Development of an automated dual piston pressure swing adsorption system
Abstract
Thousands of different adsorbate materials are developed every day. However, current
instruments are not able keep up with testing the materials and faster methods needed. This
thesis described the development and automation of a, a novel DP-PSA (Dual Piston-Pressure
Swing Adsorption) setup. It is a unique system suited to test novel materials for the efficient
separation of binary mixtures in a single adsorption column. The DP-PSA is a closed system
where pistons moving in cylinders at each end of the adsorbent column induce the cycling of
fluid flows and pressure variations in the fixed bed. The equipment can be assimilated to a
distillation column with total reflux and allows the measurement of the maximum separation
achievable with the material. Pressure transducers to measure absolute pressure variations and
pressure drops are placed at the top and at the bottom of the column, respectively. Four
thermocouples inside the column are placed in two pairs at different positions along the column.
In each pair one thermocouple is inserted into a zeolite pellet while the other is exposed to the
gas phase. The apparatus is automated by LabVIEW code and controlled by a real time
computer, Compact RIO. Thus, the automated DP-PSA is able to run a series of experiment
without direct supervision.
The development of the DP-PSA includes experiment design, measurement of leak rates, dead
volumes for packed and unpacked column, friction, pressure drop across the adsorbing column
and temperature gradient along the column. The system with thermocouples can be run in two
modes: single pellet experiments and full packed column runs. Single pellet experiments, where
only the pellets connected to the thermocouples are inside the system, were carried out to study
the heat transfer between the zeolite pellets and gases (He, N2, CO2, and mixtures of N2 and
CO2). The other mode is that the adsorbing column is packed fully with zeolite pellets.
Experiments with pure gases and mixtures of N2 and CO2 were run with different
configurations of the system: cycle time; phase angle; stroke length ratio and initial temperature.
The system was tested using commercial 13X pellets. The measured signals were compared
based on the amplitude and time shifts and numerical simulations were used to compare the
predictions of a dynamic model of the system with the experimental results. The DP-PSA has
been shown to generate a very large set of experimental results, with varying conditions which
allows to determine physical parameters of dynamic models. This is achieved without
consuming gases given that several experiments are automatically carried out in a closed
system. Thousands of different adsorbate materials are developed every day. However, current
instruments are not able keep up with testing the materials and faster methods needed. This
thesis described the development and automation of a, a novel DP-PSA (Dual Piston-Pressure
Swing Adsorption) setup. It is a unique system suited to test novel materials for the efficient
separation of binary mixtures in a single adsorption column. The DP-PSA is a closed system
where pistons moving in cylinders at each end of the adsorbent column induce the cycling of
fluid flows and pressure variations in the fixed bed. The equipment can be assimilated to a
distillation column with total reflux and allows the measurement of the maximum separation
achievable with the material. Pressure transducers to measure absolute pressure variations and
pressure drops are placed at the top and at the bottom of the column, respectively. Four
thermocouples inside the column are placed in two pairs at different positions along the column.
In each pair one thermocouple is inserted into a zeolite pellet while the other is exposed to the
gas phase. The apparatus is automated by LabVIEW code and controlled by a real time
computer, Compact RIO. Thus, the automated DP-PSA is able to run a series of experiment
without direct supervision.
The development of the DP-PSA includes experiment design, measurement of leak rates, dead
volumes for packed and unpacked column, friction, pressure drop across the adsorbing column
and temperature gradient along the column. The system with thermocouples can be run in two
modes: single pellet experiments and full packed column runs. Single pellet experiments, where
only the pellets connected to the thermocouples are inside the system, were carried out to study
the heat transfer between the zeolite pellets and gases (He, N₂, CO₂, and mixtures of N₂ and
CO₂). The other mode is that the adsorbing column is packed fully with zeolite pellets.
Experiments with pure gases and mixtures of N₂ and CO₂ were run with different
configurations of the system: cycle time; phase angle; stroke length ratio and initial temperature.
The system was tested using commercial 13X pellets. The measured signals were compared
based on the amplitude and time shifts and numerical simulations were used to compare the
predictions of a dynamic model of the system with the experimental results. The DP-PSA has
been shown to generate a very large set of experimental results, with varying conditions which
allows to determine physical parameters of dynamic models. This is achieved without
consuming gases given that several experiments are automatically carried out in a closed
system.