One of the strongest utilities of CFD is the ability to map and investigate internal flow processes, which would otherwise be an expensive and time consuming effort to measure in practice. One of the best example of this concerns furnaces. And so, R&R Consult were tasked with a thorough investigation of the combustion process at the biomass cogeneration plant of Verdo in Randers, Denmark. The goal: to map the flow-, temperature-, and species distribution inside the furnace, during several production loads – and help highlight means of limiting emissions of CO and NOx.
Verdo cogeneration power plant, Randers, Denmark
The case saw the conduction of several simulations of the combustion process, in a fully detailed model of the furnace, featuring primary- and secondary air supplies, gradual combustion steps on the grate, and stoking of primary and overhead fuel sources.
Bed model for controlling the combustion on the grate
Outline of furnace, Temperature and velocity distribution and pathlines
Through the results, it was possible to determine flame development and resulting temperature distribution inside the furnace – as a result of fuel composition and location of secondary air nozzles. The model also helped identify areas of potential air deficits, which may lead to incomplete combustion and residual CO. Finally, the results were used to give indications on adjustments to air supply, both primary and secondary, as well as the optimum location for SNCR installation.
Temperature contours