Processes, Volume 6, Issue 6 (June 2018) – 11 articles

Considering the issue caused by the tail gas of viscous oil fire flooding, which carries a large amount of jeopardizing liquid, the Liaohe Oilfield No. 56 desulfurization station applies the vertical processing separator as the main dehumidification equipment for moisture elimination. However, the lack of study on the separator’s gas–liquid separation mechanism leads to unclear recognition of the equipment’s processing capability, which easily causes the desulfurization tower to water out, and the tail gas gathering network system to get frozen and blocked. To result in a solution to the problems above, numerical simulation software is applied in this paper based on the oil field’s actual operation data to establish a mathematical model for calculation, which may assist in simulating the gas–liquid separating process, in analyzing the flow field distribution within the separator, and in studying the dehumidification mechanism in terms of influencing factors and laws of equipment dehumidification efficiency. Finally, this helps optimizing the separator’s structure based on the calculation results. The research results provide a theoretical basis and technical support for the practical application of dehumidification equipment in oil fields. Full article

A low-temperature drying with fluidized bed dryer (FBD) for wheat germ (WG) stabilization could prevent the loss of nutrients during processing. However, both evaporation and condensation behaviors occurred in sequence during FBD drying of WG. The objective of this study was to develop a theoretical thin-layer model coupling with the macro-heat transfer model and the bubble model for simulating both the dehydration and condensation behaviors of WG during low-temperature drying in the FBD. The experimental data were also collected for the model modification. Changes in the moisture content of WG, the air temperature of FBD chamber, and the temperature of WG during drying with different heating approaches were significantly different. The thermal input of WG drying with short heating time approach was one-third of that of WG drying with a traditional heating approach. The mathematical model developed in this study could predict the changes of the moisture content of WG and provide a good understanding of the condensation phenomena of WG during FBD drying. Full article

NaA zeolite membrane is an ideal hydrophilic candidate for organic dehydrations; however, its instability in salt solutions limits its application in industries as the membrane intactness was greatly affected due to the replacement of cation ions. In order to explore the relationship between the structural variation and the cation types, the obtained NaA zeolite membranes were treated by various monovalent and divalent cations like Ag⁺, K⁺, Li⁺, NH₄⁺, Zn²⁺, Mg²⁺, Ba²⁺ and Ca²⁺. The obtained membranes were subsequently characterized by contact angle, scanning electron microscopy (SEM), pervaporation (PV), and vapor permeation (VP). The results showed that all of the hydrophilicities of the exchanged membrane were reduced, and the membrane performance varied with cation charges and sizes. For the monovalent cations, the membrane performance was largely determined by the cation sizes, where the membrane remained intact. On the contrary, for the divalent cation treatments, the membrane separation was generally reduced due to the presence of cation vacancies, resulting in some unbalanced stresses between the dispersive interaction and electrostatic forces, thereby damaging the membrane intactness. In the end, a set of gas permeation experiments were conducted for the two selected cation-treated membranes (K⁺ and Ag⁺) using H₂, CO₂, N₂ and CH₄, and a much higher decreasing percentage (90% for K⁺) occurred in comparison with the permeation drop (10%) in the PV dehydration, suggesting that the vaporization resistance of phase changing for the PV process was more influential than the water vapor transport in the pore channel. Full article

Grinding is a staple size-reduction process to produce food powders in which the powdered form is chemically and microbiologically stable and convenient to use as end products or intermediate products. The moisture content of food materials before grinding is a particularly important factor, since it determines the materials’ physical properties and the powder properties, such as flowability after grinding. Generally, the moisture content of food materials is closely related to its energy requirement for grinding, because the energy expenditure required to create new surfaces varies. Grinding models used to analyze and predict the grinding characteristics, including energy, have been developed in many studies. The moisture content also influences powder flow properties. The inter-particle liquid bridges among the particles are due to the moisture in powders; therefore, the flowability of powders is interrupted because of the increase of the cohesiveness of the powder. Understanding the grinding characteristics related to various moisture contents is, theoretically and experimentally, an important cornerstone in optimizing the grinding processes used in food industries. In this review, comprehensive research of the effect of moisture content on the grinding process and powder properties is presented. Full article

The increasing demands for water and the dwindling resources of fresh water create a critical need for continually enhancing desalination capacities. This poses a challenge in distressed desalination network, with incessant water demand growth as the conventional approach of undertaking large expansion projects can lead to low utilization and, hence, low capital productivity. In addition to the option of retrofitting existing desalination units or installing additional grassroots units, there is an opportunity to include emerging modular desalination technologies. This paper develops the optimization framework for the capacity planning in distressed desalination networks considering the integration of conventional plants and emerging modular technologies, such as membrane distillation (MD), as a viable option for capacity expansion. The developed framework addresses the multiscale nature of the synthesis problem, as unit-specific decision variables are subject to optimization, as well as the multiperiod capacity planning of the system. A superstructure representation and optimization formulation are introduced to simultaneously optimize the staging and sizing of desalination units, as well as design and operating variables in the desalination network over a planning horizon. Additionally, a special case for multiperiod capacity planning in multiple effect distillation (MED) desalination systems is presented. An optimization approach is proposed to solve the mixed-integer nonlinear programming (MINLP) optimization problem, starting with the construction of a project-window interval, pre-optimization screening, modeling of screened configurations, intra-process design variables optimization, and finally, multiperiod flowsheet synthesis. A case study is solved to illustrate the usefulness of the proposed approach. Full article

For the shipbuilding industry worldwide, work-related accidents at the construction site have been a major concern. Workers at the shipyards are consistently exposed to dangerous environments and their intensity of work is quite high. Considering the complexity of the shipbuilding process, efficient communications between workers are essential in the workplace, but current communication methods, which mostly use wireless technologies, are sometimes limited by the structural blocks, creating shadow areas where the radio bands cannot reach. As a countermeasure, SUNCOM Co., Ltd in the Republic of Korea has developed the PLC-based communication system followed by establishing a test-bed facility in cooperation with SK Telecom Co., Ltd and the Hyundai Heavy Industries Co., Ltd. This system and applied technologies are expected to reduce accidents in the field and be applied for other industries having the same problem, providing an uninterrupted communication environment and safer working conditions. The solution adopted this time can provide mobile communication services inside the ship during shipbuilding, thereby enabling rapid processing of work reports and instructions and fast responses to disaster occurrence, contributing to improvements in work efficiency in shipbuilding yards and ensuring workers’ safety. Full article

Physico-chemical modelling and predictive simulation are becoming key for modern process engineering. Rigorous models rely on the separation of different effects (e.g., fluid dynamics, kinetics, mass transfer) by distinct experimental parameter determination on lab-scale. The equations allow the transfer of the lab-scale data to any desired scale, if characteristic numbers like e.g., Reynolds, Péclet, Sherwood, Schmidt remain constant and fluid-dynamics of both scales are known and can be described by the model. A useful model has to be accurate and therefore match the experimental data at different scales and combinations of process and operating parameters. Besides accuracy as one quality attribute for the modelling depth, model precision also has to be evaluated. Model precision is considered as the combination of modelling depth and the influence of experimental errors in model parameter determination on the simulation results. A model is considered appropriate if the deviation of the simulation results is in the same order of magnitude as the reproducibility of the experimental data to be substituted by the simulation. Especially in natural product extraction, the accuracy of the modelling approach can be shown through various studies including different feedstocks and scales, as well as process and operating parameters. Therefore, a statistics-based quantitative method for the assessment of model precision is derived and discussed in detail in this paper to complete the process engineering toolbox. Therefore a systematic workflow including decision criteria is provided. Full article

Healthy fish production requires intensive care and ensuring stable and healthy production environment inside the farm tank is a challenging task. An Internet of Things (IoT) based automated system is highly desirable that can continuously monitor the fish tanks with optimal resources utilization. Significant cost reduction can be achieved if farm equipment and water pumps are operated only when required using optimization schemes. In this paper, we present a general system design for smart fish farms. We have developed an optimization scheme for water pump control to maintain desired water level in fish tank with efficient energy consumption through appropriate selection of pumping flow rate and tank filling level. Proposed optimization scheme attempts to achieve a trade-off between pumping duration and flow rate through selection of optimized water level. Kalman filter algorithm is applied to remove error in sensor readings. We observed through simulation results that optimization scheme achieve significant reduction in energy consumption as compared to the two alternate schemes, i.e., pumping with maximum and minimum flow rates. Proposed system can help in collecting the data about the farm for long-term analysis and better decision making in future for efficient resource utilization and overall profit maximization. Full article

In solid backfill coal mining (SBCM), loose gangue backfill material (LGBM) is used to backfill the goaf after coal resources are exploited from the underground mines. Under certain geological conditions, LGBM with a certain height may be soaked in the water, and then becomes saturated, significantly altering its mechanical properties. The confined compression experiments were used in this paper to analyze the deformation and the crushing characteristics of LGBM with varying water soaked heights in coal mines. The results showed that a large number of small holes that were distributed in the gangue blocks were the main reason why the material absorbed water and was softened. The crushing ratio and the maximum axial strain of LGBM samples gradually increased with the water soaked heights of the samples. In addition, there was a strong linear correlation between the crushing ratio and the maximum axial strain. When LGBM was used as a solid backfill material in SBCM, its deformation resistance would significantly decrease after it was soaked in the water. Higher water soaked height of LGBM led to lower deformation resistance and greater influence on the quality of backfilling. This research has great significance in getting a deep and better understanding of the mechanical properties of LGBM, as well as guiding engineering practice. Full article

We report the application of a recently proposed approach for modeling biological systems using a maximum entropy production rate principle in lieu of having in vivo rate constants. The method is applied in four steps: (1) a new ordinary differential equation (ODE) based optimization approach based on Marcelin’s 1910 mass action equation is used to obtain the maximum entropy distribution; (2) the predicted metabolite concentrations are compared to those generally expected from experiments using a loss function from which post-translational regulation of enzymes is inferred; (3) the system is re-optimized with the inferred regulation from which rate constants are determined from the metabolite concentrations and reaction fluxes; and finally (4) a full ODE-based, mass action simulation with rate parameters and allosteric regulation is obtained. From the last step, the power characteristics and resistance of each reaction can be determined. The method is applied to the central metabolism of Neurospora crassa and the flow of material through the three competing pathways of upper glycolysis, the non-oxidative pentose phosphate pathway, and the oxidative pentose phosphate pathway are evaluated as a function of the NADP/NADPH ratio. It is predicted that regulation of phosphofructokinase (PFK) and flow through the pentose phosphate pathway are essential for preventing an extreme level of fructose 1,6-bisphophate accumulation. Such an extreme level of fructose 1,6-bisphophate would otherwise result in a glassy cytoplasm with limited diffusion, dramatically decreasing the entropy and energy production rate and, consequently, biological competitiveness. Full article

Computational fluid dynamics (CFD) is a powerful tool to model fluid flow motions for momentum, mass and energy transfer. CFD has been widely used to simulate the flow pattern and temperature distribution during the thermal processing of foods. This paper discusses the background of the thermal processing of food, and the fundamentals in developing CFD models. The constitution of simulation models is provided to enable the design of effective and efficient CFD modeling. An overview of the current CFD modeling studies of thermal processing in solid, liquid, and liquid-solid mixtures is also provided. Some limitations and unrealistic assumptions faced by CFD modelers are also discussed. Full article