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Company:Chengdu Cobalt Mining Co., Ltd


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Common Faults of Horizontal Vibrating Centrifuge and Treatment Methods

The damage of the screen basket is mainly manifested in two aspects: one is the local damage of the screen basket, when the large materials continuously impact the screen basket and cause local holes. It is usually treated by welding.In order to roughly ensure the dynamic balance, the screen basket is usually welded by symmetrical welding method which divides the screen basket 4 equally. The other is that the screen basket is seriously worn as a whole, and the vertical bar, transverse bar and screen bar of the screen basket are broken in rows. When the actual gap on the screen surface is more than 90%, the screen basket must be scrapped and replaced with a new one.
First, apply for power failure, power test and locking of centrifuge, prepare 46 mm hammer wrench, 46 mm socket, 30 mm socket, electric wrench, sledge hammer, crowbar, it chain, Jack, special sieve basket pulling tool, special installation of concentric shaft of sieve basket, steel wire buckle; then verify the spare parts, and transfer the sieve basket to the corresponding position.
Specific operation steps:
a.Open the cover plate of the front section of the centrifuge;
b.Remove the bolts on the feed pipe and lift the feed pipe;
c. Remove the bolts on the end cover of the screen basket and take out the end cover;
d.Install the special tool on the screen seat of the screen basket, and use a 100 t Jack to pull out the screen basket;
e.Screw the concentric shaft into the main shaft of the centrifuge, use the chain to transfer the new screen basket to a suitable position, place the screen basket on the concentric shaft, and push the screen basket into the main shaft of the centrifuge with the joint efforts of two people;
f. Install the screen basket end cover;
g.Install the feed pipe;
h.Install the front cover and feed hopper;
i. Apply for power transmission and test run;
j. Check tools and clean the work site.

Oil leakage.
Most of the oil leakage in the oil inlet pipe, oil return pipe and pipe joint is caused by the loose fastener of pipe joint and aging of rubber 0-ring at the joint. It can be solved by replacing the 0-ring of corresponding size.
There is oil leakage at both sides of the upper cover of the vibration box at the bearing seat and the sealing part of the bearing cover. It is necessary to dismantle the accessories and clean up the glue and oil stains, and then evenly apply the glue to fasten them.
There is oil leakage at the sealing part of the upper cover of the oil tank. Check the tightness of the bolts and the rubber gasket. Replace the rubber pad or fasten the bolt. There is a crack at the weld of the tank body, which causes oil leakage. It is necessary to replace the tank with a new one.
The oil leakage of the framework oil seal at the end of the belt pulley and screen basket is caused by the wear of the oil seal caused by the rotation of the main shaft for a long time. Replace the framework oil seal.

The pressure gauge shows that the oil pressure is too low.

Check whether the pressure gauge is damaged. If the pressure gauge does not return to zero when the machine is stopped, the pressure gauge is damaged and needs to be replaced. Check the oil level. If the oil level is too low, the oil pressure will be insufficient. Add 100 "lubricating oil to the oil window in time. Check the oil suction pipe for air leakage. If the oil suction pipe leaks, the oil suction pressure of the oil pump will be insufficient.

Adjust the spring pressure reducing valve (relief valve), observe the pressure at any time, and adjust until it is appropriate. Turn the bolt clockwise to increase the pressure, and turn it counterclockwise to decrease the pressure.
Clean or replace the filter element. If the filter element is blocked, the oil pump will be difficult to absorb oil, resulting in low oil pressure of the equipment and high noise of the oil pump. Check whether the oil pump is seriously worn, whether the cross slider connected with the motor is damaged, and whether the gear clearance is too large. Replace the motor or the whole set of gears.

Deterioration of lubricating oil.
If the lubricating oil is used for a long time, black deterioration will occur. At this time, the oil tank shall be completely cleaned and the lubricating oil shall be replaced. The first oil change shall be carried out after 250 hours of operation. After the first oil change, the oil shall be changed every 1500 hours or at least 6 months. Every time the oil is changed, the filter medium is also changed. All operating parts of the centrifuge are forced lubricated with thin oil.
Check the front frame oil seal for damage. If the wear is serious, the slurry water may enter the oil tank through the wear part, causing the emulsification of the lubricating oil. In case of oil seal problem, replace the corresponding oil seal.
If the seal of the oil tank is damaged, the flushing water will enter the oil tank when cleaning the equipment, which will also cause the emulsification of the lubricating oil. Seal the upper end cover of the oil tank again.

The centrifuge shakes left and right.
The reasons may be as follows: First, the screen basket is not cleaned before startup, and the screen basket loses dynamic balance.
Treatment: stop the machine and clean up the materials on the screen basket.
Second, the product feeding is not stable, the screen basket loses dynamic balance, and the coal quantity in the system is adjusted in time to make the centrifuge feeding normal.
Third, rubber vibration isolators and ring buffers are aged and lose elasticity. Disassemble the centrifuge and replace the corresponding ring buffer.

The dehydration effect is poor.

The water content of centrifuge feed in coal preparation plant is regulated (for example, no more than 25%), However, some kinds of coal have high viscosity, small hardness and high brittleness. When this kind of material enters the screen basket, secondary slime will be produced due to the influence of comprehensive factors such as force and vibration, which further refines the material composition, reduces the dehydration effect, and makes the cake layer formed by the material easy to adhere to the screen surface and not easy to fall off. In this case, only by increasing the exciting force and amplitude can the discharge be promoted. In addition, too much water in the feed, too small amplitude, too large screen seam and too short screen basket will cause too much water in the product.

Abnormal amplitude.
The amplitude is the reference value of centrifuge vibration. If the amplitude is too small, the discharge of centrifuge will not be clean, and there will be material accumulation on the screen basket, which can not reach the designed processing capacity.

coal centrifuge

Excessive amplitude will accelerate the wear of bearing and buffer sleeve, resulting in mechanical and electrical accidents.
The amplitude reading of the centrifuge is observed by the amplitude sign plate method. When a sharp triangle appears under the sign, the value corresponding to the tip of the triangle is the amplitude value of the centrifuge.
Figure 3 shows the amplitude identification plate of the centrifuge, figure 4 shows the amplitude plate in operation, with a reading of 3 mm.
When the amplitude is abnormal, the amplitude needs to be adjusted. In order to avoid damage to the equipment due to abnormal vibration, for example, adjust the amplitude of the centrifuge to 3 mm.
Specific steps: firstly, check the gap between two pairs of excite vibration blocks of buffer plate, which is 0.6-0.9mm under normal conditions. If this requirement is not met, it should be adjusted by changing the gasket between the vibration rubber block and the fixed plate; the actual gap distance between the excite vibration block groups can be accurately measured by using a feeler gauge, and the thickness of the gasket can be measured by using a vernier caliper.
Loosen the fixing bolt on the buffer block, and adjust the gap of the excitation block group to 0.6mm effectively by adding and subtracting the adjusting pad. It is usually necessary to adjust the gap between the excite vibration blocks on both sides of the impact plate.
Check whether the eccentric block in the excitation box is in the best position. If the position or angle of the eccentric block is unreasonable, the amplitude will be too small. Should carefully observe, make reasonable adjustment (generally not used).
The buffer ring at the connecting part of the main shaft and the shell will lose its elasticity due to the aging of the rubber. If this happens, the buffer ring shall be replaced in time. The hardening or failure of polyurethane buffer block at the base of centrifuge can also cause the amplitude to decrease. The use of buffer block shall be checked in time.
Increase or decrease the motor speed, or adjust the working radius through the split belt wheel, and then change the running speed.

The centrifuge makes a strange noise. The reasons and solutions are as follows:
a.The connecting bolts of the connecting parts of the centrifuge are loose and need to be tightened;
b.If the screen basket is damaged and causes dynamic imbalance, replace the screen basket;
c.If the screen basket is blocked and the materials in the screen basket are piled up, the screen basket shall be cleaned; if the vibration isolation rubber spring fails, the vibration isolation rubber spring shall be replaced;
d.The feeding is uneven, the water content is high and the viscosity is large, so the feeding should be adjusted;
e.If the bearing is damaged (exciter box bearing and main shaft bearing), replace the bearing;
f.If the gear fails (rubber wood gear and steel gear of the excitation box), the gear shall be replaced;
g.The buffer ring (sleeve) is aged, deformed and inelastic, so the buffer ring (sleeve) shall be replaced;
h.The butterfly cushion is aged and deformed, and the gap is too large or too small. Replace the cushion and adjust the gap to 0.6-0.9 mm;
i.The adjustment of the triangle belt tightness is not appropriate. It is better to adjust the triangle belt tightness to a deviation of 10-15 mm when 4-5 kg force is applied to the middle section;
j.If the position and angle of the eccentric block in the excitation box are not appropriate or the fastening bolt is loose, adjust the position and angle of the eccentric block and the fastening bolt. 

Belt wheel swing.
Generally, the reason is that the belt pulley swings due to the looseness of butterfly spring. The installation method of 8 disc springs at the pulley end is v AV a (the direction of disc spring is indicated by less than or greater than sign). When tightening butterfly spring, it can be conducted according to the tightness degree of butterfly spring of other centrifuges (i.e. several threads are leaked out of bolts).

There are more solid particles or large-size materials in the filtrate.
The main reasons are: the screen gap of the screen basket becomes larger due to wear, and the screen bar of the screen basket will wear and break, which will cause large particles and large materials to enter the filtrate pipe, resulting in the blockage of the filtrate pipe.
Predictive Maintenance System:
In order to ensure the long-term performance of the centrifuge, Alpha specially customize the built-in wireless sensor for centrifuge, which can real-time monitor the operation status of the core components of the centrifuge.
coal centrifuge excite vibration block

The operation data of centrifuge is uploaded to ALPHA cloud wirelessly. Intelligent analysis and intelligent algorithm are embedded to predict the operation failure of centrifuge and realize predictive maintenance of centrifuge. Predict faults in advance to avoid failure downtime. The running data of the computer and the mobile WeChat can be viewed in real time, and the warning and alarm information can be pushed in real time. Extend the service life of the equipment.

coal centrifuge&Real time monitor

Solid Particle Monitoring System
Real-time monitoring of solid particle content in centrifugal fluid, through analysis, real-time understanding of the screen basket wear situation. Convenient and timely replacement of vulnerable parts, reduce abnormal shutdown in production. The early warning information is pushed in real time, and the production personnel can understand the information and process it in the first time.

intelligent centrifuge

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