Moisture measurement and its effect on SO{sub 2} allowances

With the implementation of the Clean Air Act and its amendments, the expense of emission allowances is a concern to all SO{sub 2} emitters. The effect of inaccurate measurements of the variables used in calculating SO{sub 2} pounds per hour (SO{sub 2} lbs/hr) can be a costly problem. These inaccuracies can result in unnecessary allowance purchases and/or usage. Currently, there are accurate and reliable methods available to continuously measure SO{sub 2} and flue gas flow rates, but not H{sub 2}O concentrations. The SO{sub 2} lbs/hr formula for conventional source monitoring uses the H{sub 2}O concentration to convert from a dry to a wet value. One method to obtain the H{sub 2}O is calculated. This method has been used in certifying systems in accordance with EPA requirements. This method provides a reported SO{sub 2} lbs/hr value that is partially dependent on the accuracy limits of the O{sub 2} monitors. The error of the primary data source (O{sub 2} analyzers) may be within EPA performance specifications, but may not provide satisfactory results when used to calculate H{sub 2}O concentrations. SO{sub 2} lbs/hr error has the potential to be costly when the number of allowances needed increases as a result of false highmore » SO{sub 2} emission levels.« less