JPH0467085B2 - - Google Patents
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- Publication number
- JPH0467085B2 JPH0467085B2 JP1197376A JP19737689A JPH0467085B2 JP H0467085 B2 JPH0467085 B2 JP H0467085B2 JP 1197376 A JP1197376 A JP 1197376A JP 19737689 A JP19737689 A JP 19737689A JP H0467085 B2 JPH0467085 B2 JP H0467085B2
- Authority
- JP
- Japan
- Prior art keywords
- desulfurization
- furnace
- waste
- agent
- desulfurization agent
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000006477 desulfuration reaction Methods 0.000 claims description 103
- 230000023556 desulfurization Effects 0.000 claims description 101
- 239000003795 chemical substances by application Substances 0.000 claims description 59
- 239000002699 waste material Substances 0.000 claims description 42
- 238000000034 method Methods 0.000 claims description 33
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 31
- 239000010881 fly ash Substances 0.000 claims description 16
- 229910021529 ammonia Inorganic materials 0.000 claims description 13
- 239000002253 acid Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 10
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 7
- 239000004202 carbamide Substances 0.000 claims description 7
- 230000003009 desulfurizing effect Effects 0.000 claims description 6
- 238000006386 neutralization reaction Methods 0.000 claims description 6
- 150000001875 compounds Chemical class 0.000 claims description 3
- 239000002002 slurry Substances 0.000 claims description 2
- 239000011575 calcium Substances 0.000 description 29
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 21
- 239000007789 gas Substances 0.000 description 20
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 8
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 8
- 239000003245 coal Substances 0.000 description 8
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 6
- 238000010521 absorption reaction Methods 0.000 description 6
- 239000002956 ash Substances 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 5
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 5
- 229910000019 calcium carbonate Inorganic materials 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 4
- 230000006872 improvement Effects 0.000 description 4
- WKBOTKDWSSQWDR-UHFFFAOYSA-N Bromine atom Chemical compound [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 239000002250 absorbent Substances 0.000 description 3
- 230000002745 absorbent Effects 0.000 description 3
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 description 3
- 229910052794 bromium Inorganic materials 0.000 description 3
- KZBUYRJDOAKODT-UHFFFAOYSA-N Chlorine Chemical compound ClCl KZBUYRJDOAKODT-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 150000007524 organic acids Chemical class 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052815 sulfur oxide Inorganic materials 0.000 description 2
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 1
- ZCYVEMRRCGMTRW-UHFFFAOYSA-N 7553-56-2 Chemical compound [I] ZCYVEMRRCGMTRW-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 238000000889 atomisation Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 235000019253 formic acid Nutrition 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Landscapes
- Chimneys And Flues (AREA)
- Treating Waste Gases (AREA)
Description
［産業上の利用分野］
本発明は、各種のボイラ、各種加熱炉さらに
は、ごみ焼成炉などから排出される燃焼排ガス中
の硫黄酸化物（SOx）と窒素酸化物（NOx）を
同時に乾式法によつて除去する炉内同時脱硫脱硝
方法に関する。
［従来技術およびその問題点］
現在採用されている一般的な脱硫・脱硝の方法
は、脱硝については還元剤としてアンモニアを使
用し触媒の存在下にNOxの選択接触還元を行な
う方式が主流であり、また脱流については湿式石
灰石こう法のような湿式法が採用されている。
しかしこれらの方式ではイニシヤルコストおよ
びランニングコストが高くつくため、より安価に
実施できる方式が望まれている。
本発明は、このような要望にこたえるべく達成
せられたもので、低コストで実施でき、しかも優
れた脱硫脱硝性能を発揮することができる炉内同
時脱硫脱硝方法を提供することを目的とする。
［問題点の解決手段］
本発明は、上記目的達成のために、火炉内の
1200℃以下900℃以上の温度領域に粉状またはス
ラリー状のCa系脱硫剤を投入して、炉内直接脱
硫反応を行なわせ、排ガスから廃脱硫剤を含むフ
ライアツシユを捕集し、この捕集アツシユに酸を
添加することによつて、廃脱硫剤中のCaOまたは
CaCO3の少なくとも一部の中和反応を経て、廃
脱硫剤を活性化させ、得られた活性化廃脱硫剤含
有フライアツシユにアンモニアまたは尿素ないし
その化合物を添加し、こうして処理したフライア
ツシユを火炉または煙道内の1000℃以下500℃以
上の温度領域へ再投入して、脱硫脱硝反応を行な
わせることを特徴とする。
本発明の方法において酸としては、塩酸、硝酸
などの液状無機酸；塩化水素、塩素、臭素、フツ
素、ヨウ素などの無機物質から生じる酸性ガス；
酢酸蓚酸などの液状有機酸；ギ酸などのガス状有
機酸が単独または組合せで適宜選択される。
捕集された廃脱硫剤含有フライアツシユは、好
ましくは、これを風力分級装置などで処理してフ
ライアツシユ分をできるだけ分離除去した後、酸
処理される。
つぎに、本発明の炉内同時脱硫脱硝方法を完成
するに至つた経緯について説明する。
炉内直接脱硫法は、湿式石灰石こう法などの湿
式法に比べて極めて簡単な方式であり、一般には
炭酸カルシウムまたは消石灰のようなCa系の吸
収剤の微粉物を火炉内に直接投入することによ
り、脱硫が可能である。しかしその脱硫効率は低
く、性能面で湿式法に比べて各段に劣つているた
め、実用段階には至つていない。
この脱硫効率を向上させる手段としては、
脱硫剤を炉内の最適温度領域に投入する、
脱硫剤と排ガスとの接触をよくするために、
脱硫剤粉体を炉内で均一に分散する方法を工夫
する、
脱硫剤によるSO2ガスの吸収反応は固・気反
応であり、粉体の表面積が反応支配ベースであ
るので、表面積の大きい粉体、すなわち粒子径
の小さな吸収剤を使用する、などの手段が考え
られる。
最近の米国EPAの報告では、炉内脱硫法の性
能について、投入したCaの量（モル／時）と炉
内で発生したSO2のガス量（モル／時）との比を
Ca／Ｓモル当量比（以下Ca／Ｓと呼ぶ）とする
と、Ca／Ｓ＝３では脱硫率は60％程度である。
この報告でのCa系脱硫剤の有効利用率は20％で
あり、残り80％のCa成分はCaOまたはCaCO3の
状態でフライアツシユとともに排出・廃棄されて
いる。このように従来の炉内脱硫法では一般に
Ca有効利用率が低く、湿式法のCa利用率95％以
上に比べて大差があり、その改善が必要である。
この有効利用率を向上させるには、このフライ
アツシユ中の未反応脱硫剤を含む使用済み脱硫剤
（本明細書で廃脱硫剤と呼ぶ）を炉内に循環投入
し、SO2の吸収に利用することが考えられる。
この再循環方式の最も典型的なものが循環流動
床方式であり、文献によるとCa／Ｓ＝1.5で脱硫
率は90％であると言われている。この時のCa利
用率は約60％であり、前述の従来炉内脱硫法のそ
れに比べて大巾に向上している。しかし、循環流
動床方式では、排出灰量に対する内部循環量が
100倍程度であると言われており、循環のための
動力損失がかなり大きい。
以上記述したように、従来の炉内脱硫方式は、
(イ) 90％以上の高脱硫率が得られないので、特に
公害規制が他国より厳しい日本国内ではSO2排
出基準をクリアできない、
(ロ) Caの有効利用率が極めて低いので、排出灰
量が増大し、薬剤コストが嵩む、などの理由か
ら、昭和40年代には国内でもかなり実施されて
いたものの、最近では欧米に比べてその規模は
小さいようである。
本発明者らは、以上に記述した炉内脱硫法の問
題点を解決する手段として、前述の）〜）の
点に対する基本的な改善、廃脱硫剤の再循環の実
施およびその廃脱硫剤のSO2吸収能力の改善、す
なわち廃脱硫剤の活性化手法の検討、さらにはこ
れに平行して、炉内同時脱硫脱硝法について研究
を行なつた。
その結果、次のことが明らかになつた。
(1) 吸収剤の粒子径を小さくすると、脱硫率が向
上する。たとえば炭酸カルシウム3μ以下の粉
体による脱硫性能は、Ca／Ｓ＝３で脱硫率90
％である。
(2) 廃脱硫剤を循環再使用すれば、再脱硫が起こ
る。たとえば、廃脱硫剤中の未反応の有効Ca
基準で、Ca／Ｓ＝３における脱硫率は67％程
度あり、廃脱硫剤を多量に循環すればさらに高
い脱硫率が得られる。しかし脱硫性能は上記(1)
に及ばない。
(3) 廃脱硫剤を活性化するには、酸（全ての酸が
適用可能）を用い、未反応脱硫剤の一部をこの
酸で中和処理する。そして処理廃脱硫剤を炉内
の高温場に投入すると、高温場におけるCa塩
の分解反応により、廃脱硫剤のSO2吸収能力が
Ca／Ｓ＝３で脱硫率90％を上回る。
(4) 上記(3)の中和処理後、炉内にアンモニアを添
加することにより、炉内で脱硫と同時に脱硝も
起こる。たとえばアンモニアの添加量をNH3
（モル）／（モル）＝３にすると、脱硝率は70％
である。この場合、予めNOx抑制燃焼を行な
わせ、NOx濃度を200ppm程度に抑制した排ガ
スに本発明の方式を適用すると、NOx濃度が
60ppmにまで低減可能となる。
以上の結果は、本発明者らの実施した炉内脱硫
硝試験により得られた。
［実施例］
以下、本発明の実施例を示す。
試験装置として、微粉炭燃焼量10Kg／ｈ規模で
炉容積約0.38m3の試験炉を用いた。
供試微粉炭としては、200メツシユ以下の大同
炭を用いた。排ガス中のSO2濃度は、液化SO2の
添加により800ppmに調整した。
炉内温度は、放散熱量を調整するこにより、最
適温度に保持した。脱硝試験時は微粉炭供給量を
制限し、温度を脱硝最適温度に調整した。なおこ
の時のNOx発生値は190〜210ppmであつた。
供試脱硫剤としては、3μ以下の微粉炭酸カル
シウムを用いた。廃脱硫剤の活性化剤としては、
塩酸ガス、酢酸、塩素ガス、臭素ガスなどを用い
た。脱硝剤としては、液化アンモニアまたは粉体
尿素を用いた。試験時の総発生排ガス量は100〜
120Nm3／時であり、脱硫剤および廃脱硫剤の炉
内分散には空気噴霧方式を採用した。
(1) 試験１
炭酸カルシウムをCa／Ｓ＝１〜３の範囲で段
階的に増量して、SO2の吸収能力を調べた。
この試験では、前述の）〜）の点について
改善を検討した。この試験結果の一例を第１図に
曲線Ａとして示す。この脱硫性能はCa／Ｓ＝３
で脱流率90％であり、EPA報告の性能をはるか
に上回つており、炉内脱硫法の実用化の可能性が
大きいことが明らかとなつた。
(2) 試験２
廃脱硫剤の脱硫性能について調べた。
廃脱硫剤中に含まれるCaSO4を除いた廃脱硫剤
を有効Ca基準のCa／Ｓ＝１〜４の範囲で段階的
に増量し、SO2ガスの吸収能力を調べた。その結
果を第２図中に曲線Ｂとして示す。その脱硫性能
はCa／Ｓ＝３で脱硫率68％である。この結果に
よつて、新規脱硫剤の性能には及ばないものの、
廃脱硫剤を大量投入すれば、さらに高い脱硫率が
得られることが明らかになつた。
(3) 試験３
試験２で用いた廃脱硫剤に塩化水素ガス、酢酸
蒸気、塩素ガス、臭素ガスなどをそれぞれ単独に
添加、各廃脱硫剤についてその脱硫性能を調べ
た。その結果、廃脱硫剤中のCaO（CaCO3も含
む）と酸の中和度合によつて脱硫率が大巾に変化
することがわかつた。その一例として塩化水素ガ
スを用いた場合について、有効CaO量の10％中和
時の廃脱硫剤の脱硫性能とCa／Ｓとの関係を第
１図中に曲線Ｃとし示す。曲線Ｃから、Ca／Ｓ
＝３で脱硫率90％以上が得られ、酸処理廃脱硫剤
は上記の中和法により活性化されており、新規脱
硫剤の性能を上回る脱硫性能を示すことが明らか
になつた。
(4) 試験４
試験３において塩化水素ガスの添加で活性化さ
れた廃脱硫剤にさらにアンモニアガスを添加し
た。
この試験では、微粉炭供給量を制限し、かつ廃
脱硫剤の吹き込み位置の温度を900℃に調整した。
この時発生したNOxは200ppmであり、アンモニ
アの添加量をアンモニアとこのNOとの比、すな
わちNH3／NOの比＝１〜５の範囲で段階的に増
量し、その脱硝性能を調べた。その結果を第２図
に示す。同図からわかるように、NH3／NO＝３
以上ではNOx除去率は70％と一定であつた。
また粉状の尿素を使用する場合は、NH3／NO
の比がアンモニアの２倍程度になるように尿素を
投入すると、脱硝性能はアンモニアの場合と同じ
となり、アンモニア添加に比べて性能がやや劣つ
た。しかしSO2の除去率は増大し、尿素は脱硫に
も効果があつた。
［適用例］
上記各試験の結果から、本発明による方法を微
粉炭供給量1800Kg／ｈ（乾燥ベース）のボイラ試
験プラントに適用した。
第３図に本発明によるプロセスフローを示す。
同図のフローシートにおいて、微粉炭を試験ボイ
ラ１の低NOx燃焼装置３で燃焼させる。タンク
１１内に蓄えられた脱硫剤は定量フイーダ１２に
より供給ラインへ送り出され、空気輸送によつて
ノズル２より炉内に噴射される。炉内では脱硫反
応が起こり、排ガス中のSO2濃度はCa供給量に見
あつた分だけ下がる。しかし、炉内においては
Caの有効利用率が35％に達していない。この廃
脱硫剤と微粉炭のフライアツシユは混合しなが
ら、ヒータ４ついでエアーヒータ７を通り、集塵
装置８に至る。ここで廃脱硫剤を含むフライアツ
シユが捕集され、一方排ガスは誘引フアン９を通
つて煙突１０より系外へ排出される。エアーヒー
タ７および集塵装置８から出た捕集アツシユは、
灰貯槽１３へ空気輸送されてここに蓄えられ、輸
送後の空気はバグフイルタ１４を経て系外へ排出
される。廃脱硫剤を含むフライアツシユは同槽１
３から一部排出され、定量フイーダ１５によつて
循環ライン１６へ送り出され、煙道６まで空気輸
送されて、ノズル５により煙道６内に噴射され
る。循環ライン１６には塩化水素ガスが供給さ
れ、廃脱硫剤の一部を中和する。この中和された
廃脱硫剤は循環ライン１６内で十分に活性化反応
を完結する。活性化廃脱硫剤含有アツシユの噴射
ノズル５の直前で循環ライン１６にアンモニアが
添加される。この方式により活性化処理を施した
廃脱硫剤は、煙道６からエアーヒータ７の上部付
近までの間で再脱硫反応を起こし、脱硝反応も併
発する。こうして脱硫・脱硝が同時に達成せられ
る。このプロセスにおける各部の代表的な使用を
以下に示す。
[Industrial Application Field] The present invention is a dry method for simultaneously removing sulfur oxides (SOx) and nitrogen oxides (NOx) from combustion exhaust gas discharged from various boilers, various heating furnaces, and even garbage incineration furnaces. This invention relates to an in-furnace simultaneous desulfurization and denitrification method. [Prior art and its problems] The mainstream desulfurization and denitrification methods currently in use use ammonia as a reducing agent and perform selective catalytic reduction of NOx in the presence of a catalyst. Also, for drainage, wet methods such as the wet lime-gypsum method are used. However, these methods require high initial costs and running costs, so a method that can be implemented at a lower cost is desired. The present invention has been achieved in response to such demands, and aims to provide an in-furnace simultaneous desulfurization and denitration method that can be implemented at low cost and exhibits excellent desulfurization and denitration performance. . [Means for solving problems] In order to achieve the above object, the present invention provides
Powdered or slurry Ca-based desulfurization agent is introduced into the temperature range of 1200℃ or lower and 900℃ or higher to cause a direct desulfurization reaction in the furnace, and the fly ash containing the waste desulfurization agent is collected from the exhaust gas. By adding acid to the ash, CaO in the waste desulfurization agent or
The waste desulfurization agent is activated through a neutralization reaction of at least a portion of CaCO 3 , and ammonia or urea or its compound is added to the resulting activated waste desulfurization agent-containing fly ash, and the thus treated fly ash is placed in a furnace or smoked. It is characterized by being re-injected into Hokkaido's temperature range of 1000°C or lower and 500°C or higher to carry out the desulfurization and denitrification reaction. In the method of the present invention, acids include liquid inorganic acids such as hydrochloric acid and nitric acid; acidic gases generated from inorganic substances such as hydrogen chloride, chlorine, bromine, fluorine, and iodine;
Liquid organic acids such as acetic oxalic acid; gaseous organic acids such as formic acid are appropriately selected alone or in combination. The collected waste desulfurizing agent-containing fly ash is preferably treated with an air classifier or the like to separate and remove as much of the fly ash as possible, and then treated with an acid. Next, the circumstances that led to the completion of the in-furnace simultaneous desulfurization and denitration method of the present invention will be explained. The in-furnace direct desulfurization method is an extremely simple method compared to wet methods such as the wet lime-gypsum method, and generally involves directly injecting fine powder of a Ca-based absorbent such as calcium carbonate or slaked lime into the furnace. desulfurization is possible. However, its desulfurization efficiency is low and its performance is much inferior to wet methods, so it has not reached the practical stage. The means to improve this desulfurization efficiency are to introduce the desulfurization agent into the optimum temperature range in the furnace, to improve the contact between the desulfurization agent and the exhaust gas, and to
Devise a method to uniformly disperse the desulfurizing agent powder in the furnace.The absorption reaction of SO 2 gas by the desulfurizing agent is a solid-gas reaction, and the surface area of the powder is the basis for controlling the reaction, so it is necessary to use powder with a large surface area. Possible means include using an absorbent with a small particle size. A recent U.S. EPA report describes the performance of in-furnace desulfurization as the ratio between the amount of Ca input (mol/hour) and the amount of SO 2 gas generated in the furnace (mol/hour).
Assuming the Ca/S molar equivalent ratio (hereinafter referred to as Ca/S), the desulfurization rate is about 60% when Ca/S=3.
The effective utilization rate of the Ca-based desulfurization agent in this report is 20%, and the remaining 80% of the Ca component is discharged and disposed of in the form of CaO or CaCO 3 along with the fly ash. In this way, conventional in-furnace desulfurization methods generally
The effective Ca utilization rate is low, and there is a large difference compared to the Ca utilization rate of 95% or more in the wet method, and improvement is necessary. In order to improve this effective utilization rate, the used desulfurization agent (herein referred to as waste desulfurization agent) containing unreacted desulfurization agent in this flyash is circulated into the furnace and used for absorption of SO 2 . It is possible that The most typical type of recirculation system is the circulating fluidized bed system, and according to literature, it is said that the desulfurization rate is 90% when Ca/S=1.5. The Ca utilization rate at this time is approximately 60%, which is a significant improvement over that of the conventional in-furnace desulfurization method described above. However, in the circulating fluidized bed method, the amount of internal circulation compared to the amount of discharged ash is
It is said to be about 100 times as much, meaning that the power loss due to circulation is quite large. As described above, the conventional in-furnace desulfurization method cannot (a) achieve a high desulfurization rate of 90% or more, so it cannot clear the SO 2 emission standards, especially in Japan, where pollution regulations are stricter than in other countries. ) Since the effective utilization rate of Ca is extremely low, the amount of discharged ash increases, and the cost of chemicals increases.Although it was widely practiced in Japan in the 1960s, it has recently become more widespread than in Europe and the United States. seems small. As a means of solving the problems of the in-furnace desulfurization method described above, the present inventors have made basic improvements to the above-mentioned points) to), implemented recirculation of the waste desulfurization agent, and In order to improve the SO 2 absorption capacity, we investigated the method of activating the waste desulfurization agent, and in parallel, we conducted research on the simultaneous in-furnace desulfurization and denitrification method. As a result, the following was clarified. (1) Decreasing the particle size of the absorbent improves the desulfurization rate. For example, the desulfurization performance with calcium carbonate powder of 3μ or less is 90% when Ca/S=3.
%. (2) If waste desulfurization agent is recycled and reused, re-desulfurization will occur. For example, unreacted available Ca in waste desulfurization agent
As a standard, the desulfurization rate at Ca/S=3 is about 67%, and if a large amount of waste desulfurization agent is circulated, an even higher desulfurization rate can be obtained. However, the desulfurization performance is as above (1)
It's not as good as that. (3) To activate the waste desulfurization agent, use an acid (any acid is applicable) and neutralize a portion of the unreacted desulfurization agent with this acid. When the treated waste desulfurization agent is put into the high temperature field in the furnace, the SO 2 absorption capacity of the waste desulfurization agent decreases due to the decomposition reaction of Ca salt in the high temperature field.
Desulfurization rate exceeds 90% when Ca/S=3. (4) After the neutralization treatment in (3) above, by adding ammonia into the furnace, denitrification occurs at the same time as desulfurization in the furnace. For example, change the amount of ammonia added to NH3
When (mol)/(mol) = 3, the denitrification rate is 70%.
It is. In this case, if the method of the present invention is applied to exhaust gas whose NOx concentration has been suppressed to about 200 ppm by performing NOx suppression combustion in advance, the NOx concentration will be reduced.
It is possible to reduce it to 60ppm. The above results were obtained from an in-furnace desulfurization test conducted by the present inventors. [Example] Examples of the present invention will be shown below. As a test device, a test furnace with a pulverized coal combustion rate of 10 kg/h and a furnace volume of approximately 0.38 m 3 was used. Daido coal of 200 mesh or less was used as the pulverized coal to be tested. The SO 2 concentration in the exhaust gas was adjusted to 800 ppm by adding liquefied SO 2 . The temperature inside the furnace was maintained at an optimum temperature by adjusting the amount of heat dissipated. During the denitrification test, the amount of pulverized coal supplied was limited and the temperature was adjusted to the optimum temperature for denitrification. Note that the NOx generation value at this time was 190 to 210 ppm. As the desulfurization agent tested, fine powder calcium carbonate of 3μ or less was used. As an activator for waste desulfurization agent,
Hydrochloric acid gas, acetic acid, chlorine gas, bromine gas, etc. were used. Liquefied ammonia or powdered urea was used as the denitrification agent. The total amount of exhaust gas generated during the test was 100~
120Nm 3 /hour, and an air atomization method was used to disperse the desulfurization agent and waste desulfurization agent inside the furnace. (1) Test 1 The amount of calcium carbonate was increased stepwise within the range of Ca/S=1 to 3, and the SO 2 absorption capacity was investigated. In this test, we investigated improvements in the above points) to). An example of this test result is shown as curve A in FIG. This desulfurization performance is Ca/S=3
The desulfurization rate was 90%, far exceeding the performance reported by EPA, and it became clear that the in-furnace desulfurization method has great potential for practical application. (2) Test 2 The desulfurization performance of the waste desulfurization agent was investigated. The amount of the waste desulfurization agent excluding CaSO 4 contained in the waste desulfurization agent was increased stepwise in the range of Ca/S = 1 to 4 based on effective Ca, and the absorption capacity of SO 2 gas was investigated. The results are shown as curve B in FIG. Its desulfurization performance is Ca/S=3 and the desulfurization rate is 68%. Although this result does not match the performance of the new desulfurization agent,
It has become clear that even higher desulfurization rates can be obtained by adding a large amount of waste desulfurization agent. (3) Test 3 Hydrogen chloride gas, acetic acid vapor, chlorine gas, bromine gas, etc. were added individually to the waste desulfurization agent used in Test 2, and the desulfurization performance of each waste desulfurization agent was investigated. As a result, it was found that the desulfurization rate varied widely depending on the degree of neutralization of CaO (including CaCO 3 ) and acid in the waste desulfurization agent. As an example, in the case of using hydrogen chloride gas, the relationship between the desulfurization performance of the waste desulfurization agent and Ca/S when neutralizing 10% of the effective amount of CaO is shown as curve C in FIG. From curve C, Ca/S
= 3, a desulfurization rate of 90% or more was obtained, and it was revealed that the acid-treated waste desulfurization agent was activated by the above neutralization method, and exhibited desulfurization performance that exceeded the performance of the new desulfurization agent. (4) Test 4 Ammonia gas was further added to the waste desulfurization agent activated by the addition of hydrogen chloride gas in Test 3. In this test, the amount of pulverized coal supplied was limited, and the temperature at the point where the waste desulfurization agent was blown was adjusted to 900°C.
The NOx generated at this time was 200 ppm, and the amount of ammonia added was increased stepwise within the range of the ratio of ammonia to this NO, that is, the ratio of NH 3 /NO = 1 to 5, and the denitrification performance was investigated. The results are shown in FIG. As can be seen from the figure, NH 3 /NO=3
Above, the NOx removal rate remained constant at 70%. In addition, when using powdered urea, NH 3 /NO
When urea was added so that the ratio was about twice that of ammonia, the denitrification performance was the same as with ammonia, and the performance was slightly inferior to that when ammonia was added. However, the removal rate of SO 2 increased, and urea was also effective in desulfurization. [Application Example] Based on the results of the above tests, the method according to the present invention was applied to a boiler test plant with a pulverized coal supply rate of 1800 kg/h (dry basis). FIG. 3 shows a process flow according to the present invention.
In the flow sheet shown in the figure, pulverized coal is burned in the low NOx combustion device 3 of the test boiler 1. The desulfurizing agent stored in the tank 11 is sent to a supply line by a metering feeder 12, and is injected into the furnace from a nozzle 2 by pneumatic transport. A desulfurization reaction occurs in the furnace, and the SO 2 concentration in the exhaust gas decreases by the amount of Ca supplied. However, inside the furnace
The effective utilization rate of Ca has not reached 35%. The fly ash of the waste desulfurization agent and pulverized coal passes through the heater 4 and the air heater 7 while being mixed, and reaches the dust collector 8. The fly ash containing the waste desulfurization agent is collected here, while the exhaust gas is discharged out of the system from the chimney 10 through the induction fan 9. The collection debris from the air heater 7 and dust collector 8 is
The ash is pneumatically transported to the ash storage tank 13 and stored there, and the air after transport is discharged to the outside of the system via the bag filter 14. The fly ash containing the waste desulfurization agent is in the same tank 1.
3 is partially discharged, sent to a circulation line 16 by a metering feeder 15, pneumatically transported to a flue 6, and injected into the flue 6 by a nozzle 5. Hydrogen chloride gas is supplied to the circulation line 16 to neutralize a portion of the waste desulfurization agent. This neutralized waste desulfurization agent sufficiently completes the activation reaction within the circulation line 16. Ammonia is added to the circulation line 16 immediately before the injection nozzle 5 of the ash containing the activated waste desulfurization agent. The waste desulfurization agent that has been activated by this method undergoes a re-desulfurization reaction between the flue 6 and the vicinity of the upper part of the air heater 7, and a denitrification reaction also occurs. In this way, desulfurization and denitrification can be achieved simultaneously. Typical uses of each part in this process are shown below.
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】【table】
【表】
［発明の効果］
本発明の炉内同時脱硫脱硝方法によれば、排ガ
スから廃脱硫剤を含むフライアツシユを捕集し、
この捕集アツシユに酸を添加することによつて、
廃脱硫剤中のCaOまたはCaCO3の少なくとも一
部の中和反応を経て、廃脱硫剤を活性化させ、得
られた活性化廃脱硫剤含有フライアツシユにアン
モニアまたは尿素ないしその化合物を添加し、こ
うして処理したフライアツシユを火炉または煙道
内にするので、従来不可能であつた低いCa／Ｓ
当量比にて（すなわち新規脱硫剤の低い消費量に
て）、90％以上という高い脱硫率を達成でき、さ
らに炉内同時脱硝についても70％以上という脱硝
率を得ることができる。[Table] [Effects of the invention] According to the in-furnace simultaneous desulfurization and denitration method of the present invention, fly ash containing waste desulfurization agent is collected from exhaust gas,
By adding acid to this collection assemblage,
The waste desulfurization agent is activated through a neutralization reaction of at least a portion of CaO or CaCO 3 in the waste desulfurization agent, and ammonia or urea or its compound is added to the obtained fly ash containing the activated waste desulfurization agent. Because the treated fly ash is placed inside the furnace or flue, low Ca/S, which was previously impossible, can be achieved.
At the equivalent ratio (that is, with low consumption of the new desulfurization agent), a high desulfurization rate of 90% or more can be achieved, and even with simultaneous in-furnace denitrification, a denitrification rate of 70% or more can be achieved.
第１図はCa／Ｓ当量比と脱硫率の関係を示す
グラフ、第２図はNH3／NO当量比と脱硝率の関
係を示すグラフ、第３図は本発明の実施例を示す
フローシートである。
Figure 1 is a graph showing the relationship between Ca/S equivalent ratio and desulfurization rate, Figure 2 is a graph showing the relationship between NH3/NO equivalent ratio and denitrification rate, and Figure 3 is a flow sheet showing an example of the present invention. be.
Claims (1)
粉状またはスラリー状のCa系脱硫剤を投入して、
炉内直接脱硫反応を行なわせ、排ガスから廃脱硫
剤を含むフライアツシユを捕集し、この捕集アツ
シユに酸を添加することによつて、廃脱硫剤中の
CaOまたはCaCO3の少なくとも一部の中和反応
を経て、廃脱硫剤を活性化させ、得られた活性化
廃脱硫剤含有フライアツシユにアンモニアまたは
尿素ないしその化合物を添加し、こうして処理し
たフライアツシユを火炉または煙道内の1000℃以
下500℃以上の温度領域へ再投入して、脱硫脱硝
反応を行なわせることを特徴とする炉内同時脱硫
脱硝方法。1. Powdered or slurry Ca-based desulfurization agent is introduced into the temperature range of 1200°C or lower and 900°C or higher in the furnace.
By conducting a direct desulfurization reaction in the furnace, collecting the fly ash containing the waste desulfurizing agent from the exhaust gas, and adding acid to this collected assemblage, the amount of the waste desulfurizing agent is removed.
The waste desulfurization agent is activated through a neutralization reaction of at least a portion of CaO or CaCO 3 , and ammonia or urea or its compound is added to the obtained fly ash containing the activated waste desulfurization agent, and the thus treated fly ash is placed in a furnace. Alternatively, an in-furnace simultaneous desulfurization and denitration method characterized by reinjecting the flue into a temperature range of 1000°C or less and 500°C or more to carry out a desulfurization and denitration reaction.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1197376A JPH0359303A (en) | 1989-07-28 | 1989-07-28 | Simultaneous in-furnace desulfurization and denitrification method |
| US07/552,382 US5171552A (en) | 1989-07-19 | 1990-07-13 | Dry processes for treating combustion exhaust gas |
| IT06755790A IT1242718B (en) | 1989-07-19 | 1990-07-17 | DRY PROCEDURE FOR COMBUSTION EXHAUST GAS TREATMENT |
| KR1019900010847A KR930003212B1 (en) | 1989-07-08 | 1990-07-18 | Dry-type treating method for exhaust gas |
| DE4023030A DE4023030C2 (en) | 1989-07-19 | 1990-07-19 | Dry process for the treatment of combustion exhaust gases |
| CN90104756A CN1038312C (en) | 1989-07-19 | 1990-07-19 | Dry processes for treating combustion exhaust gas |
| GB9015848A GB2234232B (en) | 1989-07-19 | 1990-07-19 | Dry processes for treating combustion exhaust gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1197376A JPH0359303A (en) | 1989-07-28 | 1989-07-28 | Simultaneous in-furnace desulfurization and denitrification method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0359303A JPH0359303A (en) | 1991-03-14 |
| JPH0467085B2 true JPH0467085B2 (en) | 1992-10-27 |
Family
ID=16373478
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1197376A Granted JPH0359303A (en) | 1989-07-08 | 1989-07-28 | Simultaneous in-furnace desulfurization and denitrification method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0359303A (en) |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100303388B1 (en) * | 1999-06-02 | 2001-09-24 | 세 영 모 | Aaaaa |
| US6405664B1 (en) * | 2001-04-23 | 2002-06-18 | N-Viro International Corporation | Processes and systems for using biomineral by-products as a fuel and for NOx removal at coal burning power plants |
| US6883444B2 (en) | 2001-04-23 | 2005-04-26 | N-Viro International Corporation | Processes and systems for using biomineral by-products as a fuel and for NOx removal at coal burning power plants |
| US6752848B2 (en) | 2001-08-08 | 2004-06-22 | N-Viro International Corporation | Method for disinfecting and stabilizing organic wastes with mineral by-products |
| US6752849B2 (en) | 2001-08-08 | 2004-06-22 | N-Viro International Corporation | Method for disinfecting and stabilizing organic wastes with mineral by-products |
| JP2007253130A (en) * | 2006-03-27 | 2007-10-04 | Taiheiyo Cement Corp | Furnace exhaust gas purification method and heat treatment apparatus having exhaust gas purification function |
| JP5420142B2 (en) * | 2006-06-16 | 2014-02-19 | 中国電力株式会社 | Method for improving dust collection efficiency of dust collector |
| CN111701432B (en) * | 2020-05-06 | 2022-12-23 | 佛山市吉力达铝材科技有限公司 | Denitration desulfurizer and preparation method thereof |
| CN112354336A (en) * | 2020-09-15 | 2021-02-12 | 山东莱顿能源技术有限公司 | Method for preparing desulfurizer and denitrifier from unburned carbon and application |
-
1989
- 1989-07-28 JP JP1197376A patent/JPH0359303A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0359303A (en) | 1991-03-14 |
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