Rapid Mix Burner™ [Patented] Case Study 104
Morningstar TODD
Ultra Low Emissions Burner Installation
The Situation
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Fig. 1
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In late November 1994, a TODD Combustion®
Dual Rapid Mix Burner (D-RMB) was retrofitted
into a 100,000 lb/hr Nebraska boiler at
the Morningstar Cannery in Los Banos, CA. The
D-RMB replaced a forced Flue Gas Recirculation
(FGR) burner permitted for 30 ppm NOx and 400
ppm CO. The TODD retrofit consisted of
replacing the existing burner and fan, while
most of the existing control system components
were reused. The objective of the project was to
demonstrate the ability of the D-RMB version of
the burner to operate at less than 9 ppm NOx
and CO across the load range. Since the
NOx emissions of the D-RMB are relatively
insensitive to the heat release rate of the
boiler, the burner was designed for an
increased capacity.
The Boiler
A natural gas only, 130 MMBtu/hr D-RMB
was installed on a Nebraska 100,000 lb/hr
watertube boiler equipped with an economizer.
The burner installation consisted of the
D-RMB and a forced-draft combustion air fan
sized for induced FGR. The existing cross-
limited metering control system and gas train
were both reused. The burner operates at an
8-in. draft loss and 5 psig gas pressure at full
load. Since the performance of the D-RMB is
relatively insensitive to the heat release rate of
the boiler, a 130 MMBtu/hr D-RMB was
used to replace the existing burner that had
a 118 MMBtu/hr capacity. The larger burner
increased the boiler capacity from 100,000
lb/hr to 110,000 lb/hr.
The TODD® Result
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| Fig. 2: Morningstar Data |
Fig. 2 illustrates the test results achieved
with the boiler in automatic operation. The
FGR rate varied from 28% in the lower half of
the load range to 23% at full load. NOx
emissions varied between 8 ppm and 9 ppm.
Over the load range, the CO was less than 1
ppm. Excess O2 levels ranged from 4% at
minimum load to 3% at full load. The burner
turndown was 6:1 and the flame length was
less than 10 feet over the load range.
Third Party Source Test
On December 14, 1994, the boiler was
source-tested by Best Environmental. The
results are shown below. The CO and NOx
numbers are corrected to 3% O2.
Source Test Data
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| Load % |
O2% |
CO ppm |
NOx ppm |
|
| 25 |
3.4 |
<1 |
8.1 |
|
| 50 |
3.4 |
<1 |
8.2 |
|
| 100 |
3.2 |
<1 |
8.3 |
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