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Jul-2006

Benchmarking FCC operations

Benchmarking is an important tool in routine FCC data evaluations. It can be used to validate unit data as well as identify areas for improved performance

C J Farley and Dennis Newell, BASF Catalysts
Atula V Saraf Astron, International Inc
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Article Summary
Benchmarking is being used to rank the performance of a particular FCCU against other units operating at comparable conditions to complement FCC catalyst testing. This has some inherent risk due to the complications of prepping the catalysts to effectively mimic actual operations and act as a tool to help guide future research and development focus. Engelhard has worked with Astron International to develop benchmarking tools for analysing FCCU and catalyst performance. Operating data from hundreds of units can be analysed to determine best-in-class performance and pinpoint areas for improvement. The database can be sorted to analyse the effects of multiple variables, including hardware effects such as riser termination devices and catalyst coolers, as well as feed type and catalyst technology.

The development of a web-based FCC benchmarking application allows refiners to validate their unit’s performance against both their peer group and the global refining industry. This application facilitates easy management, update, search and production of charts and reports that clearly show important shifts in FCC operation due to catalyst, technology or feedstock changes, and identifies opportunities for improving unit performance. The significant benchmarking applications co-developed by Engelhard and Aston International include:1,2
• Web-based system for centralised and secure access with a web browser
• Integration with Engelhard’s proprietary LIMS system for near real-time update of equilibrium catalyst analysis
• Standardised Microsoft Excel-based data import feature for uploading FCC operating data
• Parametric search with query builder for precise and infinitely flexible searches
• Charting features to create “XY” and histogram charts downloadable in Excel
• Reporting features to create standard comparison reports downloadable in Excel
• Personalised features to save charts and reports for quick retrieval.
 
Time-based events
One of the simpler applications of benchmarking is to explore changes over time. Any input into the benchmarking application can be viewed on a time basis, providing the capability to look at how the following FCC operating parameters change with time:
• Conversion levels
• Product properties
• Heat balance conditions
• Feed properties
• Catalyst properties.

Benchmarking can also be performed to compare how particular units “move” on a time basis relative to the other units in the database. In this time-based fashion, benchmarking can illustrate success or failure of individual locations’ optimisation efforts.

Several example cases will be cited to illustrate how equilibrium catalyst properties have moved over time by comparing 2002 to 2005. Figure 1 shows a histogram of equilibrium catalyst rare earth oxide levels in 2002 and 2005. In this chart, data from approximately 200 FCCUs are plotted, representing the majority of the North American units as well as a representative global distribution. Rare earth content has increased over the last three years, coinciding with the major changes observed in unit operations. This has resulted in fewer units operating in the region of 2.0 wt% rare earth oxide. There is a marked rise in units operating between 3.0 and 4.0 wt% rare earth oxide in 2005, relative to 2002. The average rare earth levels of all the units’ catalyst have risen by approximately 0.3 wt%, which is about a 15% increase. In comparison, the average rare earth oxide level for the entire US in 1994 was 1.2 wt% — a dramatic increase upward over the 11-year time period between 1994 and 2005. The West Coast of the US averaged 2.3 wt% rare earth oxide in 1994.2

For the same time period, equilibrium catalyst activity is up by only 0.2 wt%, with the 2002 average being 71.6 wt%, while the 2005 average activity is 71.8 wt%. The histogram (Figure 2) shows that the 2005 data set is more tightly clustered around a 74–76 wt% activity, as determined by Engelhard’s proprietary FACT measurement. In 1994, all FCCUs operating in US refineries averaged 67.8 wt % activity (Note: MAT, measured value equivalent to FACT). At that time, FCCUs in the West Coast of the US averaged 71.3 wt% activity.2 Equilibrium catalyst metals are shown in Table 1.

The table shows that nickel concentration is down approximately 15% in 2005, relative to 2002, while measured vanadium shows an increase of around 9%. There is a substantial change in magnesium loadings, which likely indicates more units using SOx reduction chemistries. Since most SOx reduction additives include rare earth, magnesium and vanadium, this also impacts the observed vanadium loadings.

Hardware effects
There are numerous FCCU hardware features that can be selected for benchmarking. Information has been previously presented for two-stage regeneration design effect on equilibrium catalyst activity versus vanadium loadings at a similar catalyst age.3 Other possibilities include catalyst cooler operating effects, oxygen enrichment and unit geometry.

In this article, advanced riser termination device (RTD) performance is compared to open reactor systems. In this instance, actual operating units with and without advanced RTDs are compared to ascertain if the two types of unit operation show any separation in performance. For the benchmarking effort, all licensors’ recent technologies are considered equal. The data set called “advanced RTD” includes various designs of two-stage cyclones that are coupled together, two-stage systems consisting of a contained modified inertial separator direct-coupled with an upper cyclone, as well as post-riser quench operation. The inertial separator data set refers to the reaction systems that have an active vapour space operating at near riser outlet temperature.
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