h1. Sludge Drain Design Program
This program designs the pipe that will be used for the sedimentation tank sludge drainage. The sludge drain runs along the bottom of the each sedimentation tank and collects the flocs as they fall from the lamella and slopes.
!SludeDrain.jpg!
h2. Sludge Drain Design Algorithm
[Sludge Drain Inputs|Sludge Drain Design Program Inputs]
[Sludge Drain Outputs|Sludge Drain Design Program Outputs]
[Sludge Drain AutoCAD Drawing Program|AutoCAD Sludge Pipe Program]
h3. Algorithm
The number of sludge drains is determined by the number of sloped pairs in the sedimentation tanks. This is defined as N.SedSludge, and uses the number of slope pairs calculated in the [Sedimentation Inlet Slopes|Sedimentation Inlet Slopes Design Program] program.
Next, the number of orifices in the pipe can be calculated given the orifice spacing from the [Design Assumptions|Design Assumptions Design Program], and the given length of the sedimentation tank from the [Sedimentation|Sedimentation Design Program] program.
{include:N.SedSludgeOrifices}
The initial flow rate through the sludge drain is calculated using values found in the [Sedimentation program|Sedimentation Design Program], and the drainage time for the sedimentation found in the [Design Assumptions|Design Assumptions Design Program] program.
{include:Q.SludgeDrainInitial}
The diameter of the sludge drain pipe is estimated through an iterative process, using the ND.Manifold equation found in the [Fluids Functions|Fluids Functions Design Program] program.
{include:ND.SedSludge}
Because the sludge drain is no longer a pipe but now a rectangular channel, this nominal diameter is then used to calculate the required cross-sectional area of the drain. Based on manifold theory, the total area of the sludge orifices is equal to the cross sectional area of the manifold. Given the required area for uniform flow, and the depth of the drain, H.SedSludge (set to be 5 cm in Design Assumptions), the width of the drain is calculated.
{include:TotalArea.SludgeOrifices}
{latex}
\large
$$
$$
W_{SedSludge} = {{TotalArea_{SludgeOrifices} } \over {H_{SedSludge} }}
$$
$$
{latex}
Using this head loss, the diameter of each orifice is calculated using the D.orifice equation from the Fluids Functions program. This uses a Q.orifice, which is equivalent to the flow rate through the sedimentation tank divided by the number of slope pairs.
{include:D.SedSludgeOrifice} | 