The online world has made it a lot easier to spread common misconceptions about many things and industrial ovens are no exception. Be it about gas-fired ovens or electric furnaces, the myths are unbearable as they often lead to inefficient use and application of the equipment. So, to help you not fall victim to these myths and misunderstandings, here are some of the most pervasive ones and the truth behind them.
Myth #1. Temperature for Natural Gas or Liquid Propane Is at Around 3,500oF When Burning with Ambient Combustion Air.
This myth is so common when the topic is about flame temperatures. This can be true only if it refers to the adiabatic flame that does not lose heat to its ambient surroundings. However, in reality, flames do lose some heat and so have a much lower temperature than the figure mentioned above. This is because virtually every combustion process releases heat energy that throws off hot gases to the surroundings. Hence, the flames inside gas-fired ovens will never achieve the adiabatic flame temperature.
Myth #2. Excess Air Is Beyond What Is Required to Fully Burn the Fuel
In one way, this can be true if it means mixing the high fire amounts of fuel and air together, then adding more amount of air to reach the excess air ratio. However, most combustion ratio control systems are not following that combustion principle. Rather, they are intended to offer a specific amount of air that is enough for the desired firing rate you need while restricting the fuel flow. As a result, therefore, excess air is formed but it does not necessarily mean an excess amount of air needed to completely burn the fuel in gas-fired ovens. Instead, the proper term to refer to such excess is “fuel deficiency”.
Myth #3. Oven Efficiency and Combustion Efficiency Are the Same
While there is a similarity between these two terms, they are surely not the same. Oven efficiency refers to the amount of heat energy in the workload over the total heat input to the process. Hence, the resulting rate is always below the percentage of available heat. Conversely, combustion efficiency is often equated to available heat or the percentage of the total heat input that remains in gas-fired ovens once the exhaust gases have been eliminated.
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