...
Orifice
...
Size
...
and
...
the
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Dual
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Scale
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Design
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for
...
the
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Nonlinear
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Alum Doser
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Doser \\ !FinalDoser.png|border=2px solid black,align=center,width=500pxpx|align=center,width=500pxpx,height=350pxpx!\\ {center:class=myclass} h5. Figure 1: Doser Overview {center} \\ \\ !Scale.png|border=2px solid black,align=center,width=500pxpx|align=center,width=500pxpx,height=70pxpx!\\ |
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{center:class=myclass}
h5. Figure 2: Close up of nonlinear scale
{center}
\\
h3. |
Abstract:
...
During
...
the
...
fall
...
semester
...
of
...
2009,
...
the
...
Nonlinear
...
Chemical
...
Dosing
...
Team
...
developed
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the
...
dual
...
scale,
...
orifice-based
...
doser
...
in
...
order
...
to
...
be
...
able
...
to
...
deliver
...
both
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turbulent
...
and
...
laminar
...
alum
...
flow.
...
Like
...
its
...
linear
...
predecessor,
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this
...
doser
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must
...
automatically
...
increase
...
or
...
decrease
...
the
...
alum
...
solution
...
to
...
maintain
...
a
...
target
...
dosage
...
set
...
by
...
the
...
operator
...
as
...
the
...
plant
...
flow
...
changes.
...
As
...
an
...
additional
...
feature,
...
the
...
two
...
different
...
scales
...
provide
...
the
...
operator
...
with
...
additional
...
precision
...
through
...
a
...
low
...
dosage
...
(5-25
...
mg/L)
...
and
...
a
...
high
...
(20-100
...
mg/L)
...
alum
...
dosage
...
range.
...
Refer
...
to
...
attached
...
file
...
...
...
...
...
...
for
...
editable
...
files
...
for
...
diagram
...
and
...
dual
...
scale.
...
In
...
order
...
to
...
meet
...
our
...
objectives
...
above,
...
we
...
first
...
researched
...
and
...
identified
...
the
...
nonlinear
...
relationship
...
between
...
plant
...
flow
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rate
...
and
...
alum
...
dosage
...
and
...
the
...
movement
...
of
...
the
...
lever
...
arm.
...
We
...
then
...
utilized
...
this
...
relationship
...
to
...
develop
...
the
...
lever
...
arm
...
design
...
to
...
include
...
the
...
dual
...
scales
...
and
...
the
...
dual
...
orifices.
...
Attached
...
is
...
the
...
...
...
that
...
contains
...
the
...
calculations
...
for
...
our
...
dosing
...
system.
...
As
...
shown
...
on
...
Figure
...
1,
...
our
...
current
...
design
...
consists
...
of
...
a
...
80
...
cm
...
long
...
lever
...
arm
...
with
...
the
...
pivot
...
point
...
in
...
the
...
center
...
and
...
two
...
orifices
...
of
...
2.2
...
mm
...
and
...
1.1
...
mm
...
diameter,
...
3/8"
...
PVC
...
tubing,
...
and
...
other
...
associated
...
hydraulic
...
components
...
listed
...
in
...
our
...
...
There has also been an analysis of the drawbacks of the dual scale and the effect of surface tensionon the dosing schemes. Included in this analysis is the proposition for a submerged orifice and newly designed triple scale doser.
Summary of the Design Process:
In order to meet our design objectives mentioned above, we must link plant flow to alum flow coming out of our doser. We utilized Mathcad's vector calculation ability to help us in our calculations.
Our first step in developing this dosage system was the selection of the orifice to control the flow of alum. We increased the tubing size connecting the constant head tank to the orifice to 3/8" tubing which is wide and smooth enough to make the head loss from the tubing negligible compared to the head loss through each orifice, making the orifice the flow control component for the dosage system.
Head loss through orifices:
| Wiki Markup |
|---|
|^NCDC Component List.xlsx] There has also been an analysis of the drawbacks of the dual scale and the [effect of surface tension|Effect of surface tension]on the dosing schemes. Included in this analysis is the proposition for a submerged orifice and newly designed triple scale doser. h3. Summary of the Design Process: In order to meet our design objectives mentioned above, we must link plant flow to alum flow coming out of our doser. We utilized Mathcad's vector calculation ability to help us in our calculations. Our first step in developing this dosage system was the selection of the orifice to control the flow of alum. We increased the tubing size connecting the constant head tank to the orifice to 3/8" tubing which is wide and smooth enough to make the head loss from the tubing negligible compared to the head loss through each orifice, making the orifice the flow control component for the dosage system. Head loss through orifices: {latex}$$ h_{1Orifice} = K_{DoseOrifice} {{V_{DoseTube}^2 } \over {2g}} $${latex} |
Other
...
Head
...
Losses:
...
Major
...
Head
...
Losses:
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{latex}$$ h_{Lmajor} = f {L\over {D}}{{V^2} \over {2g}} $${latex} |
Entrance
...
Head
...
Loss:
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{latex}$$ h_{1Entrance} = K_{Entrance} {{V^2 } \over {2g}} $${latex} |
The
...
analysis
...
of
...
the
...
head
...
losses
...
in
...
the
...
system
...
can
...
be
...
seen
...
in
...
...
...
.
...
The
...
orifice
...
equation,
...
shown
...
below,
...
demonstrates
...
the
...
nonlinear
...
relationship
...
between
...
flow
...
rate
...
and
...
the
...
change
...
in
...
head
...
loss.
| Wiki Markup |
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{latex}
\large
$$
Q = K_{vc} A_{or} \sqrt {2gh}
$$
{latex} |
Where
| Wiki Markup |
|---|
Where\\ {latex}\large$$Q $${latex} |
=
...
Flow Rate
| Wiki Markup |
|---|
Rate {latex}\large$$h $${latex} |
=
...
Head Loss
| Wiki Markup |
|---|
Loss {latex}\large$$A_{or} $${latex} |
=
...
Area
...
of
...
the Orifice
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|---|
Orifice {latex}\large$$K_{vc} $${latex} |
=
...
Orifice
...
Constant
...
Head
...
loss
...
in
...
the
...
plant
...
after
...
the
...
entrance
...
tank
...
occurs
...
in
...
the
...
rapid
...
mixer,
...
the
...
flocculation
...
tank,
...
and
...
the
...
launders.
...
The
...
flow
...
of
...
water
...
through
...
the
...
AguaClara
...
plant
...
can
...
be
...
effectively
...
represented
...
as
...
a
...
series
...
of
...
flow
...
expansions,
...
a
...
subset
...
of
...
minor
...
losses.
...
.
...
The
...
table
...
below
...
lists
...
the
...
major
...
sources
...
of
...
head
...
loss
...
in
...
the
...
plant.
...
Table
...
1:
...
Head
...
Loss
...
Through
...
the
...
Plant
...
Process | Head Loss |
|---|---|
Rapid Mix Tube | 10 cm |
Flocculator | 13.5 cm |
Launder | 5 cm |
Weir | 5 cm |
Total | 33.5 cm |
The only source of head loss that doesn't have the relationship of head loss proportional to the square of the velocity is the weir at the exit of the plant that controls the plant water level. Because the majority of the head loss is due to minor losses, we can state that the minor loss equation dominates the relationship. Therefore, we can link the flow rate of the plant with the flow rate of alum required for the plant using the same square root relationship mentioned above. In other words, the rise and fall of the water height in the entrance tank caused by the change in flow rate, is nonlinearly proportional to the alum flow of our orifice based doser. Consequently, the lever arm must be long enough to rise and fall with the minimum and maximum water height in the entrance tank. This range is equal to the total head loss in the plant, which is 33.5 cm as shown in Table 1. Therefore, we designed an 0.8 m long lever arm that fits in the 1 m x 1 m entrance tank and that responds to the 33.5 cm water height change.
Refer to Orifice Size and the Dual Scale Design for the Nonlinear Alum Doser Part 2 for the rest of the research on orifice sizing and dual scale design.