In my last column ("Flame Temperature: What Is It?"), I delved into flame temperatures and the factors affecting them. To round out your understanding of the subject, I'll look at what happens to the flame and its temperature after combustion begins. To make sure we're all starting with a common understanding of the process, I'll review a few key points from the last column.
The adiabatic flame temperature of natural gas, burned with the chemically correct, or stoichiometric, amount of air is about 3,600°F (1,980°C). Adiabatic flame temperature is defined as the temperature the combustion gases would reach if they didn't give up any of their heat to their surroundings. It's an unachievable ideal, because they do, indeed, lose heat to nearby oven walls, workloads and anything else in their line of sight. In addition, at high temperatures, some of the CO2 and water vapor in the products of combustion undergo a sort of reverse combustion, reverting to CO, hydrogen and oxygen and stealing back part of the heat they had previously released. This process is called dissociation.