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Technology / Butadiene Technology

Butadiene Technology

Butadiene is used primarily as a monomer for manufacturing synthetic rubber and plastics. Smaller amounts are used as a chemical intermediate for producing other chemicals.

Nearly all butadiene is produced as a co-product of the steam cracking of hydrocarbon feedstocks to make ethylene.

Deethanizer bottom which contains a mixture of C3s and heavier components is fed to Butadiene Extraction Plant, where C3s and C5+ are separated as by products, and 1,3 Butadiene is extracted using BASF NMP Process.

Process Description of BASF NMP Process:

NMP Process from BASF is the most widely applied process for the extraction of 1,3 butadiene. The NMP process exhibits remarkable flexibility: its low susceptibility to impurities makes the NMP process capable of processing any industrial C4 feedstock mixture, It operates economically, even with low butadiene content feedstocks. Compared to competing technologies, NMP’s resistance to hydrolysis and thermal decomposition reduces solvent consumption by up to 90% or more. Simultaneously, the process provides a high yield (>98%) of particularly high purity (>99.7%) butadiene.

Butadiene Plant comprise basically six sections: Prefractionation (Depropanizer and Debutanizer), Feed Vaporization, Extractive Distillation 1 (Main Washer), Extractive Distillation 2 (Rectifier/Afterwasher), Product Purification (Butadiene Column) and Degassing (Degasser).

In the following sections, we will describe each step of 1,3 butadiene production:

Prefractionation:

Deethanizer bottom from Ethylene Plant is fed to Pre-fractionation, which consists of two conventional distillation towers namely, Depropanzer and Debutanizer.

C3s are separated from the overhead of the depropanizer, and its bottom is fed to Debutanizer, where C4s are separated from the overhead and C5+ are separated from its bottom.

Feed Vaporization:

The C4s mixture from Debutanizer overhead is fed to feed vaporizer, where it is vaporized to be suitable for extraction process.

Extractive Distillation 1:

Vaporized C4s mixture is feed to Main Washer, where butanes and butenes are separated from other C4s using NMP (N-Methyl-2-Pyrrolidone) according to selectivity.

Extractive Distillation 2:

NMP with selected C4s are fed to Rectifier/Afterwasher, where any traces of butanes and butenes are stripped, and crude butadiene (1,3 Butadiene and 1,2 Butadiene) is separated from Afterwasher overhead.

Product Purification:

Crude butadiene from Afterwasher overhead is fed to Butadiene Column, which is conventional distillation, used to separated 1,3 butadiene from 1,2 butadiene.

Degassing:

Partially loaded NMP is fed to Degasser, to strip hydrocarbons from NMP to return it back lean, so as to re-use it again in Extractive Section 1 and 2.