GB2527324A

GB2527324A - Segmented electromagnetic sensor

Info

Publication number: GB2527324A
Application number: GB1410824.5A
Authority: GB
Inventors: Andrew Hunt
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-06-18
Filing date: 2014-06-18
Publication date: 2015-12-23
Anticipated expiration: 2034-06-18
Also published as: GB2527324B; GB201410824D0

Abstract

An electromagnetic sensing device for measuring properties of a material flowing in a pipe / conduit wherein the sensing device is formed from a number of segments mounted around or within the pipe / conduit where each segment contains a sensing element. Each of the segments are in the form of a frame that may be physically separated from each other allowing the segments to be assembled in any combination whilst ensuring that the relevant sensor element is placed at the relevant part of the circumference of the pipe; and allow the sensing device to be mounted in a wider variety of positions. When fixed together in operation the segments cover substantially the entire circumference of the pipe or conduit over the length necessary for the performance of the measurement, and provides tomographic images of the material flowing in a pipe/conduit. The sensing element may be any type of electromagnetic sensor, and may be a sensor that is mounted, printed or etched onto a flexible membrane 40. The surface of the segment touching the pipe may be lined with a flexible material or shaped to divert water away from the measuring zone.

Description

i PATENT SPECIFICATION

3 TITLE: Segmented Electromagnetic Sensor

4 DESCRIPTION

S

6 The present invention relates to an apparatus for measuring the flow of one or more 7 materials flowing through a pipe or conduit, where the flowing material may consist 8 of one fluid flowing alone (known as single-phase flow'), or a mixture of two or more 9 fluids flowing together, such as water, oil or gas in various combinations. These mixtures of fluids may also contain one or more distributed solids. All mixtures of 11 more than one fluid with or without solids are known as multiphase flows'. The 12 present invention may be useful in improving the accuracy of measurement of single- 13 phase flow or multiphase flow and may reduce the manufacturing costs of instruments 14 designed to measure single-phase flowrates or multiphase flowrates. The invention IS may also enable the measurement of flow through a closed conduit, where there is no 16 direct access to the flowing materials, an application known as clamp-on' metering.

18 The present invention is designed to be appropriate for use in many industries 19 including, without limitation, food and agriculture, minerals and mining, oil and gas production and processing, energy generation and any other industry requiring the 21 measurement of materials flowing in pipes.

23 Electromagnetic sensors for flow metering are frequently manufactured by mounting 24 electrodes around the outside of a pipe. One example is the measurement system described by patent GB 2390883 B wherein conducting &ements are placed around 26 the pipe or within the pipe body as a set of curved metal plates, see Figure 1 27 reproduced from Figure 4 of that patent. The set of curved electrodes 7 shown in 28 cross section may be mounted inside, outside or within a non-conducting liner 8, the 29 whole being surrounded by a layer 10 to protect and shield the sensor elements, The layer 10 may optionally be formed from the pipe or conduit containing the flow.

I The requirement for multi-plane sensors means that these electrodes around the pipe, 2 acting as sensing elements, may be arranged in linear arrays with repeating sets of 3 electrodes along the pipe arranged in a rectangular array that is wrapped around the 4 pipe as shown in Figure 2, also reproduced from GB 2390883 B. Electrodes 11 are S used as the sensing elements while electrodes 12 and 13 are held at certain voltages to 6 modifz the extent or magnitude of the elecific field.

8 Electrode arrays may be printed on flexible circuit boards 31 and wrapped and glued 9 onto the pipe or liner 32 as shown in Figure 3.

11 The use of flexible circuit boards for the sensing elements of an electromagnetic 12 sensor has significant advantages for the manufacture of such sensors including good 13 mechanical geometric stability, easy connection through striplines 33 also etched onto 14 mult-layer circuit foil, and good longitudinal and circumferential connection of the earthed areas surrounding the electrodes.

17 There are however substantial disadvantages with this method of making and 18 wrapping the electrode foil around the pipe. These disadvantages include the need to 19 make large expensive etched foils, the inability to change or service individual electrodes or connections and the impossibility of assembling the sensor around an 21 existing pipe.

23 The present invention is designed to be applied to the design and manufacture of 24 electromagnetic sensors in order to correct the substantial disadvantages listed above, leading to lower cost manufacturing of electromagnetic sensors and more flexibility in 26 their deployment and use.

28 The present invention envisages the manufacture of any type of electromagnetic 29 sensor from a set of segmented parts, each of which contains the sensing elements normally required for that part of the circumference of the pipe. Those sensing 31 elements might be electrodes and magnets in the case of an electromagnetic 32 flowmeter such as described in WO 201 1,128656 A]; electrodes in the case of a 33 sensor based on Electrical Capacitance Tomography as described in GB 2390883 B; 34 or coils as in the case of a sensor based on magnetic induction tomography and I described by Hsin-Yu Wei and Manuchehr Soleimani in their scientific paper 2 Hardware and software design for a National Instrument-based magnetic induction 3 tomography system for prospective biomedical applications' published in the journal 4 of Physiological Measurements in 2012 (Physiol. Meas. vol. 33 pages 863-879). It S should be understood that these applications are only examples, the present invention 6 may be useflul for any type of sensor using a set of electromagnetic sensing elements 7 around the circumference of a pipe or conduit.

9 A sensor based on electromagnetic magnetic measurements may have typically between 2 and 24 elements symmetrically distributed around the circumference of the ii pipe or conduit and the present invention can be used to improve the performance and 12 reduce the manufacturing cost of any such sensor. The number of separate segments 13 envisaged is the same as the typical distribution of sensing elements, between 2 and 14 24 although more may be possible.

16 Each of the segments in the present invention may be separated physically from the 17 others during manufacture and assembly but will be easily fixed together for 18 operation. When fixed together in operation the segments cover substantially the 19 entire circumference of the pipe or conduit over the length necessary for the performance of the measurement.

22 Because the segments may be separated one from the other in any combination, the 23 sensor may be assembled around the circumference of an existing pipe. This 24 advantage may enable a sensor to be mounted in a position that would not normally be possible, offering the operator of the flow process substantial advantages over 26 other manufacturing techniques. Typical examples of such clamp-on' applications 27 include subsea oil and gas pipelines, flow in pipes made of food-safe linings, and 28 measurements on existing transparent sight tubes on production or test equipment.

29 When used in the clamp-on' manner, it may be advantageous for the pipe or conduit to be made of a material that is not electrically conducting, but depending on the 31 measurement used this may not be essential.

33 One preferred embodiment of the present invention is shown in the attached figures. n

I Figure 4 shows an example of a flexible membrane 40 where the copper surface has 2 been etched into five rectangular electrodes 41, surrounded by a complete bare copper 3 earth area 42.

In the preferred embodiment the flexible membrane 40 is folded as shown in Figure 5 6 and attached to a rectangular frame constructed from two curved segments 5] and two 7 longitudinal members 52. The curved segments are held to the longitudinal members 8 by screws 53, The flexible membrane is fixed using two non-conducting bars 54 held 9 to the longitudinal members by a set of screws 55. In this way the edges of the flexible membrane 40 which are left as exposed earthing areas as shown in Figure 4 ii are held in intimate conduct with the longitudinal members 53 and a good electrical 12 connection is ensured between the flexible membrane and the frame of the segment.

13 The top of the segment is formed from a curved metal sheet 56, this sheet is in direct 14 electrical contact with the longitudinal members and also may be in direct contact with the earther outer area of the flexible membrane, 17 In order for the segment to operate correctly in use each of the component members 18 of the segment, excluding the non-conducting bars 54, may need to be electrically 19 conducting and may need to have an appropriate electrically conducting finish, coating or surface preparation.

22 The segments are independently manufactured, but as they are of a common design 23 this may enable low cost manufacturing through increased volumes of identical 24 components. When the senor is assembled it is envisaged that the sensing elements on the flexible membrane 40 are linked to connectors 57 so that the sensing elements 26 may be interrogated or otherwise communicated with as a set in order to make the 27 required measurement.

29 Although the sensing elements are assembled in a set of similar segments, it is envisaged that a typical electromagnetic sensor made in this way would have a 31 separate, possibly unique set of measurement and/or drive electronics or other 32 common control and measurement system, the whole forming an instrument capable 33 of measuring the flow of material flowing within the pipe or conduit. n

I A typical assembled sensor built according to the preferred embodiment of the current 2 invention is shown in Figure 6. This example is made from eight segments, the 8 3 flexible membranes 40 form the internal surface of the sensor while the 8 metal plates 4 56 form the outer circumference of the sensor.

6 In the event that the sensor is assembled around the outside of a pipe or conduit the 7 internal surface 61 is fitted in contact with the external surface of the pipe or conduit, 8 while if the sensor is to be mounted within a pipe or conduit the outer surface 62 is in 9 contact with the inner surface of the pipe while the inner surface 61 is in direct contact with the material flowing in the pipe.

12 Optionally the inner surface of the sensor 61 may be lined with a flexible or rigid 13 lining material between the flexible membrane and the pipe or flowing material.

When used as a clamp-on' measurement under water, it is advantageous for the curve 16 of the segment touching the pipe to be formed from, or lined with, a flexible material 17 shaped so as to divert the water away from the measurement zone into the area of the 18 earthed edges of the segment along the longitudinal members 52.