Asymmetric Electrostatic Field Coupling Membrane Gas Dehydration Process

Gas dehydration is of great significance in many fields such as environment, energy and chemical production. Gas dehydration on using polymer membranes shows broad application which based on its unique advantages. Membrane material with better separation performance and optimization of membrane processes is very urgent to be developed. Membrane gas dehydration refers to use of the difference in the rate of water vapor diffusion and dissolved with other gases to achieve gas separation in the mixed gas under the pressure difference driving force across the membrane.This paper mainly study the process of water vapor remove from nitrogen, by attaching and designing needle-plate electrode in the membrane pool to form asymmetrical electrostatic field, which allow the mass transfer process to take place in the coupled-field formed by pressure field and asymmetric electrostatic field to optimize the membrane separation process. Static gradient force generated by asymmetric electrostatic field makes the polar water molecules to accelerate permeation, while nitrogen molecule polar will not be affected. The asymmetric electric field can improve the water flux and separation performance at the same time. We use the PEBA/PSF composite membrane in the experiment, effects of electric field ((including voltage, the scope of single needle electrode) and operating conditions (vacuum pressure and temperature) and membrane parameters (membrane thickness and membrane types) on water flux were studied. Mass transfer model of the coupling field were established. Results show that under the same experimental conditions, addition of an asymmetric electric field increased water permeation flux. Water flux was increased by 47.4% at 4kV where vacuum pressure is 20 kPa, electrode distance was 23.5 mm in a needle-plate electric field.