Shortcut Distillation Agung Ari Wibowo, S.T., M.Sc Politeknik Negeri Malang Malang - Indonesia
The use of separation column in HYSYS The column utilities in HYSYS can be used to model a wide variety of chemical separation techniques including absorption, liquid-liquid extraction and distillation
Shortcut distillation The primary purpose of the shortcut distillation is to allow for users to perform a first pass estimate on the performance requirements of a given system for a specified reflux ratio. The values gathered from the shortcut distillation utility can be used to assist the user when setting up the complete distillation utility in HYSYS, or when attempting to find reasonable column properties to allow the system to converge (e.g. number of trays, feed location, etc.)
Shortcut distillation The shortcut distillation utility within HYSYS allows users to quickly model a distillation separation of a stream with relatively little known information. Once the user attaches a fully defined inlet stream to the shortcut distillation column, the essential information that must be specified are as follows: The vapor/liquid quality of the top product The light key component and composition in the bottoms product The heavy key component and composition in the distillate (top) product The condenser pressure The reboiler pressure The external reflux ratio
Shortcut distillation What is Light and Heavy Key? Light Key : a lighter component means a component with a lower boiling point. Defined as lightest component in the bottom product in a significant amount Heavy key : a heavier component means a component with a higher boiling point. Defined as heaviest component in the overhead product in a significant amount. *Note : Both Light and Heavy key depend on the component inthe stream
Shortcut distillation With this information, the utility will run and, if possible, converge on a solution that will meet the key component specifications. The critical information that the utility will calculate are as follows: Fully specified distillate product stream (temperature, pressure, flow rate, composition) Fully specified bottom product stream (temperature, pressure, flow rate, composition) Condenser operating temperature and heat duty Reboiler operating temperature and heat duty Minimum number of trays (calculated by Fenske Methode) Actual number of trays (minimum/theoritical tray devided by tray efficiency) Optimum feed tray location Reflux minimum (Calculated by Underwood Methode)
A distillation column is used to separate mixed compound of Benzene, Case Toluene and p-xylene. Feed entering to the column at 20 C and 1 atm with mass flow 500 kg/hr. The attempt of this separation process is to get benzene with purity of 99.9% (top product only Benzene and Toluene). And the benzene composition at the bottom will be 0.1%. If the column operate isobarically and R= 1.18 Rm. What is the composition of the product (top and bottom), and what is the temperature of reboiler (Use Peng-Robinson as Fluid Package)? Feed Composition Mole Fraction Benzene 0.35 Toluene 0.25 p-xylene 0.40
Case
Case
Case
Case
Case
Case 2 ` Ethyl benzene is produced by the reaction of ethylene and benzene. The reactor which being used has the maximum conversion of 80% and operated adiabatically. The feed of the reactor consist of pure ethylene, benzene and recycle stream from Flash Separator. The product from the reactor is cooled to 64 C, and then flash separated. The bottom product of the Flash Separator will be separated using distillation column to get high purity E-benzene. If the column bottom product only consist of Benzene and E-benzene in which the mole fraction of benzene is 0.1% and in the Top product the mole fraction of E-Benzene is 0.01%, determine in which stage feed should enter the column? Column operated isobarically. C2H4 + C6H6 C8H10 Component Benzene Ethylene Temperature (C) 25 25 Pressure (atm) 1 1 Molar Flow (kmol/hr) 500 450 Fluid Package (Peng- Robinson) R = 1.26 Rm Distillate Phase : Vapor
Case 2
Case 2