JPH01201708A - Multitubular flow controller - Google Patents

Abstract

PURPOSE:To control flow in a range in which range ability is good by selecting the maximum opening of the flow control valves of respective branch pipelines by a high selector and selecting their minimum opening by a low selector. CONSTITUTION:The title multitubular flow controller of flow control valves 31-3n provided for branch pipelines 21-2n of a main pipeline 1 consists of flow sensors 41-4n, flow controller 51-5n, pressure controller 8, etc. A high selector 9 and a low selector 10 are provided and operational outputs MV1-MVn are inputted as the valve opening signals of the respective flow control valves 3. A maximum valve opening signal PVH selected by the high selector 9 and a minimum valve opening signal PVL selected by the low selector 10 are inputted to a pressure set value determining logic 11, the most suitable pressure set value SV0 is operated and it is supplied to a pressure controller 8. Thus, the pressures of the flow control valves 3 of the respective branch pipelines 2 are controlled in the range in which the range ability is good.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to changing the rangeability of a control valve in a multi-tube flow control device having a control valve in each branch pipe.

An example of the prior art will be explained based on FIG.

1 is the main pipe through which the fluid F is transferred; 2. , 22...2n
are n branch pipes branching from the main pipe; 3. , 32...
3n is a control valve inserted into each branch pipe; 4. ,42...
4n is a flow rate sensor inserted into each branch pipe, Pv.

PV, . . . PVn are the measured values.

5, 52...5n are flow rate controllers provided in each branch pipe, and each measured value PV+, PVz...'PVn and set value SV.

Manipulated output MV obtained by controlling and calculating the deviation of Sv2..., respectively;
.

MY2...MVn for each control valve 3. ．． 32...3n, and the flow rate of each branch pipe is controlled to each set value.

6 is a pressure sensor inserted into the main pipe 1 and is a PV.

is the measured value, and 7 is a control valve also inserted into the main pipe 1. Reference numeral 8 denotes a pressure regulator, which supplies a manipulated output MVo obtained by calculating the deviation between the measured value PVo and the set value SVo by 14 dJ to the control valve 7 to control the pressure in the main pipe to the set value.

(Problems to be Solved by the Invention) In systems that control the flow rates of a large number of branch pipes as described above, the pressure in the main pipe is usually controlled at a fixed value. However, in order to be able to control a wide range of flow rates from small to large, the control valve must be used within a range with good rangeability.

FIG. 4 is a characteristic diagram showing the relationship between valve opening degree and flow rate using pressure as a parameter. For example, looking at characteristic C3 with pressure P1 as a parameter, in the valve opening range α% to β% with good rangeability, the flow rate control range is FL, -FH,
It is.

If an attempt is made to control the small flow rate range under such conditions of pressure P1, the valve opening will be 4% or less, and it will be necessary to throttle the valve opening beyond the range where rangeability is good.

On the other hand, if you keep the pressure low and set the small flow rate range to the range of α% to β% with good rangeability, the valve may open even if the range exceeds β%, making it impossible to control the flow rate. .

Such problems occur in each branch pipe, so if the pressure in the main pipe is controlled to be constant, it is impossible to use all flow control valves in each branch pipe within a range with good rangeability. be.

An object of the present invention is to provide a multi-tube flow control device that can solve these problems.

(Means for Solving the Problems) A structural feature of the present invention is a multi-pipe flow control device having a flow rate control valve and a flow rate regulator means in each branch pipe, and a pressure regulating means provided in the main pipe. , a high selector means for selecting the maximum value and a low selector means for selecting the minimum value among the flow control valve opening degrees of each branch pipe, and a range between the maximum value and the minimum value is determined to have good rangeability of the flow control valve. and logic means for determining the setting value of the pressure regulating means for the main pipe so that the pressure is within the range of .

(Function) According to the present invention, the maximum opening of the flow control valves of each branch pipe is selected by the high selector, the minimum opening is similarly selected by the low selector, and each flow rate is selected based on these opening signals. The pressure setting value of the main line is determined by logic means so that the control valve is within a range with good rangeability.

(Example) The present invention will be explained in detail based on FIG.

Elements that are the same as those explained in FIG. 7 are given the same reference numerals, and explanations are omitted, and explanations of characteristic parts will be added.

9 is a high selector, and each flow control valve 31°3□・
・・Manipulation output MV to them as a valve opening signal of 3n
, , MV2...MVn is input. 10
is a low selector, and similarly the operation output of each flow control valve is input.

Maximum valve opening signal PvH selected by high selector and minimum valve opening signal PV selected by low selector
is inputted into the pressure setting logic 11, and the optimum pressure setting 11asVo is calculated and supplied to the pressure regulator 8.

Pressure setting value determination logic 11 based on FIGS. 2 and 3
An example of this and its operation will be explained.

111 is the first PID iJ for inputting the minimum opening degree PvL
It is a one-section meter, and a pressure setting value such that the minimum opening degree is SV is transmitted as a manipulated output MVL with a set value of 5VL=α+ε6% (ε: minute m).

+12 is the maximum opening PV, input the second PIDii11
It is a savings measure, SV, = β- and 2% (E,: Ishikoi City)
A pressure setting value such that the maximum opening becomes SV is transmitted as the manipulated output MV.

+13 is a changeover switch means, which holds SVo in the @ position, selects MY and makes it SVo in the ■ position, and selects MV and transmits as SVo in the ■ position.

114 is a switch changeover sequence means, which selects the changeover position of the changeover switch means 113 according to the sequence table shown in FIG.

First, when PV > 4 o'clock, ■ position is selected and MV.

is supplied as SVo. This is the case where the maximum opening degree is 8 points in characteristic C2 in the case of pressure P2 in FIG. 4, and SVo is controlled to increase and the pressure becomes P2,
The characteristics shift to C2゛, and the maximum opening degree at the same flow rate becomes β.
It will be pulled back to -5%.

When PV < α, position ■ is selected and MV is L

Supplied as LSVo. This is the case in Fig. 4 where the minimum opening is at point b in characteristic C1 for pressure P1, and SVo is controlled to decrease and the pressure becomes Plo, and the characteristic shifts to C3'' and the minimum opening at the same flow rate. degree is opened to a+i%.

However, when the maximum opening PV of a certain flow control valve > β and the minimum opening PVL of another flow control valve <'', if the maximum opening PV is 4100%, the switch selects the O position and sets the pressure setting value SVo. maintains its current value and does not change it,
When PV = +00%, select ■ to set the maximum value PV,
Change SVo by Mv, 4 until it reaches 4100%.

Naturally, if the maximum value and minimum value are in the range of β to α% (PVH≦β, PVL≧a), select position ① and do not change SVo.

In the above embodiment, since the setting fltisVo of the pressure regulator 8 may change frequently, a function as shown in FIG. 5 can be added. That is, a plurality of pressure setting values P1. P2. P)・Pn(PI<P2<P3<・P
n) is held by the setting device 12 and is a logic determining means.

11, the changeover switch 13 is driven to select one of the candidates.

At this time, it is desirable to switch with hysteresis as shown in FIG. 6 so that setting values do not switch frequently near the switching point.

In yet another embodiment, the first one in the decision logic 11
．． An intermittent integral type controller can also be used as the second iJ1 node.

(Effects) As explained above, according to the present invention, it is possible to control the pressure of the flow rate control valve of each branch pipe within a range with good rangeability, and the flow rate FkIlI within a wide flow rate range with good rangeability. A controllable multi-tube flow control device can be easily realized.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is a block diagram showing an embodiment of the pressure setting value determination logic which is the main part,
Fig. 3 is a sequence table showing the switching procedure of the switch means, Fig. 4 is an explanatory diagram of operation, Figs. 5 and 6 are block diagrams and switching characteristic diagrams showing other embodiments of pressure setting, and Fig. 7 is FIG. 1 is a configuration diagram showing an example of a conventional technique. 1... Main pipe, 2. , 22...branch pipe, 3. , 32
...flow control valve, 4. , 42...flow rate sensor, 5
．． , 52...Flow rate controller, 6...Pressure sensor, 7
...Flow rate control valve, 8...Pressure regulator, 9...High selector, lO...Low selector, 11...Pressure set value determination logic. Figures 1 and 5 t71 & Signs Rafushi No. 4

Claims (1)

[Claims] In a multi-tube flow control device having a flow control valve and a flow rate regulator means in each branch pipe, and a pressure regulating means in the main pipe, the maximum value is selected from the flow control valve opening degree of each branch pipe. a high selector means to select the minimum value, a low selector means to select the minimum value, and a set value of the pressure regulating means for the main pipe so that the range of the maximum value and minimum value is within the range of good rangeability of the flow control valve. A multi-tube flow control device characterized by comprising logic means for determining.