May-2016

Got jet?

Early in 2013, Advanced Refining Technologies (ART) acquired exclusive rights to sell the highly respected ICR line of catalysts, which includes hydrocracking catalyst from Chevron Lummus Global (CLG).

Dan Torchia and Neil Howard
Chevron

Article Summary

As a result, ART has become very active in hydrocracking catalyst sales, research and development, and product commercialisation in the global market.

Around that time, one of ART’s newest customers was just starting up a load of hydrocracking catalyst in North America. The unit is a single-stage recycle design started operations in the early 1980s and previously had been operating with a competitor catalyst system. Operating objectives included:
• Maximising unit operating cycle with higher endpoint feed
• Maximising selectivity toward jet fuel
• Minimising LPG and light gas yield

Feed planned for the upcoming cycle was a VGO/AGO blend with properties as follows:

For ART’s first operating cycle in this unit, the catalysts proposed were ICR 183 and ICR 214. These are two of ART’s newest catalysts, as you can see on the chart below:

ICR 183 is a high-activity catalyst designed to maximise jet fuel yield at the expense of light gas production, resulting in maximum C5+ liquid yields. ICR 183 exhibits a very low deactivation rate, even while operating at high conversions.

ICR 183 also has been designed to provide high nitrogen tolerance for those times when the nitrogen slip may increase from the hydrotreating section. ICR 183 utilises an advanced method of metals deposition during manufacture to result in very uniform metals dispersion over the entire surface of the catalyst. This gives the catalyst excellent hydrogenation activity, resulting in optimal product properties.

The superior metals distribution also contributes to the higher organic nitrogen tolerance and added stability for ICR 183.

ICR 214 was included as a component of this catalyst system, as it offers an activity advantage over ICR 183, while giving up a only modest yield of jet to light and heavy naphtha. Similar to ICR 183, ICR 214 yields very little light gas, thereby maximising liquid products. The pilot plant testing directed by the customer confirms that the jet selectivity is only slightly less for ICR 214 as compared to ICR 183.

The proposed catalyst system was tested at a world class third-party laboratory selected by the customer. This testing was conducted by the customer for three competing catalyst vendors in addition to ART, and was designed to show side-by-side performance comparisons at conditions similar to the customer’s commercial operation. This also allowed the customer to compare the individual catalyst vendor proposals against the pilot plant results. The scope of the testing addressed activity, selectivity, and product quality across several operating conditions. Based on this testing, along with the technical support package and commercial offering, ART was selected.

As a result, the catalyst is currently well into its first cycle and is meeting all expectations. The cracking catalyst normalised average bed temperature (ABT) for the current cycle (red data points) is yielding a very low deactivation rate. The normalised ABT of the current cycle is shown in Figure 2.

The improved performance of the ART catalyst system over previous catalyst systems is presented in the following figures. As shown in Figure 3, the catalyst start of run activity and deactivation rate are much lower than the previous cycle, and similar to that of two cycles ago.

However, it is evident from Figure 4 that the average feed rate of the current cycle is consistently higher than either of the prior two cycles.

More importantly, as a result of the excellent start-of-run activity and catalyst stability, the customer has been able to increase the feed endpoint much higher than previously planned at the outset of the current cycle. Figure 5 shows the feed distillation of the current cycle compared to the previous two cycles. We can see that 400 days into the current cycle, the customer has been able to increase the feed endpoint by 50°F higher than the previous two cycles.

Likewise, the feed API gravity is significantly lower, on average, than the previous two cycles, as shown in Figure 6.

Despite the higher feed endpoint, and lower feed API gravity, conversion has been maintained at 97 vol%, the same as much of the previous two cycles without compromise to the overall operation. The same conversion would appear to indicate the same severity in these three most recent cycles. On closer inspection, however, as a result of a higher average feed rate and fixed recycle oil rate, the conversion per pass in the current cycle is significantly higher than the previous two cycles as shown in Figure 7.

In fact, this increased severity is somewhat understated, since, with the higher endpoint and lower API gravity feed, the current cycle has less product range material in the feed than the previous two cycles, resulting in a higher net conversion as well.

From these multi-cycle comparisons, it is evident that the customer has been able to utilise the improved performance of the ICR 214/ICR 183 catalyst system to its advantage in processing higher feed rates and heavier feed at increased operating severity. In spite of this, the jet yield at 400 days into the current cycle is the same as the previous two cycles and is much more stable than the previous cycle, as shown in Figure 8.

The improved performance is also evident in the total C5+ liquid yield, which, at 400 days into the current cycle, is stable and compares favorably with the previous two cycles in spite of the increased severity of the current operation, as shown in Figure 9.

Looking to the next operating cycle, the customer invited catalyst suppliers to bid for the next reload—this time with a higher endpoint and lower API gravity feed. Because the customer continues to demand the best possible catalyst system, the customer again went to third-party testing to see if anything better was available. ART proposed the same catalysts for this proposal with an optimised stacked loading containing a higher ratio of ICR 214 to ICR 183 compared to the current loading. This will further increase the activity of the cracking catalyst system and position the unit for a longer cycle length. Based on rigorous testing against several competing suppliers, and confidence in ART’s ongoing technical service, ART again has been chosen to supply the next load.

Selecting the right catalyst can be a very rewarding experience for both the customer and the supplier. It is very easy to become complacent with catalyst, as the risk of change is always a concern. However, a close working relationship between refiner and supplier can result in a stronger catalyst system that will meet and exceed all operating objectives. Risk of change can be minimised via third-party testing and proving stated yields and product properties. This particular customer has experienced a dramatic improvement in unit profitability by enabling the processing of more feed, and more difficult feed, without compromise. This strong relationship also includes a strong technical service component to assure that all objectives are met throughout the operating cycle.