pipenet transient model arv and anti surge valve location

[venkat85]

Hi Gentlemen,

I am currently doing surge analysis for a cross country pipe line of 14Km. here I could not able to suppress the vacuum in the complete pipeline. As i am seeing the negative pressure zones i am adding ARV, but still I could not fully eliminate the negative pressure from the pipeline. I have added ARVs almost at every 1000 meters but still it is showing me negative pressure at random locations between tthese ARVs,

I have choosen the pump trip case with NRVs in the system. pump trip time I have taken is 60 seconds.

Please anyone can guide me in this regard?


Thanking you in advance.


Regards,
Venkat.

[ambhad]

You may have to use vacuum breakers at some intervals where it is showing deep vacuum.

[venkat85]

Hi ambhad, in my query I have meant vacuum breakers as ARV. after using approx 15nos vacuum breakers I am getting vacuum at some other place which is about 100 meter from the vacuum breaker location.

I am having doubt on the size of vacuum breaker which I am mentioning and also on the time duration considered for the pump trip.

Please help me about these.

Thanks.

Regards,
venkat.

[ambhad]

Effect of vacuum breaker is relatively local during surge. So interval of breakers are important. Bigger size will help to reduce vacuum quickly.

Hi ambhad, in my query I have meant vacuum breakers as ARV. after using approx 15nos vacuum breakers I am getting vacuum at some other place which is about 100 meter from the vacuum breaker location.

I am having doubt on the size of vacuum breaker which I am mentioning and also on the time duration considered for the pump trip.

Please help me about these.

Thanks.

Regards,
venkat.

[venkat85]

Thanks ambhad, in my network i have varied the vacuum breaker sizes from 10mm to 300mm. But I havent seen any difference in the negative pressure value. It is same for all sizes of vacuum breaker. For example, I am giving th inlet size 300mm, co-efficient 1 and outlet size as 250mm.

please suggest whether i am providing the parameters in right way or not? Also, please suggest me about the pump trip time considered, because this one is having major influence in the volume of vacuum.

Thankyou.

Regards,
Venkat.

[ambhad]

You can try stand pipe in place of vacuum breaker or combination of both if your system permits. In one sense stand pipes are more reliable since vacuum breaker valves may malfunction. I do not know how pump trip time can affect the solution, because surge phenomenon happens after the pump is tripped from steady state running. However more inertia for pump and motor by adding flywheel can give you some good result to reduce vacuum.

[thawdar]

If the pipe line you are studying is in design stage,you should start from possibility of rerouting.