The Influence of Mixing on Staged Flame Processes (Synthesis of Hydrogen Cyanide or Acetylene and Ethylene by Light Hydrocarbons in a Flame Reaction)

Abstract

The formation of hydrogen cyanide by propane and ammonia and the formation of acetylene and ethylene by propane in flame-reactions was investigated in a special burner using pure oxygen as oxidant. It was possible to perform the reactions in a one-stage or a two-stage process under turbulent flow conditions

In the case of hydrogen cyanide formation in a one-stage process propane, ammonia and oxygen were fed as premixed gas or ammonia was added separately to premixed propane/ oxygen flames in various ways of mixing. In the two-stage process mixtures of propane and ammonia were fed into a flow of hot gas produced by combustion of hydrogen and oxygen. The yield of hydrogen cyanide was studied in dependence on reaction temperature, residence time and ratios of C/ N and C/ O. In the case of the formation of hydrogen cyanide best results were obtained when premixed propane/ oxygen jet flames were burning in a cross flow of cold ammonia with high ratios of C/ N and low ratios of C/ O. Similar yields ( 78% )could be observed when premixed ammonia/ propane/ oxygen jet flames were burning in a cross flow of cold hydrogen or carbonmonoxide. The results can be explained by observations of other authors in their investigations of the formation of soot in rich hydrocarbon/ oxygen flames and in studies of laminar premixed ammonia/ methane/ oxygen flames

The formation of acetylene by propane was investigated in premixed propane-oxygen flames which burnt in a cross flow of cold hydrogen. In this case the yield of acetylene ( 30% is higher as compared with premixed propane/ oxygen flames. Further investigations for the formation of acetylene were executed with diffusion flames. It could be shown that the ratio of momentum of the inner and outer jet influences the ratio of acetylene to ethylene. A total yield of acetylene and ethylene of 36% was obtained.