This thesis is concerned with the design, operation and control of pressure
swing adsorption (PSA) systems, employing state of the art system engineering
tools. A detailed mathematical model is developed which captures the hydrodynamic,
mass transfer and equilibrium effects in detail to represent the real PSA
operation.
The first detailed case study presented in this work deals with the design of an
explicit/multi-parametric model predictive controller for the operation of a PSA
system comprising four adsorbent beds undergoing nine process steps, separating
70 % H2, 30 % CH4 mixture into high purity hydrogen. The key controller
objective is to fast track H2 purity to a set point value of 99.99 %, manipulating
time duration of the adsorption step, under the effect of process disturbances.
To perform the task, a rigorous and systematic framework is employed comprising
four main steps of model development, system identification, the mp-MPC
formulation, and in-silico closed loop validation, respectively. Detailed comparison
studies of the derived explicit MPC controller are also performed with the
conventional PID controllers, for a multitude of disturbance scenarios.
Following the controller design, a detailed design and control optimization
study is presented which incorporates the design, operational and control aspects
of PSA operation simultaneously, with the objective of improving real time operability.
This is in complete contrast to the traditional approach for the design
of process systems, which employs a two step sequential method of first design
and then control. A systematic and rigorous methodology is employed towards
this purpose and is applied to a two-bed, six-step PSA system represented by a
rigorous mathematical model, where the key optimization objective is to maximize
the expected H2 recovery while achieving a closed loop product H2 purity
of 99.99 %, for separating 70 % H2, 30 % CH4 feed. Furthermore, two detailed
comparative studies are also conducted. In the first study, the optimal design and
control configuration obtained from the simultaneous and sequential approaches
are compared in detail. In the second study, an mp-MPC controller is designed to
investigate any further improvements in the closed loop response of the optimal
PSA system.
The final area of research work is related to the development of an industrial
scale, integrated PSA-membrane separation system. Here, the key objective is
to enhance the overall recovery of "fuel cell ready" 99.99 % pure hydrogen, produced
from the steam methane reforming route, where PSA is usually employed
as the purification system. In the first stage, the stand-alone PSA and membrane
configurations are optimized performing dynamic simulations on the mathematical
model. During this procedure, both upstream and downstream membrane
configuration are investigated in detail. For the hybrid configuration, membrane
area and PSA cycle time are chosen as the key design parameters. Furthermore,
life cycle analysis studies are performed on the hybrid system to evaluate its
environmental impact in comparison to the stand-alone PSA system
