We have not done this before, but will have done this week. I think those of you familiar with this call it "polishing"?
Anyway, the idea is to run the diesel tank contents through a process that takes out the water and algae and trash. Not sure how complete this is, but it will hopefully remove the habitat for the algae to grow at the water/diesel interface plus any debris and algae.
I think it takes about an hour. Will report back the results, am interested in seeing what is collected out of my tank!
Mike,
Yup, a very common procedure on diesel powered boats.
Batch polishing typically use filters and coalescing units to remove water and contaminates, although industrial units can use vacuum chambers to remove water, and filters and centrifugal units to remove solids, Almost all larger boats and ships use centrifuges to remove water and solids from fuel before it is pumped to "day" tank for use by engines. Fuel filters are still used on engines for final filtration.
Hi Brett.....yep, that what I recall you boat owners had, are familiar with it. But I a long way from the ocean, so good I can get done in Nacogdoches. Think never woulda gone to coast to get
jcus......I not aware what the mechanics are of this system, probably like that, but it recirculates to the fuel tank, not a separate tank. So multiple passes to get er done.
On ships, there are multiple fuel tanks, these are centrifuged to one day tank that feeds the engines. In your case, probably just sucks off the bottom of your tank, through filters etc, then back into tank.
I would think you would need to clean your tank too not just polish the fuel. I have polished fuel on boats at sea and put it into a second tank. We only had two tanks and the day tank would feed the engine for a long time.
Smaller container ships may hold 200000 gal or more of fuel in 6 to 10 or more different tanks. Day tank [or tanks] may hold 8000 to 10000 gals. Engines at cruising speed may burn 8000 gpd, so centrifuge runs almost constantly to fill day tank except for cleaning the centrifuge. If any tank becomes contaminated, you must basically isolate it and recirculate that tank though polisher. In drydock, much easier, just pump all tanks through cleaning equipment to shore side tanks. If tank is badly contaminated, they would be pressure washed and pumped out before refilling. Of course, these tanks have access ports and manholes. Little harder to do on our coaches.
I am guessing your not going to get much fuel polishing accomplished in an hour.
John, it would be good to clean the tank too but with this system cannot do that. Further, there was education that algae adheres some to the surface of the tank, so it can still be there. On the other hand, with the water gone, that makes a difference plus I would like to know how much I had. Also, there was operator report that some algaecides have negative effects on some parts of diesel engine......I need to better understand that statement, and be sure I not using a problem chemical.
Phred, I forget the circulation rate but for a small tank....relative to a ship....it sounded reasonable. I thought as I heard the task in an hour it would circulate the fuel through the system several times. (of course if each pass through removed say 90%, even after several passes contamination remains.)
Even the small 120 volt polishing units flow 200-300 gal per hour, so thinking you will get pretty good results in an hour.
Which brings up the question about how full the tank should be, if not an emergency situation, before scheduling the polishing session. You would get more complete cycles with less fuel, and since the contaminates are generally heavier than the fuel, it seems like you might get a more complete clean up with less fuel in the tank. But perhaps there are other considerations...
Don
All day would require the same labor amount, unless they have somebody sitting around watching. As you stated this is a dilution process that takes time, and the more times it cycles the fuel thru the filters the better, up to a point.
Diesel is somewhat of a solvent. Solvents get weaker as they absorb more contaminants
Therefore my vote is to start out with a full tank. And a longer filtration time.
Result of fuel polishing.....
cycled fuel at 19 gal/minute, ran 45 minutes and operator wanted a full fuel tank, which I keep
collected what the operator said was a small amount of water and ascribed it so due to the keeping the tank full when stored. the process, my terms, brings the diesel and water out in sort of a cloudy mixture and the water settle out as you let a sample sit a few minutes. In total I would guess no more than three ounces of water.
In the water phase was however some very fine white solid material. Jackie said just guess but maybe 1/8 of a teaspoon. It seemed granular and moved about sort of like sand, if you tilted the jar, it just slid down the bottom to the new lower side. Operator is going to try to get some out and examine it more.
collected algae on the 5 micron filter, sort of embedded in it but so little that it more a stain appearance, not much, plus some larger small amount that settled at the bottom of the foot long filter. Operator said that overall quite small amount. We discussed the biocide and how I have been using it.
there was some algae at the intersection of the water/diesel layer, where the algae grows. In a "mason jar" sample you could easily see it, not more than a 30% complete layer between the two liquids. So a very small amount from 175 gallons.
The operator mentioned that there would still be algae in the tank, on the walls, and that I need to continue the biocide. While doing a good job keeping the tank full, that does not protect me....of course....from getting bad fuel (with water).
Hope this helps. I was glad to get it done, I had no idea what was in there on a coach 17 years old.