【０００１】
【発明の属する技術分野】
本発明は循環流動層ボイラに関し、特に複数の蒸発管を並置して形成した管壁で燃焼室を区画し、同管壁の下部を覆った耐火材を設け、循環する流動材や未燃灰等の粒子が前記管壁に沿って下降するように構成されている循環流動層ボイラにおいて、前記下降する粒子と蒸発管の衝突力等を前記耐火材の上端縁に一定の工夫を施して調整し、同蒸発管の摩耗、減肉を低減するようにした循環流動層ボイラに関するものである。
【０００２】
【従来の技術】
従来の循環流動層ボイラの概要について、図３及び図４の記載に基づいて説明する。
図３は従来の循環流動層ボイラの燃焼室近傍を概略的に示し、（ａ）は概略構造図、（ｂ）は（ａ）の矢視Ａ−Ａ図、（ｃ）は（ｂ）のＣ部拡大図、（ｄ）は（ａ）のＢ部の機能説明図であり、図４は図３の要部に変更を加えた改良形態の概要を示し、（ａ）は要部の構造を示す断面図、（ｂ）は（ａ）に示すプロテクタの斜視図である。
【０００３】
図３、図４において、１は循環流動層ボイラ本体、２は蒸発管で、互いに隣接して配置された蒸発管２は間隔片２ａを介して連接され、燃焼室を区画する管壁８を構成している。
【０００４】
３は耐火材で、前記管壁８の下方部分で同管壁８を覆って配置され、火力の強い燃焼室の下部で、前記管壁８を構成する蒸発管２を高温から遮蔽すると共に、後述する流動材や未燃灰等の粒子６により蒸発管２が摩耗しないように保護する役割を負っている。
【０００５】
５は風箱、７はヘッダを示し、これらを介して供給される燃焼空気Ｅを、空気ノズルにより循環流動層ボイラ本体１内部に吹き込み、外部から供給される石炭Ｆ及び下流から帰還される未燃灰Ｇ、そして予め循環流動層ボイラ本体１内部に収納された流動材（けい砂などの不活性粉粒体または石灰石などの脱硫剤からなる）等を混合して流動化し、流動層を形成して燃焼を促進する。
【０００６】
このようにして形成された循環流動層ボイラ本体１内の流動材や未燃灰等の粒子６の挙動について注目すると、同粒子６は循環流動層ボイラ本体１の中央部で上昇するが、蒸発管２等で形成される管壁８の近傍では同管壁８に沿って下降する粒子６がほとんどであり、この上昇流と下降流により同循環流動層ボイラ本体１内で前記流動材や未燃灰等の粒子６の循環が行われる。
【０００７】
耐火材３の上端は、管壁に対して段差状となった水平面で形成された耐火材上縁３ａとなっているので、前記管壁８に沿って下降する粒子６は、図３（ｄ）に示すように耐火材上縁３ａに沿って湾曲して下降する粒子６、これから分流して耐火材上縁３ａと蒸発管２の間でうず流を発生する粒子６ａ、また上方から落下して耐火材上縁３ａに当たり、進行方向を直角方向を含む多方向に折り曲げ変化する粒子６ｂ等に分かれ、このうず流を発生する粒子６ａ、及び方向を折り曲げ変換される粒子６ｂ等との衝突により、蒸発管２に局部的な摩耗が生じることとなる。
【０００８】
このうず流をなす粒子６ａ、及び方向変換する粒子６ｂ等により蒸発管２に生じる摩耗を防ぐための対策として、この部位に相当する蒸発管２の表面に耐摩耗性部材の皮膜の溶射を施したり、図４に示すように耐火材３の上端部で、前記耐火材上縁３ａの直上に同耐火材３から連続させて半割れ状の金属板で形成したプロテクタ９を配置し、同プロテクタ９で蒸発管２を密着して覆うことにより、前記耐火材上縁３ａで発生するうず流や方向転換等による流動材や未燃灰等の粒子６ａ、６ｂの衝撃に起因する蒸発管２の摩耗、減肉を防止するようにしたものが提案されるに至っている。
【０００９】
【発明が解決しようとする課題】
しかしながら、前記のようなプロテクタ９の採用、または耐摩耗性部材の皮膜の溶射等を行っても、前記粒子６ａ、及び粒子６ｂ等による摩耗を完全に防止することは不可能であり、特に管壁の隅部等における蒸発管２の摩耗、減肉は、管壁の中央寄りのものに比べて大きく、装置の規模、又は運転状況等によりその大きさにばらつきは有るものの、半年〜１年程のピッチで、耐摩耗性部材の皮膜の溶射を点検したり、再溶射したり、プロテクタの取り替え、また、耐火材のかさ上げ等の保守が必要となる。
【００１０】
本発明は、このような従来のものにおける問題点の解消を目指し、耐火材の上縁側において、流動材や未燃灰等の粒子により蒸発管に生じる摩耗、減肉を抑制することにより、プロテクタの採用を不要とし、耐摩耗性部材の皮膜の再溶射等の保守作業のピッチの長期化を図るようにした循環流動層ボイラを提供することを課題とするものである。
【００１１】
【課題を解決するための手段】
本発明は前記した課題を解決すべくなされたもので、複数の蒸発管を並置して形成した管壁で燃焼室を区画し、同管壁の下部を覆った耐火材を設け、循環する流動材や未燃灰等の粒子が前記管壁に沿って下降するようにされた循環流動層ボイラにおいて、前記耐火材はその上端縁を水平な端面で形成し、同端面に前記管壁に沿って燃焼室の周方向に延びる堰を設けた循環流動層ボイラを提供するものである。
【００１２】
すなわち本発明によれば、管壁の下部を覆って設けられた耐火材は、その上端縁を水平な端面で形成すると共に、この端面には管壁に沿って燃焼室の周方向に延びる堰を設けているので、この堰に管壁に沿って下降した流動材や未燃灰等の粒子が堆積され、次いで前記下降する流動材や未燃灰等の粒子のうち耐火材上縁と蒸発管の間でうず流を発生しようとする粒子、また上方から落下してきて進行方向を折り曲げ変化しょうとする粒子等が、前記堰に堆積された粒子により運動エネルギを吸収され、蒸発管に対する摩擦力を削がれ、蒸発管の局部的な摩耗、減肉が抑制されることになる。
【００１３】
【発明の実施の形態】
本発明の実施の一形態について図１及び図２に基づいて説明する。
図１は本実施の形態に係る循環流動層ボイラの燃焼室下部における耐火材設置部位の一部を示す概略図、図２は図１の一部における粒子の挙動を説明する説明図である。
【００１４】
本実施の形態は従来の技術として図３、図４で説明したものにおいて、耐火材３の上端面に新たな工夫を加え、これにより管壁に沿って下降する流動材や未燃灰等の粒子と蒸発管との衝突エネルギを吸収するようにしたものであり、その他の構成は前記従来のものと同一であるので、説明が冗長にならないように、前記従来のものと同一の部位については前記従来のものの説明を援用し、かつ、本実施の形態に特有の点は前記従来のものに対応させて２０台の符号を付して示すことにより重複する説明を省略する。
【００１５】
すなわち、本実施の形態においては、多数の蒸発管２２を間隔片２２ａで連結して管壁を形成し、その下部を耐火材２３で覆い、かつ蒸発管２２は耐火材２３で覆われる上端側近傍における表面に耐摩耗性部材の皮膜２２ｂを溶射し、流動材や未燃灰等の粒子のうず流等による摩耗に備えている。
【００１６】
そして本実施の形態において特に注目を要する点は、前記耐火材２３はその上端縁２３ａを水平な端面で形成し、かつ、この端面には管壁に沿って燃焼室の周方向に延びる堰３０を設けたことである。
【００１７】
前記のように構成された本実施の形態によれば、管壁の下部を覆って設けられた耐火材２３は、前記したようにその上端縁２３ａを水平な端面で形成すると共に、この端面には管壁に沿って燃焼室の周方向に延びる堰３０を設けているので、管壁に沿って下降した流動材や未燃灰等の粒子２６が、この堰３０内に堆積される。
【００１８】
先行した粒子２６が堰３０内に堆積されると、後続して下降する流動材や未燃灰等の粒子２６のうち耐火材２３の上端縁２３ａと蒸発管２２の間でうず流を発生しようとする粒子２６ａ、また上方から落下してきて進行方向を直角方向を含めて多方向に折り曲げ変化しょうとする粒子２６ｂ等が、前記堰３０内に堆積された粒子をクッションにして運動エネルギを吸収されることになる。
【００１９】
かくして本実施の形態によれば、前記粒子２６ａ、２６ｂ等は、蒸発管２２に対する摩擦力を削がれ、蒸発管２２の局部的な摩耗、減肉が抑制されて蒸発管２２の寿命の長期化を図ることが出来る。
【００２０】
以上、本発明を図示の実施の形態について説明したが、本発明はかかる実施の形態に限定されず、本発明の範囲内でその具体的構造に種々の変更を加えてよいことはいうまでもない。
【００２１】
【発明の効果】
以上、本出願の発明によれば、複数の蒸発管を並置して形成した管壁で燃焼室を区画し、同管壁の下部を覆った耐火材を設け、循環する流動材や未燃灰等の粒子が前記管壁に沿って下降するようにされた循環流動層ボイラにおいて、前記耐火材はその上端縁を水平な端面で形成し、同端面に前記管壁に沿って燃焼室の周方向に延びる堰を設けて循環流動層ボイラを構成しているので、管壁の下部を覆って設けられた耐火材は、その上端縁を水平な端面で形成し、かつ、この端面に管壁に沿って燃焼室の周方向に延びる堰を設けたことにより、この堰に管壁に沿って下降した流動材や未燃灰等の粒子が堆積され、次いで前記下降する流動材や未燃灰等の粒子のうち耐火材上縁と蒸発管の間でうず流を発生しようとする粒子、また上方から落下してきて進行方向を折り曲げ変化しょうとする粒子等が、前記堰に堆積された粒子をクッションにして運動エネルギを吸収され、蒸発管に対する摩擦力を削がれ、蒸発管の局部的な摩耗、減肉が抑制されて長期間の使用に耐え得る好適な循環流動層ボイラを得ることが出来たものである。
【図面の簡単な説明】
【図１】本発明の実施の一形態に係る循環流動層ボイラの燃焼室下部における耐火材設置部位の一部を示す概略図である。
【図２】図１の一部における粒子の挙動を説明する説明図である。
【図３】従来の循環流動層ボイラの燃焼室近傍を概略的に示し、（ａ）は概略構造図、（ｂ）は（ａ）の矢視Ａ−Ａ図、（ｃ）は（ｂ）のＣ部拡大図、（ｄ）は（ａ）のＢ部の機能説明図である。
【図４】図３の要部に変更を加えた改良形態の概要を示し、（ａ）は要部の構造を示す断面図、（ｂ）は（ａ）に示すプロテクタの斜視図である。
【符号の説明】
１ 循環流動層ボイラ本体
２ 蒸発管
２ａ 間隔片
３ 耐火材
３ａ 耐火材上縁
４ 空気ノズル
５ 風箱
６ 粒子
６ａ 粒子
６ｂ 粒子
７ ヘッダ
８ 管壁
９ プロテクタ
９ａ プロテクタ上縁
２２ 蒸発管
２２ａ 間隔片
２２ｂ 皮膜
２３ 耐火材
２３ａ 上端縁
２６ 粒子
２６ａ 粒子
２６ｂ 粒子
３０ 堰[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a circulating fluidized bed boiler, in particular, a combustion chamber is defined by a pipe wall formed by juxtaposing a plurality of evaporating pipes, a refractory material covering a lower portion of the pipe wall is provided, and a circulating fluidized material and unburned ash are provided. In a circulating fluidized bed boiler configured such that particles such as descend along the pipe wall, the collision force between the descending particles and the evaporating tube is adjusted by applying a certain measure to the upper edge of the refractory material. Further, the present invention relates to a circulating fluidized-bed boiler that reduces wear and wall loss of the evaporating tube.
[0002]
[Prior art]
An outline of a conventional circulating fluidized bed boiler will be described with reference to FIGS.
3A and 3B schematically show the vicinity of a combustion chamber of a conventional circulating fluidized bed boiler, where FIG. 3A is a schematic structural view, FIG. 3B is an AA view of FIG. FIG. 4D is a functional explanatory view of a part B of FIG. 3A, and FIG. 4 is a schematic view of an improved embodiment in which a main part of FIG. 3 is changed, and FIG. And (b) is a perspective view of the protector shown in (a).
[0003]
3 and 4, reference numeral 1 denotes a circulating fluidized bed boiler main body, 2 denotes an evaporating tube, and the evaporating tubes 2 arranged adjacent to each other are connected via a spacing piece 2a to form a tube wall 8 that partitions a combustion chamber. Make up.
[0004]
Reference numeral 3 denotes a refractory material, which is disposed below the tube wall 8 so as to cover the tube wall 8 and shields the evaporating tube 2 constituting the tube wall 8 from a high temperature at a lower part of a combustion chamber having a strong thermal power. It plays a role of protecting the evaporating tube 2 from being worn by particles 6 such as a fluid material and unburned ash described later.
[0005]
Reference numeral 5 denotes a wind box, 7 denotes a header, and combustion air E supplied through these is blown into the inside of the circulating fluidized bed boiler body 1 by an air nozzle, and coal F supplied from the outside and unreturned from the downstream. The fluidized bed is formed by mixing the fuel ash G, the fluidized material (made of an inert powder such as silica sand, or a desulfurizing agent such as limestone) and the like previously stored in the circulating fluidized bed boiler main body 1, and forming a fluidized bed. To promote combustion.
[0006]
Paying attention to the behavior of particles 6 such as fluidized material and unburned ash in the circulating fluidized-bed boiler main body 1 formed as described above, the particles 6 rise at the center of the circulating fluidized-bed boiler main body 1, but evaporate. In the vicinity of the pipe wall 8 formed by the pipe 2 and the like, most of the particles 6 descending along the pipe wall 8, and due to the rising flow and the descending flow, the fluid material and the unreacted fluid in the circulating fluidized bed boiler main body 1. Circulation of particles 6 such as fuel ash is performed.
[0007]
Since the upper end of the refractory material 3 is an upper edge 3a of the refractory material formed by a horizontal surface that is stepped with respect to the pipe wall, the particles 6 descending along the pipe wall 8 are as shown in FIG. ), The particles 6 curving and descending along the upper edge 3a of the refractory material, the particles 6a diverging therefrom to generate a vortex between the upper edge 3a of the refractory material and the evaporation pipe 2, and dropping from above. The upper edge 3a of the refractory material, and the traveling direction is divided into particles 6b and the like that bend and change in multiple directions including a right angle direction. The particles 6a that generate the vortex and the particles 6b and the like that are bent and converted in the direction are collided. Then, the abrasion tube 2 is locally worn.
[0008]
As a countermeasure for preventing the abrasion generated in the evaporating tube 2 due to the particles 6a forming the vortex and the particles 6b changing the direction, etc., the surface of the evaporating tube 2 corresponding to this portion is sprayed with a coating of a wear-resistant member. As shown in FIG. 4, a protector 9 formed of a half-split metal plate is disposed at the upper end of the refractory material 3 and directly above the refractory upper edge 3a. By covering the evaporator tube 2 in close contact with 9, the evaporator tube 2 caused by the impact of particles 6 a and 6 b such as fluidized material and unburned ash due to eddy current or direction change generated at the upper edge 3 a of the refractory material The thing which prevented abrasion and thinning has been proposed.
[0009]
[Problems to be solved by the invention]
However, even if the above-described protector 9 is employed or the coating of the wear-resistant member is thermally sprayed, it is impossible to completely prevent the wear caused by the particles 6a and the particles 6b. The abrasion and thinning of the evaporator tube 2 at the corners of the wall are larger than those near the center of the tube wall, and although the size varies depending on the scale of the apparatus or the operating conditions, etc., for six months to one year At such a small pitch, maintenance such as inspection of the thermal spraying of the coating of the wear-resistant member, re-spraying, replacement of the protector, and raising of the refractory material is required.
[0010]
SUMMARY OF THE INVENTION The present invention aims to solve the problems in the conventional art, and suppresses abrasion and thinning of an evaporating tube caused by particles of a fluidized material or unburned ash on the upper edge side of a refractory material to thereby protect the protector. It is an object of the present invention to provide a circulating fluidized-bed boiler in which maintenance work such as re-spraying of a film on a wear-resistant member is performed with a longer pitch without the need for the use of a circulating fluidized-bed boiler.
[0011]
[Means for Solving the Problems]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and a combustion chamber is defined by a pipe wall formed by juxtaposing a plurality of evaporating pipes, a refractory material covering a lower portion of the pipe wall is provided, and a circulating flow is provided. In a circulating fluidized-bed boiler in which particles such as material and unburned ash descend along the pipe wall, the refractory material has an upper edge formed by a horizontal end face, and the refractory material extends along the pipe wall at the same end face. The present invention provides a circulating fluidized bed boiler provided with a weir extending in the circumferential direction of the combustion chamber.
[0012]
That is, according to the present invention, the refractory material provided so as to cover the lower portion of the pipe wall has an upper edge formed by a horizontal end face, and a weir extending in the circumferential direction of the combustion chamber along the pipe wall. In this weir, particles such as fluidized material and unburned ash that descend along the pipe wall are deposited on the weir, and then the particles of the fluidized material and unburned ash that descend and evaporate from the upper edge of the refractory material. Kinetic energy is absorbed by the particles deposited on the weir, and particles that try to generate a vortex between the tubes, or particles that fall from above and try to change the direction of travel, and frictional force against the evaporation tube And the local wear and thinning of the evaporator tube are suppressed.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a schematic diagram showing a part of a refractory material installation site in a lower part of a combustion chamber of a circulating fluidized bed boiler according to the present embodiment, and FIG. 2 is an explanatory diagram illustrating behavior of particles in a part of FIG.
[0014]
This embodiment is different from the prior art described with reference to FIGS. 3 and 4 in that a new device is added to the upper end surface of the refractory material 3 to thereby reduce the flow material or unburned ash falling along the pipe wall. It is designed to absorb the collision energy between the particles and the evaporating tube, and the other configuration is the same as the conventional one. Therefore, in order to avoid redundant description, the same parts as those of the conventional one will be described. The description of the conventional device will be referred to, and the features unique to the present embodiment will be denoted by the reference numerals of 20 units corresponding to the conventional device, and redundant description will be omitted.
[0015]
That is, in the present embodiment, a number of evaporating tubes 22 are connected by the spacing pieces 22a to form a tube wall, the lower portion of which is covered with the refractory material 23, and the evaporating tube 22 is covered with the refractory material 23 at the upper end side. A coating 22b of a wear-resistant member is sprayed on the surface in the vicinity to prepare for abrasion due to swirling of particles such as fluidized material and unburned ash.
[0016]
In this embodiment, it should be particularly noted that the refractory material 23 has an upper end edge 23a formed by a horizontal end surface, and the end surface of the weir 30 extending in the circumferential direction of the combustion chamber along the pipe wall. That is,
[0017]
According to the present embodiment configured as described above, the refractory material 23 provided so as to cover the lower part of the pipe wall has the upper end edge 23a formed by the horizontal end face as described above, Has a weir 30 extending along the pipe wall in the circumferential direction of the combustion chamber, so that particles 26 such as fluidized material and unburned ash that have fallen along the pipe wall are deposited in the weir 30.
[0018]
When the preceding particles 26 are deposited in the weir 30, a vortex will be generated between the upper end edge 23 a of the refractory material 23 and the evaporating pipe 22 among the particles 26 such as fluidized material and unburned ash that descend subsequently. Kinetic energy is absorbed by particles 26a that fall from above and particles 26b that fall from above and try to bend and change in multiple directions including a right angle direction, using the particles deposited in the weir 30 as a cushion. Will be.
[0019]
Thus, according to the present embodiment, the particles 26a, 26b, etc., reduce the frictional force against the evaporating tube 22, suppress local abrasion and thinning of the evaporating tube 22, and prolong the life of the evaporating tube 22. Can be achieved.
[0020]
As described above, the present invention has been described with reference to the illustrated embodiments. However, the present invention is not limited to such embodiments, and it goes without saying that various changes may be made to the specific structure within the scope of the present invention. Absent.
[0021]
【The invention's effect】
As described above, according to the invention of the present application, a combustion chamber is defined by a pipe wall formed by juxtaposing a plurality of evaporating pipes, a refractory material covering a lower portion of the pipe wall is provided, and a circulating fluid material or unburned ash is provided. In the circulating fluidized-bed boiler in which particles such as are lowered along the pipe wall, the refractory material forms an upper end edge with a horizontal end face, and the end face of the combustion chamber is formed along the pipe wall along the pipe wall. Since the circulating fluidized bed boiler is formed by providing a weir extending in the direction of the pipe, the refractory material provided so as to cover the lower part of the pipe wall has an upper edge formed by a horizontal end face, and the pipe wall is provided on the end face. Of the flow material and unburned ash which fall down along the pipe wall are deposited on the weir by providing the weir extending in the circumferential direction of the combustion chamber along the Of particles that are trying to create a vortex between the upper edge of the refractory material and the evaporator tube, Particles that are likely to bend and change their traveling direction are absorbed by the particles deposited on the weir as cushions, absorbing kinetic energy, reducing the frictional force on the evaporator tube, and reducing the local wear and reduction of the evaporator tube. A suitable circulating fluidized bed boiler whose meat is suppressed and which can be used for a long period of time can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a part of a refractory material installation portion in a lower part of a combustion chamber of a circulating fluidized bed boiler according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram illustrating the behavior of particles in a part of FIG.
3A and 3B schematically show the vicinity of a combustion chamber of a conventional circulating fluidized bed boiler, where FIG. 3A is a schematic structural diagram, FIG. 3B is a view taken along the line AA in FIG. 3A, and FIG. 3D is an enlarged view of a portion C, and FIG. 4D is a functional explanatory diagram of a portion B of FIG.
4A and 4B show an outline of an improved embodiment in which a main part of FIG. 3 is changed, wherein FIG. 4A is a cross-sectional view showing the structure of the main part, and FIG. 4B is a perspective view of the protector shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Circulating fluidized-bed boiler main body 2 Evaporation pipe 2a Spacing piece 3 Refractory material 3a Refractory upper edge 4 Air nozzle 5 Wind box 6 Particle 6a Particle 6b Particle 7 Header 8 Tube wall 9 Protector 9a Protector upper edge 22 Evaporation pipe 22a Spacing piece 22b Coating 23 Refractory 23a Upper edge 26 Particle 26a Particle 26b Particle 30 Weir
