Two-phase steam measurement system

• US 7,013,740 B2
• Filed: 12/18/2003
• Issued: 03/21/2006
• Est. Priority Date: 05/05/2003
• Status: Active Grant

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Mattar, Wade M., Dutton, Robert E.
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Thompson, Jewel V.
• Application Number:
  US10/737,856
• Publication Number:
  US 20040221660A1
• Time in Patent Office: 824 Days
• Field of Search: 738/610.4, 738/610.6, 738/613.55, 738/613.56, 733/54
• US Class Current: 73/861.354
• 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 1/8468 vibrating measuring conduits
• CPC Class Codes: G01F 15/024 involving digital counting
• CPC Class Codes: G01F 15/046 involving digital counting
• CPC Class Codes: G01F 15/08 Air or gas separators in combination with liquid meters; Liquid separators in combination with gas-meters
• CPC Class Codes: G01N 9/002 using variation of the resonant frequency of an element vibrating in contact with the material submitted to analysis G01N9/34 takes precedence

Abstract

A steam measurement system includes a Coriolis flowmeter associated with a vibratable flowtube to receive a flow of wet steam. A first sensor is associated with the flowtube to relay information about a motion of the flowtube by way of a first sensor signal. A second sensor determines a property of the flow and relays the property by way of a second sensor signal. A computing device receives the first and second sensor signals and is configured to calculate a steam quality of the flow from the first and second sensor signals. The computing device also may calculate the total heat energy flow rate of the flow. Other implementations may include a full or partial separator to separate the flow of wet steam into a substantially gas flow and a substantially liquid flow and a second Coriolis meter.

Claims

1. A steam measurement system comprising:

a Coriolis flowtube to receive a flow of wet steam, wherein a bulk density of the flow is determined based on a motion of the Coriolis flowtube;

a sensor to determine a property of the flow of wet steam;

a computing device configured to calculate a steam quality of the flow from the bulk density and the property;

a steam generator to generate the flow of wet steam;

a transport element to deliver the flow of wet steam to the Coriolis flowtube; and

an injection well connected to the Coriolis flowtube to receive the flow of wet steam from the Coriolis flowtube.

2. The steam measurement system of claim 1 wherein the property is a temperature of the flow and the sensor is a temperature sensor.

3. The steam measurement system of claim 2 wherein the temperature sensor is connected to the outside of the flowtube.

4. The steam measurement system of claim 2 wherein the temperature sensor is inserted into the flow of wet steam.

5. The steam measurement system of claim 1 wherein the property is a pressure of the flow and the sensor is a pressure sensor.

6. The steam measurement system of claim 1 wherein, to calculate the steam quality, the computing device is configured to calculate a density of a vapor phase of the flow from the property and to calculate a density of a liquid phase of the flow from the property.

7. The steam measurement system of claim 6 wherein the computing device includes a memory storing a steam table, the computing device configured to use the steam table to calculate the density of the vapor phase from the property and the density of the liquid phase from the property.

8. The steam measurement system of claim 6 wherein, to calculate the steam quality, the computing device is configured to use the bulk density, the density of the liquid phase, and the density of the gas phase to solve the following equation for the steam quality $x$

;

⁢

⁢

1Bulk⁢

⁢

Density=xVapor⁢

⁢

Density+1-xLiquid⁢

⁢

Density.

9. The steam measurement system of claim 1 wherein the computing device comprises a Coriolis transmitter.

10. The steam measurement system of claim 1 wherein the computing device comprises a flow computer.

11. A steam measurement system comprising:

a Coriolis flowtube to receive a flow of wet steam, wherein a bulk density and a bulk mass flow rate of the flow is determined based on a motion of the Coriolis flowtube;

a sensor to determine a property of the flow of wet steam;

a computing device configured to calculate a steam quality of the flow from the bulk density and the property, and is configured to calculate a heat energy flow rate of the flow from the steam quality and the bulk mass flow rate.

12. The steam measurement system of claim 11 wherein, to calculate the heat energy flow rate, the computing device is configured to calculate an enthalpy of the vapor phase of the flow from the property and to calculate an enthalpy of the liquid phase of the flow from the property.

13. The steam measurement system of claim 12 wherein, to calculate the heat energy flow rate, the computing device is configured to use the bulk mass flow rate m, the enthalpy of the liquid phase h_f, the enthalpy of the gas phase h_g, and the steam quality x to solve the following equation for the heat energy flow rate H_total:

H_total=m·

h_g·

x+m·

h_f·

(1−

x).

14. A method comprising:

passing a flow of wet steam through a vibrating flowtube associated with a Coriolis flowmeter, wherein the Coriolis flowmeter determines the bulk density of the flow of wet steam;

obtaining a temperature or a pressure of the flow of wet steam;

calculating a steam quality of the flow from the bulk density and the temperature or pressure;

calculating the bulk mass flow rate of the flow of wet steam; and

calculating a heat energy flow rate of the flow from the steam quality, the bulk mass flow rate, and the temperature or pressure.

15. The method of claim 14 wherein calculating the steam quality comprises:

calculating a density of a vapor phase of the flow from the temperature or pressure; and

calculating a density of a liquid phase of the flow from the temperature or pressure.

16. The method of claim 15 wherein calculating the steam quality comprises solving the following equation for the steam quality x:

$\frac{1}{\mathrm{Bulk}<br><br><br><br>\mathrm{Density}}=\frac{x}{\mathrm{Vapor}<br><br><br><br>\mathrm{Density}}+\frac{1-x}{\mathrm{Liquid}<br><br><br><br>\mathrm{Density}}.$

17. The method of claim 14 wherein calculating the heat energy flow rate comprises:

calculating an enthalpy of the vapor phase of the flow from the temperature or pressure obtained from the second sensor; and

calculating an enthalpy of the liquid phase of the flow from the temperature or pressure obtained from the second sensor.

18. The method of claim 14 wherein calculating the heat energy flow rate comprises solving the following equation for the heat energy flow rate H_total:

H_total=m·

h_g·

x+m·

h_f·

(1−

x)

where m is the bulk mass flow rate, h_f is the enthalpy of the liquid phase, h_g is the enthalpy of the gas phase, and x is the steam quality.

19. A steam measurement system comprising:

a separator to separate a flow of wet steam into a substantially gas flow and a substantially liquid flow;

a first Coriolis flowtube to receive the substantially gas flow, wherein a bulk densisty of the substantially gas flow is determined based on a motion of the first Coriolis flowtube;

a second Coriolis flowtube to receive the substantially liquid flow, wherein a bulk density of the substantially liquid flow is determined based on a motion of the second Coriolis flowtube;

a sensor to detect a temperature or pressure of the substantially gas flow or the substantially liquid flow; and

a computing device to calculate a total steam quality of the flow of wet steam from the bulk density of the substantially gas flow, the bulk density of the substantially liquid flow, and the temperature or pressure.

20. The steam measurement system of claim 19 wherein the sensor is a temperature sensor.

21. The steam measurement system of claim 20 wherein the temperature sensor is connected to the outside of the first or second Coriolis flowtube.

22. The steam measurement system of claim 20 wherein the temperature sensor is inserted into the substantially gas or substantially liquid flow.

23. The steam measurement system of claim 19 wherein the sensor is a pressure sensor.

24. The steam measurement system of claim 19 wherein, to calculate the steam quality, the computing device is configured to use the temperature or pressure to calculate a density of a vapor phase of the substantially gas flow;

a density of a liquid phase of the substantially gas flow;

a density of a vapor phase of the substantially liquid flow; and

a density of a liquid phase of the substantially liquid flow.

25. The steam measurement system of claim 24 wherein the computing device includes a memory storing a steam table, the computer configured to use the steam table to calculate the density of a vapor phase of the substantially gas flow;

the density of a liquid phase of the substantially gas flow;

the density of a vapor phase of the substantially liquid flow; and

the density of a liquid phase of the substantially liquid flow.

26. The steam measurement system of claim 19 wherein a bulk mass flowrate of the substantially gas flow is determined based on motion information of the first Coriolis flowtube, a bulk mass flowrate of the substantially liquid flow is determined based on motion information of the second Coriolis flowtube, and the computing device is configured to calculate a heat energy flow rate of the flow from the steam quality, the bulk mass flowrate of the substantially liquid flow, the bulk mass flowrate of the substantially gas flow, and the temperature or pressure.

27. The steam measurement system of claim 26 wherein, to calculate the heat energy flow rate, the computing device is configured to use the temperature or pressure to calculate an enthalpy of the vapor phase of the substantially gas flow;

to calculate an enthalpy of the liquid phase of the substantially gas flow;

to calculate an enthalpy of the vapor phase of the substantially liquid flow; and

to calculate an enthalpy of the liquid phase of the substantially liquid flow.

28. The steam measurement system of claim 19 wherein the computing device comprises a Coriolis flowmeter transmitter.

29. The steam measurement system of claim 19 wherein the computing device comprises a flow computer.

30. The steam measurement system of claim 19 further comprising:

a steam generator to generate the flow of wet steam;

a transport element to deliver the flow of wet steam to the separator; and

an injection well connected to the first and second Coriolis flowtubes to receive the substantially gas and substantially liquid flows from the first and second Coriolis flowtubes.

31. A Coriolis transmitter for use with a steam measurement system that includes a Coriolis flowtube to receive a flow of wet steam;

a first sensor associated with the flowtube to relay information about a motion of the flowtube by way of a first sensor signal; and

a second sensor to determine a property of the flow and to relay the property by way of a second sensor signal, the Coriolis transmitter comprising;

a processing device to receive the first and second sensor signals, the processing device configured to calculate a steam quality of the flow from the first and second sensor signals.

32. The transmitter of claim 31 wherein the processing device is configured to calculate a heat energy flow rate of the flow from the steam quality and the first and second sensor signals.

33. The transmitter of claim 32 wherein, to calculate the heat energy flow rate, the processing device is configured to calculate an enthalpy of the vapor phase of the flow from the property and to calculate an enthalpy of the liquid phase of the flow from the property.

34. The transmitter of claim 33 wherein, to calculate the heat energy flow rate, the processing device is configured to calculate a bulk mass flowrate of the flow from the first sensor signal.

35. The transmitter of claim 34 wherein, to calculate the heat energy flow rate, the processing device is configured to use the bulk mass flow rate m, the entalpy of the liquid phase h_f, the enthalpy of the gas phase h_g, and the steam quality x to solve the following equation for the heat energy flow rate H_total:

H_total=m·

h_g·

x+m·

h_f·

(1−

x).