Determination of the Optimal Initial Steam Pressure for the Power Plant Under Different Loads

Abstract

Combined with the thermal system analysis, the mathematical model for selecting the optimal initial pressure of the power unit is established based on the comprehensive consideration of the effect of main steam pressure on governing stage efficiency, steam feed pump consumption and flow passage efficiency. Then the steam pressure with the maximum unit efficiency is searched using variable condition calculation. With quantitative calculations of N600-16.7/537/537-I unit of Pan Shan thermal power plant taken as an example, the optimal initial pressure is obtained by exhaustive method around the 75% load point. The results reveal that the unit power, heat absorption and unit efficiency all increase with the increase of the main steam pressure. However, the increasing velocity of efficiency is less than heat absorption when main steam pressure attains to certain value, which makes the unit efficiency begin to decrease. Therefore, this main steam pressure is the optimal initial point to be searched.