Kinetics of NO-Char Reaction at Temperatures of 1073-1573K

Abstract

Two Chinese coals (YB lignite coal and SH bituminous coal) were used to prepare the chars. The chars were obtained in an entrained flow reactor which can simulate the temperature and gas composition of a true pulverized coal combustion environment. The kinetic characterization of NOchar reaction was performed by isothermal thermogravimetry in the temperature range 1073-1573K. It was confirmed that the reactions were under chemical kinetic control in the lowtemperature regime (1073-1273K) for SH char. The discrete random pore model was applied to describe the NO-char reactions. The model can predict the data at 1073 and 1173K very well, but underestimate the reaction rates at high carbon conversions, which can be attributed to the catalysis of inherent minerals in chars. However, the influence of the catalysis on reactions of SH char is moderate. Ultimately, the determined intrinsic activation energy of NO-char is 111 J/mol.

Application of Fast Gas Chromatography–Mass Spectrometry in Combination with the QuEChERS Method for the Determination of Pesticide Residues in Fruits and Vegetables

“…In the last years, tandem mass spectrometry (MS/MS) has emerged as a very interesting approach since it allows minimizing matrix interferences and chemical noise in the chromatograms, improving selectivity and sensitivity. Numerous applications based on GC-MS/MS have been reported for the determination of multiclass pesticides using triple quadrupole (Cervera et al 2010;Frenich et al 2005;Medina et al 2009) or ion trap detector analyzers (González-Rodríguez et al 2008;Zhang et al 2008), some of them including around or more than 100 target analytes. In parallel to the interest of increasing the number of compounds in a single chromatographic run, there is a trend to decrease chromatographic run times in multiresidue analysis.…”

Experimental study on no heterogeneous reduction by char

“…Several experimental studies [8][9][10] have shown that coal char has a reduction effect on NOx during coal combustion. Zhang et al [11] illustrated the char-NO reaction in the range of 1073~1573 K by isothermal thermogravimetry using coal char obtained from an entrained-flow reactor, and found that chemical kinetics controlled the NO-char reaction at 1073~1273 K. Sun et al [12] thermodynamically characterized the char-NO reaction in the range of 973~1573 K with isothermal thermogravimetry, and found a similar phenomenon: chemical kinetics controlled the char-NO reaction at low temperature, and diffusion kinetics controlled the reaction at high temperature.…”