Influence of parameter deviations during start-up on the рower рlant equipment thermal stressed state

The current guidelines recommend evaluating the quality of start-up and shut-down modes, as well as operation modes under load, according to the compliance of start-up parameters with start-up assignment schedules, standard instructions, a regime map, reliability criteria and their limit values. The quality of maintaining operating modes is proposed to be assessed by the assigned deviations of parameters from the values specified in standard instructions or start-up schedules. The authors analyze the suggested approach and the accepted values of the parameter permissible deviations, according to which the start-up operations quality is assessed in terms of the thermal stressed state of the thermal scheme critical elements. The analysis was performed on the basis of the thermal stressed state calculations of the most loaded steam turbine high-pressure rotor and the high-pressure heat recovery steam generator superheater outlet header with deviations of the live steam temperature from the start-up schedule. It is proposed to evaluate the quality of start-up modes based on the calculation of the cyclic strength the power plant “critical” elements, and not by exceeding the control parameters values without taking into account the specific time of this excess occurrence in relation to the schedule, the temperature state of the element under consideration, steam flow, etc. All parameters deviations considered as an example do not affect the cyclic strength of the equipment in question. The most accurate assessment of the regime quality can be carried out as a result of monitoring the turbine and the boiler unit operation modes, which will make it possible to control compliance with the reliability criteria, preventing them from being exceeded.