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.