GB2089049A

GB2089049A - Gaseous-liquid dual-phase fluid flow measurement

Info

Publication number: GB2089049A
Application number: GB8126808A
Authority: GB
Original assignee: Orion Machinery Co Ltd
Current assignee: Orion Machinery Co Ltd
Priority date: 1980-11-19
Filing date: 1981-09-04
Publication date: 1982-06-16
Also published as: JPS5786717A; DE3136763A1; FR2494433A1; DK511781A

Abstract

Apparatus for measuring the flow of the gaseous and liquid phases of a dual-phase mixed fluid comprises a separation chamber 2 arranged above a liquid flow measuring chamber 3. This comprises a measuring cylinder 10 having slit-like openings 11 and a float 12 which indicates via switches 14 the liquid level and hence the flow rate. The separated fluids are re-mixed before discharge from outlet 15. The gaseous flow rate is measured with meter 17. <IMAGE>

Description

SPECIFICATION Gaseous-liquid dual-phase fluid flow measurement The present invention relates to a method of measuring quantity of flow of gaseous-liquid dualphase mixed fluid and a device to be used for such measurement, and more particularly relates io a method in which the mixed fluid is separated into gaseous-phase fluid and liquid-phase fluid so that quantity of each fluid is measured.

Various conventional methods of measuring one or each constituent of compound fluid in which gaseous-phase fluid and liquid-phase fluid are mixed, can be roughly grouped into two methods, namely a method of measuring each fluid by separating the two constituents and a method of measuring each quantity of flow from the mixed or compound fluid as it is. In the latter method measuring devices are often complicated, requiring precision manufacture of their various components and thus these devices were relatively expensive. In other cases there were problems that measuring errors were too large and it was difficult to put the devices into actual use. The present invention belongs to the first method of separating the fluid and then measuring each constituent so as to avoid disadvantages of the other method of measuring the compound fluid as mentioned above.

Among the conventional methods of measuring quantity of flow by first separating the gaseousliquid dual-phase fluid, the one which utilises a seesaw with a suacer on each side of a fulcrum, is known. In this method a certain quantity of each of the two kinds of liquid separated in the gas-liquid separation chamber, is gathered alternately in the saucers of the seesaw. Then the seesaw is reversed and swung, and quantity of flow of the two kinds or liquid is measured by multiplying the number of times the seesaw is reversed. In this method, however, there was a disadvantage that if the measuring device as a whole is not maintained level, the seesaw would be off-balance, causing measuring errors. This method, thus, was not suitable for a portable device.Moreover, as the shock exerted on the seesaw varied according to the flow quantity dropped on it, errors were again liable to be caused.

It is an object of the present invention to provide a method of separating and measuring gaseous-liquid dual-phase fluid and a device therefor which is economical and easy to transport with few errors caused by tilting of the device, having fewer movable parts, and overcoming the problems of the conventional method of separating and measuring gaseous-liquid dual-phase fluid employing a seesaw mentioned above.

The invention will now be'described, by way of example, with preference to the accompanying drawings in which: Figure 1 is a longitudinal cross-section ofthe measuring device in accordance with the present invention; Figure 2 is a perspective view thereof with a part of its principal elements broken away; Figure 3 is a diagram showing measuring of quantity of flow; and Figure 4 is also a diagram showing measuring of quantity of flow.

A measuring device body 1 is formed with a gasliquid separation chamber 2 in its upper part and a liquid quantity measuring chamber 3 thereunder. An inlet port 4 for gaseous-liquid compound fluid is provided in the gas-liquid separation chamber 2, and separated gas flows out to a gas passage 5 from the upper part of the chamber 2 while separated liquid flows down by its own weight from a liquid outlet pipe 6 to the liquid quantity measuring chamber 3. A floating valve 7 is provided in the separation chamber 2 to open and close the liquid outlet pipe 6.

The valve 7 prevents flowing down of the gas-phase portion and permits the liquid-phase portion to flow down when the valve is raised.

At the centre of the liquid measuring chamber 3 is an overflow cylinder 8 whose upper end is open and whose lower end coincides with the lower wall of the body. The lower end of the liquid outlet pipe 6 which depends from the liquid separation chamber 2 opens into the overflow cylinder 8 so that down-flow of the liquid is gradually decelerated and the liquid flows to the outer periphery of the overflow cylinder 8 from its upper end as well as from an opening 9 formed at its bottom. As the down-flow of the liquid is moderate and slow, and the liquid flows through the overfloe cylinder 8, even the gas which has flowed down still being mixed in the liquid due to insufficient separation, can be separated in the cylinder, and thus precision of measuring the liquid flow is not affected.

Around the outer periphery of the overflowcylin- der8 a measuring cylinder 10 whose upper end is open, is provided concentric with the cylinder 8 at a certain distance from the cylinder 8. A plurality of longitudinal and thin slit-like notched openings 11 are formed in the measuring cylinder 10. Liquid which goes into the measuring cylinder 10 from the overflow cylinder 8, flows outside of the cylinder 10 restrictedly th rough these openings 11 and then flows further out from an outlet formed in the bottom of a side wail of the main body 1. Thus, by suitably selecting the width B and the shape of the openings 11, the quantity of liquid which flows out of these openings can be considered equal to the flow of quantity Q in the weir which, in turn, can be reckoned as a function of the head H.As, in this case, the head H corresponds to that inside the measuring cylinder 10, the quantity of liquid flowing out of the openings 11 can be measured by detecting the liquid level in the measuring cylinder 10.

In order to measure the liquid level in the measuring cylinder 10, a ring-like float 12 which freely moves up and down in accordance with the liquid level, is provided around the outer periphery of the overflow cylinder 8. A magnet 13 is mounted in the float 12, and a plurality of leading switches 14 are provided at a certain interval in the overflow cylinder 8. The liquid level is detected by operating one of the leading switches 14 which corresponds to the position of the float 12.

By providing the openings 11 in the measuring cylinder 10 in many directions symmetrical of the centre, the liquid level in the cylinder can be main tained uniform regardless of tilting of the device, and chances of causing errors in measuring the quantity of flow can be reduced. Further, as both the inside and outside the measuring cylinder 10 are opened at the top so that atmospheric pressure is maintained the same, upsetting of correlation between the liquid level and the quantity of flow in the measuring cylin der 10 due to the difference in atmospheric pressure, is avoided. The bottom of the measuring cylinder 10 and the outlet 15 of the main body 1 are communicated by a narrow tunnel 16 so that a small quantity of flow below a certain quantity of flow is measured.

In other words, when the quantity of flow is small and the liquid level does not reach the lower ends of the openings 11, the float 12 hardly moves. By arranging the leading switches not to be operated, the quantity of flow detected at the abovementioned level can be measured as the small quan tityofflowbelowa certain quantity of flow.

Separated gas which flows in a gas passage 5 is measured by a gas flow meter 17 provided in the middle of the passage, and the measured gas comes together with the liquid to be discharged from the outlet 15.

For the gas flow meter 17, volume-type or pressure-difference-type measuring devices may be used. In case it is not necessary to measure the quantity of gas, provision ofthe gas flow meter 17 may be omitted.

The signal of the liquid level in the measuring cylinder 10 detected by the leading switch 14 and that of the measured valve detected by the gas flow meter 17 are respectively supplied to a suitable circuit 18, and the quantity of flow ofthe liquid and the gas are shown on a suitable indicator 19.

Thus, in the present invention gaseous-liquid compound fluid is separated into gas-phase fluid and liquid-phase fluid. The liquid-phase fluid is led onto a measuring cylinder with slit-like openings so that its quantity of flow is measured by detecting the liquid level in the cylinder, while the gaseous-phase fluid is measured by a gas flow meter. The two kinds of fluid are mixed and discharged after being measured. In this manner continuous measurements is possible and the device can be made more economical. Furthermore, as there are few movable parts, it is easy to maintain and manage the device and keep the rate of trouble occurrences low, while decreasing errors due to tilting of the device. Moreover, as it is not necessary to provide a part to receive the fluid, it is easy to transfer the device.

Claims

1. A method of measuring quantity of flow of gaseous-liquid dual-phase fluid comprising separating gaseous-liquid compound fluid flowing through a passage into gaseous-phase and liquid-phase; leading the liquid-phase into a measuring cylinder in which the quantity of flow through openings and the liquid level are mutually related, measuring the quantity of flow of the liquid by detecting the liquid level; and finally rembing the liquid-phase fluid and the gaseous-phase fluid for discharge to the passage.

2. A method as claimed in Claim 1 in which the quantity of flow of the gaseous-phase fluid is measured before the gaseous-phase fluid and the liquidphase fluid are re-mixed.

3. Adevice for measuring quantity of flow of gaseous-liquid compound fluid comprising a gasliquid separation chamber formed at the top of a liquid quantity measuring chamber in which is disposed a measuring cylinder with openings which maintains a mutual relationship between the quantity of outward flow through said openings and the liquid level; the gas-liquid separation chamber 2 communicating with the measuring cylinder 10 to permit the liquid-phase fluid to be supplied into the said measuring cylinder 10, a liquid level detecting means being provided in the measuring cylinder 10; and means permitting the re-mixing of the liquidphase fluid and the gaseous-phase fluid after measurement has taken place.

4. A measuring device as claimed in Claim 3 in which a gas flow meter is provided in a gas passage of which one end is communicated to the gas-liquid separation chamber and of which the other end is communicated to the liquid quantity measuring chamber 3.

5. A measuring device as claimed in Claim 3 or 4 in which the openings are slit-like and formed in several directions symmetrically of a centre.

6. A method of measuring quantity of flow of gaseous-liquid dual-phase fluid substantially as hereinbefore described.

7. A device for measuring quantity of flow of gaseous-liquid compound fluid substantially as hereinbefore described with reference to the accompanying drawings.