7 replies to this topic

Dear all..

How do we store ethylene? With spherical tank, cylindrical tank, or horizontal tank?

In what temperature and pressure? What are the considerations when we want to store ethylene?

Thanks for your valuable responses.

[Qalander (Chem)]

Dear all..

How do we store ethylene? With spherical tank, cylindrical tank, or horizontal tank?

In what temperature and pressure? What are the considerations when we want to store ethylene?

Thanks for your valuable responses.

Please Google... Dear, You will get lot of useful info indeed!

Edited by Qalander (Chem), 19 August 2010 - 02:10 PM.

[HenryB]

Check SECTION 6 "Storage" of the GPSA. (I attached)

Regards

Attached Files

•  Section 6 Storage GPSA.pdf   1.74MB   452 downloads

[abhi_agrawa]

Ethylene is usually stored in Spheres. The storage sphere could be refrigerated (if you intend to store at low pressure) or just insulated (if you intend to store at higher pressure).

Hope this helps,
Abhishek

[Art Montemayor]

Allow me to answer each of your questions:

How do we store ethylene? With spherical tank, cylindrical tank, or horizontal tank?
You store ethylene as economically and as safely as you can. You can do this with a spherical or a cylindrical tank.

In what temperature and pressure?
If your required capacity is small, you can use a “bullet” type of tank – cylindrical, horizontal, and with hemiheads. It could work well at about 250 psig and -25 oF – so you could easily keep it refrigerated with mechanical refrigeration. A sphere is usually designed for much lower pressures (and temperatures) – any where around 50 to 100 psig and -100 to -75 oF.

What are the considerations when we want to store ethylene?
The size, type, and orientation of tank you employ all depends on the quantity, and the best conditions that suit your use. Economics demands you store the ethylene as a liquid and not as gas. Therefore, you should try to store it as a saturated liquid. To do that you should study and know your thermodynamics and phase equilibria. The colder the saturated liquid, the denser it will be and the more you can store in a given tank size. However, the colder it is, the more special alloys for the tank material and the more insulation you require - so the capital cost increases. Spheres are only justifiable for very large sizes of capacity. A sphere is desirable because it is strongest natural geometric shape; it can withstand more pressure with a given wall thickness than any other shape. However, it is tough to keep insulated and takes a very big footprint.

[fallah]

A sphere is usually designed for much lower pressures (and temperatures) – any where around 50 to 100 psig and -100 to -75 oF.[/color]

A sphere is desirable because it is strongest natural geometric shape; it can withstand more pressure with a given wall thickness than any other shape.
[/color].

Isn't there any contradiction between two above statements?

Regards

[Art Montemayor]

Fallah:

I don't see any contradiction in my two statements. They point to two different items the fact that you can make the vessel any thickness you want, and the fact that it is inherently strong.

But if you see or have identified any contradictions or something that doesn't make sense to you, please be specific and point it out. I'll be glad to explain it.

[kkala]

Having read this interesting thread after summer vacations, I would like to add that ethylene is also stored in refrigerated atmospheric storage. From discussions on the perspectives of a Greek Polyethylene Plant in 1981, I had concluded that a lot of Polyethylene Plants use this kind of storage, highly affecting plant competitiveness (1981).
Kind of storage seems to depend mainly on the quantity of stored ethylene (vapor pressure 40 Bara @ 0 oC and 50.76 Bara @ 9.5 oC) and economics. For small capacities a cylindrical bullet can withstand ethylene vapor pressure. For higher capacities spheres have to be used, requiring less wall thickness than bullets (I have "seen" such case for propylene). As capacities go even higher, spheres can be used but with lower vapor pressure, hence ethylene is semi-refrigerated (see post by Art Montemayor, 17 Aug-10). And for stored quantities in excess of above atmospheric storage is adopted (cylindrical tanks) of about - 103 oC.