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Coal powder fractions distribution in thermal power plant mixture channel presented by numerical calculations

Zivkovic N., Stefanovic P., Cvetinovic D.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

2008

z. 73 [253]

311-318

One of the problems during exploalation period of thermal power plant is in determine and optimize distribution of various coal powder fractions in the mixture channel. Regulation of distribution with shutters, positioned after the mills, is proposed solution. The paper present distribution of coal powder fractions, obtained by numerical calculations, using numerical software for modelling of two-phase flow problems. The problem is two-dimensional, considering that, transversal dimension of the domain is relatively big compared with the other two dimensions, and volume occupied by solid phase is much less than volume occupied by continual phase. Continual phase is treated by an Eulerian approach, and solid phase is modeled by Lagrangian approach. The model takes in consideration coupling of phases by PSI-CELL method. Turbulence was modeled with standard k-ε model. The model treats particles as an ideal sphere. In order to determine particle movement, all relevant forces, (with continual affect and impulse affect), are incorporated in the model. The results obtained, include velocity field and profiles of continual phase, concentration field and profiles of coal particles and mass flow distribution at the outlet cross section of mixture channel for various coal particle diameters and various angular positions of shutters.

Numerical simulation of coal powder distribution along the air-coal mixture channel influenced by various shutter angles

Zivkovic N., Stefanovic P., Zivkovic G., Cvetinovic D.

Zeszyty Naukowe Politechniki Rzeszowskiej. Mechanika

2006

z. 68 [231]

261-268

For implementation of the plasma system for mineral oil free combustion support and start-up on power plant boilers few technical problems have be to solved. One of the key requirements in the implementation process is a regulation of coal powder distibution in the mixture channel in order to achieve adequate concentration in the zone where plasma has to be introduced. Regulation of powder distribution with shutters, positioned in the vertical section of the channel after the mills and prior to plasma generators is proposed solution. The paper represents numerical simulation of this problem using numerical software for modelling of two-phase flow problems, developed in Laboratory of Thermal Engineering and Energy. The model is based on Euler-Lagrangian approach. Continual phase was treated by Euleiran and disperse phase was treated Lagrangian approach. For turbulence modelling a well known k-!!! model was used. The computation results were obtained for three combinations of shutter system positions. The input data were velocity profile of continual phase and concentration profile of disperse phase in the inlet cross section, obtained by experiments. On the basis of the presented results it can be concluded that the positions of groups of shutters has a great influence on flow and concentration field in the burner channels, therefore it should be properly adopted as an adequate regulation method.