報告書番号

W96005

タイトル（和文）

低負荷対応用新型低ＮＯｘバーナのスケールアップ検討（その２）－旋回流入式バーナによる検討－

タイトル（英文）

SCALE-UP OF NEW LOW-NOX AND LOW-LOAD STABLE COMBUSTION PULVERIZED COAL BURNER (PART.2) -STUDY OF SWIRL INFLOW TYPE BURNER-

概要 （図表や脚注は「報告書全文」に掲載しております）

本報告では，低負荷対応用ＣＩ－αバーナ（燃焼量１．５ｔ／ｈ）の整流板による旋回抑制効果および微粉炭濃縮効果を非燃焼場で評価すると共に燃焼場で低負荷時の燃焼特性を明らかにし，燃焼量０．１ｔ／ｈ用バーナと比較を行った。（１）整流板の旋回抑制効果は，整流板係数が１．２以上でほぼ完全に旋回を抑止でき，バーナ容量によらず，ほぼ同一の相関関係を持つことが明らかとなった。（２）通常のＣＩ－αバーナでは着火限界が３０％負荷であったのに対し，１次空気管内に濃度調整リングを組み込むことにより，バーナ外周部の微粉炭濃度が約１．７倍にまで濃縮できることから，石油火力並みの２０％負荷でも安定燃焼できることを明らかにした。（３）微粉炭濃縮機能を付加した場合，負荷の低下に応じてＮＯｘ濃度は若干上昇するものの灰中未燃分は大幅に低減し，その低減効果はバーナ容量のスケールアップにより，一層顕著になることが示された。

概要 （英文）

WE HAVE ALREADY DEVELOPED A SCALED-UP (COAL FEED RATE:1.5 T/H) CI- BURNER (CRIEPI-IHI ADVANCED LOW POLLUTION HIGH ABILITY BURNER) WHICH ENABLED STABLE COMBUSTION AT LOWER LOADS LIKE AN OIL BURNER. IN THE BURNER, A LOW-CONCENTRATION FLOW OF PULVERIZED COAL IS CONCENTRATED BY SWIRLING FLOW AND THE COAL CONCENTRATION IS CONTROLLED BY A RING IN THE PRIMARY TUBE OF THE BURNER. HOWEVER, THE SWIRLING FLOW HAS A BAD EFFECT ON THE NOX REDUCTION FLAME AFTER THE PRIMARY-TUBE OUTLET. WE CONSIDERED HOW TO REMOVE THE SWIRLING FLOW AND KEEP THE CONCEPT OF STABLE COMBUSTION AT LOWER LOAD. THE ANSWER WAS STRAIGHTENERS TOREDUCE SWIRLING FLOW, PLACED BEFORE THE PRIMARY-TUBE OUTLET. THIS REPORT DESCRIBES THAT THE SCALE-UP EFFECT OF THE STRAIGHTENERS TO REDUCE THE SWIRLING FLOW, AND AN EVALUATION OF THE COAL CONCENTRATION AT THE RING BY A COLD-FLOW TEST. IN A COMBUSTION TEST, THE SCALED-UP EFFECT ON NOX CONCENTRATION, IGNITION CONDITION, AND THE QUANTITY OF UNBURNED CARBON IN THE FLY ASH, WERE INVESTIGATED. THE FOLLOWING RESULTS WERE OBTAINED. (1)THE SWIRLING FLOW PREVENTION COEFFICIENT INCREASED WITH THE STRAIGHTENER COEFFICIENT CALCULATED AS GROSS AREA OF STRAIGHTENERS AND AREA OF PRIMARY TUBE. THERE IS A GOOD AGREEMENT FOR THIS TREND AT LARGER BURNER SCALE. (2)THE MINIMUM LOAD OF THE SCALED-UP BURNER FOR STABLE COMBUSTION IS 20%, WHICH IS AS GOOD AS AN OIL BURNER WHERE THE RING POSITIONIS CLOSE TO THE PRIMARY-TUBE OUTLET. THIS IS BECAUSE IN A COLD-FLOW TEST, WHEN THE DISTANCE FROM THE BURNER OUTLET TO THE RING IS THE SHORTEST, THE COAL CONCENTRATION AT THE OUTSIDE IS THE HIGHEST IN THE PRIMARY TUBE. THE MAXIMUM VALUE OF THE COAL CONCENTRATION RATIO IS ABOUT 1.7. (3)FOR A BURNER WITH A RING, WHEN THE BURNER SCALE IS LARGER, THE NOX EMISSIONS IS INCREASE SLIGHTLY, BUT THE UNBURNED CARBON IN FLY ASH DECREASES GREATLY.

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