10 replies to this topic

[arvind]

Dear All,

I wanted to know is there any specific requirement of bottom (shell side) entry for crude oil storage tank.

additionally how could we destinguish between top side inlet and side inlet for storage vessel / tank.


Thanks in advance,

Arvind

[fallah]

arvind,

A requirement i can refer to is a check valve which should be located at the bottom shell entry to prevent back flow from the tank.

Indeed, in top shell entry situation you normally need to consider siphon break facility at the high point of the inlet line.

Fallah

[arvind]

Fallah,

Thanks for your prompt reply.

Additionally my concern is selection of inlet nozzle location, whether it will be at bottom shell or at top side entry through roof for bigger tanks like crude storage.


Thanks.

[fallah]

arvind,

Normally it will be at top section of the shell side below oveflow nozzle elevation with extending inlet pipe till near the bottom. In few cases it can be at lower section of the shell side as well.

Fallah

[arvind]

Hi,

Yes in our case feed inlet is at the bottom and I am wodering what will be the reasons?

Reasons what I fill are:

1. due to larger diameter of the inlet pipe to avoid additional support and design of shell and roof it is fevorable to consider bottom shell side entry.
2. Tank is of 50000 Barrel capacity, Ht = 22.5 mtr., hence to avoid impact of liquid at bottom plates. etc.

please suggest me in this regards,

Arvind

[S.AHMAD]

Top side entry design for crude tanks is more complicated since the crude tanks are normally floating roof.

[arvind]

Hi,

But in our case crude buffer tank is fixed roof storage tank with botom shell entry. I wanted to know the reasons for the same.


Arvind

[Technical Bard]

Depending on the properties of your crude (light is more likely to have this issue than heavy crudes), you may need to consider the risk of static electricity due to a top fill. It is not advised to have naphtha or diesel "splash" filled into tanks for this reason.

[S.AHMAD]

1. I cannot find any advantages for splash loading especially for flammable liquid.
2. The danger for top filled (splash) is the formation of vapor during loading. This creates fire/explosion hazards in the vapor space. Static electricity is one source of ignition and lightning is another one.
3. In addition, hydrocarbon loss is also high and the cost of piping is also increased.
4. For these reasons that, flammable fluids is normally stored in floating roof tanks.
5. Splash loading is OK for water.

Edited by S.AHMAD, 04 April 2012 - 01:51 AM.

[Zubair Exclaim]

I usually design with bottom filling for crudes with or without floating roof, splash filling will cause you additional problems like foaming, vapor losses, not to mention the stress impact at the splash impact point.

But yet again i haven't seen any code or practice preventing form doing that too..

[kkala]

We had tried to feed a floating roof tank from top (via a guide-pall), since we were afraid that feed near bottom could create back flow. Liquid was rain water collected from crude tanks, so it contained crude and it was similar to crude from safety point of view. Finally we abandoned the top feed, due to problems told in http://www.cheresour...lated-problems/ '> http://www.cheresour...lated-problems/ . Feed was realized near tank bottom, also three check valves were placed on the feed line.