Formaldehyde Formation Mechanisms in Large-Bore Natural Gas Engines
Recent testing of exhaust emissions from large bore natural gas engines has indicated that formaldehyde (CH2O) is present in amounts that are significantly relative to hazardous air pollutant standards. In consequence, a detailed literature review has been carried out to assess the current state of knowledge about formaldehyde formation mechanisms to evaluate its applicability to gas engines. In this paper, the following topics from the review, which bear directly on formaldehyde formation in natural gas engines, are discussed: (1) post combustion equilibrium concentrations, (2) chemical kinetics, (3) flame propagation and structure, (4) partial oxidation possibilities, (5) potential paths for formaldehyde. Relevant data taken from the literature on equilibrium concentrations and in-flame temperatures and concentrations are presented in graphical form.