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Title: Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion

Abstract

The use of post-consumer carpet as a potential fuel substitute in cement kilns and other high-temperature processes is being considered to address the problem of huge volumes of carpet waste and the opportunity of waste-to-energy recovery. Carpet represents a high volume waste stream, provides high energy value, and contains other recoverable materials for the production of cement. This research studied the emission characteristics of burning 0.46-kg charges of chopped nylon carpet squares, pulverized coal, and particle-board pellets in a pilot-scale natural gas-fired rotary kiln. Carpet was tested with different amounts of water added. Emissions of oxygen, carbon dioxide, nitric oxide (NO), sulfur dioxide (SO{sub 2}), carbon monoxide (CO), and total hydrocarbons and temperatures were continuously monitored. It was found that carpet burned faster and more completely than coal and particle board, with a rapid volatile release that resulted in large and variable transient emission peaks. NO emissions from carpet combustion ranged from 0.06 to 0.15 g/MJ and were inversely related to CO emissions. Carpet combustion yielded higher NO emissions than coal and particleboard combustion, consistent with its higher nitrogen content. S{sub 2} emissions were highest for coal combustion, consistent with its higher sulfur content than carpet or particle board. Addingmore » water to carpet slowed its burn time and reduced variability in the emission transients, reducing the CO peak but increasing NO emissions. Results of this study indicate that carpet waste can be used as an effective alternative fuel, with the caveats that it might be necessary to wet carpet or chop it finely to avoid excessive transient puff emissions due to its high volatility compared with other solid fuels, and that controlled mixing of combustion air might be used to control NO emissions from nylon carpet. 13 refs., 5 figs., 1 tab.« less

Authors:
; ; ;  [1]
  1. Georgia Institute of Technology, Atlanta, GA (United States). School of Civil and Environmental Engineering
Publication Date:
OSTI Identifier:
21085011
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of the Air and Waste Management Association; Journal Volume: 58; Journal Issue: 8
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 54 ENVIRONMENTAL SCIENCES; COMBUSTION; EMISSION; COAL; COMPARATIVE EVALUATIONS; SOLID FUELS; PULVERIZED FUELS; KILNS; VOLATILE MATTER; NITRIC OXIDE; SULFUR DIOXIDE; NYLON; SOLID WASTES; WASTE PRODUCT UTILIZATION; CEMENTS; TEXTILES; FUEL SUBSTITUTION

Citation Formats

Stephanie Lucero Konopa, James A. Mulholland, Matthew J. Realff, and Paul M. Lemieux. Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion. United States: N. p., 2008. Web. doi:10.3155/1047-3289.58.8.1070.
Stephanie Lucero Konopa, James A. Mulholland, Matthew J. Realff, & Paul M. Lemieux. Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion. United States. doi:10.3155/1047-3289.58.8.1070.
Stephanie Lucero Konopa, James A. Mulholland, Matthew J. Realff, and Paul M. Lemieux. 2008. "Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion". United States. doi:10.3155/1047-3289.58.8.1070.
@article{osti_21085011,
title = {Emissions from carpet combustion in a pilot-scale rotary kiln: comparison with coal and particle-board combustion},
author = {Stephanie Lucero Konopa and James A. Mulholland and Matthew J. Realff and Paul M. Lemieux},
abstractNote = {The use of post-consumer carpet as a potential fuel substitute in cement kilns and other high-temperature processes is being considered to address the problem of huge volumes of carpet waste and the opportunity of waste-to-energy recovery. Carpet represents a high volume waste stream, provides high energy value, and contains other recoverable materials for the production of cement. This research studied the emission characteristics of burning 0.46-kg charges of chopped nylon carpet squares, pulverized coal, and particle-board pellets in a pilot-scale natural gas-fired rotary kiln. Carpet was tested with different amounts of water added. Emissions of oxygen, carbon dioxide, nitric oxide (NO), sulfur dioxide (SO{sub 2}), carbon monoxide (CO), and total hydrocarbons and temperatures were continuously monitored. It was found that carpet burned faster and more completely than coal and particle board, with a rapid volatile release that resulted in large and variable transient emission peaks. NO emissions from carpet combustion ranged from 0.06 to 0.15 g/MJ and were inversely related to CO emissions. Carpet combustion yielded higher NO emissions than coal and particleboard combustion, consistent with its higher nitrogen content. S{sub 2} emissions were highest for coal combustion, consistent with its higher sulfur content than carpet or particle board. Adding water to carpet slowed its burn time and reduced variability in the emission transients, reducing the CO peak but increasing NO emissions. Results of this study indicate that carpet waste can be used as an effective alternative fuel, with the caveats that it might be necessary to wet carpet or chop it finely to avoid excessive transient puff emissions due to its high volatility compared with other solid fuels, and that controlled mixing of combustion air might be used to control NO emissions from nylon carpet. 13 refs., 5 figs., 1 tab.},
doi = {10.3155/1047-3289.58.8.1070},
journal = {Journal of the Air and Waste Management Association},
number = 8,
volume = 58,
place = {United States},
year = 2008,
month = 8
}
  • A comparison is made, for the first time, between the evolution of hydrocarbons from clay sorbent beds in a field-scale rotary kiln incinerator and in a pilot-scale rotary kiln simulator. To relate the data from the different sized units, due allowance is made for bed dynamical similitude, bed geometrical factors, and bed heat-up. To minimize the effects of disturbances caused by foreign matter in the field-scale bed and differences in loading techniques, the rate of evolution is characterized by an evolution interval defined as the time required for the middle 80% of the ultimate contaminant evolution to occur. A comparisonmore » of evolution intervals with reciprocal bed temperature reveals that the data are consistent with an analysis that assumes a uniform bed temperature (at any instant of time) and a desorption-controlled evolution rate. Furthermore, the evolution intervals scale inversely with a modified Froude number, which characterizes bed dynamics. The success in comparing field and simulator results indicates that pilot-scale rotary kilns may be used to simulate certain features of industrial-scale units if dynamical, geometrical, and thermal parameters are matched appropriately.« less
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  • Bench- and pilot-scale experiments were conducted using potassium iodide (KI) for capture and removal of Hg in air and coal combustion exhaust. Two bench-scale reactor systems were used: (1) a packed-bed reactor (PBR) packed with granular or powder KI and (2) an aerosol flow reactor (AFR) with injection of KI particles. It was found that a higher temperature, a higher concentration of KI, and a longer gas residence time resulted in a higher Hg removal efficiency. A 100% Hg removal was achieved in the PBR above 300{sup o}C using 0.5 g of powder KI and in the AFR above 500{supmore » o}C with a KI/Hg molar ratio of 600 at a 5.8 s residence time. The low KI injection ratio relative to Hg indicated that KI is highly effective for Hg removal in air. Formation of I{sub 2} vapor by the oxidation of KI by O{sub 2} at high temperatures, which then reacts with Hg to produce HgI{sub 2}, was identified as the pathway for removal. The pilot-scale experiments were conducted in a 160 kW pulverized coal combustor. KI was introduced in two ways: as a powder mixed with coal and by spraying KI solution droplets into the flue gas. In both cases the Hg removal efficiency increased with an increase in the feed rate of KI. Mixing KI powder with coal was found to be more effective than spraying KI into the flue gas. The Hg removal by KI was less efficient in the pilot-scale tests than in the bench-scale tests probably due to certain flue gas components reacting with KI or I{sub 2}. Hg speciation measurements in both bench- and pilot-scale experiments indicated no oxidized mercury in the gas phase upon introduction of KI, indicating that the oxidation product HgI2 was captured in the particulate phase. This is very beneficial in coal-fired power plants equipped with electrostatic precipitators where particulate-bound Hg can be efficiently removed. 27 refs., 8 figs., 4 tabs.« less
  • In this paper, based on analysis of the chemical and physical processes of clinker formation, a heat flux function was introduced to take account of the thermal effect of clinker formation. Combining the models of gas-solid flow, heat and mass transfer, and pulverized coal combustion, a set of mathematical models for a full-scale cement rotary kiln were established. In terms of commercial CFD code (FLUENT), the distributions of gas velocity, gas temperature, and gas components in a cement rotary kiln were obtained by numerical simulation of a 3000 t/d rotary kiln with a four-channel burner. The predicted results indicated thatmore » the improved model accounts for the thermal enthalpy of the clinker formation process and can give more insight (such as fluid flow, temperature, etc,) from within the cement rotary kiln, which is a benefit to better understanding of combustion behavior and an improvement of burner and rotary kiln technology. 25 refs., 12 figs., 5 tabs.« less
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