Comparison of Heating Losses and Macro Thermogravimetric Analysis Procedures for Estimating Unburned Carbon in Combustion Residues
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- 作者：Stuart C. Burris ; Dong Li ; and John T. Riley
- 刊名：Energy & Fuels
- 出版年：2005
- 出版时间：July 2005
- 年：2005
- 卷：19
- 期：4
- 页码：1493 - 1502
- 全文大小：178K
- 年卷期：v.19,no.4(July 2005)
- ISSN：1520-5029
文摘
One of the most important indices for evaluating the combustion efficiencies of boilers, as wellas the commercial value of the produced fly ash, is the unburned carbon in fly ash. The mostcommon method currently used by combustion engineers to estimate the amount of unburnedcarbon in fly ash is to equate it to the dry loss on ignition (LOI) value. There seems to be noreported systematic study linking LOI values with the true carbon content of ashes andcombustion residues. In this study, the LOI values for 35 combustion residues were determinedat 500, 750, and 950 
tities/deg.gif">C, using a macro thermogravimetric analyzer. The carbon contents of thecombustion residues and the residues from the LOI determinations were then measured. Forthe samples in this study, it was determined that temperatures of >790 tities/deg.gif">C should be used toachieve complete carbon burnoff. For low-percentage-carbon combustion residues, there is verypoor agreement between the unburned carbon contents and the LOI values. This is especiallytrue if the samples are exposed to the atmosphere for extended periods of time, because thecombustion residues readily absorb moisture and acidic gases. For high-percentage-carboncombustion residues, there is good agreement between the unburned carbon and the LOI values,especially if the residues are relatively fresh.
tities/deg.gif">C, using a macro thermogravimetric analyzer. The carbon contents of thecombustion residues and the residues from the LOI determinations were then measured. Forthe samples in this study, it was determined that temperatures of >790 tities/deg.gif">C should be used toachieve complete carbon burnoff. For low-percentage-carbon combustion residues, there is verypoor agreement between the unburned carbon contents and the LOI values. This is especiallytrue if the samples are exposed to the atmosphere for extended periods of time, because thecombustion residues readily absorb moisture and acidic gases. For high-percentage-carboncombustion residues, there is good agreement between the unburned carbon and the LOI values,especially if the residues are relatively fresh.