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Compressor design

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AnhsirkT

Chemical
Aug 24, 2020
85
IN
IMG_20200913_191837_xjjwtl.jpg

Why these two design have difference?
What is the reason for that?

Do not think twice
 
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Ted
 
Unless there are some special operating conditions we dont know of, design 2 is not a good idea. Design 1 is the standard almost always followed.
 
ok
compressor outlet mixing with side stream in drum is good because of proper mixing
but
an we shift casing outlet line (going to drum for mixing)to diret suction line of compressor where it will mix with other at impeller or mixing zone

Do not think twice
 
what is disadvantage of design 2 ?
if i will choose design one so ineed only one Isolation valve for compressor casing

Do not think twice
 
Each stage should only receive feed from suction drum. There should be no sidestreams going direct to the compressor to avoid risk of liquids in mix feed.
 
Yes ifoquid present then it should go to KO drum
But in this design only 1S discharge going to mix with side stream (no liquid in 1S discharge and no cooler is present).
Can we mix directly in line ?
Or mix in ko drum ?
 
To isolate the casing we have to put 6mov in design 1
And in design 2 only 4
This is also a advantage
 
We dont have all the info required to agree with you that sidestream going to 2S will not result in liquids when mixed with 1D gas. As such, it is not recommended to bypass the 2S drum for the mixed 2S gas.

There are some cases where what you suggest is possible, and this is only when all normal and upset operating cases are taken into consideration.

Your diagram also shows the same suction drum bypass configuration for feed to 3S - not recommended unless you can present much more info as suggested previously.
 
"We dont have all the info required to agree with you that sidestream going to 2S will not result in liquids when mixed with 1D gas. As such, it is not recommended to bypass the 2S drum for the mixed 2S gas"
1S discharge is higher temp and not using any cooler in b/w so no liquid will form when it mixed with 2S drum flow.
same like sidestream flow going to compressor for addition.
it is for refrigeration compressor.
 
What is the refrigerant ?
You are not telling us much at all, and asking for advice on a matter that can potentially put this compressor at risk for wrong advice which results from poor and incomplete info..
 
Why is there no cooler on 1D gas? What will happen during full recycle when there is no fresh feed to the 2S drum? - High temp in the feed to the 2S compressor...
 
Where are the anti-surge / recycle lines? how are the compressor stages protected individually?
Often ethylene refrigerant compressors use a single casing with injections, is it the case or are the sections requiring individual casing each? if so it is needed to know, because if that is the case (single casing / multi injections), the mixing would occur inside the compressor via lateral or tangential injections (which one will depend on temperature and flow of main stream relative to side stream) and that would also explain why there is no cooler depicted.
But how to say if we do not know the range of pressures, flow, etc? Also what is the purpose of the compressor in the process plant?
Quench facility is mentioned, where are the lines that connect to quench facility ? Complete guesswork.

To my opinion, this is not a proper way to benefit from the great expertise offered by the people around here.
Why not start the post with a well elaborated write up, explaining context, purpose, and problem statement ; this would relieve the expert from the efforts of doing guesses and let them focus on the problem and propose solutions for you.
I of course guess that 'mov' is meant for motor operating valve, but not all people would do; use of capital letters would be a bare minimum. I can go on and on. There are plenty of free tools over the internet that would allow to sketch a process flow diagram with a better quality than this. Oh man, just for the pleasure of the eyes.
This is driving engineering to lower standard. Sorry.
 
Ok
Actually I just only want to know
I have three different casing and discharge of first casing going to the second casing with the 2nd drum flow.
Is it good idea to mix 1discharge to 2 suction in line ?
Or it should go to 2ko drum and mix where than it will go to 2 casing?

Asv are there from final discharge to all ko drum
 
Asv are there from final discharge to all ko drum

Where is the cooler located for spill back flow to compressor stages?
What is the purpose of a by-pass on stage 3 for design #1? hot gas by pass line??
How does the quench flow, which you previously mentioned, maintain temperature low in the feed to suction when operating in recycle?

1S discharge is higher temp and not using any cooler in b/w so no liquid will form when it mixed with 2S drum flow.

What if mixing discharge (main) flow from 1st stage with a side stream flow at supposedly low temperature, would potentially cool down main flow (mixing with side stream flow) thereby inducing risk of liquid droplets (pertaining to main flow) carry over to compressor suction and incidentally damage / failure could occur?

If you plan an escape, you must succeed as if you fail, you will be punished for trying. Never say or write down your plan. Heart is the only place where secrecy is granted.
 
What if mixing discharge (main) flow from 1st stage with a side stream flow at supposedly low temperature, would potentially cool down main flow (mixing with side stream flow) thereby inducing risk of liquid droplets (pertaining to main flow) carry over to compressor suction and incidentally damage / failure could occur?
In compressor ethylene is compressed so discharge temp will higher and from second stage ethylene vapor will go and will mix with 1S discharge so overall temp will reduce but not less than suction temp (it will in b/w both of them ) so no chance of liquid droplets
 
For quench control
There are TIC to maintain the drum temperature
That valve will open and put some ethylene liquid in drum and liquid will flash and cool down the temp of drum
In discharge of compressor there is water cooler
Before the recycle tapping so approx temp of recycled flow will be 35-40 C
 
Question is
Design 1 - First casing discharge directly mix with second suction in pipeline ( before the 2nd casing entrance) and same for 2&3
Design 2 - same will mix in KO drum then will go to next casing
Which is better?
 
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