Tuning Your Boiler for Fuel Savings – Out with the Old in with the New Technology
The USA has about 811,000 MW of installed generation and over 52% of our
Electric power is produced by aging coal fired power plants. The average utility boiler
furnace was designed about 30-40 years ago. According to DOE records, the average
boiler in 1974 was fired with 80% bituminous coal. Now, western PRB coal is much
more prevalent and represents about 50% of total coal consumption. Most companies
switched fuels 30 year ago and have optimized the coal properties for improved performance. Yet, nearly all coal fired plant are working through the new challenges of low NOx burners, SCR/ SNCR installation and the continuing challenge of mercury controls.
The installation of new control equipment have created their own new problems associated with the efficient daily operations. Many of these old coal fired boilers still have numerous efficiency loss such as air in-leakage, air heater leakage, combustion airflow issues. Typically, there are more than 500 Btu’s / kWhr in optimization or efficiency improvements. The heat rates have increased from 8210 BTU’s/kWhr in the early 1960’s to 9500 BTU’s/kWhr for todays units.
The typical boiler optimization should include the 12 steps as outlined below:
1. Fuel line minimum velocity shall be 3,300 fpm.
2. Mechanical tolerances of burners and dampers shall be within 1/4” or better.
3. Furnace exit must be oxidizing preferably, 3%.
4. Fuel lines balanced in fuel flow to be +/- 10% or better.
5. Primary air flow shall be accurately measured and controlled to +/- 3%
6. Fuel fineness shall be 75% or more passing a 200 mesh screen and 50 mesh coal Shall be less than .1%.
7. Fuel lines balanced to each burner by +/- 2% or better.
8. Fuel lines balanced to dirty air test by +/- 5% or better.
9. Secondary air distribution to burner should be within 5% to 10%.
So, what are the benefits of conducting a through boiler tuning program ? List below Is fairly good list of benefits.
1. Improved plant capacity
2. Improved heat rate
3. NOx Optimization
4. Increased load capacity
5. Less Air heater fouling
6. Less stack opacity
7. less Popcorn ash to the SCR
8. Reduced slagging
9. Better flyash quality
10. Lower generation cost
11. Longer superheater and reheater tube metals life.
12. Increased reliability
13. Fuel Savings
14. Increased load capacity
Now, what if I told you that you could get the same saving and additional benefits With a more cost effective approach?