Application of Optimization Methods to Solid Phase Analysis of Combustion Gases Desulphurization Products
Abstract The variations in calcium and sulphur concentrations measured along cross-sections of limestone-lime sulphated particles in scanning electron microscope (EDS microanalysis) and the computation of the sum of oxides CaO+SO 3 , ( s ) and the molar ratio CaO/SO 3 , ( r ) are essential to identifying the compounds which could appear. A method of estimating the phase of sulphation limestone/lime products is presented in this paper. The aim of this method is to find such component proportions which minimize the differences between the measured and the calculated values of s and r . The method is developed using the software package CAMOS and enables one to calculate automatically the component proportions for the given system. In the paper the CaS–CaSO 4 –CaO–CaCO 3 and CaS–CaSO 4 –CaO–Ca(OH) 2 systems are considered. Some experimental examples are also shown.
Solid-gas reactions: Study of sulphation of limestone using thermogravimetry
Comparative data are presented on the absorption rate and capacity for SO2 capture by a natural Polish limestone with and without sodium chloride additive. Two sets of experiments were carried out, under dry and wet conditions during limestone calcination and sulphation.The presence of water vapour brought about a higher reactivity of the sorbent, probably as a result of an effect on the sintering of lime and through the influence of the CaSO4 layer. Further morphological investigations could provide confirmation of the present hypothesis.ZusammenfassungAbsorptionsgeschwindigkeit und -kapazität für SO2 an einem polnischen Kalkstein mit oder ohne NaCl-Zusatz werden verglichen. Zwei Reihen von Experimenten wurden in trockener bzw. wasserdampfhaltiger Atmosphäre bei der Calcination und Sulfatbildung durchgeführt. In Gegenwart von Wasserdampf wird die Reaktivität des Absorbens infolge Sinterung des Kalks und trotz des Einflusses der CaSO4-Schicht erhöht. Künftige morphologische Untersuchungen sollen diese Hypothese eventuel bestätigen.РезюмеПредставлены сравни тельные данные о скор ости и количестве поглоще ния двуокиси серы природным польс ким известняком в при сутствии добавки хлориастого натрия и без него. Обжиг и поглощение дв уокиси серы были пров едены в сухой и влажной атмос ферах. Присутствие паров во ды вызывает более выс окую реакционную способн ость сорбента, вероятно, вследствии спекания извести и вл ияния образующегося слоя с ульфата кальция. Дальнейшие морфолог ические исследовани я могут дать подтверждение выдви нутой гипотезе.
Thermal incompatibility analysis of metal-ceramic systems based on flexural displacement data.
The feasibility of simple tests or analytical methods for prediction of residual stress states in metal-ceramic (MC) prostheses has not been demonstrated. Biomaterial metal-ceramic strips have been proposed to provide sensitive measures of transient and residual stress states through the measurement of midpoint deflection after cooling from the ceramic sintering temperature. The objective of this study was to apply the elastic-viscoelastic analogy to calculate transient and residual midpoint deflections in MC biomaterial strips and to compare these values with deflections measured with a beam-bending viscometer (BBV). Calculations and measurements were made for five MC systems that were found from a clinical study to be "thermally compatible" systems. Metal strips, 64 mm in length, 3 mm wide, and either 0.5 mm, 1.0 mm, or 2.0 mm in thickness, were veneered with four 0.25-mm thick layers of opaque porcelain. Midpoint deflection of the MC strips (ceramic oriented in the posterior position) was measured during cooling from an initial temperature of 700 degrees C. In general, the directions of the measured residual deflections did not agree with the "textbook" convention that negative deflections are associated with positive thermal contraction mismatch (alpha(M) - alpha(c) > 0) regardless of metal thickness. For a metal thickness of 0.5 mm, the residual midpoint deflection for all thermal contraction mismatch cases, except one, was positive (upward deflection) whereas the residual midpoint deflections were all negative when the metal thickness was increased to 1 or 2 mm, independent of the thermal contraction mismatch. The best agreement between calculated and measured values of residual midpoint deflection (+16 microns vs. +14 +/- 2.3 microns, respectively was obtained for MC biomaterial strips with a Ni-Cr alloy (0.5 mm thick) while the largest difference (+346 microns vs. +61 +/- 43.8 microns) was obtained for MC bimaterial strips with a Au-Pd allow (0.5 mm thick). In all but one case, changes in deflection direction as a function of metal thickness were correctly predicted by the viscoelastic analysis. The results of this study indicate that a viscoelastic model is useful for estimating thermal compatibility conditions of MC systems.