CFD Simulation of Thermal and Thermally Stressed State of the DKVR-10-13 Boiler Drum

Abstract

The urgency of the paper is dictated by the problems that arise during the operation of power boiler drums. As a result of exposure to high pressure, elevated temperature, cyclic loads, and a corrosive environment, the formation of various defects and damages, such as cracks, fatigue failures, corrosion, and others, might occur. These defects can cause accidents and even catastrophic destruction, which threaten the safety and efficiency of boiler units. Therefore, it is important to carry out regular inspections, maintenance and repairs to ensure the safety and reliability of the equipment. Work on extending the period of safe operation of the boiler, which has served its intended service life, is carried out in accordance with the provisions of SOU 40.1-21677681-02:2009 approved in Ukraine, which recommend performing calculations on the strength of boiler units elements. These calculations can be performed using modern CFD methods of computational fluid dynamics. The presented paper is devoted to the CFD modeling of the thermoelastic state of the drum-separator installed above the DKVR-10-13 type boiler fuel tank, which is equipped with burners operating using jet-niche technology. The burners differed in the type of fuel supply. In one of the burners, fuel is supplied through rectangular slits, in the other one – through round holes arranged in a row. Air is supplied to both burners through rectangular slits. The research was carried out for two operating modes of the boiler unit - nominal and at 60% capacity with numerical methods using the ANSYS-Fluent application program package. The object of the study is a boiler drum of the DKVR-10-13 type with all weakening holes. The subject of the study is the processes of thermal strength of the shell structure, which is inherent in the boiler drum, as a result of the influence of pressure, temperature and heat flow from the heated gases moving into the fuel chamber of the boiler equipped with jet-niche burners both at nominal and 60% heat load. It was determined that the nominal wall thickness of 10 mm for the drum of the DKVR-10-13 boiler, both at the nominal and at 60% heat load, is quite sufficient to ensure the strength of the drum, since the difference between the highest and lowest temperature on the surface of the drum is within 30 °C. Moreover, during gas distribution through round holes, the temperature field of the drum wall is more uniform than in the case of fuel supply through rectangular slits. The maximum equivalent Mises stress that occurs between the rows of holes on the drum reaches 75 MPa. It was also determined that the maximum deformation of the drum walls was 1.1 mm, which could not lead to the destruction and rupture of the drum under internal pressure.