Design of a Polyethylene Terephthalate (PET) Plant (SSP Unit) with a capacity of 270 tonnes Per Day

Njoku Pius Uchechukwu; Udechukwu Mathew Chidubem; Nnadikwe Johnson; Okakpu Ogochukwu Judith

Authors

Njoku Pius Uchechukwu Chemical Engineering Department, DR. Ben Nzeribe State Polytechnic, Awomama Imo state
Udechukwu Mathew Chidubem Petroleum Engineering Department Federal University of Technology Owerri
Nnadikwe Johnson Petroleum Engineering Department, Nnamdi Azikiwe University,(UNIZIK) Awka Nigeria. https://orcid.org/0009-0000-8664-5253
Okakpu Ogochukwu Judith Pure and Industrial Chemistry Department, Nnamdi Azikiwe University Awka https://orcid.org/0000-0002-7545-1071

Keywords:

Polyethylene terephthalate; Solid-state polymerization; Intrinsic viscosity; Crystallization; Process design; Bottle-grade PET

Abstract

Demand for bottle-grade polyethylene terephthalate (PET) continues to grow, requiring energy-efficient solid-state polymerization (SSP) designs that reliably achieve high intrinsic viscosity (IV). This study presents the process design of a 270 tonnes per day PET SSP plant to produce bottle-grade resin from amorphous chip. Steady-state mass and energy balances, equipment sizing, and polymer property tracking were performed using established design correlations, kinetic models, and industrial operating data from Zimmer and Buhler technologies. The SSP train comprising pre-crystallizer, crystallizer, SSP reactor, chip cooler and nitrogen recycle was evaluated at 210°C and 10 h residence time. The design delivers 268.8 tonnes per day with 99.8% mass closure; 0.44 wt% loss corresponds to water, ethylene glycol and acetaldehyde removed. Net energy demand is 2.09 MW (0.185 kWh/kg), with the SSP reactor accounting for 46.7% of duty. IV increased from 0.60 to 0.80 ± 0.02 dL/g, while crystallinity rose from <5% to 48% in staged fashion, preventing agglomeration. Product moisture was <30 ppm and acetaldehyde <1.0 ppm. The selected conditions lie within proven commercial windows and meet all bottle-grade specifications. The design is technically feasible and provides a robust basis for economic evaluation and implementation.

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