Improved Throttling Calorimeter Steam Quality Measurement
By Tom McAuliffe
Acceptance testing of steam scrubbers to verify performance guarantees has proven difficult to implement, and therefore, difficult to enforce. Geothermal steam scrubbers are typically guaranteed to have an outlet steam quality that is equal to or greater than 99.8%. A standard throttling calorimeter, used for testing for steam quality, has an uncertainty of approximately +/- 0.1 % quality. Two alternative throttling calorimeter designs are proposed that should provide improved steam quality measurement accuracy. The proposed alternate throttling calorimeter, and enhanced alternate throttling calorimeter, offer geothermal owners and developers improved methods of enforcing such guarantees based upon firm thermodynamic principles. The uncertainty associated with the alternate method is an order of magnitude improved over the traditional throttling calorimeter. The enhanced alternate calorimeter provides four-times improvement over the alternate method. The enhanced alternate solution is more complex but has the highest potential level of accuracy, has an accuracy that only depends upon the uncertainty in the differential pressure measurement, and provides a highly graphical solution, the results of which would be difficult to dispute.
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