Note: Descriptions are shown in the official language in which they were submitted.
CA 02531870 2005-12-30
FIELD OF')I'HE INVENTXON
The present invention relates generally to waste disposal. More particularly,
the
present invention relates to an evaporator for reducing the amount of waste
materials, such as
wastewater, by evaporating at least a portion of the waste materials to reduce
the amount of
nnaterial for disposal and returning clean water to the atmosphere while
separating
contaminants for removal and disposal.
BACKGROUND OF ~ IN'YhNTiON
Industrial sites, such as those associated with oil and gas well exploration,
drilling or
service operations, or processing plants often lead to the production of waste
fluids such as
wastewater. Wastewater produced at such sites must be collected, stored, and
disposed of.
Usually, this is accomplished by collecting the wastewater in a storage tank
and then trucking
the wastewater to a disposal site for disposal, leading to trucking and
disposal posts.
US Patent No. 4,534,828 (Eriekson et al.) discloses an evaporator apparatus
having
means for heating, particularly a fire tube, situated in the bottom poztian of
a tank. A
disadvantage of this evapoFator in using a hue tube is that it requires a
separate fuel and the
flare of the fine tube presents an additional hazard; particularly where the
materials to be
evaporated include flammable materials.
i7S Fatent Na. 5,240,550 (Gregory) discloses a wastewater evaporation system
including a tank having honeycomb plates which are rotated through the
wastewater and a
vapour space above the wastewater. An electric heater heats air which is blown
through the
vapour space in the taz~k, and the hot air evaporates water from the plates. A
disadvantage of
this system is that it includes auxiliary equipment (blower and equipment to
rotate the
honeycomb plates) and would seem to require frequent maintenance.
US Patent No. 5,582,680 (Van'L~ouwenberg et al.) discloses a wastewater
treating
apparatus. Fluid is received in a receiving vessel/evaparator. A burner in a
fire box below the
vessel produces flue gas which heats the evaporator sidewalls and bottom to
evaporate
wastewater. A disadvantage of this apparatus is that flue gas can be very
corrosive, which
-1-
CA 02531870 2005-12-30
could result in a requirement for frequent maintenance on the apparatus, and
the :ire box
includes the same disadvantages of a fine tube, as mentioned above. In
addition, heating via
direct contact with the bottom or sides of the tank would be impeded if the
fluid is at all
insulating or if debris or solids interfere with the heat transfer.
S>UMMA1~Y OF T)HE IlYV)E1VTION
It is an object of the present invention to obviate or mitigate at least one
disadvantage
of previous evaporator systems.
In one aspect, the invention is an evaporator for evaporating a waste material
at an
industrial site, including, a tank, comprising side walls and a bottom, the
tank adapted to
receive waste material, and heating means adapted to heat the waste material
when in the
tank, the heating means proxinnate to, but spaced from the bottom of the tank.
Preferably, the
waste xzraterial is boiler blvwdown. Preferably, the heat source comprises a
steam tube routed
through a portion of the tank, the steam tube adapted to connect with a steam
supply to
receive steam. Preferably, the heat source is an electric heater, the electric
heater adapted to
connect to an electrical Bower source to generate heat. Preferably, a side
wall eornprises a heat
source opening, wherein the heat source opening is adapted tv receive the heat
source.
Preferably, the side walls comprise double side walls, the double side walls
having an outer
wall and an inner wall, the outer wall and the inner wall separated by a wall
space. Preferably,
the wall space is adapted to be substantially filled with an insulating
material. Preferably, the
insulating material is an insulating foam installed as a liquid. Preferably, a
boiler blowdown
inlet, the boiler blvwdown inlet adapted to receive boiler blvwdown from, a
boiler az~d to
direct the boiler blowdown into the tank via a diffuser.
Preferably, the waste material comprises a first waste material and a second
waste
material, the first waste material and the second waste material genexally
being mixable
together and the second waste material having a lower density than the first
waste material,
wherein the tank is adapted to receive waste material, which then forms a
surface level above
the second waste material and an interface level between the first waste
material and the
second waste material, the evaporator further comprising a vent passage
adapted to extend
-z-
CA 02531870 2005-12-30
between below the interface level and above the surface level, through which
vapours
generated below the interface Ievel may escacpe through the vent passage.
Preferably, a cover is adapted to generally cover the tank. Preferably, the
cover
includes a mesh grating, steel plate, or a combination of mesh grating and
steel plate.
In another aspect, the invention is a method of disposing of a waste material
or a
method of reducing the volume or amount of a waste material including the
steps of providing
an evaporator adapted to evaporate at least a portion of the waste material,
receiving the waste
zxxaterial into the evaporator, applyiztg energy or heat to the waste
material, and allowing a
period of tune to pass, wherein at least a poztiori of the waste material is
converted into a
vapour.
Preferably, the waste material comprises the solids, liquids and/or vapours of
a boiler
blawdown wherein the vapour portion, if any, readily drifts ofF, the solids,
if any, settle to the
bottom of the evaporator, and at least a portion of the liquids, if any, are
evaporated.
Preferably, the method includes the subsequent step of disposing of the waste
material that
remains in the evaporator. Preferably, the waste material that remains in the
evaporator is
removed from the evaporator by drainage or by vacuum.
Preferably, the waste material comprises snow contaminated with a contaminant.
Preferably, the waste material comprises water contaminated with a
contaminant. ~'referably,
the waste material comprises ice contaminated with a contaminant. ~'referably,
the
contaminant includes oil, soil, clay, dnih cuttings, drilling mud, mud,
hydrocarbons, glycols,
amines, reservoir fluids, fracturing fluids, human waste, sewagE, or boiler
blowdvwns or a
combination thereof, any or all of which may include solids, such as free
solids or dissolved
solids. Preferably, the waste material comprises oily water_ Preferably, the
waste material
coxz~prises oil and water, further comprising the step of removing at least a
portion of the oil
from the evaporator before applying heat to the remaining waste t~aaterial for
evaporation.
Preferably, the waste material comprises solids (dissolved or suspended).
Preferably, the temperature of the waste material is maintained between about
85°C
and about 100°C. Preferably, the period of time is sufficient for a
substantial quantity of the
waste material td evaporate, further comprising floe step of removing any
remaining waste
--3-
CA 02531870 2005-12-30
material from the evaporator. Preferably, the substantial quantity is
substantially 80% of the
waste material initially received in the evaporator. Preferably, the rennoval
is by vacuum.
Preferably, at least a portion of the vapour is converted to form condensed.
water by
condensation. Preferably, at least a portion of the condensed water is
recycled into the tank for
further evaporation. Pre~erabIy, the vapour is exposed to a temperature
sufficiently below the
dew~point of the vapour, wherein thermal condensation occuzs.
Other aspects and features of the present invention will become apparent to
those
ordinarily skilled in the art upon review of the following description of
specific embodiments
of the invention in conjunction with the accompanying ~~gures.
BRIEF DESC~.IPTION OF THE DRAWYNG.S
Embodiments of the present invention will now be described, by way of example
only,
with reference to the attached Figures, wherein-
Fig. 1 is a perspective view of as evaporator system of the present invention,
of the variant having a grate cover;
Fig. 2 is a tap view of an evapoz~ator system of the present invention, of the
variant having a plate cover;
Fig. 3 is an end view of the an evaporator system of Fig. 2;
Fig. 4 is a side view of the evaporator system of Fig. 2;
p'ig. 5 is an end view of the evaporator system of Fig. Z;
Fig. 6 is a section view of the evaporator system of Fig_ 2, along ttxe
section 6-
6 of Fig. 7, of the variant having an electric heater;
p'ig. 7 is a section view of the evaporator system of Fig. 2, along the
section 7-
7 of Fig. 6;
Fig. 8 is section view of the evaporator system of Fig. 2, along the section 8-
8
of Fig. 6; and
Fig. 9 is a perspective detail view of a boiler blowdawn inlet; and
Fig_ LO is a partial view of an evaporator system of the present invention,
detailing a vent passage.
CA 02531870 2005-12-30
n~xan.E~ nESCa~~rroN
Crenerally, the present invention pravides a method and apparatus for
evaporating
waste material at an industrial site.
Referring generally tv Figs. 1-8, an evaporator x 0 of the present invention
includes a
tank 20 having walls 30, 40, 50, and 60 and a bottom 70, adapted to receive
and contain a
waste material (not shown).
In the preferred embodiment, heating means in the forzxa of a steam tube 80 is
adapted
to heat the contents of the tank 20. Xn another embodiment, heating means in
the form of an
electric heater 90 is adapted to heat the contents of the tank 20 (see Fig.
6). 'fhe heating means
(whether it be the steam tube 80, or the electric heater 90, or even both the
steam tube 80 and
the electric heater 90} may be positioned so that there is a space between the
bottom of the
heating means and the suz~'aee of the bottom 70 of the tank 20, and may he
placed near the
bottom 70 of the tank 20 or it may be a "stab-in" type inserted through a wall
30, 40, 50, or 6b
of the tank 20. Preferably, as shown (Fig. 7}, the evaporator 10 includes the
steam tube 80
positioned proxirtxate to the bottom 70 of the tank 20 iii addition to having
an accessory flange
$S, adapted to receive the electric heater 90.
The steam tube 80 receives steam visa a steam inlet 82 and steam leaves via a
steam
outlet $4. The steam inlet 82 and the steam outlet 84 are adapted to connect
to a suitable beat
or steam source, such as, but not linnited to a steam boiler o.f the type
commonly found at
industrial sites or well sites as part of a drilling rig ar service xig or
other well site ar plant site
eduipme~nt. In the preferred ettzbodiment, steam from a steam boiler Mows from
the steam
boiler through the steam inlet 82, through the steam tube 80, and out through
the steam outlet
84, and the steam is then used for its usual purposes, such as heating.
Typically, 500-604 KPa
(75-80 psi) steam, having a temperature generally around 150°C
(300°F) may be used.
The accessory flange 85 is adapted to receive the electric k~eater 90.
FIowever, another
type of heat source could be received by the accessory flange 85. When not in
use, the
accessory flange 85 is sealingly cbvered with a blind 87.
In the variant of the evaporator 10 using the electric heater 90 (Fig. 6), a
heating
element 92 of the electric heater 90 is sealingly contained within a beater
tube 94, the heater
_5_
CA 02531870 2005-12-30
tube 94 being suppozted within the tank 20 with support 96. 'thus, the heating
element 92
does not come into direct contact with the waste matezial. The heater tube 94
is filled with a
heat transfer fluid, such as heat transfer oil 97. The heat transfer oil may
be any suitable oil,
such, as mineral oil or other oil, or may be Sun OiI CompanyTM Heat Transfer
Oil Na. 21TM.
The heating element 92 may be approximately 6" outside dimension, with the
heater tube
being approximately 8" inside dimension. .After insetting the heating element
92 into the
heater tube 94, the heater tube 94 zs~ay be substantially fzlled with tk~e
heat transfer oil 97 via a
fill opening 98. When required, the heater tube 94 may be drained of the heat
transfer oil 97
via a drain opening 99.
The evaporator 10 may include a lore level shut-off (not shown), adapted to
provide a
warning signal ar adapted to activate, deactivate or otherwise control the
heat output of the
heat source, for example by shutting off the electricity to the electric
heater 90 if the level of
waste material in the tank 20 falls below a certain level.
In the preferred embodiment, the walls 30, 40, ~0 and 60 and the bottom 74 of
the tank
20 are "double wall", having an outer wall 100 (typical) and an inner wall 110
(typical)
separated by a sealed wall space 120 (typical). The wall space 120 may be
substantially f~Iled
with an insulating material 130, such as liquid foam 140 which is poured into
the wall space
120 between the outer wall 100 and the inner wall I10 as a liquid and then
allowed to set or
harden to farm a durable insulating material 130 inside the wall space 120.
The insulating
material 130 reduces heat lass from the tame 20 as well as lowers the operate
temperature of
the outer wall 100 (typical) to reduce the risk of heat damage or burning of
operating
personnel.
Referring to Figs. 6, 8, az~d 9, waste material (not shown) in the form of
boiler
blowdown from a boiler may be directed into the tank 20 via a boiler blowdown
inlet 140.
The boiler blowdown is directed downwards into the tank 20 by a diffuser I50
which helps to
separate the vapour, liquid, and even solids portions of the boiler blowdawn.
The boiler
bla~xrdown is directed at the diffuser 1 ~0 by a nozzle 165 connected to the
boiler blowdown
inlet 140 by a conduit in the form of a pipe 160. The diffuser 1. SO rnay be a
substantially semi-
circular plate (as shown). The nozzle 16S may be an open elbow fitting (as
shown). The pipe
CA 02531870 2005-12-30
160 and the diffuser 150 may be attached to a wall 30, 40, 50 or 60 of the
ta~nlc 20 to give
stability and strength.
The tank 20 may include a cover 170 to generally cover the tank 20. The cover
170
may generally enclose the top of the tank 20 with a mesh ox grate type cover
which allows
vapours to escape the tank 20, but keeps any workers, tools and debris out of
tlae tank 20 (see
Fig. 1) or the tarxk 20 may he generally enclosed with a plate type cover with
a portion of the
cover 170 including a mesh or grate to allow vapours to escape (see Fig. 2).
Referring to Fig. 10, the tank 20 may include a vent passage 180 or a
plurality of vent
passages, oriented generally vertically in tb~e tank 20. As shown, the vent
passage 210 extends
substantially vertically along a wall 30, 40, 50 or 60 of the tanlt 20 from a
lower end 190 to an
upper end 200. The vent passage 210 may be constructed of a simple conduit
such as a pipe or
a section of square tubing I80. In operation, particularly where the waste
material comprises a
first waste material (not shown) and a second waste material (not shown), and
the first waste
material and the second waste material are not generally mixable with each
other and the
second waste xuaterial has a lower density than the first waste material, the
waste material in
the tank 20 could end up forming a lower layer of first waste material and an
upper layer of
second waste material. A surface level 230 is formed above the second layer
and an interface
level 220 is formed between the first waste material and the second waste
material.
l7epending on the components and physical properties of the first az~d second
waste materials,
the vent passage 210 provides a safety Felease in the remote and unlikely
event where the
second waste nrxaterial is suf&ciently viscous or has a lower vapour pressure
than the first
waste maternal or otherwise prohibits or restricts the escape of evaporating
first waste
material. Preferably, the event where the first waste material evaporates oz
boils underneath
(below) the second waste material, aztd the second waste material prohibits or
restricts the
escape to atmosphere of the vapour from the evaporating or boiling first waste
material such
that pressure builds up is to be avoided. Tn such cases, evaporating frst
waste material may
travel from the Iower end 190 up through the vent passage 2I0 and out the
upper end 200
regardless of any prohibition or restriction contributed by the second waste
material.
CA 02531870 2005-12-30
In operation,, waste material, such as contaminated water is placed in the
tank 20
where a steam coil 80, electric heater 90 or another heat source such as solar
energy or
geothernaa! energy, brings the waste material to a temperature su~cient for
evaporation of at
least a portion of the waste material, and a period of time is pezrnitted to
elapse to allow the
desired amount of waste material to be evaporated, l~Vhatever reduced waste
material remains
in the tartly 20 may then be disposed o~ for example by vacuum truck, thus
reducing trucking
and disposal casts.
The heat source may include the steam coil 80, the electric heater 90, or
both.
The evaporator 10 is useful for a wide variety of waste materials, including,
but not
limited t4 oil, water, grey grater, snow, contaminated snow, ice, contaminated
ice, oily water,
oily snow, oily ice, dirt, drill cuttings, drilling mud, mud, hydrocarbons,
glycols, amines,
reservoir fluids, fracturing .fluids, human waste, sewage, boiler blowdowns,
any of which may
include solids, such as free solids or dissolved solids.
The temperature of the waste material in the tank 20 znay be controlled. In
the case of
evaporating water, the temperature may be maintained between about 85°C
and about 100°C.
The evaporator 10 may be operated in a continuous or a batch operation. The
surface
of the waste material in the tank 20 may be skimmed, vacuumed or otherwise
removed to
avoid evaporating volatile hydrocarbons or other waste materials that float on
or near the
surface or at or near an interface between differing waste materials.
Solids, such as free solids, dissolved solids, or sledge etc. that settle out
in the tank 20
may be periodically removed or may be removed with the unevaporated portion of
the waste
materials in the tank 20.
Although flanged connections are shown, any suitable connection type known to
one
skilled in the art may be used for the connections.
The above-described embodiments of the present invention are intended to be
examples only. Alterations, modifications and variations may be effected to
the particular
embodiments by those of skill in the art without departing firom ttxe scope of
the invention,
which is defined solely by the claims appended hereto.
_g_
