CH3041 Chemical Engineering Unit Operations II
Lau Wai Man, Raymond Jiang Rongrong Office: N1.2-B2-32 Office: N1.2-B1-08 Phone: 6316 8830 Phone: 6514 1055 Email: firstname.lastname@example.org Email: email@example.com
• Particulate Technology – Particle size analysis – Packed bed – Gas-solid fluidized bed – Gas-liquid-solid fluidized bed • Filtration • Crystallization • Drying
Covered by Prof. Jiang Rongrong
• Continuous Assessment – 30% Quizzes • Exam – 70% Final Exam
Particulate Technology • Liang-Shih Fan and Chao Zhu, Principles of Gas-solid flows, Cambridge University Press, 1998. • Ch.1.1-1.3; Ch.5.6; Ch.9.1-9.7; Ch.10.1-10.3; Ch.11.1-11.4
• If student misses CA due to following reasons:
– valid MC (not from Chinese doctor) – passing away of immediate family (parents, siblings, grandparents) – participate in an activity representing NTU then the CA component will be counted towards the final exam. There will be no makeup CA.
• Otherwise student gets 0 for CA.
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- Tutorial Week - Holiday
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Chinese New Year LT LT LT Quiz (CA1)
Particulate systems impact a number of industries including advanced materials, environmental, chemical, mineral, energy, agricultural, pharmaceutical, and food processing. Particle technology deals with the characterization, modification, handling, production and utilization of a wide variety of particles, in both dry and wet conditions. Recently, these issues are being reinvestigated for the nano- and bio-technologies.
The fourth phase in the nature: “powder” or “particulate solids” phase Not solid, but can withstand some deformation Not liquid, but can flow Not gas, but can be compressed Having some characteristics of the other three phases, but does not belong to any of the other phases.
Size and Properties of Particles
The flow characteristics of solid particles in a gas-solid suspension vary significantly with the geometric and material properties of the particle.
Material properties include such characteristics as physical adsorption, elastic and plastic deformation, ductile and brittle fracturing, solid electrification, magnetization, heat conduction and thermal radiation, and optical transmission.
Particle Size and Sizing Methods
Sieve Diameter: The width of the minimum square aperture through which the particle will pass. Sieve diameter Minimum dimension Maximum dimension
Martin’s Diameter, Feret’s Diameter, and Projected Area Diameter: Measured based on the projected image of a single particle. Martin’s diameter – Averaged cord length of a particle which equally divides the projected area Feret’s diameter – Averaged distance between pairs of parallel tangents to the projected outline of the particle Projected area diameter – dA=(4A/π)1/2 The particle orientation under which the measurement is made, is important! Thus, use a large number of sampled particles.
Based on 3-D geometric characteristic of particle Surface Diameter: the diameter of a sphere having the same surface area as the particle
Volume Diameter: the diameter of a sphere having the same volume as the particle
⎛ 6V ⎞ d v = ⎜ ⎟ ⎝ π ⎠
Sauter’s Diameter (surface-volume diameter): the diameter of a sphere having the same volume to surface ratio as the particle
6V d v3 d 32 = = 2 S ds
Dynamic Diameter: the diameter of a sphere having the same density and the same terminal velocity as the particle in a fluid of the same density and viscosity
Re t µ dt = ρ U pt
where Ret is the particle Reynolds number at the terminal...
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