METAL RASCHIG RING

PALL RINGS

Pall rings are a progression from the Raschig rings and have the same cylindrical shape and ratio. However, they have two rows of punched out holes with webs from the centre which drastically enhances the execution of the packing with regards to the pressure drop, throughput and efficiency 

PRESSURE DROP VERSUS CAPACITY

They are most appropriate when a low-pressure drop is required in high capacity scenarios and can be customised in a wide variety of sizes for optimum performance for separation. They create a large amount of randomness, and the high surface area to volume ratio enhances mass transfer. Pall rings provide a consistent ratio of free and blocked pathways regardless of the orientation.

MECHANICAL STRENGTH

The internal structure with the web-like design results in a mechanically robust type of packing that is appropriate for use in packed beds that are deep.

Metal pall rings can be made of stainless steel alloys or other metals and provide the advantage that they are capable of handling higher temperature separations and are highly resistant to fouling and are also mechanically robust. They are typically used in separations with H2S, NH3 and SO2 as well as absorption and stripping, steam stripping, quench towers and direct contact cooling.

 
BERL SADDLES

The ceramic Berl saddles are an improvement from both the Pall rings and Raschig rings with regards to an enhanced flow distribution. The shape of the saddles has both the external and internal surfaces exposed, and the distribution of vapour-liquid is the same on both sides. When comparing Berl saddles to the previous two types of packing, they produce a lower pressure on the surrounding column walls  

Berl saddles typically consist of chemical grade porcelain which is chemically resistant to many substances apart from Hydrogen Fluoride and strong alkalis. It is most appropriate for sulphuric acid applications.