Note: Descriptions are shown in the official language in which they were submitted.
CA 02917959 2016-01-15
Settling Oil Removal Tank, System and Method for Produced Water
Treatment
Technical Field
The present invention belongs to the technical field for heavy oil produced
water
treatment in the oil field surface engineering, particularly for the treatment
of the
produced water having high temperature and low oil-water density difference as
well as
high emulsification degree which is generated in the SAGD (Steam Assisted
Gravity
Drainage) heavy oil recovery at home and abroad.
Background Art
Currently, internationally accepted technologies for treating oilfield
produced water
mainly include the oil removal techniques such as gravity settling, gas
floating, cyclone
oil remover, filtering and so on; and the yielding water is further subjected
to treatment of
desalination and softening and is then used as boiler feedwater. Since the
produced water
from heavy oil recovery has a relatively high temperature and is not suitable
for being
treated by a biological method, the following physical methods and physical-
chemical
methods are mainly used:
Physical methods: physical methods mainly use physical principles to separate
impurities such as oil and solid suspended particles in the water, and
physical methods
mainly include gravity settling separation method, removing by a cyclone oil
remover,
horizontal flow oil removal tank separation and filtration method.
Physical-chemical methods: when there are dispersed oil, emulsified oil, and
suspended solids in a dispersed state, a dissolved state or a colloidal state
in the produced
water, they cannot be removed only by using a physical method but need to be
removed
by a combination of the physical and chemical methods. The physical-chemical
methods
mainly include a coagulation and sedimentation method, a gas floating method,
a
chemical agent reaction tank and so on.
Usually, the inflow water of a produced water treatment system contains
2000ppm of
CA 02917959 2016-01-15
oil and 300ppm of suspended solids, and the requirement for the system is that
the
content of oil and suspended solids in the yielding water should be less than
5ppm. The
conventional processes of a produced water treatment system include an oil
removal tank
+ a gas floating machine + a filter. The treating devices for the processes
are slightly
different. Currently existing problems are mainly in the following two
aspects: the
efficiency of the oil removal tank for the primary treatment needs to be
further improved,
and more efficient and stable treating techniques are needed to compensate the
shortcomings of the physical method alone. The characteristics and
shortcomings of the
prior arts are described as follows.
At present, as a primary treatment device of the oil removal process, the oil
removal
tank receives original water quality of the produced water containing 2000ppm
of oil and
300ppm of suspended solids, and generally, the designed indexes for the
yielding water
are that the content of oil is less than 300ppm, and the content of the
suspended solids is
less than 150ppm. The oil removing rate of the oil removal tank is generally
designed to
be up to 90%, and the suspended solids removing rate is up to 50%, but the
investment is
less than that for the subsequent flotation and filter, belonging to the
primary factor
concerned in making the oil removal system satisfy the operation standard. If
the yielding
water from the oil removal tank does not meet the standard, it will result in
that the
subsequent floating and filtering devices may affect the water quality of the
yielding
water from the overall system, and further, damages will occur to the
subsequent
desalination devices such as MVC (Mechanical Vapor Compression), and cause
high
maintenance costs. Therefore, to ensure the treatment effect of the oil
removal tank as the
primary treatment facility at the forefront of the whole oil removing process
and the
desalination process is the key to reduce the subsequent treatment burden and
guarantee
stable operation of the subsequent processing. At present, the oil removal
tanks
commonly used in foreign countries are of the following two kinds:
2
CA 02917959 2016-01-15
Horizontal flow oil removal tank: the oil removal tank is a horizontal flow
type; One
or more vertical baffle plates are mounted inside the tank, and divide the
tank into several
parts. A flow path is provided between adjacent parts, integrally forming a
horizontal
folding flow oil removal tank. Since there are several separated parts, a
longer flow path
is formed in the limited circumferential cross-sectional area of the tank.
When the water
flow passes, the oil beads float up to the liquid surface because their
densities are smaller
than that of water. From the inlet to the outlet, the oil beads having larger
grain sizes
successively complete the floating process, and are collected and discharged
at the top of
the oil removal tank. Due to the small floating velocity, the oil beads having
relatively
smaller grain sizes cannot complete the above floating process and then cannot
be
discharged, and flow along the water into the next procedure.
Ordinary vertical flow oil removal tank: This kind of oil removal tank is a
vertical oil
removal tank. The water flows vertically in general. The inflow water goes out
through a
water tank on the center cylinder of the tank. The water tank discharges water
by using
pipelines. The water flows vertically downward after being distributed by a
water
distribution pipe, and finally goes into the bottom of the tank to be
collected and
discharged out of the tank.
These oil removal tanks for produced water only consider the floating effect
of the
oil beads caused by the density difference between oil and water, but do not
make
fundamental improvements in terms of improving coarse graining of the oil
beads and
increasing the floating velocity. Besides, they have poor adaptability to the
undulatory
property of the inflow water, and therefore, thcy need to be optimized in
aspects of
making the water collection and distribution uniform, improving the water flow
state in
the tank, and improving the way of sludge discharge.
On the other hand, most of the oilfield produced water treatment process in
foreign
countries is relatively simple, and is mainly physical process, i.e. a
floating process,
which has poor adaptability to the undulatory property of water and water
quality
difference. The filter is occasionally stopped due to the filter material
contamination
caused by the instability of the yielding water from the preceding oil removal
tank and air
3
CA 02917959 2016-01-15
flotation in previous procedures. In addition, there is no special solution to
the system
corrosion and scale formation. The pharmaceutical agents are of higher costs,
and the
sedimentation process currently used in agent coagulation reaction is not
mature, and
does not meet the requirements on the efficient treatment and stable and
qualified water
quality by the oilfield produced water treatment project.
To sum up, the produced water treatment in the prior arts mainly has the
following
problems:
1) In the aspect of the oil removal tank:
a. water collection and water distribution are not uniform: both of the above
two
kinds of oil removal tanks adopt the manner of inflowing water in large
amount, and thus
when the water flows into the tank, there is great disturbance. That is, the
flow state of the
water will be affected without the uniform water distribution, so a turbulent
flow is
formed in water, and the shearing forces, in a plurality of directions, of the
turbulent flow
will lead to that the oil beads have velocities in other directions, in
addition to the floating
velocity caused by the floating force, so the floating height is affected in a
limited time.
Therefore, under the requirement of the designed oil removing rate, the
requirement on
detention time is increased. Furthermore, without a uniform water
distribution, the
adaptability to the impact of the inflow water is also reduced, so it is
likely that the
agglomerated crude oil goes into the oil removal tank without being
distributed, and
directly enters into the subsequent procedure due to insufficient settling
ability, resulting
in contamination of the subsequent devices. Without being uniformly collected,
the water
with oil removed can easily form a short circulating, and waste oil and sludge
can easily
gather at the place where the flow state is poor at the water outlet of the
outflow-water
section, causing fluctuation of water quality of the outflow water.
b. there is no highly efficient sludge discharging device: at present, there
is no
special sludge discharging device in the above two kinds of oil removal tanks,
so the silt
and organic colloids brought from the upstream and sludge deposited in the
water all
naturally sink down to the bottom of the tank, and they are removed by means
of
providing a sewage draining exit connected with a tank cleaning vehicle to
perform tank
4
CA 02917959 2016-01-15
cleaning regularly. When the sludge is of small amount, only part of the water
at the tank
bottom is discharged; when the sludge is of large amount, the whole tank is
cleaned. By
using such means of operation, on the one hand, the sludge at the tank bottom
cannot be
removed completely, and the sludge on the other side of the opening for
cleaning tank
will still be accumulated; on the other hand, when the whole tank is cleaned,
it needs to
suspend production, or it usually needs to build two oil removal tanks,
increasing the
investment.
c. the flow state of the horizontal flow oil removal tank is not ideal. Since
water and
oil beads flow in the same direction, in addition to the floating velocity
caused by
buoyancy, the oil beads also have horizontal progressing velocities due to the
shearing
force from the water flow. Thus, the oil beads actually float in a parabolic
track. As the
flowing velocity of the water flow is much greater than the floating velocity,
in the
limited floating height, the horizontal advancing track is relatively long,
which has a
higher requirement on the height of the flow channel, thus, while keeping the
floating
height unchanged, the cross-sectional area of the oil removal tank is
increased and the
effective detention time prolongs accordingly.
2) In the aspect of technique processes:
The existing oil removal tank and the gas floating process cannot guarantee a
stable
and qualified quality of the yielding water, which exerts a great burden on
the filter. In
some oilfields, dehydration effect of the crude oil is poor, so the sewage
contains a large
amount of oil, which impacts on the sewage treatment establishment. As a
result, the
outflow water from the gravity oil removal in the early primary treatment and
the air
floatation and cyclone remover for the secondary treatment is not stable. With
large-scale
promotion of a variety of secondary, tertiary oil recovery technology, the
recycled water
is added in the produced water treatment system for being treated, resulting
in an increase
in the viscosity of the produced water, more stable emulsified oil, and
smaller density
difference between oil and water, so it is difficult for the air flotation and
the cyclone
separator to achieve the desired effect. In terms of equipment, there is a
common defect
that removing rate of the suspended solids having small particles and the oil
having a
small grain size is quite low. The above varieties of reasons cause the
treatment burden to
be transferred to the filter, causing the blockage of filter material and
affecting the
treatment effect. In addition, the filter is constantly stopped due to filter
material
contamination caused by the unqualified oil coming from early devices.
3) The produced water treatment system has no effective ion balance measure,
and
has severe corrosion and scaling problems. Because the oil removal tank + air
flotation
process only treats the produced water by physical methods, dirt forming ions
such as
calcium and magnesium cannot be effectively reduced. Thus, the oil removal
system has
severe sealing problem, and the cost of adding detergents is great.
4) The chemical treatment process needs to be optimized urgently. In view of
the
drawbacks of physical processes on the stability of the yielding water quality
and the
ability of scale prevention, some oilfields begin to use the technique of a
chemical agent
reaction tank to solve the above problems, but due to the short application
time, only the
technique of a chemical agents reaction and flocculation tank is used, and no
effective,
integrated technique and equipment for agents addition, reaction and
separation are
formed. Flocculation reaction pond is high in cost and difficult in
construction. When the
oil-containing sewage is treated by using the chemical coagulation
sedimentation method,
a large amount of water purifying agent needs to be added, thereby forming a
large
amount of floc which becomes sludge after settlement. The sludge is directly
discharged
after settling down. Therefore, the properties of the water purifying agent
are not fully
utilized, and the floc formed is quite loose, and the sludge has poor settling
property,
which is not helpful to dehydrate the subsequent sludge, resulting in low
working
efficiency, poor working quality and high costs.
Summary
In view of the above-mentioned problems in the prior art, a technical problem
to be
solved by the present disclosure is to provide a settling oil removal tank
which can
effectively remove oil and suspended solids from the produced water.
Thus, an embodiment of the present disclosure employs the following technical
6
CA 2917959 2017-07-24
CA 02917959 2016-01-15
solution: a settling oil removal tank comprising a tank body,
wherein a hollow central tubular column, a water distribution chamber, an oil
collecting groove and a sludge discharging device are provided in the tank
body;
the central tubular column is vertically provided in the tank body, with at
least at a
lower end thereof being sealed, an upper portion thereof communicating with a
first water
outlet pipe extending out of the tank body, and a lower portion thereof
communicating
with a plurality of water collecting pipelines located in the tank body; water
inlets are
provided on the water collecting pipelines;
the water distribution chamber is connected with a plurality of water
distribution
pipelines located in the tank body and a first water inlet pipe extending out
of the tank
body; water outlets are provided on the water distribution pipelines;
the oil collecting groove forms a ring shape around the inner wall of the tank
body;
the sludge discharging device is provided at the bottom inside of the tank
body.
Preferably, each of the water distribution pipelines comprises a water
distribution
main pipe which is perpendicular to the central tubular column, a water
distribution main
branch pipe which is connected to the water distribution main pipe and
perpendicular to it,
and a plurality of water distribution branch pipes which are connected to the
water
distribution main branch pipe; each of the water distribution branch pipes has
a water
outlet.
Preferably, the water outlet is in a trumpet shape with an opening upward.
Preferably, the water distribution chamber is sleeved on the central tubular
column,
and a plurality of the water distribution main pipes of a plurality of the
water distribution
pipelines are uniformly arranged at the water distribution chamber.
Preferably, each of the water collecting pipelines comprises a water
collecting main
pipe which is perpendicular to the central tubular column, a water collecting
main branch
pipe which is connected to the water collecting main pipe and perpendicular to
it, and a
plurality of water collecting branch pipes which are connected to the water
collecting
main branch pipe, and each of the water collecting branch pipes has a water
inlet.
Preferably, the water inlet is in a trumpet shape with an opening downward.
7
In one aspect, there is provided a produced water treatment system comprising
an oil
removal tank and a chemically adjustable cyclone reaction separation device,
wherein the
oil removal tank is a settling oil removal tank, the settling oil removal tank
comprising
a tank body, the tank body is provided with a hollow central tubular column, a
water
distribution chamber, an oil collecting groove and a sludge discharging
device; wherein,
the central tubular column is vertically provided in the tank body, with at
least a lower
end thereof being sealed, an upper portion thereof communicating with a first
water outlet
pipe which extends to the outside of the tank body, and a lower portion
thereof
communicating with a plurality of water collecting pipelines located in the
tank body,
whereas the water collecting pipelines are provided with water inlets thereon;
the water
distribution chamber is connected with a plurality of water distribution
pipelines located
in the tank body and a first water inlet pipe extending out of the tank body,
the water
distribution pipelines being provided with water outlets thereon; the oil
collecting groove
is formed into an annular shape around an inner wall of the tank body; and the
sludge
discharging device is provided at the bottom of the tank body, and the first
water outlet
pipe is connected to the chemically adjustable cyclone reaction separation
device.
Preferably, the chemically adjustable cyclone reaction separation device is a
cyclone
reaction separation tank which comprises a tank body and a cyclone reaction
center
cylinder longitudinally provided in the tank body, wherein a lower end of the
cyclone
reaction center cylinder is communicated with an inner cavity of the tank
body, and the
cyclone reaction center cylinder is divided into a first-stage cyclone
reaction section, a
second-stage cyclone reaction section, and a third-stage cyclone reaction
section from top
to bottom;
the tank body is fixed with a second water inlet pipe extending into the first-
stage
cyclone reaction section, a second water purifying agent pipe extending into
the
second-stage cyclone reaction section, and a tlocculant pipe extending into
the third-stage
cyclone reaction section; the second water inlet pipe is communicated with a
first water
purifying agent pipe.
CA 2917959 2017-07-24
the upper portion of the tank body is fixed with a water collecting pipe and
an oil
collecting pipe above the water collecting pipe, wherein the water collecting
pipe is
provided with an water inlet and is connected to a second water outlet pipe
extending out
of the tank body; and the oil collecting pipe is provided with an oil inlet
and is connected
to an oil outlet pipe extending out of the tank body;
the bottom of the tank body is connected to a sludge discharging pipe;
the first water outlet pipe is connected to the second water inlet pipe.
Preferably, both the water collecting pipe and the oil collecting pipe are
annular and
both are sleeved outside the cyclone reaction center cylinder, and there are a
plurality of
water inlets uniformly distributed on the water collecting pipe, and there are
a plurality of
oil inlets uniformly distributed on the oil collecting pipe.
8a
CA 2917959 2017-07-24
CA 02917959 2016-01-15
Preferably, an axial direction of the second water inlet pipe is tangential to
the inner
wall of the cyclone reaction center cylinder.
Preferably, the chemically adjustable cyclone reaction separation device
comprises a
cyclone reactor and a deslagging separation tank;
the cyclone reactor includes a tank body in which a baffle plate for
separating the
tank body into a first-stage reaction chamber in the lower portion and a
second-stage
reaction chamber in the upper portion is provided;
a water inlet is provided on the tank body corresponding to the first-stage
reaction
chamber, and a third water inlet pipe extending into the first reaction
chamber is provided
in the water inlet;
a water purifying agent adding port and a water outlet are provided on the
tank body
corresponding to the second-stage reaction chamber; an agent adding pipe
extending into
the second-stage reaction chamber is provided in the water purifying agent
adding port; a
third water outlet pipe extending into the second-stage reaction chamber is
provided in
the water outlet; the agent adding pipe is located at a lower portion of the
second-stage
reaction chamber, and the third water outlet pipe is located in an upper
portion of the
second-stage reaction chamber;
a through hole is provided on the baffle plate and is communicated with the
agent
adding pipe through a connecting pipe;
a sewage emptying opening is provided at the bottom of the tank body;
the third water inlet pipe is connected with the first water outlet pipe.
Preferably, the deslagging separation tank is a spray deslagging separation
tank
comprising a tank body, a center cyclone cylinder, a spray deslagging device,
an oil
receiving device, a sludge discharging device and a water receiving device;
the center cyclone cylinder is located in the tank body, with an upper end
thereof
being opened and a lower end thereof being fixed to the tank body and sealed;
an annular
cavity is formed between the center cyclone cylinder and the tank body; at
least one
9
CA 02917959 2016-01-15
communication port for communicating with the inner cavity of the tank body is
provided
at a lower portion of the center cyclone cylinder; a central portion of the
center cyclone
cylinder is connected with a fourth water inlet pipe, one end of which is
located in the
center cyclone cylinder and the other end of which is connected with the third
water
outlet pipe;
the spray deslagging device is provided at an outer side of the upper portion
of the
center cyclone cylinder;
the oil receiving device is provided on the inner wall of the tank body
corresponding
to the upper end of the center cyclone cylinder;
the sludge discharging device is provided at a position at the bottom of the
tank body
corresponding to the communication port;
the water receiving device comprises an external water tank which is mounted
on the
upper portion of the outer side of the tank body and a water receiving pipe
comprising a
water receiving annular pipe and a L-shaped guiding pipe; the water receiving
annular
pipe is located in the central portion of the tank body and is sleeved outside
the center
cyclone cylinder; one end of the L-shaped guiding pipe is communicated with
the water
receiving annular pipe and the other end thereof penetrates out of the tank
body and
extends into the external water tank in which a fourth water outlet pipe is
connected.
Preferably, a water level regulator is provided in the external water tank,
said water
level regulator comprising an outer cylinder, an adjustable inner cylinder, a
screw rod, a
mounting frame, a handwheel and a handwheel seat, wherein the outer cylinder
is fixed to
the bottom in the external water tank; the L-shaped guiding pipe is located in
the outer
cylinder; the fourth water outlet pipe is located at an outer portion of the
outer cylinder;
the adjustable inner cylinder is arranged in the outer cylinder and can move
up and down,
and an outer wall of the adjustable inner cylinder and an inner wall of the
outer cylinder
are maintained to be sealed; the screw rod is fixed to the adjustable inner
cylinder; the
mounting frame is located above the outer cylinder; a lower end of the
handwheel seat is
CA 02917959 2016-01-15
mounted on the mounting frame; the handwheel is mounted on an upper end of the
handwheel seat; a nut which enables the screw rod to pass through is mounted
in a central
portion of the handwheel.
Preferably, an axial direction of the fourth water inlet pipe is tangential to
the inner
wall of the center cyclone cylinder, and an exit of the fourth water inlet
pipe is located on
the inner wall of the center cyclone cylinder; the oil receiving device is an
annular groove
formed around the inner wall of the tank body, and an oil receiving pipe
extending out of
the tank body is connected to the annular groove.
Preferably, the spray deslagging device comprises a slag receiving groove, a
slag
collecting bucket, a slag receiving pipe and a flushing water pipe;
an upper end of the center cyclone cylinder penetrates through a bottom
surface of
the slag receiving groove and is positioned in the slag receiving groove, and
the bottom
surface of the slag receiving groove is a slope with one end higher than the
other;
the slag collecting bucket is provided at an outer portion of the bottom end
of the
slag receiving groove;
the slag receiving pipe is connected to the slag collecting bucket and extends
out of
the tank body;
an upper end of the flushing water pipe is fixed to the top of the center
cyclone
cylinder; a spray nozzle is connected to the flushing water pipe; and a lower
end of the
flushing water pipe penetrates out of the tank body.
Preferably, the deslagging separation tank is a negative pressure deslagging
separation tank comprising a tank body and a cylinder body provided in the
tank body,
wherein an upper end of the cylinder body is opened and a lower end thereof is
fixed to
the tank body and is sealed; an annular cavity is formed between the cylinder
body and
the tank body; at least one exit communicating with an inner cavity of the
tank body is
provided at a lower portion of the cylinder body; a slag receiving funnel is
fixed and
mounted to the upper portion of the cylinder body, and a bottom of the slag
receiving
11
funnel is connected with a slag discharging pipe extending out of the tank
body; a fifth
water inlet pipe is connected with the central portion of the cylinder
portion; an annular
oil receiving groove is formed on the inner wall of the upper portion of the
tank body, and
an oil receiving pipe extending out of the tank body is connected to the oil
receiving
groove; an annular packing layer is fixed in the central portion of the
annular cavity; an
annular water receiving pipe is provided in the annular cavity above the
filler layer; a
fifth water outlet pipe extending out of the tank body is connected to the
water receiving
pipe; a first annular sludge suction pipe located in the annular cavity is
fixed to the
bottom of the tank body, and a second annular sludge suction pipe is fixed
above the
packing layer.
In another aspect, there is provided a method for produced water treatment
comprising the steps of:
1) removing oil by settlement, wherein a settling oil removal tank is used,
and due to
the density difference of oil, water and the suspended solids in the produced
water, most
of the oil floats up while most of the suspended solids sink down, thereby oil
and
suspended solids being separated naturally, and the remaining small portion of
oil and
suspended solids go into a subsequent procedure;
2) removing oil by cyclone reaction, wherein after being treated in step 1),
the
produced water flows into a chemically adjustable cyclone reaction separation
device,
and is added with 2 to 3 kinds of purifying agent to perform a cyclone
reaction; the
suspended solids in the produced water are effectively captured by the
purifying agent
and coalesce to grow larger and larger; the sludge sinks down and the scum
floats up, so
effective separation is realized and purification of the quality of the
produced water is
achieved.
Compared with the prior arts, the settling oil removal tank, the system and
method
for produced water treatment of the present invention has the following
advantageous
effects:
12
CA 2917959 2017-07-24
CA 02917959 2016-01-15
1. The settling oil removal tank of the present invention uses a vertical flow
tank and
is provided with uniform water collecting and distributing systems. In the
vertical flow
state, oil, water and suspended solids in the produced water are naturally
separated due to
their density differences. The oil removing tank also has the functions of oil
receiving and
sludge discharge, so it significantly improves the working efficiency and
quality in
removing oil from the produced water. Compared with the traditional horizontal
flow oil
removal tank, oil removing efficiency is increased by about 40%, and the
project
investment is saved by about 30%, effectively solving the problems of the low
treatment
efficiency of the oil removal tank in the prior arts.
2. The produced water treatment system of the present invention mainly
comprises a
settling oil removal tanks for a primary treatment and a chemically adjustable
cyclone
reaction separation device for a secondary treatment, which can compensate the
shortcomings of using a physical method alone. As the increasingly strict
environmental
requirements on standardizing and reusing the treated oil-containing sewage,
as well as
the great demands on the stability and standardization of the water treated by
the
produced water treatment and effectively preventing corrosion and scaling, the
present
invention focuses on both water purification and stability of water quality,
and employs
the chemically adjustable cyclone reaction separation deice which can
effectively control
corrosion and scaling of the produced water, to fit for the treatment of the
produced water
which is characterized in having a small density difference in oil and water,
containing a
certain amount of macromolecule organics or having complicated properties. By
adding
water purifying agents (chemical agents), the aqueous property of the produced
water is
improved, and by using a highly efficient reaction device, it realizes the
mixing and
reaction of oil, suspended solids and water purifying agents, as well as the
effective
separation thereof, and achieves water purification and the control of dirt
and corrosive
ions in the water.
3. The present invention can be applied to the treatment of the water produced
from
13
CA 02917959 2016-01-15
SAGD heavy oil recovery at home and abroad, such produced water being
characterized
in having a high temperature, a small density difference between oil and
water, and high
degree of emulsification. After two stages of treatment of the produced water,
content of
oil and suspended solids in the yielding water may be kept down to 15mg / L or
less, and
after an additional process of filtering, the water can meet the reusing
requirements. Thus,
it solves the problem of small grain size of the oil bead, strong stability of
oil and water
and great difficulty in conventional treatment process, when treating the
produced water
having a high temperature, a small oil-water density difference, and high
degree of
emulsification; it also provides a solution for the produced water from heavy
oil recovery
by treating the water and making it satisfy the standard for being reused in a
boiler,
thereby avoiding the environment pollution caused by sewage discharge, and
also saving
clear water to achieve enormous economic benefit.
Drawings
Fig. 1 is the structural schematic view of the settling oil removal tank of
the
present invention.
Fig. 2 is a view along A-A direction in Fig. 1.
Fig. 3 is the structural schematic view of the cyclone reaction separation
tank in
the produced water treatment system of the present invention.
Fig. 4 is the structural schematic view of the cyclone reactor in the produced
water treatment system of the present invention.
Fig. 5 is the structural schematic view of the spray deslagging separation
tank in
the produced water treatment system of the present invention.
Fig. 6 is the structural schematic view of the negative pressure deslagging
separation tank in the produced water treatment system of the present
invention.
14
CA 02917959 2016-01-15
Embodiments
The specific embodiment of the present invention will be explained in detail
with
reference to the accompany drawings; however, such detail description does not
limit the
present invention.
As shown in Fig.1, a settling oil removal tank is disclosed in the embodiment
of
the present invention, comprising a tank body 101, and in the tank body 101, a
hollow
central tubular column 102, a water distribution chamber 103, an oil
collecting groove
104 and a sludge discharging device 105 are provided. The central tubular
column 102 is
vertically provided in the tank body 101, with at least a lower end thereof
being sealed.
The lower end of the central tubular column 102 of the present invention is
connected to
the bottom of the tank body 101 and sealed, and an upper end of the central
tubular
column 102 is connected to the top of the tank body 101 and sealed. A lower
portion of
the central tubular column 102 is communicated with a first water outlet pipe
106 which
extends to the outside of the tank body 101, and is also communicated with a
plurality of
water collecting pipelines 107 located in the tank body 101, whereas the water
collecting
pipelines 107 are provided with water inlets 108 thereon.
The water distribution chamber 103 is connected with a plurality of water
distribution pipelines 109 located in the tank body 101 and a first water
inlet pipe 110
extending out of the tank body 101, the water distribution pipelines 109 being
provided
with water outlets 111 thereon. The oil collecting groove 104 is formed into
an annular
shape around an inner wall of the tank body 101. The oil collecting groove 104
opens
upward, and the cross section thereof is U-shape, as shown in Fig. 1. The oil
collecting
groove 104 is communicated with an oil outlet pipe 112 extending to the
outside of the
tank body 101. The sludge discharging device 105 is provided at the bottom
inside of the
tank body 101.
With reference to Fig.1 and Fig. 2, as a preferable embodiment of the present
invention, each water distribution pipeline 109 comprises a water distribution
main pipe
113 perpendicular to the central tubular column 102 and communicating to the
inside of
CA 02917959 2016-01-15
the central tubular column 102, a water distribution main branch pipe 114
connected with
the water distribution main pipe 113 and perpendicular to it, and a plurality
of water
distribution branch pipes 115 connected with the water distribution main
branch pipe 114.
Each of the water distribution branch pipes 115 is respectively provided with
a water
outlet 111. And the water outlet 111 is in a trumpet shape with an upward
opening, as
shown in Fig. 1.
With continued reference to Fig. 1, in order to make the water distribution in
the
same cross section of the tank body 101 uniform, the water distribution
chamber 103
should be provided in the middle of the tank body 101. The central tubular
column 102 in
the present embodiment is located exactly at the middle of the tank body 101,
and the
water distribution chamber 103 is provided on the central tubular column 102.
The water
distribution chamber 103 of the present embodiment is of an annular shape, and
sleeved
on the central tubular column 102. A plurality of the water distribution main
pipes 113 of
the plurality of the water distribution pipelines 109 are uniformly connected
to the water
distribution chamber 103.
The water collection pipelines 107 employ substantially the same structure as
the
water distribution pipelines, that is, each of the water collection pipelines
107 comprises a
water collecting main pipe perpendicular to the central tubular column 102 and
communicating to the inside of the central tubular column 102, a water
collecting main
branch pipe connected to the water collecting main pipe and perpendicular to
it, and a
plurality of water collecting branch pipes connected to the water collecting
main branch
pipe, each water collecting branch pipe being respectively provided a water
inlet 108.
The structure of the water collection pipeline 107 can be understood with
reference to Fig.
2. The water inlet 108 is in a trumpet shape with a downward opening.
The sludge discharging device 105 is used to remove the sediment in the inflow
fluid. The sludge discharging device in the present embodiment employs a
sludge
discharging device for an oil tank, published in Chinese patent CN2516279Y.
Additionally, as shown in Fig. 1, an overflow pipe 117 is provided in the tank
body 101 with one end thereof located outside of the tank body 101, so that
when the
16
CA 02917959 2016-01-15
liquid level in the tank body 101 is too high, the water in the tank body 101
can be
discharged to the outside of the tank body 101 by the overflow pipe 117.
The working process of the settling oil removal tank of the present invention
will
be explained with reference to Fig. 1: the produced water flows into the water
distribution
chamber 103 through the first water inlet pipe 110, and then flows into the
tank body 101
through the water distribution pipelines 109 and the water outlet 111. The oil
beads with
larger grain sizes in the water float up to the oil layer firstly, and the oil
beads with
smaller grain sizes flow downward together with the water. When the small oil
beads are
flowing downward, part of them, due to their different floating velocities in
the quiet
water and the propulsion of the velocity gradient of the water flow, collide
constantly to
agglomerate to be large oil beads so as to float up. While part of the oil
beads without
floating ability get into the water collection pipelines 107 with water
through water inlets
108, and then get into the central tubular column 102, and then flow out of
the tank body
101 through the first water outlet pipe 106, into the next process; the
floating oil in the oil
layer flows into the oil collecting groove 104, and then flows out through the
oil outlet
pipe 112; The sludge accumulated at the bottom of the tank body 101 enters
into the
sludge discharging device 105, and then, is discharged out via the blowdown
pipe 116.
Through the description of the settling oil removal tank above, the following
beneficial effects can be known:
1) Because the water outlets 111 of the water distribution pipelines open
upward,
when the water flows out at certain velocity from the pipe outlets, the oil
beads have not
only floating velocities in the water obtained because of their own buoyancy
force
(caused by the relative density difference between oil and water), but the oil
beads are
also subjected to the propulsion of the upward perpendicular velocity of the
water flow.
Therefore, the oil beads will reach the oil layer faster, and the time
required to separation
and settlement is shortened.
2) The settling oil removal tank of the present invention employs the way of
distributing water at upper and collecting water at lower. There is always the
process of
convective collision agglomeration between the floating up oil beads, whose
diameters
17
CA 02917959 2016-01-15
are larger because of collision and agglomeration, and the oil beads flowing
downward
with the water, and such process is advantageous to the agglomeration of the
small
particles. Efficiency of the convective collision agglomeration depends on the
number of
the oil beads per unit volume, and the larger the number of the oil beads per
unit volume,
the more the chances to collide and agglomerate, and the higher the
efficiency.
3) Both of the water inlets of the water collection pipelines and the water
outlets
of the water distribution pipelines are in a shape of radical trumpet, so as
to ensure the
uniformity of water distribution and water collection, with the advantages of
simple
structure, easy to install, difficult to be blocked and stable running.
Therefore, water
flowing out of the water distribution pipelines are uniformly distributed to
the horizontal
cross sections in the tank body, and uniformly gathered to flow out of the
tank body.
Since the water distribution pipelines are provided to have the water
distribution main
pipe, the water distribution main branch pipe and a plurality of the water
distribution
branch pipes, the water flows out at a velocity decreasing according to
certain velocity
gradient, reducing the turbulence of the water in the tank body, and the
floating velocity
of the oil will not be affected by the turbulent flow, thereby facilitating
the agglomeration
of the oil beads.
The present invention also discloses a produced water treatment system,
comprising an oil removal tank and a chemically adjustable cyclone reaction
separation
device. The oil removal tank is the settling oil removal tank shown in Fig. 1,
and the first
water outlet pipe 106 is connected to a chemically adjustable cyclone reaction
separation
device. The chemically adjustable cyclone reaction separation device selects
the water
purifying agent needed to be added according to the characteristics of the
produced water,
and at the same time, tries out the time intervals to add the water purifying
agent and the
mix-reaction intensity, and then employs vortex field, whose turbulent flow
decreases
gradually, of the chemically adjustable cyclone reaction separation device,
technically
providing power for the mixing of the water purifying agent and the produced
water, and
the floc produced by the reaction in the outflow water after reaction is
separated from
water by coagulation settlement, realizing the purification of the water.
18
CA 02917959 2016-01-15
The chemically adjustable cyclone reaction separation device in the present
invention can adopt two ways as follows: one is an integral-type device,
mainly aiming at
a cyclone reaction separation tank under normal water quality condition; the
second one
is a divided-type device, mainly aiming at complex water characteristics,
comprising the
two parts of the cyclone reactor and the deslagging separation tank.
The chemically adjustable cyclone reaction separation device employs the
cyclone
reaction separation tank shown in Fig. 3, and the cyclone reaction separation
tank
comprises a tank body 201 and a cyclone reaction center cylinder
longitudinally provided
in the tank body 201, wherein an upper end of the cyclone reaction center
cylinder is
sealed and has an oil-gas exit 214, and a lower end of the cyclone reaction
center cylinder
is communicated with an inner cavity of the tank body 201. The cyclone
reaction center
cylinder is divided into a first-stage cyclone reaction section 202, a second-
stage cyclone
reaction section 203, and a third-stage cyclone reaction section 204 from top
to bottom.
The tank body 201 is fixed with a second water inlet pipe 205 extending into
the
first-stage cyclone reaction section 202, a second water purifying agent pipe
207
extending into the second-stage cyclone reaction section 203, and a flocculant
pipe 208
extending into the third-stage cyclone reaction section 204. The second water
inlet pipe
205 is communicated with a first water purifying agent pipe 206. The upper
portion
inside of the tank body 201 is fixed with a water collecting pipe 209 and an
oil collecting
pipe 210 located above the water collecting pipe, wherein the water collecting
pipe 209 is
provided with an water inlet (not shown in the Figures) and the water
collecting pipe 209
is connected to a second water outlet pipe 211 extending out of the tank body
201; and
the oil collecting pipe 210 is provided with an oil inlet (not shown in the
Figures), besides,
the oil collecting pipe 210 is connected to an oil outlet pipe 212 extending
out of the tank
body 201. The bottom of the tank body 201 is connected to a sludge discharging
pipe 213.
The water, after being treated by the settling oil removal tank, flows into
the cyclone
reaction separation tank through the first water outlet pipe 106 and the
second water inlet
pipe 205, for chemical treatment.
19
CA 02917959 2016-01-15
With continued reference to Fig. 3, in order to facilitate the water
collecting and
oil collecting, both of the water collecting pipe 209 and the oil collecting
pipe 210 are in
an annular shape, and both of the water collecting pipe 209 and the oil
collecting pipe 210
are fixedly sleeved on the upper portion outside the cyclone reaction center
cylinder,
besides, there are a plurality of water inlets uniformly distributed on the
water collecting
pipe 209, and there are a plurality of oil inlets uniformly distributed on the
oil collecting
pipe 210. In order to discharge the gas produced in the sewage out of the tank
body 201, a
vent 215 is provided at the top end of the tank body 201.
Additionally, an axial direction of the second water inlet pipe 205 is
tangential to
the inner wall of the cyclone reaction center cylinder. By feeding water in
tangential
direction, the water flow forms rotating flow state in the cyclone reaction
center cylinder,
and keeps at certain water flow velocity, so as to form velocity gradient,
thereby further
improving the coalescence effect of the floc.
The water coming from the settling oil removal tank flows into the first-stage
cyclone reaction section 202 through the second water inlet pipe 205, and
before the
water enters into the first-stage cyclone reaction section 202, a first kind
of water
purifying agent is added through the first water purifying agent pipe 206, and
reaction
occurs in the first-stage cyclone reaction section 202; in the first-stage
cyclone reaction
section 202, the oil and gas can be separated, and the separated oil and gas
can be
discharged from the oil-gas exit 214 to the tank body 201 and then discharged
from the
vent 215 to the outside of the tank body 201. Then, the water enters into the
second-stage
cyclone reaction section 203, and a second kind of water purifying agent is
added into the
second-stage cyclone reaction section 203 through the second water purifying
agent pipe
207, and flocculation reaction occurs again; lastly, the water goes into the
third-stage
cyclone reaction section 204, and at the same time, organic macromolecule
flocculant is
added to the third-stage cyclone reaction section 204 through flocculant pipe
208,
forming small floc by netting and adhesion; the loose floc formed initially
goes into the
tank body 1 through the bottom of the cyclone reaction center cylinder, and
due to the
upward flow of the water flow and the gravity compression, an sludge bed 216
is formed
CA 02917959 2016-01-15
between the first-stage cyclone reaction section 202, the second-stage cyclone
reaction
section 203, the third-stage cyclone reaction section 204 and the tank body
201. And by
continuing to filtrate, net and adhere the small floc, and pressing the pore
water among
the sludge, compact sludge is formed so as to settle down to the bottom of the
tank body
201. When the sewage passes through the sludge bed, it sufficiently takes
advantage of
the remaining electric potential of the water purifying agent, thereby
reducing the
negative electric potential of the small oil beads, so as to coalesce to be
large oil beads in
order to float up, and the large oil beads go into the oil collecting pipe 210
at the top of
the tank body 201, and then they are discharged from the oil outlet pipe 212;
after being
purified, the water goes into the water collecting pipe 209 and is discharged
from the
second water outlet pipe 211; by opening the valve of the sludge discharging
pipe 213 at
the bottom of the tank body 201 at certain time, the sludge can be discharged.
The structure of the cyclone reaction separation tank in the present invention
is
reasonable and compact, so as to be able to purify the sewage, remove the
sludge and
collect the oil beads rapidly and efficiently, thereby significantly improve
the working
efficiency and working quality in treating sewage containing oil.
The second kind of divided-type device of the chemically adjustable cyclone
reaction separation device of the produced water treatment system in the
present
invention comprises a cyclone reactor and a deslagging separation tank; as
shown in Fig.
4, the cyclone reactor includes a tank body 301, in which a baffle plate 307
for separating
the tank body 301 into a first-stage reaction chamber 302 located in the lower
portion and
a second-stage reaction chamber 303 located in the upper portion, is provided;
a water
inlet is provided on the tank body 301 corresponding to the first-stage
reaction chamber
302, and a third water inlet pipe 304 extending into the first-stage reaction
chamber 302
is provided in the water inlet, while the third water inlet pipe 304 is
connected with the
first water outlet pipe 106 of the settling oil removal tank. A water
purifying agent adding
port and a water outlet are provided on the tank body 301 corresponding to the
second-stage reaction chamber 303, and an agent adding pipe 305 extending into
the
second-stage reaction chamber 303 is provided in the water purifying agent
adding port.
21
CA 02917959 2016-01-15
A third water outlet pipe 306 extending into the second-stage reaction chamber
303 is
provided in the water outlet, and the agent adding pipe 305 is located at a
lower portion
of the second-stage reaction chamber 303 and close to the baffle plate 307,
while the third
water outlet pipe 306 is located in an upper portion of the second-stage
reaction chamber
303. A through hole is provided on the baffle plate 307, and a connecting pipe
308 is
provided in the through hole and communicated with the agent adding pipe 305.
The baffle plate 307 can be provided with a through hole, rather than the
connecting pipe 308, and water in the first-stage reaction chamber 302 goes
directly into
the second-stage reaction chamber 303. Providing the connecting pipe 308
enables the
water coming from the first-stage reaction chamber 302 to sufficiently react
with the
water purifying agent added by the agent adding pipe 305.
The third water inlet pipe 304, the third water outlet pipe 306 and the agent
adding pipe 305 in the present embodiment are all horizontally provided, while
the
connecting pipe 308 is vertically provided.
As shown in Fig. 4, after being added the first kind of water purifying agent,
water from the first water outlet pipe 106 of the settling oil removal tank
goes into the
first-stage reaction chamber 302 at the lower portion of cyclone reactor
through the third
water inlet pipe 304, and after the water purifying agent mixes and reacts
with the sewage
sufficiently, the water passes through the through hole of the baffle plate
307 and goes
into the second-stage reaction chamber 303. By connecting with the agent
adding pipe
305 when going into the second-stage reaction chamber 303, the second kind of
water
purifying agent is added to the sewage, and after the second kind of water
purifying agent
reacts with the first kind of water purifying agent, water mixes and reacts
sufficiently in
the second-stage reaction chamber 303, thus, the floc grows larger, and the
floc sinks
down to the bottom of the tank body 301, and finally, a small amount of
floating oil and
water go into the deslagging separation tank through the third water outlet
pipe 306, for
further treatment. A safe vent 310 is provided at the top of the cyclone
reactor, and a
sewage emptying opening 309 is provided at the bottom of the cyclone reactor.
22
CA 02917959 2016-01-15
The deslagging separation tank in the produced water treatment system of the
present invention of can employ a spray deslagging separation tank, or can
employ a
negative pressure deslagging separation tank.
As shown in Fig. 5, the spray deslagging separation tank includes a tank body
401,
a center cyclone cylinder 402, a spray deslagging device, an oil receiving
device, a sludge
discharging device and a water receiving device. An upper end of the center
cyclone
cylinder 402 is opened, and a lower end thereof is fixed to the bottom of the
tank body
401 and sealed. An annular cavity is formed between the center cyclone
cylinder 402 and
the tank body 401, and at least one communication port 403 for communicating
with the
inner cavity of the tank body 401 is provided at a lower portion of the center
cyclone
cylinder 402; a central portion of the center cyclone cylinder 402 is
connected with a
fourth water inlet pipe 404, while one end of the fourth water inlet pipe 404
is located in
the center cyclone cylinder 402 and the other end thereof is connected with
the third
water outlet pipe 306 of the cyclone reactor. The spray deslagging device is
provided at
an outer side of the upper portion of the center cyclone cylinder 402. The oil
receiving
device is provided on the inner wall of the tank body 401 corresponding to the
upper end
of the center cyclone cylinder 402. The sludge discharging device is provided
at a
position at the bottom of the tank body 401 corresponding to the communication
port 403.
The water receiving device comprises an external water tank 405 which is
mounted on
the upper portion outside of the tank body 401 and a water receiving pipe, and
the lower
end of the water receiving pipe is located in the tank body 401 and
communicated with
the tank body 401, while the upper end of the water receiving pipe is
communicated with
the external water tank 405; and a fourth water outlet pipe 406 is fixedly
connected with
the lower portion of the external water tank 405.
With the spray deslagging device and the oil receiving device, the scum
accumulated at the top inside of the tank body 401 and the treated water can
be separated
constantly and efficiently and can be discharged to the outside of the tank
body 401.
Besides, the spray deslagging device can spray water mist, removing the scum
efficiently,
so as to prevent the scum accumulated at the top inside of the tank body 401
from
23
CA 02917959 2016-01-15
flowing out through the fourth water outlet pipe 406, thereby reducing
influence of the
scum on the water quality of the outflow water and the subsequent processes.
With continued reference to Fig. 5, an axial direction of the fourth water
inlet pipe
404 is tangential to the inner wall of the center cyclone cylinder 402, and an
exit of the
fourth water inlet pipe 404 is located on the inner wall of the center cyclone
cylinder 402.
With the axial direction of the fourth water inlet pipe 404 tangential to the
inner wall of
the center cyclone cylinder 402, water to be treated can go into the center
cyclone
cylinder 402 along the tangential direction, producing high velocity vortex,
and
accelerating the mixing of the sewage to be treated and the water purifying
agent.
With continued reference to Fig. 5, the water receiving pipe comprises a water
receiving annular pipe 407 and a L-shaped guiding pipe 408, and the water
receiving
annular pipe 407 is sleeved outside of the central portion of the center
cyclone cylinder
and fixed to the inner wall of the tank body 401 by a plate with a rib. A
plurality of water
receiving inlets 409 are uniformly distributed at one side of the water
receiving annular
pipe 407 facing downward. One end of the L-shaped guiding pipe 408 is
communicated
with the water receiving annular pipe 407 and the other end thereof penetrates
out of the
tank body 401 and extends into the external water tank 405. One end of the
external water
tank 405 where the L-shaped guiding pipe 408 is located (hereinafter, this end
will be
referred as the upper end) is equipped with a filter. After being purified,
water flows into
the water receiving annular pipe 407 through the water receiving inlets 409
first, and then
flows into the L-shaped guiding pipe 408 through the water receiving annular
pipe 407,
ensuring the water purified in the tank body 401 flowing out uniformly.
As shown in Fig.5, a water level regulator is provided in the external water
tank
405, and the water level regulator comprises an outer cylinder 410, an
adjustable inner
cylinder (not shown in the Figures), a screw rod 412, a mounting frame 413, a
handwheel
414 and a handwheel seat 415, wherein the outer cylinder 410 is fixed to the
bottom in
the external water tank 405, and the upper end of the L-shaped guiding pipe
408 is
located in the outer cylinder 410, while the fourth water outlet pipe 406 is
located outside
of the outer cylinder 410. The adjustable inner cylinder is arranged in the
outer cylinder
24
CA 02917959 2016-01-15
410 and can move up and down, and an outer wall of the adjustable inner
cylinder and an
inner wall of the outer cylinder 410 are maintained to be sealed when the
adjustable inner
cylinder is moving. The screw rod 412 is fixed to the adjustable inner
cylinder, and the
mounting frame 413 is located in the external water tank 405 and above the
outer cylinder
410. A lower end of the handwheel seat 415 is mounted on the mounting frame
413; the
handwheel 414 is mounted on an upper end of the handwheel seat 415; a nut is
mounted
in a central portion of the handwheel 414, and an upper end of the screw rod
412 passes
through the nut.
The water level regulator can regulate the height of the water level in the
external
water tank 405. During production, according to the practical requirement of
the water
quality and change of the water amount, the handwheel 414 is rotated so as to
drive the
screw rod 412 to move up and down, and the screw rod 412 drives the adjustable
inner
cylinder to slide up and down in the outer cylinder 410, so as to regulate the
height of the
outflow water of the external water tank 405. When high liquid level in the
tank body 401
is required to discharge the oil and the slag, the height of the adjustable
inner cylinder can
be increased, making the liquid level in the external water tank 405 higher;
and when low
liquid level in the tank body 401 is required to discharge the water, the
height of the
adjustable inner cylinder can be decreased, to facilitate to discharge the
water in the tank
body 401. With the water level regulator, the floating oil in the tank body
401 is able to
be discharged completely by the oil receiving device, without remaining and
accumulating in the tank body 401, thereby further improving the water quality
of the
outflow water.
The oil receiving device in the present embodiment is an annular oil receiving
groove 424 formed around the inner wall of the tank body 401, the cross
section of the oil
receiving groove 424 being in a U-shape opening upward, and an oil receiving
pipe 416
extending out of the tank body 401 is connected to the oil receiving groove
424.
With continued reference to Fig. 5, the spray deslagging device includes a
slag
receiving groove 417, a slag collecting bucket 418, a slag receiving pipe 419
and a
flushing water pipe 420; only an upper end of the slag receiving groove 417 is
opened,
CA 02917959 2016-01-15
and a hole for the upper end of the center cyclone cylinder 402 to pass
through is
provided on the bottom surface thereof, while center cyclone cylinder 402 is
sealed with
the wall of the hole. The upper end of the center cyclone cylinder 402 is
located in the
slag receiving groove 417, and the bottom surface of the slag receiving groove
417 is a
slope with one end higher than the other, that is, as shown in Fig. 5, the
left end is lower
while the right end is higher; the slag collecting bucket 418 is provided
outside of the
bottom end (that is, the left end) of the slag receiving groove 417; the slag
receiving pipe
419 is connected to the slag collecting bucket 418 and extends out of the tank
body 401.
Moreover, the slag receiving groove 417, the slag collecting bucket 418 and
the slag
receiving pipe 419 are communicated with each other. An upper end of the
flushing water
pipe 420 is fixed above of the center cyclone cylinder 402, and a spray nozzle
is
connected to the flushing water pipe 420, while a lower end of the flushing
water pipe
420 penetrates out of the tank body 401 and is connected with the tap water.
With continued reference to Fig. 5, the spray nozzles in the present
embodiment
include an upper layer spray nozzle 421 and a lower layer spray nozzle 422.
There are at
least two upper layer spray nozzles 421, and they are arranged uniformly
around the
outside of the upper end of the flushing water pipe 420, and the flushing
water pipe 420,
between and below the adjacent two upper layer spray nozzles 421, is provided
with the
lower layer spray nozzle 422. The upper layer spray nozzles 421 and the lower
layer
spray nozzle 422 are arranged in two layers and staggered, making the flushing
effect
better. In practical operation, when the thickness of the scum is relatively
small and the
density is relatively lighter at the upper portion of the center cyclone
cylinder 402, it can
employ only the lower layer spray nozzle 422; and when the thickness of the
scum is
relatively thicker, both of the upper layer spray nozzles 421 and the lower
layer spray
nozzle 422 can be employed at the same time.
As shown in Fig. 5, the sludge discharging device can employ the sludge
discharging device for an oil tank, published in the Chinese patent
CN2516279Y, whose
structures and principles are not described in detail here. Additionally, an
overflow pipe
423 is fixed at the position inside the tank body 401 near the outer upper end
of the slag
CA 02917959 2016-01-15
receiving groove 417, the upper end port of the overflow pipe 423 is
communicated to the
inside cavity of the tank body 401, and the middle of the overflow pipe 423
passes
through the tank body 401 and extends out of the tank body 401, while the
lower end of
the overflow pipe 423 is connected to the discharging line of the sewage
treatment station,
so that when the amount of the inflow water of the fourth water inlet pipe 404
increases
suddenly and exceeds the treatment load of the spray deslagging separation
tank in short
time, the redundant water flows out of the tank body 401 through the overflow
pipe 423,
preventing the untreated water goes directly into the external water tank 405,
which
otherwise may result in poor quality of the outflow water.
The working process of the spray deslagging separation tank is explained with
reference to Fig. 5. Firstly, the produced water, after being treated by the
cyclone reactor,
flows into the fourth water inlet pipe 404 through the third water outlet pipe
306, and
then flows into the middle of the center cyclone cylinder 402, while the water
flow
rotates and flows downward in the center cyclone cylinder 402, and the
produced water
sufficiently mixes and reacts with the water purifying agent to form the oil
residue, and
the oil residue is separated gradually from the treated water in the center
cyclone
cylinder 402 and moves upward, and the oil residue rising up to the top of the
center
cyclone cylinder 402 forms a scum layer; the floating oil produced by the
reaction of the
produced water and the water purifying agent go into the oil receiving groove
424, and
then is discharged through the oil receiving pipe 416 to the outside of the
tank body 401.
The sediment and other impurities in the produced water, and the sludge
produced by the
reaction of the produced water and the water purifying agent deposit to the
bottom of the
tank body 401, and is collected by the negative pressure sludge-discharging
device and
then discharged to the outside of the tank body 401 via the sludge discharging
pipe 425.
The pressurized water from the flushing water pipe 420 is ejected out through
the spray
nozzles, and the scum accumulated at the top of the center cyclone cylinder
402 are
blown to the inside of the slag receiving groove 417, while the scum in the
slag
receiving groove 417 slides into the slag collecting bucket 418 along the
bottom slope
surface of the slag receiving groove 417, and then is discharged out of the
tank body 401
27
CA 02917959 2016-01-15
through the slag receiving pipe 419. Finally, the treated water flows into the
tank body
401 through the communicating port 403, and into the adjustable inner cylinder
through
the water receiving annular pipe 407 and the L-shape guiding pipe 408. Water
flowing
out from the upper end of the adjustable inner cylinder goes into the external
water tank
405, and goes into the subsequent treatment equipment by being discharged via
the
fourth water outlet pipe 406.
As shown in Fig. 6, the deslagging separation tank is a negative pressure
deslagging separation tank, and the negative pressure deslagging separation
tank
comprises a tank body 501 and a cylinder body 502 provided in the tank body
501,
wherein an upper end of the cylinder body 502 is opened and a lower end
thereof is fixed
to the tank body 501 and is sealed; an annular cavity 517 is formed between
the cylinder
body 502 and the tank body 501; a lower portion of the cylinder body 502 has
at least one
exit 503 communicating with an inner cavity of the tank body 501; a slag
receiving
funnel 504 is fixed and mounted to the upper portion of the cylinder body 502,
and a
bottom of the slag receiving funnel 504 is connected with a slag discharging
pipe 505
extending out of the tank body 501; a fifth water inlet pipe 506 is connected
with the
central portion of the cylinder body 502 and extends into the cylinder body
502 along the
tangential direction of the cylinder body 502; an annular oil receiving groove
508, whose
cross-section is in a U-shape with opening upward, is formed on the inner wall
of the
upper portion of the tank body 501, and an oil receiving pipe 509 extending
out of the
tank body 501 is connected to the oil receiving groove 508; an annular packing
layer 507
is fixed in the central portion of the annular cavity 517, and an annular
water receiving
pipe 510 is provided in the annular cavity 517 above the packing layer 507. A
fifth water
outlet pipe 511 extending out of the tank body 501 is connected to the water
receiving
pipe 510.
With continued reference to Fig. 6, a first annular sludge suction pipe 512
located
in the annular cavity 517 is fixed to the bottom of the tank body 501, and
there are two
first sludge suction pipes 512 in the present embodiment, arranged up and down
respectively. A second annular sludge suction pipe 513 is fixed above the
packing layer
28
CA 02917959 2016-01-15
507. The sludge suction holes are respectively distributed on the bottom
surfaces of the
first annular sludge suction pipes 512 and the second annular sludge suction
pipe 513.
The first annular sludge suction pipes 512 and the second annular sludge
suction pipe 513
are respectively communicated with the sludge discharging pipes 514 extending
out of
the tank body 501. The two first annular sludge suction pipes 512 can be
communicated
with each other so as to use one sludge discharging pipe 514, or can each use
one sludge
discharging pipe 514. The first annular sludge suction pipes 512 and the
second annular
sludge suction pipe 513 are of the same structure and are equipment known in
the prior
art, so the details thereof will not be explained.
Additionally, as shown in Fig. 6, an overflowing port is provided in the tank
body
501 located above the annular water collection pipe 510, and an overflow pipe
515 is
fixedly connected to the overflowing port. When the amount of the inflow water
in the
negative pressure deslagging separation tank is too large, it can be
discharged out of the
tank through the overflow pipe 515, preventing the untreated water from going
directly
into the water collecting pipe 510 and affecting the quality of the outflow
water. Besides,
an annular stopper ring 516 is fixed to the inner wall of the middle portion
of the tank
body 501, and the packing layer 507 is seated on the annular stopper ring 516,
so that the
annular stopper ring 516 functions to support, fix and position-limit the
packing layer 507.
The packing layer 507 is fixed with a U-shape vent-balancing pipe 217, and the
U-shape
vent-balancing pipe 217 passes through the packing layer 507 to make one
portion
thereof to be located at the upper portion of the packing layer 507, and one
portion
thereof located at the lower portion of the packing layer 507. The U-shape
vent-balancing
pipe 217 is used to balance the pressure between the upper portion and lower
portion of
the packing layer 507 in the annular cavities 517, so as to prevent pressure-
suppression.
The packing layer 507 can adopt a slant plate packing layer made by
ethylene-propylene copolymer, and the slant plate packing layer has excellent
chemical
properties, well stability, small specific gravity, smooth surface and well
sludge-slip
effect, avoiding the phenomenon of filling broken and loss.
29
CA 02917959 2016-01-15
The working process of the negative pressure deslagging separation tank is
explained with reference to Fig. 6. The produced water, after being treated by
the cyclone
reactor, goes into the fifth water inlet pipe 506 through the third water
outlet pipe 306,
and goes into the cylinder body 502 in tangential direction through the fifth
water inlet
pipe 506. The produced water in the cylinder body 502 sufficiently reacts with
the water
purifying agent through hydraulic rotational flow, and the floc produced by
the reaction
floats up to the water surface by means of the dissolution gas released in the
sewage so as
to accumulate to be the scum, and the water flowing at the lower portion flows
from the
exit 503 of the cylinder body 502 to enter into the annular cavity 517, then,
after the clear
water separated by the settlement passes through the packing layer 507 from
top to
bottom, and the floc in the water is further held up, thereby further
purifying the water
after passing through the packing layer 507, while the purified clear water
above the
packing layer 507 goes into the water collecting pipe 510, and finally is
discharged out of
the tank body 501 through the fifth water outlet pipe 511. The floating up
scum goes into
the slag receiving funnel 504 first, and then is discharged out of the tank
body 501
through the slag discharging pipe 505. After the floating oil is collected by
the oil
receiving groove 508, it is discharged out of the tank body 501 through the
oil receiving
pipe 509. The sludge deposited on the bottom of the tank body 501 and the
upper portion
of the packing layer 507 are termly discharged out of the tank body 501
through the first
annular sludge suction pipes 512 and the second annular sludge suction pipe
513
respectively.
The present invention also discloses a treatment method for the produced
water,
including the following steps:
1) removing oil by settlement, wherein the settling oil removal tank shown in
Fig.
1 is used, and due to the density differences of oil, water and the suspended
solids in the
produced water, most of the oil floats up while the suspended solids sink
down, therefore,
oil and suspended solids are separated naturally, and the remaining small
portion of oil
and suspended solids go into a subsequent procedure;
2) removing oil by cyclone reaction, wherein after being treated in step 1),
the
CA 02917959 2016-01-15
produced water flows into a chemically adjustable cyclone reaction separation
device,
and is added with 2 to 3 kinds of water purifying agents to perform a chemical
cyclone
reaction; the suspended solids in the produced water are effectively captured
by the
purifying agent and coalesce to grow larger and larger; the sludge sinks down
and the
scum floats up, so effective separation is realized and purification of the
quality of the
outflow water is achieved.
The produced water treatment method in the present invention adopts two-stage
treatment establishment, while the primary-stage employs physical treatment
method of
the settling oil removal tank, and the second-stage employs chemical treatment
method
with the chemically adjustable cyclone reaction separation device for cyclone
reaction, to
make up the shortage of using the physical treatment method only, and take
both of the
water purification and stability of water quality into consideration,
satisfying the
increasingly strict environmental protection requirement of the treated
produced water for
reuse.
Specifically, the high-temperature produced water from heavy oil recovery
firstly
goes into the vertical settling oil removal tank. The settling oil removal
tank is provided
with uniform water collection and water distribution system, and employs the
way of
distributing water at upper and collecting water at lower. Shape of a radical
trumpet is
used in water distribution and in water collection, ensuring the uniformity in
water
distribution and water collection. After the produced water flows upward and
out of the
water distribution pipe at certain velocity in vertical flow state, the oil
has not only
floating velocity in the water obtained because of its floating, but the oil
droplet is also
subjected to the propulsion of the upward perpendicular velocity of the water
flow.
Therefore, the oil will reach the oil layer faster, and the time required to
separation and
settlement is shortened. Besides, when the oil is rising, it collides and
agglomerates to
form a floating oil droplet and becomes larger directly. And there is always
the process of
convective collision agglomeration between the floating up oil beads and the
oil beads
flowing downward with the water flow, in this way, the oil beads agglomerate
to be large
oil droplet which is beneficial for floating up, thereby shortening the time
for floating up
31
CA 02917959 2016-01-15
and increasing the oil removal efficiency. The oil floating up to the upper
surface of the
produced water enters into the oil receiving groove in the inner wall of the
settling oil
removal tank, and then is discharged out of the settling oil removal tank. The
sludge in
the produced water deposits to the bottom of the settling oil removal tank and
is
discharged out via the negative pressure sludge-discharging device.
After being treated by the settling oil removal tank, the produced water goes
into
the chemically adjustable cyclone reaction separation device. The chemically
adjustable
cyclone reaction separation device selects the water purifying agent needed to
be added
according to the characteristics of the produced water, and at the same time,
tries out the
time intervals to add the water purifying agent and the mix-reaction
intensity, and then
employs vortex field, whose turbulent flow decreases gradually, of the
chemically
adjustable cyclone reaction separation device, technically providing power for
the mixing
of the water purifying agent and the produced water, and the floc produced by
the
reaction in the outflow water after reaction is separated from water by
coagulation
settlement, realizing the purification of the water. At the same time, the
small amount of
oil in the produced water floats up and is collected.
The chemically adjustable cyclone reaction separation device can employ an
integral-type device (only a single device, see, for example, the cyclone
reaction
separation tank shown in Fig. 3), or can employ a divided-type device
(including two
devices, that is, the combination of the cyclone reactor shown in Fig. 4, and
the spray
deslagging separation tank shown in Fig. 5 or the negative pressure deslagging
separation
tank shown in Fig. 6). With regard to the produced water with polymer or super-
heavy oil,
SAGD, the oil beads are of small grain sizes, large viscosities, and it is
difficult for the oil
and water to be separated; as for the produced water containing gas, because
there is
much dissolution gas in it and it is not stable, the floc tends to float up,
and since the
scum layer accumulates at the top of the tank for a long time, the thickness
of the scum
layer increases, and the scum flows out through the water outlets and goes
into the next
process, causing the content of oil and suspended solid in the outflow water
to exceed the
standard, and bringing a treatment burden to the subsequent process. The spray
32
CA 02917959 2016-01-15
deslagging separation tank shown in Fig. 5 is used. A slag receiving groove is
provided at
the top of the tank, and a water mist nozzle is provided at the middle portion
of the slag
receiving groove. The scum is blown into the slag receiving groove by the
ejected-mist,
and then is discharged out of the tank, while the sludge settles down to the
bottom of the
spray deslagging separation tank, and is discharged out of the tank through
the negative
pressure sludge discharging device. And the negative pressure deslagging
separation tank
in Fig. 6 collects the scum floating up the liquid surface of the tank by
means of the
negative pressure, and then discharge it out of the tank, while the sludge
settles down to
the bottom of the negative pressure deslagging separation tank, and is
discharged out of
the tank through the negative pressure sludge discharging device, ensuring the
water
quality of the outflow water.
After the produced water has been treated by the two-stage treatment of the
present invention, the oil and suspended solid containing in the outflow water
can be kept
to be below 15mg/L, and can satisfy the reuse requirement with the assistant
post-filtration. Therefore, for the produced water with high-temperature, low
oil-water
density difference and high emulsification degree, the problems of small grain
sizes, high
oil-water stability and high degree of normal treatment difficulties are
solved. Therefore,
the produced water from heavy oil recovery can satisfy the treatment standard
and can be
reused in the boiler, so as to prevent the discharge of the produced water
from heavy oil
recovery from polluting the environment, and at the same time, clear water is
saved and
significant economy benefit is produced.
The exemplary embodiment of the present invention has been described in
detail.
However, such detail description is not used to limit the scope of the present
invention.
A person skilled in the art can make various modifications and equivalent
substitutions
within the spirit and protection scope of the present invention, while such
modifications
and substitutions should be construed to fall into the protection of the
present invention.
Therefore, the combination of the features described in detail previously
doesn't
necessarily mean to implement the present invention in the widest scope, but
alternatively, only teaches the specifically described exemplary embodiment of
the
33
CA 02917959 2016-01-15
present invention. Besides, in order to obtain the additional useful
embodiment of the
present invention, various features taught in the description can be combined
in various
ways, however, these are not illustrated specifically.
34
