Burners

Pulverized coal burners function in a unique manner, and this program re-evaluates all of the affecting parameters to re-size, if necessary, the coal nozzle, burner throat, inner air/outer air partition, and perhaps some of the air register size components.

Old-school coal burners (ie, pre-NSPS), usually operated at full load with a secondary air velocity of about 140fps, and sometimes higher. Similarly, primary air exit velocity was around 90 fps. In today’s Low NOX Burners these velocities are much less. The burners also operate at a specific secondary air-to-primary air ratio, and they have much, much less room for operation outside these design targets. The reason? When the primary air and fuel ignite in front of the burner nozzle they expand rapidly into the secondary air, which is why burner secondary air exit velocity is much higher. The smaller the absolute numbers become, the narrower the tolerances become. If fuel or air velocity is too high or too low, then fuel can either escape to increase LOI and CO, or become a high-NOX hot spot. The entire phenomenon is aggravated by substoichiometric firing and by spot market coals.

Our program investigates the existing coals, equipment dimensions, OFA if it applies, and operating scenarios, and calculates the correct nozzle, partition and throat sizes for optimum burner performance. Our engineers have designed burners and burner parts, so we can also do all the engineering for the re-sized components. A typical Burner Optimization Program would include:

Burner Optimization Program

• Gather dimensional drawings for burner, burner nozzle, air register, waterwall, and burner throat.
• Gather applicable coal analysis data and operating data, including intended excess air and burner stoichiometric ratio.
• Calculate existing primary air, inner secondary air, and outer secondary air velocities, and the outer air/primary air velocity ratio.
• Calculate optimized primary air, inner secondary air, and outer secondary air velocities, and the outer air/primary air velocity ratio.
• Re-calculate burner and air register dimensions required to result in optimized velocities.
• Investigate operability and effectiveness of the proposed optimized dimensions at low loads.
• Investigate the practicality of revising dimensions, and make recommendations with practical results.
• Implement changes.
• Burners are optimized and available for optimized tuning.

See Boiler Balance Program.