GEO was clearly receptive to this approach and various options were then discussed, namely, 1) the purchase and installation of a remanufactured boiler, as was initially requested; 2) providing a new parallel positioning linkage-less burner with the remanufactured boiler; and 3) to furnish and install a new York-Shipley Global (YSG) high-pressure steam boiler with a Limpsfield natural gas-fired low NOx burner. As Ware illustrated, the benefits of Option 3 comprising an increase in boiler capacity, operating efficiency and reduced payback analysis, exceeded GEO’s expectations. The decision was therefore made to move forward with this solution.

Ware suggested that the existing 500 bhp four-pass water-backed unit serve as the redundant unit, in lieu of GEO’s initial thought of installing a remanufactured unit for this purpose. Secondly, after careful analysis of GEO’s processes and load characteristics, it was decided that a YSG Series 500L, 800 bhp — three-pass water-backed — 150 psig steam boiler be furnished, to serve as the primary boiler, fitted with a Limpsfield Series LC forced draft pre-mix natural gas-fired low-NOx burner.

Ware recognized the ability of the YSG Series 500L to withstand and compensate for the large sudden swing loads that GEO’s processes commonly experience. The liberal steam disengaging area of the YSG Series 500L serves to minimize steam velocity increase caused by the rapid or sudden loss of system pressure caused by process load demands and therefore alleviates nuisance low water conditions and moisture entrainment in the steam supply.

Additionally, Ware understood the performance characteristics of the Limpsfield Series LC burner as being necessary to ensure GEO’s expectations. The unique pre-mix design feature distributes air at the burner diffuser to ensure combustion is maximized throughout the entire firing range while maintaining stable flame geometry throughout and accommodating safe, reliable, repeatable and efficient operation.

The Limpsfield Series LC operates at 3% O2 when firing natural gas, while producing negligible CO, and therefore maximizes combustion efficiency. Without reducing combustion efficiency, Limpsfield also maintains sub-30 ppm NOx emissions, reducing emissions per LBS/106 MMBtu input by as much as 70% of an uncontrolled emission rate, due to its unique technology. An Autoflame electronic parallel positioning control system was also utilized, ensuring repeatability and therefore sustained efficient and safe operating conditions. Adding to the client’s concern for future fuel flexibility, the Limpsfield system includes the capability to fire alternative gaseous and/or fuel oils, and under applicable control guidelines is capable of simultaneous firing two fuels.

To complement the proposed solution, Ware employees are fully trained and certified to Limpsfield manufacturing standards for field implementation and installation. As the prime contractor for this effort, this added value was instrumental in GEO’s decision to move forward with the Ware solution. 

After a short time in service, GEO’s operation immediately started meeting the expectations that had been created. Namely, these were reduced operating costs, efficiency gain, and emissions reductions. Additionally, the advent of the larger-capacity YSG boiler afforded uninterrupted service, which ensured the client an efficient and competitive manufacturing environment.

The results of the installation are shown in Tables 1 and 2. During the two-month metered test period, the existing 500 bhp unit operated at an average load of 39.5% firing rate, or 6,811 pph — the YSG 800 bhp unit had operated at an average load of 33.7% firing rate or 9,312 pph — providing sub 30 ppm NOx emissions rate.

Average fuel to steam efficiency achieved by the existing 500 bhp unit was 78% — the YSG 800 bhp unit was 89% — representing an 11% increase over the existing 500 bhp system, representing a total 14.1% operational improvement.

Commonly accepted beliefs that were demonstrated as being unsupported:

• Low-NOx burner provides lower operational efficiency, compared to standard equipment. As tested, this is simply not the case.

• Operating at a higher firing rate is more efficient than at a lower firing rate. As tested, similar or greater efficiencies can be obtained.

• Four passes are more efficient than three passes. Again, as tested, similar or greater efficiencies can be obtained.

Although the solution which GEO opted for was the more complex and expensive proposition, yet the most encompassing, as the tables indicate, the performance of the newly installed YSG/Limpsfield equipment yielded a payback which would not have been possible had the original intent of a redundant back-up system been employed.

Ware’s unique perspective, its approach of listening to, and understanding, the need of its client, and proposing solutions which best fit their immediate needs and future considerations, have provided an opportunity for continued operational efficiencies and overall cost savings for years to come.  TB