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Title: Advanced combustion system for industrial boilers. Phase 2, Quarterly technical progress report, January--March 1990

Abstract

During Phase I of the project, a coal injector was designed, fabricated, and tested. It is a direct replacement for the oil gun in the original equipment of a 200 hp CleaverBmoks fire-tube boiler. The system was tested at coal-firing rates in the range of 2 to 6 million Btu`s per hour, firing Upper Elkhorn No. 3 (eastern bituminous, ``UE3``) coal supplied by Energy International, Incorporated. For these tests, propane was used to preheat the boiler before initiation of coal firing. The propane flow was turned off after coal combustion was established. No combustion air preheat was used. During these tests, boiler efficiency was typically about 85 to 86 percent, while carbon conversion efficiency was approximately 94 percent. Concentrations of CO were less than 150 ppm. The NO{sub x} emissions were less than 0.6 pounds per million Btu`s. Following a series of laser-illuminated cold-flow-visualization tests, a new burner was also designed, fabricated, and tested during Phase 1. The arrangement is shown in Figure 1.2. It is a two-stage, swirl burner which fits in the space previously occupied by the original Cleaver-Brooks burner, and uses the existing section of refractory. Air flow can be regulated independently into each of the twomore » stages. Additionally, the angle is adjustable for individual swirl blades. Upper Elkhorn No. 3 ultra fine coal was used as the standard fuel for most UTSI-burner tests. Firing rates were in the range of 2 to 6 million Btu`s per hour. Upper Elkhorn No. 3 coals were tested with three levels of ash. These were approximately 1.4%, 2.7%, and 4.8% ash, on an as-fired basis. The 2.7%-ash UE3 coal was used for most tests because it exhibited a good balance between ash content and ash-fusion characteristics.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Tennessee Univ., Tullahoma, TN (United States). Space Inst.
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10121441
Report Number(s):
DOE/PC/79653-T10
ON: DE94006413; BR: AA3520100
DOE Contract Number:
AC22-87PC79653
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: [1990]
Country of Publication:
United States
Language:
English
Subject:
20 FOSSIL-FUELED POWER PLANTS; 01 COAL, LIGNITE, AND PEAT; FOSSIL-FUEL POWER PLANTS; BURNERS; DESIGN; BOILERS; FABRICATION; PERFORMANCE TESTING; EFFICIENCY; COAL; COMBUSTION; ASH CONTENT; ASHES; MELTING; PROGRESS REPORT; 200104; 014000; COMPONENTS

Citation Formats

Wagoner, C.L., Foote, J.P., Millard, W.P., Attig, R.C., and Schulz, R.J.. Advanced combustion system for industrial boilers. Phase 2, Quarterly technical progress report, January--March 1990. United States: N. p., 1990. Web. doi:10.2172/10121441.
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Wagoner, C.L., Foote, J.P., Millard, W.P., Attig, R.C., & Schulz, R.J.. Advanced combustion system for industrial boilers. Phase 2, Quarterly technical progress report, January--March 1990. United States. doi:10.2172/10121441.
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Wagoner, C.L., Foote, J.P., Millard, W.P., Attig, R.C., and Schulz, R.J.. Mon . "Advanced combustion system for industrial boilers. Phase 2, Quarterly technical progress report, January--March 1990". United States. doi:10.2172/10121441. https://www.osti.gov/servlets/purl/10121441.
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@article{osti_10121441,
title = {Advanced combustion system for industrial boilers. Phase 2, Quarterly technical progress report, January--March 1990},
author = {Wagoner, C.L. and Foote, J.P. and Millard, W.P. and Attig, R.C. and Schulz, R.J.},
abstractNote = {During Phase I of the project, a coal injector was designed, fabricated, and tested. It is a direct replacement for the oil gun in the original equipment of a 200 hp CleaverBmoks fire-tube boiler. The system was tested at coal-firing rates in the range of 2 to 6 million Btu`s per hour, firing Upper Elkhorn No. 3 (eastern bituminous, ``UE3``) coal supplied by Energy International, Incorporated. For these tests, propane was used to preheat the boiler before initiation of coal firing. The propane flow was turned off after coal combustion was established. No combustion air preheat was used. During these tests, boiler efficiency was typically about 85 to 86 percent, while carbon conversion efficiency was approximately 94 percent. Concentrations of CO were less than 150 ppm. The NO{sub x} emissions were less than 0.6 pounds per million Btu`s. Following a series of laser-illuminated cold-flow-visualization tests, a new burner was also designed, fabricated, and tested during Phase 1. The arrangement is shown in Figure 1.2. It is a two-stage, swirl burner which fits in the space previously occupied by the original Cleaver-Brooks burner, and uses the existing section of refractory. Air flow can be regulated independently into each of the two stages. Additionally, the angle is adjustable for individual swirl blades. Upper Elkhorn No. 3 ultra fine coal was used as the standard fuel for most UTSI-burner tests. Firing rates were in the range of 2 to 6 million Btu`s per hour. Upper Elkhorn No. 3 coals were tested with three levels of ash. These were approximately 1.4%, 2.7%, and 4.8% ash, on an as-fired basis. The 2.7%-ash UE3 coal was used for most tests because it exhibited a good balance between ash content and ash-fusion characteristics.},
doi = {10.2172/10121441},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Dec 31 00:00:00 EST 1990},
month = {Mon Dec 31 00:00:00 EST 1990}
}
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Technical Report:
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DOI:  10.2172/10121441
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  • ; ; ; ...
    Work in Phase II has concentrated on: (a) adapting a commercially available automotive oxygen sensor for use in the boiler control system; ( b.) developing a commercially oriented dense-phase coal transport system; (c.) designing, fabricating, testing, and fine tuning an improved burner for better combustion efficiency; and (d) adding deep-air-staging capabilities to the new burner to decrease NO{sub x} emissions to slightly above 0.4 lb-NO{sub x}/MBtu with ultra fine coal. This performance is considerably better than the DOE goal for Phase 11 work. Reburning tests were conducted using ultra fine coal and propane in the external, water-cooled 15-foot long testmore » duct. When propane supplied approximately 14% of the heat input, NO{sub x} levels were as low as 0.295 lb-NO{sub x}/MBtu. Initial testing of the UTSI boiler control and automation system was successful.« less

  • ; ; ; ...
    This During this quarter, work continued on development/improvement of the low-NO{sub x} coal combustor for the boiler system. Reburning tests were conducted in the external, water-cooled test duct with a length of 15 feet using ultra fine coal with propane to reduce the NO{sub x} levels to as low as 0.295 lb-NO{sub x}/MBtu. Work also continued on design/construction of the new coal-feed system that will be used for the 100-hour demonstration test with the on-line refillable coal hopper operating in air at atmospheric pressure. Coal will be loaded into the hopper from bulk bags. Initial testing of the UTSI boilermore » control and automation system was successful. Normally-pulverized coal with approximately 70% passing a number 200 sieve was burned in the external test duct. Initial flame-visualization tests were successful, and the burner was able to handle coal without being micronized to the ultra fine level. Refractory was poured for a new combustor second-stage assembly. Subsequently, the combustor was installed inside the 200 hp fire-tube boiler.« less

  • ; ; ; ...
    Initial work in Phase II concentrated on: (a) adapting a commercially available automotive oxygen sensor for use in the boiler control system; (b) developing a more commercially oriented dense-phase coal transport system; (c) designing, fabricating and testing an improved burner for better combustion efficiency; and (d) adding deep-air-staging capabilities to the new burner to decrease NO{sub x} emissions.

  • ; ; ; ...
    (1) A ZrO{sub 2} oxygen sensor was calibrated successfully over the concentration range from 0 to 21 percent O{sub 2} at temperatures from ambient to 400{degrees}F. This inexpensive automotive sensor provides 8 signal which will be used to monitor and automatically control combustion conditions to maintain consistently high combustion efficiency combined with low NO{sub x} emissions; (2) An improved burner was designed and fabricated with an initial ``stage`` which functions as a coal-eductor/coal-air mixer. Now coal can be transported in dense phase to the burner without pressurizing the coal-storage hopper which had approximately a four-hour capacity. This permits refilling themore » hopper during periods of continuous operation of the boiler as required for commercial use; (3) The improved burner produced the highest boiler efficiency to date. Carbon burnout improved to 98.9 Percent, compared to about 97 percent during Phase I testing for the same Upper Elkhorn No. 3 coal with 2.7% ash. We expect to exceed 99% Combustion efficiency with all of the test coals during more optimized future testing; and (4) Although the new burner proved to be very efficient, emissions of NO{sub x} were higher than those observed during Phase I testing. The new-burner design was modified. Capability for deep air-staging was added to the new burner to promote low-NO{sub x} operation.« less

  • ; ; ; ...
    During this quarter, several coal combustion tests were carded out in the boiler using the eductor coal feed system and the two-stage combustor. The coal feed system and combustor are shown in Figures 2.1 and 2.2. The main goal for these tests was to determine the optimum combustor setup for low NO{sub x} emissions while maintaining good carbon conversion efficiency. It was found during the tests that the amount of air introduced into the combustor along with the coal through the eductor tailpipe was a critical parameter for both NO{sub x} formation and carbon conversion. Using the new fluidized coalmore » hopper discharge arrangement, the air required for eductor operation varies from about 12 percent of the total combustion air at a 2 MBtu/h firing rate to about 8 percent at 4 and 6 MBtu/h. (During previous testing using the old coal tank, the eductor air requirement was about 12 percent at 4 MBtu/h.) In initial tests, only the amount of air needed for eductor operation was introduced through the tailpipe. Combustor operation under this condition was satisfactory at 2 MBtu/h but not at 4 or 6 MBtu/h. At 4 and 6 MBtu/h firing rates, carbon conversion was typically less than 98 percent (based on ash exiting the stack), and CO was relatively high. It was necessary to operate the combustor at a primary stoichiometry of 0.40 or less in order to meet the goal of 0.6 lb/MBtu for NO{sub x} emission.« less