Onsite Ethanol in Gasoline Blend Analysis

Eliminating uncertainty in fuel blends & saving costs
The use of ethanol as a gasoline additive has increased dramatically over the past few years, and will likely continue to increase. For fuel blenders, this means an added challenge to avoid an incorrect blend that could lead to regulatory fines, loss of customer confidence, and damage to equipment. A quick onsite analysis with a portable mid-infrared based analyzer can help fuel blenders quickly flag out-of-spec product and ensure the final blend meets specifications.

The four most common reasons for incorrect fuel blends are described below, highlighting how essential a quick check of the fuel blend can be.

1. Mechanical failure of blending equipment.
The majority of ethanol fuel is blended at a fuel terminal using a loading rack. Although blending systems at fuel terminal loading racks are considered quite reliable, they are never foolproof—and neither are the operators who make the adjustments. Too much or too little ethanol could be loaded into the tank truck without being detected at the rack and, ultimately, make its way to the consumer. Having the capability to quickly check the blend at the loading rack not only ensures correct deliveries, but also avoids delays in waiting for sample results sent to a centralized laboratory for measurement.

2. Multiple bay loading rack issues.
Multiple bay fuel loading racks can experience variations in the flow rates of ethanol and gasoline due to sudden pressure changes as one of the tank trucks begins or completes filling. If the blending equipment is not properly set up to compensate for these flow rate changes by maintaining a set pressure in the main header, the resulting blend ratio can be different than expected. An onsite test takes less than five minutes, providing the added assurance that the fuel blend in the tank trucks is correct.

3. Ethanol denaturant level variations.
Even in a situation where the blending equipment is working properly, other factors can affect the final blend percentage. One of the most notable is the variation in the denaturant level of ethanol. The denaturant is usually natural gasoline, and is typically blended at 5%. If this percentage differs from the expected level, the contribution of the denaturant to the ethanol blend ratio will not be correctly compensated, resulting in an incorrect blend. Again, an easy onsite check of the blend quickly identifies any inconsistencies.

4. Ethanol and gasoline expand when mixed.
Another cause of uncertainty in the final blend level can be related to the fact that when ethanol and gasoline are blended, the total volume will expand. For example, a mix of 100 gallons of ethanol added to 900 gallons of gasoline will add up to more than 1000 gallons of blended fuel. Consequently, without some way to actually test the fuel blend at the rack, simple proportional blending could lead to an incorrect blend calculation. Portable Infrared analyzers offer a simple, accurate, and low-cost solution to onsite blend testing.

Should any of the situations described above occur at the blending rack, the resulting costs of an incorrect blend can far out way the modest cost of an onsite ethanol blend analyzer. Fortunately, many analyzers are already in use at petroleum terminals and by regulatory agencies. Ethanol blend analyzers have proven to be a reliable tool to ensure safety and fuel blend accuracy.


Sandra R Rintoul is the President of Wilks Enterprise, Inc.

Wilks Enterprise, Inc.
www.wilksir.com