JP2008089374A - Flow measurement and flow control device not affected by pressure loss by Coriolis flowmeter - Google Patents

Abstract

Disclosed is a flow measurement and flow control device using a Coriolis flowmeter that apparently does not cause a differential pressure.
A Coriolis flow meter, a pump that is disposed upstream of the Coriolis flow meter and transports fluid to the Coriolis flow meter, a position near the upstream side of the pump, and a position near the downstream side of the Coriolis flow meter. The differential pressure measuring means 26 for measuring the differential pressure with the Coriolis flow meter 24, the pump 25 and the differential pressure measuring means 26 are electrically connected, and the discharge amount of the pump 25 so that the differential pressure is zero or close to zero. And a control means 27 for controlling the flow rate, and the flow rate measuring / flow rate control device 21 is configured.
[Selection] Figure 1

Description

  The present invention relates to a flow rate measurement and flow rate control device that does not affect the pressure loss caused by a Coriolis flow meter.

  A conventional flow rate measuring device will be described with reference to FIG. 2 (see, for example, Patent Document 1 below). In FIG. 2, reference numerals 1a, 1b, and 1c indicate storage tanks. In the storage tanks 1a, 1b and 1c, filling liquids corresponding to purposes are stored. Liquid supply pipes 2a, 2b, and 2c are attached to the bottoms of the storage tanks 1a, 1b, and 1c. Open / close valves 3a, 3b, 3c are attached to the liquid supply pipes 2a, 2b, 2c. The on-off valves 3a, 3b, 3c are connected to a common liquid supply pipe (pipe through which fluid flows) 4. A pump 5, a Coriolis flow meter 6, a flow rate adjustment valve 7, and a filling nozzle 8 are connected to the liquid supply pipe 4 sequentially from the upstream side. A control means 10 is connected to the detection end of the Coriolis flow meter 6 via a signal line 9. An electromagnetic valve 12 is connected to the control means 10 via a signal line 11. The solenoid valve 12 is connected to the flow rate control valve 7 through the air pipe 13.

  In the above configuration, for example, when the filling container 14 is to be filled with the liquid stored in the storage tank 1a, the on-off valve 3a is first opened. Next, when the flow rate adjusting valve 7 is opened by the operation of the electromagnetic valve 12, the liquid (filling liquid) in the storage tank 1 a is transported by the pump 5 and flows through the liquid supply pipe 4. At this time, a mass flow rate is obtained by the Coriolis flow meter 6 and the control means 10. The liquid flowing through the liquid supply pipe 4 flows into the filling container 14 via the filling nozzle 8, whereby the filling of the liquid is started. The flow rate value to be filled is preset in the control means 10. The control means 10 is set to operate the solenoid valve 12 when the integrated value integrated by the control means 10 reaches the set value. When the solenoid valve 12 is actuated by an actuation signal from the control means 10, the flow rate regulating valve 7 is closed via the air pipe 13. Thereby, the filling of the liquid is stopped.

  The Coriolis flow meter 6 includes, for example, a portal flow tube, a vibration device, a pair of vibration detectors, and a transmitter. A fluid to be measured flows through the flow tube. The flow tube is configured to vibrate at the natural frequency of the flow tube by a vibration device. Both ends of the flow tube are fixed, and the amplitude becomes larger toward the vibration tip of the flow tube.

When the fluid to be measured flows through the vibrating portal flow tube, the fluid to be measured receives acceleration in the vibration direction. Since the flow tube has a gate shape, a Coriolis force in the opposite direction is generated when the fluid to be measured flows from the fixed end toward the vibration tip and when flowing from the vibration tip toward the fixed end. As a result, the portal flow tube is twisted between half cycles of vibration and twisted in the opposite direction between the next half cycles. The torsion angle at this time is proportional to the mass flow rate, and the vibration phase difference is obtained from the left and right vibration signals of the portal flow tube obtained by the vibration detectors attached to the left and right (inflow and outflow) of the portal flow tube. Detected. Since this vibration phase difference is proportional to the mass flow rate, a flow signal such as a frequency signal or an analog signal is generated and output based on the vibration phase difference.
Japanese Patent Laid-Open No. 9-69191

  When the pressure of the liquid flowing through the liquid supply line 4 is measured upstream and downstream of the Coriolis flow meter 6, a pressure difference is generated. The pressure difference is, in other words, a pressure loss. In the conventional equipment, if the equipment does not have a head (liquid feeding force), a predetermined flow rate does not flow due to the pressure loss caused by the Coriolis flow meter 6. It includes the danger.

  This invention is made | formed in view of the situation mentioned above, and makes it a subject to provide the flow measurement and flow control apparatus by a Coriolis flowmeter which do not produce a differential pressure | voltage apparently.

  The flow measurement and flow control device that does not affect the pressure loss by the Coriolis flowmeter of the present invention according to claim 1 made to solve the above-mentioned problem is arranged at the upstream position of the Coriolis flowmeter and the Coriolis flowmeter. A pump for transporting fluid to the Coriolis flow meter, and a differential pressure measuring means for measuring a differential pressure between a position near the upstream side of the pump and a position near the downstream side of the Coriolis flow meter, The pump and the differential pressure measuring means are electrically connected, and a control means is provided for controlling the discharge amount of the pump so that the differential pressure is zero or close to zero.

  According to the present invention, the pump is arranged at the upstream position of the Coriolis flow meter, and by controlling the rotational speed of the pump so that the differential pressure before and after these is a positive pressure and zero or near zero, an apparent difference is obtained. A Coriolis flow meter that does not generate pressure (pressure loss) can be obtained. Further, according to the present invention, it is possible to use a high-viscosity fluid for equipment having no sufficient lift (liquid feeding force).

  Hereinafter, description will be given with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a flow rate measurement and flow rate control device that does not affect the pressure loss by the Coriolis flow meter of the present invention.

  In FIG. 1, reference numeral 21 indicates a flow measurement and flow control device (hereinafter abbreviated as a flow measurement / flow control device) that does not affect the pressure loss by the Coriolis flowmeter of the present invention. The flow measurement / flow control device 21 is installed in a facility having a liquid supply pipe (fluid flow pipe) 23 having a storage tank 22 upstream. The flow measurement / flow control device 21 includes a Coriolis flow meter 24. Specifically, a Coriolis flow meter 24, a pump 25, a differential pressure measuring unit 26, and a control unit 27 are provided. In addition, the installation of this form shall be an example. A flow rate adjustment valve 28 is provided downstream of the liquid supply pipe 23.

  The storage tank 22 stores a filling liquid according to the purpose (the number of the storage tanks 22 may be plural). A liquid supply pipe 29 is attached to the bottom of the storage tank 22. An opening / closing valve 30 is attached to the liquid supply pipe 29. The on-off valve 30 is connected to the most upstream position of the liquid supply pipe 23.

  The liquid supply pipe 23 is a pipe through which a filling liquid (fluid and also a controlled fluid in the present invention) stored in the storage tank 22 flows to, for example, a filling container, and the conventional liquid supply pipe 1 (see FIG. 2). Designed and manufactured in the same way.

  The Coriolis flowmeter 24 supports one or both ends of the flow tube through which the fluid to be measured (controlled fluid) flows, and applies vibration around the support point in a direction perpendicular to the flow direction of the fluid to be measured in the flow tube. Sometimes it is a mass flow meter that utilizes the fact that the Coriolis force acting on the flow tube is proportional to the mass flow rate. The shape of the flow tube constituting the Coriolis flow meter is roughly classified into a straight tube type and a curved tube type, and is generally known.

  When the flow tube is a straight pipe type, when vibration in the direction perpendicular to the straight pipe axis in the center of the straight pipe supported at both ends is applied, the Coriolis force is applied between the support part and the central part of the straight pipe. A straight pipe displacement difference, that is, a vibration phase difference is obtained, and a flow rate signal is generated and output based on the vibration phase difference. The straight pipe type has a simple, compact and robust structure.

  On the other hand, when the flow tube is a curved tube type, it is superior to the straight tube type in that the shape for effectively taking out the Coriolis force can be selected. In fact, it has been proven that it is possible to detect mass flow with high sensitivity. In the case of the curved tube type, there are one with a single flow tube, two with a parallel flow tube, or one with a single loop. Although it does not specifically limit in this form, it respond | corresponds by the two parallel gate type flow tubes 31. FIG. The two flow tubes 31 in parallel have an inlet and an outlet for the filling liquid, and these inlet and outlet are connected to the liquid supply pipe 23, respectively.

  The Coriolis flow meter 24 outputs a flow signal to the control means 27. The control means 27 takes in the flow signal from the Coriolis flow meter 24 as a process value (control target value). The Coriolis flow meter 24 is connected to the control means 27 via a signal line 32.

  The pump 25 is connected to the liquid supply pipe 23. Specifically, it is connected to a position upstream of the Coriolis flow meter 24 (the pump 25 may be directly connected to the Coriolis flow meter 24). The pump 25 transports the filling liquid flowing through the liquid supply pipe 23 to the Coriolis flow meter 24 side, and such a pump 25 is provided with a rotation speed control means although not particularly shown. The rotation speed control means is connected to the control means 27 via the signal line 33. The rotation speed of the pump 25 is controlled based on a control signal from the control means 27.

  The differential pressure measuring means 26 includes an upstream measurement unit 34 and a downstream measurement unit 35 that detect the pressure of the filling liquid flowing through the liquid supply pipe 23. The upstream measurement unit 34 is connected to the liquid supply pipe 23 at a position upstream of the pump 25 (it may be connected to the vicinity of the inlet of the pump 25). The downstream measurement unit 35 is connected to the liquid supply pipe 23 at a position downstream of the Coriolis flow meter 24 (it may be connected to the vicinity of the outlet of the Coriolis flow meter 24). The differential pressure measuring unit 26 is configured to output the pressure difference (ΔP: differential pressure) obtained by the upstream measuring unit 34 and the downstream measuring unit 35 to the control unit 27 as a differential pressure signal (measured differential pressure of the flowmeter). Has been. The differential pressure measuring means 26 is connected to the control means 27 via a signal line 36.

  The control means 27 has a microcomputer function. That is, it has a general configuration such as a CPU and a storage unit. The control means 27 is configured to perform a predetermined process based on the differential pressure signal from the differential pressure measuring means 26 and generate a control signal to control the pump 25. The control means 27 is configured and programmed to control the pump 25 so that the pressure difference upstream and downstream of the pump 25 and the Coriolis flow meter 24 is zero or close to zero.

  The control means 27 is also configured to automatically control the degree of opening and closing of the flow rate control valve 28 connected to the liquid supply pipe 23 at a position downstream of the downstream measuring unit 35 (reference numeral 37 is a signal line). Shown).

  In the above configuration, during the operation of the flow measurement / flow control device 21, the discharge amount of the pump 25 is controlled so that the pressure difference between the upstream and downstream of the pump 25 and the Coriolis flow meter 24 becomes zero or approaches zero. Thereby, it becomes possible to make the Coriolis flow meter 24 that does not appear to have a differential pressure (pressure loss). Since the Coriolis flowmeter 24 apparently has no pressure loss, the filling liquid (fluid) flows to the downstream flow rate control valve 28 at a predetermined flow rate.

  It can be seen that it is useful to install the flow rate measurement / flow rate control device 21 in a facility that is a highly viscous fluid and does not have a sufficient head (liquid feeding force).

  In addition, it goes without saying that the present invention can be variously modified without departing from the spirit of the present invention.

It is a block diagram which shows one Embodiment of the flow measurement and flow control apparatus which do not give the influence of the pressure loss by the Coriolis flowmeter of this invention. It is a block diagram of the flow volume measuring apparatus of a prior art example.

Explanation of symbols

21 Flow measurement and flow control device (flow measurement / flow control device) without impact of pressure loss by Coriolis flow meter
DESCRIPTION OF SYMBOLS 22 Storage tank 23 Supply pipe 24 Coriolis flow meter 25 Pump 26 Differential pressure measurement means 27 Control means 28 Flow control valve 29 Supply pipe 30 On-off valve 31 Flow tube 32, 33, 36, 37 Signal line 34 Upstream measurement part 35 Downstream Measurement unit

Claims (1)

A Coriolis flow meter,
A pump disposed upstream of the Coriolis flow meter for transporting fluid to the Coriolis flow meter;
Differential pressure measuring means for measuring a differential pressure between a position near the upstream side of the pump and a position near the downstream side of the Coriolis flow meter,
The Coriolis flowmeter, the pump, and the differential pressure measuring means are electrically connected, and a control means is provided for controlling the discharge amount of the pump so that the differential pressure is zero or close to zero. Flow measurement and flow control device that does not affect the pressure loss due to the flow meter.

Images