Measurement of Furnace Exit-Gas Temperature
The continued rise of worldwide electricity consumption has put an ever increasing demand on power generation facilities. With coal-fired power plants, this demand results in challenges to increase production efficiency while minimizing environmental impact.
One of the primary parameters for monitoring the performance of a power boiler is the furnace exit-gas temperature (FEGT). This measurement provides a direct indication of the heat transfer to the furnace water walls at a particular load condition, and sets expectations for performance of the superheat and re-heat processes.
If the FEGT is too high, residual fly ash will fuse to the pendants and tubes forming slag, reducing the heat exchange efficiency to the tube walls. This can lead to increased soot blowing operations, tube corrosion, reduced load operation, and possible safety issues.
A low FEGT value may indicate excessive radiative losses to the water walls or an incomplete combustion process resulting in lost efficiency. Fuel quality, excess air, burner selection and tilt, low NOx operation, and heat transfer issues all affect the exit gas temperature. By monitoring the FEGT, operators can balance and optimize their combustion process and safeguard the boiler furnace.
LumaSense Technologies has brought over 50 years of industrial infrared temperature and gas measurement experience to the development of a new system solution specifically designed to more effectively monitor the exit gas temperature (FEGT) in boiler furnaces.
- Fig. Spectrum of CO2 emission
The LumaSense solution utilizes our IMPAC Pyrometer IPE 140/45 with a custom narrowband filter (near 4.5 μm) to monitor the CO2 emission line from the hot combustion gases.
Typical fossil fuel combustion processes contains approximately 10% CO2. The radiative emissions from these molecules can be accurately measured to obtain the temperature of the hot gas, while not being affected by furnace wall or tube conditions. By adjusting the pyrometer depth of focus, we can obtain an effective profile of approximately one half of the total furnace width and obtain the average temperature for the furnace exit gas region.
- Minimize unwanted slag accumulation and fouling by controlling FEGT below the ash fusion point.
- Optimize and Tune heat transfer by monitoring FEGT under varying process conditions. Measure and quantify trade-offs of heat rate and NOx & SO2 emissions.
- Set alarm triggers to determine precisely when to take corrective actions and initiate soot-blowing operations. Minimize soot blowing operations to increase pendant lifetime.
- Maximize boiler efficiency by running under optimal load conditions. Prevent failures by continuously and proactively monitoring the furnace temperature.
- Minimize unscheduled outages and reduced power conditions. Easily installed and maintained while boiler is online.