Interchangeability of Mixed Gas Components for Heating Industrial Furnaces

The interchangeability of gases can be assessed by various parameters such as burning rate, flame stability, combustion perfection, calorific value, combustion temperature, quantity and composition of flue gases, most of which cannot be met at the same time. The new composition of the gas mixture must be controlled according to the selected criteria, in particular the calorific value, Wobbe number etc. An example from industry illustrates the practical impact of interchangeability of gaseous fuels on the operation of a tunnel furnace for heat treatment of products. Due to limited availability, coke oven gas was compensated by increased addition of natural gas. Although the same calorific value of the new gas mixture was maintained, the change in mixing ratio led to an increase in gas consumption. Effects of several simultaneous causes on the furnace efficiency and gas consumption are analysed in the paper. The main causes of the increase in gas consumption were found in the decline in Wobbe number, reduction in production and changes in flue gas temperature and chemical composition.