JPH04337192A - Reduction method of pressure increase in case of water column separation - Google Patents
Reduction method of pressure increase in case of water column separationInfo
- Publication number
- JPH04337192A JPH04337192A JP3107099A JP10709991A JPH04337192A JP H04337192 A JPH04337192 A JP H04337192A JP 3107099 A JP3107099 A JP 3107099A JP 10709991 A JP10709991 A JP 10709991A JP H04337192 A JPH04337192 A JP H04337192A
- Authority
- JP
- Japan
- Prior art keywords
- water column
- column separation
- pressure
- case
- pressure increase
- 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
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 238000000926 separation method Methods 0.000 title claims abstract description 26
- 238000000034 method Methods 0.000 title claims abstract description 8
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 6
- 238000009434 installation Methods 0.000 abstract description 7
- 238000010276 construction Methods 0.000 abstract 1
- 230000000630 rising effect Effects 0.000 description 5
- 230000007423 decrease Effects 0.000 description 2
- 239000011800 void material Substances 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 230000005514 two-phase flow Effects 0.000 description 1
Landscapes
- Pipeline Systems (AREA)
- Pipe Accessories (AREA)
Abstract
Description
【０００１】0001
【産業上の利用分野】上下水道等の管路系における、水
柱分離現象時の圧力上昇低減方法に関する。[Industrial Application Field] This invention relates to a method for reducing pressure rise during water column separation phenomenon in water and sewage pipeline systems.
【０００２】0002
【従来の技術】ポンプを備えた管路内の圧力低下が蒸気
圧まで低下すると、そこで水柱分離が起こり空洞が発生
する。この空洞の消減に伴い管路内に高い圧力上昇が生
じ、その衝撃圧により管路が破損するおそれがある。そ
こで管路の破損等の原因となる空洞消減時の高い圧力上
昇を防止し空洞を生じないように対策していた。その具
体例を以下に示す。BACKGROUND OF THE INVENTION When the pressure drop in a pipeline equipped with a pump drops to vapor pressure, separation of the water column occurs and cavities are created. As this cavity disappears, a high pressure rise occurs within the pipe, and the impact pressure may cause the pipe to be damaged. Therefore, measures were taken to prevent the formation of cavities by preventing the high pressure rise when the cavities disappear, which could cause damage to the pipelines. A specific example is shown below.
【０００３】すなわち、 （１）管路に立上り部のないように配管系を設ける。[0003] That is, (1) Install the piping system so that there are no rising parts of the pipe.
【０００４】（２）サージタンクを設ける。(2) Provide a surge tank.
【０００５】（３）ワンウェイサージタンクを設ける。(3) A one-way surge tank is provided.
【０００６】（４）空気弁を設ける。(4) Provide an air valve.
【０００７】（５）圧力水槽を設ける。(5) Provide a pressure water tank.
【０００８】（６）ポンプにフライホイールを設ける。(6) A flywheel is provided on the pump.
【０００９】（出典「水撃解析法」Ｊｏｈｎ Ｐａｒｍ
ａｋｉａｎ著 小堀，横山訳 出版 コロナ社）
これら従来の技術は地形的な制約を受けたり、装置の設
置場所、大きさを考慮しなければならない。また、（６
）のように制御を必要とするとポンプ等の特性を考慮し
なければならず、負圧軽減対策にも問題が出てくる。(Source: “Water hammer analysis method” John Parm
Written by Akian, translated by Kobori and Yokoyama, published by Coronasha)
These conventional techniques are subject to topographical constraints and must take into consideration the installation location and size of the device. Also, (6
), if control is required, the characteristics of the pump, etc. must be taken into account, and problems arise in measures to reduce negative pressure.
【００１０】そこで、負圧対策として圧力降下が起こっ
た時、エアー弁よりエアを吸入することにより水柱分離
を防止し、逆止弁および逆止弁を迂回するバイパス管の
作用と合わせて圧力上昇を防止する。（実公昭４８−９
６８１号公報）のものも考案されている。しかし実公昭
４８−９６８ 号公報に記載のものは、逆止弁の制御が
重要でありこの制御の方法によっては、弁閉鎖による水
撃現象が生じてしまう。また、管路は、ほとんど、地下
に埋設されるのでバイパス管の設置には費用，設置場所
等の問題も出てくる。[0010] Therefore, as a countermeasure against negative pressure, when a pressure drop occurs, air is sucked in from the air valve to prevent water column separation, and together with the action of the check valve and the bypass pipe that bypasses the check valve, the pressure rises. prevent. (Jikko 48-9
681) has also been devised. However, in the device described in Japanese Utility Model Publication No. 48-968, control of the check valve is important, and depending on the control method, a water hammer phenomenon may occur due to valve closure. Furthermore, since most pipelines are buried underground, installation of bypass pipes poses problems such as cost and location.
【００１１】[0011]
【発明が解決しようとする課題】本発明の目的は、制御
及び広い設置場所を必要としない、水柱分離時の圧力上
昇低減方法を提供することにある。SUMMARY OF THE INVENTION An object of the present invention is to provide a method for reducing pressure rise during water column separation that does not require control or a large installation space.
【００１２】0012
【課題を解決するための手段】本発明は管路破損等の原
因となる高い圧力上昇を防止するため、水柱分離の発生
が予測される場所で負圧になったとき、その場所の上流
と下流側、または、そのどちらか一方、空気を混入また
は発生させる部品を設ける。[Means for Solving the Problems] In order to prevent high pressure increases that may cause pipeline breakage, the present invention provides a system for preventing high pressure increases that may cause pipeline breakage, etc. when negative pressure occurs at a location where water column separation is expected to occur A part that mixes or generates air is provided on the downstream side or either of them.
【００１３】[0013]
【作用】管路内の流速が急に変化すると、それに伴って
管路内の圧力が急激に変化し圧力上昇、圧力降下を繰り
返す。この圧力降下時に、圧力が蒸気圧まで低下すると
そこで蒸気が起こり、空洞をふくむ二相流となる。この
空洞が圧力波の伝播によりつぶされたとき、水撃現象時
より高い圧力上昇が起こり管路を破損する。しかし、管
路内で水柱分離が生じてもそれは空洞が消減するときに
高い圧力上昇が起こることを必ずしも意味するものでは
ない。管路を破損する高い圧力を発生するのに十分に流
速を生じるには、大きな動水勾配が必要である。この動
水勾配は基準面からの配管の高さと圧力水頭の和で表わ
される。[Operation] When the flow velocity in the pipe changes suddenly, the pressure in the pipe changes rapidly, and the pressure rises and falls repeatedly. During this pressure drop, when the pressure decreases to the vapor pressure, steam is generated there, resulting in a two-phase flow that includes the cavity. When this cavity is collapsed by the propagation of pressure waves, a higher pressure rise than during the water hammer phenomenon occurs, causing damage to the pipeline. However, the occurrence of water column separation within the conduit does not necessarily mean that a high pressure rise will occur as the cavity disappears. Large hydraulic gradients are required to generate flow velocities sufficient to generate high pressures that can rupture the pipeline. This hydraulic gradient is expressed as the sum of the height of the pipe from the reference plane and the pressure head.
【００１４】水撃現象時の圧力水頭は、文献「明解
水理学」日野幹雄著に示されるように式（１）で示され
る。[0014] The pressure head during the water hammer phenomenon is described in the literature ``Clear explanation.
As shown in "Hydraulics" written by Mikio Hino, it is expressed by equation (1).
【００１５】[0015]
【数１】[Math 1]
【００１６】そこで本発明では式（１）の圧力波伝播速
度を低下させることにより動水勾配を小さくし、高い圧
力上昇を低減する。Therefore, in the present invention, the hydraulic gradient is reduced by lowering the pressure wave propagation velocity in equation (1), thereby reducing the high pressure rise.
【００１７】文献ＦＬＵＩＤ ＴＲＡＮＳＩＥＮＴ Ｗ
ｙｌｉｅ／Ｓｔｒｅｅｔｅｒ著の１４１ページのＦｉｇ
ｕｒｅ ８−３，Ｐ１４１ページのＦｉｇｕｒｅ８−４
に示されるように液体で満たされている管路内の圧力波
伝播速度は管路内の空気量により低下する。
例えば、Ｆｉｇｕｒｅ８−３によれば、圧力水頭が１６
ｍのとき、空気量がボイド率で０．０００１％ の場合
、圧力波伝播速度は約１３００ｍ／Ｓなのに対し、空気
量がボイド率で１．０％ の場合では、圧力波伝播速度
は２００ｍ／Ｓ以下になっている。Literature FLUID TRANSIENT W
Fig on page 141 by ylie/Streeter
ure 8-3, Figure 8-4 on page 141
As shown in , the pressure wave propagation velocity in a liquid-filled pipe decreases depending on the amount of air in the pipe. For example, according to Figure 8-3, the pressure head is 16
m, when the air volume is 0.0001% in void ratio, the pressure wave propagation velocity is approximately 1300 m/s, whereas when the air volume is 1.0% in void ratio, the pressure wave propagation velocity is 200 m/s. It is below S.
【００１８】本発明の水柱分離現象時の圧力上昇低減方
法は、水柱分離の発生が予測される場所の上流と下流側
、または、そのどちらか一方の圧力波伝播速度を低下さ
せる。それにより水柱分離時の負圧波の伝播を遅くする
ことで空洞消減時の高い圧力上昇を抑える。従って、水
柱分離時の空洞消減に伴う高い圧力上昇を低減し、管路
の破損等を防ぐことができる。The method of reducing pressure rise during a water column separation phenomenon according to the present invention reduces the pressure wave propagation velocity upstream and/or downstream of a location where water column separation is predicted to occur. This slows down the propagation of negative pressure waves when the water column separates, thereby suppressing the high pressure rise when the cavity disappears. Therefore, it is possible to reduce the high pressure increase caused by the disappearance of cavities during water column separation, and to prevent damage to the pipe line.
【００１９】[0019]
【実施例】次に本発明を図１に従って説明する。図１は
本発明を適用した停電等によりポンプの電動機の電源が
しや断されて急に動力を失った場合の水柱分離時の圧力
上昇低減方法を示している。EXAMPLE Next, the present invention will be explained with reference to FIG. FIG. 1 shows a method of reducing pressure rise during water column separation to which the present invention is applied when the power to the motor of the pump is suddenly cut off due to a power outage or the like and the power is suddenly lost.
【００２０】図１は、貯水池１，管路２，吐出し槽４，
ポンプ５，逆止弁６より成る管路系を示したものである
。停電等によりポンプが急に動力を失った場合、管路の
立上り部ａで水柱分離が起こり空洞が発生する。従来は
管路の立上り部にサージタンク等を設けることにより水
柱分離を生じないような対策を行っていた。サージタン
クは管路との接続管が十分大きいと見掛け上は吐出し水
槽となり、サージタンク以降、吐出し負圧は防止される
。また、サージタンクは単なる水槽のため、制御がいら
ず信頼性はもっとも高い。しかし、サージタンク水面を
動水勾配以上としなければならず、また、管内径の太い
長距離管の場合は、逆流量を考慮しサージタンク容量は
大きくとらなくてはならない。そのため地形的な制約を
受け設置が不可能である場合がある。そこで本発明によ
れば、立上り部ａの水柱分離の発生の予測場所で、負圧
が生じたときその上流側と下流側に空気弁３等により空
気を混入させる。それにより管路内の圧力波伝播速度を
低下させ、水柱分離ａの負圧波の伝播を遅くすることで
空洞消減時の高い圧力上昇を抑える。一例を示すと管内
径２．２ｍ ，管路長さ４１６７ｍ，管肉厚２８ｍｍ，
材質が鋼管の場合、空気が存在しない場合の圧力波伝播
速度は１００４．０ｍ／Ｓ であるが、管路内の圧力水
頭が１００ｍで図１の立上り部の上流と下流側に約０．
５ｍ３ずつ空気弁３等の部品により空気を混入する場合
、圧力波伝播速度は約６５０ｍ／Ｓに下がり、水柱分離
時の高い圧力上昇は三分の二に抑えられる。FIG. 1 shows a reservoir 1, a pipe line 2, a discharge tank 4,
This figure shows a pipe system consisting of a pump 5 and a check valve 6. If the pump suddenly loses power due to a power outage or the like, water column separation occurs at the rising portion a of the pipe, creating a cavity. Conventionally, measures have been taken to prevent water column separation by providing a surge tank or the like at the rising end of the pipeline. If the surge tank has a sufficiently large connection pipe to the pipeline, it will appear to be a discharge water tank, and discharge negative pressure will be prevented from the surge tank onwards. Also, since the surge tank is just a water tank, it requires no control and has the highest reliability. However, the surge tank water level must be higher than the hydraulic gradient, and in the case of long-distance pipes with large inner diameters, the surge tank capacity must be increased to account for backflow. Therefore, installation may be impossible due to topographical constraints. Therefore, according to the present invention, when negative pressure is generated at the predicted location of the water column separation in the rising portion a, air is mixed into the upstream and downstream sides thereof using the air valve 3 or the like. This reduces the pressure wave propagation speed within the pipe and slows down the propagation of the negative pressure wave in the water column separation a, thereby suppressing a high pressure rise when the cavity disappears. As an example, the inner diameter of the pipe is 2.2 m, the length of the pipe is 4167 m, the wall thickness is 28 mm,
When the material is steel pipe, the pressure wave propagation velocity in the absence of air is 1004.0 m/s, but when the pressure head in the pipe is 100 m, there is a pressure wave propagation velocity of about 0.0 m/s on the upstream and downstream sides of the rising part in Fig. 1.
When air is mixed in by 5 m3 using parts such as the air valve 3, the pressure wave propagation velocity is reduced to about 650 m/s, and the high pressure increase during water column separation is suppressed to two-thirds.
【００２１】公知例（実公昭４８−９６８１号公報）で
は、水柱分離の発生が予測される場所に空気を混入し、
最初の水柱分離は下流側の吐出し水槽等へ自然流下させ
る。しかし、管路系によっては吐出し水槽側の水が逆流
し空気弁より空気を押し出すとともに、その流速差によ
りポンプ側の水柱へ衝突し、大きな圧力上昇の問題があ
るためバイパス管により水の逆流を緩和している。その
ため、バイパス管のような余分な設備が必要であった。
本発明では、水柱分離の発生が予測される場所ではなく
、その少し離れた上流側と下流側、または、そのどちら
か一方に空気を混入または発生させ、圧力波伝播速度を
低下させることにより、空洞消減に伴う高い圧力上昇を
低減する。それにより空洞消減後に、再び、水撃現象及
び水柱分離現象の発生することを防ぎ、余分な設備を必
要としない。In a known example (Japanese Utility Model Publication No. 48-9681), air is mixed into a place where water column separation is expected to occur,
The first separation of the water column is carried out by allowing it to flow naturally to a discharge tank or the like on the downstream side. However, depending on the pipe system, the water from the discharge tank side flows backwards, pushing air out of the air valve, and due to the difference in flow velocity, it collides with the water column on the pump side, causing a problem with a large pressure increase, so the water flows backwards through the bypass pipe. is being eased. Therefore, extra equipment such as a bypass pipe was required. In the present invention, air is mixed in or generated not at the location where water column separation is expected to occur, but at a slightly distant upstream and downstream side, or either of the two, thereby reducing the pressure wave propagation speed. Reduces the high pressure rise associated with cavity elimination. This prevents the water hammer phenomenon and water column separation phenomenon from occurring again after the cavity has disappeared, and no extra equipment is required.
【００２２】[0022]
【発明の効果】本発明によれば制御及び広い設置場所な
しの簡単な構成で、水柱分離時の圧力上昇低減が可能で
ある。According to the present invention, it is possible to reduce pressure rise during water column separation with a simple configuration that does not require control or a large installation space.
【図１】本発明の一実施例を示す系統図。FIG. 1 is a system diagram showing one embodiment of the present invention.
１…貯水池、２…管路、３…空気弁、４…吐出し槽、５
…ポンプ、６…逆止弁。1...Reservoir, 2...Pipe line, 3...Air valve, 4...Discharge tank, 5
...Pump, 6...Check valve.
Claims (1)
が予想される場所の上流と下流側またはそのどちらか一
方に、負圧時に空気を混入または発生させる部品を設け
ることを特徴とする水柱分離時の圧力上昇低減方法。Claim 1: A pipeline system equipped with a pump, characterized in that a component that mixes or generates air when negative pressure is provided is provided upstream and/or downstream of a location where water column separation is expected to occur. A method for reducing pressure rise during water column separation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3107099A JPH04337192A (en) | 1991-05-13 | 1991-05-13 | Reduction method of pressure increase in case of water column separation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3107099A JPH04337192A (en) | 1991-05-13 | 1991-05-13 | Reduction method of pressure increase in case of water column separation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH04337192A true JPH04337192A (en) | 1992-11-25 |
Family
ID=14450437
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3107099A Pending JPH04337192A (en) | 1991-05-13 | 1991-05-13 | Reduction method of pressure increase in case of water column separation |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH04337192A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2022131059A (en) * | 2021-02-26 | 2022-09-07 | 株式会社シンテック | Water hammer cushioning method and its device |
-
1991
- 1991-05-13 JP JP3107099A patent/JPH04337192A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2022131059A (en) * | 2021-02-26 | 2022-09-07 | 株式会社シンテック | Water hammer cushioning method and its device |
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