The change of the steam turbine axial thrust under special conditions

Under special working condition of steam turbine axial thrust change 2018 - 11 - 15 1 new steam temperature reduce the machine ideal enthalpy drop at this time, each level is less than the enthalpy drop, leading to increased faster than at all levels and reaction degree increases, so the axial thrust increase. 2 water shock when steam turbine water shock occurs, steam temperature is reduced, reaction degree increases; In addition, when the water into a hot body, part of water by evaporation, higher level of pressure, so axial thrust increases. When a large amount of water into the steam turbine, in an instant all or partially blocked the flow section, a certain level to level stuck in front of the pressure increased sharply, and class after pressure was sucked for steam condenser and reduce, so stuck suffered large axial thrust level, until the steam will all the water out, this process lasts only a fraction of a second. 3 load jump when the load suddenly increases, the axial thrust of the steam turbine is bigger than normal. This is because by this time steam to the previous level of heat transfer and lower the temperature, metal level than enthalpy drop, as to make the reaction degree increases. In addition, because the diaphragm compared with the impeller wheel, baffle heat faster, make steam seal clearance increases, leakage is thus increasing, the impeller before the pressure increased, the axial thrust increases. 4 load shedding load shedding if the valve unsmooth, instantaneous rise, speed will be faster than the increase and make the reaction degree increases, so axial thrust violently. But this is a smaller effect on reaction turbine. 5 blade scaling of the steam turbine passage parts are generally moving blade scale than the nozzle is serious, this is mainly because Suo mouth RGL flow velocity is larger, steam carried in salt concentration down. Thrust tile the influence of the temperature changes: (1) thrust bearing is composed of thrust tile work and non-work thrust segment. It is under the axial thrust of the rotor, general single-cylinder steam turbine, steam along the flow direction of the direction of the axial thrust, thrust segment by work to bear; Multi-cylinder steam turbine due to the high and middle pressure cylinder steam flow reverse flow, the axial thrust by the difference of the two, if the high pressure cylinder thrust is greater than medium pressure cylinder thrust, can form the axial negative thrust, the non-working thrust segment, under thrust temperature is varied with the change of axial thrust and the corresponding change, sometimes working thrust tile non-working thrust segment have different temperature, an individual segment temperature is very high, it is uneven in under the action of thrust tile demanding or a fault segment, caused by the poor lubrication, the need to strengthen the monitoring, prevent segment all or partial melting, caused severe damage to parts on steam. (2) the change of the axial thrust, thrust tile of the oil film pressure sensitive than thrust tile temperature changes quickly, the change of the temperature of thrust tile than thrust bearing is sensitive to temperature changes. No push oil film pressure and temperature of thrust tile mark whatever unit, temperature monitoring of thrust bearing more should pay attention to, sometimes thrust bearing temperature rise only 1 ~ 2 ℃, sharply to wear a lot, if the temperature rise of 8 ~ 15 ℃, is not only sharply has melted, and tile itself have also been badly worn.