The design of random packings has changed greatly over the years to support processing industries worldwide and intensify mass transfer activities. For example, these products have evolved from simple ring or saddle structures to complex flow-through solutions with large effective surface areas.
The evolution in random packing design over four generations has served to maximise the interfacial area between gas and liquid whilst ensuring high fluid flows. Additional improvements also target uniform bed distribution, high wetting rates, reduced fouling, and costs, as well as maximum overall strength and durability of the packings.
The anatomy of a next-generation random packing
The best example of how the latest, fourth generation of random packing addresses all these aspects is provided by Sulzer’s NeXRing. The solution was first developed and thoroughly tested in 2014 and is now available in seven different sizes, to suit different separation requirements.
Figure 1. Sulzer's NeXRing is the latest advance in random packing design, featuring large and accessible ring surface for optimal column performance.
NeXRing is characterised by a large and widely open ring-like structure that distributes evenly on the column bed. In this way, the packings optimise wetting rates, ensure a large surface area for the separation process and uniform flowing of liquids and gases. Furthermore, the next-generation design lowers any pressure drops and minimises solvent foaming, thus improving the gas flow within the column.
The end flanges and the reinforced ribs of Sulzer’s system give the packing a high mechanical strength. NeXRing offers maximum allowable forces 1.5 and 1.8 times higher than first- and second-generation rings respectively. Also, the very open structure of the NeXRing provides excellent fouling resistance to ensure an extended service life.
Random packing upgrades delivers substantial savings
The innovative features of fourth generation random packings make them superior to older-generation rings. Previous generation solutions, even when well-designed, cannot compete with the performance offered by latest, fourth generation random packings.
Numerical simulations, laboratory and pilot studies show that replacing conventional second-generation rings with NeXRing can increase column capacity by 25% to 35% while maintaining or even increasing the overall efficiency and product quality. Similarly, by trading third generation random packings for NeXRing, it is possible to increase column capacity by 10% while keeping an optimal separation efficiency. In both cases, Sulzer’s fourth generation solution is able to do this at half the pressure drops.
These substantial improvements in efficiency and capacity also result in clear energy saving as well as a reduction in operating costs. Consequently, the increased levels of productivity available from newer random packings offer a substantial and immediate ROI.
Sulzer’s experts generally estimate the investment to have been repaid in less than two years for users replacing third-generation solutions with NeXRing, based on the predicted yields. When the random packings are even older, such as designs from 1980s or earlier, the upgrade to NeXRing can pay off in a matter of weeks.
Figure 2. NeXRing provides extremely large and uniform open area in every ring orientation allowing a high surface exposure to liquid and vapour while minimising dry zones.
When replacing or installing a new column, customers in the hydrocarbon and chemical processing industries who choose NeXRing can gain substantial benefits and fast ROI. To achieve set capacity and loading, columns using NeXRing can be thinner than systems using second- or third-generation packings. This results in substantial reductions in vessel material volumes and weights, and subsequent capital expenditure (CAPEX) savings.
For example, the diameter of a general CO2 absorber can be reduced by 6-10% when shifting from third-generation packings to NeXRing, offering CAPEX savings up to 10%.
It is clear that delaying random packing replacements until it is absolutely necessary, e.g. due to equipment failures, is often counterproductive. By sticking to obsolete solutions, hydrocarbon and chemical processing industries miss an opportunity to achieve a substantial ROI with a well-proven and widely accepted technology.
Overcoming the fear to upgrade
While companies may be held back by the idea of partially or wholly upgrading a fully working separation column, they should also consider that random packings were designed specifically for applications that require frequent removal of column parts. Therefore, such operations do not greatly affect uptime, as they can be easily integrated during scheduled maintenance.
Processing industries can further slash the impact of replacing their rings by relying on highly skilled experts, such as Sulzer’s field engineers. They can suggest the most suitable implementation pathways and provide continuous support during the installation of NeXRing packing and for future maintenance. As a result, hydrocarbon and chemical processing plants can benefit from a reliable one-stop-shop for the manufacture, supply, dismantling and replacement of quality column internals.
Author: Mark Pilling, Manager of Technology at Sulzer Chemtech
Read the article online at: https://www.hydrocarbonengineering.com/gas-processing/12032019/sulzers-latest-random-packings-promises-improved-column-efficiency-and-capacity/