NOx predictions

Computational Dynamics Ltd., London, UK, has successfully used its CFD code STAR-CD to assess NOx production and the combustion efficiency of new coals in multi-burner furnaces. The trial was part of a collaborative project on the effect of coal quality on utility furnace performance.

Test burns of various UK and foreign coals were undertaken in conditions ranging from a single-burner, 40 MW test rig to a 500 MW full-scale, multi-burner furnace. STAR-CD calculations were compared with experimental results to assess the capability of the code to predict NOx emissions and carbon burn-out. Emissions were predicted to within 5-10 per cent of measured values.

The char burn-out trends were also correctly reproduced. The STAR-CD predictions show that detailed burner modelling is essential to reproduce the flame structure in the near-burner region, and providing this is done, the high accuracy of predictions can be maintained in the scale-up to multi-burner conditions.