How to determine the feed plate?
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In distillation calculations, how can the feed position of the theoretical plates be determined accurately?
It’s in the book on principles of chemical engineering!
Any book on the principles of electrical engineering will do; if you need detailed calculations, it’s recommended to use software instead
Are you referring to manual calculation or computer calculation?
It’s quite complicated, depending on factors such as feed temperature and composition.
This post was last edited by hgjoys on 2010-5-19 00:05. It’s not complicated; it’s quite simple! Determining the feed tray position in a distillation column mainly takes into account: 1. the composition of the feed, 2. the thermal properties of the feed. In essence, it is about making the thermodynamic state of the feed as similar as possible to that of the material inside the tower (note: thermal conditions and thermodynamic states are not the same thing!) ). For specific details, refer to the step method for calculating the number of theoretical plates; the steps indicate the positions of the feed plates when crossing the operating lines of the distillation section and the reboiler section.
You can refer to the Handbook of Chemical Engineering Principles and Chemical Process Design. Generally, when determining the feed level in a distillation column, the following factors are mainly considered: 1. the composition of the feed, 2. the thermal condition of the feed.
In theoretical calculations, the feed plate is generally chosen to be a tray with the same or similar composition to that of the liquid or gas phase, as well as the feed gas or liquid. The purpose is to reduce backmixing. Improve tower efficiency. However, this is generally not possible in practice. The feeding plate must be selected based on specific circumstances in order to adjust the distribution of the number of plates in the rectification section and the stripping section. Without considering efficiency issues.
The most suitable position for the feed inlet in the pre-tower is where the concentration of light fractions in the material at the inlet is equal to the concentration of light fractions in the feed. For pressure columns and atmospheric columns, the optimal location for the feed inlet is such that the water content of the material at the inlet is equal to the water content in the feed.
Based on experience, generally the feed composition is similar to that of a certain plate, and that plate is then used as the feed plate.