Numerical and experimental study of temperature distribution on thermal plant coal mill walls

Abstract

This article presents results of a numerical and experimental study of the temperature distribution inside and on the walls of the ventilation mill in the Kostolac B power plant, Serbia. This is very important because heat exchange between gas mixtures, ventilation mill walls and the environment, influences coal powder temperature, the combustion process, and the emission of greenhouse gases. The most complex multi-phase model in the Euler-Euler approach has been used through the ANSYS FLUENT code, for the numerical simulation of temperature distribution. Two ventilation mill models have been considered, one with zero wall thickness and the other one with steel walls, with and without insulation. An infrared thermographic camera was used for monitoring the temperature distribution on the outside wall of the ventilation mill housing, before insulator reparation, while after the reparation measurements were carried out at the selected points with infrared thermometer. The experimental results were used for verifying the results of the numerical simulation method as well as for detecting the damaged insulation.

Turbulence recognition in free convective flow by thermal-video post-processing in the case of a thermal power plant mill

“…The prepared coal mass, with impurities like sand and mineral particles, enters the VM from the dozer. The VM is continually fed with the coal mass heated by air (≈ 250 ºC [14]) through the front inlet located in the rotor center. The VM is of EVT N 270.45 type (nominal capacity ≈ 76 t/h of coal).…”

“…The process of coal pulverization produces fine particles of coal (average 150 m in diameter). Pulverized coal, carried by a recirculation gas, forms a lifting stream ( T exit = 168 ºC [14] at the VM exit). The mixture is directed upwards, to the channel with separators, directly to the system of four-level burners.…”

“…The aim of the initial investigations was to detect the positions of the insulation damage using IRT. Extensive investigations of the VM at the TPP "Kostolac B", Kostolac, were conducted by numerical simulations and IRT in order to improve functional efficiency [14,15]. The potential of IRT for turbulence recognition became clearer when the analysis was extended to include the extreme surface temperature differences noticed from thermal videos.…”

Corrosion resistance of metalized layers on steel parts in ventilation mill

“…Also, application of wear resistant coatings additionally extended the working life of ventilation mill parts. Results of numerical simulation, as well as deposition of wear resistant coatings by metalization and hardfacing technique, are discussed in detail in [6][7][8][9].…”