Biodiesel and Cold Weather meet in Minnesota

Biodiesel and Cold Weather meet in Minnesota

The Minnesota Department of Agriculture recently released (February 15, 2009) a report to the legislature regarding the states mandated biodiesel program and the cold weather issues it has caused.

Starting in September 2005 Minnesota required that virtually all diesel fuel sold in the state contain at least 2% biodiesel. This level is supposed to be raised to 5% in 2009, 10% in 2012, and finally 20% in 2015.

This report by the Governors “Biodiesel Task Force” created in 2003 shows that there a number of significant problems with using biodiesel blends, particularly in areas subject to long periods of cold weather.

Some of the issues noted in the report:

· Discussion indicated at least fifteen cases of unusual filter plugging in commercial trucks this winter for which the cause had not been determined. Discussion of possible causes included engine manufacturers’ reduction of truck filter sizes (from 10 to15 microns down to 2 to 5 microns), paraffin from diesel, glycerin from biodiesel, water contamination, biotic contamination as a result of ultra-low sulfur diesel levels plus water contamination, and vehicle designs in which the fuel filter is located away from the engine.

· Discussion that existing cold flow test procedures are not sufficiently predictive of the
cold temperature performance of diesel fuel with or without biodiesel. ASTM International and other organizations at a national level must develop new test methods that are more predictive of the cold weather performance of diesel fuel and biodiesel blends.

· Variations in seasonal availability of fuel were also discussed, specifically routine shortages of diesel fuel at terminals in the fall leading to the practice of bulk plants and fleets buying and storing fuel in the late summer for use in the fall and early winter months when shortages of diesel are anticipated. Such stockpiling of B10 or higher could result in problems in above ground tanks.

· The suggestion was made that the Task Force discussions should freely address the availability and quality of all winter fuel in the state instead of being confined only to biodiesel. Given recent changes in the diesel industry, including biodiesel, low-sulfur diesel fuel and smaller fuel filter pore diameters, a wide range of issues regarding equipment and diesel fuel with and without biodiesel must be addressed.

Laboratory testing has indicated that blending with number one (#1) diesel at 50/50 rate produces results similar to treating with additives but the #1 fuel is at a far higher cost.

There is also a concern over whether the current testing (e.g. Cold Point (CP), Cold Filter Plug Point (CFPP), Pour Point (PP), Low Temperature Flow Test (LTFT)) done to assess cold weather operability characteristics of diesel fuel are adequate for testing biodiesel blends.

Unfortunately this discussion has been complicated by many factors including the change from Low Sulfur (LSD) to Ultra-Low Sulfur diesel (ULSD), that diesel fuel changes seasonally, the fact that biodiesel derived from different base oils have far different characteristics, that transportation and storage affect quality, and that materials will tend to precipitate out of biodiesel when it cold for extended periods of time.

To read the complete Minnesota Report to the Legislature please click here: Report to the Legislature February 2009

Please post your comments, questions, ideas, and thoughts.

Diesel Doctor

Copyright 2009© - William Richards

Gasohol – Ethanol Blended Gasoline – How to Prevent Storage Problems

Gasohol – Ethanol Blended Gasoline – How to Prevent Storage Problems

Image Courtesy of JME Sales

One of the biggest problems with gasohol (Ethanol blended Gasoline) is that it is extremely hygroscopic (the ability to attract water molecules from the surrounding environment and to hold them either through absorption or adsorption.

E-10 Gasohol (Gasoline containing 10% Ethanol) can hold up to 3.8 teaspoons of water in solution in the fuel. This water can lead to corrosion, poor economy, drivability problems, and to phase separation leading to other much more serious problems.

To combat this hygroscopic problem it is vital that storage tanks be purged of all water before any fuel containing Ethanol is added. The use of dispersant additives to deal with any residual water is also beneficial.

Storage tanks will pick up water from condensation of moisture in the air due to the daily changes in temperature. A large storage tank can actually generate anywhere from several ounces to as much as a gallon of water per day. Normally this water would settle to the bottom of the tank; however the Ethanol will pick it up, blend with it, and hold it in suspension.

The addition of a Desiccant type filter in the vent system will dramatically reduce or eliminate this condensation. While this idea is relatively new in the US many other countries mandate the use of these filters to prevent water problems.

It is also vital to regularly check the storage tank with water finding paste to be certain that there is no separated water on the tank bottom. Another advantage to water finding paste is that it will begin to slightly change color or in some cases small colored dots will begin to appear on the paste. This indicates that the fuel mixture is approaching the saturation point where phase separation will happen.

Note: Many of the electronic monitoring systems used for tank water detection may not register properly with Ethanol blended fuels. Also we have seen many instances where the fuel tank sending unit becomes saturated with water and stops functioning properly. When this happens the device will show the last good reading indefinitely.

It should be expected that tanks containing Ethanol will require a significantly higher level of maintenance than those holding regular gasoline or diesel.

For more information on this and other fuel related issues visit: http://www.lcbamarketing.com

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

Fuel and Water - They Don't Go Together

Fuel and Water

They don't mix and you shouldn't try to make them.

One of the more interesting characteristics that is shared by diesel, biodiesel, gasoline, and gasohol is that all these fuels are hygroscopic.

Hygroscopy is the ability of a substance to attract water molecules from the surrounding environment through either absorption or adsorption.

Some examples of this phenomenon are that Ultra-Low Sulfur Diesel (ULSD) will hold approximately 2/10 of 1% dissolved water. This may not sound like much, but if you do the numbers they show that 2/10 of 1% equals 2 gallons of water dissolved in 1000 gallons of fuel. If you work backwards, that would equal 1 gallon of water in 500 gallons of fuel, or 1 quart (32 ozs.), in 125 gallons, or 1 pint (16 ozs.), in 62.5 gallons, down to about 8 ozs. in a 30 gallon tank.

That much water can cause severe corrosion of fuel system components such as injectors, pumps, connectors, and even metal fuel tanks.

That level of water speeds the oxidation and chemical breakdown of the fuel.

That level of water is enough to encourage the growth of bacteria and fungi.

One of the most insidious characteristics of water dissolved in fuel is that the fuels ability to hold water is dependent on temperature. Simply put the warmer the fuel (up to a point) the more water it hold.

What often happens is that fuel stored for example at 60°F will absorb that 2/10% water then as the fuel in a vehicle gets colder more and more of that water is pushed out of the fuel becoming liquid water droplets.

These droplets can collect in filters and if the temperature drops below 32°F those droplets turn to ice crystals quickly plugging filters and causing other problems.

Fuel at 28°F can hold approximately 1/2 as much water as fuel at 60°F.

This means that you can have clear fuel with no liquid water at 60°F and if the temperature drops sufficiently, you can have large amounts of free water suddenly appear as the temperature drops.

To make matters worse biodiesel can pickup and hold 10 times as much water as ULSD. So adding 2% or 5% biodiesel to regular diesel can dramatically increase the level of dissolved water.

Gasoline containing Ethanol suffers the same problem.

A 10% Ethanol blend can hold 3.8 teaspoons of dissolved water at 60°F.

However if more water is added or if the temperature drops significantly this fuel suffers a problem called "Phase Separation".

In Phase Separation the dissolved (or liquid) water binds to the Ethanol and this Water/Ethanol mixture will drop out of the fuel.

This has a series of negative affects on the fuel quality and can have catastrophic effects on engines.

We will discuss more about this later.

We look forward to your comments and questions.

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.

New Cold Weather Problems with Biodiesel Identified

New Cold Weather Problems with Biodiesel Identified

The recent bout of very cold weather in the northern tier states has shown new issues with biodiesel blends containing as little as 2% biodiesel.

We are seeing a significant number of customers that are having problems with the filters on their diesel fuel dispensers.

In nearly every case the customers are receiving a B2 to B5 blend.

In most of these cases they are not having vehicle or equipment problems, but rather problems getting the fuel from the storage tank to the vehicle tank. The dispenser filters seem to plug anywhere from a few hours to a few days of operation.

These filters when opened contain what at first appears to be wax. However when analyzed this material appears to be a glycerin type material. If you then bottom sample the storage tank, you generally find a material that resembles cottage cheese. There is often a layer that starts at the tank bottom and can be several inches thick of this material.

When this layer reaches the level of the pickup tube it can very quickly plug the dispenser filter.

This issue has several variations and we have identified several potential causal factors.

1. 
   Fuel that has a high level of dissolved water. This high water content seems to be a significant factor in all of these cases.
2. 
   Fuel derived from animal fats (including plant / animal blends of biodiesel) seems to be a factor in these problems.
3. 
   Long periods (more than 72 hours) of temperatures below 32 °F (the longer it is cold and the colder the average temperature the greater the problem).
   Above ground versus in-ground fuel storage.
4. 
   Use of additives – Some help, some make things worse.
   CP, CFPP, PP of the diesel portion of the blended fuel.
5. 
   Quality of the blend procedure and temperature at which the fuel and biodiesel are blended.
6. 
   Storage period.

Another factor in the rapid plugging of these dispenser filters is that as filter media starts to plug the filter actually begins to reduce the micron size of the media so that the filter picks more and more material that is smaller and smaller.

Also consider that a diesel engine tends to heat the fuel during the recirculation process whereas a dispenser provides no heat.

We offer some suggestions for users experiencing these problems.

1. 
   If you have this problem today you can go to a dispenser filter with a large micron size. There are winter filters available from Cim-Tek with a cleanable 144 micron stainless steel mesh.
2. 
   You can have the tank pumped from the bottom to remove this material. Depending upon your tank size, you may need to remove 50 to as much as 300 gallons to eliminate this problem.
3. 
   You can add certain types of additives that will break this material down and return it to solution.
4. 
   You can add kerosene (Note: if you have Ultra-Low Sulfur Diesel, you MUST use Ultra-Low Sulfur Kerosene). ULSD Kerosene is very expensive and it can take a lot of it to resolve this problem.
   Ask for your next two or three loads of diesel to be delivered with no biodiesel.
5. 
   Ask for biodiesel blends derived only from plant base oils during the fall and winter months.
6. 
   Additization with the correct products can help to prevent these problems.
   If you have access to biodiesel that has been through a distillation process, you will have far less problems.

Please let us know about your experiences with these problems

Winter Problems with Ultra-Low Sulfur Diesel (ULSD)

Winter Problems with Ultra-Low Sulfur Diesel (ULSD)

Which One of these Filters Would You Rather Have on Your Vehicle?

The above image is from February 5th 2007, the first real winter weather while using the “new” Ultra Low Sulfur Diesel (ULSD). After being told by refiners and many distributors that ULSD would be the “be all, end all” magic problem solver for all diesel engines, this is what really happened when it finally got cold and stayed cold for 48+ hours.

The red colored filter on the left is the result of a fuel distributor using so much anti-gel additive that it actually saturated the fuel to the point of completely plugging THOUSANDS of fuel filters over several days.

The filter on the right shows paraffin wax plugging it. This customer used ULSD #1 (ULSD Kerosene) to “cut” the ULSD #2 fuel. However the “new” ULSD #1 doesn’t work the same way as the “old” LSD Kerosene (see more below)

The new ULSD gels 4°F to 5°F sooner than the “old” Low Sulfur Diesel (LSD). The new ULSD is harder to treat for cold weather than the “old” LSD. Many additives that you have been using for years no longer work on the “new” ULSD. The “new” ULSD holds more dissolved water than the “old” LSD, causing ice formation as the temperature drops below freezing.

When treating with a cold flow improver (anti-gel), using the recommended treatment ratio provides a certain level of protection, using twice the recommended ratio may improve the gel point a little, however if you go beyond that level it will actually raise or worsen the gel-point. At treatment levels beyond 3-4 times the recommended ratio, you will begin to saturate the fuel and can actually plug a filter full of anti-gel additive. This is generally indicated by a reddish or pink colored wax-like substance covering the filter as much as ¼” thick. This wax-like substance will not readily melt at room temperature unlike paraffin wax that melts above 32°F.

In the past the general “Rule of Thumb” regarding using Kerosene (#1D) to “cut” #2 diesel was that for every 10% kerosene added to #2 diesel you would lower the Cold Filter Plug Point (CFPP) by approximately 5°F. So for example a 50%-50% blend of #2D and Kerosene would have lowered CFPP by approximately 25°F. The “new” ULSD #1 is far less aromatic and has much less solvency than did the old Kerosene. As a result the new ULSD #1 will only lower CFPP by 2°F-3°F. This means that a 50%-50% blend will only lower CFPP by 10°F to maybe 15°F.

If you have any comments or related incidents or problems, please post to this blog.

Doctor Diesel