Technology

Technology Summary

The Clean Tubular Reactor Technology (CTR^®) is a non-pulsing technology where ethylene is polymerized through a radical reaction initiated by peroxides at a pressure of approximately 2500 bar in a tubular reactor. The reactor is a plug flow type reactor. Not all the ethylene is converted into polymer on the first pass. The unconverted monomer is recycled to the compression section and the produced LDPE, as a melt, is extruded^[1].

Technology ownership

The Tubular Reactor Polymerisation of Ethylene technology was originally patented by STAMICARBON N.V. in Fe. 1967^[2]. DSM started licensing CTR LDPE in 1995^[3]. SABIC inherited the CTR LDPE Technology when it acquired DSM's petrochemicals business in 2022^[4].  Today, Technip Energies is the exclusive licensing support contractor of SABIC for the Clean Tubular Reactor LDPE technology^[1].

Features of the CTR^® LDPE Technology

Claimed advantages of the CTR LDPE Technology are simplicity of design and operation resulting coupled with the so-called 'Clean Tubular Reactor' concept, resultiing in low investment cost, high on-stream times, high prime grade percentage and low manufacturing costs^[1,2]. 

A conceptual Block Flow Diagram (Fig. 1) shows the low pressure cycle, the high pressure cycle, inputs and outputs of the process. The chain transfer agent is added to the booster compressor, ethylene in fed to the primary compressor and recycle is added between primary and secondary compressor stages. In particular, the initiator from cans is blended in minaral oil and the mix is injected via four initiator dosing systems at different points along the reactor lenght (Fig. 2)^[2]. 

Figure 1 - Conceptual Block Flow Diagram of the CTR LDPE Technology^[2].

  The characteristics of the CTR LDPE Technology are as it follows^[2]: 

• Plug flow
• Design pressure: 3,000 bar
• Design temperature: 300°C
• Four reaction peaks
• Initiators: peroxide only
• Conversion: up to 38.5%
• No fouling
• No pressure pulsing required

Figure 2 - Initiators Injection Points along the CTR Tubular Reactor^[2].

The CTR Reactor is claimed to be "Simple" in Design—by comparison with the "Complex" Design of competitor's reactors—resulting in a non-pulsating reactor as depicted in Fig. 3^[2].

Figure 3 - Operating Temperature Profiles of the CTR Tubular Reactor^[2].

Plant References

More than 10 plants are in operation and Eight references were designed by Technip Energies^[1].

Literature

1. Technip Energies, Oct 2023, Technip Energies Technology Handbook.
2. STAMICARBON N.V. (NL), GB1196183 (A), Priority date 9^th Feb 1967, Process for Preparing Ethylene Polymers or Copolymers.
3. SABIC, May 2012, SABTEC CTR LDPE Technology, Global Petrochemicals conferennce, Cologne, German. 
4. Oil&Gas Journal, 3^rd Apr 2002, SABIC to acquire DSM's petrochemicals business for almost $2 billion.