The Analysis Of The Bypass System Design In USC Fossil Fuel Power Plant

At present, the rounded system of the Ultra supercritical (USC)unit in design, construction and operation was formed, and the technology of electric power generation was mastered through introducing and absorbing the foreign advanced technology, which achieved international advanced level. As USC units with high efficiency will share the basic load in the system primarily, it's important that the economic and practical bypass system was selected in the prerequisite of assuring the safe start-stop of the units.The start-up process, the characteristic of host machine and the relationship between host machine and bypass system in three different start-up styles were presented in this paper. Besides, the influence of the bypass capacity on the start-up of unit, the calculating method of the bypass capacity including its different definitions at home and abroad, and the control mode of the bypass in the course of the start-stop of the units were pointed out, comparing with three different programs in technical economy including two-stage series bypass with high-low pressure, one-stage large bypass with high pressure and triple-purpose bypass system. According to the cost performance, two-stage series import hydraulic bypass with high-low pressure in 40% BMCR was selected on the Siemens steam turbine in STC.