JPS6329210Y2 - - Google Patents
Info
- Publication number
- JPS6329210Y2 JPS6329210Y2 JP1986073014U JP7301486U JPS6329210Y2 JP S6329210 Y2 JPS6329210 Y2 JP S6329210Y2 JP 1986073014 U JP1986073014 U JP 1986073014U JP 7301486 U JP7301486 U JP 7301486U JP S6329210 Y2 JPS6329210 Y2 JP S6329210Y2
- Authority
- JP
- Japan
- Prior art keywords
- flow rate
- control valve
- flow
- valve lift
- valve
- 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
Links
- 239000012530 fluid Substances 0.000 claims description 14
- 238000001514 detection method Methods 0.000 claims description 8
- 230000001052 transient effect Effects 0.000 claims description 5
- 238000011144 upstream manufacturing Methods 0.000 claims description 5
- 230000000694 effects Effects 0.000 description 7
- 239000007788 liquid Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 230000000116 mitigating effect Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
Landscapes
- Measuring Volume Flow (AREA)
Description
〔産業上の利用分野〕
本考案は配管流路内を流れる流体の流量を検出
する装置に関するものである。
〔従来の技術〕
配管流路内を流れる流体の流量を求める場合に
は、通常オリフイスを用いている。
すなわち、第１図に示すように、配管１内にオ
リフイス２を介装し、オリフイス２の近傍上・下
流側の流体圧力を導圧管３、４で差圧計５に導
き、同差圧計５の出力をあらかじめ求められてい
るレイノルズ数等の関係により流量に変換し変換
器７で出力するものである。
〔考案が解決しようとする問題点〕
このようにしてなる装置で、たとえば液体窒素
のように極低温蒸発性液流体の流量を測定する場
合には、不具合となることもある。
配管１に介装してある流量調節弁６が全閉に近
い状態で、流れがほとんど無い時不具合が生じ
る。なんとなれば、配管１や導圧管３，４には断
熱材が巻かれているものの、若干の熱の流入はま
ぬがれない。従つて、流れがほとんど無いような
場合には導圧管３，４などからの入熱によつて、
オリフイス２の周辺の液体が気化してしまい気泡
が局部的に発生することになり、差圧計５に伝達
される差圧が異常に変動してしまう場合も多い。
また、オリフイス２などの絞り機構を用いた流
量測定では流量は差圧の平方根に比例するが、オ
リフイス２の開口面積は一定であるために差圧を
特に大きくするなどということができず、小さい
ままの差圧を用いることになつてしまう。気泡の
発生による圧力の異常変動は極めて大きい検出誤
差をもたらすことになり、前述の不具合を一層助
長し、流量測定の安定性・信頼性を阻害すること
になる。
〔問題点を解決するための手段〕
本考案はこれらの欠点を排除するものであつ
て、弁開度が弁リフトの関数として全閉から全開
まで連続的に変化して配管流路内を流れる流体の
流量を制御する流量調節弁と、同流量調節弁の弁
リフトを制御する弁リフト制御器と、同弁リフト
制御器の出力を分岐して上記流量調節弁の過渡応
答を補償する補償回路と、同補償回路で補償され
た弁リフトに基づき上記流量調節弁の個有の流量
係数Cvを発生するCv関数発生器と、上記流量調
節弁の近傍上・下流側の圧力の差圧を測定する偏
差器と、同偏差器で求められた値の絶対値を開平
する開平演算器と、同開平演算器と上記Cv関数
発生器の出力および定数を乗じる乗算器とからな
ることを特徴とし、その目的とするところは、極
低温蒸発性液流体などの流れがほとんど無いよう
な状態であつても、正しくその流量を求めことが
でき、かつ補償回路の付加によつて流量制御への
利用における動特性を改善しうる流量検出装置を
提供するものである。
〔作用および効果〕
すなわち、本考案に係る流量検出装置はオリフ
イスの使用を廃し絞り機構としてその管路に使用
されている流量調節弁を用いており、流量調節弁
を流れる流体の流量Ｑ（m3／ｈ）は流量調節弁の
流量係数をCv、流量調節弁の上流側と下流側と
の差圧を△Ｐ（Kg／cm2）、流体の比重をGfとすれ
ば
[Industrial Application Field] The present invention relates to a device for detecting the flow rate of fluid flowing in a piping flow path. [Prior Art] When determining the flow rate of fluid flowing in a piping channel, an orifice is usually used. That is, as shown in FIG. 1, an orifice 2 is installed in a pipe 1, and fluid pressure near the orifice 2 on the upstream and downstream sides is guided to a differential pressure gauge 5 through impulse pipes 3 and 4. The output is converted into a flow rate based on a predetermined relationship such as the Reynolds number, and the converter 7 outputs the converted flow rate. [Problems to be Solved by the Invention] When measuring the flow rate of a cryogenically evaporable liquid fluid such as liquid nitrogen using a device constructed in this manner, problems may occur. A problem occurs when the flow control valve 6 installed in the pipe 1 is close to fully closed and there is almost no flow. Although the piping 1 and the impulse pipes 3 and 4 are wrapped with heat insulating material, some amount of heat cannot be avoided. Therefore, when there is almost no flow, the heat input from the impulse pipes 3, 4, etc.
The liquid around the orifice 2 vaporizes and bubbles are generated locally, which often causes the differential pressure transmitted to the differential pressure gauge 5 to fluctuate abnormally. In addition, when measuring flow rate using a throttle mechanism such as orifice 2, the flow rate is proportional to the square root of the differential pressure, but since the opening area of orifice 2 is constant, it is not possible to make the differential pressure particularly large, and the flow rate is small. This results in the use of the same differential pressure. Abnormal fluctuations in pressure due to the generation of bubbles will result in extremely large detection errors, further aggravating the aforementioned problems and impairing the stability and reliability of flow measurement. [Means for Solving the Problems] The present invention eliminates these drawbacks, and the valve opening degree changes continuously from fully closed to fully open as a function of the valve lift, and the flow in the piping flow path is improved. A flow control valve that controls the flow rate of fluid, a valve lift controller that controls the valve lift of the flow control valve, and a compensation circuit that branches the output of the valve lift controller to compensate for the transient response of the flow control valve. , a Cv function generator that generates the unique flow coefficient Cv of the flow control valve based on the valve lift compensated by the same compensation circuit, and the pressure difference between the pressure on the upper and downstream sides near the flow control valve is measured. a square root calculator that squares the absolute value of the value obtained by the deviation device, and a multiplier that multiplies the square root calculator and the output of the Cv function generator and a constant, The purpose of this is to be able to accurately determine the flow rate even when there is almost no flow of cryogenic evaporative liquid fluid, and to make it possible to use it for flow control by adding a compensation circuit. The present invention provides a flow rate detection device that can improve dynamic characteristics. [Operations and Effects] That is, the flow rate detection device according to the present invention eliminates the use of an orifice and uses the flow rate control valve used in the conduit as a throttling mechanism, and the flow rate Q (m) of the fluid flowing through the flow rate control valve is 3 /h) is the flow rate coefficient of the flow rate control valve, Cv is the differential pressure between the upstream and downstream sides of the flow rate control valve, △P (Kg/cm 2 ), and the specific gravity of the fluid is Gf.
以下本考案を第２図に示す一実施例の装置につ
いて説明する。
１は流体を流す配管であつて流量制御のための
流量調節弁６が介装されており、その上・下流側
近傍に一対の導圧管８，１０を設ける。９および
１１は導圧管８，１０で導びかれる流体圧PUと
PLを測定する圧力変換器であつて、その出力は
偏差器１２に導入され差圧PU−PLが検出され
る。
１３は偏差器１２で検出される差圧PU−PLの
絶対値を開平する開平演算器であつて、後記する
乗算器１７にその値√｜−｜を出力するも
のである。
１４は流量調節弁６に、図示しない制御装置に
よつて決定される弁リフトを与える弁リフト制御
器であつて、信号変換器１９および弁操作器２０
を介して流量調節弁６が操作される。
補償回路１５は弁操作器２０が有する近似的な
１次おくれ特性の時定数を下限とし、少くとも50
％大なる時定数まで任意に設定し得る機能を備え
た補償回路であつて、上記弁リフト制御器１４の
出力を受けてCv関数発生器１６に送出するもの
である。
Cv関数発生器１６は弁リフト制御器１４で与
えられる流量調節弁６の弁リフトの信号に基づ
き、第３図に示すような弁リフトと固有の流量係
数Cvとの関数を記憶している。
１７は開平演算器１３の出力√｜−｜お
よび、Cv関数発生器１６の出力Cv値および定数
Ｋを乗ずる演算器であつて、流量Ｑが出力され
る。
さて、配管１内を流れる流体の流量Ｑは、別途
設けられた制御装置から弁リフト制御器１４に与
えられた信号により流量調節弁６の弁リフトが操
作されることによつて変化する。
この時、補償回路１５によつて所定時間補償さ
れた弁リフト信号はCv関数発生器１６に入力さ
れ、流量調節弁６とほぼ同期、またはそれ以上に
遅れた時間にそのCv値が出力され乗算器１７に
送出される。
一方、導圧管８、１０を介して圧力変換器９，
１１に伝達された流量調節弁６の上・下流側の流
体圧力PU・PLは、電気信号に変換され偏差器１
２に入力される。偏差器１２で得られた差圧PU
−PLは、開平演算器１３でその絶対値の開平が
行なわれ、乗算器１７に入力され、上記Cv値お
よび定数との乗算が行なわれて流量Ｑが出力され
る。
従来のオリフイスを用いる液流量の検出装置で
は、例えば流量調節弁６を急速に閉じるとオリフ
イスの上流側に「水撃現象」の影響が強く出て過
渡的に差圧が逆転する結果を生じる。オリフイス
開口面積は一定であるため、検出流量Ｑに換算す
ると第４図実線に示すごとく反対方向に20％程度
（約５秒間）増加するような、いわゆる「逆応答」
の誤差が出る。この誤差は、対象流体が極低温の
蒸発性の場合、導圧管がオリフイスを挾む至近な
位置関係に取付けられる「差圧検出の原理」によ
り、外部から導圧管を伝導する入熱がオリフイス
周辺に集中的なフラツシングを発生させることに
よつて一層顕著になり、更に低流量になれば脈動
的な誤差に発達する。
しかしながら、本実施例の装置は上記したよう
に本来流量制御を目的として設けられている流量
調節弁６自体を絞り機構として用いたものであ
り、流量調節弁６の開度が小となるにしたがい差
圧は大となり、流量は主として弁開度、すなわち
Cv値に依存して小となる。この物理現象の実態
に順応した装置であるので、上述のオリフイス使
用における流量検出の欠点をすべて解消できる特
長を有することができる。
更に、流量調節弁６の実際の弁リフトを用い
ず、弁リフト指令値を「弁の操作おくれ」の時定
数に相当して補償回路１５で補償するようにした
ので、弁リフトを検出する必要が無く、このよう
な検出器を取り付け難い場合に特に有効である。
なお、補償回路１５の時定数を弁の実際の操作
おくれ時定数より大きく設定すれば、検出流量が
実際よりも遅れるので、これをフイードバツク制
御系に用いると、過渡動作の初期には「進み効
果」を与え、後期には「遅れ効果」を与えるた
め、その流量制御系の動特性を改善する効果が得
られる。また、「水撃現象」の緩和にも有効とな
る。
以上述べたように、本考案の最大の特長は、弁
が可変オリフイスの作用を有するため、小流量に
おける差圧の検出が安定して行なわれ、配管流路
内に無駄な水頭損失や乱れを生じさせないため極
低温蒸発性液でも弁リフトの全可動範囲に亘つて
流量を精度良く検出でき、また前記補償回路の付
加によつて流量調節弁６が過渡動作の初期には
「進み効果」、後期には「遅れ効果」となるように
作用し、制御の安定性改善と配管路の「水撃現
象」の緩和に有効な効果を奏する点にある。
The present invention will now be described with reference to an embodiment of the apparatus shown in FIG. Reference numeral 1 denotes a pipe through which fluid flows, and a flow control valve 6 for controlling the flow rate is interposed therein, and a pair of impulse pipes 8 and 10 are provided near the upper and downstream sides thereof. 9 and 11 are fluid pressure PU guided by impulse pipes 8 and 10;
This is a pressure transducer for measuring PL, and its output is introduced into a deviation device 12 to detect the differential pressure PU-PL. Reference numeral 13 denotes a square root calculator that squares the absolute value of the differential pressure PU-PL detected by the deviation device 12, and outputs the value √|-| to a multiplier 17, which will be described later. Reference numeral 14 denotes a valve lift controller that gives the flow control valve 6 a valve lift determined by a control device (not shown), and includes a signal converter 19 and a valve operator 20.
The flow rate control valve 6 is operated via. The compensation circuit 15 has a lower limit of the time constant of the approximate first-order delay characteristic of the valve operator 20, and has a time constant of at least 50
This is a compensation circuit that has a function of arbitrarily setting a time constant up to a % larger time constant, and receives the output of the valve lift controller 14 and sends it to the Cv function generator 16. The Cv function generator 16 is based on the valve lift signal of the flow control valve 6 given by the valve lift controller 14, and stores a function between the valve lift and a unique flow coefficient Cv as shown in FIG. 17 is a calculator which multiplies the output √|-| of the square root calculator 13, the output Cv value of the Cv function generator 16, and a constant K, and outputs the flow rate Q. Now, the flow rate Q of the fluid flowing through the pipe 1 is changed by operating the valve lift of the flow rate control valve 6 based on a signal given to the valve lift controller 14 from a separately provided control device. At this time, the valve lift signal compensated for a predetermined time by the compensation circuit 15 is input to the Cv function generator 16, and its Cv value is output almost in synchronization with the flow rate control valve 6, or at a later time, and is multiplied. The signal is sent to the device 17. On the other hand, pressure transducers 9,
The fluid pressures PU and PL on the upstream and downstream sides of the flow control valve 6 that are transmitted to the deviator 11 are converted into electrical signals.
2 is input. Differential pressure PU obtained by deviation device 12
-PL is subjected to the square root of its absolute value in the square root calculator 13, and is inputted to the multiplier 17, where it is multiplied by the Cv value and a constant, and the flow rate Q is output. In a conventional liquid flow rate detection device using an orifice, for example, when the flow rate control valve 6 is rapidly closed, the effect of "water hammer" is strong on the upstream side of the orifice, resulting in a transient reversal of the differential pressure. Since the orifice opening area is constant, the detected flow rate Q increases by about 20% (for about 5 seconds) in the opposite direction as shown by the solid line in Figure 4, a so-called "reverse response".
There will be an error. This error is caused by the "principle of differential pressure detection" in which when the target fluid is extremely low-temperature and evaporative, the impulse tube is installed in close position between the orifice. This becomes more noticeable when intensive flushing occurs, and when the flow rate becomes even lower, it develops into a pulsating error. However, as described above, the device of this embodiment uses the flow rate control valve 6 itself, which is originally provided for the purpose of flow rate control, as a throttling mechanism, and as the opening degree of the flow rate control valve 6 becomes smaller, The differential pressure becomes large, and the flow rate mainly depends on the valve opening, i.e.
It becomes small depending on the Cv value. Since the device is adapted to the actual state of this physical phenomenon, it can have the feature of eliminating all the drawbacks of flow rate detection when using an orifice as described above. Furthermore, since the actual valve lift of the flow rate control valve 6 is not used, and the valve lift command value is compensated by the compensation circuit 15 by corresponding to the time constant of "valve operation delay", there is no need to detect the valve lift. This is particularly effective in cases where it is difficult to install such a detector. Note that if the time constant of the compensation circuit 15 is set larger than the actual operation lag time constant of the valve, the detected flow rate will lag behind the actual one, so if this is used in the feedback control system, there will be a "lead effect" at the beginning of the transient operation. '' and a ``delay effect'' in the latter stage, resulting in the effect of improving the dynamic characteristics of the flow rate control system. It is also effective in alleviating the "water hammer phenomenon." As mentioned above, the greatest feature of the present invention is that the valve has the function of a variable orifice, so differential pressure can be detected stably at small flow rates, eliminating unnecessary water head loss and turbulence in the piping flow path. Since this does not occur, the flow rate can be detected with high precision over the entire range of valve lift movement, even for extremely low-temperature evaporative liquids.Additionally, by adding the compensation circuit, the flow rate control valve 6 has an "advance effect" at the beginning of a transient operation. In the latter stage, it acts as a ``delay effect'' and is effective in improving control stability and mitigating the ``water hammer phenomenon'' in the pipeline.
第１図は従来の装置の説明図、第２図は本考案
の一実施例を示す装置の説明図、第３図は弁リフ
トとCv値の関係図、第４図は流量検出の特性を
示すグラフである。
１……配管、６……流量調節弁、１２……偏差
器、１３……開平演算器、１４……弁リフト制御
器、１５……補償回路、１６……Cv関数発生器、
１７……乗算器。
Fig. 1 is an explanatory diagram of a conventional device, Fig. 2 is an explanatory diagram of a device showing an embodiment of the present invention, Fig. 3 is a diagram showing the relationship between valve lift and Cv value, and Fig. 4 shows the characteristics of flow rate detection. This is a graph showing. 1...Piping, 6...Flow control valve, 12...Deviator, 13...Square root calculator, 14...Valve lift controller, 15...Compensation circuit, 16...Cv function generator,
17... Multiplier.
Claims (1)
に変化して配管流路内を流れる流体の流量を制御
する流量調節弁と、同流量調節弁の弁リフトを制
御する弁リフト制御器と、同弁リフト制御器の出
力を分岐して上記流量調節弁の過渡動作を補償す
る補償回路と、同補償回路で補償された弁リフト
に基づき上記流量調節弁の個有の流量係数Cvを
発生するCv関数発生器と、上記流量調節弁の近
傍上・下流側の圧力の差圧を測定する偏差器と、
同偏差器で求められた値の絶対値を開平する開平
演算器と、同開平演算器と上記Cv関数発生器の
出力および定数を乗じる乗算器とを具えてなるこ
とを特徴とする補償回路をそなえた流量検出装
置。 A flow control valve that continuously changes from fully closed to fully open as a function of valve lift to control the flow rate of fluid flowing in a piping flow path, and a valve lift controller that controls the valve lift of the flow control valve. a compensation circuit that branches the output of the valve lift controller to compensate for the transient operation of the flow control valve; and a Cv that generates a unique flow coefficient Cv of the flow control valve based on the valve lift compensated by the compensation circuit. a function generator; a deviation device that measures the differential pressure between upstream and downstream pressures near the flow rate control valve;
A compensation circuit comprising: a square root operator that squares the absolute value of the value obtained by the deviator; and a multiplier that multiplies the square root operator and the output of the Cv function generator and a constant. Equipped with a flow rate detection device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986073014U JPS6329210Y2 (en) | 1986-05-15 | 1986-05-15 |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1986073014U JPS6329210Y2 (en) | 1986-05-15 | 1986-05-15 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS621117U JPS621117U (en) | 1987-01-07 |
| JPS6329210Y2 true JPS6329210Y2 (en) | 1988-08-05 |
Family
ID=30611974
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1986073014U Expired JPS6329210Y2 (en) | 1986-05-15 | 1986-05-15 |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6329210Y2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2525909Y2 (en) * | 1988-09-09 | 1997-02-12 | 西部瓦斯株式会社 | Gas flow grasping device |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5522188A (en) * | 1978-07-27 | 1980-02-16 | Alsthom Atlantique | Device for measuring flow rate through duct |
-
1986
- 1986-05-15 JP JP1986073014U patent/JPS6329210Y2/ja not_active Expired
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5522188A (en) * | 1978-07-27 | 1980-02-16 | Alsthom Atlantique | Device for measuring flow rate through duct |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS621117U (en) | 1987-01-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR101930304B1 (en) | Flow meter | |
| EP0598720A1 (en) | Nonintrusive flow sensing system. | |
| US5002459A (en) | Surge control system | |
| JPH09155180A (en) | Liquid mixing device | |
| US20170153132A1 (en) | Measurement of flow through pipelines | |
| JPS6329210Y2 (en) | ||
| US5088322A (en) | Extended range flow meter | |
| JPS5973726A (en) | Flow rate detecting device | |
| JP2000283810A (en) | Differential pressure type flowmeter | |
| US4556018A (en) | Steam boiler | |
| JPS5992313A (en) | Flow rate detector | |
| GB2231669A (en) | Flowmeters | |
| JP2000249619A (en) | Gas leakage detecting method | |
| JPH04328435A (en) | Connecting pipe for differential pressure transmitter | |
| JPS6017692Y2 (en) | flow rate detector | |
| JP2787369B2 (en) | Automatic pressure control valve | |
| JPH08136305A (en) | Transmitter | |
| JPS61202120A (en) | Flow rate measuring apparatus | |
| JPH01227012A (en) | Method and apparatus for controlling flow rate | |
| JPS5965319A (en) | Control method for fluid pressure | |
| JPH04286931A (en) | Apparatus for detecting leakage of pipeline | |
| JPH03210608A (en) | Tank pressure controller | |
| JPS59212606A (en) | Controller for temperature of steam | |
| JPH10197315A (en) | Method for detecting level of tank | |
| JPH11324932A (en) | Water-distribution pressure control device |