Dynaswirl-LN™ Case Study 112
Pittsburg Power Station Units No. 5 and No. 6
The Situation
The Environmental Protection Agency (EPA)
continues to lower the allowable NOx emission
rates through stringent regulations. These regula-tions
are being met by several advanced methods
in California.
One unit in particular at the Mirant (formerly Southern Energy
California) plant in Pittsburg, CA, required a
new low NOx burner system to help comply with
the clean air requirements. The daily average
emission rate of the existing utility boiler needed to be reduced to less than 36 ppm.
The Boiler
The Pittsburg Station Units No. 5 and No. 6
are each 326 MWe power boilers capable of
delivering 2,150 kpph steam at 2,475 psig and
1,050°F. Each unit has two firing walls with two
rows of six burners on each wall. There is a row of
six Over Fire Air (OFA) ports - one above each
burner column on each firing wall. The burners
and OFA ports are all in one common windbox.
Flue Gas Recirculation (FGR) is supplied to the
air stream via sparger sections. Table 1 shows the
boiler data.
 |
Unit No. 5 and 6 |
|
|
|
| No. Burners |
24 |
|
|
| No. Over Fire Ports |
12 |
|
|
| Boiler/Turbine Output, MW (gross) |
326 |
|
|
| Steam Flow @ MCR, kpph |
2,150 |
|
|
| Nominal Combustion Air Temp., °F |
575 |
|
|
 |
| Fig. 1: |
Pittsburg Power Station, Dynaswirl-LN burner installation in Unit 6. |
The TODD® Solution
In 1999, COOLflow technology was used to
prepare for the supply of 24 TODD Dynaswirl-LN
burners that used the existing FGR system and
OFA ports. It was not necessary to increase
the capacity of the FGR system or to modify
the OFA ports. The TODD Dynaswirl-LN is a
low NOx gas/oil burner for multi-burner and
utility boilers.
A COOLflow physical model of Units 5 and
6 was created of the combustion air, FGR and
OFA systems to help correct airflow problems, to
maximize the FGR mixing device performance,
and to help ensure the proper OFA penetration
into the rising furnace gases was obtained.
The Dynaswirl-LN burners for Unit No. 6
were installed in May 2000, while the burners for
Unit No. 5 are scheduled for installation in
February 2001.
The TODD Result
 |
| Fig. 2: |
Twenty-four Dynaswirl-LN burners, ready for shipment. |
The TODD Dynaswirl-LN burners reduced
NOx emissions by over 40%. The excess O2 and CO levels
were lowered to 0.88% O2 and 133 ppm CO, which
benefited efficient boiler operation. Finally, the
Dynaswirl-LN retrofit improved the boiler turn-down
and operating flexibility.
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