You must log in to edit PetroWiki. Help with editing

Content of PetroWiki is intended for personal use only and to supplement, not replace, engineering judgment. SPE disclaims any and all liability for your use of such content. More information


Gas turbine meter: Difference between revisions

PetroWiki
Jump to navigation Jump to search
 
No edit summary
 
(2 intermediate revisions by the same user not shown)
Line 1: Line 1:
Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure.
Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure.


==International standards==
== International standards ==
There are two main standards for turbine meters: ISO ''Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters''<ref name="r5" /> and OIML ''R32, Rotary Piston Gas and Turbine Gas Meters''. <ref name="r6" />  
 
There are two main standards for turbine meters: ISO ''Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters''<ref name="r1">ISO Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters. 1994. Geneva, Switzerland: ISO.</ref> and OIML ''R32, Rotary Piston Gas and Turbine Gas Meters''. <ref name="r2">OIML R 32, Rotary Piston Gas Meters and Turbine Gas Meters. 1989. Paris: OIML.</ref>
 
== Turbine meter overview ==
 
A basic turbine meter consists of:


==Turbine meter overview==
A basic turbine meter consists of:
*A pressure-containing meter housing with end flanges
*A pressure-containing meter housing with end flanges
*A set of internals, incorporating the turbine wheel and gearing mechanisms
*A set of internals, incorporating the turbine wheel and gearing mechanisms
*A means of counting the turbine wheel revolutions
*A means of counting the turbine wheel revolutions


A typical turbine meter has additional components such as:  
A typical turbine meter has additional components such as:
 
*Flow conditioning devices
*Flow conditioning devices
*Bearing lubrication mechanisms
*Bearing lubrication mechanisms
*Sophisticated mechanical and electrical counter systems
*Sophisticated mechanical and electrical counter systems


An exploded view of a turbine meter is given in '''Fig. 1'''. For additional information about turbine meters and their use in liquid measurement, see [[Inference liquid meters#Turbine liquid flowmeters|Inference liquid meters]].
An exploded view of a turbine meter is given in '''Fig. 1'''. For additional information about turbine meters and their use in liquid measurement, see [[Inference_liquid_meters#Turbine_liquid_flowmeters|Inference liquid meters]].


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol3 Page 453 Image 0002.png|'''Fig. 1—Gas turbine meter components (Courtesy of Daniel Industries).'''
File:Vol3 Page 453 Image 0002.png|'''Fig. 1—Gas turbine meter components (Courtesy of Daniel Industries).'''
</gallery>
</gallery>


Like orifice meters, turbine meters should be mounted within a meter tube ('''Fig. 2'''). Most modern turbine meters have integral flow conditioners. These conditioners help to remove swirl and much of the distortion from the flow profile, and hence, the overall straight length requirement upstream of the meter can be relatively small. A typical requirement is 5 diameters.  
Like orifice meters, turbine meters should be mounted within a meter tube ('''Fig. 2'''). Most modern turbine meters have integral flow conditioners. These conditioners help to remove swirl and much of the distortion from the flow profile, and hence, the overall straight length requirement upstream of the meter can be relatively small. A typical requirement is 5 diameters.


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol3 Page 454 Image 0001.png|'''Fig. 2—Gas turbine meter tube (Courtesy of Daniel Industries).'''
File:Vol3 Page 454 Image 0001.png|'''Fig. 2—Gas turbine meter tube (Courtesy of Daniel Industries).'''
</gallery>
</gallery>


==Theory of operation==
== Theory of operation ==
The operation of a turbine meter is based on the measurement of the velocity of gas. The flowing gas is accelerated and conditioned by the meter’s straightening section. The integrated straightening vanes prepare the gas flow profile by removing undesirable swirl and asymmetry before the gas flows over the freely rotating turbine wheel. The dynamic forces of the flowing gas cause the rotor to rotate. The turbine wheel is mounted on the main shaft, with high-precision, low-friction ball bearings. The turbine wheel has helical blades that have a known angle relative to the gas flow. The gas flow drives the turbine wheel at an angular velocity, which, in the linear range of a well-designed meter, is proportional with the gas velocity. Using a gearing mechanism, the rotating turbine wheel drives the mechanical counter. In addition, the rotating blade can also be used to generate pulses via a proximity sensor. Each pulse detected is equivalent to a discrete volume of gas at actual conditions (i.e., the total number of pulses collected in any period of time represents the gross observed volume during that period). For each meter, a calibration characteristic (''K'' factor) is required. This factor is expressed in pulses per volume and is given by the manufacturer.


The ''K'' factor is determined by means of a flow calibration. This flow calibration should be carried out over the entire operating range of the meter because the ''K'' factor may vary with flow. This variation with flow is the turbine meter’s linearity. Once the ''K'' factor has been defined, the flow through the meter can be calculated because the two quantities are proportional.  
The operation of a turbine meter is based on the measurement of the velocity of gas. The flowing gas is accelerated and conditioned by the meter’s straightening section. The integrated straightening vanes prepare the gas flow profile by removing undesirable swirl and asymmetry before the gas flows over the freely rotating turbine wheel. The dynamic forces of the flowing gas cause the rotor to rotate. The turbine wheel is mounted on the main shaft, with high-precision, low-friction ball bearings. The turbine wheel has helical blades that have a known angle relative to the gas flow. The gas flow drives the turbine wheel at an angular velocity, which, in the linear range of a well-designed meter, is proportional with the gas velocity. Using a gearing mechanism, the rotating turbine wheel drives the mechanical counter. In addition, the rotating blade can also be used to generate pulses via a proximity sensor. Each pulse detected is equivalent to a discrete volume of gas at actual conditions (i.e., the total number of pulses collected in any period of time represents the gross observed volume during that period). For each meter, a calibration characteristic (''K'' factor) is required. This factor is expressed in pulses per volume and is given by the manufacturer.
 
The ''K'' factor is determined by means of a flow calibration. This flow calibration should be carried out over the entire operating range of the meter because the ''K'' factor may vary with flow. This variation with flow is the turbine meter’s linearity. Once the ''K'' factor has been defined, the flow through the meter can be calculated because the two quantities are proportional.
 
== Advantages and disadvantages ==


==Advantages and disadvantages==
The advantages and disadvantages for turbine meters are given in '''Table 1'''.
The advantages and disadvantages for turbine meters are given in '''Table 1'''.


<gallery widths=300px heights=200px>
<gallery widths="300px" heights="200px">
File:Vol3 Page 454 Image 0002.png|'''Table 1'''
File:Vol3 Page 454 Image 0002.png|'''Table 1'''
</gallery>
</gallery>


==Sizing==
== Sizing ==
Gas turbine meter sizing varies from one manufacturer to the next; however, the variables to be considered are consistent. Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure. Thus, a given size turbine meter will have an associated upper uncorrected flow rate limit. The range of the measurement is affected at the low end by the amount of mass flow through the meter. Thus, the range of a turbine meter is enhanced by increasing line pressure. For example, a 3-in. gas turbine meter might have a range of 30:1 at 200 psi but more than 60:1 at 500 psi.


==References==
Gas turbine meter sizing varies from one manufacturer to the next; however, the variables to be considered are consistent. Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure. Thus, a given size turbine meter will have an associated upper uncorrected flow rate limit. The range of the measurement is affected at the low end by the amount of mass flow through the meter. Thus, the range of a turbine meter is enhanced by increasing line pressure. For example, a 3-in. gas turbine meter might have a range of 30:1 at 200 psi but more than 60:1 at 500 psi.
<references>
 
<ref name="r5" >ISO Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters. 1994. Geneva, Switzerland: ISO. </ref>
== References ==
<ref name="r6" >OIML R 32, Rotary Piston Gas Meters and Turbine Gas Meters. 1989. Paris: OIML.</ref>
 
</references>
<references />
 
== Noteworthy papers in OnePetro ==


==Noteworthy papers in OnePetro==
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read
Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read


==External links==
== External links ==
 
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro
Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro


==See also==
== See also ==
[[Gas meters]]
 
[[Gas_meters|Gas meters]]


[[Positive displacement liquid meters]]
[[Positive_displacement_liquid_meters|Positive displacement liquid meters]]


[[Inference liquid meters]]
[[Inference_liquid_meters|Inference liquid meters]]


[[Liquid flow meter proving and LACT units]]
[[Liquid_flow_meter_proving_and_LACT_units|Liquid flow meter proving and LACT units]]


[[Liquid meters]]
[[Liquid_meters|Liquid meters]]


[[PEH:Liquid and Gas Measurement]]
[[PEH:Liquid_and_Gas_Measurement]]
[[Category:4.1.6 Compressors, engines, and turbines]]

Latest revision as of 21:15, 1 June 2015

Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure.

International standards

There are two main standards for turbine meters: ISO Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters[1] and OIML R32, Rotary Piston Gas and Turbine Gas Meters. [2]

Turbine meter overview

A basic turbine meter consists of:

  • A pressure-containing meter housing with end flanges
  • A set of internals, incorporating the turbine wheel and gearing mechanisms
  • A means of counting the turbine wheel revolutions

A typical turbine meter has additional components such as:

  • Flow conditioning devices
  • Bearing lubrication mechanisms
  • Sophisticated mechanical and electrical counter systems

An exploded view of a turbine meter is given in Fig. 1. For additional information about turbine meters and their use in liquid measurement, see Inference liquid meters.

Like orifice meters, turbine meters should be mounted within a meter tube (Fig. 2). Most modern turbine meters have integral flow conditioners. These conditioners help to remove swirl and much of the distortion from the flow profile, and hence, the overall straight length requirement upstream of the meter can be relatively small. A typical requirement is 5 diameters.

Theory of operation

The operation of a turbine meter is based on the measurement of the velocity of gas. The flowing gas is accelerated and conditioned by the meter’s straightening section. The integrated straightening vanes prepare the gas flow profile by removing undesirable swirl and asymmetry before the gas flows over the freely rotating turbine wheel. The dynamic forces of the flowing gas cause the rotor to rotate. The turbine wheel is mounted on the main shaft, with high-precision, low-friction ball bearings. The turbine wheel has helical blades that have a known angle relative to the gas flow. The gas flow drives the turbine wheel at an angular velocity, which, in the linear range of a well-designed meter, is proportional with the gas velocity. Using a gearing mechanism, the rotating turbine wheel drives the mechanical counter. In addition, the rotating blade can also be used to generate pulses via a proximity sensor. Each pulse detected is equivalent to a discrete volume of gas at actual conditions (i.e., the total number of pulses collected in any period of time represents the gross observed volume during that period). For each meter, a calibration characteristic (K factor) is required. This factor is expressed in pulses per volume and is given by the manufacturer.

The K factor is determined by means of a flow calibration. This flow calibration should be carried out over the entire operating range of the meter because the K factor may vary with flow. This variation with flow is the turbine meter’s linearity. Once the K factor has been defined, the flow through the meter can be calculated because the two quantities are proportional.

Advantages and disadvantages

The advantages and disadvantages for turbine meters are given in Table 1.

Sizing

Gas turbine meter sizing varies from one manufacturer to the next; however, the variables to be considered are consistent. Gas turbine meters are velocity meters, and the upper velocity limit is essentially unchanged by pressure. Thus, a given size turbine meter will have an associated upper uncorrected flow rate limit. The range of the measurement is affected at the low end by the amount of mass flow through the meter. Thus, the range of a turbine meter is enhanced by increasing line pressure. For example, a 3-in. gas turbine meter might have a range of 30:1 at 200 psi but more than 60:1 at 500 psi.

References

  1. ISO Standard 9951, Measurement of Gas Flow in Closed Conduits: Turbine Meters. 1994. Geneva, Switzerland: ISO.
  2. OIML R 32, Rotary Piston Gas Meters and Turbine Gas Meters. 1989. Paris: OIML.

Noteworthy papers in OnePetro

Use this section to list papers in OnePetro that a reader who wants to learn more should definitely read

External links

Use this section to provide links to relevant material on websites other than PetroWiki and OnePetro

See also

Gas meters

Positive displacement liquid meters

Inference liquid meters

Liquid flow meter proving and LACT units

Liquid meters

PEH:Liquid_and_Gas_Measurement