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btx extraction technology

The demand for high-purity BTX aromatics for the synthesis of petrochemical products is steadily increasing.

New catalysts enable performance improvements in the reformers (platformer, aromizer) and thus higher selectivities and yields of BTX aromatics.

Reformer products, the so called reformate gasolines, are used as feedstock for BTX aromatics extraction.

A final distillation of the aromatic fractions purifies the BTX aromatics for further use in a synthesis unit.

 

process description 

 

The purpose of a BTX extraction unit is to produce high purity aromatics from a feed stream of aromatic and non-aromatic components. For most BTX extraction units, the recovery of aromatics occurs in a liquid-liquid extractor column while the purification takes place in an extractive distillation column. Steam stripping is used to remove the aromatics from the solvent.

BTX extraction units use solvents of different polarity, such as sulfolane (high polarity) and diethylene glycol (DEG) / triethylene glycol (TEG) (low polarity).

Flow scheme for more polar solvents
Flow scheme for less polar solvents

 

 

product purities and yields

 

BTX extraction technologies can produce CH-grade benzene and TDI-grade toluene. Typical recovery of benzene, toluene and xylenes is at least 99 %, 97 % and 91 %, respectively. Higher recoveries require slightly more energy.

 

solvent selection

 

The selection of the solvent is often based on some fundamental property such as solvency and selectivity. The more polar solvents have the highest solvency at a given selectivity. A solvent with high solvency would require a lower solvent circulation rate and, therefore, need a lower capital budget for extractor and extractive distillation columns. However, the solvent recovery would require additional equipment, since solvents with high solvency are more difficult to remove from the products.

 

economics

 

Energy consumption & heat integration

The optimization of a BTX extraction unit in terms of energy consumption and the heat integration in conjunction with the separation of the BTX aromatics by distillation is integral part of the design process.

ISBL Cost estimate

Indicative ISBL costs of a BTX extraction unit for the production of high purity aromatic products with an assumed capacity of 10,000 BPD of reformate feed:

 

services

 

EDL together with its partner offer the following scope of services:

  • Process simulation for individual columns of the BTX process as well as the entire BTX extraction unit
  • Analysis of current operation and determination of bottlenecks
  • Recommendations for process modifications (e.g. modification of flow rate, change of solvent, modification of internals)
  • Process studies
  • Basic and detail engineering, procurement and construction services for BTX extraction units

 

 

Customer benefits

  • 20 - 30 % increased capacity
  • 10 - 50 % decreased energy consumption
  • More robust operations
  • Fewer problems with corrosion
  • Inexpensive advanced process control
  • Utilization of existing equipment as much as possible
  • Become cash neutral within 3 to 6 months