Continuous Sorbent Reactions in a High-Temperature Fabric Filter Following Convective Pass Ca(OH)2 Injection for SO2 Removal.
A specially designed two-stage reactor was used to study solid sorbent reactions in the filtration stage of a high-temperature fabric which follow convective pass Ca(OH)2 injection. Solid conversions during the progress of the sorbent reactions were thoroughly analyzed. It was found that, unlike the sorbent reactions in the injection stage, which proceed extremely fast with strong carbonation under high temperatures, the subsequent sorbent reactions in the filtration stage are much slower and residual sorbent is mainly utilized in removing sulfur dioxide (SO2). Two major reaction pathways are discovered in the filtration stage. The first route is through the decomposition of residual calcium hydroxide (Ca(OH)2), which is critical in inducing further sorbent reactions when there is sufficient residual sorbent. The second route is the sulfation of the carbonation product, calcium carbonate (CaCO3), which may become the principal reaction to remove SO2 after the residual sorbent is consumed. The con-vective pass and the fabric filter are found to be equally important reaction sites in the combined process of convec-tive pass sorbent injection with high-temperature filtration. The overall SO2 removal efficiency of the system is affected by both the sorbent injection and filtration conditions.
Kinetic Evaluation of Lime for Medium-Temperature Desulfurization in Oxy-Fuel Conditions by Dry Sorbent Injection
With increasing emphasis on the control of greenhouse gases, power plants may move towards oxy-fuel technologies rather than air-fired plants. This move leads to a change in the feed to the desulfurization unit, which also needs to be adapted along with the power plant. Most existing plants already have functioning desulfurization units, which need to be retrofitted for the new conditions. In the present study, three different limes have been examined as sorbents for sulfur capture in oxy-fuel conditions with varying residence times at medium temperature (150–450 ∘ C). Parameters indicative of the kinetics and competition between SO 2 and CO 2 , like SO 2 breakthrough time, total lime conversion, yield for sulfur capture and sulfur selectivity have been evaluated. The results of this study lead to the recommendation that medium temperature desulfurization should be used for moderate SO 2 capture, in combination with already existing sulfur capture systems. The effects of CO 2 and water vapor have also been analyzed. In addition, the performance of the unit irrespective of temperature strongly depends on the lime type. In addition, absence of water vapor strongly favored the desulfurization process when there was high concentration of CO 2 .
Dating of Historical Manuscripts Using Spectrometric Methods: A Mini-Review
An overview is provided of spectrometric methods useful for age estimation of historical manuscripts (medieval ones in particular), in order to confirm their authenticity. Individual methods (infrared and Raman spectroscopy, mass spectrometry, atomic emission spectroscopy, X-ray spectroscopy, and electron scanning microscopy) are discussed and examples of their application described. The following general strategy can be recommended for dating and/or authenticating of historical manuscripts. First of all, the pigment analysis should be carried out using Raman spectroscopy (distinguishing the period and modern pigments), followed by PIXE ink analysis (solving the question of ink homogeneity). Finally, the radiocarbon dating of the writing support, potentially supplemented by the ink dating using scanning Auger microscopy should be performed.