Heavy fuel oil sedimentation

What's your design - normal, high and low temperatures?

BigInch-born in the trenches.

The sedimentation will entrain good fuel with it, then you will have a big bill cleaning the tank, and a big bill writing off the 20,000 barrel or so loss.

HAZOP at

Sounds like there may be 100 MBBLS of dirty stuff right now, so it might be a worth it.

BigInch-born in the trenches.

Sedimentation is a rather broad term, as is "better quality fuel". What particularly are you interested in removing from the HFO by sedimentation....water, inorganic solids, high molecular weight organics such as asphaltenes, etc.? What is the incremental improvement you are looking for, and at what incremental cost of treatment. There may be better ways of achieving the fuel quality improvements you're looking for.

As OWG states, there will be a measurable economic loss of "good fuel" with the sedimented material, which, unless you are a petroleum refinery that can recycle the slops, will be a cost of disposal issue for you.

You should also consider that heating 100,000+ barrels of fuel will induce substantial agitation of the liquid within the tanks, which in turn will reduce effective sedimentation.

Orenda

Hello everybody:

Thanks to all for your comments.

BigInch: I beg your pardon but, what temperatures are you talking about?

orenda1168: By sedimentation, mainly we are interested in remove the water from the HFO and, of course, some solid impurities and contaminants; because they put the fuel separators under severe working conditions and it entails to have faults. These contaminants also play a very important role in the performance of the fuel filtration system.

The temperatures you will heat the oil to, the minimum ambient temperature and the maximum ambient temperature. If the ambient temperatures are too cool, higher viscosity will increase the settlement time, so there may be a break-even point for the optimum temperature at which to conduct the settling process determined by heating expense versus the time at which a certain % of total solids settling occurs.

BigInch-born in the trenches.

Hello everybody:

BigInch: The idea is to heat the fuel oil to 50ºC (so far, we really do not know the optimum temperature). The minimum air dry bulb temperature is 21ºC and the maximum is 40ºC. For the wet bulb we have minimum of 20ºC and a maximum 27ºC with an average Relative Humidity of 67 %.

Sounds like interior temperatures. I mean the outside winter or cool-rainy season temps and the hottest temperatures during the warm season.

In any case 100 MBBLS from 20 to 50 is a heck of a lot of heat. Too bad you can't burn the dirty stuff to help out the with fuel bill. Maybe you can draw some off the bottom after 1 day and burn it to make the heat needed for the next 2 or so.

BigInch-born in the trenches.

I have a lot of questions to 21121956 I would like to see the answers to:

- Are the tank bottom plates sloped so as to enable removing contaminants with minimum fuel losses ?
- What do you plan to do with the removed slops ?
- Do you have the kin. visc. and density at two temperatures to estimate the optimum for sedimentation ?
- How do you plan to heat these large volumes ?
- Have you estimated the heat loss from the uninsulated tanks over the two/three days of settling ?
- Have you measured the water-and-sediment content ?
- What is the final ppm water desired ?
- Have you carried out lab bench tests to evaluate the efficiency of the settling process ?

Hello everybody:

Hi 25362, nice to hear from you again.

The Heavy Fuel Oil that we have these days stored has a density of 997,3 kg/m³ @ 15º C, and a kinetic viscosity of 554 cSt @ 50º C.

Regarding with your questions, these are the answers:

1. The tank bottom plates have a slope of 1 inch every 10
feet.
2. The sludge will be used as fuel for boilers. The water
will be discarded.
3. The fuel at 99º C has a density of 943 kg/m³ and, at
125º C has a kin. visc. of 20 cSt.
4. In some way, the plant has an overproduction of
saturated steam and the idea is to use this excess.
5. The stimated heat losses for the surfaces of the tank
and the surface of the fuel, are on the order of 545 kW
and 610 kW respectively.
6. No.
7. We only want to get rid of the water on the bottom of
the tank, later on, depending on the quality of this
water, will be used a proper chemical treatment, before
its disposal.
8. No.

I hope this will be useful. Thanks .... Gracias

Thanks for remembering that I speak Spanish. All your points noted.

Are you sure that the slope of the bottom plate is enough to collect water w/o losing much oil ?

The kinematic viscosity at 50 Celsius is still quite high. Be careful not to reach water boiling conditions in the storage tanks.

Note that -beside an increase in dissolved water- the turbulence resulting from pumping and heating may have a mixing effect for the ¨suspended¨ water droplets, contrary to the initial (water settling) purpose.

Buena suerte.