Method and apparatus for measuring ratio of mass flow rates and energy flow in a gas pipeline

- Badger Meter, Inc.

The present invention is a method and apparatus for monitoring in real time the mass and energy flow rate of a gas through a pipeline. The invention determines the mass flow ratio of a pipeline gas flowing through a pipeline compared to sample gas tapped from the pipeline line when the volumetric flow of pipeline gas through the pipeline is measured by a linear flow meter. Sample gas tapped from the pipeline is flowed to a chamber having a section with a fixed volume until the pressure in the chamber section is substantially equal to the pipeline gas pressure. The sample gas is maintained at substantially the same temperature as the gas in the pipeline while the sample gas is in the chamber section. A timer measures the time interval for the sample gas to flow from the chamber section at a selected rate for a calculated pressure drop the selected rate being controlled by a flow controller. The mass flow ratio is computed using the measured time interval and a signal from the linear flow meter. The energy flow rate of the pipeline gas is determined by measuring the energy flow rate of the sample gas and relating that value to the mass flow ratio of the pipeline gas compared to the sample gas.

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Claims

1. An apparatus to be used with a linear flow meter to measure a ratio of a mass flow rate of a pipeline gas through a pipeline compared to a mass flow rate of a sample gas tapped from the pipeline, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
means for routing the sample gas to the chamber section;
a valve for controlling the flow of sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber section at a selected rate;
a pressure sensor for measuring the sample gas pressure in the chamber section;
means for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline; and
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure, and ending when the sample gas pressure in the chamber section drops below a second pressure, the first pressure being greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure being less than about one-half of the pipeline gas pressure in the pipeline; and
a controller which receives a signal from the timer and a signal from the linear flow meter representing the volumetric flow of the pipeline gas through the pipeline and derives the ratio of the mass flow rate of the pipeline gas through the pipeline compared to the mass flow rate of the sample gas.

2. An apparatus as recited in claim 1 further comprising means for quickly reducing the sample gas pressure in the chamber section from the pipeline gas pressure to the first pressure.

3. An apparatus as recited in claim 2 wherein the means for quickly reducing the sample gas pressure in the chamber section from the pipeline gas pressure to the first pressure comprises a second section in the chamber.

4. An apparatus as recited in claim 1 further comprising a pressure regulator for reducing the pressure of the sample gas before the sample gas flows to the flow controller.

5. An apparatus as recited in claim 1 wherein the controller calculates the mass flow ratio in accordance with the following function: ##EQU39## where K.sub.x is a constant, f.sub.t is a signal from linear flow meter, t.sub.m is the time interval and C.sub.f is a correction factor dependent on the pipeline gas pressure, temperature and composition.

6. An apparatus as recited in claim 5 further comprising a second chamber located such that the sample gas flows through the second chamber before it flows to the flow controller.

7. An apparatus to be used with a linear flow meter for measuring the energy flow rate of a pipeline gas through a pipeline, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
means for routing the sample gas to the chamber section;
a valve for controlling the flow of sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber section at a selected rate;
a pressure sensor for measuring the sample gas pressure in the chamber section;
means for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure, and ending when the sample gas pressure in the chamber section drops below a second pressure, the first pressure being greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure being less than about one-half of the pipeline gas pressure in the pipeline;
a sample gas energy flow rate meter for measuring the energy flow rate of the sample gas; and
a controller which receives a signal from the timer, the linear flow meter which represents the volumetric flow of the pipeline gas through the pipeline the sample gas energy flow rate meter and derives the energy flow rate of the pipeline gas through this pipeline.

8. An apparatus as recited in claim 7 wherein the sample gas energy flow rate meter comprises:

a burner for burning the sample gas with air to form a flame; and
means for maximizing the flame temperature.

9. An apparatus as recited in claim 8 further comprising an air mass flow meter for measuring the air mass flow rate of the air burning the sample gas.

10. An apparatus as recited in claim 9 wherein the controller calculates the energy flow rate in accordance with the following function: ##EQU40## where K.sub.x is a constant, f.sub.t is a signal from the linear flow meter, t.sub.m is the time interval,.omega..sub.air is the air mass flow rate and C.sub.f is a correction factor dependent on the pipeline gas pressure, temperature, and composition.

11. A method for measuring a mass flow ratio ##EQU41## of a pipeline gas through a pipeline compared to a sample gas tapped from the pipeline, the method comprising the steps of:

measuring the volumetric flow rate of the pipeline gas through the pipeline with a linear flow meter;
flowing the sample gas to a chamber having a section with a fixed volume;
maintaining the temperature of the sample gas at substantially the same temperature as the pipeline gas in the pipeline when the sample gas is in the chamber section;
stopping the flow of sample gas to the chamber section when the pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
flowing the sample gas from the chamber section after the flow of the sample gas to the chamber section is stopped, thereby reducing the sample gas pressure in the chamber section;
timing the interval of time t.sub.m for the sample gas to flow from the chamber section at a selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure and ending when the sample gas pressure in the chamber section drops below a second pressure wherein the first pressure is greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure is less than about one-half of the pipeline gas pressure in the pipeline; and
deriving the mass flow ratio ##EQU42## of the pipeline gas through the pipeline compared to the sample gas tapped from the pipeline from a signal f.sub.t from the linear flow meter that is related to the volumetric flow rate of the pipeline gas, and the time interval t.sub.m.

12. A method as recited in claim 11 wherein the mass flow ratio is derived in a control system.

13. A method as recited in claim 12 wherein the control system calculates the mass flow ratio in accordance with the following function: ##EQU43## where K.sub.x is a constant, f.sub.t is a signal from the linear flow meter, t.sub.m is the time interval and C.sub.f is a correction factor dependent on the pipeline gas pressure, temperature and composition.

14. A method as in claim 13 further comprising the steps of:

flowing the sample gas to a second chamber of fixed volume;
stopping the flow of sample gas to the second chamber when the pressure of the sample gas in the second chamber is greater than or equal to a third pressure;
flowing the sample gas from the second chamber after the flow of the sample gas to the second chamber is stopped, thereby reducing the sample gas pressure in the second chamber;
timing the interval of time for the sample gas to flow from the second chamber at the selected rate beginning when the sample gas pressure in the second chamber drops below a third pressure and ending when the sample gas pressure in the second chamber section drops below a fourth pressure; and
determining a value for the correction factor C.sub.f in accordance with the following function: ##EQU44## where P.sub.L is the pipeline gas pressure, c is estimated using data stored in the control system and b is estimated in accordance with the following function: ##EQU45## where V.sub.1 is the volume of the chamber section, V.sub.2 is the volume of the second chamber, P.sub.1 is the first pressure, P.sub.2 is the second pressure, P.sub.3 is the third pressure, P.sub.4 is the fourth pressure, t.sub.m is the time interval for the pressure in the chamber section to drop from P.sub.1 to P.sub.2, and t.sub.Y is the time interval for the pressure in the second chamber to drop from P.sub.3 to P.sub.4.

15. A method for measuring the energy flow rate of a pipeline gas through a pipeline, the method comprising:

measuring the volumetric flow rate of the pipeline gas through the pipeline with a linear flow meter;
flowing the sample gas to a chamber having a section with a fixed volume;
maintaining the temperature of the sample gas at substantially the same temperature as the pipeline gas in the pipeline when the sample gas is in the chamber section;
stopping the flow of sample gas to the chamber section when the pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
flowing sample gas from the chamber section at a selected rate after the flow of sample gas to the chamber section is stopped, thereby reducing the sample gas pressure in the chamber section;
timing the interval of time t.sub.m for the sample gas to flow from the chamber section at a selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure and ending when the sample gas pressure in the chamber section drops below a second pressure wherein the first pressure is greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure is less than about one-half of the pipeline gas pressure in the pipeline;
measuring the energy flow rate of the sample gas; and
determining the energy flow rate of the pipeline gas through the pipeline from a signal f.sub.t from the linear flow meter that is related to the volumetric flow rate of the pipeline gas, the time interval t.sub.m, and the energy flow rate of the sample gas.

16. A method as recited in claim 15 wherein the energy flow rate of the sample gas is measured by:

burning the sample gas flowing from the chamber with air; and
adjusting the air flow so that the sample gas burns at maximum flame temperature.

17. A method as recited in claim 15 wherein the energy flow rate of the pipeline gas is determined in a control system.

18. A method as recited in claim 17 further comprising the step of measuring the air mass flow rate of air burning the sample gas.

19. A method as recited in claim 18 wherein the control system calculates the energy flow rate in accordance with the following function: ##EQU46## where K.sub.x is a constant, f.sub.t is a signal form the linear flow meter, t.sub.m is the time interval,.omega..sub.air is the air mass flow rate and C.sub.f is a correction factor dependent on the pipeline gas pressure, temperature and composition.

20. A method as recited in claim 19 further comprising the steps of:

flowing the sample gas to a second chamber of fixed volume;
stopping the flow of sample gas to the second chamber when the pressure of the sample gas in the second chamber is greater than or equal to a third pressure;
flowing the sample gas from the second chamber after the flow of the sample gas to the second chamber is stopped, thereby reducing the sample gas pressure in the second chamber;
timing the interval of time for the sample gas to flow from the second chamber at the selected rate beginning when the sample gas pressure in the second chamber drops below a third pressure and ending when the sample gas pressure in the second chamber section drops below a forth pressure; and
determining a value for the correction factor C.sub.f in accordance with the following function: ##EQU47## where P.sub.L is the pipeline gas pressure, c is estimated using data stored in the control system and b is estimated in accordance with the following function: ##EQU48## where V.sub.1 is the volume of the chamber section, V.sub.2 is the volume of the second chamber, P.sub.1 is the first pressure, P.sub.2 is the second pressure, P.sub.3 is the third pressure, P.sub.4 is the fourth pressure, t.sub.m is the time interval for the pressure in the chamber section to drop from P.sub.1 to P.sub.2, and t.sub.Y is the time interval for the pressure in the second chamber to drop from P.sub.3 to P.sub.4.

21. An apparatus that measures a ratio of a mass flow rate of a pipeline gas through a pipeline compared to a mass flow rate of a sample gas tapped from the pipeline for use with a linear flow meter measuring the volumetric flow of the pipeline gas through the pipeline, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
a pressure sensor for measuring the pressure of the sample gas in the chamber section;
a first line connected to the pipeline for routing the sample gas to the chamber section;
a valve mounted in the first line for controlling the flow of the sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber at a selected rate;
a second line for routing the sample gas away from the chamber to the flow controller;
a control for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure, and ending when the sample gas pressure in the chamber section drops below a second pressure, the first pressure being greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure being less than about one-half of the pipeline gas pressure in the pipeline;
a third line for routing the sample gas away from the flow controller; and
a control system for receiving signals from the pressure sensor, the timer and the linear flow meter and for computing the ratio of the mass flow rate of the pipeline gas through the pipeline compared to the mass flow rate of the sample gas.

22. An apparatus as recited in claim 21 further comprising a second chamber of fixed volume located in the second line so that the sample gas flows through the second chamber before it flows to the flow controller.

23. An apparatus as recited in claim 22 further comprising a pressure regulator located in the second line for reducing the sample gas pressure before the sample gas flows to the second chamber.

24. An apparatus as recited in claim 21 wherein the chamber has a second section located downstream of the chamber section with the fixed-volume and further comprising a second valve for controlling the flow of the sample gas from the fixed-volume chamber section to the second chamber section.

25. An apparatus for measuring the energy flow rate of a pipeline gas through a pipeline, the apparatus to be used with a linear flow meter measuring the volumetric flow of the pipeline gas through the pipeline, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
a pressure sensor for measuring the pressure of the sample gas in the chamber section;
a first line connected to the pipeline for routing the sample gas to the chamber section;
a valve mounted in the first line for controlling the flow of the sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber at a selected rate;
a second line for routing the sample gas away from the chamber to the flow controller;
a control for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure, and ending when the sample gas pressure in the chamber section drops below a second pressure, the first pressure being greater than about one-half of the pipeline gas pressure in the pipeline and the second pressure being less than about one-half of the pipeline gas pressure in the pipeline;
a burner for burning the sample gas with an air flow to form a flame;
a third line for routing the sample gas away from the flow controller to the burner;
a temperature sensor for measuring the flame temperature;
an air conduit for routing the air flow to the burner;
an air valve located in the air conduit for adjusting the air flow through the air conduit;
an air mass flow meter for measuring an air mass flow rate through the air conduit; and
a control system for receiving signals from the pressure sensor, the timer, the linear flow meter, the air mass flow meter and the temperature sensor, for communicating with the air valve to adjust the air flow so that the flame burns at the maximum temperature, and for computing the energy flow rate of the pipeline gas flowing through the pipeline.

26. An apparatus as recited in claim 25 further comprising a second chamber of fixed volume located in the second line so that the sample gas flows through the second chamber before it flows to the flow controller.

27. An apparatus as recited in claim 26 further comprising a pressure regulator located in the second line for reducing the sample gas pressure before the sample gas flows to the second chamber.

28. An apparatus as recited in claim 25 wherein the chamber has a second section located downstream of the chamber section with the fixed-volume and further comprising a second valve for controlling the flow of the sample gas from the fixed-volume chamber section to the second chamber section.

29. An apparatus to be used with a linear flow meter to measure a ratio of a mass flow rate of a pipeline gas through a pipeline compared to a mass flow rate of a sample gas tapped from the pipeline, the apparatus comprising:

a chamber having a section with a fixed volume V for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
means for routing the sample gas to the chamber section;
a valve for controlling the flow of sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber section at a selected rate;
a pressure sensor for measuring the sample gas pressure in the chamber section;
means for closing the valve when the sample gas pressure in the chamber section reaches the pressure P.sub.L of the pipeline gas in the pipeline; and
means for determining a time rate of change of pressure in the chamber section for a condition where the pressure in the chamber section is about one-half of pressure P.sub.L of the pipeline gas in the pipeline ##EQU49## a control system which receives a signal f.sub.t representing volumetric flow through the pipeline from the linear flow meter, and signals from the pressure sensor, and computes the ratio ##EQU50## of the mass flow rate of the pipeline gas through the pipeline compared to the mass flow rate of the sample gas by the following relationship: ##EQU51## where K.sub.t is a calibration constant for the linear flow meter, b is a second pressure virial coefficient of the gas and c is a third pressure virial coefficient of the gas.

30. A method for measuring a mass flow ratio ##EQU52## of a pipeline gas through a pipeline compared to a sample gas tapped from the pipeline, the method comprising the steps of:

measuring the volumetric flow rate of the pipeline gas through the pipeline with a linear flow meter;
flowing the sample gas to a chamber having a section with a fixed volume V;
maintaining the temperature of the sample gas at substantially the same temperature as the pipeline gas in the pipeline when the sample gas is in the chamber section;
stopping the flow of sample gas to the chamber section when the pressure in the chamber section reaches the pressure P.sub.L of the pipeline gas in the pipeline;
flowing the sample gas from the chamber section after the flow of the sample gas to the chamber section is stopped, thereby reducing the sample gas pressure in the chamber section;
determining the time rate of change of pressure in the chamber section for a condition where the pressure in the chamber section in about one-half of pressure P.sub.L of the pipeline gas in the pipeline ##EQU53## and deriving the mass flow ratio ##EQU54## of the pipeline gas through the pipeline compared to the sample gas tapped from the pipeline by solving the following relationship: ##EQU55## where f.sub.t is a signal from the linear flow meter representing the volumetric flow rate of the gas through the pipeline, K.sub.t is a calibration constant for the linear flow meter, b is a second virial coefficient of the gas, and c is a third virial coefficient of the gas.

31. A method for monitoring the energy flow rate of a pipeline gas through a pipeline and representing the flow of the pipeline gas in terms of an adjusted volumetric flow rate which corresponds to a volumetric flow rate at a defined pressure and temperature, the method comprising:

measuring the volumetric flow rate of the pipeline gas through the pipeline with a linear flow meter;
flowing sample gas to a chamber having a section with a fixed volume;
maintaining the temperature of the sample gas at substantially the same temperature as the pipeline gas in the pipeline when the sample gas is in the chamber section;
stopping the flow of sample gas to the chamber section when the pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
flowing sample gas from the chamber section at a selected rate after the flow of sample gas to the chamber section is stopped, thereby reducing the sample gas pressure in the chamber section;
timing the interval of time t.sub.m for the sample gas to flow from the chamber section at a selected rate beginning when the sample gas pressure in the chamber section drops below the first pressure and ending when the sample gas pressure in the chamber section drops below a second pressure;
measuring the energy flow rate of the sample gas;
measuring the energy content per unit volume of the sample gas; and
determining the adjusted volumetric flow rate of the pipeline gas through the pipeline from the volumetric flow rate of the pipeline gas measured by the linear meter, the time interval t.sub.m, the energy flow rate of the sample gas, and the energy content per unit volume of the sample gas.

32. An apparatus to be used with a control system and a linear flow meter measuring a volumetric flow rate of a pipeline gas flowing through a pipeline, for monitoring the energy flow rate of the pipeline gas through the pipeline and representing the flow of the pipeline gas in terms of an adjusted volumetric flow rate that corresponds to a volumetric flow rate at a defined pressure and temperature, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
means for routing the sample gas to the chamber section;
a valve for controlling the flow of sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber section at a selected rate;
a pressure sensor for measuring the sample gas pressure in the chamber section;
means for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline;
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure and ending when the sample gas pressure in the chamber section drops below a second pressure;
a sample gas energy flow rate meter for measuring the energy flow rate of the sample gas; and
means for determining the energy content per unit volume of the sample gas;
wherein the control system calculates the adjusted volumetric flow rate of the pipeline gas through the pipeline from the volumetric flow rate measured by the linear flow meter, the time interval, the energy flow rate of the sample gas, and the energy content per unit volume of the sample gas.

33. An apparatus to be used with a linear flow meter to measure a ratio of a mass flow rate of a pipeline gas through a pipeline compared to a mass flow rate of a sample gas tapped from the pipeline, the apparatus comprising:

a chamber having a section with a fixed volume for containing the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas in the pipeline when contained in the chamber section;
means for routing the sample gas to the chamber section;
a valve for controlling the flow of sample gas to the chamber section;
a flow controller for flowing the sample gas from the chamber section at a selected rate;
a pressure sensor for measuring the sample gas pressure in the chamber section;
means for closing the valve when the sample gas pressure in the chamber section reaches the pressure of the pipeline gas in the pipeline; and
a timer for measuring a time interval for the sample gas to flow from the chamber section at the selected rate beginning when the sample gas pressure in the chamber section drops below a first pressure, and ending when the sample gas pressure in the chamber section drops below a second pressure, the first pressure being equal to one-half of the pipeline gas pressure in the pipeline and the second pressure being less than the first pressure; and
a controller which receives a signal from the timer and a signal from the linear flow meter representing the volumetric flow of the pipeline gas through the pipeline and derives the ratio of the mass flow rate of the pipeline gas through the pipeline compared to the mass flow rate of the sample gas..Iadd.

34. An apparatus to be used with a flow meter that generates a signal representing flow rate of gas in a pipeline, said apparatus measuring a ratio of a mass flow rate of the gas in the pipeline to a mass flow rate of a sample gas tapped from the pipeline, the apparatus comprising:

a chamber having a known volume for receiving the sample gas, the sample gas being maintained at substantially the same temperature as the pipeline gas;
means for controlling the flow of the sample gas from said chamber, said means generating at least one signal indicative of mass flow rate of the sample gas; and
a controller which receives the signal from the flow meter and at least one signal from the means for controlling the flow of the sample gas, said controller being operable in response thereto, to calculate the ratio of the mass flow rate of the gas through the pipeline to the mass flow rate of the sample gas..Iaddend..Iadd.35. An apparatus as recited in claim 34, further comprising means for reducing the sample gas pressure in the chamber from a pipeline gas pressure to a pressure for measuring mass flow rate of the sample gas..Iaddend..Iadd.36. An apparatus as recited in claim 35, wherein the means for reducing the sample gas pressure comprises a second chamber communicating with said first-mentioned chamber..Iaddend..Iadd.37. An apparatus as recited in claim 36, further comprising a pressure regulator in a path of flow between the first-mentioned chamber and the second chamber for reducing the pressure of the sample gas before the sample gas flows to a flow controller..Iaddend..Iadd.38. An apparatus as recited in claim 34, wherein the gas in the pipeline is at pipeline pressure, and wherein the means for controlling the flow of the sample gas generates at least one signal indicative of a time interval in response to a decrease in pressure of the sample gas in the chamber from a first predetermined pressure to a second predetermined pressure, wherein said first predetermined pressure is greater than one-half of the pipeline pressure and wherein said second predetermined pressure is less than one-half of the pipeline pressure..Iaddend..Iadd.39. A method for measuring the energy flow of a gas through a pipeline, the method comprising:
measuring the volumetric flow rate of gas through the pipeline;
capturing in a chamber of predetermined volume, a sample of the gas in the pipeline at substantially the same temperature and pressure as the gas in the pipeline;
measuring the energy contained in the sample of the gas in the chamber of predetermined volume;
calculating the energy flow of gas in the pipeline in response to the volumetric flow rate of pipeline gas in the pipeline, and in response to the energy measured in the sample of the gas from the pipeline.

.Iaddend..Iadd.40. The method of claim 39, wherein the step of measuring the volumetric flow rate of gas through the pipeline further comprises:

measuring a ratio of the mass flow rate of gas in the pipeline to the mass flow rate of the sample of gas in the chamber of predetermined volume by:
flowing at least a portion of the sample of gas out of the chamber of predetermined volume; and
measuring a time interval (t.sub.m) corresponding to a predetermined pressure change, said pressure change resulting from the flowing of the portion of the sample of gas out of the chamber..Iaddend..Iadd.41. The method of claim 39, wherein the step of measuring the volumetric flow rate of gas through the pipeline further comprises measuring a signal (f.sub.t) from a turbine flow meter in the pipeline and multiplying by a constant (K.sub.t) to determine the volumetric flow rate of the pipeline gas in the pipeline..Iaddend..Iadd.42. The method of claim 41, wherein the step of measuring the energy contained in the sample of gas includes the step of measuring the volume of air required to combust the sample of gas at a maximum flame temperature..Iaddend..Iadd.43. The method of claim 39, wherein the step of measuring the energy contained in the sample of the gas in the chamber of predetermined volume further includes measuring the energy flow rate of the sample of gas flowed out of the chamber of predetermined volume..Iaddend..Iadd.44. The claim of claim 43, wherein the step of measuring the energy flow rate of the sample of gas further includes the steps of:
burning said sample of the gas with air; and
adjusting the flow of the air to obtain maximum flame temperature; and
measuring the flow rate of air (.omega..sub.air) at maximum flame

temperature..Iaddend..Iadd.45. The method of claim 44, wherein the step of measuring volumetric flow rate further comprises:

measuring a ratio of the mass flow rate of gas in the pipeline to the mass flow rate of the sample of gas in the chamber of predetermined volume by:
flowing at least a portion of the sample of gas out of the chamber of predetermined volume; and
measuring a time interval (t.sub.m) corresponding to a predetermined pressure change, said predetermined pressure change resulting from the flowing of the portion of the sample of gas out of the chamber.

.Iaddend..Iadd.46. The method of claim 45, wherein the step of measuring the volumetric flow rate of the pipeline gas further comprises the step of adjusting the volumetric flow rate of the pipeline gas to standard operating conditions in response to the ratio of the mass flow rates, and in response to the flow rate of air (.omega..sub.air) at maximum flame

temperature..Iaddend..Iadd.47. Apparatus for measuring the energy flow of a gas through a pipeline, the apparatus comprising:

a pipeline flow meter that measures the volumetric flow rate of gas through the pipeline and generates a signal indicative thereof;
means including a chamber of predetermined volume for receiving a sample of the gas in the pipeline at substantially the same temperature as the gas in the pipeline;
means for combusting the sample of the gas from the chamber of predetermined volume and generating a signal indicative of energy content of said sample of gas;
wherein said chamber receives successive samples of gas and wherein said samples are combusted by said means for combusting; and
means responsive to the signals from the pipeline flow meter and from the combusting means for calculating the energy flow of gas in the pipeline..Iaddend.
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Patent History
Patent number: RE35639
Type: Grant
Filed: Apr 11, 1995
Date of Patent: Oct 21, 1997
Assignee: Badger Meter, Inc. (Milwaukee, WI)
Inventors: William H. Vander Heyden (Mequon, WI), William H. Clingman, Jr., deceased (late of Dallas, TX)
Primary Examiner: Diego F. F. Gutierrez
Law Firm: Quarles & Brady
Application Number: 8/420,254
Classifications
Current U.S. Class: Heat Value Of Combustion (e.g., 'calorific Value') (374/36); Having Specified Control Of Input Of Mixture (374/37); Flow Comparing (73/196); 73/86303; 73/86361
International Classification: G01N 2522; G01F 100; G01F 900;