JPH055506A - Pulverized coal burner - Google Patents

Abstract

PURPOSE:To reduce auxiliary fuel and, besides, to improve the ignition stability of a pulverized coal burner. CONSTITUTION:An opening 26 making a condensed pulverized coal flow passage 19 and a thinned pulverized coal flow passage 20 communicate with each other is provided on the rear side of a contraction part 25. By this opening 26, part of air is made to run from a condensed pulverized coal flow 21 of the condensed pulverized coal flow passage 19 into a thinned pulverized coal flow 22 of the thinned pulverized coal flow passage 20, and therefore the density of the condensed pulverized coal flow 21 is increased.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は微粉炭の燃焼装置に係
り、特にミルと微粉炭バーナを直接連結して運転する燃
焼システムにおける負荷変化の運用幅を拡大するのに好
適な微粉炭バーナに関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulverized coal combustion apparatus, and more particularly to a pulverized coal burner suitable for expanding the operational range of load changes in a combustion system in which a mill and a pulverized coal burner are directly connected to operate. ..

【０００２】[0002]

【従来の技術】近年、我が国においては重油供給量のひ
つ迫から、石油依存度の是正を計るために、従来の重油
専焼から石炭専焼へと変換しつつあり、特に事業用火力
発電ボイラにおいては、石炭専焼の大容量火力発電所が
建設されている。2. Description of the Related Art In recent years, due to the tight supply of heavy oil in Japan, in order to correct the dependence on petroleum, conventional heavy oil burning is being converted to coal burning, especially in commercial thermal power generation boilers. , A large-capacity coal-fired power plant has been built.

【０００３】一方、最近の電力需要の特徴として、原子
力発電の伸びと共に、負荷の最大、最小差も増加し、火
力発電用ボイラをベースロード用から負荷調製用へと移
行する傾向にあり、この火力発電用ボイラを負荷に応じ
て圧力を変化させて変圧運転する、いわゆる全負荷運転
では超臨界圧域、部分負荷運転では亜臨界圧域で運転す
る変圧運転ボイラにすることによつて、部分負荷運転で
の発電効率を数％向上させることができる。On the other hand, as a feature of the recent demand for electric power, the maximum and minimum difference in load increases along with the growth of nuclear power generation, and the boiler for thermal power generation tends to shift from base load use to load adjusting use. By changing the pressure of a boiler for thermal power generation according to the load to perform a variable pressure operation, a so-called full-pressure operation in the supercritical pressure range and a partial load operation in the subcritical pressure range The power generation efficiency in load operation can be improved by several percent.

【０００４】このためにこの石炭専焼火力においては、
ボイラ負荷が常に全負荷で運転されるものは少なく、負
荷を昼間は７５％負荷、５０％負荷、２５％負荷、１５
％負荷へと上げ、下げして運転したり、あるいは夜間は
運転を停止するなど、いわゆる高頻度起動停止（Ｄａｉ
ｌｙ Ｓｔａｒｔ Ｓｔｏｐ以下単にＤＳＳという）運
転を行なつて中間負荷を担う石炭専焼火力へと移行しつ
つある。For this reason, in this coal-only firing power,
Few boiler loads are always operated at full load, and the load is 75% load, 50% load, 25% load, 15
% So that the load may be increased or decreased to operate, or at night, the operation may be stopped.
LY Start Stop (hereinafter simply referred to as DSS) is being operated to shift to coal-fired combustion power that bears an intermediate load.

【０００５】またＤＳＳ運転を行なう石炭専焼ボイラに
おいては、起動時から全負荷に至るまで微粉炭のみで全
負荷帯を運転するものは少なく、石炭専焼ボイラといえ
ども起動時、低負荷時には微粉炭以外の軽油，重油，ガ
ス等を補助燃料として用いる。それは起動時においては
石炭専焼ボイラからミルウオーミング用の排ガス、加熱
空気が得られず、このためにミルを運転することができ
ないので石炭を微粉炭に粉砕することができないからで
ある。また、低負荷時にはミルのターンダウン比がとれ
ないこと、微粉炭自体の着火性が悪いことなどの理由に
よつて軽油，重油，ガス等が用いられている。In the coal-fired boiler which performs the DSS operation, few coal-fired boilers operate in the full load zone only from pulverized coal at the time of start-up to full load. Other light oil, heavy oil, gas, etc. are used as auxiliary fuel. This is because exhaust gas for mill warming and heated air cannot be obtained from the coal-fired boiler at the time of start-up, and therefore the mill cannot be operated and therefore coal cannot be pulverized into pulverized coal. Further, light oil, heavy oil, gas, etc. are used because of the fact that the turndown ratio of the mill cannot be taken when the load is low and the ignitability of the pulverized coal itself is poor.

【０００６】例えば起動時に補助燃料として軽油，重油
を用いる場合には、起動時から１５％負荷までは軽油を
補助燃料としてボイラを焚き上げ、１５％負荷から４０
％負荷までは軽油から重油へ補助燃料を変更して焚き上
げ、４０％負荷以上になると補助燃料の重油と主燃料の
微粉炭を混焼して順次補助燃料の重油量を少なくすると
ともに主燃料の微粉炭量を多くして微粉炭の混焼比率を
上げて実質的な石炭専焼へと移行する。For example, when light oil or heavy oil is used as the auxiliary fuel at the time of starting, the boiler is fired with the light oil as the auxiliary fuel from the time of starting to 15% load and 40% from the 15% load.
When the load exceeds 40%, the auxiliary fuel is changed from light oil to heavy oil and heated. When the load exceeds 40%, the auxiliary fuel heavy oil and the main fuel pulverized coal are mixed and burned to reduce the amount of the auxiliary fuel heavy oil and Increasing the amount of pulverized coal to increase the co-firing ratio of pulverized coal and shifting to practical coal-only combustion.

【０００７】以下、図１０および図１１を用いて微粉炭
焚ボイラの起動時における概要について説明する。図１
０及び図１１は微粉炭焚ボイラの概略系統図および従来
の微粉炭バーナの拡大断面図である。図１０に示す微粉
炭焚ボイラ１をコールドスタートする際は、まず図１１
に示す微粉炭バーナ７の軽油点火バーナ２により、ボイ
ラ負荷の１５％まで焚き上げる。その後に重油起動用バ
ーナ３を点火する。そして、重油起動用バーナ３のみ
で、ボイラ負荷の２５〜３５％まで焚き上げる。その後
にボイラ火炉４の火炉内温度が十分に上つた時点で、図
１０に示すミル５から図１１に示す微粉炭供給管６、微
粉炭バーナ７へ微粉炭燃料を供給して微粉炭ノズル８か
らボイラ火炉４内へ送り、微粉炭専焼へと切り換える。An outline of the pulverized coal burning boiler at the time of starting will be described below with reference to FIGS. 10 and 11. Figure 1
0 and FIG. 11 are a schematic system diagram of a pulverized coal burning boiler and an enlarged sectional view of a conventional pulverized coal burner. When cold starting the pulverized coal burning boiler 1 shown in FIG.
By the light oil ignition burner 2 of the pulverized coal burner 7 shown in Fig. 1, the boiler load is raised to 15%. After that, the heavy oil starting burner 3 is ignited. Then, with only the heavy oil starting burner 3, the boiler load is raised to 25 to 35%. After that, when the temperature inside the furnace of the boiler furnace 4 rises sufficiently, the pulverized coal fuel is supplied from the mill 5 shown in FIG. 10 to the pulverized coal supply pipe 6 and the pulverized coal burner 7 shown in FIG. To the inside of the boiler furnace 4 to switch to the pulverized coal exclusive firing.

【０００８】微粉炭の搬送用媒体は、図１０に示すエア
ヒータ９によつて、ボイラ排ガスと熱交換された後ミル
５に送られ、コールバンカ１０から供給される塊炭に付
着した水分の除去と、ミル５に内蔵した図示していない
分級器の分級エアとして、さらには、ミル５で粉砕され
た微粉炭を微粉炭バーナ７まで搬送するための搬送用空
気として使用される。The pulverized coal transportation medium is heat-exchanged with the boiler exhaust gas by the air heater 9 shown in FIG. 10 and then sent to the mill 5 to remove water adhering to the agglomerates supplied from the coal bunker 10. The air is used as a classifying air for a classifier (not shown) built in the mill 5, and further as a conveying air for conveying the pulverized coal pulverized by the mill 5 to the pulverized coal burner 7.

【０００９】図１１には従来技術の微粉炭バーナ７を示
しているがこの微粉炭バーナ７には、軽油点火バーナ２
と重油起動用バーナ３が取り付けられており、微粉炭バ
ーナ７を構成している。風箱１１内の燃焼用空気は、二
次エアレジスタ１２と三次エアレジスタ１３により、旋
回が加えられた後、ボイラ火炉４内に投入される。一
方、微粉炭は微粉炭供給管６を通り微粉炭バーナ７の微
粉炭ノズル８へ送られるが、その間にベンチユリー１４
を通過するのみで、ほぼ自由噴流に近い状態でボイラ火
炉４内に吹き込まれる。この微粉炭バーナ７には保炎器
１５が設けられ、燃焼用空気の旋回によつて、逆流域が
生じ、火炎の伝播速度以下の流速域で、火炎が保持され
るのみであつた。したがつて微粉炭粒子の拡散は良い
が、一方では火炎が不安定になり、微粉炭バーナ７の空
気側の操作条件に極めて左右されやすい。なお、図１
０，図１１の符号１５は保炎器、１６は重油タンク、１
７は軽油タンクである。一方、ミル５（微粉炭バーナ
７）の負荷が低い領域でミル５から供給される微粉炭−
空気流中の微粉炭濃度（Ｃ／Ａ）が低くなるため、着火
安定性が悪くなる。FIG. 11 shows a pulverized coal burner 7 of the prior art. The pulverized coal burner 7 includes a light oil ignition burner 2
And a heavy oil starting burner 3 are attached to form a pulverized coal burner 7. The combustion air in the wind box 11 is fed into the boiler furnace 4 after being swirled by the secondary air register 12 and the tertiary air register 13. On the other hand, the pulverized coal is sent to the pulverized coal nozzle 8 of the pulverized coal burner 7 through the pulverized coal supply pipe 6, while the bench coal 14
And is blown into the boiler furnace 4 in a state close to a free jet. The pulverized coal burner 7 is provided with the flame stabilizer 15, and the swirling of the combustion air causes a backflow region, and the flame is only retained in the flow velocity region equal to or lower than the flame propagation velocity. Therefore, although the dispersion of the pulverized coal particles is good, the flame becomes unstable on the other hand, and it is extremely susceptible to the operating conditions on the air side of the pulverized coal burner 7. Note that FIG.
0, reference numeral 15 in FIG. 11 is a flame stabilizer, 16 is a heavy oil tank, 1
7 is a light oil tank. On the other hand, pulverized coal supplied from the mill 5 in a region where the load of the mill 5 (pulverized coal burner 7) is low-
Since the pulverized coal concentration (C / A) in the air stream becomes low, the ignition stability becomes poor.

【００１０】この微粉炭粒子の希釈に対処するために、
ミル５からの低Ｃ／Ａ微粉炭流を、慣性力等を利用し
て、濃厚微粉炭流と希薄微粉炭流に分け、濃厚微粉炭流
を微粉炭バーナでの安定燃焼に用いるのが有効である。
図１２において、符号４から１３までは図１１のものと
同一のものを示す。１８はサイクロン式の外部濃縮器、
１９は濃厚微粉炭流路、２０は希薄微粉炭流路、２１は
濃厚微粉炭流、２２は希薄微粉炭流である。このような
構造において、図１１のものと異なる点は、サイクロン
式の外部濃縮器１８によつて微粉炭を濃厚微粉炭流２１
と希薄微粉炭流２２に分離し、濃厚微粉炭流２１は濃厚
微粉炭流路１９より、希薄微粉炭流２２は希薄微粉炭流
路２０よりそれぞれボイラ火炉４内に供給される点であ
る。つまり、微粉炭バーナ７の中心部に濃厚微粉炭流２
１を、その周囲に希薄微粉炭流２２を供給し、その周囲
に燃焼用の２次，３次空気が旋回して供給される。従つ
て、希薄微粉炭流２２の微粉炭は、濃厚微粉炭流２１の
微粉炭により形成される火炎からの輻射熱を効率良く受
けるために、安定燃焼が可能となる。しかしながら、こ
のサイクロン式の外部濃縮器１８による微粉炭流の分離
では、せつかく微粉炭バーナ７の入口で分離濃縮した濃
厚微粉炭流２１が微粉炭バーナ７の出口部分で希薄微粉
炭流路２０の希薄微粉炭流２２と再度混合してしまい好
ましくない。In order to cope with the dilution of the pulverized coal particles,
It is effective to divide the low C / A pulverized coal stream from the mill 5 into a concentrated pulverized coal stream and a lean pulverized coal stream by utilizing inertial force, etc., and use the concentrated pulverized coal stream for stable combustion in the pulverized coal burner. Is.
In FIG. 12, reference numerals 4 to 13 denote the same as those in FIG. 18 is a cyclone type external concentrator,
19 is a dense pulverized coal flow path, 20 is a dilute pulverized coal flow path, 21 is a rich pulverized coal flow, and 22 is a dilute pulverized coal flow. In such a structure, a point different from that of FIG. 11 is that the pulverized coal is concentrated by the cyclone-type external concentrator 18 into a concentrated pulverized coal flow 21.
Is divided into a fine pulverized coal flow 22 and a dense pulverized coal flow 21 is supplied to the boiler furnace 4 from the rich pulverized coal flow passage 19 and a lean pulverized coal flow 22 is supplied to the boiler furnace 4 from the lean pulverized coal flow passage 20, respectively. That is, the concentrated pulverized coal flow 2 is added to the center of the pulverized coal burner 7.
1, and a lean pulverized coal flow 22 is supplied around it, and secondary and tertiary air for combustion is swirl supplied around it. Therefore, the pulverized coal of the lean pulverized coal flow 22 efficiently receives the radiant heat from the flame formed by the pulverized coal of the rich pulverized coal flow 21, and thus stable combustion is possible. However, in the separation of the pulverized coal flow by the cyclone-type external concentrator 18, the dense pulverized coal flow 21 separated and concentrated at the inlet of the pulverized coal burner 7 at the outlet of the pulverized coal burner 7 is diluted with the lean pulverized coal flow passage 20. It is not preferable because it is mixed again with the diluted pulverized coal stream 22.

【００１１】図１３は内部濃縮器を備えた微粉炭バーナ
を示す。図１３において、符号３から２２は図１１，図
１２のものと同一である。２３は可動プラグ、２４はガ
イドシリンダ、２５は縮流部である。低負荷時において
は、図１３に示すように可動プラグ２３をガイドシリン
ダ２４内に挿入した状態とする。この場合、微粉炭噴流
は、ガイドシリンダ２４の影響で濃厚微粉炭流路１９に
沿うように流れ、縮流部２５において、微粉炭粒子は直
進し、一方空気は反転して希薄微粉炭流路２０、つまり
バーナ中心部へ流れ込む。このために保炎器１５の内側
に濃厚微粉炭流２１が流れるようになる。高負荷時にお
いては、微粉炭バーナ７の入口で微粉炭濃度が十分着火
に必要な濃度に達しているので可動プラグ２３を引抜き
１次空気流量の増加に伴う圧力損失の増加を低減する。
このような内部濃縮器での流れを調べてみると、図１４
に示すように縮流部２５の後流において剥離が生じ、こ
れが原因で微粉炭バーナ出口部で高流速化するととも
に、高速噴流が周囲の空気を同伴するために、せつかく
濃縮した微粉炭も、急速に稀薄化されてしまう。この現
象のために、微粉炭バーナ出口部における着火に必要
な、高濃度、低流速領域が縮小される。この現象を回避
するには、縮流部２５の後流側長さＬを延長すればよ
く、ちなみに、この例では、縮流部の後流側長さＬとそ
のステツプ部高さとの比率Ｌ／Ｈを１９以上にすれば高
濃厚微粉炭流路１９の濃厚微粉炭流２１が再付着して、
微粉炭バーナの出口での流速の低下が図れた。ただし、
このように十分な助走距離（Ｌ）が必要なことから、従
来の微粉炭バーナに容易に取付けることはできない。FIG. 13 shows a pulverized coal burner equipped with an internal concentrator. In FIG. 13, reference numerals 3 to 22 are the same as those in FIGS. 11 and 12. Reference numeral 23 is a movable plug, 24 is a guide cylinder, and 25 is a contracting portion. When the load is low, the movable plug 23 is inserted into the guide cylinder 24 as shown in FIG. In this case, the pulverized coal jet flow flows along the rich pulverized coal flow passage 19 under the influence of the guide cylinder 24, and in the contracting portion 25, the pulverized coal particles go straight, while the air is reversed to dilute the pulverized coal flow passage. 20, it flows into the center of the burner. Therefore, the rich pulverized coal flow 21 flows inside the flame stabilizer 15. At the time of high load, the pulverized coal concentration at the inlet of the pulverized coal burner 7 has reached a sufficient concentration for ignition, so that the movable plug 23 is pulled out and the increase in pressure loss due to the increase in the primary air flow rate is reduced.
Examining the flow in such an internal concentrator, FIG.
As shown in (4), separation occurs in the wake of the contracting section 25, which causes a high flow velocity at the pulverized coal burner outlet, and since the high-speed jet entrains the surrounding air, the pulverized coal that has been concentrated to some extent is also removed. , Is rapidly diluted. Due to this phenomenon, the high-concentration, low-velocity region required for ignition at the pulverized coal burner outlet is reduced. In order to avoid this phenomenon, it is sufficient to extend the wake side length L of the contracting section 25. Incidentally, in this example, the ratio L of the wake side length L of the contracting section and the step height thereof is L. If / H is set to 19 or more, the dense pulverized coal flow 21 of the highly concentrated pulverized coal flow passage 19 is reattached,
The flow velocity at the outlet of the pulverized coal burner was reduced. However,
Since a sufficient run-up distance (L) is required in this way, it cannot be easily attached to a conventional pulverized coal burner.

【００１２】[0012]

【発明が解決しようとする課題】このように補助燃料を
用いる微粉炭バーナでは、頻繁な起動停止運転毎に補助
燃料の使用量が増加し、直接ミルから微粉炭バーナへ微
粉炭−空気流を供給する燃焼システムではミル（バー
ナ）負荷が低い場合、微粉炭バーナの着火性が悪くなる
ために未燃分が増加し、サイクロン式の外部濃縮器で高
濃度化すると動力費用が増加する等の欠点があつた。本
発明はかかる従来の欠点を解消しようとするもので、そ
の目的とするところは、補助燃料を削減し、しかも微粉
炭バーナの着火安定性を向上させることにより、ＤＳＳ
運転での低負荷運転を行なうことができる微粉炭バーナ
を提供することにある。As described above, in the pulverized coal burner using the auxiliary fuel, the amount of the auxiliary fuel used increases with each frequent start / stop operation, and the pulverized coal-air flow is directly supplied from the mill to the pulverized coal burner. In the combustion system to be supplied, when the load of the mill (burner) is low, the ignitability of the pulverized coal burner deteriorates and the unburned content increases, and if the concentration is increased by the cyclone type external concentrator, the power cost will increase. There was a flaw. The present invention is intended to solve the above-mentioned conventional drawbacks, and an object of the present invention is to reduce the auxiliary fuel and improve the ignition stability of the pulverized coal burner to improve the DSS.
An object of the present invention is to provide a pulverized coal burner capable of performing low load operation during operation.

【００１３】[0013]

【課題を解決するための手段】本発明は前述の目的を達
成するために、縮流部の後流に濃厚微粉炭流路と希薄微
粉炭流路を連絡する開口を設けたのである。In order to achieve the above-mentioned object, the present invention provides an opening for connecting the dense pulverized coal flow passage and the lean pulverized coal flow passage in the downstream of the contracting portion.

【００１４】[0014]

【作用】濃厚微粉炭流路の濃厚微粉炭流から開口を経て
希薄微粉炭流路の希薄微粉炭流側へ空気や一部の微粉炭
を分離できるので、濃厚微粉炭流の微粉炭濃度を濃くす
ることによつて達成される。[Operation] Since air and a part of pulverized coal can be separated from the dense pulverized coal flow in the rich pulverized coal flow path through the opening to the lean pulverized coal flow side in the lean pulverized coal flow channel, the pulverized coal concentration in the dense pulverized coal flow can be changed. Achieved by thickening.

【００１５】[0015]

【実施例】以下、本発明の実施例を図面を用いて説明す
る。図１は本発明の実施例に係る微粉炭バーナの縦断面
図、図２は図１の先端部を拡大した詳細図、図３、図４
は図２の他の実施例を示す詳細図、図５は外部濃縮器を
備えた微粉炭バーナの系統図、図６は図５の微粉炭バー
ナを拡大した詳細図、図７は縦軸に圧力、横軸に縮流部
の長さを示した特性曲線図、図８は縦軸に圧力損失、濃
縮倍率、横軸に可動プラグの開度を示した特性曲線図、
図９は縦軸に流速、横軸にバーナ負荷、可動プラグの開
度を示した特性曲線図である。図１から図６において符
号３から２５は従来のものと同一のものを示す。２６は
縮流部２５の下流側に設けた開口で、濃厚微粉炭流路１
９と希薄微粉炭流路２０を連絡するバイパス通路でもあ
る。２７は可動円筒、２８は開口２６の開口面積を変え
る調整器である。Embodiments of the present invention will be described below with reference to the drawings. 1 is a vertical cross-sectional view of a pulverized coal burner according to an embodiment of the present invention, FIG. 2 is an enlarged detailed view of a tip portion of FIG. 1, FIG. 3 and FIG.
2 is a detailed view showing another embodiment of FIG. 2, FIG. 5 is a system diagram of a pulverized coal burner equipped with an external concentrator, FIG. 6 is an enlarged detailed diagram of the pulverized coal burner of FIG. 5, and FIG. FIG. 8 is a characteristic curve diagram showing the pressure and the length of the contracted portion on the horizontal axis, and FIG. 8 is a characteristic curve diagram showing the pressure loss, the concentration ratio on the vertical axis and the opening of the movable plug on the horizontal axis.
FIG. 9 is a characteristic curve diagram showing the flow velocity on the vertical axis, the burner load on the horizontal axis, and the opening of the movable plug. In FIGS. 1 to 6, reference numerals 3 to 25 are the same as conventional ones. 26 is an opening provided on the downstream side of the contracting section 25, which is the dense pulverized coal flow path 1
It is also a bypass passage that connects the dilute pulverized coal flow path 20 with the fuel cell 9. Reference numeral 27 is a movable cylinder, and 28 is an adjuster for changing the opening area of the opening 26.

【００１６】図１，図２において、微粉炭とその搬送用
の１次空気は図１の微粉炭供給管６から微粉炭バーナ７
に流入する。そして、内部濃縮器を構成する可動プラグ
２３の周りを流れ、ガイドシリンダ２４の外側を通過し
た後、縮流部２５で濃厚微粉炭流２１と希薄微粉炭流２
２の２つの流れに分離される。その後、濃厚微粉炭流２
１はガイドシリンダ２４の外側を流れ、一方希薄微粉炭
流２１はガイドシリンダ２４の内側を流れ、ボイラ火炉
４内に投入され、火炎を形成する。この様に微粉炭の濃
縮は主に、図１，図２の縮流部２５で行なわれ縮流部２
５の後流の流れは図１４でも説明したように、縮流部２
５の後流で剥離を生じ、これが原因で局所流速は増大す
る。そこで、本発明の実施例では、縮流部２５の後流に
開口２６を設けて、この開口２６をバイパス通路にする
ことにより濃厚微粉炭流２１から一部の微粉炭と空気を
抜き出して、希薄微粉炭流路２０の希薄微粉炭流２２へ
流すようにする。この構造を採用することによつて、微
粉炭の分離効率は変らないまま、濃厚微粉炭流２１の微
粉炭濃度を向上させることができる。また、負荷が高
く、バーナ入口の微粉炭濃度が着火に十分な濃度になつ
た場合は、縮流部２５における圧力損失を低下させるた
めに、可動プラグ２３を引抜く操作が必要となる。そこ
で、この動作に連動するように可動円筒２７もスライド
して、開口２６を閉塞する。これは、高負荷時に濃厚微
粉炭流路１９の微粉炭流量が低下して逆火しないために
必要である。1 and 2, the pulverized coal and the primary air for carrying the same are supplied from the pulverized coal supply pipe 6 to the pulverized coal burner 7 in FIG.
Flow into. Then, after flowing around the movable plug 23 constituting the internal concentrator and passing outside the guide cylinder 24, the dense pulverized coal stream 21 and the lean pulverized coal stream 2 are condensed in the contracting section 25.
It is separated into two streams of two. After that, dense pulverized coal flow 2
1 flows outside the guide cylinder 24, while the lean pulverized coal flow 21 flows inside the guide cylinder 24 and is charged into the boiler furnace 4 to form a flame. As described above, the pulverized coal is mainly concentrated in the contracting section 25 shown in FIGS. 1 and 2.
As for the flow of the wake of No. 5, as described in FIG.
In the wake of No. 5, separation occurs, which causes the local flow velocity to increase. Therefore, in the embodiment of the present invention, an opening 26 is provided in the downstream of the contracting portion 25, and a part of the pulverized coal and air is extracted from the dense pulverized coal flow 21 by using this opening 26 as a bypass passage. The diluted pulverized coal flow path 20 is made to flow to the diluted pulverized coal flow 22. By adopting this structure, the pulverized coal concentration of the dense pulverized coal stream 21 can be improved without changing the separation efficiency of the pulverized coal. Further, when the load is high and the pulverized coal concentration at the burner inlet has reached a sufficient concentration for ignition, it is necessary to pull out the movable plug 23 in order to reduce the pressure loss in the contracting section 25. Therefore, the movable cylinder 27 is also slid so as to interlock with this operation to close the opening 26. This is necessary because the flow rate of the pulverized coal in the dense pulverized coal flow passage 19 does not decrease and the flashback does not occur when the load is high.

【００１７】図３は図２の他の実施例を示すもので、図
２のものと異なる点は、図２のものにおいては開口２６
を可動円筒２７の移動によつて開口面積を変えたが、図
３のものにおいては開口２６を調整器２８を破線のよう
に移動させることによつて開口面積を変えるようにした
もので、他の説明は図１、図２のものと同一である。FIG. 3 shows another embodiment of FIG. 2 and is different from that of FIG. 2 in that the opening 26 in FIG.
The opening area was changed by moving the movable cylinder 27. However, in FIG. 3, the opening area is changed by moving the opening 26 by moving the adjuster 28 as shown by the broken line. Is the same as that of FIG. 1 and FIG.

【００１８】図４は他の実施例を示すもので、図２、図
３のものにおいては可動円筒２７や調整器２８の移動に
よつて開口２６の開口面積を変えたが、図４のものは縮
流部２５を実線の位置から破線の位置へ移動させること
によつて開口面積を変えるようにしたもので、他の説明
は図２、図３のものと同一である。FIG. 4 shows another embodiment. In FIGS. 2 and 3, the opening area of the opening 26 is changed by the movement of the movable cylinder 27 and the adjuster 28. Is to change the opening area by moving the contracting portion 25 from the position indicated by the solid line to the position indicated by the broken line, and other explanations are the same as those in FIGS.

【００１９】図５および図６は外部濃縮器を備えた微粉
炭バーナを示すもので、図５は燃料系統図、図６は微粉
炭バーナを示す。通常微粉炭を主燃料とする大型の燃焼
装置においては、複数の微粉炭バーナが配置されるが、
１台のミルから微粉炭供給管６を分岐して各々の微粉炭
バーナ７に送るシステムとなる。ここでは、ミルからの
微粉炭供給管６を外部濃縮器１８で受け濃厚微粉炭流路
１９と希薄微粉炭流路２０に分けて各々の微粉炭バーナ
７に接続されている。図６には、微粉炭バーナ７の外部
に外部濃縮器１８があり、濃厚微粉炭流路１９が微粉炭
バーナ７の中心部に接続され、一方、希薄微粉炭流路２
０がその周囲に接続されバーナに、濃厚微粉炭流路１９
と希薄微粉炭流路２０の途中に縮流部２５が配置されそ
の下流には開口２６が設けられている。そして開口面積
は可動円筒２７で調整する。この調整機構によつて、微
粉炭バーナ７毎別に希薄微粉炭流２２の濃度調整と、濃
厚微粉炭流２１のバーナ出口流速の調整ができる。5 and 6 show a pulverized coal burner provided with an external concentrator, FIG. 5 shows a fuel system diagram, and FIG. 6 shows a pulverized coal burner. In a large-scale combustion device that normally uses pulverized coal as the main fuel, multiple pulverized coal burners are arranged,
This is a system in which the pulverized coal supply pipe 6 is branched from one mill and sent to each pulverized coal burner 7. Here, the pulverized coal supply pipe 6 from the mill is received by an external concentrator 18 and divided into a dense pulverized coal flow passage 19 and a lean pulverized coal flow passage 20 and connected to each pulverized coal burner 7. In FIG. 6, an external concentrator 18 is provided outside the pulverized coal burner 7, and a dense pulverized coal flow passage 19 is connected to the center of the pulverized coal burner 7, while the lean pulverized coal flow passage 2 is provided.
0 is connected to the periphery of the burner and the dense pulverized coal flow path 19
A reduced flow portion 25 is arranged in the middle of the lean pulverized coal flow passage 20, and an opening 26 is provided downstream thereof. The opening area is adjusted by the movable cylinder 27. With this adjusting mechanism, it is possible to adjust the concentration of the lean pulverized coal flow 22 and the burner outlet flow velocity of the rich pulverized coal flow 21 for each pulverized coal burner 7.

【００２０】以下、発明者等が行なつた実験データを紹
介する。図７には濃厚微粉炭流路１９の壁面静圧分布を
示した。図中の曲線Ａは従来型微粉炭バーナ，曲線Ｂは
本発明の実施例における壁面静圧分布を示している。圧
力は縮流部２５において最も低下し、流速が増加してお
り、その後縮流部２５では、しばらく圧力が回復せず、
この部分で剥離していることが推測される。その後圧力
が回復するとともに、ゆるやかに圧力減少する。この図
７から曲線Ｂの方が剥離領域が狭くなつているのが分か
る。これは開口２６によつて空気のみが希薄微粉炭流路
２０に流れやすくなるために剥離領域が縮小したことに
よるものと考えられる。従つて、この効果によれば縮流
部２５の下流側長さを短くしても微粉炭バーナ出口部に
おける流れは変わらないために、濃縮器自体を小型化で
きることから装置の軽量コストダウンが計れる。新設の
微粉炭バーナに適応する場合においては微粉炭バーナを
短くすることができるために、風箱を軽量化できボイラ
燃焼装置の総合的なコストダウンを計ることができる。The experimental data conducted by the inventors will be introduced below. FIG. 7 shows the static pressure distribution on the wall surface of the dense pulverized coal flow path 19. Curve A in the figure shows the conventional pulverized coal burner, and curve B shows the static pressure distribution on the wall surface in the embodiment of the present invention. The pressure is the lowest in the contracting section 25 and the flow velocity is increasing. After that, in the contracting section 25, the pressure is not recovered for a while,
It is presumed that peeling occurred at this portion. After that, the pressure recovers and the pressure gradually decreases. It can be seen from FIG. 7 that the peeling region of the curve B is narrower. It is considered that this is because only the air easily flows into the lean pulverized coal flow path 20 through the opening 26, and thus the separation area is reduced. Therefore, according to this effect, the flow at the outlet of the pulverized coal burner does not change even if the length of the downstream side of the contracting section 25 is shortened, so that the concentrator itself can be downsized and the cost of the device can be reduced. .. When the new pulverized coal burner is applied, the pulverized coal burner can be shortened, so that the wind box can be made lighter and the overall cost of the boiler combustion device can be reduced.

【００２１】図８には、可動プラグ２３の位置と縮流部
２５における圧力損失ΔＰと濃縮倍率ηの関係を示し
た。ここにηは、微粉炭バーナ出口濃縮側の微粉炭濃度
（Ｃ／Ａ０）と微粉炭バーナ入り口部分における微粉炭
濃度（Ｃ／Ａｉ）の比率を示す。図中可動プラグ２３の
位置０％は全閉、１００％は全開状態を示す。圧力損失
に関しては若干開口２６がある方が曲線Ｂで示すように
高いが殆ど差は無く、濃縮倍率に関しては、開口２６の
ある方が曲線Ｂで示すように高い値になつている。図中
破線で同じ圧力損失での濃縮倍率をηＡとηＢで比較し
てみると、開口２６のあるほうがやはり高く、濃縮効果
の高いことが分かる。FIG. 8 shows the relationship between the position of the movable plug 23, the pressure loss ΔP at the contracting portion 25 and the concentration ratio η. Here, η indicates the ratio of the pulverized coal concentration (C / A0) on the pulverized coal burner outlet concentration side and the pulverized coal concentration (C / Ai) at the pulverized coal burner inlet portion. In the figure, the position 0% of the movable plug 23 is fully closed and 100% is fully open. Regarding the pressure loss, there is a little difference with the opening 26 as shown by the curve B, but there is almost no difference, and regarding the concentration ratio, the value with the opening 26 is high as shown by the curve B. Comparing the concentration ratios of ηA and ηB at the same pressure loss with the broken line in the figure, it can be seen that the presence of the opening 26 is still high and the concentration effect is high.

【００２２】図９においては、バーナ負荷と濃厚側のバ
ーナ出口流速の関係について示す。微粉炭の着火保炎に
は、バーナ出口部分での流速は微粉炭の粒度や、石炭中
の揮発分の比率よつても異なるが低いほうがよい。しか
し必要以上に低い場合、微粉炭供給管の中に火炎が戻り
（逆火し）微粉炭バーナを焼損してしまう可能性があ
り、バーナ負荷に応じて流速の調整が不可欠である。図
中のハツチングで示した領域は、安定燃焼が可能な流速
域を示す。図中の曲線Ａは、従来型微粉炭バーナの特性
を示し、図中の曲線Ｂは開口２６を全開にした場合の流
速条件を示す。本実施例のうち開口２６を全開にしたま
まバーナ負荷を増加すると、流速が減少して、逆火の可
能性があることが分かる。従つて、負荷を変化させる場
合には、開口２６を開閉させる操作を行い流速が安定燃
焼域に入るように調整する必要がある。負荷が増加する
場合には、開口２６の断面積を縮小する操作を行い図中
Ｃ点からＤ点を結ぶ破線Ｂ′で示すものが操作線とな
り、開口２６を開閉することによつて安定燃焼範囲で運
転することができる。FIG. 9 shows the relationship between the burner load and the burner outlet flow velocity on the rich side. For the ignition and flame protection of pulverized coal, the flow velocity at the burner outlet is preferably low, although it depends on the particle size of the pulverized coal and the ratio of volatile components in the coal. However, if it is lower than necessary, the flame may return (backfire) in the pulverized coal supply pipe and burn the pulverized coal burner, and it is essential to adjust the flow velocity according to the burner load. The hatched area in the figure shows the flow velocity area where stable combustion is possible. Curve A in the figure shows the characteristics of the conventional pulverized coal burner, and curve B in the figure shows the flow velocity condition when the opening 26 is fully opened. It can be seen that when the burner load is increased while the opening 26 is fully opened in the present embodiment, the flow velocity decreases and there is a possibility of flashback. Therefore, when changing the load, it is necessary to perform an operation of opening and closing the opening 26 to adjust the flow velocity so as to enter the stable combustion region. When the load increases, the operation of reducing the cross-sectional area of the opening 26 is performed, and the operation line is shown by the broken line B ′ connecting points C and D in the figure, and stable combustion is achieved by opening and closing the opening 26. Can drive in a range.

【００２３】[0023]

【発明の効果】本発明によれば、低負荷時や極低負荷時
においても火炎の安定性が向上し、油，ガス等の補助燃
料の使用量が低下することから、経費の大幅な節減がで
きる。さらに、外部縮器等の補機を使用しないため省ス
ペース化が計られ、特に既設の微粉炭バーナへの改造に
適用できる。EFFECTS OF THE INVENTION According to the present invention, the stability of the flame is improved even under a low load or an extremely low load, and the amount of auxiliary fuel such as oil or gas used is reduced, resulting in a significant cost saving. You can Furthermore, since auxiliary equipment such as an external compressor is not used, space can be saved, and it can be applied especially to the modification of an existing pulverized coal burner.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の実施例に係る微粉炭バーナの縦断面図
である。FIG. 1 is a vertical sectional view of a pulverized coal burner according to an embodiment of the present invention.

【図２】図１の先端部を拡大した詳細図である。FIG. 2 is an enlarged detailed view of the tip portion of FIG.

【図３】図２の他の実施例を示す詳細図である。FIG. 3 is a detailed view showing another embodiment of FIG.

【図４】図３の他の実施例を示す詳細図である。FIG. 4 is a detailed view showing another embodiment of FIG.

【図５】外部濃縮器を備えた微粉炭バーナの系統図であ
る。FIG. 5 is a system diagram of a pulverized coal burner equipped with an external concentrator.

【図６】図５の微粉炭バーナを拡大した詳細図である。FIG. 6 is an enlarged detailed view of the pulverized coal burner of FIG.

【図７】縦軸に圧力、横軸に縮流部の長さを示した特性
曲線図である。FIG. 7 is a characteristic curve diagram showing the pressure on the vertical axis and the length of the contracting portion on the horizontal axis.

【図８】縦軸に圧力損失と濃縮倍率、横軸に可動プラグ
の開度を示した特性曲線図である。FIG. 8 is a characteristic curve diagram showing the pressure loss and the concentration ratio on the vertical axis and the opening of the movable plug on the horizontal axis.

【図９】縦軸に流速、横軸にバーナ負荷、可動プラグの
開度を示した特性曲線図である。FIG. 9 is a characteristic curve diagram showing the flow velocity on the vertical axis, the burner load on the horizontal axis, and the opening of the movable plug.

【図１０】微粉炭焚ボイラの概略系統図である。FIG. 10 is a schematic system diagram of a pulverized coal burning boiler.

【図１１】従来の微粉炭バーナの拡大断面図である。FIG. 11 is an enlarged sectional view of a conventional pulverized coal burner.

【図１２】従来の外部濃縮器を備えた微粉炭バーナの断
面図である。FIG. 12 is a sectional view of a pulverized coal burner provided with a conventional external concentrator.

【図１３】従来の内部濃縮器を備えた微粉炭バーナの断
面図である。FIG. 13 is a sectional view of a pulverized coal burner provided with a conventional internal concentrator.

【図１４】従来の縮流部の拡大断面図である。FIG. 14 is an enlarged cross-sectional view of a conventional contracting section.

【符号の説明】[Explanation of symbols]

１９ 濃厚微粉炭流路 ２０ 希薄微粉炭流路 ２５ 縮流部 ２６ 開口 19 Dense Pulverized Coal Flow Path 20 Dilute Pulverized Coal Flow Path 25 Constricted Flow Section 26 Opening

───────────────────────────────────────────────────── フロントページの続き (72)発明者 森田 茂樹 広島県呉市宝町６番９号 バブコツク日立 株式会社呉工場内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shigeki Morita 6-9 Takaracho, Kure City, Hiroshima Prefecture Babkotsk Hitachi Ltd. Kure Factory

Claims (1)

【特許請求の範囲】 【請求項１】 濃厚微粉炭流路と希薄微粉炭流路の途中
に縮流部を設け、微粉炭を濃縮して燃焼させるものにお
いて、前記縮流部の後流に濃厚微粉炭流路と希薄微粉炭
流路を連絡する開口を設けたことを特徴とする微粉炭バ
ーナ。Claim: What is claimed is: 1. A compact flow section is provided in the middle of the dense pulverized coal flow path and the lean pulverized coal flow path for condensing and burning the pulverized coal. A pulverized coal burner having an opening for connecting the dense pulverized coal flow channel and the lean pulverized coal flow channel.