Chemical Engineering Principles Research Articles

Development of Efficient Designs of Cooking Systems. II. Computational Fluid Dynamics and Optimization

Sections 2–6 of Part I were devoted to the analysis of heat transfer characteristics of cookers. In all the experiments, only water was employed as a working medium. Now, we extend such an analysis to the actual cooking process in order to arrive at an improved cooking device. The major strategies for the optimization of energy utilization is to design appropriate insulation that has been obtained by two cover vessels. In order to select an air gap, the flow and temperature patterns in the air gap have been extensively analyzed using computational fluid dynamics (CFD). The flow pattern and heat transfer in cooking pots have also been analyzed by CFD. This has enabled us to design suitable internals for minimizing the stratification of temperature. The understanding of fluid mechanics has also given basis for selection of heat flux, gap between burner tip and cooker bottom, and temperature of flue gases leaving the cooker. Chemical engineering principles have been used for modeling and optimization. Kinetics have been obtained in batch cookers. The knowledge of kinetics, thermal mixing, axial mixing, and optimum selection of insulation have been employed for the development of continuous cookers. The continuous mode of operation also helps in saving of energy. Systematic data have been collected for the design and scale up of continuous cookers.

The Success and Outlook of JCEPT

Journal of Chemical Engineering & Process Technology (JCEPT) continues to represent a premier Open Access to a broad range of topics relevant to principles of chemical reaction engineering, heat transfer, mass transfer, fluid mechanics, physical chemistry, and biochemical engineering and process. It has an impressive history of publishing the most exciting researches in the interdisciplinary field of Chemical Engineering & Process Technology to a worldwide readership through the Internet with a rapid turn-around time.

Non-ideal flow in an annular photocatalytic reactor

This study deals with the modelling of non-ideal flow in a tubular photocatalytic reactor with thin layer of TiO2 photocatalyst. The objective was to analyse different level of mixing in the photoreactor applying basic principles of chemical reaction engineering. For this purpose photocatalytic oxidation of toluene was used as the model reaction. Photocatalytic reactor was operated in two different flow modes: classic type of an annular reactor with basically ideal (plug) flow with some extent of dispersion and annular flow reactor acted as stirred tank reactor with mixing of reaction mixture accomplished by recirculation. A series of experiments with step input disturbance at the entrance of the reactor with different air flow was performed in order to achieve better understanding of the reactor hydrodynamics. Several reactor models are applied, such as one dimensional model of tubular reactor at the steady state conditions, axial dispersion model at non-stationary conditions and the model of the continuous non-stationary stirred tank reactor. Numerical methods necessary for solving model equations and parameter estimation were described.

Simulation and Analysis of an Ethylene Slurry Polymerization System Using Supercritical Propane

In this paper, a model for an ethylene slurry polymerization system using supercritical propane as a solvent is developed by adopting a set of thermodynamic and kinetic parameters using fundamental chemical engineering principles and Polymers Plus software. The Ziegler–Natta catalyst is characterized by assuming the existence of multiple types of catalyst sites and deconvolution data from gel permeation chromatography to determine the most probable chain-length distribution and relative amounts of polymer produced at each site type. A set of suitable reaction subclasses and kinetic constants for different site types that fit plant conditions is developed, validating our model. The values calculated for production rate, ethylene conversion, residence time, H2/C2H4 molar ratio in the reactor, number-average molecular weight, and polydispersity index are all close to actual values, verifying that our model accurately describes plant conditions.

The protective role of dissolved carbon dioxide against wine oxidation: a simple and rational approach

<p style="text-align: justify;"><strong>Aims</strong>: During wine making, oxygen and carbon dioxide are often simultaneously present in the liquid phase. We propose a simple rational approach, based on usual chemical engineering and thermodynamic principles, to provide understanding and practical rules for controlling the effects of these two dissolved gases, and especially their inter-relationship. Furthermore, this study proposes an explanation for the “protective” effect against oxidation, which is reported when high concentrations of carbon dioxide are present in musts and wines.</p><p style="text-align: justify;"><strong>Methods and results</strong>: The theoretical quantitative relation, termed “binary gas equilibrium line”, between the maximum possible concentration of dissolved oxygen in respect to dissolved carbon dioxide was derived and, in our experiments, corresponded to C<sub>O2max</sub> ≅ -0,005 C<sub>CO2</sub> + 7,9 mg.L<sup>-1</sup>. Specific saturation experiments using simultaneous injection of air and gaseous carbon dioxide were performed and the experimental results allowed us to validate this theory in the case of gas bubbling in a liquid.</p><p style="text-align: justify;"><strong>Conclusion</strong>: It is shown that complete protection is only obtained when carbon dioxide is generated by the fermentation in the liquid. An interesting parallel conclusion is that micro-oxygenation is totally inefficient in such periods. In the case where there is no production of CO<sub>2</sub> but where a high initial dissolved carbon dioxide concentration is present, the “protective” effect acts only by reducing the rate of oxygen transfer.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: The physical understanding of this phenomenon can be found in the fact that as soon as a gaseous air or pure oxygen phase is in contact with a carbon dioxide saturated liquid, the dissolved carbon dioxide, which is not at equilibrium with the gaseous phase, tends to escape into this gaseous phase. This study points out the complexity of the gas-liquid equilibrium when two dissolved gases are simultaneously present in a liquid and its implication in the winemaking process.</p>

Chemotherapeutic Engineering: Concept, Feasibility, Safety and Prospect—A Tribute to Shu Chien’s 80th Birthday

This article is made for the special issue of Cellular and Molecular Bioengineering—“Mechanobiology: A Tribute to Shu Chien’s Scientific Achievement” for his 80th Anniversary. Shu Chien is well known as a founder and pioneer of bioengineering. He is the only one in the world who simultaneously holds six academicians: US National Academy of Sciences, US National Academy of Engineering, US Institute of Medicine, and American Academy of Arts and Sciences, as well as Chinese Academy of Sciences and Academia Sinica Taiwan. As one of Shu Chien’s PhD students at Columbia University, the author emphasizes in this article the significant contribution of Professor Shu Chien in creating and defining chemotherapeutic engineering as an emerging and prospective multidisciplinary area, which is defined as application and further development of engineering especially chemical engineering principles to solve the problems in chemotherapy of cancer and other fatal diseases such as cardiovascular disease and AIDS. Proof-of-concepts experimental results obtained so far are summarized. Safety issue is addressed. Prospect and outlook are described. In the author’s point of view, chemotherapeutic engineering may change the way we make drugs and the way we take drugs, and will thus make significant contribution to the twentieth century medicine.

Steady-State and Dynamic Modeling of the Basell Multireactor Olefin Polymerization Process

In this work, we developed the steady-state and dynamic models for the commercial polypropylene process of Basell Spheripol technology, involving fundamental chemical engineering principles and advanced software tools, i.e., Polymers Plus and Aspen Dynamics. The models considered the important issues of physical property and thermodynamic model selection, catalyst characterization, and reactor model. Besides, a multisite catalyst with traditional Ziegler−Natta polymerization kinetics was introduced to describe the broad molecular weight distribution of the polymers produced in this polypropylene technology. Both the continuous stirred tank reactor model and the combined plug flow reactors model were proposed to simulate the reactors. Furthermore, we validated the models using industrial data and demonstrated application of the dynamic model to grade change, start up, and shut down at a certain emergent accident.

Nanomaterials synthesized by gas combustion flames: Morphology and structure

The flame technology has been employed broadly for large-scale manufacture of carbon blacks, fumed silica, pigmentary titania, and also ceramic commodities such as SiO 2, TiO 2, and Al 2O 3. A deeper understanding of the process also made it possible for production of novel nanomaterials with high functionality—various novel nanomaterials such as nanorods, nanowires, nanotubes, nanocoils, and nanocomposites with core/shell, hollow and ball-in-shell structures, have been synthesized recently via gas combustion technology, while the mechanisms of the material formation were investigated based on the nucleation-growth and chemical engineering principles. Studies of the fluid flow and mass mixing, supported by principles of chemical reaction engineering, could provide knowledge for better understanding of the process, and thus make rational manipulation of the products possible.

Reactor Scale-up for Fluidized Bed Conversion of Ethane to Vinyl Chloride

Novel LaOCl/LaCl3 catalysts have been discovered that enable the production of vinyl chloride monomer from ethane. An ethane-based process would result in both capital savings and raw materials savings when compared to the current most effective vinyl technology. These materials are unique in the world of chlorination/oxychlorination as the mechanism for chlorination over LaOCl/LaCl3 occurs on a catalyst without a redox metal center, unlike the conventional CuCl2 catalysts used for oxychlorination, where the Cu species are reducible. This report focuses on the engineering approaches taken and the challenges encountered in the scale-up of a fluidized bed reactor based on this catalyst technology. The objective is to highlight the application of chemical reaction engineering principles to an industrial reactor scale-up, with special attention to the unexpected and atypical challenges encountered in this development effort.

Structure controlling and process scale-up in the fabrication of nanomaterials

Nanotechnology is already having a significant commercial impact, and will very certainly have a much greater impact in the future. The research on process engineering and scale-up will be very important for the commercial production and application of nanomaterials, because the properties and structure of nanomaterials are not only determined by the nucleation and growth process, but also strongly affected by the engineering properties, such as the mixing, the heat and mass transfer, and also the distribution of temperature, concentration, etc. This paper will present some research work in our laboratory on the fabrication of nanomaterials. Based on the chemical engineering principle and methods, many kinds of novel nanomaterials can be synthesized and their structure can be easily controlled through adjusting the parameters of the fluid mixing, and the distribution of temperature, residence time and concentration, etc. By using the micro-mixing, heat and mass transfer and reaction control methods, the host-guest nanocomposites have been assembled and assumed as the novel electroanalytical sensing nanobiocomposite materials. Based on the principles of chemical engineering, the manufacturing technologies for magnetic powders, calcium carbonate, and titanium dioxide have been developed for commercial-scale production, and the largest production scale has reached 15 kt/year.

Roll-to-Roll Deposition of a Semiconductor Film on a Flexible Substrate for Photovoltaics: Conception to Reality

T. W. Fraser Russell has made significant contributions to process engineering advances relating to the commercialization of photovoltaic technology. He recognized that its commercial viability would require the application of sound chemical engineering principles to solve a very nontraditional chemical engineering problem—in particular the engineering methodologies needed to transfer thin-film deposition processes from the laboratory scale into commercial production. In this paper, a historical narrative, spanning the late 1970s through the present day, is presented detailing Fraser’s contributions to the development of photovoltaic film deposition on a continuous moving web via thermal evaporation.

Steady-state and dynamic modeling of commercial bulk polypropylene process of Hypol technology

Both steady-state and dynamic models for the commercial bulk polypropylene process of HYPOL technology were developed by using fundamental chemical engineering principles and advanced software tools, Polymers Plus and Aspen Dynamics. The models consider the important issues of physical property and thermodynamic model selections, catalyst characterization, and reactor model, in addition to the traditional Ziegler–Natta polymerization kinetics. The performance of equilibrium-stage modeling was examined using the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state and a pre-built reactor model in Polymers Plus. The detection of non-equilibrium behavior for the liquid-phase reactor leads to a novel reactor model suggested in this work, wherein the vapor–liquid equilibrium behavior was separated from polymerization behavior. Besides, the traditional Ziegler–Natta polymerization system was incorporated from single-site to multi-site model by fitting the actual data sourced from open reports and certain plant data. Furthermore, we validated the models using the plant data and demonstrated the application of our dynamic model by simulating a grade change.

Heading to photoswitchable magnets

The review concerns the strategic approaches to the photomodulation of the magnetic properties of molecular hybrid compounds combining magnetic and optical properties. The approaches developed include photocontrol of intra- and intermolecular magnetic coupling and manipulation of the effect of the photochromic sublattice on the bulk behavior of molecular magnets. In the framework of the first approach, we consider photoinduced charge-transfer phase transitions, changes in the spin state of magnetic centers, photoswitching of intramolecular exchange interactions between magnetic centers connected by a photochromic bridge, and generation of high-spin organic molecules forming high-spin groups due to intermolecular exchange interactions. In the framework of the second approach, we discuss hybrid polyfunctional compounds combining magnetic and photochromic sublattices in the same crystal lattice, as well as intercalation of organic photochromes into voids or inter-layer space of organic magnetics (or vice versa). Creation of such materials allows not only several functions to be combined in the same lattice, which is important for reducing the size of hardware components, but also these properties to be controlled and modified through synergistic effects. The results of basic research suggest that novel materials for various practical applications can be created using principles of crystal chemical engineering.

A macroscopic agglomeration kernel model for gibbsite precipitation in turbulent and laminar flows

A macroscopic agglomeration kernel model has been developed that is capable of describing gibbsite agglomeration over a broad range of process conditions, including both the laminar and turbulent flow regimes. The agglomeration kernel model was derived using chemical reaction engineering principles and data from an extensive experimental program covering a wide range of temperatures, supersaturations, seed sizes, shear rates and mixing regimes. The experimental precipitation data in the laminar flow regime were generated using a novel Taylor–Couette precipitator. Data in the turbulent regime were generated in a stirred reactor. The developed agglomeration kernel model incorporates terms for the collision, capture, rupture and cementation rates affecting the formation of agglomerates. The model is shown to be able to predict the data from independent experiments. The proposed model also captures the complex non-linear shear rate and size-dependency observed experimentally, e.g. (1) for small particles the agglomeration kernel exhibits a maximum with respect to the shear rate, increasing at low shear rates in the laminar flow, but decreasing in the unstable Taylor–Couette flows and turbulent regimes; (2) for large particles the agglomeration kernel decreases monotonically with increasing shear.

PROCESS CONTROL PERSPECTIVE FOR PROCESS ANALYTICAL TECHNOLOGY: INTEGRATION OF CHEMICAL ENGINEERING PRACTICE INTO SEMICONDUCTOR AND PHARMACEUTICAL INDUSTRIES

FDA's Process Analytical Technology (PAT) initiative provides an unprecedented opportunity for chemical engineers to play significant roles in the pharmaceutical industry. In this article, the authors provide their perspectives on (1) the need for chemical engineering principles in pharmaceutical development for a thorough process understanding; (2) applications of chemical engineering principles to meet the challenges from the semiconductor and pharmaceutical industries; and (3) the integration of chemical engineering practice into the semiconductor and pharmaceutical industries to achieve process understanding and the desired state of quality-by-design. A real-world case study from the semiconductor industry is presented to demonstrate how a classic chemical engineering concept, mixing homogeneity, can be implemented by inducing forced flow to ensure an excellent copper electrochemical plating process performance and to improve product quality substantially. Further, a case study of brake system design is discussed with the concept of Dr. Taguchi's robust engineering design to illustrate how quality-by-design can be achieved through appropriate experimental design, in conjunction with the discussion on the concept of quality-by-design in pharmaceuticals. Third, a case study of freeze-dried sodium ethacrynate is presented to demonstrate the vital importance of controlling the processing factors to achieve the desired product stability. Finally, the problems of the current pharmaceutical manufacturing mode, the opportunities and engineering challenges during implementation of PAT in the pharmaceutical industry, and the role of chemical engineering in implementation of PAT is discussed in detail.

Design and Implementation of a Novel Quench Flow Reactor for the Study of Nascent Olefin Polymerisation

AbstractA novel stopped flow reactor system is described in the current work, along with the underlying design philosophy. While the concept of stopped flow technology is not recent, this system is the first to be designed with the objective of studying particle morphology, and to work at extremely short (40 ms) residence times. It is shown that traditional chemical engineering principles are required to properly design and operate this type of reactor, and that when correctly design, it is a very flexible tool for the study of nascent polymerisation of olefins.magnified image

Steady-State and Dynamic Modeling for New Product Design for the Solid-State Polymerization of Poly(Ethylene Terephthalate)

We model an entire poly(ethylene terephthalate) (PET) solid-state polymerization (SSP) process with precrystallizers, crystallizers, SSP reactors, and dryers using a unified cell approach. This approach builds complex unit-operation models using individual cells, or continuous-stirred-tank reactor (CSTR) models. Each cell considers the essential physical properties, phase equilibrium, polymerization kinetics, mass transfer through the polymer and into the carrier gas, and crystallization kinetics. Our model development involves fundamental chemical engineering principles and advanced software tools, such as Polymers Plus and Aspen Custom Modeler. We analyze both reaction and diffusion in each cell, considering two options: (1) to model diffusion using a second-order partial differential equation (PDE) or a simplified two-film theory and (2) to include or ignore crystallization kinetics. Performing best is the model with a PDE for diffusion and with equations describing crystallization and its effect on reaction and diffusion. We validate the model using commercial plant data of intrinsic viscosity, degree of crystallinity, and acetaldehyde concentration. We are unable to find a suitable set of parameters for other simpler models to represent accurately the plant data in its entirety. After validating our SSP model, we apply it to study the sensitivity of our SSP process on temperature and pellet geometry. For pellets with cross-sectional dimensions of 3.2 mm × 3.2 mm, we vary the length from 1.5 to 3.5 mm and predict the intrinsic viscosity. The model suggests only a mild dependence of intrinsic viscosity on the pellet length. In contrast, our model suggests that, for an increase in temperature of 12 °C, intrinsic viscosity rises by almost 0.1 dL/g. Last, we use our validated model to predict the process changes required to produce a high-viscosity product (1 dL/g). Our model suggests that, with appropriate increases in both reactor temperature and residence time, we can make this product.

Food Engineering as an Advancing Branch of Chemical Engineering

During the past two decades, application of established chemical engineering principles in food industry has rapidly become an important branch of chemical engineering. Challenges faced by engineers and technologists have been in the areas of preserving the original food quality, creating new food structures in large quantities and at high rates. Active ingredients within foods that are good for human consumption must be kept within acceptable limits. Collaborations with food and nutrition scientists and microbiologists, microelectronic engineers etc. are an essential element for success. Studies have been conducted at all scales (from molecular (nano scale), macromolecular, to macroscopic and large scales such as packaged foods). In the area of chemical engineering education, there is an increasing amount of interest in introducing chemical engineering students to food related concepts. Both Australia and New Zealand have very large agri-food businesses. The challenges due to the specific materials (food materials) concerned in R & D have led to many inventions that have great potentials in new food development. In this lecture, the advances made in food engineering research and new technology development will be highlighted.

Design of a Fuel Cell Power System for Automotive Applications

In this paper, the primary components of a PEM fuel cell for automotive applications, using methane as a fuel, are analyzed. Basic chemical engineering principles are utilized to assess the role of thermodynamics, heat transport, and reaction kinetics. The amount of methane required is calculated as function of hydrogen produced as well as the power produced. The heat duty for thermal control of the system is analyzed.

Sustainable development and its implications for chemical engineering

Sustainable development presents us all with the challenge of living in ways which are compatible with the long-term constraints imposed by the finite carrying capacity of the closed system which is Planet Earth. The chemical engineering approach to the management of complex systems involving material and energy flows will be essential in meeting the challenge. System-based tools for environmental management already embody chemical engineering principles, albeit applied to broader systems than those which chemical engineering conventionally covers. Clean technology is an approach to process selection, design and operation which combines conventional chemical engineering with some of these system-based environmental management tools; it represents an interesting new direction in the application of chemical engineering to develop more sustainable processes. Less conventional applications of chemical engineering lie in public sector decisions, using the approach known as post-normal science. These applications require chemical engineers to take on a significantly different role, using their professional expertise to work with people from other disciplines and with the lay public. The contribution of chemical engineering to the formation of UK energy policy provides an example of the importance of this role. Recognising the role of engineers as agents of social change implies the need for a different set of skills, which just might make the profession more attractive to potential new recruits.