摘要 |
<p>A method of viewing the flame produced by a burner in a furnace is provided, comprising viewing the flame through an interference filter adapted to pass light of only a narrow wavelength range, in which the wavelength range corresponds to a wavelength which is stronger in the light emitted by the burner than in the ambient light of the furnace. The method is particularly applicable to viewing the flames produced by natural gas burners in petroleum crackers and the preferred wavelength range is that of sodium.</p> |