Large-scale Units Research Articles

Analysis of granulation systems using idealistic modeling-principle of similarity for scaling up sustainable production lines

Pharmaceutical industry produces safe, effective, affordable, and quality medicines used to guarantee a healthy life and promote the well-being of the entire population in a sustainable way. Currently, the solid dosage form is the preferred formulation for human use. However, the large scale production of these medicines it requires well-tested formulation and appropriate equipment because any substantial variation in the development of the pharmaceutical product can alter the final quality of the product, causing the entire manufactured batch to be discarded. For this reason, this research aimed to analyze and understand the behavior of the variables involved in the wet granulation process while scaling from a laboratory system and a production line unit to transfer the results obtained to a large-scale production unit of solid dosage forms to meet the health needs of the world population. This study was carried out under a mixed approach applying quantitative and qualitative technologies to explain and predict the behavior of the involved variables while scaling from a laboratory system to a production line unit. It was found that there are some regularities and causal relationships between geometric, kinematic, and dynamic similarities.

Numerical study on heat and mass transfer characteristics in a randomly packed air cooling tower for large-scale air separation systems

To investigate the heat and mass transfer characteristics of the moist air–water counter-current flow in a randomly packed air cooling tower (RPACT) for large-scale air separation units, a 3-D Eulerian porous media computational fluid dynamics (CFD) model coupled with mass transfer equations was developed. A plastic Super ring (model 50-RLF1), with the highest porous resistance of the candidate materials, was selected as the optimal packing material for the RPACT. The effects of operating conditions and packing characteristics on the flow and coupled heat–mass transfer performance were analyzed, including pressure drop, liquid holdup, fluid temperature, wall film flow rate, humidity ratio, and the total heat transfer rate of the RPACT. Through model validation, it was found that the 3-D Eulerian porous media model built in this study can accurately predict the RPACT performance and is suitable for the configuration design and optimization. The investigation results show that both the F-factor and liquid load sensitively influence the performance, and there is an optimum range of operating conditions. The total heat transfer rate of the RPACT is 0.84% greater than the rated value designed by an industrial gas equipment producer, even with a packing depth reduced to 6 m from the designed value (8 m).

Biotechnological approaches to enhance biofuel producing potential of microalgae

Oleaginous microalgae have emerged as the promising feedstock for biofuels due to their various advantageous features over terrestrial plants. However, the microalgal fuel industry is still in its infancy due to the unavailability of robust algal strains with enhanced lipid content and biomass and economically feasible oil extraction strategies. Microalgal metabolic engineering shows the great potential to enhance lipid accumulation without impairing cell growth by targeted control of key metabolic nodes. Despite the recent advancements in synthetic biology, genetic improvement of microalgae without hindered cellular biomass remains an untapped tool for large-scale biofuel production. In this review, we therefore provide a comprehensive overview of various metabolic engineering strategies for lipid enhancement and the necessity of designing the appropriate strategy for scale-up processes. We have emphasized the need of streamlining the engineering strategies with the aid of recent advancements in DNA manipulation techniques to obviate the existing biological intricacies in lipogenesis. We outline the significance of recruiting potential engineering strategies such as transcription engineering, heterologous recombineering, and genome engineering to generate chassis algal strains successfully. Besides, this review highlights the designing of modular strategies by subjecting the engineered strains under sub-optimal conditions, mixotrophic cultivations and chemical treatment to overcome the existing bottlenecks in microalgal commercialization. This review also discusses the current large-scale algal cultivation units and the drawbacks. Overall, this review provides insights into employing the metabolic rewiring strategies to engineer the intricate lipogenic circuit in microalgae for enhancing biofuel potential.

Research of Turbine Oil Varnish in Generator Unit

In recent years, due to the fact that thermal power generating units have been deeply involved in the peak shaving work of the power grid, the frequent start and stop operations of the units and rapid load-carrying operations have made the operating conditions of the units very bad. In large-scale thermal power generation units, shutdown accidents caused by varnish failures are becoming more common. Take the serious varnish failure of Unit 3 in a domestic power plant as a case for analysis. The steam turbine oil after the varnish is formed is fully analyzed and tested and the metal ion content test is carried out. The changes in the physical indicators of the steam turbine oil during the formation of the varnish are studied to determine the influence of the steam turbine oil on the physical indicators of the steam turbine oil during the formation of the steam turbine oil. The operation and maintenance personnel can detect the varnish in advance through the daily sampling and analysis of the steam turbine oil, and timely take treatment measures to remove the varnish components in the oil to ensure the safe and stable operation of the unit. This article summarizes the reason for the formation of varnish and the detection method of varnish. It is of great significance to effectively discover and control the production of varnish during the operation of the generator set, to study the formation mechanism of varnish and to find an effective method to remove varnish. This article also introduces the commonly used paint film treatment methods for the convenience of electric power technicians.

In Situ Precipitated Calcium Carbonate in the Presence of Pulp Fibers – A Beating Study

The paper industry around the world is in search for new ways to decrease production costs. New approached with additives such as new developed In Situ precipitated paper fillers materials have the potential to reduce production cost and increase profit margins.
 In Situ precipitated calcium carbonate filler with 20.9% and 41.7% filler material was produced in a large-scale laboratory unit using a eucalyptus pulp fiber suspension with a 1.7% fiber solids content.
 Laboratory beating tests were performed with a Valley Beater and APFI Mill using pure eucalyptus pulp with no filler content as the based trial and the two-laboratory manufactured In Situ precipitated filler pulps.
 Valley Beater and PFI Mill laboratory beating machines show similar differences/trends for the breaking length, tear and burst index.
 EC-pulp with no filler has the highest strength for breaking length, tear and burst index. With increasing filler level breaking length, tear and burst index decrease. Filler containing pulp shows a decrease in beating time for the same beating level. 20 minutes for the Valley Beater and 15000 revolutions for the PFI mill show highest change in pulp fiber beating level sufficient for paper making operation.
 Valley Beater and PFI Mill laboratory equipment operate different and an exact comparison of the beating curves is not possible. Based on the amount of pulp fiber needed for experiments the Valley Beater for large amounts and the PFI mill for smaller amounts should be selected.
 The SEM pictographs of the Valley Beater and PFI Mill beating trials from 0 stage to the high beating stage at 80 minutes for the Valley beater and 60000 revolutions for the PFI Mill show similar results. No damage to the fibers is noticeable at the unbeaten level. With increasing beating level. At a magnification of 430 times the fiber structure shows an increasing dense fiber structure with less visible pores. Magnification of 2500 times reveals increasing damage to the fiber wall and fiber surface.

Reckoning with the barriers to Lean implementation in Northern Indian SMEs using the AHP-TOPSIS approach

PurposeThe purpose of this study is to recognize critical barriers for Lean manufacturing practices implementation in small and medium enterprises (SMEs) focusing in the context of a developing economy. The advancement of SMEs is of utmost important for a surge in exports while competing with other countries and these barriers have to be given due importance as they play a major role in stalling the overall development of SMEs.Design/methodology/approachIn this present investigation, 26 barriers to Lean implementation in SMEs have been identified after an extensive study of the literature available on the subject. After that, the influential barriers were investigated through the Analytical hierarchy process-Technique of order preference by similarity to ideal solution (AHP-TOPSIS) method using priority weightage given to them by different experts in their industries. The ranking given to the barriers is based on the AHP-TOPSIS method and has been validated by the sensitivity analysis.FindingsThe investigation reveals that for the successful implementation of Lean manufacturing practices, the will of the management, individual will power and contribution of the people matter a lot apart from other barriers such as flexibility, expertise of the people, resources and resistance offered by the people to new programs. The solutions for overcoming these barriers are also provided in this study and a model has been suggested for the same.Research limitations/implicationsThis work was devoted to the evaluation of obstacles in the introduction of Lean practices and prioritizing them. But it was limited to the medium- and small-scale organizations located in Northern India. Further studies can expand the scope to the large-scale units in the field. Moreover, the scope of this study was confined to the manufacturing sector. Future studies can extend it to the non-manufacturing environments such as the service sector, health care, etc. This investigation was based on the judgments of industry experts and academicians. Another approach such as Viekriterijumsko kompromisno rangiranje can be used for future investigations.Originality/valueThis study is significant when keeping in mind the contribution of SMEs to a country’s economy, especially in the Indian context.

Thermo-Economic Assessment and Multi-Objective Optimization of an Innovatively Designed District Cooling System in Saudi Arabia

Abstract The experience of leading countries in distributed energy systems (e.g., Scandinavian countries) shows that district cooling systems are highly beneficial techno-economic-environmentally by facilitating the use of waste heat resources, solar energy, etc. for cold supply at large scales. This study proposes the optimal development of a novel district cooling design equipped with a large-scale cold storage unit and utilizing the exhaust waste heat of an energy plant in a case study in Saudi Arabia. The optimal configuration of the hybrid system, the sizing of its components, and operating conditions are found using multi-objective optimization techniques based on the genetic algorithm method and a creative performance assessment index. Then, the feasibility of this optimized proposal is investigated through comprehensive thermodynamic and economic analyses. The results show that a district cooling system can surely cope with the harsh climate condition of the case study and provide the required interior comfort conditions. The energy and exergy efficiencies of the system can be as high as 62% and 53% using an absorption chiller utilizing a power plant’s waste heat along with a storage tank for peak shaving. The levelized cost of cooling of the system can be 28 USD/MW h, by which the payback period will be only 8 years.

Membrane Processes for Direct Carbon Dioxide Capture From Air: Possibilities and Limitations

The direct capture of CO2 from air (DAC) has been shown a growing interest for the mitigation of greenhouse gases but remains controversial among the engineering community. The high dilution level of CO2 in air (0.04%) indeed increases the energy requirement and cost of the process compared to carbon capture from flue gases (with CO2 concentrations around 15% for coal power plants). Until now, solid sorbents (functionalized silica, ion exchange resins, metal–organic frameworks, etc.) have been proposed to achieve DAC, with a few large-scale demonstration units. Gas-liquid absorption in alkaline solutions is also explored. Besides adsorption and absorption, membrane processes are another key gas separation technology but have not been investigated for DAC yet. The objective of this study is to explore the separation performances of a membrane unit for CO2 capture from air through a generic engineering approach. The role of membrane material performances and the impact of the operating conditions of the process on energy requirement and module production capacity are investigated. Membranes are shown to require a high selectivity in order to achieve purity in no more than two stages. The specific energy requirement is globally higher than that of the adsorption and absorption processes, together with higher productivity levels. Guidelines on the possibilities and limitations of membranes for DAC are finally proposed.

High-Pressure Processing for the Production of Added-Value Claw Meat from Edible Crab (Cancer pagurus).

High-pressure processing (HPP) in a large-scale industrial unit was explored as a means for producing added-value claw meat products from edible crab (Cancer pagurus). Quality attributes were comparatively evaluated on the meat extracted from pressurized (300 MPa/2 min, 300 MPa/4 min, 500 MPa/2 min) or cooked (92 °C/15 min) chelipeds (i.e., the limb bearing the claw), before and after a thermal in-pack pasteurization (F9010 = 10). Satisfactory meat detachment from the shell was achieved due to HPP-induced cold protein denaturation. Compared to cooked or cooked–pasteurized counterparts, pressurized claws showed significantly higher yield (p < 0.05), which was possibly related to higher intra-myofibrillar water as evidenced by relaxometry data, together with lower volatile nitrogen levels. The polyunsaturated fatty acids content was unaffected, whereas the inactivation of total viable psychrotrophic and mesophilic bacteria increased with treatment pressure and time (1.1–1.9 log10 CFU g−1). Notably, pressurization at 300 MPa for 4 min resulted in meat with no discolorations and, after pasteurization, with high color similarity (ΔE* = 1.2–1.9) to conventionally thermally processed samples. Following further investigations into eating quality and microbiological stability, these HPP conditions could be exploited for producing uncooked ready-to-heat or pasteurized ready-to-eat claw meat products from edible crab.

Numerical Simulation of the Thermo-catalytic Reforming Process: Up-scaling Study

The up-scaling of the pyrolysis technologies is the next step to achieve the industrial scale and to fulfill the energy and petrochemical demand in large-scale units. The overall goal of this study...

Performance of circular hollow concrete columns with a single layer of transverse reinforcement

Circular hollow concrete columns are preferably designed with a single layer of transverse reinforcement to withstand seismic loads considering both acceptable performance and ease of construction. However, both the confining effect and failure characteristics of hollow columns are different from the confining effect and failure of solid columns. To investigate the performance of circular hollow concrete columns with a single layer of transverse reinforcement, two large-scale column units were designed and tested. Their performance was evaluated in terms of displacement ductility, stiffness degradation, and energy dissipation. In addition, the confinement-induced strains in the transverse reinforcement within the plastic hinge regions were recorded to quantify the confining effect. To better simulate the responses of circular hollow concrete columns with a single layer of transverse reinforcement, a frequently used confined concrete model was improved, and its accuracy was validated by comparing the experimental and simulated responses at both global and local levels.

LINGUISTATICAL STUDY OF CHINESE INTERNET LEXICOLOGY

Different changes occur in each language under the influence of scientific and technical processes. Significant changes are observed in the lexical structure of the language: constant renewal and enrichment, the reflection of major changes in the life of society, the emergence of large-scale new language units. As a result of the emergence of a new object in human life, the problem of defining it in speech arises, translating it from one language to another in order to support and develop mutual cultural communication. With the advent of the Internet, there have been many changes in Chinese society, including the Chinese language. Under the influence of the Internet, an Internet language different from the literary normative language was formed.

Modeling and Investigation of Demand Response Uncertainty on Reliability Assessment

Demand Response (DR) provides an opportunity for customers to reduce their loads during times of high prices and therefore to shave the peak loads. The power outputs of large-scale generator units can be predicted and controlled easily; therefore, the pricing and reliability of conventional power utilities can be assessed straightforwardly. However, the customer loads are very variable and difficult to predict and control; therefore, the integration of DR might cause uncertainty issues on pricing and reliability and is essential to be further investigated. A novel uncertainty model for load reduction is proposed in this paper. The probability intensities of load reduction are first estimated from the measured load reduction variations. A multi-state probability model is then proposed for load reduction and the Markov process is used to calculate the state probabilities. A stochastic analysis scheme using Monte Carlo simulation for pricing and reliability taking the DR uncertainty into account is then investigated. Several cases are designed to compare the effects of DR uncertainty. Simulation results show that the proposed uncertainty model can be integrated into conventional economic dispatch to precisely evaluate the DR uncertainty on system operation and reliability.

The creation and application of a large-scale corpus-based academic multi-word unit list

This paper outlines a project involving the construction of a corpus-based list which provides a large-scale selection of multi-word units that occur in academic English. Using the most up-to-date, reliable methods, the goal was to produce a large-scale resource which could either be studied directly or used as a reference for practitioners to create further resources. The paper details the procedures used to generate this academic multi-word unit list, explains why specific decisions were made to identify useful items, and discusses the resulting resource. Comparisons will be made between the list created and currently existing lists, and also between the characteristics of the list created versus characteristics of high-frequency general English word lists. Finally, applications of this free resource for English practitioners and students will be suggested.

Frequency Response From Solar PV: A Dynamic Equivalence Closed-Loop System Identification Approach

The analysis of the frequency response of integrated transmission-distribution networks with deep penetration of solar photovoltaic (PV) generation faces major challenges due to the complexity emerging from the dynamic models of the numerous and diverse PV units involved. This article proposes converter-based dynamic equivalent models for both distributed (distribution network-connected) and large-scale (transmission network-connected) PV units, which take into account practical issues, such as measurement and coordination delays. Different from the previous work that adopted an open-loop identification, the unknown model parameters are identified here through a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">closed-loop</i> identification process based on the least-square minimization. This allows capturing the continuous interaction between system and PV responses, thus improving the outcome of the overall frequency response model. The proposed models are validated with the real data from the August 2018 separation event in Australia. The results demonstrate the excellent performance of the proposed models in determining the frequency response from PV in both transmission and distribution networks, hence paving the way to its adoption in the frequency stability analysis in low-carbon grids dominated by frequency-responsive renewables.

Modeling technology of large-scale half speed unit and its thermal actuator participating in grid frequency modulation

In view of the shortage of the technology of large half speed units in nuclear power participating in the primary frequency regulation modeling and parameter measurement of power grid, the speed regulation system, thermal actuator and prime mover model of nuclear power unit are established. At the same time, the technology of model parameter test, identification and verification is developed. The developed technology meets the requirements of BPA. Through the frequency step simulation of the established model and the obtained model parameters, and compared with the field test results, the results show that the model and its parameter test method are correct. The established model and its parameters can accurately reflect the dynamic process of nuclear motor group participating in the primary frequency modulation of large power grid.

Solving the Real Power Limitations in the Dynamic Economic Dispatch of Large-Scale Thermal Power Units under the Effects of Valve-Point Loading and Ramp-Rate Limitations

Few non-traditional optimization techniques are applied to the dynamic economic dispatch (DED) of large-scale thermal power units (TPUs), e.g., 1000 TPUs, that consider the effects of valve-point loading with ramp-rate limitations. This is a complicated multiple mode problem. In this investigation, a novel optimization technique, namely, a multi-gradient particle swarm optimization (MG-PSO) algorithm with two stages for exploring and exploiting the search space area, is employed as an optimization tool. The M particles (explorers) in the first stage are used to explore new neighborhoods, whereas the M particles (exploiters) in the second stage are used to exploit the best neighborhood. The M particles’ negative gradient variation in both stages causes the equilibrium between the global and local search space capabilities. This algorithm’s authentication is demonstrated on five medium-scale to very large-scale power systems. The MG-PSO algorithm effectively reduces the difficulty of handling the large-scale DED problem, and simulation results confirm this algorithm’s suitability for such a complicated multi-objective problem at varying fitness performance measures and consistency. This algorithm is also applied to estimate the required generation in 24 h to meet load demand changes. This investigation provides useful technical references for economic dispatch operators to update their power system programs in order to achieve economic benefits.

Photosynthetic performance of Chlorella vulgaris R117 mass culture is moderated by diurnal oxygen gradients in an outdoor thin layer cascade

Dissolved oxygen concentration is a critical point for microalgae in large scale cultivation systems. Highly productive cultures inevitably generate a build-up of oxygen gradients along the reactor which can affect photosynthetic performance. In this study, a fast-growing strain of Chlorella vulgaris R117 was cultured outdoors in a thin-layer cascade during a one-week trial reaching a biomass productivity of 4 g DW L−1 d−1 (27 g DW m−2 d−1). High photosynthetic activity led to oxygen oversaturation of up to 400% in some parts along the culture units at midday. The aim was to examine the effect of high dissolved oxygen concentration on diurnal changes in the photosynthetic performance and growth of the Chlorella culture using multi-technique approach. Photosynthetic activity of Chlorella R117 culture was estimated in situ and ex situ using oxygen production and in vivo Chl a fluorescence measurements, which showed good correlation. The rates of electron transport and of oxygen production were related, but the values of the μmolelectrons/μmolO2 ratio was higher than predicted, suggesting the probable involvement of electron and oxygen consuming processes such as photorespiration and Mehler reaction. These processes probably function as photoprotective mechanisms, since no photodamage was observed in the Chlorella R-117 cultures. Depression (down-regulation) of photosynthetic activity due to the exposition to high dissolved oxygen concentration along the cascade area over time was observed. The usefulness of on-line measurements was demonstrated to obtain immediate and in-situ information on the physiological status of the culture. This data can be used in models of operation control for large-scale microalgae production units.

Make Hydrogen Whilst the Sun Shines: How to Turn the Current Momentum into a Well-Functioning Hydrogen Market?

The energy transition calls for greater interdependency between different energy infrastructures and energy carriers to ensure an effective integration of renewable energy into the energy system. The energy sector’s legislative framework and legal safeguards, however, are still largely based on the traditional market model, designed for centrally managed, fossil fuel-based, and large-scale production units for the supply of energy. Regulation is also fundamentally based on the idea that energy markets are separate. The role of hydrogen as a flexible energy vector – allowing for interaction between different energy markets – is not yet accounted for. Regulation and integration of newer energy carriers into the energy system, like the hydrogen market, is a challenge. This is all the more so in light of the uncertainties on how the hydrogen market will develop. This contribution assesses how good regulation of the hydrogen market can be attained. For this assessment, the principles of good regulation provide a foundation for developing a normative framework to identify ‘good regulation’ and good regulatory strategies. It is suggested that considering uncertain market developments, the use of a regulatory sandbox can offer a practical solution to assess what good regulation for the hydrogen market could entail.

Mapping diurnal cycles of precipitation over China through clustering

The diurnal cycle of precipitation is a fundamental mode of climatic variability. Based on an hourly 0.1° × 0.1° gauge-satellite merged precipitation dataset, which is provided by the China Meteorological Data Service Center, this study used the K-means clustering algorithm to map the diurnal cycles of precipitation in summer over China. The obtained maps can objectively delineate irregular regions with similar patterns of diurnal cycles, and many of these regions resemble large-scale geomorphic units such as the North China Plain and the valley of the Yarlung Zangbo River, which verifies the importance of macroterrain for diurnal cycles of precipitation. In addition to total precipitation, precipitation events with different durations, which are often related to different types of precipitation (e.g., convective precipitation and stratiform precipitation), were analyzed separately. Compared with the previous studies using predefined region boundaries, the main advantage of this study is that the obtained maps can show more spatial details, through which we can get intuitive and in-depth understandings of the regional characteristics and spatial patterns of the diurnal cycles of precipitation over China.