When it comes to blending gasoline and diesel fuels with octane, there is a lot riding on the speed and reliability of a refinery's process analysis: It is critical for delivering product which meets customers' exact specifications, and it enables operators to optimize treat rates. Because both of these factors have a direct impact on a facility's bottom line, delayed or inaccurate results from a process analyzer can add up to millions of dollars in losses.
Timely and accurate process analysis is complex, and diagnosing issues arising within a system is not always easy. Operators can run the risk of performing unnecessary repairs — frequent filter swaps, for example — that will not fix any problems, but will cut into profitability through downtime and increased maintenance costs. By implementing optimized analytical systems and collaborating with sampling experts, though, refinery complexes can keep plant operations on track with properly validated gasoline composition that minimizes financial losses due to excess octane treatment.
The problem of giveaways
Say you are blending a high-octane product, and then you switch the treat rate to blending a lower-octane product with a lower price point. Naturally, this requires analytical confirmation that the change has occurred. In the meantime, though, any product in the system has to be priced at the lower-grade rate until the change is validated. What if instead of 10 minutes, it takes 30? That can represent a multi-million-dollar loss, all due to time delay.
In gasoline process analysis, time delay is the amount of time it takes for the sample to travel from the tap in the process line to the process analyzer. There is always some delay, of course, but it is important to gauge it accurately and take steps to minimize it whenever possible. If you are working under the assumption that your time delay is one minute and it is actually closer to two hours, the analyzer readings might not even be relevant anymore. Not only that, but the extended time delay has made it impossible to validate the octane levels and charge accurate rates for the product, resulting in “giveaways” since you are selling higher-octane fuel at the lower-octane price.
Teaming up to tackle challenges
The key to addressing these problems is pulling together the right team. What does that look like in action? Here is an example: An analytical supervisor at one of the largest U.S.-based refiners suspected a time delay issue within a major gasoline blending unit, but was unsure exactly how long the delay was. Swagelok Texas Mid-Coast field engineers met with the customer and conducted analytical surveys in collaboration with refinery teams.
Here is what they found:
- Pressure variation at the sampling tap
- No variable area flowmeter
- Insufficient flow to purge second-stage filters and ½-inch header
- Insufficient flow control elements, with little to no visibility of pressure and flow
- An excessively long sample transfer line
- Excessive filter volumes
- Several unnecessary deadlegs on lines leading to the analyzer
- No visibility to the sampling probe
- Sub-optimized grab sampling station
It is a perfect illustration of several factors all combining to have a huge impact that could not have been fixed through filter changes or routine maintenance. They were all addressed with new grab sampling and analyzer panels, and the system was further enhanced with a centrifugal filtration setup for improved accuracy. And that time delay? It was reduced to 56 seconds, resulting in millions of dollars saved. In fact, it worked so well that the refinery opted to implement the same changes at its facilities across North America.
