Gas inlet temperature to furnace

An increased intake temperature of the gas is beneficial for combustion. The maximum inlet temperature of the gas depends mainly on whether the electronic components such as the gas valves in the burner can withstand it. Dunse’s solenoid valves can handle temperatures up to 60°C.

The gas inlet temperature depends on the burner; some burners do not allow hot gas to enter them. In general, it is not advisable to let hot gas enter the burner, as poor control of the air temperature can easily lead to premature combustion or backflow of gas, resulting in damage to the burner and posing significant safety risks to the operation of the boiler.

For some gases with a low calorific value, it is necessary to preheat them in order to increase the combustion temperature inside the furnace. I am mainly interested in knowing whether there are any requirements regarding the upper limit of this preheating temperature

Burners generally require an ambient temperature below 40 degrees Celsius. The temperature of the gas is generally referenced to this temperature. The temperature of the gas should not be too high. On one hand, this is due to the changes in the properties of the gas at high temperatures; on the other hand, many of the seals used in gas pipes and fittings are made of rubber. For example, in the parts where solenoid valves cut off the flow of gas, these seals can easily deform at high temperatures, resulting in poor sealing. The same applies to pressure switches, pressure regulators, and so on. As for raising the combustion temperature, I don’t recall any mechanism for preheating the gas; instead, it is the air that is preheated, with the inlet air temperature reaching nearly 300 degrees Celsius. However, the burner is different from ordinary burners in terms of its design – for example, the sensors used must be those capable of withstanding high temperatures.