JP4836103B2 - Pump flow rate measuring method and pump flow rate measuring device - Google Patents
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Description
【０００１】
【発明の属する技術分野】
本発明は、調圧水槽が設けられた排水設備などに設置されているポンプの吐出流量を測定するポンプ流量測定方法およびポンプ流量測定装置に関するものである。
【０００２】
【従来の技術】
排水機場などの排水設備にあっては、ポンプの吐出流量の急激な変化による圧力変動を吸収するために、ポンプと排出水域との間に調圧水槽が設けられる。そこで、ポンプの吐出配管が調圧水槽に接続され、この調圧水槽が排出水域に排水管で連通される。この調圧水槽を設けることで、ポンプの吐出が急激に停止し、あるいはポンプの始動時において、吐出配管内の圧力変動を抑制し、またポンプの吐出が急激に停止したときには調圧水槽内の流体が慣性の法則でひき続き排水管を介して排出水域に流出し、吐出配管の水撃現象を抑制する。さらに、排出水域の水位の急激な変動をも抑制する。
【０００３】
ところで、排水設備に設置されたポンプの吐出流量の測定は、吐出配管内の流速を超音波流量計で行うものがある。また、予めポンプ出荷前に工場などでポンプの流量−全場程曲線を実測し、これと現地の設置条件から実測により得られる配管全体の抵抗曲線との交点からポンプの吐出流量を測定するものもある。
【０００４】
【発明が解決しようとする課題】
上述の超音波流量計によるポンプの吐出流量の測定では、ポンプの吐出口と調圧水槽の間に介装される吐出配管直管部の長さを充分に長くする必要がある。これは、流量を正確に測定するためには吐出配管直管部内の流れが安定していなければならないためである。しかるに、排水設備の設置スペースなどの制約から、充分な長さの吐出配管直管部を設けることは現実的には困難である。
【０００５】
また、流量−全場程曲線を用いて吐出流量を算出する方法では、ポンプ羽根車の経年変化により実際の流量−全場程曲線が変化し、また配管の摩擦損失やバルブの損失も変化して配管全体の抵抗曲線も変化し、吐出流量の算出精度が年々悪化する傾向にある。
【０００６】
本発明は、上述のごとき従来技術の不具合に鑑みてなされたもので、調圧水槽と排出水域の水位差からポンプの排出流量を簡単にかつ正確に算出できるポンプ流量測定方法およびポンプ流量測定装置を提供することを目的とする。
【０００７】
【課題を解決するための手段】
上記目的を達成するために、本発明のポンプ流量測定方法は、ポンプの吐出配管が調圧水槽に接続され、この調圧水槽が排出水域に排水管で連通され、しかも前記排水管が前記排出水域の水面下にあって常に満水状態が保持される排水設備であって、前記ポンプの運転時における前記調圧水槽の水位Ｈ１と、前記排出水域の水位Ｈ２と、前記ポンプからの流入を停止した際に生ずる前記調圧水槽の水位と前記排出水域の水位との偏差水位変動および前記排水管内の流体の流体運動方程式から予め算出された前記排水管の損失係数ξと、前記排水管の断面積Ａから、
【数４】
により前記ポンプの吐出流量Ｑを算出する。
【０００８】
そして、前記ポンプの吐出を急激に停止させてた際に生ずる前記調圧水槽の水位と前記排出水域の水位との偏差水位変動と、その際の前記排水管内の流体の流体運動方程式から前記損失係数ξを予め算出しておいても良い。
【０００９】
さらに、前記ポンプからの流入を停止するとともに前記排水管を遮断して前記調圧水槽の水位と前記排出水域の水位に水位差を設け、前記排水管を急激に連通した際に生ずる前記調圧水槽の水位と前記排出水域の水位との偏差水位変動と、その際の前記排水管内の流体の流体運動方程式から前記損失係数ξを予め算出しておくこともできる。
【００１０】
また、本発明のポンプ流量測定装置は、ポンプの吐出配管が調圧水槽に接続され、この調圧水槽が排出水域に排水管で連通され、しかも前記排水管が前記排出水域の水面下にあって常に満水状態が保持される排水設備であって、前記調圧水槽にその水位Ｈ１を計測する第１の水位計測手段を設け、前記排出水域にその水位Ｈ２を計測する第２の水位計測手段を設け、前記第１と第２の計測手段の計測値が与えられてその水位差を演算する水位差演算手段と、前記水位差に応じた信号を与えられる記録手段を設け、この記録手段で、前記ポンプの吐出が急激に停止された際に生ずる前記調圧水槽の水位と前記排出水域の水位との偏差水位変動曲線を記録し、記録された偏差水位変動曲線と前記排水管内の流体の流体運動方程式より損失係数演算手段で予め損失係数ξを算出し、この損失係数ξを演算手段に設定し、前記第１と第２の計測手段の計測値を前記演算手段に与え、この演算手段で前記水位Ｈ１およびＨ２と、予め算出して設定された前記排水管の損失係数ξと、前記排水管の断面積Ａと、から
【数５】
により前記ポンプの吐出流量Ｑを算出するように構成されている。
【００１１】
また、ポンプの吐出配管が調圧水槽に接続され、この調圧水槽が排出水域に排水管で連通され、しかも前記排水管が前記排出水域の水面下にあって常に満水状態が保持される排水設備であって、前記調圧水槽にその水位Ｈ１を計測する第１の水位計測手段を設け、前記排出水域にその水位Ｈ２を計測する第２の水位計測手段を設け、前記第１と第２の計測手段の計測値が与えられてその水位差を演算する水位差演算手段と、前記水位差に応じた信号を与えられる記録手段を設け、この記録手段で、前記ポンプからの流入を停止するとともに前記排水管を遮断して前記調圧水槽の水位と前記排出水域の水位に水位差を設け、前記排水管を急激に連通した際に生ずる前記調圧水槽の水位と前記排出水域の水位との偏差水位変動曲線を記録し、記録された偏差水位変動曲線と前記排水管内の流体の流体運動方程式より損失係数演算手段で予め損失係数ξを算出し、この損失係数ξを演算手段に設定し、前記第１と第２の計測手段の計測値を前記演算手段に与え、この演算手段で前記水位Ｈ１およびＨ２と、予め算出して設定された前記排水管の損失係数ξと、前記排水管の断面積Ａと、から
【数６】
により前記ポンプの吐出流量Ｑを算出するように構成しても良い。
【００１２】
【発明の実施の形態】
以下、本発明の第１実施例を図１ないし図４を参照して説明する。図１は、本発明のポンプ流量測定装置の第１の実施例の構造図であり、（ａ）はポンプの定常運転時の水位を示し、（ｂ）はポンプの運転が急激に停止されて調圧水槽の水位が排出水域の水位より低下した状態を示し、（ｃ）は再び調圧水槽の水位が排出水域の水位より上昇した状態を示し、（ｄ）は再び調圧水槽の水位が排出水域の水位より低下した状態を示す。図２は、オシロスコープに記録された調圧水槽の水位と排出水域の水位の偏差水位変動曲線を示す図である。図３は、偏差水位の理論変動曲線を示す図である。図４は、本発明によるポンプの吐出流量の算出値と実測値とを示す表である。
【００１３】
まず、図１において、本発明の第１実施例は、ポンプ１０の吐出配管１２が調圧水槽１４に接続され、この調圧水槽１４が河川などの排出水域１６と排水管１８で連通される。この排水管１８は、排出水域１６の水面下に配設され、常に満水状態が保持される。また、調圧水槽１４には、その水位を測定する第１の水位計測手段２０が配設され、排出水域１６には、その水位を測定する第２の水位計測手段２２が配設される。そして、第１と第２の水位計測手段２０，２２の計測値が水位差演算手段２４に与えられて水位差が演算される。この水位差に応じた信号が、演算手段２６とオシロスコープなどの記録手段２８とに与えられる。記録手段２８は、一例として図２に示すごとき、時間の経過と水位差の変動を示す偏差水位変動曲線を記録する。そして、この偏差水位変動曲線が損失係数演算手段３０に与えられ、後述のごとくして損失係数ξが演算され、この損失係数ξが演算手段２６に設定される。演算手段２６では、予め算出して設定された損失件数ξと、ポンプ１０の定常運転状態の調圧水槽１４と排出水域１６の水位の水位差（Ｈ１−Ｈ２）と、排水管１８の断面積Ａとからポンプ１０の流量Ｑを後述のごとくして演算出力する。
【００１４】
ところで、ポンプ１０の定常運転状態にあっては、調圧水槽１４の水位Ｈ１が排出水域１６の水位Ｈ２よりも高く、その水位差（Ｈ１−Ｈ２）と排水管１８内の平均流速Ｖの二乗とが比例する。そして、排水管１８の断面積Ａと平均流速Ｖの積が、ポンプ１０の吐出する流量Ｑである。そこで、比例計数としての損失係数ξが予め演算されていれば、調圧水槽１４と排出水域１６の水位の水位差（Ｈ１−Ｈ２）からポンプ１０の吐出する流量Ｑが演算できる。そこで、（２）式と（３）式が成立する。
【数７】
但し、ξは損失係数、Ｖは排水管内の平均流速である。
【数８】
但し、Ｑはポンプの吐出流量、Ａは排出管の断面積である。
そして、これらの（２）（３）式から、上述の（１）式が得られる。
【数９】
ここで、排水管１８の断面積Ａは、容易に計測または算出でき、また水位Ｈ１，Ｈ２も第１と第２の水位計測手段２０，２２により容易に測定し得る。なお、損失係数ξは、一度だけ予め測定算出すれば良く、流量測定の度に繰り返して算出する必要はない。
なお、排水管１８の損失係数ξとその断面積Ａ、および水位差から流量を求めることは、公知であり、特開平０５−１９８６４号公報（特許文献１）や特開平１０−１８５６３５号公報（特許文献２）等に示されている。
【特許文献１】
特開平０５−１９８６４号公報
【特許文献２】
特開平１０−１８５６３５号公報
【００１５】
続いて、損失係数ξを算出する方法につき以下述べる。ポンプ１０の定常運転にて調圧水槽１４が水位Ｈ１で排出水域１６が水位Ｈ２の状態で、ポンプ１０の運転を急激に停止して吐出流量Ｑを零とする。すると、ポンプ１０からの流入が停止し、調圧水槽１４側の高い水位差および排水管１８内を流れる水の慣性で、水は排出水域１６に流れ続けて調圧水槽１４の水位は低下し続け、（ｂ）に示すごとく、調圧水槽１４の水位が排出水域１６の水位Ｈ２より低いＨ３まで変動する。するとこんどは、排出水域１６側の高い水位差により排水管１８内を逆流し、調圧水槽１４の水位は上昇し、（ｃ）に示すごとく、排出水域１６の水位Ｈ２よりも高いＨ４まで変動する。さらにこんどは、調圧水槽１４側の水位が高いことで、水が排水管１８内を排出水域１６に流れて、（ｄ）に示すごとく調圧水槽１４の水位は排出水域１６の水位よりも低いＨ５まで変動する。もって、偏差水位変動を生ずる。
【００１６】
このように、調圧水槽１４の水位は、下降と上昇を繰り返す振動現象を呈し、やがて振動は減衰して最終的には排出水域１６の水位Ｈ２と等しくなる。この水位差が、第１と第２の水位計測手段２０，２２の計測値から水位差演算手段２４で演算され、この水位差を時間経過とともに記録手段２８で記録した一例が、図２の偏差水位変動曲線である。図２でＳ０、Ｓ１、Ｓ２、Ｓ３、Ｓ４，Ｓ５は、排出水域１６の水位を基準とする水位差を示す。
【００１７】
この偏差水位変動の振動現象を生ずる排水管１８内の水の流体運動方程式は、公知であり、（４）式で示される。
【数１０】
そして、この（４）式の解として（５）式が得られる。
【数１１】
であり、Ｓは排出水域の水位を基準とした調圧水槽水位、ｇは重力加速度、Ｌは排水管長さ、ξは排水管の損失係数、βは面積比（排水管断面積／調圧水槽底面積）、ｔは時間、Ｃは定数である。
なお、（５）式で、プラスマイナス符号（±）およびマイナスプラス符号の上側の符号は排出水域１６から調圧水槽１４への流入を示し、下側の符号は調圧水槽１４から排出水域１６への流出を示す。また、排出水域１６は、調圧水槽１４からの流出に対して、水位がほぼ変動しないとみなし得る程度に十分に広いものとする。具体的には、排出水域１６としての河川の幅は、調圧水槽１４の幅の約５倍程度以上あれば良い。
【００１８】
そして、ポンプ１０が定常的に動作している場合は、水位差Ｓと流量Ｑと排水管１８の断面積Ａとその流速Ｖと、調圧水槽の底面積Ａ０は、（６）式の関係にある。
【数１２】
そこで、ポンプ１０を急激に停止した際の流量Ｑは０となるのでｔ＝０で、（７）式が成立する。
【数１３】
これを整理すれば、（８）式となる。
【数１４】
【００１９】
さらに、（５）式と（８）式を整理すると、（９）式となる。
【数１５】
但し、ｎは２以上である。
【００２０】
この（９）式に記録手段２８で記録された図２の偏差水位変動曲線から求めた極大値と極小値Ｓ１、Ｓ２、Ｓ３、Ｓ４、Ｓ５を代入して、それぞれのｍを算出して、ｍの平均値ｍ０を算出する。
【００２１】
そして、算出した平均値のｍ０を下記の（１０）式に代入してξを求め、この求めたξを（４）式に代入すると、図３のごとき理論変動曲線が得られる。この図３で、ｍの値が大きくなると理論変動曲線の偏差水位が小さくなり、ｍの値が小さくなると理論変動曲線の偏差水位が大きくなる。そこで、記録手段２８で記録された偏差水位変動曲線に、理論変動曲線が一致するようにｍの値が決定される。
【数１６】
【００２２】
なお、上記説明では偏差水位変動曲線から求めた極大値と極小値Ｓ１、Ｓ２、Ｓ３…から理論変動曲線のｍを算出し、最終的には偏差水位変動曲線に理論変動曲線が一致するｍを求めているが、偏差水位変動曲線に一致する理論変動曲線を探し、これからｍを求めても良い。
【００２３】
このようにして、予め排水管１８の損失係数ξを求め、これと調圧水槽１４と排出水域１６の水位差Ｓ０＝（Ｈ１−Ｈ２）から求めたポンプ１０の吐出流量Ｑと、流量を他の測定手段で測定した実測流量を比較したものが図４の表である。初期水位差Ｓ０を０．３０７ｍと０．２１４ｍと０．１３６ｍとそれぞれに相違させて測定を行った。この結果、本発明のポンプ流量測定方法にて充分に正確な流量の測定が可能であることが判明した。
【００２４】
次に、排水管１８の損失係数ξを上述のごとくポンプ１０を急激に停止させることによって測定算出するのとは、別の方法につき説明する。損失係数ξを測定算出するには、調整水槽１４の水位が下降および上昇する振動現象を生じれば良い。かかる観点から構成されたものが、図５に示す本発明の第２実施例である。図５は、本発明のポンプ流量測定装置の第２実施例の構造図である。図５において、図１と同じまたは均等な部材に同じ符号を付けて重複する説明を省略する。
【００２５】
図５の構造にあっては、排水管１８に第１の開閉弁３２が介装され、吐出配管１２に第２の開閉弁３４が介装される。そして、排水管１８の損失係数ξの測定算出のときには、第１の開閉弁３２を閉塞し、遅れてポンプ１０を停止すると同時に第２の開閉弁３４を閉塞してポンプ１０からの流入を停止し、調圧水槽１４と排出水域１６に所望の水位差を設定する。そして、第１の開閉弁３２を急激に全開とすることで、調圧水槽１４の水位に振動現象を生じさせる。もって、第１実施例と同様にして、排水管１８の損失係数ξの測定算出が可能である。
【００２６】
なお、上記実施例では、水位差演算手段２４と演算手段２６と記録手段２８と損失係数演算手段３０がそれぞれ異なるブロックで示されるが、これらを演算手段２６としてのコンピュータにより実行しても良いことは勿論である。また、損失係数ξは、予め測定算出して演算手段２６にデータとして記録されてあれば良く、ポンプ１０の設置の際に測定できれば良く、測定後は記録手段２８と損失係数演算手段３０が取り外されても良い。
【００２７】
【発明の効果】
以上説明したところから明らかなように、本発明のポンプ流量測定方法およびポンプ流量測定装置は、以下のごとき格別な作用効果を奏する。
【００２８】
請求項１記載のポンプ流量測定方法にあっては、ポンプからの流入を停止して調圧水槽の水位と排出水域の水位との偏差水位変動と排水管内の流体の流体運動方程式から予め排水管の損失係数ξを算出し、予め測定された排水管の損失係数ξとその断面積および調圧水槽と排出水域との水位差とからポンプの吐出流量が測定でき、その水位差の測定は簡単にでき、流量測定が極めて容易である。そして、ポンプの吐出流量を正確に測定するための吐出配管直管部を必要とせず、それだけ排水設備などの設置スペースが狭くて良い。また、必要により排水管の損失係数ξを測定演算しなおせば、常に正確な流量が得られる。
【００２９】
請求項２記載のポンプ流量測定方法にあっては、ポンプの吐出を急激に停止して、調圧水槽の水位を下降および上昇させる振動現象を生じさせることで、簡単に排水管の損失係数ξの測定算出ができる。
【００３０】
請求項３記載のポンプ流量測定方法にあっても、ポンプからの流入を停止するとともに排水管を遮断して調圧水槽の水位と排出水域の水位とに水位差を設け、排水管を急激に連通させて、調圧水槽の水位を下降および上昇させる振動現象を生じさせることで、簡単に排水管の損失係数ξの測定算出ができる。
【００３１】
請求項４記載のポンプ流量測定装置においては、調圧水槽に設けた第１の水位計測手段と排出水域に設けた第２の水位計測手段とから得られる計測値が与えられて水位差を算出する水位差演算手段と、ポンプの吐出を急激に停止した際に生ずる水位差に応じた偏差水位変動曲線を記録する記録手段を設けたので、この偏差水位変動曲線を用いて排水管の損失係数ξを簡単に算出することができ、この損失係数ξを用いて容易にポンプの吐出流量が算出され得る。
【００３２】
請求項５記載のポンプ流量測定装置にあっては、調圧水槽に設けた第１の水位計測手段と排出水域に設けた第２の水位計測手段とから得られる計測値が与えられて水位差を算出する水位差演算手段と、ポンプからの流入を停止するとともに排水管を遮断して調圧水槽の水位と排出水域の水位とに水位差を設け、排水管を急激に連通させた際に生ずる水位差に応じた偏差水位変動曲線を記録する記録手段を設けたので、この偏差水位変動曲線を用いて排水管の損失係数ξを簡単に算出することができ、この損失係数ξを用いて容易にポンプの吐出流量が算出され得る。
【図面の簡単な説明】
【図１】 本発明のポンプ流量測定装置の第１の実施例の構造図であり、（ａ）はポンプの定常運転時の水位を示し、（ｂ）はポンプの運転が急激に停止されて調圧水槽の水位が排出水域の水位より低下した状態を示し、（ｃ）は再び調圧水槽の水位が排出水域の水位より上昇した状態を示し、（ｄ）は再び調圧水槽の水位が排出水域の水位より低下した状態を示す。
【図２】 オシロスコープに記録された調圧水槽の水位と排出水域の水位の偏差水位変動曲線を示す図である。
【図３】 偏差水位の理論変動曲線を示す図である。
【図４】 本発明によるポンプの吐出流量の算出値と実測値とを示す表である。
【図５】 本発明のポンプ流量測定装置の第２実施例の構造図である。
【符号の説明】
１０ ポンプ
１２ 吐出配管
１４ 調圧水槽
１６ 排出水域
１８ 排水管
２０ 第１の水位測定手段
２２ 第２の水位測定手段
２４ 水位差演算手段
２６ 演算手段
２８ 記録手段
３０ 損失係数演算手段
３２ 第１の開閉弁
３４ 第２の開閉弁[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pump flow rate measuring method and a pump flow rate measuring device for measuring a discharge flow rate of a pump installed in a drainage facility provided with a pressure regulating water tank.
[0002]
[Prior art]
In a drainage facility such as a drainage station, a pressure-regulating water tank is provided between the pump and the discharge water area in order to absorb pressure fluctuation due to a rapid change in the discharge flow rate of the pump. Therefore, the discharge pipe of the pump is connected to the pressure regulating water tank, and this pressure regulating water tank is communicated with the discharge water area through the drain pipe. By providing this pressure regulating water tank, the discharge of the pump stops abruptly, or when the pump is started, the pressure fluctuation in the discharge pipe is suppressed, and when the pump discharge stops suddenly, The fluid continues to flow into the discharge water area through the drainage pipe according to the law of inertia, and suppresses the water hammer phenomenon of the discharge pipe. It also suppresses sudden fluctuations in the water level of the discharge area.
[0003]
By the way, the measurement of the discharge flow rate of the pump installed in the drainage equipment includes a method in which the flow velocity in the discharge pipe is measured by an ultrasonic flow meter. In addition, the pump flow rate-whole field curve is measured at the factory before shipping the pump in advance, and the pump discharge flow rate is measured from the intersection of this and the resistance curve of the entire piping obtained from the actual installation conditions. There is also.
[0004]
[Problems to be solved by the invention]
In the measurement of the discharge flow rate of the pump using the ultrasonic flow meter described above, it is necessary to sufficiently increase the length of the discharge pipe straight pipe portion interposed between the discharge port of the pump and the pressure regulating water tank. This is because the flow in the straight portion of the discharge pipe must be stable in order to accurately measure the flow rate. However, it is practically difficult to provide a discharge pipe straight pipe portion having a sufficient length due to restrictions such as the installation space of the drainage facility.
[0005]
Also, in the method of calculating the discharge flow rate using the flow rate-full field curve, the actual flow rate-full field curve changes due to aging of the pump impeller, and the piping friction loss and valve loss also change. As a result, the resistance curve of the entire piping also changes, and the calculation accuracy of the discharge flow rate tends to deteriorate year by year.
[0006]
The present invention has been made in view of the problems of the prior art as described above, and a pump flow rate measuring method and a pump flow rate measuring device capable of easily and accurately calculating the pump discharge flow rate from the water level difference between the pressure regulating water tank and the discharge water area. The purpose is to provide.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the pump flow rate measuring method of the present invention is such that a pump discharge pipe is connected to a pressure regulating water tank, the pressure regulating water tank is connected to a drainage water area by a drain pipe, and the drain pipe is connected to the drainage pipe. A drainage facility that is always below the surface of the body of water and is kept full of water, and stops the water level H1 of the pressure-regulating water tank, the water level H2 of the discharge water area, and the inflow from the pump during operation of the pump The drainage pipe loss coefficient ξ calculated in advance from the deviation level fluctuation between the water level of the pressure regulating water tank and the water level of the discharge water area and the fluid motion equation of the fluid in the drainage pipe, and the disconnection of the drainage pipe. From area A,
[ Equation 4 ]
To calculate the discharge flow rate Q of the pump.
[0008]
Then, the deviation water level fluctuations in the water level of the pressure water tank water level and the discharge waters generated when had abruptly stopping the discharge of the pump, from said fluid motion equation of the fluid in said drain pipe in that case The loss coefficient ξ may be calculated in advance.
[0009]
Further, the pressure regulation that occurs when the drainage pipe is abruptly communicated by stopping the inflow from the pump and shutting off the drainage pipe to provide a water level difference between the water level of the pressure regulating water tank and the water level of the discharge water area. The loss coefficient ξ can be calculated in advance from the deviation level fluctuation between the water level of the water tank and the water level of the discharge water area and the fluid motion equation of the fluid in the drain pipe at that time.
[0010]
In the pump flow measuring device of the present invention, the discharge pipe of the pump is connected to the pressure regulating water tank, the pressure regulating water tank is connected to the drainage water area through the drain pipe , and the drain pipe is below the surface of the drain water area. And a second water level measuring means for providing a first water level measuring means for measuring the water level H1 in the pressure regulating water tank and measuring the water level H2 in the drained water area. Provided with measurement values of the first and second measuring means and calculating a water level difference calculating means, and a recording means for receiving a signal corresponding to the water level difference. , Recording a deviation water level fluctuation curve between the water level of the pressure regulating water tank and the water level of the discharge water area generated when the discharge of the pump is suddenly stopped, and the recorded deviation water level fluctuation curve and the fluid in the drain pipe Calculate loss factor from fluid equation of motion Calculating a pre-loss coefficient ξ in stages, set this loss coefficient ξ to the arithmetic unit gives a measured value of said first and second measuring means to the calculating means, the water level H1 and H2 in this computing means the a loss factor of drainage pipes ξ which is set in advance calculated, the cross-sectional area a of the drain pipe, Equation 5] from
Thus, the discharge flow rate Q of the pump is calculated.
[0011]
In addition, the discharge pipe of the pump is connected to a pressure regulating water tank, the pressure regulating water tank communicates with the drainage water area through a drain pipe, and the drain pipe is below the surface of the drain water area so that the water is always kept full. A first water level measuring means for measuring the water level H1 in the pressure-regulating water tank; and a second water level measuring means for measuring the water level H2 in the drained water area . The water level difference calculating means for calculating the water level difference given the measurement value of the measuring means, and the recording means for giving a signal corresponding to the water level difference are provided, and the recording means stops the inflow from the pump. In addition, the drainage pipe is shut off to provide a water level difference between the water level of the pressure regulating water tank and the water level of the discharge water area, and the water level of the pressure regulating water tank and the water level of the discharge water area generated when the drain pipe is communicated rapidly Record the deviation water level fluctuation curve with Deviation calculated previously loss coefficient ξ water level fluctuation curve with a fluid motion equation than the loss coefficient calculating means for fluid of the drainage tube, set this loss coefficient ξ to the computing means, said first and second measuring means From the water levels H1 and H2, the loss coefficient ξ of the drain pipe set in advance and the cross-sectional area A of the drain pipe.
[Formula 6]
The may be configured to calculate a discharge flow rate Q of the pump.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a structural diagram of a first embodiment of a pump flow rate measuring apparatus according to the present invention, where (a) shows the water level during steady operation of the pump, and (b) shows that the operation of the pump is suddenly stopped. (C) shows the state where the water level of the pressure regulating tank is raised again from the water level of the discharge water area, and (d) shows the state where the water level of the pressure regulating tank is again Shows a state where the water level is lower than the discharge water area. FIG. 2 is a diagram showing a deviation water level fluctuation curve of the water level of the pressure regulating water tank and the water level of the discharge water area recorded in the oscilloscope. FIG. 3 is a diagram showing a theoretical fluctuation curve of the deviation water level. FIG. 4 is a table showing calculated values and measured values of the discharge flow rate of the pump according to the present invention.
[0013]
First, in FIG. 1, in the first embodiment of the present invention, a discharge pipe 12 of a pump 10 is connected to a pressure regulating water tank 14, and the pressure regulating water tank 14 is communicated with a discharge water area 16 such as a river and a drain pipe 18. . The drain pipe 18 is disposed below the water surface of the discharge water area 16 and is always kept in a full state. Further, the pressure regulating water tank 14 is provided with a first water level measuring means 20 for measuring the water level, and the discharged water area 16 is provided with a second water level measuring means 22 for measuring the water level. And the measured value of the 1st and 2nd water level measuring means 20 and 22 is given to the water level difference calculating means 24, and a water level difference is calculated. A signal corresponding to the water level difference is given to the calculating means 26 and the recording means 28 such as an oscilloscope. As an example, the recording means 28 records a deviation water level fluctuation curve indicating the passage of time and the fluctuation of the water level difference as shown in FIG. Then, this deviation water level fluctuation curve is given to the loss coefficient calculating means 30, the loss coefficient ξ is calculated as described later, and this loss coefficient ξ is set in the calculating means 26. In the calculation means 26, the number of losses ξ that is calculated and set in advance, the water level difference (H 1 −H 2) between the water levels of the pressure-regulating water tank 14 and the discharge water area 16 in the steady operation state of the pump 10, and the cross-sectional area of the drain pipe 18. The flow rate Q of the pump 10 is calculated and output from A as described below.
[0014]
By the way, in the steady operation state of the pump 10, the water level H1 of the pressure regulating water tank 14 is higher than the water level H2 of the discharge water area 16, and the difference between the water levels (H1-H2) and the square of the average flow velocity V in the drain pipe 18. Is proportional. The product of the cross-sectional area A and the average flow velocity V of the drain pipe 18 is the flow rate Q discharged from the pump 10. Therefore, if the loss coefficient ξ as a proportional count is calculated in advance, the flow rate Q discharged from the pump 10 can be calculated from the water level difference (H1−H2) between the water levels in the pressure regulating water tank 14 and the discharge water area 16. Therefore, equations (2) and (3) are established.
[ Expression 7 ]
Where ξ is a loss factor and V is an average flow velocity in the drain pipe.
[ Equation 8 ]
However, Q is the discharge flow rate of the pump, and A is the cross-sectional area of the discharge pipe.
Then, the above-described equation (1) is obtained from these equations (2) and (3).
[ Equation 9 ]
Here, the cross-sectional area A of the drain pipe 18 can be easily measured or calculated, and the water levels H1 and H2 can also be easily measured by the first and second water level measuring means 20 and 22. The loss coefficient ξ may be measured and calculated only once in advance, and does not need to be calculated repeatedly every time the flow rate is measured.
It is known that the flow rate is obtained from the loss coefficient ξ of the drain pipe 18 and its cross-sectional area A and the water level difference, and Japanese Patent Laid-Open No. 05-19864 (Patent Document 1) and Japanese Patent Laid-Open No. 10-185635 ( Patent Document 2) and the like.
[Patent Document 1]
JP 05-19844 A
[Patent Document 2]
Japanese Patent Laid-Open No. 10-185635
Next, a method for calculating the loss coefficient ξ will be described below. In the steady operation of the pump 10, the operation of the pump 10 is abruptly stopped and the discharge flow rate Q is made zero with the pressure regulating water tank 14 at the water level H1 and the discharge water area 16 at the water level H2. Then, the inflow from the pump 10 stops , and water continues to flow into the discharge water area 16 due to the high water level difference on the pressure regulating water tank 14 side and the inertia of the water flowing in the drain pipe 18, and the water level of the pressure regulating water tank 14 decreases. Subsequently, as shown in (b), the water level of the pressure regulating water tank 14 fluctuates to H3 lower than the water level H2 of the discharge water area 16. Then, due to the high water level difference on the discharge water area 16 side, the water flows back in the drain pipe 18 and the water level in the pressure regulating water tank 14 rises and changes to H4 higher than the water level H2 in the discharge water area 16 as shown in (c). To do. Furthermore, this time, the water level on the pressure adjusting water tank 14 side is high, so that water flows in the drain pipe 18 to the discharge water area 16, and the water level in the pressure adjusting water tank 14 is higher than the water level in the discharge water area 16 as shown in (d). Vary to low H5. Therefore, the deviation water level fluctuation occurs.
[0016]
As described above, the water level of the pressure regulating water tank 14 exhibits a vibration phenomenon that repeatedly descends and rises, and eventually the vibration is attenuated and finally becomes equal to the water level H2 of the discharge water area 16. An example in which this water level difference is calculated by the water level difference calculating means 24 from the measured values of the first and second water level measuring means 20 and 22 and this water level difference is recorded by the recording means 28 over time is shown in the deviation of FIG. It is a water level fluctuation curve. In FIG. 2, S 0, S 1, S 2, S 3, S 4, and S 5 indicate water level differences based on the water level of the discharge water area 16.
[0017]
The fluid motion equation of water in the drain pipe 18 that causes the oscillation phenomenon of the deviation water level fluctuation is known and is expressed by the following equation (4).
[ Expression 10 ]
As a solution of the equation (4), the equation (5) is obtained.
[ Expression 11 ]
Where S is the regulated water tank level based on the level of the discharge water area, g is the gravitational acceleration, L is the drain pipe length, ξ is the loss factor of the drain pipe, β is the area ratio (drain pipe cross-sectional area / pressure tank Bottom area), t is time, and C is a constant.
In the equation (5), the plus / minus sign (±) and the sign above the minus / plus sign indicate the inflow from the discharge water area 16 to the pressure regulating water tank 14, and the lower sign indicates the discharge water area 16 from the pressure regulating water tank 14. Indicates an outflow to. Further, the discharge water area 16 is sufficiently wide so that the water level can be regarded as almost unchanged with respect to the outflow from the regulated water tank 14. Specifically, the width of the river as the discharge water area 16 may be about 5 times or more than the width of the pressure regulating water tank 14.
[0018]
When the pump 10 is operating steadily, the water level difference S, the flow rate Q, the cross-sectional area A of the drain pipe 18 and its flow velocity V, and the bottom area A0 of the pressure regulating water tank are expressed by the relationship of equation (6). It is in.
[ Expression 12 ]
Therefore, since the flow rate Q when the pump 10 is suddenly stopped becomes 0, t = 0 and the equation (7) is established.
[ Formula 13 ]
If this is arranged, equation (8) is obtained.
[ Expression 14 ]
[0019]
Furthermore, when formulas (5) and (8) are arranged, formula (9) is obtained.
[ Expression 15 ]
However, n is 2 or more.
[0020]
Substituting the maximum value and the minimum values S1, S2, S3, S4, and S5 obtained from the deviation water level fluctuation curve of FIG. 2 recorded by the recording means 28 into the equation (9), each m is calculated, An average value m0 of m is calculated.
[0021]
Then, by substituting the calculated average value m0 into the following equation (10) to obtain ξ, and substituting the obtained ξ into equation (4), a theoretical fluctuation curve as shown in FIG. 3 is obtained. In FIG. 3, when the value of m increases, the deviation level of the theoretical fluctuation curve decreases, and when the value of m decreases, the deviation level of the theoretical fluctuation curve increases. Therefore, the value of m is determined so that the theoretical fluctuation curve matches the deviation water level fluctuation curve recorded by the recording means 28.
[ Expression 16 ]
[0022]
In the above description, m of the theoretical fluctuation curve is calculated from the maximum value and the minimum values S1, S2, S3... Obtained from the deviation water level fluctuation curve, and finally m is calculated so that the theoretical fluctuation curve matches the deviation water level fluctuation curve. However, m may be obtained from a theoretical fluctuation curve that matches the deviation water level fluctuation curve.
[0023]
In this way, the loss coefficient ξ of the drain pipe 18 is obtained in advance, and the discharge flow rate Q and the flow rate of the pump 10 obtained from this and the water level difference S0 = (H1−H2) between the pressure regulating water tank 14 and the discharge water area 16 FIG. 4 is a table comparing actual flow rates measured by the measuring means. The initial water level difference S0 was set to 0.307 m, 0.214 m, and 0.136 m, respectively. As a result, it has been found that a sufficiently accurate flow rate can be measured by the pump flow rate measuring method of the present invention.
[0024]
Next, another method for calculating and calculating the loss coefficient ξ of the drain pipe 18 by abruptly stopping the pump 10 as described above will be described. In order to measure and calculate the loss factor ξ, a vibration phenomenon in which the water level of the adjustment water tank 14 falls and rises may be generated. The second embodiment of the present invention shown in FIG. 5 is constructed from this viewpoint. FIG. 5 is a structural diagram of a second embodiment of the pump flow rate measuring apparatus of the present invention. In FIG. 5, the same or equivalent members as in FIG.
[0025]
In the structure of FIG. 5, a first on-off valve 32 is interposed in the drain pipe 18, and a second on-off valve 34 is interposed in the discharge pipe 12. When the loss coefficient ξ of the drain pipe 18 is measured and calculated, the first on-off valve 32 is closed, and the pump 10 is stopped with a delay. At the same time, the second on-off valve 34 is closed to stop the inflow from the pump 10. Then , a desired water level difference is set in the pressure regulating water tank 14 and the discharge water area 16. Then, the first on-off valve 32 is suddenly fully opened to cause a vibration phenomenon in the water level of the pressure regulating water tank 14. Therefore, it is possible to measure and calculate the loss coefficient ξ of the drain pipe 18 as in the first embodiment.
[0026]
In the above embodiment, the water level difference calculating means 24, the calculating means 26, the recording means 28, and the loss coefficient calculating means 30 are shown as different blocks, but these may be executed by a computer as the calculating means 26. Of course. Further, the loss coefficient ξ only needs to be measured and calculated in advance and recorded as data in the calculation means 26, and may be measured when the pump 10 is installed. After the measurement, the recording means 28 and the loss coefficient calculation means 30 are taken. May be removed .
[0027]
【The invention's effect】
As is apparent from the above description, the pump flow rate measuring method and the pump flow rate measuring apparatus of the present invention have the following special effects.
[0028]
In the pump flow rate measuring method according to claim 1, the inflow from the pump is stopped, and the drainage pipe is preliminarily determined from the deviation level fluctuation between the water level of the pressure regulating tank and the water level of the discharge water area and the fluid motion equation of the fluid in the drainage pipe. The loss coefficient ξ of the pump can be calculated, and the discharge flow rate of the pump can be measured from the loss factor ξ of the drainage pipe measured in advance and its cross-sectional area and the water level difference between the pressure-regulating tank and the discharge water area. The flow rate measurement is very easy. And the discharge piping straight pipe part for measuring the discharge flow rate of a pump correctly is not required, and installation space, such as a drainage facility, may be so narrow. Further, if the loss coefficient ξ of the drain pipe is measured and calculated again if necessary, an accurate flow rate can always be obtained.
[0029]
In the pump flow rate measuring method according to claim 2, the loss coefficient ξ of the drain pipe can be easily obtained by suddenly stopping the discharge of the pump and causing a vibration phenomenon of lowering and raising the water level of the pressure regulating water tank. Can be measured and calculated.
[0030]
Even in the pump flow rate measuring method according to claim 3, the inflow from the pump is stopped and the drainage pipe is shut off to provide a water level difference between the water level of the pressure regulating water tank and the water level of the discharge water area. By communicating and generating a vibration phenomenon that lowers and raises the water level of the pressure regulating water tank, it is possible to easily measure and calculate the loss coefficient ξ of the drain pipe.
[0031]
5. The pump flow rate measuring apparatus according to claim 4, wherein a measured value obtained from a first water level measuring means provided in the pressure regulating water tank and a second water level measuring means provided in the discharge water area is given to calculate a water level difference. Water level difference calculation means and recording means to record the deviation water level fluctuation curve according to the water level difference that occurs when the pump discharge is suddenly stopped, so using this deviation water level fluctuation curve, the loss factor of the drain pipe ξ can be easily calculated, and the discharge flow rate of the pump can be easily calculated using the loss coefficient ξ .
[0032]
In the pump flow rate measuring device according to claim 5, the measured value obtained from the first water level measuring means provided in the pressure regulating water tank and the second water level measuring means provided in the discharge water area is given, and the water level difference When the water level difference calculation means that calculates the water level and the water level difference between the water level in the regulated water tank and the water level in the discharge water area are stopped by stopping the inflow from the pump and shutting off the drain pipe, Since the recording means for recording the deviation water level fluctuation curve according to the generated water level difference is provided, it is possible to easily calculate the loss coefficient ξ of the drain pipe using this deviation water level fluctuation curve, and using this loss coefficient ξ The discharge flow rate of the pump can be easily calculated .
[Brief description of the drawings]
FIG. 1 is a structural diagram of a first embodiment of a pump flow rate measuring apparatus according to the present invention, where (a) shows the water level during steady operation of the pump, and (b) shows that the operation of the pump is suddenly stopped. (C) shows the state where the water level of the pressure regulating tank is raised again from the water level of the discharge water area, and (d) shows the state where the water level of the pressure regulating tank is again Shows a state where the water level is lower than the discharge water area.
FIG. 2 is a diagram showing a deviation water level fluctuation curve between a water level in a pressure regulating water tank and a water level in a discharge water area recorded in an oscilloscope.
FIG. 3 is a diagram showing a theoretical fluctuation curve of a deviation water level.
FIG. 4 is a table showing calculated values and measured values of the discharge flow rate of the pump according to the present invention.
FIG. 5 is a structural diagram of a second embodiment of the pump flow rate measuring apparatus according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Pump 12 Discharge piping 14 Pressure regulation tank 16 Drainage area 18 Drain pipe 20 1st water level measurement means 22 2nd water level measurement means 24 Water level difference calculation means 26 Calculation means 28 Recording means 30 Loss coefficient calculation means 32 1st opening / closing Valve 34 Second on-off valve
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001220188A JP4836103B2 (en) | 2001-07-19 | 2001-07-19 | Pump flow rate measuring method and pump flow rate measuring device |
Applications Claiming Priority (1)
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| JPH02102386A (en) * | 1988-10-11 | 1990-04-13 | Meidensha Corp | Flow rate measuring device |
| JP2794992B2 (en) * | 1991-07-10 | 1998-09-10 | 富士電機株式会社 | Liquid level control method and liquid level control device |
| JPH10185635A (en) * | 1996-12-26 | 1998-07-14 | Nec Eng Ltd | Flow rate measuring system |
| JP3046558B2 (en) * | 1997-03-25 | 2000-05-29 | 和夫 灘岡 | Oscillating flow generator |
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