How to ensure melt quality?

In the plastic recycling process, the melt filter and the screen changer are important equipment to ensure that the material is clean. If you can properly use advanced equipment, not only to maintain quality, capacity and more powerful. The following are some of the experience of European recycling companies.

Ettlinger melt filter is stable and high quality

Ettlinger's ERF melt filter is specifically developed for continuous processing of various types of raw materials (new raw materials to heavy contaminated recycled plastics). When used to process new materials containing gels or impurities, the filter is effective in removing the crosslinked high molecular weight components contained in the melt.

The ERF 500 is the largest model in its range, with a maximum throughput of six tonnes per hour. It is also the latest model in the ERF filter series. ERF 250 models with a maximum throughput of 3 t / h and an ERF 200 with a maximum throughput of 1 ton / hour.

Conventional plunger-type screen changers may need to replace many filters every day, and each replacement will interrupt the filtration process, but the ERF can work without trouble for a few weeks without interrupting the production process. Throughout the production stage the filter is kept smooth, keep the process stable, with constant flow and pressure.

The core component of the ERF melt filter is a rotary cylindrical filter with millions of tapered holes that offer a variety of pore sizes. When the melt flows through these filters, the contaminants are blocked on the outside of the screen, and the cleaning melt in the cartridge flows through a flow path system to the downstream granulator or mold.

While the filter barrel for rotary motion, resulting in mixing, so that the melt to achieve the best uniformity. During the slow rotation of the filter (driven by a servo motor), the scraper is cleaned once every revolution. The particles cleaned from the surface of the filter are continuously fed into a discharge system (driven by another servo motor) and discharged from the filter.

Not only can effectively remove solid particles, such as wood particles and aluminum particles or paper dust, but also can remove the high temperature generated by the gel and high molecular weight cross-linking components.

The German recycling company, CPE Entsorgung Ltd, has purchased Ettlinger's ERF melt filter for its polystyrene (PS) recycling project.

"At the start of the project, our goal was to convert the PS waste (containing about 25% of the various contaminants) of the refrigerator that reached the service life into a high quality recycled material," said Robert Harting, general manager of CPE. "

The currently available materials are used to make sheets for thermoformed products such as vegetable trays. He explained that if the material also contains more than 150 micron particles of impurities, in this application will have a major problem. This particle causes the thermoformed product to tear in a thinner area where the sheet is highly stretched and the product is scrapped.

For the final processing steps (PS scrap is extruded after several steps of pretreatment), the CPE is equipped with a rugged single screw extruder (screw diameter: 120 mm) and an Ettlinger ERF 250 in its existing production line Melt filter.

The filter is installed directly between the extruder and the granulator. The filter area is as high as 1,500 cm², and for this application the filter level selected from the numerous filter levels is 150 microns.

During the test, CPE resulted in a maximum weekly production of about 130 tonnes per week and increased to 180 tonnes per week after production. Simple static filter is difficult to achieve this difficult task of filtering requirements. PS melt contains a lot of pollutants, with the accumulation of pollutants, the filter will soon have a huge pressure drop.　

Harting said: "Continuous recoil contaminants for periodic recoil contaminants are also prone to problems in this application, but Ettlinger's ERF filters ensure stable high product quality and excellent durability "

ERF filters are even suitable for the filtration of contaminants with up to 18% of heavily contaminated raw materials. In automatic mode, the continuous discharge of contaminants produces very little loss of melt, since these contaminants are highly enriched (up to 70%) at the discharge port.

The actual melt pressure upstream of the filter is an important parameter of the control system. For example, if the degree of contamination in the feedstock changes (resulting in a change in the melt pressure at the inlet of the ERF filter), the rotational speed of the filter cartridge and the exit screw is automatically adjusted and the two speeds can be adjusted independently.

Nordson V-type network device to extend the start time

A European polyethylene (PE) recycling company installed the Nordson Kreyenborg V-changer, extending the time to once a day.

The recycling company installed Nordson Kernberg's 200mm V-changer on two production lines in its recycling line, replacing the traditional 300mm skateboard changer. These recycling lines are pellets for the production of waste PE into waste bags for blown film production.

Nordson Kernberg said that because the V-type system with automatic self-cleaning function, so only need to replace a filter every day, and the old equipment every 8 minutes to be replaced once. If the contaminant buildup causes the differential pressure on both sides of the screen changer to reach a pre-set level, its "strong recoil" operation will automatically start, by the hydraulic plunger compression of some of the melt polymer, the melt along Reverse direction, recoil through the filter, the pollutants discharged from the system.

It is said that V-type screen changer can remove heavy contaminants from the melt filter element while maintaining the same extrusion output, thus reducing the operator's intervention and avoiding the shutdown. In the Nordson Kernberg V-shaped screen changer, the melt from the extruder is divided into four melt streams in two pairs of filter chambers for filtration, after which the melt flow is re-merged and the melt flow is not There will be significant changes.

Each pair of filter cavities is mounted on a plunger, which retains the position of the filter cavity so that it can filter their respective melt streams, either of which can be removed from the process and removed by recoil Of contaminants. Under normal operating conditions, the polymer flows out of all four filter chambers.

When the predetermined number of backwashing is reached, the filter will begin to be replaced. At this point to carry the plunger out of the filter movement, which can be removed filter components, put on a new filter. In the fourth filter cavity to replace the new filter components, the other three filter cavity is still in working condition.

Kolcor is patented without leakage

Kolcor Technologies of the United States announces that a unique seal used in its series of hydraulic and manual changers has been granted a US patent.

Kolcor has been using this seal since its inception in 2012, but it was "patent pending" and is now "patented". This unique sealing device ensures no leakage at high pressures of 10,000 psi and high temperatures of 345 ° C.

"We have all the seals on our hydraulic and manual changers," says Krcor's president, Chris Kowal. "Unlike other designs that require a working temperature to seal, our seals are equipped with springs, springs Can provide a tightening force, and immediately produce a sealing effect.

When working at the operating temperature, the polymerization pressure will only increase the sealing force to form a true leak-free process.

Sales manager Randy Joubert said: "The polymer leak is a common problem with the changer, which will cause some maintenance problems, resulting in a shutdown and a decline in productivity." Since we started selling the screen changer in 2012, we have never seen To the problems caused by the leak. "