WO2010002432A1

WO2010002432A1 - Insertable ultrasonic meter and method

Info

Publication number: WO2010002432A1
Application number: PCT/US2009/003547
Authority: WO
Inventors: Christopher B. Laird; William R. Freund, Jr.
Original assignee: Cameron International Corporation
Priority date: 2008-07-01
Filing date: 2009-06-13
Publication date: 2010-01-07

Abstract

An ultrasonic flowmeter that is inserted within a pipe through which fluid flows under an internal pipe pressure. The flowmeter includes signal processing unit, a meter body subject to internal pipe pressure and essentially free of any pressure differential from the internal to the external of the pipe having a bore through which fluid in the pipe flows, an upstream and downstream opposing acoustic transducers disposed in the body subject to internal pipe pressure and free of any pressure differential from the internal to the external of the pipe forming at least one acoustic path across the flow stream and in communication with the signal processing unit, and a mechanism for mounting the meter body within the pipe subject to a pressure differential from the internal to the external of the pipe. A method for determining fluid flow with said device.

Description

TITLE OF THE INVENTION Insertable Ultrasonic Meter and Method

FIELD OF THE INVENTION

[0001] The present invention is related to the measurement of fluid flow in a pipe with an ultrasonic flow meter where a meter body is subject to internal pipe pressure but is essentially free of any pressure differential from the internal to the external of the pipe. (As used herein, references to the "present invention" or "invention" relate to exemplary embodiments and not necessarily to every embodiment encompassed by the appended claims.) More specifically, the present invention is related to the measurement of fluid flow in a pipe with an ultrasonic flow meter where a meter body is subject to internal pipe pressure but is essentially free of any pressure differential from the internal to the external of the pipe that utilizes a wire sealing gland through which wiring extends from the internal to the external of the pipe.

BACKGROUND OF THE INVENTION

[0002] This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.

[0003] Conventional ultrasonic flowmeters consist of a meter body and a signal processing unit. The meter body contains acoustic transducers to sense the fluid velocity along at least one path across the fiowstream. The meter body serves not only as a support for the acoustic transducers but also as a pressure vessel to contain the fluid within the pipe and therefore should be designed and constructed of the appropriate materials. In the case where the pipe is flowing petroleum fluids, there are rigid design and manufacturing standards that should be taken into consideration. The mounting of the transducer within the meter body should not only be sealed against the pressure within the pipe but also designed to minimize the amount of sound that bypasses the fluid stream and travels through the meter body to the other transducers. This phenomenon is call "acoustic ring-around" and has detrimental effects on the ability of the meter to perform accurate flow measurement.

[0004] The geometry of the meter body is altered by changes in its temperature.

In order for the meter to precisely measure the flow of fluid, it is desired to account for this geometry change. However, rarely is the meter body at one temperature. It is more likely that there is an unknown temperature gradient from the inside to the outside surfaces of the meter body and that only a rough estimate can be made of its true geometry, particularly, when the fluid temperature is significantly different than the ambient temperature.

[0005] The geometry of the meter body is altered by changes in the fluid pressure.

While these changes can be considered insignificant in many meter body designs when operating at normal pressures, there a cases where the pressure can be several hundred atmospheres which again should be accounted for to achieve precision flow measurement. Due to the complex shape of the meter body, only a rough estimate of the affect of pressure can be made.

[0006] The geometry of the meter body can be altered by stresses within the piping system. This alteration can affect the ability of the meter to perform precise flow measurements. Generally, there is no attempt to account for these geometry changes since it is difficult or impossible to determine the direction and magnitude of these stresses.

[0007] The invention allows for an ultrasonic meter body without the necessity of it being a pressure vessel, thereby providing a simplified meter design. The meter body is free to be made of a wide range of materials including those (for example, plastics) that can be not only economical but that may have desirable acoustic properties, e.g., lower velocities of sound that reduce the undesirable effects of "acoustic ring-around" that occurs with steel meter bodies. The acoustic transducers are immersed in the fluid and therefore do not have to be sealed against the pressure in the pipe thereby simplifying their mounting design. Since the meter body is immersed in the fluid flowing through the pipe, temperature gradients are unlikely allowing for accurate compensation for geometric changes. Because the meter body is not subjected to fluid pressure within the pipe or pipe stresses, these variables have no detrimental effect on the accuracy of the meter.

BRIEF SUMMARY OF THE INVENTION

[0008] The present invention pertains to the measurement of flowing fluid through a pipe. The measurement is performed with a transit time ultrasonic flowmeter having transducers that are disposed in cavities of a flow meter body. The fluid in the pipe flows through a bore of the flow meter body, wherein the flowmeter measures transit times along geometrically defined acoustic paths.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0009] In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:

[0010] Figure 1 is a representation of a full more meter of the present invention.

[0011] Figure 2 is a representation of a reducing nozzle unsearchable meter of the present invention.

[0012] Figure 3 is a representation of an angularly mounted transducer. [0013] Figure 4 is a representation of the field of view of a transducer.

[0014] Figures 5a and 5b is a side view and a perspective view, respectively, of a 6 path transducer arrangement having 4 vertical and 2 horizontal chords.

[0015] Figures 6a and 6b is a side view and a perspective view, respectively, of a

12 path transducer arrangement having 4 vertical and 4 horizontal chords.

[0016] Figure 7 shows a wire sealing gland.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to figure 1 thereof, there is shown an ultrasonic flowmeter (25) that is inserted within a pipe (23) through which fluid flows under an internal pipe (23) pressure. The flowmeter (25) comprises a signal processing unit (11). The flowmeter (25) comprises a meter body subject to internal pipe (23) pressure and essentially free of any pressure differential from the internal to the external of the pipe (23) having a bore (26) through which fluid in the pipe (23) flows. The flowmeter (25) comprises upstream and downstream opposing acoustic transducers (4, 5) disposed in the meter body subject to internal pipe (23) pressure and essentially free of any pressure differential from the internal to the external of the pipe (23) forming at least one acoustic path across the flow stream and in communication with the signal processing unit (11). The flowmeter (25) comprises means for mounting the meter body within the pipe (23) subject to a pressure differential essentially from the internal to the external of the pipe (23).

[0018] The flowmeter (25) can include wiring (24) extending between the transducers and the signal processing unit (11). The meter body can have at least one internal passageway (9) in communication with the transducers (4, 5) in which the wiring (24) is disposed. The mounting means can include means for passing the wiring (24) outside of the pipe (23) to form electrical communication between the signal processing unit (1 1) and the transducers (4, 5).

[0019] The mounting means can include a wafer (1) attached to the pipe (23), and more specifically attached between flanges in the pipe (23). The passing means can include a wire sealing gland (10) attached to the wafer (1) through which the wiring (24) extends. The wafer (1) can have an internal passageway (9) in which the wiring (24) is disposed in communication with the passageway (9) of the meter body.

[0020] The bore (26) can have an inlet in the shape of a nozzle (20) and an outlet in the shape of a pressure recovery cone (21). The transducers (4, 5) can be either flush mounted, or angularly mounted to the bore (26), as shown in figure 3.

[0021] The present invention pertains to an ultrasonic flowmeter (25) that is inserted within a pipe (23) through which fluid flows, as shown in figure 1. The flowmeter (25) comprises a signal processing unit (11). The flowmeter (25) comprises a meter body disposed in the pipe (23) having a bore (26) through which fluid in the pipe (23) flows. The flowmeter (25) comprises upstream and downstream opposing acoustic transducers (4, 5) disposed in the meter body forming at least one acoustic path across the flow stream and in communication with the signal processing unit (11). The transducers are flush mounted to the bore (26). The flowmeter (25) comprises means for mounting the meter body within the pipe (23).

[0022] The present invention pertains to an ultrasonic flowmeter (25) that is inserted within a pipe (23) having an inner diameter through which fluid flows, as shown in figure 1. The flowmeter (25) comprises a signal processing unit (11). The flowmeter

(25) comprises a meter body disposed in the pipe (23) having a bore (26) with an inner diameter through which fluid in the pipe (23) flows. The flowmeter (25) comprises upstream and downstream opposing acoustic transducers (4, 5) disposed in the meter body forming at least one acoustic path across the flow stream and in communication with the signal processing unit (11). The flowmeter (25) comprises means for allowing the bore (26) of the meter body to have a same inner diameter as the inner diameter of the pipe (23). The flowmeter (25) comprises means for mounting the meter body within the pipe (23).

[0023] The allowing means can include concentric pipe reducers (14) disclosed upstream and downstream of the meter body and attached to the pipe (23).

[0024] The present invention pertains to a method for determining fluid flow in a pipe (23) through which the fluid flows under an internal pipe (23) pressure. The method comprises the steps of flowing fluid in the pipe (23) through a bore (26) of a meter body subject to internal pipe (23) pressure and essentially free of any pressure differential from the internal to the external of the pipe (23). There is the step of sampling the fluid in the bore (26) with upstream and downstream opposing ultrasonic acoustic transducers (4, 5) disposed in the meter body subject to internal pipe (23) pressure and essentially free of any pressure differential from the internal and external of the pipe (23) forming at least one acoustic path across the fluid. There is the step of sending signals from at least one of upstream or downstream transducers (4, 5) corresponding to the fluid flow in the bore (26) to a signal processing unit (11) through means for mounting the meter body within the pipe (23) subject to a pressure differential essentially between the internal and external pipe (23) pressure.

[0025] In the operation of the invention, this is a transit time ultrasonic flowmeter

(25) where the arrangement of acoustic transducers (4, 5) are installed into the meter body in the typical fashions to create chordal and/or diametral paths along which the transit times or frequencies of upstream and downstream acoustic signals can be measured as an indication of the volumetric flow of fluid through a pipe (23). The meter body is inserted into the pipe (23) in such a way that insures all fluid passing through the pipe (23) is passed through the meter body. The wiring (24) is channeled from the acoustic transducers through internal passageways (8) to a pressurewithstanding wire sealing gland (10). The meter body is attached to a pressure containing wafer (1) that is mounted between flanges in the pipe (23), thereby eliminating the need for the meter body to withstand the pressure from within the pipe (23).

[0026] Figure 1 shows the arrangement and operation of the meter in the form of a full bore (26) insertable ultrasonic meter (25). In this form, the meter (25) comprises a wafer (1), an upstream meter body (2) and a downstream meter body (3). Meter bodies (2, 3) are attached to the wafer (1). Within one (or both) of the meter bodies are at least one upstream acoustic transducer (4) and one downstream acoustic transducer (5) in such a fashion as to create chordal and/or diametral paths (6) along which the transit times or frequencies of upstream and downstream acoustic signals (7) can be measured as a indication of the volumetric flow of fluid through a pipe (23). The acoustic transducer wires (8) are fed through internal passage ways (9) within the meter housings (2, 3) and wafer (1) until reaching a wire sealing gland (10) and to the outside of the meter where they can be connected to a signal processing unit (11). The wafer (1) is installed between upstream and downstream pipeline reducing sections (12), each consisting of larger sized flanges (13), pipe reducers (14) and smaller sized flanges (15) which are the same size as the pipeline flanges (16). The bore (26) of the meter bodies (2, 3) and the wafer (1) are equal to the inside diameter of the pipeline. The length of the upstream and downstream meter bodies (2, 3) are such that there is a minimum gap (17) between their ends and the pipe reducers (14) so as to minimize the disturbance to the flow stream thereby creating a full bore (26) meter.

[0027] Figure 2 shows the arrangement and operation of the meter in the form of a reducing nozzle insertable meter (25) which is similar to the full bore (26) meter described above except the inside diameter of the wafer (1) and meter body (2) are smaller than that of the adjoining pipe (16). The wafer (1) is shaped so as to funnel the flow into the smaller diameter of the meter body (2) which has proven to improve the transit time flow measurement technique by increasing the Reynolds number and reducing the size of the turbulent features within the flow stream. The downstream end of the meter body (2) is shown as an increasing cone (21) which tends to recover pressure loss across the nozzle (20).

[0028] The apparatus described above can utilize any arrangement of acoustic transducers (4, 5) typically used in transit time ultrasonic flow meters including those that are positioned so that the upstream and downstream transducer point at each other, within a cut-out cavity (22) in the meter body (2, 3). Figures 5a and 5b, and 5c and 5d show two special examples of acoustic transducers (4, 5) arrangements; one forming a 6 path arrangement and one forming a 12 path arrangement, respectively. The transducer in these arrangements is such that the acoustic signals are emitted in a wide wave angle (18), as shown in figure 4, forming a conical shape (19) such that the other upstream or downstream transducer fall within the cone (19). In this way, the number of transducers per acoustic path is minimized and the mounting of the transducer within the meter body can be at right angles to the axis of the meter bore (26), thereby eliminating, or greatly reducing flow turbulence in front of the transducer formed by the cut-out cavity (22) and the corresponding inaccuracies in the measurement of transit times or frequencies.

[0029] The wafer (1) is a pressure containing element and therefore should be constructed of the appropriate material, e.g., carbon steel or stainless steel. The meter bodies (2, 3) are not pressure containing elements and therefore can be constructed of low strength materials, e.g., cast iron or even plastic. The meter body (2, 3) can be attached to the wafer (1 ) by a variety of techniques, e.g., screw fasteners. The acoustic transducers (4, 5) can be immersed in the fluid thereby eliminating pressure boundaries and making the mounting straightforward. One way of mounting the transducers (4, 5) into cavities (22) of the meter body (2, 3) is the use of snap rings. The wire sealing gland (10) is mounted to the wafer (1) and creates a pressure seal using NPT thread, for example.

[0030] In the common ultrasonic meter arrangement (prior art), the meter body, or measuring section is fitted with an arrangement of transducers and is designed to contain the pressure of the fluid within the line. The meter (25) is believed unique in that while the measuring section is fitted with an arrangement of transducers as before, the measuring section does not serve as a pressure vessel. Only the mounting ring (wafer) is needed to contain the pressure. This makes for an arrangement that is inherently easier and less costly to construct.

[0031] Referring to figure 1, notice that the upstream and downstream meter bodies

(2, 3) are attached to wafer (1) which is fitted between flanges in the pipeline. While bodies (2, 3) are under the pressure of the fluid in the pipeline, they do not contain the pressure and therefore are free from the associated stresses. The same can be said of the transducers, i.e., they do not contain the pressure. Line pressure is contained by reducing sections (12), which in the apparatus, are comprised of standard piping components. The ability to allow the measuring section (bodies 2 and 3) to be immersed in the fluid without having to contain the pressure of the fluid, is practically done with the use of the wire sealing gland (10).

[0032] The flush mounted transducers, as shown in figure 1, are mounted perpendicular to the cavity (22), thereby eliminating the traditional cutout, as shown in figure 3, that causes turbulence and corresponding measurement uncertainties. The angular path is created by the wide acoustic beam, as shown in figure 4. In the meter, the transducers are inside of the pipe (23) and therefore are pressurized. This arrangement allows for greater simplicity since there is no need of the traditional pressure containing transducer housing — the pressure boundary is on the transducer wires. An example of a wire sealing gland supplied by Conax Technologies is shown in figure 6.

[0033] The advantages of the invention are as follows.

[0034] Since the meter body is not stressed by the fluid pressure, there is no need to employ algorithms that attempt to correct for the fluid measurement errors caused by bore (26) diameter differences when the operating pressure is different than the calibration pressure. [0035] Since the meter body is immersed in the fluid, there is no thermal gradient across the meter body so that its temperature is essentially the same as the fluid temperature making it possible to accurately employ algorithms to correct for fluid measurement errors caused by bore (26) diameter difference when the operating temperature is different than the calibration temperature.

[0036] This design is inherently less costly to manufacture because the meter body does not have to serve as a pressure vessel and the transducers do not have to contain the pressure of the fluid.

[0037] Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.

Claims

1. An ultrasonic flowmeter that is inserted within a pipe through which fluid flows under an internal pipe pressure comprising:

a signal processing unit;

a meter body subject to internal pipe pressure and essentially free of any pressure differential from the internal to the external of the pipe having a bore through which fluid in the pipe flows;

upstream and downstream opposing acoustic transducers disposed in the meter body subject to internal pipe pressure and essentially free of any pressure differential from the internal to the external of the pipe forming at least one acoustic path across the flow stream and in communication with the signal processing unit; and

means for mounting the meter body within the pipe subject to a pressure differential essentially from the internal to the external of the pipe.

2. A flowmeter as described in claim 1 including wiring extending between the transducers and the signal processing unit.

3. A flowmeter as described in claim 2 wherein the mounting means includes means for passing the wiring outside of the pipe to form electrical communication between the signal processing unit and the transducers.

4. A flowmeter as described in claim 3 wherein the meter body has at least one internal passageway in communication with the transducers in which the wiring is disposed.

5. A flowmeter as described in claim 4 wherein the mounting means includes a wafer attached to the pipe.

6. A flowmeter as described in claim 5 wherein the passing means includes a wire sealing gland attached to the wafer through which the wiring extends.

7. A flowmeter as described in claim 6 wherein the wafer has an internal passageway in which the wiring is disposed in communication with the passageway of the meter body.

8. A flowmeter as described in claim 7 wherein the bore has an inlet in the shape of a nozzle and an outlet in the shape of a pressure recovery cone.

9. A flowmeter as described in claim 8 wherein the transducers are flush mounted to the bore.

10. An ultrasonic flowmeter that is inserted within a pipe through which fluid flows comprising:

a signal processing unit;

a meter body disposed in the pipe having a bore through which fluid in the pipe flows;

upstream and downstream opposing acoustic transducers disposed in the meter body forming at least one acoustic path across the flow stream and in communication with the signal processing unit, the transducers are flush mounted to the bore; and

means for mounting the meter body within the pipe.

11. An ultrasonic flowmeter that is inserted within a pipe having an inner diameter through which fluid flows comprising:

a signal processing unit;

a meter body disposed in the pipe having a bore with an inner diameter through which fluid in the pipe flows;

upstream and downstream opposing acoustic transducers disposed in the meter body forming at least one acoustic path across the flow stream and in communication with the signal processing unit;

means for allowing the bore of the meter body to have a same inner diameter as the inner diameter of the pipe; and

means for mounting the meter body within the pipe.

12. A flowmeter as described in claim 11 wherein the allowing means includes concentric pipe reducers disclosed upstream and downstream of the meter body and attached to the pipe.

13. A method for determining fluid flow in a pipe through which the fluid flows under an internal pipe pressure comprising the steps of:

flowing fluid in the pipe through a bore of a meter body subject to internal pipe pressure and not subject to essentially any pressure differential;

sampling the fluid in the bore with upstream and downstream opposing ultrasonic acoustic transducers disposed in the meter body subject to internal pipe pressure and essentially free of any pressure differential from the internal and the external of the pipe forming at least one acoustic path across the fluid; and

sending signals from at least one of upstream or downstream transducers corresponding to the fluid flow in the bore to a signal processing unit through means for mounting the meter body within the pipe subject to a pressure differential essentially between the internal and external pipe pressure.