原子力プラント向け抽気絞り運転制御方式の検討

抄録

As a power generation control method for utilization in nuclear power plants, the turbine bleed valve operation known as condensate throttling (CT) which controls the extraction steam flow rate from a steam turbine to increase generating power has been studied. The purpose of this paper was to evaluate the applicability of the CT to nuclear power plants which have been conventionally operated as a base load power source in the future when use of thermal power plants has to be suspended to reduce greenhouse gas emissions. First, in order to evaluate the basic CT characteristics in nuclear power plants, a dynamic characteristics simulator for the nuclear power plant balance of plant (BOP) system was developed. Next, an effective CT operation method for improving the power generation output was devised, and the dynamic characteristics of the BOP system during CT operation were evaluated using the dynamics characteristics simulator.

The feedwater temperature decreased due to the CT operations. The amounts of the decrease were estimated to be 91.3% of the rated temperature in plant rated load for the case that reactor heat output was the rated value, and 93.2% for the case that reactor heat output was increased from the plant partial load of 95% to 100%. The power generation output increased due to the CT operations. The amounts of increase were estimated to be 4.5% of the rated output for the case of the reactor rated heat output operation, and 5% for the case that the reactor heat power was changed from the plant partial load of 95% to 100%. Assuming that the rated power generation output was 1300 MWe, the power generation output increase was equivalent to the capacity of one or two small- and medium-capacity gas turbines or one small-capacity coal-fired power plant. From the above, it was judged that nuclear power plants could be evaluated as having the ability to adjust supply and demand of electric power systems by CT operation.