(40g) Totally Open Pressure Swing Adsorption Intensification Laboratory (toPSAil)

In this contribution, we present an open-source software program written in MATLAB® called Totally Open Pressure Swing Adsorption Intensification Laboratory (toPSAil), capable of simulating breakthrough experiments and pressure swing adsorption (PSA) processes.

A few commercial PSA process simulation tools are currently available, including Aspen Adsorption (formerly AdSim), AVEVA Process Simulation Adsorption Library, PSE gPROMS ProcessBuilder Adsorption Library, and ProSim Dynamic Adsorption Column Simulation. However, these tools have some significant shortcomings. First, none of them are open source, so researchers cannot modify the source codes to implement new ideas in PSA process modeling. Second, correctly specifying all the input parameters for is difficult in general and fine tuning a such simulation requires a trial-and-error procedure. Third, existing simulators only support a limited set of adsorption isotherms and adsorption rate models, which excludes significant new modeling advances and is often insufficient for emerging PSA systems, such as those based on kinetic selectivity. These three issues are elaborated further in the following paragraphs.

While there exist in-house PSA process simulators, no other code for PSA process simulation exists as open source. This means there is no direct and unified framework where the overall development of the simulation tool can take place. This localized development is limiting the global advancement of PSA process simulation. Furthermore, while modifying a source code can be risky, not being able to do so presents more severe predicament for implementing new research ideas. For instance, implementing a novel control strategy for PSA processes requires a fundamental reformulation in the process model and modifications in the solution algorithm; without modifying the source codes, a such idea cannot readily be realized.

To simulate a PSA process, a plethora of input parameters need to be accurately specified by the user. Moreover, such inputs can significantly influence the simulation output quite substantially. While necessary inputs can be obtained from independent PSA process and breakthrough experiments, this approach remains impractical when it comes to designing a novel PSA process. In this case, the user will have to identify a working set of inputs by a trial-and-error procedure. For instance, the user must specify inputs for making operation and design decisions such as volumetric flow rates, and a pressure ratio, just to name a few. Unfortunately, such procedure is prone to generate an unworkable PSA process with sub-optimal process performance metrics.

The current set of state-of-the-art adsorption isotherm and rate models implemented in PSA process simulators are inadequate for simulating emerging class of novel cyclic adsorptive mechanisms. For instance, for kinetically driven PSA processes, a transient overshoot phenomenon is not captured by a traditional LDF adsorption rate model. This is an example of a serious limitation of the currently available simulation tools. While there are recent developments in adsorption isotherm and rate models available in the literature, such models are not readily incorporated into the process simulators yet, seriously limiting the scope of applications for novel PSA processes.

toPSAil provides an open source environment where researchers can actively carry out and test new ideas by modifying the internals of the PSA process simulator. To address the general challenge of making acceptable operational and design decisions, toPSAil provides the valve-free operation policy, which allows the user to systematically make such decisions in a logical manner and be able to successfully evaluate predicted performance metrics with a high fidelity. Furthermore, toPSAil is equipped with recent advancements in adsorption isotherm and rate models in the literature, enabling the simulation of novel PSA process technologies.