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Abstract

The present invention relates to methods and means including a process and system for producing an elemental-mercury-free reference flue gas which is used to obtain background photometric measurements thereby eliminating the photometric interferences of flue gas components to the photometric measurement of mercury. In the process, elemental mercury is selectively removed from a portion of a gaseous stream (the reference portion) and the intensity of radiation absorbed is measured by a UV spectrometer on the resulting mercury-free reference gas, and thereafter the concentration of mercury in the remainder of the gaseous stream is determined through utilization of the ratio of the transmitted radiation of the mercury-containing flue gas with respect to that of the mercury-free reference portion of the gaseous stream. The mercury concentration can then be determined without interference by other absorbing moieties at 254 nm in the flue gas. The gist underlying the inventive concept of the instant invention relates to use of a porous bed of gold-coated material to effectively remove mercury from the reference portion of the gaseous stream without altering the composition of other radiation-absorbing components therein at the wavelengths utilized for measuring mercury. An important feature of this process is that it can be used to measure elemental mercury in a flue gas upon extractive sampling from a flue stack or after the extractive sample undergoes a process to convert the mercury species in the stream to elemental mercury prior to a total mercury measurement. The ability of the instant invention to monitor mercury in the presence of interfering agents is an essential feature for mercury emission control and for compliance by fossil-fueled industries and waste combustors.

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First Claim