4 replies to this topic

[sazy101]

Hi all,

I have a question regarding minimum gas velocity effect in piping. Currently we are in design phase of an amine plant (80 sgpm). Client have provided following conditions for design.

Gas Maximum Flow: 30 MMscfd

Gas Minimum Flow: 5 MMscfd

Gas Maximum Pressure: 1000 psig

Gas Minimum Pressure: 500 psig

Gas Temperature: 100 deg F

One of Our Process Engineer have sized inlet and outlet piping on Contactor based on Maximum flow rate (30 MMscfd) and Minimum Pressure of 500 psig. Which comes out to be 8”. The gas velocity in 8” @1000 psig with 30 MMscfd is around 15 ft/sec. when gas flow rate and pressure reduces, the velocity with also decrease. My question is basically " Is there in impact on process if velocity is 15 ft/sec or less".

 

Thank you very much in advance

 

[PingPong]

No. There is no impact on the contactor due to low gas velocity in the inlet and outlet piping.

 

Why would you think there is?

[sazy101]

I was concerned about Condensation of hydrocarbon C5+ and also about impact on gas velocity in contractor.

I am new in gas industry. So far i have heard about high gas velocity like 30-60 ft/sec ( typical velocity). Or 100 ft/sec Gas velocity when gas is dry and clean.

But 15ft/sec never heard and also gas velocity in this project will decrease with time, At minimum condition it will be around 5 or less than  5 ft/sec.

 

Thank you for your response

 

[Ajay S. Satpute]

Sazy101,

 

You need to calculate the heat loss from the gas. FYI, this can be done quickly using Hysys.

 

Velocity criteria in pipes are available in below link.

http://www.cheresour...velocity-check/

 

Regards.

 

Ajay S. Satpute

[PingPong]

I was concerned about Condensation of hydrocarbon C5+ and also about impact on gas velocity in contactor.

Gas velocity in contactor itself is not affected by chosing smaller inlet and outlet pipes to increase pipe velocities.

 

A properly designed contactor system has a KO drum just upstream the contactor (to remove any liquids in the feed gas) and a KO drum just after the contactor to remove any entrained amine.

 

If you are worried about heat loss, simply insulate the inlet pipe to the contactor.