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Case Studies: Fullerton College

With expansion underway at Fullerton College, located in Fullerton, California, the need for increased capacity and compliance with California emissions requirements dictated that its boiler room facility be upgraded. Before the upgrade, Fullerton had two firetube, water-back boilers each rated at 8 million Btu/hr. They opted to replace the old units with a pair of Johnston firetube boilers that incorporate the GTI-developed forced internal recirculation burner technology.

Traditionally, external flue gas recirculation (FGR) approaches have dominated the 15 to 30-vppm NOx retrofit market. Ultra-low NOx emissions (below 9 vppm) have been achieved with very high FGR levels, but, in most cases, FGR requirements compromised efficiency and performance and led to higher capital and operating costs.

An alternative, the forced internal recirculation burner (FIR), utilizes the distribution of a premixed or partially premixed flame around a metallic insert or "recirculation sleeve" that induces recirculation of combustion products back to the root of the flame. FIR technology combines the use of premixed combustion and internal FGR to reduce the bulk and peak flame temperatures. The lower flame temperatures reduce the formation of thermal NOx compounds. The recirculation sleeve controls the flue gas recirculation and anchors the flame over all firing conditions. The recirculating sleeve also radiates to the cold furnace wall or a process heater wall, increasing heat transfer and helps to reduce the peak flame temperature. The result: NOx emissions are drastically reduced without costly efficiency penalties.

Installation of the packaged boilers at Fullerton College occurred in stages to allow for continued usage of steam and hot water. Removal of existing boiler No. 2 and final testing of the new boiler took less than a month. Following final testing, the new boiler with its FIR burner system went into continuous operation and operated for a ten-day period without incident. The success of the No. 2 boiler upgrade gave Fullerton the confidence to proceed with the changeover of Boiler No. 1.

Both of the packaged boilers installed at Fullerton College surpassed the performance goals established for NOx emissions and combustion efficiency. For this application, Fullerton required less than 12 vppm NOx
with greater than 85% combustion efficiency. Baseline emissions with Fullerton's previous firetube boilers
ranged from 78 vppm at low fire to 86 vppm at high fire. NOx emissions from the FIR-equipped boilers were
below 10 vppm from low to high fire, and CO emissions were consistently below 15 vppm through the entire firing range. This represents an average 88% reduction in NOx emissions compared to baseline data.

The FIR burners combined with the Johnston four-pass boilers were also more efficient than the existing boiler package. At the lower firing ranges, the FIR burners could run at lower excess oxygen levels, and this enhanced efficiency. In fact, the FIR burners could operate at the same excess oxygen through the entire firing range. Combustion was stable and quiet and set-up of the FIR burner was easier than a burner equipped with external FGR.

The new packaged boilers/burners passed the test at Fullerton College, offering superior performance, improved efficiency and significant reduction of NOx emissions.

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