Water content in diesel oil (fuel)

The idea of burning hydrocarbon fuel in air in the first place is to combine the force from the explosion with the expansion of the resultant gases to move the piston or turbine or whatever. The heaviest lifter after combustion is the expanding superheated steam that is created. A few hundred ppm of extra water in the fuel should in reality have very little effect on the power output. The superheated steam will still combine with nitrogen to form corrosive acids in measurably increased but insignificant quantities. There should be very little effect on the detonation point of the injected mixture. An effective water trap in the supply line before the pump should be able to separate out and filter out small quantities of water prior to injection. If it's computer controlled direct injection the feedback system will control any required timing corrections. If it's a mechanically controlled prechamber type injection the pump adjustments are pretty vague and seldom accurately repeatable over two or three engine revolutions so adjustments of ~0.25-2.0 degrees are moot anyway.

an aproach to your issue is to look at water as a friend rather than foe. Emulsified fuels provide many benefits, not least vastly inmproved emissions especially in older technology fuel systems and large stationary engines for power generation/marine engines. Unless you emulsify though with an additive to keep the water in suspension you need to follow wrench490's advice.

<...filter out small quantities of water...>

Q1) How does that work? A <...filter...> is designed to block by the action of separating solids from fluids.

Q2) Where does the <...water...> go?

If there is a water content present in the cumbustion chamber of a diesel engine the water content the pressure developed during the compression may not be chaged but the power developed during the cumbustion of the fuel will definitely have fluctuation. Moreover if the water particle enters during the engine run the effect may be negligible but when it enters at the time of starting the engine it will have some power loss at the time of starting the engine.

If you using the engine outside or in a cold environment I'd be more concerned with the fuel gelling given the increased water content – given you even bigger headaches then just a little bit of power loss.

Water corrodes engines. We have seen several catastrophic failures on engines with high water content on large vessels which have caused enormous amounts of lost revenue. This is because of ignorance. Someone mentioned 800ppm.. In reality, we have seen thousands of ppm in many cases. The client could not see the high water content because it was free water contamination that can only be picked up by online water sensors

Water in diesel fuel ~> BAD

Yes, gelling is a problem for sure, but the contribution of water to increasing acid content is another concern. Clearances in diesel injection pumps are very small and acids create problems with the close tolerances of these pieces of precision equipment.

Tier 3 (and coming soon Tier 4) engines in newer equipment are less tolerant of moisture, and filtration to eliminate moisture from fuel has become more sophisticated.

These engines use common rail fuel injection systems operating at very high pressure, and at this high pressure water getting to the injector will explode the injection nozzle.

There is interesting information on fuel, filtration, and additives on the net.

Check some of these links;

http://en.wikipedia.org/wiki/High_Diesel_Injection#Common_rail_direct_injection

I would just add this. Water in diesel fuel is bad (above a certain limit) In the big volvo engines used for power generation a bit of water give us a 100 rpm more, possibly becuase the injectors get a bit of a steam clean, some suggest it is a slight improvement in compression. A number of companies around the world now offer a emulsion fuel that burns very clean and the engines love the fuel. In the ship engines that really works well.

The problem (apart form everything mentioned on this blog already) is the tipping point where a water droplet size becomes an issue. On commonrails that droplet under high pressure becomes a abrasive material and will resize the injectors for you.

The ASTM and ISO specs for water content is a bit misleading. We measure the way water behaves in water activity (WA). This is a measure of how big the size of a water droplet will grow in a specific enviroment and also determines the ability for microbes to grow in the fuel on suspended water. The typical WA for road diesel is 0.63. It is just to small for a microbe to estbalish itself, fungus need about 0.67. The problem comes in when bio fuels are added. FAME for instance support a water droplet with a WA of 1.01 in most cases. Not only does it support a number of organisms in the fuel now but when the winter cold hits ice crystals or gelling is far more extreme.

The general advice is, the more you use bio fuels the more importnat it is to keep your fuel dry. It is a near impossible task if you cannot fit a filter on a ship/boat/car. The alternative is surfactant based additives that will reduce the water droplets to nano size. Just be carefull not to overdose.

This post popped up in a search - hope you don't mind. My company is having problems with excess water in ULSD (ultra low sulfur diesel - less than 15ppm sulfur).

The water provides air for microbiologicals ("bugs") to grow and plug filters and cling to metal parts, esp. aluminum. Their carcases can actually cover the bottom of a storage tank. Only treatment is with a biocide. Water also raises the cloud point of the fuel.

I'm told "normal water content" is 50-100 ppm. We are seeing some fuels with 250-300 ppm. Water is not good for diesel!!

Thanks for your indulgence.

Here is a marketing bulletin from Fleetguard that may have some value for you, learn something everyday, right?

http://www.cumminsfiltration.com/pdfs/product_lit/americas_brochures/MB10-04-3.pdf

It gives some detail about one source of your water problem, your fuel supply itself (seems it can't be helped). Other water content can result from condensation which can vary dependant on where your stock tank is located, your climate, how full you keep you stock tank on average, etc. You can get lots of advice on these variables, I'm sure.

The bulletin also has information on the microbial habitat being at the fuel/water interface, how to take samples, test and treatment options, using their products, of coarse.

Take it for what it's worth, hope it all helps.

FYI.... CC2661 Fleet-Tech Microbicide - 1Qt bottle is supposed to treats 2500 gallons (these will be 32oz quarts (US Gallons) and I think is about the CDN$0.08 cost per gallon treated mark. You will need to call some suppliers to check price and availability if you take an interest. (Hope it's not against the rules to make a price guesstimate)

i am student in marine engineering and the problems of high water content in marine diesel engines are:

First of all water in fuel is a contamination and does not yield any energy. the percentage of water in fuel can be translated into energy loss for the consumer.

water content on board ships is partially removed by settling and centrifugal purification.

if water content is still high when entering the engine serious probems may occur:

As water is heated in pumps before entering the engine water vapor can occur. water vapor can cut out the pumps

erratic combustion if water-contaminated fuel reaches injectors

retardation of the speed of combustion resulting in still burning particles striking cylinder wall and crown

dilution of cylinder oil film leading to high wear rates of cylinders, piston rings and piston crowns

Also water has corrosive action and the use of water contaminated fuel for extended periods of time can cause corrosion in f/o lines, pumps, injectors

Water in diesel fuel is not your friend especially in the emulsfied state. Emulsified water is the hardest to filter out and if you do not have a good water seperating filter it will pass through to the engine. The newer CRD engines seem to be more sensitive that the older diesels. What usually happens is the water will attack the injectors and cause corrosion. The newer injectors have very tight tolerances and connot tollerate any corrosion.