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Low Pressure Gas Storage Tank


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#1 rikakose

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Posted 28 February 2018 - 07:53 AM

What are the advantages of storing petroleum gas at low pressure? 

Our business partner insists to have an atm petrol gas storage tank without any proper explanations. 

I have never seen something like that before. 

 

Can someone give some instructions/explanations about low pressure gas storage?


Edited by rikakose, 28 February 2018 - 07:54 AM.


#2 Art Montemayor

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Posted 28 February 2018 - 07:13 PM

If you are an engineer, then please be SPECIFIC.  No one on this Forum can be aware of what you mean by "low" pressure.

 

What is low to one is high to another.



#3 Bobby Strain

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Posted 28 February 2018 - 09:31 PM

Maybe you are talking about gasoline storage?

 

Bobby



#4 Technical Bard

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Posted 01 March 2018 - 01:04 AM

I am confused.  Art is right - be more specific.  Are you talking about "Gasoline" (Petrol in british terms), or LPG (liquified petroleum gas)?  

 

If Gasoline - it is always stored at atmospheric pressure.

 

If LPG, it is usually stored pressurized (i.e. at vapour pressure at ambient temperature), but can be stored at atmospheric pressure using refrigeration to keep the temperature down (especially for large volumes).  For example, propane can be stored at atmospheric pressure but you need to keep the temperature below -43ºC.



#5 rikakose

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Posted 05 March 2018 - 05:14 AM

The gas tank is atmospheric or slightly over pressure like most atm storage tanks  and at ambient temperature.    

 

Petroleum gas is the LPG without L- Propane and butane not liquefied. 


Edited by rikakose, 05 March 2018 - 05:17 AM.


#6 fallah

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Posted 05 March 2018 - 07:25 AM

rikakose,

 

At first ask your business partner to provide the detail of the gas storage system , then ask this forum members to assist about the points not clarified for you...



#7 rikakose

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Posted 05 March 2018 - 07:53 AM

Fallah,

 

Because I couldn't get any proper explanation. And in my opinion it is simply wrong to store gas in an atmospheric tank. 

I have never seen an atmospheric gas tank before. I think it is probably because I  am not experienced enough. So I post my question here in order to get some indications from more experienced engineers. 



#8 fallah

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Posted 05 March 2018 - 09:59 AM


 

rikakose,

 

Well, can you provide us with the info of where this stored gas is intended to be utilized?

 

It might help to guess about the concept behind such storage...!



#9 rikakose

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Posted 05 March 2018 - 10:11 AM

Fallalh:

 

It will be used in Burners.  They can save a compressor if the gas is stored in atm pressure.

 

What I am curious about is that in the reality, is atm gas storage tank existing or not? 

 

Is that right to store gas in an atm tank? It is not right to make a wrong design just for reducing the cost.



#10 fallah

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Posted 05 March 2018 - 10:41 AM

rikakose,

 

Nothing is wrong to store gas in atmospheric tank, but i guess if even the tank is an atmospheric one; the gas has to be stored in it at a pressure a little bit higher than atmospheric due to burner requirement.  Anyway, I think it is a surge tank after a, let's say, gas gathering system with a variable pressure source will lead to having a stable pressure at the burner inlet while without having such surge tank it might pressure fluctuation at the burner inlet would affect burner operation and performance. This is just my guess...!



#11 rikakose

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Posted 05 March 2018 - 11:02 AM

Thanks fallah,

 

gas is from single source with pressure slightly higher than atm.

If there is nothing wrong to store gas in atm tanks, I won't have more concerns. 



#12 fallah

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Posted 05 March 2018 - 11:20 AM


 

rikakose,

 

Nothing wrong but it's not a normal practice to do so...!



#13 Art Montemayor

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Posted 05 March 2018 - 01:48 PM   Best Answer

Rikakose:

 

In spite of you not explaining exactly what gas you are dealing with, I believe I know exactly what is being proposed by your partner.  You stated that you have:

 

“Petroleum gas is the LPG without L- Propane and butane not liquefied.”

 

You are not clear in explaining.  What is “LPG without L”??  I believe if you are correct in identifying the gas as basically gaseous LPG - that is, a mixture of propane and butane that is not liquefied, then all you are dealing with is a very common and practical way of handling a fuel gas prior to distribution to burners.  This method was used extensively in England and the USA in the first half of the last century to distribute synthesis gas or natural gas.  In my hometown, we had a very large gas holder that once serviced the municipality with natural gas.  Today, with the advent of modern instrumentation and pressurized systems, gas holders are rarely, if ever, used.

 

If you are not familiar with a gas holder or know how it works, suffice it to say that it works basically just as Fallah has mentioned - as a low pressure surge vessel.  The gas holder has the ability to handle varying flow rates of gas by using a water seal to allow the inner, inverted tank to expand its volume capacity.  This action keeps the gas holder working at a steady, constant low pressure prior to distribution.  If you are interested, I can furnish a detailed sketch of a gas holder to show you how it works.  Let me know if you are interested.

 

I have used gas holders in industry.  One that I used was to handle gaseous oxygen prior to compressing it for pipeline distribution and cylinder filling at high pressures (2,000 psig).  I believe what your partner is thinking is that you can use the existing atmospheric tank in the same manner - except that you have a FIXED volume to contend with.  The fixed volume of the atmospheric tank forces you to have to increase the surge pressure in the tank should the inlet gas feed to the tank increase while you are burning a steady flow of fuel gas.  This means that a fixed volume surge (or temporary storage) tank is a potential area of problems.  You cannot exceed the MAWP (Maximum Allowable Working Pressure) of the atmospheric storage tank - no matter what the other conditions may be.

 

All you can do is fill the tank with your fuel gas up to the MAWP and then start to use your burners while maintaining a constant, steady flow of feed fuel gas into the storage tank at a pressure below the MAWP, but above the pressure required at the burners PLUS allowing for the pressure loss in the distribution piping leading from the tank to the burner tips (don’t forget, you have to allow for a pressure drop through a gas regulator also!).  This kind of proposal is open to a lot of risks, hazards, and operating problems.  I would never recommend anyone to use this type of system.

I strongly recommend you read some of the many threads we have generated in our Forums regarding the proper, safe use of so-called “atmospheric” storage tanks and how to identify the MAWP in such tanks.  For the sake of safety and elimination of hazards, you must certify the correct MAWP of the storage tank in question before attempting to employ it in the proposed service.  I hope we are all clear and fully understand this.



#14 rikakose

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Posted 07 March 2018 - 11:26 AM

Many thanks Art, 

 

This is very clear.  To be honest, this is the first time I hear the name "gas holder"

I will be grateful if you can make the sketch. 

 

Two more questions: 

What are the major safety concerns and operating problems about the gas holders?

Any size limitation? we need around 250 m3



#15 fallah

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Posted 07 March 2018 - 12:20 PM

 

Two more questions: 

What are the major safety concerns and operating problems about the gas holders?

Any size limitation? we need around 250 m3

 

 

rikakose,

 

The safety concerns and operating problems are similar to those of a floating roof tank...

 

The gas holders are to be manufactured up to the volume of 50,000 cubic meters...



#16 rikakose

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Posted 08 March 2018 - 03:41 AM

Thanks Fallah.  :)



#17 Art Montemayor

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Posted 08 March 2018 - 10:09 AM

Rikakose:

 

There is an excellent, detailed discussion of fuel gas gas holders - complete with sketches - at:

 

https://en.wikipedia...wiki/Gas_holder

 

Your application is explained therein.  I hope this helps you understand the principle and its application.






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