Extraction units are typically utilizing the solvents to dissolve the aromatics compounds such as benzene, toluene, and xylenes from hydrocarbon stream. These solvents are organo-sulfur compound which is readily soluble in the water due to high polarity of oxygen-sulfur compounds.
Fresh solvents are not considered to be corrosive for carbon steel and stainless-steel components, however improper application and handling of this solvents will result in degradation of this products. The degradation is basically occurring due to various factors such as solvent from upstream units, reaction with oxygen, high temperatures, high level of chlorides, pH, chemical injection, use of water and method of regenerating the solvents.
These solvents decomposition products are acidic in nature that will results in serious corrosion issues in carbon steel and stainless-steel material in the form of pitting, thinning, gouging and corrosion-erosion damage mechanism. Such failures will result in various consequences subject to health, safety, environment as well as cost/economic impacts including damage to company assets and reputation
This units required high attention subject to material selection philosophy, in-service inspection methodology and control over operating process parameters to avoid issues subject to solvent corrosion damage mechanism. This paper will describe all the factors in details that will help in mitigating the corrosion challenges in aromatic extraction units
The primary purpose of the Benzene Extraction Unit (BEU) is to extract benzene from the reformate splitter side-cut stream. In addition, a raffinate stream, very low in aromatics content and a toluene-rich stream are produced for gasoline blending.
The Benzene Extraction Unit (BEU) are licensed with technology to process from the reformate splitter side-cut stream. In addition to the Benzene product, a raffinate stream with very low aromatics content and a toluene-rich stream are produced for gasoline blending.
The solvent section consists of the Extractor and Stripper Section, Recovery Column Section, Solvent Regeneration, and the Benzene Fractionation Section, A schematic diagram of the BEU is presented in Figure-1.
