Gasoline stabilization column

Debutanizer/gasoline stabilization column - Separates LPG (C3-C4) from product gasoline stream. 

The effluent from the last reactor is cooled and sent to a separator, from which hydrogen-rich gas is removed and recycled to the reactors. The liquid product flows to a stabilizer column, where entrained gases are removed, before going to the gasoline blender or aromatics plant. 

The approach is best demonstrated with an example. Here, we will examine potential control strategies for the stabilizer column described in Workshop Exercise 7. The stabilizer is designed to remove volatile components from potential gasoline blend stocks. The feed is usually a mixture of C3, C4, and C5. In this case, the feed contains 5 per cent propane, 40 per cent isobutane, 40 per cent n-butane, and 15 per cent isopentane. The total flow rate is 40 000 bbl day at 720 kPa and 30°C. 

Before the Net Liquid enters the gasoline stabilizer, we must heat the product to a temperature suitable for fractionation. In the actual refinery process, the product heater is often integrated with the bottoms outlet of the gasoline splitter or other columns. However, for the purposes of this simulation we use a simple heat exchanger instead. For more detailed simulations, we advise the use of cross exchangers to accurately model the model the duty required for the fractionation. 

However for the single-column scheme, both light and heavy naphtha fractions are fed to the main column. If they are taken together as overhead liquid product, there will need to be a downstream stabilizer and a naphtha splitter to produce the gasoline streams for treatment. 

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