Combustion emissions from conventional boiler firing coal and tire derived fuel

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Virginia Tech

This study was conducted at the Virginia Tech Power Plant to measure and compare stack emissions while firing coal alone and coal mixed with shredded tires. The coal-tire mixtures consisted of 10 and 20 percent tire chips.

Modified EPA method 5 sampling train was used to determine particulate emissions. CO emissions were determined with an ENERAC 2000 gas analyzer. Supelco XAD-2 resin was used in the modified method 5 sampling train to adsorb nonpolar, vapor phase hydrocarbons. The XAD-2 resin was extracted and the wash concentrated before High Performance Liquid Chromatography (HPLC) was used to quantify the presence of benzene, chrysene, phenol, and benzo(a)pyrene.

Particulate emissions resulting from the combustion of 0, 10 and 20 percent tire mixtures with coal were 0.88, 2.32, and 2.13 lb/10⁶ Btu, respectively. For carbon monoxide, the emissions were 0.17,0.22, and 0.33 1b/10⁶ BTU for 0, 10, and 20 percent tire mixtures, respectively. Large variations in polynuclear aromatic hydrocarbon (PAH) emissions were observed. Therefore, only trends in the PAH data can be discussed. Phenol emissions appeared to increase with the addition of shredded tires to the combustion process. Benzene and benzo(a)pyrene emissions appeared to decrease with the addition of shredded tires to the combustion process. An increase in chrysene emissions for 20% addition of shredded tires was observed. A larger data base is needed in order to develop stronger conclusions regarding PAH emissions resulting from coal/tire shred combustion in a conventional spreader stroker.