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Title	Performance of Natural Gas Cofiring on a Coal-Fired Spreader Stoker at Dover Light & Power
Creator	Mason, H. B.; Borland, David G.; Chan, Isaac ; Kinney, Ward L.; Backlund, Jon
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1995
Spatial Coverage	presented at Monterey, California
Abstract	Gas cofiring is an efficient way to enhance performance and treat operational problems with coal-fired stoker boilers. Firing from 5 to 30 percent of total heat input through side-wall gas burners offers a spectrum of benefits including faster and cleaner warmup and light-off, reduced opacity, recovered derate, coal flexibility, and improved turndown and load following. In this project, the 165,000 Ib/hr Babcock & Wilcox spreader stoker boiler at Dover Light & Power was retrofit with dual Coen gas-fired burners rated at 37 MMBtu/hr each. The burners were positioned on opposite sidewalls 6 feet above the grate and offset 8 feet. A high pressure drop burner design with a small throat opening was used to increase penetration into the combustion gases and minimize pressure part modifications. The gas burners in the staggered configuration promote better mixing and heat distribution and reduce the load per unit area on the grate. The unit has been operated since August 4 1995, cofiring gas a majority of the time. Test results with cofiring show recovery of lost capacity derate and significant improvement in efficiency, emissions and operability. Firing from 10 to 15 percent of total heat input from gas increased boiler efficiency 2 to 3 percent due to improved carbon utilization and reduced excess air. Carbon in fly ash was reduced by 35 to 40 percent by cofiring. Excess oxygen was a function of coal quality and was reduced up to 2 to 3 percent with gas cofiring. Particulate emissions at the electrostatic precipitator inlet were reduced by an average of 24 percent with 10 percent gas cofire.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6vq3589
Setname	uu_afrc
ID	9341
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6vq3589

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Title	Page 23
Format	application/pdf
OCR Text	Show 680 I/) C!' • ; 0 • w • COAL < 660 X COFIRE • •• • X • • XXX • • ~X EconolNf LET. 640 .... \ X XX • X • X • X<X~X 620 • X Xx X 600 110 120 130 140 150 160 STEAM LOAD Lb/hr Figure 14. Economizer inlet temperatures and cofiring for a variety of run conditions over a 2-month period. An average temperature reduction of 15 to 20°F with cofiring was experienced with cofiring. The composite effect of the reduced stack losses and improved carbon utilization gave a boiler efficiency increase of 2 to 3 percent depending on conditions. This result was also seen from the overall plant heat rate results which averaged a 3-percent improvement over the initial month of cofiring. Particulate loading. The particulate loading upstream of the ESP was sampled with an EPA Method 17 traverse. The average baseline grain loading was 0.90 gr / dscf and the cofiring loading at 12 percent cofiring was 0.68 gr / dscf. This gives an average particulate emission reduction of 24 percent. This level of reduction is consistent with the reduction in carbon in ash seen in the LOI analyses. Cofiring Economics. Figure 15 summarizes the composite cofiring economic credits and debits based on the testing results. The dominant credit was derate recovery which accrues both from avoided demand charges and avoided cost of purchase power, particularly at peak load periods. This benefit alone is sufficient to compensate for the differential fuel 22
Setname	uu_afrc
ID	9338
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6vq3589/9338