METHOD FOR CONTROLLING HIGH PRESSURE DRUM LEVEL IN HEAT RECOVERY STEAM GENERATOR, ESPECIALLY INCLUDING A START CONTROL VALVE WITH SMALL DIAMETER AND A MAIN CONTROL VALVE WITH LARGE DIAMETER

摘要

PURPOSE: A method for controlling a high pressure drum level in a heat recovery steam generator(HRSG) is provided to keep drum level constant by switching a start control valve and a main control valve. CONSTITUTION: A method for controlling a high pressure drum level in a heat recovery steam generator includes the steps of: compensating(S2) the corresponding measurement values by measuring the drum level, the supplied water, the amount of spray flow and the main steam; maintaining the drum level a predetermined load value in one element control type considering the drum level by controlling the small diameter multi stage control valve; and maintaining the drum level by controlling the large diameter multi stage control valve above the predetermined load value in three element type considering the drum level, the supplied amount of water and the amount of main steam flow when the amount of main steam flow becomes larger than the predetermined amount.