Denstone® deltaP® Support Media Reduces Operating Costs and Layers in Fixed-Bed Catalyst Applications
Refining is gaining in complexity due to expanding markets, increased regulations and attempts to offset declining profits. Process optimization, therefore, is becoming mandatory in effective refinery planning, turnaround planning, troubleshooting and profit margin analysis and management.
Pressures on Reﬁneries
The Role of Support Media
- Unplanned reactor shutdown
- Pressure drop fluctuations
- Process inefficiencies related to breakage, chipping, etc.
- Increased operating costs
Denstone® Support Media Family of Products
Denstone® deltaP® Support Media, Engineered Performance and Value
Based on its unique shape, Denstone® deltaP® media provides many performance advantages in fixed-bed catalyst applications:
- Only two layers of media are used compared to up to four layers of spherical media
- Increases available space within the reactor allowing for additional catalyst or adsorbent media
Reduces fill cost by eliminating the need for expensive small spheres
Dramatically reduces pressure drop
Fewer media layers translates into faster, simpler installation
Denstone® deltaP® Support Media Properties
|Denstone® deltaP® -- Typical Properties|
|Size||Typical Diameter||Crush Strength*|
*Note: Crush strength is the average of the strength in the axial and radial orientations.
Tested and Validated Performance
Video 1. This video shows the high performance of Denstone® deltaP® support media during a migration test designed to mimic actual process conditions.
» Customers see performance improvements with Denstone® deltaP® support media «
Reduces catalyst migration risk without reducing active catalyst volume
For many years, Chevron has used ceramic spherical support media as catalyst support in their hydroprocessing reactors. At times, they have observed migration of small catalyst particles through the support balls that would partially plug the catalyst support screens at the bottom of the reactor beds. Migrating catalyst can contribute to reactor pressure drop build and in rare cases can lead to catalyst migrating into reactor internals. Multiple layers of appropriately-sized ceramic balls can be used to inhibit catalyst migration, but adding extra support layers can significantly reduce active catalyst volume with subsequent reduction of reactor performance.
To reduce this catalyst migration, Chevron trialed the use of Denstone® deltaP® support media in multiple reactors. Based on these trials, Chevron believes the Denstone deltaP support achieved the goal of reducing catalyst migration without reducing the amount of active catalyst in the reactor. Chevron has stated that the unique shape of the material appears to be more resistant than ceramic balls in preventing catalyst migration.
Chevron utilized two layers of Denstone® deltaP® support media in their reactors – one layer of the P1 size and one layer of the P2 size, during the initial trials. During this time, they found that the larger Denstone deltaP P2 size proved to be very difficult to load and unload using conventional catalyst handling techniques. After several trials, Chevron decided to abandon the use of the larger Denstone deltaP P2 size and continued to use the Denstone deltaP P1 size, which was found to be easily loaded and dumped using normal handling methods.
Chevron then contacted the Saint-Gobain NorPro team and described the difficulties of handling the larger P2 size and proposed the idea of Denstone® deltaP® support media in an intermediate size (smaller than P2 but larger than P1). Saint-Gobain NorPro successfully commercialized an intermediate size of the Denstone deltaP material within two months for further trials in Chevron reactors. The intermediate size is identified as Denstone deltaP P1.4. Chevron has now successfully used the various Denstone deltaP support media sizes in multiple reactors and believes they have achieved our goal of reducing catalyst migration without reducing the volume of active catalyst.
Reduced support media volume leads to more adsorbent and higher performance
The performance of Denstone® deltaP® media was tested in a crude gas dryer, pygas cracker and MAPT reactor by a major European Petrochemical player. Their main goal was to increase the volume of mole-sieve in the reactors in order to upgrade the performance and the run-time of the applications. By utilizing Denstone deltaP media, they were able to reduce the support media layer from 150mm to 100mm, and were able to install an additional 17 percent of adsorbent. With the use of additional adsorbent, the user saw the longer running times and the performance upgrades they were looking for.
Along with the upgraded performance in the vessels, they also saw no negative impact to using the shaped media. Their installation (sock-loading) remained as easy as their previous experience with spherical media. With a highly positive experience, this company would recommend the usage of Denstone® deltaP® media in all other applications, especially in those where a user would want to add more active media into the application.
A Look at Loading and Pressure Drop
Selecting the right size of support media
- Catalyst size
- Bottom screen opening
- Total support media
Denstone® spherical support media is typically loaded so that the diameter of the media in each layer is no greater than double the diameter of the media in the adjacent layer. Using this 2X concept, the diameter of the spherical support media directly below the catalyst bed should then be no greater than 2X the diameter of the catalyst. The largest support media size needed is determined by the size of the bottom screen opening.
Users can print the selector tool’s results as well as email the results to themselves and colleagues. In addition, this data can be automatically populated into the pressure drop estimator, which will allow users to see the impact of the layering depths by product type on their pressure drop.
Estimating Pressure Drop
Figure 4: Denstone® deltaP® media pressure drop advantage vs. spherical support media.
The Denstone® Pressure Drop Estimator tool simplifies both the calculation of pressure drop and comparison of support media. Specifically, users are asked to input the following information:
- Size support media
- Layer depth
- Gas Velocity (ft./min)
- Operating pressure (PSIg)
- Average operating temp (°F)
- Output units (inches H2O, PSI or kPa)
Once the conditions are entered into the tool, the user will then be able to see the pressure drop for Denstone® spheres and how that compares to Denstone® deltaP®. The tool not only provides the total overall pressure drop, but by each layer in the output unit specified.
- Layer 1 : Denstone® size 1/8” (3mm) with a layer depth of 100mm
- Layer 2 : Denstone® size 1/4” (6mm) with a layer depth of 100mm
- Layer 3 : Denstone® size 1/2” (13mm) with a layer depth of 100mm
- Layer 4 : Denstone® size 3/4” (19mm) with a layer depth of 200mm
- Gas velocity of 100 ft./min
- Operating pressure of 300 PSIg
- An average operating temp of 150°F
- With PSI as the output unit
The Pressure Drop Estimator tool would show an overall pressure drop of 0.6 PSI for Denstone® spheres and of 0.2 PSI for Denstone® deltaP® as seen in Figure 5. As indicated, there is a substantial improvement in pressure drop when utilizing Denstone deltaP.
Figure 6. Pressure drop variation when air flow rate is adjusted and all other inputs remain constant.