An Apparatus for Density and VLE Measurements for Gas-Liquid Systems

  • Rashawn K. Washignton
  • Vinayak N. Kabadi
Conference paper


The Objective of this research project was to design and build and apparatus to measure density and vapor liquid equilibrium data for gas-liquid systems. This work was done in support of the National Science Foundation Science and Technology Center’s (NSFSTC) goal of identifying and enabling sustainable process and products using CO2-related technology. The apparatus consists of a syringe pump, a multi-port multi-position valve, a high pressure cell with multiple sampling ports and fitted with a magna-drive stirring system. A precision temperature oven, a pycnometer fitted with a 4-port 2-position valve and a GC with TCD and FID detectors and with on-line sampling capability. For the density measurements a required amount of liquid solvent and gas are delivered to the high pressure cell by the syringe pump, which also maintains the required pressure of the system. The cell and pycnometer are placed in the oven which maintains the desired temperature. The mixture is well-stirred and the composition is measured precisely by the on-line GC. The liquid is then passed through the trapped inside the pycnometer. The pycnometer is disconnected and weighed. The density is obtained from the mass of the liquid and the volume of the pycnometer. The apparatus can also be operated for VLE measurements. Static vapor-liquid equilibrium is achieved in the high pressure cell which is fitted with multiple dip-tubes for sample extraction. Upon equilibration the liquid and vapor samples are sent to GC for analysis. The density data for CO2-ethyl lactate system have been measured in the temperature range 25–80°C and at pressures from atmospheric to 2000 psi for a few compositions of the liquid mixtures. Measurements are continuing to cover the entire composition range for the binary system.


Pressure Vessel Check Valve Vapor Liquid Equilibrium High Pressure Cell Ethyl Lactate 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


  1. Kolagani, R., A Flow Apparatus for VLE Measurements of Carbon Dioxide Containing Systems, M.S. Thesis, North Carolina Agricultural and Technical State University, 2002Google Scholar
  2. Pena-Tejedor, S., Murga, R., Teresa Sanz, M., Beltran, S., Vapor-liquid equilibria and excess volumes of the binary systems ethanol + ethyl Lactate, isopropanol + isopropyl lactate and n-butanol + n-butyl lactate at 101.325 kPa, Fluid Phase Equilibria, 2005, 230, 197–203.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Rashawn K. Washignton
    • 1
  • Vinayak N. Kabadi
    • 1
  1. 1.Chemical EngineeringNorth Carolina A&T State UniversityGreensboroUSA

Personalised recommendations