Detection and control of aromatic compounds in combustion effluent

A method for detecting the presence of dioxin in the effluent of a turbulent commercial combustion system, comprising:

• directly, selectively detecting the presence of high molecular weight polycyclic aromatic compounds having five or more rings by
• selecting excitation radiation having a fluorescence excitation wavelength that induces substantial fluorescence by said high molecular weight polycyclic aromatic compounds having 5 or more rings in the gas phase, and
• selecting a position along the effluent stream downstream of the flame or combustion region where said effluent has a temperature of about 1200.degree. C. or less and at which high molecular weight polycyclic aromatic compounds having 5 or more rings may be present in sufficient amounts such that fluorescence from said effluent, at said position, at said excitation wavelength is predominantly from said high molecular weight polycyclic aromatic compounds having 5 or more rings, when said high molecular weight polycyclic aromatic compounds are present in said amounts,
• illuminating said effluent at said position along the effluent stream with said radiation.
• detecting fluorescence from said illuminated effluent,
• analyzing said fluorescence to directly, selectively determine the presence of said high molecular weight polycyclic aromatic compounds having 5 or more rings in said effluent, and
• indirectly detecting the presence of said dioxins by correlating the fluorescence from said high molecular weight polycyclic aromatic compounds having 5 or more rings with the presence of said dioxins.

A method for controlling the production of aromatic hydrocarbons in a turbulent commercial combustion system, comprising:

• directly, selectively detecting the presence of high molecular weight polycyclic aromatic compounds having five or more rings by
• selecting excitation radiation having a fluorescence excitation wavelength that induces substantial fluorescence by said high molecular weight polycyclic aromatic compounds having 5 or more rings in the gas phase, and
• selecting a position along the effluent stream downstream of the flame or combustion region where said effluent has a temperature of about 1200.degree. C. or less and at which high molecular weight polycyclic aromatic compounds having 5 or more rings may be present in sufficient amounts such that fluorescence from said effluent, at said position, with said excitation radiation is predominantly from said high molecular weight polycyclic aromatic compounds having 5 or more rings, when said high molecular weight polycyclic aromatic compounds are present in said amounts,
• illuminating the effluent at said position,
• detecting fluorescence from said effluent,
• analyzing said fluorescence to directly, selectively determine the presence of said high molecular weight polycyclic aromatic compounds having 5 or more rings in said effluent;
• and
• effecting the composition of said effluent in response to said detecting.