1. Dynamics of Particulate Systems

2. Measurement Techniques
Electrical Capacitance Tomography (ECT)
Velocity (Twin Plane)
Concentration
Particle Image Velocimetry (PIV)
Velocity
Phase Doppler Particle Analyzer (PDPA)
Number density

3. Single Plane ECT System
Components
Capacitance Measurement
Data Acquisition Unit
Multiplexing
Circuit
Capacitance
To Voltage
Transfer
A/D
Converter
Insulating Pipe
Control Signals
Electrode
Data
Post Processing
Image Reconstruction
Algorithm

4. Single Plane ECT System
Mechanism
Measures capacitance of 12 electrodes
Obtains 66 capacitance values
Utilizes distribution of permeability to obtain porosity
Solves for solid concentration

5. Twin Plane ECT System ( D ) U = L /D Plane 1 Plane 2 V Signal Delay
Cross Correlation
Signal Delay
( D )
U = L /D
Plane 1
Plane 2 V

6. Twin Plane ECT System Mechanism
Measures particulate concentration profiles at two axially-separated locations
Obtains velocity profile via correlation techniques
Obtains overall flow rate via integration of product of both concentration and velocity profiles
Obtains the volumetric flow of the particulates via second integration over a period of time

7. PIV System
(1) Synchronizer (2) Computer (3) Laser generator (4) CCD camera (5) Vessel (6) Vibrator (7) Function generator (8) Power amplifier

8. PIV System
Mechanism
Measures instantaneous global velocity in a flowing fluid
CCD camera takes pictures
Displacement/Time = Velocity

9. Stability Analysis

10. Perturbation Form
Perturbations:
Where:
And:

11. Ωr is > 0 (positive): amplitude of disturbance increases with time
Ωr is < 0 (negative): amplitude of disturbance decays with time
Ωr is positive: unstable mode
If you introduce a small disturbance, integrate forward with time, the variable will move away from steady state
Ωr is negative: stable mode

12. Stability Diagram
(+ve Eigen value)
(-ve Eigen value)

13. Electrostatic Characterization
5: MPCT / ECT
6: Induced current measurement
7: Faraday Cage

14. Types of flow Disperse flow (highest u) Half Ring flow
Ring flow (lowest u)

15. Summary
Air flow rate - lower air flow rate, higher induced current and particle charge density
Time – Charge accumulation for pipewall and individual particle increases with time for all types of flow. Leads to clustering of particles even in case of disperse flow.
Composition – Antistatic agent, Lacrostat 519 powder can reduce electrostatic effect.
Tribroelectrification – strong force effect created on walls when particles slide on pipe wall.

16. Discrete element method (DEM)
A numerical method for computing the motion and effect of a large number of small particles in a pipe by using computational fluid dynamics.
Outline of the method
A DEM-simulation is started selecting a model and setting an initial gas velocity.
The forces which act on each particle are computed from the initial data, relevant physical laws and contact models.
The change in the position and the velocity of each particle during a certain time step can be computed from Newton's laws of motion.

17. Models
Force Displacement Model
Fluid Drag Force Model

18. Types of flows Vertical pneumatic conveying Dispersed flow Plug flow
Horizontal pneumatic conveying
Stratified Flow
Moving dunes
Slug Flow
Homogeneous Flow
For different types of flow and gas velocity, the solid flow rate profile and the solid concentration profile can be determined from the data and graph.

19. Thank you