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Dehydrating Heavy Fuel Oil


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#1 rid1kabir

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Posted 22 December 2016 - 03:30 AM

Hi,

I have been trying to dehydrate Heavy Fuel Oil using a vacuum dehydrator. But breaking the emulsion takes very long time.
The oil is heated to 95'c at vacuum of 28 inch. Initially free water is separated but the emulsified water doesn't even after several runs. I have checked the vacuum it's perfect and so the temperature .

Is it because of high interfacial viscosity? Any help in this regard would be helpful

#2 Neelakantan

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Posted 22 December 2016 - 04:37 AM

dear mr kabir,

 

additional information is first required:

1) exactly what you mean by heavy fuel oil; api; water content, etc; is the emulsion prepared by adding water to fuel oil? or did you get the sample from others; how did you estimate the water if you have not dehydrated it?

2) are you attempting the water removal in laboratory equipment; if so what is the procedure you are following and how you find that initally the water separates

3) what test runs you did and what are the results;

4) did you try adding demulsifier chemical?

5) have you tried inversion (that is adding more water, making water as the major phase in the emulsion; that is instead of the emulsion being water in oil, it is inverted as oil in water!)

 

regards

neelakantan

 



#3 rid1kabir

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Posted 22 December 2016 - 05:45 AM

Thank you so much for the support .
heavy fuel oil also known as Bunker C fuel or furnace oil.
API  -81
Density- 0.9718
Viscosity- 380 CST
Surface tension at 25 degree centigrade- 40nM/n
Water content - 0.5 % or 5000 ppm s tolerable

Currently is has 4% water 40,000 ppm

The water came from condensation in storage tanks . We have sent a sample to lab for water content test by ASTM D95 method.

2) We have tried to remove water both at lab scale as well as in our Dehydrator which has a flow rate of 190 litre per minute .

3) we heated up the oil to 95degree centigrade and applied vacuum of 28 inch Hg in gauge.

4) No we do not have knowledge of demulsifier. Never used it for vacuum dehydration . But we have heard of its use in crude oil.

5) Inversion ? No we never tried it. how will it help to being water levels down to 5000 Ppm?

#4 Neelakantan

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Posted 22 December 2016 - 06:53 AM

since the oil is already a product oil and in storage, it is essential not to add chemicals to that;  even inversion tech will not be suitable as we do it for large oil production units where the hot water can be recycled; certainly not suitable for your purpose

 

i donot know the quantum that you are planning to handle and the cost you are looking for dehydration;  based just on technical part, i would suggest three methods;

 

1) use dry nitrogen sparging; it may be effective but depends on the sparging method and size of the bubbles that you get into the oil

2) dessicant; use a dryer bed; you can ask your lab personnel to arrange for such a setup

3) but the best and time tested method is normally to go for centrifuging; i have seen in singapore an AlfaLaval centrifuge which we used for clarifying dirty oil; check at alfalaval and other such websites; there may be rentals too

 

regards

neelakantan



#5 rid1kabir

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Posted 22 December 2016 - 07:20 AM

Dear Neela,

Thank you so much for the insight

1. Does demulsifier have negative effect on the oil?
2. Our requirement is to process 18,000 litres per day. Can you give me link where to learn the inversion process?
3. Will centrifuge be able to remove water upto 5000ppm or 0.5 % ?
4. Is centrifuge better than Vacuum dehydrator? By Vacuum dehydration we are able to remove 90% of water almost immediately but a small quantity remains. I fail to understand how the oil is able to hold back onto the oil. In other terms the interfacial tension should have reduced at such temperature if I am no wrong.

#6 Neelakantan

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Posted 22 December 2016 - 07:44 AM

mr  kabir

 

there is an incosistency in your reply and questions:

 

1) you said 18000 litres per day; are you constantly allowing water to ingress in your storage?

2) i was thinking there was some failure of blanketing which has fouled one of the storages; not expecting continuous operation per day!

3) when you say 90% water is removed, it simply means that from 40000 ppm you have moved to 4000 ppm which is less than the spec of 0.5% (5000 ppm); so confirm what is the real spec you are looking at;  as a fuel oil, standard spec is 0.5 to 0.7%

4) from your answer, it appears that vacc dehydration is working; so why look beyond it!?

5) for alfaLaval i have gone through the web and got this:

http://www.alfalaval...dehydration.pdf

The capacity indicated is very high, as we normally go for such units for heavy oil production fields.

6) i am sure you can find similar industrial or laboratory centrifuges;

7) for inversion, just google oi-water inversion;; you will get reams of materials;

 

 if you tell your location, and industry, i can help more

 

regards

neelakantan



#7 rid1kabir

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Posted 22 December 2016 - 08:17 AM

Dear Neela

Sorry for the misunderstanding. We own bunker boat with 1200 tons capacity due to a recent leakage most of the oil absorbed water. So myou calculation is that we have to process at least 18 tons per day.

Sorry the calculation was wrong . Water upto 13000 ppm or 1.3 % remained that would be 67 % water comes out easily and rest remained.

#8 Neelakantan

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Posted 22 December 2016 - 09:51 AM

i would suggest using centrifuge only and also ensure proper drygas blanketing of the bunker hold

 

regards

neelakantan



#9 rid1kabir

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Posted 28 December 2016 - 10:02 AM

Hi,

 

we have re-run the dehydration with a few changes in the system. We have increased the temperature to 95 ' c .  Now the ultimate moisture level is 0.1 % or 1000 ppm but the entire process took very long time . Could you kindly suggest if using "Metal Intalox Saddle ring " would reduce the time required ? Would it reduce the interfacial tension ?  Currently we use metal plates in the dehydrator to increase the surface area .

 

Thank you for your support .

 

regards,

Ridwan 






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