Hazard cooling tower fan vibration and Treatment
Release date：2015/5/3
Vibration exceeds the design value of the cooling tower, as well as vibration, amplitude fluctuations and other abnormal phenomena that the cooling tower fan flawed, if not to take measures to continue to run the unit would loose parts of each link, reducing the coupling rigidity, vibration will follow further exacerbate , creating a vicious cycle. Cooling tower fan vibration may cause the following hazards:
1) Gear load increased, affecting gear life;
2), the motor current overload and increased volatility, resulting in motor burn;
3) leaves the coupling damage, thrown off, causing machine crash injury accidents;
4), drive shaft coupling gear, chain wear increasing damage;
5), the tower open welding or soldering section loose off;
6), fiberglass panels, duct connecting portion loose, cracking, deformation hairdryer.
Thus, the cooling tower fan excessive vibration, fluctuations can cause serious harm, should be properly analyze the causes and vibrational properties of vibration, find the cause of excessive vibration cooling tower sites, take the appropriate measures to deal with the vibration value down , to meet the design allowable range.
Cooling Tower Vibration Analysis and Processing Method
Cooling Tower Vibration Cause Analysis
According to the fan operating conditions and processes, the reasons for the cooling tower vibration preliminary analysis, there are the following possibilities:
1), the fan blade angle error. Each blade installation angle error is too large, it will make a difference on the windward side of each blade, suffered a different load on the blades, causing the cooling tower fan vibration.
2), the blade imbalance. This cooling tower fan blades of glass fiber reinforced plastic material, in the abdomen hollow, conducted after the completion of the torque load, because it is formed craftsmanship, quality south there are some errors, moments after weighing unbalance although reduced, but not eliminate, still exist a certain amount of imbalance, will produce vibration cooling tower operation.
3), the drive shaft balancing errors. Shaft parts for the high-speed operation, the speed of 980r / min, manufacturing, drive shaft balancing poorly or if the calibration accuracy is not high, is bound to affect the stability of the fan, resulting in larger cooling tower vibrations.
4), drive shafts, couplings install low concentricity. Because the shaft is connected to a gear chain by aligning bearings, gears and gear chain are connected with the motor, if concentricity bad, causes the motor to the output shaft and the gear unit input shaft are on different axes, eccentricity, vibration is too large cooling tower fan is running.
5), shaft bending. Shaft bent also cause cooling tower fan vibration, since the fan shaft long and thin-walled steel pipe material, when the drive shaft is bent during operation generates unbalanced torque, so that the cooling tower fan vibration.
6), severe corrosion steel weld cracking. Between the pillars and beams of steel cooling tower connected to the welding process, to form a rigid structure, as part of the steel corrosion, weld cracking, shaking the entire steel large cooling towers will produce vibration.
7), fan motor pillars insufficient structural strength. Cooling tower fan motor placed directly on top of a steel pillar, if insufficient pillar strength, it will rattle during operation, excessive vibration caused by the cooling tower.
8), gearbox accuracy error. Gearbox appear broken tooth gear during operation, severe pitting, ratcheting the gap is too large, bearing failure will result in increased vibration when the fan is running.
Treatment of cooling tower fan vibration
After a preliminary analysis, to address the problem analyzed several possible causes. First, eliminate security risks, and follow the principle of easy to difficult, for processing.
For half serious corrosion on steel cooling tower replacement, reinforcement, eliminating the cooling tower shaking, then the test machine, cooling tower fan vibration without significant changes, vibration is still too large. Check the blade angle, replace aligning bearings, wear connected chain; measuring shaft runout (permissible range), recalibrate the drive shaft, after coupling coaxial test machine, vibration decreased cooling tower, cooling tower fan vibration velocity : fluctuate between 12 and 19, the motor vibration velocity values: fluctuate between 8 to 15; exceed the design allowable value. Vibration of the cooling tower will eventually be locked on the gearbox.
Removing the leaves were moments weighed less unbalance; then continue to check the gearbox gears, bearings, found increased backlash, bearing wear serious, shaft gap increases, the spindle side to side, taking the replacement of bearings, adjust backlash .
Treatment effect
Through the above measures for cooling tower fan vibration treatment, which greatly reduces vibration, fan vibration velocity values: fluctuate between 5 ~ 7mm / s, the motor vibration velocity values: fluctuate between 4 ~ 6mm / s, basically meet the design allowable value . This shows through the cooling tower fan vibration treatment methods have been basically solved the problem of the vibration of steel cooling tower.
