JP2013225263A - Governor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a venturi-system pilot type governor device with high stability.SOLUTION: In a venturi-system pilot type governor device, a pilot flow passage 12 is provided with a venturi 12 V through which a constriction part 12 V1 communicates with a driving part 11A for a main governor 11, a pilot governor 13 which controls the flow rate of the pilot flow passage 12 on the basis of secondary pressure is provided, and capacity Vof a communication part between the venturi 12 V and pilot governor 13 is so set that control pressure becomes stable against load variation in primary pressure.

Description

  The present invention relates to a pilot-type pressure regulator.

  As a fluid supply system for city gas or the like using a pipeline, a system is adopted in which the high-pressure fluid on the upstream side is decompressed in stages and supplied to the downstream side. At this time, each stage for pressure reduction is equipped with a pressure regulator (governor) in the fluid conduit, and the pressure on the downstream side is adjusted to the set pressure. In the following description, the pressure in the upstream fluid conduit of the pressure regulator is referred to as primary pressure, and the pressure in the downstream fluid conduit set by the pressure regulator is referred to as secondary pressure.

  The pressure regulator adjusts so that the secondary pressure in the downstream conduit becomes the set pressure regardless of the pressure fluctuation of the upstream fluid conduit and the load flow rate. This pressure regulator generally has a direct acting type as a simple structure equipped in a fluid conduit having a relatively small flow rate, and a pilot type as one equipped in a fluid conduit having a relatively large flow rate. (For example, refer to Patent Document 1 below).

FIG. 1 is an explanatory diagram (FIG. 1A is a piping configuration diagram, and FIG. 1B is an operation explanatory diagram) showing a configuration example of a conventional pilot pressure regulator. The pressure regulating device J10 provided in the fluid conduit 1 is provided between the upstream fluid conduit 1A and the downstream fluid conduit 1B, and includes a main governor 11, a pilot flow path 12, and a pilot governor 13. The pilot flow path 12 is a flow path that connects the upstream fluid conduit 1A and the downstream fluid conduit 1B. The pilot governor 13 is provided in the pilot flow path 12 and adjusts the flow rate of the fluid flowing through the pilot flow path 12 by opening and closing according to the secondary pressure P ₂ detected through the secondary pressure detection flow path 14. It is. The main governor 11, the control pressure P _C is fed to the control pressure chamber 11A1 of the driving unit 11A via the control pressure passage 15 branched from the pilot flow passage 12, the control pressure P _C drops upstream fluid conduit 1A and the downstream A valve mechanism is provided that operates so as to increase the opening degree of the flow part communicating with the side fluid conduit 1B.

According to such a pressure regulator J10, the opening degree of the main governor 11 can be controlled by the control pressure P _C amplified in the pilot flow path 12. That is, when the secondary pressure P ₂ decreases due to fluid consumption on the downstream side, the pressure applied to the diaphragm of the pilot governor 13 decreases, the valve of the pilot governor 13 opens, and the flow rate of the pilot flow path 12 increases. Since the pilot passage 12 is provided with a resistance portion (throttle) 12A, the pressure loss due to the resistance portion 12A increases as the flow rate of the pilot passage 12 increases, and the control pressure passage 15 causes the drive portion 11A of the main governor 11 to move. The control pressure supplied to the control pressure chamber 11A1 decreases. Thereby, the opening degree of the circulation part of the main governor 11 is increased, and the flow rate flowing to the secondary side through this circulation part is increased. When the secondary pressure P ₂ rises to the set pressure, a new steady state is reached, and the secondary pressure P ₂ is held at the set pressure.

JP 2006-285660 A

As shown in FIG. 1 (b), the conventional Sei圧apparatus described above, the control pressure P _C for controlling the opening of the main governor 11 is output from the pilot channel 12. The driving force F for increasing the opening degree of the main governor is ensured depending on how much the control pressure P _C can be reduced by the pressure loss due to the resistance portion 12A provided in the pilot flow path 12. However, since the control pressure P _C is a pressure between the primary pressure P ₁ and the secondary pressure P ₂ , the primary pressure P ₁ is reduced from, for example, the normal pressure (= 700 kPaG) to the design minimum pressure P ₁ ′ (= 300 kPaG). Then, the difference between the primary pressure P ₁ ′ and the secondary pressure P ₂ (for example, 150 kPaG) becomes small, the flow rate of the pilot flow path 12 cannot be increased, and the control pressure P _C ′ due to the pressure loss of the resistance portion 12A is lowered. I can't. Therefore, the driving force F ′ becomes small, and there arises a problem that a driving force sufficient to fully open the main governor 11 cannot be obtained.

As a low differential pressure regulating mechanism for solving this problem, there is a venturi type pressure regulating device as shown in FIG. 2 (FIG. 2A is a piping configuration diagram, and FIG. 2B is an operation explanation). It is a figure.) In FIG. 2, the same parts as those in FIG. In this system, a venturi 12V is adopted as a resistance portion provided in the pilot flow path 12, and the control pressure flow path 15 is communicated with the narrowed portion 12V1 of the venturi 12V. According to this, it is possible to generate a pressure lower than the atmospheric pressure by the fluid passing through the narrow portion 12V1 of the venturi 12V at a high speed, and by outputting this low pressure as the control pressure P _C (P _C ′), As shown in FIG. 2B, a relatively large driving force F _V ′ can be obtained even when the primary pressure is lowered (at the set minimum pressure P ₁ ′) (F _{V in the} figure has a relatively high primary pressure. In this case, the driving force in case of normal pressure P ₁ is shown.)

However, in this venturi type pilot pressure regulator, when it is necessary to cause the main governor 11 to suddenly operate due to sudden load fluctuations, the flow rate flowing into and out of the drive unit 11A is delayed, and the control pressure P _C (P _C ') cannot follow the load fluctuation, and the operation tends to become unstable. For this reason, the venturi-type pilot pressure regulator shown in FIG. 2 is such that the load fluctuation on the primary side is moderate, or the secondary side capacity is large and unstable behavior of the secondary pressure is unlikely to occur. There was a problem that the use conditions had to be limited.

  This invention makes it an example of a subject to cope with such a problem. That is, in a pilot-type pressure regulator that outputs a control pressure for controlling the opening degree of the main governor from the pilot flow path, the opening degree of the main governor is sufficient even when the difference between the primary pressure and the secondary pressure is small. It is an object of the present invention to be able to control with a sufficient driving force, to obtain a stable secondary pressure even against a sudden load fluctuation, and to enhance the versatility of use conditions.

  In order to achieve such an object, a pressure regulator according to the present invention comprises at least the following configuration.

  A pressure regulator that is provided in a fluid conduit and regulates a primary pressure in an upstream fluid conduit to a secondary pressure in a downstream fluid conduit, the main pressure device being provided between the upstream fluid conduit and the downstream fluid conduit. A governor, and a pilot channel that communicates the upstream fluid conduit and the downstream fluid conduit, and the main governor includes a drive unit that adjusts an opening degree by a control pressure output from the pilot channel. The pilot flow path is provided with a venturi in which the constriction portion communicates with the drive section, and further provided with a pilot governor for adjusting the flow rate of the pilot flow path on the downstream side based on the secondary pressure, The pressure regulating device, wherein a communication portion capacity with a pilot governor is set so that the control pressure is stabilized against a load fluctuation of the primary pressure.

  The present invention has been devised to model a control system of a pilot-type pressure regulator that outputs a control pressure by a venturi provided in a pilot flow path in accordance with an actual operation, and a secondary pressure against a sudden load fluctuation. It has been newly found that the effective setting parameter for stabilizing the pressure is the joint capacity of the venturi and the pilot governor. According to the pressure regulator of the present invention, the secondary pressure of the venturi-type pilot pressure regulator can be stabilized by appropriately setting the connecting portion capacity between the venturi and the pilot governor. Even when the difference in the secondary pressure is small, the opening degree of the main governor can be stably controlled with a sufficient driving force. Thereby, the versatility of the venturi type pilot pressure regulator can be enhanced.

FIG. 1 is an explanatory diagram showing a configuration example of a conventional pilot pressure regulator (FIG. 1A is a piping configuration diagram, and FIG. 1B is an operation explanatory diagram). FIG. 2A is an explanatory diagram showing a configuration example of a venturi type pilot pressure regulator (FIG. 2A is a piping configuration diagram, and FIG. 2B is an operation explanatory diagram). It is explanatory drawing explaining the control system model of the pressure regulating apparatus which concerns on embodiment of this invention. 4 is a block diagram and a transfer function showing the operation of the control system model shown in FIG. FIG. 5 is a Bode diagram showing frequency characteristics of the transfer function shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is an explanatory diagram for explaining a control system model of the pressure regulator according to the embodiment of the present invention, and FIG. 4 is a block diagram and a transfer function showing the operation of the control system model shown in FIG. . The same parts as those described above are denoted by the same reference numerals, and a part of the overlapping description is omitted.

As shown in FIG. 3, the control system of the pressure regulator according to the embodiment of the present invention includes a pilot flow path 12, a venturi 12V, a pilot governor 13, a control pressure chamber 11A1, a control pressure flow path 15, a venturi 12V and a pilot governor 13. The connecting portion 20 is provided as a control element. The pilot governor 13 includes a nozzle 13 a and a flapper 13 b for adjusting the opening degree of the pilot governor 13. Here, x: displacement of the flapper 13b, C _PG: opening of the pilot governor 13, P _1: primary pressure, P _M: connection unit pressure, P _C: control pressure, P _2: the secondary pressure, g _1: Venturi 12 V upstream flow rate, g _M : downstream flow rate of venturi 12 V, g ₂ : flow rate of pilot governor 13, g _C : control flow rate (= g ₁ -g _M ), V _M : connection capacity, V _C : The volume of the control pressure channel 15 is shown.

Each control element of the block diagram shown in FIG. Control element e1 is the change elements of the opening C _PG Pilot governor 13, the opening C _PG Pilot governor 13 is opened to open the displacement x of the flapper 13b. Control element e2 is the change elements of the passing flow g ₂ pilot governor 13, the flow rate through g ₂ pilot governor 13 is changed by opening C _PG pilot governor 13. Control element e3 is a transfer element for obtaining the connecting portion pressure P _M, connecting portion pressure P _M is obtained by the integral of the flow rate to and from the flow to the connecting unit volume V _M. Control element e4 is the change elements of the downstream flow rate through g _M of the venturi 12V, downstream flow rate through g _M of the venturi 12V varies by the connecting portion pressure P _M. Control element e5 is a transfer element for obtaining the control pressure P _C, the control pressure P _C is calculated by the integral of the flow rate to and from the flow to the volume V _C of the control pressure passage 15. Control elements e6 is the change elements of the upstream passing flow g ₁ venturi 12V, upstream passing flow g ₁ of the venturi 12V varies with venturi output pressure (control pressure) P _C. Control element e7 is the change elements of the downstream flow rate through g _M of the venturi 12V, downstream flow rate through g _M of the venturi 12V varies with venturi output pressure (control pressure) P _C. Control elements e8 is the change elements of the passing flow g ₂ pilot governor 13, varies with the passing flow g ₂ upstream pressure of the pilot governor 13 (coupling portion pressure) P _M pilot governor 13.

When the block diagram shown in FIG. 4A is transformed into a formula, the second-order lag transfer function shown in FIG. 4B is obtained. Here, T _P can be expressed by the following formula (a), and K _VC can be expressed by the following formula (b) (where R is a gas constant, θ is a gas temperature), and FIG. It is confirmed that the pressure flow behavior of the Venturi 12V can be expressed by the following empirical formulas (1) and (2).

g ₁ = C · {P _C · (P ₁ −P _C )} ^1/2 (1)
Where C is a coefficient corresponding to the upstream shape of the venturi

ただし、ａ〜ｆはベンチュリ形状に応じた係数

Where a to f are coefficients corresponding to the venturi shape

FIG. 5 is a Bode diagram showing frequency characteristics of the transfer function of the open loop shown in FIG. Here it is shown a difference in frequency characteristics when changing the connection portion capacitance V _M. First, in the example of the pressure regulator in which the coupling portion capacity V _M = 24 ml, the phase at the gain = 0 dB is smaller than −180 °, which indicates that the frequency characteristic in this case is unstable. On the other hand, in the example of the pressure regulator in which the coupling portion capacity V _M = 0.8 ml, the phase at the gain = 0 dB is larger than −180 °, and the frequency characteristic in this case is stable. Is shown.

Thus, the frequency characteristic of the transfer function shown in FIG. 4 (b), in the case of changing the connecting portion capacitance V _M to match the other conditions, the smaller the coupling portion capacitance V _M, gain = It can be confirmed that the phase at 0 dB is large (the phase delay is small) and the phase margin is large. As apparent from this, even if a sudden load change of the primary pressure P1 is generated by setting the connecting portion capacitance V _M, the control pressure P _C and the secondary pressure P ₂ can be stabilized become. In particular, to miniaturize the connecting portion capacitance V _M, specifically, by directly connecting the input side of the output side and the pilot governor 13 of the venturi 12V, obtain pilots ShikiSei圧apparatus having high stability venturi system be able to.

1: fluid conduit, 1A: upstream fluid conduit, 1B: downstream fluid conduit,
11: main governor, 11A: drive unit, 11A1: control pressure chamber,
12: Pilot flow path, 12A: Resistance section,
12V: Venturi, 12V1: Stenosis,
13: Pilot governor, 13a: Nozzle, 13b: Flapper,
14: secondary pressure detection flow path, 15: control pressure flow path,
20: connecting portion, V _M: connecting portion capacity

Claims (3)

A pressure regulator that is mounted on the fluid conduit and regulates the primary pressure in the upstream fluid conduit to the secondary pressure in the downstream fluid conduit;
A main governor provided between the upstream fluid conduit and the downstream fluid conduit; and a pilot flow path communicating the upstream fluid conduit and the downstream fluid conduit;
The main governor includes a drive unit that adjusts an opening degree by a control pressure output from the pilot flow path,
A pilot governor that adjusts the flow rate of the pilot flow path based on the secondary pressure on the downstream side of the pilot flow path is provided with a venturi in which the constriction portion communicates with the drive unit,
2. A pressure regulator according to claim 1, wherein a communicating portion capacity between the venturi and the pilot governor is set so that the control pressure is stabilized against a load fluctuation of the primary pressure.   The pressure regulating device according to claim 1, wherein the capacity of the connecting portion is miniaturized.   3. The pressure regulating device according to claim 1, wherein an output side of the venturi and an input side of the pilot governor are directly connected.

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