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Liq Propane Transfer Operational Problems

lpg import (liquid propane)

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#1 sharmakartikeya

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Posted 16 May 2016 - 06:58 AM

Dear All,

 

I am working with the project of revamping of LPG import terminal.Under cryogenic condition liquid propane(-43 C) and butane(0.5 C) is being unloaded from ship tanker to the terminal storage tank.

 

The flash generated are being compressed to maintain the cryogenic condition of the storage tanks. While transferring butane, design capacity is easily achievable (1000 MT/hr). But when, we transfer propane a huge only 35 % of the transfer design capacity is achieved (350 MT/hr). However, the flash gas compressors are designed as per the theoretical vapor load generated by the transfer of the propane.

 

Any suggestions of thoughts on the issue. We are trying to achieve deign unloading capacity with propane. Let me know if any other data is required.

 

Regards,

Kartikeya



#2 Bobby Strain

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Posted 16 May 2016 - 09:31 AM

Well, cryogenic temperature is below -150 C. So your operation is just cold, not cryogenic. A sketch or drawing might help.

 

Bobby



#3 fallah

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Posted 16 May 2016 - 11:54 AM


 

Kartikeya,

 

You need to consider the facility by which the loading line to be cooled down to loading temperature.  This can be done by using a circulating pump to conduct the low temperature propane into the loading line with the return routed back to the source to prepare the conditions for main loading.
 



#4 Art Montemayor

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Posted 16 May 2016 - 12:01 PM

Kartikeya:

 

Bobby is right.  Your use of English is difficult to understand because of the typos, composition, and grammar mistakes.

 

The ONLY WAY to convey an accurate description of what you are working on is to draw a decent, detailed engineering flow diagram showing the major equipment involved and the calculated conditions (temperatures & pressures) of each flow stream.  Draw a sketch for the propane unloading as well as one for the butane unloading.

 

I don't know if you propose to unload both liquid propane and butane at the same time into the same terminal storage tank or if you are pumping out one product at a time into the same tank - but at different times.

 

You don't explain the origin of the flash gas, although I am very familiar with the normal operation and can calculate the amount if given the liquid pumping rates and the conditions.  What I think you mean to explain is that you would unload each product into the same terminal storage tank at different times.  However, when you unload propane you are having excessive flash gas generated.

 

You make the mistake of calling the operation a cryogenic one.  That is erroneous.  Although not well defined, Cryogenics is generally described as the temperature zone below -150 oC.  Your temperatures don't even come close to that.

 

That you will generate flash gas is fairly obvious.  However, you don't explain how you plan to cool and re-liquefy the recovered, compressed flash gas that must be returned to the storage tank.  Since the flash flow quantities for each product will be different, the flash gas compressor has to designed to handle each - or you employ a different compressor for each product flash gas.  Which is it?

 

If you furnish a detailed flow diagram together with your calculations for the flash gas generation and liquefaction, our members will have an easier time of understanding your application and what you propose.



#5 sharmakartikeya

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Posted 16 May 2016 - 11:22 PM

Dear All,

 

Many thanks for your valuable suggestions. Will get back soon with the process flow diagram with the process conditions.

 

However, please note that at a time, either propane or butane can be unloaded from the ship tanker to the terminal. Dedicated storage tank for each product at the terminal is provided.

 

Regards,

Kartikeya






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