Scale-Up of Internal Mixers

1984 ◽  
Vol 57 (1) ◽  
pp. 48-54 ◽  
Author(s):  
I. Manas-Zloczower ◽  
Z. Tadmor
Keyword(s):  
Shear Strain ◽  
Scale Up ◽  
Operating Conditions ◽  
Dimensionless Number ◽  
Operational Parameters ◽  
Acceptable Error ◽  
Work Input ◽  
Unit Work ◽  
New Criterion ◽  
Total Shear

Abstract In this paper, a new criterion for scaling Banbury type internal mixers is proposed. The new criterion is a dimensionless number Xt*, representing the product of the fraction of broken agglomerates during one pass through the high shear zone of the internal mixer and the average number of passes through this zone, for a given mixing time. It can be calculated for a given system of polymer-additive from a knowledge of machine geometry and operating conditions. The dimensionless number Xt* is uniquely related to the fraction of undispersed agglomerates, ψ, which is a frequently encountered mixing quality criterion. Experimental results reported in literature, for a broad range of mixer sizes, fit, within practical acceptable error, the theoretical curve ψ versus Xt*, lending support to its validity. Moreover, the dimensionless number Xt* correlates almost linearly with the presently used scaling-up criteria, the unit work input and the total shear strain, which in turn proved to be interrelated to other properties of the compound, such as Mooney viscosity and die-swell. However, while the unit work input and the total shear strain can be used in scaling only as long as proper operating conditions are met, the dimensionless number Xt* provides a reliable scale-up criterion for a broad range of mixer sizes and geometries as well as different operational parameters. Derived from a theoretical model of dispersive mixing in internal mixers based exclusively on fundamental considerations, this new criterion can be used also for mixing cycle optimization and basic machine design.

Practical Parameters for Mixing

1975 ◽  
Vol 48 (4) ◽  
pp. 577-591 ◽  
Author(s):  
P. R. Van Buskirk ◽  
S. B. Turetzky ◽  
P. F. Gunberg
Keyword(s):  
Shear Strain ◽  
Large Scale ◽  
Rate Of Change ◽  
Dimensionless Number ◽  
Die Swell ◽  
High Shear ◽  
Actual Measurement ◽  
Unit Work ◽  
Mooney Viscosity ◽  
Total Shear

Abstract (1) Compounds mixed under high-shear conditions in a laboratory Brabender Plastograph or in larger Banbury mixers can be quantitatively compared on the basis of work input per unit volume. This quantity, unit work Wu, is proposed as a useful parameter for characterizing the effects of polymer, filler, and other ingredient on mixing performance. (2) This work supports the principle that, independent of the size and speed of a mixer, there is a unique relationship between unit work and such in-process properties of the compound as Mooney viscosity, die swell, etc. It has been shown that this relationship extends to other high-shear mixers, such as the Shaw Intermix and a cam-head type Brabender Plasticorder. (3) Practical unit work ranges for passenger tire-tread mixing found typical of factory operations are: first stage, 300–800 MJ/m3; second stage, 150–400 MJ/m3; final mix, 2000–4500 MJ/m3. Mixing to these unit-work levels in the laboratory achieved mixing quality that closely duplicated large-scale high-shear mixing. (4) Process profiles (the changes of certain in-process properties such as Mooney viscosity and die swell as functions of unit work) yield additional behavior indices that are characteristic of each individual rubber—filler mixture: The viscosity-work index (VWI), for instance, reflects the rate of change in the compound viscosity with increasing unit work, while the position of the maximum in the die swell vs. unit work curve is a good indicator of the minimum unit work required to obtain low levels of undispersed carbon black. (5) A second scaling parameter, based on an expanded concept of the total shear-strain performance for Banbury-type mixers, is proposed. It offers an alternative approach to scaled mixing when the actual measurement of unit work is not convenient. The total shear-strain parameter, as derived, is a dimensionless number Γ defined as Γ = [(shear rate) (time) (volumetric throughput ratio) (land-length ratio)]. Its use implies ideal viscous flow during mixing plus an accurate knowledge of mixer rotor and chamber dimensions.

Numerical Modeling and Experimental Studies of the Operational Parameters of the Earth-To-Air Heat Exchanger of the Geothermal Ventilation System

2021 ◽  
Vol 23 ◽  
pp. 42-64
Author(s):  
Boris Basok ◽  
Ihor Bozhko ◽  
Maryna Novitska ◽  
Aleksandr Nedbailo ◽  
Myroslav Tkachenko
Keyword(s):  
Heat Exchanger ◽  
Heat Exchangers ◽  
Ventilation System ◽  
Experimental Studies ◽  
Operating Conditions ◽  
Operational Parameters ◽  
Cross Sectional ◽  
Distinctive Features ◽  
Sectional Shape ◽  
Experimental Bench

This article is devoted to the analysis of the heat engineering characteristics of the operation of an Earth-to-Air Heat Exchanger, EAHE, with a circular cross-sectional shape, which is a component of the geothermal ventilation system. The authors analyzed literature sources devoted to the research of heat exchangers of the soil-air type of various designs and for working conditions in various soils. Much attention is paid to the issues of modeling the operation of such heat exchangers and the distinctive features of each of these models. Also important are the results of experimental studies carried out on our own experimental bench and with the help of which the numerical model was validated. The results of these studies are the basis for the development of a method for determining the optimal diameter of an EAHE under operating conditions for soil in Kyiv, Ukraine.

Morphological Adaptation for Speed Control of Pipeline Inspection Gauges MC-PIG

2021 ◽  
Author(s):  
Sujet Phodapol ◽  
Tachadol Suthisomboon ◽  
Pong Kosanunt ◽  
Ravipas Vongasemjit ◽  
Petch Janbanjong ◽  
...  
Keyword(s):  
Fluid Velocity ◽  
Operating Conditions ◽  
Pi Control ◽  
Operating Pressure ◽  
Acceptable Error ◽  
Valve Unit ◽  
Pipeline Inspection ◽  
Flow Adjustment ◽  
Valve Angle ◽  
Moving Speed

Abstract Passive and active hybrid pipeline inspection gauges (PIGs) have been used for in-pipe inspection. While a passive PIG cannot control its speed, the hybrid version can achieve this by using an integrated valve specifically designed and embedded in the PIG. This study proposes a generic new method for speed adaptation in PIGs (called MC-PIG) by introducing a generic, modular, controllable, external valve unit add-on for attaching to existing conventional (passive) PIGs with minimal change. The MC-PIG method is based on the principle of morphological computation with closed-loop control. It is achieved by regulating/computing the PIG's morphology (i.e., a modular rotary valve unit add-on) to control bypass flow. Adjustment of the valve angle can affect the flow rate passing through the PIG, resulting in speed regulation ability. We use numerical simulation with computational fluid dynamics (CFD) to investigate and analyze the speed of a simulated PIG with the valve unit adjusted by proportional-integral (PI) control under various in-pipe pressure conditions. Our simulation experiments are performed under different operating conditions in three pipe sizes (16″, 18″, and 22″ in diameter) to manifest the speed adaptation of the PIG with the modular valve unit add-on and PI control. Our results show that the PIG can effectively perform real-time adaptation (i.e., adjusting its valve angle) to maintain the desired speed. The valve design can be adjusted from 5 degrees (closed valve, resulting in high moving speed) to a maximum of 45 degrees (fully open valve, resulting in low moving speed). The speed of the PIG can be regulated from 0.59 m/s to 3.88 m/s in a 16″ pipe at 4.38 m/s (in-pipe fluid velocity), 2500 kPa (operating pressure), and 62 °C (operating temperature). Finally, the MC-PIG method is validated using a 3D-printed prototype in a 6″ pipe. Through the investigation, we observed that two factors influence speed adaptation; the pressure drop coefficient and friction of the PIG and pipeline. In conclusion, the results from the simulation and prototype show close characteristics with an acceptable error.

Sootblowing Optimization Improves Heat Rate and Enhances Operational Flexibility at Hawthorn Unit 5

2014 ◽  
Author(s):  
Neel J. Parikh ◽  
Peter Rogge ◽  
Kenneth Luebbert
Keyword(s):  
Control System ◽  
Closed Loop ◽  
Heat Rate ◽  
Operating Conditions ◽  
Operational Experience ◽  
Unit Operation ◽  
Gas Temperature ◽  
Dynamic Adjustment ◽  
Operational Parameters ◽  
Unit Load

Coal-fired units are increasingly expected to operate at varying loads while simultaneously dealing with various operational influences as well as fuel variations. Maintaining unit load availability while managing adverse effects of various operational issues such as, flue gas temperature excursions at the SCR inlet, high steam temperatures and the like presents significant challenges. Dynamic adjustment of sootblowing activities and different operational parameters is required to effectively control slagging, fouling and achieve reliability in unit operation. Closed-loop optimizers aim to reduce ongoing manual adjustments by control operators and provide consistency in unit operation. Such optimizers are typically computer software-based and work by interfacing an algorithmic and/or artificial intelligence based decision making system to plant control system [1]. KCP&L is in the process of implementing Siemens SPPA-P3000 combustion and sootblowing optimizers at several Units. The Sootblowing Optimizer solution determines the need for sootblowing based on dynamic plant operating conditions, equipment availability and plant operational drivers. The system then generates sootblower activation signals for propagation in a closed-loop manner to the existing sootblower control system at ‘optimal’ times. SPPA-P3000 Sootblowing Optimizer has been successfully installed at Hawthorn Unit 5, a 594-MW, wall-fired boiler, firing 100 percent Powder River Basin coal. This paper discusses implementation approach as well as operational experience with the Sootblowing Optimizer and presents longer-term operational trends showing unit load sustainability and heat rate improvement.

Studying Systems of Stabilization of Supports in Hydrostatic Machine Tool

2012 ◽  
Vol 622-623 ◽  
pp. 489-493
Author(s):  
Iskander Beisembetov ◽  
Sabyi Ussupov ◽  
Bakhyt Absadykov ◽  
Beken Arymbekov ◽  
Birzhan Bektibay
Keyword(s):  
Film Thickness ◽  
Machine Tools ◽  
Operating Conditions ◽  
Coefficient Of Performance ◽  
Operational Parameters ◽  
Automatic Stabilization ◽  
Design Elements ◽  
Oil Film ◽  
Hydrostatic Bearing ◽  
Automatic Control Systems

Development relevance to improve the operational parameters of the support units of machine tools in their design elements is introduced that increase the rigidity of the components, their carrying capacity, damp occurring vibrations in the process, the coefficient of performance (COP), smoothness of motion, positioning accuracy, reducing the wear of their working surfaces and maintain the original accuracy. A number of engineering development [1], [2], aimed at improving the above characteristics of the machine by changing and improving design of reference nodes used in these rails rolling bearings, aerostatic and hydrostatic guides, as well as the use of automatic control systems of its basic parameters, determine its quality. However, in some operating conditions in which errors occur, mainly due to the instability of oil-film thickness (gap) between the mobile and immobile elements of the hydrostatic bearing. For high accuracy requirements it will negatively affect the quality of machined parts and equipment performance. On this basis, it becomes apparent urgency of the problem of automatic stabilization of oil-film thickness (gap) in the IR. To ensure high precision equipment to improve power system hydrostatic bearing units of machine tools. This, in turn, creates the prerequisite for the development of stabilization systems of the gap in the hydrostatic bearing, with the help of which the thickness of oil layer in them would be kept constant even with significant dynamic load on the support.

Influence of the Pressure Load in the Efficiency of a Longitudinal Ventilation System in Road Tunnels

2009 ◽  
Author(s):  
Mo´nica Galdo-Vega ◽  
Carlos Santolaria-Morros ◽  
Jesu´s Manuel Ferna´ndez Oro ◽  
Katia Maria Argu¨elles-Di´az
Keyword(s):  
Momentum Transfer ◽  
Ventilation System ◽  
Operating Conditions ◽  
Traffic Density ◽  
Moderate Pressure ◽  
Pressure Gradients ◽  
Operational Parameters ◽  
Satisfactory Description ◽  
Longitudinal Ventilation ◽  
Road Tunnels

The longitudinal ventilation system (LVS) efficiency in road tunnels is conditioned by geometric and operational parameters. Typical geometric parameters are the length of the tunnel, its slope and the transversal section. All these factors are generally fixed and thus not modifiable in the regular operation of the facility. On the other hand, operational parameters, like the working fans layout, the environmental conditions or the traffic density are case-sensitive and susceptible to influence the baseline performance of the ventilation system. In the present study, different pressure gradients, established between inlet and outlet location of the jet fan influence, are analyzed. This static resistance is shown to have a significant impact on the momentum transfer established between the jet expansion and the bulk flow inside the tunnel. For moderate pressure gradients, the jet discharged from fan is relativity well-mixed, allowing to reach uniform flow conditions in the streamwise direction. When the adverse pressure gradients become severe, the high-velocity flow is blocked, unable to mix out in the inter fan spacing and losing spanwise uniformity. At critical conditions, large recirculation areas can be developed within primary flow structures, generating turbulence and important energy losses, and even inducing reverse flow at the tunnel exit. The extreme operating conditions of a longitudinal ventilation system in a road tunnel have been studied using a 3D numerical simulation. Preliminary analysis for grid sensitivity and election of an accurate turbulence closure were performed to guarantee a valuable modeling. Following, systematic computations over a cluster of PC’s were executed using the well-tested Fluent code. RANS modeling with RSM scheme allowed a satisfactory description of three-dimensional vortical structure in the recirculation zones, especially for adverse pressure gradients. At this point, numerical results have provided a comprehensive overview of the mechanism associated to the momentum transfer of the jet expansion, comparing the performance for zero-pressure gradients with those observed for adverse conditions. Also, this paper gives valuable information about practical limits of the LVS, advancing operational conditions that compromise the ventilation efficiency.

Data Analytics into Hydraulic Modelling for Better Understanding of Well/Surface Network Limits, Proactively Identify Challenges and, Provide Solutions for Improved System Performance in the Greater Burgan Field

2021 ◽  
Author(s):  
Qasem Dashti ◽  
Saad Matar ◽  
Hanan Abdulrazzaq ◽  
Nouf Al-Shammari ◽  
Francy Franco ◽  
...  
Keyword(s):  
Production Management ◽  
Planning Process ◽  
System Optimization ◽  
Development Planning ◽  
Operating Conditions ◽  
Flow Assurance ◽  
Operational Parameters ◽  
Field Development ◽  
Hydraulic Models ◽  
Surface Network

Abstract A network modeling campaign for 15 surface gathering centers involving more than 1800 completion strings has helped to lay out different risks on the existing surface pipeline network facility and improved the screening of different business and action plans for the South East Kuwait (SEK) asset of Kuwait Oil Company. Well and network hydraulic models were created and calibrated to support engineers from field development, planning, and operations teams in evaluating the hydraulics of the production system for the identification of flow assurance problems and system optimization opportunities. Steady-state hydraulic models allowed the analysis of the integrated wells and surface network under multiple operational scenarios, providing an important input to improve the planning and decision-making process. The focus of this study was not only in obtaining an accurate representation of the physical dimension of well and surface network elements, but also in creating a tool that includes standard analytical workflows able to evaluate wells and surface network behavior, thus useful to provide insightful predictive capability and answering the business needs on maintaining oil production and controlling unwanted fluids such as water and gas. For this reason, the model needs to be flexible enough in covering different network operating conditions. With the hydraulic models, the evaluation and diagnosis of the asset for operational problems at well and network level will be faster and more effective, providing reliable solutions in the short- and long-terms. The hydraulic models enable engineers to investigate multiple scenarios to identify constraints and improve the operations performance and the planning process in SEK, with a focus on optimal operational parameters to establish effective wells drawdown, evaluation of artificial lifting requirements, optimal well segregation on gathering centers headers, identification of flow assurance problems and supporting production forecasts to ensure effective production management.

Influence of Operational Parameters on Photocatalytic Degradation of Linuron in Aqueous TiO2 Pillared Montmorillonite Suspension

2021 ◽  
Vol 16 (3) ◽  
pp. 673-685
Author(s):  
D. Hadj Bachir ◽  
Hocine Boutoumi ◽  
H. Khalaf ◽  
Pierre Eloy ◽  
J. Schnee ◽  
...  
Keyword(s):  
Photocatalytic Degradation ◽  
Physicochemical Characterization ◽  
Operating Conditions ◽  
Cod Removal ◽  
Pollutant Concentration ◽  
Catalyst Loading ◽  
Operational Parameters ◽  
X Ray ◽  
Pillared Montmorillonite ◽  
Initial Ph

TiO2 pillared clay was prepared by intercalation of titan polyoxocation into interlamelar space of an Algerian montmorillonite and used for the photocatalytic degradation of the linuron herbicide as a target pollutant in aqueous solution. The TiO2 pillared montmorillonite (Mont-TiO2) was characterized by X-ray photoelectron spectroscopy (XPS), X-Ray diffraction (XRD), X-Ray fluorescence (XRF), scanning electronic microscopy (SEM), thermogravimetry and differential thermal analysis (TG-DTA), Fourier transformed infra-red (FT-IR), specific area and porosity determinations. This physicochemical characterization pointed to successful TiO2 pillaring of the clay. The prepared material has porous structure and exhibit a good thermal stability as indicated by its surface area after calcination by microwave. The effects of operating parameters such as catalyst loading, initial pH of the solution and the pollutant concentration on the photocatalytic efficiency and COD removal  were evaluated. Under initial pH of the solution around seven, pollutant concentration of 10 mg/L and 2.5 g/L of catalyst at room temperature, the degradation efficiency and COD removal of linuron was best then the other operating conditions. It was observed that operational parameters play a major role in the photocatalytic degradation process. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

scholarly journals Effect of Biodegradable Binder Properties and Operating Conditions on Growth of Urea Particles in a Fluidized Bed Granulator

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2320 ◽  
Author(s):  
Ehsan Zhalehrajabi ◽  
Kok Keong Lau ◽  
Ku Zilati Ku Shaari ◽  
Seyed Mojib Zahraee ◽  
Seyed Hadi Seyedin ◽  
...  
Keyword(s):  
Fluidized Bed ◽  
Air Temperature ◽  
Scale Up ◽  
Cost Effective ◽  
Stokes Number ◽  
Operating Conditions ◽  
Air Velocity ◽  
Air Inlet ◽  
Lower Temperature ◽  
Penetration Time

Granulation is an important step during the production of urea granules. Most of the commercial binders used for granulation are toxic and non-biodegradable. In this study, a fully biodegradable and cost-effective starch-based binder is used for urea granulation in a fluidized bed granulator. The effect of binder properties such as viscosity, surface tension, contact angle, penetration time, and liquid bridge bonding force on granulation performance is studied. In addition, the effect of fluidized bed process parameters such as fluidizing air inlet velocity, air temperature, weight of primary urea particles, binder spray rate, and binder concentration is also evaluated using response surface methodology. Based on the results, binder with higher concentration demonstrates higher viscosity and higher penetration time that potentially enhance the granulation performance. The viscous Stokes number for binder with higher concentration is lower than critical Stokes number that increases coalescence rate. Higher viscosity and lower restitution coefficient of urea particles result in elastic losses and subsequent successful coalescence. Statistical analysis indicate that air velocity, air temperature, and weight of primary urea particles have major effects on granulation performance. Higher air velocity increases probability of collision, whereby lower temperature prevents binder to be dried up prior to collision. Findings of this study can be useful for process scale-up and industrial application.

Construction of a Broad-Based Experimental and Computational Test Capability for High Power Wide Bandgap Semiconductor Devices

2007 ◽  
Author(s):  
Jason A. Carter ◽  
Matthew D. Roth ◽  
Michael W. Horgan ◽  
Lisa Shellenberger ◽  
Daniel P. Hoffmann ◽  
...  
Keyword(s):  
Thermal Stresses ◽  
High Electron Mobility Transistors ◽  
Operating Conditions ◽  
High Electron ◽  
Thermal Impedance ◽  
Analysis Model ◽  
Operational Parameters ◽  
Material Interfaces ◽  
Electron Mobility Transistors ◽  
The Impact

In this paper, the authors will discuss the development and implementation of a test stand to assess the impact of temperature on the performance of commercial X-band gallium nitride (GaN) on silicon carbide (SiC) high electron mobility transistors (HEMTs) designed for radio frequency (RF) communications platforms. The devices are tested under a range of operating temperatures and under a range of electrical operating conditions of variable gate and source-drain voltages to assess the impact of temperature on core operational parameters of the device such as channel resistance and transconductance. This test capability includes infrared thermography and transient thermal impedance measurements of the device. In addition to the experimental effort, the initial construction of a finite-volume numerical analysis model of the device will be discussed. The focus of these models will be the accurate assessment of device thermal impedance based on assumed thermal loads and eventually the assessment of accumulated thermal stresses at the material interfaces within the device and package structure.

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