What's next Mixing of high viscosity materials
Download as PPT, PDF4 likes2,872 views
This document discusses mixing of high viscosity materials. It begins by defining mixing and its importance in producing consistent, homogenous mixtures. Mixing viscous materials presents challenges including heat transfer and requiring high mechanical energy. A variety of mixer types are presented that can handle viscous materials through different mixing mechanisms like shear and elongation. Selection of the proper high viscosity mixer requires considering material properties, process parameters, and testing through lab and pilot trials. Mixer design must provide thorough blending while preventing stagnation.
What's next Mixing of high viscosity materials
- 1. KNOWING WHAT’S NEXT IN MIXING OF HIGH VISCOSITY MATERIALS Jayesh R. Tekchandaney Director -Technical @ Unique Mixers Founder @ Mixing Expert Author – “Process Plant Equipment - Mixers” @ John Wiley, 2012 Contributor – “Dictionary of Industrial Terms” @ Scrivener-Wiley, 2012
- 2. DISCUSSION ◊ ◊ ◊ ◊ ◊ Importance of Mixing Challenges 20-20 Mixing Mechanisms What’s Next In High Viscosity Mixing Mixer Selection, Specification & Design Guidelines
- 3. MIXING ◊ Process of thoroughly combining different materials to produce a homogenous mix ◊ Consistency in chemical composition, color, flavor, reactivity ◊ Mixing is a critical process ◊ Quality of the final product, attributes depend on the mixing performance “Cost of poor mixing is estimated as US$ 100 million / year ”
- 4. PROFITABILITY !!! ◊ ◊ ◊ ◊ Polymer Product Product purity – 90%, US$ 45,000/ton Market demand – 95%, US$ 50,000/ton Change in mixer operating parameters – 92 to 93 % ◊ Change in mixing agitator design – 95 % ◊ Production capacity ~ 55,000 tons/yr “Mixer is no longer a generic production tool. It is a critical and decisive business tool.”
- 5. VISCOUS MATERIALS MATERIAL Water @ 70 F Honey Chocolate Syrup APPROXIMATE VISCOSITY (in centipoise) 1 to 5 10,000 10,000 to 25,000 Ketchup or French Mustard 50,000 to 70,000 Plastisol 50,000 (2 - 2.5 million cps during mixing process) Tomato Paste or Peanut Butter 150,000 to 250,000 Silicone Sealant 6 to 7 million Solid Propellant 10 to 15 million Dental whitening gels, polyester compounds, epoxies, transdermal drugs, dental composites, butyl sealants, automotive sound absorbing compounds, color pigment compounding pastes, and chewing gum formulations. “ The viscosities of materials to be processed are constantly on the rise, as there is an urgent need to cut levels of volatile organic compounds in most parts of the process industry ”
- 6. CHALLENGES 20-20 ◊ Increased customer expectation, constant development of new products ◊ Minimum time from new product conception to implementation ◊ Little time for lab trials - pilot scale - production ◊ Need for higher product purity, yields ◊ Price reductions, increasing costs ◊ Frequent Product Change Overs ◊ Multi-purpose equipment – Coating, granulation, heat transfer, drying ◊ HSE compliances
- 7. LIQUID MIXING “Liquid mixing depends on the creation of flow currents, which transport unmixed material to the mixing zone adjacent to the impeller ”
- 8. SOLID BLENDING Primary Mechanisms of Solid Blending ◊ Diffusion Blending ◊ Convection Blending ◊ Shear Blending
- 9. VISCOUS MIXING “ Mixing in viscous systems can be achieved only by mechanical action or by the forced shear or by elongation flow of the matrix ”
- 10. MIXING CHALLENGES Equipment Design, Scale-Up : Because of the viscosity and temperature changes that occur during the mixing process, it is difficult to model the system. Mixer drive systems should provide constant torque throughout the speed range, even at very low rotational speeds. Power Requirement : Mixing requires large amounts of shearing, folding over, dividing and recombining. mechanical energy for Heat Transfer : Heat transfer is generally poor in viscous materials. Mixers for high viscosity materials therefore need to be designed for promoting efficient heat transfer. Constraints – shear sensitive materials, hard to disperse powders, abrasive components. dense sticky material, hard agglomerates, volatile solvents, material rheology
- 14. DPM WITH HELICAL BLADES, HSD
- 15. DISCHARGE SYSTEM •Large batch sizes can be discharged in minutes •Eliminating time wasted in scraping heavy or sticky materials •Avoiding operator exposure to hazardous material Discharge is often overlooked and can end up as a bottleneck
- 16. CHANGE CANS Use of multiple vessel extends the production capacity • Mixing • Discharging • Cleaning • Loading
- 17. KNEADER MIXER
- 18. KNEADER EXTRUDER
- 19. VACUUM MIXING Mixer under vacuum can achieve several process goals and offer several benefits : De-aeration - Superior visual appeal of an air-free product, reduced risk of product failures. De-oxidation - The removal of oxygen prevents the oxidation, degradation of sensitive ingredients, improves product stability. Solid/liquid injection − Under vacuum, liquids and lightweight powders can be injected into a batch through a sub-surface port in the vessel. This accelerates mix cycle, especially by wetting out powders instantly. Vacuum drying - Excellent method for drying heat-sensitive materials without fear of thermal degradation
- 20. VACUUM MIXING Solvent recovery - Solvents drawn off with vacuum can be recovered, reused. Densification- With densification, the physical properties of the end-product are often improved. APPLICATIONS Adhesive and sealants – Vacuum mixing results in higher density and better tensile properties due to increased shear and contact of different components Food and pharmaceutical formulations – Vacuum mixing reduces the entrapped oxygen and leads to longer product shelf life and better stability “Vacuum can improve the performance of almost any mixing, blending or drying system”
- 21. HIGH VISCOSITY MIXERS CONTINUOUS MIXERS BATCH MIXERS Dual Shaft Mixer Triple Shaft Mixer Planetary - HSD Double Planetary Kneaders Kneader Extruder Intensive Mixer Banbury Mixer High Intensity Mixer Roll Mill Pan Muller Mixer Single Screw Extruder Twin Screw Extruder Pug Mill
- 22. MIXER SELECTION & SPECIFICATION BASIC CRITERIA ◊ Process setup ◊ Mixer operating parameters ◊ Mixing accuracy ◊ Mixer cleanability ◊ Equipment costs ◊ Viscosity ◊ Density ◊ Degree of Shear ◊ Sequence of addition ◊ Power consumption ◊ Process cycle time “There are many variables in each application and as a result no standard set of rules pinpoints which type of mixer is best suited for an application. Selection and scale-up of high viscosity mixers should be carried out after trials and in consultation with mixer manufacturers.”
- 23. LAB TRIALS Laboratory and pilot test results can useful data with respect to selection of mixer capacity, power requirements, heat transfer and above all the performance of the mixing process.
- 24. DESIGN GUIDELINES Mixing element should preferably operate within all parts of the mixing vessel. Maintain low clearances between the mixing element and the mixing container (1 to 2 mm). The mixing elements may comprise of intermeshing blades that prevent the material from cylindering along with the rotating mixing element. Mixers should be provided with close-clearance blades and / or scraper devices to move stagnant material away from heat-transfer surfaces. High connected power per unit volume. (upto 6 kW / kg of product) High viscosity mixers operate at low speeds, require high power and therefore need high torque. Discharge of materials after mixing may be difficult and may require special arrangements. As the forces generated during mixing process are high, mixers should be rigid in construction.
- 25. PRODUCTS & SERVICES Design, Manufacture, Supply, I Mixing process review nstallation, Commissioning of Mixing equipment review Liquid Agitators, Reactors… Solid Blenders V-Blender Ribbon Blender Plough Share Mixer… Viscous Mixer Planetary Mixer Kneader Mixers Kneader Mixer Extruders… Laboratory & pilot scale trials Scale-up Mixing Simulation Mixer troubleshooting Short courses, seminars Engineering services
- 26. THANK YOU Jayesh R. Tekchandaney Unique Mixers & Furnaces Pvt. Ltd www.uniquemixer.com, www.mixing-expert.com [email protected], [email protected] Phone (+91-22)-25801214, 25822385 “No matter how good you are, ou can always get better. And that’s the exciting part”