報告書番号

W97016

タイトル（和文）

高燃料比炭の微粉炭燃焼特性－石炭燃焼試験炉を用いた検討－

タイトル（英文）

PULVERIZED COAL COMBUSTION CHARACTERISTIC OFHIGH FUEL RATIO COAL -INVESTIGATION USING TEST FURNACE-

概要 （図表や脚注は「報告書全文」に掲載しております）

本研究では，燃料比が５．５と７．１の高燃料比炭を用い，微粉炭燃焼解きにおける着火性およびＮＯｘ・灰中未燃分排出特性に及ぼす燃料比の影響について検討を行った。（１）燃料比が高くなるほど着火性は悪くなり，その傾向は低負荷ほど顕著であった。また，バーナ近傍の高温場で再循環流を形成し微粉炭粒子の滞留時間を長くするバーナ形式の方が，高燃料比炭の安定燃焼範囲を拡大できることがわかった。（２）高燃料比炭燃焼時のＮＯｘ濃度および灰中未燃分濃度は瀝青炭に比べ高い値を示し，ＮＯｘ転換率は燃料比と窒素含有率の比の増加に伴い増大するが高燃料比になるほどその傾向は弱まる。未燃焼率は高燃料比になるに従い顕著な増大傾向を示すことがわかった。（３）二段燃焼によるＮＯｘの低減効果は燃料比の増加とともに減少し，その傾向は二段燃焼率が高くなるほど顕著になる。灰中未燃分濃度は燃料比が高くなるほど極端に増加することがわかった。

概要 （英文）

INGENERAL,COAL-FIRED POWER PLANTS USE BITUMINOUS COAL WITH A FUEL RATIO OF 1.0 TO 2.5,AND A HEAT VALUE OF 6500 TO 7000 KCAL/KG. HOWEVER,OTHER TYPES OF COAL WILL BE USED FOR COAL-FIRED POWER PLANTS,BECAUSE DEMAND FOR COAL IS INCREASING EACH YEAR AND THE COSTOF BITUMINOUS COAL IS INCREASING. HIGH-FUEL-RATIO COALS,WHICH ARE NOT NOW USED IN COAL-FIRED POWER PLANTS BECAUSE OF THEIR LOW IGNITABILITY,HAVE POTENTIAL DUE TO THEIR HIGH CALORIFIC VALUE AND LOW TRANSPORT COST PER CALORIE. THIS REPORT DESCRIBES THE EFFECT OF FUEL RATIO ON IGNITABILITY,NOX EMISSION CHARACTERISTICS AND RATIO OF UNBURNED CARBON IN FLY ASH USING COMBUSTION TESTS OF HIGH-FUEL-RATIO COALS WITH A 0.1-T/H PULVERIZED COAL FURNACE. (1) THE IGNITABILITY WAS WORSE WHEN THE FUEL RATIO INCREASED. THIS TENDENCY WAS OBVIOUS IN THE CASE OF LOW-LOAD COMBUSTION. THE CI- BURNER,WHICH PRODUCES RECIRCULATION FLOW IN FRONT OF THE BURNER-EXIT TO INCREASE THE RESIDENCE TIME OF PULVERIZED COAL PARTICLES,GAVE A STABLE FLAME AT COMBUSTION OF HIGH-FUEL-RATIO COALS.(2) NOX AND UNBURNED CARBON AT COMBUSTION OF HIGH-FUEL-RATIO COAL WAS HIGHER THAN FOR BITUMINOUS COAL. THE CONVERSION RATIO OF FUEL-BOND NITROGEN TO NOX ROSEWHEN THE FUEL RATIO WAS HIGH AND/OR THE CONTENT OF FUEL-BOND NITROGEN WAS LOW. HOWEVER,THIS TENDENCY WAS REDUCED IN HIGH-FUEL-RATIO COAL. ON THE OTHER HAND,THE NON-COMBUSTION FRACTION INCREASED AT COMBUSTION OF HIGH-FUEL-RATIO COAL. (3) THE NOX REDUCTION RATIO AT TWO-STAGE COMBUSTION DECREASED WITH INCREASED FUEL RATIO. THIS TENDENCY WAS VERY NOTICEABLE AT HIGHER TWO-STAGE AIR RATIOS BECAUSE THE REDUCING REGION BECAME SMALL AND THE AMOUNT OF NOX-REDUCING COMPONENTS SUCH AS HCN,NH3,ETC.,BECAME SMALL. ON THE OTHER HAND,THE UNBURNED CARBON CONTENT IN FLY ASH AT TWO-STAGE COMBUSTION WAS HIGHER THAN AT NON-STAGE COMBUSTION. THIS TENDENCY WAS OBVIOUS FOR HIGH-FUEL-RATIO COAL.

報告者

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