adsorption media into the elongated
vessels and gravity
.. assisting in the unloading of adsorption media once the adsorption media is
fully saturated. The
generally horizontal position also provides a more convenient point of access
for operators to
load and unload the media. It is preferred that the one or more elongated
vessels are oriented
an oblique angle of between 10 and 30 degrees. This angle of orientation
provides an optimal
amount of gravity assistance in both the movement of production water through
the elongated
vessels and the loading and unloading of adsorption media.
[0017] While the adsorption media rejuvenation module will work with any
commercially
available standard kiln that can subject the adsorption media to heat, it is
prefen-ed that the kiln
Date Recue/Date Received 2020-08-14
4
used is a rotary kiln. A rotary kiln will be able to subject the adsorption
media to a heat
treatment with agitation until the contaminants undergo a phase change to
gaseous form. The
added agitation assists with the efficient removal of contaminants from the
adsorption media.
[0018] While different ways exist to move the contaminants in gaseous form
from the kiln
to the at least one cooler-condenser, it is preferred that at least one
compressor is used to thaw
contaminants in gaseous form from the kiln into the at least one cooler-
condenser. Use of a
compressor is advantageous as it will assist in the cooling and condensing of
the hot gaseous
contaminants.
[0019] While
the one or more elongated vessels in the adsorption media module may be of
a variety of materials, it is prefen-ed that the one or more elongated vessels
are of a non-
corrosive material. Some contaminants, such as hydrogen sulphide, are highly
corrosive. It is
further preferred that the non-corrosive material is a high-density
polyethylene polymer plastic
(HDPE). Use of a non-corrosive material will increase the life span of the
elongated vessels.
[0020] While
the adsorption media rejuvenation module can remove contaminants withjust
the application of heat in the kiln, it is preferred that an air source
provide limited amounts of
air to the kiln. It will be understood that excessive amounts of air can cause
an explosion, but
some air is desirable to facilitate oxidization and combustion required for
the effective removal
of contaminants from the adsorption media.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] These and other features will become more apparent from the
following description
in which reference is made to the appended drawings, the drawings are for the
purpose of
illustration only and are not intended to be in any way limiting, wherein:
[0022] FIG.
1 is a flow diagram of the process and system for recovering contaminants
from production water.
[0023] FIG. 2 is a perspective view of an adsorption media module of the
system for
recovering contaminants.
[0024] FIG.
3 is a side elevation view of a flow control assembly for the adsorption media
module of FIG. 2.
Date Recue/Date Received 2020-08-14
5
[0025] FIG.
4 is a side elevation view of a rotary kiln used as part of an adsorption
media
rejuvenation module of the system for recovering contaminants.
DETAILED DESCRIPTION
[0026] A system for removing contaminants from production water will now be
described
with reference to FIG. 1 through FIG. 4.
Structure and Relationship of Parts:
[0027] Referring to FIG. 1, a system100 for removing contaminants
fromproduction water
includes an adsorption media module 200, an adsorption media rejuvenation
module 300, and
a hydrocarbon contaminants recovery module 400.
[0028]
Referring to FIG. 2, adsorption media module 200 includes two elongated
vessels
202 containing an adsorption media (not shown) capable of adsorbing
hydrocarbons. The
Adsorption media is a combination of activated and bio carbon adsorption media
in granulated
form. The two elongated vessels 202 have a first end 206, a second end 208, a
water inlet 210
at a first end 206 and a water outlet 212 at a second end 208. There is also a
media inlet 214 at
first end 206. Media inlet 214 has a removable flange 213 and a valve
connection 215 for the
loading of adsorption media. The two elongated vessels 202 are in a generally
horizontal
orientation, and at an oblique angle of between 10 and 30 degrees relative to
a horizontal plane,
with first end 206 positioned above second end 208. The two elongated vessels
202 are placed
on a skid 217 for transport to well sites. The two elongated vessels 202 are
of a non-corrosive
high-density polyethylene polymer plastic (HDPE). Referring to FIG. 3, there
is a flow contni
assembly 218 controlling a flow rate of production water into water inlet 210
of two elongated
vessels 202. Flow control assembly 218 includes a primary filter 219, a
secondary filter 221,
and valves 220.
[0029]
Referring to FIG. 1, a de-contaminated water storage facility 500 is available
for the
storage of de-contaminated production water.
[0030]
Referring to FIG. 4, adsorption media rejuvenation module 300 includes a
rotaiy
kiln 302 for subjecting adsorption media to a heat treatment with agitation
until the
Date Recue/Date Received 2020-08-14
6
contaminants undergo a phase change to gaseous form. The source of the heat
generated by the
rotary kiln 302 is high voltage, three phase electricity. Referring to FIG. 1,
adsorption media
rejuvenation module 300 also includes an air source 304 for supplying air to
rotary kiln 302.
Rotary kiln 302 has a gas outlet 306 for the evacuation of the contaminants in
gaseous form.
[0031] Referring to FIG. 1, hydrocarbon contaminants recovery module 400
includes a
compressor 402 for drawing contaminants in gaseous form from the rotary kiln
302 through
gas outlet 306, a cooler-condenser 404 for condensing the contaminants in the
gaseous form to
a liquid fon'', and a storage container 406 for capturing the contaminants in
the liquid form.
[0032] Referring to FIG. 1, a disposal well 600 is available for the
disposal of the
contaminants in liquid form.
Operation:
[0033] Referring to FIG. 1, the process involves a first step of passing
production water
through adsorption media, which is a combination of activated and bio carbon,
at a controlled
flow rate in order to capture hydrocarbon contaminants. Referring to FIG. 2,
this is achieved
by operating the adsorption media module 200, which include two elongated
vessels 202.
Adsorption media is pumped in to elongated vessels 202 as a slurry through
valve connection
215 at media inlet 214, which is located at first end 206. Alternatively,
flange 213 may be
removed and dry adsorption media may be added pneumatically. The elevated
position of fist
end 206 above the second end 208, allows the adsorption media to slide down to
the second
end by the operation of gravity. Adsorption media is loaded into the two
elongated vessels 202
until the two elongated vessels 202 are completely filled. Once adsorption
media is loaded into
the two elongated vessels 202, adsorption media module 200 is ready for the
intake of
production water. Referring to FIG. 3, before production water is pumped into
adsorption
media module 200, the production water is passed through flow control assembly
218. In flow
control assembly 218, production water passes through primary filter 219 and
secondary filter
221, for the removal of particulate matter. Once production water passes
through flow control
assembly 218, the production water is then pumped into the two elongated
vessels 202 through
water inlet 210.
Date Recue/Date Received 2020-08-14
7
[0034] Referring to FIG. 3, the flow of water into the two elongated
vessels 202 is
controlled via flow control assembly 218. The flow rate should match the
ability of the
adsorption media to adsorb the contaminants. This is tied to time exposure.
Referring to FIG.
2, in the proto-type, elongated vessels 202 were 25 feet long. As the
production water flows
through the adsorption media in the two elongated vessels 202, contaminants
from the
production water are adsorbed by adsorption media. De-contaminated production
water then
flows out water outlet 212 to de-contaminated water storage facility 500 for
storage and reuse.
The flow rate was optimized by performing calculations and by testing
performed at water
outlet 212. If trace contaminants appear at water outlet 212, the flow rate is
too high.
[0035] Referring to FIG. 2, once adsorption media in one of the two
elongated vessels 202
becomes saturated with contaminants from the production water, the flow of
production water
through that elongated vessel 202 is stopped. Water is then pumped into the
elongated vessel
202 to turn the granular adsorption media into a slurry, which can be removed
through water
outlet 212 using a vacuum truck.
[0036] The two elongated vessels 202 allow for alteration in operation
between the two
such that the process of passing production water through adsorption media can
be a continual
process. An operator can keep the flow of production water running through one
elongated
vessel 202, while replacing the saturated adsorption media with fresh
adsorption media in the
other elongated vessel 202. Preferably, both of the two elongated vessels 202
is operated
simultaneously with a slightly offset operationschedule to allow for the time
required to change
out adsorption media. Doing so would provide for a continuous and high
capacity operation.
[0037] Referring to FIG. 1, the process then involves a second step of
subjecting adsorption
media to an agitation and heat treatment at temperatures of between 650 and
850 degrees
Celsius until the contaminants undergo a phase change to gaseous form. The
saturated
adsorption media is moved from adsorption media module 200 to the adsorption
media
rejuvenation module 300. Referring to FIG. 4, the saturated adsorption media
is loaded into the
rotary kiln 302. Once loaded into the rotary kiln 302, the rotary kiln 302
subjects the saturated
adsorption media to a direct heat treatment at temperatures of between 650 and
850 degrees
Date Recue/Date Received 2020-08-14
8
Celsius. Rotary kiln 302 agitates the saturated adsorption media through a
rotary mechanism.
Referring to FIG. 1, air inlet 304 adds a controlled amount of air to rotary
kiln 302 to assist
with the oxidization and combustion of contaminants. As the contaminants
undergo a phase
change to gaseous form and are liberated from adsorption media, the gaseous
contaminants are
evacuated from rotary kiln 302 via gas outlet 306. Once adsorption media is
fully de-
contaminated via this heat and agitation treatment, adsorption media is
unloaded from rotary
kiln 302 and cooled to room temperature. This de-contaminated adsorption media
is removed
from adsorption media rejuvenation module 300 and re-loaded back into
adsorption media
module 200 for re-use in the de-contamination of production water.
[0038] Referring to FIG. 1, the process involves a third step of
condensing the contaminants
in the gaseous form to a liquid form, and capturing the contaminants in the
liquid form. As the
contaminants undergo a phase change to gaseous form in rotary kiln 302, the
gaseous
contaminants are continuously evacuated from adsorption media rejuvenation
module 300 to
hydrocarbon contaminants recovery module 400 by compressor 402 through gas
outlet 306.
The gaseous contaminants are discharged into cooler-condenser 404 and are
condensed back
into liquid form. The liquefied contaminants are then captured in storage
container 406. The
recovered liquid contaminants in storage container 406 can then be refined and
reused, sold, or
disposed of safely into disposal well 600. It is important to note, that there
will be no
atmospheric discharge of the noxious contaminants.
[0039] In this patent document, the word "comprising" is used in its non-
limiting sense to
mean that items following the word are included, but items not specifically
mentioned are not
excluded. A reference to an element by the indefinite article "a" does not
exclude the
possibility that more than one of the element is present, unless the context
clearly requires that
there be one and only one of the elements.
[0040] The scope of the claims should not be limited by the illustrated
embodiments set
forth as examples, but should be given the broadest interpretation consistent
with a purposive
construction of the claims in view of the description as a whole.
Date Recue/Date Received 2020-08-14
