JP2011112243A - Method of suppressing differential pressure for air preheater - Google Patents

Method of suppressing differential pressure for air preheater Download PDF

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JP2011112243A
JP2011112243A JP2009267199A JP2009267199A JP2011112243A JP 2011112243 A JP2011112243 A JP 2011112243A JP 2009267199 A JP2009267199 A JP 2009267199A JP 2009267199 A JP2009267199 A JP 2009267199A JP 2011112243 A JP2011112243 A JP 2011112243A
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coal
air preheater
differential pressure
exhaust gas
cao
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Hiroharu Hayami
宏治 速水
Yasuhito Machii
泰人 待井
Takashi Nagao
隆司 長尾
Ryoji Morooka
良司 諸岡
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Chubu Electric Power Co Inc
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Chubu Electric Power Co Inc
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    • 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
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00—Combustion technologies with mitigation potential
    • Y02E20/34—Indirect CO2mitigation, i.e. by acting on non CO2directly related matters of the process, e.g. pre-heating or heat recovery

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of easily and effectively suppressing differential pressure of an air preheater in a thermal power plant. <P>SOLUTION: The thermal power plant P includes a boiler 1 for burning a fuel including coal, and exhaust gas treatment equipment 20 for treating a combustion exhaust gas discharged from the boiler 1. The exhaust gas treatment equipment 20 includes a flue-gas denitration device 21 for removing nitrogen oxide included in the combustion exhaust gas, and the air preheater 22 disposed at a lower stage of the flue-gas denitration device 21 for exchanging heat between the combustion exhaust gas and the air supplied to the boiler 1. In the thermal power plant P, coal or a coal mixture in which a ratio (CaO/S) of a content rate of calcium oxide to a content rate of the total sulfur content is 3.0 or more, is used as the fuel. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、火力発電所における空気予熱器の差圧抑制方法に関する。   The present invention relates to a method for suppressing differential pressure of an air preheater in a thermal power plant.

石炭を燃料とする火力発電所において、ボイラにて発生する燃焼排ガスは、排煙脱硝装置、空気予熱器、乾式集塵装置、排煙脱硫装置、湿式集塵装置による処理を経て煙突から排出されることが一般的である。   In a thermal power plant that uses coal as fuel, flue gas generated in a boiler is discharged from the chimney through treatment by a flue gas denitrifier, air preheater, dry dust collector, flue gas desulfurizer, and wet dust collector. In general.

ここで、空気予熱器は、ボイラに供給される燃焼用空気と燃焼装置から排出される高温の排ガスとの熱交換によって、燃焼用空気の予熱を行うものであって、回転再生式と称されるものが一般に用いられる。このものは、常温の燃焼用空気が流れる流路と高温の燃焼排ガスが流れる流路とが設けられているハウジング内に、蓄熱式エレメントが回転可能に収納された構成をなしている。そして、高温の燃焼排ガスの熱がエレメントに一旦蓄熱され、この熱がエレメントの回転に伴って燃焼用空気に伝達されることで熱交換が行われる。   Here, the air preheater preheats the combustion air by exchanging heat between the combustion air supplied to the boiler and the high-temperature exhaust gas discharged from the combustion device, and is called a rotary regeneration type. Is generally used. This has a configuration in which a regenerative element is rotatably accommodated in a housing provided with a flow path through which room-temperature combustion air flows and a flow path through which high-temperature combustion exhaust gas flows. The heat of the high-temperature combustion exhaust gas is temporarily stored in the element, and this heat is transferred to the combustion air as the element rotates, so that heat exchange is performed.

特開２０００−３００９４４号公報JP 2000-300904 A

このような空気予熱器においては、エレメントへの燃焼灰等の付着により目詰まりが発生し、入口ダクトと出口ダクトとの圧力差が増大することがある。このような差圧上昇はボイラ運転に支障を生じさせるため、改善が求められていた。   In such an air preheater, clogging may occur due to adhesion of combustion ash or the like to the element, and the pressure difference between the inlet duct and the outlet duct may increase. Such an increase in the differential pressure causes a problem in boiler operation, and hence improvement has been demanded.

本発明は上記のような事情に基づいて完成されたものであって、火力発電所における空気予熱器の差圧を簡易かつ効果的に抑制可能な方法を提供することを目的とする。   This invention is completed based on the above situations, Comprising: It aims at providing the method which can suppress the differential pressure | voltage of the air preheater in a thermal power plant simply and effectively.

本発明の空気予熱器の差圧抑制方法は、石炭を含む燃料を燃焼させるボイラと、前記ボイラから排出される燃焼排ガス中から窒素酸化物を除去するための排煙脱硝装置および前記排煙脱硝装置の下段に設けられて前記燃焼排ガスと前記ボイラへ供給される空気とを熱交換させるための空気予熱器を含む排ガス処理設備とを備える火力発電プラントにおいて、前記空気予熱器に前記燃焼排ガスを導入するガス側入口ダクトと前記空気予熱器から前記燃焼排ガスを排出するガス側出口ダクトとの差圧を抑制する方法であって、前記燃料として、全硫黄分の含有率に対する酸化カルシウム含有率の比率（ＣａＯ／Ｓ）が３．０以上である石炭または石炭混合物を用いるものである。   The method for suppressing a differential pressure of an air preheater according to the present invention includes a boiler for burning a fuel containing coal, a flue gas denitration device for removing nitrogen oxides from a flue gas discharged from the boiler, and the flue gas denitration In a thermal power plant provided at a lower stage of the apparatus and having an exhaust gas treatment facility including an air preheater for exchanging heat between the combustion exhaust gas and air supplied to the boiler, the combustion exhaust gas is supplied to the air preheater. A method for suppressing a differential pressure between a gas-side inlet duct to be introduced and a gas-side outlet duct that discharges the combustion exhaust gas from the air preheater, wherein the fuel has a calcium oxide content ratio relative to a total sulfur content ratio. Coal or a coal mixture having a ratio (CaO / S) of 3.0 or more is used.

本発明によれば、火力発電所における空気予熱器の差圧を簡易かつ効果的に抑制可能である。   ADVANTAGE OF THE INVENTION According to this invention, the differential pressure | voltage of the air preheater in a thermal power plant can be suppressed simply and effectively.

実施形態における火力発電プラントの概略図Schematic diagram of thermal power plant in the embodiment 実施形態における空気予熱器の概略図Schematic of the air preheater in the embodiment 実施例において、試験期間中における１号機の空気予熱器差圧および節炭機出口のＮＯｘ濃度の推移を表すチャートIn embodiments, chart showing a transition of the NO x concentration of 1 Unit air preheater differential pressure and economizer machine outlet of the test period 実施例において、試験期間中における２号機の空気予熱器差圧および節炭機出口のＮＯｘ濃度の推移を表すチャートIn embodiments, chart showing a transition of the NO x concentration of the second car air preheater differential pressure and economizer machine outlet of the test period 実施例において、試験期間中における４号機の空気予熱器差圧および節炭機出口のＮＯｘ濃度の推移を表すチャートIn embodiments, chart showing a transition of the NO x concentration of 4 Units air preheater differential pressure and economizer machine outlet of the test period 実施例において、試験期間中における５号機の空気予熱器差圧および節炭機出口のＮＯｘ濃度の推移を表すチャートIn embodiments, chart showing a transition of the NO x concentration of 5 Units air preheater differential pressure and economizer machine outlet of the test period 実施例において、スートブロワのオン／オフによる空気予熱器差圧の変動を示すチャートIn an Example, the chart which shows the fluctuation | variation of the air preheater differential pressure by ON / OFF of a soot blower

図１には、本発明を適用可能な火力発電プラントＰの概略図を示した。この火力発電プラントＰには、石炭を含む燃料を燃焼させるためのボイラ１が備えられている。ボイラ１には、貯炭場から運ばれてきた石炭を供給する石炭バンカ１０と、この石炭バンカ１０に貯蔵された石炭の供給量を調整しつつ供給する給炭機１１と、給炭機１１から供給された石炭を微細な粒度に粉砕してボイラ１へ供給する微粉炭器１２とが接続されている。   FIG. 1 shows a schematic diagram of a thermal power plant P to which the present invention can be applied. The thermal power plant P is provided with a boiler 1 for burning fuel containing coal. The boiler 1 includes a coal bunker 10 that supplies coal transported from the coal yard, a coal feeder 11 that supplies the coal bunker 10 while adjusting the amount of coal stored in the coal bunker 10, and a coal feeder 11. A pulverized coal unit 12 that pulverizes the supplied coal to a fine particle size and supplies the coal to the boiler 1 is connected.

ボイラ１は、内部で微粉炭を燃焼させる火炉２と、火炉２の側方に配され、上部で火炉２と連結される排ガス流路３とを有している。火炉２の上部および排ガス流路３には、過熱器の配管およびこの過熱器に接続される節炭器の配管が配置されている。そして、詳細には図示しないが、給水器から供給された水は、節炭器および過熱器の配管内部を順次通過する際に加熱され、最終的に蒸気となって図示しないタービンに供給される。   The boiler 1 has a furnace 2 that burns pulverized coal inside, and an exhaust gas passage 3 that is disposed on the side of the furnace 2 and connected to the furnace 2 at the top. In the upper part of the furnace 2 and the exhaust gas flow path 3, a superheater pipe and a economizer pipe connected to the superheater are arranged. Although not shown in detail, the water supplied from the water feeder is heated when sequentially passing through the pipes of the economizer and the superheater, and finally becomes steam and is supplied to a turbine (not shown). .

排ガス流路３の出口は、煙道４と称される筒状の配管によって煙突５に接続されており、この煙道４上には排ガス処理設備２０が配されている。排ガス処理設備２０は、排煙脱硝装置２１、空気予熱器２２、乾式集塵装置２３、排煙脱硫装置２４、湿式集塵装置２５が、ボイラ１に近い側からこの順で配置されたものである。ボイラ１から排出された燃焼排ガスは、まず、排煙脱硝装置２１に導入されて窒素酸化物が除去される。排煙脱硝装置２１から排出された燃焼排ガスは空気予熱器２２に導入され、ここでは、ボイラ燃焼用空気を予熱する代わりに燃焼排ガスを低温化する。空気予熱器２２を通過した燃焼排ガスは乾式集塵装置２３に導入されて煤塵が除去され、排煙脱硫装置２４によって硫黄酸化物が取り除かれ、湿式集塵装置２５により煤塵が除去された後、煙突５から排出される。   An outlet of the exhaust gas passage 3 is connected to the chimney 5 by a cylindrical pipe called a flue 4, and an exhaust gas treatment facility 20 is disposed on the flue 4. The exhaust gas treatment facility 20 includes a flue gas denitration device 21, an air preheater 22, a dry dust collector 23, a flue gas desulfurization device 24, and a wet dust collector 25 arranged in this order from the side close to the boiler 1. is there. The combustion exhaust gas discharged from the boiler 1 is first introduced into the flue gas denitration device 21 to remove nitrogen oxides. The combustion exhaust gas discharged from the flue gas denitration device 21 is introduced into the air preheater 22, where the combustion exhaust gas is cooled instead of preheating the boiler combustion air. The combustion exhaust gas that has passed through the air preheater 22 is introduced into a dry dust collector 23 to remove soot and dust, sulfur oxide is removed by the flue gas desulfurizer 24, and soot dust is removed by the wet dust collector 25, It is discharged from the chimney 5.

空気予熱器２２は、回転再生式と称されるものであって、内部にエレメント３５を収容するハウジング３０を備えている。ハウジング３０の上面には、ガス側入口ダクト３１および空気側出口ダクト３２が接続され、一方、ハウジング３０の下面においてガス側入口ダクト３１の下方位置にはガス側出口ダクト３３、空気側出口ダクト３２の下方位置には空気側入口ダクト３４がそれぞれ接続されている。空気側入口ダクト３４には押込送風機３６が接続され、空気側出口ダクト３２は火炉２に接続されている。またガス側入口ダクト３１およびガス側出口ダクト３３は、それぞれ煙道４において排煙脱硝装置２１の出口の下流側、および乾式集塵装置２３の入口の上流側に接続されている。ハウジング３０内に収容されるエレメント３５は、ハウジング３０に取り付けられている各ダクト３１、３２、３３、３４の軸方向に沿う方向（図２の上下方向；言い換えれば燃焼排ガスおよび燃焼用空気の流路方向に沿う方向）を軸方向として回転可能とされている。   The air preheater 22 is called a rotary regeneration type, and includes a housing 30 that houses an element 35 therein. A gas-side inlet duct 31 and an air-side outlet duct 32 are connected to the upper surface of the housing 30, while a gas-side outlet duct 33 and an air-side outlet duct 32 are positioned below the gas-side inlet duct 31 on the lower surface of the housing 30. Are respectively connected to air side inlet ducts 34. A pusher blower 36 is connected to the air side inlet duct 34, and the air side outlet duct 32 is connected to the furnace 2. Further, the gas side inlet duct 31 and the gas side outlet duct 33 are connected to the downstream side of the outlet of the flue gas denitration device 21 and the upstream side of the inlet of the dry dust collector 23 in the flue 4, respectively. The element 35 accommodated in the housing 30 is a direction along the axial direction of the ducts 31, 32, 33, 34 attached to the housing 30 (the vertical direction in FIG. 2; in other words, the flow of combustion exhaust gas and combustion air The direction along the road direction) can be rotated as an axial direction.

排煙脱硝装置２１から排出された燃焼排ガスは、ガス側入口ダクト３１からハウジング３０内に導入され、ガス側出口ダクト３２から排出されて乾式集塵装置２３へ送られる。一方、押込送風機３６により送り込まれた燃焼用空気は空気側入口ダクト３４からハウジング３０内に導入され、空気側出口ダクト３２にて火炉２に送られる。この際、ハウジング３０内の高温の燃焼排ガスがエレメント３５に接触することでエレメント３５に熱が一旦蓄熱される。そして、エレメント３５の回転に伴ってこのエレメント３５における熱を蓄積した部分が燃焼用空気の流路内に入り、燃焼用空気に接触することで、熱が燃焼用空気に伝達される。   The combustion exhaust gas discharged from the flue gas denitration device 21 is introduced into the housing 30 from the gas side inlet duct 31, discharged from the gas side outlet duct 32, and sent to the dry dust collector 23. On the other hand, the combustion air sent by the forced air blower 36 is introduced into the housing 30 from the air side inlet duct 34 and sent to the furnace 2 through the air side outlet duct 32. At this time, the high-temperature combustion exhaust gas in the housing 30 comes into contact with the element 35, whereby heat is temporarily stored in the element 35. And the part which accumulated the heat in this element 35 enters in the flow path of combustion air with rotation of element 35, and heat is transmitted to combustion air by contacting with combustion air.

排煙脱硝装置２１による脱硝は接触アンモニア還元法によって行われる。すなわち、燃焼排ガスの流路中に還元剤としてのアンモニアを注入して燃焼排ガスと混合し、この混合ガスを排煙脱硝装置２１内で触媒と接触させることにより、排ガス中のＮＯｘをＮ２とＨ２Ｏに還元している。このような方法を採用する場合、脱硝反応に使用されなかった未反応アンモニアが燃焼排ガス中に多量に残留すると、まず燃焼排ガス中のＳＯ３と水とが反応して硫酸を生成し、この硫酸とアンモニアとが反応して硫酸水素アンモニウムを生成する。硫酸水素アンモニウムは１５０℃〜２３０℃で粘着性流体となる性質を持つため、空気予熱器２２のエレメント３５（特に中温層エレメント）に付着し、詰まりを生じさせる。この詰まりにより、ガス側入口ダクト３１とガス側出口ダクト３３との圧力差（差圧）が上昇するものと考えられる。 Denitration by the flue gas denitration device 21 is performed by a catalytic ammonia reduction method. That is, ammonia as a reducing agent is injected into the flue gas flow path and mixed with the flue gas, and this mixed gas is brought into contact with the catalyst in the flue gas denitration device 21, thereby reducing NO x in the flue gas to N 2. And H 2 O. When such a method is employed, if a large amount of unreacted ammonia that has not been used in the denitration reaction remains in the combustion exhaust gas, SO 3 in the combustion exhaust gas first reacts with water to produce sulfuric acid. And ammonia react to produce ammonium hydrogen sulfate. Since ammonium hydrogen sulfate has the property of becoming an adhesive fluid at 150 ° C. to 230 ° C., it adheres to the element 35 (especially the middle temperature layer element) of the air preheater 22 and causes clogging. This clogging is considered to increase the pressure difference (differential pressure) between the gas side inlet duct 31 and the gas side outlet duct 33.

そこで、本発明では、燃料である石炭中に、全硫黄分に対して一定量以上のＣａＯが含まれるようにした。このようにすれば、燃焼排ガス中において、硫黄分（特に硫酸水素アンモニウムの発生源となるＳＯ３）の量に対して一定量以上のＣａＯが含まれることとなる。すると、まず燃焼排ガス中のＳＯ３と水とが反応して硫酸を生成し、この硫酸とＣａＯと水蒸気とが反応して二水石膏（ＣａＳＯ４・２Ｈ２Ｏ）を生成する。この二水石膏は結晶性粉体（さらさらした粉体）であるため空気予熱器２２のエレメント３５への付着が起こりにくい。また、仮に付着が生じたとしても、スートブロワ等による除灰が硫酸水素アンモニウム付着の場合と比べて極めて容易である。さらに、この反応により燃焼排ガス中のＳＯ３が消費されるから、硫酸水素アンモニウムの生成が抑制される。これにより、差圧上昇を抑制することができる。 Therefore, in the present invention, coal, which is a fuel, contains a certain amount or more of CaO with respect to the total sulfur content. In this way, the combustion exhaust gas contains a certain amount or more of CaO with respect to the amount of sulfur content (especially SO 3 that is a source of ammonium hydrogen sulfate). Then, SO 3 in the combustion exhaust gas reacts with water to produce sulfuric acid, and this sulfuric acid, CaO, and water vapor react to produce dihydrate gypsum (CaSO 4 .2H 2 O). Since this dihydrate gypsum is a crystalline powder (free flowing powder), adhesion to the element 35 of the air preheater 22 hardly occurs. Even if adhesion occurs, ash removal by a soot blower or the like is extremely easy as compared to the case of ammonium hydrogen sulfate adhesion. Furthermore, since SO 3 in the combustion exhaust gas is consumed by this reaction, the production of ammonium hydrogen sulfate is suppressed. Thereby, an increase in differential pressure can be suppressed.

なお、「石炭または石炭混合物」とは、単一の銘柄の石炭であってもよく、ＣａＯ含有量の高い石炭を他の銘柄の石炭と混合してＣａＯ／Ｓが３．０以上となるように調整したものであってもよく、石炭（単一の銘柄の石炭でも、２種以上の銘柄の石炭混合物であってもよい）にＣａＯを添加してＣａＯ／Ｓが３．０以上となるように調整したものであってもよい、との意である。
特に、ＣａＯ含有量の高い石炭として、豪州産のニューランズ炭を使用することができる。
また、石炭にＣａＯを添加してＣａＯ／Ｓが３．０以上となるように調整する場合、ＣａＯの添加のためのＣａＯ供給路を給炭機１１または微粉炭器１２に接続すればよい。 The “coal or coal mixture” may be a single brand of coal, and coal of high CaO content is mixed with other brands of coal so that the CaO / S becomes 3.0 or more. It is possible to adjust to CaO / S by adding CaO to coal (which may be a single brand of coal or a mixture of two or more brands of coal). It may mean that it may be adjusted as described above.
In particular, Australian Newlands coal can be used as coal with a high CaO content.
Moreover, what is necessary is just to connect the CaO supply path for addition of CaO to the coal feeder 11 or the pulverizer 12 when adding CaO to coal and adjusting so that CaO / S may be 3.0 or more.

[空気予熱器差圧と石炭性状の相関分析]
中部電力碧南火力発電所において、空気予熱器差圧と石炭性状の相関を分析した。試験期間は、１号機においては平成１９年６月２９日〜１２月３１日、２号機においては平成１９年８月１６日〜１２月２７日、４号機においては平成１９年５月１３日〜９月９日、５号機においては平成１９年６月２４日〜１２月２３日とした。 [Correlation analysis of air preheater differential pressure and coal properties]
At Chubu Electric Power Shonan Thermal Power Station, the correlation between air preheater differential pressure and coal properties was analyzed. The test period is from June 29 to December 31, 2007 for Unit 1, August 16 to December 27, 2007 for Unit 2, and May 13, 2007 for Unit 4. On September 9th, it was set as June 24 to December 23, 2007 for Unit 5.

一定期間ごとにボイラに投入される石炭のサンプルを採取し、全硫黄の含有率を元素分析法、ＣａＯの含有率を原子吸光法にて測定した。また、空気予熱器のガス側入口ダクトとガス側出口ダクトに電子式差圧計を設置し、差圧を測定した。
併せて、節炭機出口から排ガスサンプルを採取し、ＮＯｘ分析計（赤外線吸収法）にてＮＯｘ濃度を計測した。 Samples of coal that were put into the boiler at regular intervals were collected, and the total sulfur content was measured by elemental analysis, and the CaO content was measured by atomic absorption. In addition, an electronic differential pressure gauge was installed in the gas side inlet duct and the gas side outlet duct of the air preheater to measure the differential pressure.
In addition, an exhaust gas sample was collected from the outlet of the economizer and the NO x concentration was measured with a NO x analyzer (infrared absorption method).

図３には、１号機において空気予熱器差圧、および節炭機出口のＮＯｘ濃度の推移を表すチャートを示した。なお、空気予熱器および節炭機はそれぞれ２系統（系統Ａ、系統Ｂ）存在するため、各系統について示した。また、表１〜３には、１号機における試料採取日、使用した石炭の銘柄、空気予熱器（ＡＨ）差圧（単位：ｍｍＡｑ）、燃料中のＣａＯ／Ｓ、ＣａＯ（単位：質量％）、全硫黄Ｓ（単位：質量％）、節炭機出口のＮＯｘ濃度（単位：ｐｐｍ）をそれぞれ示した。 FIG. 3 shows a chart showing the transition of the air preheater differential pressure and the NO x concentration at the outlet of the economizer in Unit 1. Since there are two air preheaters and economizers (system A and system B), each system is shown. Tables 1 to 3 also show the date of sampling in Unit 1, the brand of coal used, the air preheater (AH) differential pressure (unit: mmAq), CaO / S in fuel, and CaO (unit: mass%). , Total sulfur S (unit: mass%) and NO x concentration (unit: ppm) at the outlet of the economizer were shown.

なお、図１における空気予熱器差圧の推移より、差圧低下が観察された期間および差圧上昇が観察された期間をそれぞれ期間Ａ、期間Ｃとして区分し、図および表中にＢ１、Ｂ２...およびＣ１、Ｃ２...のように示した。また、特にＣａＯ含有率の高いニューランズ炭を単独または他の銘柄の石炭と混合して使用し、大きな差圧低下が観察された期間を期間Ａと区分し、図および表中にＡ１、Ａ２...のように示した。   From the transition of the air preheater differential pressure in FIG. 1, the period in which the differential pressure drop is observed and the period in which the differential pressure rise is observed are divided into period A and period C, respectively. ... and C1, C2 .... In addition, Newlands coal with a particularly high CaO content is used alone or mixed with other brands of coal, and the period in which a large drop in differential pressure is observed is divided from period A. A1 and A2 are shown in the figures and tables. Shown like ...

図４には、２号機における空気予熱器差圧、および節炭機出口のＮＯｘ濃度の推移を表すチャートを示した。また、表４〜６には、２号機における試料採取日、使用した石炭の銘柄、空気予熱器差圧、燃料中のＣａＯ／Ｓ、ＣａＯ、全硫黄Ｓ、節炭機出口のＮＯｘ濃度をそれぞれ示した。また、図５には、４号機における空気予熱器差圧、および節炭機出口のＮＯｘ濃度の推移を表すチャートを示した。また、表７〜９には、４号機における使用した石炭の銘柄、空気予熱器差圧、燃料中のＣａＯ／Ｓ、ＣａＯ、全硫黄Ｓ、節炭機出口のＮＯｘ濃度をそれぞれ示した。さらに、図６には、５号機における空気予熱器差圧、および節炭機出口のＮＯｘ濃度の推移を表すチャートを示した。また、表１０〜１２には、５号機における、試料採取日、使用した石炭の銘柄、空気予熱器差圧、燃料中のＣａＯ／Ｓ、ＣａＯ、全硫黄Ｓ、節炭機出口のＮＯｘ濃度をそれぞれ示した。図４〜６および表４〜１２における記載要領は、図３および表１〜３と同様である。但し、図４、図５および表７〜１２において、空気予熱器差圧は単位ｋＰａで記載した。 FIG. 4 shows a chart showing changes in the air preheater differential pressure in Unit 2 and the NOx concentration at the outlet of the economizer. Also, Table 4-6, sample days in Unit 2, brand of coal used, air preheater differential pressure, CaO / S in the fuel, CaO, total sulfur S, the concentration of NO x economizer machine outlet Shown respectively. FIG. 5 shows a chart showing the transition of the air preheater differential pressure in Unit 4 and the NO x concentration at the outlet of the economizer. Also, Table 7-9, shows coal used in Unit 4 brands, air preheater differential pressure, CaO / S in the fuel, CaO, total sulfur S, the concentration of NO x economiser machine outlet, respectively. Further, FIG. 6 shows a chart showing the transition of the air preheater differential pressure in Unit 5 and the NO x concentration at the outlet of the economizer. Further, Table 10-12, in Unit 5, sample days, stocks of coal used, air preheater differential pressure, in the fuel CaO / S, CaO, total sulfur S, NO x concentration economizer machine outlet Respectively. The description points in FIGS. 4 to 6 and Tables 4 to 12 are the same as those in FIGS. However, in FIG. 4, FIG. 5 and Tables 7-12, the air preheater differential pressure was described in unit kPa.

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図３〜６よび表１〜１２より、差圧低下した期間Ａ、期間Ｂと差圧上昇した期間Ｃとを比較すると、期間Ａおよび期間Ｂでは使用した燃料のＣａＯ／Ｓが大きく、期間Ｃでは小さい傾向にあった。概ね、ＣａＯ／Ｓが３以上であれば差圧低下が期待でき、４．５以上であればより確実であると考えられる。さらに、ＣａＯが２以上、Ｓが０．５以下であることが好ましいと考えられる。   3 to 6 and Tables 1 to 12, when comparing the period A and the period B in which the differential pressure has decreased and the period C in which the differential pressure has increased, the CaO / S of the fuel used in the period A and the period B is large. It was a small trend. Generally, if CaO / S is 3 or more, a decrease in differential pressure can be expected, and if it is 4.5 or more, it is considered to be more reliable. Furthermore, it is considered preferable that CaO is 2 or more and S is 0.5 or less.

また、図７には、平成１９年１１月７日の２号機におけるスートブロワのオン／オフによる空気予熱器差圧の変動を示すチャートを示した。このチャートからは、スートブロワがオンのときに空気予熱器の差圧が低下し、停止時は横ばいか若干上昇するのみであって、全体として差圧が徐々に低下する傾向にあることが分かる。当日は期間Ａ２に属しており、ＣａＯ／Ｓの高いニューランズ炭を使用していることから、結晶性粉体である石膏が多く生成され、硫酸水素アンモニウムの生成が抑制されているものと考えられる。このことから、スートブロワの運転により容易に除灰が行われて差圧が低下し、スートブロワ停止中においても燃焼灰の付着があまり多くないため差圧があまり上昇しないことが示されている、といえる。   FIG. 7 shows a chart showing fluctuations in the air preheater differential pressure due to ON / OFF of the soot blower in Unit 2 on November 7, 2007. From this chart, it can be seen that the differential pressure of the air preheater decreases when the soot blower is on, and is flat or slightly increased when the soot blower is stopped, and the overall differential pressure tends to gradually decrease. The day belongs to period A2, and because Newlands charcoal with a high CaO / S is used, a large amount of gypsum, which is a crystalline powder, is produced, and the production of ammonium hydrogen sulfate is suppressed. It is done. From this, it is shown that the ash is easily removed by the operation of the soot blower and the differential pressure is lowered, and even when the soot blower is stopped, the adhesion of combustion ash is not so much, so the differential pressure does not rise so much. I can say that.

なお、排煙脱硝装置における脱硝効率の低下が、排ガス中への未反応アンモニア濃度を増大させ、硫酸水素アンモニウム生成量増大の一因となる。   Note that a decrease in the denitration efficiency in the flue gas denitration apparatus increases the concentration of unreacted ammonia in the exhaust gas, which contributes to an increase in the amount of ammonium hydrogen sulfate produced.

脱硝触媒が劣化すると、硫酸水素アンモニウムの発生原因となる未反応アンモニアが排ガス中に多量に残留することとなるので、空気予熱器の差圧上昇が起こりやすいと考えられる。よって、脱硝装置のメンテナンス（脱硝触媒の取替）を行うといった対策を併用すると、より効果的である。   When the denitration catalyst is deteriorated, a large amount of unreacted ammonia that causes ammonium hydrogen sulfate to be generated remains in the exhaust gas. Therefore, it is considered that the differential pressure of the air preheater is likely to increase. Therefore, it is more effective to use measures such as maintenance of the denitration device (replacement of the denitration catalyst) together.

＜他の実施形態＞
本発明は上記記述及び図面によって説明した実施形態に限定されるものではなく、例えば次のような実施形態も本発明の技術的範囲に含まれる。
（１）上記実施例では、ＣａＯ含有量の高いニューランズ炭を単独で用いた場合、およびニューランズ炭を他の銘柄の石炭と混合してＣａＯ／Ｓが３．０以上となるように調整したものを燃料として用いた場合に、差圧低下降下が確認された例について示したが、ＣａＯ含有量の低い石炭にＣａＯを添加してＣａＯ／Ｓが３．０以上となるように調整した燃料を使用しても同様の効果が得られる。 <Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the above example, when Newlands coal with a high CaO content is used alone, and when Newlands coal is mixed with other brands of coal, the CaO / S is adjusted to 3.0 or more. In the case of using this as a fuel, an example in which a drop in pressure difference was confirmed was shown, but CaO was added to coal with a low CaO content so that CaO / S was adjusted to 3.0 or more. The same effect can be obtained even if fuel is used.

１...ボイラ
２０...排ガス処理設備
２１...排煙脱硝装置
２２...空気予熱器
３１...ガス側入口ダクト
３３...ガス側出口ダクト
Ｐ...火力発電プラント DESCRIPTION OF SYMBOLS 1 ... Boiler 20 ... Exhaust gas treatment equipment 21 ... Flue gas denitration device 22 ... Air preheater 31 ... Gas side inlet duct 33 ... Gas side outlet duct P ... Thermal power plant

Claims (4)

石炭を含む燃料を燃焼させるボイラと、前記ボイラから排出される燃焼排ガス中から窒素酸化物を除去するための排煙脱硝装置および前記排煙脱硝装置の下段に設けられて前記燃焼排ガスと前記ボイラへ供給される空気とを熱交換させるための空気予熱器を含む排ガス処理設備とを備える火力発電プラントにおいて、前記空気予熱器に前記燃焼排ガスを導入するガス側入口ダクトと前記空気予熱器から前記燃焼排ガスを排出するガス側出口ダクトとの差圧を抑制する方法であって、
前記燃料として、全硫黄分の含有率に対する酸化カルシウム含有率の比率（ＣａＯ／Ｓ）が３．０以上である石炭または石炭混合物を用いる、空気予熱器の差圧抑制方法。 A boiler for burning fuel containing coal, a flue gas denitration device for removing nitrogen oxides from flue gas discharged from the boiler, and the flue gas and boiler provided in a lower stage of the flue gas denitration device In a thermal power plant comprising an exhaust gas treatment facility including an air preheater for exchanging heat with air supplied to the air preheater, a gas side inlet duct for introducing the combustion exhaust gas into the air preheater and the air preheater A method for suppressing a differential pressure with a gas side outlet duct for discharging combustion exhaust gas,
A method for suppressing a differential pressure of an air preheater using coal or a coal mixture having a ratio of calcium oxide content to total sulfur content (CaO / S) of 3.0 or more as the fuel. 前記燃料としてニューランズ炭を用いる、請求項１に記載の空気予熱器の差圧抑制方法。   The method for suppressing a differential pressure of an air preheater according to claim 1, wherein Newlands coal is used as the fuel. 前記燃料として、ＣａＯ／Ｓが３．０以上となるように前記ニューランズ炭を他の銘柄の前記石炭と混合したものを用いる、請求項１に記載の空気予熱器の差圧抑制方法。   The method for suppressing differential pressure of an air preheater according to claim 1, wherein the fuel is a mixture of the Newlands coal with another brand of coal so that CaO / S is 3.0 or more. 前記燃料として、ＣａＯ／Ｓが３．０以上となるように前記石炭にＣａＯを添加したものを用いる、請求項１に記載の空気予熱器の差圧抑制方法。   The method for suppressing a differential pressure of an air preheater according to claim 1, wherein the fuel is one in which CaO is added to the coal so that CaO / S is 3.0 or more.
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CN104456600A (en) * 2014-12-16 2015-03-25 抚顺天赐石灰石开发有限公司 Lime rotary kiln pulverized coal preparing and conveying device
CN106731832A (en) * 2017-01-09 2017-05-31 青岛双瑞海洋环境工程股份有限公司 Marine exhaust denitrating system
JP2019027763A (en) * 2017-08-03 2019-02-21 一般財団法人電力中央研究所 Boiler equipment, power generation equipment, air preheating equipment and differential pressure prediction method of air preheater

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CN104456600A (en) * 2014-12-16 2015-03-25 抚顺天赐石灰石开发有限公司 Lime rotary kiln pulverized coal preparing and conveying device
CN106731832A (en) * 2017-01-09 2017-05-31 青岛双瑞海洋环境工程股份有限公司 Marine exhaust denitrating system
JP2019027763A (en) * 2017-08-03 2019-02-21 一般財団法人電力中央研究所 Boiler equipment, power generation equipment, air preheating equipment and differential pressure prediction method of air preheater
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