Fault Analysis of Horizontal Decanter Centrifuge for Petrochemical Industry

1. Working Principle of Horizontal Decanter Centrifuge

Horizontal decanter centrifuge is a continuous, automatic mechanical equipment, which can separate the solid in the suspension from the liquid. Its working principle is as follows:

(1) The screw and the drum rotate at a certain differential speed in the same direction. The suspension is continuously fed into the drum from the inlet pipe.

(2) Under the action of high-speed rotating centrifugal force, the solid phase with large density will settle on the drum wall and form a solid ring layer. Then the sediment will be continuously pushed to the cone end of the drum by the conveying screw, and be discharged form the slag outlet.

(3) The liquid phase with smaller density will form a liquid ring layer, and be discharged out of the drum under the action of gravity, and then be discharged from the liquid outlet.

2. Fault Analysis and Solution of Horizontal Decanter Centrifuge

2.1 Internal Blockage

The phenomenon of blockage is that the centrifuge does not discharge slag for a long time. In the case of no change in the feed, the discharged liquid will be gradually turbid and darkened, the rotating speed of the drum will be greatly reduced and the current of the drum will be increased, the slag discharge torque will gradually rise and remain high. The appearance of these features indicates that the centrifuge may be blocked.

Solution:

In case of the fault of the above features, the operator should not press the emergency button, because the centrifuge has no brake device and is in high-speed operation. At this time, pressing the emergency button can not solve any problems.

First of all, cut off the suspension feed immediately, because in most cases, the centrifuge can automatically discharge the blocked solid by the double action of the screw and the drum.

If it is not valid, the operator should not turn off the screw motor, but immediately turn off the drum motor or reduce the rotating speed of the drum. After the rotating speed of the drum is reduced, the solid blockage may gradually relax and be discharged out of the centrifuge.

If the above measures do not work, the drum motor should be turned off. The water should still be injected into the centrifuge, as long as the screw can rotate, the centrifuge is possible to return to normal.

2.2 Vibration

The vibration of the centrifuge can be divided into sudden vibration and chronic vibration.

Sudden vibration generally means that the internal materials are blocked, or the internals parts are damaged or fall off. It is necessary to check whether there is fault in the slag discharge system and check whether there is blockage in the discharge pipeline.

Chronic vibration generally means that the centrifuge is suffering from serious wear and tear, the bearing system is damaged and the rotation is unbalanced, the external parts are damaged or fall off, which needs to be repaired and replaced.

2.3 Bearing Temperature Is Too High

When the bearing temperature is too high.

Check whether the amount of grease added to the bearing is too large and check the color of waste grease. The color of normal bearing waste grease should be light gray. If it is found that the color of waste grease is rust yellow, or black, or other abnormal colors, the bearing may be damaged, and should be replaced.

Check whether there is excessive vibration and whether there is abnormal noise when the bearing is running. If there is vibration and abnormal noise, the bearing may be damaged, and should be replaced.

2.4 Manual Turning of Drum

The manual turning of drum is an effective method to judge whether there is solid accumulation inside the drum and whether the drum can be started smoothly.

When turn the drum manually, if the drum rotates smoothly, decelerates itself through resistance and stops at a random angle, it means that the drum is normal.

If the drum rotates very heavily, and it will turn back by itself after releasing the hand, and after repeated rotation, the drum almost stops at the same position, it means that there is solid accumulation inside the drum.

Solution: inject water into the centrifuge and start the screw motor. After removing the materials inside the drum, then start the drum motor, so as to avoid violent vibration of the drum.