COUPLED FLOW – THERMAL STRUCTURAL ANALYSIS OF RECTANGULAR AIR-COAL MIXTURE CHANNEL
Existing air – pulverized coal mixture burning channels at boiler A1 in the TPP Nikola Tesla in Obrenovac are of the rectangular, downstream variable cross section, with overall dimension of 4m length, 1.2m wide and 0.26m (inlet) to 0.535m (outlet) height. The thickness of this thin walled stainless steel structure, rigidly supported (welded) in the inlet, outlet and the first cross section of height changes, is 10mm. Temperature of air coal mixture, conveyed through this channels, is regularly above 140 oC.
New system for coal fire support and stabilization in the furnace, based on thermal plasma, is planed to be an alternative to existing oil burner’s system at boiler A1. According to preliminary calculations and measurements on the experimental and pilot facilities with plasma system in operation, the air coal mixture temperature arise up to 1200oC, inducing that burning channel walls are heated on the temperature more than 700 oC.
The goal of this work, within the project of investigation and development of a new system for the fire support based on thermal plasma, is to analyze influences of thermally loaded channel structure dilatations on air-coal mixture flow through it and vice versa. Structural simulation was done using Ansys, while flow simulation was conducted using CFX software.
The results of the coupled flow-thermal-structural parametric study of the coal mixture channel for the range 300…700oC of the inlet mixture temperature and 10…300oC in the channel’s inner and outer wall temperatures difference (depending on the insulation of the channel) shows that channel complex geometry will deform in couple different shapes, depending on the level of the inlet air coal mixture temperature and supposed insulation of the channel. Accordingly, the deformation and stresses field distribution in the channel wall, flow field and pressure drop in the channel depends of these two parameters.
Zoran Markovic, Laboratory for Thermal Engineering and Energy, Institute of Nuclear Science “Vinca”, University of Belgrade, Belgrade, Serbia, e-mail: firstname.lastname@example.org