Patent ID: 7128818
Filing Date: 2006-10-31
Classification: G01N

Abstract:
1. A gas sensor system for monitoring gas concentrations in flue gas generated by a combustor, the gas sensor system comprising: a gas sensor comprising: an outer shell disposed in a stream of flue gas in a post-flame zone of the combustor, the outer shall having at least one opening in a fluid communication with the flue gas; a solid electrolyte cell disposed within the outer shell; at least one seal cooperating with the electrolyte cell to form a sensing chamber isolated from the flue gas; a first electrode disposed within the sensing chamber and being isolated from the flue gas so as not to be in a direct fluid contact with the flue gas; and a second electrode disposed in the outer shell and positioned in close proximity to the at least one opening so as to be in fluid contact with the flue gas, a voltage being generated across the first and second electrodes representing at least two conditions, wherein the first electrode and the second electrode generate a signal comprised of a DC component and a fluctuating AC component, the two conditions comprised of the DC component and a fluctuating AC component; and the gas sensor system further comprising a processing portion, the processing portion configured to analyze each of the DC component and a fluctuating AC component to determine gas concentrations in the flue gas; and wherein the first electrode and the second electrode are configured to have different time constants resulting in a measured potential between the first electrode and the second electrode the processing portion configured to analyze the measured potential to represent the fluctuating AC component.