Friday, September 26, 2014

HYDRAULIC ANALYSIS CALCULATION FOR ASH SLURRY PIPELINE



HYDRAULIC ANALYSIS CALCULATION FOR ASH SLURRY PIPELINE


The velocity of slurry in pipelines shall be in the range 1.8 m/s to 2.5m/s to avoid increasing the wear rate of the pipeline (if operating velocity above 2.5m/s) and risks of settling out and causing a blockage inside pipeline (if operating velocity below 1.8m/s). This slurry is non-Newtonian fluid so that the formula of Durand equation will be applied to calculate the friction loss of slurry.



The difference i - iw represents an increase in pressure drop due to the presence of solids in the slurry. The effect of particle size on slurry pressure drop is accounted for by the inclusion of the drag coefficient CD.
In most industrial applications, the particle size is not uniform, so the equation above can be written as follows:

Step 1: Calculation CDRew2 based on input data.
CDRew2 = ρl(4gd3s - ρl)/(3µ2gc2
Whereas:
CD – Drag coefficient
d – Particle diameter (m)
g – Acceleration due to gravity (9.81 m/s2)
ρl – Density of liquid (kg/m3)
ρs – Density of solid particle (kg/m3)
Rew = d ρl w0/(gµ)
w0 – settling velocity (m/s)
µ - viscosity of liquid (kg.s/m).

Step 2: Find the drag coefficient of particles of individual size fraction based on result of step 1

Source: Piping handbook, seventh edition.

Step 3: Calculation of friction loss of slurry
Calculation follows below equation:

iw – friction loss for water (mH2O/m) were calculated by software.
i – Friction loss for slurry
Cvi – volume fraction of solid having size di
CDi – Drag coefficient of particle having size di
N – Total number of size fraction into which given particle size distribution is divided.

Calculation file: Download 

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