Nitrogen Enriched Gasolines – What Are They and What Do They Do

Nitrogen Enriched Gasolines – What Are They and What Do They Do

Shell Oil has recently begun advertising their Shell V-Power “Nitrogen Enriched” Gasoline.

Why would nitrogen improve the cleaning performance of gasoline detergent?

Here are some facts to consider:

1. The earth’s atmosphere is approximately 78% nitrogen
2. Nitrogen is an inert gas that is not combustible
3. Nitrogen atoms are larger than oxygen atoms
4. Nitrogen when combusted with fuel and Oxygen creates Nitrogen Oxides (NOx)
5. NOx when combined with Volatile Organic Compounds (VOC’s) creates petrochemical smog.

Shell claims that fusing (their term) nitrogen with their detergent creates a more stable, longer lasting detergent that will be more effective in preventing gunk (their term) deposits (my term) from building up on the valves and other combustion chamber areas.

It would seem to me that adding Nitrogen will make the combustion process less efficient and could possibly lower combustion temperatures. This would seem to be the opposite of the desired effect.

It would also seem that adding Nitrogen could raise the NOx emissions from the engine which would tend to increase smog production, again the opposite of the desired effect.

I definitely applaud the idea of raising detergent levels in all gasolines. This is a quick and inexpensive way to reduce emissions and improve fuel economy.

The whole Nitrogen thing is nothing other than another marketing ploy. Shell and many other refiners have attempted to convince the consumer that they are doing something unique and wonderful, when in reality they simply want to sell more and or charge more than their competitors.

Shell needs fewer “Cutesy” TV commercials and more science, or at least they should provide some documentation to support thier claims.

If you want to do the best thing for your gasoline powered vehicle, look for fuels containing “Top Tier” fuel additives used at the manufactures “Top Tier” levels or simply purchase and regularly use aftermarket “tank additives” that meet or exceed the “Top Tier’ requirements.

This together with proper maintenance will ensure peak performance and minimum emissions from your engine.

Please let me know what you think, post your comments, ideas, and suggestions here.

Diesel Doctor

Copyright 2009 – William Richards

Asphaltene's and Plugged Fuel Filters

Asphaltenes and Plugged Fuel Filters

Asphaltenes in diesel fuels are becoming a much larger problem since the introduction of Ultra-Low Sulfur Diesel (ULSD - S-15) fuels.

There are actually several problems that have come together to cause the filter plugging black slime we so often see today.

Asphaltenes are highly polarized long chain components in crude and the heavier refined oils. Under certain circumstances these compounds associate themselves to form complex colloidal structures.

In Low Sulfur Diesel (LSD – S-500), High Sulfur Diesel (HSD – S-5000) and heating and bunker fuels the higher aromatic content of the fuel tends to discourage the formation of the complex colloidal structures limiting the problem.

However the EPA mandated reduction in aromatic content in ULSD has allowed this problem to happen sooner, more often, and in cooler temperatures than had been seen previously.

Asphaltenes agglomerate into an oily sludge. This problem is made worse when water is added to mix.

Petroleum and bio-derived fuels all hold water suspended in them, ULSD unfortunately holds approximately twice as much as the LSD and HSD fuels we had seen prior to June of 2006. Biodiesel (B100) can hold ten (10) times as much water as LSD and HSD, so even small amounts of biodiesel blended with diesel fuels dramatically increases the amount of dissolved water present.

Blending of fuels refined from different crude stocks further exacerbates this problem. Also, warmer temperatures in storage or due to the recirculation of fuel by the engine fuel system speeds the process and thickens the sludge.

Fuel that looks perfect going into a clean tank can develop tiny asphaltene droplets in a matter of hours when recirculation temperatures exceed 140°F (note: some newer engine fuel temperature as it exits the head exceeds 210°F). These pin-prick sized droplets can plug a 10 micron fuel filter in 3ooo to 4000 miles or less 50 hours of operation.

Many people mistakenly see this as a biological (bacteria and fungi) problem, however in the majority of cases the accelerated biological growth is the result of near perfect growing conditions that allows this rapid growth after the filter plugging asphaltene material has blocked the filter(s).

Keeping the water out helps, but the real solution is a thermal stability additive, a oxidative stability additive, together with a water dispersant.

Please comment with your experiences, suggestions, and or questions.

Diesel Doctor

Copyright 2009©

Long Term Fuel Storage

Long Term Fuel Storage

STORAGE LIFE

Under normal storage conditions diesel fuel can be expected to stay in a useable condition for:

9-12 months or longer at an ambient of 70ºF.

6-12 months at an ambient temperature higher than 85ºF.

Note: There are many factors that will affect storage life, including but not limited to:

· Ambient temperature

· Temperature variation - the wider the range, the more likely you are to have problems

· Above-Ground versus In-Ground Storage

· Dissolved water content of the fuel

· Humidity

· Quality of the fuel when added to tank

· Condition of storage tank

· Materials used in the tank and fuel piping system

As diesel gets older, fine sediment and gums will form in the fuel brought about by a chemical reaction between components in the diesel fuel with oxygen from the air. The fine sediment and gums can block fuel filters, leading to fuel starvation and the engine stopping. Frequent filter changes are then required to keep the engine going. The gums and sediments do not burn completely in the engine and this incomplete combustion can lead to carbon and soot deposits on injectors and other combustion surfaces.

The expected life of a diesel fuel can be indicated by the oxidation stability test ASTM D2276. The test measures how much gum and sediment will be deposited after keeping the fuel at 120°C in the presence of oxygen for 16 hours. It roughly corresponds to one year storage at 25°C. A result of less than 20mg/L of sediment and gum after the test is considered acceptable for normal diesel.


ACCELERATED AGING

The aging process can be accelerated by the following conditions:

• Contact with zinc, copper or metal alloys containing them. These metals will quickly react with diesel fuel to form unstable compounds.

• The presence of water. Water allows the growth of fungus and bacteria, these produce natural by-products such as organic acids which make the fuel unstable.

• Exposure to high temperatures.

• Exposure to dust and dirt which contain trace elements that can destabilize the fuel, such as copper and zinc.

• Fuel composition. Some components in diesel fuel naturally age quickly.


PROLONGING THE STORAGE LIFE

Prolonging the storage life is achieved by removing or controlling the conditions described in the previous section. Important measures to take are as follows:

• Ensure that the fuel is not in contact with any surfaces containing zinc or copper or compounds containing those metals (e.g. brass). If those metals are present then a metal deactivator additive may help.

• Establish a regular fuel maintenance program to ensure that water and dirt is removed from storage tanks. This will also remove any chance for fungus to grow.

• Water should be drained from the storage tanks weekly. The frequency can be extended if the tank shows no tendency to collect water but should be done at least monthly.

• Tanks should be kept full to reduce the space for water to condense, maintaining tanks half full increases the water build up and promotes corrosion in the top half of the tank. Most water will come from condensation as the tank breathes. The rate at which water collects will depend on local climate and will be higher in hot humid coastal areas.

• Tanks if possible should have a well defined low point where water will collect and can be drained. For example, cone down bottoms.

• Establish a system for filtering the contents of the main storage tank through a recirculating filter system. This can be made automatic and will reduce the potential for problems by removing sediment and gums. The filters should be checked and changed at regular intervals. When the filter change interval reaches a certain frequency then the fuel should be changed over.

• Tanks should be emptied and cleaned at least once every 10 years, or more frequently if there is a major contamination.

• Ensure that the fuel supplied conforms to a recognized specification to ensure the fuel matches the winter cloud point for the area to avoid filter blocking by wax drop out in cold weather.

• Always purchase fuel to replenish stocks in the winter season November - March. This will help to ensure that the fuel will not cause wax problems whatever season it is used.

• Obtain assurances from the supplier that all components are fully refined to promote stability.

• Establish a monitoring program whereby samples are taken at regular intervals to monitor the condition of the fuel. The samples can be examined at the site visually for evidence of haziness, sediment, darkening or sent to a laboratory for testing.

• Regularly turn the fuel over. If possible, plan the fuel usage so that it will all be used within 1-5 years and replaced with fresh fuel.


ADDITIVES TO IMPROVE STORAGE LIFE

The following additives can improve fuel storage life:

• Metal deactivators. These work by stopping copper, zinc and other reactive metals from reacting with the fuel.

• Fungicides/Biocides. These work by stopping fungus and bacteria from growing in the fuel and so prolong the life of the fuel. They are only effective on fungus and bacteria and will not stop other oxidation reactions from taking place. They are normally active at the water fuel interface where the fungus and bacteria grow. If fungus is present then a kill dose is required. Otherwise a maintenance dose is used to stop fungus growing.

The disadvantages of biocides are:

• Handling and mixing is hazardous because they are poisons.

• When using a kill dose, it is important to remember that killing the fungus can lead to a buildup of dead matter which will block filters and also cause the fuel to oxidize.

• Ideally, the fungus should be killed and then the tank emptied and drained out.

• Maintenance doses are effective but no more so than regular water draining and or the use of a Water Dispersant.

• Disposal of water bottoms requires special handling with due regard to the environment.

• Anti-Oxidants. These work by stopping the oxidation processes from taking place. They prevent the fuel oxidizing and reduce the formation of sediment and gum.

As always, your questions and comments are welcomed and encouraged

Black Fuel Filters - Asphaltenes - Re-polymerization

Black Fuel Filters – Asphaltene Production and

Re-polymerization in ULSD Fuels

Have you seen filters that look like this.

There is a difficult new problem with ULSD fuels. Today most ULSD is derived using the process of catalytic cracking. This form of refining uses very high temperatures, high pressures, and chemicals known as catalysts to refine crude oils into various fractions including Ultra Low Sulfur Diesel. The fuels derived using these processes suffer from a wide range of problems including a lack of oxidative and thermal stability.

This lack of stability manifests itself in many ways including an increased ability to hold dissolved water, an increased negative reaction with oxygen, and a far greater inability to handle high temperatures over time. Different refining processes and catalysts can make these problems better or worse. It appears that certain refineries produce fuels which are far less stable than that of others.

Diesel engines recirculate fuel to lubricate and cool the fuel system and engine components, In the past fairly large volumes of fuel were recirculated and this tended to keep temperatures lower, generally in the 140°F to 160°F. Today some of the newer engines can heat that fuel to temperatures that can exceed 200°F or even 220°F.

When some catalytically derived fuel is exposed to temperatures above 100°F for extended periods of time such as when fuel is recirculated in a diesel engine, the catalytic process starts up again re-polymerizing parts of the fuel. This results in rapid deterioration and darkening of the fuel. In this process small droplets of asphaltenes (heavy oils) are formed.

When the fuel is again pumped from the tank, the fuel filters will pick up the tiny asphaltene droplets, agglomerating them until the filter or filters are plugged. This can happen in 3000 to 5000 miles with some instances of plugging in less than 1000 miles.

While there are additives that can add thermal and oxidative stability to fuels, they are not commonly used by refiners or fuel distributors. These additives are not found in most aftermarket additives.