Fault treatment of spray drying tower system
The spray drying tower system is used for redispersible latex powder. The system is imported from Denmark and produced by maniru company with the model of production minor / 12.5. The drying tower is composed of high-speed atomizer, blower, flash dryer, cyclone separator, heating box, feeding system, filler pusher, induced draft system, explosion-proof door and control cabinet.The spray drying tower system is used for redispersible latex powder. The system is imported from Denmark and produced by maniru company with the model of production minor / 12.5. The drying tower is composed of high-speed atomizer, blower, flash dryer, cyclone separator, heating box, feeding system, filler pusher, induced draft system, explosion-proof door and control cabinet.
1. Sudden smoke and alarm during equipment operation
The cause of smoke and alarm is the combustion of air inlet filter. Immediately cut off the power and put out the fire. It was found that a large amount of ash was produced by the combustion of the air inlet filter; the display of the air inlet temperature of the control cabinet was normal; a group of electric heaters were damaged; and a large number of massive materials were found in the receiving bucket.
The system has been in dust environment for a long time, and a large amount of dust adheres to the filter element (paper) of the air inlet filter, resulting in the air inlet speed far lower than the process design requirements (2m3 / s)
The temperature in the heating box rises. When the temperature reaches the self ignition temperature of the filter element, the filter element will self ignite.
The signal feedback circuit is installed at the bottom of the heating box. After overheating, the wire of the temperature tester is damaged, the temperature feedback signal cannot be transmitted back, the heating regulator is open circuit, and automatic regulation can not be realized; the heater can not be cut off in time, and a group of high-power heaters are burnt out; when the operator is powered off, some atomized materials in the drying tower can not be dried, condense and form blocks.
The air inlet pipe of the heater is led out of the production workshop to avoid dust adhesion and blockage of the heater box filter, so as to ensure the air inlet speed of the heating box.
The installation mode of the temperature tester in the heating box is reformed. Only the probe is placed in the heating box, and the signal feedback circuit is attached to the outside of the heating box through heat insulation and flame retardant protection.
Connect the heater temperature controller control circuit in series with the main control circuit of the equipment. When the heater temperature is higher than the set temperature, the system can cut off power in time to avoid accidents.
2. High speed atomizer vibrates violently and produces noise
The high-speed atomizer is composed of high-speed motor, material distributor, flash dryer and atomizing wheel. The motor model is vfs31.09-24, the speed is 10000-30000r / min, and the running current is 0.47a. It is made in Germany. During the operation, the high-speed atomizer vibrates violently and makes a "squeak" sound. The running current of the motor reaches 0.55a. After disassembly, it was found that the atomizing wheel and the material distributor were in good condition, the rear bearing seat of the motor was cracked with a length of about 8 mm, and the inner ring raceway of the rear bearing had 0.5 mm deep wear traces and blue burning phenomenon, and the cage was broken. At the same time, it is found that there are slight friction marks between the rotor and the stator. According to the preliminary judgment, it is caused by poor lubrication during high-speed operation of the motor.
The coaxiality of the motor rotor was detected and the dynamic balance test was carried out, which met the technical requirements. Argon arc welding was used to repair the rear bearing seat of the motor, and the correction processing was carried out. Replace the front and rear bearings of the motor (model hss7002, hss7004, FAG). During the test run, when the speed is 20 000 R / min, violent vibration and "squeak" sound appear again, and the running current of the motor reaches 0.5 a.
The site inspection was carried out with the SITEC 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). The results are shown in Table 1.
When the motor is running under no-load or loading, the vibration value of each point has no obvious change, which indicates that the vibration has nothing to do with the atomizing wheel and the material distributor.
The radial horizontal vibration and axial vibration of each measuring point of the motor are large, and the vibration of the rear bearing seat is significantly greater than that of the front bearing seat. It shows that there is obvious couple unbalance characteristic, which is related to bearing.
Because the end face of the motor rear bearing block is machined after repair welding, it is difficult to meet the requirements of the original bearing position accuracy after machining, which will lead to increased clearance and severe vibration during operation.
The centrifugal force produced by high-speed rotation of atomizing wheel is the unbalanced force of motor rotor. Due to the radial clearance of the bearing, the force of the ball in the non load area is unbalanced, and abnormal sound and vibration will appear.
A corrugated spring (0.5mm in thickness, 32mm in outer diameter and 28mm in inner diameter) is installed at the rear bearing seat of the motor. After installation, the spring has a preload compression of 1.5mm to compensate the axial displacement of the bearing. When the motor rotor changes in heat, the inner ring of the bearing moves accordingly to eliminate the excessive clearance of the bearing.
After treatment, the vibration values of each measuring point are in a good range.
