OCR Text |
Show the velocity. Coal and air enter the furnace through the reburning burners on the rear wall. The flow turns upward and mixes with the cyclone gases flowing upward from the bottom of the furnace. A recirculation zone is formed above the reburning burners which circulates air downward from the OF A ports into the reburn zone. The recirculation zone is expected to improve carbon burnout; however, it may have a negative impact on overall NOll reduction because of the reduced size of the reburn zone. The OF A flow enters the furnace and turns upward while mixing with the reburn zone combustion gases. Predicted distributions of stoichiometric ratio (SR) were also used to evaluate mixing in the SBS. Figure 7 shows the comparison of in-furnace CO measurements with the predicted stoichiometries at four elevations in the SBS. In this comparison, only two regions of SR are shown with corresponding CO measurements. The shaded region is fuel-rich (SR> 1); the unshaded regions are fuellean (SR>I). Generally, the higher CO concentrations correspond to predicted fuel-rich regions. Aggreement is particularly good in the upper furnace. Some disparity exists in lower furnace presumably due to the delay of CO oxidation. LEFT SIDE: ~e1 FT u r--~~~ ~ ! >0 It ."',' .. ""---- .. .""""" .. .,.", __ _ It ., .,1 I ,"" ............. __ _ :: :::::::::~.::.: ..... " .) ,,, t, .•• .. .t It '11t , •• I, •• "~I"~"~ I t .t .",,\, . ~ . I I I • , \ ... " ..... , i • •• ,\\\" ..... ......... . '" ... ,\\' " ...... _ ... .. 11 ' ! : ! i IIIL:::--;:;:j: :: ~~~~~~ ~ .: :: ::::~ .:~. '~~, - •••• , I .., JI n )) 1"I l") u !: ," ~ .) I.,t , Jl')" " "'lU 1lU • SCAL£: 100 fT/sEC ~ ~NTER : Ie 2FT JJ ~~ ............... _-- , • ..... , ......... _-- " .. , ... "", .... _-- .I,I •..• ",."' ".. ' ,.. .' .,... ___ __ - It ,",,""" .. ,_-, .. _- .::, .: ": :" :::::::~: .....:.. :: ... ,. , ., ., ,.,, I, • . I. ,'1"1 ' II " 1111 11" ,. " .... " .. , .. .. s. "." ",., .. , H "i ~ ~ i i! iii ~i~; ~~;~~~~1: l! 'T::i!ilii':::i:ii:! !i .~ : :m:~:;::::::~ !liil~1 ;! !; =--:.;. I) '; , RIQtfT SIDE: Ie 3FT " ~-""'!"'!"!~~ ;"! .. ......... _-- :: :::::::::::=== .n. ........... _-- .u. u " .I.I U U ,"I.e u !.:. "I, I) .. .) II I • 1I "II 3 ' II ""u ".I,t '3 Il ': ! , Rgure 6. Pr,dlct8d Row Profiles for Pilot-Scale Rebumlng Conditions Reburner ElevDtion (6 ft., 0.5 In.) Uft ... !1Jl SR < 1 ~ Rebum Zone Measurement Elevltlon f1 fl, 10.5 In.) Bumout Zone Meaaurement Elevation (10ft.. 4.5 In.) Left ... 1*10 1*10 *40 Bumout Zone Me .. urement Elevation (14 ft., 4.75 In.) *II •* *10 1'IIgIt11l .. Rgure 7. Comparison of Measured CO (ppm) and Predicted Regions of SR < fin tM SBS for Rebumlng Conditions 6 i • l |