Furnace Exit Gas Temperature (FEGT) Monitoring

IMPROVED BOILER PERFORMANCE AND OPTIMIZATION WITH THE INFRA-VIEW® BOILER THERMOMETER

by FIRESIDE PARAMETER MONITORING AND CONTROL - Furnace Exit Gas Temperature (FEGT) Monitoring 

 

 

 

 

In a typical fossil power plant, there is lack of furnace flue gas (where combustion takes place)  temperature monitoring.

There is a simple logic to converting from a two point control, burner and boiler exit temperature, to a three point control; i.e., burner, furnace exit gas temperature (FEGT), then boiler exit temperature. This extra control point, FEGT, can have a major impact on boiler performance and reliability.

 

Basically, the furnace exit point separates the radiation zone from the convection pass. As such, FEGT control is a critical parameter which can be used to preserve the boiler operation and performance including, emission, reliability, and safety.

 

If FEGT deviates from the design value the following undesired condition can occur:

  •  Increased slagging/ fouling of water walls, superheater, and economizer, and air heaters
  •  Increased corrosion rates of superheater and reheater tubes
  •  Potential of convective pass tube overheating
  •  (creep damage), requiring more steam attemperation
  •  Altered design conditions which are more difficult to correct by the operator
  •  Increased flue gas temperature in the boiler exit which
  •  increases heat loss and lowers efficiency
  •  FEGT provides an operational safeguard and indictor for the boiler operation. 

 

Current Situation - in-effective measurement 

 

Modeling. For many years the utility industry has been actively involved in developing more accurate instrumentation, analysis methods, and performance improvement techniques for the fire side parameters control. 

 

Traditional T/C probes or mechanical moving T/C probes:  A furnace startup probe is sometimes used to protect the superheater and reheater tubes prior to the establishment of steam flow. Unfortunately, the T/C weld tends to giveway after expose on high temperature operation and also the mechanical moving T/C probe need high maintenace. 

 

SOLUTIONS: 

 

Direct infrared temperature measurement of the exit gas temperature gives the accurate, and reliable, hassle free measurement, over any other techniques such as thermocouple, acoustical detection, or thermal modeling. 

 

ADVANTAGES:

  • High Accurate 
  • No moving part or physical contact with the hot gas.
  • Low Mainteance 

 

 

BENEFITS:

 

Infra-View® can optimize your boiler by monitoring flue gas temperatures for: Startup, Sootblower and Slag Control; Low NOx; Fire Ball Centering; FEGT Monitoring.