Method and apparatus for measuring mass flow and energy content using a linear flow meter

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.

A method for measuring a mass flow ratio ##EQU42## 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 ##EQU43## 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.

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.

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.

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.

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 ##EQU50## 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 ##EQU51## 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:
• ##EQU52## 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.

A method for measuring a mass flow ratio ##EQU53## 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 ##EQU54## and deriving the mass flow ratio ##EQU55## of the pipeline gas through the pipeline compared to the sample gas tapped from the pipeline by solving the following relationship:
• ##EQU56## 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.

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.

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.

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.