Air preheater rotor stall at a factory accident analysis

Air preheater rotor stall at a factory accident analysis - 2019 10 - 01 abstract: air preheater is an important equipment, the safe operation of the unit during the commissioning of a certain power plant in air preheater rotor suddenly stalling phenomenon, aiming at this phenomenon, to analyze it. Key words: air preheater; Thrust bearing; Rotor stall 0 introduction to heat transfer principle of air preheater, is through the continuous rotation of the rotor, carrying the heat transfer element of slow rotation after into the hot flue gas and air preheater, the heat exchange. （ Juncker type) Heat transfer element absorbs heat from the flue gas side of the hot flue gas, through the rotation of the rotor, heat is heat transfer element's heat, and continually passed to the air side in the cold air, and heating the air. 1 accident process for the single series unit in one power plant, the specific system heating surface decorate a three-point storehouse rotating juncker type air preheater, two coaxial YE2 - 200 l4 motor, power rating 38 kw, 58 a rated current. Air preheater speed 0. 85 ~ 1 r/min, the transmission form of monolithic machine of decelerate of hard tooth face gear, the entire group, air preheater fan-shaped plate adjustment device not into, fan-shaped board up to the highest level, the air preheater axial sealing also attune to the maximum. Refer to history curve changes related parameters are as follows: during unit start-up, 42 - air preheater current Around 60 a fluctuation, air preheater inlet smoke temperature about 340 ℃. At the beginning of the load down air preheater current short of 62 a, exhaust smoke temperature is 132 ℃. After load down to 180 mw, air preheater around current resume to 44 a fluctuation, exhaust smoke temperature to 128 ℃, began, air preheater inlet smoke temperature 308 ℃, air preheater current suddenly by 45 a dropped to 18 a. Air preheater fire alarm temperature from 128 ℃ started to rise, came to 277 ℃. Immediately arrange personnel to the site inspection. Operating picture air preheater auxiliary motor and pneumatic motor are not allowed to start ( The main air preheater motor did not stop) 。 Site feedback air preheater spindle rotation, 8:05-8:05-7:45-7:45-7:25-7:25-7:05-7:05-6:45-6:45 boiler MFT, tripping ownership powder system. The boiler furnace is stuffy. 2 air preheater stalling accident analysis when the normal operation of the main drive motor current should be stable in the range of the rated current of a certain value, the fluctuation amplitude is not greater than & plusmn; 1. 5A。 Air preheater at run time, the current oscillation problem, its fluctuation frequency of about once every 1 second, on-site inspection heard a low blow air preheater internal grinding, it could be a fan-shaped board or axial sealing device of the reserved clearance is too small or air preheater rotor imbalance mushroom deformation due to temperature changes, cause and seal friction caused, if the motor current maximum value does not exceed the rated current, but in the case of volatile run for a long time, will cause the seal and fan-shaped plate, serious wear and tear of axial sealing device. In addition, the drive motor current increases is a symptom of a thrust bearing wear, accompanied by abnormal bearing temperature rise during this time, the radial seal friction phenomenon with the cold end segment. Result in thrust bearing the main motor side bearing damage, stress to the main motor side is aggravating, reducer damage, this inspection after the accident in the process of the collapse of the verified. 3 accident advice which is a fan-shaped board or should try to eliminate the axial sealing device of the reserved clearance is too small, in order to readjust in the furnace. Check the hot end (after the furnace The cold end) Fan-shaped board level installed, whether can take a piece of hot side ( The cold end) Radial seal as a benchmark, and check the sealing piece and three pieces of hot end ( The cold end) Fan-shaped plate gap is uniform, if more than 1 mm gap value, shows the fan-shaped plate installation does not reach the designated position, need to cut the fan plate fixed on both sides of the sealing plate, to adjust the levelness of the fan-shaped plate; Can use the same method to check the installation of axial sealing device. In the design of factory requires the introduction of 'rotor stall signals, once the' rotor stall occurs, immediately stop running motor and pneumatic motor automatically. Purpose is: when a motor and the transmission mechanism between the rotor fault, the likely scenario is' motor turns, the rotor turn; Interlock protection function of rotor stall in pneumatic motor and automatically makes the air preheater continues to run normally, can automatically stop running motor, termination may continue to damage of transmission mechanism. So I think it is necessary to introduce the 'rotor stall interlock protection function in the actual control logic. （ Here you need to consider whether stable reliable rotor stall) 4 summarizes this accident has certain representativeness, because it is a new operation of air preheater, there are some fluctuations, friction and current manufacturer habitually blamed it on the new air preheater to grind, hoping for good after polishing equipment will run normally, as a result, current and the different sound did not cause people value, in addition, improve the quality of equipment, to prevent low price bidding, in order to ensure the quality of equipment, still need to strengthen the crisis consciousness equipment, guarantee the safe operation of equipment, timely find out abnormal reason, formulate measures.