The higher the main steam temperature, the more economical the operation of the steam turbine. However, in actual operation, due to the direct contact between the inlet and high-pressure parts of the steam turbine and high-temperature steam, when the steam temperature is too high, the mechanical strength of the turbine components will decrease due to the temperature rise, resulting in a relatively shortened service life of the unit; When the temperature of the main steam decreases, the output power of the steam turbine decreases accordingly. In order to maintain the same power of the unit, it is necessary to increase the steam inlet, which causes an increase in the axial thrust of the rotor. In addition, when the temperature of the main steam is too low, it is easy to increase the loss of moisture in the low-pressure stage, which will exacerbate the erosion of the moving blades.
The increase in main steam pressure enhances the steam's ability to do work. But if the pressure is too high, the corresponding pressure difference between the inlet and outlet of the nozzle will increase, and the bending stress of the regulating stage blades will increase, which will cause damage to the blades and nozzles, and increase the stress of pressure bearing components such as the air duct, steam chamber, and valve, posing a threat to the safe operation of the unit; The main steam pressure is too low, the economic efficiency of equipment operation is reduced, the available enthalpy drop of the steam turbine is reduced, the steam consumption is large, the axial thrust is increased, and the stress borne by the last stage blades is increased, resulting in blade deformation.
Therefore, during the commissioning and operation of the steam turbine, the temperature and pressure of the steam must be maintained within the design range and adjusted appropriately according to the actual situation to ensure the economical and stable operation of the air separation equipment.
