Edmond P. Byrne

Influence of shear on particle size and fractal dimension of whey protein precipitates: implications for scale-up and centrifugal clarification efficiency

Abstract Whey protein fractionation was carried out at laboratory scale by applying the required temperature and pH conditions in a standard configuration batch agitated vessel to cause selective precipitation and aggregation of proteins. Scale-up of this operation to pilot scale was achieved on the basis of impeller power input per unit volume resulting in similar particle sizes. Separation was subsequently achieved by high-speed disc-stack centrifugation. Processing of precipitates in pumps, valves and at the centrifuge inlet zone can lead to substantial breakage, depending on the strength of the precipitates formed and aged in the batch vessel. Such turbulent processing was mimicked at lab scale by passing the precipitate solution through a ball-valve rig while monitoring the effects on particle size and fractal geometry. Measurement of fractal dimension were used to assess the compactness of precipitates. Precipitates subjected to higher batch vessel impeller shear-rates during formation and ageing were found to be smaller, more compact and better able to resist turbulent breakage and thus should provide better feed–stock for disc-stack centrifugation at pilot scale. Clarification efficiency curves obtained for pilot-scale disc-stack centrifugation confirmed these lab-scale predictions. Recommendations for improved process design in terms of selecting suitable batch vessel shear-rates that ultimately lead to improved separation efficiencies have been made.

Investigation of how agitation during precipitation, and subsequent processing affects the particle size distribution and separation of α-lactalbumin enriched whey protein precipitates

Abstract In this work, α-lactalbumin (α-la) rich precipitate particles are formed and aged in a batch stirred-tank from a whey protein concentrate (WPC) dispersion. Precipitation of the proteins occurs during a period of acid-addition followed by an ageing period. This study investigates how stirred-tank impeller agitation and subsequent processing, by means of passing precipitate suspensions through a capillary tube or a partially open ball-valve, affect particle size and composition. Precipitate particles are largely unaffected when subjected to laminar capillary tube flow. However, as flow becomes transitional and thereafter turbulent, particle breakage increases, especially for precipitates formed and aged under mild agitation conditions. Precipitates passed through the ball-valve experience even greater particle size reduction as a sharp geometrical transition results in highly turbulent flow. Moreover, particles formed and aged under low shear conditions, though initially larger, are in fact weaker and fragment to a greater extent during turbulent processing through the ball-valve. This has process design implications for separation processes where particle size is important, as shear history can influence particle toughness. Substantial size reduction of particles can best be mitigated by identifying regions of high turbulence or sudden changes in flow geometry, and by redesigning these regions so as to reduce these effects.

Exploring sustainability themes in engineering accreditation and curricula

Purpose This paper aims to present key findings from an inquiry into engineering accreditation and curricula renewal. The research attempted to ascertain conceptions of requisite sustainability themes among engineering academics and professionals. The paper also reflects on the potential role of professional engineering institutions (PEIs) in embedding sustainability through their programme accreditation guidelines and wider implications in terms of rapid curricula renewal. Design/methodology/approach This research comprised an International Engineering Academic Workshop held during the 2010 International Symposium on Engineering Education in Ireland, on “accreditation and sustainable engineering”. This built on the findings of a literature review that was distributed prior to the workshop. Data collection included individual questionnaires administered during the workshop, and notes scribed by workshop participants. Findings The literature review highlighted a wide range of perspectives across and within engineering disciplines, regarding what sustainability/sustainable development (SD) themes should be incorporated into engineering curricula, and regarding language and terminology. This was also reflected in the workshop discussions. Notwithstanding this diversity, clusters of sustainability themes and priority considerations were distilled from the literature review and workshop. These related to resources, technology, values, ethics, inter- and intra-generational equity, transdisciplinarity, and systems and complex thinking. Themes related to environmental and economic knowledge and skills received less attention by workshop participants than represented in the literature. Originality/value This paper provides an appreciation of the diversity of opinion regarding priority sustainability themes for engineering curricula, among a group of self-selected engineering academics who have a common interest in education for SD. It also provides some insights and caveats on how these themes might be rapidly integrated into engineering curricula.

Is attending lectures still relevant in engineering education

A case study was conducted on a group of undergraduate chemical engineering students to assess the relevance of attending lectures from a student perspective and to understand why these students attend and do not attend lectures with a view to developing approaches to teaching, which are of greater interest and benefit to student learning. The students were surveyed by means of a questionnaire-type survey, which collected both quantitative and qualitative data from them. The majority of students stated that lectures are still very beneficial to their learning and are not an out-of-date mode of education. The major reasons for lecture non-attendance were time priority and curriculum overload issues with other scholarly activities and poor quality teaching. The students provided a number of suggestions to improve lectures and lecture attendance, including the incorporation of active learning in lectures, linking lectures to assessment and adding extra value to what is already in the notes.

Seeing Beyond Silos: Transdisciplinary Approaches to Education as a Means of Addressing Sustainability Issues

Sustainability is a normative topic framed by disciplinary perspectives. This can be problematic as the tools that are used and applied to meta-problems and ‘grand challenges’ associated with societal (un)sustainability, and which may result in proposed ‘sustainable solutions’, are framed through the lens of the ‘object world’ disciplinarian. Traditional engineering education and practice has tended to frame problems in narrow techno-economic terms, often neglecting broader social, environmental, ethical and political issues; or what might be termed the social complexities of problems (Bucciarelli 2008; Mulder et al. 2012). This reductionist approach has sought to close down risk and uncertainty through deterministic modelling and design, resulting in frameworks/models which provide an air of misplaced confidence but which are incapable of accounting for (or recognising) unknowability, and can thus lead to behaviour which ironically, results in increased fragility, rather than promoting increased robustness or resilience. Researchers in the social sciences and humanities are inherently more comfortable and adept with dealing with complexity, uncertainty and unknowability. This paper is posited in this context, whereby chemical engineering and sociology students taking respective disciplinary sustainability/environmental modules were brought together to work on a common assignment dealing with some aspect of sustainability. This paper reflects on this collaborative exercise, including the experiences of the students themselves, alongside some challenges and successes. It concludes that transdisciplinary approaches to learning are not just desirable in addressing wicked and meta-problems when addressing challenges of (un)sustainability, but represent a sine qua non for building the social capacity in confronting these issues.

Engaging with sustainability through collaborative and transdisciplinary approaches to education

Sustainability is a normative topic framed by disciplinary perspectives. This can be problematic as the tools that are used and applied to meta-problems and ‘grand challenges’ associated with societal (un)sustainability, and which may result in proposed ‘sustainable solutions’, are framed through the lens of the ‘object world’ disciplinarian. Traditional engineering education and practice has tended to frame problems in narrow techno-economic terms, often neglecting broader social, environmental, ethical and political issues; or what might be termed the social complexities of problems (Bucciarelli, 2008; Mulder et al., 2012). This reductionist approach has sought to close down risk and uncertainty through deterministic modelling and design, resulting in frameworks/models which provide an air of misplaced confidence but which are incapable of accounting for (or recognising) unknowability, and can thus lead to behaviour which ironically, results in increased fragility, rather than promoting increased robustness or resilience. Researchers in the social sciences and humanities are inherently more comfortable and adept with dealing with complexity, uncertainty and unknowability. This paper is posited in this context, whereby chemical engineering and sociology students taking respective disciplinary sustainability/environmental modules were brought together to work on a common assignment dealing with some aspect of sustainability. This paper reflects on this collaborative exercise, including the experiences of the students themselves, alongside some challenges and successes. It concludes that transdisciplinary approaches to learning are not just desirable in addressing wicked and meta-problems when addressing challenges of (un)sustainability, but represent a sine qua non for building the social capacity in confronting these issues.

A stochastic model for performance analysis of pharmaceutical high purity water systems

Abstract The operating performance of high purity water systems such as pharmaceutical Deionized and Water for Injection (DI/WFI) distribution systems can be difficult to analyse due to the highly variable demand that is drawn from these systems; a situation compounded by schedule and demand volume uncertainties. This work presents a stochastic model to simulate volume and schedule uncertainties of industrial size DI/WFI systems. The model utilises discrete-event simulation combined with the Monte Carlo method to calculate the demand profile of the distribution system and a continuous simulation to compute the variation of the level in the storage tank. It is shown that the model may be used to predict if an existing DI/WFI systems is capable of delivering water for a new process, for which historical data is lacking. The model is programmed in Excel 2003 and is available for download [1] as open software.

Plant and Equipment | Flow Equipment: Valves

Valves are employed to regulate flow and pressure drop in product and service fluid lines in dairy plants. Some valves have a simple open/closed mode of operation, while others can regulate flow between these two extremes. A variety of construction principles are possible to achieve the desired mode of operation. The most important feature of any valve is the relationship between the flow rate through it and the corresponding pressure drop across it. This feature must be considered for the valve itself (the inherent characteristic) and for the valve as a component of the total flow line (the installed characteristic). Equations from fluid mechanics are available to predict this depending on the nature of the flow: compressible versus incompressible, laminar versus turbulent, and so on. One particular aspect of good valve fluid flow design is the avoidance of the phenomenon of water hammer, which, if it occurs, can damage the valve and connected pipework. Hygienic design is also essential for valves in the dairy industry, and a variety of industry and regulatory bodies can supply sound guidelines in this regard. There are a number of means to actuate a valve: manually, electrically, pneumatically, or hydraulically; however, the pneumatic option is favored by dairy processors.

Comparison of deterministic and stochastic simulation for capacity extension of high-purity water delivery systems.

This work presents a deterministic and a stochastic model for the simulation of industrial-size deionized water and water for injection (DI/WFI) systems. The objective of the simulations is to determine if additional DI/WFI demand from future production processes can be supported by an existing DI/WFI system. The models utilize discrete event simulation to compute the demand profile from the distribution system; they also use a continuous simulation to calculate the variation of the water level in the storage tank. Whereas the deterministic model ignores uncertainties, the stochastic model allows for both volume and schedule uncertainties. The Monte Carlo method is applied to solve the stochastic method. This paper compares the deterministic and stochastic models and shows that the deterministic model may be suitable for most applications and that the stochastic model should only be used if found necessary by the deterministic simulation. The models are programmed within Excel 2003 and are available for download as open public domain software (1), allowing for public modifications and improvements of the model. The proposed models may also be utilized to determine size or analyze the performance of other utilities, such as heat transfer media, drinking water, etc. LAY ABSTRACT: Water for injection (WFI) and other pharmaceutical water distribution systems are notoriously difficult to analyze analytically due to the highly dynamic variable demand that is drawn from these systems. Discrete event simulation may provide an answer where the typical engineering approach of utilizing a diversity factor fails. This paper develops an Excel based deterministic and stochastic model for a WFI system with the latter allowing for the modeling of offtake volume and schedule uncertainty. The paper also compares the deterministic and stochastic models and shows that the deterministic model may be suitable for most applications while the stochastic model should only be used if found necessary. The models are available for download as open public domain software allowing for modifications and improvements of the model.

A Fuzzy Logic Model of Deionised and Water for Injection Systems for Sizing and Capacity Assessment Under Uncertainty

The operating performance of deionized and water for injection (DI/WFI) distribution systems can be difficult to analyse due to the highly variable demand that is drawn from these systems, a situation compounded by schedule uncertainties. This paper presents a fuzzy logic (FL) model of a typical DI/WFI system simulating schedule uncertainties in the opening and closing events of the offtake valves based on operator behaviour, e.g. tiredness of the operators. The model utilises discrete-event simulation to calculate the demand profile of the distribution system and a continuous simulation to compute the variation of the level in the storage tank. It is shown that the FL model may be useful in the design of new DI/WFI systems if little historical data are available.