Self-priming pumps in PET recycling plants

PET is a thermoplastic resin commonly used for the production of beverage bottles and containers. The containers are collected by waste collection companies and delivered to the recycling centre, where labels and caps are removed. After sorting by colour, the containers are shredded using special machines. The washed, dried and decontaminated material is melted at 270°C and then granulated. The resulting 'regranulate' is mixed with new granulate, melted again and poured into injection moulding machines to produce 'preforms' for new PET bottles. Transported to the filling plant, the preforms are heated and stretch-blown, turning them into new PET bottles. Sanitised and labelled, the bottles are ready for filling and sale, starting a new life cycle.

Varisco, in collaboration with well-known companies in the sector, designed a line of self-priming centrifugal pumps with special construction (sizes from 2 to 6") to be installed underneath washing tanks to transfer the waste fluid to treatment and purification plants.

Loaded and dense fluids derived from washing are generally very abrasive slurries (water mixed with glue, macerated paper and shredded plastic) that are difficult for ordinary centrifugal pumps to handle.

The design features that make Varisco self-priming centrifugal pumps particularly suitable for this type of application can be summarized as follows:

• Generation of high levels of vacuum in suction to facilitate the entry of the fluid inside the pump casing;
• Wide solids handlings guaranteed by semi-open impellers
• Robust construction with thick castings, metal-based fittings with amply sized support and elastic coupling
• Easily replaceable wear plates to preserve the integrity of the pumps and their performance over time
• Front inspection and unclogging hatches with easy access

In addition, the J self-priming pumps:

• Are equipped with an anti-accumulation system for shredding debris in the back-rotator, which prevents clogging and wear of the machines and ensures simple and infrequent maintenance;
• Can be made of hardened anti-abrasion cast iron. High-quality materials and treatments make the pumps even more resistant to friction wear.
• Can be coupled with oversized motors to handle high density and concentration of solids as well as the possibility of inverter speed control.

In addition to the J series self-priming centrifugal pumps, the ST-R series is also available for even easier and faster on site maintenance. Complete access to the impeller, wear plate, check valve and all internal parts of the pump casing is guaranteed through the opening cover. This feature of the ST-R pump allows routine maintenance without removing the pump from the system and rapid on site de-priming.