Burner Testing – Where and When
Burner demonstration tests should be conducted at the burner supplier’s facility for all new burners or any change in burner design. The burner test should be omitted only for simple “replacements in kind.”
Gas should be blended to the design heating value and specific gravity. Oil should be temperature-controlled to the design viscosity. Steam consumption for oil atomization should be measured.
Operating headaches can be eliminated by testing burners at the supplier’s plant prior to installation in refinery heaters. A successful test is not an iron-clad guarantee of good performance in the field. However, poor performance on test is an absolute guarantee of poor performance in the field.
For years, we bought burners without testing them, but what you rarely hear about are the operating problems that had to be solved after installation to get those heaters to operate efficiently. Many of today’s fired heaters don’t operate as well as they might, had burner problems been identified and ironed out prior to installation. An installed heater is not the place to play with modifications to improve burner performance.
Some fired heater manufacturers routinely test burners for all their large heater designs. Typically, they test a burner taken at random from the production line. This test comes too late if design changes are needed. A successful demonstration test should come before production as a condition of purchase.
Two general kinds of burner problems are discovered during testing: 1) combustion problems relating to such things as flame size and stability, and 2) mechanical problems such as potential for poor burner fitup to the heater and difficult air register operation. Even standard, off-the-shelf burners should be tested because they can vary depending on who handles the job at the vendor’s plant.
Because burners often operate far from design conditions due to operating necessity, control fluctuations or occasionally to maladjustment, we test them through their entire operating range. As an example, we tested an off-the-shelf burner that happened to be supplied with a pilot. (Usually we don’t use pilots but prefer to rely on minimum gas bypasses.) The test procedure should always include slamming the air registers wide open at maximum draft and minimum gas-only firing rate to make sure the burner can’t be blown out. When we did this, the gas flame remained perfectly stable (as it should) but the pilot blew out!