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Title: Coal desulfurization in a rotary kiln combustor

Abstract

The purpose of this project was to demonstrate the combustion of coal and coal wastes in a rotary kiln reactor with limestone addition for sulfur control. The rationale for the project was the perception that rotary systems could bring several advantages to combustion of these fuels, and may thus offer an alternative to fluid-bed boilers. Towards this end, an existing wood pyrolysis kiln (the Humphrey Charcoal kiln) was to be suitably refurbished and retrofitted with a specially designed version of a patented air distributor provided by Universal Energy, Inc. (UEI). As the project progressed beyond the initial stages, a number of issues were raised regarding the feasibility and the possible advantages of burning coals in a rotary kiln combustor and, in particular, the suitability of the Humphrey Charcoal kiln as a combustor. Instead, an opportunity arose to conduct combustion tests in the PEDCO Rotary Cascading-Bed Boiler (RCBB) commercial demonstration unit at the North American Rayon CO. (NARCO) in Elizabethton, TN. The tests focused on anthracite culm and had two objectives: (a) determine the feasibility of burning anthracite culms in a rotary kiln boiler and (b) obtain input for any further work involving the Humphrey Charcoal kiln combustor. A number ofmore » tests were conducted at the PEDCO unit. The last one was conducted on anthracite culm procured directly from the feed bin of a commercial circulating fluid-bed boiler. The results were disappointing; it was difficult to maintain sustained combustion even when large quantities of supplemental fuel were used. Combustion efficiency was poor, around 60 percent. The results suggest that the rotary kiln boiler, as designed, is ill-suited with respect to low-grade, hard to burn solid fuels, such as anthracite culm. Indeed, data from combustion of bituminous coal in the PEDCO unit suggest that with respect to coal in general, the rotary kiln boiler appears inferior to the circulating fluid bed boiler.« less

Authors:
Publication Date:
Research Org.:
BCR National Lab., Pittsburgh, PA (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6986558
Report Number(s):
DOE/PC/90169-T7; BCRNL-L-1665
ON: DE93005086
DOE Contract Number:
FG22-90PC90169
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; BITUMINOUS COAL; COCOMBUSTION; COMBUSTORS; PERFORMANCE; CULM; AIR POLLUTION CONTROL; ANTHRACITE; EXPERIMENTAL DATA; KILNS; LIMESTONE; PROGRESS REPORT; SULFUR OXIDES; BLACK COAL; CARBONACEOUS MATERIALS; CARBONATE ROCKS; CHALCOGENIDES; CHEMICAL REACTIONS; COAL; COMBUSTION; CONTROL; DATA; DOCUMENT TYPES; ENERGY SOURCES; FOSSIL FUELS; FUELS; INFORMATION; MATERIALS; MINERAL WASTES; NUMERICAL DATA; OXIDATION; OXIDES; OXYGEN COMPOUNDS; POLLUTION CONTROL; ROCKS; SEDIMENTARY ROCKS; SOLID WASTES; SULFUR COMPOUNDS; THERMOCHEMICAL PROCESSES; WASTES; 014000* - Coal, Lignite, & Peat- Combustion

Citation Formats

Cobb, J.T. Jr. Coal desulfurization in a rotary kiln combustor. United States: N. p., 1992. Web. doi:10.2172/6986558.
Cobb, J.T. Jr. Coal desulfurization in a rotary kiln combustor. United States. doi:10.2172/6986558.
Cobb, J.T. Jr. 1992. "Coal desulfurization in a rotary kiln combustor". United States. doi:10.2172/6986558. https://www.osti.gov/servlets/purl/6986558.
@article{osti_6986558,
title = {Coal desulfurization in a rotary kiln combustor},
author = {Cobb, J.T. Jr.},
abstractNote = {The purpose of this project was to demonstrate the combustion of coal and coal wastes in a rotary kiln reactor with limestone addition for sulfur control. The rationale for the project was the perception that rotary systems could bring several advantages to combustion of these fuels, and may thus offer an alternative to fluid-bed boilers. Towards this end, an existing wood pyrolysis kiln (the Humphrey Charcoal kiln) was to be suitably refurbished and retrofitted with a specially designed version of a patented air distributor provided by Universal Energy, Inc. (UEI). As the project progressed beyond the initial stages, a number of issues were raised regarding the feasibility and the possible advantages of burning coals in a rotary kiln combustor and, in particular, the suitability of the Humphrey Charcoal kiln as a combustor. Instead, an opportunity arose to conduct combustion tests in the PEDCO Rotary Cascading-Bed Boiler (RCBB) commercial demonstration unit at the North American Rayon CO. (NARCO) in Elizabethton, TN. The tests focused on anthracite culm and had two objectives: (a) determine the feasibility of burning anthracite culms in a rotary kiln boiler and (b) obtain input for any further work involving the Humphrey Charcoal kiln combustor. A number of tests were conducted at the PEDCO unit. The last one was conducted on anthracite culm procured directly from the feed bin of a commercial circulating fluid-bed boiler. The results were disappointing; it was difficult to maintain sustained combustion even when large quantities of supplemental fuel were used. Combustion efficiency was poor, around 60 percent. The results suggest that the rotary kiln boiler, as designed, is ill-suited with respect to low-grade, hard to burn solid fuels, such as anthracite culm. Indeed, data from combustion of bituminous coal in the PEDCO unit suggest that with respect to coal in general, the rotary kiln boiler appears inferior to the circulating fluid bed boiler.},
doi = {10.2172/6986558},
journal = {},
number = ,
volume = ,
place = {United States},
year = 1992,
month = 9
}

Technical Report:

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  • The focus of our work during the first quarter of 1991 was on combustion tests at the PEDCO rotary kiln reactor at North American Rayon (NARCO) plant in Elizabethton, TN. The tests had essentially tow related objectives: (a) to obtain basic data on the combustion of anthracite culm in a rotary kiln reactor, and (b) upon the test results, determine how best to proceed with our own planned program at the Humphrey Charcoal kiln in Brookville, PA. The rationale for the tests at PEDCO arose from process analysis which posted red flags on the feasibility of burning low-grade, hard-to-burn fuelsmore » like anthracite culms, in the rotary kiln. The PEDCO unit afforded a unique opportunity to obtain some quick answers at low cost. Two different anthracite culm fuels were tested: a so-called Jeddo culm with an average heating value of 7000 Btu/lb, and a relatively poorer culm, and Emerald'' culm, with an average heating value of 5000 Btu/lb. An attempt was also made to burn a blend of the Emerald culm with bituminous coal in 75/25 percent proportions. This report describes the tests, their chronology, and preliminary results. As it turned out, the PEDCO unit is not configured properly for the combustion of anthracite culm. As a result, it proved difficult to achieve a sustained period of steady-state combustion operation, and combustion efficiencies were low even when supplemental fuel was used to aid combustion of the culm. 1 fig., 2 tabs.« less
  • Studies on coal combustion in a rotary kiln combustor continued. During the months of October, November and December, 1990, five major areas have received attention from the project team. They are: equipment evaluations and actions; environmental issues; process analysis and design; rotary reactor comparison and test; and trips and presentations.
  • Several issues that could have an impact on the capability to burn anthracite culm in a rotary bed boiler were identified; specifically, questions were raised concerning the specifications of the anthracite culm itself and some relating to the equipment. The anthracite culm delivered was wet, (with more than 10 percent moisture), and coarser than feed material for fluidized boilers. It was felt that using finer fuel, ensuring that it is largely dry, would aid the combustion of anthracite culm. It also appeared that if provisions were made for more efficient internal and external recycle of ash, this would also enhancemore » the combustion of this fuel. Accordingly, the decision was made to conduct an additional campaign of tests that would incorporate these changes. The tests, conducted on July 15 and 16, 1991, involved an anthracite culm that was, in fact, obtained from a fluidized bed a heating value of 3,000 Btu/lb and came with a top size of 1/4-inch. Despite these changes, sustained combustion could not be achieved without the use of large quantities of supplemental fuel. Based on these tests, we tend to conclude that the rotary kiln is ill suited for the combustion of hard-to-burn, low-grade solid fuels like anthracite culm.« less
  • During the months of July, August, and September 1990, six major areas have received attention from the project team. They are: background discussions, process analysis, equipment evaluations and actions, environmental issues, presentations, and future planning.
  • BCR National Laboratory (BCRNL) has initiated a project aimed at evaluating the technical and economic feasibility of using a rotary kiln, suitably modified, to burn Pennsylvania anthracite wastes, co-fired with high-sulfur bituminous coal. Limestone will be injected into the kiln for sulfur control, to determine whether high sulfur capture levels can be achieved with high sorbent utilization. The principal objectives of this work are: (1) to prove the feasibility of burning anthracite refuse, with co-firing of high-sulfur bituminous coal and with limestone injection for sulfur emissions control, in a rotary kiln fitted with a Universal Energy International (UEI) air injectormore » system; (2) to determine the emissions levels of SO{sub x} and NO{sub x} and specifically to identify the Ca/S ratios that are required to meet New Source Performance Standards; (3) to evaluate the technical and economic merits of a commercial rotary kiln combustor in comparison to fluidized bed combustors; and, (4) to ascertain the need for further work, including additional combustion tests, prior to commercial application, and to recommend accordingly a detailed program towards this end.« less