Basic situation of induced draft fan unit
The basic situation of the induced draft fan unit is driven by a single-stage steam turbine, and the sliding bearing of the unit is lubricated by forced oil supply. The gear oil pump in the oil station is driven by the motor, and is sent to the lubrication points of the unit through the oil filter and the cooler, and is connected with the oil brake of the quick-closing valve through the three-way electromagnetic valve. The front end support bearing of the induced draft fan is subjected to radial load, and the end support bearing is subjected to radial load and axial load. The fan shaft material is 35CrMo, the bearing journal diameter is 175mm, the main shaft length is 4055mm, and the two support points span 3400mm. Problems in the fuel supply system of the unit In the case of high-load production, the turbine speed of the induced draft fan unit is 4200r/min, and the fan speed is 929r/min. The gear pump driven by the motor station motor is stopped due to electrical failure. When the lubricating oil pressure is lower than 0.03MPa, the piston of the quick closing valve cylinder should be retracted, and the speed closing valve is closed. The actual situation is that the reliability of the quick-closing valve is low, and when the valve is operated, there is a phenomenon that the closing is not strict, the delay and the non-action occur. Since the speed shut-off valve does not close the steam entering the turbine in time, the fan continues to rotate under the action of the huge inertial force, which causes the oil leakage of the unit sliding bearing, the severe wear of the rotor journal, the deceleration of the reduction gear, and the damage of the oil seal. normal production. However, the method needs to be dismantled and opened, which has a large workload, long maintenance time and high cost. This time, the method of installing the output shaft on the spot is adopted. The key is how to ensure the concentric requirements of the two axes. The fan supports the bearing block on the upper dial gauge, and checks the radial runout value of the matching part between the free end of the fan shaft and the output shaft.
Counter Current Cooling Tower has higher efficiency of the same volume, and offers larger water temperature difference. But it also comes with several disadvantages:
1.The unequal height between the air inlet and the water eliminator makes up the big Counter Current Cooling Tower and its high power consumption.
2.Meanwhile, the tower adopts nozzles to distribute water, which needs high pressure requirements and are easy to be blocked.
3.The entire tower body of the countercurrent tower is a closed structure, and it must be shut down when the equipment is overhauled or routinely maintained.
4.In addition, the rapid loss of water in the lower tank is very large, and it is easy to form water mist around the cooling tower, which is easy to cause the reproduction of legionary bacteria.
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