There has been a dramatic increase in the use of ethanol as a gasoline additive over the past few years, and this may well increase even further. For fuel blenders this means an additional challenge, namely to avoid an inaccurate blend that may lead to regulatory fines, loss of customer confidence and damage to equipment.
A rapid on-site analysis with a portable mid-infrared based analyzer, such as the InfraCal Ethanol Blend Analyzer as shown in Figure 1 can help fuel blenders to rapidly flag out-of-spec product and ensure the final blend meets specifications.
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Figure 1. InfraCal ethanol blend analyzer
There are four common reasons for incorrect fuel blends that highlight how important a quick check of the fuel blend can be.
Mechanical Failure of Blending Equipment
Most ethanol fuel is blended at a fuel terminal using a loading rack. While blending systems at fuel terminal loading racks are considered quite reliable, they never are fool proof and neither are the operators who make the adjustments.
Too little or too much ethanol can be loaded to the tank truck without being detected at the rack and it makes its way to the consumer. The ability to check the blend at the loading rack ensures appropriate deliveries and prevents delays caused by waiting for results of samples sent to a centralized laboratory for measurement.
Multiple Bay Loading Rack Issues
Variations can be experienced in the flow rates of gasoline and ethanol by multiple bay fuel loading racks, due to sudden pressure changes as one of the tank trucks begins or completes filling. In the case that 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 on-site test takes below 5 minutes and will offer the added assurance that the fuel blend in the tank trucks is correct.
Ethanol Denaturant Level Variations
Even in a situation in which the blending equipment is properly working, other factors can impact the final blend percentage. One of the most notable is the variation in the denaturant level of the ethanol.
The denaturant is normally natural gasoline and it is blended at 5%. If this percentage is different from the expected level, the contribution of the denaturant to the ethanol blend ratio will not be correctly compensated and it will result in an incorrect blend. Any inconsistencies can be identified by an easy on-site check of the blend.
Ethanol and Gasoline Expand when Mixed
Another reason for uncertainty in the final blend level is the fact that the blending of gasoline and ethanol causes expansion of the total volume. For instance, a mix of one hundred gallons of ethanol added to 900 gallons of gasoline will add up to more than 1000 gallons of blended fuel. Consequently, without a way to actually test the fuel blend in the rack, simple proportional blending could lead to an incorrect blend calculation.
Portable Infrared analyzers offer an accurate, simple and low cost solution to on-site blend testing. In case any of the situations take place at the blending rack, the resulting costs of an incorrect blend can far out way the modest cost of an on-site ethanol blend analyzer. With a large number of them already in use at petroleum terminals and by regulatory agencies, the InfraCal Ethanol Blend Analyzer has proven to be a reliable tool to ensure fuel blend accuracy.
This information has been sourced, reviewed and adapted from materials provided by AMETEK Spectro Scientific.
For more information on this source, please visit AMETEK Spectro Scientific.