Hot oil heating coils Crude oil storage tank 1

[LittleInch]

Hi,

I've had a look around the forum but can't find anything direct but apologies if this has been asked before.

My situation:
Currently designing large (500,000 bbls) EFR Crude Oil storage tank approx. 85m diam by 17m high storing Crude Oil which needs to be kept at circa 55 C (130-140F). We think, even with insulation, this is around 250-300kW of heat just to maintain temperature.

We have no other utilities available other than what we generate and hence we plan to use an electric heated hot oil ( 200-250C) system circulating through heating coils in the base of the tank as opposed to having a steam supply or hot water supply just for this use.

So my questions are:
1) Is a hot oil system normal / acceptable for such a duty?
2) What is a good maximum surface temperature to use for Crude Oil to avoid scaling or coking?
3) How would I test my Crude Oil for a heating coil system design to avoid fouling / coking?
4) Any recommended hot oil system vendors / websites etc?
5) Any other tips for a heated Crude oil system of this size?

Thanks,

LI

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IFRs]

Hot oil systems work, so do steam and bayonet heaters. The heat balance calculation is fairly straightforward although there are many factors to evaluate and include or not based on the sensitivity of the system to them. Hot oil systems that I have seen is a fairly dense array of plain pipe, running at 350 to 350 DegF. Steam systems typically used discrete fin tube heaters running at 250 to 350 DegF so, there are some nice compact steam generators that just need treated water, a little electric and natural gas. Bayonet systems used bare or enclosed bayonets. Often the heater vendors will help you run calculations, size the system and give you tips on design and operation. Chromalox, Amrican Heating Compay, Heatec Inc would probably get you started.

 

[LittleInch]

IFRs - I was hoping you would respond!

Many thanks, that's what I was looking for.

Assume you meant 350F to 450F above for the hot oil skin temperature??



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IFRs]

The 350 to 450 I thought was the oil temperature. The serpentine pipes were about 5 feet apart and left enough room to walk around the inside of the tank. The fin-tube style puts localized heat that then forms more distinctive convection patterns. The quality of the stored liquid has a lot to do with the pipes or fins being coked up an dropping in efficiency.

 

[LittleInch]

IFRS,

thanks for reply. I just meant that your previous reply said 350F to 350F... Assumed it was a typo.

Just as an aside, what would you anticipate would be the temperature delta from hot oil inlet to outlet? 50C?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[IFRs]

The last hot oil system I found on my backup drive included the following specifications for the heaters: Flow: 600 GPM, Temperature In: 450°F, Temperature Out: 550°F, Fluid Paratherm: NF SP.HT: 0.66 BTU/LB/°F Density: 6.4 LB/Gal with a System volume: 500 ft3. The system was bid out to include two hot oil heaters rated at 75% of total load each, three skid mounted circulation pumps (2 active and one spare) and a skid mounted oil expansion tank. The two heaters were to be natural gas-fired, low-Nox with a minimum design pressure of 170 PSIG for operation at 150 PSIG.

Two examples of the type of help Chromalox can be:

https://www.google.com/url?sa=t&rct...wkLfeAhVnRN8KHZl9Ae4QFjAAegQIAxAC&url=http://

http://www.chromalox.com/catalog/re...-Heating.pdf&usg=AOvVaw3G5-QBSXw1qYepXIRDa7Ze

https://www.google.com/url?sa=t&rct...wkLfeAhVnRN8KHZl9Ae4QFjACegQIBxAC&url=http://

http://www.chromalox.com/catalog/re...-Density.pdf&usg=AOvVaw1LnQrmNmSZKedLE61hp6QE