Measuring system for a medium flowing in a process line

• US 20090217771A1
• Filed: 12/30/2008
• Published: 09/03/2009
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Original Assignee: Endress+Hauser Flowtec AG (Endress+Hauser AG)
• Inventors: Hoecker, Rainer
• Granted Patent: US 7,882,751 B2
• Time in Patent Office: Days
• US Class Current: 73/861.220
• CPC Class Codes: G01F 1/3209 using Karman vortices
• CPC Class Codes: G01F 15/185 Connecting means, e.g. bypass conduits

Abstract

The measuring system is inserted into the course of a process line and serves for registering at least one measured variable of a medium flowing in the process line. The measuring system includes for such purpose a measuring transducer having a measuring tube serving for conveying medium being measured and a sensor arrangement, which has at least one sensor element reacting primarily to the measured variable to be registered, and which delivers by means of at least one sensor element at least one measurement signal influenced by the measured variable. Further, the measuring system includes a measuring electronics communicating with the measuring transducer and using the at least one measurement signal for producing, at least at times, at least one measured value instantaneously representing the measured variable.

The measuring tube has, in the case of the measuring system of the invention, a smaller flow cross section than a supply segment of the process line connected to the inlet end of the measuring system. The measuring system further includes a flow conditioner arranged at the inlet end of the measuring tube and mediating between the measuring tube and the supply segment of the process line. The flow conditioner has a lumen tapering in the direction of the measuring tube. During operation, medium flows through the lumen of the flow conditioner. The flow conditioner includes at least two inner edges arranged upstream of its outlet end and protruding into the lumen of the flow conditioner. During operation, medium conveyed within the flow conditioner flows against each of the inner edges. Between the first inner edge and the second inner edge, there extends, additionally, a first guide surface of the flow conditioner. Moreover, the second inner edge bounds a second guide surface of the flow conditioner extending in the direction of the outlet end of the flow conditioner and serving for guiding medium flowing in the flow conditioner.

Claims

1. A measuring system inserted into the course of a process line for registeri at least one measured variable of a medium flowing in the process line, said measuring system comprising:

a measuring transducer, including a measuring tube which serves for conveying the medium to be measured and which shows a smaller flow cross section than a supply segment of the process line connected to an inlet of the measuring system;

a sensor arrangement which includes at least one sensor element reacting primarily to said variable to be registered and/or reacting primarily to changes of said variable to be registered, and provides, by means of the at least one sensor element, at least one measurement signal influenced by the measured variable; and

a measuring electronics communicating with the measuring transducer and producing, taking into consideration the at least one measurement signal, at least one measured value instantaneously representing the measured variable; and

a flow conditioner arranged at an inlet of the measuring tube, said flow conditioner mediating between the measuring tube and the supply segment of the process line, and said flow conditioner showing a lumen which tapers toward the measuring tube, and through which medium flows during operation, an inlet end of said flow conditioner, facing the supply segment of the process line, shows a flow cross section which is greater than the flow cross section of the measuring tube, and an outlet end of the flow conditioner, facing toward the measuring tube, shows a flow cross section which is smaller than the flow cross section of the inlet end of the flow conditioner;

wherein;

the flow conditioner includes, arranged upstream of its outlet end, at least a first inner edge protruding into the lumen of the flow conditioner and against which medium conveyed in the flow conditioner flows during operation, and the flow conditioner includes, arranged downstream from the first inner edge, at least a second inner edge likewise protruding into the lumen of the flow conditioner and against which medium conveyed in the flow conditioner flows during operation, and the flow conditioner includes a first guide surface serving to guide medium flowing in the flow conditioner and a second guide surface serving to guide medium flowing in the flow conditioner, said first guide surface extending between the first inner edge and the second inner edge, and said second guide surface extending from the second inner edge in the direction of the outlet end of the flow conditioner.

2. The measuring system as claimed in claim 1, wherein each of the first and second inner edges protruding into the lumen of the flow conditioner has an edge radius smaller than 2 mm, especially smaller than 0.6 mm;

and/or

wherein a cross section ratio, defined by a ratio of the flow cross section of the supply segment of the process line to the flow cross section of the measuring tube, is kept greater than 1.5 and/or smaller than 10, especially in a range between 1.66 and 9.6.

3. The measuring system as claimed in claim 1, wherein a cross section of the lumen of the flow conditioner bounded by one of the first and second inner edges is smaller than the flow cross section of the supply segment of the process line.

4. The measuring system as claimed in claim 3, wherein a constriction ratio, defined by a ratio of a cross section bounded by the first inner edge to the flow cross section of the supply segment of the process line, is kept smaller than 0.9 and/or greater than 0.1, especially in a range between 0.25 and 0.85;

and/or

wherein a contraction ratio, defined by a ratio of the cross section bounded by the first inner edge to the flow cross section of the measuring tube, is kept greater than 1.2 and/or smaller than 5, especially in a range between 1.3 and 3.

5. The measuring system as claimed in claim 1, wherein a cross section ratio, defined by a ratio of the flow cross section of the supply segment of the process line to the flow cross section of the measuring tube, is kept greater than 1.5 and/or smaller than 10, especially in a range between 1.66 and 9.6, and a constriction ratio, defined by a ratio of a cross section bounded by the first inner edge to the flow cross section of the supply segment of the process line, is kept smaller than 0.9 and/or greater than 0.1, especially in a range between 0.25 and 0.85, and

wherein a difference between said cross section ratio and the said constriction ratio is kept greater than 0.5 and/or smaller than 10, especially in a range between 0.83 and 9.5.

6. The measuring system as claimed in claim 1, wherein a cross section ratio, defined by a ratio of the flow cross section of the supply segment of the process line to the flow cross section of the measuring tube, is kept greater than 1.5 and/or smaller than 10, especially in a range between 1.66 and 9.6, and a contraction ratio, defined by a ratio of the cross section bounded by the first inner edge to the flow cross section of the measuring tube, is kept greater than 1.2 and/or smaller than 5, especially in a range between 1.3 and 3, and

wherein a difference between said cross section ratio and said contraction ratio is kept greater than 0.2 and/or smaller than 10, especially in a range between 0.25 and 8.

7. The measuring system as claimed in claim 1, wherein the measuring tube shows a smaller caliber than a supply segment of the process line attached to the inlet end of the measuring system.

8. The measuring system as claimed in claim 7, wherein the inlet end of the flow conditioner facing the supply segment of the process line shows a caliber greater than a caliber of the measuring tube, and the outlet end of the flow conditioner facing the measuring tube shows a caliber smaller than the caliber of the inlet end of the flow conditioner;

and/or

wherein the first inner edge protruding into the lumen of the flow conditioner is formed by keeping the inner diameter of the inlet end of the flow conditioner smaller than the caliber of the supply segment of the process line; and

/or

wherein a cross section of the lumen of the flow conditioner bounded by the first inner edge protruding into the lumen of the flow conditioner shows a diameter, which is smaller than the caliber of the supply segment of the process line; and

/or

wherein a caliber ratio, defined by a ratio of the caliber of the supply segment of the process line to the caliber of the measuring tube, is kept greater than 1.1 and/or smaller than 5, especially in a range between 1.2 and 3.1.

9. The measuring system as claimed in claim 1, wherein the measuring tube shows an installed length, which is greater than an installed length of the flow conditioner, so that an installed length ratio, defined by a ratio of the installed length of the flow conditioner to the installed length of the measuring tube, is kept smaller than one.

10. The measuring system as claimed in claim 9, wherein the measuring tube shows a smaller caliber than a supply segment of the process line attached to the inlet end of the measuring system, and wherein a caliber ratio, defined by a ratio of the caliber of the supply segment of the process line to the caliber of the measuring tube, corresponds to at least 10% of the installed length ratio of the installed length of the flow conditioner to the installed length of the measuring tube.

11. The measuring system as claimed in claim 1, wherein the at least one sensor element, especially a sensor element immersed in the medium during operation, is arranged at a distance from the inlet end of the measuring tube in and/or on, especially directly on, the measuring tube.

12. The measuring system as claimed in claim 11, wherein the measuring tube shows a smaller caliber than a supply segment of the process line attached to the inlet end of the measuring system, and wherein the at least one sensor element is so placed that a ratio of the distance to the caliber of the measuring tube is kept greater than one.

13. The measuring system as claimed in claim 1, wherein the first inner edge of the flow conditioner limits an impingement surface of the flow conditioner arranged in a border region of the flow conditioner, especially an annular border region.

14. The measuring system as claimed in claim 13, wherein the impingement surface is so arranged and so oriented in the flow conditioner that it is at least sectionally essentially perpendicular to a longitudinal axis of the flow conditioner and/or that it is sectionally essentially perpendicular to a longitudinal axis of the measuring tube;

and/or

wherein the impingement surface has a height in the radial direction of at least 1 mm; and

/or

wherein the impingement surface is an annular surface; and

/or

wherein the impingement surface and the first inner edge are, at least in part, formed by a shoulder formed in the inlet of the flow conditioner, especially a circular and/or self-closing shoulder; and

/or

wherein the impingement surface is at least sectionally essentially planar; and

/or

wherein the impingement surface is so arranged and oriented in the flow conditioner that it is sectionally essentially coplanar with a cross section of the flow conditioner and/or sectionally essentially coplanar with a cross section of the measuring tube; and

/or

15. The measuring system as claimed in claim 13, wherein the impingement surface is at least sectionally essentially conical;

and/or

wherein the impingement surface tapers toward the measuring tube; and

/or

wherein the impingement surface widens towards the inlet end of the flow conditioner; and

/or

wherein the impingement surface and the first inner edge are formed at least partially by an inner cone formed into the inlet in the flow conditioner, especially an inner cone extending to the inlet end of the flow conditioner and tapering toward the measuring tube.

16. The measuring system as claimed in claim 13, wherein the impingement surface and the first inner edge are formed at least partially by an inner cone formed into the inlet in the flow conditioner, especially an inner cone extending to the inlet end of the flow conditioner and tapering toward the measuring tube and wherein the inner cone forming the impingement surface shows a flank angle greater than 45°

, especially greater than 60°

, and/or smaller than 90°

, especially smaller than 88°

.

17. The measuring system as claimed in claim 1, wherein the first guide surface is formed concavely, especially predominantly or entirely concavely, with reference to a longitudinal axis of the flow conditioner;

and/or

wherein the second guide surface of the flow conditioner, especially the conically formed, second guide surface, is formed convexly, at least sectionally, with reference to a longitudinal axis of the flow conditioner; and

/or

wherein the second guide surface of the flow conditioner, especially the conically formed, second guide surface, is, at least sectionally, concavely formed; and

/or

wherein the second guide surface of the flow conditioner tapers toward the measuring tube; and

/or

wherein the second guide surface of the flow conditioner is formed essentially conically.

18. The measuring system as claimed in claim 1, wherein the second guide surface and the second inner edge are formed, at least in part, by an inner cone formed in the inlet of the flow conditioner, especially an inner cone extending toward the outlet end of the flow conditioner.

19. The measuring system as claimed in claim 18, wherein the inner cone forming the second guide surface of the flow conditioner shows a flank angle greater than 2°

, especially greater than 4°

, and/or smaller than 45°

, especially smaller than 10°

.

20. The measuring system as claimed in claim 13, wherein the impingement surface is formed by a first inner cone formed into the inlet of the flow conditioner and extending toward its inlet end, and the second guide surface is formed by a second inner cone formed into the inlet of the flow conditioner and extending toward its outlet end.

21. The measuring system as claimed in claim 20, wherein the first inner cone forming the impingement surface shows a flank angle which is greater than a flank angle of the second inner cone forming the second guide surface;

and/or

wherein the first inner cone forming the impingement surface of the flow conditioner shows a flank angle greater than 45°

, especially greater than 60°

, and smaller than 90°

, especially smaller than 88°

; and

/or

wherein the second inner cone forming the second guide surface of the flow conditioner shows a flank angle greater than 2°

, especially greater than 4°

, and smaller than 45°

, especially smaller than 10°

.

22. The measuring system as claimed in claim 1, wherein the at least one sensor element comprises at least one piezoelectric element and/or at least one piezoresistive element;

and/or

wherein the at least one sensor element comprises at least one solenoidal coil corresponding with an armature; and

/or

wherein the at least one sensor element comprises at least one measuring electrode contacting medium flowing in the measuring tube and sensing electric potentials; and

/or

wherein the at least one sensor element comprises at least one measuring capacitor reacting to changes of the measured variable; and

/or

wherein the at least one sensor element comprises at least one electrical resistor; and

/or

wherein the at least one sensor element is subjected during operation repeatedly to mechanical deformations influenced by the medium flowing in the measuring tube; and

/or

wherein the at least one sensor element is moved during operation repeatedly relative to a static, rest position under influence of medium flowing in the measuring tube.

23. The measuring system as claimed in claim 1, wherein the measuring transducer comprises at least one bluff body arranged in the measuring tube.

24. The measuring system as claimed in claim 23, wherein the at least one sensor element of the sensor arrangement, especially a sensor element protruding at least partially into the measuring tube, is arranged downstream from the at least one bluff body.

25. The measuring system as claimed in claim 1, wherein the measuring transducer is selected from a transducer group consisting of vortex flow transducer, especially a vortex-street, flow transducer, magneto-inductive flow transducer, flow transducer of vibration-type, especially a Coriolis mass flow transducer, a density transducer and/or a viscosity transducer, and an ultrasonic flow transducer.

26. The measuring system as claimed in claim 1, wherein the measured variable is selected from a group consisting of:

a mass flow, a volume flow, a flow velocity, a density, a viscosity, a pressure, a temperature, and/or the like;

and/or wherein the at least one measured value produced by the measuring electronics is selected from a group consisting of;

a mass flow measured value, a volume flow measured value, a density measured value, a viscosity measured value, a pressure measured value, a temperature measured value.

27. The measuring system as claimed in claim 1, wherein a cross section of the lumen of the flow conditioner bounded by the first inner edge protruding into the lumen of the flow conditioner is greater than a cross section of the lumen of the flow conditioner bounded by the second inner edge protruding into the lumen of the flow conditioner;

and/or

wherein a cross section of the lumen of the flow conditioner bounded by a second inner edge protruding into the lumen of the flow conditioner is smaller than the flow cross section of the supply segment of the process line, especially smaller than the flow cross section of the inlet end of the flow conditioner; and

/or

wherein a constriction ratio, defined by a cross section of the lumen of the flow conditioner bounded by the second inner edge to the flow cross section of the supply segment of the process line, is kept smaller than 0.9 and/or greater than 0.1, especially in a range between 0.19 and 0.78; and

/or

wherein a contraction ratio, defined by a ratio of the cross section bounded by the second inner edge to the flow cross section of the measuring tube, is kept greater than 0.9 and/or smaller than 5, especially in a range between 0.9 and 2.5.

28. The measuring system as claimed in claim 1, wherein a cross section ratio, defined by a ratio of the flow cross section of the supply segment of the process line to the flow cross section of the measuring tube, is kept greater than 1.5 and/or smaller than 10, especially in a range between 1.66 and 9.6, and a contraction ratio, defined by a ratio of the cross section bounded by the second inner edge to the flow cross section of the measuring tube, is kept greater than 0.9 and/or smaller than 5, especially in a range between 0.9 and 2.5, and

wherein a difference between said cross section ratio and said contraction ratio is kept greater than 0.2 and/or smaller than 10, especially in a range between 0.4 and 8.

29. The measuring system as claimed in claim 1, wherein each of the first and second inner edges protruding into the lumen of the flow conditioner is so formed and so arranged in the flow conditioner, that it is oriented essentially transversely to a longitudinal axis of the flow conditioner and/or transversely to a longitudinal axis of the measuring tube;

and/or

wherein each of the inner edges protruding into the lumen of the flow conditioner extends circumferentially, especially circularly, around the flow conditioner and, as a result, closes on itself; and

/or

wherein the first inner edge protruding into the lumen of the flow conditioner is arranged in the vicinity, especially the immediate vicinity, of the inlet end of the flow conditioner; and

/or

wherein the first guide surface is essentially strongly concavely formed at least sectionally with respect to a longitudinal axis of the flow conditioner; and

/or

wherein the second guide surface is essentially convex; and

/or

wherein the first inner edge extends circumferentially along a directrix of the flow conditioner; and

/or

wherein the first inner edge is circular; and

/or

wherein the second inner edge extends circumferentially along a directrix of the flow conditioner; and

/or

wherein the second inner edge is circular.

30. The measuring system as claimed in claim 1, wherein the flow conditioner is formed essentially circular-cylindrically, at least in an inlet region;

and/or

wherein the measuring tube is formed essentially circular-cylindrically, at least in an inlet region; and

/or

wherein the flow conditioner is formed essentially circular-cylindrically, at least in an outlet region; and

/or

wherein the measuring tube, especially the circular-cylindrical measuring tube, is essentially straight; and

/or

wherein the process line is embodied as a pipeline; and

/or

wherein the first guide surface is formed, at least partially, by a furrow or groove, especially a circular and/or circumferential furrow or groove, formed in the flow conditioner; and

/or

wherein the first guide surface is formed by an annular groove formed in the flow conditioner; and

/or

wherein the first guide surface is formed by an inner cone formed in the flow conditioner; and

/or

wherein the first inner edge protruding into the lumen of the flow conditioner is located immediately at the inlet end of the flow conditioner; and

/or

wherein the second inner edge bounds a second guide surface.

31. The use of a measuring system as claimed in claim 1 for registering at least one measured variable, especially a mass flow, a volume flow, a flow velocity, a density, a viscosity, a pressure, a temperature and/or the like, of a medium flowing in the process line.

32. A method for registering at least one measured variable, especially a mass flow, a volume flow, a flow velocity, a density, a viscosity, a pressure, a temperature, and/or the like, of a medium flowing in a process line, by means of a measuring system inserted into the course of the process line and having a flow conditioner connected to a supply segment of the process line, as well as a measuring transducer connected to the flow conditioner, which method includes the following steps:

allowing medium to be measured to flow out of the supply segment into the flow conditioner;

accelerating the flowing medium in the direction of a longitudinal axis of the flow conditioner;

inducing at least one essentially stationary, especially also essentially locationally fixed, toroidal vortex within medium flowing in an inlet region of the flow conditioner in a manner such that a principal axis of greatest inertia of the at least one toroidal vortex essentially coincides with the longitudinal axis of the flow conditioner, and/or a longitudinal axis of the measuring tube;

allowing the medium being measured to flow past the at least one toroidal vortex; and

allowing the medium being measured to flow out of the flow conditioner into a measuring tube of the connected measuring transducer, as well as producing at least one measurement signal influenced by the measured variable to be registered, by application of at least one sensor element reacting primarily to the measured variable, especially also to changes in the same,

wherein the step of inducing the at least one, essentially stationary, toroidal vortex in the inlet region of the flow conditioner includes steps of allowing medium to flow past a first inner edge of the flow conditioner protruding into a lumen of the flow conditioner, especially a first inner edge extending on a closed path along a directrix of the flow conditioner, as well as allowing medium to flow past a second inner edge of the flow conditioner located downstream from the first inner edge and protruding into a lumen of the flow conditioner, especially a second inner edge extending on a closed path along a directrix of the flow conditioner.

33. The method as claimed in claim 32, further comprising a step of inducing at least one further, essentially stationary, especially essentially locationally fixed, toroidal vortex in the inlet region of the flow conditioner in such a manner that a principal axis of greatest inertia of each of the at least two toroidal vortices extends essentially parallel with one another and, at least when imaginary axially extended, essentially coincides with the other.

34. The method as claimed in claim 33, further comprising steps of allowing medium to flow against an impingement surface of the flow conditioner opposing flowing medium in a boundary region of the flow conditioner, especially a boundary region circumferentially closed along a directrix of the flow conditioner, for inducing essentially stationary, toroidal vortices in the inlet region of the flow conditioner.