What is packing Raschig ring?

Industrial Raschig ring packing is the earliest artificial random packing used in industry. The common size range of Raschig rings is relatively large, and the commonly used size is 25mm - 75mm, but there are also special specifications as small as 6mm and as large as 150mm.

When the Raschig ring is made of ceramic material, its wall thickness is usually 2.5mm - 9.5mm; if it is made of metal material, the wall thickness is 0.8mm - 1.6mm. Under the premise of ensuring strength, reducing the wall thickness as much as possible helps to reduce costs and weight, while increasing the specific surface area of the packing. Large-sized Raschig rings (above 100mm) are generally filled in a regular manner in a whole-laying manner to ensure regularity and stability; while Raschig rings below 75mm are mostly filled in a random manner because they are easier to operate.

The structural characteristics of the Raschig ring with equal height and diameter give it advantages such as simple structure, easy manufacturing, and low price, but there are also some disadvantages. The regular annular structure makes the gas-liquid distribution poor, and the liquid is prone to uneven distribution and serious wall flow channeling in the packing layer, low mass transfer efficiency, large resistance when the gas passes through, and small flux. These problems have limited its application in modern efficient industrial production to a certain extent.

Due to its simple structure and low price, Raschig ring packing still has certain applications in some occasions where the mass transfer efficiency is not high and the working conditions are relatively simple, such as simple tower equipment in small chemical plants and some basic industrial production with extremely strict cost control. At the same time, with the development of materials science, the materials of Raschig ring packing have been continuously enriched, from the initial ceramics and metals to a variety of plastic materials later, such as polyethylene (PE) and polypropylene (PP), which further expanded its application range.