Technology

Introduction

SINOPEC Loop Reactor Polypropylene Process (ST-PP) is a combination of N, DQC, ND catalyst family and complex technology of liquid loop reactors and gas-phase fluidized-bed reactor. The first commercial single loop reactor polypropylene plant was built and started up in 1998. ST-PP technology provides the solution of two cascaded loop reactors to produce homopolymer and random copolymer, or two loop reactors combined with a gas phase reactor to produce impact copolymer. The first commercialized of such PP plant was built and started up in 2002.

Technical Characteristics

1. Two cascaded loop reactors are used to produce homopolymer and random copolymer. Two loop reactors combined with a gas phase reactor are used to produce impact copolymer.
2. Intermediate Powder Silos will benefit the Polymerization unit operation and grade transition.
3. Pure or pre-blend additives feeding system makes grade transition easier and faster.
4. Loop reactor has its unique benefits:
- High (time and volume) production rate (>400 kg PP/h m³);
- High speed of materials circulation, high polymer concentration in slurry, and high efficiency heat transfer between liquid monomer and polymer powder;
- Uniformed distribution of catalyst system, condensed monomer easily recovered;
- Rapid product grade transition, off-spec product minimized;
- Full liquid reactors;
- Small diameter of reactors , and thin wall even with high design pressure.

Source: SINOPEC, Chemical Process Solutions, Polyolefin Technologies, Loop Reactor Polypropylene Process (ST-PP) (accessed 12^th Oct 2024).