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