The reaction of fuel-sulfur in hydrocarbon combustion

Abstract

Comprehensive sulfur species measurements were performed on combustion gases in a premixed, jet-stirred reactor containing 0.23 mole % total sulfur. Species measured were H 2 S, COS, CS 2 , C 4 H 4 S, SO 2 , O 2 , CH 4 , and C 2 H 2 by gas chromatography; relative SH and CS and absolute OH by uv absorption spectroscopy; and SO 3 by controlled condensation. Reactor fuels were C 3 H 8 , C 2 H 2 , CH 4 , H 2 , and a H 2 /CO mixture. Sulfur dopants were C 4 H 4 S, H 2 S, and SO 2 . Reactor conditions were 1600≤T≤1800 K, 0.7≤Ф≤1.7, and 3.5≤τ≤7 ms. Pressure was 0.9 atm, except for SO 3 measurements at 0.9≤P≤2.9 atm. It was confirmed that SO 2 was always the dominant product. In fuel-rich flames lacking significant hydrocarbons, H 2 S was the stable non-SO 2 product sampled—of order 5% yield. In hydrocarbon flames at richer conditions, COS and CS 2 replaced H 2 S as the non-SO 2 product. Kinetic interpretation indicated that internal equilibration of the S−H−O subsystem occurred and that H 2 S, COS, and CS 2 likely formed within the sample probe through reaction of SO. The SO 3 measurements, in conjunction with inference of O-atom concentrations from measured OH, indicated that the reaction SO 2 +O+M→SO 3 +M predicts SO 3 formation provided that a second order pressure limit of 0.3 atm is assumed.