Situation

United Airlines, located at the San Francisco airport, has a cogeneration facility with a 50 MW gas turbine, heat recovery steam generator, and two auxiliary packaged boilers. In order to meet the new Bay Area Air Quality Management District (BAAQMD) emission requirements of 30 ppm NOx on the auxiliary boilers, United decided to upgrade one of its boilers with Coen's new Quantum Low NOx "QLN" burners a full two years ahead of the January 1, 1996 compliance deadline.

Solution

One of the benefits of the new "QLN" burner is that it did not require flue gas recirculation (FGR), so the added  expense of a larger fan and motor for FGR with the associated operating horsepower cost and thermal stack losses were avoided, along with the installation and maintenance of a FGR system. Since the boiler is an auxiliary backup to a gas turbine, a special permit was required to fire with the turbine. Once the local air quality regulators realized the potential NOx reduction, they not only helped in our request for a permit, they bent over backyards to see that it was granted.

Results

The startup  achieved the BAAQMD limits of 30 ppm NOx within two days of firing. No FGR was required and United Airlines met the local regulations a full two years ahead of the compliance deadline.

The conversion resulted in :

• LOW NOx - At all loads, the BAAQMD permitted limit of 30 ppm was met without the use of FGR.
• LOW CO - Again at all loads, the permitted limit was achieved.
• LOW COST - With no FGR fan and motor, United Airlines saved on installation, operating cost, and reduced stack losses.
• TURNDOWN - The permitted levels of NOx and CO were met even at a boiler steam flow turndown of 10:1.
• EFFICIENCY : The new QLN burner reduced excess air by 50%.

Situation

Agrium US, Inc., located in Borger, Texas, employs several   25,000 PPH boilers at its ammonia production facility. The boiler in question was originally installed in 1968, and is cycled for start-ups to meet process requirements. After years of "up and down" duty, it developed substantial leaks and numerous refractory problems, requiring ongoing repairs.

Solution

The boiler has deteriorated to the point that repairs were no longer feasible. A complete new boiler was being considered, until the ABCO alternative was presented and selected.

ABCO custom - engineered a gas-tight, fully-welded boiler, employing the drums from the previous boiler. This new boiler featured virtually no refractory and full membrane construction.

Results

The new ABCO boiler enjoys significant advantages for Operations personnel as well as corporate management :

• No leaks - Leakage problems have been eliminated
• Reliable operation - Although it is still used in a rigorous cycling application, operators report no difficulties
• No refractory problems - With virtually all refractory removed, maintenance is greatly simplified.