JPH09166390A - Equipment for recovering exhaust heat - Google Patents
Equipment for recovering exhaust heatInfo
- Publication number
- JPH09166390A JPH09166390A JP32851595A JP32851595A JPH09166390A JP H09166390 A JPH09166390 A JP H09166390A JP 32851595 A JP32851595 A JP 32851595A JP 32851595 A JP32851595 A JP 32851595A JP H09166390 A JPH09166390 A JP H09166390A
- Authority
- JP
- Japan
- Prior art keywords
- exhaust gas
- tube
- heat exchanger
- heat transfer
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Landscapes
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
Abstract
Description
【0001】[0001]
【発明が属する技術分野】本発明は、廃棄物焼却炉等の
排ガスから排熱を回収するために用いられる排熱回収装
置に関するものである。TECHNICAL FIELD The present invention relates to an exhaust heat recovery apparatus used for recovering exhaust heat from exhaust gas from a waste incinerator or the like.
【0002】[0002]
【従来の技術】廃棄物焼却炉等の排ガスから排熱を回収
するための熱交換器として、実公昭62-1578 号公報に示
されるUチューブ式熱交換器が知られている。このUチ
ューブ式熱交換器は、図3に示すように排ガスが流れる
缶体1の内側に多数のU字状の伝熱管2を設けたもので
ある。そして各伝熱管2の排ガス上流側の端部は缶体1
の外周に設けられたエアマニホールド3、4に接続され
ており、被加熱流体である空気がU字状の伝熱管2を通
過する間に排ガスにより加熱される構造となっている。2. Description of the Related Art As a heat exchanger for recovering exhaust heat from exhaust gas from a waste incinerator or the like, a U-tube heat exchanger shown in Japanese Utility Model Publication No. 62-1578 is known. As shown in FIG. 3, this U-tube heat exchanger is provided with a large number of U-shaped heat transfer tubes 2 inside a can body 1 through which exhaust gas flows. The end of each heat transfer tube 2 on the upstream side of the exhaust gas is the can body 1.
It is connected to the air manifolds 3 and 4 provided on the outer periphery of and has a structure in which air as a fluid to be heated is heated by exhaust gas while passing through the U-shaped heat transfer tube 2.
【0003】このUチューブ式熱交換器は、伝熱管2が
U字状でその基部のみが缶体1に固定されているため、
高温の排ガスと接したときに自由に熱膨張することがで
き、熱応力による破損のおそれがない利点がある。また
伝熱管2は排ガスの流れと平行に配置されていること、
及び十分なガス流路面積を確保しているため、排ガス中
の灰が伝熱管2に堆積することによる閉塞を起こしにく
い等の利点があり、廃棄物焼却炉の排熱回収に適したも
のである。In this U-tube type heat exchanger, since the heat transfer tube 2 is U-shaped and only its base is fixed to the can body 1,
It has the advantage that it can freely expand thermally when it comes into contact with high-temperature exhaust gas, and there is no risk of damage due to thermal stress. Further, the heat transfer tube 2 should be arranged in parallel with the flow of the exhaust gas,
In addition, since a sufficient gas flow passage area is secured, there is an advantage that ash in the exhaust gas is less likely to be clogged due to accumulation in the heat transfer tube 2, and it is suitable for waste heat recovery of a waste incinerator. is there.
【0004】ところが、排ガス温度が500 ℃以下の低温
域においてこのUチューブ式熱交換器を用いた場合、金
属製の伝熱管2の屈曲部5付近の表面温度が酸露点(約
150 ℃) 以下となり、腐食のおそれがあることがわかっ
た。すなわち、図3に示したように伝熱管2の屈曲部5
は排ガスの最も下流側に位置するため、周囲の排ガス温
度は低くなり、例えば排ガスの入口温度が300 ℃、出口
温度が200℃である場合には伝熱管2の屈曲部5の周囲
温度は200 ℃程度となる。しかも伝熱管2の内部を流れ
る空気もこの位置では十分に加熱されていないので伝熱
管2を内部から冷却することとなり、伝熱管2の屈曲部
5付近の表面温度が130 ℃程度となってしまうのであ
る。また図4のように伝熱管2の内部の空気流の方向を
逆にしても、伝熱管2の屈曲部5付近の表面温度は120
℃程度としかならない。However, when this U-tube type heat exchanger is used in a low temperature range where the exhaust gas temperature is 500 ° C. or less, the surface temperature near the bent portion 5 of the metal heat transfer tube 2 is the acid dew point (about
It became less than 150 ° C) and it was found that there is a risk of corrosion. That is, as shown in FIG. 3, the bent portion 5 of the heat transfer tube 2
Is located on the most downstream side of the exhaust gas, the ambient exhaust gas temperature becomes low. For example, when the exhaust gas inlet temperature is 300 ° C and the outlet temperature is 200 ° C, the ambient temperature of the bent portion 5 of the heat transfer tube 2 is 200 ° C. It becomes about ℃. Moreover, since the air flowing inside the heat transfer tube 2 is not sufficiently heated at this position, the heat transfer tube 2 is cooled from the inside, and the surface temperature near the bent portion 5 of the heat transfer tube 2 becomes about 130 ° C. Of. Even if the direction of the air flow inside the heat transfer tube 2 is reversed as shown in FIG. 4, the surface temperature near the bent portion 5 of the heat transfer tube 2 is 120.
Only about ℃.
【0005】このように、伝熱管2の屈曲部5付近の表
面温度は130 ℃以下の低温となり、排ガス中の酸成分が
結露する酸露点(約150 ℃) 以下となるために、排ガス
に含有される硫酸等の酸による腐食を受けることとな
る。従って、従来のUチューブ式熱交換器は排ガス温度
が500 ℃以下の低温域において使用することは問題であ
った。As described above, the surface temperature near the bent portion 5 of the heat transfer tube 2 is as low as 130 ° C. or lower, and is lower than the acid dew point (about 150 ° C.) at which the acid component in the exhaust gas is condensed, so that it is contained in the exhaust gas. It will be corroded by acids such as sulfuric acid. Therefore, it has been a problem that the conventional U-tube heat exchanger is used in a low temperature range where the exhaust gas temperature is 500 ° C or lower.
【0006】[0006]
【発明が解決しようとする課題】本発明は上記した従来
の問題点を解決し、500℃以下の低温域の排ガスから排
熱回収を行う場合にも、伝熱管の屈曲部等が酸による腐
食を受けるおそれのないようにした排熱回収装置を提供
するためになされたものである。DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned conventional problems, and even when exhaust heat recovery from exhaust gas in a low temperature range of 500 ° C. or less is performed, the bent portion of the heat transfer tube is corroded by acid. This is done in order to provide an exhaust heat recovery device that is free from the risk of receiving heat.
【0007】[0007]
【課題を解決するための手段】上記の課題を解決するた
めになされた本発明の排熱回収装置は、排ガスが流れる
缶体の内側に多数のU字状の伝熱管を設けたUチューブ
式熱交換器を複数段、好ましくは2段に分割し、排ガス
上流側に設けられたUチューブ式熱交換器により被加熱
流体である空気を予熱したうえ、排ガス下流側のUチュ
ーブ式熱交換器の伝熱管に導いて所定の温度に加熱する
ことを特徴とするものである。なお、上流側に設けられ
たUチューブ式熱交換器により、空気を70〜100 ℃に加
熱することが好ましい。The exhaust heat recovery apparatus of the present invention made to solve the above problems is a U-tube type in which a large number of U-shaped heat transfer tubes are provided inside a can body through which exhaust gas flows. The heat exchanger is divided into a plurality of stages, preferably two stages, and the U-tube heat exchanger provided upstream of the exhaust gas preheats the air to be heated, and the U-tube heat exchanger downstream of the exhaust gas. It is characterized in that it is guided to a heat transfer tube of and heated to a predetermined temperature. In addition, it is preferable to heat the air to 70 to 100 ° C. by a U-tube type heat exchanger provided on the upstream side.
【0008】[0008]
【発明の実施の形態】以下に本発明の好ましい実施の形
態を説明する。図1は本発明の第1の実施の形態を示す
断面図であり、従来のUチューブ式熱交換器が、排ガス
上流側のUチューブ式熱交換器6と排ガス下流側のUチ
ューブ式熱交換器7とに2段に分割されている。この場
合、2つに分割されたUチューブ式熱交換器6、7の長
さの和は、同一能力を持つ従来のUチューブ式熱交換器
の長さと略等しくなっている。なお、これらの2つに分
割されたUチューブ式熱交換器6、7は分離して配置し
てもよいが、隣接して配置することが好ましい。またU
チューブ式熱交換器は2段に分割するほか、3段以上の
複数段に分割してもよい。BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below. FIG. 1 is a cross-sectional view showing a first embodiment of the present invention, in which a conventional U-tube heat exchanger includes a U-tube heat exchanger 6 on the exhaust gas upstream side and a U-tube heat exchanger on the exhaust gas downstream side. It is divided into two parts. In this case, the sum of the lengths of the U-tube heat exchangers 6 and 7 divided into two is substantially equal to the length of a conventional U-tube heat exchanger having the same capacity. The U-tube heat exchangers 6 and 7 divided into these two may be arranged separately, but are preferably arranged adjacent to each other. Also U
The tube heat exchanger may be divided into two stages, or may be divided into a plurality of stages of three or more.
【0009】各Uチューブ式熱交換器6、7は、従来と
同様に排ガスが流れる缶体1の内側に多数のU字状の伝
熱管2を設けたものである。またU字状の伝熱管2の排
ガス上流側の端部はエアマニホールド3、4に接続され
ており、被加熱流体である空気が伝熱管2の内部を流れ
ている。この図1の例では、排ガス上流側のUチューブ
式熱交換器6の伝熱管2を流れて予熱された空気が、排
ガス下流側のUチューブ式熱交換器7に導かれている。Each U-tube type heat exchanger 6, 7 is provided with a large number of U-shaped heat transfer tubes 2 inside the can body 1 through which exhaust gas flows, as in the conventional case. Further, the end of the U-shaped heat transfer tube 2 on the upstream side of the exhaust gas is connected to the air manifolds 3 and 4, and air as a fluid to be heated flows inside the heat transfer tube 2. In the example of FIG. 1, the air that has flowed through the heat transfer tube 2 of the U-tube heat exchanger 6 on the upstream side of the exhaust gas and has been preheated is guided to the U-tube heat exchanger 7 on the downstream side of the exhaust gas.
【0010】このように予熱された空気を排ガス下流側
のUチューブ式熱交換器7に導けば、排ガス温度が最も
低くなる伝熱管2の屈曲部5付近の表面温度を酸露点よ
りも高温に維持することができる。また、排ガス上流側
のUチューブ式熱交換器6では排ガス温度が高いため、
伝熱管2の内部を流れる空気の温度は低くても伝熱管2
の屈曲部5付近の表面温度が酸露点以下になるおそれは
ない。また酸露点防止のために回収空気温度を高く設定
し、エアプレヒータを設置することもなくすことが可能
となる。By introducing the preheated air to the U-tube type heat exchanger 7 on the downstream side of the exhaust gas, the surface temperature near the bent portion 5 of the heat transfer tube 2 where the exhaust gas temperature becomes the lowest becomes higher than the acid dew point. Can be maintained. Further, since the exhaust gas temperature is high in the U-tube heat exchanger 6 on the upstream side of the exhaust gas,
Even if the temperature of the air flowing inside the heat transfer tube 2 is low, the heat transfer tube 2
There is no possibility that the surface temperature in the vicinity of the bent portion 5 becomes lower than the acid dew point. In addition, it is possible to set the temperature of the recovered air high to prevent the acid dew point and eliminate the need to install an air preheater.
【0011】排ガス上流側のUチューブ式熱交換器6に
よる空気の予熱温度は、70〜100 ℃程度とすることが好
ましい。これは、予熱温度が70℃未満であると排ガス下
流側のUチューブ式熱交換器7の伝熱管2の屈曲部5付
近の表面温度が酸露点以下となるおそれがあるためであ
る。また逆に予熱温度を100 ℃以上とすると、排ガス上
流側のUチューブ式熱交換器6による排ガス温度の低下
が大きくなり、排ガス下流側のUチューブ式熱交換器7
における排ガス温度が低温となるために空気とガスとの
間の温度差が過大となり、やはり伝熱管2の屈曲部5付
近の表面温度が酸露点以下となるおそれがあるためであ
る。The preheating temperature of the air by the U-tube type heat exchanger 6 on the upstream side of the exhaust gas is preferably about 70-100 ° C. This is because if the preheating temperature is lower than 70 ° C., the surface temperature near the bent portion 5 of the heat transfer tube 2 of the U-tube heat exchanger 7 on the downstream side of the exhaust gas may be below the acid dew point. On the contrary, if the preheating temperature is set to 100 ° C. or higher, the exhaust gas temperature in the U-tube heat exchanger 6 on the upstream side of the exhaust gas greatly decreases, and the U-tube heat exchanger 7 on the downstream side of the exhaust gas becomes
This is because the temperature of the exhaust gas becomes low and the temperature difference between the air and the gas becomes excessively large, and the surface temperature near the bent portion 5 of the heat transfer tube 2 may be lower than the acid dew point.
【0012】図2は本発明の第2の実施の形態を示す断
面図である。この例では排ガス上流側のUチューブ式熱
交換器6により70〜100 ℃に予熱された空気がパイプ8
により排ガス上流側のUチューブ式熱交換器6の下端に
導かれている。従って予熱された空気はエアマニホール
ド10の内部を上流側に流れ、この間に排ガスにより加熱
されたうえで伝熱管2に入り、排ガスにより更に加熱さ
れて最終的にエアマニホールド9から取り出される。こ
のように図2の構造とすると、伝熱管2の屈曲部5付近
の表面温度は図1の構造よりは低温となるが、酸露点以
下となるおそれはない。従ってケースに応じて図1と図
2の構造を選択することができる。FIG. 2 is a sectional view showing a second embodiment of the present invention. In this example, the air preheated to 70 to 100 ° C by the U-tube type heat exchanger 6 on the upstream side of the exhaust gas is pipe 8
Is guided to the lower end of the U-tube heat exchanger 6 on the upstream side of the exhaust gas. Therefore, the preheated air flows through the inside of the air manifold 10 to the upstream side, is heated by the exhaust gas during this time, enters the heat transfer tube 2, is further heated by the exhaust gas, and is finally taken out from the air manifold 9. With the structure of FIG. 2 as described above, the surface temperature near the bent portion 5 of the heat transfer tube 2 is lower than that of the structure of FIG. 1, but there is no fear of becoming lower than the acid dew point. Therefore, the structure of FIGS. 1 and 2 can be selected according to the case.
【0013】[0013]
【実施例】次に本発明の実施例を示す。排ガス流量が50
00m3/h、排ガスの入口温度が300 ℃、出口温度が200
℃、空気の入口温度が20℃、出口温度が200 ℃の条件
で、図4に示す構造の従来の排熱回収装置と、図1に示
す構造の本発明の排熱回収装置とを製作した。この条件
を満たすためには従来の排熱回収装置は直径1.8 m、全
長4mのサイズとなり、また伝熱管の屈曲部付近の表面
温度は120 ℃であって、酸露点以下となった。Next, examples of the present invention will be described. Exhaust gas flow rate is 50
00m 3 / h, exhaust gas inlet temperature 300 ℃, outlet temperature 200
The conventional exhaust heat recovery device having the structure shown in FIG. 4 and the exhaust heat recovery device of the present invention having the structure shown in FIG. 1 were manufactured under the conditions of ℃, air inlet temperature of 20 ° C., and outlet temperature of 200 ° C. . In order to satisfy this condition, the conventional exhaust heat recovery device had a diameter of 1.8 m and a total length of 4 m, and the surface temperature near the bent portion of the heat transfer tube was 120 ° C., which was below the acid dew point.
【0014】これに対して、図1に示す本発明の排熱回
収装置は直径1.8 m、全長5mとなり、全長が従来より
も長くなったが、伝熱管の屈曲部付近の表面温度は170
℃となり、酸露点よりも高くなった。従って本発明の排
熱回収装置は排ガス中の酸による腐食のおそれがない。On the other hand, the exhaust heat recovery apparatus of the present invention shown in FIG. 1 has a diameter of 1.8 m and a total length of 5 m, which is longer than before, but the surface temperature near the bent portion of the heat transfer tube is 170.
The temperature became ° C, which was higher than the acid dew point. Therefore, the exhaust heat recovery system of the present invention has no risk of corrosion due to acid in the exhaust gas.
【0015】[0015]
【発明の効果】以上に説明したように、本発明の排熱回
収装置はUチューブ式熱交換器を2段に分割し、排ガス
上流側に設けられたUチューブ式熱交換器により予熱し
た空気を排ガス下流側のUチューブ式熱交換器の伝熱管
に導く構造としたので、排ガス温度が500 ℃以下の低温
域において使用する場合にも、伝熱管の表面温度を酸露
点以上に保つことができる。従って従来のような伝熱管
の酸腐食を防止することができる利点がある。As described above, in the exhaust heat recovery apparatus of the present invention, the U-tube heat exchanger is divided into two stages, and the air preheated by the U-tube heat exchanger provided on the upstream side of the exhaust gas is used. Since it has a structure that guides the heat transfer tube to the heat transfer tube of the U-tube heat exchanger on the downstream side of the exhaust gas, the surface temperature of the heat transfer tube can be kept above the acid dew point even when the exhaust gas temperature is used in the low temperature range of 500 ° C or less. it can. Therefore, there is an advantage that acid corrosion of the conventional heat transfer tube can be prevented.
【図1】本発明の第1の実施形態を示す断面図である。FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
【図2】本発明の第2の実施形態を示す断面図である。FIG. 2 is a sectional view showing a second embodiment of the present invention.
【図3】従来例を示す断面図である。FIG. 3 is a sectional view showing a conventional example.
【図4】他の従来例を示す断面図である。FIG. 4 is a sectional view showing another conventional example.
1 缶体、2 伝熱管、3 エアマニホールド、4 エ
アマニホールド、5 伝熱管の屈曲部、6 排ガス上流
側のUチューブ式熱交換器、7排ガス下流側のUチュー
ブ式熱交換器、8 パイプ、9 エアマニホールド、10
エアマニホールドDESCRIPTION OF SYMBOLS 1 can body, 2 heat transfer tube, 3 air manifold, 4 air manifold, 5 bent part of heat transfer tube, 6 U-tube type heat exchanger on exhaust gas upstream side, 7 U-tube type heat exchanger on exhaust gas downstream side, 8 pipe, 9 air manifolds, 10
Air manifold
Claims (3)
状の伝熱管を設けたUチューブ式熱交換器を複数段に分
割し、排ガス上流側に設けられたUチューブ式熱交換器
により被加熱流体である空気を予熱したうえ、排ガス下
流側のUチューブ式熱交換器の伝熱管に導いて所定の温
度に加熱することを特徴とする排熱回収装置。1. A U-tube heat exchanger in which a large number of U-shaped heat transfer tubes are provided inside a can body through which exhaust gas flows, is divided into a plurality of stages, and the U-tube heat exchanger is provided upstream of the exhaust gas. An exhaust heat recovery apparatus which preheats air, which is a fluid to be heated, by the above, and guides it to a heat transfer tube of a U-tube heat exchanger on the downstream side of exhaust gas to heat it to a predetermined temperature.
排ガス下流側との2段に分割した請求項1に記載の排熱
回収装置。2. The exhaust heat recovery device according to claim 1, wherein the U-tube heat exchanger is divided into two stages, an exhaust gas upstream side and an exhaust gas downstream side.
器により、空気を70〜100 ℃に加熱する請求項2に記載
の排熱回収装置。3. The exhaust heat recovery device according to claim 2, wherein the air is heated to 70 to 100 ° C. by a U-tube type heat exchanger provided on the upstream side.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32851595A JPH09166390A (en) | 1995-12-18 | 1995-12-18 | Equipment for recovering exhaust heat |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP32851595A JPH09166390A (en) | 1995-12-18 | 1995-12-18 | Equipment for recovering exhaust heat |
Publications (1)
Publication Number | Publication Date |
---|---|
JPH09166390A true JPH09166390A (en) | 1997-06-24 |
Family
ID=18211145
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP32851595A Pending JPH09166390A (en) | 1995-12-18 | 1995-12-18 | Equipment for recovering exhaust heat |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH09166390A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007255825A (en) * | 2006-03-24 | 2007-10-04 | Ngk Insulators Ltd | Circulation fluidized bed furnace |
-
1995
- 1995-12-18 JP JP32851595A patent/JPH09166390A/en active Pending
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007255825A (en) * | 2006-03-24 | 2007-10-04 | Ngk Insulators Ltd | Circulation fluidized bed furnace |
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