Page 317 - Materials Chemistry, Second Edition

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288 Waste Management Practices: Municipal, Hazardous, and Industrial
EXCEL EXERCISE

ANALYSIS OF RDF BEFORE AND AFTER COMBUSTION
FILE NAME: RDF.XLS

Background
Data are provided from actual field-test burns of densified RDF. An MRF had recently begun oper-
ations and was producing d-RDF with the expectation of selling it to local markets. The tests out-
lined below were conducted in order to satisfy concerns of the state regulatory agency as to any
potential hazards with gaseous emissions or ash.
The data for this exercise can be located at www.crcpress.com/e_products/downloads/
download.asp?cat_no=3525
Some of the analyses and experiments were as follows:

● Ultimate analysis of fuel as received (three RDF and two local coal samples)
● Varying mixtures of coal and d-RDF were combusted in a coal-fired boiler. Steam pro-
duction, ash generation, and acid gas production were documented.
● A field-scale experiment was conducted in which pellets were manufactured containing
fixed ratios of paper and assorted plastics. These pellets were combusted in a coal-fired
boiler and gaseous emissions were monitored.

Tasks
1. Determine the relationship between percentage of plastic in the RDF pellets and acid gas
production. Graph the data for SO ,NO , and HCl. What is the trend for HCl with
2 x
increased ash? How could this trend occur?
2. Graph the concentrations of SO ,NO , and HCl for the coal and RDF mixtures. What
2 x
trends do you discern? On a separate page, graph steam production with percentage of
coal/RDF. Also graph ash generation with percentage of coal/RDF. Discuss the trends, if
any.
3. Analyze the TCLP data for the RDF ash. Compare the values generated with TCLP lim-
its. Based on the TCLP limits in the table, are any of the ash samples considered “haz-
ardous waste”?
4. Calculate the mean and standard deviations of the ultimate analysis data for the three
RDF samples. How precise are the data? Within one standard deviation or greater? What
does this tell us about the sampling and analysis procedures, and about the inherent
chemical variability of a natural material such as southern Indiana coal?
5. The data provided are from actual pilot tests conducted at a facility considering the use
of RDF alone or coal and RDF mixtures for steam production. The RDF supplier placed
a bid of $29/ton of RDF. The coal was $33/ton. Based on steam production data, SO
2
data, and increased ash handling requirements, under what percentage of coal/RDF ratio
would the facility accrue maximum savings?