Plant #1 > PX/MeX
PTA is produced with PX, catalyst, and acetic acid as raw materials. It is used as a raw material not only for polyester fibers with excellent thermal resistance, insulation, mechanical strength, water resistance, and wear resistance but also for video and audio films and PET bottles closely related to our everyday life. It is used for industrial yarns as well.
■ Production process
01 Fractionation Process
Receiving the raw material (mixed xylene) from the raw material tank and the isomerization process, xylene is separated using the difference in boiling points of individual components (difference in boiling points). Substances with low boiling points including meta-xylene and para-xylene are transferred as raw materials from the top of the column to the adsorption/desorption processes, and substances with high boiling points including ortho-xylene pass through the bottom of the column to be made into products.
02 Adsorption and Desorption Process
The process involves selectively separating only PX using adsorbent from among the feeds transferred from the X-S splitter column for the production of PX. (The Parex technology of UOP is used). The remaining raw materials apart from PX are transferred to the isomerization process for the equilibrium reaction of xylene.
03 Isomerization Process Feed
After the main product PX is separated from the adsorption/desorption process and produced, the remaining mixed xylene (OX, MeX) is fed to the isomerization process. To form temperature and pressure for the equilibrium reaction of xylene in the isomerization process, the temperature is raised to 385~390℃ using two units of the heater. The raw material that has met the reaction requirements is fed to the isomerization process, and the equilibrium reaction is achieved with isomer ization acting as catalyst.
04 Isomerization Process
The process involves converting the mixed xylene (PX, MeX, OX), that remains after the main product X is produced and separated from the adsorption/desorption process, at a ratio of 1 : 2 : 1 for PX, MeX, and OX through the isomerization reaction. Through the isomerization reaction, PX is additionally produced (xylene loss is minimized). MX (Recycle MX) that has passed through the isomerization reaction gets mixed with the initial M-X in the raw material tank and goes through the fractionation process again.
05 Benzene Unit
The light substances that have passed the isomerization process are transferred to the benzene unit, except for xylene composition. It consists of two columns (Depentanizer Column, Benzene Column) to produce benzene and toluene, and as with the fractionation process, products are produced using the differences in boiling points of the substances.
