The development of more efficient clean up techniques in coal power plants is essential in order to reduce trace metals emissions into the atmosphere. However, understanding of the behavior of the trace metals during the gasification process is necessary for the optimization of the hot gas cleaning systems. Thereby, in this work the influence of H 2 O, HCl, and H 2 S on the release and condensation behavior of Cd was experimentally investigated. The experiments were conducted in two different setups. The condensation behavior (temperature and speciation) of the trace metal vapors was investigated in a heated flow channel reactor housed in a furnace with a gas cooling zone. Experiments on the release of the inorganic vapors were carried out in a heated flow channel reactor coupled to a molecular beam mass spectrometer (MBMS) in order to analyze the gas in situ. The results of the experimental investigations were compared with Scheil−Gulliver cooling calculations performed by FactSage 6.3. Furthermore, thermodynamic pseudoequilibrium calculations were carried out to help in understanding the condensation mechanisms of the trace metal cadmium and the global kinetics in the experiments. The experimental results showed that the main chemical species detected in the condensation and release experiments were Cd, CdO, CdCl 2 , and CdS. In general, the speciation as well as the temperatures at which the species condensed and were present in the gas phase in the release experiments had the same trend in the calculations and in the experimental results. Thus, the Scheil−Gulliver cooling model was proved to be an excellent tool for the prediction of the release and condensation of cadmium. With this work, a better comprehension of the behavior of cadmium under gasification conditions was obtained.
The aim of this work was to assess the influence of H 2 O, HCl, and H 2 S on the condensation and release of zinc. The condensation behavior of the zinc vapors was investigated in a heated flow channel reactor housed in a furnace with a gas cooling zone, where eight glass filters were placed on different cooling stages. The metal species deposited in the filters were determined by means of ion chromatography (IC) and inductively coupled plasma optical emission spectroscopy (ICP-OES). Experiments on the release of the inorganic vapors were carried out in a heated flow channel reactor coupled to a molecular beam mass spectrometer (MBMS). The experiments were carried out under two typical gasification conditions (H 2 /H 2 O/He or Ar) and atmospheric pressure with 50 and 500 ppm v of HCl and H 2 S. Hot gas analysis was done at 900, 800, 700, and 500 °C. The condensation experiments showed that zinc condensed as ZnO, ZnCl 2 , and ZnS under the conditions considered. The species detected in the gas phase were Zn, ZnO, ZnCl 2 , and ZnS. The experimental results were compared with Scheil−Gulliver cooling calculations carried out with FactSage 6.3 software. This model was proven to be an excellent tool for the prediction of the behavior of zinc under gasification conditions. Furthermore, the global kinetics of the condensation experiments was clarified with the thermodynamic pseudoequilibrium model recently developed by researchers of Chubu University (Japan). With this work, not only a good understanding of the behavior of the zinc under gasification conditions was obtained, but also the finding and evidence of a powerful tool for predicting fast and easily the behavior of trace metals under gasification conditions.
An investigation of the chemical form, the concentration, and distribution of lead species between the gas and condensed phase was carried out under gasification-like conditions. The influence of hydrogen sulfide, hydrogen chloride, and steam on the speciation of lead was studied. The gaseous species were determined online by molecular-beam-mass-spectrometry. The condensates were analyzed by standard methods. The dominant chemical forms were metallic Pb, PbCl2, and PbS. The experimental data were compared with the results of thermodynamic Scheil–Gulliver cooling calculations. Further, the experimental data was used as an input for a pseudoequilibrium model aiming at the determination of kinetic information on the underlying transformations.
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