Paraxylene Crystallization Process by GTC Technology

CrystPX is a modern suspension crystallization technology for production of paraxylene (PX). The process can be applied in a single-stage for concentrated PX feedstock or in two stages for equilibrium xylenes feed. The technology has fewer pieces of equipment, simplified flow schemes, and a more reliable operation compared to traditional crystallization methods.

Paraxylene Crystallization Process by GTC Technology

Suspension crystallization of PX in the xylene isomer mixture is used to produce PX crystals. The technology utilizes an optimized arrangement of equipment to obtain the required recovery and product purity. Washing the paraxylene crystal with the final product in a highefficiency pusher-centrifuge system produces the paraxylene product.

When PX content in the feed is enriched above equilibrium, such as streams originating from selective toluene conversion processes, the proprietary crystallization process technology is even more economical to produce high-purity PX product at high recoveries. The process technology takes advantage of recent advances in crystallization techniques and improvements in equipment to create this cost-effective method for PX recovery and purification.

The design uses only crystallizers and centrifuges in the primary operation. High-purity PX is produced in the front section of the process at warm temperatures, taking advantage of the high concentration of PX already in the feed. At the back end of the process, high PX recovery is obtained by operating the crystallizers at colder temperatures. This
scheme minimizes the need for recycling excessive amounts of filtrate, thus reducing overall energy requirements.

Process advantages:
• High-purity PX and recovery (99.8+ wt% purity at up to 95% recovery)
• Crystallization equipment is simple, easy to procure and operationally trouble free
• Compact design requires small plot size, and lowest capital investment
• Operation is flexible to meet market requirements for PX purity
• System is easily amenable to future requirement for incremental capacity increases
• Feed concentration of PX is used efficiently
• Technology is flexible to process a range of feed concentrations (75 wt%–95 wt% PX) using a single refrigeration system
• Design variations are used to recover paraxylene efficiently from feedstocks (~22% PX) in a multi-stage system, competitive with adsorption-based systems.

Licensor: CrystPX is a proprietary process technology marketed and licensed by GTC Technology Inc., in alliance with LyondellBassell

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