CONSTRUCTION
Multi Mesh column packing are fabricated by knitting bunched fine wires in to mesh which is further crimped and wound in to a roll of the desired column diameter. A vari - Multi Mesh column packing is also developed in which the density of mesh is lower at the top of the packing than at the bottom. The variation in density of mesh tends to the change liquid flow pattern in the mesh resulting in redistribution of liquid within column.

LIQUID DISTRIBUTION
For better operation of Multi Mesh column packing it is necessary to have a good initial multipoint distributor. Because of the capillary action of multi filaments, the wall effects are nearly eliminated. However, for column heights larger than 3 metres an intermediate re distributor would be recommended. SUMIT INDUSTRIES offers a full line of columns internals to complement Multi Mesh column packing high efficiency packing's.

MATERIALS OF CONSTRUCTION
Any material which can be drown into a fine wire or filament can be used in the manufacture of Multi Mesh Column Packing's. However stainless steel 316 grades are readily stocked and other higher alloys are available on order.

INSTALLATION
Multi Mesh column packing is supplied as 150 mm height module of the same diameter as the nominal bore of the column. The column must be free from all internal projections and in the case of welded columns the internal welds should be ground smooth. Only the simplest type of support is required usually two bars at right angles or in larger towers parallel bars and cross bars at 150 mm pitch.

Successive modules of Multi Mesh column packing are inserted into the top of each section of tower and pushed gently down towards the support grid. A disc of wood mounted on a pole permits the packing to be pushed without risk of damage. Care should be taken to ensure than successive modules of Multi Mesh column packing have their crimps going in opposite direction (i.e. staggered).

SALIENT FEATURES
1) The high voidage of Multi Mesh column packing allows free flow of both liquid and vapour through the packed column resulting in low pressure drop per unit height of the packing ∆ P/Theoretical = 0.05 − 0.75
2) The high surface area of Multi Mesh column packing permits an intimate contact between vapour and liquid, resulting in low values of HETP ≥ 100 to200 mm in production column.
3) The low bulk density of Multi Mesh column packing result in decreasing the dead weight of the packed column. It also result in a lower shell thickness.
4) The HETP (Height equivalent of theoretical plate) of Multi Mesh column packing is less than 15 cm over the entire range of velocity.
5) Due to the capillary effect or multifilament mesh of Multi Mesh column packing wall effect is almost completely eliminated.
6) The flooding velocity of Multi Mesh column packing is 2-2.5 times higher than those of conventional packing's. This depending upon the requirement will reduce the column diameter or will reduce the column diameter or will increase the throughput.

ADVANTAGES
1) Improve performance of existing columns. You can upgrade existing processes by replacing random packing's or trays with Multi Mesh column packing column packing. This simple change can result in increased product quality, higher production capacity and lower pressure by permitting the use of lower reflux ratios resulting in lower reboiler duty.
2) Reduced cost of new packed column systems. The high efficiency of Multi Mesh column packing permits
significant reductions in tower diameter and height, minimizing structural, foundation, piping, insulation and installation costs on new project.
3) Turn down-due to its capillary nature, the efficiency of Multi Mesh column packing increase with decreasing loading thereby providing an extremely wide range of operating capabilities.

TYPICAL APPLICATIONS
Multi Mesh column packing supersede all the conventional tower packing their characteristic and performance.
Some of the typical applications of Multi Mesh column packing are mentioned here.
Vacuum distillation service where pressure drop across the packed height is critical separation of close boiling components which requires a very large number of theoretical plates.
Where components are thermally unstable Multi Mesh column packing are indispensable.

COMPARATIVE TECHNICAL DATA OF MULTI MESH COLUMN PACKING