- 12:30 PM

A Dynamic Model for a Cupola Furnace

Sten Bay Jorgensen, of Chemical and Biochemical Engineering, CAPEC, Technical University of Denmark, Søltofts Plads, Kgs. Lyngby, DK 2800, Denmark and John Bagterp Jorgensen, Informatics and Mathematical Modelling, Technical University of Denmark, Richard Petersens Plads, Building 305 Office 109, Kgs. Lyngby, DK-2800, Denmark.

Cupola furnaces are widely used in the foundry industry and models have previously been developed. However, the focus of most previous cupola model developments have aimed at foundry related problems which are different from those of stone wool production.

A dynamic mathematical model of a mineral melting cupola furnace is used to illustrate how different process parameters affect the static and dynamic operation. A mathematical model of a mineral melting cupola furnace for stone wool production has been developed for improving cupola operation. The one space dimensional first engineering principle model includes mass and energy balances for the gas phase, solid phases for mineral and coal and a liquid mineral phase. The gas and solid/liquid phases flow counter currently. Several chemical

reactions account for conversion of coke, limestone and gaseous species. The heterogeneous reactions of coke conversion are limited by both kinetics and mass transport. Heat transfer between phases is modelled including both convection and radiation.

The model predicts gas concentration, mass flow rates and

temperature profiles of solid, melt and gas in the cupola and the heat loss to the water cooled walls. Input to the model is the coke, rock and blast air properties and blast air amount and coke percentage in the charge. The unknown model parameters have been estimated based on input/output measurements. Comparison of model predicted and measured concentration and temperature profiles inside

the cupola shows good agreement. The static model behaviour is compared to experimental data and rules of thumb for steady state cupola operation at stone wool factories. The comparison with the rules of thumb indicates that the model well captures the essential phenomena in the process including description of gas concentrations, temperatures and flow rates inside the cupola.

The dynamic model behaviour during start-up compares qualitatively reasonably well to industrial practice. The behaviours in response to step changes in air inlet temperature and coal loading also compare favourably with industrial experience. Thus the dynamic model is ready for further design and study of model predictive control.