Comparison between Spectrophotometry and Gas Phase Molecular Absorption Spectrometry for Determination of Nitrite Nitrogen in Flue Gas

Spectrophotometry and gas phase molecular absorption spectrometry for determination of nitrite nitrogen in flue gas were compared.KOH absorption solution was used to absorb nitrite nitrogen in flue gas,and the concentration of nitrite nitrogen in the absorption solution was determined by spectrophotometry and gas phase molecular absorption spectrometry to obtain the concentration of nitrite nitrogen in flue gas.The experiments show that both methods are accurate and reliable.

Comprehensive Theoretical and Experimental Studies on the CF3H Fire-extinguishing Mechanism

In order to clarify the chemical suppression mechanisms of CF3H, experimental and theoretical studies were conducted respectively in this paper. Firstly, the combustion species in low pressure laminar premixed flat methane flames with CF3H addition is measured by synchrotron radiation molecular beam mass spectrometry （SR-MBMS） experimentally. Fire suppression chemistry of CF3H is investigated by selective detection of combustion radicals and intermediates in experimental process. Secondly, quantum chemistry calculations are performed to calculate the potential energy surfaces （PES） for the CF3H unimolecular dissociation reaction and reactions of CF3H with free radical OH and H at the B3LYP/6-311-F ＋G＊＊ and QCISD（T）/6-311＋＋G＊＊ levels. Finally, the chemical suppression mechanism of CF3H was discussed by comparing the theoretical calculation with experimental measurement.

Investigation of the Laminar Premixed n-Propylamine Flame

The laminar premixed n-propylamine(NPA)flame with equivalence ratio of 1.70 has been investigated at 4666.28 Pa using tunable synchrotron photoionization and molecular-beam mass spectrometry techniques.Chemical structures and mole fractions of 40 species were determined.Ethenol,allylamine,butadiyne,vinylacetylene,1,3-butadiene,1-butene,2-butene,n-butyl radical,1,3-cyclopentadiene,cyclopentene,2-pentene,benzene,toluene,ethylbenzene,2-propen-1-imine,cyclopropanimine,pyrrole,2-butenenitrile and n-butylamine were newly identified in the amine flames.Mole fraction profiles of some species including reactants,intermediates and products in the NPA flame were given.HCN and N_(2)were observed as the primary N-containing products in the NPA flame,which was different from the result that NO was the major N-containing products in previous studies of nitrogen flames.The bond energies of NPA were calculated through quantum chemistry calculations on the basis of density functional theory at the CBS-QB3 level.It showed that the CH_(3)CH_(2)-CH_(2)NH_(2)bond was the weakest and NPA mainly decomposed to CH_(2)NH_(2)and C_(2)H_(5)radicals.The H-abstractions at C_(α)by OH/O(NPA+OH=CH_(3)CH_(2)CHNH_(2)+H_(2)O and NPA+O=CH_(3)CH_(2)CHNH_(2)+OH)had significant promoting effects on NPA consumption.The N conversion chain of NPA under flame conditions was proposed and detailed analysis with respect to intermediates especially the nitrogen-containing species were provided.The results will enrich the understanding of NPA flame and are essential to further establish the kinetic mechanism.