System and method measuring fluid flow in a conduit

• US 5,905,208 A
• Filed: 10/03/1996
• Issued: 05/18/1999
• Est. Priority Date: 02/03/1995
• Status: Expired due to Fees

• Current Assignee: Battelle Energy Alliance LLC (Battelle Memorial Institute)
• Original Assignee: Lockheed Martin Postal Technologies Inc (Opex Corporation)
• Inventors: Kidd, Terrel G., Ortiz, Marcos German
• Primary Examiner(s): Dombroske, George
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/724,985
• Time in Patent Office: 957 Days
• Field of Search: 73/861.42, 73/861.64, 73/861.72, 73/30.01, 73/30.02, 73/32, 73/438
• US Class Current: 73/861.42
• CPC Class Codes: G01F 1/206 Measuring pressure, force or momentum of a fluid flow which is forced to change its direction
• CPC Class Codes: G01F 1/363 with electrical or electro-mechanical indication G01F1/37 and G01F1/38 take precedence
• CPC Class Codes: G01F 1/72 Devices for measuring pulsing fluid flows
• CPC Class Codes: G01F 1/74 Devices for measuring flow of a fluid or flow of a fluent solid material in suspension in another fluid
• CPC Class Codes: G01F 1/80 operating by measuring pressure, force, momentum, or frequency of a fluid flow to which a rotational movement has been imparted
• CPC Class Codes: G01F 1/88 with differential-pressure measurement to determine the volume flow

Abstract

A system for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements.

Claims

1. A method for measuring fluid flow in a conduit having an abrupt bend in which there is a pressure differential between two locations in the conduit, the method comprising the steps of:

(a) positioning a first pressure transducer in the side of the conduit at a first of the two locations, to measure pressure of fluid in the conduit;

(b) positioning two or more second pressure transducers at a second of the two locations, to carry out a plurality of pressure measurements of fluid in the conduit;

(c) a computer computing the average pressure from the plurality of pressure measurements, and

(d) a computer computing flow rate of fluid in the conduit in accordance with the formula, ##EQU7## where mf is the flow rate in kilograms per second, B is a proportionality constant, D is the diameter of the conduit in meters, ρ

is the fluid density in kilograms per cubic meter, α

is the angle of the change of direction of the conduit at the bend, and Δ

P is the pressure difference between the first pressure transducer and the average pressure calculation.

2. A method as in claim 1 further comprising the steps of

(e) positioning a third pressure transducer in a side of the conduit to measure pressure,

(f) positioning a fourth pressure transducer in the conduit, at an elevation above that of the third pressure transducer, to measure pressure, and wherein said computing step further comprises

(g) computing the density ρ

of fluid flowing in the conduit in accordance with the formula ##EQU8## where g is the gravitational constant, H is the elevational distance in meters of the fourth pressure transducer above the third pressure transducer, and Δ

P₂ is the pressure difference measured between the third pressure transducer and the fourth pressure transducer, and

(h) computing the flow rate of fluid in the conduit in accordance with the formula of step (d), using the density ρ

computed in step (g).

3. A method for measuring fluid flow in a conduit having a gradual arc in which there is a pressure differential between two locations in the conduit, the method comprising the steps of:

(a) positioning a first pressure transducer in the side of the conduit at a first of the two locations, to measure pressure of fluid in the conduit;

(b) positioning a second or more pressure transducers at a second of the two locations, to carry out a plurality of pressure measurements of fluid in the conduit;

(c) a computer computing the average pressure from the plurality of pressure measurements, and

(d) a computer computing flow rate of fluid in the conduit in accordance with the formula, ##EQU9## where mf is the mass flow in kilograms per second, R is the radius of curvature of the arc, D is the diameter of the conduit in meters, ρ

is the fluid density in kilograms per cubic meter, and Δ

P is the pressure difference between the first pressure transducer and the average pressure calculation.