Mathematical modeling of a continuous solution polymerization reactor: case-study MMA polymerization

In this paper, the dynamics of the free radical polymerization of methyl methacrylate (MMA) in a cooling jacketed continuous reactor were investigated. The modeling stage has been conducted regarding several underlying phenomena so to obtain the most accurate model as we can. Like most of the chemical processes, the mathematical model exhibits high interaction and nonlinearity. To control this system several methods can be implemented to control the system. However, the design of an efficient and reliable control strategy requires, in most cases, the linearization and decoupling of the model equations. In this first part of a paper series the process model is developed and validated prior to the implementation of a fuzzy control strategy

Spherical agglomeration of benzoic acid using membrane emulsification

Spherical agglomeration (SA) is a key crystal shape modification technique commonly used to improve processability and physical properties of active pharmaceutical ingredients (APIs), such as flowability and dissolution. SA involves the introduction of a bridging liquid in the form of droplets into a suspension of API crystals. A novel approach was successfully implemented in this study by adopting a membrane emulsification (ME) system to control the size of bridging liquid droplets and spherical agglomerates. The study investigated ways to achieve the critical quality attributes of the spherical agglomerates by varying operating conditions and design parameters, including mixing rate, bridging liquid injection rate and membrane pore diameter. Antisolvent crystallization of benzoic acid in ethanol (solvent) and water (antisolvent) in presence of toluene as a bridging liquid was used as a case study. Spherical agglomerates of benzoic acid with enhanced quality attributes and mean size of 300 μm were obtained using a membrane pore size of 18 μm, a bridging liquid flow rate of 0.025 mL/min and mixing rate in the range of 800 RPM and 1000 RPM

Control methodologies for robust operation of a nucleator + growth cascade crystallizer: model based steady state and start-up optimization [Abstract]

Control methodologies for robust operation of a nucleator + growth cascade crystallizer: model based steady state and start-up optimization [Abstract

Towards a novel microfluidic device for synthesis of gold nanoparticles for drug delivery

Towards a novel microfluidic device for synthesis of gold nanoparticles for drug deliver

Towards more accurate and reliable mathematical model for steam gasification [Abstract]

Over the last decade, renewable energy has undergone unprecedented growth and development because of the increasing need for cleaner and more environmental friendly technologies. Hydrogen is one of the most important renewable energy that can be employed in many applications e.g. fuel cell technologies. Biomass, including municipal solid waste, is also a potential option for producing hydrogen and they can be converted through the thermochemical process particularly gasification, which is a technology that can produce H2 on both small and large scales using just air or steam as the oxidizing agents. Developing accurate and highly predictable model for the gasification is essential for process design and optimization. In order to predict the product gas composition and the amount of hydrogen produced from the gasification process precisely, the simulation of the mathematical models to present the behaviors and properties of gases is needed to be developed. Different types of gasification models are used to predict the maximum yield of the product gases based on thermodynamic equilibrium1. In addition, different simulators have been developed, such as Aspen Plus model type, but still not predictable enough compared to the experimental data2. The objective of this work is to develop more precise equilibrium model for the biomass steam gasification using Gibb’s energy minimization and Lagrange multiplier method. A rigorous and systematic procedure was developed to improve parameter estimation, using global optimization approach, which enhances the prediction capabilities of the mathematical model

Wet-mill aided continuous cooling mixed suspension mixed product removal crystallizer [Abstract]

Wet-mill aided continuous cooling mixed suspension mixed product removal crystallizer [Abstract

State feedback linearization and adaptive model predictive control applied to a simulated MSMPR crystalliser [Abstract]

State feedback linearization and adaptive model predictive control applied to a simulated MSMPR crystalliser [Abstract

Droplet-based microfluidic method for robust preparation of gold nanoparticles in axisymmetric flow focusing device

A novel microfluidic mixing strategy was developed and used to prepare polyvinylpyrrolidone (PVP) capped gold nanoparticles (AuNPs). In this process, 1 mM tetrachloroauric acid (HAuCl4) stream containing 1% (w/v) PVP was injected through the inner capillary tube and mixed with 20 mM L-ascorbic acid solution delivered co-currently through the outer coaxial capillary. The reaction mixture was hydrodynamically flow focused by the environmentally friendly oil Miglyol 840 delivered from the opposite side of the outer capillary, which resulted in the generation of reaction droplets in a tapered collection tube. The reactants were rapidly mixed within droplets by internal circulating flows induced by hydrodynamic interactions of fluids inside the droplets with the carrier oil. The size of the prepared AuNPs was measured by both dynamic light scattering and transmission electron microscopy and was found to decrease with decreasing the droplet size and increasing the difference in velocity between the two reactant streams, which improved mixing efficiency within droplets. The smallest nanoparticles were obtained when the outlet section of the injection tube was positioned at the entry section of the collection tube due to the highest shear at the liquid interface. The carrier oil formed a hydrophobic barrier between the droplets and the reactor walls preventing deposition of the synthesised particles. As a result, the size of the AuNPs was smaller than in the co-flow mixer operated with two continuous reactant streams

A comparative life cycle assessment approach of 5 alternative technologies for converting municipal solid waste (MSW) into chemicals and electricity in the UK

This study develops a systematic life cycle assessment approach for 5 alternative technologies that can be used to convert municipal solid waste (MSW) into chemicals and electricity. Particular attention is given to the combustion and gasification as the main conversion processes and the UK’s MSW is used here as the case study. The investigation focusses on 5 different scenarios: (1) combustion and electricity generation, (2) gasification and electricity generation, (3) methanol synthesis from syngas with electricity co-production (4), dimethyl ether (DME) synthesis from produced methanol by syngas (indirect synthesis) and power generation, and (5) DME synthesis from syngas (direct synthesis) and electricity co-production. The unreacted gas left from the methanol or DME synthesis process can also be employed as a fuel gas for the electricity generation. As the result, it is interesting to find out which method is the most appropriate and optimal to convert the UK’s MSW. The environmental impacts are evaluated by IMPACT2002+ method using Ecoinvent 3 as a database. The results show that scenario 5 (direct DME synthesis with electricity co-production) causes the least climate change impact (532 kg CO2 eq.) and resource impact (-5560 MJ primary), followed by scenario 4 (544 kg CO2 eq. and -5250 MJ primary), scenario 3 (569 kg CO2 eq. and - 4820 MJ primary), scenario 1 (591 kg CO2 eq. and -3880 MJ primary) and scenario 2 (881 kg CO2 eq. and -3900 MJ primary) respectively. However, the study also demonstrates that the scenarios involving methanol and DME synthesis have more impacts on human health category due to the required metal oxide catalysts. The impact of a change in total yield of methanol and DME synthesis is also investigated and analysed along with the associated potential environmental benefits

Input-output state feedback linearization and model predictive control of an MSMPR crystalliser [Abstract]

Input-output state feedback linearization and model predictive control of an MSMPR crystalliser [Abstract