Homogeneous and Heterogeneous Reaction and Transformation of Hg and Trace Metals in Combustion Systems

J. Helble ; Clara Smith ; David Miller

关键词: ARSENIC;    CALCIUM;    CHEMISTRY;    COAL;    COMBUSTION;    FLY ASH;    HEMATITE;    IRON OXIDES;    MERCURY;    OXIDATION;    PARTICLE SIZE;    SIMULATION;    TRANSFORMATIONS;   

DOI  :  10.2172/1004877
RP-ID  :  None
PID  :  OSTI ID: 1004877
Others  :  TRN: US201105%%114

美国|英语

来源: SciTech Connect

【 摘 要 】

The overall goal of this project was to produce a working dynamic model to predict the transformation and partitioning of trace metals resulting from combustion of a broad range of fuels. The information provided from this model will be instrumental in efforts to identify fuels and conditions that can be varied to reduce metal emissions. Through the course of this project, it was determined that mercury (Hg) and arsenic (As) would be the focus of the experimental investigation. Experiments were therefore conducted to examine homogeneous and heterogeneous mercury oxidation pathways, and to assess potential interactions between arsenic and calcium. As described in this report, results indicated that the role of SO{sub 2} on Hg oxidation was complex and depended upon overall gas phase chemistry, that iron oxide (hematite) particles contributed directly to heterogeneous Hg oxidation, and that As-Ca interactions occurred through both gas-solid and within-char reaction pathways. Modeling based on this study indicated that, depending upon coal type and fly ash particle size, vaporization-condensation, vaporization-surface reaction, and As-CaO in-char reaction all play a role in arsenic transformations under combustion conditions.