A method for evaluating the safety of the corrosion fatigue of a high-pressure (HP) drum for the heat recovery steam generator (HRSG) is presented through a transient thermal stress analysis. To evaluate the corrosion fatigue, European Standard EN 13445-3 is applied to check whether the magnetite protective layer on the water-contacting surface can be preserved during the transient operating conditions: cold start, hot start, warm start, and load change. Static analysis is performed to analyze the stress due to the operating pressure, and transient thermal and structural analyses are performed for the transient operating conditions. As per EN 13445-3, the analyzed maximum and minimum stresses of the transient operating conditions at representative locations are compared with the allowable limits derived from the stress due to the operating pressure. In conclusion, the magnetite protective layer was preserved under the transient operating conditions and the HP drum was found to be safe for the corrosion fatigue. The method of analyzing the thermal stress and evaluating the safety of the corrosion fatigue presented in this research can be applied effectively in the design stage of various unfired pressure vessels exposed to high temperature and high pressure loading.

The soot blowing performance for a wall blower, according to the entering distance of a nozzle from the boiler wall, is evaluated according to a liquid droplet impingement erosion model. This erosion model incorporated the computational fluid dynamics of a jet steam of nozzle, and it uses the pressure and velocity of a jet steam at the furnace wall for several entering distances of the nozzle. A relative erosion rate dependent on the velocity of the jet steam is also introduced. Several cases are compared, as determined according to the entering distance and the number of nozzles. The shaded erosion region, according to the entering distance of the nozzle and the co-injected region, have also been schematized. Specifically, when the entering distance of the nozzle is large, the maximum relative erosion rate is small. However, the soot blowing area is uniformly large, as compared with the case of a small entering distance. This shows that the maximum relative erosion rate is high, but the soot blowing region is small and the shaded regions occur.

Industrial boilers are used in numerous fields, and heat efficiency enhancement is a major topic of study. A double-pipe boiler is a simply structured industrial boiler having a high thermal efficiency. Baffles are specially installed in the doublepipe boiler for increasing the heating time. The baffles determine the heat efficiency of the double-pipe boiler. However, it is theoretically difficult to design a baffle and locate its optimal position, solely by considering the fluid flow of heated air, and the heat exchange between water and heated air. To confirm the correct positioning of baffles, fluid flow and heat transfer simulations were conducted on the boiler. Our results showed that at some points, there was insufficient circulation of heated air. To overcome this problem, baffles were added at these points, by referring to the simulation results. The changing of baffles resulted in an increase in efficiency of heat transfer in the double-pipe boiler.