Showing papers on "Mixing (process engineering) published in 2006"

Principles of polymer processing

Abstract: 1 History, Structural Formulation of the Field Through Elementary Steps, and Future Perspectives 11 Historical Notes 12 Current Polymer Processing Practice 13 Analysis of Polymer Processing in Terms of Elementary Steps and Shaping Methods 14 Future Perspectives: From Polymer Processing to Macromolecular Engineering 2 The Balance Equations and Newtonian Fluid Dynamics 21 Introduction 22 The Balance Equations 23 Reynolds Transport Theorem 24 The Macroscopic Mass Balance and the Equation of Continuity 25 The Macroscopic Linear Momentum Balance and the Equation of Motion 26 The Stress Tensor 27 The Rate of Strain Tensor 28 Newtonian Fluids 29 The Macroscopic Energy Balance and the Bernoulli and Thermal Energy Equations 210 Mass Transport in Binary Mixtures and the Diffusion Equation 211 Mathematical Modeling, Common Boundary Conditions, Common Simplifying Assumptions, and the Lubrication Approximation 3 Polymer Rheology and Non-Newtonian Fluid Mechanics 31 Rheological Behavior, Rheometry, and Rheological Material Functions of Polymer Melts 32 Experimental Determination of the Viscosity and Normal Stress Difference Coefficients 33 Polymer Melt Constitutive Equations Based on Continuum Mechanics 34 Polymer Melt Constitutive Equations Based on Molecular Theories 4 The Handling and Transporting of Polymer Particulate Solids 41 Some Unique Properties of Particulate Solids 42 Agglomeration 43 Pressure Distribution in Bins and Hoppers 44 Flow and Flow Instabilities in Hoppers 45 Compaction 46 Flow in Closed Conduits 47 Mechanical Displacement Flow 48 Steady Mechanical Displacement Flow Aided by Drag 49 Steady Drag-induced Flow in Straight Channels 410 The Discrete Element Method 5 Melting 51 Classification and Discussion of Melting Mechanisms 52 Geometry, Boundary Conditions, and Physical Properties in Melting 53 Conduction Melting without Melt Removal 54 Moving Heat Sources 55 Sintering 56 Conduction Melting with Forced Melt Removal 57 Drag-induced Melt Removal 58 Pressure-induced Melt Removal 59 Deformation Melting 6 Pressurization and Pumping 61 Classification of Pressurization Methods 62 Synthesis of Pumping Machines from Basic Principles 63 The Single Screw Extruder Pump 64 Knife and Roll Coating, Calenders, and Roll Mills 65 The Normal Stress Pump 66 The Co-rotating Disk Pump 67 Positive Displacement Pumps 68 Twin Screw Extruder Pumps 7 Mixing 71 Basic Concepts and Mixing Mechanisms 72 Mixing Equipment and Operations of Multicomponent and Multiphase Systems 73 Distribution Functions 74 Characterization of Mixtures 75 Computational Analysis 8 Devolatilization 81 Introduction 82 Devolatilization Equipment 83 Devolatilization Mechanisms 84 Thermodynamic Considerations of Devolatilization 85 Diffusivity of Low Molecular Weight Components in Molten Polymers 86 Boiling Phenomena: Nucleation 87 Boiling-Foaming Mechanisms of Polymeric Melts 88 Ultrasound-enhanced Devolatilization 89 Bubble Growth 810 Bubble Dynamics and Mass Transfer in Shear Flow 811 Scanning Electron Microscopy Studies of Polymer Melt Devolatilization 9 Single Rotor Machines 91 Modeling of Processing Machines Using Elementary Steps 92 The Single Screw Melt Extrusion Process 93 The Single Screw Plasticating Extrusion Process 94 The Co-rotating Disk Plasticating Processor 10 Twin Screw and Twin Rotor Processing Equipment 101 Types of Twin Screw and Twin Rotor-based Machines 102 Counterrotating Twin Screw and Twin Rotor Machines 103 Co-rotating, Fully Intermeshing Twin Screw Extruders 11 Reactive Polymer Processing and Compounding 111 Classes of Polymer Chain Modification Reactions, Carried out in Reactive Polymer Processing Equipment 112 Reactor Classification 113 Mixing Considerations in Multicomponent Miscible Reactive Polymer Processing Systems 114 Reactive Processing of Multicomponent Immiscible and Compatibilized Immiscible Polymer Systems 115 Polymer Compounding 12 Die Forming 121 Capillary Flow 122 Elastic Effects in Capillary Flows 123 Sheet Forming and Film Casting 124 Tube, Blown Film, and Parison Forming 125 Wire Coating 126 Profile Extrusion 13 Molding 131 Injection Molding 132 Reactive Injection Molding 133 Compression Molding 14 Stretch Shaping 141 Fiber Spinning 142 Film Blowing 143 Blow Molding 15 Calendering 151 The Calendering Process 152 Mathematical Modeling of Calendering 153 Analysis of Calendering Using FEM Appendix A: Rheological and Thermophysical Properties of Polymers Appendix B: Conversion Tables to the International System of Units (SI) Appendix C: Notation Author Index Subject Index

Active micro-mixers using surface acoustic waves on Y-cut 128° LiNbO3

Abstract: This study presents an active method for micro-mixers using surface acoustic waves (SAW) to rapidly mix co-fluent fluids. Mixing is challenging work in microfluidic systems due to their low-Reynolds-number flow conditions. SAW devices were fabricated on 128? Y-cut lithium niobate (LiNbO3). The micro-mixers are these piezoelectric actuators integrated with polydimethylsiloxane microchannels. The effects of the applied voltages on interdigitated transducers (IDTs) and two layouts, parallel- and transversal-type, of micro-mixers on the mixing performance were experimentally explored. The experimental results revealed that the parallel-type mixer achieved a higher mixing effect. Meanwhile, a higher applied voltage on the IDTs led to a significant improvement in the mixing performance of the active micro-mixer. Typical temperature effects associated with the applied voltages on the IDTs were also investigated. Finally, a digestion reaction between a protein (hemoglobin) and an enzyme (trypsin) was performed to verify the capability of the micro-mixers. The protein?enzyme mixture was qualitatively analyzed using mass spectrometry. Using these SAW-based mixers, the amount of digested peptides increased. Additionally, the protein?enzyme mixture was also quantitatively analyzed using high-performance liquid chromatography. Experimental data showed that the amount of digested peptides increased 21.1% using the active mixer. Therefore, the developed micro-mixers can be applied in microfluidic systems for improving mixing efficiency and thus enhancing the bio-reaction.

Hot water storage type water heater

Abstract: PROBLEM TO BE SOLVED: To provide a hot water storage type water heater capable of detecting such a state that a hot water supply valve is kept in an opened state, and preventing continuation of hot water supply from a hot water storage tank to a bathtub SOLUTION: This hot water storage type water heater comprises a hot water storage tank 1 for storing hot water, a heat source machine for heating up the hot water in the hot water storage tank 1, a hot water supply pipe 9 for supplying water of high temperature from the hot water storage tank 1, a hot water/water mixing valve 13a for connecting the hot water supply pipe 9 and a water supply pipe 12 for supplying the water, a bathtub hot water supply pipe 24 for supplying the hot water/water mixed by the hot water/water mixing valve 13b to the bathtub, a bathtub hot water supply valve 25 for starting or stopping the supply of hot water/water to the bathtub 30, and a flow rate detecting means 26 for detecting a flow rate of the hot water/water supplied to the bathtub 30 When the flow rate detecting means 26 detects that the supply of hot water/water to the bathtub 30 is not stopped even though a signal for stopping the supply of hot water/water is output to the bathtub hot water supply valve 25, a start signal for starting the supply of hot water/water and a stop signal for stopping the supply of hot water/water are alternately repeatedly output to the bathtub hot water supply valve 25 by the predetermined number of times COPYRIGHT: (C)2008,JPO&INPIT

On the ionisation fraction in protoplanetary disks. II. The effect of turbulent mixing on gas-phase chemistry

Abstract: We calculate the ionisation fraction in protostellar disk models using two different gas-phase chemical networks, and examine the effect of turbulent mixing by modelling the diffusion of chemical species vertically through the disk. The aim is to determine in which regions of the disk gas can couple to a magnetic field and sustain MHD turbulence. The disk models are conventional α-disks, and the primary source of ionisation is X-ray irradiation from the central star. We assume that the vertical mixing arises because of turbulent diffusion, and accordingly equate the vertical diffusion coefficient, D, with the kinematic viscosity, v. We find that the effect of diffusion depends crucially on the elemental abundance of heavy metals (magnesium) included in the chemical model. In the absence of heavy metals, diffusion has essentially no effect on the ionisation structure of the disks, as the recombination time scale is much shorter than the turbulent diffusion time scale. When metals are included with an elemental abundance above a threshold value the diffusion can dramatically reduce the size of the magnetically decoupled region (dead zone), or even remove it altogther. This arises when recombination is dominated by metal ions, and the recombination time exceeds the vertical diffusion time scale. For a complex chemistry the elemental abundance of magnesium required to remove the dead zone is x Mg = 10 -10 -10 -8 . We also find that diffusion can modify the reaction pathways, giving rise to dominant species when diffusion is switched on that are minor species when diffusion is absent. This suggests that there may be chemical signatures of diffusive mixing that could be used to indirectly detect turbulent activity in protoplanetary disks. We find examples of models in which the dead zone in the outer disk region is rendered deeper when diffusion is switched on. This is caused by turbulent mixing diluting the electron fraction in regions where the ionisation degree is marginally above that required for good coupling. Overall these results suggest that global MHD turbulence in protoplanetary disks may he self-sustaining under favourable circumstances, as turbulent mixing can help maintain the ionisation fraction above that necessary to ensure good coupling between the gas and magnetic field.

Juice Dispensing System

Abstract: The present application describes a product mixing device. The product mixing device includes an ingredient combination chamber and means for agitation positioned about the ingredient combination chamber. The ingredient combination chamber includes a diluent inlet, a number of macro-ingredient inlets, a number of micro-ingredient inlets, and an outlet.

Method for the rapid pyrolysis of lignocellulose

Abstract: Method for fast pyrolysis of lignocellulose including: mechanically comminuting the lignocellulose to lignocellulose particles; at least one of completely drying and preheating the lignocellulose particles; mixing the lignocellulose particles with heat transfer particles so as to provide a mixture; heating the heat transfer particles, prior to the mixing, to a temperature between 500° C. and 650° C.; and heating, in a pyrolysis reactor with oxygen excluded, the lignocellulose particles using the heat transfer particles so as to establish a temperature between 400° C. and 600° C. for 1 to 50 seconds and so as to react the lignocellulose particles so as to provide pyrolysis coke, pyrolysis condensate, and pyrolysis gas.

Continuous process for production of silicone pressure sensitive adhesives

Abstract: A composition for preparing a pressure sensitive adhesive contains (A) a hydroxyl-functional polydiorganosiloxane polymer, (B) a hydroxyl-functional polyorganosiloxane resin, and (C) a solvent. A continuous method for producing the silicone pressure sensitive adhesive is performed by mixing the composition while heating the composition at a temperature above the vaporization point of the solvent and removing essentially all volatile species in an apparatus with a residence time sufficient for bodying ingredients (A) and (B). A devolatilizing twin-screw extruder is useful in the method.

Enhancement of monascus pigment production by the culture of Monascus sp. J101 at low temperature.

Abstract: In general, high broth viscosity is a key factor to be considered in a submerged fermentation of filamentous fungi. High broth viscosity was also observed in a batch fermentation of Monascus sp. J101 at 30 °C. In a batch culture at 30 °C, most cell growth was accomplished within 48 h, which induced highly entangled clumps. The resultant high viscosity induced heterogeneity inside the fermentor, poor oxygen transfer, and low pigment yield. However, these problems could be overcome by reducing fungal growth rate through culture at low temperature (25 °C). Cell growth was moderate and continued for 120 h, and low viscosity was maintained. The DO levels remained at 50% or higher with good mixing. As a result, the pigment yield at 25 °C was 10 times greater than at 30 °C.

Compositions and methods of making sustained release liquid formulations

Abstract: The present invention includes compositions and methods for the controlled release of active agents in a shelf-stable liquid formulation by blending one or more controlled release microbeads comprising one or more active agents, preparing a dense, thixotropic solution having a density that is at, or about, the density of the one or more microbeads comprising a thixotropic agent, water and one or more preservatives under conditions that reduce bubble formation and mixing the microbeads and the thixotropic solutions in a mixer that lacks scraping paddles.

Scale Up of Slurry Bubble Reactors

Abstract: Bubble column reactors are finding increasing use in industrial practice. They are in particular appropriate to carry out highly exothermic reactions, such as methanol synthesis or Fischer-Tropsch synthesis of conversion of synthesis gas to liquid paraffins. Industrial process require important volumes of reactors, the reactor diameter can reach 10 m. To control the reaction temperature, internal heat-exchange tubes (vertical tubes) are inserted inside the reactor. This study deals with the effects of scale and the presence of internals on hydrodynamic characteristics, for scale-up purposes based on experiments in cold mockups. Our study shows that the liquid recirculation intensity depends strongly on the column diameter whereas the gas holdup is slightly affected. Two methods are proposed to predict scale effect on liquid velocity: an empirical correlation proposed in the literature and a phenomenological model. Internals guide liquid: the large scale recirculation increases but fluctuations of liquid velocity decrease. Therefore the mixing of liquid is significantly affected by the presence of internals and is not well described by the standard mono dimensional axial dispersion model. A two-dimensional model, taking into account a radially dependent axial velocity profile and both axial and radial dispersion, is therefore developed to describe the liquid mixing in a bubble column with internals.

Scraped surface heat exchangers.

Abstract: Scraped surface heat exchangers (SSHEs) are commonly used in the food, chemical, and pharmaceutical industries for heat transfer, crystallization, and other continuous processes. They are ideally suited for products that are viscous, sticky, that contain particulate matter, or that need some degree of crystallization. Since these characteristics describe a vast majority of processed foods, SSHEs are especially suited for pumpable food products. During operation, the product is brought in contact with a heat transfer surface that is rapidly and continuously scraped, thereby exposing the surface to the passage of untreated product. In addition to maintaining high and uniform heat exchange, the scraper blades also provide simultaneous mixing and agitation. Heat exchange for sticky and viscous foods such as heavy salad dressings, margarine, chocolate, peanut butter, fondant, ice cream, and shortenings is possible only by using SSHEs. High heat transfer coefficients are achieved because the boundary layer is continuously replaced by fresh material. Moreover, the product is in contact with the heating surface for only a few seconds and high temperature gradients can be used without the danger of causing undesirable reactions. SSHEs are versatile in the use of heat transfer medium and the various unit operations that can be carried out simultaneously. This article critically reviews the current understanding of the operations and applications of SSHEs.

Hydrodynamics and gas mixing in a carbon nanotube agglomerate fluidized bed

Abstract: A typical nanoscale fiber material, carbon nanotubes (CNTs), was fluidized in a 280 mm inner diameter (ID) nano-agglomerate fluidized bed (NAFB). The solids distribution and gas mixing were measured by a self-developed conductance method and the hydrogen tracer technique. Typical nano-agglomerate fluidization characteristics, such as high bed expansion ratio and multi-staged agglomerate structure, were observed. Fluidization experiments over a wide gas velocity range showed that the CNT agglomerates have agglomerate-bubbling-fluidization (ABF) characteristics. Particulate fluidization can also be achieved in the range 0.017∼0.038 m/s, showing they also have Geldart-A particle characteristics. A systematic comparison of the transition velocities, solids distributions, and gas mixing between the fluidizations of CNT agglomerates and Geldart-A particles was carried out. CNT NAFBs have more non-uniform solids concentration profiles near the wall, but more homogenous micro-flow structures than Geldart-A particles, which leads to good gas mixing. These unique hydrodynamics behaviors are attributed to the difference in the microstructure between the nano-agglomerates and ordinary particles. © 2006 American Institute of Chemical Engineers AIChE J, 2006

Rheological behavior of starch–polycaprolactone (PCL) nanocomposite melts synthesized by reactive extrusion

Abstract: Rheological behavior of reactively extruded starch–PCL nanocomposite blends was evaluated in an off-line capillary rheometer. Power law models for blends with different nanoclay volume fractions were developed using appropriate correction factors. Consistency coefficients K for blends containing starch were significantly higher than 100% PCL. Starch–PCL nanocomposite blends showed shear-thinning behavior with higher pseudoplasticity than did 100% PCL. Viscosities of nanocomposite blends were significantly lower than that of 100% PCL and nonreactive starch–PCL composites synthesized from simple extrusion mixing. Power law coefficients developed in this study will be used to evaluate rheology-dependent parameters during scaling up the reactive extrusion process from a batch micro-extruder to a high output continuous twin-screw extruder. POLYM. ENG. SCI. 46:650–658, 2006. © 2006 Society of Plastics Engineers.

Cavitation device with balanced hydrostatic pressure

Abstract: A method of mixing two or more dissimilar fluids such a gas and a liquid is provided. The method includes the steps of introducing one fluid into the other to form a mixture, inducing cavitation in the mixture to reduce at least one of the fluids to a large number of relatively small units, and distributing the small units uniformly throughout the mixture. In a preferred embodiment, the step of inducing cavitation comprises introducing the mixture into a chamber having a rotating disk formed with a plurality of irregularities such as bores. The irregularities on the rotating disk induce cavitation in the mixture. The cavitation also breaks down van der Waals attractions within the mixture to enhance mixing.

Hydraulically integrated solids/liquid separation system for wastewater treatment

Abstract: A system and method for treating wastewater includes a treatment container for receiving and treating wastewater and a mixing/aeration system disposed in the treatment container. Wastewater is pumped under pressure from the treatment container through a solids/liquid separation system, preferably comprising multiple parallel membrane bioreactors, to separate the solids and liquids in the wastewater. Liquid retentate from the solids/liquid separation system is cycled back to the treatment container via the mixing/aeration system. The closed-loop system and method for solids/liquid separation and aeration/mixing provides for reduced equipment requirements and energy usage during operation.

Optical recording medium

Abstract: PROBLEM TO BE SOLVED: To provide an optical recording medium using a resin composition containing a polylactic resin and having excellent heat resistance for its substrate. SOLUTION: The optical recording medium is formed by using, for its substrate, the resin composition formed by mixing a polylactic resin and a thermoplastic resin having ≥75°C load deflection temperature measured at 1.82 MPa load. The thermoplastic resin is preferably a polymethylmethacrylate or a polymethylmethacrylate having ≤110°C load deflection temperature measured at 1.82 MPa, or consists of at least two polymethylmethacrylates having ≥3% difference of syndiotacticity therebetween. The resin composition used for the substrate has ≥70°C load deflection temperature measured at 1.82 MPa load. COPYRIGHT: (C)2006,JPO&NCIPI