7 replies to this topic

[Engr. Zain]

Dear Sir,

I have been appointed as research and design trainee engineer in a private organisation that is doing job as Fabrication, Installation and designing field.


The details are as follow:

Capacity of Tank: 500 BBLs
Ambient Temperature Range: -5 Deg C to Max 55 Deg C
Crude Oil Storage Temperature: 38-68 Deg C
Height of Tank : 10
Tank Dia : 40

Cladding Material : GI Sheet Gauge of min. 18
Internal FRP Coating @ 3mm Thickness to all surfaces (bottom side and ceiling)
External Coating for all the surface
* 1 coat of Zinc Epoxy Primer at 50 microns dft
Please Help me in finding the following:

* Type of Suitable Insulation
* Calculated Thickness
* basis for the Calculation
* Details of the Calculation


Please I need help in Insulating a Crude Oil Storage Tank.

Thank You,

Zain Ahmed Siddiqee

[Engr. Zain]

Please Answer me

[kkala]

You have given data, I think a bit more could help reply from an expert at insulation (I am not).
1. The tank is existing or under design? It seems that it is not heated (by e.g. steam coil, etc), please confirm.
2. Is it a floating roof tank (as expected) or a cone roof tank?
3. What is the purpose of insulation? Can we say that a minimum storage temperature of 38 oC is adequate for all crudes stored? Insulation will delay cooling, but will not reduce heat loss to zero.
4. -5 oC to + 55 oC is the range between max and min ambient temperatures ever recorded? Some minimum value (say 0 oC) has to be considered for the heat losses on which insulation thickness will be based on.

Edited by kkala, 26 November 2012 - 05:01 AM.

[Steve Hall]

Here's a free computer program:

http://www.pipeinsulation.org/

[Engr. Zain]

Dear KKAKA,

1.This tank is under design. it is steamed jacketed for heating

2. It is cone roof tank

3. Yes we need to maintain insulation to such critical thickness that crude oil temperature will not fall than min storage temperature i.e., 38 Deg C. keeping in view that minimum ambient temperature of surrounding -5 Deg C.

[kkala]

Since tank size plays a role, another question about tank dimensions. What are the units for H=10 and D=40? These cannot be meters, since tank capacity is 500 bbl = 21000 US gal =79.5 m3. Even if they represent feet, tank volume (cylinder) would be 406 m3. Could you clarify?
http://www.cheresour...ing-large-tank/ '> http://www.cheresour...ing-large-tank/ may be useful as an introduction. If tank is steam jacketed, temperature of outside metal (contacting insulation) would approach that of condensing steam and insulation has to consider this. But it would be hard to control crude oil temperature withing a restricted range, (e.g. 38-68 oC), despite the 3 mm FRP coat (not having heard of it). I suppose flash point of the crude is lower and nitrogen blanketing is applied on the tank.
Local refinery crude oil tanks (floating roof), needing heating from time to time (not all of them need it), have steam coils at the bottom. I think electric heating is safer today (more precise control of temperatures), though never seen applied. Needing to lower crude oil viscosity, steam coil or electric heating could heat mainly at the bottom, near the exit line.
Insulation design can be the next step after specifying way of heating. If you have decided on a steam jacket (rather risky for crude tanks), what is the temperature of condensing steam?

[S.AHMAD]

Zain
1. The purpose of insulation is for energy conservation (economics) and/or for personnel safety reason (hot surface must be kept below 60C). The crude tank temperature is maintained by the heating steam not by the insulation. Insulation helps to minimize the heat loss due to temperature difference between tank and ambient.
2.When I look at the operating conditions, there is.not enough justification to insulate the tank except for the steam jacket portion for personnel protection.
3. Please keep in mind the problem of under-insulation-corrosion problem that you may have to deal with in the future.
4. My advise is, reconsider the need to install insulation for the crude tank

Edited by S.AHMAD, 03 December 2012 - 10:19 PM.

[kkala]

Besides the above post by S.AHMAD, it is anticipated that a crude oil tank (of up to 60 oC max storage temperature) in a local refinery would be only peripherally insulated from ground to a height of about 2 m. Heating would be by steam coil at tank bottom.
This is what we were instructed to do for a slops tank (14000 m3, floating roof, 2008), which could alternatively be used as crude oil tank. Storage temperature could be set to lower values than 60 oC. See http://www.cheresources.com/invision/topic/9826-slops-storage-heating-and-handling for more data and safety issues.

Edited by kkala, 11 December 2012 - 05:54 AM.