Slurry 10: Storage of Slurries
Slurry
10: Storage of Slurries Part 1: Slurry Tank Design 1 INTRODUCTION TO SLURRY TANK DESIGN 1.1 Methods for Suspending Solids in Tanks 1.2 Levels of Solids Suspension 1.3 Agitated Tank Design Employed for Solids Suspension 1.3.1 Tank Design. 1.3.2 Agitator Types Available and Selection. 1.4 Batch or Continuous Operation 1.5 Start-up from Settled Solids 2 COMPLETE SOLIDS SUSPENSION(JOBS) USING MECHANICAL AGITATORS 2.1 Empirical Correlations for Minimum Agitator Speed N js 2.1.1 Continuation section 2.2 Selection of N js Correlation for JOBS 2.3 Scale-up from Small-scale Tests Using Complete Suspension Criterion 2.4 Design for Suspending Floating Solids 2.5 Intermittent Versus Continuous Agitation 3 COMPLETE SOLIDS SUSPENSION (JOBS) BY GAS BUBBLE AGITATION 3.1 Solids Suspension through a Combination of Bubble and Impeller Agitation 3.2 Solids Suspension Using Bubbles Only 4 NEAR HOMOGENEOUS SUSPENSION 4.1 Is it necessary? 4.2 Can it be achieved with realistic power input? 4.3 Information on One-dimensional Vertical Solids Concentration Profiles 4.3.1 Continuation section 4.4 Information on Two-Dimensional Solids Concentration Profiles 4.4.1 Continuation section 5 SOLIDS SUSPENSION USING LIQUID OR SLURRY JETS 6 SOLIDS SUSPENSION BY VIBRATORY AGITATION 7. RECOMMENDATIONS FOR RESEARCH ON STORAGE FOR SETTLING SLURRIES AND SUSPENSIONS 8. NOTATION 9. REFERENCES Part 2: Commercially Available Slurry Agitators SUMMARY 1. INTRODUCTION 2. TYPES OF NON-PROXIMITY TOP-ENTRY AGITATORS 2.1 Non-proprietary 2.1.1 Marine Propeller 2.1.2 45?#176; 4-Bladed Pitched Turbine 2.1.3 Pitched Blade Turbine 2.1.4 Flat Blade ("Rushton") Turbine 2.2 Proprietary 2.2.1 ABS Pump Group - Scaba 2.2.2 APV Fluid Handling 2.2.3 Chemineer 2.2.4 De Dietrich 2.2.5 EKATO 2.2.6 Hayward Gordon 2.2.7 Lightnin 2.2.8 Milton Roy VRE 3000 range 2.2.9 Mixmor 2.2.10 Mixertech 2.2.11 Pfaudler 2.2.12 Philadelphia 2.2.13 Plenty 2.2.14 Svedala 2.2.15 Spyral Corporation 2.2.16 Vollrath 3. TYPES OF NON-PROXIMITY SIDE-ENTRY AGITATOR 3.1 Introduction 3.1.1 ABS Pump Group - Scaba 3.1.2 APV Fluid Handling 3.1.3 Chemineer 3.1.4 EKATO 3.1.5 Hayward Gordon 3.1.6 Joshua Greaves 3.1.7 Lightnin 3.1.8 Plenty 4. TYPES OF NON-PROXIMITY SUBMERSIBLE AGITATORS 4.1 Introduction 4.1.1 ABS Pump Group - Scaba 4.1.2 ITT Flygt 5. TYPES OF PROXIMITY AGITATOR 5.1 Non-proprietary 5.1.1 Anchor Impeller 5.1.2 Helical Impellers 5.2 Proprietary 5.2.1 Chemineer 5.2.2 EKATO 5.2.3 Lightnin 5.2.4 Plenty 6. CORRELATIONS FOR "JUST-OFF BOTTOM" SUSPENSION CRITERION 7. CORRELATIONS FOR "HEIGHT OF A HOMOGENEOUS ZONE" 8. POWER CONSUMPTION ESTIMATION 8.1 Newtonian Slurries - Non Proximity Agitators 8.1.1 Chemineer 8.1.2 EKATO 8.1.3 Lightnin 8.2 Newtonian Slurries - Proximity Agitators 8.3 Non-Newtonian Slurries - Non-Proximity Agitators 8.4 Non-Newtonian Slurries - Proximity Agitators 9. CAVERN SIZE ESTIMATION FOR VISCOPLASTIC SLURRIES 9.1 Theory 9.2 Non-proprietary Agitators 9.2.1 6-Bladed Disc (Rushton)Turbine 9.2.2 Marine Propeller 9.2.3 45?#176; 6-Bladed Pitched Turbine 9.3 Proprietary Agitators 9.3.1 Chemineer HE-3 9.3.2 Chemineer CD-6 9.3.3 Ekato Intermig 9.3.4 Lightnin A315 9.3.5 Scaba SRGT 10. NOTATION 11. REFERENCES 12. APPENDIX A: MANUFACTURERS / SUPPLIERS OF AGITATORS AND THEIR CONTACT DETAILS Part 3: Design of Slurry Storage Systems Part 4: SRR on Research into Comparison of Agitators Part 5: Flow of Solid-Liquid Mixtures from Hoppers 1. Introduction 1.1 Summary of contents 1.2 Characteristics of slurries 1.3 Discharge of solid-liquid mixtures from hoppers in industry 1.3.1 Food industry 1.3.2 Minerals processing 1.3.3 Dredging industry 1.3.4 Chemical industry 1.4 Typical problem areas 1.5 Research Centres 2. Basic Concepts 2.1 Flow patterns in hoppers 2.2 Parameters for solid-liquid mixtures 2.2.1 Stresses 2.2.2 Bulk Density 2.2.3 Internal and Wall Friction Angles 2.2.4 Cohesion 2.2.5 Solids Flow Function 2.3 Hopper Characteristics 2.3.1 Hopper flow factor ff 2.3.2 Critical Outlet Dimension 2.4 Critical Flow Condition 2.5 Determination of Properties of Solids and Hopper Wall 2.5.1 Test Requirements 2.5.2 Shear Testing Device 3. Theoretical studies 3.1 Flow Pattern Criterion 3.2 Mass Flow 3.2.1 Models 3.2.2 Prediction of volume flowrate 3.2.3 Prediction of discharge liquid fraction 3.2.4 Pressure distribution in hoppers 3.2.5 Application of dimensional analysis to scale-up 3.3 Funnel flow 3.4 Hopper design for handling solid-liquid mixtures 3.4.1 Design Principle 3.4.2 Hopper Half angle 3.4.3 Arching effect and outlet diameter 3.5 Corrective methods 4. Experimental studies 4.1 Experimental Study at CSIRO Australia 4.2 Silsoe Research Institute 4.3 University of Cambridge 4.4 University of Surrey 5. Future Activities 5.1 Theoretical 5.2 CFD 5.3 Physical Modelling 6. Conclusions 7. References 8. Notation |
Volume SH 10: Part 1 Slurry Tank Design This part considers the design of slurry tanks with emphasis on methods by which solids are kept in suspension. Volume SH 10: Part 2 Commercially-available Agitators This part surveys the variety of both non-proximity (turbines) and proximity (e.g., helical screw) agitators used for agitating low and high viscosity solid-containing liquids respectively. Turbines tend to be used for suspending particles in a slurry which would otherwise tend to settle out readily under gravity, while proximity agitators are used for agitating high viscosity fluids which may be Newtonian or non-Newtonian materials, with or without a yield stress, but where gravity-settling of solids may still be a potential problem. There are several proprietary designs of turbine for solids suspension. These designs have been developed, often with the aid of LDA measurements and with a view to minimising the agitator power consumption for a given slurry agitation duty. Claims made by manufacturers of so-called "profiled" agitators or "hydrofoils", tend to be unsubstantiated by independent studies. Proprietary designs of proximity agitators are far less common. All proprietary designs of agitator for solids suspension applications will be reviewed in the report. Non-proximity agitators are classified into top-entry, side-entry and portable. A start has been made in sections 2 and 3 to list commercially-available agitator designs from suppliers contacted in the UK. Additional UK suppliers will be contacted. The list will also be expanded to cover other North American and continental Europe mixer manufacturers and their products will be described in some detail. A similar approach will be taken in section 4 with proximity agitators, although there are far fewer proprietary designs of proximity agitator. Any guidelines from manufacturers and the open literature on how to choose between a non-proximity or proximity agitator will be included and discussed. It is not always clear from the manufacturers’ brochures obtained so far which non-proximity and proximity agitators are proprietary. This will be confirmed during the review. Sections 5 and 6 will outline the available correlations for predicting the agitator speed for "just-off-bottom" suspension and homogeneous suspension respectively. In particular, any additional information from manufacturers, beyond that already published in the open literature will be included and discussed. The estimation, as well as the minimisation, of agitator power consumption is important for sizing agitator shafts and drives. Section 7 summarises the technology behind agitator power estimation and provides information on power number/Reynolds number relationships for both non-proprietary and proprietary agitators, when this information is openly-available. Section 8 describes any case studies from the literature and from WSHP members’ input covering the successful or unsuccessful application of proprietary agitators to solids suspension duties. Volume SH 10: Part 3 Design of Slurry Storage Systems This part will take the form of a series of decision charts with accompanying explanation, clarification and expansion in the form of text to lead the engineer to an appropriate choice of agitation system. Such an approach then lends itself readily to conversion to software in which the decision charts take the form of an expert system, with "HELP" screens based on the clarifying text. The guide is aimed at engineers in industry who are not specialists in the selection and design of equipment for solids suspension duties. The main aims of the guide are as follows to indicate the best type of agitation system to select where new equipment is to be installed; to indicate the best type of agitator and to suggest possible manufacturers when mechanical agitation (either top-mounted, single or multiple agitators, or side-entry) is recommended; to enable a manufacturers' design data to be assessed by comparison with data generated by using the guide; to provide a basis for the design of a system to be supplied in-house; and to enable the suitability of an existing system for a new duty to be judged. Three main categories of agitation will be considered: mechanical (most effort will be focused on this option); recirculating slurry (or occasionally liquid) jet; bubble/sparging. Mechanical options would normally include one or more rotating agitators on either a single or multiple shafts, but some information will be included on the use of vibratory plates which may be appropriate for some duties. |