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Ultra-Low Nox Coal Burner
 
 

Figure 1. ULTRA-LOW NOx BURNER
Burners' development remains the most economical way of nitrogen oxides emissions reduction. Coal burner series PPX-300 (Figure 1) culminates 30 plus years of Low-NOX burner development and provides multiple benefits that include superior emissions performance, wide turndown ratio, high reliability, and simplicity of design combined with the ease of control and installation. Burner design is modular; it allows accommodating various site-specific conditions. This burner series is supplied to fit customers’ request and may include
a). Scroll or elbow type of coal inlet,
b). Gas or oil igniter,
c). Electric or pneumatic actuators, in any combination with the manual ones,
d). Modular burner design is available (supplied as a single assembly).

The emphases put forth on burner design resulted in numerous advantages summarized below:
  1. Simplicity of design - fixed register with no moving parts exposed to high temperature
  2. Unique secondary air swirl control (Swirl parameter varies from 0 to 3)
  3. Reliable secondary air flow measurements through individual parallel path, allowing for fine tuning of emissions and unburned carbon
  4. Register designed allows to minimize air bias between burners (less than to ± 2%) for common windbox installations and eliminates the need for additional control means
  5. Self-cleaning capabilities especially important for installations with regenerative air-heater
  6. Unique coal nozzle design allows stable fuel ignition and is suitable for combustion of various fuel grades from lignite to semi-anthracite
  7. Reliable on-line pulverized coal measurements are provided to further suppress NOx emissions control
 
 
 
PPX-300 burner series is designed to work on wide range of coals from brown coals to semi-anthracites. Burner performance is typically depends on the ratio of fixed carbon (FC) to volatile matter (VM), which increases for hard-to-burn coals.
Preferred operating conditions for PPX-300 include coal fineness around 80% passing mesh 74 mkm. Burner design also allows adjusting for broad range of primary air to coal ratio (ACR). Depending on combustion system configuration and selected coal mills burner successfully operates ACR within 1 to 3.
Special coal nozzle design exploits Coand effect to provide deep fuel staging at the nozzle outlet resulting in superior suppression of nitrogen oxides.

 
Emissions performance in terms of NOx for PPX-300 is shown in Figure 2. Data in this figure covers various commercially available boiler sizes. NOx formation increases for “hotter” (larger) boilers. It is directly proportional to the specific heat liberation (relative to the "burner basket" size, and with fuel rank as defined by FC/VM ratio. Our data above presents typical burner performance on coals with nitrogen content around 1.50% (as received) and the oxygen concentration in the flue gas 3% vol.dry at the air-heater inlet. At these conditions and furnace stoichiometry at 80% to 85%, carbon monoxide emissions do not exceed regulated values, while heat loss with unburned carbon varies from 0.1% to 1.2% and is directly proportional to FC/VM ratio.
PPX-300 burners are supplied in 50 MMBtu/hr to 300 MMBtu/hr sizes that have wide turndown ratio of 1:5.

Figure 2. NOx Emissions for Various Coals
 
   

51 Shaffer Rd, Bridgewater, NJ 08807 Tel.: 908-419-3996,
Fax: 908-636-2244