The importance of regular decanter centrifuge inspection

1. Regular inspection

(1) Regularly check the gaps between the pusher plate, scraper and drum filter. The gap between the scraper and the screen should be within 5~7mm, and the axial clearance of the scraper blade from the bottom of the drum and the liquid blocking plate is about 4mm.

(2) Detect the vibration of the fuselage of decanter centrifuge every 7 to 15 days.

(3) Check whether the safety interlocking device is sensitive and easy to use every 3 months.

(4) Check and clean the oil filter every 3 months to ensure that there is no grease, water scale, and sand.

(5) Analyze the quality of lubricating oil every 3-6 months to ensure that the quality of lubricating oil meets the standard.

(6) Check and verify whether the instrument device meets the performance parameter requirements every 12 months to ensure that the instrument device is accurate, sensitive and easy to use.

2. Decanter centrifuge adjustment The timely inspection and adjustment of the decanter centrifuge before operation or during the stoppage time of the operation is an important guarantee for keeping the machine in good running condition and an important part of machine maintenance.

(1) Adjustment of the working pressure of the oil pump Adjust the relief valve to keep the output pressure of the oil pump at 1.6MPa (gauge pressure).

(2) When the working position of the scraper is adjusted when the piston rod in the scraper cylinder goes down and hits the bottom cover of the cylinder (that is, when the piston is at the bottom dead center position), the roller on the crank of the scraper device should touch the travel switch. The distance between the blade and the screen (surface screen) in the drum should be kept at 5~7mm. This distance is achieved by adjusting the travel switch on the door cover and the nut on the piston rod in the scraper cylinder. Adjust the fastening screw of the scraper blade to connect the knife holder so that the axial gap between the two ends of the blade and the bottom of the drum and the liquid blocking plate is approximately the same, about 4mm.

(3) Rotary drum loading amount The thickness of the material layer is determined by different materials, but it should not exceed 120mm.

(4) Adjustment of process duration During automatic operation, the time relay knob in the electrical console can be adjusted according to different materials and corresponding process requirements to realize the duration of each process and the total time to complete a work cycle.

The most important part of the Decanter centrifuge is the transmission part, and the bearing is an important part of the transmission part. Generally, experienced centrifuge purchasers will ask the manufacturer a series of questions about the bearing when purchasing the centrifuge.

Here we discuss the issue of bearing over-heat in centrifuges. There are several reasons for bearing heating, which should be analyzed in detail:

1. It may be due to overload or overload;

2. It may be due to heat generated by mechanical friction;

But the main problem is whether the bearing is authentic or not. Some users buy low-priced bearings for low prices, which will cause the bearings to become hot and hot, causing the bearings to burn out.

Therefore, first emphasize the need to purchase authentic bearings.

The Decanter centrifuge is a high-speed chemical and pharmaceutical equipment. High-speed bearings require good bearings. High-quality and authentic bearings can ensure the long-term normal operation of the centrifuge, and the service life can reach more than 10 years.

Second, we must pay attention to adhere to the mechanical lubrication and choose high-quality high-temperature lithium-based grease. The quality of the lithium-based grease is another main reason for bearing heat.

In addition, you must check with your detailed situation. Assuming that mechanical friction will be accompanied by noise, mechanical parts will have obvious wear, and the bearing will be loose, then it should be a bearing problem, and the bearing needs to be replaced.

Third, whether the concentricity of the centrifuge spindle and the bearing seat is accurate during the machining process. Under normal circumstances, people do not pay much attention to the concentricity. The high concentricity of the spindle tends to cause bearing heating.

Fourth, in the machining process of the spindle and the bearing seat, the tolerance is not in place, and the clearance between the bearing inner ring (outer ring) and the ball (column) is too small.

Maintenance of Spindle of Decanter Centrifuge

  1. Check the wear of the main shaft journal of decanter centrifuge. If the wear depth is not too large, the wear part can be repaired by surfacing or electroplating, and then processed to the original size; if the wear depth is too large, a new shaft should be replaced.

  2. Perform flaw detection on the spindle. If there are defects such as cracks, corrosion, etc., they are not allowed to be repaired, but only replaced.

  3. Detect the straightness deviation of the spindle. If the deviation of straightness or coaxiality exceeds the allowable value, the spindle should be corrected; if the deviation is too large, it should be replaced.

  4. Check the surface quality of each machining mating surface at the journal. The surface roughness value R<6.3m, and there must be no scratches, grooves and other defects.

　　 There are two types of shafts for decanter centrifuges. One kind of shaft is slender and has greater flexibility, so it can automatically adjust the center. The other kind of shaft is thicker and shorter, and the bending deflection of the shaft itself is small, but the layered shock absorber still makes the working speed of the system above the critical speed, so the system is still a flexible system. Although it is also a flexible system, the difference between the operation of a slender flexible shaft and a more rigid shaft is that the automatic centering of the slender flexible shaft mainly realizes the rotation of the rotor around its center of mass through the bending of the shaft. The more rigid shaft is automatically centered through the flexible relative displacement of each component in the entire rotating system.

　　 The vibration of the decanter centrifuge is one of the important indicators to measure the performance. Vibration damping can adopt active damping and passive damping. Active vibration reduction means that the working speed of the decanter centrifuge is designed to far avoid the critical speed of the rotating system. Passive vibration damping is to separate the possible vibration from the frame and foundation with various types of vibration dampers.

　　 1. Design the spindle bearing seat into a flexible vibration reduction type;

　　 2. Flexible connection between the spindle and the motor;

　　 3. The entire drive system is flexibly connected to the frame.

　　Rubber shock absorbers generally can meet the vibration reduction requirements of decanter centrifuges. When the structure of the shock absorber is determined, the greater the hardness of the rubber, the higher the critical speed of the system. Shock absorbers with too low hardness cannot meet the requirements and are easily damaged.

Methods to eliminate hidden dangers in decanter centrifuge operation

As we all know, chemical and pharmaceutical equipment-centrifuges are high-speed machines, safety hazards are particularly important, and serious threats to human lives, so we must pay more attention to the principles of use when operating decanter centrifuges.

1. When the decanter centrifuge is in the pre-cooling state, the centrifuge cover must be closed. After the centrifugation, the rotor should be placed upside down on the experimental table, and the remaining water in the cavity should be wiped off. The centrifuge cover is open.　

2. When the rotor is pre-cooled, the rotor cover can be placed on the platform of the decanter centrifuge or placed on the experimental bench. It must be tightened and floated on the rotor, because once it is started by mistake, the rotor cover will be Will fly out and cause an accident!　　

3. After the rotor cover is tightened, there must be no gap between the rotor and the rotor cover with your fingers. If there is a gap, unscrew and re-tighten the centrifuge until it is confirmed that there is no gap.　　

4. During the centrifugation process, the operator shall not leave the decanter centrifuge room. Once an abnormal situation occurs, the operator shall not turn off the power (POWER) and press STOP. Before pre-cooling, fill in the centrifuge usage records.　　

5. Do not use fake or inferior decanter centrifuge tubes, and do not use aging, deformed, or cracked centrifuge tubes.　　

6. You can leave after the last routine safety inspection using the centrifuge during holidays and evenings.　　

7. If the machine fails during the use of the instrument, and the parts are damaged, contact the manufacturer in time for replacement.

The above author has summarized the seven issues that need to be paid attention to when using centrifuges. In fact, they are far from enough. In short, operators must always put safety first in order to prevent unnecessary occurrences.