Fossil Fuels contain Sulfur which oxidizes during combustion forming SO_2 and SO_3. Both SO_2 and SO_3 are acid gases but they pose different challenges for power producers. SO_3 interferes with other emissions controls processes such as SCR/SNCR for NO_x and Active Carbon Injection (ACI) for Mercury. SO_3 also creates its own issues such as Air Heater fouling, ESP performance and Blue Plume. Measurement of SO_3 and its condensable compounds are the first step towards an effective strategy to manage and mitigate the Balance of Plant (BOP) impacts of SO_3.The direct measurement of SO_3 particularly for reporting purposes is very difficult and the current state of the art for such measurements is manual Controlled Condensate Measurements (CCM) - albeit this technique has its own set of challenges.This paper presents the methodology of measuring SO_3 and its compounds as condensables using a Dewpoint measurement device. The unique approach of this device is based on a 'Kinetic' measurement approach as opposed to an 'Equilibrium' measurement approach that has been used in practice in the past with limited success. The data presented by this device allows it to be used as a 'condensables chromatograph' that allows the identification of various species of condensables based on the temperatures at which they condense. The specific data reported by this device has now been successfully employed in real-time closed loop control to mitigate the BOP impacts of Sulfur condensables.This paper will also present some early work being done on extending the application of this device to Wet and Dry stack measurement of SO_3 with a high level of accuracy. An early prototype of such a device has been developed and is currently going through alpha testing.
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