Patent ID: 8021617

Claim:
A system for monitoring sulfur trioxide/sulfuric acid levels in an emission stream comprising sulfur trioxide and water vapor flowing through an exhaust, the system comprising: a probe positionable adjacent to the exhaust to be able to extract essentially simultaneously a first supply of sample gas from the exhaust and a second supply of sample gas from the exhaust, wherein the second supply of sample gas is separate from the first supply of sample gas, the probe comprising the following elements housed within an outer probe shell: (i) an unspiked line for carrying the first supply of sample gas, (ii) a spiking line for carrying the second supply of sample gas, (iii) a catalyst for converting SO 2 gas to SO 3 gas, (iv) an inlet line for supplying SO 2 gas of a known quantity to the catalyst, (v) a heating coil positioned adjacent to the catalyst, (vi) a thermocouple, (vii) a carrier line for adding SO 3 gas generated at the catalyst to the second supply of sample gas in the spiking line to create a spiked gas, and (viii) an outlet line for carrying the spiked gas to a connector to measuring equipment, the connector to the measuring equipment, and the measuring equipment in the form of the means for measuring as claimed below, being located outside the probe; the system further comprising: a condenser for condensing sulfuric acid in the first supply of sample gas carried by the unspiked line; a condenser for condensing sulfuric acid in the spiked gas carried by the outlet line; means for measuring sulfuric acid content in the first supply of sample gas carried by the unspiked line; and means for measuring sulfuric acid content in the spiked gas carried by the outlet line; whereby the system is configured such that a comparison of the measuring of the sulfuric acid content in the first supply of sample gas carried by the unspiked line with the measuring of sulfuric acid content in the spiked gas carried by the outlet line can help validate the system.