Modelling and process control research

by Noraini Mohd

Modelling and control are vital components of chemical and process engineering. The basic idea in modelling is to mimic what we normally experience and observe in real life, as well as make specific predictions in a more quantitative and precise manner.

Such a model can then be used to represent a real process and enable researchers to study certain behaviours of the process in a surrogate world – the computer.

Any system from the size of an atom to that of the globe, either natural or man-made, can maintain its orderly behaviours and structures, and hence its existence through a device called ‘the control’.

To build a good control device, a great deal of knowledge about the process is required and this knowledge can be extracted from a process model.

Why is control important? Even a simple unicellular microorganism may possess within its cell hundreds of thousands of controllers that help the organism adapt to constantly changing environments. Such sophisticated designs in the natural world have been adapted in numerous man-made systems since the dawn of human civilisation.

However, a man-made control system might still be relatively crude in comparison to even the simplest form of control system found in a single-cell microorganism, yet man-made control devices have enabled the running of complex manufacturing plants, the tracking of rocket trajectories and many other applications.

In recent decades, with the advance of computer technology, modelling and process control has become one of the most popular courses in the field of chemical and process engineering.

Despite its popularity, it is perceived to be a tough and expensive course to undertake. This is not true as it can be relatively easy and affordable, and furthermore has high research potential, giving students a high chance of graduating on time (GOT).

Easy and low cost

Modelling is a process where a researcher builds a virtual model to represent a real process. Process control, on the other hand, involves building controllers to control the process where these controllers are often tested on the built model in a computer.

Both techniques can be carried out using various simulation software in the computer environment. Researchers may only have to wait for a few minutes or hours for the simulation to complete and produce results. In a real process environment, the equivalent experiment could take a few days or even weeks to complete. Thus, modelling can save a great deal of time.

Furthermore, the estimated cost to conduct a study in the area of modelling and process control could be as low as RM20,000 (not including student allowances and fee) for a period of three years. It does not require big grants that are usually required for real experimental study and, in most cases, does not involve costs for any field work.

Production of hydrogen fuel as a future green energy resource

One current research conducted at the Curtin Sarawak Research Centre (CSRI) is Modelling and Control of Hydrogen Production Plant via Sulphur-iodine Thermochemical Water Splitting Process. It aims to produce environmental-friendly hydrogen fuel for the transportation sector.

For this process, a pilot plant alone would cost millions of dollars where the heat source for the process would be obtained either from a solar or a nuclear power plant. This would require highly robust safety measures in such a pilot plant, but at Curtin Sarawak, the research involves building a model and controller for the process by means of simulation.

Instead of working with hazardous chemicals such as sulphur, iodine and sulfuric acid as well as dealing with critically high temperatures, the researchers need only simulate a virtual model to represent the real process using a simulation software.

This research involves the entire thermochemical cycle process and takes into account all the recycle lines of the process throughout the system. The result of this simulation is then compared with real experimental results available and the model is validated using real data to ensure that the model developed is accurate and robust.

Simulation has made a major impact on the chemical process industry. Firstly, it is cheaper to use simulation techniques incorporating fundamental laboratory data in the mathematical model than it is to build numerous pilot plants of different sizes.

Secondly, it is a convenient way to repeatedly investigate the effects of the system parameters and process disturbances.

Thirdly, simulations are a reasonable way of extrapolating performance of scaling up processes, for example, lab-scale process to plant scale process. Ultimately, it provides a better understanding of the behaviour and mechanics of the simulated process.

Graduate on time (GOT)

Research based on laboratory experiment requires students to wait for a certain period to purchase chemicals or equipment before commencing their research work. For research requiring field work, students may face uncertainty due to weather, the absence of subjects to interview, or technical difficulties in the field.

Researchers using modelling, simulation and process control will not face such problems. As long as there is a functional computer and appropriate software, the research can be carried out at any time. What is also needed, of course, is drive and determination on the part of the researcher to ensure the success of the study.

Noraini Mohd. is a PhD candidate from the Faculty of Engineering and Science, Curtin Sarawak. She can be contacted at 085-44 3966 or by email to noraini.mohd@postgrad.curtin.edu.my.

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