The absorption process is very much influenced by proper liquid distribution on the packing surface. Liquid channelling and existence of dry elements of the packing are the factors which decrease mass transfer coefficients.

In order to achieve the optimum liquid cover, a special type of Multiwir rectangular packing, named MX packing, has been developed. The packing consists of perforated polypropylene strips which are bent at definite vertical distances. The perforations allow for the moisturising of both sides of the strips and are also responsible for equalising the liquid flow on the packing surface. There is an evenly distributed liquid film flowing down on both sides of the inclined strips. Irrespective of the gas and liquid flow rates applied, the interfacial area is stable and equals the surface area of MX packing.


Multiwir MX packing is characterised by low pressure-drop. For that reason an application of a wide range of gas and liquid flow rates are possible. In the case of a countercurrent flow the gas velocity can safely reach 4,5 m/s without any risk of flooding. In the case of cocurrent flow, the only parameter limiting the maximum gas velocity is pressure-drop. The minimum velocity can be as low as 0,5 m/s. The optimal range of the liquid flow rate is wide and averages 0,2 ÷ 10 m3/(m2.s).
Multiwir MX packing has been applied in water-cooling installations, gas humidifiers and absorbers.

An example of an application of Multiwir MX packing is a HCl absorption installation operating since 1995 in Copperwoks Legnica (Poland), the Sulphuric Acid Department. Two identical absorbers working in parallel are part of the Solinox flue gas desulphurization system. Each apparatus is cylindrical and bisected vertically into a cocurrent and a countercurrent section. Both sections are packed columns equipped with liquid distributing nozzles. The total height of the MX packing applied equals 6 m. The second section additionally contains a droplet separator (standard Multiwir packing, 0,5 m high) mounted at the top. Both columns are fed with a circulating water solution of Cl&ndash at a concentration of 1,5 ÷ 2,5 g/dm3, without neutralisation by means of alkali dosage. The average temperatures of the inlet and outlet gas streams are 230oC and 60oC respectively. The gas velocity equals 3,5 m/s, and hence the retention time within the packing structure is about 1,7sec. Under these conditions the attained HCl reduction in the gas stream averages 97 ÷ 99% (from about 100 mg/mN3 to 0,5 ÷ 3 mg/mN3).



MULTIWIR GAS HUMIDIFIERS are applied in the sugar industry. A device called carbonation gas humidifier is designed for humidifying and heating up the carbonation gas by hot water. Its operation leads to improvement of the carbonation process and to decrease of the gas supply needed.

The device is a cylindrical packed column operating countercurrently under overpressure. It usually contains 1,5 ÷ 2,0 m of Multiwir MX packing made from polypropylene and is also equipped with a droplet separator placed at the top. Hot water is distributed via nozzles. The average liquid load is about 7 dm3/m2s, while the gas velocity exceeds 3 m/s. The liquid outlet flow is controlled by a valve.

An application of Multiwir MX structured packing
in the processes of membraneless mass-and-heat exchange
brings following advantages:
  • high efficiency within a wide ranges of gas and liquid flow rates applied
  • optimal liquid distribution on the packing surface, no channelling
  • steady, even operation
  • ease and flexibility of implementation
  • low pressure drop (below 300 Pa/m)
  • good mechanical properties and durability of the packing

MULTIWIR - dr Kwasniak