Flow monitoring using flow control device

• US 7,054,764 B2
• Filed: 09/13/2004
• Issued: 05/30/2006
• Est. Priority Date: 09/29/2003
• Status: Active Grant

• Current Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Original Assignee: Air Products and Chemicals Incorporated (Linde Plc)
• Inventors: Miller, Jeremy Paul, Trembley, Jean-Philippe, Williams, Stuart Bruce
• Primary Examiner(s): Bui, Bryan
• Assistant Examiner(s): Pretlow, Demetrius
• Application Number:
  US10/939,809
• Publication Number:
  US 20050103093A1
• Time in Patent Office: 624 Days
• Field of Search: 702/137, 73/614.6, 73/614.7
• US Class Current: 702/45
• CPC Class Codes: F25D 29/001 for cryogenic fluid systems
• 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

Abstract

A method for determining the flow rate of a fluid, having a liquid fraction and a gas fraction, having the steps of: measuring the pressure and temperature of the fluid at a flow control device through which said cyrogenic fluid passes; inputting the measured pressure and C_v into an algorithm; and performing a single or multi-step iteration to determine a fluid mass flow rate of the fluid through the flow control device using the algorithm that relates the mass flow rate of the fluid to the C_v, and mass densities of the liquid fraction and the gas fraction of the fluid which are a function of the measured pressure, and temperature. A system is also provided.

Claims

1. A method of determining the flow rate of a fluid, having a liquid fraction and a gas fraction, comprising the steps of:

measuring the pressure and temperature of said fluid at a flow control device through which said fluid passes;

inputting said measured pressure and flow coefficient (C_v) into an algorithm; and

performing a single or multi-step iteration to determine a fluid mass flow rate of the fluid through said flow control device using said algorithm that relates the mass flow rate of said fluid to said C_v, and mass densities of said liquid fraction and said gas fraction of said fluid which are a function of said measured pressure, and temperature.

2. The method of claim 1 further comprising the step of repeating said measuring, inputting and performing steps on a continuous or semi-continuous basis.

3. The method of claim 1 wherein said flow control device is selected from the group consisting of an orifice, hole, open-ended pipe, nozzle, and valve.

4. The method of claim 1 wherein said algorithm additionally relates the mass flow rate of said fluid to vapor pressure of said fluid.

5. The method of claim 1 further comprising the step of measuring a temperature and pressure at a source of said fluid.

6. The method of claim 1 further comprising the step of calculating a flash loss of said fluid through each flow control device.

7. The method of claim 1 further comprising the step of defining one or more pipe portions through which said fluid flows and calculating a heat inleak of said fluid in said pipe portions.

8. The method of claim 1 further comprising the steps of:

calculating a flash loss of said fluid for said flow control device;

defining one or more pipe portions through which said fluid flows;

calculating a heat inleak of said fluid in said pipe portion; and

calculating said gas fraction and said liquid fraction of said fluid at said flow control device using said flash loss, and said heat inleak.

9. The method of claim 1 wherein said flow control device is a valve, and further comprising the step of measuring the percent opening of said valve.

10. The method of claim 9 wherein said algorithm additionally relates the mass flow rate of said fluid to vapor pressure of said fluid.

11. The method of claim 1 further comprising the step of inputting the measured temperature into said algorithm.

12. A system comprising a source of fluid having a liquid fraction and a gas fraction, one or more flow control devices, one or more apparatuses, means for measuring temperature and pressure at said one or more flow control devices, a pipe comprising one or more pipe portions in fluid communication with said source and at least one of said one or more apparatuses, an algorithm, means for inputting said measured pressures and flow coefficient (C_v) for each of said one or more flow control devices into said algorithm;

and

means for performing a single or multi-step iteration to determine a mass flow rate of the fluid to said one or more apparatuses using said algorithm that relates the mass flow rate of said fluid to said one or more apparatuses to said C_v for each of said one or more flow control devices and mass densities of said gas fraction and said liquid fraction of said fluid which are a function of said measured pressures and temperatures.

13. The system of claim 12 further comprising a plurality of said apparatuses, a plurality of said flow control devices, a plurality of said pipe portions in fluid communication with said source and at least one apparatus, and a plurality of said means for measuring said temperature and pressure.

14. The system of claim 12, further comprising means to repeat said iteration to calculate said mass flow rate of said fluid to said one or more apparatuses continuously or semi-continuously during a period of usage.

15. The system of claim 12 wherein said algorithm additionally relates the mass flow rate of said fluid to vapor pressure of said fluid.

16. The system of claim 12 further comprising the means for measuring a temperature and pressure at a source of said fluid.

17. The system of claim 12 wherein said means for performing calculates a flash loss of said fluid through each of said one or more flow control devices.

18. The system of claim 12 wherein said algorithm defines said pipe portions through which said fluid flows and calculates the heat inleak of said fluid in said pipe portions.

19. The system of claim 12 wherein said algorithm relates said gas fraction and said liquid fraction of said fluid to said flash loss in said one or more flow control devices, and said heat inleak in said portions.

20. The system of claim 12 wherein said flow control device is selected from the group consisting orifice, hole, open-ended pipe, nozzle, and valve.

21. The system of claim 12 wherein said means for performing is selected from the group consisting of a valve controller, PLC, computer, server, and a supervisory control data and aquisition industrial controller.