ring wall, so that the gas and liquid in the packed tower can pass freely through the window hole, improving the gas-liquid distribution and making full use of the inside of the ring. The surface increases the mass transfer efficiency. Compared with the Raschig ring, the treatment capacity can be more than 50% larger, and the pressure is reduced by half; generally made of metl, plastic or ceramic.The ceramic Pall ring has excellent acid and heat resistance, can withstand various inorganic acids