CaO interaction in the staged combustion of coal. Ninth quarterly technical progress report, October 1, 1982-December 31, 1982

Technical Report · Mon Jan 31 04:00:00 EST 1983

OSTI ID:6608846

Levy, A; Merryman, E L

Lime (CaO) and limestone (CaCO/sub 3/) have been shown to be effective agents in capturing sulfur in-situ. Present limitations in the effective use of these materials to capture sulfur appears to be in the temperature-time-excess oxygen regime in which these treated coals are burned. In oxygen-rich environments, high temperatures, as normally encountered in coal combustion, and long residence times are detrimental to the capture process. A possible way to circumvent this problem, while still using calcium as the capturing agent, may be to burn the coals under staged combustion. In staged combustion, one fires first under reducing (fuel rich) conditions prior to oxidation in the second stage. Our studies wherein coals were treated with CaO, i.e., impregnated with CaO for pulverized coal firing, or mixed and pelletized with CaO for stoker firing, suggest that conditions prevail under which CaO is first converted to CaS prior to being oxidized to CaSO/sub 4/. Since CaS has greater thermal stability than CaSO/sub 4/ in the absence of O/sub 2/, it is possible to fire at temperatures above 1200 C (2190 F) and retain sulfur under proper stoichiometric conditions. Work continued on the methane-coal (MC) combustion studies. The three coal firings were carried out at higher fuel/air equivalence ratios in an effort to enhance the formation of sulfides. It does not appear that the CO/sub 2/ is causing significant destruction of any CaS that may have been formed in the system, although other compounds such as H/sub 2/S may be effected. Analysis of solid samples by X-ray fluorescence indicate sulfides are present in the ashes and may actually be the dominant form of sulfur present in the samples. This is in contradiction to the wet analysis of ash which report no sulfides.

• Research Organization: Battelle Columbus Labs., OH (USA)
• DOE Contract Number: AC22-80PC30301
• OSTI ID: 6608846
• Report Number(s): DOE/PC/30301-9; ON: DE83006630
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
014000* -- Coal
Lignite
& Peat-- Combustion
ADDITIVES
ALKALINE EARTH METAL COMPOUNDS
ASHES
CALCIUM COMPOUNDS
CALCIUM OXIDES
CALCIUM SULFATES
CALCIUM SULFIDES
CARBONACEOUS MATERIALS
CARBONATE ROCKS
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COAL
COMBUSTION
DATA
ELEMENTS
ENERGY SOURCES
EXPERIMENTAL DATA
FOSSIL FUELS
FUEL ADDITIVES
FUEL-AIR RATIO
FUELS
INFORMATION
LIMESTONE
MATERIALS
NONDESTRUCTIVE ANALYSIS
NONMETALS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN COMPOUNDS
RESIDUES
RETENTION
ROCKS
SEDIMENTARY ROCKS
STABILITY
SULFATES
SULFIDES
SULFUR
SULFUR COMPOUNDS
THERMOCHEMICAL PROCESSES
X-RAY EMISSION ANALYSIS
X-RAY FLUORESCENCE ANALYSIS