Industrial oil-water separator

Jinan Lufa Environmental Protection Technology Co., Ltd
industryInstructions for oil-water separator
1、 Overview of Industrial Oil Water Separators
With the rapid development of industry and the strengthening of environmental awareness, oil-water separation technology has received more attention from people. Oil water separation is a category of liquid-liquid separation, and different methods should be used for liquid-liquid separation based on the different states of oil in water and the requirements for treatment effectiveness. The separation of oily wastewater can achieve the effect of one inlet and two outlets, with oily wastewater entering. Separating oil from the top (such as separating water to obtain clean oil) and producing clean water from the bottom is both energy-saving and environmentally friendly.
The combination of oil and water is a mixture of immiscible liquids. Water is dispersed in oil as tiny droplets, known as the "water in oil" type (symbol W/O), where water is the dispersed phase and oil is the continuous phase; What we are discussing here is the dispersion of oil in water in extremely small droplets, known as the "water in oil" type (symbol O/W), where oil is the dispersed phase and water is the continuous phase. The form of oil in water can be divided into five physical forms:
Free state oil (floating oil): The particle size of the oil is ≥ 100 μ m, and it floats on the water surface as a continuous phase oil film. After standing still, it can quickly float up. About 60% of the oil in the sewage.
Dispersed oil: Fine oil droplets with a particle size of 10-100 μ m, which have low stability in water and combine with each other to form a floating oil after standing for a period of time.
Emulsified oil: Oil with particle size less than 10 μ m is mostly 1-2 μ m. The emulsified state of this water in oil is very stable.
Dissolved oil: The particle size of oil is smaller than that of emulsified oil droplets, and the solubility of oil in water is very low, generally only 5-10 mg/L. It is oil that truly dissolves in water.
Adhesive oil on solids: It is formed by the solid as the core, which means that oil on solid particles is wrapped in water.
The technical conditions of this device fully comply with the national regulations for GB12917-91 oil-water separation device. After treatment by this device, the discharged water quality and oil content meet the "GB8978-96 Comprehensive Wastewater Discharge Standard".
2、 Working principle
This device is designed based on the principle of gravity separation. Oil and sewage enter the separation chamber. Due to the large wetted surface area and low flow rate of the coarse-grained element, they aggregate into larger oil droplets and float to the top oil collection chamber. Oil droplets containing smaller particles enter the second and third coarse-grained devices in sequence. Due to the special aggregation function of the coarse-grained element, residual fine oil droplets aggregate into larger oil droplets and separate from water before rising to the top oil collection chamber. The clean water at the bottom is discharged through the discharge outlet.
The dirty oil accumulated in the first and second oil collection chambers is automatically discharged through an oil level detector, an automatic oil discharge device, and an oil discharge valve. After the third stage, the coarse granulation device belongs to the fine separation system, and the amount of dirty oil is very small. It can be manually drained regularly. In order to ensure the separation of high viscosity dirty oil and its smooth discharge from the dirty oil tank, electric heating devices are installed in the first and second stage separation chambers, which are automatically controlled to maintain the temperature within 25 ℃~50 ℃.
According to the level of oil and sewage in the sewage tank, automatic startup and shutdown can be performed. Users can request and configure a UGK-15 float level controller to achieve automatic operation. Users can also install an oil concentration meter as needed to automatically monitor whether the discharged water meets the emission standards. When the standards are met, the water will be automatically discharged without the need for manual inspection.
3、 Oil water separation steps
The first step is to remove floating oil, and gravity separation utilizes the density difference between oil-water phases and the immiscibility between oil and water for separation. The larger the particle size of oil droplets separated from water, the easier it is to separate them from water; The smaller the oil droplet size, the more difficult the separation, and the more challenging the separation.
The second step is to perform solid-liquid separation, removing solid particles larger than 5 μ m from the liquid.
The third step is to carry out emulsion breaking and coalescence, using a 3-5 μ m fine fiber filter layer that is hydrophobic and oleophilic to cut open the emulsified water in oil. After demulsification, the small oil droplets quickly approach the fibers or the oil droplets already attached to the fibers. Due to the diffusion effect of filtration from inside to outside, from dense to thin, the small oil droplets collide with the coalescing material and gradually increase in adsorption on the surface of the coalescing material. When the adsorption force is less than the water flow traction force, these agglomerated large oil droplets detach from the agglomerated material. The liquid pressure releases droplets from the surface of the fibers and increases their adhesion to the fibers with larger gaps in the next layer. This deep diffusion has repeatedly formed larger oil droplets. Preliminary coalescence has been achieved, which means the oil droplets are not yet very large. The mixed layer of water. When the oil layer is thick, the oil level controller sends a signal to open the oil discharge valve to drain the oil. Water containing trace amounts of oil flows downstream.
The fourth step is further agglomeration (coarsening), where we use multiple lipophilic slender tubes and a water oil mixture containing small oil droplets flows upward from the lower end of the tubes. When the liquid flows inside the tube, small oil droplets collide to form large oil droplets and adhere to the lipophilic tube wall. The oil droplets flow slowly but also form large oil droplets. When they quickly rise to the upper small hole and flow out, due to the difference in specific gravity, water flows down and oil accumulates upward. You can clearly see the oil layer, water layer, and oil-water mixture layer here.
The fifth step is a more refined demulsification and coalescence process. The fiber layer that is lipophilic and hydrophobic should be thick, with a composition that is internally dense and externally hydrophobic, to achieve the goal of precise demulsification and coalescence. The flow rate here is even lower, and the total effective oil content can range from 5000ppm to 1-2ppm. The filtration ratio can reach β ≥ 2000.
4、 Factors affecting oil-water separation
Flow rate: Flow rate is an important parameter for oil-water separation, and the faster the flow rate, the worse the treatment effect. The common feature of oil-water separation is working at low flow rates. A solid-liquid separation filter made of 3-5 μ m fine fibers that are lipophilic and hydrophobic. The optimal flow rate (the speed passing through the surface of the filter material) is only between 0.03-0.05 M/min. In this case, not only did it play a role in solid-liquid separation, but it also produced emulsion breaking and agglomeration effects. And the separated oil is also very clean. The suspended solids in the water clog the filter element, causing the flow channel to become smaller and the solid-liquid separation filter element to become blocked. This reduces the probability of collision between oil droplets and coalescing materials, affecting the effectiveness of liquid-liquid separation. Therefore, a pre filter for solid-liquid separation is added earlier to separate solid particles. This solid-liquid separation pre filter can have a flow rate of 0.2-0.3M/min.
Temperature: The same filter has different separation effects on different liquids. The filtration effect is very good in Henan (high temperature), but not in Northeast China (low temperature). Diesel and water can be separated effectively at 2 ℃ And edible oil and water must be above 16 ℃ to separate. When the temperature of oily wastewater rises to 70 ℃~75 ℃, it changes the viscosity of the oil, which means that the density difference between oil and water decreases, disrupting the stability of the emulsion and achieving the effect of demulsification.
PH value: When the pH is ≥ 9, oil-water separation becomes difficult. The pH value is acidic and easy to separate. Some companies use medication to acidify the liquid to pH ≤ 2, and then add medication to restore it to neutral after oil-water separation.
Material: Fine oleophilic fibers should be used during the demulsification and coalescence process. Fibers that are too thin lack support, while fibers that are too coarse do not have a demulsification effect on small droplets. Oil loving fiber materials can stick and aggregate oil droplets that have just been cut into milk bubbles. In the separation step, superhydrophilic fiber materials are used, and superhydrophilic fibers form a strong water film. When fine oil particles come with the water flow, the strong water film prevents the oil droplets from passing through, thus achieving the separation effect. The side effect is an increase in system resistance.
5、 Installation requirements
The installation of this device should generally be arranged according to the system diagram, but during the installation process, special attention must be paid to the following points:
1. Before the plunger pump, it is necessary to install a randomly supplied pump front filter.
2. Clear water pipelines should be installed for flushing and maintenance.
3. The oil and sewage suction inlet on the pipeline of this device should be at a certain distance from the bottom of the pool, generally not less than 200 millimeters.
4. On the suction pipe in front of the pump, the user should install a vacuum gauge by themselves to observe the working condition of the pump (provided by the user).
5. The inlet pipeline system should strictly prevent air leakage and minimize pipeline resistance caused by bends and other factors.
6. The shorter the oil discharge pipeline, the better, and the dirty oil tank should be as close to and lower than the device as possible.
7. The electrical control box of this device cannot guarantee that the pump will automatically stop when it is empty, preventing the water pump from being empty.
6、 Maintenance
1. The filter in the pump inlet pipeline of the device should be cleaned at least once a week. If the filter screen is found to be damaged, a 60 mesh copper wire mesh should be used to repair or replace it in a timely manner.
2. The plunger pump should be maintained once a year, and parts such as the gearbox, piston, and sleeve should be disassembled, cleaned, and inspected. Special attention should be paid to checking the roundness of the nylon ball, the flexibility of the ball in the valve seat, and the sealing of the ball valve to ensure the volumetric efficiency of the pump.
3. To prevent clogging of coarse-grained components, the relief valve should be frequently opened for drainage. If the pressure difference between the two cylinders reaches 0.1 MPa or more, the device should be disassembled in a timely manner to clean the coarse-grained components or replace them.
4. When opening the cylinder for maintenance purposes, the first and second stage oil discharge solenoid valve knobs should be manually turned to the open position to drain any remaining oil from the upper part of the cylinder. Then, the lower relief valve should be opened to drain any remaining water and sludge from the cylinder and rinse it clean. After maintenance, attention should be paid to the sealing between the coarse-grained components and the water collection chamber during assembly. After maintenance, clean water should be filled immediately for wet maintenance.
7、 Product specifications and main parameters

8、 Attached image