Thermal Performance Of HRSG For Supercharged Boiler

Ship power system in pressurized boiler is the source for its impetus ,therefore,the design of equipments receiving gas of HRSG from pressurized boiler has great significance for marine power due to great waste of energy caused by the high- temperature exhaust gas of pressurized boiler.The difficulty in design of HRSG receiving the waste heat of pressurized boiler gas lies in its variable working conditions.Furthermore,due to big load changes of its boiler together with different speed of the ship, multiple operating points of regular running shall be considered in HRSG design.So check becomes the main way for studying its operation in thermodynamic calculation before boiler manufacture.In this article the theory of heat recovery system for pressurized boiler is described, its structural design and method of heating calculation studied, and the check of calculation on the main conditions of HRSG and analysis of its thermal parameters done.The main conclusions by checking calculation of HRSG developed by us are as follows: (a)yield of HRSG steam and temperature difference of nodes increase linearly with larger working conditions; (b)low-pressure saturated steam generated in low working conditions increases with bigger loads, achieving the design value of 1.57MPa in the conditions over 46.5% load.So this characteristic of saturated vapor pressure has greater impact on smoke temperature ,utilization rate and other parameters of this kind of boiler.Temperature of gas out of the evaporator varies with working conditions, up at bigger growth rate in low conditions and at smaller in high ones. While waste heat utilization rate increases rapidly with the growth rate of the heat load in low segment ,and drop slowly in high part.According to the research of acid dew point corrosion on its tail heating surfaces ,the gas temperature of the HRSG which receives waste heat from pressurized boiler is minimum ,namely 150℃, at 20% of the whole load of HRSG, so it can only run in 20% or more as its regular conditions .Various boiler types are proposed based on structural optimization for different surroundings by checking of calculation whose thermal calculation is carried out, and its thermodynamic parameters compared and analyzed. For example,the method of varying heating surfaces is proposed due to the difficulty in the design of varying duty of finding the equilibrium condition both for requirements of the high- and low- working conditions.