JPS6053083B2 - Control method for pulverized fuel injection into blast furnace - Google Patents

Description

Translated fromJapanese

【発明の詳細な説明】 本発明は、高炉への粉体燃料吹込条件を制御する方法
に関し、詳細には、燃焼性が向上するにつれて灰分の付
着が充進するという粉体燃料の特性を利用し、平常時は
燃焼性の向上を主眼とする吹込みを行ない、灰分付着が
認められる異常時には付着物の成長抑制を主眼とする吹
込みを行なう粉体燃料吹込制御法に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling the conditions for injecting powdered fuel into a blast furnace, and in particular, it utilizes the characteristic of powdered fuel that ash content increases as the combustibility improves. The present invention relates to a powder fuel injection control method in which injection is performed with a focus on improving combustibility during normal times, and injection is performed with a focus on suppressing the growth of deposits during abnormal times when ash adhesion is observed.

高炉操業における吹込燃料は、石油価格の高騰の影響
を受けて重油単独吹込みが影をひそめオールコークス操
業が主流となつている。しかしながら、オールコークス
操業の困難性の緩和や高価なコークスの節約のために微
分決算の粉体燃料吹込みが検討あるいは実施されつつあ
る。しかるに微 粉決等の粉体燃料（以下本明細書にお
いては粉体燃料と総称する）は重油に比べて燃焼速度が
遅くかつ灰分等の未燃分を含有するという欠点を有する
ので、吹込みに当つては種々の対策を構する必要がある
。これを更に具体的に説明すれば以下の通りである。従
来の重油吹込みでは、バーナの先端が高炉別口とブロー
パイプの境界点近傍に配置され、吹込まれた重油が別口
内及び別口直後のレースウェイ内でほぼ完全に燃焼され
ていたのに対し、粉体燃料を同じ位置から吹込んだ場合
は羽口やレースウェイ内で完全に燃焼し尽すことができ
ず、結果として燃焼率が悪くなる。そこで更に検討の結
果燃焼率を向上させる為には、吹込位置をもつと上流に
移動させてブローパイプ内に吹込み、ブローパイプ内に
おいて着火燃焼させればレースウェイ内においてほぼ完
全燃焼が行なわれるということが明らかとなつた。 し
かしその反面下記の如き問題を表面化した。As for the fuel injected in blast furnace operations, due to the effects of soaring oil prices, heavy oil injection alone has faded, and all-coke operation has become the mainstream. However, in order to alleviate the difficulty of all-coke operation and save on expensive coke, powder fuel injection based on differential accounting is being considered or implemented. However, pulverized fuel such as pulverized fuel (hereinafter collectively referred to as pulverized fuel in this specification) has the disadvantage that it has a slower combustion rate than heavy oil and contains unburned matter such as ash, so it is not suitable for injection. In this regard, it is necessary to take various measures. This will be explained more specifically as follows. In conventional heavy oil injection, the tip of the burner was placed near the boundary between the blast furnace outlet and the blow pipe, and the injected heavy oil was almost completely burned inside the outlet and in the raceway immediately after the outlet. On the other hand, if powdered fuel is injected from the same position, it will not be completely burned within the tuyere or raceway, resulting in a poor combustion rate. As a result of further study, we found that in order to improve the combustion rate, if we move the blowing position upstream and blow into the blowpipe, then ignite and burn it in the blowpipe, almost complete combustion will occur in the raceway. It became clear that. However, on the other hand, the following problems have surfaced.

即ち粉体燃料中には程度の差はあれ若干の灰分が・含ま
れており、この灰分は燃焼熱によつて溶融する性質のも
のであるが、上記の如く吹込位置を上流側に移動させた
場合にはこの溶融物がブローパイプの内面に衝突し易く
なり、その衝突部に付着・堆積する。また灰分が未溶融
であつても熱風・通路たるブローパイプや羽口の高温内
面に衝突することにより、その部分で溶融物となり同じ
く付着・堆積する。その結果熱風通路を狭くし、燃料の
安定吹込みを継続することが困難になるばかりか、遂に
は羽口からの熱風吹込みが不能になるという最悪の事態
に発展するという危険もある。そこで本発明者等はこう
した灰分の付着・堆積を発生乃至進行させずに燃焼性を
向上させ得る様な適当な吹込制御法を求めて更に鋭意研
究を重ねた結果、遂に本発明に到達した。しかしてこの
様な本発明の粉体燃料吹込み制御法とは、粉体燃料吹込
用バーナを、高炉羽口に連接された熱風吹込用ブローバ
イブの壁を貫通して該ブローバイブ内へ突入させ、前記
バーナから吹込まれた粉体燃料をブローバイブ内の熱風
と共に高炉羽口から吹込むに当り、前記粉体燃料吹込用
バーナの取付位置を予め前記ブローバイブ側寄りに配置
し、運転開始時には粉体燃料の吹込速度を２３Ｎｍ／Ｓ
ｅｃ未満の燃焼性能が良好な範囲で吹込みを行なうと共
に、ブローバイブ内壁面に付着物の成長が認められた段
階で、粉体燃料の吹込速度を２３Ｎｍ／Ｓｅｃ以上に高
めて吹込みを行なう点に要旨を有するものである。In other words, powdered fuel contains some ash to varying degrees, and this ash has the property of being melted by the heat of combustion. In such a case, this molten material tends to collide with the inner surface of the blow pipe, and adheres and accumulates on the collision part. Furthermore, even if the ash is unmelted, when it collides with the hot inner surface of the blow pipe or tuyere, which serves as a hot air passage, it turns into molten material and adheres to and accumulates there. As a result, the hot air passage becomes narrow, and not only does it become difficult to continue the stable injection of fuel, but there is also the risk that the worst situation will develop, where the hot air blowing from the tuyeres becomes impossible. Therefore, the present inventors conducted further intensive research in search of an appropriate blowing control method that would improve combustibility without causing or promoting the adhesion and accumulation of ash, and finally arrived at the present invention. However, the pulverized fuel injection control method of the present invention is such that the pulverized fuel injection burner penetrates the wall of the hot air blowing blow vibe connected to the blast furnace tuyere and enters the blow vibe. In order to blow the powdered fuel injected from the burner from the blast furnace tuyeres together with the hot air in the blow vibe, the burner for blowing powder fuel is placed in advance near the blow vibe side, and the operation is started. Sometimes the injection speed of powdered fuel is 23Nm/S.
Inject in a range where the combustion performance is good below ec, and when the growth of deposits is observed on the blow vibe inner wall surface, increase the injection speed of powdered fuel to 23 Nm/Sec or more and perform injection. The main points are the main points.

以下実施例図面に基つき本発明の構成及び作用効果を説
明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and effects of the present invention will be explained below based on the drawings of the embodiments.

第１図は本発明制御法の概略説明図てあり、１は高炉底
部、２は高炉底部１に設けられた羽口、３は該羽口２に
連接されたブローバイブである。FIG. 1 is a schematic explanatory diagram of the control method of the present invention, in which 1 is a blast furnace bottom, 2 is a tuyere provided in the blast furnace bottom 1, and 3 is a blow vibe connected to the tuyere 2.

又４は粉体燃料吹込用バーナで、該バーナ４の下方先端
はブローバイブ３内の中央部へ突入して配設され、一方
他端は粉体燃料供給部７から供給される粉体燃料を気流
輸送するための輸送管５に接続され、更に輸送管５の上
部には気流輸送用気体．導入管６が連結されている。こ
の様に構成された粉体燃料吹込み装置を使用して下記の
条件で微粉炭の燃焼実験を行なつた。Further, 4 is a burner for blowing powdered fuel, and the lower end of the burner 4 is arranged so as to protrude into the center of the blow vibe 3, while the other end is the powdered fuel supplied from the powdered fuel supply section 7. The transport pipe 5 is connected to a transport pipe 5 for transporting airflow, and the upper part of the transport pipe 5 is connected to a transport pipe 5 for transporting airflow. An introduction pipe 6 is connected thereto. A pulverized coal combustion experiment was conducted under the following conditions using the pulverized fuel injection device configured as described above.

実験条件吹込燃料：微粉炭（揮発分３２％）熱風温度：１２００揮Ｃ同空気比：２．０燃料吹込用バーナ先端位置（微粉炭吹込み位置）：プローパイプ３と羽口２の境界
から該バイブ３側寄りに０．４１７Ｔｒ１．４離れた
所に固定さて図に現われない熱風発生炉で所定の温度（
１２００℃）まで上昇させた熱風を、ブローバイブ３を
通して羽口２から高炉底部１へ吹込むと共に、微粉炭を
、輸送管５を通してバーナ４からブローバイブ３内に吹
込む。Experimental conditions Injected fuel: Pulverized coal (volatile content 32%) Hot air temperature: 1200 vC Same air ratio: 2.0 Burner tip position for fuel injection (pulverized coal injection position): Boundary between blowpipe 3 and tuyere 2
It was fixed at a place 0.417Tr1.4 away from the vibrator 3 side and heated to a predetermined temperature (
Hot air heated to 1200° C. is blown into the blast furnace bottom 1 from the tuyere 2 through the blow vibe 3, and pulverized coal is blown into the blow vibe 3 from the burner 4 through the transport pipe 5.

吹込みに当つてはバーナ４の先端における吹込速度、即
ち微粉炭噴射速度が１０Ｎｍ／Ｓで固気比９となる様に
、微粉体供給部７からの微粉炭供給及び気流輸送用気体
導入管６からの空気供給の設定調整操作を行なう。この
様な条件及び操作において微粉炭を燃焼させたとき、ブ
ローバイブ３の内壁面に付着物の形成が確認された。こ
のときのバーナ先端から着火位置）Ｐまでの距離１は０
．７７Ｔｒｔ，であつた。この後微粉炭の噴射速度を徐
々に上げながら付着物の形成状態とその時の距離１を調
べた所、第２図のグラフに示す結果が得られた。図中×
印は付着物の形成が確認されたことを、又０印は付着物
の形成が見ら・れなかつたことを示す。このグラフから
明らかな様に、微粉炭噴射速度が２３Ｎｍ／Ｓ以上では
付着物が全く形成されず、勿論成長することもない。又
このときの距離１は０．０９７７ｎであつた。尚このと
き対応する固気比は図示の如く４（Ｋ９／Ｋ９）以“下
である。一般にバーナ噴射口径を一定にして微粉炭噴射
速度を変化させると、固気比は該速度と一定の関係を維
持する様に変化するので、ある特定のバーナにおいて微
粉炭供給量を一定にしたところ、微粉炭噴射速度２３Ｎ
ｍ／Ｓ以上に限定すれば固気比がほぼ４（Ｋ９／Ｋｇ）
以下という条件が付随的に得られた。尚吹込開始時の微
粉炭噴射速度を２３Ｎｍ／Ｓ以上に設定する場合には、
同時に固気比も４（Ｋ９／Ｋ９）以下に設定しおかなけ
ればならないことは言うまでもない。しかし高炉への微
粉炭吹込みはいわゆる間接燃焼方式であり、燃焼性能を
良好に維持する為に一般には固気比を約５（Ｋ９／Ｋ９
）以上に設定して運転が開始される場合がほとんどある
ので、制御も、運転開始は燃焼性能が良好な範囲〔固気
比が５（Ｋｇ／Ｋ９）以上〕で行ない、付着物の形成が
確認されれば固気比が結果的に４（Ｋ９／Ｋ９）以下と
なる様にすることが好ましい。しかして上記実施例では
、微粉炭の吹込み位置を予めブローバイブ側寄りに移動
させて配置することにより完全燃焼が行なわれる状態を
保障し、更に運転開始を燃焼性能が良好な範囲〔固気比
９（Ｋ９／Ｋ９）、微粉炭噴射速度１０Ｎｍ／Ｓ〕で行
ない、付着物の成長が認められた段階で、微粉炭噴射速
度を２３Ｎｍ／Ｓ以上に高めることにより固気比が付随
的に４（Ｋ９／Ｋ９）以下となるように制御する。During the blowing, the pulverized coal is supplied from the pulverized powder supply section 7 and the gas introduction pipe for air flow transport is adjusted so that the blowing speed at the tip of the burner 4, that is, the pulverized coal injection speed is 10 Nm/S and the solid-gas ratio is 9. Perform the air supply setting adjustment operation from step 6. When pulverized coal was burned under these conditions and operations, the formation of deposits on the inner wall surface of the blow vibe 3 was confirmed. At this time, the distance 1 from the burner tip to the ignition position) P is 0.
．． It was 77Trt. Thereafter, while gradually increasing the injection speed of pulverized coal, the state of deposit formation and the distance 1 at that time were investigated, and the results shown in the graph of FIG. 2 were obtained. × in the diagram
A mark indicates that the formation of a deposit was confirmed, and a 0 mark indicates that no deposit was observed. As is clear from this graph, when the pulverized coal injection speed is 23 Nm/S or higher, no deposits are formed at all and, of course, they do not grow. Further, the distance 1 at this time was 0.0977n. In addition, the corresponding solid-air ratio at this time is 4 (K9/K9) or less as shown in the figure.Generally, when the burner injection diameter is kept constant and the pulverized coal injection speed is changed, the solid-air ratio is equal to the constant speed. Since the relationship changes to maintain the relationship, when the pulverized coal supply amount is kept constant in a particular burner, the pulverized coal injection speed is 23N.
If limited to m/S or more, the solid-air ratio is approximately 4 (K9/Kg)
The following conditions were obtained incidentally. In addition, when setting the pulverized coal injection speed at the start of injection to 23 Nm/S or more,
It goes without saying that the solid-air ratio must also be set to 4 (K9/K9) or less at the same time. However, pulverized coal injection into a blast furnace is a so-called indirect combustion method, and in order to maintain good combustion performance, the solid-air ratio is generally about 5 (K9/K9
) or above, the control should be performed at the start of operation in a range where combustion performance is good [solid-air ratio is 5 (Kg/K9) or higher] to prevent the formation of deposits. If confirmed, it is preferable that the solid-gas ratio eventually becomes 4 (K9/K9) or less. However, in the above embodiment, by moving the pulverized coal injection position in advance toward the blow vibe side, it is possible to ensure complete combustion, and furthermore, the operation is started in a range where the combustion performance is good [solid air ratio of 9 (K9/K9) and pulverized coal injection speed of 10 Nm/S], and when the growth of deposits was observed, the solid-gas ratio was increased by increasing the pulverized coal injection speed to 23 Nm/S or more. 4 (K9/K9) or less.

その結果着火点Ｐは第２図に示す様にＰ１−Ｐ２−Ｐ３
・・・・・・と徐々に羽口に近づき、Ｐ５に至つたとき
（微粉炭の噴射速度が２３Ｎｍ／Ｓのとき）にはもはや
付着物の形成は認められず、その成長は停止する。これ
は着火点が遅れることによつて微粉炭中の灰分がブロー
バイブ羽口内で溶融せず、全て高炉底部内で溶融するか
らである。ところで着火点Ｐ，の羽口からの距離は０．
４１７７ＴＩ．−０．０９７７ｎ＝０．３２０７ｎであ
るから、微粉炭の吹込み位置は依然として十分、ブロー
バイブ側寄りに存在し、灰分付着物を成長させることな
く良好な燃焼性能を保持しつつ微粉炭燃焼を行なうこと
ができた。本発明の粉体燃料吹込み制御法は以上の様に
構成したので、灰分の付着・堆積を発生乃至進行させる
ことなく燃焼性能を高く維持して粉体燃料の燃焼を行な
えるようになり、高炉操業における燃料コストの低減化
に寄与する所は大きい。As a result, the ignition point P is P1-P2-P3 as shown in Figure 2.
When the coal gradually approaches the tuyere and reaches P5 (when the injection speed of pulverized coal is 23 Nm/S), the formation of deposits is no longer observed and its growth stops. This is because the ash in the pulverized coal is not melted within the blow-vibrator tuyeres due to the delayed ignition point, but is entirely melted within the bottom of the blast furnace. By the way, the distance of the ignition point P from the tuyere is 0.
4177TI. Since -0.0977n=0.3207n, the injection position of pulverized coal is still sufficiently close to the blow vibe side, and pulverized coal combustion can be achieved while maintaining good combustion performance without growing ash deposits. I was able to do it. Since the pulverized fuel injection control method of the present invention is configured as described above, it is possible to burn pulverized fuel while maintaining high combustion performance without causing or promoting the adhesion or accumulation of ash. It greatly contributes to reducing fuel costs in blast furnace operations.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図は本発明制御法の概略説明図、第２図は微粉炭噴
射速度、固気比、着火位置と灰分付着物形成との関係説
明図である。１・・・・・・高炉底部、２・・・・・・羽口、３・・
・・・・ブローバイブ、４・・・・・・粉体燃料吹込用
バーナ、Ｐ・・・・・・着火位置、１・・・・・・バー
ナ先端から着火位置Ｐまでの距離。FIG. 1 is a schematic explanatory diagram of the control method of the present invention, and FIG. 2 is an explanatory diagram of the relationship between pulverized coal injection speed, solid-air ratio, ignition position, and ash deposit formation. 1... bottom of blast furnace, 2... tuyere, 3...
... Blow vibe, 4 ... Burner for blowing powdered fuel, P ... Ignition position, 1 ... Distance from the tip of the burner to the ignition position P.

Claims (1)

Translated fromJapanese

【特許請求の範囲】[Claims]１ 粉体燃料吹込用バーナを、高炉羽口に連接された熱
風吹込用ブローパイプの壁を貫通して該ブローパイプ内
を突入させ、前記バーナから吹込まれた粉体燃料をブロ
ーパイプ内の熱風と共に高炉羽口から吹込むに当り、前
記粉体燃料吹込用バーナの取付位置を予め前記ブローパ
イプ側寄りに配置し、運転開始時には粉体燃料の吹込速
度を２３Ｎｍ／ｓｅｃ未満の燃焼性能が良好な範囲で吹
込みを行なうと共に、ブローパイプ内壁面に付着物の成
長が認められた段階で、粉体燃料の吹込速度を２３Ｎｍ
／ｓｅｃ以上に高めて吹込みを行なうことを特徴とする
高炉への粉体燃料吹込み制御法。1. A burner for blowing powdered fuel penetrates the wall of a blowpipe for blowing hot air connected to a blast furnace tuyere and enters the blowpipe, and the powdered fuel injected from the burner is transferred to the hot air inside the blowpipe. At the same time, when injecting from the blast furnace tuyeres, the installation position of the burner for blowing powdered fuel is placed in advance near the blow pipe side, and at the start of operation, the blowing speed of powdered fuel is less than 23 Nm/sec, resulting in good combustion performance. When the growth of deposits was observed on the inner wall of the blow pipe, the injection speed of the powdered fuel was increased to 23 Nm.
A method for controlling the injection of powdered fuel into a blast furnace, characterized in that the injection is carried out at a rate higher than /sec.