JPH0574845B2 - - Google Patents
Info
- Publication number
- JPH0574845B2 JPH0574845B2 JP23577585A JP23577585A JPH0574845B2 JP H0574845 B2 JPH0574845 B2 JP H0574845B2 JP 23577585 A JP23577585 A JP 23577585A JP 23577585 A JP23577585 A JP 23577585A JP H0574845 B2 JPH0574845 B2 JP H0574845B2
- Authority
- JP
- Japan
- Prior art keywords
- level
- signal
- differential pressure
- high differential
- 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 - Lifetime
Links
- 239000012530 fluid Substances 0.000 claims description 26
- 230000001105 regulatory effect Effects 0.000 claims description 17
- 230000003628 erosive effect Effects 0.000 claims description 8
- 238000012544 monitoring process Methods 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000010248 power generation Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
Landscapes
- Control Of Fluid Pressure (AREA)
Description
〔発明の技術分野〕
本発明は、火力発電用ボイラあるいは化学プラ
ント等において入口圧力と出口圧力との差が大き
い条件のもとで用いられる高差圧調節弁の制御装
置に係り、特に、前記高差圧調節弁の微開制御動
作に起因する弁のエロージヨンを防止するための
改良に関する。
〔発明の技術的背景〕
例えば火力発電用ボイラあるいは化学プラント
等には、管または圧力容器等に装着され、流体ま
たは加圧体を制御するいわゆる調節弁が数多く用
いられている。第４図は、この調節弁のうちでも
特に入口圧力と出口圧力との差が大きい条件のも
とで、例えばタンク内流体のレベル制御を行なう
ために用いられる従来の高差圧調節弁と、この制
御装置の構成を示したものである。この第４図に
よれば、前記高差圧調節弁１は、流入配管２から
タンク３内に流入する流体４をポンプ５によつて
送出される系に装着され、前記タンク３内の流体
レベルが設定値以上となつたときに弁を開け、流
出配管６を通して前記流体４を排出させることに
より、前記タンク３内の流体レベルを、前記設定
値に保とうとするものである。尚、ここで示した
被制御系ではタンク３側の圧力が調節弁１の排出
側圧力に比して充分高く、上述した如く高差圧を
呈しているのは上述した通りである。これに対し
て制御装置は、レベル検出器７、減算器８、比例
積分調節器９から成り、前記レベル検出器７によ
り検出される前記流体４のレベル信号を、前記減
算器８に入力し、図示しないレベル設定器から入
力されるレベル設定値との間で減算を行なうこと
により偏差を求めるとともに、該偏差を前記比例
積分調節器９に入力し、当該偏差にもとづく前記
調節弁１の開閉制御を実行させることによつて上
述した流体４のレベル制御を行なつている。
〔背景技術の問題点〕
係る従来の高差圧調節弁の制御装置によれば、
前記レベル設定値を超える前記流体４のレベル全
域で、当該流体４のレベルに応じた前記調節弁１
の開閉制御を実行するものであつたため、状況に
よつては、前記調節弁１が微開状態に維持される
ことが生じていた。このような調節弁１の微開状
態のもとでは、上述した如く高差圧をもつて当該
調節弁１より排出される前記流体４の流速が極め
て高速となるため、当該調節弁１内のステム（弁
棒）およびシート部等にエロージヨン（浸食）が
生じ易く、当該調節弁１の寿命が極端に短かくな
るるとともに、当該エロージヨンに起因して発生
する弁リーク（漏れ）等のために、プラント効率
が低下するという問題点があつた。
〔発明の目的〕
本発明は上記問題点を除去するためになされた
ものであり、前記調節弁１の微開状態のもとでの
ステム、シート部等のエロージヨンを防止し、当
該調節弁１の長寿命化を図るとともに、プラント
効率の低下防止にも寄与することのできる高差圧
調節弁の制御装置を提供することを目的とする。
〔発明の概要〕
そこで本発明では、流体のレベルを検出するレ
ベル検出手段と、該流体レベルの検出値と予め設
定した閉レベル及び開レベル（閉レベル＜開レベ
ル）との関係を監視する監視手段と、高差圧調節
弁を強制閉鎖するための弁強制閉信号を発生する
第１の信号発生手段と、流体レベルの検出値が前
記閉レベル以上になつた時に前記弁強制閉信号か
ら当該検出値に切り替えて出力する第１の切り替
え手段と、該第１の切り替え手段の出力と設定レ
ベルとの偏差を求める演算手段と、前記高差圧調
節弁を規定開度にするための規定開度信号を発生
する第２の信号発生手段と、前記高差圧調節弁を
規定開度から全閉状態にするための全閉信号を発
生する第３の信号発生手段と、流体レベルの検出
値が前記閉レベルを超え、更に開レベルを超えて
から再び前記閉レベルとなるまでの間、前記全閉
信号を前記規定開度信号に切り替えて下限開度信
号として出力する第２の切り替え手段と、前記演
算手段からの偏差信号を前記第２の切り替え手段
からの下限開度信号により制限し、弁開度指令信
号を出力する比例積分調整手段とを具備し、高差
圧調節弁の最小開度（上記下限開度）をエロージ
ヨンが発生しない開度に制限するとともに、該高
差圧調節弁の最小開度以下の開閉は全速で行うよ
うにし、当該最小開度より小さい開度での流体レ
ベル制御を実質的に禁止することにより上記目的
を達成している。
なお、本発明において、上記レベル検出手段は
以下に述べる実施例のレベル検出器７に対応し、
監視手段はモニタスイツチ１５に対応する。
同様に、第１の信号発生手段、第２の信号発生
手段、第３の信号発生手段はそれぞれ信号発生器
１２，１４，１３に対応し、演算手段は減算器８
に対応する。
更に、第１の切り替え手段、第２の切り替え手
段はそれぞれ切替リレー１０，１１に対応し、比
例積分調整手段は比例積分調節器に対応する。
〔発明の実施例〕
以下本発明の実施例を添付図面にもとづいて詳
細に説明する。第１図は本発明の一実施例を示す
ものであり、第４図に示したものと同様に流入配
管２からタンク３内に流入する流体４を、ポンプ
５によつて送出する系に装着され、前記タンク３
内の流体レベルに応じて弁の開閉を行ない、余量
分の流体４を、前記タンク３内の圧力に比して充
分に圧力が低い排出路に排出させることにより、
前記タンク３内の流体レベルを基準値に維持する
ための高差圧調節弁１と、該高差圧調節弁１の制
御装置の構成を示したものである。
この第１図において被制御系の構成は、上述し
た如く従来のものと同様であるが、制御装置は、
レベル検出器７、減算器８、比例積分調節器９に
加え、新規に、前記レベル検出器７により検出さ
れるレベル信号に応じてそれぞれａ端子およびｂ
端子から入力される信号を選択的に出力する２つ
の切替リレー１０，１１、それぞれ異なる規定の
信号を発生する３つの信号発生器１２，１３，１
４前記レベル信号をモニタし、前記タンク３内に
充填される流体４に対する調節弁閉レベルSAお
よび調節弁開レベルSBとの比較結果に応じて前記
切替リレー１０，１１を制御するモニタスイツチ
１５を具備して構成されている。
以下にその動作を詳述する。まず、前記タンク
３内における流体４のレベルは、前記レベル検出
器７によつてレベル信号S1に変換され、前記モニ
タスイツチ１５および前記切替リレー１０のｂ端
子に入力される。ここで前記モニタスイツチ１５
は、上述した如く入力されたレベル信号S1をモニ
タするとともに、該レベル信号S1と前記調節弁閉
レベルSAおよび調節弁開レベルSBと比較してお
り、その比較結果に応じて前記切替リレー１０，
１１を下表に示す如くに制御する。
[Technical Field of the Invention] The present invention relates to a control device for a high differential pressure control valve used under conditions where there is a large difference between inlet pressure and outlet pressure in a thermal power generation boiler or a chemical plant. The present invention relates to an improvement for preventing valve erosion caused by a slight opening control operation of a high differential pressure regulating valve. [Technical Background of the Invention] For example, in thermal power generation boilers, chemical plants, etc., many so-called control valves are used, which are attached to pipes, pressure vessels, etc., and control fluids or pressurized bodies. Among these control valves, FIG. 4 shows a conventional high differential pressure control valve that is used, for example, to control the level of fluid in a tank under conditions where the difference between inlet pressure and outlet pressure is particularly large. This figure shows the configuration of this control device. According to FIG. 4, the high differential pressure regulating valve 1 is installed in a system in which a pump 5 sends out a fluid 4 flowing into a tank 3 from an inflow pipe 2, and the fluid level in the tank 3 is The fluid level in the tank 3 is maintained at the set value by opening the valve and discharging the fluid 4 through the outflow pipe 6 when the value exceeds the set value. As described above, in the controlled system shown here, the pressure on the tank 3 side is sufficiently higher than the pressure on the discharge side of the control valve 1, and exhibits a high differential pressure as described above. On the other hand, the control device includes a level detector 7, a subtracter 8, and a proportional-integral regulator 9, and inputs the level signal of the fluid 4 detected by the level detector 7 to the subtracter 8, A deviation is obtained by subtracting the level set value input from a level setter (not shown), and the deviation is input to the proportional-integral regulator 9, and the opening/closing control of the control valve 1 is controlled based on the deviation. By executing this, the level control of the fluid 4 described above is performed. [Problems with the background art] According to the conventional high differential pressure control valve control device,
In the entire level of the fluid 4 exceeding the level setting value, the control valve 1 is adjusted according to the level of the fluid 4.
Therefore, depending on the situation, the control valve 1 may be maintained in a slightly open state. Under such a slightly open state of the control valve 1, the flow rate of the fluid 4 discharged from the control valve 1 with a high differential pressure becomes extremely high as described above. Erosion is likely to occur in the stem (valve rod), seat, etc., and the lifespan of the control valve 1 is extremely shortened, as well as valve leakage that occurs due to the erosion. However, there was a problem that the plant efficiency decreased. [Object of the Invention] The present invention has been made in order to eliminate the above-mentioned problems, and prevents erosion of the stem, seat, etc. under the slightly open state of the control valve 1. It is an object of the present invention to provide a control device for a high differential pressure regulating valve that can extend the life of the valve and also contribute to preventing a decrease in plant efficiency. [Summary of the Invention] Therefore, the present invention provides a level detection means for detecting the level of a fluid, and a monitor for monitoring the relationship between the detected value of the fluid level and a preset closed level and open level (closed level < open level). means for generating a forced valve closing signal for forcibly closing the high differential pressure control valve; a first switching means for switching to and outputting a detected value; a calculation means for calculating the deviation between the output of the first switching means and a set level; and a specified opening for setting the high differential pressure control valve to a specified opening. a second signal generating means for generating a degree signal; a third signal generating means for generating a fully closed signal for changing the high differential pressure regulating valve from a specified opening to a fully closed condition; and a detected value of a fluid level. a second switching means for switching the fully closed signal to the specified opening signal and outputting it as a lower limit opening signal during a period from when the signal exceeds the close level and further exceeds the open level until it reaches the close level again; , proportional-integral adjustment means for limiting the deviation signal from the calculation means by the lower limit opening signal from the second switching means and outputting a valve opening command signal, In addition, the high differential pressure control valve should be opened and closed at full speed below the minimum opening, and the fluid at an opening smaller than the minimum opening should be The above objective is achieved by virtually prohibiting level control. In the present invention, the level detection means corresponds to the level detector 7 of the embodiment described below,
The monitoring means corresponds to the monitor switch 15. Similarly, the first signal generating means, the second signal generating means, and the third signal generating means correspond to the signal generators 12, 14, and 13, respectively, and the calculating means is the subtracter 8.
corresponds to Further, the first switching means and the second switching means correspond to the switching relays 10 and 11, respectively, and the proportional-integral adjusting means corresponds to a proportional-integral regulator. [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail based on the accompanying drawings. FIG. 1 shows an embodiment of the present invention, which is installed in a system that sends out fluid 4 flowing into a tank 3 from an inflow pipe 2 by means of a pump 5, similar to that shown in FIG. 4. and said tank 3
By opening and closing the valve according to the fluid level in the tank 3 and discharging the excess amount of fluid 4 to a discharge path whose pressure is sufficiently lower than the pressure inside the tank 3,
This figure shows the configuration of a high differential pressure regulating valve 1 for maintaining the fluid level in the tank 3 at a reference value, and a control device for the high differential pressure regulating valve 1. In FIG. 1, the configuration of the controlled system is the same as that of the conventional system as described above, but the control device is
In addition to the level detector 7, the subtractor 8, and the proportional-integral regulator 9, a terminal a and a terminal b are newly added, respectively, in accordance with the level signal detected by the level detector 7.
Two switching relays 10, 11 that selectively output signals input from terminals, three signal generators 12, 13, 1 that generate different prescribed signals, respectively.
4 a monitor switch that monitors the level signal and controls the switching relays 10 and 11 according to the comparison result with the control valve close level S A and the control valve open level S B for the fluid 4 filled in the tank 3; 15. The operation will be explained in detail below. First, the level of the fluid 4 in the tank 3 is converted into a level signal S1 by the level detector 7, and is input to the monitor switch 15 and the b terminal of the switching relay 10. Here, the monitor switch 15
monitors the input level signal S 1 as described above, and compares the level signal S 1 with the control valve close level S A and the control valve open level S B , and depending on the comparison result, switching relay 10,
11 is controlled as shown in the table below.
以上説明したように、本発明の高差圧調節弁の
制御装置によれば、高差圧調節弁の最小開度をエ
ロージヨンが生じない開度に制限するとともに、
弁開閉は全速で行ない、レベル制御等のための微
小開度での連続運転を禁止するようにしたため、
前記エロージヨン防止に伴ない前記高差圧調節弁
の長寿命化を果せるとともに、該エロージヨンに
起因する弁リーク等によるプラント効率の低下防
止にも寄与できるという優れた効果を得ることが
できる。
As explained above, according to the high differential pressure regulating valve control device of the present invention, the minimum opening degree of the high differential pressure regulating valve is limited to an opening degree that does not cause erosion, and
The valves are opened and closed at full speed, and continuous operation at minute openings for level control, etc. is prohibited.
Along with the prevention of erosion, the life of the high differential pressure regulating valve can be extended, and an excellent effect can be obtained in that it can also contribute to preventing a decrease in plant efficiency due to valve leakage caused by the erosion.
第１図は、本発明に係る高差圧調節弁による被
制御系とこの高差圧調節弁の制御系の構成を示す
概念図、第２図ａ，ｂ，ｃは、第１図に示した制
御系で扱われるレベル信号、制御用レベル信号、
調節弁開度指令信号の変化態様を示す図、第３図
は本発明の高差圧調節弁の制御装置に用いられる
切替リレーのロジツク構成の１例を示す図、第４
図は従来の高差圧調節弁による被制御系とこの高
差圧調節弁の制御系の構成を示す概念図である。
１……高差圧調節弁、２……流入配管、３……
タンク、４……流体、５……ポンプ、６……流出
配管、７……レベル検出器、８……減算器、９…
…比例積分調節器、１０，１１……切替リレー、
１２，１３，１４……信号発生器、１５……モニ
タスイツチ、SA……調節弁閉レベル、SB……調
節弁開レベル、S1……レベル信号、S2……調節弁
強制閉信号、S3……制御用レベル信号、S4……レ
ベル設定値、S5……偏差信号、S6……下限信号、
S7……全閉信号、S8……規定開度信号、S9……全
開信号、S10……調節弁開度指令信号。
FIG. 1 is a conceptual diagram showing the configuration of a system to be controlled by a high differential pressure regulating valve according to the present invention and a control system for this high differential pressure regulating valve, and FIG. 2 a, b, and c are shown in FIG. Level signals handled by control systems, control level signals,
FIG. 3 is a diagram showing how the control valve opening degree command signal changes; FIG.
The figure is a conceptual diagram showing the configuration of a controlled system using a conventional high differential pressure regulating valve and a control system for this high differential pressure regulating valve. 1...High differential pressure control valve, 2...Inflow piping, 3...
Tank, 4... Fluid, 5... Pump, 6... Outflow piping, 7... Level detector, 8... Subtractor, 9...
...Proportional-integral regulator, 10, 11...Switching relay,
12, 13, 14... Signal generator, 15... Monitor switch, S A ... Control valve closing level, S B ... Control valve open level, S 1 ... Level signal, S 2 ... Control valve forced closing. signal, S 3 ... control level signal, S 4 ... level setting value, S 5 ... deviation signal, S 6 ... lower limit signal,
S 7 ... Fully closed signal, S 8 ... Specified opening signal, S 9 ... Fully open signal, S 10 ... Control valve opening command signal.
Claims (1)
に設けられる高差圧調節弁を、前記流入側から流
入する流体のレベルが設定レベルとなるべく開閉
制御する高差圧調節弁の制御装置において、 流体のレベルを検出するレベル検出手段と、 該流体レベルの検出値と予め設定した閉レベル
及び開レベル（閉レベル＜開レベル）との関係を
監視する監視手段と、 前記高差圧調節弁を強制閉鎖するための弁強制
閉信号を発生する第１の信号発生手段と、 流体レベルの検出値が前記閉レベル以上になつ
た時に前記弁強制閉信号から当該検出値に切り替
えて出力する第１の切り替え手段と、 該第１の切り替え手段の出力と前記設定レベル
との偏差を求める演算手段と、 前記高差圧調節弁を規定開度にするための規定
開度信号を発生する第２の信号発生手段と、 前記高差圧調節弁を規定開度から全閉状態にす
るための全閉信号を発生する第３の信号発生手段
と、 流体レベルの検出値が前記閉レベルを超え、更
に開レベルを超えてから再び前記閉レベルとなる
までの間、前記全閉信号を前記規定開度信号に切
り替えて下限開度信号として出力する第２の切り
替え手段と、 前記演算手段からの偏差信号を前記第２の切り
替え手段からの下限開度信号により制限し、弁開
度指令信号を出力する比例積分調整手段と を具備することを特徴とする高差圧調節弁の制御
装置。 ２ 下限開度信号は、前記高差圧調節弁のエロー
ジヨンを生じない開度に対応した値に設定される
ことを特徴とする特許請求の範囲第１項記載の高
差圧調節弁の制御装置。[Claims] 1. A height difference that controls opening and closing of a high differential pressure regulating valve provided between an inflow side and an outflow side that have a pressure difference of a certain level or more so that the level of fluid flowing from the inflow side reaches a set level. A pressure regulating valve control device includes: a level detection means for detecting a fluid level; a monitoring means for monitoring a relationship between a detected value of the fluid level and a preset closed level and open level (closed level < open level); , a first signal generating means for generating a valve forced closing signal for forcibly closing the high differential pressure control valve; and a first signal generating means for generating a valve forced closing signal for forcibly closing the high differential pressure control valve; a first switching means for switching to and outputting a value; a calculation means for calculating a deviation between the output of the first switching means and the set level; and a specified opening for setting the high differential pressure control valve to a specified opening. a second signal generating means for generating a degree signal; a third signal generating means for generating a fully closed signal for changing the high differential pressure control valve from a specified opening to a fully closed condition; and a detected fluid level value. a second switching means for switching the fully closed signal to the specified opening signal and outputting it as a lower limit opening signal during a period from when the signal exceeds the close level and further exceeds the open level until it reaches the close level again; , a high differential pressure adjustment characterized by comprising proportional integral adjustment means for limiting the deviation signal from the calculation means by a lower limit opening signal from the second switching means and outputting a valve opening command signal. Valve control device. 2. The control device for a high differential pressure regulating valve according to claim 1, wherein the lower limit opening degree signal is set to a value corresponding to an opening degree that does not cause erosion of the high differential pressure regulating valve. .
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23577585A JPS6295612A (en) | 1985-10-22 | 1985-10-22 | High differential pressure control valve control device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23577585A JPS6295612A (en) | 1985-10-22 | 1985-10-22 | High differential pressure control valve control device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6295612A JPS6295612A (en) | 1987-05-02 |
| JPH0574845B2 true JPH0574845B2 (en) | 1993-10-19 |
Family
ID=16991053
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23577585A Granted JPS6295612A (en) | 1985-10-22 | 1985-10-22 | High differential pressure control valve control device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6295612A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100362696B1 (en) * | 2000-07-26 | 2002-11-27 | 한화종합화학 주식회사 | Material for floor construction including cashew coating composition |
-
1985
- 1985-10-22 JP JP23577585A patent/JPS6295612A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6295612A (en) | 1987-05-02 |
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