JP3698916B2 - Method and apparatus for removing mercury from coal flue gas - Google Patents

Method and apparatus for removing mercury from coal flue gas Download PDF

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JP3698916B2
JP3698916B2 JP13807999A JP13807999A JP3698916B2 JP 3698916 B2 JP3698916 B2 JP 3698916B2 JP 13807999 A JP13807999 A JP 13807999A JP 13807999 A JP13807999 A JP 13807999A JP 3698916 B2 JP3698916 B2 JP 3698916B2
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coal
exhaust gas
mercury
gas
chlorine compound
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JP2000325747A (en
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博文 吉川
浩 石坂
成仁 高本
滋 野沢
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Mitsubishi Power Ltd
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Babcock Hitachi KK
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Description

【０００１】
【発明の属する技術分野】
本発明は、石炭類の燃焼排ガス中の水銀除去方法および装置に関し、特にボイラなどの燃焼装置から排出される排ガス中に含まれる水銀を効率的に除去する方法および装置に関するものである。
【０００２】
【従来の技術】
火力発電所等において、石炭などの化石燃料の燃焼に伴って発生する排煙中の水銀（排煙中では主として金属水銀または塩化水銀として存在）は含有量は多くないが、その毒性の強さから処理技術の普及が望まれている。排ガス中の水銀を除去する方法としては、ごみ焼却炉から排出される排ガス中の水銀処理が盛んに検討されている（特公平６−６１４２４号および同６−１０４１８２号）。これはごみ焼却炉からの排ガス中により高濃度の水銀が含まれているためである。特公平６−６１４２４号および同６−１０４１８２号には、吸収液または固体吸収剤を排ガス中に噴霧し、排ガス中の水銀を剤に捕集し、排ガス中のばい塵などとともに水銀を捕集したものを後流のバグや電気集塵機などの集塵装置で回収する方法が開示されている。
図６は、石炭焚きの火力発電所にこのような固体吸収剤を排ガス中に噴霧して排ガス中の水銀を除去する排煙処理システムの一例を示したものである。
【０００３】
ボイラ２から排出される排ガスＤは、脱硝装置４、Ａ／Ｈ（エアヒータ、以下同様）５およびＧＧＨ（ガスガスヒータ、以下同様）の熱回収部６を経由して水銀除去装置１３に導かれ、そこでライン１４から供給された固体吸収剤Ｅが噴霧される。排ガス中の水銀を含んだ吸着剤はばい塵とともに後流のＥＰ（電気集塵装置、以下同様）７に導かれ、排ガス中のばい塵とともに水銀を含んだ吸収剤が除去される。ＥＰ７で除去されなかったばい塵を含む排ガスは脱硫装置８に導入され、排ガス中のＳＯ2 が除去され、さらに脱硫装置８から排出された排ガスはＧＧＨの再加熱部９で排ガス温度を高められた後、煙突１０から排出される。
【０００４】
しかし、このような従来技術では、吸収液または固体吸収剤を排ガス中に噴霧する装置および吸収液または固体吸収剤と排ガスをある程度の時間（通常、数秒）接触させるための反応器が必要になり、その設置スペースを確保する必要がある。また、比較的高価な吸収液または固体吸収剤を消費するのはいうまでもない。新たに発電所を建設する場合は、あらかじめ必要なスペースを確保しておけばよいが、既設の発電所にこのような吸収液または固体吸収剤を排ガス中に噴霧する装置および反応器を追設することとは実質的に不可能である。
【０００５】
既設のプラントに適用可能な方法として、ごみ焼却炉においては、供給するごみに塩素化合物を添加する方法（特公昭６２−４７５７２号）、また特公昭６２−４７５７２号には、ごみ焼却炉に供給するごみに塩素化合物を添加し、後流の洗浄装置で洗浄水により洗浄して排ガス中の水銀を捕集・回収する方法（特公昭６２−４７５７２号）が知られている。また、特公昭６２−４７５７２号に示された技術では、集塵装置では水銀は除去不可能であり、また洗浄水で効率よく除去するには、尿素やキレート剤などを添加する必要があるとしている。さらに、本発明者らが検討した結果、石炭焚きボイラ等からの排ガスのように亜硫酸ガス（以下、ＳＯ2 と呼ぶ）を多く含む場合、ＳＯ2 を除去するための脱硫装置（一般的に石灰石−石膏法）が設置されるが、脱硫装置内ではＳＯ2 を吸収した際には吸収液のｐＨが低下し、また吸収液温度が５０℃程度になるため、尿素が分解し易くなることがわかった。さらに、脱硫の吸収液中には排ガスなどから起因する多くの金属が溶解しているためキレート剤の効果が低くなり、脱硫装置内での水銀の除去は高い効率が期待できないことが判明した。
【０００６】
【発明が解決しようとする課題】
上記の従来技術では、高価な吸収液または固体吸収剤の消費量が多いばかりでなく、吸収液または固体吸収剤を排ガス中に噴霧する装置および反応器が必要になり、その設置スペースを確保する必要がある。さらに、設置スペースの点から既設の発電所では実質的に適用が不可能であるという問題点がある。また、既設の発電所に適用可能な技術では充分な水銀除去率が期待できない。
本発明の課題は、これらの課題を解決し、経済的に既設の発電所に適用可能で、高い水銀除去率を得る排ガス中の水銀除去方法および装置を提案することにある。
【０００７】
【課題を解決するための手段】
上記課題を達成するため、本願で特許請求する発明は以下のとおりである。
（１）石炭類をボイラのような燃焼装置で燃焼する際、該石炭類に予め塩素化合物を添加して燃焼させ、次いで燃焼排ガスの温度を１５０℃以下に冷却した後、集塵装置で排ガス中のばい塵を除去、回収することを特徴とする石炭類の燃焼排ガス中の水銀除去方法。
（２）前記石炭類に添加する塩素化合物の量を塩素として７００ｍｇ／ｋｇ−石炭以下とすることを特徴とする（１）記載の石炭類の燃焼排ガス中の水銀除去方法。
（３）前記集塵装置の前流にガスガスヒータの熱回収部を設置することを特徴とする（１）または（２）記載の石炭類の燃焼排ガス中の水銀除去方法。
【０００８】
（４）石炭類に塩素化合物を予め添加する方法として、塩素化合物の水溶液を粉砕前の石炭類に添加することを特徴とする（１）ないし（３）のいずれかに記載の石炭類の燃焼排ガス中の水銀除去方法。
（５）集塵装置出口ガス中の水銀濃度を測定し、その測定値に基づいて石炭類に添加する塩素化合物の量を調整することを特徴とする（１）ないし（４）のいずれかに記載の石炭類の燃焼排ガス中の水銀除去方法。
【０００９】
（６）燃焼装置に供給される石炭類に塩素化合物を添加する手段と、後記の集塵装置入口のガス温度を１５０℃以下にする手段と、該石炭類を燃焼装置で燃焼した際に発生する排ガス中の粒子を除去する集塵装置とを備えたことを特徴とする石炭類の燃焼排ガス中の水銀除去装置。
（７）集塵装置の前流にガスガスヒータの熱回収部を設置したことを特徴とする（６）に記載の石炭類の燃焼排ガス中の水銀除去装置。
【００１０】
（８）塩素化合物の水溶液を粉砕前の石炭類に添加する手段を有することを特徴とする（６）または（７）に記載の石炭類の燃焼排ガス中の水銀除去装置。
（９）集塵装置出口ガス中の水銀濃度を測定する手段と、その測定値に基づいて石炭類に添加する塩素化合物の量を調整する手段とをさらに有することを特徴とする（６）ないし（８）のいずれかに記載の石炭類の燃焼排ガス中の水銀除去装置。
【００１２】
本発明で用いる塩素化合物としては、塩化ナトリウム、塩化カリウム、塩化カルシウム等の塩化物が代表的なものとして挙げられる。
【００１３】
【発明の実施の形態】
以下、本発明を下記の実施例を示す図面によりさらに詳細に説明するが、本発明はこれらの例で制限されるものではない。
図１は、本発明の一実施例を示す排ガス中の水銀除去方法のフロー図である。石炭供給管１からボイラ２に供給される石炭Ａにライン３から塩素化合物として塩化カルシウムＢが添加され、ボイラ２で燃焼された後、灰粒子などのばい塵Ｃを含む排出される排ガスＤは、脱硝装置４、Ａ／Ｈ５およびＧＧＨの熱回収部６を経由してＥＰ７に導かれ、排ガス中のばい塵Ｃが除去される。その際に、排ガスの水銀の一部がばい塵表面に付着し、ＥＰ７によりばい塵Ｃとともに回収される。ＥＰ７で除去されなかったばい塵を含む排ガスは脱硫装置８に導入され、排ガス中のＳＯ2 が除去される。さらに、脱硫装置８から排出された排ガスはＧＧＨの再加熱部９では排ガス温度を高められ、煙突１０から排出される。石炭に添加する塩素カルシウムＢの量は、ＥＰ７出口ガス中の水銀濃度を水銀計測装置１１で測定し、その測定値に基づいて調整される。
【００１４】
図２は、図１に示した実施例での塩化カルシウム添加装置の詳細を示す。タンク２１に蓄えれらた塩化カルシウムＢ溶液はライン２２を通じてポンプ２３により、バンカ２４から石炭定量供給機２５により粗粉砕機２６に送られる途中の石炭Ａに添加される。粗粉砕機２６から石炭供給管２７を通じてバンカ２８に送られた石炭Ａは、石炭定量供給機２９により微粉砕機３０に送られて所定の粒度に微粉砕された後、石炭供給管３１からボイラ２のバーナ（図示せず）に送られて燃焼される。塩化カルシウムの添加量は、水銀計測装置１１で測定されたＥＰ７出口ガス中の水銀濃度測定値およびその設定濃度に基づいて、演算器３２によりその最適添加量が計算され、ポンプ２３から供給される塩化カルシウムＢ溶液の流量が調整される。
【００１５】
図３には、石炭の性状やＥＰ入口での排ガス温度など他の条件が一定で、石炭中の塩素濃度がＥＰでの水銀の除去率（ＥＰ入口排ガスＤ中に含まれていた水銀のうち、ばい塵Ｃとともに回収された水銀の割合、以下同様）に及ぼす影響を示す。石炭中の塩素濃度が高くなるほど水銀の除去率が高まり、塩素として７００mg／kg−石炭以上でほぼ一定となった。
【００１６】
また、石炭中の塩素濃度が一定で、ＥＰ入口での排ガス温度がＥＰでの水銀の除去率に及ぼす影響を図４に示す。石炭中の塩素濃度が高くても、ＥＰ入口での排ガス温度が１５０℃以上になると水銀の除去率はきわめて低くなるので、ＥＰ入口での排ガス温度としては１５０℃以下（好ましくは１００℃以下）にする必要がある。ＥＰ入口での排ガス温度を調整する具体的な手段の一例としては、図１に示した実施例のようにＥＰ前にＧＧＨの熱回収部を設置し、その運転条件を適切にすることにより達成できる。
【００１７】
塩素化合物添加の効果が飽和になる塩素化合物添加量は石炭の性状や水銀含有量、排ガス温度などによっても影響されるので、ＥＰ７出口ガス中の水銀濃度を水銀計測装置１１で測定し、その測定値に基づいて石炭に添加する塩化カルシウムＢの量を調整することが好ましい。具体的には、ＥＰ７出口ガス中の水銀濃度が目標とする濃度より高い場合には塩化カルシウムＢの添加量を増加させるが、必要以上に塩化カルシウムを添加することは経済的でないばかりでなく、ＥＰや脱硫装置などの金属材料の腐食の原因となるので注意する必要がある。このためＥＰ７出口ガス中の水銀濃度を測定し、塩化カルシウムＢの添加量を調整することは有効である。
【００１８】
図５は、図２に示した実施例で石炭中に塩素化合物を添加する代わりに、排ガス中に塩素化合物を水溶液の状態で添加する方法の装置構成を示す図である。石炭供給管１からボイラ２に供給される石炭Ａとは別に、ライン１２から塩化カルシウムＢが水溶液としてボイラ内に噴霧され、灰粒子などのばい塵Ｃを含む排出される排ガスＤは、脱硝装置４、Ａ／Ｈ５およびＧＧＨの熱回収部６を経由してＥＰ７に導かれ、排ガス中のばい塵Ｃが除去される。その際に、排ガス中の水銀の一分がばい塵表面に付着し、ＥＰ７によりばい塵Ｃとともに回収される。ＥＰ７で除去されなかったばい塵を含む排ガスは脱硫装置８に導入され、排ガス中のＳＯ2 が除去される。さらに、脱硫装置８から排出された排ガスは、ＧＧＨの再加熱部９で排ガス温度を高められた後、煙突１０から排出される。本実施例ではボイラ内に塩化カルシウム水溶液を噴霧するため、噴霧用のノズルがあればよく、従来技術のような吸収液または固体吸収剤と排ガスとをある程度の時間接触させるための反応器は必要としないという利点がある。
【００１９】
上記の実施例では塩素化合物として塩化カルシウムを用いているが、塩化ナトリウムなど他の塩化物でもかまわない。また、上記実施例では塩化カルシウムの水溶液を用いているが、粉体で石炭に添加したり、ボイラ以外の排ガスライン等で排ガス中に添加することも可能である。しかし、塩化カルシウムは潮解性で空気中の水分を吸収し易いので、水溶液として使用したほうが取扱いが容易である。
上記の実施例で用いている水銀計測装置は、ガス中の水銀濃度を測定できるものであれば、どのような原理の測定装置でも使用可能である。
【００２０】
【発明の効果】
本発明によれば、既設のボイラ等の燃焼装置にも適用可能で、設置スペースが少なくてすむ、高効率の排ガス中の水銀除去方法および装置を提供することができる。
【図面の簡単な説明】
【図１】本発明による実施例の排煙処理システムのフローを示す図。
【図２】本実施例の装置の詳細フローを示す図。
【図３】本発明法に関する実験データを示す図。
【図４】本発明法に関する実験データを示す図。
【図５】本発明による実施例の排煙処理システムのフローを示す図。
【図６】従来技術に基づく排煙処理システムのフローを示す図。
【符号の説明】
１…石炭供給管、２…ボイラ、３…ライン、４…脱硝装置、５…Ａ／Ｈ（エアヒータ）、６…ＧＧＨ（ガスガスヒータ）熱回収部、７…ＥＰ（電気集塵装置）、８…脱硫装置、９…ＧＧＨ再加熱部、１０…煙突、１１…水銀計測装置、１２…ライン、１３…水銀除去装置、１４…ライン、２１…タンク、２２…ライン、２３…ポンプ、２４…バンカ、２５…石炭定量供給機、２６…粗粉砕機、２７…石炭供給管、２８…バンカ、２９…石炭定量供給機、３０…微粉砕機、３１…石炭供給管、３２…演算器。
Ａ…石炭、Ｂ…塩化カルシウム、Ｃ…ばい塵、Ｄ…排ガス、Ｅ…吸収剤。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for removing mercury in combustion exhaust gas of coals, and more particularly to a method and apparatus for efficiently removing mercury contained in exhaust gas discharged from a combustion apparatus such as a boiler.
[0002]
[Prior art]
In thermal power plants, etc., mercury in flue gas (mainly present as metallic mercury or mercury chloride in flue gas) generated by combustion of fossil fuels such as coal is not high in content, but its toxicity is strong Therefore, the spread of processing technology is desired. As a method for removing mercury in exhaust gas, mercury treatment in exhaust gas discharged from a waste incinerator has been actively studied (Japanese Patent Publication Nos. 6-61424 and 6-104182). This is because the exhaust gas from the waste incinerator contains a higher concentration of mercury. In Japanese Patent Publication Nos. 6-61424 and 6-104182, an absorbing liquid or a solid absorbent is sprayed into exhaust gas, mercury in the exhaust gas is collected in the agent, and mercury is collected together with dust in the exhaust gas. A method is disclosed in which the collected product is collected by a dust collector such as a downstream bug or an electric dust collector.
FIG. 6 shows an example of a flue gas treatment system that sprays such solid absorbent into exhaust gas at a coal-fired thermal power plant to remove mercury in the exhaust gas.
[0003]
The exhaust gas D discharged from the boiler 2 is guided to the mercury removal device 13 via the denitration device 4, the A / H (air heater, the same applies below) 5 and the heat recovery unit 6 of the GGH (gas gas heater, the same applies below), Therefore, the solid absorbent E supplied from the line 14 is sprayed. The adsorbent containing mercury in the exhaust gas is guided to the downstream EP (electric dust collector, the same applies hereinafter) 7 together with the dust, and the absorbent containing mercury is removed together with the dust in the exhaust gas. Exhaust gas containing dust that has not been removed in EP 7 is introduced into the desulfurization device 8, SO 2 in the exhaust gas is removed, and the exhaust gas discharged from the desulfurization device 8 is increased in exhaust gas temperature by the GGH reheating unit 9. After that, it is discharged from the chimney 10.
[0004]
However, such a conventional technique requires a device for spraying the absorbing liquid or solid absorbent into the exhaust gas and a reactor for contacting the absorbing liquid or solid absorbent with the exhaust gas for a certain period of time (usually several seconds). It is necessary to secure the installation space. Further, it goes without saying that a relatively expensive absorbent or solid absorbent is consumed. When constructing a new power plant, it is sufficient to secure the necessary space in advance, but a device and a reactor for spraying such absorbing liquid or solid absorbent into the exhaust gas will be additionally installed in the existing power plant. It is virtually impossible to do.
[0005]
As a method applicable to the existing plant, in a waste incinerator, a chlorine compound is added to the waste to be supplied (Japanese Patent Publication No. 62-47572), and in Japanese Patent Publication No. 62-47572, it is supplied to the waste incinerator. There is known a method (Japanese Examined Patent Publication No. 62-47572) in which a chlorine compound is added to waste and washed with washing water in a downstream washing apparatus to collect and collect mercury in exhaust gas. In the technique disclosed in Japanese Examined Patent Publication No. 62-47572, mercury cannot be removed by a dust collector, and it is necessary to add urea or a chelating agent in order to efficiently remove with washing water. Yes. Further, as a result of the study by the present inventors, when a large amount of sulfurous acid gas (hereinafter referred to as SO 2 ) is contained as in the exhaust gas from a coal-fired boiler or the like, a desulfurization apparatus (generally limestone) for removing SO 2 -Gypsum method) is installed, but when SO 2 is absorbed in the desulfurization apparatus, the pH of the absorbing solution is lowered, and the temperature of the absorbing solution is about 50 ° C, so that urea is easily decomposed. all right. Furthermore, since many metals derived from exhaust gas and the like are dissolved in the desulfurization absorbing solution, the effect of the chelating agent is reduced, and it has been found that high efficiency cannot be expected for removing mercury in the desulfurization apparatus.
[0006]
[Problems to be solved by the invention]
The above-described conventional technology not only consumes a large amount of expensive absorption liquid or solid absorbent, but also requires an apparatus and a reactor for spraying the absorption liquid or solid absorbent into the exhaust gas, thereby securing the installation space. There is a need. Furthermore, there is a problem that it cannot be applied to existing power plants in terms of installation space. In addition, sufficient mercury removal rate cannot be expected with technology applicable to existing power plants.
An object of the present invention is to propose a method and apparatus for removing mercury in exhaust gas that solves these problems and is economically applicable to existing power plants and obtains a high mercury removal rate.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the invention claimed in the present application is as follows.
(1) When coal is burned in a combustion device such as a boiler, a chlorine compound is added to the coal in advance and burned, and then the temperature of the combustion exhaust gas is cooled to 150 ° C. or lower and then exhausted with a dust collector. A method for removing mercury in combustion exhaust gas of coals, characterized by removing and collecting the dust in it.
(2) The method for removing mercury from the combustion exhaust gas of coal according to (1), wherein the amount of chlorine compound added to the coal is 700 mg / kg-coal or less as chlorine .
(3) The method for removing mercury in combustion exhaust gas of coal according to (1) or (2), wherein a heat recovery part of a gas gas heater is installed upstream of the dust collector.
[0008]
(4) Combustion of coal according to any one of (1) to (3), wherein a chlorine compound aqueous solution is added to the coal before pulverization as a method of previously adding the chlorine compound to the coal. Mercury removal method in exhaust gas.
(5) The mercury concentration in the dust collector outlet gas is measured, and the amount of chlorine compound added to the coals is adjusted based on the measured value. mercury removal how the combustion exhaust gas of coal acids according.
[0009]
( 6) Means for adding a chlorine compound to coal supplied to the combustion device, means for setting the gas temperature at the dust collector inlet described later to 150 ° C. or less, and generated when the coal is burned by the combustion device An apparatus for removing mercury in combustion exhaust gas of coal, comprising a dust collector for removing particles in the exhaust gas.
( 7) The apparatus for removing mercury in the combustion exhaust gas of coal according to ( 6), wherein a heat recovery part of a gas gas heater is installed in the upstream of the dust collector.
[0010]
( 8) The apparatus for removing mercury in combustion exhaust gas of coal according to ( 6) or (7) , characterized by comprising means for adding an aqueous solution of a chlorine compound to coal before pulverization.
( 9) It further has means for measuring the mercury concentration in the dust collector outlet gas, and means for adjusting the amount of chlorine compound added to the coals based on the measured value ( 6) to (8) The mercury removal apparatus in the combustion exhaust gas of coal in any one of.
[0012]
Typical examples of the chlorine compound used in the present invention include chlorides such as sodium chloride, potassium chloride, and calcium chloride.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail with reference to the drawings illustrating the following examples, but the present invention is not limited to these examples.
FIG. 1 is a flowchart of a method for removing mercury in exhaust gas according to an embodiment of the present invention. After the calcium chloride B is added as a chlorine compound from the line 3 to the coal A supplied to the boiler 2 from the coal supply pipe 1 and burned in the boiler 2, the exhaust gas D containing dust C such as ash particles is discharged. Then, the denitration device 4, the A / H 5 and the GGH heat recovery section 6 lead to the EP 7 to remove the dust C in the exhaust gas. At that time, a part of the mercury of the exhaust gas adheres to the dust surface and is collected together with the dust C by EP7. The exhaust gas containing the dust that has not been removed in EP7 is introduced into the desulfurizer 8, and SO 2 in the exhaust gas is removed. Further, the exhaust gas discharged from the desulfurization device 8 is increased in exhaust gas temperature in the GGH reheating unit 9 and discharged from the chimney 10. The amount of calcium chloride B added to the coal is adjusted based on the measured value of the mercury concentration in the EP7 outlet gas measured by the mercury measuring device 11.
[0014]
FIG. 2 shows the details of the apparatus for adding calcium chloride in the embodiment shown in FIG. The calcium chloride B solution stored in the tank 21 is added to the coal A in the middle of being sent from the bunker 24 to the coarse pulverizer 26 by the coal fixed amount feeder 25 by the pump 23 through the line 22. Coal A sent from the coarse pulverizer 26 to the bunker 28 through the coal supply pipe 27 is sent to the fine pulverizer 30 by the coal quantitative supply machine 29 and pulverized to a predetermined particle size, and then from the coal supply pipe 31 to the boiler. It is sent to two burners (not shown) and burned. As for the addition amount of calcium chloride, the optimum addition amount is calculated by the calculator 32 based on the measured mercury concentration value in the EP7 outlet gas measured by the mercury measuring device 11 and its set concentration, and supplied from the pump 23. The flow rate of the calcium chloride B solution is adjusted.
[0015]
In FIG. 3, the other conditions such as the properties of coal and exhaust gas temperature at the EP inlet are constant, and the chlorine concentration in the coal is the mercury removal rate at the EP (of the mercury contained in the exhaust gas D at the EP inlet). , The ratio of mercury recovered together with dust C, the same applies hereinafter). The higher the chlorine concentration in the coal, the higher the mercury removal rate, and the chlorine content became almost constant at 700 mg / kg-coal or higher.
[0016]
Further, FIG. 4 shows the influence of the exhaust gas temperature at the EP inlet on the mercury removal rate at the EP when the chlorine concentration in the coal is constant. Even if the chlorine concentration in coal is high, if the exhaust gas temperature at the EP inlet becomes 150 ° C or higher, the mercury removal rate becomes extremely low. Therefore, the exhaust gas temperature at the EP inlet is 150 ° C or lower (preferably 100 ° C or lower). It is necessary to. As an example of specific means for adjusting the exhaust gas temperature at the EP inlet, it is achieved by installing a GGH heat recovery unit before the EP and making the operating conditions appropriate as in the embodiment shown in FIG. it can.
[0017]
The amount of chlorine compound added to saturate the effect of adding the chlorine compound is also affected by the properties of the coal, mercury content, exhaust gas temperature, etc., so the mercury concentration in the EP7 outlet gas is measured with the mercury measuring device 11 and measured. It is preferable to adjust the amount of calcium chloride B added to the coal based on the value. Specifically, when the mercury concentration in the EP7 outlet gas is higher than the target concentration, the amount of calcium chloride B added is increased. However, adding calcium chloride more than necessary is not economical, Care must be taken because it causes corrosion of metal materials such as EP and desulfurization equipment. Therefore, it is effective to measure the mercury concentration in the EP7 outlet gas and adjust the amount of calcium chloride B added.
[0018]
FIG. 5 is a diagram showing an apparatus configuration of a method of adding a chlorine compound to an exhaust gas in an aqueous solution state instead of adding a chlorine compound to coal in the embodiment shown in FIG. Separately from coal A supplied to the boiler 2 from the coal supply pipe 1, calcium chloride B is sprayed into the boiler as an aqueous solution from the line 12, and the exhaust gas D containing dust C such as ash particles is removed from the denitration device. 4, A / H5 and GGH are led to EP7 via heat recovery section 6 to remove dust C in the exhaust gas. At that time, a part of mercury in the exhaust gas adheres to the dust surface and is collected together with dust C by EP7. The exhaust gas containing the dust that has not been removed in EP7 is introduced into the desulfurizer 8, and SO 2 in the exhaust gas is removed. Further, the exhaust gas discharged from the desulfurization device 8 is discharged from the chimney 10 after the exhaust gas temperature is raised by the GGH reheating unit 9. In this embodiment, since an aqueous solution of calcium chloride is sprayed into the boiler, it is only necessary to have a nozzle for spraying, and a reactor for bringing the absorbing liquid or solid absorbent and the exhaust gas into contact with each other for a certain period of time is required. There is an advantage of not.
[0019]
In the above embodiment, calcium chloride is used as the chlorine compound, but other chlorides such as sodium chloride may be used. Moreover, although the aqueous solution of calcium chloride is used in the said Example, it can also be added to coal by powder, or can be added to exhaust gas by exhaust gas lines other than a boiler. However, since calcium chloride is deliquescent and easily absorbs moisture in the air, it is easier to handle when used as an aqueous solution.
The mercury measuring device used in the above embodiment can be any measuring device that can measure the mercury concentration in the gas.
[0020]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, it can apply also to combustion apparatuses, such as an existing boiler, and can provide the highly efficient mercury removal method and apparatus in waste gas which requires little installation space.
[Brief description of the drawings]
FIG. 1 is a diagram showing a flow of a flue gas treatment system according to an embodiment of the present invention.
FIG. 2 is a diagram showing a detailed flow of the apparatus according to the present embodiment.
FIG. 3 is a diagram showing experimental data related to the method of the present invention.
FIG. 4 is a diagram showing experimental data related to the method of the present invention.
FIG. 5 is a diagram showing a flow of a smoke emission treatment system according to an embodiment of the present invention.
FIG. 6 is a diagram showing a flow of a flue gas treatment system based on a conventional technique.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Coal supply pipe, 2 ... Boiler, 3 ... Line, 4 ... Denitration apparatus, 5 ... A / H (air heater), 6 ... GGH (gas gas heater) heat recovery part, 7 ... EP (electric dust collector), 8 DESCRIPTION OF SYMBOLS ... Desulfurization device, 9 ... GGH reheating part, 10 ... Chimney, 11 ... Mercury measuring device, 12 ... Line, 13 ... Mercury removal device, 14 ... Line, 21 ... Tank, 22 ... Line, 23 ... Pump, 24 ... Bunker 25 ... Coal meter supply machine, 26 ... Coarse grinder, 27 ... Coal feed pipe, 28 ... Bunker, 29 ... Coal meter feeder, 30 ... Fine mill, 31 ... Coal feed pipe, 32 ... Calculator.
A ... coal, B ... calcium chloride, C ... dust, D ... exhaust gas, E ... absorbent.

Claims (9)

石炭類をボイラのような燃焼装置で燃焼する際、該石炭類に予め塩素化合物を添加して燃焼させ、次いで燃焼排ガスの温度を１５０℃以下に冷却した後、集塵装置で排ガス中のばい塵を除去、回収することを特徴とする石炭類の燃焼排ガス中の水銀除去方法。When combusting coal with a combustion device such as a boiler, a chlorine compound is added to the coal in advance and burned, and then the temperature of the combustion exhaust gas is cooled to 150 ° C. or lower, and then the dust in the exhaust gas is collected with a dust collector. A method for removing mercury from combustion exhaust gas of coal, characterized by removing and collecting dust. 前記石炭類に添加する塩素化合物の量を塩素として７００ｍｇ／ｋｇ−石炭以下とすることを特徴とする請求項１記載の石炭類の燃焼排ガス中の水銀除去方法。 The method for removing mercury in combustion exhaust gas of coal according to claim 1, wherein the amount of chlorine compound added to the coal is not more than 700 mg / kg-coal as chlorine . 前記集塵装置の前流にガスガスヒータの熱回収部を設置することを特徴とする請求項１または２記載の石炭類の燃焼排ガス中の水銀除去方法。  The method for removing mercury in the combustion exhaust gas of coals according to claim 1 or 2, wherein a heat recovery part of a gas gas heater is installed upstream of the dust collector. 石炭類に塩素化合物を予め添加する方法として、塩素化合物の水溶液を粉砕前の石炭類に添加することを特徴とする請求項１ないし３のいずれかに記載の石炭類の燃焼排ガス中の水銀除去方法。  The mercury removal from the combustion exhaust gas of coal according to any one of claims 1 to 3, wherein an aqueous solution of the chlorine compound is added to the coal before pulverization as a method of previously adding the chlorine compound to the coal. Method. 集塵装置出口ガス中の水銀濃度を測定し、その測定値に基づいて石炭類に添加する塩素化合物の量を調整することを特徴とする請求項１ないし４のいずれかに記載の石炭類の燃焼排ガス中の水銀除去方法。  The mercury concentration in the dust collector outlet gas is measured, and the amount of chlorine compound added to the coal is adjusted based on the measured value. Mercury removal method from combustion exhaust gas. 燃焼装置に供給される石炭類に塩素化合物を添加する手段と、後記の集塵装置入口のガス温度を１５０℃以下にする手段と、該石炭類を燃焼装置で燃焼した際に発生する排ガス中の粒子を除去する集塵装置とを備えたことを特徴とする石炭類の燃焼排ガス中の水銀除去装置。Means for adding a chlorine compound to coal supplied to the combustion device, means for lowering the gas temperature at the inlet of the dust collector described later to 150 ° C. or less, and in exhaust gas generated when the coal is burned by the combustion device A device for removing mercury in combustion exhaust gas of coals, characterized by comprising a dust collector for removing particles of coal. 集塵装置の前流にガスガスヒータの熱回収部を設置したことを特徴とする請求項６に記載の石炭類の燃焼排ガス中の水銀除去装置。The apparatus for removing mercury in combustion exhaust gas of coals according to claim 6, wherein a heat recovery part of a gas gas heater is installed upstream of the dust collector. 塩素化合物の水溶液を粉砕前の石炭類に添加する手段を有することを特徴とする請求項６または７に記載の石炭類の燃焼排ガス中の水銀除去装置。The apparatus for removing mercury in combustion exhaust gas of coal according to claim 6 or 7 , further comprising means for adding an aqueous solution of a chlorine compound to the coal before pulverization. 集塵装置出口ガス中の水銀濃度を測定する手段と、その測定値に基づいて石炭類に添加する塩素化合物の量を調整する手段とをさらに有することを特徴とする請求項６ないし８のいずれかに記載の石炭類の燃焼排ガス中の水銀除去装置。9. The method according to claim 6 , further comprising means for measuring the mercury concentration in the dust collector outlet gas and means for adjusting the amount of chlorine compound added to the coals based on the measured value. An apparatus for removing mercury in combustion exhaust gas of coal according to any one of the above.
JP13807999A 1999-05-19 1999-05-19 Method and apparatus for removing mercury from coal flue gas Expired - Lifetime JP3698916B2 (en)

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