Energy Savings from Supplying Drinking Water at Two Pressure Levels - a Retrofit in Las Delicias, El Salvador, EWB-MAP Presented by Adam A. Brostow November 17, 2012
Presented by Adam A. Brostow November 17 , 2012
Jan 03, 2016
Energy Savings from Supplying Drinking Water at Two Pressure Levels - a Retrofit in Las Delicias , El Salvador, EWB-MAP. Presented by Adam A. Brostow November 17 , 2012. Location. Problem. - PowerPoint PPT Presentation
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Energy Savings from Supplying Drinking Water at Two Pressure Levels - a Retrofit
in Las Delicias, El Salvador, EWB-MAP
Presented by Adam A. BrostowNovember 17, 2012
Location
Problem• Las Delicias has an existing drinking water system
that consists of a well, two pumps (submersible and booster), three storage tanks at elevation (one supplied by a spring), and gravity distribution system.
• The village experiences water shortage due to high electricity cost.
• Hoarding water leads to disease. Over 80% of children in the village have parasites which leads to school absenteeism.
• Standing water provides breeding ground for Dengue Fever mosquitoes.
Solution• Our chapter (EWB-MAP) came up with a way
to supply about 30% more water for the same energy consumed.
• About 50% of the population lives below the elevation of ~250’ above the elevation of the well while the tanks are located over 400’ above the elevation of the well.
• The solution is to add another tank at an intermediate elevation and pump to two different pressures.
Hoarding Water
A typical water system
Critical Elevation Diagram, existing system
~ 2 3 0 '
S u b m e r s i b l e p u m p
w e l l
6 ' ' , 6 7 3 0 ' , 7 L B
B o o s t e r p u m p
g r a d ee l . 1 7 4 0 '
3 9 4 '
T a n k 1 ,e l . 2 3 1 0 '
T a n k 3 ,e l . 2 1 8 0 '
3 ' ' , 1 8 7 0 ' , 4 L B
4 ' ' , 1 7 4 0 ' , 4 L B
C r u z e r o ,e l . 1 9 9 5 '
2 5 5 '
2 . 5 ' ' , 3 6 1 0 ' , 7 L Bs p r i n g
1 8 5 '
T a n k 2 ,e l . 2 2 6 0 '
5 0 '1 3 0 '
Idea explored: new tank plus pump
Good for grass-roots design. No space available. Electricity only reaches the existing pumps.
S u b m e r s i b l e p u m p
~ 2 3 0 '
C r u z e r o ,e l . 1 9 9 5 '
w e l l
B o o s t e r p u m p
g r a d ee l . 1 7 4 0 '
3 9 4 '
T a n k 3 ,e l . 2 1 8 0 '
T a n k 1 ,e l . 2 3 1 0 '
2 5 5 '
N e w T a n ks p r i n g
1 8 5 '
1 3 0 '5 0 '
T a n k 2 ,e l . 2 2 6 0 '
Idea explored: another well at higher elevation
Idea explored: pressurized system solution
S u b m e r s i b l e p u m p
B o o s t e r p u m p
~ 2 3 0 '
w e l l
L I C
V F D
r e c y c l e
g r a d ee l . 1 7 4 0 '
3 9 4 '
T a n k 1 ,e l . 2 3 1 0 '
2 6 0 '
P I C
C r u z e r o ,e l . 1 9 9 5 '
T a n k 3 ,e l . 2 1 8 0 '
1 8 5 '
1 3 0 '
Tanks 1 and 3 can still be filled by using a booster pump in the manner it is used now. During filling the lower elevations would get water at higher pressure. After Tanks 1 and 3 are full the isolation valves on the two supply lines are closed and the pump only pressurizes the distribution system at lower elevations. According to EWB Guidelines, a sustainable water distribution system uses gravity to drive the system and has been designed to offer a long service life with little to no maintenance.
Idea explored: tank level control using a float valve
p u m p
P R V
W
H
o
t a n k w i t hf l o a t v a l v e
o p
o p '
There is a float valve in the tank that closes when the tank is full (like in a toilet). When the valve closes the pump gests back-pressured (the operating point goes up on the pump curve). There is a pressure switch high (PSH) on the pump’s electrical controls. It shuts down the pump when the discharge pressure exceeds a certain value. Such scheme completely eliminates the need for an electrical, phone, or radio signal from the tank. The water in the pipe itself conveys the information. The risk is overpressurization of the system.
Critical Elevation Diagram , proposed system
S u b m e r s i b l e p u m p
~ 2 3 0 '
S o c c e r F i l e de l . ~ 1 9 9 5 '
w e l l
B o o s t e rp u m p
V F D
g r a d ee l . 1 7 4 0 '
3 9 4 '
T a n k 3 ,e l . 2 1 8 0 '
T a n k 1 ,e l . 2 3 1 0 '
2 5 5 '
N e w T a n ks p r i n g
1 8 5 '
1 3 0 '5 0 '
T a n k 2 ,e l . 2 2 6 0 '
Proposed booster pump test
S u b m e r s i b l e p u m p
C i s t e r ne x i s t i n g
n e w
p o r t a b l eu l t r a s o n i c
B o o s t e r p u m p
o p e nn e w e x i s t i n g
Modified booster pump test• The ultrasonic flow meter was not charged.• We ran the submersible pump (known flow) to
obtain the so-called strapping chart of the cistern (liquid level vs. volume stored). The cistern has a baffle in the middle but one does not have to know the exact geometry to use a strapping chart.
• We drained the cistern using the booster pump varying the discharge pressure to produce the characteristic (head vs. flow).
Idea explored: liquid level indicator
i n d i c a t o r
t r a n s p a r e n t t u b e
f l o a t
Idea explored: liquid level indicator
Submersible pump
Booster pump
Submersible pump test
Booster pump test
Generic pump characteristics curve
Challenge: pumping system• We have to be able to match the submersible
pump flow and the booster pump flow (they match now at high booster pump discharge head).
• If we run the booster at lower head (pumping to the new tank) the flow will increase. The energy consumed will decrease but (a) the cistern will run dry, (b) the efficiency will decrease.
• Bigger cistern takes care of (a) but not (b).• Solution: Variable Frequency Drive (VFD).
Pump characteristics curve - efficiency
R P M 2 < R P M 1
H
w
R P M 1
o p '
o p
8 5 %8 0 %
7 5 %
Variable Frequency (Speed) Drive
Pump characteristics curve with a VFD
Map of Las Delicias Water System
DOWNHILL
260 Homes Served by Tank 3
33 Homes Served
by Tank 2291 Homes Served by Tank 1
DOWNHILL
Map of current Las Delicias Water System from ADESCO with approx house locations indicated
117 Homes Served by Tan 3
33 Homes Served
by Tank 2
154 Homes Served by Tank 1
Proposed Water Distribution System
280 Homes Served by New Tank
DOWNHILL
Map of Current Water System (section relevant for EWB-MAP modifications)
RED lines – supply lines to tank (uphill by pump)BLUE lines – distributions lines by gravity
DOWNHILL
New 17,000 gallon tank Exisiting
11,000 gallon tank
Challenge: supply/distribution tie-in points
• We have to tie in to the existing supply and distribution system.
• Part of the proposed path is covered with concrete which makes trenching difficult. Can we install the piping above ground? If we do, how can we protects it from the elements and vandalism?
• How to avoid damaging the existing buried pipe while installing the new one?
• How to best connect the distribution system from the two tanks.
Proposed update to Water System (section relevant for EWB-MAP modifications)
RED lines – supply lines to tank (uphill by pump)BLUE lines – distributions lines by gravity
NEW
SUP
PLY
LIN
E 1
NEW DISTRIBUTION LINE 2c
NEW DISTRIBUTIO
N
LINE 2a
NEW
DI
STRI
BUTI
ON
LI
NE
2bNEW TANK
A
B
C
D
E
F
DOWNHILL
1. Tank Construction2. Pipe connections3. Pipeline Plans4. Distribution of Work
Proposed update to Water System (section relevant for EWB-MAP modifications)
RED lines – supply lines to tank (uphill by pump)BLUE lines – distributions lines by gravity
NEW
SUP
PLY
LIN
E 1
NEW DISTRIBUTION LINE 2c
NEW DISTRIBUTIO
N
LINE 2a
NEW
DI
STRI
BUTI
ON
LI
NE
2bNEW TANK
A
B
C
D
E
F
DOWNHILL
1. Tank Construction2. Pipe connections3. Pipeline Plans4. Distribution of Work
Proposed update to Water System (section relevant for EWB-MAP modifications)
RED lines – supply lines to tank (uphill by pump)BLUE lines – distributions lines by gravity
NEW
SUP
PLY
LIN
E 1
NEW DISTRIBUTION LINE 2c
NEW
DI
STRI
BUTI
ON
LI
NE
2bNEW TANK
A
B
C
D
E
F
DOWNHILL
Photos along Pipeline PathArea of Connection to Tubo Madre
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
Photos along Pipeline Path
NEW
SUP
PLY
LIN
E 1
NEW
DI
STRI
BUTI
ON
LI
NE
2b
NEW TANK
A
B
C
D
New Tank schematic
New Tank
New Tank
New Tank
New tank detail
Possible distribution scheme
Possible distribution scheme
Conclusions• If different areas served by the same water
system are located at different elevations it is possible to save pumping energy by pumping to two (or more) different storage pressures.
• Multiple pumps and storage tanks at different elevations can be used in grass-roots design.
• One can just change the backpressure on the pump. The thing to watch for is the pump’s efficiency. A VFD can fix the problem.
• Additional savings come from time-of-day power cost and power factor (VFD takes care of the PF; otherwise, one can use capacitors).
Thank You
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