Measuring system with a flow conditioner arranged at an inlet of a measuring tube

• US 20100011878A1
• Filed: 09/23/2009
• Published: 01/21/2010
• Est. Priority Date: 07/21/2006
• 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 7,946,186 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 1/86 Indirect mass flowmeters, e.g. measuring volume flow and density, temperature or pressure
• CPC Class Codes: G01F 1/88 with differential-pressure measurement to determine the volume flow
• CPC Class Codes: G01F 15/00 Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
• 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. To this end, 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 one inner edge arranged upstream of its outlet end and protruding into the lumen of the flow conditioner. During operation, medium conveyed in the flow conditioner flows against the inner edge.

Claims

1. Measuring system for registering at least one measured variable of a medium flowing in a process line, said measuring system comprising:

an inlet;

a measuring transducer including a measuring tube and a sensor arrangement with at least one sensor element reacting to the variable to be registered,

said measuring tube serving for conveying the medium to be measured and said measuring tube showing a smaller flow cross section than a supply segment of the process line connected to said inlet of the measuring system,

said measuring transducer providing, by means of the at least one sensor element, at least one measurement signal influenced by the measured variable;

a measuring electronics communicating with the measuring transducer and producing, at least at times, 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 showing a lumen, which tapers toward the measuring tube and through which medium flows during operation,

said flow conditioner including an inlet end facing the supply segment of the process line and showing a flow cross section, which is greater than the flow cross section of the measuring tube,

said flow conditioner including an outlet end facing toward the measuring tube and showing a flow cross section, which is smaller than the flow cross section of the inlet end of the flow conditioner, and

said flow conditioner including, arranged upstream of its outlet end, at least one inner edge, which protrudes into the lumen of the flow conditioner and against which medium, conveyed in the flow conditioner, flows during operation, said inner edge bounding a cross section of the lumen of the flow conditioner, said cross section bound by the inner edge being smaller than the flow cross section of the supply segment of the process line;

wherein;

the at least one inner edge protruding into said lumen of said flow conditioner limits an impingement surface of said flow conditioner arranged in a border region of said flow conditioner, and

the at least one inner edge protruding into said lumen of said flow conditioner limits a guide surface of said flow conditioner extending in the direction of the outlet end of said flow conditioner and serving for guiding medium flowing in said flow conditioner.

2. The measuring system as claimed in claim 1, wherein:

the at least one inner edge protruding into said lumen of said flow conditioner is so formed and so arranged in said flow conditioner, that it is oriented essentially transversely to a longitudinal axis of said flow conditioner; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner is so formed and so arranged in said flow conditioner, that it is oriented essentially transversely to a longitudinal axis of said measuring tube; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner extends circumferentially around said flow conditioner and, as a result, closes on itself; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner is arranged in the vicinity of the inlet end of said flow conditioner; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner is located immediately at the inlet end of said flow conditioner; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner shows an edge radius smaller than 2 mm; and

/or

the at least one inner edge protruding into said lumen of said flow conditioner is formed by keeping the inner diameter of the inlet end of said flow conditioner smaller than the caliber of said supply segment of the process line

3. The measuring system as claimed in claim 1, wherein:

a cross section of said lumen of said flow conditioner bounded by the inner edge protruding into said lumen of said flow conditioner is smaller than the flow cross section of said supply segment of the process line.

4. The measuring system as claimed in claim 1, wherein:

a constriction ratio, defined by a ratio of said cross section bounded by the inner edge to said flow cross section of the supply segment of the process line, is kept smaller than 0.9 and greater than 0.1; and

/or

a cross section ratio, defined by a ratio of said flow cross section of the supply segment of the process line to said flow cross section of the measuring tube, is kept greater than 1.5 and smaller than 10; and

/or

a contraction ratio, defined by a ratio of said cross section bounded by the inner edge to the flow cross section of said measuring tube is kept greater than 1.2 and smaller than 5.

5. 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 said flow conditioner to the installed length of said measuring tube, is kept smaller than one, and/or the measuring tube shows a smaller caliber than said supply segment of the process line attached to the inlet end of said measuring system so that a caliber ratio, defined by a caliber of the caliber of said supply segment of the process line to the caliber of said measuring tube, is kept greater than 1.1 and/or smaller than 5.

6. The measuring system as claimed in claim 1, wherein:

a caliber ratio, defined by a ratio of said caliber of the supply segment of the process line to the caliber of said measuring tube, corresponds to at least 10% of an installed length ratio, defined by an installed length of said flow conditioner to an installed length of said measuring tube.

7. The measuring system as claimed in claim 1, wherein:

a difference between the cross section ratio, defined by a ratio of said cross section bounded by the inner edge to said flow cross section of the supply segment of the process line, and the constriction ratio, defined by a ratio of said flow cross section of the supply segment of the process line to said flow cross section of the measuring tube, is kept greater than 0.5 and/or smaller than 10.

8. The measuring system as claimed in claim 1, wherein:

the measuring transducer comprises a transducer selected from a transducer group consisting of;

a vortex flow transducer, a magneto-inductive flow transducer, a Coriolis mass flow transducer, a density transducer, a viscosity transducer, and an ultrasonic flow transducer.

9. The measuring system as claimed in claim 1, wherein:

the at least one sensor element of the sensor arrangement protrudes at least partially into the measuring tube.

10. The measuring system as claimed in claim 1, wherein:

the inlet end of said flow conditioner facing said supply segment of the process line shows a caliber greater than a caliber of said measuring tube, and the outlet end of said flow conditioner facing said measuring tube shows a caliber smaller than the caliber of the inlet end of said flow conditioner.

11. The measuring system as claimed in claim 1, wherein:

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

/or

a caliber ratio, defined by the caliber of said supply segment of the process line to the caliber of said measuring tube, is kept greater than 1.1 and/or smaller than 5.

12. The measuring system as claimed in claim 1, wherein:

said at least one sensor element is arranged at a distance from the inlet end of said measuring tube in and/or on said measuring tube that a ratio of said distance to a caliber of said measuring tube is kept greater than one.

13. The measuring system as claimed in claim 1, wherein:

the impingement surface is so arranged and so oriented in said flow conditioner that it is at least sectionally perpendicular to a longitudinal axis of said flow conditioner; and

/or

the impingement surface is so arranged and so oriented in said flow conditioner that it is at, least sectionally perpendicular to a longitudinal axis of said measuring tube; and

/or

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

/or

the impingement surface is at least sectionally planar; and

/or

the impingement surface tapers toward the measuring tube.

14. The measuring system as claimed in claim 1, wherein:

the impingement surface and the inner edge are formed at least partially by an inner cone formed into the inlet in said flow conditioner.

15. The measuring system as claimed in the preceding claim, wherein:

the inner cone forming the impingement surface shows a flank angle, which is greater than 45° and

smaller than 90°

such that said inner cone tapers toward the measuring tube.

16. The measuring system as claimed in claim 1, wherein:

said guide surface of said flow conditioner tapers toward said measuring tube.

17. The measuring system as claimed in claim 1, wherein:

said guide surface of said flow conditioner is formed, at least in part, by an inner cone formed in the flow conditioner.

18. The measuring system as claimed in the preceding claim, wherein:

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

smaller than 45°

.

19. The measuring system as claimed in claim 1, wherein:

the at least one measured value, produced by said 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, and a temperature measured value.

20. The measuring system as claimed in claim 1, wherein:

said measuring transducer comprises at least one bluff body arranged in said measuring tube, and said at least one sensor element of the sensor arrangement is arranged downstream from said at least one bluff body.

21. The measuring system as claimed in claim 1, wherein:

said at least one sensor element of the sensor arrangement protrudes at least partially into said measuring tube.

22. The measuring system as claimed in claim 1, wherein:

said measuring transducer comprises a transducer selected from a transducer group consisting of;

a vortex flow transducer, a magneto-inductive flow transducer, a Coriolis mass flow transducer, a density transducer, a viscosity transducer, and an ultrasonic flow transducer.