Patent ID: 8443648

Claim:
A continuous emissions monitoring system that is in fluid communication with a flue stack conducting exhaust gas from a combustion source, the continuous emissions monitoring system comprising: an analyzer for measuring concentrations of an analyte present in the exhaust gas; a probe in fluid communication with the flue stack, the probe having an inlet to acquire a sample of exhaust gas from the flue stack, the probe also having an outlet to return the sample to the flue stack, the probe being in fluid communication with the analyzer, and the probe inlet being located upstream of the analyzer, the probe tending to remove analyte from the sample; a calibration checking system in fluid communication with the probe at a location downstream of the probe inlet and upstream of the analyzer, the calibration checking system including: a source that provides a gas flow of a known concentration of calibration material to be measured by the analyzer, the calibration material being chemically the same as the analyte; a supply system including a water source and a pressurized gas located upstream of the water source, the supply system providing a water flow to a mass flow controller; and a humidifier that combines the gas flow and the water flow from the mass flow controller to provide moisture to the calibration material, the moisture acting to remove accumulated analyte from the probe and thereby enable an accurate measurement of the concentration of the calibration material; and an air cleanup panel fluidly connected to the probe at a first location upstream of the analyzer and at a second location downstream of the analyzer.