Calculation and Analysis of the Platen Superheater's Over-temperature During a 660 MW Supercritical Boiler's Deep Peaking Shaving and Research on Modification Plan
Analysis of the furnace data for the platen superheater of the 660 MW supercritical lignite fired boiler revealed that,under 175 MW load,the over-temperature alarm mainly occurred at the tubes close to the flame in the 3rd and 4th platens.To address this issue,a mathematical model to calculate the hydrodynamics of the platen superheater was established using the flow network system method,combining conservation equations for mass,energy,and momentum,and two modification plans were proposed:adding a throttle orifice and upgrading the tube materials.The platen superheater was divided into loops and tube sections,and the actual thermal deviation in the furnace was calculated using measured data at 175 MW load.The outlet steam temperatures of the platen superheater were then calculated with a throttle orifice and upgraded Super304H material under low,medium,and high loads.The calculation results demonstrate that the addition of the throttle orifice reduces the deviation of the outlet steam temperature for the platen superheater,ensuring that the outlet steam temperature for 3rd and 4th platens remains below the alarm temperature of TP347H material.Similarly,upgrading the material to Super304H leads to that the outlet steam temperature for the platen superheater is below the alarm temperature,thus ensuring safe operation.The tube wall temperature calculations and the strength checks were carried out for both modification options,and the results indicate that the wall temperature and strength are safe under various loads.To provide a greater safety margin for boiler operation,it is recommended to add a throttle orifice to the last platen and at the same time upgrade the material from TP347H to Super304H.
万方数据
维普
