Sub-Product

Raw Pygas from the steam cracking process is first fed to the first stage hydrotreating section. To produce BTX, this C₆⁺ Stream is sent to a fractionation section to obtain a C₆-C₈ Heart Cut, which will be further hydrotreated to saturate mono-Olefins in the second stage hydrotreating section. The hydrotreating unit consists of three Sections: 1) First stage hydrotreating section to saturate mainly di-Olefins to Olefins. 2) Second stage hydrotreating section to saturate the Olefins and de-sulfurize the Pygas. 3) Fractionation section to stabilize the Hydrotreated Streams and to recover the C₆-C₈ Heart Cut for further processing for Aromatics extraction. The C₉⁺ Raffinate, or C₉⁺ Cut, is the heavier Bottom Fraction from the fractionation process.

Source: EnggCyclopedia, Typical Process Flow Diagram (PFD) – Pygas Processing.