Current burners for ethylene cracking furnaces are generally designed for 10 percent excess air operation. According to e-Missions, a newsletter from Tulsa-based John Zink Co. LLC, controlling tramp air leakage by sealing the firebox and closing dampers of burners that are out of service is important. Additionally, controlling heat losses to conduction by having adequate furnace insulation are also paramount in energy efficient operation.

The company offers several tips on how to inspect burners for efficient operation while the heater is online.

• Visually inspect the heat patterns on the wall.
  
• Look for tramp air sources around tube seals, sight doors and mounting locations.
  
• Visually inspect the flames; they should be uniform and free from soot.
  
• Monitor the fuel composition to ensure the supply temperature is at a safe margin above the dew point to avoid liquid carryover and tip plugging.
  
• Monitor the burner supply pressure, temperature, flow and composition; increases in pressure are an indication of tip plugging.
  
• Monitor burner inlets for restrictions.
  
• Inspect tile for pitting, cracking, glassing and an increase in tile porosity.

Among the tips offered for offline inspection of burners are:

• When the heater is offline and entrance is allowed into the furnace, there are some additional inspections that can be performed.
  
• Inspect tile for pitting, cracking, glassing and an increase in tile porosity.
  
• Examine refractory for improper insulation coverage.
  
• Inspect and clean fuel-gas headers during scheduled turnarounds.
  
• Look for tip plugging/coking while the heater is offline.
  
• Check all burner dampers for proper operation; replace any that do not operate through the complete range of motion.
  
• If possible, smoke test the furnace under positive pressure during scheduled maintenance to identify any sources of tramp air leakage.

Links

• John Zink LLC