JP2735004B2 - Corrosion prevention method for high and medium pressure steam return piping - Google Patents
Corrosion prevention method for high and medium pressure steam return pipingInfo
- Publication number
- JP2735004B2 JP2735004B2 JP25238494A JP25238494A JP2735004B2 JP 2735004 B2 JP2735004 B2 JP 2735004B2 JP 25238494 A JP25238494 A JP 25238494A JP 25238494 A JP25238494 A JP 25238494A JP 2735004 B2 JP2735004 B2 JP 2735004B2
- Authority
- JP
- Japan
- Prior art keywords
- return water
- steam
- pipe
- pressure
- pressure steam
- 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.)
- Expired - Lifetime
Links
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- Preventing Corrosion Or Incrustation Of Metals (AREA)
Description
【０００１】[0001]
【産業上の利用分野】本発明は、還水配管の腐食を防止
する方法に関し、特に、建物の空調等に用いられる高・
中圧蒸気還水配管の腐食を防止する方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing corrosion of return water pipes, and more particularly, to a method for preventing the corrosion of return water piping.
The present invention relates to a method for preventing corrosion of a medium-pressure steam return water pipe.
【０００２】[0002]
【従来の技術】例えば、中高層ビルディングの空気調和
には、高・中圧蒸気が用いらることがある。この種の従
来の高・中圧蒸気による空気調和装置は、図２に示すよ
うに、一端に配置されたボイラー１０と、空調機器とし
て途中に配置された蒸気コイルまたは熱交換器１１と、
他端に配置されたホットウェルタンク（ＨＷＴ）１２
と、ボイラー１０と蒸気コイルまたは熱交換器１１とを
連結する蒸気供給配管１３と、蒸気コイルまたは熱交換
器１１とホットウェルタンク１２とを連結する還水配管
１４とを備えている。この還水配管１４の端部は、ホッ
トウェルタンク１２上の空気中に開放されている。蒸気
供給配管１３の途中には蒸気の供給を制御するための自
動制御弁（ＭＶ）１５が配置されており、還水配管１４
の途中には蒸気からの還水と不凝縮ガスを分離するため
の蒸気トラップ１６が配置されている。2. Description of the Related Art For example, high and medium pressure steam is used for air conditioning of middle and high rise buildings. As shown in FIG. 2, this type of conventional air conditioner using high / medium pressure steam includes a boiler 10 arranged at one end, a steam coil or a heat exchanger 11 arranged in the middle as an air conditioner,
Hot well tank (HWT) 12 located at the other end
And a steam supply pipe 13 connecting the boiler 10 and the steam coil or the heat exchanger 11, and a return water pipe 14 connecting the steam coil or the heat exchanger 11 and the hot well tank 12. The end of the return water pipe 14 is open to the air above the hot well tank 12. An automatic control valve (MV) 15 for controlling the supply of steam is disposed in the middle of the steam supply pipe 13, and a return water pipe 14 is provided.
A steam trap 16 for separating return water and non-condensable gas from steam is disposed in the middle of the process.
【０００３】この従来の空気調和設備では、空調時に
は、ボイラー１０で発生した中・高圧蒸気を蒸気供給配
管１３によって蒸気コイルまたは熱交換器１１に供給
し、そこで室内の空調等に利用する。そして、蒸気コイ
ルまたは熱交換器１１から蒸気の供給圧力によって還水
配管１４に流れた蒸気は蒸気トラップ１６で還水が分離
される。分離された還水はホットウェルタンク１２に回
収される。また、非空調時にはボイラー１０を停止す
る。In this conventional air conditioning equipment, during air conditioning, medium / high pressure steam generated in the boiler 10 is supplied to a steam coil or a heat exchanger 11 through a steam supply pipe 13 and used there for air conditioning in a room. Then, the steam flowing from the steam coil or the heat exchanger 11 to the return water pipe 14 by the supply pressure of the steam is separated into the return water by the steam trap 16. The separated return water is collected in the hot well tank 12. Further, the boiler 10 is stopped during non-air conditioning.
【０００４】[0004]
【発明が解決しようとする課題】前記空気調和装置で
は、還水配管１４の端部がホットウェルタンク１２上で
空気中に開放されているので、蒸気供給停止後に還水配
管１４内に空気や不凝縮ガスが残留する。In the air conditioner, since the end of the return water pipe 14 is open to the air on the hot well tank 12, air or the like is introduced into the return water pipe 14 after the steam supply is stopped. Non-condensable gas remains.
【０００５】一方、還水中では、下記（１）式に示すよ
うに二酸化炭素（ＣＯ2）と水との反応が起きる。さら
に生成した炭酸（Ｈ2ＣＯ3）が、下記（２）式に示すよ
うに鉄（Ｆｅ）と反応して、炭酸水素第一鉄（Ｆｅ（Ｈ
ＣＯ3））が発生する。On the other hand, in the return water, a reaction between carbon dioxide (CO 2 ) and water occurs as shown in the following equation (1). Further, the generated carbonic acid (H 2 CO 3 ) reacts with iron (Fe) as shown in the following equation (2) to produce ferrous hydrogen carbonate (Fe (H
CO 3 )) occurs.
【０００６】 ＣＯ2 ＋ Ｈ2Ｏ → Ｈ2ＣＯ3 --- （１） Ｆｅ ＋ ２Ｈ2ＣＯ3 → Ｆｅ（ＨＣＯ3)2 ＋Ｈ2 --- （２） また、ｐＨが５〜６以下であれば炭酸塩は水に溶解する
ため、鋼表面に腐食生成物が付着せずに鋼が直接腐食環
境にさらされるために、腐食はさらに激しくなる。CO 2 + H 2 O → H 2 CO 3 --- (1) Fe + 2H 2 CO 3 → Fe (HCO 3 ) 2 + H 2 --- (2) When the pH is 5-6 or less, If present, the carbonate will dissolve in the water and the corrosion will be even more severe as the steel is directly exposed to the corrosive environment without the corrosion products adhering to the steel surface.
【０００７】このとき、還水中に空気が含まれている場
合、炭酸水素第一鉄と空気中の酸素との間に、下記
（３）式に示すような急激な反応が起き、さらに腐食が
促進される。このため、従来の空気が残留する還水配管
１４は、腐食が早く寿命が短いという問題がある。[0007] At this time, if air is contained in the return water, a rapid reaction as shown in the following equation (3) occurs between ferrous hydrogen carbonate and oxygen in the air, and further corrosion occurs. Promoted. For this reason, the conventional return water pipe 14 in which air remains has a problem that corrosion is quick and life is short.
【０００８】 ２Ｆｅ（ＨＣＯ3)2 ＋1/2 Ｏ2 →Ｆｅ2Ｏ3 ＋４ＣＯ2 ＋２Ｈ2Ｏ ---（３） さらに、生成した酸化鉄が水中の鋼表面に沈殿すれば、
そこが貴金属側となり、鋼表面を卑金属側としてガルバ
ニックカップルが生じ、下記（４），（５）式のように
変化して、卑金属側で腐食が進行する二次的な弊害も生
まれてくる。この結果、下記（６）式に示すように水酸
化鉄（Ｆｅ（ＯＨ)2）が発生する。2Fe (HCO 3 ) 2 +1/2 O 2 → Fe 2 O 3 + 4CO 2 + 2H 2 O (3) Furthermore, if the generated iron oxide precipitates on the steel surface in water,
This becomes the noble metal side, and a galvanic couple occurs with the steel surface as the base metal side, which changes as in the following equations (4) and (5), and secondary adverse effects such that corrosion progresses on the base metal side also arise. As a result, iron hydroxide (Fe (OH) 2 ) is generated as shown in the following equation (6).
【０００９】 卑金属側：Ｆｅ → Ｆｅ2+＋２ｅ ---（４） 貴金属側：1/2 Ｏ2 ＋Ｈ2Ｏ＋２ｅ→２（ＯＨ-） ---（５） Ｆｅ2+＋２ＯＨ- → Ｆｅ（ＯＨ)2 ---（６） 本発明はこのような事情に鑑みてなされたものであり、
本発明の目的は、高・中圧蒸気還水配管の腐食の進行を
抑制できる高・中圧蒸気還水配管の腐食防止方法を提供
することにある。Base metal side: Fe → Fe 2+ + 2e --- (4) Noble metal side: 1/2 O 2 + H 2 O + 2e → 2 (OH − ) --- (5) Fe 2+ + 2OH − → Fe (OH) ) 2 --- (6) The present invention has been made in view of such circumstances,
An object of the present invention is to provide a method for preventing corrosion of high / medium pressure steam return water piping that can suppress the progress of corrosion of high / medium pressure steam return water piping.
【００１０】[0010]
【課題を解決するための手段】上記目的を達成するため
に、本発明者等は種々の検討を重ねた結果、高・中圧蒸
気の還水は温度が高く、負圧下では還水の再蒸発現象が
生じるため、従来、負圧による空気・不凝縮ガスの排気
を行っていないことに着目し、本発明を完成した。In order to achieve the above object, the present inventors have made various studies, and as a result, the return water of high- and medium-pressure steam has a high temperature. The present invention has been completed by paying attention to the fact that air / non-condensable gas is not exhausted by a negative pressure because an evaporation phenomenon occurs.
【００１１】即ち、本発明に係る高・中圧蒸気還水配管
の腐食防止方法は、ボイラーで発生した高・中圧蒸気の
還水配管の腐食を防止する方法であって、蒸気供給停止
後に還水温度が所定温度以下になるのを待って、末端が
ホットウエルタンク内に水没された還水配管内を真空ポ
ンプによって所定範囲の負圧に維持することを特徴とす
る。That is, the method for preventing corrosion of high- and medium-pressure steam return water piping according to the present invention is a method for preventing corrosion of high- and medium-pressure steam return water piping generated in a boiler. Waiting for the return water temperature to fall below a predetermined temperature, the vacuum pump is used to maintain a negative pressure within a predetermined range in a return water pipe whose terminal is submerged in the hot well tank.
【００１２】なお、還水温度が所定温度以下になったか
否かは、タイマーまたは温度センサーにて行うものと
し、例えば−300 mmHgの負圧に維持する場合は86℃以下
になるのを待って、真空ポンプの運転を行う。Whether or not the return water temperature has fallen below the predetermined temperature is determined by a timer or a temperature sensor. For example, when maintaining a negative pressure of -300 mmHg, wait until the temperature falls below 86 ° C. , Operate the vacuum pump.
【００１３】[0013]
【作用】本発明に係る高・中圧蒸気還水配管の腐食防止
方法では、ボイラーを停止して、高・中圧蒸気の供給が
停止されると、還水温度が所定温度以下になるのを待っ
て、末端がホットウエルタンク内に水没された還水配管
内を真空ポンプによって所定範囲の負圧に維持する。こ
こでは、還水配管の末端をホットウエルタンク内に水没
させた状態で、所定温度以下になってから還水配管内を
負圧に維持するので、負圧下での還水の再蒸発現象が生
じることなく管内を負圧に維持できる。このため、管内
が吸引されて管内に空気や不凝縮ガスが残留しにくくな
り、還水配管の腐食の進行を抑制できる。According to the method for preventing corrosion of high / medium pressure steam return water piping according to the present invention, when the boiler is stopped and the supply of high / medium pressure steam is stopped, the return water temperature falls below a predetermined temperature. After that, the inside of the return water pipe whose terminal is submerged in the hot well tank is maintained at a predetermined range of negative pressure by a vacuum pump. Here, while the end of the return water pipe is submerged in the hot well tank, the return pressure inside the return water pipe is maintained at a negative pressure after the temperature falls below a predetermined temperature. It is possible to maintain the inside of the tube at a negative pressure without occurrence. For this reason, the inside of the pipe is sucked and air and non-condensable gas hardly remain in the pipe, and the progress of corrosion of the return water pipe can be suppressed.
【００１４】[0014]
【実施例】図１は、本発明方法の実施に用いられる高・
中圧蒸気配管系の概略系統図である。図において、空気
調和装置は、一端に配置されたボイラー１０と、空調機
器として途中に配置された蒸気コイルまたは熱交換器１
１と、他端に配置されたホットウェルタンク（ＨＷＴ）
１２と、ボイラー１０と蒸気コイルまたは熱交換器１１
とを連結する蒸気供給配管１３と、蒸気コイルまたは熱
交換器１１とホットウェルタンク１２とを連結する還水
配管１４と、還水配管１４の途中から分岐してホットウ
ェルタンク１２上の空気中に端部が開放されている排気
配管１７と、排気配管１７の途中に配置された真空ポン
プ（ＶＰ）１８とを備えている。ホットウエルタンク１
２は、蒸気を復水した温水をボイラー１０に再び給水す
る前に一時蓄える水槽である。蒸気供給配管１３の途中
には蒸気の供給を制御するための自動制御弁（ＭＶ）１
５が配置されている。還水配管１４の途中には蒸気の還
水等を分離するための蒸気トラップ１６が配置されてい
る。排気配管１７において、真空ポンプ１８の上流側に
は、管内の真空圧が過大にならないための真空破壊弁１
９が分岐して設けられている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG.
It is a schematic system diagram of a medium pressure steam piping system. In the figure, an air conditioner includes a boiler 10 disposed at one end and a steam coil or a heat exchanger 1 disposed midway as an air conditioner.
1 and a hot well tank (HWT) located at the other end
12, boiler 10 and steam coil or heat exchanger 11
, A return water pipe 14 connecting the steam coil or heat exchanger 11 and the hot well tank 12, and a branch from the middle of the return water pipe 14, and The exhaust pipe 17 has an open end, and a vacuum pump (VP) 18 disposed in the middle of the exhaust pipe 17. Hot well tank 1
Reference numeral 2 denotes a water tank for temporarily storing hot water having condensed steam before supplying the boiler 10 with water again. An automatic control valve (MV) 1 for controlling the supply of steam is provided in the middle of the steam supply pipe 13.
5 are arranged. In the middle of the return water pipe 14, a steam trap 16 for separating steam return water or the like is arranged. In the exhaust pipe 17, on the upstream side of the vacuum pump 18, a vacuum break valve 1 for preventing the vacuum pressure in the pipe from becoming excessive.
9 is provided in a branched manner.
【００１５】次に真空ポンプの運転制御の仕方について
説明する。真空ポンプを運転する条件としては、ボイラ
ー停止指令中、すなわち蒸気供給停止中で、かつ還水管
内圧力が所定の負圧に維持されていない場合である。こ
れらの一連の制御システムは公知の制御シーケンスおよ
び蒸気供給信号、タイマー、または温度センサー、およ
び真空センサーを用いることにより容易に実現できる。Next, a method of controlling the operation of the vacuum pump will be described. The condition for operating the vacuum pump is that a boiler stop command is being issued, that is, steam supply is being stopped, and the pressure in the return pipe is not maintained at a predetermined negative pressure. These series of control systems can be easily implemented using known control sequences and steam supply signals, timers or temperature sensors, and vacuum sensors.
【００１６】[0016]
【発明の効果】本発明に係る高・中圧蒸気還水配管の腐
食防止方法では、還水配管の末端をホットウエルタンク
内に水没させた状態で、所定温度以下になってから還水
配管内を負圧に維持するので、負圧下での還水の再蒸発
現象が生じることなく管内を負圧に維持できる。このた
め、管内が吸引されて管内に空気や不凝縮ガスが残留し
にくくなり、還水配管の腐食の進行を抑制できる。According to the method for preventing corrosion of high- and medium-pressure steam return water pipes according to the present invention, the return water pipe must be cooled to a predetermined temperature or less while the end of the return water pipe is submerged in the hot well tank. Since the inside is maintained at a negative pressure, the inside of the pipe can be maintained at a negative pressure without re-evaporation phenomenon of the return water under the negative pressure. For this reason, the inside of the pipe is sucked and air and non-condensable gas hardly remain in the pipe, and the progress of corrosion of the return water pipe can be suppressed.
【図１】本発明方法の実施に用いる高・中圧蒸気配管系
の概略系統図である。FIG. 1 is a schematic system diagram of a high / medium pressure steam piping system used for carrying out the method of the present invention.
【図２】従来方法の実施に用いる従来の高・中圧蒸気配
管系の概略系統図である。FIG. 2 is a schematic system diagram of a conventional high / medium pressure steam piping system used for implementing a conventional method.
１０・・ボイラー １１・・蒸気コイルまたは熱交換器 １２・・ホットウエルタンク １４・・還水配管 １７・・排気配管 １８・・真空ポンプ １９・・真空
破壊弁10. Boiler 11. Steam coil or heat exchanger 12. Hot well tank 14. Return water pipe 17. Exhaust pipe 18. Vacuum pump 19. Vacuum break valve
Claims (1)
配管の腐食を防止する方法であって、 前記ボイラーからの蒸気供給停止後に還水温度が所定温
度以下になるのを待って、末端がホットウエルタンク内
に水没された前記還水配管内を真空ポンプによって所定
範囲の負圧に維持し、空気、不凝縮ガス等の腐食要因ガ
スを排気することを特徴とする高・中圧蒸気還水配管の
腐食防止方法。1. A method for preventing corrosion of a return pipe for high- and medium-pressure steam generated in a boiler, the method comprising: after the supply of steam from the boiler is stopped, waiting until the return water temperature falls below a predetermined temperature; A high pressure and a medium pressure, wherein the inside of the return water pipe whose end is submerged in a hot well tank is maintained at a negative pressure within a predetermined range by a vacuum pump, and a corrosive gas such as air and non-condensable gas is exhausted. Corrosion prevention method for steam return water piping.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25238494A JP2735004B2 (en) | 1994-10-18 | 1994-10-18 | Corrosion prevention method for high and medium pressure steam return piping |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25238494A JP2735004B2 (en) | 1994-10-18 | 1994-10-18 | Corrosion prevention method for high and medium pressure steam return piping |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH08114301A JPH08114301A (en) | 1996-05-07 |
| JP2735004B2 true JP2735004B2 (en) | 1998-04-02 |
Family
ID=17236577
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP25238494A Expired - Lifetime JP2735004B2 (en) | 1994-10-18 | 1994-10-18 | Corrosion prevention method for high and medium pressure steam return piping |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2735004B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106593898B (en) * | 2016-12-27 | 2018-05-01 | 滨州市甲力太阳能科技有限公司 | Geothermal pump well automatic control water-change pump |
| CN111594818B (en) * | 2020-06-17 | 2021-08-24 | 新疆心连心能源化工有限公司 | Device for effectively reducing temperature of boiler steam main pipe and using method thereof |
-
1994
- 1994-10-18 JP JP25238494A patent/JP2735004B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH08114301A (en) | 1996-05-07 |
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