FI119784B - Device for measuring and controlling flow rate - Google Patents

Description

FLOW VOLUME MEASUREMENT AND CONTROL DEVICE

The invention relates to a device for measuring and regulating a flow rate for controlling a volume of a pressurized pipe flow, such as a metering or discharge from a pipe, with a flow pressure greater than that of the outlet on the inlet side.

It is previously known to control a valve in a pipeline for controlling the flow of fluids in a pipe, the opening of which is adjusted as necessary. The pressure of the flow to the valve is greater than the pressure exiting the valve. Adjustment is done manually or with a motor-driven actuator. The flow rate is not usually known from the valve position, but a flow meter needs to be added to the pipeline. The control valve and flow meter are connected to a control and control unit which automatically controls the valve and maintains the flow at the desired value.

Process industries, such as the paper industry, have high solids-liquid mixtures that are difficult to adjust for small tubes and valves. In the paper industry, the purification of pulps is aimed at recovering all useful fibers. It follows that the reject stream of the final purification step of the process is controlled. · J *. outflow from the process is kept as low as possible so that it contains a large amount of impurities. The small flow, together with the impurities, causes the following: * * *; some adjustment problem. Small diameter control valves less than 50 mm in diameter • · · •; · · · Become clogged with impurities when the valve has to be partially maintained due to adjustment:: open. An attempt has been made to solve this problem by a periodic control in which the valve is either closed or open. By changing the closed / opening hours ratio, the desired impurities are removed from the process. Intermittent operation often causes interference at the beginning of the line. · M · head process steps.

• · · • • • • • ·: * ·. · To eliminate the drawbacks described above, a new flow measurement and control device has been developed to achieve a substantial improvement over the valves currently in use.

The invention is characterized in that the actuator is a type of constant displacement • • .... priming pump and that the rotary actuator is a sensor for flow measurement and the flow rate is obtainable from the amount of rotation of the actuator.

2

An advantage of the flow measuring and controlling device according to the invention is that the mechanical rotating pump accurately transmits a certain constant amount of flow through the pump at each revolution, regardless of the mass or solids content of the flow. In this case, the measured or controlled rotation amount of the pump can be converted in a simple manner into a flow rate. Although the pump inlet side has an unusually higher flow pressure relative to pump drives than the outlet side, a motor driven by the pump, for example, controlled by a frequency converter, does not allow the pump speed to rise from the set value. Flow pressure fluctuations do not affect the flow control, as in the case of a valve with flow control.

The invention will now be explained in more detail with reference to the accompanying drawing, in which Figure 1 schematically illustrates a known flow control by means of a valve. Figure 2 is a side elevational view of the flow control device according to the invention and partially cut away.

Figure 1 shows a known pipe flow control by means of valve 1.

The valve 1 is controlled by the control from the control device 3 according to the flow desired through the valve 1. The flow meter 2 retrieves the respective flow rate and transmits this information to the control device 3. When the fluid contains a solid or other flowing mass, the variable orifice valve 1 is not very reliable. .

Fig. 2 shows a flow 5 for the regulator and an outlet 6 for the regulator, respectively. The pressure of the incoming flow 5 is higher than the flow of the outflow 6, as is also the case in Fig. 1. · · • · ·. · · ·. case. According to the invention, the impeller 4, used in the pumps, and the pump body 7, and the impeller 4, are connected to a rotator for controlling the flow. . engine. Conventional soldering pumps can advantageously be used for flow control • · ·. * * *. because they have the property of having a constant displacement volume per revolution of the impeller.

• · ·]. When the impeller 4 is driven via an electric frequency converter and the drive is controlled by a control system, the rotation speed of the impeller 4 is constantly controlled and consequently the flow rate in pipe 5, 6 is accurately known without flow measurement.

• · ”*. The impeller 4 also acts as a sensor for flow measurement.

• · · • · · · · 3

Fig. 2 shows, as an example, a rubber impeller pump 7 whose rotation is controlled. The pump replaces the control valve and is an inexpensive control device for controlling small contaminated flows. The adjusted flow is smooth and does not interfere with any other process. With the impeller 4 rotating very slowly, the flow may be almost zero. When the pump passages are relatively large, impurities can flow through it without blocking the pump.

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Claims (2)

1. A device for measuring and controlling the flow rate of a pressurized pipe flow, such as a metering or discharge from said inlet pipe, with an inflow pressure greater than the outlet side, said regulator being a rotatable motor-driven pump (7) of known rotational speed, that the regulator (7) is a constant volume per revolution pumping brazing pump and that the rotary regulator (7) is a flow measurement sensor and the flow rate is obtainable from the rotation rate of the regulator (7). A flow rate measuring and control device according to claim 1, characterized in that the motor speed control is tracked by a frequency converter. 1. Mät- och regleringsapparat för strömningsmängd, I am wearing apparat reglerar games i en trycklig rörströmning, liksom dosering eller utmatning som handler frän et rör och som är monterbar i so strömningsrör och att trørkning rørstörrning, pump (7) stem motor kan regleras av sin rotationshastighet, kännetecknad därav, att regleringsapparaten ei av • · · ...: then typ en förträngningspump som pumpar constant volym per ett varv och att den rote- • ·. · · ·. rande regleringsapparaten (7) and som g en givare för strömningsmätningen och strömnings- • · • · · ....: play can fis frän varvtalet av regleringsapparaten (7). • · · • · · · ·. ***; 2. Mät-och regleringsapparat för strömningsmängd, kännetecknad därav, att regie- ·· · ringen av motoms rotationshastighet är anordnad med hjälp av en frekvenstransforma-Tor. · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · ·