Operating principle of the centrifugal oil separator system

The basic operating principle of a centrifugal oil separator system

Dirty oil is continuously fed into the centrifugal separator as in conventional ones. Clean oil is continuously discharged from the machine through the clean oil exit path, the residue is collected in the residue tank in the drum.
On the clean oil exit path, there is a device installed to check the water content in the clean oil (water transducer). When the amount of water and sediment begins to touch the circumference of the disc bundle, some water droplets begin to escape through the clean oil path. The increase in water content in the oil is immediately sensed and sent to the controller. This signal is translated into the amount of water in the oil. This value is remembered each time the residue is discharged as a comparison value. The amount of water in the oil is measured according to the difference between the amount of water present and the comparison amount of water memorized from the previous residue discharge. This deviation will be the signal to trigger automatic residue discharging and alarm.

Basic operating principle of ALCAP centrifugal oil separator system

The normal state of the separator (low water content in oil)

Normally, if the water content in the oil is low, the time between two sediment discharges is a time predetermined by the user. When this time expires, the deviation in the amount of water in the oil is recorded in the controller, and the water to soften the sediment and remove the oil is automatically supplied to the drum before proceeding to discharge the sediment.

Initially, water is continuously supplied to the drum. The water is then supplied in the form of short, gradually decreasing pulses. Therefore, it eliminates the possibility of mixing water into the clean oil.

After a number of water supply pulses, the discharging process is initiated. The sludge discharge time is calculated so that only water and sediment are discharged out, while oil does not escape through the sediment door. Then a new separating cycle begins again.

State of high water content in oil (>0.5%)

If the amount of water in the oil is high (>0.5%), this amount of water will fill the sludge chamber before the preset time between two sludge discharges ends. The water released through the clean oil path is immediately detected by the water content sensor in the oil, and the sludge discharge process is initiated without the need for additional water supply. After discharging the residue, the cycle is repeated, starting by recording the value of the amount of water in the oil to compare for the next discharge.
If 5 consecutive sludge discharges before the predetermined time occur, an alarm signal is generated from the controller, indicating that the water content mixed in the oil is very high. This alarm signal indicates that water is leaking into the oil from somewhere in the system.

The content of water in the oil is too high

If the water content in the oil is too high, the separator is automatically switched to emergency mode. There is a light showing this mode on the controller. The separator is activated to discharge sediment according to the signal from the water content sensor. When the water content decreases or the time between two sludge discharges becomes longer than the preset time, water is automatically replenished into the separator drum as usual. This action is the signal to return the system to normal operating state. When the water content in the oil is low, water to repel the oil is additionally supplied according to the adaptive principle, so that the neutral surface is always maintained at the optimal position, ensuring the best separation efficiency. If the controller initiates sediment discharge right while water is being supplied due to a signal from the water sensor, it means the additional water to push the oil is too much. The amount of water supplied to the next sludge discharge will be reduced. After 10 sludge discharges, the system automatically checks the amount of water to push the oil by adding a small amount of water to the drum. If the water content sensor responds in the form of an increase in water content value, the amount of water supplied to push the oil out is sufficient. If the sensor does not respond to the increase in the amount of supplied water, the amount of water supplied to the drum is insufficient and the system will increase the amount of water to push the oil for the next sludge discharge.

Operation of water content sensor in oil

The water-in-oil sensor operates on the capacitor principle and measures the dielectric constant of clean oil flowing through the capacitor. The device consists of two concentric conduits, insulated from each other to form a cylindrical capacitor and a box mounted on this tube. The current from the controller is fed to the sensor and is converted into alternating current by the oscillator mounted in the box on the tube to supply to the capacitor. This current varies directly according to the dielectric constant of the liquid flowing between the two cylinders, which are the two plates of the capacitor. This capacitor current is a signal about the water content in the oil, sent to the controller.