MELT FILTRATION SYSTEMS for PLASTIC RECYCLING

The filtration technologies used in melt filtration systems are different from each other. Choosing the right filtration technology is necessary to maintain the quality of the recycling output. In addition, the performance required in the recycling process of input and output plastic materials is also decisive in this selection.

The role of melt filters in plastic recycling is very important. It is even decisive. Because laser filters separate aluminum, paper, rubber, cardboard, wood and even foreign plastics in molten plastic from recycled plastic. If this filtration is not performed with a sufficiently high performance, the purpose of recycling cannot be achieved, that is, a quality material that can be reused cannot be obtained. Therefore, obtaining quality pellets as a final product depends on filtration in line with the performance needs of both input and output pellets.

Basically, it is possible to talk about two filtration systems. The first of these is back flushing filters. Wire mesh screens are used in these filters. The other is self-cleaning continuous filters and steel screen discs are used for filtration.

Automatic Back Flushing Filters

Automatic back flushing filters have piston screen changer systems with back flushing and are used in wire mesh filters. Two filter cavities are carried by each piston. The purpose of these cavities is to transport packages of wire mesh screen. In this system, which offers a cyclic process, there is filtering with mesh sizes of 32 microns and below.

Filters are made from woven wires. Therefore, the open area ratio per unit surface area is high. These systems are designed in a way that allows them to be developed and to increase their capacities. So much so that the capacity of one piston and two screens can be increased up to 6 pistons and 12 screens. With the 6-piston screen changer, the melt pressure difference in the back flushing cycle is very low. While maintaining the stability and continuity of the recycling process, only one of the 12 screens is in back flush mode. Others are in full production.

Self-Cleaning Continuous Filters

Laser filters are used for continuous plastic recycling filtration periods. That’s why they’re called self-cleaning continuous filters. These continuous filtrations are performed at stable pressure levels. Considering the mesh screen filters, the time for the contaminants to be present in the filtration process is much shorter. Because mesh filters have to wait for back flushing.

Screen disc filters is another filtration technology. It has a steel plate. The orifices on this steel plate are made by laser. Technically, the reason for the use of laser is to provide the most appropriate filtration precision. The melted plastic, which is started to be recycled, passes through these orifices. Contaminants remain on the laser filter. Melt pressure increases as contaminants accumulate and the stripping mechanism of the laser filtration machine works and scrapes the accumulated contaminants from the filter. Each of the screen has three scrapers. This is to ensure that the melt flow is not blocked by contaminants. Thus, high efficiency is obtained even in materials with high contamination rate.

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