...
Horizontal
...
Flow
...
Flocculation
...
Design
...
Program
...
This
...
flocculator
...
program
...
determines
...
the
...
size,
...
number,
...
and
...
spacing
...
of
...
the
...
flocculator
...
channels
...
and
...
baffles,
...
based
...
on
...
the
...
results
...
of
...
the
...
Computational
...
Fluid
...
Dynamics
...
(CFD)
...
team
...
and
...
the
...
specification
...
of
...
horizontal
...
flow.
...
Horizontal
...
flow
...
is
...
used
...
for
...
very
...
high
...
flow
...
rates
...
to
...
avoid
...
building
...
the
...
plants
...
even
...
taller,
...
instead
...
making
...
them
...
wider.
...
Horizontal
...
flocculators
...
are
...
also
...
easier
...
to
...
drain
...
than
...
vertical
...
flocculators
...
made
...
of
...
cement
...
baffles
...
because
...
individual
...
drains
...
are
...
not
...
needed
...
for
...
every
...
lower
...
baffle
...
as
...
they
...
are
...
in
...
the
...
vertical
...
flocculator.
...
The
...
tank
...
is
...
designed
...
given
...
an
...
optimal
...
energy
...
dissipation
...
rate
...
to
...
maximize
...
the
...
opportunity
...
for
...
flocs
...
to
...
form
...
and
...
to
...
produce
...
flocs
...
that
...
are
...
small
...
enough
...
that
...
they
...
can
...
be
...
transported
...
to
...
the
...
sedimentation
...
tank
...
without
...
breaking.
...
The
...
program
...
also
...
outputs
...
arrays
...
of
...
the
...
location
...
of
...
each
...
baffle
...
in
...
the
...
tank;
...
these
...
arrays
...
are
...
used
...
by
...
the
...
AutoCAD
...
scripts
...
to
...
draw
...
the
...
baffles
...
in
...
place
...
in
...
the
...
flocculator.
...
The
...
programs
...
used
...
are
...
Flocculator
...
3
...
(the
...
design
...
program)
...
and
...
floctank
...
(
...
...
...
...
).
...
In
...
the
...
scheme
...
of
...
the
...
whole
...
plant,
...
the
...
flocculation
...
tank
...
is
...
drawn
...
after
...
the
...
sedimentation
...
tank
...
(so
...
many
...
of
...
our
...
variables
...
are
...
constrained
...
by
...
an
...
already-drawn
...
sedimentation
...
tank).
...
The
...
design
...
program
...
from
...
horizontal
...
flow
...
is
...
integrated
...
into
...
the
...
same
...
program
...
used
...
to
...
design
...
vertical
...
flow
...
flocculators
...
and
...
an
...
...
is
...
used
...
to
...
select
...
between
...
the
...
two
...
designs.
Generic | Vertical | Horizontal |
Ρ | W | H |
S | S | S |
J | H | W |
To create a consistent relation between vertical and horizontal flow, generic notation is used. J represents the flow travel distance between flow direction changes. The flow area, which is the cross sectional area that is perpendicular to the flow of the water, is P*S.
Top View
Flocculation Design Algorithm
Each section outlined below corresponds to its equivalent MathCAD code, identified by the same titles.
To view the first part that informs and establishes the equations and design ideas used in the actual drawing of the tank refer to the Vertical Flow Flocculation Design Program page as these equations and ideas are the same.
The second part determines the number, spacing, energy dissipation, and collision potential of the necessary baffles.
The third part determines the width, height, size, and the other parameters needed to draw the flocculation tank with the baffles inside it. This section is heavily relied upon by the MathCAD code in floctank that draws the plant.
The last part creates and outputs the matrix of baffle positions.
Flocculator Functions
The critical balance in the flocculator is between ensuring that the alum and entering water are meeting the energy dissipation (ED) and collision potential (CP) goals, and not breaking up flocs that have formed.
Calculating the number of baffle spaces that gives the target ED and CP is done with a non-iterative code (as opposed to the vertical code which is iterative sometimes). The optimal J/S value of 3 found from the CFD calculations can be used for horizontal flocculators since the flocculator can be made as wide as necessary (whereas in vertical flocculation, J was constrained by the height of the sedimentation tank), so iteration is not needed. The space between two baffles is determined using the following code:
| Wiki Markup |
|---|
| Generic | Vertical | Horizontal | | Ρ | W | H | | S | S | S | | J | H | W | To create a consistent relation between vertical and horizontal flow, generic notation is used. J represents the flow travel distance between flow direction changes. The flow area, which is the cross sectional area that is perpendicular to the flow of the water, is P*S. h2. Top View !Horizontal Top Dimensions.PNG|width=1081,height=596! h2. Flocculation Design Algorithm Each section outlined below corresponds to its equivalent MathCAD code, identified by the same titles. To view the first part that informs and establishes the equations and design ideas used in the actual drawing of the tank refer to the [Vertical Flow Flocculation Design Program] page as these equations and ideas are the same. The second part determines the number, spacing, energy dissipation, and collision potential of the necessary baffles. The third part determines the width, height, size, and the other parameters needed to draw the flocculation tank with the baffles inside it. This section is heavily relied upon by the MathCAD code in floctank that draws the plant. The last part creates and outputs the matrix of baffle positions. h2. Flocculator Functions The critical balance in the flocculator is between ensuring that the alum and entering water are meeting the energy dissipation (ED) and collision potential (CP) goals, and not breaking up flocs that have formed. Calculating the number of baffle spaces that gives the target ED and CP is done with a non-iterative code (as opposed to the vertical code which is iterative sometimes). The optimal J/S value of 3 found from the CFD calculations can be used for horizontal flocculators since the flocculator can be made as wide as necessary (whereas in vertical flocculation, J was constrained by the height of the sedimentation tank), so iteration is not needed. The space between two baffles is determined using the following code: {latex} \large $$ S = \mathop {\left( {{{\mathop Q\nolimits_{Plant} } \over {\mathop P\nolimits_{FlocChannel} }}} \right)}\nolimits^{{3 \over 4}} \mathop {\left( {{1 \over {\mathop {Pi}\nolimits_{JS} }}} \right)}\nolimits^{{1 \over 4}} \mathop {\left( {{{\mathop K\nolimits_P \mathop \alpha \nolimits_\varepsilon } \over {2ED}}} \right)}\nolimits^{{1 \over 4}} $$ {latex} \\ |
The
...
number
...
of
...
spaces
...
per
...
channel
...
is
...
determined
...
by
...
a
...
non-iterative
...
code
...
also
...
since
...
the
...
length
...
of
...
the
...
channels
...
are
...
fixed
...
to
...
be
...
the
...
length
...
of
...
the
...
sedimentation
...
tank.
...
Unlike
...
in
...
vertical
...
flow
...
flocculation,
...
channels
...
will
...
always
...
have
...
an
...
odd
...
number
...
of
...
spaces
...
to
...
ensure
...
that
...
water
...
flows
...
into
...
successive
...
channels
...
and
...
eventually
...
into
...
the
...
sedimentation
...
tank.
...
See
...
Calculation
...
of
...
Flocculator
...
Geometry
...
for
...
this
...
equation.
...
Calculation
...
of
...
Flocculator
...
Geometry
...
The
...
depth
...
of
...
water
...
at
...
the
...
end
...
of
...
the
...
flocculation
...
tank
...
is
...
set
...
by
...
the
...
user.
...
The
...
different
...
options
...
are
...
described
...
in
...
the
...
...
that
...
chooses
...
between
...
horizontal
...
and
...
vertical.
...
If
...
the
...
floc
...
tank
...
is
...
shallower
...
than
...
the
...
sed
...
tank,
...
the
...
floc
...
tank
...
is
...
elevated
...
so
...
that
...
the
...
water
...
levels
...
match.
...
The
...
number
...
and
...
spacing
...
of
...
floc
...
spaces
...
and
...
floc
...
baffles
...
is
...
calculated,
...
as
...
well
...
as
...
the
...
Collision
...
Potential,
...
for
...
the
...
specific
...
tank
...
being
...
drawn.
...
The
...
number
...
of
...
floc
...
spaces
...
is
...
determined
...
using
...
the
...
following
...
function
...
which
...
forces
...
the
...
number
...
of
...
spaces
...
to
...
be
...
an
...
odd
...
integer:
| Wiki Markup |
|---|
{latex} \large $$ {N_{FlocSpacesF}}(L,{\rm{T}},S) = Floor({{L + {\rm{T}}} \over {S + {\rm{T}}}} + 1,2) - 1 $$ {latex} \\ |
When
...
calculating
...
the
...
spacing,
...
L
...
represents
...
the
...
length
...
of
...
the
...
sed
...
tank
...
L.Sed
...
and
...
T
...
represents
...
the
...
thickness
...
of
...
a
...
baffle
...
T.FlocBaffle
...
.
...
The
...
minimum
...
baffle
...
spacing
...
is
...
45
...
cm,
...
which
...
is
...
the
...
width
...
that
...
a
...
human
...
could
...
walk
...
through
...
if
...
needed
...
for
...
maintenance.
...
The
...
center-to-center
...
distance
...
between
...
baffles
...
includes
...
the
...
spacing
...
between
...
baffles
...
and
...
the
...
thickness
...
of
...
the
...
baffles,
...
for
...
each
...
channel.
...
This
...
is
...
an
...
array
...
with
...
an
...
element
...
for
...
each
...
channel.
...
Since
...
the
...
horizontal
...
design
...
is
...
untapered,
...
each
...
channel
...
should
...
have
...
the
...
same
...
baffle
...
spacing,
...
but
...
the
...
code
...
was
...
kept
...
as
...
similar
...
to
...
the
...
vertical
...
code
...
as
...
possible.
...
The
...
exception
...
is
...
the
...
last
...
channel,
...
which
...
might
...
have
...
corrected
...
spacing
...
to
...
make
...
up
...
for
...
the
...
wide
...
entrance
...
into
...
the
...
inlet
...
channel.
| Wiki Markup |
|---|
{latex} \large $$ B_{FlocBaffle} = S_{FlocBaffle} + T_{FlocBaffle} $$ {latex} \\ $$ {latex} |
The
...
total
...
number
...
of
...
channels
...
is
...
found
...
by
...
dividing
...
the
...
total
...
target
...
collision
...
potential
...
by
...
the
...
collision
...
potential
...
per
...
space
...
and
...
rounding
...
that
...
value
...
up
...
according
...
to
...
how
...
many
...
spaces
...
are
...
in
...
a
...
channel.
...
The
...
residence
...
time
...
in
...
the
...
flocculator
...
is
...
determined
...
as
...
follows:
| Wiki Markup |
|---|
{latex} \large $$ Ti_{Floc} = {{HW_{FlocEnd} \cdot L_{FlocTank} \cdot {{\rm P}_{FlocChannel}}} \over {Q_{Plant}}} $$ {latex} \\ |
The
...
height
...
of
...
water
...
at
...
the
...
beginning
...
of
...
the
...
flocculator
...
is
...
based
...
on
...
the
...
height
...
of
...
water
...
at
...
the
...
end
...
of
...
the
...
flocculator
...
plus
...
the
...
headloss
...
through
...
the
...
flocculator.
...
The
...
head
...
loss
...
is
...
determined
...
per
...
baffle
...
(and
...
per
...
channel,
...
and
...
in
...
the
...
whole
...
flocculator)
...
based
...
on
...
the
...
minor
...
loss
...
coefficient
...
for
...
flow
...
around
...
a
...
baffle.
...
An
...
additional
...
freeboard
...
space
...
was
...
added
...
to
...
the
...
water
...
level
...
(HW)
...
found at
...
the
...
beginning
...
of
...
the
...
flocculator
...
to
...
determine
...
the
...
height
...
of
...
the
...
flocculator
...
walls.
...
The
...
head
...
loss
...
per
...
baffle:
| Wiki Markup |
|---|
{latex} \large $$ HL_{FlocBaffle} = {{{Kp \cdot ({{J_{FlocChannel}} \over {S_{FlocBaffle}}}) \cdot Q_{Plant}^2 } \over {2 \cdot g \cdot (S_{FlocBaffle} \cdot P_{FlocChannel})^2 }}} $$ {latex} \\ |
Water
...
flows
...
between
...
channels
...
in
...
the
...
flocculator.
...
There
...
are
...
no
...
ports
...
as
...
there
...
were
...
for
...
the
...
vertical
...
flocculator
...
because
...
they
...
were
...
only
...
necessary
...
to
...
maintain
...
the
...
vertical
...
flow
...
pattern.
...
The
...
width
...
is
...
the
...
same
...
as
...
the
...
baffle
...
spacing
...
in
...
the
...
previous
...
channel
...
and
...
the
...
height
...
is
...
the
...
height
...
of
...
the
...
floc
...
tank.
Position Calculations for Each Baffle
The length of the lower floc baffles and upper floc baffles that was seen in vertical flow is now the length of the left and right baffles (both are on the same height level). These baffles are set to line up with the top of the tank rather than the water level. The baffles are oriented to switch from one side of the tank channel's wall to other ("east" to "west") so that the flow of water is smooth back and forth through the tank. The baffles must be staggered in opposite directions in each channel so that the baffles at the end will form the necessary channel connecting the larger floc channels.
Length of "Lower" Baffle = Length of "Upper" Baffle:
| Wiki Markup |
|---|
\\ h2. Position Calculations for Each Baffle The length of the lower floc baffles and upper floc baffles that was seen in vertical flow is now the length of the left and right baffles (both are on the same height level). These baffles are set to line up with the top of the tank rather than the water level. The baffles are oriented to switch from one side of the tank channel's wall to other ("east" to "west") so that the flow of water is smooth back and forth through the tank. The baffles must be staggered in opposite directions in each channel so that the baffles at the end will form the necessary channel connecting the larger floc channels. Length of "Lower" Baffle = Length of "Upper" Baffle: {latex} \large $$ L_{FlocBaffleLower} = J_{FlocChannel} - S_{FlocBaffle} $$ $$ L_{FlocBaffleUpper} = J_{FlocChannel} - S_{FlocBaffle} $$ {latex} |
The
...
placement
...
of
...
the
...
baffles
...
in
...
the
...
flocculator
...
is
...
determined
...
by
...
algorithms
...
that
...
create
...
a
...
matrix
...
of
...
baffle
...
displacements
...
from
...
the
...
end
...
of
...
the
...
flocculator
...
(see
...
this drawing program for step-by-step
...
details
...
of
...
how
...
the
...
lamina,
...
baffles,
...
and
...
other
...
tank
...
details
...
are
...
drawn).
...
All
...
baffles
...
are
...
also
...
placed
...
at
...
the
...
bottom
...
of
...
the
...
tank,
...
which
...
is
...
represented
...
in
...
a
...
Z-matrix
...
for
...
the
...
baffles.
Drain Design
Port Sizing
The time it takes to drain the flocculator can be approximated by:
| Wiki Markup |
|---|
\\ h2. Drain Design h3. Port Sizing The time it takes to drain the flocculator can be approximated by: {latex} \large $$ D = {\sqrt {{\sqrt {h_0 }} \over {{{\pi t} \over {8A_{res} }}\sqrt {{{2g} \over {K_{minor} }}} }}} $$ {latex} |
where
...
D
...
is
...
the
...
nominal
...
valve
...
diameter,
...
h
...
o is
...
the
...
initial
...
water
...
height
...
in
...
the
...
flocculator,
...
A
...
res is
...
the
...
plan
...
area
...
the
...
entire
...
tank,
...
and
...
K
...
minor is
...
the
...
minor
...
loss
...
coefficient
...
associated
...
with
...
the
...
valve
...
and
...
subsequent
...
expansion.
...
Since
...
there
...
is
...
a
...
valve
...
in
...
every
...
other
...
channel,
...
the
...
maximum
...
number
...
of
...
channels
...
being
...
drained
...
by
...
any
...
given
...
valve
...
is
...
two.
...
Applying
...
this
...
equation
...
to
...
two
...
channels
...
gives
...
the
...
calculated
...
value
...
for
...
the
...
idealized
...
size
...
of
...
the
...
valve,
...
which
...
is
...
then
...
rounded
...
up
...
to
...
the
...
next
...
available
...
nominal
...
diameter.
...
For
...
a
...
flocculator
...
that
...
has
...
only
...
two
...
channels,
...
each
...
of
...
the
...
channels
...
will
...
have
...
a
...
valve
...
in
...
it.
...
In
...
this
...
case,
...
the
...
above
...
equation
...
will
...
be
...
applied
...
to
...
a
...
single
...
channel
...
only.
...
Male
...
Adapters
...
The
...
calculated
...
nominal
...
diameter
...
is
...
that
...
of
...
the
...
slip
...
side
...
of
...
the
...
adapter
...
and
...
is
...
used
...
to
...
calculate
...
its
...
corresponding
...
inner
...
and
...
outer
...
diameters.
...
The
...
outer
...
diameter
...
of
...
the
...
slip
...
side
...
is
...
also
...
the
...
inner
...
diameter
...
of
...
the
...
threaded
...
side.
...
The
...
outer
...
diameter
...
of
...
the
...
threaded
...
side
...
is
...
used
...
as
...
the
...
inner
...
diameter
...
of
...
the
...
valve
...
which
...
fits
...
it.
| Wiki Markup |
|---|
\\ {float:left|border=2px solid black} [!sw iso horiz coupling.png|width=600px!|AutoCAD Channel Program] Adapters for Draining the Flocculator {float} \\ h3. Drain Slopes Since the center of the valve is aligned with the floor of the flocculator, slopes are required in |
Drain Slopes
Since the center of the valve is aligned with the floor of the flocculator, slopes are required in the floor of the tank. The slopes have a width equal to the diameter of the valve and a depth equal to half the diameter (placing the center of the valve at-grade) with a slope of 30 degrees. If the distance the slope extends into the channel is longer than the spacing between baffles, the slope would extend through a baffle. To correct this problem, the distance the slope extends into the channel will be set to a distance of 5 cm from the nearest baffle.
| Wiki Markup |
|---|
the floor of the tank. The slopes have a width equal to the diameter of the valve and a depth equal to half the diameter (placing the center of the valve at-grade) with a slope of 30 degrees. If the distance the slope extends into the channel is longer than the spacing between baffles, the slope would extend through a baffle. To correct this problem, the distance the slope extends into the channel will be set to a distance of 5 cm from the nearest baffle.
\\
{float:left|border=2px solid black}
[!horiz floc slopes side by side.PNG|width=1000px!|AutoCAD Channel Program]
Slope in Floor of Flocculator
{float} |
Gate Valves
Gate valves are placed at the base of every other channel in the flocculator at-grade to allow for draining. Additionally, the design requires a drain in the first and last channel of the flocculator, so if there is an even number of channels, the first two channels (the ones closest to the entrance tank) will each have a valve.
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\\ h3. Gate Valves Gate valves are placed at the base of every other channel in the flocculator at-grade to allow for draining. Additionally, the design requires a drain in the first and last channel of the flocculator, so if there is an even number of channels, the first two channels (the ones closest to the entrance tank) will each have a valve. \\ {float:left|border=2px solid black} [!sw iso horiz valves.png|width=1000px!|AutoCAD Channel Program] Valves for Draining the Flocculator {float} \\ \\ \\ \\ |