Chandrakishor L. Ladekar, Manoj R. Dahake, Chandrakant B. Kothare, and Ajay V. Kolhe
Flow analysis, CFD analysis, boiler economiser, erosion failure, boiler tube leakage
The forced outages in the thermal power plants are due to boiler tube leakage (BTL) as they run at full load, which affects the power plant’s performance. The areawise and causewise boiler tube failure data analysis showed more percentage failure in the finned tube economiser due to erosion and overheating of the tubes. Computational fluid dynamics (CFD) modelling can be applied in the power plant economiser. This work focuses on CFD analysis of a finned tube economiser to see velocity, temperature, and pressure at various places in the economiser. A comparison of simulated velocity with cold air velocity test data showed that actual velocity along the water wall is approximately 10–20% more than measured by simulation. Further investigation in close view shows that the tube failure occurs at U-bends due to ash particles’ high velocity and temperature. The low temperatures at the corners of the attached fin resulted in the welded corner’s failure, further validated through the tube failure data. A low temperature on the downside leads to pitting damages. Pressure variations show the low pressure on the downside of the tube, resulting in the un-uniform pressure of the fluid particles in close vicinity to the tubes of the economiser and a reduction in the heat transferring area. Redesigning the fin structure over the tube is suggested to eliminate this problem. High static temperature and velocity were observed near the walls. This helps to identify the location and magnitude of the temperature and velocity for further modification. The modification in terms of re-designing the fins over the tube, placement of the baffles in the flow passage, and introduction of the mixing chamber and blowers were suggested based on the study. The impact of the flue gases can be predicted using the advanced technique of life-placing baffles, which will expect the tube life based on the simulation model and can reduce the cost of experimentation.
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