Chemical engineering of cellular processes

Processes conducted by living cells determine the quantity and quality of our food, medicines, environment and our personal health and vitality. The functions of cells in these contexts are determined primarily by networks of specific catalytic and noncovalent interactions. The nature and activities of these networks are dictated by the DNA in the cell and the history of the cell's environment, thereby defining the ways in which engineers can influence cellular function. The onslaught of quantitative and qualitative knowledge in molecular biology, combined with the emergence of powerful and precise genetic, biochemical, chemical, analytical, and mathematical technologies, have defined the working framework and the needed tools for a systematic chemical engineering approach to creation and optimization of cellular processes to serve better the needs of mankind and our environment. Several recent examples demonstrate how chemical engineers are mobilizing this information and capability to address critical problems in bioprocessing, medicine, and in the generation of new molecules and materials. These examples illustrate the ability of chemical engineers to be more actively involved in the creation of products and processes, an essential endeavor for the future vitality of the profession.     

Chemical engineering for the Anthropocene

The environmental and resource crises that confront human life on earth demand changes to the whole socio-economic metabolic system. The changes will affect all aspects of life, including the practice of chemical engineering. The historical association of the profession with the fossil carbon economy means that the expertise that makes up chemical engineering must be re-examined and repurposed urgently if the discipline is to play a full role in the socio-economic transition. In this article, we review the historical development of chemical engineering to identify its unique features and find ways in which it can change to meet the challenge. A pattern of 30-year cycles in the development of the discipline is revealed, showing the way it has built up by incorporating approaches from other disciplines and also developing a unique set of skills and knowledge. Chemical engineering as taught needs to prepare graduates to operate under the kind of social contract embodied in declarations by professional bodies. We propose ways in which the expertise comprising chemical engineering can be applied in the ‘just transition’ to a less unsustainable society, including new approaches to plant and process design and also applications ‘outside the pipe’ to environmental modelling and industrial ecology. The unsustainability crisis results from a history of poor public and private decisions, so examination of the different types of decisions is timely. Specific roles for chemical engineers in deliberative decision processes are identified, including enhanced emphasis on risk and precaution.     

Reliability of complex chemical engineering processes

This paper presents a stochastic performance modelling approach that can be used to optimise design and operational reliability of complex chemical engineering processes. The framework can be applied to processes comprising multiple units, including the cases where closed form process performance functions are unavailable or difficult to derive from first principles, which is often the case in practice. An interface that facilitates automated two-way communication between Matlab^® and process simulation environment is used to generate large process responses. The resulting constrained optimisation problem is solved using both Monte Carlo Simulation (MCS) and First Order Reliability Method (FORM); providing a wide range of stochastic process performance measures. Adding such capabilities to traditional deterministic process simulators provides a more informed basis for selecting optimum design factors; giving a simple way of enhancing overall process reliability and cost-efficiency. Two case study systems are considered to highlight the applicability and benefits of the approach.     

Reaction engineering of emerging oxidation processes

A review of the recent developments in emerging multiphase catalytic oxidation processes for the manufacture of various key chemicals, and an overview of reaction engineering principles needed for reactor design and interpretation of performance are presented. The utility of combining a knowledge of the catalytic chemistry through fundamental mechanisms and kinetics with transport effects and hydrodynamics using recent advances in experimental methods is also discussed and reviewed with reference to liquid phase oxidation.     

Scaleup of wet granulation processes: science not art

Significant advances have been made in the last decade to quantify the process of wet granulation. The attributes of product granules from the granulation process are controlled by a combination of three groups of processes occurring in the granulator: (1) wetting and nucleation, (2) growth and consolidation and (3) breakage and attrition. For the first two of these processes, the key controlling dimensionless groups are defined and regime maps are presented and validated with data from tumbling and mixer granulators. Granulation is an example of particle design. For quantitative analysis, both careful characterisation of the feed formulation and knowledge of operating parameters are required. A key thesis of this paper is that the design, scaleup and operation of granulation processes can now be considered as quantitative engineering rather than a black art.     

Chemical engineering aspects of reactive dyeing

The process of dyeing with reactive dyes was formulated on the basis of diffusion of dye species in the pores of polymer phase accompanied by fixation reaction with fiber substrate on the pore wall incorporating hydrolysis of dye species. The effect of the hydrolysis on the fractional fixation was numerically analyzed under various levels of bath ratio and degree of mixing in the dyebath. The simulation model was presented to yield the unlevelness arisen from lack of uniformity of degree of mixing in the dyebath.