JP6238285B2 - Coal combustion apparatus and coal combustion method - Google Patents
Coal combustion apparatus and coal combustion method Download PDFInfo
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本発明は石炭燃焼装置および石炭燃焼方法に関し、特に微粉炭を燃料とする石炭火力発電設備等に適用して有用なものである。 The present invention relates to a coal combustion apparatus and a coal combustion method, and is particularly useful when applied to a coal-fired power generation facility using pulverized coal as a fuel.
石炭火力発電設備では、その多くで微粉炭が燃料として使用されている。微粉炭は、石炭をローラミルで細かく粉砕して製造し、その後火炉に搬送して燃焼させている。そして、微粉炭を火炉で燃焼させることにより生成される石炭灰はセメント等に混入されて有効利用されている。石炭中に１割程度含まれている石炭灰の再利用を図る場合、灰中未燃焼分濃度（燃え残り成分の割合）を所定値以下にすることが求められる。具体的には、灰中未燃分濃度を３％以下にする必要がある。ここで、灰中未燃分濃度を少なくするには微粉炭の燃焼性を向上させて燃え残りを少なくする必要がある。 In many coal-fired power generation facilities, pulverized coal is used as fuel. The pulverized coal is produced by finely pulverizing coal with a roller mill, and then transported to a furnace and burned. And the coal ash produced | generated by burning pulverized coal with a furnace is mixed with cement etc., and is utilized effectively. When reusing coal ash contained in about 10% of coal, it is required that the unburned component concentration (ratio of unburned components) in the ash be a predetermined value or less. Specifically, it is necessary to make the unburned fuel concentration in ash 3% or less. Here, in order to reduce the concentration of unburned ash in the ash, it is necessary to improve the flammability of pulverized coal and reduce the unburned residue.
なお、微粉炭として炉内に吹き込まれた微粉炭の燃焼性を向上させる燃焼方法を開示する公知文献として特許文献１がある。これは、微粉炭に酸化鉄粉を混合し、高炉に吹込んで燃焼させることにより微粉炭の燃焼性を向上させるものである。しかしながら、特許文献１に開示する燃焼方法では、亜瀝青炭等の低品位の石炭であっても充分な燃焼効率を得るという点からは充分ではない。 In addition, there exists patent document 1 as a well-known literature which discloses the combustion method which improves the combustibility of the pulverized coal injected into the furnace as pulverized coal. This improves flammability of pulverized coal by mixing iron oxide powder with pulverized coal and blowing it into a blast furnace for combustion. However, the combustion method disclosed in Patent Document 1 is not sufficient from the viewpoint of obtaining sufficient combustion efficiency even with low grade coal such as subbituminous coal.
本発明は、上記従来技術に鑑み、微粉炭の燃焼効率を向上させ、安価、確実に石炭灰中の未燃分濃度を低減させることができる石炭燃焼装置および石炭燃焼方法を提供することを目的とする。 An object of the present invention is to provide a coal combustion apparatus and a coal combustion method capable of improving the combustion efficiency of pulverized coal and reducing the unburned component concentration in coal ash reliably and inexpensively in view of the above-described conventional technology. And
上記目的を達成する本発明の第１の態様は、
供供給される石炭を粉砕して微粉炭とするローラミルと、該ローラミルで粉砕した微粉炭が燃焼される火炉とを有する石炭燃焼装置であって、
前記ローラミルの上流側に配設され、前記火炉に供給される石炭に、鉄またはカルシウムを溶融させた酢酸溶液を噴霧する噴霧手段を有し、
前記噴霧手段は、前記石炭として燃料比が異なる複数種類の石炭を個別の搬送ラインを介して搬送された後、前記ローラミルで粉砕して得る混炭を用いる際に、前記各石炭の燃料比に基づき燃料比が大きい炭種の石炭を搬送する搬送ラインから順に前記噴霧を選択的に行うようにしたことを特徴とする石炭燃焼装置にある。
The first aspect of the present invention for achieving the above object is as follows:
A coal combustion apparatus having a roller mill that pulverizes supplied coal into pulverized coal, and a furnace in which the pulverized coal pulverized by the roller mill is burned,
Wherein is disposed upstream of the roller mill, the coal supplied to the furnace, have a spray means for spraying the acid solution obtained by melting iron or calcium,
The spray means is based on the fuel ratio of each coal when using a coal mixture obtained by pulverizing with a roller mill after a plurality of types of coal having different fuel ratios are transported as individual coals via individual transport lines. In the coal combustion apparatus, the spraying is selectively performed in order from a transport line for transporting coal of a coal type having a large fuel ratio .
本態様によれば、微粉炭の表面に鉄またはカルシウムの微粒子が担持されているので、かかる微粉炭が火炉内に投入されることにより、鉄またはカルシウムの触媒効果が発揮され、微粉炭の燃焼効率を向上させることができる。この結果、石炭灰中の灰中未燃分を低く抑えることができる。 According to this aspect, since the fine particles of iron or calcium are supported on the surface of the pulverized coal, the catalytic effect of iron or calcium is exhibited when the pulverized coal is put into the furnace, and the combustion of the pulverized coal is performed. Efficiency can be improved. As a result, the unburned content in the ash in the coal ash can be kept low.
一方、鉄またはカルシウムを酢酸に溶融させることなく粉体で石炭に噴霧しても燃焼効率の向上という効果は得られず、同様に高鉄分炭や高カルシウム炭を混炭しても相手炭に対する燃焼効率の向上という効果は得られなかった。かかる事実は、鉄またはカルシウムを酢酸溶液に溶融させた状態で石炭に噴霧しなければ、微粉炭の燃焼効率の向上という本態様の特徴的な効果は得られないことを示している。すなわち、微粉炭の表面に鉄またはカルシウムの微粒子が担持されてはじめて燃焼時における鉄またはカルシウムの触媒効果が発揮されて燃焼効率の向上に寄与し得ると考えられる。
また、ローラミルで粉砕されて得る微粉炭は火炉内に乾燥空気とともに、乾燥した状態で供給される。この結果、微粉炭が火炉のバーナ等に付着することなく、良好に火炉内に供給することができる。ちなみに、微粉炭に粉砕した後に前記酢酸溶液を噴霧すると、酢酸溶液の付着により微粉炭がバーナ等に付着して火炉内への供給が阻害される場合が懸念される。一方、粉砕前の石炭に酢酸溶液を噴霧した後、前記石炭を粉砕しても、粉砕された微粉炭には、石炭の表面から浸透した酢酸溶液とともに鉄またはカルシウムの微粒子が微粉炭の表面に付着していることが確認できた。
さらに、燃料比を考慮した炭種に応じた噴霧の適正化を図ることができる。
On the other hand, even if iron or calcium is sprayed on coal with powder without melting it in acetic acid, the effect of improving combustion efficiency is not obtained, and even if high iron content coal or high calcium coal is mixed, combustion against the opposite coal The effect of improving efficiency was not obtained. This fact indicates that the characteristic effect of this aspect of improving the combustion efficiency of pulverized coal cannot be obtained unless iron or calcium is melted in an acetic acid solution and sprayed onto the coal. That is, it is considered that the catalytic effect of iron or calcium during combustion is exhibited only after iron or calcium fine particles are supported on the surface of pulverized coal and can contribute to improvement in combustion efficiency.
Moreover, the pulverized coal obtained by pulverizing with a roller mill is supplied into a furnace together with dry air in a dry state. As a result, pulverized coal can be satisfactorily supplied into the furnace without adhering to the furnace burner or the like. Incidentally, if the acetic acid solution is sprayed after pulverized into pulverized coal, there is a concern that the pulverized coal adheres to the burner or the like due to the acetic acid solution and the supply into the furnace is hindered. On the other hand, after spraying the acetic acid solution on the coal before pulverization, even if the coal is pulverized, the pulverized coal has fine particles of iron or calcium on the surface of the pulverized coal together with the acetic acid solution that has penetrated from the surface of the coal. It was confirmed that they were attached.
Further, it is possible to optimize the spray according to the coal type in consideration of the fuel ratio.
本発明の第２の態様は、
第１の態様に記載する石炭燃焼装置において、
前記噴霧手段は、前記石炭の燃料比に基づき燃料比が大きいものほど噴霧するか、または噴霧量が多くなるように制御されるように構成したことを特徴とする石炭燃焼装置にある。
The second aspect of the present invention is:
In the coal combustion apparatus described in the first aspect,
The spray means is configured to be sprayed as the fuel ratio is larger based on the fuel ratio of the coal, or to be controlled so as to increase the spray amount.
本態様によれば、燃料比が大きいほど効果的な未燃焼率の低減効果が得られる石炭に対して選択的に所定の酢酸溶液を噴霧するようにしたので、噴霧の適正化を図ることができる。 According to this aspect, since the predetermined acetic acid solution is selectively sprayed on the coal that can obtain an effective effect of reducing the unburned rate as the fuel ratio increases, it is possible to optimize the spraying. it can.
本発明の第３の態様は、
ローラミルで粉砕した微粉炭を火炉内に供給して燃焼させる石炭燃焼方法において、
前記ローラミルで石炭を粉砕する上流側で、鉄またはカルシウムを溶融させた酢酸溶液を前記石炭に噴霧して前記火炉内に供給し、前記石炭として燃料比が異なる複数種類の石炭を個別の搬送ラインを介して搬送された後、前記ローラミルで粉砕して得る混炭を用いる際に、前記各石炭の燃料比に基づき燃料比が大きい炭種の石炭から順に前記噴霧を選択的に行うようにしたことを特徴とする石炭燃焼方法にある。
The third aspect of the present invention is:
In a coal combustion method in which pulverized coal pulverized by a roller mill is supplied into a furnace and burned,
On the upstream side of pulverizing coal with the roller mill, an acetic acid solution in which iron or calcium is melted is sprayed on the coal and supplied into the furnace, and a plurality of types of coal having different fuel ratios as the coal are individually transported. When using the coal mixture obtained by pulverizing with the roller mill after being conveyed through the coal, the spraying is selectively performed in order from coal of the coal type having a large fuel ratio based on the fuel ratio of each coal. It is in the coal combustion method characterized by this.
本態様によれば、微粉炭の表面に鉄またはカルシウムの微粒子が担持されているので、
かかる微粉炭が火炉内に投入されることにより、鉄またはカルシウムの触媒効果が発揮さ
れ、微粉炭の燃焼効率を向上させることができる。この結果、石炭灰中の灰中未燃分を低
く抑えることができる。
また、ローラミルで粉砕されて得る微粉炭は火炉内に乾燥空気とともに、乾燥した状態で供給される。この結果、微粉炭が火炉のバーナ等に付着することなく、良好に火炉内に供給することができる。
さらに、燃料比が異なる複数種類の石炭の混炭を用いる場合において、噴霧の最適化を計り最も合理的な微粉炭の燃焼効率の向上を図ることができる。
According to this aspect, since fine particles of iron or calcium are supported on the surface of the pulverized coal,
By introducing such pulverized coal into the furnace, the catalytic effect of iron or calcium is exhibited, and the combustion efficiency of pulverized coal can be improved. As a result, the unburned content in the ash in the coal ash can be kept low.
Moreover, the pulverized coal obtained by pulverizing with a roller mill is supplied into a furnace together with dry air in a dry state. As a result, pulverized coal can be satisfactorily supplied into the furnace without adhering to the furnace burner or the like.
Furthermore, in the case of using a mixture of a plurality of types of coal having different fuel ratios, the most rational combustion efficiency of pulverized coal can be improved by optimizing the spray.
本発明の第４の態様は、
第３の態様に記載する石炭燃焼方法において、
前記噴霧は、前記石炭の燃料比に基づき燃料比が大きいものほど噴霧するか、または噴霧量を多くして行うようにしたことを特徴とする石炭燃焼方法にある。
The fourth aspect of the present invention is:
In the coal combustion method described in the third aspect,
In the coal combustion method, the spraying is performed by spraying the fuel with a larger fuel ratio based on the fuel ratio of the coal or by increasing the spray amount.
本態様によれば、上述の如き鉄またはカルシウムの触媒効果の発揮による微粉炭の燃焼効率を向上効果の最適化を計ることができる。 According to this aspect, it is possible to optimize the effect of improving the combustion efficiency of pulverized coal by exhibiting the catalytic effect of iron or calcium as described above.
本発明によれば、鉄またはカルシウムを溶融させた酢酸溶液を石炭に噴霧しているので、火炉内に供給する微粉炭の表面に鉄またはカルシウムの微粒子を担持させることができる。この結果、火炉内における微粉炭の燃焼に際し、鉄またはカルシウムの触媒効果により燃焼効率を向上させることができ、石炭灰中の未燃分濃度を良好に低減させることが可能になる。 According to the present invention, since the acetic acid solution in which iron or calcium is melted is sprayed onto the coal, fine particles of iron or calcium can be supported on the surface of the pulverized coal supplied into the furnace. As a result, when the pulverized coal is burned in the furnace, the combustion efficiency can be improved by the catalytic effect of iron or calcium, and the unburned component concentration in the coal ash can be favorably reduced.
以下、本発明の実施の形態を図面に基づき詳細に説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
図１は本発明の実施の形態に係る石炭燃焼装置を示すブロック図である。同図に示すように、ローラミル２で粉砕されて燃料となる微粉炭は、搬送用の空気を兼用する１次空気とともに微粉炭搬送管路４およびバーナ３を介して石炭燃焼装置Ｉの火炉１内に給される。石炭燃焼装置Ｉは、火炉１の下流側に二段燃焼用空気が供給される二段燃焼ボイラであり、さらにバーナ３からは１次空気の他に２次空気および３次空気が旋回流として噴射される。かくして、火炉１の下部では、燃料を過剰にして主に微粉炭のガス化を促進するととともに、上部では空気を過剰にして酸化雰囲気での燃焼を行う。かかる二段燃焼によりＮＯｘの発生を可及的に抑制している。 FIG. 1 is a block diagram showing a coal combustion apparatus according to an embodiment of the present invention. As shown in the figure, the pulverized coal that is pulverized by the roller mill 2 and used as the fuel, together with the primary air that also serves as the conveying air, is connected to the furnace 1 of the coal combustion apparatus I through the pulverized coal conveying line 4 and the burner 3. Be fed in. The coal combustion apparatus I is a two-stage combustion boiler in which air for two-stage combustion is supplied to the downstream side of the furnace 1, and secondary air and tertiary air are swirled from the burner 3 in addition to primary air. Be injected. Thus, in the lower part of the furnace 1, fuel is excessively promoted mainly to promote gasification of pulverized coal, and in the upper part, air is excessively combusted in an oxidizing atmosphere. Such two-stage combustion suppresses generation of NO x as much as possible.
ローラミル２では、そのテーブル上に供給された石炭塊がローラの回転によりテーブルとの間で粉砕されて微粉炭となる。かかる微粉炭が、乾燥用の熱風とともに微粉炭搬送管路４内を火炉１に向けて搬送される。 In the roller mill 2, the coal lump supplied onto the table is pulverized between the table and the pulverized coal by the rotation of the roller. The pulverized coal is conveyed along with the hot air for drying toward the furnace 1 in the pulverized coal conveyance pipeline 4.
本形態に係る石炭燃焼装置Ｉには、ローラミル２の上流側においてローラミル２に供給される石炭に酢酸溶液を噴霧する噴霧手段５が配設されている。噴霧手段５の酢酸溶液には、鉄またはカルシウムが溶融させてあり、酢酸溶液の噴霧により鉄またはカルシウムが石炭の表面に付着され、鉄またはカルシウムが酢酸溶液とともに石炭の内部に浸透される。したがって、火炉１内には、鉄またはカルシウムを表面に担持した状態で微粉炭が供給される。 The coal combustion apparatus I according to the present embodiment is provided with spraying means 5 for spraying an acetic acid solution onto coal supplied to the roller mill 2 on the upstream side of the roller mill 2. Iron or calcium is melted in the acetic acid solution of the spraying means 5, and the iron or calcium is adhered to the surface of the coal by spraying the acetic acid solution, and the iron or calcium is permeated into the coal together with the acetic acid solution. Therefore, pulverized coal is supplied into the furnace 1 with iron or calcium supported on the surface.
かかる本形態によれば、酢酸溶液を媒介として微粉炭の表面に付着している鉄分（Ｆｅ）やカルシウム分（Ｃａ）による触媒効果が発揮され未燃焼率が低減される。したがって、灰中未燃分濃度も低減され所定の良質の石炭灰を得ることができる。 According to this embodiment, the catalytic effect of iron (Fe) and calcium (Ca) adhering to the surface of the pulverized coal through the acetic acid solution is exerted, and the unburned rate is reduced. Accordingly, the concentration of unburned ash in the ash is reduced, and a predetermined high quality coal ash can be obtained.
ここで、本形態では、ローラミル２で粉砕されて得る微粉炭は火炉１内に乾燥空気とともに、乾燥した状態で供給される結果、微粉炭が火炉１のバーナ３等に付着することなく、良好に火炉１内に供給することができる。ちなみに、粉砕した後の微粉炭に酢酸溶液を噴霧すると、酢酸溶液の付着により微粉炭がバーナ３等に付着して火炉１内への供給が阻害される場合が懸念される。したがって、酢酸溶液の噴霧後に石炭を粉砕する方が望ましい。ただ、粉砕前に限る必要はない。 Here, in this embodiment, the pulverized coal obtained by being pulverized by the roller mill 2 is supplied into the furnace 1 together with the dry air in a dry state. As a result, the pulverized coal does not adhere to the burner 3 of the furnace 1 and the like. Can be supplied into the furnace 1. Incidentally, when the acetic acid solution is sprayed on the pulverized coal after pulverization, there is a concern that the pulverized coal adheres to the burner 3 or the like due to adhesion of the acetic acid solution and the supply into the furnace 1 is hindered. Therefore, it is desirable to pulverize the coal after spraying the acetic acid solution. However, it need not be limited to before crushing.
一方、粉砕前の石炭に酢酸溶液を噴霧した後、石炭を粉砕しても、粉砕された微粉炭には、石炭の表面から浸透した酢酸溶液とともに鉄またはカルシウムの微粒子が微粉炭の表面に付着していることは電子線マイクロアナライザによる観察で確認されている。 On the other hand, even after the acetic acid solution is sprayed on the coal before pulverization and the coal is pulverized, fine particles of iron or calcium adhere to the surface of the pulverized coal along with the acetic acid solution that has penetrated from the surface of the coal. This is confirmed by observation with an electron beam microanalyzer.
かかる本願発明の作用・効果は次のような実験結果により裏付けられる。本実験では、微粉炭燃焼時における鉄分およびカルシウム分の添加による未燃分低減効果を確認した。具体的には、鉄分（Ｆｅ）やカルシウム分（Ｃａ）による触媒効果に着目し、まず、石炭灰中のこれらの成分と未燃分との関係を把握した。次に、これらの成分を別途添加し、燃焼促進効果を明らかにした。 The operation and effect of the present invention is supported by the following experimental results. In this experiment, the unburned matter reduction effect by adding iron and calcium during pulverized coal combustion was confirmed. Specifically, focusing on the catalytic effect of iron (Fe) and calcium (Ca), first, the relationship between these components in coal ash and unburned components was grasped. Next, these components were added separately to clarify the combustion promotion effect.
燃焼試験は２つの微粉炭燃焼試験炉を用いて実施した。一つは竪型炉（０．９ｍ（Ｗ）×１．９ｍ（Ｌ）×９．７ｍ（Ｈ）、投入熱量２．４ＭＷth、３段バーナ）で、他の一つは横置円筒炉（０．８５ｍ（φｉn)、８ｍ（Ｌ）、投入熱量０．８ＭＷth、単一バーナ）である。空気比１．２４(火炉出口酸素濃度４％)、二段燃焼率３０％（注入位置：竪型炉は中段バーナから３ｍ、横置円筒炉はバーナ出口から３ｍ）の一定条件において、燃焼試験を実施した。 The combustion test was carried out using two pulverized coal combustion test furnaces. One is vertical furnace (0.9m (W) x 1.9m (L) x 9.7m (H), input heat is 2.4MW th , 3 stage burner), the other is horizontal cylindrical furnace (0.85 m (φ in ), 8 m (L), input heat amount 0.8 MW th , single burner). Combustion test under constant conditions of air ratio 1.24 (furnace outlet oxygen concentration 4%), two-stage combustion rate 30% (injection position: vertical furnace 3m from middle burner, horizontal cylindrical furnace 3m from burner outlet) Carried out.
この結果、石炭性状と未燃焼率の関係に関し、次の知見を得た。竪型炉を用いて、１２炭種について一定条件で燃焼した。この場合、既報（牧野ら、日本エネルギー学会誌、７３，１０，９０６−９１３（１９９３））と同様に、燃料比（固定炭素／揮発分量）と未燃焼率（＝１００−燃焼効率）の関係を比較すると、幾つかの炭種は、導出される直線関係に合致しなかった。これらの炭種について石炭性状を比較すると、鉄（Ｆｅ）またはカルシウム（Ｃａ）が他の炭種に比べて多く含まれていることが確認できた。燃料比ごとに、石炭中の鉄（Ｆｅ）とカルシウム（Ｃａ）の含有量が未燃焼率に及ぼす影響を比較すると、図２に示すように、鉄（Ｆｅ）とカルシウム（Ｃａ）の含有量の増加に応じて、未燃焼率が低くなり、燃料比の高い石炭は、未燃焼率の低下が顕著になることがわかった。 As a result, the following knowledge was obtained regarding the relationship between the coal properties and the unburned rate. Using a vertical furnace, 12 types of coal were burned under certain conditions. In this case, as in the previous report (Makino et al., Journal of the Japan Institute of Energy, 73, 10, 906-913 (1993)), the relationship between the fuel ratio (fixed carbon / volatile content) and the unburned rate (= 100-combustion efficiency). , Some coal types did not match the derived linear relationship. When the coal properties of these coal types were compared, it was confirmed that iron (Fe) or calcium (Ca) was contained in a larger amount than other coal types. When the influence of the content of iron (Fe) and calcium (Ca) in coal on the unburned rate is compared for each fuel ratio, the content of iron (Fe) and calcium (Ca) is shown in FIG. It has been found that the unburned rate decreases with an increase in the amount of coal, and that the unburned rate decreases significantly for coal with a high fuel ratio.
そこで、続いて、鉄分およびカルシウム分の添加による未燃分低減効果に関して調べた。燃料比が２の瀝青炭に、石炭中の鉄（Ｆｅ）とカルシウム（Ｃａ）の含有割合が１×０−2（ｋｇ-Ｆｅ,ｋｇ-Ｃａ／ｋｇ-ｃｏａｌ）となるように、酢酸に溶融した鉄またはカルシウムを５×１０−3（ｋｇ-Ｆｅ,ｋｇ-Ｃａ／ｋｇ-ｃｏａｌ）添加してから粉砕し、横置円筒炉で燃焼した際の未燃焼率を比較した。この結果を図３に示す。同図を参照すれば、石炭に鉄（Ｆｅ）やカルシウム（Ｃａ）を添加することでも、未燃焼率が低くなり、燃料比だけでなく、鉄（Ｆｅ）やカルシウム（Ｃａ）の含有量も未燃焼率に及ぼす影響が大きいことがわかった。鉄（Ｆｅ）やカルシウム（Ｃａ）の添加量をさらに減少し、５×１０−5（ｋｇ-Ｆｅ,ｋｇ-Ｃａ／ｋｇ-ｃｏａｌ）とすると、カルシウム（Ｃａ）の場合、未燃焼率は低減しないが、鉄（Ｆｅ）の場合は、未燃焼率が低くなることが明らかとなった。かくして、鉄（Ｆｅ）やカルシウム（Ｃａ）を溶解させた酢酸溶液を石炭に噴霧することで未燃焼率を低減させ、良質の石炭灰を提供できることが明らかになった。 Then, it investigated about the unburned content reduction effect by addition of an iron content and a calcium content subsequently. The bituminous coal with a fuel ratio of 2 is melted in acetic acid so that the content ratio of iron (Fe) and calcium (Ca) in the coal is 1 × 0 −2 (kg-Fe, kg-Ca / kg-coal). After adding 5 × 10 −3 (kg-Fe, kg-Ca / kg-coal), the pulverized iron or calcium was pulverized and compared with the unburned rate when burned in a horizontal cylindrical furnace. The result is shown in FIG. Referring to the figure, even if iron (Fe) or calcium (Ca) is added to coal, the unburned rate is lowered, and not only the fuel ratio but also the content of iron (Fe) and calcium (Ca) It was found that the effect on the unburned rate was large. If the amount of iron (Fe) or calcium (Ca) added is further reduced to 5 × 10 −5 (kg-Fe, kg-Ca / kg-coal), the unburned rate is reduced in the case of calcium (Ca). However, in the case of iron (Fe), it has become clear that the unburned rate is low. Thus, it has been clarified that spraying an acetic acid solution in which iron (Fe) or calcium (Ca) is dissolved onto coal can reduce the unburned rate and provide good quality coal ash.
さらに、図４に示すように、鉄（Ｆｅ）やカルシウム（Ｃａ）の添加によっても排ガス中のＮＯｘ濃度は変化しないことも確認された。したがって、本発明によれば、低品質の石炭であっても、環境負荷を増大させることなく、未燃焼率を低減させて良質の石炭灰を提供し得る。 Furthermore, as shown in FIG. 4, it was also confirmed that the addition of iron (Fe) or calcium (Ca) did not change the NO x concentration in the exhaust gas. Therefore, according to this invention, even if it is low quality coal, an unburned rate can be reduced and a good quality coal ash can be provided, without increasing an environmental load.
図２に示すように、鉄（Ｆｅ）やカルシウム（Ｃａ）を溶解させた酢酸溶液を石炭に噴霧する場合、噴霧量が多くなれば多くなるほど、未燃焼率を低減し得る。ただ、噴霧量の最適化を図るためには、噴霧量と未燃焼率の低減効果との関係を考慮する必要がある。図５は、瀝青炭ＣＬに亜瀝青炭ＡＤを混炭した場合の混炭率に対する未燃焼率を、各混炭率の石炭に酢酸溶液を噴霧した場合と、そうでない場合とで調べた燃焼実験の結果を示すグラフである。なお、燃料比（固定炭素／揮発分量）が大きい瀝青炭は、固定炭素の量が多いことに起因して未燃焼率が大きくなる。一方、燃料比が小さい亜瀝青炭は、水分を多く含むので、初期における燃焼はあまり良くないが、水分の蒸発後には揮発分が燃焼され、結果としては未燃焼率が小さくなる。 As shown in FIG. 2, when the acetic acid solution in which iron (Fe) or calcium (Ca) is dissolved is sprayed on coal, the unburned rate can be reduced as the spray amount increases. However, in order to optimize the spray amount, it is necessary to consider the relationship between the spray amount and the effect of reducing the unburned rate. FIG. 5 shows the results of combustion experiments in which the unburned ratio relative to the blend ratio when sub-bituminous coal AD is blended with bituminous coal CL, when the acetic acid solution is sprayed on coal with each blend ratio, and when not. It is a graph. Note that bituminous coal with a large fuel ratio (fixed carbon / volatile content) has a large unburned rate due to a large amount of fixed carbon. On the other hand, sub-bituminous coal with a small fuel ratio contains a lot of water, and therefore, combustion at the initial stage is not so good. However, after evaporation of water, volatile matter is burned, resulting in a low unburned rate.
図５を参照すれば、燃料比が大きい瀝青炭ＣＬに対して燃料比が小さい亜瀝青炭ＡＤの割合が増加する程、未燃焼率（＝１００−燃焼効率（％））は低下している。そして、亜瀝青炭ＡＤの割合が増加すればするほど、酢酸溶液を石炭に噴霧した場合と、そうでない場合の未燃焼率の差が小さくなっていることが分かる。これは、亜瀝青炭ＡＤの割合が増加するほど酢酸溶液を噴霧した効果が相対的に低減するからであると考えられる。だとすれば、揮発分量が多く燃料比が小さい石炭（例えば、亜瀝青炭）に酢酸溶液を噴霧しても顕著な未燃焼率低下の効果は、得られないことになる。かかる事実を確認するため、図６に示す特性を調べた。 Referring to FIG. 5, the unburned rate (= 100−combustion efficiency (%)) decreases as the ratio of subbituminous coal AD having a small fuel ratio to bituminous coal CL having a large fuel ratio increases. And it turns out that the difference of the unburned rate between the case where an acetic acid solution is sprayed on coal and the case where it is not so becomes small, so that the ratio of subbituminous coal AD increases. This is considered to be because the effect of spraying the acetic acid solution relatively decreases as the ratio of subbituminous coal AD increases. If so, even if the acetic acid solution is sprayed on coal (for example, subbituminous coal) having a large amount of volatile components and a small fuel ratio, a remarkable effect of reducing the unburned rate cannot be obtained. In order to confirm this fact, the characteristics shown in FIG. 6 were examined.
図６は、図５における混炭率が２５％（図６（ａ））と、５０％（図６（ｂ））とにおいて、瀝青炭ＣＬと亜瀝青炭ＡＤとの両方に、１）酢酸鉄の溶液を噴霧しなかった場合、２）瀝青炭のみに噴霧した場合、３）両方に噴霧した場合、のそれぞれについて未燃焼率を調べた結果を示すグラフである。 FIG. 6 is a solution of 1) iron acetate for both bituminous coal CL and subbituminous coal AD when the coal mixture ratio in FIG. 5 is 25% (FIG. 6 (a)) and 50% (FIG. 6 (b)). It is a graph which shows the result of having investigated the unburned rate about each when not spraying 2), spraying only to bituminous coal, and 3) spraying to both.
図６（ａ）および図６（ｂ）に示す何れの場合においても、一方（瀝青炭）にのみ噴霧した場合（図中の灰色部分）と両方（瀝青炭および亜瀝青炭）に噴霧した場合（図中の黒色部分）とで、未燃焼率の低減効果は同等であることが認められた。このことは、燃料比が小さい亜瀝青炭に対する噴霧は、燃料比が大きい瀝青炭に対する噴霧に較べ、未燃焼率の低減効果が小さいことを示している。 In either case shown in FIG. 6 (a) and FIG. 6 (b), when sprayed only on one (bituminous coal) (gray portion in the figure) and when sprayed on both (bituminous coal and subbituminous coal) (in the figure) It was confirmed that the effect of reducing the unburned rate was the same. This indicates that the spray for subbituminous coal with a small fuel ratio has a smaller effect of reducing the unburned rate than the spray for bituminous coal with a large fuel ratio.
なお、図６（ａ）および図６（ｂ）に示す何れの場合においても、両方（瀝青炭および亜瀝青炭）に噴霧しない場合（図中の白色部分）に対し、一方（瀝青炭）にのみ噴霧した場合（図中の灰色部分）や、両方（瀝青炭および亜瀝青炭）に噴霧した場合（図中の黒色部分）には、未燃焼率が顕著に低減されている。 In both cases shown in FIGS. 6 (a) and 6 (b), spraying was carried out only on one (bituminous coal) as opposed to the case (white portion in the figure) where both (bituminous coal and subbituminous coal) were not sprayed. In the case (gray part in the figure) or when sprayed on both (bituminous coal and subbituminous coal) (black part in the figure), the unburned rate is significantly reduced.
表１に、上述の実験に用いた瀝青炭ＣＬと亜瀝青炭ＡＤとの性質を示す。 Table 1 shows the properties of bituminous coal CL and sub-bituminous coal AD used in the above-described experiment.
上表１を参照すれば、瀝青炭ＣＬの燃料比（＝固定炭素／揮発分量）が２．１６であるのに対し、亜瀝青炭ＡＤの燃料比は０．９２である。 Referring to Table 1 above, the fuel ratio (= fixed carbon / volatile content) of bituminous coal CL is 2.16, whereas the fuel ratio of sub-bituminous coal AD is 0.92.
そこで、石炭の炭種毎に固有の燃料比に基づき酢酸溶液の噴霧を行うのが合理的である。この場合には、上述の如き鉄またはカルシウムの触媒効果の発揮による微粉炭の燃焼効率を向上効果の最適化を計ることができるからである。 Therefore, it is reasonable to spray the acetic acid solution based on the fuel ratio specific to each coal type. In this case, it is possible to optimize the effect of improving the combustion efficiency of pulverized coal by exhibiting the catalytic effect of iron or calcium as described above.
さらに、石炭として燃料比が異なる複数種類の石炭からなる混炭を用いる際には、各石炭の燃料比に基づき燃料比が大きい炭種の石炭から順に前記噴霧を選択的に行うようにすることでさらに合理的な噴霧を行なうことができる。 Furthermore, when using a coal blend consisting of a plurality of types of coal with different fuel ratios as coal, the spraying is selectively performed in order from the coal type with the larger fuel ratio based on the fuel ratio of each coal. Furthermore, rational spraying can be performed.
図１に示す石炭燃焼装置を、上述の知見に基づき、酢酸溶液の噴霧の適正化を図り得るように構成することもできる。具体的には、噴霧手段５の下方を通過する石炭の燃料比に応じて開閉される噴霧弁を噴霧手段５に設けておき、石炭の種類に応じて選択的に酢酸溶液を噴霧するように構成すればよい。ここで、噴霧弁は、噴霧量を調整し得るように構成されたものでも良く、この場合には、石炭の燃料比を考慮して、燃料比が大きいほど多く噴霧されるように噴霧量を制御することができる。さらに、複数の搬送ラインにより異なる種類の石炭（例えば、瀝青炭と亜瀝青炭）をローラミル２に供給して混炭である微粉炭を火炉１に供給する場合には、搬送ライン毎に区別して酢酸溶液を噴霧するか、または噴霧量を調整するように構成しても良い。 The coal combustion apparatus shown in FIG. 1 can be configured to optimize the spraying of the acetic acid solution based on the above-described knowledge. Specifically, a spray valve that is opened and closed according to the fuel ratio of coal passing under the spraying means 5 is provided in the spraying means 5 so that the acetic acid solution is selectively sprayed according to the type of coal. What is necessary is just to comprise. Here, the spray valve may be configured so that the spray amount can be adjusted. In this case, in consideration of the fuel ratio of coal, the spray amount is increased so that the larger the fuel ratio, the more spray is performed. Can be controlled. Further, when different types of coal (for example, bituminous coal and subbituminous coal) are supplied to the roller mill 2 by a plurality of conveyance lines and pulverized coal as a mixed coal is supplied to the furnace 1, an acetic acid solution is distinguished for each conveyance line. You may comprise so that it may spray or the amount of spraying may be adjusted.
このように石炭の燃料比を考慮して酢酸溶液の噴霧の制御を行なうことにより、効果的な未燃焼率の低下を実現し得る。 Thus, by controlling the spraying of the acetic acid solution in consideration of the fuel ratio of coal, an effective reduction in the unburned rate can be realized.
本発明は微粉炭を燃焼させてその燃焼エネルギーを利用する微粉炭火力発電等の産業分野で有効に利用することができる。 The present invention can be effectively used in industrial fields such as pulverized coal thermal power generation that burns pulverized coal and uses the combustion energy.
Ｉ 石炭燃焼装置
１ 火炉
２ ローラミル
３ バーナ
４ 微粉炭搬送管路
５ 噴霧手段
I Coal Combustion Equipment 1 Furnace 2 Roller Mill 3 Burner 4 Pulverized Coal Conveyance Line 5 Spraying Means
Claims (4)
前記ローラミルの上流側に配設され、前記火炉に供給される石炭に、鉄またはカルシウムを溶融させた酢酸溶液を噴霧する噴霧手段を有し、
前記噴霧手段は、前記石炭として燃料比が異なる複数種類の石炭を個別の搬送ラインを介して搬送された後、前記ローラミルで粉砕して得る混炭を用いる際に、前記各石炭の燃料比に基づき燃料比が大きい炭種の石炭を搬送する搬送ラインから順に前記噴霧を選択的に行うようにしたことを特徴とする石炭燃焼装置。 A coal combustion apparatus having a roller mill that pulverizes supplied coal into pulverized coal, and a furnace in which the pulverized coal pulverized by the roller mill is burned,
Wherein is disposed upstream of the roller mill, the coal supplied to the furnace, have a spray means for spraying the acid solution obtained by melting iron or calcium,
The spray means is based on the fuel ratio of each coal when using a coal mixture obtained by pulverizing with a roller mill after a plurality of types of coal having different fuel ratios are transported as individual coals via individual transport lines. A coal combustion apparatus characterized in that the spraying is selectively performed in order from a transport line for transporting coal of a coal type having a large fuel ratio .
前記噴霧手段は、前記石炭の燃料比に基づき燃料比が大きいものほど噴霧するか、または噴霧量が多くなるように制御されるように構成したことを特徴とする石炭燃焼装置。 The coal combustion apparatus according to claim 1 ,
The coal combustion device is configured such that the spraying means is sprayed as the fuel ratio is larger based on the fuel ratio of the coal, or is controlled so as to increase the spray amount.
前記ローラミルで石炭を粉砕する上流側で、鉄またはカルシウムを溶融させた酢酸溶液を前記石炭に噴霧して前記火炉内に供給し、
前記石炭として燃料比が異なる複数種類の石炭を個別の搬送ラインを介して搬送された後、前記ローラミルで粉砕して得る混炭を用いる際に、前記各石炭の燃料比に基づき燃料比が大きい炭種の石炭から順に前記噴霧を選択的に行うようにしたことを特徴とする石炭燃焼方法。 In a coal combustion method in which pulverized coal pulverized by a roller mill is supplied into a furnace and burned,
On the upstream side of pulverizing coal with the roller mill, an acetic acid solution in which iron or calcium is melted is sprayed on the coal and supplied into the furnace ,
Coal having a large fuel ratio based on the fuel ratio of each coal when using a coal mixture obtained by pulverizing with a roller mill after plural types of coal having different fuel ratios are conveyed as individual coals via individual conveyance lines. The coal combustion method , wherein the spraying is selectively performed in order from seed coal .
前記噴霧は、前記石炭の燃料比に基づき燃料比が大きいものほど噴霧するか、または噴霧量を多くして行うようにしたことを特徴とする石炭燃焼方法。 In the coal combustion method according to claim 3 ,
The coal spraying method is characterized in that spraying is performed with increasing fuel ratio based on the fuel ratio of the coal or by increasing the spray amount.
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