Oilfield wastewater reuse chemical softening treatment unit

Abstract

This utility model discloses a chemical softening treatment device for oilfield wastewater reuse, which is dynamically controlled by a PLC. It includes a mechanically accelerated mixing tank, a first contact coagulation tank, a second contact coagulation tank, an inclined tube sedimentation tank, and a softened water tank, sequentially connected via an oilfield wastewater transport pipeline. The tanks of the mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank are arranged in a square configuration, adjacent to each other. The tank of the inclined tube sedimentation tank is fixedly located beside and adjacent to the second contact coagulation tank and the softened water tank. Each of the mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank has a stirrer fixedly installed from the top inwards. Multiple dosing ports and vent pipes are also provided from the top of the tanks. Each tank has an online water quality probe built into it.

Description

Technical Field

[0001] This utility model relates to oilfield wastewater treatment, specifically to a highly efficient integrated treatment device that removes calcium and magnesium ions, suspended solids, and oils from wastewater through a chemical softening process, suitable for hardening treatment of produced water from oilfields for reuse. Background Technology

[0002] Currently, the softening equipment used in oilfields for wastewater treatment suffers from the following problems due to the unreasonable distribution of water tanks and the use of single-point dosing for each tank: 1) Low utilization rate of the agent and uneven mixing lead to waste of the agent and unstable softening efficiency; 2) Difficulty in sludge treatment: Chemical sludge production is large, traditional sedimentation tanks have poor separation effect, and subsequent dewatering costs are high; 3) Poor resistance to water quality fluctuations: Manually controlling the dosage is difficult to cope with changes in the water quality of oilfield wastewater, which can easily lead to excessive hardness in the effluent; 4) Large equipment footprint: The non-modular design makes on-site installation complicated and difficult to adapt to the needs of decentralized oilfields. Utility Model Content

[0003] The purpose of this utility model is to provide a chemical softening treatment device for oilfield wastewater reuse. The entire process is automatically controlled, which can solve the above-mentioned technical problems and has the advantages of high efficiency, simple operation and long duration.

[0004] This utility model relates to a chemical softening treatment device for oilfield wastewater reuse, which is dynamically adjusted and controlled by a PLC. It includes a mechanically accelerated mixing tank, a first contact coagulation tank, a second contact coagulation tank, an inclined tube sedimentation tank, and a softened water tank, which are connected in sequence through an oilfield wastewater transport pipeline. The water tanks of the mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank are arranged in a square with close proximity. The water tank of the inclined tube sedimentation tank is fixedly located next to the second contact coagulation tank and the softened water tank, and is arranged close to each other. The mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank are all equipped with agitators fixedly installed from the top of the water tank inwards. At the same time, multi-stage dosing ports and vent pipes are provided from the top of the water tank, and an online water quality probe is built into each water tank.

[0005] Preferably, the impeller diameter of the agitator in the mechanically accelerated mixing tank is 500 mm, the rotation speed is 72 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.4; the impeller diameter of the agitator in the first contact coagulation tank is 700 mm, the rotation speed is 45 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.5; the impeller diameter of the agitator in the second contact coagulation tank is 1100 mm, the rotation speed is 30 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.9.

[0006] Preferably, the inclined tube sedimentation tank is equipped with a sludge scraper and an inclined tube device. The sludge scraper is installed from the top of the water tank inward and passes through the inclined tube device to the bottom of the water tank.

[0007] Preferably, each of the multi-stage dosing ports has two dosing ports that are respectively connected to high-concentration and low-concentration dosing devices.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: The oilfield wastewater reuse chemical softening treatment unit includes a chemical softening reaction unit and a solid-liquid separation unit.

[0009] Compared with the prior art, the present invention has the following advantages: the oilfield wastewater reuse chemical softening treatment device of the present invention has a small footprint, a high degree of integration, a highly integrated process structure, and high and stable effluent quality.

[0010] By setting up multi-stage mixing and coagulation, adjusting the stirring intensity in different operating units, regulating the hydraulic conditions of each stage of coagulation, and controlling the flow velocity gradient in each operating unit, a good coagulation effect is achieved, and the hardness of the effluent is stabilized. The dosage of chemical agents is reduced, and the coagulation reaction is promoted by sludge recirculation, thus reducing the dosage of flocculants. The operating load and sludge thickening effect are effectively improved. The inclined plate sedimentation has a good sedimentation effect on flocs, which improves the operating load. The lower part of the sedimentation separation tank is designed according to the structure of a sludge thickening tank, which greatly improves the sludge thickening effect, and the discharged sludge can be directly dewatered.

[0011] It has a high degree of automation. By developing an advanced integrated control system, it can realize automatic control of pH adjustment and sedimentation tank operation, thereby improving commissioning and operation efficiency. It can meet the independent control of mixing, coagulation and sedimentation separation, which facilitates targeted process optimization of each operating unit. Attached Figure Description

[0012] Figure 1 This is a plan view of the chemical softening treatment device for oilfield wastewater reuse in this utility model.

[0013] Figure 2 This is a system pipeline diagram of the chemical softening treatment device for oilfield wastewater reuse in this utility model.

[0014] Figure 3 This is an internal structural diagram of the chemical softening treatment device for oilfield wastewater reuse in this utility model. Detailed Implementation

[0015] To provide a clearer understanding of the technical features, objectives, and beneficial effects of this utility model, it will now be described in further detail with reference to the accompanying drawings and specific embodiments. However, this should not be construed as limiting the scope of implementation of this utility model.

[0016] like Figure 1 , Figure 2 and Figure 3 As shown, the chemical softening treatment device for oilfield wastewater reuse in this utility model includes a mechanically accelerated mixing tank 8, a first contact coagulation tank 15, a second contact coagulation tank 13, an inclined tube sedimentation tank 1, and a softened water tank 4, which are sequentially connected through an oilfield wastewater transport pipeline. Wherein: The mechanically accelerated mixing tank 8 includes a water tank, a first agitator 4 fixedly installed from the top of the water tank inwards, and two primary dosing ports 6 connected to a multi-stage dosing device. The first agitator 4 has a blade diameter of 500 mm, a rotation speed of 72 r / min, and a blade diameter to water tank inner diameter ratio of 0.4. This provides high-intensity, short-time mixing for the wastewater entering the mechanically accelerated mixing tank 8, ensuring rapid mixing without forming large flocs. The two primary dosing ports 6 are mainly used for adding pH adjusters and coagulants. Each dosing port is 300 mm apart to ensure they do not interfere with each other. Thanks to the high-intensity mixing of the first agitator 4, each agent can be mixed rapidly and intensely, and the agents can quickly and evenly diffuse and complete the initial charge neutralization / compression of the double electric layer.

[0017] The first contact coagulation tank 15 includes a water tank, a second agitator 7 installed from the top of the water tank inwards, and two secondary dosing ports 6 connected to a multi-stage dosing device. Inside the water tank, there are baffles and a reaction guide (not shown in the figure). The second agitator 7 has a blade diameter of 700 mm, a rotation speed of 45 r / min, and a blade diameter to water tank inner diameter ratio of 0.5, providing moderate energy to promote the collision of destabilized particles and the formation of small, dense micro-floc nuclei. The two secondary dosing ports 6 are used to add coagulant aids (such as PAM) or to return unreacted sludge.

[0018] The second contact coagulation tank 13 includes a water tank, a third agitator 14 installed from the top of the water tank inwards, and two secondary dosing ports 6 connected to a multi-stage dosing device. Inside the water tank, there are baffles and a reaction guide. The third agitator 14 has a blade diameter of 1100 mm, a rotation speed of 30 r / min, and a blade diameter to water tank inner diameter ratio of 0.9. This provides low-intensity, long-term agitation, promoting the slow collision and aggregation of micro-flocculations into dense, high-strength large flocs, preventing floc breakage. The two secondary dosing ports 6 are used to add coagulant aids (such as PAM) or to return unreacted sludge.

[0019] The inclined tube sedimentation tank 1 includes a water tank, a sludge scraper 2 installed from the top of the water tank inwards, and an inclined tube device 3. The inclined tube sedimentation tank 1 allows the sedimentation separation zone to maintain a high upward flow velocity, reducing the system's footprint.

[0020] The softening tank 5 includes a water tank, a first agitator 4 fixedly installed from the top of the tank, and two tertiary dosing ports 6 connected to a multi-stage dosing device. The two tertiary dosing ports 6 add pH-adjusting agents (such as acids or alkalis). All dosing ports 6 are connected to high-concentration and low-concentration agent dosing devices respectively, allowing for independent adjustment of the dosage at each stage. Specifically, the dosage of each agent can be independently adjusted based on real-time water quality (online pH monitoring) and treatment effects (such as floc formation). For example, if the raw water turbidity suddenly increases, the amount of primary coagulant can be increased, while the amount of secondary coagulant aid can be fine-tuned. If small and scattered flocs are found, the amount of secondary coagulant aid can be increased. When pH fluctuates, precise adjustments can be made at the alkali / acid addition points. The multi-stage dosing system enables precise, phased dosing, greatly avoiding agent waste and insufficiency.

[0021] In this invention, the mechanically accelerated mixing tank 8, the first contact coagulation tank 15, the second contact coagulation tank 13, and the softened water tank 5 are all the same size and arranged in a square, closely adjacent arrangement. The inclined tube sedimentation tank 1 is fixedly installed on the common side of the second contact coagulation tank 13 and the softened water tank 5, and is also arranged adjacent to each other. A sludge discharge screw pump 10, a circulating screw pump 11, and a control cabinet 17 are fixedly installed on the common side of the mechanically accelerated mixing tank 8 and the first contact coagulation tank 15. Both the sludge discharge screw pump 10 and the circulating screw pump 11 are connected to the mechanically accelerated mixing tank 8, the first contact coagulation tank 15, the second contact coagulation tank 13, the inclined tube sedimentation tank 1, and the softened water tank 4 via their respective oilfield wastewater transport pipelines, and are controlled by a pH meter, sludge level meter, and flow meter installed in the control cabinet 17 and the analysis instrument box 12. The use of the circulating screw pump 11 for sludge recirculation helps unreacted flocculant continue to participate in the flocculation reaction, promotes floc growth, and accelerates sludge sedimentation. The sludge return ratio is 3% to 7% of the influent volume. When the sludge settling performance is poor and the sludge flocs are small, the settling performance can be changed by reducing the sludge return ratio and increasing the bottom sludge concentration.

[0022] After pretreatment, the produced water from the oilfield enters the chemical softening treatment device of this utility model through the device inlet 18. According to the design of the flow channel, it passes through the mechanical acceleration mixing tank 8, the first contact coagulation tank 15 and the second contact coagulation tank 13 in sequence, and then enters the inclined tube sedimentation tank 1 and the softening water tank 5 in sequence. Finally, it enters the product water tank through the device outlet 19 set in the softening water tank 5 for reuse.

[0023] Reaction guides are installed in contact coagulation tanks 15 and 13. These guides use an up-and-down baffle method to distribute water, which increases the water flow path and extends the effective hydraulic residence time. This ensures that each stage of reaction has enough time to proceed, allowing the reagents to fully exert their effects. At the same time, the design of the reaction guides can control the flow velocity gradient, preventing excessive shear force in the later stage of flocculation from causing the mature flocs to break.

[0024] In summary, the oilfield wastewater reuse chemical softening treatment device of this utility model can effectively solve the problem of "low reagent utilization" through multi-stage and multi-point dosing, effectively solve the problem of "difficult sludge treatment" through graded stirring with decreasing intensity gradient, and effectively solve the problem of "poor resistance to water quality fluctuations".

Claims

1. A chemical softening treatment device for oilfield wastewater reuse, characterized by fully automatic dynamic adjustment and control by PLC, wherein... It includes a mechanically accelerated mixing tank, a first contact coagulation tank, a second contact coagulation tank, an inclined tube sedimentation tank, and a softened water tank, which are connected in sequence through an oilfield wastewater transport pipeline. The water tanks of the mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank are arranged in a square with close proximity. The water tank of the inclined tube sedimentation tank is fixedly located next to the second contact coagulation tank and the softened water tank, and is arranged close to each other. The mechanically accelerated mixing tank, the first contact coagulation tank, the second contact coagulation tank, and the softened water tank are all equipped with agitators fixedly installed from the top of the water tank inwards. At the same time, multi-stage dosing ports and vent pipes are provided from the top of the water tank, and an online water quality probe is built into each water tank.

2. The oilfield wastewater reuse chemical softening treatment device according to claim 1, characterized in that, The impeller diameter of the agitator in the mechanically accelerated mixing tank is 500 mm, the rotation speed is 72 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.4; the impeller diameter of the agitator in the first contact coagulation tank is 700 mm, the rotation speed is 45 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.5; the impeller diameter of the agitator in the second contact coagulation tank is 1100 mm, the rotation speed is 30 r / min, and the ratio of the impeller diameter to the inner diameter of the water tank is 0.

9.

3. The oilfield wastewater reuse chemical softening treatment device according to claim 1, characterized in that, The inclined tube sedimentation tank is equipped with a sludge scraper and an inclined tube device. The sludge scraper is installed from the top of the water tank inward and passes through the inclined tube device to the bottom of the water tank.

4. The oilfield wastewater reuse chemical softening treatment device according to claim 1, characterized in that, Each of the multi-stage dosing ports is equipped with two dosing ports that are respectively connected to high-concentration and low-concentration dosing devices.

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