US 5,400,653 A · Coriolis effect meter using optical fiber sensors

Abstract

A Coriolis mass flow rate meter for measuring the mass flow rate of material flowing through a conduit. The flow meter includes at least one flow tube through which the material to be measured passes. The flow tube is vibrated at its natural frequency so that the concurrent flow of material through the vibrating tube produces a displacement of the tube with the magnitude of the displacement being dependent upon the magnitude of the generated Coriolis forces and the mass flow rate of the measured material. The phase of the displacement of the flow tube is measured using optical fiber sensors comprising at least one loop of optical fiber which is flexed by the displacement of the flow tube. This flexing of the fiber causes a corresponding change in its optical conductivity and a corresponding change in the intensity of the light transmitted through the fiber from a light signal source to a signal detector. The modulated light signal received by the optical signal detector is converted to an electrical signal which is processed to generate the mass flow rate and other information for the flowing material. A feedback circuit for the light signal source monitors the average intensity of the light received by the signal detector and controls the drive signal applied to the light source to maintain the average intensity of the light signal received by the detector at a predetermined initial intensity.

Claims52

Dependent claims

A Coriolis mass flow meter for measuring at least one characteristic of material flowing through a conduit, said flow meter comprising:

(a) at least one flow tube means having an inlet and an outlet that, in use, are coupled to a conduit for enabling the flow of material through said at least one flow tube means from said inlet to said outlet;
(b) means for vibrating said at least one flow tube means so that said vibration of said at least one flow tube means and said flow of material through said at least one flow tube means together produce a resultant oscillation of said at least one flow tube means;
(c) an optical signal source;
(d) optical fiber means connected to said at least one flow tube means and to said optical signal source;
and
(e) means including said optical fiber means responsive to the oscillation of said at least one flow tube means for optically measuring the oscillation of said at least one flow tube means to provide for the measurement of said at least one characteristic of said material flowing through the conduit;
wherein said optical fiber means comprises at least one optical fiber capable of providing optical attenuation of a signal emitted by said optical signal source in response to microbending of said at least one optical fiber.

4 more elements

A method of operating a Coriolis mass flow meter for measuring at least one characteristic of material flowing through a conduit, said mass flow meter comprising at least one flow tube having an inlet and an outlet, said method comprising the steps of:

(a) coupling said at least one flow tube with a conduit to enable a flow of material through said at least one flow tube from said inlet to said outlet;
(b) vibrating said at least one flow tube so that said vibration of said at least one flow tube and said flow of material through said at least one flow tube together produce a resultant oscillation of said at least one flow tube;
and
(c) coupling optical fiber means to said at least one flow tube so that said optical fiber means bends in response to said oscillation of said at least one flow tube for optically measuring said oscillation of said at least one flow tube to provide for measurement of said at least one characteristic of said material flowing through the conduit, wherein said optical fiber means comprises at least one optical fiber capable of providing optical attenuation in response to microbending of said at least one optical fiber.

1 more element

A Coriolis effect meter for measuring at least one characteristic of material flowing through a conduit, said meter comprising:

(a) at least one flow tube having an inlet and an outlet coupled, when in use, to a conduit to enable a flow of said material through said at least one flow tube from said inlet to said outlet;
(b) means for vibrating said at least one flow tube so that said vibration of said at least one flow tube and said flow of material through said at least one flow tube together generate Coriolis forces that produce a resultant oscillation of said at least one flow tube;
(c) a light source;
(d) an optical detector means;
(e) metal-clad optical fiber sensor means coupled to said at least one flow tube for conducting light from said light source to said optical detector means;
wherein said metal clad optical fiber sensor means comprises at least one optical fiber that provides optical attenuation of a signal emitted by said light source in response to microbending of said at least one optical fiber as said at least one flow tube is oscillated;
and
(f) said metal-clad optical fiber sensor means and said optical detector means being responsive to said oscillation of said at least one flow tube and to said optical attenuation for generating a signal representing the displacement of said at least one flow tube resulting from said oscillations to facilitate a measurement of said at least one characteristic of said material flowing through the conduit.

5 more elements

A method of operating a Coriolis effect meter for measuring at least one characteristic of material flowing through a conduit, said meter comprising at least one flow tube having an inlet and an outlet coupled, when in use, to a conduit to enable a flow of said material through said at least:

one flow tube from said inlet to said outlet, said method comprising the steps of:
(a) vibrating said at least one flow tube so that said vibration of said at least one flow tube and said flow of material through said at least one flow tube together generate Coriolis forces that produce a resultant oscillation of said at least one flow tube;
(b) conducting light from a light source via a metal-clad optical fiber sensor means to an optical detector means;
wherein said metal clad optical fiber sensor means comprises at least one optical fiber coupled to said at least one flow tube for providing optical attenuation of a signal emitted by said light source in response to microbending of said at least one optical fiber as said at least one flow tube is oscillated;
and
(c) operating said metal-clad optical fiber sensor means and said optical detector means in response to said oscillations of said at least one flow tube and to said optical signal attenuation for generating a signal corresponding to the displacement of said at least one flow tube resulting from said oscillations to provide for measurement of said at least one characteristic of said material flowing through the conduit.

3 more elements

A Coriolis effect meter for measuring the mass flow rate of material through a conduit, said meter comprising:

(a) at least one flow tube having an inlet and an outlet coupled, when in use, to a conduit to enable a flow of said material through said at least one flow tube from said inlet to said outlet;
(b) means for vibrating said at least one flow tube so that said vibration of said at least one flow tube and the flow of material through said at least one flow tube together generate forces that produce a resultant oscillation of said at least one flow tube;
(c) a light source;
(d) a light detector means;
(e) metal-clad optical fiber sensor means for conducting light from said light source to said light detector means;
(f) said metal-clad optical fiber sensor means being flexibly movable in response to said oscillations of said at least one flow tube to provide microbend attenuation of said conducted light;
(g) said metal-clad optical fiber sensor means and said light detector means being responsive to said flexible movement caused by said oscillations of said at least one flow tube for generating a first signal representing the displacement of said at least one flow tube caused by said oscillations;
and
(h) means responsive to the said generation of said first signal for generating a second signal representing said mass flow rate through the conduit.

6 more elements

A method of operating a Coriolis effect meter for measuring the mass flow rate of material through a conduit, said meter comprising at least one flow tube having an inlet and an outlet coupled, when in use, to a conduit to enable a flow of said material through said at least one flow tube from said inlet to said outlet, said method comprising the steps of:

(a) vibrating said at least one flow tube so that said vibration of said at least one flow tube and said flow of material through said at least one flow tube together generate forces that produce a resultant oscillation of said at least one flow tube;
(b) conducting light from a light source via metal-clad optical fiber sensor means to an optical detector means;
(c) said metal-clad optical fiber sensor means being flexibly movable in response to said oscillation of said at least one flow tube to provide microbend attenuation of said optical signal conducted to said optical detector means;
(d) operating said optical detector means in response to said flexible movement caused by said oscillations of said at least one flow tube for generating a first signal corresponding to the displacement of said at least one flow tube caused by said oscillations;
and
(e) generating a second signal representing said mass flow rate through said conduit in response to the said generation of only an AC component of said first signal.

3 more elements

A Coriolis effect meter for measuring at least one characteristic of material flowing through a conduit, said meter comprising:

(a) at least one flow tube means having an inlet and an output adapted to be coupled, when in use, to a conduit to enable a flow of said material through said at least one flow tube means from said inlet to said outlet;
(b) means for vibrating said at least one flow tube means at a natural frequency of said at least one flow tube means with material flow in said at least one flow tube means so that said vibration of said at least one flow tube means and the material flow through said at least one flow tube means together generate forces that produce a resultant oscillatory displacement of said at least one flow tube means;
(c) a light source;
(d) a light detector means;
(e) an optical fiber system comprising an optical fiber sensor means for conducting light from said light source to said light detector means, said optical fiber sensor means being flexibly movable in response to said oscillatory displacement of said at least one flow tube means for varying the intensity of the light applied to said light detector means;
(f) said light detector means being responsive to said variation of said light intensity for generating a first signal having an AC and a DC component with said AC component representing the instantaneous oscillatory displacement of said at least one flow tube means, said detector being effective for generating said first signal in response to the microbend attenuation of said light resulting from said flexible movement of said optical fiber sensor means;
and
(g) means responsive only to said generation of said AC component for generating an output signal representing said at least one characteristic of said material flowing through said conduit.

5 more elements

A method of operating a Coriolis effect meter for measuring the mass flow rate of material through a conduit, said meter comprising at least one substantially U-shaped flow tube means having an inlet and an outlet coupled, when in use, to a conduit to enable a flow of said material through said at least one substantially U-shaped flow tube means from said inlet to said outlet, said method comprising the steps of:

(a) vibrating said at least one substantially U-shaped flow tube means at a natural frequency of said at least one substantially U-shaped flow tube means with material flow therein so that said vibration of said at least one substantially U-shaped flow tube means and said material flow through said at least one substantially U-shaped flow tube means together generate forces that produce a resultant oscillation of said at least one substantially U-shaped flow tube means;
(b) conducting light from a light source via optical fiber sensor means to an optical detector means;
(c) flexibly moving said optical fiber sensor means in response to said oscillations of said at least one substantially U-shaped flow tube means for varying the intensity of the light applied to said optical detector means;
(d) operating said optical detector means in response to said variation of said light intensity for generating a first signal having an AC and a DC component, with said AC component representing the instantaneous displacement of said at least one substantially U-shaped flow tube means resulting from said oscillations of said at least one substantially U-shaped flow tube means, said optical detector being effective for generating said first signal in response to the microbend attenuation of said light signal resulting from said flexible movement of said optical fiber sensor means;
and
(e) generating an output signal representing said mass flow rate of material through said conduit solely in response to said generation of said AC component of said first signal.

3 more elements

Dependencies are inferred from the claim text.

Coriolis effect meter using optical fiber sensors

Life of this patent

Coriolis effect meter using optical fiber sensors

Life of this patent

Abstract

Claims52