2 replies to this topic

[look4siva]

I need a better understanding on term 'Compressor settle out pressure' since I am dealing with  Dry type screw compressor with two stages of Compression in current running project (Flare Gas Recovery Project).

 

First of all , I would like to ask the Gurus whether my understanding of settle out pressure is correct.

My Understanding on settle out pressure

Whenever there is a shut down or a trip in a  Compressor , the suction and discharge valves will be shut off and an equilibrium pressure is developed in between these two isolation valves.This equilibrium pressure is called settle out pressure.Settle out Pressure is calculated for the following reasons :

 

1. Determine the design pressure of the downstream vessels (Ex: Knock out drum in our case).

 

2. Size the Compressor motor such that it will start at settle out pressure.( Told by Compressor Vendor)

 

Correct me , If my understanding is wrong else add some inputs for more clarity.

 

Now my concerns...

 

1. Does Positive displacement Compressors have settle out pressure ? If not , what would be the pressure contained within the Compressor during Compressor trip is called?.

2. Is there any requirement/standard to unload the so called settle out pressure to flare line through a flapper valve?

3.Can the Compressor start at settle out pressure ?

 

 

I am fresh to this concept and whatever information you give will educate me.

 

Thank You

 

[look4siva]

Can anybody help me to understand ?

 

Can Compressor start at settle out pressure without depressuring ?

[fallah]

Can anybody help me to understand ?

 

Can Compressor start at settle out pressure without depressuring ?

 

Hi,

 

Settle our pressure isn't applicable/definable for positive displacement compressor. But, in a centrifugal compressor if the motor has already been sized to cover the case, it can be started at settle out pressure...

Edited by fallah, 08 July 2015 - 11:27 PM.