Propane Gas Burner Control

The Importance of efficient combustion and accurate proportional control.

In this day and age Energy Efficiency is the aim of all consumers.

Large Propane Heaters used in Agricultural applications consume large volumes of gas and gaining efficiency on their operation ought to be a key goal.

We believe the Farm Electronics ACE Gas Burner offers many efficiency advantages over the more common burner arrangements currently found on farms.

In order to demonstrate this claim this article attempts to explain the differences in the control and operation of each type of burner.

Efficient combustion is only achievable with the best fuel / oxygen mix being available. The Farm Electronics ACE Burner has full control of both elements.

The other burners discussed have a fixed oxygen (air) supply, which has to be matched with the maximum burner output. The fuel (gas) is then modulated to lower the flame which must mean the fuel / oxygen mix is incorrect at lower flames as too

much oxygen / air is being supplied. This will lead to incomplete (inefficient) combustion and likely flame outs. In recognition of this problem the manufacturers of these burners have to limit the amount of “Turn Down” (minimum flame) to relatively high level in order to keep the burner alight. This might not seem a major drawback until you want to accurately control a temperature or humidity level on a drying system. You will inevitably reach a point where too much heat is still being produced and therefore more gas than is necessary is being consumed in order to hit a control target. This situation is far worse on the Torpedo Style heaters which switch the gas using electrical solenoid valves in “Stages”. These stages are very large on the bigger output heaters and will only allow a very coarse control of temperature / humidity to be achieved.

The other factor to be considered is the effect of the efficiency of the fan, the burner is fitted to. The Duct Style burner is the worst offender in this area, as an air gap has to be provided, to cause the fan to draw the bulk of its air through this gap. This is to try and maintain the correct fuel / oxygen mix within the burner casing itself. This feature prevents a bellmouth intake being fitted to the fan which also compromises its efficiency.

The Torpedo Style burner scores much better in this respect as it can be stood well away from the fan leaving a normal airflow pattern and a bellmouth intake can now be used.

The Farm Electronics ACE burner offers the best set of solutions to all the issues outlined above. It is the only one that has full proportional control of the oxygen (air) supply for the gas burner head. Because of this the burner can be attached directly to the fan casing becoming part of the fan duct and the bellmouth intake can be attached to the burner casing maintaining airflow efficiency. As the gas flow to the burner is modulated the oxygen (air) flow from the burners dedicated fan is modulated in proportion using a motorised IRIS air valve. As a result a much lower turndown of 40:1 is achievable. Combined with an Artificial Intelligence PID proportional controller extremely accurate and achievable temperature / humidity targets can be maintained.