HIGH TEMPERATURE SEQUESTRATION OF ELEMENTAL MERCURY BY NON-CARBON BASED SORBENTS
This work is concerned with chemi-sorption of elemental Hg at high temperatures (900 - 1100℃) on a sorbent that is mineral, rather than carbon based. This sorbent, MinPlus, consists of an intimate mixture of CaO, CaCO3, and Al2O3-2SiO2, and is manufactured in industrially quantities (tones) from residues from paper recycling processes. Use of this non-carbon based sorbent has special advantages in that it actually can enhance fly ash utilization for cement, rather than diminish it as, for example, activated carbon does. We have conducted experimental tests using an externally heated quartz tube reactor, with sorbent feeding rates from 1g/h to 6g/h. Preliminary results indicate that Hg removal efficiency is sensitive to sorbent feeding rates and to furnace temperature. The Hg removal percentage increased with both variables. Two mechanisms come into play: an in-flight mechanism and another mechanism of Hg sorption on sorbent deposits on the reactor wall. A maximum total (in flight plus reactor surface) Hg removal efficiency of 83-90％ was obtained at temperatures of 900-1100℃. There was negligible sorption at temperatures below 600℃. Results for the in-flight mechanism alone showed a maximum sorption efficiency at ～900℃, whereas that on the reactor surface increased continuously with temperature. This suggests that sorbent de-activation occurs in flight, which is in agreement with other fixed bed results obtained in this laboratory, but not necessarily on the substance formed on the reactor wall. Raw and spent sorbents were analyzed by XRD and SEM-EDS to identify the sorbent mineral transitions that seem to activate the process. The in-flight mechanisms appear to involve 1) activation of the sorbent, caused most probably by an internal solid-solid reaction, followed by 2) Hg sorption and 3) possible de-activation, if the temperatures are too high, too long. Reactor surface mechanisms still remain to be elucidated.
Mercury control Coal combustion and gasification Adsorbents
Sung Jun Lee Jost O.L.Wendt Joep Biermann
Dept.of Chemical Engineering, University of Utah, Salt Lake City, UT, USA MinPlus, BV., Arnhem, The Netherlands Dept.of Chemical Engineering, University of Utah, Salt Lake City, UT, USA,
国际会议
第六届煤燃烧国际会议(The 6th International Symposium on Coal Combustion)
武汉
英文
853-858
2007-12-01（万方平台首次上网日期，不代表论文的发表时间）