Sampling interface for continuous monitoring of emissions

Abstract

Sampling interfaces and methods of operation thereof having increased duty cycles and pressure equalizations that improve sensing of airborne metals in air samples fed to a continuous emissions monitor. Residual pressure in one or two sample reservoirs (loops) can be automatically equalized just prior to pneumatic connection between each sample reservoir loop and plasma in a plasma torch, thus minimizing or eliminating perturbation of the plasma. Deliberate sequential activation of valves allows each sample reservoir loop to be first isolated from the vacuum pump, and then momentarily as its pressure is equalized, it remains isolated from the plasma as well. Finally, pneumatic connection is made between each sample reservoir loop and the plasma allowing the contents of each sample reservoir (now at the same pressure as the plasma) to be transported into the plasma. Sampling interface having dual elongate sample reservoirs that alternate aliquots of sample air nearly doubles the rate of measurement of air entrained metals relative to a single elongate reservoir loop arrangement. By allowing measurements to be made at more frequent intervals using more representative sampling of extracted flue gases or air, the dual loops may permit the acquisition of hazardous emissions monitoring data that is more meaningful in terms of its temporal characteristics.