scholarly journals Reactor Selection for Upgrading Hemicelluloses: Conventional and Miniaturised Reactors for Hydrogenations

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1558
Author(s):  
Stefan Haase ◽  
Cesar A. de Araujo Filho ◽  
Johan Wärnå ◽  
Dmitry Yu. Murzin ◽  
Tapio Salmi
Keyword(s):  
Selection Strategy ◽  
Special Focus ◽  
Reactor Performance ◽  
Liquid Distribution ◽  
Knowledge Based ◽  
Process Simulations ◽  
Aspen Custom Modeler ◽  
Space Time Yield ◽  
Parallel Reactions ◽  
Reactor Models

This work presents an advanced reactor selection strategy that combines elements of a knowledge-based expert system to reduce the number of feasible reactor configurations with elaborated and automatised process simulations to identify reactor performance parameters. Special focus was given to identify optimal catalyst loadings and favourable conditions for each configuration to enable a fair comparison. The workflow was exemplarily illustrated for the Ru/C-catalysed hydrogenation of arabinose and galactose to the corresponding sugar alcohols. The simulations were performed by using pseudo-2D reactor models implemented in Aspen Custom Modeler® and automatised by using the MS-Excel interface and VBA. The minichannel packings, namely wall-coated minichannel reactor (MCWR), minichannel reactor packed with catalytic particles (MCPR), and minichannel reactor packed with a catalytic open-celled foam (MCFR), outperform the conventional and miniaturised trickle-bed reactors (TBR and MTBR) in terms of space-time yield and catalyst use. However, longer reactor lengths are required to achieve 99% conversion of the sugars in MCWR and MCPR. Considering further technical challenges such as liquid distribution, packing the reactor, as well as the robustness and manufacture of catalysts in a biorefinery environment, miniaturised trickle beds are the most favourable design for a production scenario of galactitol. However, the minichannel configurations will be more advantageous for reaction systems involving consecutive and parallel reactions and highly exothermic systems.

scholarly journals Biofilm carrier migration model describes reactor performance

2017 ◽  
Vol 75 (12) ◽  
pp. 2818-2828 ◽  
Author(s):  
Joshua P. Boltz ◽  
Bruce R. Johnson ◽  
Imre Takács ◽  
Glen T. Daigger ◽  
Eberhard Morgenroth ◽  
...  
Keyword(s):  
Plug Flow ◽  
Biofilm Reactor ◽  
Bulk Liquid ◽  
Reactor Performance ◽  
Reactor Model ◽  
Operational Conditions ◽  
Limit Model ◽  
Biofilm Model ◽  
Reactor Models ◽  
The Impact

The accuracy of a biofilm reactor model depends on the extent to which physical system conditions (particularly bulk-liquid hydrodynamics and their influence on biofilm dynamics) deviate from the ideal conditions upon which the model is based. It follows that an improved capacity to model a biofilm reactor does not necessarily rely on an improved biofilm model, but does rely on an improved mathematical description of the biofilm reactor and its components. Existing biofilm reactor models typically include a one-dimensional biofilm model, a process (biokinetic and stoichiometric) model, and a continuous flow stirred tank reactor (CFSTR) mass balance that [when organizing CFSTRs in series] creates a pseudo two-dimensional (2-D) model of bulk-liquid hydrodynamics approaching plug flow. In such a biofilm reactor model, the user-defined biofilm area is specified for each CFSTR; thereby, Xcarrier does not exit the boundaries of the CFSTR to which they are assigned or exchange boundaries with other CFSTRs in the series. The error introduced by this pseudo 2-D biofilm reactor modeling approach may adversely affect model results and limit model-user capacity to accurately calibrate a model. This paper presents a new sub-model that describes the migration of Xcarrier and associated biofilms, and evaluates the impact that Xcarrier migration and axial dispersion has on simulated system performance. Relevance of the new biofilm reactor model to engineering situations is discussed by applying it to known biofilm reactor types and operational conditions.

scholarly journals Comparison of Photocatalytic Membrane Reactor Types for the Degradation of an Organic Molecule by TiO2-Coated PES Membrane

Catalysts ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 725 ◽  
Author(s):  
Chhabilal Regmi ◽  
Shabnam Lotfi ◽  
Jonathan Cawettiere Espíndola ◽  
Kristina Fischer ◽  
Agnes Schulze ◽  
...  
Keyword(s):  
Specific Energy Consumption ◽  
Space Time ◽  
Pollutant Removal ◽  
Design Flow ◽  
Membrane Reactors ◽  
Process Efficiency ◽  
Efficient Design ◽  
Reactor Performance ◽  
Flow Through ◽  
Space Time Yield

Photocatalytic membrane reactors with different configurations (design, flow modes and light sources) have been widely applied for pollutant removal. A thorough understanding of the contribution of reactor design to performance is required to be able to compare photocatalytic materials. Reactors with different flow designs are implemented for process efficiency comparisons. Several figures-of-merit, namely adapted space-time yield (STY) and photocatalytic space-time yield (PSTY), specific energy consumption (SEC) and degradation rate constants, were used to assess the performance of batch, flow-along and flow-through reactors. A fair comparison of reactor performance, considering throughput together with energy efficiency and photocatalytic activity, was only possible with the modified PSTY. When comparing the three reactors at the example of methylene blue (MB) degradation under LED irradiation, flow-through proved to be the most efficient design. PSTY1/PSTY2 values were approximately 10 times higher than both the batch and flow-along processes. The highest activity of such a reactor is attributed to its unique flow design which allowed the reaction to take place not only on the outer surface of the membrane but also within its pores. The enhancement of the mass transfer when flowing in a narrow space (220 nm in flow-through) contributes to an additional MB removal.

Modeling Information Search Behavior for Design Purposes: An Example from Process Control

1988 ◽  
Vol 32 (19) ◽  
pp. 1376-1380 ◽  
Author(s):  
Gunilla A. Sundström
Keyword(s):  
Control Systems ◽  
Supervisory Control ◽  
Information Search ◽  
Search Behavior ◽  
Special Focus ◽  
Knowledge Based ◽  
Human Machine Interfaces ◽  
Information Search Behavior ◽  
Graphical Design ◽  
Operator Behavior

Current models on operator behavior in supervisory control systems are reviewed with special focus on their usefulness for graphical design of human-machine interfaces in dynamic technical systems. An alternative framework is described and used in a knowledge based approach to represent information search behavior of operators for graphical design purposes.

scholarly journals A Bibliometric Analysis of Research on Membrane Coated Electrodes in the 2001-2019 Period: Potential Application to CO2 Capture and Utilization

2020 ◽  
Author(s):  
Clara Casado-Coterillo ◽  
Aitor Marcos-Madrazo ◽  
Aurora Garea ◽  
Angel Irabien
Keyword(s):  
Carbon Dioxide ◽  
21St Century ◽  
Chemical Engineering ◽  
Environmental Science ◽  
Electrochemical Reactor ◽  
Past Century ◽  
Special Focus ◽  
Reactor Performance ◽  
Co2 Electroreduction ◽  
Coated Electrodes

The chemistry and electrochemistry basic fields have been active since the last two decades of the past century studying how surface modification of electrodes by coating with conductive films enhances their activity and performance. In the light of the development of alternative sustainable ways of energy storage and carbon dioxide conversion by electrochemical processes, these research studies have jumped in the 21st century to more applied fields such as chemical engineering, energy and environmental science and engineering. The huge amount of literature on experimental works dealing with the development of CO2 electroreduction processes addresses electrocatalyst development. Membranes can help understanding and controlling the mass transport limitations of current electrodes and reactors designs. The present bibliometric review addresses the papers published in the 21st century regarding membrane coated electrodes and electrocatalysts to enhance electrochemical reactor performance and viability with a special focus on the urgent issue of carbon dioxide capture and utilization.

Improved Leak Detection by Method Diversity

1998 ◽  
Author(s):  
Ruprecht M. J. Pichler
Keyword(s):  
Transient Flow ◽  
Detection System ◽  
Type System ◽  
Leak Detection ◽  
Operating Conditions ◽  
Detection Methods ◽  
Special Focus ◽  
Oil Pipeline ◽  
Knowledge Based ◽  
Noise Factors

Leak detection systems for liquid pipelines are installed to minimize spillage in case of a leak. Therefore reliability, sensitivity and detection time under practical operating conditions are the most important parameters of a leak detection system. Noise factors to be considered among others are unknown fluid property data, friction factor, instrument errors, transient flow, slack-line operation and SCADA update time. The opening characteristics and the size of leaks differ considerably from case to case. Each software-based leak detection method available today has its particular strength. As long as just one or two of these methods are applied to a pipeline a compromise has to be found for the key parameters of the leak detection system. The paper proposed illustrates how a combination of several different software-based leak detection methods together with observer-type system identification and a knowledge-based evaluation can improve leak detection. Special focus is given to leak detection and automated leak locating under transient flow conditions. Practical results are shown for a crude oil pipeline and a product pipeline.

Knowledge Based Qualification Methodology to Evaluate Shock Induced Risks in BGA Components

2017 ◽  
Author(s):  
Min Pei ◽  
Guru Arakere ◽  
Milena Vujosevic
Keyword(s):  
User Behavior ◽  
System Level ◽  
Special Focus ◽  
Detailed Knowledge ◽  
End User ◽  
Physics Of Failure ◽  
Knowledge Based ◽  
Test Board ◽  
Deformation Modes

This paper provides details of Knowledge Based Qualification (KBQ) methodology to calculate BGA component shock qualification requirements. The methodology is based on experimental, theoretical and computational approach used to generate a detailed knowledge of the use conditions and failure physics. Discussed are the steps taken to understand the end-user behavior and system design impact on dynamic load experienced by the component in the field. A special focus is placed on the understanding of the board deformation modes, their impact on BGA failures, and the physics-of-failure (PoF) metric that is not only accurate enough but also practical for everyday applications. Theoretical and computational modeling was used to perform the necessary “translations” from use condition to test conditions and from system level drop to test board component shock. These “translations” enabled by the PoF metric, directly lead to the determination of BGA shock qualification requirements.

scholarly journals Academic entrepreneurship as a factor of knowledge spillovers in the regions – the case of Malopolska region

2012 ◽  
Vol 20 ◽  
pp. 182-195
Author(s):  
Magdalena Godowska
Keyword(s):  
Academic Entrepreneurship ◽  
Knowledge Spillovers ◽  
New Ventures ◽  
Knowledge Spillover ◽  
Theoretical Concept ◽  
Special Focus ◽  
Knowledge Based ◽  
Knowledge Based Economy ◽  
Spillover Theory ◽  
Knowledge Spillover Theory

With the transition towards a knowledge-based economy, entrepreneurship has become a focus of public policy, especially on the regional level, as one of the most significant factors of economic growth. The knowledge spillover theory of entrepreneurship is based on the assumption that entrepreneurs act as a missing link in the knowledge-based economy, by converting incompletely commercialized knowledge into economically significant one.  They do so by founding new ventures – start-ups – in order to exploit knowledge created in larger companies, which are unwilling to commercialize new ideas due to a high level of uncertainty. In this sense, starting up a new company acts as a conduit for the spillover of knowledge.The aim of the paper is to explain the foundations of the knowledge spillover theory of entrepreneurship. In the second part of the paper, the analysis of the Małopolska region in the light of the knowledge spillover theory of entrepreneurship is carried out. The special focus is on academic entrepreneurship in the region, since the theoretical concept of knowledge spillover theory of entrepreneurship may well serve as a framework to analyze knowledge-based ventures.

Building CLIA for Resource-Scarce African Languages

2015 ◽  
Vol 5 (1) ◽  
pp. 48-67
Author(s):  
Kula Kekeba Tune ◽  
Vasudeva Varma
Keyword(s):  
Retrieval System ◽  
Information Access ◽  
Special Focus ◽  
Query Translation ◽  
African Languages ◽  
Linguistic Resources ◽  
Knowledge Based ◽  
Overall Performance ◽  
Cross Language ◽  
Asian Languages

Since most of the existing major search engines and commercial Information Retrieval (IR) systems are primarily designed for well-resourced European and Asian languages, they have paid little attention to the development of Cross-Language Information Access (CLIA) technologies for resource-scarce African languages. This paper presents the authors' experience in building CLIA for indigenous African languages, with a special focus on the development and evaluation of Oromo-English-CLIR. The authors have adopted a knowledge-based query translation approach to design and implement their initial Oromo-English CLIR (OMEN-CLIR). Apart from designing and building the first OMEN-CLIR from scratch, another major contribution of this study is assessing the performance of the proposed retrieval system at one of the well-recognized international Cross-Language Evaluation Forums like the CLEF campaign. The overall performance of OMEN-CLIR was found to be very promising and encouraging, given the limited amount of linguistic resources available for severely under-resourced African languages like Afaan Oromo.

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