Troubleshooting of spray drying tower system
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Abstract:Spray drying tower system for testing of redispersible powder. The system was introduced from Denmark and produced by Manilu Company, model Production minor / 12.5, the drying tower is composed of high-speed atomizer, blower, flash dryer, cyclone, hea…
Spray drying tower system for testing of redispersible powder. The system was introduced from Denmark and produced by Manilu Company, model Production minor / 12.5, the drying tower is composed of high-speed atomizer, blower, flash dryer, cyclone, heating box, feeding system, filler pusher, and induced air , Explosion-proof door and control cabinet.
1. Sudden smoke and alarm during equipment operation
The reason for smoke and alarm is that the air inlet filter of the system is burning. The site immediately cut off power and extinguished the fire. It was found that a large amount of ash was generated by the combustion of the air inlet filter; the air temperature display on the control cabinet showed normal; a group of electric heaters were damaged; there were a large number of block materials in the receiving bucket.
The system has been in a dust environment for a long time, and a large amount of dust adhered to the air inlet filter element (paper), which caused the air inlet speed to be far lower than the process design requirement (2m3 / s).
The temperature in the heating box rises. When the temperature reaches the self-ignition temperature of the filter element, the self-ignition of the filter element is caused.
The signal feedback line is installed at the bottom of the heating box. After overheating, the temperature tester wire is damaged, the temperature feedback signal cannot be transmitted, the heating regulator is disconnected, and automatic adjustment cannot be achieved; the heater cannot be powered off in time, and a group of high-power heaters burned out; When the operator is powered off, some of the atomized materials in the drying tower cannot be dried, coagulate, and form a block.
Lead the heater air inlet pipe out of the production workshop to prevent the filter of the heating box from being blocked by dust adhesion to ensure the inlet speed of the heating box.
Modify the installation method of the heating box temperature tester, only put the probe in the heating box, and the signal feedback line is insulated and flame-retardant protected, and is attached to the outside of the heating box.
Connect the heater thermostat control loop in series with the main control loop of the equipment. When the heater temperature is higher than the set temperature, the system can be powered off in time to avoid accidents.
2. The high-speed atomizer vibrates violently and makes noise
High-speed atomizer, composed of high-speed motor, material distributor, flash dryer, atomizing wheel, motor model VFS31.09-24, speed 10000 ~ 30,000r / min, running current 0.47A, made in Germany. During operation, the high-speed atomizer vibrates violently and emits a "squeak" sound, and the motor running current reaches 0.55A. After disassembly, it was found that the atomizing wheel and the material distributor were intact, the rear bearing seat of the motor was cracked, about 8mm long, and the inner ring raceway of the rear bearing had 0.5mm deep wear marks, and there was blue burning, and the cage was broken. At the same time, it was found that there was a slight trace of friction between the rotor and the stator. Preliminary judgment is caused by poor lubrication during high-speed operation of the motor.
Detect the coaxiality of the motor rotor and perform a dynamic balance test, which meets the technical requirements. The rear bearing seat of the motor is repaired by argon arc welding and corrected. Replace the front and rear bearings of the motor (models HSS7002, HSS7004, FAG). During the test run, when the rotation speed was 20000r / min, severe vibration occurred again and a "squeak" sound was issued, and the motor running current reached 0.5A.
On-site inspection with STARK CMS2977 maintenance system. The measuring points are set at the front and rear bearings of the motor. Each point is taken in three directions: radial horizontal (H), radial vertical (V) and axial (A).
When the motor is running with no load or load, the vibration value at each point does not change significantly, indicating that the vibration has nothing to do with the atomizing wheel and has nothing to do with the material distributor.
The radial horizontal vibration and axial vibration of each measuring point of the motor are relatively large, and the vibration at the rear bearing seat is significantly larger than that of the front bearing seat. It shows that there is obvious unbalance characteristic of force couple, which has a lot to do with the bearing.
Because the machining of the rear bearing housing end face of the motor is performed after welding, it is difficult to achieve the original bearing position accuracy requirements after processing. This will increase the clearance for the split bearing and cause severe vibration during operation.
The centrifugal force generated when the atomizing wheel rotates at high speed is the unbalanced force of the motor rotor. Due to the radial clearance of the bearing, the ball is unbalanced in the non-load area, and abnormal sound and vibration will occur.
A corrugated spring (thickness 0.5mm, outer diameter 32mm, inner diameter 28mm) is installed at the rear bearing seat of the motor. After installation, the spring has a preload compression of 1.5mm, so that the axial displacement of the bearing is compensated. When the motor rotor is heated and changed, the bearing inner ring moves accordingly, eliminating excessive bearing clearance.
After processing, the vibration value of each measuring point is in a good range until the motor runs.