The technology of PA production offered by Technobell limited, starts with oxidation of o-xylene in fix bed tubular reactor on specific catalyst.

Atmospheric air is compressed by compressor. The o-xylene is feed to air stream and both pass through catalyst installed in tubular fix bed reactor, cooled by eutectic salt mixture. There chemical reaction takes place and    o- xylene is transformed mainly to Phthalic Anhydride. Heat released by chemical reactions is removed through melted salts to heat exchanger where High Pressure steam is produced. Reactor gases are conveyed through post reactor where almost 90% of by-products are removed.

The reactor off-gases containing PA are then cooled to appropriate temperature in two heat exchangers producing Medium Pressure steam. Cooled gases are further conveyed to Switch condensers section. In this section PA is removed from gas by the process of de-sublimation – forming solid crystals. After melting the PA in liquid form is obtained. The technology allow to obtain almost 99,8% of PA produced in the reactor.

Switch condensers off gases are conveyed to Thermal or catalytic Incinerator and after it released to atmosphere. The Incinerator is designed to incinerate also residue from the distillation (Light and heavy cut). Due to carefull design important quantity of heat is recovered in form of MP steam.

Liquid PA from Switch Condensers is first thermaly treated and then continously distilled in two distillation columns.

Finally pure comercial product is conveyed to stock tanks to be sold in liquid form or conveyed to a solidifying section where PA flakes are produced and packed in 25 kg bags or 1/1,25 tons big bags.

Other sections of the plant are:

• Steam system, with the task of careful energy transformation and recuperation,
• Oil system prowiding hot and cold oil for Switch Condenser operation,
• Demineralized water station
• Other Utilities system, as Instrumental air, nitrogen, el. Power stations.

From brief description could be seen that efficient PA production technology would:

1. Obtain as high as possible concentration of o-xylene in feed to reactor leading to:
   
   • higher production,
   • smaller equipment.
2. Elimination of by products with post-reactor technology leading to:
   
   • less consumption of energy for distillation,
   • Less residue on the distillation,
   • Extremely good commercial product quality,
   • Smaller columns
3. As high as possible de-sublimation efficiency Switch Condenser section.