SPÖRL KG Hall 8 / B13

At the last Filtech-conference in 2023 the newly developed Betamesh-PLUS as woven wire meshes for energy-efficient filtration processes were presented. Using a woven wire cloth of this weaving type as filter medium, a filtration process with highest separation efficiencies at lowest power consumptions can be realized. With the Betamesh-PLUS, geometric pore sizes down to 5µm can be realized.

Until now, Dutch Twilled Weaves with their low porosity, low free passage area, low dirt-holding capacity and poor cleaning behavior had to be used for this small pore sizes. In the Betamesh-PLUS the wire diameters of the warp and weft as well as the pitches are combined in such a way, that these fabrics are characterized by a high permeability, a high dirt-holding capacity and ideal back flushing properties.

Due to the realized slit-shaped pores and larger number of pores of the Betamesh-PLUS compared to the Dutch Twilled Weaves, they are characterized by a significantly lower increase of the pressure loss with increasing filter loading and thus a longer service life of the filter medium. Also, the removal of deposited particles from the filter medium e. g. by a pulse-jet is much easier compared to the Dutch Twilled Weaves, since the smallest pore is located on the top of the woven wire mesh. A low remaining pressure loss and consequently a low power consumption result.

The finer the mesh, the thinner the used wires must be chosen. However, this also reduces the mechanical stability of the wire mesh. Betamesh-PLUS with its small pore sizes can also be used as a filter layer in so-called composite-cloths so that these fine meshes can also be used under harsh operating conditions. In composite-cloths, the filter layer is bonded to one or more coarser supporting, protection and drainage layers over the entire surface in a high-temperature sintering process.

These further layers are woven wire meshes with a large aperture size made out of relatively thick wires. Using these mechanical very stable coarse supporting layers with their high permeability in the composite-cloths, the ... The other advantageous filtration properties such as the high dirt-holding capacity and the good back-cleaning behavior are also given in the composite-cloths.

Within the paper, the filtration performance of these composite-cloths is analyzed on the basis of the initial pressure loss, the absolute pore size, the dirt-holding capacity, the load-depending separation efficiency and the cleaning behavior. These quantifying parameters are determined experimentally using a flow rate test-rig, an air-solid test-rig and a cleaning test-rig based on DIN ISO 11057 and are compared with the performance of the single-layered Betamesh-PLUS.

The influence of one or two supporting layers in the composite-cloth on the ... To protect the filter layer, a coarse wire cloth, a so-called protection layer, can be sintered as first layer of the composite-cloth onto it. The paper shows how the permeability and dirt-holding capacity, and therefore the service life of the filter medium, is massively reduced using ... Between the protection layer and the filtration layer, a trapped grain can occur, which can no longer be removed during back-cleaning. Back-cleaning tests using pulse-jet cleaning illustrate how these not-removable particles increase the residual pressure loss.

If cylindrical filter elements are subjected to external pressure, the maximum possible pressure until the element buckles depends not only on the geometry but also on the mechanical properties of the filter material used. For the experimental investigation of this maximal pressure, the so-called buckling pressure, a special test-rig was set up, with which it is possible to pressurize filter cylinders of different geometries. In addition to the geometry, the layer structure of the composite-cloth was also varied during the tests. Based on the results ...