ChE 154 lecture 2b.pdf
10
Asst. Prof. Jewel A. Capunitan Department of Chemical Engineering College of Engineering and Agro-Industrial Technology University of the Philippines Los Baños ChE 154 - Transfer Operations II 1 st sem. 2014-2015 PROPERTIES OF SOLIDS
Transcript of ChE 154 lecture 2b.pdf
Asst. Prof. Jewel A. CapunitanDepartment of Chemical EngineeringCollege of Engineering and Agro-Industrial TechnologyUniversity of the Philippines Los Baños
ChE 154 - Transfer Operations II1st sem. 2014-2015
PROPERTIES OF SOLIDS
PARTICLE SIZE: ADDITIONAL NOTES
REFERENCES: http://golik.co.il/Data/ABasicGuidtoParticleCharacterization%282%29_1962085150.pdfhttp://www.horiba.com/fileadmin/uploads/Scientific/eMag/PSA/Guidebook/pdf/PSA_Guidebook.pdf
PARTICLE SIZE
• influences many properties of particulate materials and is a valuableindicator of quality and performance
• important in various industries as it influences material properties suchas:
reactivity or dissolution rate e.g. catalysts, tabletsstability in suspension e.g. sediments, paintstexture and feel e.g. food ingredientsappearance e.g. powder coatings and inksflowability and handling e.g. granulespacking density and porosity e.g. ceramics
PARTICLE SIZE
WHICH SIZE TO MEASURE?
• For a spherical particle: size =diameter because everydimension is identical
• For non-spherical particle:multiple length and widthmeasures (horizontal andvertical projections are shownbelow) but requires greatcomplexity
Figure 1. Particle size measurement
PARTICLE SIZE
WHICH SIZE TO MEASURE?
• Equivalent spherical diameter: many techniques make the usefuland convenient assumption that every particle is a sphere
• This approach is simplistic and not perfectly accurate but for mostindustrial processes, the shapes of particles generated are suchthat the spherical assumption does not cause serious problems
PARTICLE SIZE
Figure 2. Equivalent spherical diameter
PARTICLE SIZE DISTRIBUTION
• Performing a particle size analysis is the best way to answer the question:What size are those particles?
• Reporting the result: average size - a single number cannot describe thedistribution of the sample
• Interpreting results of a particle size measurement requires anunderstanding of which technique was used and the basis of thecalculations
• Each technique generates a different result since each measures differentphysical properties of the sample. Once the physical property ismeasured a calculation of some type generates a representation of aparticle size distribution
EXAMPLE: PSD INTERPRETATION - NUMBER VS. VOLUME DISTRIBUTION
Figure 3. Particles with different sizes (left) and corresponding number and volume distributions (center and right)
EXAMPLE: PSD INTERPRETATION - NUMBER VS. VOLUME DISTRIBUTION
Figure 4. Another example of number and volume distributions
PARTICLE CHARACTERIZATION TECHNIQUES
Figure 5. Particle characterization systems
