Polymers and Integrated Systems Engineering

Our projects involve scientific and applied research on the synthesis of polymer colloids, and the modelling, optimization and control of polymer manufacture via emulsion, dispersion and living free-radical polymerization. These processes are environmentally beneficial due to the use of water as the dispersing medium and the modest temperature and pressure requirements. Our scientific approach to develop models using population balances and the governing transport equations for batch, semi-batch and continuous polymerization is enabling fundamental understanding of the complex processes and enhanced product formulation. A number of postgraduate and post-doctoral researchers are working in association with the centre from Australia and overseas.

Particulate products are ubiquitous in the industry. Thus, we have engaged in significant research with producing particulate systems having the desired properties such as the particle size distribution, the molecular weight distribution, conversion, flow properties, etc. Many such processes lack the availability of on-line instrumentation for closed loop control. For example, the turbidity and (milky-white) appearance of polymerization reactor contents preclude the use of light-based sensors for monitoring the status. Thus, inexpensive alternative means such as soft-sensors are being developed for this purpose.

Our research developments in modelling, advanced process control, fault detection/diagnosis and artificial intelligence are applicable to a number of complex systems, including the minerals, chemical, petrochemical and environmental processes. Our "soft-sensors" are finding increasing use with substantial benefits in process operation, optimization and control in coatings, food and agricultural applications.

Projects in polymers:

Model-based control of polymerization reactors
Expert systems for polymerization processes
Scale-up and coagulum formation in polymerization reactors
Living controlled polymerization.

For new projects/details please contact:
Dr. Vincent Gomes (V.Gomes at usyd.edu.au)
School of Chemical and Biomolecular Engineering
The University of Sydney
Sydney, NSW 2006

Laboratory Facilities

The laboratory facilities are instrumented, monitored and controlled using state-of-the-art equipment. A consortium of software and industrial partners provided substantial contributions towards the equipment, infrastructure and research support.

Polymer Laboratory

Reactor Facilities
The laboratory is equipped with state-of-the-art facilities valuable in production and characterization of a variety of polymeric materials.

The polymerization reactor facilities comprise of:

a 5 L acketed stirred tank reactor (STR)
a 1 L jacketed stirred tank reactor (STR)
two Julabo heating circulators to provide heating/cooling to the reactor via the jacket and heating/cooling coils;
6 PLC controlled dosing pumps to provide controlled doses of monomers, surfactants, initiators, etc to the reactor;
4 precision balances to measure quantities consumed;
6 RTDs for precision temperature mmeasurements.

The laboratory is provided with a Honeywell C200 industry-standard controller supported by Honeywell PlantScape DCS. The control configuration schemes are supported by a Control Builder (Honeywell PlantScape r500.1) suite. The flow controllers, thermal transducers, analogue inputs/outputs, digital outputs and the 4-port serial to Ethernet converter are interfaced to the Honeywell system. The RTDs are used measure temperatures within the reactors, the jackets and heating/cooling coils. The Ethernet converter is used for transmitting signals from the input/output devices to the controller.

The reactor systems are controlled in conjunction with Inferential Model Predictive Control algorithms. An intelligent control hierarchy has been formulated incorporating multiple layers of supervisory control via expert system, offline optimization, on-line MPC and regulatory control successively.

Particle Size Distribution (PSD)
The hydro-dynamically based particle analyzer (HDC, PL-PSDA) is used for the measurement of average particle size and particle size distribution in complex mixtures. The instrument provides accurate distribution measurements of nano-sized particles (2-5000 nm).

Molecular Weight Distribution (MWD)
Gel Permeation Chromatography (GPC) for the measurement of average molar mass, molar mass distribution and molecular radius of gyration of polymeric and biological materials.

Thermal Analysis

Differential Scanning Calorimetry
The Seiko EXSTAR6000 Disk Station controls the differential scanning calorimeter (DSC 220C). These modules allow complete testing of polymer and composite properties over a wide range of temperatures. Further, this equipment enables rapid development of optimized processing conditions for materials without the need for full scale processing.
The DSC enables the determination of the melt, crystallization and glass transition of materials, as well as the heat capacity. The DSC 220C is designed to provide automatic heating and cooling measurements. Temperatures ranging from -150C to +725C are possible, with heating rates programmable from 0.01 - 100C/min. The DSC system offers a direct way to observe self-assembly and phase transitions in lipid, surfactant, polymer and protein systems. Through comparison between the sample and a reference system, melting and other transitions in a range of systems may be monitored.

Thermo Gravimetric Analysis (TG/DTA)
The TG/DTA enables the precise simultaneous measurement of weight change, while indicating critical transitions, such as the glass transition. The TG/DTA has a temperature range from room temperature to 1100C, and covers a range of application areas.

Dynamic Mechanical Analysis (DMA)
For simultaneous measurement of thermal transition temperatures and mechanical properties (available through Mechanical Engineering, University of Sydney).

Nuclear Magnetic Resonance (NMR)
For determination of polymeric material chemical structure, composition and chemical chain sequence (available through Biochemistry, University of Sydney).

Scanning Electron Microscopy (SEM)
For the determination of physical material structure (available through The Electron Microscope Unit (EMU), University of Sydney).

Integrated Reaction and Separation Systems

Many industrially important chemical reactions are limited by the equilibrium conversion of reactants within a feed and product mix. For most chemical processes, the effluent from the reactor is separated into unconverted reactants, by-products and products. The unconverted feed is usually recycled, and the products and by-products are separated for meeting requisite specifications.

Process Intensification (PI) through integrated reaction and separation, presents one of the most important trends in today’s process technology. It consists in the development of innovative processes that offer drastic improvements in chemical manufacturing and processing, substantially decreasing equipment volume, energy consumption, or waste formation, and ultimately leading to cheaper, safer, sustainable technologies.

This combining of the reaction and separation steps in a single unit operation known as reactive separation process (RSP) or integrated reactive separation (IRS) and the process unit is called a multifunctional reactor.

The potential advantages of process integration are:

Greater productivity
Higher selectivity
Reduced energy consumption
Improved safety
Reduced catalyst requirement
Achieve difficult separations
Heat transfer integration
Avoidance of chemical wastes.

Design and Operation
Despite the research effort on process synthesis over the last two decades, very few systematic procedures have been proposed for the synthesis of reactor-separator-recycle systems. Existing approaches often use heuristics.
The interaction of several process steps in a single equipment, the steady-state and dynamic behaviour of integrated process units are often much more complex than that of a single unit. Thus, methods for the design and control of integrated processes need development to ensure optimal operation of the integrated process. This project deals with the problem at the core of chemical processes - creating a structure for the reaction-separation-recycle system through innovative methods.

Figure: Characterization with Micromeritics ASAP 2010

Figure: Schematic of Multifunctional Reactor Facility

Metathesis Reaction

Integrated Design, Optimization and Control

The emphasis in industry on energy savings, sustainable processes and environmental protection has driven process systems engineers, including design and operations engineers, to incorporate a number of crucial steps in developing integrated designs of chemical processes. Design teams are required to integrate the process with control to satisfy economical, environmental and social objectives, while at the same time achieving optimal performance.

Ethene Epoxidation
This work is addresses the advanced control and operation of the ethylene oxide reactor. Five key strategies were identified for this purpose and are outlined below:

Steady sate and dynamic modelling
CFD model of the shell side of the reactor
Process optimisation and advanced control
Data reconciliation and rectification