Noor Asma Fazli Bin Abdul Samad

A generic multi-dimensional model-based system for batch cooling crystallization processes

A generic multi-dimensional modelling framework for crystallization processes has been developed to study various aspects of batch cooling crystallization operations and modelling options. The framework contains a generic crystallizer model from which a wide range of problem-system specific models can be created through a model generation procedure. The modelling framework allows one to study a wide range of chemical (crystallization) systems as well as different crystallizer operation phases (scenarios) through choices of different forms of models for phenomena such as nucleation, crystal growth, agglomeration and breakage. Applications of the modelling framework are highlighted through: (i) a paracetamol crystallization case study illustrating the ability of the modelling framework to develop and further extend models and to switch between different chemical systems; and (ii) a potassium dihydrogen phosphate (KDP) case study to demonstrate how the model complexity can be changed by switching between one-dimensional and two-dimensional descriptions.

A Systematic Framework for Design of Process Monitoring and Control (PAT) Systems for Crystallization Processes

Abstract A generic computer-aided framework for systematic design of a process monitoring and control system for crystallization processes has been developed to study various aspects of crystallization operations. The systematic design framework contains a generic crystallizer modelling toolbox, a tool for generation of the supersaturation set-point for supersaturation control, as well as a tool for design of a process monitoring and control system (also called Process Analytical Technology (PAT) system). This systematic design allows one to generate the necessary problem-chemical system specific model, the necessary supersaturation set-point as well as a PAT system design including implementation of monitoring tools and control strategies in order to produce the desired target product properties notably crystal size distribution (CSD) and shape for a wide range of crystallization processes. Application of the framework is highlighted through a case study involving the design of a monitoring and control system for a potassium dihydrogen phosphate (KDP) crystallization process, where also the one-dimensional CSD and two-dimensional CSD modelling features are highlighted.

Introducing uncertainty analysis of nucleation and crystal growth models in Process Analytical Technology (PAT) system design of crystallization processes

This paper presents the application of uncertainty and sensitivity analysis as part of a systematic model-based process monitoring and control (PAT) system design framework for crystallization processes. For the uncertainty analysis, the Monte Carlo procedure is used to propagate input uncertainty, while for sensitivity analysis, global methods including the standardized regression coefficients (SRC) and Morris screening are used to identify the most significant parameters. The potassium dihydrogen phosphate (KDP) crystallization process is used as a case study, both in open-loop and closed-loop operation. In the uncertainty analysis, the impact on the predicted output of uncertain parameters related to the nucleation and the crystal growth model has been investigated for both a one- and two-dimensional crystal size distribution (CSD). The open-loop results show that the input uncertainties lead to significant uncertainties on the CSD, with appearance of a secondary peak due to secondary nucleation for both cases. The sensitivity analysis indicated that the most important parameters affecting the CSDs are nucleation order and growth order constants. In the proposed PAT system design (closed-loop), the target CSD variability was successfully reduced compared to the open-loop case, also when considering uncertainty in nucleation and crystal growth model parameters. The latter forms a strong indication of the robustness of the proposed PAT system design in achieving the target CSD and encourages its transfer to full-scale implementation.

Control of Process Operations and Monitoring of Product Qualities through Generic Model-based in Batch Cooling Crystallization

Abstract A generic model-based framework has been developed for crystallization processes, with applications aiming at the control of process operations and the monitoring of product quality. This generic model-based framework allows the systematic development of a wide range of crystallization models for different operational scenarios. This enables the design and control engineers to analyze various crystallization operations and conditions, thus facilitating the development of process control and monitoring systems (PAT systems) for crystallization processes. The generic framework has been implemented in the ICAS-PAT software which allows the user to design and validate PAT systems through a systematic computer-aided framework. The application of the framework is highlighted for batch cooling crystallization of paracetamol where the framework was applied for design of a process monitoring and control system to obtain a desired crystal size distribution (CSD).

Systematic identification of crystallization kinetics within a generic modelling framework

Abstract A systematic development of constitutive models within a generic modelling framework has been developed for use in design, analysis and simulation of crystallization operations. The framework contains a tool for model identification connected with a generic crystallizer modelling tool-box, a tool for data handling and translation as well as model application features. Through this framework it is possible, for a wide range of crystallization processes, to generate the necessary problem-system specific models; to identify the parameters for constitutive models; and to handle or translate raw crystallization data. Application of the systematic framework is highlighted through a sucrose crystallization case study, for which the parameters for nucleation and crystal growth are first estimated from the available measured data and are then applied to study the crystallization operation.

Integration of Generic Multi-dimensional Model and Operational Policies for Batch Cooling Crystallization

Abstract A generic multi-dimensional modeling framework for studying batch cooling crystallization processes under generated operational policies is presented. The generic nature of the modeling allows the study of a wide range of chemical systems under different operational scenarios, enabling thereby, the analysis of various crystallization operations and conditions. Furthermore, a systematic procedure for generating operational policies through available analytical crystal size distribution (CSD) estimators has been developed and verified for achieving targeted CSD consistently. The application of the model-based framework is highlighted for batch cooling crystallization of potassium dihydrogen phosphate (KDP) in two-dimensions, while the use of the analytical estimator is demonstrated for a potassium dichromate case study to achieve a target CSD.

Systematic procedure for generating operational policies to achieve target crystal size distribution (CSD) in batch cooling crystallization

A systematic procedure to achieve a target crystal size distribution (CSD) under generated operational policies in batch cooling crystallization is presented. An analytical CSD estimator has been employed in the systematic procedure to generate the necessary operational policies to achieve the target CSD. Furthermore, this systematic procedure has been integrated with a generic multi-dimensional model-based framework. The generic nature of the model-based framework allows the study of a wide range of chemical systems under different operational scenarios, enabling thereby, the analysis of various crystallization operations and conditions. Therefore this generic multidimensional model-based framework can be used to generate “specific” models for crystallization processes and further verify the operational policies generated by the analytical CSD estimator for achieving the targeted CSD consistently. The application of the systematic procedure is illustrated for a potassium dichromate case study.