4 replies to this topic

[Leonardo TD]

Hi, I am not an expert in this area.  Hope you can help me.

 

I am studying some various process for air separation such as from Linde when I found some of the process utilize high pressure up to 40-60 bar to liquefy the air.

 

I am curious whether to sustain a cryogenic environment using 6-7 bar pressure is sufficient.

 

I also look some PFD using stages of compression.  Is this configuration just for the system start-up? or for the stable ASU operation?

 

Thank you.  Appreciated all feedback.

 

[Bodhisatya]

It all boils down to the product mix of the plant.

 

If high amount of liquid is extracted as output ,then to compensate ,you need to feed air with higher pressure ,as it gains higher enthalpy ,it can contributes more heat to  the outgoing stream and in-turn gets closer to  liquefaction temp at that pressure . 

 

Attached is a slide describing Cold production.Hope it helps.

 

 

Bodhisatya

Attached Files

•  6_cold production1.ppt   8.14MB   88 downloads

[Leonardo TD]

thank you @Bodhisatya.

 

My mistake not to put more detail.  Anyway how if the process is to produce GOX (gas oxygen).

 

I assume the GAN (gas nitrogen) and LOX (liquid oxygen) is being used as cold source in the main heat exchanger.  together with the cold gas from expansion.

 

I saw the power point.  Its informative.  If the output is gas product, from your explanation I assume it can use lower pressure?

 

However, during initial start up of the plant still kinda make me wonder how it works.

 

How many hours do it usually took?

 

Thank you.

[Bodhisatya]

I can't get what you r trying to say.Your statements are bit confusing.

 

The PPT shows LOX pumped from LP Column upto 32 bar(g) get converted to GOX while passing through MHE.This process is called Internal Compression of LOX.

 

Depending upon ur product mix the feed air pressure is determined.

 

Generally during warm start up it takes nearly 29-32 hours to start GOX production.

 

Bodhisatya

[Leonardo TD]

 

@Bodhisatya,

 

Sorry for my confusion.

 

Ok, so basically when i search for oxygen plant process (main product only GOX - gas oxygen), the process that i saw is using a compressor to produce 7 barg pressure.  The air will then further compressed then expanded when go through expansion brake turbine.  

 

I assume that the process is to produce pure oxygen (argon and nitrogen is considered as waste).  That's why i am asking whether we need pressure 32 barg.

 

Any opinion about this process?    Noted on the warm start up time.  If i assume the unit is small size with <100Nm3/hour do you think the time will be shorter?  

 

I appreciated your reply.