Note: Descriptions are shown in the official language in which they were submitted.
SYSTEM AND METHOD FOR OIL SANDS TAILINGS TREATMENT
[0001] m
FIELD
[0002] The present disclosure relates generally to treatment of oil
and gas tailings
and in particular, oil sands tailings.
BACKGROUND
[0003] Extraction and refining of oil, for example oil obtained from
oil sands, may
result in tailings that include, for example, solid, dissolved or suspended
pollutants. The
pollutants may be, for example, organic pollutants, such as hydrocarbon
mixtures. Examples
of hydrocarbon mixtures include bitumen, naptha, organic compounds like
naphthenic acids
(NAs); phenols; benzene, ethylbenzene, toluene, xylenes (BETX); polycyclic
aromatic
hydrocarbons (PAHs); oil & grease; and inorganic compounds, forexample Cl-,
S042-, Al, As,
Cr, Ca, Pb, Ni, Zn, and other metals. Usual loads of organic and inorganic
compounds confer
to tailings alkalinity (600-800 mg CaCO3/L), hardness (90-120 mg CaCO3/L), TDS
(1900-
2300 mg/L), TSS (<7000 mg/L), NAs (50-120 mg/L), BOD (10-70 mg02/L), COD (-350
mg
02/L), oil & grease (9-92 mg/L), Cu (0.002-0.9 mg/L), and Ni (0.006-2.8 mg/L).
[0004] A discussion of oil sands tailings can be found in: FTFC (Fine
Tailings
Fundamentals Consortium), 1995, "Advances in Oil Sands Tailings Research",
Alberta
Department of Energy, Oil Sands and Research Division, Publisher, and Devenny,
D. W., "A
Screening Study of Oil Sands Tailings Technologies and Practices", March 2010,
Alberta
Energy Research Institute.
[0005] These broad range of harmful pollutants found in tailings
streams pose a
significant risk to the environment and/or human health if left untreated.
Government
regulations often mandate that various organic, inorganic, chemical, and
microbial
components of a tailing stream must be treated before the tailing stream can
be discharged
to the environment.
- 1 -
Date Recue/Date Received 2020-08-07
[0006] It is desirable to provide a method and system for treating
the tailings to
attempt to remove, destroy, or both remove and destroy, as much of the
pollutants as
possible. Electrochemical methods and systems for treating sewage wastewater
are
discussed in PCT Applications: PCT/IB99/01276, PCT/CA2003/001780, and
PCT/CA2007/002037; and in U.S. Patent Application 12/905,350.
SUM MARY
[0007] According to one aspect of the present disclosure, there is
provided amethod
of treating tailings, the method includes: pre-treating the tailings;
electrolytically treating the
pre-treated tailings; in the electrolytically treated tailings, separating
solids from liquids; and
filtering the separated liquids to result in a filtrand and a filtrate
comprising the treated
tailings.
[0008] The method may additionally include electrolytically treating
the filtrate
comprising the treated tailings, or the separated liquids.
[0009] Pre-treating the tailings may include: screening the tailingsto
remove
substantially all particles greater than 1 mm; removing floating oils from the
tailings to result
in less than about 2 mg of floating oil per L of tailings; or both.
[0010] Electrolytically treating the pre-treated tailings may
include: applying a
continuously pulsed electrical signal to at least one of a pair of electrodes
submersed in an
aqueous liquid to generate bubbles of an oxyhydrogen-rich gas; and contacting
the pre-
treated tailings with the oxyhydrogen-rich gas bubbles.
[0011] The pulsed electrical signal may have a mark-space ratio of
between
approximately 1:1 and 10:1 and a pulse frequency of approximately 10Hz-250
kHz.
[0012] The aqueous liquid may be the pre-treated tailings.
[0013] The method may further include: separating the mryhydrogen-rich gas
from
the electrolytically treated tailings; and transporting the oxyhydrogen-rich
gas to a secondary
process. The secondary process includes production of energy in a fuel cell or
combustion
device.
[0014] Separating solids from liquids in the electrolytically treated
tailings may
include: coagulating the solids, coalescing the solids, precipitating the
solids, settling the
solids, flocculating the solids, or any combination thereof; and separating
the coagulated
solids, the coalesced solids, precipitated solids, settled solids, or
flocculated solids from the
liquids.
- 2 -
Date Recue/Date Received 2020-08-07
[0015] According to another aspect of the present disclosure, there
is provided a
system for treating tailings. The system includes: a pre-treatment system for
pre-treating the
tailings; an electrolytic treatment system for electrolytically treating the
pre-treated tailings; a
separation system for separating, in the electrolytically treated tailings,
separating solids from
liquids; and a filtering system for filtering the separated liquids to result
in a filtrand and a
filtrate comprising the treated tailings.
[0016] The system may further include: a recycling system to return
the treated
tailings filtrate or the separated liquids to the electrolytic treatment
system.
[0017] The pre-treatment system may include: a screening system to
remove
substantially all particles greater than 1 mm from the tailings; a skimmer to
remove floating
oils from the tailings to result in less than about 2 mg of floating oil per L
of tailings; or both.
[0018] The electrolytic treatment system may include: at least one
pair of electrodes
submersed in an aqueous liquid; and a source of a continuously pulsed
electrical signal
connected to least one of the electrodes to generate bubbles of an oxyhydrogen-
rich gas.
[0019] The pulsed electrical signal may have a mark-space ratio of between
approximately 1:1 and 10:1 and a pulse frequency of approximately 10Hz-250
kHz.
[0020] The aqueous liquid may be the pre-treated tailings.
[0021] The system may further include: a separator for separating the
oxyhydrogen-
rich gas from the electrolytically treated tailings; and a transporter for
transporting the
oxyhydrogen-rich gas to a secondary system. The secondary system may be a fuel
cell or a
combustion device.
[0022] The separation system may include: one or more systems for
coagulating the
solids, for coalescing the solids, for precipitating the solids, for settling
the solids, for
flocculating the solids, or for any combination thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Embodiments of the present disclosure will now be described,
by way of
example only, with reference to the attached Figures.
[0024] Fig. 1 is an illustration of reactions that may occur during
electrolysis;
[0025] Fig. 2 is a schematic of a method for treating oil and gas tailings;
and
[0026] Fig. 3 is an illustration of the chemical oxygen demand (COD)
concentration in
a liquid as a function of the number of electrolytic treatments.
-3-
Date Recue/Date Received 2020-08-07
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
DETAILED DESCRIPTION
[0027] Generally, the present disclosure provides a method and system
for
electrochemically processing tailings using electrolysis to attempt to remove,
destroy, or
both remove and destroy, pollutants. The tailings may be, for example,
tailings from oil
sands operations or tailings from other similar operations.
[0028] Embodiments herein are intended to allow pollutants to be
removed,
destroyed, or both removed and destroyed, at lower Hydraulic Retention Times
than in
conventional biological or physical-chemical systems. The process may reduce
the
amount of residual bio-solids, thereby reducing additional treatment or
disposal. Off gas
may be produced during treatment, and may be separated and purified. The
separated
and purified off gas may be, for example: sold, used to produce energy in a
fuel cell or
combustion device, used to produce energy to be sold back to a utility company
or
another user of electricity, consumed in the process, or any combination
thereof.
[0029] The tailings may comprise an influent tailing stream.
Alternatively, the
tailings may comprise an intermediate waste or wastewater stream such as
supernatant
or biosolids, for example, in the context of a larger wastewater treatment
system. In still
other examples, the tailings may include chemical processing effluent from an
oil cracking
process. Tailings may be subjected to preliminary processing steps, such as
oil
skimming, screening, grit removal, or any combination thereof. Oil skimming,
screening,
and/or grit removal may be particularly important when tailings comprises raw
wastewater
influent from oil sands operations.
[0030] Pre-treated tailings may be pumped between a set of electrodes
where
highly oxidative species, for example ozone, hydrogen peroxide, hydroxyl
radicals, or any
combination thereof, are generated. Alternatively, the set of electrodes may
be used to
generate the highly oxidative species separately from the pre-treated tailings
and then
subsequently mixed with at least a portion of the pre-treated tailings. The
mixture of
oxidative species produced may be controlled by modulating the input signal.
The mixture
of oxidative species may be selected in order to target specific pollutants.
[0031] Water molecules and other constituents in the liquid may be
split by the
electrodes into a mixture of hydrogen, oxygen, nitrogen, and traces of 002.
Fig. 1
illustrates reactions that may occur during electrolysis. Chemicals, for
example
phosphorous, and suspended solids may be coagulated, coalesced, precipitated,
settled,
flocculated, or any combination thereof. The oxidative species may oxidize
organic
matter. In such a manner, the method and system may reduce the amount of
organics in
the tailings, reduce toxicity, convert ammonia to nitrogen gas, reduce the
level of
- 4 -
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
pathogens in the tailings, or any combination thereof. A small fraction of the
original solids
in the raw tailings may remain after treatment and may be directly disposed.
[0032] The system may be designed as a continuous-flow, a batch-flow,
or a
recycling-flow system.
[0033] It is desirable for the tailings entering the system to be
substantially free of
floating oil, for example it is desirable for the tailings to have less than 2
mg of floating oil
per L of tailings. It is desirable for the tailings entering the system to be
substantially free
of particles larger than about 1 mm in size. The system and method may include
a
pretreatment to reduce the amount of floating oil, reduce the number of
particles larger
than about 1 mm in size, or both, before electrolytic treatment of the
tailings.
[0034] The system may include one or more blowers to dilute and vent
gas
produced by the system, for example H202, to the atmosphere. The system may
include
stainless steel components for gas exhaust, hydrogen gas sensors (for example
located
downstream from a gas-liquid separator), building fans, or any combination
thereof in
order to protect against any risk of hydrogen combustion. Because of the non-
biological
character of the solids, there is generally no need for digesters, therefore
eliminating the
production of CH4 or mercaptans.
[0035] The system and method may include multiple electrolytic
treatments,
where each electrolytic treatment is followed by settling and removing the
resulting solids.
Further, each electrolytic treatment may include multiple passes, for example
two passes,
through the electrodes before settling and removing the resulting solids.
[0036] In view of the above, the method of treating tailings includes:
pre-treating
the tailings; electrolytically treating the pre-treated tailings; in the
electrolytically treated
tailings, separating solids from liquids; and filtering the separated liquids
to result in a
filtrand and a filtrate comprising the treated tailings.
[0037] The method may additionally include electrolytically treating
the filtrate
comprising the treated tailings, or the separated liquids.
[0038] Pre-treating the tailings may include: screening the tailings
to remove
substantially all particles greater than 1 mm; removing floating oils from the
tailings to
result in less than about 2 mg of floating oil per L of tailings; or both.
[0039] Electrolytically treating the pre-treated tailings may include:
applying a
continuously pulsed electrical signal to at least one of a pair of electrodes
submersed in
an aqueous liquid to generate bubbles of an oxyhydrogen-rich gas; and
contacting the
pre-treated tailings with the on/hydrogen-rich gas bubbles. The pair of
electrodes may be
spaced less than 5 mm apart.
- 5 -
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
[0040] The pulsed electrical signal may have a mark-space ratio of
between
approximately 1:1 and 10:1 and a pulse frequency of approximately 10Hz-250
kHz.
[0041] The aqueous liquid may be the pre-treated tailings.
[0042] The method may further include: separating the oxyhydrogen-rich
gas from
the electrolytically treated tailings; and transporting the oxyhydrogen-rich
gas to a
secondary process. The secondary process includes production of energy in a
fuel cell or
combustion device.
[0043] Separating solids from liquids in the electrolytically treated
tailings may
include: coagulating the solids, coalescing the solids, precipitating the
solids, settling the
.. solids, flocculating the solids, or any combination thereof; and separating
the coagulated
solids, the coalesced solids, precipitated solids, settled solids, or
flocculated solids from
the liquids.
[0044] Similarly, the system for treating tailings includes: a pre-
treatment system
for pre-treating the tailings; an electrolytic treatment system for
electrolytically treating the
.. pre-treated tailings; a separation system for separating, in the
electrolytically treated
tailings, separating solids from liquids; and a filtering system for filtering
the separated
liquids to result in a filtrand and a filtrate comprising the treated
tailings.
[0045] The system may further include: a recycling system to return
the treated
tailings filtrate or the separated liquids to the electrolytic treatment
system.
[0046] The pre-treatment system may include: a screening system to remove
substantially all particles greater than 1 mm from the tailings; a skimmer to
remove
floating oils from the tailings to result in less than about 2 mg of floating
oil per L of
tailings; or both.
[0047] The electrolytic treatment system may include: at least one
pair of
.. electrodes submersed in an aqueous liquid; and a source of a continuously
pulsed
electrical signal connected to least one of the electrodes to generate bubbles
of an
oxyhydrogen-rich gas. The pair of electrodes may be spaced less than 5 mm
apart.
[0048] The pulsed electrical signal may have a mark-space ratio of
between
approximately 1:1 and 10:1 and a pulse frequency of approximately 10Hz-250
kHz.
[0049] The aqueous liquid may be the pre-treated tailings.
[0050] The system may further include: a separator for separating the
on/hydrogen-rich gas from the electrolytically treated tailings; and a
transporter for
transporting the oxyhydrogen-rich gas to a secondary system. The secondary
system
may be a fuel cell or a combustion device.
- 6 -
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
[0051] The separation system may include: one or more systems for
coagulating
the solids, for coalescing the solids, for precipitating the solids, for
settling the solids, for
flocculating the solids, or for any combination thereof.
[0052] One specific example of a method according to the present
disclosure is
illustrated in Fig. 2. Tailings (10) from oil and gas production are screened
and de-gritted
(12) to generate screenings (14). Oil (16) that floats is removed from the
screened and
de-gritted tailings at (18). The de-oiled tailings are again screened, using a
1-2 mm fine
screen (20), to generate fine screenings (22). The resulting de-oiled and
screened tailings
are electrolytically treated (24). In the particular method illustrated in
Fig. 2, the
electrolytic treatment uses an oxyhydrogen gas generator and implements a
water
dissociation technology, as discussed in greater detail below, generating
oxyhydrogen-
rich gas (26). Electrolytic treatment oxidizes organic matter present in the
de-oiled and
screened tailings.
[0053] The oxyhydrogen-rich gas (26) may optionally be separated and
purified.
The separated and purified off gas may be used for a secondary use (28). For
example, it
may be sold, used to produce energy in a fuel cell or combustion device, used
to produce
energy to be sold back to a utility company or another user of electricity,
consumed in the
process, or any combination thereof.
[0054] The electrolytic treatment (24) coagulates, coalesces,
precipitates and/or
.. flocculates chemicals and suspended solids, which are separated (30) from
the treated
tailings to generate solids (32). The solids (32) may be treated, for example
by
thermophilic aerobic digestion, to reduce the biological demand before
disposal.
Thermophilic digestion of biological agents may be effected at, for example: a
temperature of about 55 C to about 60 C for a period of about 10 days; or a
temperature
of about 50 for a period of about 5 days. In particular examples, the
thermophilic digestion
may be effected at about 25 C for about 4 to about 6 hours. This reduced time
and
temperature may be due to the electrolytic treatment reducing the biological
demand of
the tailings before the solids (32) are collected.
[0055] The effluent from the solids separation is filtered (34), using
for example
sand or granular activated carbon (GAC) to generate treated filtrate (36) and
filtrand (38).
The filtrand (38) may be additionally treated (40), for example by being
regenerated and
reused, or disposed through environmentally safe and cost effective processes.
Regeneration may be achieved, for example, by incineration of the filtrand
(38). Disposal
of the filtrand (38) may include, for example, washing and dewatering. The
screenings
(14), fine screenings (12) and/or the solids (32) may also be treated (step(s)
not shown)
- 7 -
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
and disposed through environmentally safe and cost effective processes. The
additional
treatment of the screenings (14), fine screenings (12) and/or the solids (32)
may include
washing and dewatering. The screenings (14), fine screenings (12) and/or the
solids (32)
may be treated together.
[0056] The treated effluent (36) and/or the effluent from the solids
separation may
be electrolytically treated more than once. For example, the tailings may be
electrolytically treated 2, 3, 4, 5, 6, 7, 8, 9, or more than 9 times by
recycling the treated
effluent and/or the effluent from the solids separation to the electrolytic
treatment system,
as illustrated in Fig. 2. The COD concentration in mg/L of the treated
effluent is illustrated
in Fig. 3 for untreated effluent (that is, where the electrolytic treatment
step = 0), as well
as for effluent that has been eletrolytically treated 1, 2, 3, 4, 5, 6, 7 and
8 times by
recycling the effluent from the solids separation system to the electrolytic
treatment
system.
[0057] The method and system are intended and expected to remove in
the range
of 80 to 98% of the pollutants in the tailings. The method and system are
intended and
expected to have a hydraulic retention time from 3 to 60 minutes. The method
and
system are intended and expected to have power requirements around 0.5 to 40
kWh/m3.
[0058] The method and system may destabilize colloidal particles and
increase
the settling velocity of the resulting particles. In some examples, the
electrolytically
treated tailings may be settled in 5 to 20 minutes, resulting in a clear
supernatant and
settled solids. The method and system can be controlled to generate a mixture
of
oxidative species suitably targeted to destabilize tailings having varying
compositions.
The settled solids may include 50 to 70% v/v of the water from added tailings.
The settled
solids may have water capillary suction times of less than 10 seconds and may
be
dewatered using, for example, sloped banks. Dried settled solids are typically
easier to
dewater and compact than solids produced by chemical or biological treatment.
The
quantity of water continuously released (i.e. not needing to be dewatered from
the solids)
is intended to be in the range of 30 to 50% in volume. Overall, the system and
method
are designed to remove organic contaminants and reduce toxicity of the
tailings input at
the same time that fine tailings are being precipitated.
[0059] The tailings are expected to have a chemical oxygen demand
(COD: an
indirect measurement of the amount of organic compounds) in the range of
40,000 mg/L.
After electrochemical (electrolytic) treatment, the COD is intended to be in
the range of
200 mg/L. After filtering, for example using granular activated carbon, the
COD is
intended to be in the range of 50 mg/L.
- 8 -
[0060] Table 1 provides a list of exemplary pollutants found in
tailings from oil sands,
and their resulting levels after electrolytic treatment. BOD (biological
oxygen demand) is an
indirect measurement of organic compounds that can be oxidized biologically.
Pollutant in mg/L Sample 1 Sample 2 Sample 3
Raw Treated Raw Treated Raw Treated
Benzene 92.9 <0.0005 0.014 <0.0005 <0.0005 <0.0005
Toluene 263 <0.0005 0.119 <0.0005 0.0013 <0.0005
Ethyl Benzene 39.3 <0.0005 0.111 <0.0005 <0.0005 <0.0005
Xylenes 360 <0.00015 0.7 <0.00015 0.0034 <0.00015
Methanol 16.8 27800 28.7 130
4-methyl-2-pentanone - <0.002 117 <0.0002 - <0.0002
COD 1750000 25 40000 19.4 260 132
BOD 12.5 11 122
Calcium 432 22.7 107 8.41 86.6 15.8
Chloride 10600 29.5 2590 29.3 841 182
Magnesium 81.4 16.7 14.5 12.6 18.3 13.5
Table 1
[0061] Electrolysis may be performed using an oxyhydrogen gas generator and
may implement a water dissociation technology, such as the kind disclosed in
U.S. Pat. Nos.
6,419,815 and 6,126,794 of Chambers, both issued to Xogen Technologies Inc.
(hereinafter
"the Xogen patents"). As described in the Xogen patents at columns 3-5, gas
generation
apparatuses in accordance with embodiments include electrode "cells" each
including two or
more spaced-apart electrodes adapted to be immersed in a working fluid
including water. In
the embodiments described herein, the working fluid comprises tailings or a
tailings stream.
The electrodes are preferably made of the same material. One electrode
material is stainless
steel for its low cost and durability, but it may be possible to use other
conductive metals. An
equal spacing between the electrodes is maintained and it is preferable to
minimize the
spacing between the electrodes. However, the spacing between the electrodes
cannot be
positioned excessively close because arcing between the electrodes would
occur. It has
been determined that a spacing of 1 mm or less is optimal spacing for
producing
oxyhydrogen-rich gas, but an increased spacing of up to approximately 5 mm may
work
effectively while being less subject to fouling due to accumulation of solids
between the
- 9 -
Date Recue/Date Received 2020-08-07
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
electrodes. A spacing above 5 mm may also be feasible, but tends to reduce the
output of
oxyhydrogen gas and increases power requirements.
[0062] It is preferable to include many pairs of electrodes (e.g.
dozens or
hundreds) within each cell. The electrodes can be almost any shape, but
preferably
comprise flat plates closely spaced and parallel to each other. Alternative
embodiments
may include coaxially aligned cylinders. Insulating spacers can be interposed
between
adjacent electrodes to maintain equal spacing between the electrodes and to
prevent
current leakage therebetween.
[0063] As further described in the Xogen patents, a high- frequency
pulsed direct
current (DC) electrical signal is applied to the electrodes. The pulsed signal
can be almost
any waveform and have a variable current level, voltage level, frequency and
mark-space
ratio (i.e., a ratio of the duration of a single pulse to the interval between
two successive
pulses). The source of power for the power supply may include a mains 110
volts or
batteries, such as 12-volt car batteries. For example, the power supply may
comprise two
12-volt batteries arranged in series to provide a 24-volt supply. For powering
a large-
scale gas generator (GG1) in a large tailings treatment system, a more complex
power
supply may be required for generating 24-volt pulsed DC signal having
sufficient power to
drive the large cells required. Alternatively, multiple smaller electrode
cells may be
provided for redundancy and spaced apart in a reaction vessel or other
reaction zone, in
which case the cells may be driven by simpler independent power supplies.
[0064] A controller is used in conjunction with the batteries or other
power source
to generate one of a variety of pulsed output waveforms, such as a square
wave, a saw
tooth wave, or a triangular wave, which can be applied to the electrodes. The
pair of
electrodes may be spaced less than 5 mm apart. At present, the best results
for
producing oxyhydrogen-rich gas have been obtained using a square wave. In one
embodiment a pulsed signal has a mark-space ratio of between approximately 1:1
and
10:1 and a pulse frequency of approximately 10Hz-250 kHz.
[0065] After initiation of the pulsed signal from the power supply,
the electrodes
continuously and almost instantaneously generate bubbles of oxyhydrogen-rich
gas from
water molecules in an interaction zone that extends between the electrodes and
slightly
beyond the edges of the electrodes. The generated bubbles are not bunched
around or
on the electrodes and thus readily float to the surface of the fluid in the
reactor vessel or
other reaction zone. Therefore, there is no need to add a chemical catalyst to
assist the
conduction of the solution or inhibit bubbles from bunching around or on the
electrodes.
-10-
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
Thus, many different kinds of tailing streams can be used as the working
fluid, as can
other sources of water, such as surface water and ordinary tap water.
[0066] Oxyhydrogen gas generator GG3 may be submerged in tailings
contained
in a reaction vessel and operated for an interval of from approximately 60
seconds to up
to approximately 10 minutes, then power to the gas generator GG3 may be shut
off. In
particular examples, the oxyhydrogen gas generator is operated for an interval
between
about 3 minutes and about 10 minutes. After an interval of operation of gas
generator
GG3, a substantial amount of solids may collect on the surface of the
tailings. While a
modest amount of solids may collect on the surface of the tailings during
operation of gas
generator GG3, a surprisingly large increase in floating solids occurs nearly
immediately
after de-energizing of gas generator GG3 and stopping of a recycle flow
through the
reaction vessel. De-energizing of gas generator GG3 and stopping of the
recycle flow
results in quiescent conditions within the reaction vessel, which allow for
unhindered
floatation of solids. An extracted gas floatation unit process includes one or
more cycles
each including the following steps: (1) operating the gas generator GG3
(typically by
applying a high-frequency pulsed electrical signal) for between approximately
60 seconds
and approximately 10 minutes, (2) de-energizing gas generator GG3, (3) waiting
until
solids collect on the surface of the fluid (typically between approximately 30
seconds and
2 minutes), and (4) removing the solids from the surface (by skimming the
surface, for
example). The cycles can be repeated continually until a desired amount of
solids has
been removed from the tailings.
[0067] Oxyhydrogen gas generator may be mounted on a frame that is
hung from
a set of floats so that the submergence of the oxyhydrogen gas generator is
maintained
at a desired level below the surface of the fluid. Alternatively, the
oxyhydrogen gas
generator may be mounted to a fixed lid or other fixed support for positioning
at a fixed
height in reaction vessel. Floats may also serve to seal the top of reaction
vessel. The
frame may be adjustable so that the submergence level of the gas generator can
be
adjusted independent of the depth of fluid in the reaction vessel.
[0068] Alternatively, the oxyhydrogen gas generator may be placed on a
pedestal
or other support so that it is positioned below the middle of the depth of
fluid in the
reaction vessel. Placement of gas generator low in the reaction vessel (or
other reaction
zone) increases the distance that bubbles of oxyhydrogen-rich gas must rise
through
fluid, thus increasing their residence time and probability of contacting a
solid particle or
other treatable molecule. Preferably, the oxyhydrogen gas generator may be
positioned
- 11 -
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
at least slightly above the floor of the reaction vessel to avoid buildup of
sediment and
sludge between the electrodes of the gas generator.
[0069] The oxyhydrogen gas generator may include a series of closely-
spaced
electrode plates that are oriented generally vertically and arranged such that
the spaces
between adjacent plates are open to the reactor contents at both the top and
bottom
edges of the plates. A pulsed electrical signal from a power source may be
provided to
the electrode plates via power transmission wires. The application of the
pulsed electrical
signal may cause water molecules in the fluid suspension to be dissociated in
an
interaction zone extending between the plates and slightly beyond the openings
between
the plates, to thereby form an oxyhydrogen-rich gas including hydrogen and
oxygen. The
oxyhydrogen-rich gas may collect in the interaction zone to form bubbles that
rise through
the fluid suspension between the plates and can then be collected at the
surface of the
fluid suspension under a gas containment lid. Because the aggregate density
(specific
gravity) of flocs in the fluid suspension is only marginally greater than 1.0,
the rising
bubbles may transport the flocs upward and into contact with the oxygen and
hydrogen in
the liberated gas bubbles and/or the atmosphere collected under the
containment lid.
[0070] In the process of generating oxyhydrogen-rich gas, heat is
generated
around the oxyhydrogen gas generator and the temperature of the fluid
suspension in the
reaction vessel may increase. A portion of the contents of the reaction vessel
may be
withdrawn on a continual and variable basis and recirculated through a heat
exchanger
via a feed/recirculation pump to maintain the temperature of the fluid
suspension at a
desired level for the specific application in question. In addition to
providing temperature
control, the recirculation loop may also provide a degree of positive mixing
in the reaction
vessel to help keep the solids in suspension and thus in a position to be
transported
upwards toward the surface of the fluid suspension or another contact zone
where the
solids are more likely to contact oxyhydrogen-rich gas. Sample ports may be
provided in
the recirculation line to allow samples of the solids to be collected and
analyzed for
various parameters in order to determine the degree of treatment that has been
achieved
at any point in time.
[0071] In the preceding description, for purposes of explanation,
numerous details
are set forth in order to provide a thorough understanding of the examples.
However, it
will be apparent to one skilled in the art that these specific details are not
required. The
above-described examples are intended to be exemplary only. Alterations,
modifications
- 12-
CA 02880227 2015-01-27
WO 2013/016821
PCT/CA2012/050513
and variations can be effected to the particular examples by those of skill in
the art
without departing from the scope, which is defined solely by the claims
appended hereto.
-13-
