CA2917959C

CA2917959C - Settling oil removal tank, system and method for produced water treatment

Info

Publication number: CA2917959C
Application number: CA2917959A
Authority: CA
Inventors: Pingping Yang; Qiang Huang; Aijun Wang; Jun MEI; Chunlin LUO; Lei Fu; Zhiqing Zhang; Shuai ZHENG; Jingdu Zhou; Jiangping Ning; Yong Ling; Li Jiang
Original assignee: Xinjiang Petroleum Engineering Design Co Ltd
Current assignee: Xinjiang Petroleum Engineering Design Co Ltd
Priority date: 2015-10-30
Filing date: 2016-01-15
Publication date: 2018-02-27
Anticipated expiration: 2036-01-15
Also published as: CA2917959A1; CN106621484A

Abstract

The present invention discloses a settling oil removal tank, and a system and method for produced water treatment. The settling oil removal tank comprises a tank body, which is provided with a central tubular column, a water distribution chamber, an oil collecting groove, and a sludge discharging device provided at the bottom of the tank body. The central tubular column is 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, and a lower portion thereof communicating with a plurality of water collecting pipelines which are provided with water inlets thereon; the water distribution chamber is connected to a plurality of water distribution pipelines and a first water inlet pipe, and the water distribution pipelines are provided with water outlets; the oil collecting groove is formed into an annular shape around the inner wall of the tank body. The settling oil removal tank of the present invention adopts a vertical flow tank and is provided with a uniform water collection and distribution system, so that oil, water and suspended solids can be naturally separated due to their density differences in the vertical flow state. The produced water treatment system of the present invention comprises a settling oil removal tank for primary treatment and a chemically adjustable cyclone reaction separation device for secondary treatment; after the above two levels of treatment of the produced water, the oil and suspended solids in the water may be kept down to 15mg/L or less.

Description

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 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 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 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 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 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.

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.

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 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 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 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 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:

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 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.

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 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 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 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.

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 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.

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 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.

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.

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 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 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, 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 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 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 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.

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 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 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 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 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 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.

Claims

1. 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.

2. The produced water treatment system according to claim 1, wherein 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 flocculant pipe extending into the third-stage cyclone reaction section; the second water inlet pipe is communicated with a first water purifying agent pipe;
the upper portion inside of the tank body is fixed with a water collecting pipe and an oil collecting pipe located 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.

3. The produced water treatment system according to claim 2, wherein 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.

4. The produced water treatment system according to claim 2, wherein an axial direction of the second water inlet pipe is tangential to the inner wall of the cyclone reaction center cylinder.

5. The produced water treatment system according to claim 1, wherein 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 located in the lower portion and a second-stage reaction chamber located 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-stage 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.

6. The produced water treatment system according to claim 5, wherein 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 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 outside 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.

7. The produced water treatment system according to claim 6, wherein 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 outside 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 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.

8. The produced water treatment system according to claim 6, wherein 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.

9. The produced water treatment system according to claim 6, wherein 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 outside 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 above 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.

10. The produced water treatment system according to claim 5, wherein 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 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 body; 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 packing 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.

11. A method for treating produced water, comprising the steps of.
1) removing oil by settlement, wherein a settling oil removal tank 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, thereby most of the oil and suspended solids being separated naturally from the produced water, 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 for cyclone reaction, and is added with 2 to 3 kinds of water purifying agents to perform a chemical cyclone reaction; the oil and the suspended solids in the produced water are effectively captured by the water 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.