Commercial/Industrial Ultrasonic Gas Meter Operation...

Commercial/Industrial Ultrasonic Gas Meter

Operation & Diagnostics

2017 Western Regional Gas Conference

Bayview Ballroom 2

8/29/2017

9:00 – 9:45

Presenter: Dan Whaley

Company: Meter, Valve & Control, Inc

Meter, Valve & Control, Inc



▪ Natural gas distribution

▪ Transfer and measuring stations for municipal and regional gas suppliers

▪ Measuring stations of industrial and commercial applications

▪ Applications where continuous gas supply must be ensured




Operating PrincipleCrossing a river

• A boat crossing a river diagonally with the flow needs less

time than a boat crossing the river against the flow

• The stronger the current the faster the crossing with the

flow and the slower the crossing against it

• The difference between the two transit times depends

directly on the flow velocity

• Exactly this effect is exploited by the ultrasonic flow meter

Crossing a pipe by ultra sound

• The two diagonally opposed transducers function

alternatively as transmitters and receivers

• The sound signal emitted from Transducer A is accelerated

by the flow

• The sound signal emitted from Transducer B is slowed by

the flow

• The difference between the two transit times (T1 & T2) is

directly proportional to the gas velocity

• From the gas velocity, the volumetric flow can then be

calculated using cross sectional area.

Transducer B

Transducer A

Flow direction

Transit time

from A to B

(T1)

Transit time

from B to A

(T2)

Delta time

T = T2 - T1




Operating Principle




Typical Ultrasonic Meter Designs

Several meter designs are available today

Many diagnostic parameters are similar for all designs

Main difference in designs is analysis of velocity info




Typical Ultrasonic Meter Designs

Path CPath A

Path A

Path B

Path B




Flow Profile

• Good measurement is dependent on flow profile

• Typical requirements for upstream/downstream piping

with flow conditioning.

• Internal Flow Conditioning = No Upstream/Downstream

Piping Requirements

U-turn

Metering

section

Flow

conditioning




Diagnostics

Diagnostic parameters in USMs that are required by AGA 9:

• Average Gain Control (AGC) Levels

• Path Transit Times

• Average Axial Flow

• Speed of Sound (SOS) for each path

• Flow Velocities (VOG) for each path

• Average Speed of Sound

• Velocity Sampling Interval

• Averaging Time Interval

• Percentage of accepted pulses

• Status and/or measurement quality

• Alarm and failure indicatorsMeter, Valve & Control, Inc



Diagnostics - Gain

Gain? Can anyone tell me what it is?




Diagnostics - Gain

• Automatic operation in USMs

• Manufactures fire transducers with a fixed energy

• Gain is a measure of how much amplification is needed

• Amount of gain depends on several variables including:

• Metering pressure

• Gas velocity

• Meter size (path length)

• May increase due to contamination

• Gas composition (i.e.; Hydrogen vs. Natural Gas)

• Readings vary by manufacturer

• Contamination seldom causes gain to reach the maximumMeter, Valve & Control, Inc



Diagnostics - SNR

Signal to Noise? Can anyone tell me

what it is?




Diagnostics - SNR

• SNR is a measure of signal strength to noise

• Generally SNR is not used as much as others

• SNR becomes important when control valves are near

• At very high gas velocities, SNR will decrease

• Different manufactures have different methods of presenting

this information

• When the SNR gets low enough, performance will also decline




Diagnostics - SOS

Speed of Sound? Can anyone tell me what

it is?




Diagnostics - SOS

• Equation is similar to velocity calculation

• “Health” check for path velocities

• SOS by path is required by AGA 9

• SOS affect by gas composition, P&T, but not gas velocity!

• Can be calculated with AGA 10 or other algorithms

• If they do not agree, possibility of liquids, contamination or

poorly entered data.

• Can be checked versus theoretical values using GCMeter, Valve & Control, Inc



Diagnostics - Performance

Performance? Can anyone tell me what it

is?





• Signal Quality

• Level of accepted pulses (displayed in percent)

• Reported by path

• 100% acceptance isn’t required for accurate measurement

• Pulses are rejected if they fail certain criteria

• The most important part of pulse detection is to insure we don’t

pick the wrong waveform peak and thus have a bad transit time




Diagnostics In Action

• Software will automatically compare diagnostic

parameters. If within tolerance, meter will give an “all

good signal”

• If not in tolerance will give an indication as well





• All diagnostic data for each path is stored and can be

reviewed to determine the cause.

• Can account for accuracy changes.




Verification


• Self-Diagnostics

• SOS Verification

• Transfer Prover



Verification


Questions? Comments?

Commercial/Industrial Ultrasonic Gas Meter Operation...

Documents

Transcript of Commercial/Industrial Ultrasonic Gas Meter Operation...