Burner Malfunction

As part of any hood survey burner exhaust gases should be tested. Just because the combustion airflow and gas are operating at the appropriate stochiometric ratio does not guarantee good burner performance. Also, making a judgement call on the quality of a flame as viewed through a sight glass can lead to wrong conclusions. In this example a machine did not seem to be performing up to its designed drying capability.

Energy consumption was very high. In the course of a survey of the hood it was found that the supply flow after the burners was generating carbon monoxide in the range of 2000 ppm or greater. This indicated very poor and inefficient burner performance. A series of attempts were made to adjust the gas/airflow mix to the burner. The supply air was monitored while adjustments were made to the airflow. In fact increasing combustion airflow actually made the problem worse. It was decided at the next down to do a thorough burner inspection.

The inspection identified the source of the problem. Shrouds that protected the flame from quenching by the makeup air were removed when the burner was replaced. Because of the ductwork design makeup air entered after the burner and perpendicular to the flame. This cool air striking the flame reduced combustion efficiency and therefor generated high CO counts. By increasing the combustion air the flame was cooled even more which produced the increased CO counts.

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© 2007 PROdry Technology, Inc. Site last updated 3/7/07