Hydrocarbon Processing Issue 02 | Page 6

COMBUSTION SERVOMEX COMBUSTION ANALYSIS SOLUTIONS For O 2 analysis, Tunable Diode Laser (TDL) analyzers offer an average path measurement across all burners, while Zirconia analyzers measure a single point. TDL is susceptible to a range of environmental factors that must be compensated for, including path length variation, window purge gas effects, optical interferences and changes in temperature and pressure. Zirconia and TDL analyzers offer great advantages when considered as complementary techniques for combustion control. It is not unusual to see a SERVOMEX COMBUSTION MEASUREMENTS IN THE PROCESS HEATER CO reaction almost complete The oxygen measurements are relatively comparable; however, the measurement of the carbon monoxide with TDL showed a marked improvement in performance with a faster speed of response, ideal for both efficiency and – more importantly – safety, albeit at the cost of having a second analyzer. TDL measurements can also be built into flame-out protection, specifically the measurement of methane (CH 4 ) in natural gas burners. If a TDL analyzer is installed so that a burner flame-out can be detected quickly, it enables greater flexibility and response to control and shut down processes. TDL lasers come complete with SIL (Safety Integrity Level) certification and so can be incorporated into safety systems in a relatively straightforward manner. CONTROLLING COMBUSTION