OCR Text |
Show seen for the temperat u r e his tor y n ear the burner along the axis. That is. the temperature rose to a maximum near the burner and then went down rapidly. This behavior was more distingwished at low excess 0, than at high excess 0,. At low excess O2 • the change of NOx concent rat ion for the s • a I I est par tic I e size was interesting to note that NOx was produced rapidly near the burner ( Z/D<4 ) but its concentration decreased with increasing Z/D in the region of Z/D = 4 ....... 10 where O2 concentration was less than 1% for.ing the reduction region. However. a region with the 0, concentration more than 4% was formed near the burner using the finest particles at high excess 0,. More than 4% of O2 concentration is too high to fori the reduction region even if the particle size is s.all. From these results, low air ratios at the burner by adopting the staged combustion and fine particles were found to be effective for reducing NOx concentration in this burner. 1. GOO----r----r--,.----,-tt-,.--, 500 Normalized Axial Position. 15 - ~ 10 ~ 5 Fig. 7 D istributjons of NO x Concentration along tlle Axis of Furnace under Low Excess 02 1.60 0 . . · • ""I I I C Coal I ex. 02=5% O~ 'h,iiI21111i1r" U~ O~ . "0 · "0"0 O~ · 1. 40 p - 1.20 ~ f- 1. 00 80 I~ • • . · Jl J'---,," c~ GO 0 Jl I , , , " . · 20 O~ ~~·---:~·~·t-···-()· .. ···rIO · O~ ,=::e--- ----e---'''. · O~ . \ 0 0--00 ~ , ·"'~~!:'!.-O C· 0-11'0 · O~ 'is 02 50 ~ . 30 10 ~ zu 6 . a . · a II ~ " o o 10 20 30 40 Outlet Normalized Axial Position. Z/D(-) .Fig.8 Distributions of NO x Concentration along the Axis of F umace under High Excess 02 -6- |