The feed position calculated by the simplified algorithm is negative
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Using simplified calculations, yes – but how are the light components and heavy components defined? For example, in the separation of water, propanol, and butanol, the product taken from the top of the tower consists mainly of water along with small amounts of propanol and butanol, while the bottom of the tower contains 99.9% butanol. So, when using simplified calculations, is water considered the light component and propanol the heavy component, or is it the other way around? When I specified water as the light component and butanol as the heavy component, ASPEN’s calculation indicated that separation was too easy – a very low reflux ratio was required, and the number of theoretical plates was less than 1. When propanol was designated as the light component and butanol as the heavy component, the separation met the required standards; however, the calculated feed position was negative, as shown in the figure below
An azeotrope exists; use Radfrac
Through property analysis, if an azeotrope is present, simple methods yield inaccurate results; therefore, the rigorous method should be used for calculations. Initial values need to be assigned reasonably based on experience... Process optimization is carried out through sensitivity analysis and design specifications...