4 replies to this topic

[pmunishankar]

Dear All,

 

I have a question regarding design of Natural Gas Pressure let down station.

 

Attached schematic has all the details.

 

Downstream pressure of the Proposed Regulator varies between 600 - 700psig depending on the main gas supply source pressure and the downstream customers demand whereas the upstream pressure maintained at 1000psig by the supplier.

 

The question here is What type of Pressure Regulator should be used? Our consultant proposed Pressure Regulator that maintains the Upstream Pressure.

We are afraid that this may not work. We want that regulator to sense and maintain the downstream header pressure.

 

Please advise based on your experience. Your help is highly appreciated.

 

 

 

Attached Files

•  Pressure Regulator Design.png   531.35KB   2 downloads

[pmunishankar]

Dear All,

 

Appreciate if you any one can share their thoughts on this issue.

 

Thanks

Muni Shankar

[fallah]

 

Downstream pressure of the Proposed Regulator varies between 600 - 700psig depending on the main gas supply source pressure and the downstream customers demand whereas the upstream pressure maintained at 1000psig by the supplier.

 

The question here is What type of Pressure Regulator should be used? Our consultant proposed Pressure Regulator that maintains the Upstream Pressure.

We are afraid that this may not work. We want that regulator to sense and maintain the downstream header pressure.

 

 

Muni Shankar,

 

If you want the regulator 2 senses and maintains the downstream header pressure you should arrange the regulator 1 also senses and maintains its downstream pressure i.e the pressure of the pipe segment between regulators 1 and 2....

[Amit J]

pmunishankar,

 

You need to focus on your desired parameter i.e. Header operating pressure of 600-700 psig.

 

1. In given schematic, pressure regulator 1 is maintaining upstream pressure and hence it is difficult to predict , how supply of 1000 psig is maintained consistently.

 

2. But assuming that Gas supply pressure from your supplier is 1000 psig at battery limit....

 

your approach is correct ....you need to set Pressure regulator set point to maintain downstream pressure of 600-700 psig. Here tricky point is that pressure regulator set point cannot be a range but need to be a single value. Hence you need to choose appropriate setpoint for Pressure regulator2 to maintain your header operating pressure.

 

Also System with 2 pressure regulators in series can work. It is better if you have surge vessel in between. Also make sure that there is no condensation of gas due to pressure let down in 2 stages. otherwise it may create some operating problems to downstream system.

 

Hope this helps.

Edited by Amit J, 10 May 2018 - 02:30 AM.

[pmunishankar]

Thank you Fallah and Amit J.

 

First of all, it is a mistake on my part to wrongly depict Pressure Regulator 1. Actually Pressure Regulator 1 maintains the downstream pressure i.e. maintains pressure of the segment between Pressure Regulator 1 and Pressure Regulator 2. It is proposed that Pressure Regulator 2 also maintains its upstream pressure i.e maintains the pressure of pipe segment between Pressure Regulator 1 and Pressure Regulator 2.It is like two Pressure Regulators in series which are about 4 KM apart trying to maintain the pressure.

 

However, Pressure Regulator 2 downstream is connected to a header whose pressure varies between 600 - 700 psig due to other gas source and consumer's varying gas demand.

 

My worry is that having 2 Pressure Regulators in series though they are about 4KM apart.

 

Thanks and Regards,

Muni Shankar