One operating parameter of the solvent recovery tower in the aromatics extraction unit is the stripping water ratio, which is the ratio of stripping water volume to solvent circulation volume. ...
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According to the data, the stripping water ratio will affect the content of aromatic hydrocarbons in the lean solvent and bring out the aromatic hydrocarbons. What is the principle? Is it because water and aromatics form an azeotrope? I don’t understand it very well, please ask the experts to explain it. Many thanks! ! !
The solvent regeneration tower is essentially a vacuum evaporator. Its function is to remove polymers and solid residues in the solvent to purify the solvent, thereby ensuring the cleanliness of the entire solvent system. The main factors that affect the solvent regeneration operation include residual pressure, regeneration tower bottom temperature, etc. The overhead gas of the solvent regeneration tower is directly returned to the bottom of the solvent recovery tower, and its operating pressure is determined by the operating pressure of the solvent recovery tower. In order to avoid solvothermal degradation, the solvent regeneration temperature is usually controlled at 170~177°C. In the presence of oxygen, sulfolane decomposes rapidly and generates corrosive sulfonic acid. In order to avoid equipment corrosion, the pH value of the solvent system needs to be controlled between 6 and 9. Monoethanolamine is added to the solvent system as a corrosion inhibitor to adjust the pH value of the solvent system. It can be seen from the figure that the stripping water ratio has a significant impact on the hydrocarbon content in the lean solvent. The temperature at the bottom of the recovery tower is controlled at 170~177°C. When the stripping water ratio increases from 0.008 to 0.012, the toluene content in the lean solvent decreases rapidly. When the stripping water ratio further increases from 0.016 to 0.02, the effect on reducing the toluene content in the lean solvent is significantly reduced. Therefore, the more suitable stripping water ratio range is approximately 0.012~0.018. Effect of Stripping Water Ratio on Hydrocarbon Content in Lean Solvent
Thank you very much for your answer. But why does stripping water affect the aromatic hydrocarbon content in lean solvent? Is it because of the formation of an azeotrope of water and aromatics?
1. The selectivity of water is greater than aromatic hydrocarbons, so a high stripping water ratio can release the aromatic hydrocarbons extracted from the solvent. 2. It reduces the gas phase partial pressure of aromatic hydrocarbons, making it easier for aromatic hydrocarbons to evaporate.