Ionic Mechanisms of Carbon Formation in Flames.
Abstract
A critical survey of the literature and experimental mass spectrometric studies of ion profiles in low pressure acetylene and benzene flames support an ionic mechanism of soot nucleation. The initial precursor ion, C3H3+, is produced by chemi-ionization and this ion grows by very rapid ion-molecule reactions with acetylene and other C(x)H(y) species to produce larger ions which eventually become incipient soot particles. Preliminary computer simulations using the proposed mechanism qualitatively describe many of the observed experimental features including the rapid growth of large ions. A new definition of the Threshold Soot Index, TSI, as a relative number varying from 0 to 100 (from least to greatest tendency to soot) makes it possible to organize all literature data on both premixed flames and diffusion flames into two rational sets so that the effect of molecular structure on sooting determined by different techniques can be compared. The results show more major differences from accepted trends. Selected available data on soot formation in gas turbine combustors for various fuel compositions have been compared with laboratory data on soot formation for various fuels in a search for a simple correlation. For some sets of data such a correlation was found for TSI, or the reciprocal of the fuel smoke point (related to TSI), but for other sets of data the correlation was poor. The reasons for the differences are not understood. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1981
- Accession Number
- ADA102411
Entities
People
- D. B. Olson
- H. F. Calcote