Reasons for the excessively high content of poor solvent benzene
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I have set the pressure control for the solvent recovery tower at -40 KPa, the temperature control at 172 degrees, and the gas-to-water ratio at 1300 PPm. Recently, the benzene content in the lean solvent has been high, reaching up to 8000 PPm; I would appreciate some suggestions for adjustments
How do you calculate the ratio of water used for stripping? Our processing capacity is 10 tons per hour; the solvent is recycled in an amount of around 35 tons, while the water used for stripping is about 1 ton
Raise the bottom temperature to the design value. The bottom temperature of the solvent recovery tower is usually 175°C, and the amount of stripping steam is 1-3% w of the lean solvent. Calculate whether it is sufficient; if not, it can be increased slightly. Also, have you confirmed that the benzene content in the poor solvent is 8000 ppm? Or total hydrocarbons? Generally, levels below 2w% are acceptable. The total hydrocarbon content in the lean solvent on my end is between 8,000–13,000 ppm, and there is no benzene present in the raffinate oil.