Thermal-Hydraulic Calculation and Analysis on Evaporator System of a 1000 MW Ultra-Supercritical Pulverized Combustion Boiler with Double Reheat

Abstract

A double reheat ultra-supercritical boiler is an important development direction for high-parameter and large-capacity coal-fired power plants due to its high thermal efficiency and environmental value. China has developed a 1000 MW double reheat ultra-supercritical boiler with steam parameters of 35 MPa at 605°C/613°C/613°C. Reasonable water wall design is one of the keys to safe and reliable operation of the boiler. In order to examine the thermal-hydraulic characteristics of the double reheat ultra-supercritical boiler, the water wall system was equivalent to a flow network comprising series-parallel circuits, linking circuits and pressure nodes, and a calculation model was built on account of the conservation equations of energy, momentum and mass. Through the iterative solving of nonlinear equations, the prediction parameters of the water wall at boiler maximum continue rate (BMCR), 75% turbine heat-acceptance rate (THA) and 30% THA loads, including total pressure drops, flow distribution, outlet steam temperatures, fluid and metal temperatures were gotten. The results of calculation exhibit excellent thermal-hydraulic characteristics and substantiate the feasibility of the water wall design of the double reheat ultra-supercritical boiler.