ERROR in ESP - Emission Performance Test
Caution to Improve - Operational Performance of ESP
Pollution Control Equipment like ESP, Bag Filter etc should give effective performance to control emission within the authority prescribed range
ESP Design mainly depends on parameters like Inlet gas flow, Inlet dust concentration, Ash particle size, Ash chemical composition, Migration velocity, Electrical resistivity of fly ash & Specific Collection Area
ESP’s Performance test accuracy is most neglected activity in the plant & very less significant for end users. Any error in the testing is directly proportional to emission result & wrong performance data
According to my analysis & field experience, In most of the ESP's (>90%) Emission test result is not meeting the emission designed parameters consistently
ESP performance test code for Iso-kinetic sampling method is IS-11255, EPA Method-5 (at Outlet of Chimney) & Method–17 (at Inlet of Chimney)
ESP performance improved by presence of SOx vapors, Moisture content, Sodium alkali salts, Ferrous salts, Silica salts. ESP performance deteriorate by presence of CaO, MgO, Chlorides & higher fouling tendency of electrodes
CHECKS TO ELIMINATE ERROR IN EMISSION PERFORMANCE TESTING
GD test velocity mapping to achieve uniform gas distribution
Flue gas temperature drop≈10ºC max. across ESP
Separation of Cable Tray & Cables for ESP’s Electrical power, Instrument control & signal cables
Total Number of Sampling Port holes & sizes at ESP inlet & ESP outlet. Normally, the sampling ports shall be made in straight duct / stack length of 8D downstream and 2D upstream to avoid any flow disturbance / turbulences
Review procedure for ESP performance test method, SPM sampling & measurement method
Record the Thimble empty initial weight / final weight, carryout thimble conditioning, do Thimble marking before & after sampling
- If Initial weight is not known, emission test result is uncontrolled
- Thimble may be wet, scratched, punctured, change of thimble etc
- Malfunctioning / Weight reduction of Emission collected in thimble, loss of collected emission during thimble transfer, punctured, Improper removal of moisture, change of thimble, inaccuracy in final weight measurement of thimble etc
No air or gas leak in sampling train arrangement like vacuums pump, nozzle & thimble holder assembly, Attend before start
Error / Malfunctioning in Gas flow rate (Nm3/hr) measured quantity
Demand for site preliminary calculation report from testing agency after completion of emission testing and before leaving the site
Recheck final Performance test report w.r.t. earlier recorded data
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