4"12-Z 1 - part - usaid
4"12-Z 1 - part - usaid
4"12-Z 1 - part - usaid
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ECO-04. ECO-06, AND ECO-OB CALCULATIONS<br />
IN-SITU OXYGEN ANALYZERS. MAZUT FLOW METERS AND COAL FLOW METERS<br />
1 0 INTRODUCTION<br />
The bOilers air to fuel ratio IS controlled manually The eXisting extractive paramagnetic<br />
type oxygen analyzers are maintained and calibrated However, the Instruments are prone<br />
to being fouled by mOisture and aCid sludge from the flue gas. Also, there IS a slgntflcant<br />
time lag between sample POint and readout, which IS aggravated by sWings In excess oxygen<br />
due to fluctuations of coal feed to burners The biggest problem with the eXisting extractive<br />
analyzers IS that the sample IS taken after major air In-leakages has already occurred<br />
Installation of in-Situ zircontum oXide cells upstream of major In-leakages would Improve<br />
reliability, response, and accuracy of readings<br />
2 0 ASSESSMENT OF POTENTIAL EXCESS OXYGEN REDUCTION<br />
There IS the potential to reduce the levels of excess oxygen at the Burshtyn untts This<br />
potential IS based on the current levels of excess oxygen that are maintained at the burners<br />
In order to assess thiS potential, It IS necessary to evaluate the measured excess oxygen<br />
levels and account for air In-leakage through the various sections of the bOiler Normal<br />
burner deSign calls for an excess oxygen level at the burners of 3 5% For burners of thiS<br />
deSign and vintage, It would be more appropriate to assume that the excess oxygen level<br />
would be closer to 4 0% These are the minimum levels required for stable flame and<br />
proper combustion. Excess oxygen levels higher than thiS prOVide the opportuntty for a reduction<br />
In the operating levels.<br />
2.1 Evaluation of Excess Oxygen at the Burners<br />
At full load firing coal, the excess oxygen was measured In the convection pass and ahead<br />
of the air heaters The excess oxygen measured was a maximum of 6 1% BRC calculation<br />
Indicates that the corresponding excess oxygen at the burner IS about 5.0%<br />
Accounting for the eXisting burner deSign, the minimum excess oxygen at the burners would<br />
be assumed to be approximately 4 0% Thus, the potential reduction In excess oxygen at<br />
the burners would be 5 0 - 4 0 = 1 0%<br />
2.2 Effect of Excess Oxygen on BOiler EffiCiency<br />
Baller effiCiency IS calculated based on the ASME Baller Test Code, PTC-4 1 The losses In<br />
bOiler effiCiency affected by the excess oxygen levels are the dry flue gas loss and the<br />
mOisture In air loss The dry flue gas loss IS the loss of heat determined by the flue gas flow<br />
and the difference In temperature of the flue gas and the ambient air. The mOisture In air<br />
loss IS the same loss calculated for the mOisture that IS contained in the air<br />
The reference excess oxygen was selected to be 4 0%, which IS typical for coal fired burners<br />
of thiS deSign and vintage BOiler effiCiency was calculated for excess oxygen levels up<br />
to 6%, to account for pOSSible operating conditions above the optimum<br />
G \BENDER\BURSCALC 1 MAY 3, 1995
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