Field validation of sampling procedures for the speciation of mercury in flue gas

In order to assess the performance of continuous emissions monitoring systems (CEMS) in measuring total mercury, it was necessary to determine the species of the mercury present in the flue gas. It was therefore necessary to make reference measurements with a sampling train capable of speciating mercury emissions. Such a train was developed by the EPA office of Research and Development; and their contractor, Research Triangle Institute. A quad train was used. Measurements were made on the stack, but at a single point, not traversing. Two of the trains were dynamically spiked with mercury and mercuric chloride generated by a permeation device. The spiking was carried out by introducing gas phase mercury and mercuric chloride sequentially into the probes of two of the four trains while sampling from the stack. The spike amounts were on the order of the amount of mercury collected from the stack gas during the sampling period, and were verified by sampling the spike flow at the point of introduction into the MM29 probe with a midget impinger Method 29 train. A fresh M29 verification train was used for each spike to allow accurate determination of the amounts of mercury and mercuric chloride spiked. Nine (9)more » one to two-hour runs of the quad trains were made, with spiking of two of the trains carried out each time.« less