From:	Schaffner, Karen S. <ksschaffner@rti.org>
Sent:	Monday, June 08, 2009 2:23 PM
To:	'warren.dean@siemens.com'
Subject:	NOx Chapters:  Siemens TDL NH3 slip

Good Afternoon, Mr. Dean:  Thank you very much for the information on Siemens TDL ammonia 
monitoring system you shared today.  I have included a summary of our discussion below and 
hopefully I understood you clearly.  Please feel free to correct me or expand on.  Thank you, 
Karen Schaffner

The Siemens TDL for ammonia monitoring is in place at approximately 90 to 100 full-scale coal-
fired units in the U.S.  Facilities measure NH3 slip concentration after the SCR (and SNCR) and 
before the air heater.  Some facilities measure at up to 3 points in the duct between the SCR and 
AH (for example, at 10 foot distances) to account for or eliminate any stratification.  The Siemens 
TDL unit has a capital cost of approximately $40,000 for one point of measurement; 
measurement at three points could be up to $70,000 for capital cost.



Karen Schaffner
Air Quality Engineering Group
RTI International
3040 Cornwallis Rd (800 Park, C311)
Research Triangle Park, NC  27709
phone:  (919) 316 3740
fax:  (919) 541 7155

