1 cee 426 wastewater treatment plant design november 12, 2012 thomas e. jenkins president jentech...
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CEE 426Wastewater Treatment Plant Design
November 12, 2012
Thomas E. JenkinsPresident JenTech Inc.
6789 N. Elm Tree RoadMilwaukee, WI 53217
J enTec h Inc .
2JCI 12
Water seeks its own level.
My Dad
3JCI 13
Pumping Processes and Design Considerations
What is a Pump? Types of Pumps Pump Curves System Curves Pump System Performance
4JCI 14
What is a Pump?
A pump is a machine to move a fluid from a lower to a higher energy level Pumps produce flow System resistance to flow produces pressure
5JCI 15
Basic Physics:
Continuity Equation:
Always use consistent units1 cu ft = 7.48 gallons
ft/second velocity,
ft area,
second/ft rate, flow2
3
2211
V
A
Q
VAVAQ
6JCI 16
Basic Physics:
Pressure and “Head”
Water = 62.4 lb/cu ft= 0.0361 lb/cu in
One foot head = 0.433 psiOne psi = 27.7 inches water
inches distance, height,
inlbs/cu me,force/volu weight,specific
psi area, force/unit pressure,
h
p
hp
7JCI 17
Basic Physics:
Bernoulli’s Equation(Energy Equation)
In this case all pressures are expressed in feet of head.
The application of Bernoulli’s Equation is used to construct the system energy grade line.
lossesfriction
22
222
2
211
1
f
f
h
g
VpZh
g
VpZ
8JCI 18
Basic Physics:
Theoretical Energy Required to Lift Water is Weight of Water Times the Height .
Power is the Rate of Energy Used Over a Period of Time.
To Pump a Certain Amount of Water Takes More Power If It Is Done Faster, But the Same Energy!
weight
height
W
Z
WZE
feet head,
gpm rate, flow
hp water,pump
power to ltheoretica3960
h
Q
P
hQP
w
w
9JCI 19
Basic Physics:
Actual Pump Power Must Include Efficiency. Power Cost Must Include Pump, Motor, And Drive Efficiency.
0.746hpkW
decimal ,efficiency drive
decimal ,efficiencymotor
decimal ,efficiency pump
feet head,
gpm rate, flow
hp water,pump
power to water towire
3960
d
m
p
h
Q
P
hQP
ww
dmpww
10JCI 110
Types of Pumps
Archimedes Screw
Positive Displacement
Centrifugal
11JCI 111
Archimedes Screw Pumps Date from Ancient Greeks Used for High Volume, Low Lift Internal and External Types
12JCI 112
Positive Displacement (PD) Pumps PD Pumps Move a Fixed Volume for Every
Revolution Many Types
Piston Lobe Gear Progressive Cavity Peristaltic …..
13JCI 113
Positive Displacement Pump Examples
Progressive Cavity
Peristaltic Pump
Usually Used for Slurries, Sludge, Heavy Fluids
14JCI 114
Positive Displacement PumpsFlow for a PD pump is linear with speed, but has a non-zero intercept due to “slip”. Slip is the internal leakage. This may also be expressed as volumetric efficiency.
Discharge pressure will rise to meet system resistance (up to the point something breaks).
PD pumps must always have pressure relief valves on the discharge.
vgallons/re pump, ofnt displaceme
rpm factor, leakage internal
speed rotational
gpm rate, flow
)(
d
slip
rpm
Q
dsliprpmQ
15JCI 115
Centrifugal (Dynamic) Pumps Centrifugal Pumps Convert Kinetic Energy
Into Potential Energy (i.e. Velocity Head Into Static Head)
Most Common Pump in Water and Wastewater
Radial Flow Most Common Axial Flow (Vertical Turbine) For High
Flows
16JCI 116
Centrifugal Pumps Many Types
Single and Double Suction Horizontal and Vertical Split Submersible Close Coupled Extended Shaft…..
17JCI 117
Centrifugal Pumps
Axial (Turbine) Pump
Typical Centrifugal PumpSubmersible Pump
18JCI 118
Centrifugal Pumps Impeller Imparts Kinetic Energy To Water Volute Slows Water, Converts Velocity
Head to Static Pressure (Head)
19JCI 119
Centrifugal Pumps Pump Capability Is Given In Manufacturer’s Performance Curve (Pump Curve)
20JCI 120
Centrifugal Pumps Pump Performance Can Be Controlled By:
Trimming Impeller (Smaller Diameter) Throttling Discharge Variable Speed Operating In Parallel
Same Pressure, More Flow Operating In Series
Same Flow, More Pressure
21JCI 121
Centrifugal Pump Affinity LawsVariable Speed Pumps Are Used To Control Flow and Pressure. Variable Speed Operation Can Provide Significant Energy Savings. Most Effective If Pump Head Is Mostly Friction Losses.
Variable Frequency Drives (VFD) Are the Most Common Method for Variable Speed Control.
kWor hp power,
psior feet head, pump
rpm speed, rotational
gpm rate, flow
3
2
1
2
1
2
2
1
2
1
2
1
2
1
P
h
N
Q
N
N
P
P
N
N
h
h
N
N
Q
Q
22JCI 122
Centrifugal Pump Affinity Laws
2000 3000 4000 5000 6000 7000 8000 9000 10000 110000
20
40
60
80
100
120
140
160
0
40
80
120
160
200
240
280
320
Variable Speed PerformancePump Head 1180 rpm bhp 1180 rpm
Pump Head 1003 rpm bhp 1003 rpm
Flow, gpm
He
ad
, ft.
H2
O
Po
we
r, b
hp
23JCI 123
Centrifugal Pump Performance Pump Operation Cannot Be Determined
From Pump Curve Alone Must Include System Curve Operating Point Is Identified By the Intersection of the Pump Curve and System Curve
24JCI 124
Centrifugal Pump PerformanceThe pump head is the sum of the static head (lift) and the friction losses.
The friction loss can be determined from the Darcy-Weisbach equation or the Hazen-Williams equation. The Hazen-Williams is the most often used in water and wastewater.
pipe encrusted old,for 30
value typical100
pipesmooth new,for 140C
factor C iamsHazen Will
gpm rate, flow
inches pipe, ofdiameter inside
fittingsfor allowance includes
feet pipe, oflength equivalent
OHft friction, from headloss
46.10
2
85.1
87.4
C
Q
d
L
h
C
Q
d
Lh
eq
f
eqf
25JCI 125
Centrifugal Pump Performance Adding System Curve Identifies Actual Pump Performance
2000 3000 4000 5000 6000 7000 8000 9000 10000 110000
20
40
60
80
100
120
140
160
0
40
80
120
160
200
240
280
320
Variable Speed PerformancePump Head 1180 rpm
System Head
bhp 1180 rpm
Pump Head 1003 rpm
bhp 1003 rpm
Flow, gpm
He
ad
, ft.
H2
O
Po
we
r, b
hp
26JCI 126
http://www.pumpsystemsmatter.org/default.aspx
http://www.pumps.org/
Questions?