Note: Descriptions are shown in the official language in which they were submitted.
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Title: SUBMERGED COMBUSTION DISPOSAL OF PRODUCED WATER
The present invention is related to and claims priority to previously filed,
co-pending U.S. Provisional Application No. 60/865,450, filed 13 November
2006,
U.S. Provisional Application No. 60/866,354, filed 17 November 2006, and U.S.
Provisional Application No. 60/883,226, filed 03 January 2007.
Field of the Invention
This invention relates to an apparatus for disposing of water at the maximum
rate and efficiency. More particularly, the present invention relates to a
water disposal
system including a sparger tube type submerged combustion apparatus, for
disposing of water produced, for example, from a hydrocarbon well.
Background of the Invention
Submerged combustion is a method of heating whereby hot products of
combustion are forced through a medium to heat the medium. The heat exchange
occurs directly between the hot products of combustion and the medium, which
may
be water or an aqueous solution. In a submerged combustion system, the hot
combustion products are generated by a flame fed by a combination of air and a
suitable fuel. The flame typically does not actually come into contact with
the
medium. This technology differs from conventional heat exchange methods such
as
immersion tube heating where the heat exchange is indirect from combustion
products to the tube and through the tube walls to the medium. In conventional
heat
exchange methods, the spent products of combustion are inefficiently exhausted
directly to the atmosphere with useable heat remaining, rather than being
efficiently
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exhausted through the medium and giving up all possible heat, as is possible
in
submerged combustion.
A problem which exists in hydrocarbon recovery operations, such as oil and
gas wells is the production of sometimes large quantities of water together
with the
desired hydrocarbons, which water must be disposed of in an economical and
environmentally friendly way. A great variety of apparatuses and methods have
been proposed for disposing of large quantities of water that cannot simply be
poured on the ground or into a waterway. Generally these methods have included
impoundment and evaporation, use for irrigation of crops, and in some cases
active
heating or conversion to steam. However, none of these methods efficiently
combine high rates of heat transfer from the fuel to the water, as needed to
achieve
the maximum evaporation rate at the maximum fuel efficiency.
Submerged combustion devices have been applied to the problem of heating
water, both for production of hot water per se and for other applications such
as
melting snow. The submerged combustion devices used in prior art systems often
employ a vertical combustor/weir style apparatus having a relatively small
coverage
area compared to the volume of water to be heated, in which the combustion
gases
are directed downwardly onto the liquid to be heated.
A weir type submerged combustion device includes two concentric vertical
tubes of relatively short length. The tubes are vertically displaced, with the
top and
bottom of the outer tube (the weir tube) being lower than the respective top
and
bottom of the inner tube (the combustion tube). This tube system is vertically
mounted and is partially immersed in the medium; usually about half the
vertical
length of the tubes are immersed. The bottom of the outer tube is located
above the
bottom of the medium container. In operation, the combustion products (hot
gases)
are directed downward against the surface of the medium in the inner tube. The
hot
gases are forced to pass downwardly through the medium, around the lower edge
of the inner tube and up through the medium in the space between the inner
tube
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and the outer tube. The hot gases entrain the medium and force it to rise in
the
space between the inner and outer tubes and then over the upper edge of the
outer
tube. At this point, the partially cooled gases escape upward and out of the
device,
while the entrained, warmed water flows downward on the outside of the outer
tube
and into the medium container thus mixing with the remainder of the medium.
The
only agitation of the medium is that provided by the water flowing into the
bottom of
the weir and out over the top edge of the outer tube, and so additional
agitation must
be provided, at additional capital and operational cost.
The weir type of submerged combustion apparatus has a number of
shortcomings, in that it fails to completely transfer heat from the combustion
gases
into the liquid to be heated and so is not optimally efficient. The weir type
of
submerged combustion fails to achieve complete agitation of the container, and
thus
does not provide sufficient agitation of the water to rapidly heat and
evaporate the
water deposited in the apparatus. In addition, the lack of complete agitation
results
in non-uniform temperature distribution in the water. Thus, additional
agitation must
be provided from an external mixing device. Without adequate agitation, a
problem
arises due to the non-uniform distribution of heat in the water. The weir type
of
submerged combustion is inefficient in transferring combustion heat to water
because the close contact of the flame with the water forms water vapor in the
combustion chamber. In addition, the full heat of combustion is exposed to
only a
small fraction of the total water. These effects combine to limit the water
evaporation rate into the apparatus to less than what could be had with full
agitation
and complete and uniform heat transfer.
In the absence of added agitation by an external mixing device, the needed
agitation of the water has been left to the often inadequate passive mixing
resulting
from the water flow through the weir. The lack of agitation directly results
in a
reduced rate of water evaporation and thus a loss in efficiency of fuel use as
well.
Other prior art systems include externally applied mechanical mixing devices,
thus
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requiring the input of additional energy as well as provision of the
additional
equipment.
Due to these problems, such systems for water evaporation have not been
widely used. Instead, collection in ponds for passive evaporation is often
relied
upon despite the adverse environmental effects.
The adverse environmental effects of such produced water have gained the
attention of governmental agencies, and have increased the importance of
finding
economical alternative methods for disposing of such unwanted produced water.
Complex systems such as that disclosed in U.S. Patent No. 6,971,238 have been
devised. While such systems may be good at disposing of the water in an
environmentally acceptable way, these systems are expensive to build and
expensive to operate, and cannot attain the maximum efficiency possibly
obtained
from the fuel used in the process.
An additional problem in the prior art has been the accumulation and
concomitant requirement for removal of sand, mud, salt and other suspended
and/or
dissolved solids from systems such as those described above. To avoid
accumulation of such materials, prior art systems have required that the
incoming
water be filtered prior to introduction into the system. Such filtering
introduces an
additional layer of complexity to the system, and adds to the capital and
operational
costs, as well as providing another source of possible operational
interruption as a
result of equipment breakdown or for required maintenance.
Removal of such debris is particularly problematical due to the wide variation
in size and type of debris. For example, such debris may include sand, gravel,
stones, wood, plastics of many shapes and sizes, finely divided organic and
inorganic particulates and organic materials such as asphalts and crude oil,
which
are either inherently present in the water or which are inadvertently
collected along
with the water. In prior water disposal systems, the entire system must be
shut
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down and the water drained out of the tank or other vessel in order to gain
access to
and remove the debris collected with the water, if it is not filtered out
initially.
In addition to debris, water produced from hydrocarbon wells often includes
various hydrocarbons in varying amounts. As the water is evaporated, these
hydrocarbons tend to accumulate and must also be collected and disposed of
properly.
Therefore, a need remains for an apparatus and method which will rapidly and
efficiently dispose of such unwanted produced water and provide for an
efficient
debris and accumulated hydrocarbon removal apparatus in association with the
water
disposal.
Summary of the Invention
In another embodiment, the present invention relates to a produced water
disposal apparatus including a container for receiving and holding produced
water; a
submerged combustion burner; and a debris removal mechanism.
In one embodiment, the present invention relates to a produced water disposal
apparatus including a container for receiving, heating and vaporizing produced
water;
a submerged combustion burner; and a debris removal mechanism.
In an aspect, there is provided a produced water disposal apparatus
comprising: a container for receiving and holding produced water; a feed water
line
providing produced water to the container; a burner having a combustion
chamber,
wherein at least a portion of the combustion chamber is submerged in the water
and
the submerged portion of the combustion chamber comprises a substantially
horizontal sparger tube having a plurality of exit ports along its length
through which
combustion gases emerge into, mix with, agitate and vaporize the water; and a
condenser to condense and recover vaporized water; a debris removal mechanism
comprising an auger; the container further comprises a v-shaped ending with a
cylindrical bottom having an inside diameter providing a clearance from an
outside
diameter of the auger.
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In another aspect, there is provided a produced water disposal apparatus
comprising: a container for receiving and holding produced water; a feed water
line
providing produced water to the container; a source of hot gas other than a
submerged combustion apparatus; a sparger tube operatively communicating with
the source of hot gas and through which the hot gas emerges into, mix with,
agitate
and vaporize the water; and the sparger tube positioned substantially
horizontal and
having a plurality of exit ports along its length; a condenser to condense and
recover
vaporized water, wherein the source of hot gas provides a gas at a temperature
and
in a volume sufficient to vaporize the water at a rate comparable to a system
including a submerged combustion burner; a debris removal mechanism comprising
an auger; the container further comprises a v-shaped ending with a cylindrical
bottom
having an inside diameter providing a clearance from an outside diameter of
the
auger.
In one embodiment, the debris removal mechanism comprises an auger.
In one embodiment, the sparger tube is branched in a side-arm configuration
or in a "Y" configuration, or a combination thereof.
In a further aspect, there is provided a method of disposing of produced
water,
comprising: providing produced water to a produced water disposal apparatus,
wherein the produced water disposal apparatus comprises: a container for
receiving
and holding produced water; a feed water line providing produced water to the
container; a burner having a combustion chamber, wherein at least a portion of
the
combustion chamber is submerged in the water and the submerged portion of the
combustion chamber comprises a substantially horizontal sparger tube having a
plurality of exit ports along its length; and a condenser; combusting fuel in
the
combustion chamber to form hot combustion gases; heating and agitating the
water
by directly contacting the water with the hot combustion gases exiting the
sparger
tube; and vaporizing the water; and condensing vaporized water in the
condenser
and recovering condensed water; removing debris from the produced water
disposal
apparatus with a debris removal mechanism comprising an auger; the container
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further comprises a v-shaped ending with a cylindrical bottom having an inside
diameter providing a clearance from an outside diameter of the auger.
In another aspect, there is provided a method of produced water disposal
comprising: providing produced water to a produced water disposal apparatus,
the
produced water disposal apparatus including a container, a feed water line
providing
produced water to the container, a submerged combustion burner, a
substantially
horizontal sparger tube having a plurality of exits ports along its length, a
condenser
and a debris removal mechanism comprising an auger; wherein the container
further
comprises a v-shaped ending with a cylindrical bottom having an inside
diameter
providing a clearance from an outside diameter of the auger; operating the
submerged combustion heating system to heat and vaporize the produced water in
the container; condensing vaporized water in the condenser and recovering
condensed water; and removing debris from the produced water disposal
apparatus
by means of the debris removal mechanism.
In one embodiment, an apparatus as described herein is used, except that
there is no submerged combustion system provided for heating the water to
evaporation. Instead, an alternative source of heat, such as the exhaust from
a steam
boiler, a diesel engine used for generating electricity, the exhaust from a
landfill
generator, or any other source of useful heat, may be used. In this
embodiment, the
system includes a source of hot gas, such as combustion gas exhausted from a
boiler, and the remainder of the apparatus is as described herein, including,
in
particular, a sparger tube submerged in the water. The hot gas is passed into
the
sparger tube and heats the water as described herein.
In one embodiment, the apparatus of the present invention is used as a
concentrator, to concentrate a solute by removing water as the solvent, and
thereby
obtaining the solute in concentrated form. The solute so recovered may be a
valuable
material in its own right, or it may be a material destined for disposal or
treatment, but
rendered easier to handle, cheaper and/or easier to dispose than when the
solute
was in the solvent.
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Thus, the present invention relates to a produced water disposal apparatus in
which water is disposed of by evaporation and which provides a high
evaporation rate
and high fuel efficiency. These benefits are attained by use of sparger tube
submerged combustion, in which the hot combustion gases produced by the burner
are brought rapidly, directly and intimately into contact with the water to be
disposed.
The hot combustion gases thereby both agitate a large portion or all of the
water and
obtain nucleate boiling to most efficiently transfer heat from the hot
combustion gases
to the water. Nucleate boiling provides much greater heat transfer from the
hot
combustion gases to the water than does conduction or convection heating.
In a further aspect, there is provided a method of concentrating a solute in
an
aqueous medium, comprising: providing an aqueous medium containing a solute to
a
water removal apparatus, wherein the water removal apparatus comprises: a
container for receiving and holding an aqueous medium; a feed water line
providing
produced water to the container; a burner having a combustion chamber, wherein
at
least a portion of the combustion chamber is submerged in the aqueous medium
and
the submerged portion of the combustion chamber comprises a substantially
horizontal sparger tube having a plurality of exit ports along its length; and
a
condenser; combusting fuel in the combustion chamber to form hot combustion
gases; heating and agitating the aqueous medium by directly contacting the
aqueous
medium with the hot combustion gases exiting the sparger tube; vaporizing the
aqueous medium and concentrating the solute; condensing vaporized water in the
condenser and recovering condensed water; and recovering the solute in a more
concentrated form by means of a debris removal mechanism comprising an auger;
the container comprises a v-shaped ending with a cylindrical bottom having an
inside
diameter providing a clearance from an outside diameter of the auger.
Accordingly, the present invention addresses and overcomes the problems of
the prior art produced water disposal apparatuses. Additional features and
benefits of
the invention will be understood from the following detailed description.
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Brief Description of the Drawings
Fig. 1 is a schematic side sectional view of a produced water disposal
apparatus in accordance with an embodiment of the present invention.
Fig. 2 is a schematic cross-sectional view of the produced water disposal
apparatus of Fig. 3 taken at line C--C of Fig. 1.
Fig. 3 is a schematic cross-sectional view of another embodiment of the
produced water disposal apparatus similar to that shown in Fig. 2.
Fig. 4 is a schematic cross-sectional view of another embodiment of the
produced water disposal apparatus similar to that shown in Fig. 2.
Fig. 5 is a schematic cross-sectional view of an embodiment of the sparger
tube which may be used in the produced water disposal apparatus, such as that
shown in Fig. 4.
Fig. 6 is a schematic side sectional view of a produced water disposal
apparatus in accordance with another embodiment of the present invention.
Fig. 7 is a schematic side sectional view of a produced water disposal
apparatus in accordance with yet another embodiment of the present invention.
Fig. 8 is a schematic end perspective view of a produced water disposal
apparatus in accordance with an embodiment of the present invention similar to
the
embodiment of Fig. 6.
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Fig. 9 is a schematic top plan view of a produced water disposal apparatus
in accordance with an embodiment of the present invention similar to the
embodiment illustrated in Fig. 6.
It should be appreciated that for simplicity and clarity of illustration,
elements
shown in the Figures have not necessarily been drawn to scale. For example,
the
dimensions of some of the elements may be exaggerated relative to each other
for
clarity. Further, where considered appropriate, reference numerals have been
repeated among the Figures to indicate corresponding elements.
Furthermore, it should be appreciated that the process steps and structures
described below may not form a complete process flow for disposing of produced
water. The present invention can be practiced in conjunction with water
handling,
treatment and processing techniques currently used in the art, and only so
much of
the commonly practiced process steps are included as are necessary for an
understanding of the present invention.
Detailed Description
As used herein, unless otherwise specifically stated, the term "produced
water" includes water produced from a hydrocarbon well, e.g., a gas or oil
well,
whether land-based or offshore, including water escaping or removed from the
well
at any stage of production, and further includes any other water from any
other
source, which water needs to be disposed of and cannot be simply poured on the
ground, flowed into a waterway, or otherwise put "down the drain" into a
sewage or
septic system, for reasons such as toxicity, governmental regulations or for
any
other reason. This definition thus includes water from sources such as
landfill runoff
and leachate, water from waste disposal sites such as landfills and waste
lagoons,
water from areas such as airports or parking lots that, once collected, cannot
be
disposed of by other conventional, simple methods such as noted above. It is
foreseeable that collection of runoff water from paved areas, such as parking
lots,
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may eventually be required by government regulation to be collected and
disposed
of and/or treated prior to release or discharge. Such water is also included
within
the scope of the "produced water" as used herein. In one embodiment, landfill
leachate or other water sources which may include a volatile toxic or
regulated
material may be excluded from this definition.
The present invention provides a method of produced water disposal capable
of disposing of the water at an optimum rate, i.e., tie amount of produced
water
disposed of per unit of time and energy input to the produced water disposal
apparatus is at or near the theoretical maximum. The rate of produced water
disposal is optimized by maximizing heat transfer from the burners to the
water by
means of a sparger tube submerged combustion apparatus. In one embodiment,
all water agitation is provided by the sparger. In one embodiment, the
apparatus
includes an insulated tank. In one embodiment, the apparatus includes the
ability
to remove debris from the apparatus. These features enable the produced water
disposal apparatus of the present invention to operate continuously and at the
maximum rate and efficiency. When the tank is insulated, the system is capable
of
evaporation efficiencies in the range of 1200 50 BTU per pound (2791 kJ/kg)
of
water removed and the resulting approximately 185 F (85 C) saturated plume
contains approximately one pound of released water vapor per pound of cooled
combustion gases, in accordance with psychometric principles of evaporation.
See,
e.g., Perry's Chemical Engineer's Handbook.
A first feature of the present invention is the use of a sparger tube for
distributing the submerged combustion burner gases evenly throughout the
produced water disposal container and for providing agitation of substantially
all of
the water in the conte,ner. The sparger tube provides a very high efficiency
of heat
transfer from the combustion gases to the water and also provides a high
degree of
agitation to the water. The sparger tube rapidly delivers the heat to the
total volume
of the water in the container via nucleate boiling heat transfer.
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A second feature is the provision for debris removal from the produced water
disposal apparatus. The present inventor has discovered a solution to the long-
standing problem of debris accumulation in any kind of produced water disposal
apparatus. In the prior art, to avoid the problem, the water for disposal was
required
to be filtered, a costly and time-consuming procedure, which also requires
additional
capital equipment. In one embodiment of the present invention, the water for
disposal is not filtered. In one embodiment, the water is not treated in any
way prior
to its introduction into the apparatus. In one embodiment, the debris removal
is by
means of an auger. The auger enables the produced water disposal apparatus of
the present invention to continue operating without the necessity of periodic
shutdowns to clean out the debris.
A third feature is use of insulation of the tank to retain the maximum amount
of heat in the water and to avoid radiative loss of the heat imparted to the
water.
This feature enhances the efficiency of the overall system and method.
An additional feature is a leveling device to maintain a constant level of
water
in the tank, so that a constant volume of water is maintained in the tank and
so that
the quantity of new water fed into the tank substantially equals the quantity
of water
evaporated, thus maintaining a steady-state condition which maintains
efficient fuel
use in the system.
Additional features of the present invention include one or more of: (a) use
of a demister to avoid release of droplets of liquid water from the apparatus;
(b) use
of a condenser to recover the evaporated water or to avoid release of a plume
of
water vapor or both; (c) use of a fiberglass tank to avoid corrosion; (d) use
of heat
treated metal system components, especially those exposed to both chlorides
and
heat, to avoid stress-corrosion cracking of the metal components; and (e) use
of a
"Y" or "W' shape sparger tube to allow for adjustments in the size of the
container,
particularly for enabling transport by truck and use in remote locations.
Various
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other features will become apparent to the skilled person on reading and
understanding the disclosure herein.
Another feature of the present invention is that the apparatus can be
operated with a source of hot gas, other than a submerged combustion system,
such as the exhaust from a diesel or gasoline powered generator, the exhaust
from
a boiler such as a steam generation boiler, exhaust from a landfill gas-
powered
generator, or other source of hot gases. Thus, in one embodiment, the system
can
be operated with what would otherwise be waste heat.
As a result of these features, the produced water disposal apparatus of the
present invention optimizes the amount of water disposed of per unit of energy
input
to the produced water disposal apparatus, thus providing the most efficient
possible
continuous operation.
Throughout the disclosure of the present invention, including both
specification and claims, in all numerical values, the limits of the ranges
and ratios
may be combined, and are deemed to include all intervening values. All
temperatures and pressures are at ambient except where disclosed to be
otherwise.
Furthermore, in the specification and claims all numerical values are deemed
to be
preceded by the modifier "about", whether or not this term is specifically
stated.
Sparger Tube
The apparatus of the present embodiment includes a sparger tube which
provides a high rate of direct heat transfer to the water from the combustion
gases,
such that the transfer is accomplished with minimum loss of the energy
provided by
the fuel. This highly efficient, high rate transfer of heat is accomplished by
means
of submerged combustion with a sparger tube for distributing the hot
combustion
gases to the water. With sparger tube submerged combustion, little or no loss
of
heat transfer is encountered, such as due to, e.g., film resistance resulting
from use
of a conventional heat exchange apparatus, or to inefficient mixing of the hot
gases
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with the water and subsequent escape of only partially cooled combustion
gases,
as happens with a weir-type submerged combustion system.
The apparatus of the present invention avoids the loss in efficiency of heat
transfer inherent in any device which does not include sparger tube-type
submerged
combustion heating. In sparger tube submerged combustion produced water
disposal apparatus, the heat generated by combustion of a fuel is transferred
directly into the water. The sparger tube provides both more efficient heat
transfer
to and agitation of the water. Incoming water is rapidly mixed with the water
already
in the container, and is rapidly and efficiently evaporated.
The use of sparger tube submerged combustion provides excellent fuel
efficiency at or near the maximum theoretically possible. The apparatus of the
present invention obtains excellent fuel efficiency in part because the hot
combustion gases transfer substantially 98% of the heat contained therein to
the
water through nucleate boiling. The lack of intermediate devices or barriers
between
the combustion chamber/hot combustion gases and the water or water means that
there is no heat loss and no slowing of the process of heat transfer from the
combustion gases to the water.
An additional feature of the present invention which further distinguishes it
from prior art devices is that the force of the hot combustion gases exiting
the
sparger tube and mixing with the water in the container provides highly
agitated and
thorough mixing of the hot combustion gases with the water for efficient
heating of
the water. Thus, no separate, additional apparatus for agitation of the water
needs
to be provided. The temperature and velocity of the hot, i.e., about 2000 F to
about
2600 F (about 1090 C to about 1427 C) combustion gases result in nucleate
boiling
and strong agitation of the water. The nucleate boiling provides maximum heat
transfer rate of heat from the combustion gases to the water. The strong
agitation
of the water results in uniform vapor release.
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A further feature of one embodiment of the present invention is the use of
internally recirculated water which is recirculated around the combustion
chamber
by means of an externally mounted pump. This water is applied to the outside
of the
portion of the combustion chamber which otherwise would not be submerged in
the
water container. This feature provides for the maximum amount of the
combustion
heat to be transferred into the water, as well as keeping the temperature of
the
combustion chamber walls to a relatively lower temperature.
In one embodiment, the sparger tube is formed in a "Y" configuration, in
which the distal or terminal portions of the tube, through which the hot gases
escape
to mix with and heat the water, is split into two tubes. In another
embodiment, the
sparger tube is formed in a "W' configuration, in which the distal or terminal
portions
of the tube, through which the hot gases escape to mix with and heat the
water, is
split into three tubes. Configurations with higher number of arms are also
possible,
but may not be practical. These embodiments are quite advantageous in reducing
the size of the apparatus for a given heat input, and, viewed another way, for
allowing a greatly increased heat input for a given apparatus. In one
embodiment,
by using a "Y"-shape sparger tube, the size of the apparatus can be reduced to
about one-half the size that would be needed for the same heat input. In
another
embodiment, by using a "Y"-shape sparger tube, the heat input can be increased
by a factor of about two, compared to the same apparatus with a single
straight
(unbranched) sparger tube. In one embodiment, by using a "W'-shape sparger
tube, the size of the apparatus can be reduced to about one-third the size
that would
be needed for the same heat input. In another embodiment, by using a "W'-shape
sparger tube, the heat input can be increased by a factor of about three,
compared
to the same apparatus with a single straight (unbranched) sparger tube.
In one embodiment, the sparger tube is branched in a side-arm configuration
or in a "Y" configuration, or a combination thereof. That is, the sparger tube
may be
in a "Y" configuration and each of the arms of the "Y" may include further,
laterally
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extending branches, as described herein. The "Y" or "W" or higher
configuration of
the sparger tube enables the length of the overall apparatus to be reduced
while
allowing for dispersal of the same amount of heat to the water. As will be
understood, using the "Y" or "W' configuration may necessitate in increase in
the
width of the container.
In one embodiment, the present invention includes insulation of the water
tank, which avoids loss of heat to the environment, thereby the maximum amount
of the heat of combustion is applied to evaporation of the water, and a
minimum
amount is lost.
In one embodiment, instead of a submerged combustion system, the
apparatus of the present invention is heated by a hot gas obtained, for
example,
from the exhaust of a diesel or gasoline engine, e.g., where the engine is
part of an
electric generator, or from a steam generating boiler, or from a landfill gas-
fired
generator. The exhaust from other systems can be used, as long as the hot gas
provided is sufficiently hot to obtain an adequate rate of water disposal. In
this
embodiment, the remainder of the apparatus is as described herein, including,
in
particular, a sparger tube submerged in the water. The hot gas is passed into
the
sparger tube and heats the water as described herein. In this embodiment,
there
is provided a produced water disposal apparatus including a container for
receiving
and holding produced water; a source of hot gas; a sparger tube operatively
communicating with the source of hot gas and through which the hot gas emerges
into, mix with, agitate and vaporize the water, in which the source of hot gas
provides a gas at a temperature and in a volume sufficient to vaporize the
water at
a rate comparable to a system including a submerged combustion burner. That
is,
in this embodiment, the source of hot gas should provide the hot gas at a
temperature and in a quantity or volume sufficient to vaporize the water to be
disposed at a rate that is within an order of magnitude of that provided by a
submerged combustion system as described herein.
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Use As a Concentrator
In one embodiment, the water disposal apparatus of the present invention
may be used as a concentrator, to remove water and thereby increase the
concentration of a solute. The solute may be the "gunk" contained in the
produced
water of a natural gas well, or it may be a more valuable commodity, such as
the
salts, ethylene glycol, propylene glycol or other materials used for deicing
objects
such as aircraft, streets, runways, etc. In many situations, a material of
importance
is found dispersed in a large volume of water, and needs to be separated from
the
water to obtain whatever value the material has, or to enable disposal of the
material
as other than a hazardous waste or pollutant. In the prior art, such
separation has
been carried out by less efficient, more costly methods, or the large volume
of water
had to be treated as a whole as a hazardous material. The present invention
provides a highly efficient water removal apparatus that essentially doubles
as a
concentrator of the material in the water. Thus, for example, in aircraft
deicing
operations, ethylene glycol and/or propylene glycol are often used. The
combination
of these materials with the snow or ice melted thereby result in the formation
of a
usually dirty, diluted form of these materials. Due to their possible toxicity
and
environmental hazard, the glycol-laden dirty water cannot be simply run into
the
nearest creek, river, lake or onto the ground. This water must be collected
and
somehow treated. By use of the apparatus of the present invention, the water
can
be removed and, if desired, recovered, and the material carried by the water
can
also be removed and collected either for further treatment and recovery or
disposal
or other waste handling.
Debris Removal
In one embodiment, the present invention provides for removal of debris from
the produced water disposal apparatus. In one embodiment, the produced water
disposal apparatus includes an apparatus for debris removal.
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In one embodiment, the debris removal is by an upwardly open-faced screw
auger saddled in a half pipe at the bottom of a substantially V-bottomed
vessel. The
half pipe may have about the same inside diameter as the outside diameter of
the
screw auger. The half pipe may be simply laid or attached in the bottom of a V-
bottomed vessel, or may be built into the structure, so that the V-shape
vessel has
a slightly rounded bottom-most portion. The V-bottom vessel is relatively
simple and
the screw auger can simply be placed inside it.
In one embodiment, the debris removal is by a screw auger saddled in a full
pipe having slots cut into the top of the pipe and communicating with a narrow
slot
in the bottom of a substantially V-bottomed vessel. The pipe may have about
the
same inside diameter as the outside diameter of the screw auger. The pipe may
be
simply attached in the bottom of a V-bottomed vessel, or may be built into the
structure, so that the V-bottomed vessel has a relatively narrow open slot
along the
bottom of the V, at which point the pipe is connected. As described in more
detail
below, the pipe may have a plurality of longitudinally extending slots
communicating
with the open slot along the bottom of the V.
In one embodiment, the V-bottom vessel simply has the screw auger placed
near the bottom of the V, and the screw auger is not inside any additional
pipe or
other container.
In an alternate embodiment, the debris removal is by a chain apparatus in
which the container is a flat-bottom vessel. The chain apparatus provides a
simple
mechanism for removal of debris which settles to the bottom of a flat bottom
container embodiment of the produced water disposal apparatus, in an
embodiment
in which the bottom is flat. The chain apparatus may have any suitable
configuration. In addition to the debris removal from the bottom of the
container,
any material which floats to the surface and collects there may be removed by
actively skimming or by providing a passive weir type skimmer.
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As noted above, water produced from hydrocarbon wells often includes
various hydrocarbons in varying amounts. As the water is evaporated, these
hydrocarbons tend to accumulate and must also be collected and disposed of
properly. As will be understood, hydrocarbons have a density lower than water,
so
will float on the surface of the water. As the hydrocarbons accumulate, they
can
interfere with efficient vaporization of the water. In one embodiment, the
apparatus
includes a weir over which the accumulated hydrocarbons can pass, to be
collected
in a separate section of the apparatus. In one embodiment, the weir is located
at
a level about 5-15 cm. above the normal water level, as maintained by a water
level
control system for normal operations. In this embodiment, when accumulated
hydrocarbons need to be removed, the water level can be adjusted upward so
that
the accumulated hydrocarbons pass over the weir. In another embodiment, the
weir
is located at or near the normal water level. In these embodiments, in
addition to
the hydrocarbons, there will be a quantity of water passing over the weir, and
it will
need to be returned to the main tank. In one embodiment, a separation device
and
a pump or other suitable means is provided for separating and returning the
water
to the tank. Other suitable means may be selected and provided for collecting
the
hydrocarbons.
Embodiments Illustrated in the Drawings
Referring now to Figs. 1, 2 and 3, there is shown a produced water disposal
apparatus 120 in accordance with an embodiment of the present invention. Fig.
1
is a schematic cross-sectional view of an embodiment of the produced water
disposal apparatus, taken at line D-D of Fig. 2. Fig. 2 is a schematic cross-
sectional
view of this embodiment of the produced water disposal apparatus, taken at
line C-C
of Fig. 1. Fig. 3 is a schematic cross-sectional view of another embodiment of
the
produced water disposal apparatus, similar to Fig. 2.
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Referring to Fig. 1, there is shown a produced water disposal apparatus 120
in accordance with an embodiment of the present invention. The produced water
disposal apparatus 120 includes at least one burner 122, a container 124, and
a
combustion chamber or tube 126. As illustrated in Fig. 1, the burner is
mounted
substantially vertically. In other embodiments, the burner may be mounted at
an
angle, ranging from the depicted substantially vertical to a substantially
horizontal
position. In one embodiment, the burner is mounted at an angle ranging from
about
30 degrees to about 60 degrees, and in another embodiment, the burner is
mounted
at about a 45 degree angle. Any such angle may be suitably selected. The
burner
122 may be a conventional multi-fuel burner. The burner 122 includes a fuel
line
128 through which fuel is provided to the burner 122, and an air line 130,
through
which combustion air is provided to the burner 122. Suitable blower, fan or
other
air-providing apparatus may be used to provide the combustion air. When the
fuel
is burning, a flame 132 is directed into the submerged portion of the
combustion
chamber 126. As noted above, in another embodiment, two or more burners may
be included in a single apparatus 120. The container 124 contains water 134.
The
water 134 is the water for disposal, e.g., the produced water.
The burner used in the present invention may be operated on any of several
different fuels. The burner may use untreated wellhead gas, natural gas, LP
gas,
propane, butane, diesel oil, kerosene, gasoline, heating oil, or other
hydrocarbon
fuel. In one embodiment, the burner of the present invention is operated on
propane. For environmental reasons, a fuel such as propane, butane, natural
gas
or LP gas may be preferred. For mobile applications, No. 2 diesel fuel may be
preferred, particularly when the vehicle operates on the same fuel. In one
embodiment, the produced water is from a petroleum well, such as a gas well,
and
the fuel used in the burners is the petroleum, e.g., wellhead gas, obtained
directly
from the well. In one embodiment, the wellhead gas is not treated prior to its
use
as fuel for the burner of the present invention. In one embodiment, the
wellhead gas
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is treated to remove one or more of carbon dioxide, water, sulfur, natural gas
liquids,
oils or other condensates. Since the natural gas liquids and oils, at least,
are
combustible, in one embodiment, these are not removed from the wellhead gas
when
it is used as the fuel. In one embodiment, the wellhead gas is treated to a
degree
required to convert it to a pipeline quality gas. In one embodiment, the
wellhead gas
is treated with an "iron sponges" apparatus, as known in the art. The "iron
sponge"
primarily removes sulfur compounds (such as hydrogen sulfide, mercaptans and
sulfides) to "sweeten" the gas, but may also remove some water, when present.
In
one embodiment, the wellhead gas is treated according to the methods disclosed
in
U.S. Patent No. 4,435,371, both in the background section and in the detailed
disclosure of the invention.
In one embodiment, the produced water disposal apparatus of the present
invention is operated with hot gases obtained from a source other than the
submerged combustion burner described herein. In one such embodiment, the
apparatus is operated with combustion gases obtained from any high-temperature
operation, such as a boiler flue, engine exhaust, a steam turbine in an
electrical
generation facility, combustion gases in a landfill-gas fueled generator, or
any source
of waste heat in which the waste heat-carrying gas has a temperature of at
least
about 700 F (at least about 370 C). Of course, the higher the temperature of
the
waste heat-carrying gas, the better, since it is the total heat content that
is important,
and more concentrated heat is better in that a smaller volume is needed to
obtain a
given quantity of heat.
Each burner 122 is mounted on the apparatus 120 is a position in which the
combustion chamber is at least partially submerged in the water 134 in the
container
124, as illustrated in Fig. 1. The combustion chamber may be water-jacketed as
shown in Fig. 1 and described in more detail below. In one embodiment, the
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combustion chamber is oriented at an angle of about 450 to horizontal, as
shown in
Figs. 6 and 7 and described in more detail below.
The apparatus 120 further includes at least one sparger tube 136 connected
to each burner 122 and combustion chamber 126. The sparger tube 136 is
completely submerged in the water 134. Other mounting configurations of the
burner 122 and the combustion tube 126 may be used as needed, and are within
the scope of the present invention. However, the most efficient operation is
obtained when at least a substantial portion of the combustion chamber 126 and
all
of the sparger tube 136 are submerged in the water 134. The sparger tube 136
should be mounted horizontally.
As the fuel is consumed, the combustion flame 132 emanates from the
burner 122 into the combustion chamber 126, and generates hot combustion gases
138. The hottest part of the combustion gases 138 obviously are near the flame
in
the combustion chamber 126. As the hot combustion gases move away from the
flame 132, heat is transferred to the water surrounding the submerged
apparatus
and the sparger tube 136. The heat transfer is primarily via holes in the
sparger
tube, as illustrated in Figs. 1-3. Some amount of heat will also be
transferred by
conduction through the walls of the combustion chamber and sparger tube, but
the
primary heat transfer is from the combustion gases exiting the sparger tube,
as
shown in the drawings.
In one embodiment, shown in Figs. 1 and 3, the sparger tube 136 includes
additional, laterally extending sparger tube arms 284. The arms 284 extend
laterally, horizontally, outward from the main sparger tube 136.
In one embodiment, shown schematically in Figs. 4 and 5, a water disposal
apparatus 420 in accordance with another embodiment of the present invention
includes a "Y" configured sparger tube. As shown in Fig. 4, the apparatus 420
includes a sparger tube 436 is formed in a "Y" configuration, in which the
distal or
terminal portions of the tube 436, through which the hot gases escape to mix
with
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and heat the water, is split into two tubes 436A and 436B. Fig. 4 is a view
similar
to that shown in Fig. 2, and the components thereof having the same reference
numerals are substantially the same as those shown in Fig. 2. Although a "Y"
configuration in the apparatus 220 in Fig. 3 is not shown separately, such a
combination may also be used and is within the scope of the invention.
Similarly,
the sparger embodiment of Fig. 3 may be used with any other embodiment of the
present invention.
Fig. 5 is a schematic top plan view of the sparger tube 436, showing an
embodiment in which the sparger tube 436 has a "Y" configuration in the distal
ends
436A, 436B of the sparger tube, similar to the sparger tube 436 shown in Fig.
4.
The exact configuration of the "Y" configured sparger tube may be adjusted as
needed for a particular application or use. Thus, in various embodiments, the
sparger tube may be branched in a side-arm configuration or in a "Y"
configuration,
or a combination thereof. Although not shown, in the combination, the sparger
tube
is in a "Y" configuration and each of the arms of the "Y" include one or more
laterally
extending branches, as described herein in the embodiment shown in Figs. 1 and
3, except that the sideways branching is on the arms of the "Y".
In one embodiment, the produced water disposal apparatus 120 further
includes a recirculation pump 140 and a transfer line 142 which pumps a
portion of
the water 134 into a contact space 144 surrounding the outside of the
combustion
chamber 126, then over a weir 146 and back into the main body of the water
134.
As illustrated in Fig. 1, the recirculation pump and/or the motor driving the
recirculation pump may be externally mounted. While it is possible the
recirculation
pump and/or the motor driving it could be mounted within the water container,
it
would be subjected to the high temperature of the heated water, which could be
detrimental to the pump and electric motor operating it. In one embodiment,
the
motor is externally mounted and the recirculation pump is within the confines
of the
container, in the water. This pumping of a portion of the water around the
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combustion chamber 126 keeps the combustion chamber relatively cool and allows
transfer of some heat from the hot combustion gases 138 passing through this
portion of the burner 122 to the water 134 in the contact space 144. Provision
of
this additional contact space 144 also prevents loss of radiant heat from the
portion
of the combustion chamber 126 which is not actually submerged, i.e., below the
liquid level of, the water 134 in the container 124. The remainder of the
combustion
gases 138 pass through an area reduction or transition zone 148 into the
sparger
tube 136. The sparger tube 136 includes a plurality of exit ports 150. The hot
combustion gases 138 pass through the exit ports 150 to be mixed with, to
transfer
heat to, and to agitate the water 134. The combustion gases exiting the exit
ports
150 are schematically depicted in Figs. 1-3 by the dashed-line arrows
emanating
from the ports 150. In one embodiment, the apparatus 120 does not include the
additional contact space 144.
As shown in Fig. 1, each sparger tube 136 is mounted such that its
longitudinal axis is oriented generally horizontally. In the illustrated
embodiments,
the exit ports 150 are disposed on the lower side of the sparger tube 136 and
of the
outwardly extending arms 284, so that the hot combustion gases 138 are forced
to
pass in a radially downward direction in exiting from the sparger tube 136 and
arms
284, thus providing maximum contact with the water 134. In one embodiment, the
exit ports 150 are in the form of a plurality of slits. In another embodiment,
the exit
ports 150 may be in the form of holes, e.g., round or elliptically shaped
openings,
rather than slits. In the embodiment shown in Fig. 1, the exit ports 150 are
placed
on the lowest portion of the sparger tube 136. In other embodiments, the exit
ports
150 may be placed elsewhere on the sparger tube 136, so that the combustion
gases 138 would pass radially outward to the side and down or simply to the
side.
While it is possible to have these or other orientations of the exit ports
150, such
orientations may provide less thorough contact between the hot combustion
gases
138 and the water 134 in the container 124, and therefore may provide less
efficient
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heat transfer to and less agitation of the water. For this reason, these
embodiments
are less preferred than embodiments in which the exit ports 150 provide a
downwardly oriented exit from the bottom of the sparger tube 136. Viewed from
the
side, downwardly oriented includes any orientation that is below the
horizontal plane
across the sparger tube.
The hot combustion gases 138, by the time they arrive in the sparger tube
136, may have a temperature in the range from about 800 C to about 1650 C. In
one embodiment, at least a portion of the hot combustion gases 138 in the
sparger
tube 136 may have a temperature in the range from about 1200 C to about 1500
C.
In one embodiment, at least a portion of the hot combustion gases 138 in the
sparger tube 136 have a temperature of about 1400 C.
As the hot combustion gases 138 pass from the sparger tube 136 through the
exit ports 150 into the water in the container 124, the temperature of the
combustion
gases 138 rapidly drops as the heat content of these gases is transferred to
the
water 134 via nucleate boiling. As the combustion gases 138 mix with and give
up
their heat to the water 134, the temperature of the combustion gases drops to
about
the temperature of the water 134. During this process, water will be vaporized
and
mixed with the cooled combustion gases to form the saturated exhaust effluent
which is expelled via a duct 158, by which the produced water is disposed of
to the
atmosphere as a vapor.
As shown in Fig. 1, the produced water disposal apparatus 120 further
includes a level control device 178 including a water level sensor 180. The
level
control device 178 is mounted so that the sensor 180 is in contact with the
water
134, in order to provide water level data to a flow controller 182. The flow
control
valve 182 is programmed to control the flow of water into the container, as
delivered
by a water feed line 184. The flow control valve 182 may include, e.g., a
bypass
valve, in which a relatively constant flow of water is provided, and the flow
control
valve 182 operates to allow a sufficient portion of the flow needed to
maintain a
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constant level to enter the container and the remainder to be returned to the
source.
Under the control of the control device 178, the flow control valve 182 allows
an
appropriate amount of water to pass through the water feed line 184 to
maintain the
water level in the tank 124 at a substantially constant level. As will be
recognized,
such a system allows for a relatively constant pump operation, a relatively
constant
line pressure, and therefore the most economical operation with a constantly
operating water feed pump.
Referring now to Fig. 2, which schematically illustrates a cross-sectional
view
of the produced water disposal apparatus 120 shown in Fig. 1, taken along line
C-C
in Fig. 1, the invention is further described.
Referring now more specifically to Fig. 2, in one embodiment, the produced
water disposal apparatus 120 includes a sloped bottom section 268. The sloped
bottom section 268 facilitates the movement of mud, precipitated solids and
any
debris towards the downwardly extending portion 270 of the bottom of the
produced
water disposal apparatus 120, in which the debris removal mechanism is
located.
Referring still to Fig. 2, as described with respect to Fig. 1, hot combustion
gases 138 pass from the sparger tube 136 through the exit ports 150 and mix
with
the water 134. The hot combustion gases 138 mix with the water 134 in the
container 124. The cooled combustion gases 138 (shown by the dashed lines
emerging from the slits 150 in the bottom of the sparger tube 136 in Fig. 2),
together
with water vapor, pass up through the medium, and exit the apparatus 120 into
the
surrounding ambient air through an exhaust duct or port 158, which is
described in
more detail below.
As shown in Fig. 2, in one embodiment, the container 124 may be mounted
on support legs 172. The support legs 172 may be conventional tank support
legs,
formed of, e.g., I-beams or channel. In one embodiment, the entire produced
water
disposal apparatus is mounted on the legs 172. In one embodiment, the legs 172
are attached to each other by horizontally disposed, ground-contacting skids
174.
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In one embodiment, the skids 174 are elevated by feet 176 or other suitable
means
for providing access for a lifting device. In one embodiment, the lower end of
the
legs 172 are affixed to the bed of a truck (not shown). The truck bed may be
in a
flatbed truck or a semi-trailer truck. In one embodiment, the entire produced
water
disposal apparatus is carried on a mobile vehicle. In one embodiment the
mobile
vehicle also includes water collection means, such as a sump pump. In one
embodiment, the produced water disposal apparatus 120 is mounted on springs or
other shock- and/or vibration-absorbing devices, or these may be included as
an
integral part of the legs 172. The springs may be useful because submerged
combustion apparatus may generate harmonic vibrations which the user may wish
to damp in order to avoid the vibration.
As schematically shown in Figs. 1-3, the produced water disposal apparatus
includes the vapor exit port 158, which functions as an exit port for the
evaporated
water/combustion gas mixture to escape from the produced water disposal
apparatus 120. The exit port 158 may be any appropriate size. For example, the
port 158 may be generally conical, actually truncated conical, and a height as
required to direct the water vapor plume away from the apparatus. The
configuration should be such that its flow velocity does not carry water,
spray,
droplets, etc., out of the apparatus. Ideally, only water vapor and combustion
gases
exit the apparatus via the exit port 158. The exit port 158 may be
appropriately
configured. The truncated conical configuration acts to improve the flow of
water
vapor and combustion gases from the container 124. The exit port 158, and the
apparatus 120 generally, may include a demister system and/or an exhaust
blower
and/or a condenser system, as may be needed according to the location of the
apparatus 120 and/or according to governmental or other regulations. In one
embodiment, the evaporated water passes into a condenser system, in which the
water vapor is condensed into the liquid state. The liquid water thus
collected is
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generally free of contaminants and can be disposed of by simply running the
stream
into a natural body of water, such as a stream, river, lake or ocean.
As schematically shown in Figs. 1-3, in one embodiment, the produced water
disposal apparatus includes a clean-out mechanism which comprises a debris
removal mechanism 240. The debris removal system may be either intermittently
or continuously operated. As used herein, the term "debris" includes mud,
sand,
precipitated solids (introduced into the apparatus as either dissolved or
suspended
solids or otherwise), tarry materials from, e.g., a hydrocarbon well, and any
actual
particulate debris that may be inadvertently introduced into the apparatus. As
used
herein, the term "debris removal mechanism" refers to any bulk conveyor
suitable
for use with the present invention, as described herein. In one embodiment,
the
debris removal mechanism comprises an auger 240, described in more detail
below,
which is particularly well adapted to the V-shape bottoms depicted in Figs. 1-
3. In
an embodiment in which the tank 124 has a flat bottom, the debris removal
mechanism includes an appropriate mechanism, such as a drag chain, as known
in the art of debris or sludge removal.
A debris removal mechanism, such as the auger 240, is most useful for the
purpose or removing debris (as defined herein) from the produced water
disposal
apparatus 120. Since varying amounts of debris may be entrained in the water
received by the apparatus 120, the removal prevents buildup of such debris.
Referring now to Figures 1-3, there are shown two embodiments of a
produced water disposal apparatus 120 and 220 in accordance with the present
invention. The embodiments illustrated Include an auger-type debris removal
device
240. The auger debris removal device 240 includes spiral blades or flights
242, as
shown in the Figures. The auger debris-removal device 240 is shown in Fig. 2
in a
V-shaped bottom 268, sloping down to a round bottom 270 in which the auger 240
operates. In this embodiment, the round bottom 270 may be fabricated from a
half-
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pipe, having an inside diameter appropriate to the outside diameter of the
flights 242
on the auger 240.
Referring now to Fig. 3, there is shown a produced water disposal apparatus
220 in accordance with another embodiment of the present invention. The
apparatus shown in Fig. 3 is similar to that shown in Fig. 1 in that it
includes the
outwardly extending arms 284 on the sparger tube 136, and is similar to that
shown
in Fig. 2, except in the bottom of the tank. In the embodiment shown in Fig.
3, the
apparatus 220 include a V-shaped bottom 268 similar to that in Fig. 2, sloping
down
to a relatively narrow orifice 272 communicating with a substantially closed
round
bottom 274 in which the auger 240 operates. In this embodiment, the round
bottom
274 may be fabricated, for example, from a pipe having a plurality of
longitudinally
extending sections removed, and having an inside diameter appropriate to the
outside diameter of the flights 242 on the auger 240.
In one embodiment, a pipe is used, e.g., having an outside diameter ranging
from about 6 inches to about 12 inches (about 15 to about 30 cm), or larger,
in
which a plurality of longitudinally extending sections, for example, sections
having
a length about 2 inches by about 10 inches (about 5 cm x 25 cm), spaced apart
every 1-3 inches (about 2.5-7.5 cm), along the length of the pipe. In this
embodiment, the pipe would be welded to the lower portion of the V-shape
bottom,
with the slots in the pipe opening into the tank 134. In this embodiment, the
auger
is mounted inside the pipe as described herein.
In the embodiment shown in Fig. 3, the auger is substantially more isolated
from the remainder of the tank 124 than in the Fig. 2 embodiment. The
remainder
of the apparatus 220 shown in Fig. 3 is substantially similar to the
embodiments
described with respect to Figs. 1 and 2. Although not shown, the embodiment of
the
sparger 136 including the outwardly extending arms 284 may be used with the
embodiment shown in Fig. 2, or with any other embodiment of the present
invention.
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Referring again to Fig. 1, the auger 240 is rotated, e.g., by an electric
motor
244 (or other suitable driver) as a suitable rotational velocity. The auger
240
operates by rotating with the spiral blades or flights 242 advancing the
debris
towards an end portion 246. In the embodiment illustrated in Fig. 1, the
apparatus
120 further includes a second auger 250 which is disposed in an external tube
252
and is rotated by a second electric or other motor 254. The auger 250 is in
operative communication with the end portion 246 and thereby with the first
auger
240. The second auger 250 moves debris (as defined herein) to and discharges
it
out an exit chute 256, where it may be collected as appropriate to the nature
of the
debris.
In the embodiment shown in Fig. 1, the auger 240 is horizontally mounted,
and is operatively coupled to or transmits collected debris to a second auger
250,
which lifts the collected debris above the water line. In one embodiment, the
second
auger 250 is substantially similar to the auger 240, having flights and
rotating so as
to move collected debris toward an exit port. In the embodiment shown in Fig.
1, the
second auger 250 is mounted in the external tube 252. In another embodiment,
not
shown, the second auger 250 may be mounted inside the container. Other
suitable
arrangements may be used for removing debris. For example, where the quantity
of debris is expected to be low, the auger 240 may be omitted, the debris
allowed
to collect, and the apparatus thereafter shut down and manually cleaned.
Referring now to Figs. 6-9, additional embodiments of the water disposal
apparatus of the present invention are described. In the embodiments shown in
Figs. 6, 7 and 9, the combustion chamber is oriented at an angle of about 450
to the
horizontal. While other non-right angles may be used, the angle of about 45
to the
horizontal provides a good combination of features. In general, the height and
length of the apparatus are directly affected by the angle of the combustion
chamber. For a given capacity of the combustion chamber and water disposal,
when the combustion chamber is vertically oriented, i.e., at 900 as in Fig. 1,
the
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overall height of the apparatus is greater than when the combustion chamber is
oriented at an angle such as 45 as in Fig. 6, but the overall length is
greater at the
45 orientation. Thus, there is a trade-off between height and length based on
orientation of the combustion chamber. In accordance with one embodiment of
the
invention, the increased length engendered by the 45 orientation is mitigated
by the
use of the "Y" or "W' shape sparger tube, in combination with the 45
orientation.
In this embodiment, there is obtained a combination in which the entire unit
can be
carried on a highway-capable truck within legal limits for vehicle height,
while
minimizing the overall length. The angle of the combustion chamber should be
great
enough that the water remaining in the container does not escape through the
combustion chamber when the unit is shut down.
In the drawings in Figs. 6-9, the views shown may include a combination of
cross-sectional views and perspective views. It is intended that the drawings
are to
illustrate the important features of the embodiments, and it is believed that
any
person of skill in the art can readily understand what is intended to be
depicted,
even with the "combination" views.
Fig. 6 is a schematic side sectional view of a produced water disposal
apparatus 620 in accordance with another embodiment of the present invention.
As
shown in Fig. 6, similar to the embodiments described above, this embodiment
of
the produced water disposal apparatus 620 includes a burner 622, a container
624
for holding the water to be disposed, a combustion chamber 626, a substantial
portion of which is submerged in and/or is surrounded by the water to be
disposed.
The burner 622 is fed by a fuel line (not shown in Fig. 6), an air line 630
fed, in this
embodiment, by a blower 630A mounted nearby. The fuel and air are combusted
in the combustion chamber 626, forming a flame 632 forming hot combustion
gases
that are directed into the water 634 and dispersed into the water 634 by the
sparger
tube 636. As in the other embodiments, the hot gases exiting openings in the
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sparger tube 636 heat the water for disposal by nucleate boiling, and transfer
heat
to the water at very high efficiency.
In the embodiment illustrated in Fig. 6, the water vapor produced in the water
disposal apparatus exits the container 624 via a duct 658. In one embodiment,
the
duct 658 is equipped with a mist reduction device 656, to prevent the escape
of
liquid water droplets from the apparatus. Such liquid water droplets might
contain
the undesirable components from which the water is intended to be separated,
thereby defeating the purpose of the device. Thus, in some embodiments, the
mist
reduction device 656 is included. The mist reduction device 656 may include a
screen, baffles or some type of honeycomb structure or other structure
presenting
a tortuous path to the exiting water vapor, thereby preventing carryover of
liquid
water droplets. In the embodiment shown in Fig. 6, the water vapor produced by
the
water disposal apparatus 620 is simply allowed to escape into the surrounding
atmosphere. Since it is substantially pure water, such release is
not of
environmental concern. Alternatively, the condensed water can be collected and
reused, with or without further purification, as may be needed.
In the embodiment illustrated in Fig. 6, a level sensing device 660 is
included.
The level sensing device may be, for example, an ultrasonic level detector, or
it may
be a float-type device. The level sensing device 660 is operatively connected
to a
level control device 662, which may be operated to control the liquid level in
the
container 624. The level control device 662 may be any suitable such device
known
in the art. The level control device 662 may be connected to a flow control
valve
664 and to a pump 666, mounted to feed incoming water to the container 624.
In the embodiment illustrated in Fig. 6, a debris removal apparatus 640 is
included. The debris removal apparatus 640 may be any one of the debris
removal
apparatuses described herein. In one embodiment the debris removal apparatus
640 is an auger, as described above. In the embodiment illustrated in Fig. 6,
the
debris removal apparatus 640 feeds the collected debris through a debris exit
port
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642 and into a debris container 644. The debris collected in the container 644
may
be disposed of as appropriate, for example, by confinement, by sequestration
or by
disposal in a suitable landfill. If the debris contains a sufficient quantity
of hazardous
waste, it may have to be confined or sequestered, or otherwise treated to
remove
the hazardous waste. As will be recognized, one of the important features of
the
present invention is the significant reduction in volume of material that must
be
treated, e.g., from thousands of gallons of liquid is obtained a few pounds of
solid
waste.
In the embodiment illustrated in Fig. 6, the feed pump 666 and flow control
valve 664 control the flow of incoming water for disposal into a feed line
668. In this
embodiment, the feed line 668 feeds the incoming water for disposal to a
jacketed
space 670 mounted around the burner 626. By use of this, the temperature of
the
walls of the combustion chamber can be controlled, and the incoming water can
be
heated. By use of the jacketed space 670, the inner walls of the combustion
chamber can be kept at a temperature within acceptable limits, e.g., at
temperatures
at which the material can both retain its strength and provide a significant
amount
of heat transfer to the incoming water. In the absence of the jacketed chamber
670
being filled with water, if the combustion chamber wall was formed of metal,
it would
likely soften and lose its strength. If the combustion chamber wall was formed
of a
refractory material, less heat transfer would be possible. In one embodiment,
a
substantial portion of the heating and vaporization takes place in the
jacketed space
670. The pre-heated water and vapor exit the jacketed space 670 through a line
672, which feeds the preheated water and vapor into the container 624. In one
embodiment, about 30% of the total heating takes place in the jacketed space
670.
In the embodiment illustrated in Fig. 6, the produced water disposal
apparatus 620 is mounted on a skid 674. The skid 674 allows the apparatus to
be
more easily transported on a flat-bed truck or by rail, and to be moved across
the
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ground to a desired location simply by dragging the apparatus with a suitable
vehicle.
Fig. 7 is a schematic side sectional view of a produced water disposal
apparatus 720 in accordance with yet another embodiment of the present
invention.
In the embodiment illustrated in Fig. 7, the apparatus 720 is substantially
identical
to the apparatus illustrated in Fig. 6, although not all of the components are
shown
with reference numerals and not all of the components described with respect
to Fig.
6 are shown. However, it is intended that the embodiment of the apparatus 720
includes all of the components described above with respect to Fig. 6.
The embodiment illustrated in Fig. 7, in addition to all of the components
described with respect to Fig. 6, further includes a condenser 780 mounted
with
respect to a vapor exit duct 758. The duct 758 is substantially similar to the
duct
658, and may include a mist reduction device as well, but differs in that it
is
connected to the condenser 780. The condenser 780 may be any type of
condenser known in the art. In the embodiment illustrated in Fig. 7, the
condenser
780 includes a coil 782. The coil 782 includes a coolant inlet 784 and a
coolant
outlet 786, through which a suitable coolant, such as cold water, is passed.
The
coolant may be re-cooled by any known method, such as a dry cooler or other
method.
By use of the condenser 780, water vapor exiting the apparatus 720 is
condensed into liquid water, which may be collected via a condensed water exit
port
788. When the apparatus is properly operated, the water condensed in the
condenser 780, like the water vapor exiting through the duct 758, is
substantially
pure and may be used for most any ordinary use or simply disposed of into a
suitable waterway or by pumping into the ground. In some situations, the
produced
water disposal apparatus of the present invention may be used in a remote area
where sources of water are limited. Thus, the availability of large quantities
of liquid
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water may be of significant value, and this apparatus is capable of providing
such
large quantities.
Although a particular condenser 780 is shown in Fig. 7, any known condenser
can be used. For example, a tube and shell condenser (similar to that shown)
may
be used. As another example, a "reverse sparger" may be used, in which a
sparger
such as that illustrated and described herein is submerged in a suitable body
or
container of water, so that the water vapor produced by the water disposal
apparatus of the present invention can be re-condensed into the body or
container
of water. The use of a condenser may be desirable in locations at which a
plume
is not desirable or is not allowed, such as at or near an airport.
In one embodiment, not shown, the duct 758 (or any other duct described
herein) may be equipped with an auxiliary fan. The auxiliary fan may be used
to
help "push" the water vapor out of the duct into the atmosphere or into a
condenser.
That is, when a condenser is used, the pressure drop between the container and
the
ambient atmosphere may be increased to such a level that the pressure inside
the
container becomes sufficiently high that the container may easily develop
leaks. Use
of the auxiliary fan helps to mitigate any such pressure drop, and thereby
acts to
"push" the water vapor into the condenser. In one such embodiment, the
auxiliary
fan adds some atmospheric air to the water vapor. Such addition may be useful
to
help cool and begin to condense the water vapor into liquid water, as well as
to
increase its velocity moving through the duct.
Fig. 8 is a schematic end perspective view of a produced water disposal
apparatus 820 in accordance with an embodiment of the present invention
similar
to the embodiment of Fig. 6, and including a "Y" shape sparger tube such as
shown
in Fig. 5. The embodiment illustrated in Fig. 8 is intended to include any and
all
elements of the present invention, but only some are described here. In the
embodiment illustrated in Fig. 8, the apparatus 820 includes a container 824
which
contains water for disposal 834. The apparatus 820 further includes a
combustion
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chamber 826, which feeds into a sparger including a first sparger tube 836A
and a
second sparger tube 836B, arranged in the "Y" configuration described herein.
The
sparger tubes 836A and 836B are mounted to a manifold 836M, which both
supports the sparger tubes and divides the combustion gases between the two
sparger tubes. The embodiment illustrated in Fig. 8 further includes a duct
858
similar to that described above for Figs. 6 and 7. As shown in Fig. 8, the
apparatus
820 may be mounted on a skid 840.
Fig. 9 is a schematic top plan view of a produced water disposal apparatus
920 in accordance with an embodiment of the present invention similar to the
embodiment of Figs. 6 and 8, including a "Y" shape sparger tube such as shown
in
Fig. 5. The embodiment illustrated in Fig. 9 is intended to include any and
all
elements of the present invention, but only some are described here. In the
embodiment illustrated in Fig. 9, the apparatus 920 includes a container 924
which
may contain water for disposal (not shown). The apparatus 920 further includes
a
combustion chamber 926, which feeds into a sparger including a first sparger
tube
936A and a second sparger tube 936B, arranged in the "Y" configuration
described
herein. The sparger tubes 936A and 936B are mounted to a manifold 936M, which
both supports the sparger tubes and divides the combustion gases between the
two
sparger tubes, similar to the embodiment illustrated in Fig. 8.
Since the apparatus of the present invention is likely to encounter a number
of corrosive elements while in use, and in particular, salt and other
chemicals used
in drilling mud, as well as mud and minerals dissolved from any holding tank
in
which the water is stored, the apparatus may be manufactured from a corrosion
resistant material, such as stainless steel, aluminum, appropriately painted
mild
steel, fiberglass or other suitable materials. The paint used for mild steel,
or for any
of the other materials, should be a paint that is resistant to both high
temperatures
and corrosive, e.g., salty or mineral-rich, aqueous solutions. For example,
paints
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used for ships may meet the requirements for such a system. The paint may be
appropriately selected by those of skill in the art.
Method of Produced Water Disposal
The present invention further relates to a method of disposing of produced
water. In one embodiment, the method of produced water disposal includes steps
of providing water to a produced water disposal apparatus, the produced water
disposal apparatus including a container, a submerged combustion heating
system
and a debris removal mechanism; operating the submerged combustion heating
system to heat the produced water in the container; and, as needed, removing
debris from the produced water disposal apparatus by means of the debris
removal
mechanism. In one embodiment, the submerged combustion burner includes a
sparger tube for distributing hot combustion gases to and for agitating the
water, as
described above.
The method of produced water disposal, in one embodiment, includes steps
of providing produced water to a produced water disposal apparatus, wherein
the
produced water disposal apparatus includes: a container for holding and
receiving
water; a burner having a combustion chamber, wherein at least a portion of the
combustion chamber is submerged in the water and the submerged portion of the
combustion chamber comprises at least one sparger tube; combusting fuel in the
combustion chamber to form hot combustion gases; heating and agitating the
water
by directly contacting the water with the hot combustion gases exiting the
sparger
tube; and thereby creating a mixture of saturated water vapor and cooled
combustion gas which exits the apparatus, e.g., in a plume.
In one embodiment, the method further includes removing from the produced
water disposal apparatus any debris (as defined herein) which may find its way
into
the apparatus. In one embodiment, the removing step is carried out with a
debris
removal mechanism, as described above. In one embodiment, the feed water
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provided to the apparatus is primarily laden with dissolved solids, minerals
or
organic materials such as tar, and with suspended solids, such as mud. If the
water
has been retained in an impoundment, the pumps that move the water to the
apparatus will generally have some screening or filtering apparatus, to
prevent
damage to the pump from stones or gravel. Of course, these dissolved and
suspended solids accumulate in the tank and need to be removed. In other
embodiments, the removing step is carried out by using other known means for
removing debris or solid matter from the bottom of a container filled with
liquid, such
as an auger. Such other methods may also include manually removing or washing
out the debris, and may entail first emptying the tank of the water otherwise
contained therein.
The method may be carried out with the apparatus mounted on a truck, for
example. The truck may be equipped with a pump, including the necessary
apparatus for straining and providing the produced water to the produced water
disposal apparatus. The produced water disposal apparatus has been described
above in detail. In one embodiment, the apparatus may be mounted on a skid, so
that it can be transported by truck or other suitable vehicle. In one
embodiment, the
height of the apparatus is kept to a minimum so that, when mounted on a truck
or
other vehicle, whether permanently mounted or mounted on a skid carried by the
vehicle, the total height of the apparatus is within legal limits. For
example, in many
areas, the maximum legal limit for vehicle height is 13.5 feet (about 4.1
meter). This
limitation may be met, for example, by mounting the submerged combustion
burner
at a suitable angle away from the vertical mounting illustrated in Fig. 1. For
example, the submerged combustion burner may be mounted at about a 45 degree
angle, as shown in Figs. 6 and 7.
In one embodiment, the burner is fired to heat the water to a temperature at
which it will quickly evaporate in accordance with known psychrometric
principles.
In one embodiment, the burner is fired to heat the water to a temperature at
which
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it will quickly evaporate, as suggested above, in one embodiment in the range
from
about 80 C to about 100 C, in another embodiment, in the range from about 83 C
to about 90 C, in another embodiment, and in one embodiment, about 84 C to
about
87 C. The evaporated water may be simply vented to the atmosphere or fed to a
condenser and collected.
The produced water disposal apparatus of the present invention may be a
self-contained unit, including a vehicle, fuel supply, electrical controls,
etc., as
needed for fully independent operation. The invention is not limited by the
means
by which it may be transported. In one embodiment, the produced water disposal
apparatus is operated at the site of the oil or natural gas production site,
i.e., at a
producing gas well site, such as on land or, possibly, on an offshore
production rig.
In one embodiment, the container 124 has a V-shape bottom 268 leading to
a clean-out port, with or without an auger 240. The V-shape bottom may be used
to collect debris for removal through the clean-out port. In one embodiment,
the
clean-out port may be equipped with the auger 240 or some variation thereof
for
removing debris from the bottom of the container 124 through the clean-out
port,
which may be, for example, at or adjacent the location of the end portion 246
in the
embodiment shown in Fig. 1.
Although the invention has been shown and described with respect to certain
embodiments, equivalent alterations and modifications will occur to others
skilled in
the art upon reading and understanding this specification and the annexed
drawings.
In particular regard to the various functions performed by the above described
integers (components, assemblies, devices, compositions, steps, etc.), the
terms
(including a reference to a "means") used to describe such integers are
intended to
correspond, unless otherwise indicated, to any integer which performs the
specified
function of the described integer (i.e., that is functionally equivalent),
even though
not structurally equivalent to the disclosed structure which performs the
function in
the herein illustrated exemplary embodiment or embodiments of the invention.
In
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addition, while a particular feature of the invention may have been described
above
with respect to only one of several illustrated embodiments, such feature may
be
combined with one or more other features of the other embodiments, as maybe
desired and advantageous for any given or particular application. Therefore,
it is to
be understood that the invention disclosed herein is intended to cover such
modifications as fall within the scope of the appended claims and equivalents
thereof.
39
