2 replies to this topic

[vaibhav]

Dear Respected Members

 

I am working on project for crude oil storage tank farm facility. in the terminal there are total 10 no of tank used to store crude oil product.

product specification is as follows.

 Viscosity = 50 cSt

Density =  860-891 Kg/ m3.

Vapor Pressure = 71 Kpa.

Volatility = Highly Volatile.

 

the existing tank information is  ( tank is having external floating roof ) ( API 650 design tank )

tank diameter = 72 meter

tank height = 22.3 meter. refer tank data sheet for more details.

 

end user require this tank to be use for large cargo loading / unloading operation. flow rate for ship loading & ship unloading operation is change from 5000 m3 / hr to 12000 m3 / hr. because of this change in flow rate , there will be change in tank venting rate ( inbreathing / out breathing ) , no & size of vents, inlet diffuser etc.

 

I have question how to size inlet diffuser for this new requirement . what sort of modification is require in existing inlet diffuser & tank  PVRV valves, sizes in order to comply with end user requirement. is there  any other modification need to be done in the storage tank ? 

   your advice or  suggestion is highly helpful to me in presenting the technical proposal to the client.

 

Note- any other alternative solution to cater above requirement is also welcomed. For doing above modification works in the tank require  emptying, gas freeing, sludge removal operation which is time consuming process .

 

Thanks in advance for the technical advice.

 

regards

VP

 

Attached Files

•  Tank data sheets T101 to T110.pdf   2.18MB   45 downloads

[Neelakantan]

i shall go through the data sheets;

if i understand your question, you are talking about an existing tank with floating roof (with buoys, probably as the dia is 72m); you are looking at modifying its fill and drain rate? if so what is the original max design fill and discharge rate?

 

floating roof tanks vent dont exactly work for venting due to fill or ingress due to discharge; the idea of floating roof is to keep them minimal!

the vent and ingress is planned differently; infact there is no real compression or emptying of "vapour space" due to filling and emptying. the vents and pvrv are designed for "sitting" and "lifting" from the supports. Also to provide for thermal relief due to pockets held in undulations of the roof (if you ever walk over a floating roof tank you will know what i mean!)

 

your worry should be about the connecting pipes! what about the existing inlet and outlet connection pipes; they also need to be changed; which means cutting the  inlet and outlet!

 

the next point to worry about the static electricity produced due to movement of the roof; since it will be faster, worry about the effect of friction on the seal.

 

regards

neelakantan

[vaibhav]

Dear Neelakantan

 thanks for your reply. 

 

please note the following points.

 

1. there are total 10 no of crude oil storage tanks . out of 10 no of storage tanks, 6 nos of storage tanks having geometric capacity of 91238 m3  . tank dimensions are 72 meter  dia x 22.3 meter height.  these tanks having product inlet line size of 36" . ( TK - 101 TO TK 106 )

 

2.  There are 4 no of crude oil storage tanks having geometric capacity of 10642 m 3 . tank dimensions are 26 meter dia x 20 meter height. 

        these tanks having product inlet line size of 24" . ( TK 107 TO TK 110 )

 

FOR TK 101 TO TK 106 tanks, emptying / filling rate for the product is 4000 m3 / hr  while for tanks TK 107 TO TK- 110 , filling / emptying rate for the product is 2000 m3 / hr.  All relevant information can be found in the storage tank data sheet which I  had attached in my previous post for this topic.

 

All above tanks are having external floating roof.

 

main question is that filling / emptying rate needs to increased to 12000 m3 / hr for the tanks.

 

what will be the effect on inlet diffuser / vents/  Floating roof design or any other tank design factors in order to make the above tanks compatible for the increased  inflow / outflow rate of the product.

 

Thanks in advance for the technical advice.

 

looking for the valuable advice form the respected members of the community ASAP.

 

Regards

VP