Note: Descriptions are shown in the official language in which they were submitted.
LOW STEAM CONSUMPTION HIGH SMOKELESS CAPACITY WASTE GAS FLARE
[0001] Continue to [0002].
BACKGROUND OF THE INVENTION
[0002] The present invention relates to an improved flare apparatus and
more specifically
to an efficient steam-assisted flare apparatus.
[0003] Steam assisted flares are used in refinery and petrochemical
plants for the
combustion of high volume releases of waste gases during interruptions of
normal plant
operation. The "smokeless" capacity is an extremely important operating
parameter. High
quantities of high pressure steam is used to entrain atmospheric air and force
the mixing of
the air with the waste gases. The greater the quantity of air mixed per pound
of steam injected
with the waste gases the higher the achievable smokeless capacity.
[0004] Flare apparatus for burning and disposing of combustible gases
are well known.
Flare apparatus are commonly mounted on flare stacks and are located at
production,
refining, processing plants and the like for disposing of flammable waste
gases or other
flammable gas streams which are diverted for any reason including but not
limited to venting,
shut-downs, upsets and/or emergencies. Flare apparatus are extremely important
in the event
of plant emergencies such as fire or power failure and a properly operating
flare system is a
critical component to prevent plant disruption in any of the above-mentioned
or other
circumstances.
[0005] In one example of an illustration of "traditional" prior art high
capacity steam
assisted flare design, the waste gas flow enters at the bottom of the flare
tip through a 60 inch
diameter waste gas connection (conduit). The flare tip is 9 to 10 feet in
diameter. There are
numerous 8 inch diameter nozzles that extend through the wall of the flare tip
near the base
then vertically to the discharge end of the tip. Attached to the inlet of the
nozzle is a "venturi
mixer". Steam injection nozzles are located at the inlet end of the venturi
mixer. The high
pressure steam injection entrains atmospheric air that travels through the
nozzle and is
injected into the waste gas that travels from the waste gas inlet at the
bottom of the tip
- 1 -
CA 3075057 2021-09-13
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
through the space around air nozzles to the discharge the end of the tip. Only
a small portion
of the required combustion air flows through the nozzles. The remainder of the
required
combustion air flows up around the outside of the flare tip. At the discharge
end of the flare
tip there is the second set of steam nozzles that are used to force the air
into the waste gas
stream.
100061 There are several shortcomings for this design. First, the
relatively small 8 inch
diameter nozzles severely limit the quantity of the air that can be entrained
by the steam.
Secondly, the steam flow and waste gas flow are essentially parallel which
reduces the
mixing efficiency. And finally, the waste gas has a tendency to flow up
through the center of
the tip instead of spreading uniformly across the tip diameter. This causes
higher
concentrations of waste gas in the center of the tip resulting in incomplete
combustion that
produces smoke.
100071 It is generally desirable that the flammable gas be burned
without producing
smoke and typically such smokeless or substantially smokeless burning is
mandatory. One
method for accomplishing smokeless burning is by supplying combustion air with
a steam jet
pump, which is sometimes referred to as an eductor. Combustion air insures the
flammable
gas is fully oxidized to prevent the production of smoke. Thus, steam is
commonly used as a
motive force to move air in a flare apparatus. When a sufficient amount of
combustion air is
supplied, and the supplied air mixes well with combustible gas, the steam/air
mixture and
flammable gas can be smokelessly burned. In a typical flare apparatus, only a
fraction of the
required combustion air is supplied using motive force such as blower, a jet
pump using
steam, compressed air or other gas. Most of the required combustion air is
obtained from the
ambient atmosphere along the length of the flame.
[0008] One type of known steam-assisted flare apparatus comprises a
generally
cylindrical gas tube into which flammable gas is communicated. Lower steam is
communicated through a plurality of steam tubes at an inlet and is forced to
negotiate a bend
in the steam tube, which causes a pressure drop. At the bend, the steam tubes
are redirected
so that they are parallel with the outer cylinder. Center steam is injected
into the center of the
gas tube so that flammable gas and steam pass upwardly through the outer tube
and is mixed
with steam that exits the lower steam tubes. At the upper end or exit of the
gas tube, steam
injectors direct steam radially inwardly to control the periphery of the
mixture exiting the gas
tube, and the steam/air and gas mixture is ignited. The center steam is
provided to ensure
- 2 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
burning does not occur internally in the gas tube. Internal burning is
typically seen at low gas
flow rates such as purge rates, and is aggravated by cross wind, capping
effects caused by the
upper steam, and if the purge gas has a lower molecular weight than air. A
purge rate is
typically the minimum gas flow rate continuously flowing to the flare to
prevent explosion in
the flare stack.
100091 Another type of steam-assisted flare uses only center and upper
steam injectors,
and works in a similar fashion. The steam-assisted flares described herein may
accomplish
smokeless flaring. However, such flare apparatus may require more steam per
waste gas than
other steam-assisted flare types, especially at larger sizes; additionally,
they may create an
excessive amount of noise. The noise from the lower steam can be muffled,
while the noise
from the upper steam is difficult or impractical to muffle due to its vicinity
to the flare flame.
A muffler for the lower steam not only adds to the costs, but also increases
the wind load of
the flare stack, resulting in increased flare stack costs. Due to the high
cost of steam and the
piping and flare stack structure associated with delivering the steam, it is
desirable that less
.. steam be utilized to achieve smokeless burning. Thus, there is a need for
an improved flare
apparatus and methods for smokelessly burning combustible gases with air to
lessen the noise
and to increase the efficiency whereby more fuel may be burned without added
steam.
100101 Under low-flow operating conditions, steam is often added to
maintain smokeless
combustion, more with higher-wind conditions; however, due to regulatory
requirements that
the combined steam and waste gas mixture remain above 270 Btu/SCF, extra
assist gas,
commonly methane, must additionally be added to maintain smokeless combustion.
With
many steam-assisted flares, the steam and steam/air mixtures are introduced to
the waste gas
fairly uniformly, whereas the waste gas can exit the flare non-uniformly with
higher wind,
requiring higher steam and/or assist gas utilities to maintain smokeless
combustion. Thus,
.. there is a need for an improved flare apparatus to consume reduced steam
and/or assist gas
utilities under low-flow conditions, regardless of the wind conditions.
SUMMARY OF THE INVENTION
100111 In one embodiment, the invention provides a steam flare
comprising a waste gas
cylinder connected at an upper portion of said waste gas cylinder to a
plurality of extensions
.. that extend away from a center of said waste gas cylinder, wherein each of
the extensions
contain a plurality of flare gas conduits, and a steam tube is located in each
of the flare gas
- 3 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
conduits. The steam flare may have a ring at a top portion of said flare gas
conduit and above
a top portion of said steam tube. The steam flare may additionally have a
singular or plurality
of flow-restricting cones in some section of the flare gas conduit below the
conduit exit. The
flare gas conduit may be a tube having a cylindrical configuration or other
configuration such
as a square, rectangular, oval or complex configuration. The steam tube may be
a single tube
having branches that extend into each of said flare gas conduits. The steam
exit may be a
singular orifice or plurality of orifices directly vertical or at an angle.
The ring may contain
perforations or other surface features. The transition from the waste gas
cylinder to the waste
gas equipment may be completely horizontal, at a certain slope, curved in some
direction, or
a combination of two or more of these features. The cap of the waste gas
cylinder may
involve a flat plate, a cone, a smaller concentric cylinder, or a combination
of two or more of
these features.
100121 In another embodiment, the invention is a process of operating a
steam flare
comprising sending a waste gas stream through a waste gas cylinder to a
plurality of flare gas
conduits while sending a stream of steam through a tube wherein said tube
extends into said
flare gas conduit, mixing said waste gas stream and said steam and then
causing a flame to
burn as a resulting mixture of said waste gas stream, said steam and oxygen in
outside
ambient air. There may be a ring at an upper portion on a waste gas tip of the
flare gas
conduit that comprises perforations or other surface features to direct
mixture of said steam
and said waste gas. The steam flare may have a singular or plurality of
velocity seals or flow-
restricting cones in some section of said flare gas conduit below the conduit
exit to reduce
atmospheric air backflow into the flare gas extensions, additionally reducing
the level of
assist gas and/or steam required to maintain smokeless combustion under low-
flow operating
conditions. The steam exit may involve an orifice directly vertical or
multiple orifices at an
angle to increase mixing of the steam, surrounding atmospheric air, and waste
gas and
additionally increase the velocity of the waste gas stream while reducing the
level of
atmospheric air backflow at low flow rates through partial steam-capping of
the flare gas
conduit, reducing the level of assist gas and/or steam required to maintain
smokeless
combustion under low-flow operating conditions. The flare gas conduit may have
a
configuration selected from the group consisting of cylindrical, square,
rectangular, oval and
complex shapes. The transition from the waste gas cylinder to the waste gas
extension may be
completely horizontal, at a certain slope, curved in some direction, or a
combination of these
- 4 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
features to reduce the pressure drop through the tip so as to not require
increased nominal tip
size with higher structural requirements; in addition, this improves
structural integrity of tip
by reducing stress from thermal growth due to combustion within tip. The cap
of the waste
gas cylinder may involve a flat plate, a cone, a smaller concentric cylinder,
or a combination
of these features, to reduce the stresses from thermal growth, increasing the
structural
integrity of the apparatus, and result in better flow distribution within the
flare apparatus,
resulting in acceptable pressure drop. The invention also addresses the
situation where
atmospheric air ingress into the tip mixes with waste gas and assist gas and
combusts within
the tip, thereby heating the tip and reducing equipment life; therefore,
reducing level of air
ingress is important to maximizing equipment life at low-flow operating
conditions. In
addition, the invention provides advantages in the low amount of steam that is
needed with
less than 0.20 lbs steam used per pound of propane waste gas. All of the steam
that is injected
internally to the waste gas before exposure to surrounding atmospheric air.
The steam imparts
mixing and momentum transfer to said waste gas and said surrounding
atmospheric air. The
invention also provides advantages under low-flow conditions, requiring
reduced steam
and/or assist gas to maintain smokeless combustion and increase equipment
life.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Fig. 1 is an isometric perspective of a top portion of a steam
flare.
[0014] Fig. 2 is a view of the steam flare including a waste gas
cylinder and tube for
steam.
[0015] Fig. 3 is a cutaway upper portion of the steam flare.
[0016] Fig. 4 shows an isometric view of two flare enclosure conduits.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention delivers smokeless combustion while
utilizing less than
0.20 lbs steam per lb of propane waste gas stream while requiring no steam for
cooling and
minimal steam for warming (less than 0.0006 lbs steam per maximum vent gas
flow)
[0018] The invention relies solely on completely internal steam, steam
injected
completely internally to the flare vent gas ducting with no exposure to
surrounding
atmospheric air while imparting a significant mixing and momentum transfer
effect on the
surrounding ambient air environment. Other flares rely on stream that is
injected into the air
- 5 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
near and immediately surrounding the periphery of the flare tip and aimed so
that they drive
steam and air near and immediately surrounding the periphery of the flare tip
and aimed so
that they drive stream and air into the waste gas or effluent stream of the
waste gas. Such
flares are referred to as "External Steam Flares". There are other flares that
may be termed
"Internal Steam Flares" that rely on injecting steam through conduits,
passageways, or a
venturi from a surrounding air atmosphere thereby injecting air and steam
through the
containing wall or shell of the waste gas stream and into the central core of
the waste gas
stream.
[0019] In the present invention, as shown in FIG. 1, a waste gas stream
passes up through
a cylinder 12. Steam 2 is injected into the waste gas stream 1 at one or more
locations 4
whereupon the resulting accelerated stream and waste gas mixture, upon
exposure to the
surrounding air induces the surrounding air into the waste gas (fuel) and
steam mixture.
There is no mixture of the surrounding air 3 with the waste gas stream 1
before exiting the
top of the flare enclosure conduits. The steam and waste gas 5 are partially
mixed prior to
mixing with the surrounding ambient air 6 but emit from the confines of the
flare enclosure or
waste gas conduit with sufficient combined velocity and momentum to induce
effective
mixing of fuel and steam with the surrounding air to affect improved
combustion and
effectively complete destroying combustible waste gas. Relatively high
velocity steam 2
transfers momentum to the relatively low velocity waste gas 1 and induces some
mixing of
steam and waste gas 5 before exiting into surrounding air 3. The resulting
partially mixed
steam and waste gas stream then imparts momentum, drawing in and mixing with,
the
surrounding ambient air 6 as the steam and waste gas emit from the flare
enclosure conduits
7 In Figure 1 are shown four sets of four enclosure conduits 7, conduit steam
injection
nozzles 8, rings 9, velocity seals 10, and hub steam injection nozzles 16.
Also shown are
transition plates 11, curved to allow for sufficient flow distribution into
cans with minimal
wind area and a hub expansion cylinder and plate 13 to mitigate growth from
theinial
stresses.
100201 Fig. 2 is a view that includes the lower portion of the flare
assembly with the
cylinder 12 into which waste gas 1 passes and the pipe in which steam 2 is
sent to the upper
portion that contains the explained above. Hub steam injection nozzles 16 are
shown, which
result in steam separating the combusting waste gas stream mixture from the
center hub
metal.
- 6 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
[0021] Fig. 3 illustrates detail of several flare enclosure conduits.
Steam 2 passes into
flare conduits 7 and then into surrounding air 3 to be burned effectively.
Rings 9 and velocity
seals or flow-restricting cones 10 are shown in each enclosure conduit 7.
[0022] Fig. 4 is a view that shows more detail of two individual flare
enclosure conduits 7
with steam 8 entering through a tube 14 that extends to near the top of the
flare enclosure
conduit while waste gas passes up to mix with the outside ambient air to then
burn efficiently.
[0023] In other embodiments of the invention, there is a reliance on
internally injected
steam to keep the steam warm. This steam is injected wholly within the flare
tip conduit
enclosure and is sufficiently away from, upstream of, the exit to atmosphere
opening of the
.. flare tip that this steam completely mixes with the waste gas and imparts a
small but largely
insignificant momentum component to the waste gas stream and is sufficiently
upstream of
the flare exit as to impart no significant effect on enabling or enhancing the
mixing of the
resulting waste gas and steam mixture with the surrounding atmospheric air.
This design
relies on internal steam as injected through a conduit or venture drawing in
surrounding air as
.. described above. External steam is used in drawing in surrounding air from
the periphery of
the exiting waste gas stream and steam to keep warm is injected wholly within
the flare waste
stream conduit. The present invention relies on a new, separate and different
mixing method
of partially mixing steam with waste gas at a location where it can then mix
with and impart
momentum upon the surrounding atmospheric air.
[0024] The depicted embodiment shows twenty-four waste gas conduits 7, four
on each
of six transition sections, for a twenty-four inch riser cylinder 12. in
another embodiment, the
number and size of waste gas conduits and number and size of transition
sections could vary
more or less.
[0025] In one embodiment (pictured), the steam injection nozzle in
located upstream of
the plane at the exit of the waste gas conduit. In another embodiment (not
pictured) the steam
injection tip extends through and beyond the plane of at the exit of the waste
gas conduit
while remaining completely enveloped in the waste gas stream.
[0026] In the depicted embodiment, the waste gas tip has a ring 9
located near, but
slightly upstream of the waste gas exit. This ring is not necessary, but can
serve to 1) enhance
the mixing of waste gas, steam and air, 2) stabilize or create as stable bluff
body for flame
stabilization and 3) serve as a fine tuning location whereby adjusting the
size of the
passage(s) in the ring the flow capacity of the flare can be adjusted to
specifically meet the
- 7 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
flow capacity requirements of a particular flaring application or operation.
The benefits of
adjusting the capacity of the flare to correctly match the flow and capacity
requirements of a
particular flaring application or operation include fuller utilization of the
available pressure
loss in the waste stream system thereby enhancing the mixing of the waste gas,
steam and air.
Improved or enhance mixing of waste gas, steam and air not only improves the
combustion,
thereby increasing the smokeless capacity of the flare burner but also further
reduces the
steam utilization of the flaring system to values of much less than 0.20 lbs
steam is used per
pound of propane waste gas approaching or less than 0.10 lbs steam used per
pound of
propane waste gas This ring or rings can be located as depicted, upstream of
the exit, at the
exit or suspended on a structure and held downstream of the exit. These rings
may also reside
singularly or in plurality on the outside of the outside of the waste gas
conduit. The depicted
waste gas conduit 7 is cylindrical but in practice may be of various shapes
including square,
rectangular, oval or complex. Given the multiplicity of possible shapes, the
"ring(s)" may be
of various shapes and dimensions and may contain perforations or other surface
features the
may disrupt, guide or channel the flow of steam, waste gas or air to affect
the mixing of the
three component streams.
[0027] In the depicted embodiment, the waste gas tip 9 has three
velocity seals or flow-
restricting cones 10 per waste stream conduit 7. These cones are not necessary
but serve to 1)
restrict air from flowing upstream into the flare transition or entry cylinder
12 under low-flow
operating conditions, 2) maintain combustion in waste stream conduits 7, and
3) reduce
combustion within the waste stream entry cylinder 12. Additionally, these
cones can be
increased or decreased in count per waste stream conduit or flow diverted from
them as
required.
[0028] Curved transition plate 11 is shown in the depicted embodiment,
but this plate can
be flat, sloped, or curved in a direction opposite to that depicted in the
figure. The curved
shape is utilized to optimize flow distribution while minimizing pressure
drop. Hub cylinder
and flat plate 13 are not required but as depicted are used to maximize
equipment life. Other
embodiments not depicted involve cone with flat plate or simple flat plate.
100291 The entrance of steam 2 into mixing zone with waste gas stream 5
is depicted with
nine orifices 15 at a forty degree angle from vertical. Other embodiments
include more or less
orifices down to a single orifice, ranging from an angle up to fifty degrees
from vertical to
directly vertical.
- 8 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
100301 The depicted embodiment displays hub steam injection nozzles
which are not
required but which lengthen the life of the equipment by separating the center
hub metal from
the combustion with cooling steam.
SPECIFIC EMBODIMENTS
100311 While the following is described in conjunction with specific
embodiments, it will
be understood that this description is intended to illustrate and not limit
the scope of the
preceding description and the appended claims.
100321 A first embodiment of the invention is a steam flare comprising a
waste gas
cylinder connected at an upper portion of the waste as cylinder to a plurality
of extensions
that extend away from a center of the waste gas cylinder, wherein each of the
extensions
contain a plurality of flare gas conduits, and wherein a steam tube is located
in each of the
flare gas conduits. An embodiment of the invention is one, any or all of prior
embodiments in
this paragraph up through the first embodiment in this paragraph wherein the
steam flare
further comprises a ring at a top portion of the flare gas conduit and above a
top portion of
the steam tube. An embodiment of the invention is one, any or all of prior
embodiments in
this paragraph up through the first embodiment in this paragraph wherein the
flare gas
conduit is a tube having a cylindrical configuration. An embodiment of the
invention is one,
any or all of prior embodiments in this paragraph up through the first
embodiment in this
paragraph wherein the flare gas conduit is a tube having a square,
rectangular, oval or
complex configuration. An embodiment of the invention is one, any or all of
prior
embodiments in this paragraph up through the first embodiment in this
paragraph wherein the
steam tube comprises a single tube having branches that extend into each of
the flare gas
conduits. An embodiment of the invention is one, any or all of prior
embodiments in this
paragraph up through the first embodiment in this paragraph wherein the ring
contains
perforations or other surface features An embodiment of the invention is one,
any or all of
prior embodiments in this paragraph up through the first embodiment in this
paragraph
wherein the steam flare further comprises a multiplicity of flow-reducing
cones in the flare
gas conduit and below a top portion of the steam tube. An embodiment of the
invention is
one, any or all of prior embodiments in this paragraph up through the first
embodiment in this
paragraph wherein the steam flare further comprises a singular flow-reducing
cone in each of
the flare gas conduits and below a top portion of the steam tube. An
embodiment of the
- 9 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
invention is one, any or all of prior embodiments in this paragraph up through
the first
embodiment in this paragraph wherein the stream flare comprises a curved
transition piece
from waste gas cylinder to flare gas conduits. An embodiment of the invention
is one, any or
all of prior embodiments in this paragraph up through the first embodiment in
this paragraph
wherein the steam flare comprises a straight transition piece from waste gas
cylinder to flare
gas conduits. An embodiment of the invention is one, any or all of prior
embodiments in this
paragraph up through the first embodiment in this paragraph wherein the steam
flare has a
sloped transition piece from waste gas cylinder to flare gas conduits An
embodiment of the
invention is one, any or all of prior embodiments in this paragraph up through
the first
embodiment in this paragraph wherein there is a flat plate capping the waste
gas cylinder. An
embodiment of the invention is one, any or all of prior embodiments in this
paragraph up
through the first embodiment in this paragraph wherein there is a cone and a
flat plate
capping the waste gas cylinder. An embodiment of the invention is one, any or
all of prior
embodiments in this paragraph up through the first embodiment in this
paragraph wherein the
steam flare has a cylinder and a flat plate capping the larger concentric
waste gas cylinder.
An embodiment of the invention is one, any or all of prior embodiments in this
paragraph up
through the first embodiment in this paragraph wherein the steam flare has a
steam tube with
a singular orifice pointing vertical. An embodiment of the invention is one,
any or all of prior
embodiments in this paragraph up through the first embodiment in this
paragraph wherein the
steam flare has a team tube with two to twenty orifices, pointing at an angle
between zero and
fifty degrees from vertical. An embodiment of the invention is one, any or all
of prior
embodiments in this paragraph up through the first embodiment in this
paragraph wherein the
steam flare has external steam tubes injecting steam between hub metal and
combusting
stream.
[0033] A second embodiment of the invention is a process of operating a
steam flare
comprising sending a waste gas stream through a waste gas cylinder to a
plurality of flare gas
conduits while sending a stream of steam through a tube wherein the tube
extends into the
flare gas conduit, mixing the waste gas stream and the steam and then causing
a flame to bum
as a resulting mixture of the waste gas stream, the steam and oxygen in
outside ambient air.
An embodiment of the invention is one, any or all of prior embodiments in this
paragraph up
through the first embodiment in this paragraph wherein a ring at an upper
portion on a waste
gas tip of the flare gas conduit comprises perforations or other surface
features to direct
- 10 -
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
mixture of the steam and the waste gas. An embodiment of the invention is one,
any or all of
prior embodiments in this paragraph up through the first embodiment in this
paragraph
wherein the flare gas conduit has a configuration selected from the group
consisting of
cylindrical, square, rectangular, oval and complex shapes. An embodiment of
the invention is
one, any or all of prior embodiments in this paragraph up through the first
embodiment in this
paragraph wherein less than 0.09 kg (0.20 lbs) steam is used per pound of
propane waste gas.
An embodiment of the invention is one, any or all of prior embodiments in this
paragraph up
through the first embodiment in this paragraph wherein a ring at the upper
portion of the
waste gas tip of the flare gas conduit comprises perforation or other surface
features properly
sized in proportion to the waste gas stream and thereby values approaching or
less than 0.05
kg (0.10 lbs) steam is used per pound of propane waste gas. An embodiment of
the invention
is one, any or all of prior embodiments in this paragraph up through the first
embodiment in
this paragraph wherein all of the steam is injected internally to the waste
gas before exposure
to surrounding atmospheric air. An embodiment of the invention is one, any or
all of prior
embodiments in this paragraph up through the first embodiment in this
paragraph wherein
most of the steam is injected internally to waste gas before exposure to
surrounding
atmospheric air and some of the steam is injected externally to separate
combusting stream
from hub metal. An embodiment of the invention is one, any or all of prior
embodiments in
this paragraph up through the first embodiment in this paragraph wherein the
steam imparts
mixing and momentum transfer to the waste gas and the surrounding atmospheric
air. An
embodiment of the invention is one, any or all of prior embodiments in this
paragraph up
through the first embodiment in this paragraph wherein a singularity or
multiplicity of flow-
reducing cones in the flare gas conduit reduce the amount of air flowing
upstream into the
flare gas conduit. An embodiment of the invention is one, any or all of prior
embodiments in
this paragraph up through the first embodiment in this paragraph wherein
reduced steam
and/or assist gas is required to maintain smokeless operation under low-flow
operating
conditions. An embodiment of the invention is one, any or all of prior
embodiments in this
paragraph up through the first embodiment in this paragraph wherein curved
transition pieces
between flare gas cylinder and the waste gas conduits improve flow
distribution exiting the
waste gas conduits and reduce pressure drop through flare gas system. An
embodiment of the
invention is one, any or all of prior embodiments in this paragraph up through
the first
embodiment in this paragraph wherein a singular vertical orifice or multiple
orifices at an
-11-
CA 03075057 2020-03-05
WO 2019/055335 PCT/US2018/050171
angle are utilized to increase mixing of the steam, surrounding atmospheric
air, and waste
gas. An embodiment of the invention is one, any or all of prior embodiments in
this
paragraph up through the first embodiment in this paragraph wherein the
orifices increase the
velocity of the waste gas stream while reducing the level of atmospheric air
backflow at low
flow rates through partial steam-capping of the flare gas conduit.
- 12 -
