Liquid ammonia pipeline leak detection 2

[zane009]

Hi - I am in need of some assistance. I have been given conflicting information regarding the time a down stream flow meter will respond to a leak in a liquid ammonia pipeline (1.4 km, @ 750 tonnes/hr). One engineer says that as liquid ammonia is an incompressible fluid, the down stream meter will respond immediately. Another engineer advises that there will be a delay based on fluid velocity. Can some one provide some clarity

Thanks

 

[BigInch]

Note: EVERYTHING is compressible.

Time to realize a leak is dependent on the relative size of the leak and the method of detection.

If you are attempting to use ultrasonic leak detection, there will be a travel time of the sound, estimate 0.5 seconds for a leak at one end and a detector at the other and the time for the software to realize its not just noise.

Other methods are available statistical volume tracking and pressure-volume measurements within a hydraulic model compared to real time parameters for which time to realize a leak is some inverse function of leak size and time that the leak has been active.

**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[Latexman]

In my experience, liquid ammonia transfer is usually characterized as "flashing flow". It starts out as saturated liquid and flashes as it flows to it's destination, where it is a two phase mixture. Can your lead detection method handle two phase flow?

Good luck,
Latexman

 

[zane009]

Thanks for the info. The flow meters at the start and end of the pipeline (300 mm) are DP type. We use the differential as a leak detection indicator (>50 tonnes/hr differential will activate the ESD). They do not handle two phase flow well and that causes problems. Information suggest that a leak of >25 mm will generate a differential of >50 tonnes/hr, but the clash of views is when will the flow meter at the end of the pipeline se the reduction in flow.

Thanks

 

[BigInch]

Flowmeter measurement alone will delay based on velocity, compressibility and distance from the leak.

Small leaks may take longer time to notice, since only slight variations in pressure & flow would be easily disguised by noise, so the integration time for small differential flow needs to be longer to pick them up. The timing details for various leak rates can easly be found when the system is simulated with a transient analysis and inlet and outlet integral flow meters.

**********************
"Pumping systems account for nearly 20% of the world’s energy used by electric motors and 25% to 50% of the total electrical energy usage in certain industrial facilities." - DOE statistic (Note: Make that 99.99% for pipeline companies)

http://virtualpipeline.spaces.live.com/

 

[dcasto]

for such a short line try typical mass meters and over under accounting, for added security try ultra sonic sound detection.