JPS6324411Y2 - - Google Patents

Description

[Detailed description of the invention] This invention improves the problem that when measuring a multiphase flow such as steam containing mist using a vortex flowmeter, sensitivity decreases and becomes unstable when mist adheres to the detection part. Regarding how to.

The applicant filed Japanese Patent Application No. 57-206800 (Unexamined Japanese Patent Application No. 59-
97007), we proposed a new vortex flowmeter with the aim of improving the detection sensitivity of Karman vortices and improving its durability. This vortex flowmeter introduces vortex differential pressure into the pressure change detection chamber by drilling a pressure communication port on the side of the vortex generator so as to communicate with the pressure change detection chamber, which is bored parallel to the axis of the vortex generator. This detection method detects this vortex differential pressure by using a built-in force detection element with an outer diameter slightly smaller than the inside diameter of the pressure detection chamber so as to have a minute gap with the wall surface of the pressure change detection chamber. The end face of the cylindrical body is fixed to one end of the vortex generating body, and the other end of the cylindrical body is used as a plate-shaped body, and the force detection element detects the vortex differential pressure acting on this plate-shaped body. In this invention, the purpose of the pressure introduction port is simply to introduce the vortex differential pressure, and the opening position does not matter. When the fluid to be measured is a multiphase flow such as steam containing mist, the liquid flows down through the plate-shaped body and blocks the space between the tip of the plate-shaped body and the vortex generator, so the signal level decreases at low flow rates with small differential pressure. This results in measurement errors. The present invention is intended to solve these problems, and will be explained with reference to the drawings.

FIG. 1 is a front view of a conventional example in which A is a front view facing the flow, and B is a side view of A. 1 is a tube body, 2 is a vortex generator, and 3 is a cylindrical body 4 with a force transducer 7 installed inside the tube body 1.
The flange 5 fixed to the cylindrical body 4 is a plate-shaped body disposed at the other end of the cylindrical body 4 so that the flat plate portion faces the flow direction. This plate-like body receives a vortex differential pressure introduced from a pressure communication port 6 that is bored in the side surface of the vortex generator 2 and communicates with the pressure change detection chamber 11 . Since the cylindrical body 4 has an outer diameter slightly smaller than the inner diameter of the pressure change detection chamber 11, there is a small gap, and due to the force caused by the vortex differential pressure, the cylindrical body 4 is slightly displaced left and right about the fixed portion as a fulcrum. This force is converted into an electrical signal by a force converter 7 and output from a terminal 8. Since the vortex differential pressure is proportional to the density and the square of the flow velocity, the vortex differential pressure at a small flow rate of gas is minute and the output is small. When such a gas contains mist, it passes through the pressure introduction port 6 and adheres to the bottom of the pressure change detection chamber 11, and the gap with the tip of the plate-shaped body 5 is closed by this fluid. If the fluid is steam, condensation will cause a similar problem if the flow rate is stopped and the temperature drops. Since the viscosity of these liquids is extremely high compared to that of gas, the viscous drag is also large and the height sensitivity is reduced.

FIG. 2 shows the invention of the present application made to solve such problems. Components that are in common with the component numbers in FIG. 1 are represented by the same numbers. Reference numeral 9 denotes a drain hole, which opens below the lower end of the plate-like body 5. Reference numeral 10 regulates the gap between the plate-shaped body 5 and the vortex generating body, and also controls the position of this gap by drain hole 9.
This is a barrier that is made higher than the drain hole 9 to make it easier for liquid to flow out, but it may be omitted if the position of the drain hole 9 can be lowered. Moreover, it may also be used as a pressure introduction hole.

FIG. 3 shows another embodiment in which the drain hole 9 is bored so as to be inclined downward from the axis of the vortex generator toward the side surface, so that the liquid flows out more easily.

As described above, according to the present invention, it is possible to very easily and inexpensively prevent a decrease in sensitivity due to the blockage of the gap at the tip of the plate-shaped body where the liquid receives the vortex differential pressure in mist fluid measurement, and to prevent signal dropout due to this.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional vortex flow meter, in which A is a front view seen from the flow direction, and B is a side view taken at cross section AA in FIG. FIG. 2 is an explanatory diagram of the present invention, and A and B are a front view and a side view similar to those in FIG. 1. FIG. 3 shows another embodiment. 1: pipe body, 2: vortex generator, 3: flange fixing the cylindrical body 4, 5: plate-shaped body, 6: pressure introduction hole,
7: Force transducer, 8: Terminal, 9: Drain hole.

Claims (1)

[Claims for Utility Model Registration] (1) Pressure change detection in which a hole is drilled parallel to the axis of the vortex generator in a vortex generator disposed facing the flow in a pipe through which the fluid to be measured flows. A pressure communication port is bored in the side surface of the vortex generator so as to communicate with the chamber,
A cylindrical body is maintained in the pressure change detection chamber with a small distance from the wall surface of the pressure change detection chamber, and a cylindrical body is fixed to one end of the vortex generator or the tube body, and a force transducer is built in the cylindrical body. , in a vortex flowmeter in which the other end of this cylindrical body is formed into a plate-shaped body, and the force due to the pressure introduced from the pressure communication port to the plate-shaped body is detected by the force converting element, the vortex generating body A vortex flowmeter characterized in that a drain hole is bored in the side surface near the gap formed by the end of the plate-like body and the bottom of the pressure change detection chamber opposing thereto. (2) The vortex flowmeter according to claim 1, wherein the drain hole is formed so as to be inclined downward from the axis of the vortex generator toward the side surface.