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Title: ON LINE MEASUREMENT OF PRIMARY FINE PARTICULATE MATTER

Abstract

The measurement of fine particulate in pulverized coal flames has several applications of importance. These include but are not limited to: (1) The detection of fine particulate in the effluent for pollution control; (2) The detection of soot and fuel burnout in real time within a boiler; and (3) The quantification of soot within coal flame for improved understanding of pulverized coal flame heat transfer and soot modeling. A method has been investigated using two-color extinction along a line of sight within the flame which provides a continuous real-time measurement of the soot concentration. The method uses two inexpensive HeNe lasers and simple light detectors. The results of testing the method on a pilot scale 0.2 MW pulverized coal reactor demonstrate the method is working well in a qualitative sense and an error analysis performed on the uncertainty of the assumed values demonstrates the method to be accurate to within {+-} 30%. Additional experiments designed to quantify the measurement more accurately are ongoing. Measurements at the end of the reactor just prior to the exit showed soot could not be detected until the overall equivalence ratio became greater than 1.0. The detection limit for the method was estimated to bemore » 1 x 10{sup -8} soot volume fraction. Peak soot concentration was found to approach a level of 0.88 x 10{sup -6} at the sootiest condition. The method was used to obtain an axial profile of soot concentration aligned with the down-fired pulverized coal flame for three different flame swirls of 0, 0.5 and 1.5 and an overall equivalence ratio of 1.2. The axial measurements showed the soot concentration to increase initially and level off to a constant maximum value. At 0.5 swirl the soot volume fraction increased more rapidly near the burner and both the 0.5 and 1.5 swirl cases showed that soot had reached a maximum by 0.9 m, but the 0 swirl soot concentration was still increasing. Previous measurements of species and velocity in the reactor suggest that the flame is lifted at zero swirl allowing O{sub 2} to be entrained and that the flame protrudes further down the reactor explaining the lower soot values measured. An evaluation of the potential for using this measurement technique on full scale boilers suggests that attenuation of the signal across a larger boiler distance is the largest obstacle. The beam would be expected to become completely attenuated under moderate sooting conditions; however, the longer pathlength would improve the ability of the method to measure very small amounts of soot escaping the main combustion zone.« less

Authors:
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
787727
Report Number(s):
FG26-98FT40116-01
TRN: AH200135%%72
DOE Contract Number:  
FG26-98FT40116
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 1 Sep 1999
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; BOILERS; BURNERS; BURNOUT; COAL; COMBUSTION; DETECTION; HEAT TRANSFER; LASERS; PARTICULATES; POLLUTION CONTROL; TESTING; VELOCITY

Citation Formats

Tree, Dale R. ON LINE MEASUREMENT OF PRIMARY FINE PARTICULATE MATTER. United States: N. p., 1999. Web. doi:10.2172/787727.
Tree, Dale R. ON LINE MEASUREMENT OF PRIMARY FINE PARTICULATE MATTER. United States. doi:10.2172/787727.
Tree, Dale R. Wed . "ON LINE MEASUREMENT OF PRIMARY FINE PARTICULATE MATTER". United States. doi:10.2172/787727. https://www.osti.gov/servlets/purl/787727.
@article{osti_787727,
title = {ON LINE MEASUREMENT OF PRIMARY FINE PARTICULATE MATTER},
author = {Tree, Dale R},
abstractNote = {The measurement of fine particulate in pulverized coal flames has several applications of importance. These include but are not limited to: (1) The detection of fine particulate in the effluent for pollution control; (2) The detection of soot and fuel burnout in real time within a boiler; and (3) The quantification of soot within coal flame for improved understanding of pulverized coal flame heat transfer and soot modeling. A method has been investigated using two-color extinction along a line of sight within the flame which provides a continuous real-time measurement of the soot concentration. The method uses two inexpensive HeNe lasers and simple light detectors. The results of testing the method on a pilot scale 0.2 MW pulverized coal reactor demonstrate the method is working well in a qualitative sense and an error analysis performed on the uncertainty of the assumed values demonstrates the method to be accurate to within {+-} 30%. Additional experiments designed to quantify the measurement more accurately are ongoing. Measurements at the end of the reactor just prior to the exit showed soot could not be detected until the overall equivalence ratio became greater than 1.0. The detection limit for the method was estimated to be 1 x 10{sup -8} soot volume fraction. Peak soot concentration was found to approach a level of 0.88 x 10{sup -6} at the sootiest condition. The method was used to obtain an axial profile of soot concentration aligned with the down-fired pulverized coal flame for three different flame swirls of 0, 0.5 and 1.5 and an overall equivalence ratio of 1.2. The axial measurements showed the soot concentration to increase initially and level off to a constant maximum value. At 0.5 swirl the soot volume fraction increased more rapidly near the burner and both the 0.5 and 1.5 swirl cases showed that soot had reached a maximum by 0.9 m, but the 0 swirl soot concentration was still increasing. Previous measurements of species and velocity in the reactor suggest that the flame is lifted at zero swirl allowing O{sub 2} to be entrained and that the flame protrudes further down the reactor explaining the lower soot values measured. An evaluation of the potential for using this measurement technique on full scale boilers suggests that attenuation of the signal across a larger boiler distance is the largest obstacle. The beam would be expected to become completely attenuated under moderate sooting conditions; however, the longer pathlength would improve the ability of the method to measure very small amounts of soot escaping the main combustion zone.},
doi = {10.2172/787727},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {9}
}