Method and apparatus for accurately measuring individual components of a multiphase fluid using separately measured Reynolds number

1. A method for determining the flow rates of a multi-component mixture in a pipe containing at least a liquid phase having an unknown viscosity, the method comprising the following steps:

a. the flow rates of the individual components of the multi-component mixture are measured in a flow meter,

b. the Reynolds number of the multi-component mixture is determined at a location separate from the flow meter but where the flow rate of the multi-component mixture is the same as in the flow meter, and

c. based on the results from steps a and b, a more accurate flow-rate of the individual components of the multi-component mixture is calculated.

2. A method according to claim 1 , wherein the said flow rates of the individual components of the multi-component mixture is measured using a multiphase flow meter.

3. A method according to claim 2 , wherein said multiphase flow meter contains one of a Venturi, V-cone and Dall-tube.

4. A method according to claim 1 , wherein said Reynolds number is determined based on a measurement of the pressure drop across a pipe section with a large wall roughness.

5. A method according to claim 4 , wherein said pipe section with large wall roughness has the same inner diameter as said multiphase flow meter.

6. A method according to claim 4 , wherein an axial section through said wall roughness has one of a saw-tooth pattern, square wave pattern and sinusoidal pattern.

7. A method according to claim 1 , wherein said Reynolds number is determined based on a ratio and/or difference between a measurement of the pressure drop across a pipe section with a large wall roughness and the pressure drop across a pipe section with a small wall roughness.

8. An apparatus for determining the flow rates of a multi-component mixture in a pipe containing at least a liquid phase having an unknown viscosity, the apparatus comprising the following elements:

a. a flow meter for measuring the individual components of the multi-component mixture,

b. means for determining the Reynolds number of the multi-component mixture located separately from the flow meter but where the flow rate of the multi-component mixture will be the same as in the flow meter, and

c. a computer and a mathematical program for calculating the Reynolds number of said multi-component mixture and a mathematical program for calculating the flow rates of the individual components of said multi-component mixture.

9. An apparatus according to claim 8 , wherein the said flow-meter is a multiphase flow meter.

10. An apparatus according to claim 9 , wherein said multiphase flow meter contains one of a Venturi, V-cone and Dall-tube.

11. An apparatus according to claim 8 , wherein said means for determining the Reynolds number contains a pipe section with a large wall roughness and a means for measuring the pressure drop across the pipe section with the large wall roughness.

12. An apparatus according to claim 11 , wherein said pipe section with large wall roughness has the same inner diameter as said multiphase flow meter.

13. An apparatus according to claim 11 , wherein an axial section through said wall roughness has one of a saw-tooth pattern, square wave pattern and sinusoidal pattern.

14. An apparatus according to claim 8 , wherein said means for determining the Reynolds number contains a pipe section with a large wall roughness and a means for measuring the pressure drop across the pipe section with the large wall roughness and a pipe section with a small wall roughness and a means for measuring the pressure drop across the pipe section with the small wall roughness.