In the first and third stage superheater and two-stage high temperature reheater in a 1 000 MW doublereheat unit tower-type boiler

the tube wall temperature is far away over the limit temperature. To solve this problem

many measures related to optimization and modification of the heating surfaces have been proposed

on the basis of the site operation data and simulation thermodynamic calculation results. By cutting two outboard tubes on the secondary superheater

the heat absorption area of the superheater decreased by 28%. By installing throttle short tubes on both sides of the high pressure and low pressure reheaters

the coolant flow rate of the central tube group increased. For some of the seriously over-temperature tubes

part of the high pressure high temperature reheater tubes were cut short and the low pressure high temperature reheater was painted with thermal insulation material. These measures greatly reduced heat absorption of the relevant tubes and the tube wall temperature reduced dramatically. After the comprehensive retrofitting and adjustment

the over-temperature problem of the superheater was basically solved during the boiler load change process. Under full load working conditions

the superheated steam temperature and two-stage reheat steam temperature approached the design value. No metal tube wall temperature alarmed. The comprehensive renovation plan greatly improves the safety and economy of the boiler operation.