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- Titre : 50958.pdf
- Submitted by : Anonymous
- Description : for Ash Formation based upon the understanding developed in (a) and (b). When completed, this model will predict the particle size and chemical composition distributions of ash formed during the combustion of pulverized coal under a broad range of conditions.
Transcription
FUNDAMENTAL STUDY OF ASH FORMATION AND DEPOSITION:
EFFECT OF REDUCING STOICHIOMETRY
Editor:
Dr. J.J. Helble
PSI Technologies
.. .
Quarterly Report No. 7
for the Period 1 October to 31 December 1994
Prof. T.W. Peterson and Mr. Dennis Gallien
University of Arizona
and
Prof. A.F. Sarofim and Mr. Taofang Zeng
Massachusetts Institute of Technology
DATE PUBLISHED – February 1995
Prepared under
DOE Contract No. DE-AC22-93PC92 190
U S . DEPARTMENT OF ENERGY
Pittsburgh Energy Technology Center
P.O. Box 10940
Pittsburgh, PA 15236
20 New England Business Center I Andover, MA 01 81 0-1 077 I U.S.A.
P H Y S I C A L S C I E N C E S
I N C .
DISTRlBUTlON OF TWS DOCUMENT IS UNLIMiT@$ U
I
TABLE OF CONTENTS
Section
2.
3.
4.
EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 – 1
OVERVIEW OF PROGRAM TASKS . . . . . . . . . . . . . . . . . . . ; . . . . . . . . . . . . . . . . 2- 1
PULVERIZED COAL COMBUSTION STUDIES IN A CONTINUOUS
SELF-CONTAINED LABORATORY REACTOR . . . . . . . . . . . . . . . . . . . . . . . . . .
3- I
FUNDAMENTAL COMBUSTION STUDIES UNDER REDUCING
CONDITIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1
Transport Properties of Reacting Gases . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4. I
4-3
Estimation of Reaction Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-4
4.2
Estimation of Chemical Kinetics for Char Combustion . . . . . . . . . . . . . . . . . . 4-5
4.3
Prediction of Combustion Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-7
4.4
DISCLAIMER
This report was prepared as an account of work sponsored by an agency of the United States
Government. Neither the United States Government nor any agency thereof, nor any of their
employees, makes any warranty, express or implied, or assumes any legal liability or responsi-
bility for the accuracy, completeness, or usefulness of any information, apparatus, product, or
process disclosed, or represents that its use would not infringe privately owned rights. Refer-
ence herein to any specific commercial product, process, or service by trade name, trademark,
manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recom-
mendation, or favoring by the United States Government or any agency thereof. The views
and opinions of authors expressed herein do not necessarily state or reflect those of the
United States Government or any agency thereof.
…
111
LIST OF ILLUSTRATIONS
Figure
Pag;e
2-1
Program Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2-5
3- 1
Old feed system design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-3
3-2
Schematic of coal removal problem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-3
3-3
New entraining gas setup for the feed system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4-1 …. mass …………. time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3-4
4-8
4-2 Oxygen ……………………………………………………….
CO. ………………. surface …………. diameter . . . . . . . . . . . . . . . . . . . 4-9
CO …………………………………
diameter ………………..
4-9
4-8
4-3
4-4
iv
DISCLAIMER
Portions of this document may be illegible
in electronic image products. images are
produced from the best avaiiabie original
document.
SECTION 1
EXECUTIVE SUMMARY
1- 1/1-2
1. EXECUTIVE SUMMARY
The technical objectives of this project are:
a.
b.
C.
To identify the partitioning of inorganic coal constituents among vapor, submicron
fume, and fly ash products generated during the combustion of pulverized coal
under a variety of combustion conditions. Fuel lean and fuel rich combustion
conditions will be considered.
To identify and quantify the fundamental processes by which the transformations
of minerals and organically-associated inorganic species occur. Emphasis will be
placed on identifying any changes that occur as a result of combustion under sub-
stoichiometric combustion conditions.
To incorporate the effects of combustion stoichiometry into an Engineering Model
for Ash Formation based upon the understanding developed in (a) and (b). When
completed, this model will predict the particle size and chemical composition
distributions of ash formed during the combustion of pulverized coal under a broad
range of conditions.
A description of the work plan for accomplishing these objectives is presented in Section 2 of this
report.
The work discussed in this report highlights the accomplishments of the seventh quarter of
this two year project. This includes University of Arizona efforts to minimize periodicity in the
coal feeder for the drop tube furnace, and MIT efforts to calculate the concentrations of CO,
CO,, and 0, surrounding a burning char particle.
In Section 3, the use of a pulsed gas flow to maintain a smooth coal feed to the drop tube
furnace is discussed. Addition of pulsing action, driven by a peristaltic pump, has eliminated the
coal feeder pluggage problems that had been occurring.
In Section 4, the development of a single particle char combustion model by MIT is
discussed. The model is then used for calculating oxygen, CO, and CO, concentrations on the
char particle surface as a function of char particle diameter. This information can then be used to
interpret results of ash formation experiments conducted as a function of particle size and
combustion stoichiometric ratio.
1-3