JP2018162917A - Method for operating gas preheating device - Google Patents
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Abstract
Description
本発明は、高炉ガスを含む燃料ガスを排気ガスによって予熱するガス予熱装置の操業方法に関するものである。 The present invention relates to a method for operating a gas preheating device that preheats fuel gas containing blast furnace gas with exhaust gas.
製鉄所で使用される一部のボイラの燃料として、高炉ガスと転炉ガスの混合気体（以下、燃料ガス）が使用されている。
ボイラが排出する排気ガスは高温なので、省エネルギーや環境問題の観点からこの熱を回収することは重要である。
このボイラからの排熱は同じボイラの燃料ガスの予熱に用いると効率がよい。
A mixed gas of blast furnace gas and converter gas (hereinafter referred to as fuel gas) is used as fuel for some boilers used in steelworks.
Since the exhaust gas discharged from the boiler is hot, it is important to recover this heat from the viewpoint of energy saving and environmental problems.
The exhaust heat from this boiler is efficient when used for preheating the fuel gas of the same boiler.
ボイラのガス予熱装置について説明する。
ガス予熱装置はガス流路１０と、熱交換器２０と、を備える。
ガス流路１０は、高炉ガスを含む燃料ガスＧが流れるパイプ又はダクトであり、この中で燃料ガスＧを予熱する。
熱交換器２０は、フィン２２を有する伝熱管２１が管台２３を介して管寄２４に接続されてなる。そして、内部に循環熱媒体Ｗを流し、排気ガスの熱を循環熱媒体Ｗを介して燃料ガスを予熱する。
より詳しくは、熱交換器２０は複数あり、ガス流路１０内に、一つ以上の熱交換器２０を一つの群として互いに近接配置している。この群を燃料ガスに対して上流から昇順で第ｎ群（ｎ＝１，２，３，…）とした。
また、熱交換器２０の各部分は炭素鋼からなる。
A boiler gas preheating device will be described.
The gas preheating device includes a gas flow path 10 and a heat exchanger 20.
The gas flow path 10 is a pipe or duct through which the fuel gas G including the blast furnace gas flows, in which the fuel gas G is preheated.
The heat exchanger 20 is formed by connecting a heat transfer tube 21 having fins 22 to a header 24 via a nozzle base 23. Then, the circulating heat medium W is caused to flow inside, and the heat of the exhaust gas is preheated through the circulating heat medium W.
More specifically, there are a plurality of heat exchangers 20, and one or more heat exchangers 20 are arranged close to each other in the gas flow path 10 as one group. This group was designated as the nth group (n = 1, 2, 3,...) In ascending order from the upstream with respect to the fuel gas.
Moreover, each part of the heat exchanger 20 consists of carbon steel.
ここで、高炉ガスには塩化アンモニウム等の腐食成分が含まれており、その高炉ガスを含む燃料ガスと熱交換する熱交換器２０は高い腐食環境に曝されている。
伝熱管２１が腐食しその腐食が進行すると、伝熱管２１内の循環熱媒体Ｗが漏洩してしまう。
Here, the blast furnace gas contains corrosive components such as ammonium chloride, and the heat exchanger 20 that exchanges heat with the fuel gas containing the blast furnace gas is exposed to a highly corrosive environment.
When the heat transfer tube 21 is corroded and the corrosion proceeds, the circulating heat medium W in the heat transfer tube 21 leaks.
各群の伝熱管２１が一本でも漏洩すると、群全体の機能が低下し熱交換効率が大きく低下するので、漏洩配管の補修を実施しなければならない。
漏洩部分の補修方法とは、漏洩した管を切除し管寄２４側の管台２３に閉止栓を溶接するものであるので、伝熱管２１の稼働数が減少し熱交換器２０の全体の効率が低下することを意味している。
If even one heat transfer tube 21 of each group leaks, the function of the entire group is lowered and the heat exchange efficiency is greatly lowered. Therefore, repair of the leaked pipes must be carried out.
The repair method of the leaked part is to cut out the leaked pipe and weld a stopper plug to the nozzle base 23 on the side of the header 24. Therefore, the number of operating heat transfer pipes 21 is reduced, and the overall efficiency of the heat exchanger 20 is reduced. Is meant to decline.
そこで、腐食環境下（ここではアルカリ腐食）にある伝熱管の材料をＣｒ含有量が９％以上のものにしたボイラが開示されている（例えば、特許文献１参照）。
特許文献１に記載の発明によれば、アルカリ腐食速度は、材料中のＣｒ含有量が高くなるほど低減し、Ｃｒ含有量９％以上になると実質的に腐食が生じない。
よって、ごみ焼却発電設備等での過熱蒸気を得る過熱器のアルカリ腐食を防止でき、しかも低コストである。
Therefore, a boiler is disclosed in which the material of the heat transfer tube in a corrosive environment (here, alkali corrosion) has a Cr content of 9% or more (see, for example, Patent Document 1).
According to the invention described in Patent Document 1, the alkali corrosion rate decreases as the Cr content in the material increases, and when the Cr content is 9% or more, corrosion does not substantially occur.
Therefore, it is possible to prevent alkaline corrosion of the superheater that obtains superheated steam at a waste incineration power generation facility or the like, and at a low cost.
また、ショットピーニング加工を施すことにより、耐食性を向上させたステンレス鋼が開示されている（例えば、特許文献２参照）。
特許文献２に記載の発明によれば、ショットピーニング加工を施すことにより、ステンレス鋼の表面に圧縮応力を付与し引張応力を緩和させることで耐食性が向上するので、応力腐食割れが抑制される。
Moreover, stainless steel which improved the corrosion resistance by performing shot peening is disclosed (see, for example, Patent Document 2).
According to the invention described in Patent Document 2, by performing shot peening, the corrosion resistance is improved by applying a compressive stress to the surface of the stainless steel and relaxing the tensile stress, so that stress corrosion cracking is suppressed.
しかしながら、高炉ガスに曝される環境下での腐食対策としてはいずれも不十分である。
このように腐食対策が不十分な状況では、短期間で第１群１０１の熱交換器２０が腐食してしまい、その機能が失われると、腐食範囲はその下流の群に加速度的に拡大する。
However, both are insufficient as countermeasures against corrosion in an environment exposed to blast furnace gas.
In such a situation where countermeasures against corrosion are insufficient, if the heat exchanger 20 of the first group 101 is corroded in a short period of time and its function is lost, the corrosion range is accelerated to the downstream group. .
このような腐食の拡大を早く発見でき新しい熱交換器２０に更新したとしても、ボイラを予定外に停止させることになってしまい、時間とコストが掛かる。
一方、ボイラを停止することができないとか、腐食の拡大の発見が遅れると、上流側から熱交換器２０がどんどん機能停止してしまうので、ついには複数の熱交換器２０全体が機能しなくなってしまう。
Even if such an expansion of corrosion can be found early and updated to a new heat exchanger 20, the boiler will be stopped unexpectedly, which will take time and cost.
On the other hand, if the boiler cannot be stopped or the discovery of the expansion of corrosion is delayed, the heat exchanger 20 will stop functioning from the upstream side, and eventually the entire plurality of heat exchangers 20 will not function. End up.
そこで、本発明の目的とするところは、複数の熱交換器全体を長寿命化させ得るガス予熱装置の操業方法を提供することにある。 Accordingly, an object of the present invention is to provide a method of operating a gas preheating device that can extend the life of the entire plurality of heat exchangers.
上記の目的を達成するために、本発明の請求項１に記載のガス予熱装置の操業方法は、ボイラの燃料である高炉ガスを含む燃料ガス（Ｇ）が内部を流れるガス流路（１０）と、循環熱媒体（Ｗ）が内部を流れる複数の伝熱管（３１）と、前記複数の伝熱管（３１）の外面に設けられたフィン（３２）と、前記複数の伝熱管（３１）の両端に管台（３３）を介して接続された管寄（３４）と、を有する複数の熱交換器（３０）と、を備え、前記ガス流路（１０）内に、一つ以上の前記熱交換器（３０）を一つの群として互いに近接配置するとともに、前記群を燃料ガス（Ｇ）に対して上流から昇順で第ｎ群（ｎ＝１，２，３，…）として複数配置したガス予熱装置の操業方法であって、前記第１群（１０１）及び第２群（１０２）の前記伝熱管（３１）を耐腐食性ステンレス材で構成し、前記第１群（１０１）及び第２群（１０２）の前記熱交換器（３０）が両方同時に腐食によって熱交換機能を失う前に、前記第１群（１０１）及び第２群（１０２）の前記熱交換器（３０）のうち一方の群の熱交換器（３０）を更新することを特徴とする。 In order to achieve the above object, a gas preheating device operating method according to claim 1 of the present invention is a gas flow path (10) in which a fuel gas (G) containing blast furnace gas as fuel for a boiler flows. A plurality of heat transfer tubes (31) through which the circulating heat medium (W) flows, fins (32) provided on the outer surface of the plurality of heat transfer tubes (31), and the plurality of heat transfer tubes (31). A plurality of heat exchangers (30) having a nozzle (34) connected to both ends via a nozzle (33), and one or more of the above-mentioned gas flow paths (10) The heat exchangers (30) are arranged close to each other as one group, and a plurality of the groups are arranged as an n-th group (n = 1, 2, 3,...) In ascending order from the upstream with respect to the fuel gas (G). An operation method of a gas preheating device, wherein the heat transfer tubes of the first group (101) and the second group (102) 31) is made of a corrosion-resistant stainless steel, and the heat exchangers (30) of the first group (101) and the second group (102) both lose the heat exchange function due to corrosion at the same time. One of the heat exchangers (30) of the group (101) and the second group (102) is updated.
この熱交換機能を失うとは、熱交換機能を完全に喪失するものに限られず、第３群（１０３）以降の熱交換器（３０）を急激に腐食させる程度に第１群（１０１）及び第２群（１０２）の熱交換器（３０）が熱交換機能を失っていることを意味する。 The loss of the heat exchange function is not limited to the complete loss of the heat exchange function, and the first group (101) and the heat exchanger (30) after the third group (103) are rapidly corroded. It means that the heat exchanger (30) of the second group (102) has lost its heat exchange function.
また、請求項２に記載のガス予熱装置の操業方法は、前記第１群（１０１）の前記管台（３３）に対してショットピーニングを施していることを特徴とする。 The operation method of the gas preheating apparatus according to claim 2 is characterized in that shot peening is performed on the nozzle (33) of the first group (101).
また、請求項３に記載のガス予熱装置の操業方法は、前記第１群（１０１）の熱交換器（３０）のフィン（３２）の間隔を、他の群の前記熱交換器（３０）のフィン（３２）の間隔より広くしていることを特徴とする。 Further, in the operation method of the gas preheating device according to claim 3, the interval between the fins (32) of the heat exchanger (30) of the first group (101) is set to be different from that of the heat exchanger (30) of the other group. The distance between the fins (32) is wider.
また、請求項４に記載のガス予熱装置の操業方法は、前記第１群（１０１）の熱交換器（３０）には前記フィン（３２）を設けず前記伝熱管（３１）は裸管であることを特徴とする。 Further, in the operation method of the gas preheating device according to claim 4, the heat exchanger tube (31) of the first group (101) is not provided with the fin (32), and the heat transfer tube (31) is a bare tube. It is characterized by being.
ここで、上記括弧内の記号は、図面および後述する発明を実施するための形態に掲載された対応要素または対応事項を示す。 Here, the symbols in the parentheses indicate corresponding elements or corresponding matters described in the drawings and the embodiments for carrying out the invention described later.
本発明の請求項１に記載のガス予熱装置の操業方法によれば、第１群及び第２群の伝熱管を耐腐食性ステンレス材で構成したので、通常使用される炭素鋼からなる伝熱管と比べて腐食を抑制可能である。これにより、第１群の熱交換器が腐食し下流側が高腐食環境になっても、第２群の熱交換器の腐食が緩やかなので、第３群以降の熱交換器の腐食も抑制できる。
そして、第１群及び第２群の熱交換器が両方同時に腐食によって熱交換機能を失う前に、第１群及び第２群の熱交換器のうち一方の群の熱交換器を更新するので、複数の熱交換器全体の長寿命化が可能である。
また、第１群の熱交換器と第２群の熱交換器は腐食が緩やかなので、短期間で腐食が進む場合とは異なり、その一方の群の熱交換器の熱交換率の低下や更新の際に確認できる腐食の状況から、他方の群の熱交換器の腐食状況を推測可能である。よって、その推測に基いて最適なタイミングで他方の群の熱交換器を更新することができる。
According to the operation method of the gas preheating apparatus according to claim 1 of the present invention, since the heat transfer tubes of the first group and the second group are made of the corrosion-resistant stainless steel material, the heat transfer tube made of carbon steel which is usually used. Corrosion can be suppressed compared to Thereby, even if the heat exchanger of the first group is corroded and the downstream side is in a highly corrosive environment, the corrosion of the heat exchanger of the second group is moderate, so that the corrosion of the heat exchangers after the third group can also be suppressed.
And since both the heat exchangers of the first group and the second group simultaneously lose the heat exchange function due to corrosion, the heat exchangers of one of the first group and the second group of heat exchangers are updated. The life of the entire heat exchanger can be extended.
In addition, since the first group heat exchanger and the second group heat exchanger are moderately corroded, unlike the case where the corrosion proceeds in a short period of time, the heat exchange rate of one of the heat exchangers is reduced or renewed. It is possible to infer the corrosion status of the heat exchangers of the other group from the corrosion status that can be confirmed at the time. Therefore, the other group of heat exchangers can be updated at an optimal timing based on the estimation.
また、請求項２に記載ガス予熱装置の操業方法によれば、請求項１に記載の発明の作用効果に加え、第１群の管台に対してショットピーニングを施しているので、より耐食性が向上する。 Further, according to the operation method of the gas preheating device according to claim 2, in addition to the operational effect of the invention according to claim 1, since the shot peening is applied to the first group of nozzles, the corrosion resistance is further improved. improves.
また、請求項３に記載ガス予熱装置の操業方法によれば、請求項１又は２に記載の発明の作用効果に加え、第１群の熱交換器のフィンの間隔を、他の群の熱交換器のフィンの間隔より広くしているので、燃料ガス中の腐食性物質がフィンに詰まり難くなり、腐食を抑制可能である。 According to the operation method of the gas preheating device according to claim 3, in addition to the operation and effect of the invention according to claim 1 or 2, the interval between the fins of the first group of heat exchangers is set to the heat of another group. Since the distance between the fins of the exchanger is larger than that, the corrosive substance in the fuel gas is less likely to clog the fins, and corrosion can be suppressed.
また、請求項４に記載ガス予熱装置の操業方法によれば、請求項１又は２に記載の発明の作用効果に加え、第１群の熱交換器にはフィンを設けず伝熱管は裸管であるので、燃料ガス中の腐食性物質が伝熱管に付着し難くなり、腐食をより抑制可能である。
以上のような対策を行った結果、熱交換器全体の寿命が二年から五年以上へ大幅に延びた。
Further, according to the operation method of the gas preheating device according to claim 4, in addition to the operation and effect of the invention according to claim 1 or 2, the heat exchanger tube is a bare tube without providing fins in the first group of heat exchangers. Therefore, the corrosive substance in the fuel gas is difficult to adhere to the heat transfer tube, and the corrosion can be further suppressed.
As a result of these measures, the overall life of the heat exchanger has been significantly extended from two years to more than five years.
なお、本発明のガス予熱装置の操業方法のように、第１群及び第２群の一方の群の熱交換器が腐食し伝熱管から循環熱媒体が漏洩したときに、他方の群の熱交換器の循環熱媒体が漏洩する前に一方の群の熱交換器を更新する点は、上述した特許文献１には全く記載されていない。 In addition, like the operation method of the gas preheating device of the present invention, when the heat exchanger of one group of the first group and the second group corrodes and the circulating heat medium leaks from the heat transfer tube, the heat of the other group The point that one group of heat exchangers is renewed before the circulating heat medium of the exchanger leaks is not described at all in Patent Document 1 described above.
図１、図２、及び図４を参照して、本発明の実施形態に係るガス予熱装置の操業方法を説明する。
従来例で示したものと同一部分には同一符号を付した。
このガス予熱装置は、ガス流路１０と、複数の熱交換器３０と、を備え、製鉄所で使用されるボイラの燃料ガスＧを予熱するものである。
燃料ガスＧは、製鉄所で生成される高炉ガス（ＢＦＧ）と転炉ガス（ＬＤＧ）の混合ガスであり、その高炉ガスは塩化アンモニウム等の腐食成分を含んでいる。
With reference to FIG. 1, FIG. 2, and FIG. 4, the operation method of the gas preheating apparatus which concerns on embodiment of this invention is demonstrated.
The same parts as those shown in the conventional example are denoted by the same reference numerals.
This gas preheating device includes a gas flow path 10 and a plurality of heat exchangers 30, and preheats a fuel gas G for a boiler used in an ironworks.
The fuel gas G is a mixed gas of blast furnace gas (BFG) and converter gas (LDG) generated at an ironworks, and the blast furnace gas contains a corrosive component such as ammonium chloride.
ガス流路１０は、燃料ガスＧが内部を流れるパイプ又はダクトであり、この内部で燃料ガスＧを予熱（加熱）する。
ガス流路１０の内径は、熱交換器３０一つの長さよりも大きく、内部に複数の熱交換器３０が配置される。ガス流路１０内部の熱交換器３０にガス流路１０の外部からの熱を伝えるため、ガス流路１０は適宜パイプを介して外部と連通されており、循環熱媒体Ｗが熱交換器３０へ流れるようになっている。
The gas flow path 10 is a pipe or duct through which the fuel gas G flows, and the fuel gas G is preheated (heated) therein.
The inner diameter of the gas flow path 10 is larger than the length of one heat exchanger 30, and a plurality of heat exchangers 30 are arranged inside. In order to transmit heat from the outside of the gas flow path 10 to the heat exchanger 30 inside the gas flow path 10, the gas flow path 10 is appropriately communicated with the outside through a pipe, and the circulating heat medium W is transferred to the heat exchanger 30. To flow.
熱交換器３０は、伝熱管３１と、フィン３２と、管台３３と、管寄３４と、を備える。
本実施形態に係るガス予熱装置はボイラの高温の排気ガスから熱を取得する熱交換器３０も別に備えるが、ここでは排気ガスに比べて低温の燃料ガスＧに対して熱を付与する、ガス流路１０内に配置される熱交換器３０について主に説明する。
The heat exchanger 30 includes a heat transfer tube 31, fins 32, a nozzle 33, and a header 34.
The gas preheating device according to the present embodiment also includes a heat exchanger 30 that obtains heat from the high-temperature exhaust gas of the boiler, but here, the gas that gives heat to the fuel gas G that is lower in temperature than the exhaust gas. The heat exchanger 30 disposed in the flow channel 10 will be mainly described.
熱交換器３０はガス流路１０内に、一つ以上の熱交換器３０を一つの群として互いに近接配置されるとともに、そのような群を燃料ガスＧに対して上流から昇順で第ｎ群（ｎ＝１，２，３，…）として複数配置した。
本実施形態においては第１群１０１から第６群まで設けた。
この近接配置とは、燃料ガスＧの流れ方向（上流下流方向）に関してお互い近くに配置したという意味である。
The heat exchanger 30 is arranged in the gas flow path 10 in the vicinity of one or more heat exchangers 30 as a group, and such a group is arranged in ascending order from the upstream with respect to the fuel gas G. A plurality of (n = 1, 2, 3,...) Are arranged.
In the present embodiment, the first group 101 to the sixth group are provided.
This close arrangement means that the fuel gas G is arranged close to each other in the flow direction (upstream / downstream direction) of the fuel gas G.
つまり、第１群１０１が燃料ガスＧの流れに対して最も上流側に位置している熱交換器３０のグループで、第２群１０２は第１群１０１の下流側に配置されている熱交換器３０のグループ、そして第３群１０３は第２群１０２の下流側に配置されている熱交換器３０のグループである。
第３群１０３以下、第４群１０４、第５群１０５、第６群は順に同様である。
そして、各群について４４列・３段で構成した。つまり各群は１３２本の伝熱管３１を備える。
That is, the first group 101 is a group of the heat exchangers 30 that are located most upstream with respect to the flow of the fuel gas G, and the second group 102 is a heat exchange that is disposed on the downstream side of the first group 101. The group of the heat exchanger 30 and the third group 103 are a group of the heat exchangers 30 arranged on the downstream side of the second group 102.
The third group 103 and below, the fourth group 104, the fifth group 105, and the sixth group are the same in order.
Each group was composed of 44 rows and 3 stages. That is, each group includes 132 heat transfer tubes 31.
伝熱管３１は、その内部を循環熱媒体Ｗが流れるパイプである。この循環熱媒体Ｗは、ガス流路１０に到達するより前にボイラの排気ガスによって昇温されている。
伝熱管３１の両端には管台３３を介して管寄３４が接続され、複数の伝熱管３１を管寄３４に集合させており、それにより一つの熱交換器３０がなる。
The heat transfer tube 31 is a pipe through which the circulating heat medium W flows. The circulating heat medium W is heated by the exhaust gas of the boiler before reaching the gas flow path 10.
A pipe 34 is connected to both ends of the heat transfer pipe 31 via a nozzle 33, and a plurality of heat transfer pipes 31 are assembled in the pipe 34, thereby forming one heat exchanger 30.
フィン３２は、伝熱管３１の実質的な表面積を増加させるために、第２〜第６群のそれぞれの伝熱管３１の外面に螺旋状に設けられている。
フィン３２のピッチは４〜５ｍｍとした。
一方、第１群１０１の伝熱管３１にはフィン３２を設けておらず、第１群１０１の伝熱管３１は裸管になっている。
In order to increase the substantial surface area of the heat transfer tube 31, the fin 32 is spirally provided on the outer surface of each heat transfer tube 31 of the second to sixth groups.
The pitch of the fins 32 was 4-5 mm.
On the other hand, the fin 32 is not provided in the heat transfer tube 31 of the first group 101, and the heat transfer tube 31 of the first group 101 is a bare tube.
そして、第１群１０１と第２群１０２の伝熱管３１、管台３３及び第２群１０２のフィン３２を耐腐食性ステンレス材で構成した。この耐腐食性ステンレス材とは出願人が製造する商品名：ＮＳＳ ＳＣＲであり、その代表成分は１８．５Ｃｒ−１２Ｎｉ−３Ｓｉ−２Ｃｕ−０．８Ｍｏである。
また、管寄３４はＳＵＳ３１６Ｌで構成した。
さらに第１群１０１の管台３３には、残留応力が１０ｋｇ／ｍｍ2以下になる程度にショットピーニング処置を行った。
また、第１群１０１の管台３３の溶接部には３００℃耐熱防食塗装を施している。
The heat transfer tubes 31 and the nozzles 33 of the first group 101 and the second group 102 and the fins 32 of the second group 102 were made of a corrosion resistant stainless material. This corrosion-resistant stainless steel is a product name: NSS SCR manufactured by the applicant, and its representative component is 18.5Cr-12Ni-3Si-2Cu-0.8Mo.
In addition, the tube holder 34 is made of SUS316L.
Further, shot peening treatment was performed on the nozzle 33 of the first group 101 to such an extent that the residual stress was 10 kg / mm 2 or less.
Further, the welded portion of the nozzle 33 of the first group 101 is subjected to 300 ° C. heat and corrosion resistance coating.
一方、第３乃至第６群の伝熱管３１、フィン３２、管台３３、管寄３４は従来通り、炭素鋼からなる。
つまり、第１群１０１の熱交換器３０を最も耐食性を高くし、次に第２群１０２の熱交換器３０の耐食性を高くした。
On the other hand, the third to sixth groups of heat transfer tubes 31, fins 32, nozzles 33, and nozzles 34 are made of carbon steel as usual.
That is, the heat resistance of the heat exchanger 30 of the first group 101 was made highest, and then the corrosion resistance of the heat exchanger 30 of the second group 102 was made high.
次に、ガス流路１０内の腐食環境について説明する。
第１群１０１の周囲環境（雰囲気）は、ｐＨ５．０、相対湿度１００〜４５％、ｃｌ-が最大１５００ｐｐｍである。
第１群１０１の箇所を通過した燃料ガスＧは熱を受け取り昇温するので、相対湿度が低下する。その結果、第２群１０２以下の周囲環境は第１群１０１の周囲環境に比べて低腐食環境となる。つまり、最も上流側である第１群１０１の周囲環境が最も腐食に関して過酷な条件であるが、その高腐食環境下に置かれていない第２群の熱交換器についても敢えて耐食性を高めている。
Next, the corrosive environment in the gas flow path 10 will be described.
The ambient environment (atmosphere) of the first group 101 has a pH of 5.0, a relative humidity of 100 to 45%, and a maximum of cl − of 1500 ppm.
Since the fuel gas G that has passed through the location of the first group 101 receives heat and rises in temperature, the relative humidity decreases. As a result, the surrounding environment below the second group 102 is a low-corrosion environment compared to the surrounding environment of the first group 101. In other words, the environment surrounding the first group 101 on the most upstream side is the most severe condition with respect to corrosion, but the corrosion resistance of the second group heat exchanger not placed in the highly corrosive environment is also increased. .
そして、第１群１０１が機能しているときにはガス相対湿度は４５％未満であるが、第１群１０１の機能が低下すると、燃料ガスＧが第１群１０１を通過するときに昇温されない（昇温が不足する）ので、その下流である第２群１０２まわりの相対湿度が４５％以上に上昇する。特に相対湿度が６０％以上になると、急激に腐食が進むことが判明している。
つまり、第１群１０１の熱交換機能が低下すると、第２群１０２やそれより下流側が高腐食環境になってしまうということである。
And when the 1st group 101 is functioning, gas relative humidity is less than 45%, but if the function of the 1st group 101 falls, it will not raise temperature when fuel gas G passes the 1st group 101 ( Therefore, the relative humidity around the second group 102 downstream thereof increases to 45% or more. In particular, it has been found that when the relative humidity is 60% or more, corrosion proceeds rapidly.
That is, when the heat exchange function of the first group 101 is lowered, the second group 102 and the downstream side thereof are in a highly corrosive environment.
次に、以上のように構成されたガス予熱装置の効果と、その操業方法（補修・更新方法）について、説明する。
まず、ガス予熱装置を通常通り稼働させる。
第１群１０１の熱交換器３０を耐腐食性ステンレス材で構成し、管台３３に対してショットピーニングを施しているので耐食性が向上している。また、第１群１０１の熱交換器３０にはフィン３２を設けず裸管としたので、燃料ガスＧ中の腐食性物質が伝熱管３１に付着し難くなり、腐食をより抑制可能である。
Next, the effect of the gas preheating device configured as described above and the operation method (repair / update method) will be described.
First, the gas preheating device is operated as usual.
Since the heat exchanger 30 of the first group 101 is made of a corrosion-resistant stainless steel and shot peening is applied to the nozzle 33, the corrosion resistance is improved. In addition, since the heat exchanger 30 of the first group 101 is not provided with the fins 32 and is a bare pipe, the corrosive substance in the fuel gas G is difficult to adhere to the heat transfer pipe 31, and the corrosion can be further suppressed.
このように第１群１０１の熱交換器３０の耐食性を特に高めているが、先述の通り、第１群１０１まわりが最も過酷な腐食環境であるので、いつかは第１群１０１の熱交換器３０に応力腐食割れ等が生じて伝熱管３１内の循環熱媒体Ｗが漏洩する。 Thus, although the corrosion resistance of the heat exchanger 30 of the first group 101 is particularly enhanced, as described above, since the periphery of the first group 101 is the most severe corrosive environment, the heat exchanger of the first group 101 will someday. Stress corrosion cracking or the like occurs in 30 and the circulating heat medium W in the heat transfer tube 31 leaks.
ボイラ停止のタイミングで、漏洩した第１群１０１の伝熱管３１を切除し閉止栓を溶接する。
このように補修により止栓した伝熱管３１が複数に拡大し、第１群１０１全体の熱交換効率が低下するに伴い、第２群１０２まわりが高腐食環境となっていく。
そして、第２群１０２の伝熱管３１も腐食及び補修により止栓が増加する。
At the timing of the boiler stop, the leaked heat transfer tube 31 of the first group 101 is cut off and a stopper plug is welded.
Thus, as the heat transfer tubes 31 stopped by the repair expand to a plurality and the heat exchange efficiency of the entire first group 101 decreases, the periphery of the second group 102 becomes a highly corrosive environment.
And the heat transfer tube 31 of the 2nd group 102 also increases a stop plug by corrosion and repair.
ここで、第１群１０１及び第２群１０２の熱交換器３０が両方同時に腐食によって熱交換機能を失う前に、第１群１０１及び第２群１０２の熱交換器３０のうち一方の群の熱交換器３０を更新する。つまり、止栓するのではなく、新品の熱交換器３０に交換する。
この点、第１群１０１及び第２群１０２の熱交換器３０の耐食性を向上させているので、第１群１０１の熱交換器３０が腐食し下流側が高腐食環境になっても、第２群１０２の熱交換器３０の腐食が緩やかで、第３群以降の熱交換器の腐食も抑制できる。 よって、第３群１０３より下流側の群の熱交換器３０において加速度的に腐食が進むことは抑制される。
このように、複数の熱交換器３０全体の長寿命化が可能である。
Here, before both the heat exchangers 30 of the first group 101 and the second group 102 lose their heat exchange function due to corrosion at the same time, one of the heat exchangers 30 of the first group 101 and the second group 102 The heat exchanger 30 is updated. In other words, the heat exchanger 30 is replaced with a new one instead of being plugged.
In this regard, since the corrosion resistance of the heat exchangers 30 of the first group 101 and the second group 102 is improved, even if the heat exchanger 30 of the first group 101 corrodes and the downstream side becomes a highly corrosive environment, the second Corrosion of the heat exchangers 30 of the group 102 is moderate, and corrosion of the heat exchangers after the third group can be suppressed. Therefore, accelerated progress of corrosion in the heat exchangers 30 in the group downstream from the third group 103 is suppressed.
In this way, the life of the plurality of heat exchangers 30 as a whole can be extended.
また、第１群１０１の熱交換器３０と第２群１０２の熱交換器３０は腐食が緩やかなので、短期間で腐食が進む場合とは異なり、その一方の群の熱交換器３０の熱交換率の低下や更新の際に確認できる腐食の状況から、他方の群の熱交換器３０の腐食状況を推測可能である。よって、その推測に基いて最適なタイミングで他方の群の熱交換器を更新することができる。 Further, since the heat exchanger 30 of the first group 101 and the heat exchanger 30 of the second group 102 are moderately corroded, the heat exchange of the heat exchanger 30 of one group is different from the case where the corrosion proceeds in a short period of time. The corrosion status of the heat exchanger 30 of the other group can be estimated from the corrosion status that can be confirmed when the rate is reduced or updated. Therefore, the other group of heat exchangers can be updated at an optimal timing based on the estimation.
なお、本実施形態において、第１群１０１の管台３３に対してショットピーニングに施したが、これに限られるものではなく、第２群１０２の管台３３に対してもショットピーニングを行ってもよい。
同様に、第２群１０２の管台３３の溶接部にも３００℃耐熱防食塗装を施してもよい。
In this embodiment, the shot peening is performed on the nozzle 33 of the first group 101. However, the present invention is not limited to this, and shot peening is also performed on the nozzle 33 of the second group 102. Also good.
Similarly, the welded portion of the nozzle 33 of the second group 102 may be subjected to 300 ° C. heat and corrosion resistance coating.
また、第１群１０１の熱交換器３０にはフィン３２を設けず裸管としたが、これに限られるものではなく、第１群１０１の熱交換器３０のフィン３２の間隔を、他の群の熱交換器３０のフィン３２の間隔よりも広くすることでも、燃料ガスＧ中の腐食性物質がフィン３２に詰まり難くなり、腐食を抑制可能である。
もちろん、第１〜第６群までフィン３２の間隔を等しくしてもよい。
In addition, the heat exchanger 30 of the first group 101 is not provided with fins 32 and is a bare tube, but the present invention is not limited to this, and the interval between the fins 32 of the heat exchanger 30 of the first group 101 can be set to other values. By making the distance between the fins 32 of the group of heat exchangers 30 wider than that, the corrosive substance in the fuel gas G becomes difficult to clog the fins 32, and corrosion can be suppressed.
Of course, you may make the space | interval of the fin 32 equal to 1st-6th group.
また、第６群まで配置したが、これに限られるものではなくこれより多くても少なくてもよい。
さらには、一つの群における伝熱管３１の本数も、本実施形態のものに限られない。
Moreover, although arrange | positioned to the 6th group, it is not restricted to this, It may be more or less than this.
Furthermore, the number of heat transfer tubes 31 in one group is not limited to that of the present embodiment.
１０ ガス流路
２０ 熱交換器
２１ 伝熱管
２２ フィン
２３ 管台
２４ 管寄
３０ 熱交換器
３１ 伝熱管
３２ フィン
３３ 管台
３４ 管寄
１０１ 第１群
１０２ 第２群
１０３ 第３群
１０４ 第４群
１０５ 第５群
Ｇ 燃料ガス
Ｗ 循環熱媒体
DESCRIPTION OF SYMBOLS 10 Gas flow path 20 Heat exchanger 21 Heat transfer tube 22 Fin 23 Pipe stand 24 Nose 30 Heat exchanger 31 Heat transfer pipe 32 Fin 33 Nozzle 34 Nozzle 101 1st group 102 2nd group 103 3rd group 104 4th group 105 5th group G Fuel gas W Circulating heat medium
Claims (4)
循環熱媒体が内部を流れる複数の伝熱管と、前記複数の伝熱管の外面に設けられたフィンと、前記複数の伝熱管の両端に管台を介して接続された管寄と、を有する複数の熱交換器と、を備え、
前記ガス流路内に、一つ以上の前記熱交換器を一つの群として互いに近接配置するとともに、前記群を燃料ガスに対して上流から昇順で第ｎ群（ｎ＝１，２，３，…）として複数配置したガス予熱装置の操業方法であって、
前記第１群及び第２群の前記伝熱管を耐腐食性ステンレス材で構成し、
前記第１群及び第２群の前記熱交換器が両方同時に腐食によって熱交換機能を失う前に、前記第１群及び第２群の前記熱交換器のうち一方の群の熱交換器を更新することを特徴とするガス予熱装置の操業方法。 A gas flow path through which fuel gas containing blast furnace gas, which is boiler fuel, flows;
A plurality of heat transfer tubes through which the circulating heat medium flows, fins provided on the outer surfaces of the plurality of heat transfer tubes, and pipes connected to both ends of the plurality of heat transfer tubes via nozzles A heat exchanger, and
In the gas flow path, one or more heat exchangers are arranged close to each other as a group, and the group is arranged in the ascending order from the upstream with respect to the fuel gas, the nth group (n = 1, 2, 3, ...) a plurality of gas preheating device operation methods,
The heat transfer tubes of the first group and the second group are made of a corrosion resistant stainless material,
The heat exchangers of one of the first and second groups of heat exchangers are updated before both the first and second group of heat exchangers simultaneously lose their heat exchange function due to corrosion. A method for operating a gas preheating device.
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| US11769774B2 (en) | 2018-03-29 | 2023-09-26 | Sony Semiconductor Solutions Corporation | Solid-state imaging device and electronic device |
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