ABSTRACT
Thomas Baxter, James Prescott, Roger Barnum, and Jayant Khambekar
CONTENTS
14.1 Introduction ..................................................................................................348 14.1.1 Introduction to Flowability ............................................................... 349 14.1.2 Introduction to Blending ................................................................... 350 14.1.3 Introduction to Segregation .............................................................. 351
14.2 Typical Flow and Segregation Concerns ...................................................... 352 14.2.1 Common Flow Problems .................................................................. 352
14.2.1.1 No Flow .............................................................................. 352 14.2.1.2 Erratic Flow ....................................................................... 354 14.2.1.3 Fine Powder Flow Concerns: Two-Phase Flow Effects ..... 354
14.2.2 Flow Patterns .................................................................................... 355 14.2.3 Common Segregation Mechanisms .................................................. 357
14.2.3.1 Material Properties That Affect Segregation ..................... 357 14.2.3.2 Sifting Segregation............................................................. 358 14.2.3.3 Fluidization Segregation .................................................... 358 14.2.3.4 Dusting Segregation ........................................................... 359
14.3 Measurement of Flow Properties and Segregation Potential........................ 361 14.3.1 Cohesive Strength Tests: Preventing Arching and Ratholing ........... 361
14.3.1.1 Test Methods ...................................................................... 361 14.3.1.2 Calculation of the Minimum Required Outlet
Dimensions to Prevent Arching: Mass Flow Bin............... 363 14.3.1.3 Calculation of Minimum Required Outlet Dimensions
to Prevent Ratholing: Funnel Flow Bin .............................364 14.3.2 Wall Friction: Determining Hopper Angles for Mass Flow ............. 365
14.3.2.1 Test Method........................................................................ 365
14.1 INTRODUCTION
This chapter provides guidance in designing bulk solid (“powder”) handling equipment to provide consistent, reliable flow and to minimize segregation. The principles discussed in this chapter can be applied to analyzing new or existing equipment designs. The principles can also be used to compare different powders using the various test methods discussed.
