PETpla.net Insider 03 / 2016

MATERIAL / RECYCLING 12 PET planet insider Vol. 17 No. 03/16 www.petpla.net MATERIAL / RECYCLING 12 Fig.6: Plant lay-out of large scale EcoSphere plant EG generated from the PET polycondensation reaction is recycled in the melt phase, while it is usually incinerated in a conventional SSP using a catalytic combustion system in the nitrogen purification unit. As an alternative, a scrubber system can be used in the nitrogen purification unit to recover the EG from the polycondensa- tion reaction and recycle it to the melt phase. This technique has been demonstrated in several SSP plants already; it is employed as part of the Eco- Sphere technology. Two features of the EcoSphere technology help to avoid off-spec material. One is the actively- heated delta Q crystalliser, which supplies a temperature and crystallinity adjustment indepen- dently of the granulation conditions. The other is the opportunity to re-feed material from off-line storage through the delta Q crystalliser into the SSP. All of this helps to maximise yield from the PET production plant. Yield advantages also result from the lower IV melt in the underwater granula- tion process. Less dust is generated leading to extended life for the knives and die plates, leading to consequently fewer changeovers and, conse- quently therefore, reduced start-up waste. EcoSphere technology offers potential for higher single line capacity. Conventional SSP covers a wide range of starting IVs and is already in operation in plants exceeding 900t/d capacity. Direct melt processes – which, by definition, focus on a higher starting IV – have not reached these capacities. EcoSphere offers more. A first installa- tion has already exceeded its nameplate capacity of 600t/d. Polymetrix is currently building two SSP plants with over 1,500t/d capacity each, following two IPT/Chemtex CP plants with the same capac- ity. (Fig.6) EcoSphere technology is not limited to new installations. Many older conventional CP/SSP plants can accommodate change to granulation systems and accept a delta Q crystalliser. Capac- ity increases are usually achieved at the same time. Similarities in the granulation step allow Eco- Sphere technology to be retrofitted to direct melt processes. www.polymetrix.com