An integrated computational fluid dynamics–process model of natural circulation steam generation in a coal-fired power plant

A semi-detailed 1D process model for steam generation in a natural circulation boiler (thermosyphon loop) is linked to a detailed 3D computational fluid dynamics (CFD) model of the coal-fired furnace. The CFD model has been validated against typical data from a 500 MWe subcritical power plant. The heat flux distribution data from the CFD model are regressed into a function of height and used to drive the process model. The complex physics occurring in the furnace are coupled with the thermosyphon steam loop, resulting in circulation flows of around 4 times the feed flow. The steam side heat transfer coefficients are predicted in the process model and so the overall heat transfer coefficient for use in the CFD simulation can be re-evaluated as a function of height. The recalculated heat flux distribution is almost identical to the original, because the dominant resistance to heat flow is on the furnace side.

► A thermosyphon loop used for steam generation in a pf power plant has been modelled.
► A coupled fluid dynamics–process approach using regression analysis was used.
► The combined simulations revealed circulation flows four times the feedwater flows.
► Iterative calculation may not be necessary; the furnace side resistance dominates.
► The technique is applicable to any type of coal boiler.