Evaluation of Gas
Reburning and LowNOx
Burners on a
Wall-Fired Boiler
Project Description
This project was selected during Round
III of DOE’s CCT Program. In October
1990 Energy and Environmental Research
Corporation (EER) signed an agreement with
DOE to conduct this project. Gas reburning
coupled with low-NOx burners (GR-LNB)
was tested at Public Service Company of
Colorado’s (PSCo) 158-MWe (net) wallfired
Cherokee Unit 3 near Denver, Colorado.
PSCo served as co-funder and host.
EER and Foster Wheeler Energy Corporation
were the technology suppliers, and
testing was conducted by EER. Additional
team members and co-funders were the
Gas Research Institute (GRI), Colorado
Interstate Gas Company, and EPRI. DOE
provided 50% of the total project cost of
$17.8 million.
The existing 16 burners on Unit 3 were
replaced by Foster Wheeler Controlled Flow/
Split Flame LNBs. These burners employ
dual combustion-air registers, allowing control
of air distribution at the burner and providing
independent control of the ignition
zone and flame shape. The gas reburning
system retrofit involved routing natural gas
to 16 boiler penetrations (eight on the front
wall and eight on the rear wall), installing a
flue gas recirculation fan, installing a multiclone
dust collector to remove particulates
and protect the fan, and connecting the
equipment with the ductwork. The OFA
system involved installing an OFA fan and
ductwork from the secondary air system to
six front-wall injection nozzles. The control
system was also modified.
During the first test series, it was found
that FGR had little effect on NOx reduction.
Therefore, part way through the demonstration,
the FGR system was removed. At the
same time, the natural gas injectors were
replaced by high-velocity injectors, which
made greater use of the available natural gas
pressure. Also, the OFA ports were modified
to provide higher jet momentum, air
swirl capability, and velocity control. This
provided improved lateral coverage and turbulence
in mixing with unburned fuel. After
these modifications, the system was referred
to as Second Generation GR-LNB