Combustion in industrial burners
Burners are used in industrial processes, and their function is to generate the flame that will give off heat when burning fuel. In this article we are going to talk about gas-combustion burners in industrial furnaces, describing the most relevant aspects of each type in terms of fuel consumption, speed and temperature homogeneity.
Self-recovery direct-fired burners
Burners with integrated heat recovery are the most efficient at recovering heat from flue gases in industrial furnaces operating at high temperatures.
Self-recovery burners have a ceramic bed through which the combustion gases are passed before being sent to the chimney, so that the sensible energy carried by these gases accumulates in the ceramic bed.
After a period of time, the system switches over and passes cold air through the bed, which steals the accumulated energy and returns it back to the system with heat recovery efficiencies between 70 and 85%, allowing significant fuel savings depending on the operating temperature of the process.
Performance and energy savings in heat-recovery burners
Evidently, with self-recovery burners, higher combustion yields are obtained with lower natural gas consumption. This technique makes more sense the higher the treatment temperature. For example, at a treatment temperature of 900ºC, the efficiency of conventional burners is 52%, compared to 67% for self-recovery burners, translating into energy savings of 22%.
Depending on the mix of heat treatments, this may or may not influence the overall result, since at low temperatures the yields are not very different and the energy savings may not be as significant. Another factor influencing the result is the case of controlled ramp-ups — in these cases, you do not always work at high temperatures even when quenching, normalizing, etc.
Difference from high-speed industrial burners
High-speed burners maximize the speed and circulation of the gases inside the furnace chamber throughout the load. This increases the temperature homogeneity in the batch.
Self-recovery burners are medium-speed, although the suction effect of the combustion gases through the burners and the recuperator also generates more gas circulation in the combustion chamber.
The high degree of recirculation caused by high-speed burners favors temperature homogeneity, which can also be achieved with self-recovery burners — depending on the arrangement of burners, split plugs, and other elements in the furnace hearth, which can ensure greater recirculation underneath the load.
At ULMA Forged Solutions, we have heat-treatment lines and our gas furnaces are equipped with self-recovery burners.