...
Inlet
...
Channel
...
Design
...
Program
...
The
...
purpose
...
of
...
the
...
inlet
...
channel
...
program
...
is
...
to
...
determine
...
the
...
dimensions
...
of
...
the
...
inlet
...
channel,
...
the
...
dimensions
...
of
...
circular
...
ports
...
in
...
the
...
inlet
...
chimneys
...
that
...
deliver
...
water
...
from
...
the
...
inlet
...
channel
...
into
...
the
...
sedimentation
...
tank,
...
and
...
the
...
dimensions
...
of
...
the
...
weir
...
in
...
the
...
inlet
...
channel
...
that
...
will
...
regulate
...
the
...
height
...
of
...
the
...
water
...
in
...
the
...
inlet
...
channel
...
and
...
flocculator.
...
The
...
inlet
...
channel
...
will
...
run
...
along
...
the
...
inlet
...
end
...
of
...
the
...
sedimentation
...
tanks,
...
such
...
that
...
its
...
length
...
will
...
be
...
equal
...
to
...
the
...
combined
...
widths
...
of
...
all
...
the
...
sedimentation
...
tanks
...
plus
...
the
...
thickness
...
of
...
the
...
walls
...
between
...
the
...
tanks
...
and
...
the
...
thickness
...
of
...
the
...
walls
...
that
...
separate
...
the
...
bays
...
within
...
the
...
sedimentation
...
tank
...
channels.
The Inlet Channel Weir
The purpose if the inlet weir is to regulate the height of water in the inlet channel and flocculator. This is accomplished by a relation between the width of the weir and the head loss over the weir, which is governed by the equation:
| Latex |
|---|
h2. The Inlet Channel Weir The purpose if the inlet weir is to regulate the height of water in the inlet channel and flocculator. This is accomplished by a relation between the width of the weir and the head loss over the weir, which is governed by the equation: {latex} \large $$ W = {3 \over 2}{Q \over {K_{VC} \sqrt {2g} H^{{3 \over 2}} }} $$ {latex} |
Where
...
W
...
is
...
the
...
width
...
of
...
the
...
weir
...
and
...
H
...
is
...
the
...
head
...
loss
...
over
...
the weir. The weir can either be placed parallel or perpendicular to the length of the channel.
Parallel Weir
The parallel weir will be placed in the inlet channel such that it will satisfy two constraints. First that on the side of the weir that delivers water to the inlet chimneys, the width of the channel will be wide enough so that the energy dissipation rate associated with the channel geometry will be greater than the energy dissipation rate at the end of the flocculator and will also be wide enough to fit the ports leading to the inlet chimneys plus an additional 3 cm of space on each side of the port. The second constraint for placing the weir will be that on the side of the weir that delivers water to waste, the channel will be wide enough to handle the flow of water in the event that all sedimentation tanks are shut off and all of the water coming from the flocculator must go to waste; it must be able to handle the entire flow of the plant.
Perpendicular Weir
The perpendicular weir design is placed inside the inlet channel such that the energy dissipation rate associated with the inlet chimneys will be much greater than the energy dissipation rate in the open inlet channel. A perpendicular weir also must be placed so that it can handle the entire flow of the plant if all the sedimentation tanks are turned off and all water is going to waste.
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weir. The weir will be placed in the inlet channel such that it will satisfy two constraints. First that on the side of the weir that delivers water to the inlet chimneys, the width of the channel will be wide enough so that the energy dissipation rate associated with the channel geometry will be greater than the energy dissipation rate at the end of the flocculator and will also be wide enough to fit the ports leading to the inlet chimneys plus an additional 3 cm of space on each side of the port. The second constraint for placing the weir will be that on the side of the weir that delivers water to waste, the channel will be wide enough to handle the flow of water in the event that all sedimentation tanks are shut off and all of the water coming from the flocculator must go to waste; it must be able to handle the entire flow of the plant. \\ \\ {float:left|border=2px solid black} [!RenderedInlet.png|width=500px!|InletSide.bmp] {float} \\ \\ \\ \\ |
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{float:left|border=2px solid black}
[!InletTop.png|width=500px!|InletSide.bmp]
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{float:left|border=2px solid black}
[!InletFront.png|width=500px!|InletSide.bmp]
{float} |
Inlet Channel Design Algorithm
Algorithm
The length of the channel is a function of the number of sedimentation tanks, and the thickness of the walls between the sedimentation tanks.
| Latex |
|---|
\\ \\ h2. Inlet Channel Design Algorithm [Inlet Channel AutoCAD Drawing|AutoCAD Channel Program] h3. Algorithm The length of the channel is a function of the number of sedimentation tanks, and the thickness of the walls between the sedimentation tanks. {latex} \large $$ L_{Channel} = (N_{SedTanks} )(W_{Sed} ) + (N_{SedTanks} + 1)(T_{PlantWall} ) $$ {latex} |
The
...
cross
...
sectional
...
area
...
of
...
the
...
inlet
...
channel
...
on
...
the
...
side
...
of
...
the
...
weir
...
that
...
delivers
...
water
...
to
...
the
...
inlet
...
chimneys
...
is
...
determined
...
using
...
the
...
A.Port
...
function
...
in
...
| Latex |
|---|
Functions|Fluids Functions Design Program] {latex} \large $$ A_{InletChannel} = A_{Port} (Pi_{FlocDissipation} ,K_{LTurn90} ,Q_{Plant} ,ED_{SedInlet} ,Pi_{VenaContractaOrifice} ) $$ {latex} |
Therefore
...
the
...
height
...
of
...
the
...
water
...
in
...
the
...
inlet
...
channel
...
is
...
equal
...
to
...
the
...
square
...
root
...
of
...
the
...
area
...
of
...
the
...
channel.
| Latex |
|---|
} \large $$ HW_{InletChannel} = \sqrt {A_{InletChannel} } $$ {latex} |
The
...
first
...
constraint
...
for
...
the
...
width
...
of
...
the
...
inlet
...
channel
...
on
...
the
...
side
...
of
...
the
...
weir
...
that
...
delivers
...
water
...
to
...
the
...
chimneys
...
is
...
to
...
consider
...
the
...
energy
...
dissipation
...
rate.
...
The
...
area
...
of
...
the
...
inlet
...
channel
...
and
...
the
...
height
...
of
...
the
...
water
...
in
...
the
...
channel
...
have
...
already
...
been
...
calculated,
...
and
...
so
...
the
...
width
...
may
...
be
...
determined:
| Latex |
|---|
} \large $$ W_{InletChannelED} = {{A_{InletChannel} } \over {HW_{InletChannel} }} $$ {latex} |
Next
...
the
...
size
...
of
...
the
...
ports
...
that
...
take
...
the
...
flocculated
...
water
...
down
...
into
...
the
...
inlet
...
chimneys
...
and
...
to
...
the
...
sedimentation
...
ports
...
is
...
calculated
...
through
...
the
...
A.Port
...
function
...
in
...
...
| Latex |
|---|
|Fluids Functions Design Program]. {latex} \large $$ A_{SedManifoldEntrance} = A_{Port} (Pi_{FlocDissipation} ,K_{PipeEnt} ,Q_{SedManifold} ,ED_{SedInlet} ,Pi_{VenaContractaOrifice} ) $$ {latex} |
The
...
diameter
...
of
...
the
...
hole
...
that
...
delivers
...
the
...
water
...
from
...
the
...
inlet
...
channel
...
into
...
the
...
inlet
...
chimneys
...
is
...
calculated
...
using
...
an
...
array
...
that
...
loops
...
through
...
the
...
available
...
pipe
...
size
...
diameters
...
and
...
rounds
...
the
...
needed
...
diameter
...
up
...
to
...
the
...
next
...
available
...
diameter
...
through
...
the
...
function
...
found
...
in
...
the
...
...
| Latex |
|---|
|Pipe Database Design Program]. {latex} \large $$ {D_{SedChimneyPipe}} = {D_{pipelarger}}\left( {2\sqrt {{{{A_{SedManifoldEntrance}}} \over \pi }} ,\left. {{D_{Pipesizes}}} \right)} \right. $$ {latex} |
The
...
circular
...
hole
...
through
...
the
...
inlet
...
chimneys
...
must
...
have
...
at
...
least
...
3
...
cm
...
of
...
space
...
around
...
it,
...
and
...
so
...
the
...
second
...
constraint
...
on
...
the
...
width
...
of
...
the
...
inlet
...
channel
...
on
...
the
...
side
...
of
...
the
...
weir
...
that
...
delivers
...
the
...
water
...
to
...
the
...
chimneys
...
is
...
that
...
it
...
must
...
be
...
at
...
least
...
as
...
wide
...
as
...
the
...
diameter
...
of
...
this
...
port,
...
plus
...
the
...
3
...
cm
...
of
...
space
...
needed
...
on
...
each
...
side
...
of
...
the
...
port.
...
Therefore
...
the
...
width
...
of
...
the
...
inlet
...
channel
...
on
...
the
...
side
...
of
...
the
...
weir
...
delivering
...
water
...
to
...
the
...
chimneys
...
is
...
set
...
to
...
be
...
the
...
maximum
...
of
...
the
...
width
...
determined
...
by
...
the
...
allowable
...
energy
...
dissipation
...
in
...
the
...
inlet
...
channel,
...
and
...
the
...
width
...
needed
...
by
...
the
...
circular
...
port
...
in
...
the
...
inlet
...
chimney.
| Latex |
|---|
} \large $$ {W_{InletChannelEst}} = \max \left( {{W_{InletChannelED}},\left. {{D_{SedChimneyPipe}} + 2{S_{SedInletChannelMin}}} \right)} \right. $$ {latex} |
The
...
height
...
of
...
the
...
inlet
...
channel
...
is
...
equal
...
to
...
the
...
water
...
height
...
in
...
the
...
inlet
...
channel
...
plus
...
the
...
plant
...
freeboard
...
height,
...
so
...
that
...
the
...
water
...
is
...
not
...
at
...
the
...
very
...
top
...
of
...
the
...
channel.
| Latex |
|---|
} \large $$ H_{InletChannel} = HW_{InletChannel} + H_{PlantFreeboard} $$ {latex} |
As
...
mentioned
...
earlier,
...
the
...
inlet
...
channel
...
weir
...
will
...
serve
...
to
...
regulate
...
the
...
height
...
of
...
the
...
water
...
in
...
the
...
inlet
...
channel.
...
On
...
one
...
side
...
of
...
the
...
weir,
...
the
...
water
...
is
...
being
...
delivered
...
to
...
the
...
inlet
...
chimneys.
...
On
...
the
...
other
...
side
...
of
...
the
...
weir,
...
water
...
will
...
go
...
to
...
waste
...
when
...
the
...
sedimentation
...
tanks
...
are
...
shut
...
off.
...
The
...
width
...
of
...
this
...
side
...
of
...
the
...
weir
...
is
...
determined
...
to
...
be
...
able
...
to
...
handle
...
the
...
flow
...
in
...
the
...
case
...
that
...
all
...
of
...
the
...
sedimentation
...
tanks
...
are
...
shut
...
off
...
and
...
all
...
of
...
the
...
water
...
must
...
go
...
to
...
waste;
...
it
...
must
...
be
...
able
...
to
...
handle
...
the
...
entire
...
flow
...
rate
...
of
...
the
...
plant.
...
To
...
do
...
this,
...
the
...
inlet
...
channel
...
must
...
have
...
a
...
width
...
that
...
will
...
yield
...
a
...
desired
...
head
...
loss.
...
Taking
...
advantage
...
of
...
the
...
fact
...
that
...
head
...
loss
...
is
...
proportional
...
to
...
the
...
width
...
of
...
the
...
channel,
...
the
...
width
...
of
...
the
...
inlet
...
channel
...
on
...
the
...
side
...
of
...
the
...
weir
...
that
...
delivers
...
water
...
to
...
waste
...
is
...
determined
...
through
...
an
...
iterative
...
solution
...
that
...
compares
...
the
...
channels
...
width
...
and
...
calculated
...
head
...
loss
...
to
...
a
...
target
...
head
...
loss
...
and
...
then
...
adjusts
...
the
...
width
...
until
...
the
...
target
...
head
...
loss
...
is
...
reached.
...
This
...
algorithm
...
can
...
be
...
found
...
in
...
...
| Latex |
|---|
Design Program]. {latex} \large $$ W_{InletChannelWaste} = w_{channel\min HL} (H_{SedWeirInlet} ,H_{SedWeirInlet} ,Q_{Plant} ,L_{Channel} ,Nu_{Water} ,E_{Concrete} ,1,HL_{SedWeir} ) $$ {latex} |
The
...
width
...
of
...
the
...
entire
...
inlet
...
channel
...
is
...
now
...
the
...
sum
...
of
...
the
...
width
...
of
...
the
...
channel
...
delivering
...
water
...
to
...
the
...
inlet
...
chimneys,
...
the
...
thickness
...
of
...
the
...
weir,
...
and
...
the
...
width
...
of
...
the
...
channel
...
delivering
...
water
...
to
...
waste:
| Latex |
|---|
} \large $$ W_{InletChannel} = W_{InletChannelEst} + T_{SedWeir} + W_{InletChannelWaste} $$ {latex} |
Stopping the Flow of Water into the Sedimentation Tank
The inlet chimneys carry water from the inlet channel into the bottom of the sedimentation tank. However, sometimes it is necessary to shut off the flow of water into a sedimentation tank in order to clean it, make repairs, or to close it off if the plant is producing an excess of clean water. For this purpose, control pieces are needed to stop the flow of water into the chimneys. Individual control pieces for each chimney are advantageous because a particular sedimentation tank can be shut off while still allowing the rest of the plant to function normally.
The control piece consists of three parts:
1. A PVC pipe to fit into the coupling of the inlet chimney
2. A cap to cover the top of the PVC pipe
3. A thin, long tube that comes out of the cap and extends above the height of the water in the inlet channel to allow air to escape
The constraint for designing this control piece is the diameter of the coupling in the inlet chimney, which is derived from the variable D.SedChimneyPipe, the diameter of the chimney itself. With this variable, and using the information in the pipe database that specifies PVC coupling and cap sizes for a particular PVC pipe size, the dimensions of the rest of parts (1) and (2) of the control piece are determined. The specifications for the long tube are that it is less than 1 inch in diameter and that its height extends above the height of the water in the inlet channel (HW.InletChannel), so that air can flow out of it, and it is easy to pull out.
These chimney plugs are one half of the control pieces being designed to allow for the shutting off and re-filling of a sedimentation tank.