Coriolis flowmeter having a reduced flag dimension

• US 6,308,580 B1
• Filed: 03/19/1999
• Issued: 10/30/2001
• Est. Priority Date: 03/19/1999
• Status: Expired due to Term

• Current Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Original Assignee: Micro Motion Incorporated (Emerson Electric Company)
• Inventors: Johnston, Steven James, Crisfield, Matthew T., McCarthy, John Richard
• Primary Examiner(s): PATEL, HARSHAD R
• Application Number:
  US09/272,150
• Time in Patent Office: 956 Days
• Field of Search: 738/613.55, 738/613.56, 738/613.57
• US Class Current: 73/861.355
• CPC Class Codes: G01F 1/8409 constructional details
• CPC Class Codes: G01F 1/8413 means for influencing the flowmeter's motional or vibrational behaviour, e.g., conduit support or fixing means, or conduit attachments
• CPC Class Codes: G01F 1/8477 with multiple measuring conduits

Abstract

A Coriolis flowmeter sensor having a reduced flag dimension. In order to have a reduced flag dimension, the entire length of the flow tubes must vibrate to make the flowmeter sensor more sensitive to Coriolis effects. When the entire length of the flow tubes vibrate, a first set of brace bars connected to the flow tube separates the frequencies of vibration in the flow tubes. A second set of brace bars connected to the flow tubes enhances the zero stability of the flowmeter.

Claims

1. A Coriolis flowmeter comprising:

a pair of parallel oriented flow tubes wherein each of said flow tubes is divided into a plurality of segments including;

in-line segments defining opposing end portions of each of said flow tubes wherein said in-line segments have a longitudinal axis that is substantially parallel with a longitudinal axis of a pipeline and is contained in a first plane containing said pipeline,

bending segments in each of said flow tubes that extend from an end of said in-line segments and define a bend that changes said longitudinal axis of each of said flow tubes from being oriented in said first plane to being oriented substantially perpendicular to said first plane, and

a substantially u-shaped segment that extends between said bending segments on opposing end portions of said flow tubes, wherein said substantially u-shaped segment in each of said flow tubes defines a curve in each of said flow tubes that changes said longitudinal axis of said flow tube to be oriented in a direction that is substantially parallel to said first plane to traverse between said bending segments;

a first set brace bars affixed to each of said flow tubes at points in said bending segments where said longitudinal axis of said flow tubes is substantially forty-five degrees from being parallel with said first plane;

said first set of brace bars providing frequency separation between modes of vibration in said flow tubes; and

a second set of brace bars affixed to said flow tubes at points in said bending segments on said opposing ends of said flow tubes between said in-line segments and said first set of brace bars wherein said second set of brace bars enhance zero stability for each of said flow tubes.

2. The Coriolis flowmeter of claim 1 further comprising:

a inlet manifold that is connected to a first one of said in-line segments of each of said flow tubes and that receives flow from said pipeline, divides the flow into two flows and directs each of said two flows into a different one of said flow tubes.

3. The Coriolis flowmeter of claim 2 further comprising:

an inlet flange affixed to said inlet manifold for connecting said inlet manifold to said pipeline.

4. The Coriolis flowmeter of claim 1 further comprising:

an outlet manifold that is connected to a second one of said in-line segments of each of said flow tubes and that receives said flows from said flow tubes, combines said flows into an outlet flow, and directs said outlet flow into said pipeline.

5. The Coriolis flowmeter of claim 4 further comprising:

an outlet flange affixed to said outlet manifold for connecting said outlet manifold to said pipeline.

6. The Coriolis flowmeter of claim 1 further comprising:

manifolds affixed to opposing ends of said flow tubes;

a spacer affixed to said manifolds with said spacer enclosing said in-line segments and said bending segments of each of said flow tubes; and

an opening in said spacer through which said u-shaped segments of each of said flow tubes protrude through said spacer.

7. The Coriolis flowmeter of claim 1 wherein said u-shaped segments have a reduced flag dimension.

8. The Coriolis flowmeter of claim 1 further comprising:

a first leg and a second leg of said u-shaped segment that extend outward from said bending segments with a longitudinal axis that is oriented substantially three degrees from being perpendicular to said first plane.

9. The Coriolis flowmeter of claim 8 wherein said first plane is perpendicular to the ground and said flowmeter is self-draining.

10. The Coriolis flowmeter of claim 1 further comprises:

a housing enclosing said flow tubes.

11. The Coriolis flowmeter of claim 1 wherein an entire length of each of said flow tubes vibrates.

12. The Coriolis flowmeter of claim 1 wherein said point where said second set of brace bars to said flow tubes is a point where said longitudinal axis of said flow tubes is oriented at an angle in a range between seven and half degrees and twenty-two and half degrees with respect to said first plane.

13. The Coriolis flowmeter of claim 1 further comprising:

a drive system that oscillates said pair of flowtubes.

14. The Coriolis flowmeter of claim 1 further comprising:

a first pick-off affixed to said pair of flow tubes on an inlet said of said drive system; and

a second pick-off affixed to said pair of flow tubes on an outlet side of said drive system.

15. The Coriolis flow meter of claim 1 further comprising:

meter electronics which receives signal indicating said oscillation of said flow tubes from said pick-offs and determines a mass flow rate of material flowing through said flowmeter.