Transcript Document

SAMPLE SLIDES OF THE 2-DAY SEMINAR FOR
ENGINEERS
As you will notice there are few words on these slides, your trainer will provide
you with his experience which will make these images come alive providing you
with the opportunity to reflect and ask questions, the more the better.
All of the presentation slides are available in a binder supplied with the seminar.
PUMP
SYSTEM ANALYSIS
A BRIEF HISTORY OF PUMPS
A BRIEF HISTORY
France 1600’S
HYDROSTATIC PRESSURE VS. FLUID COLUMN HEIGHT
The weight of a fluid column is:
F  gV  V   z A
since
V  zA
Pressure (p) is equal to the weight of the fluid (F) divided by the surface area (A) at the bottom of the
fluid column:
p 
F
zA

 z
A
A
PRESSURE VS. THE SHAPE OF CONTAINERS
OPEN SYSTEMS AND ENTHALPY
Conservation of energy demands that:
PUMP TOTAL HEAD
The energy balance is:
 W
  E
  K
 E  P
E
Q
E
The specific energy or head balance is
(pF12  pEQ12 )

pP


Subsituting other expressions for head terms:

( p1  p2 )


1
2
2
(v1  v2 )  ( z1  z2 )
2g
1
2
2
H P  H F 12  H EQ12 
(v2  v1 )  z2  H 2  ( z1  H1 )
2g
THE CONTROL VOLUME APPLIED TO A REAL SYSTEM
PRESSURE HEAD ANYWHERE ON THE SUCTION SIDE OF THE PUMP
0
2
2
H P (H F12 H EQ12) 1 (v2 v1 )(z2  H2 (z1  H1))
2g
H X  ( H F 1 X
1
 H EQ1 X ) 
(v12  v X 2 )  ( z1  H1  z X )
2g
NET POSITIVE SUCTION HEAD AVAILABLE (N.P.S.H.)
DEFINITION: NPSH is the head at the pump suction minus the vapor pressure head
What is vapor pressure ?
N.P.S.H. REQUIRED
HOW IS THE N.P.S.H. REQUIRED LEVEL DETERMINED?
SPECIFIC SPEED
Example
NS 
N (rpm)  Q(USgpm) 1750x 500

 1266
H ( ft fluid )0.75
970.75
NPSH REQUIRED CURVES
OPTIMAL SELECTION OF THE IMPELLER DIAMETER AND
PUMP
SYSTEM CURVE
H P (q)  H F (q)  H EQ (q)  H v (q)  H TS
Why increase the impeller diameter when the flow must be increased?
MEASURING TOTAL HEAD
H P  ED  ES
2
ED  H GD  vD  zGD
2g
ES  H GS
2
 vS  zGS
2g
2
2
H P  1 (vD vS ) zGD  HGD (zGS  HGS )
2g
p ( psig ) 2.31
p ( psig ) 2.31
H GD ( ft fluid )  GD
and H GS ( ft fluid )  GS
SG
SG
H P ( ft
fluid) 
( p  pGS )( psi) 2.31
1
2
2
(vD  vS )  ( zGD  zGS )  GD
2g
SG
SOURCES OF INFORMATION ON MOTOR EFFICIENCIES
DATA BASE - MotoMaster
Department of Energy USA (DOE)
Opportunities with higher return
Opportunities in electrical
energy reduction
Possible decrease
in electrical
1. Replace a standard motor with a
high efficiency motor
Typically 1.5 to
5% and as much
as 8%
Replace a standard efficiency motor
with one that meets or surpasses the
NEMA Premium standard
Winning
conditions
consumption 1
When the motors
are defective or
at the end of their
useful life or
when a motor
must be replaced
to accommodate
a VFD.
High efficiency motors
Opportunities with higher return
Opportunities in electrical
energy reduction
2. Install a variable frequency drive
(VFD)
A VFD can adjust the speed of a
motor in response to a variable
demand avoiding the throttling of
control valves or the opening of
recirculation control valves and the
energy losses incurred.
Possible decrease
in electrical
Winning
conditions
consumption 1
Typically 12 to
15% and as
much as 27%
Ideal solution
when the flow
varies between
40 and 60%
6
PUMP
SYSTEMS
Pumps in parallel - Instability
Minimum submergence of the pump inlet
The effect of air (or gas) entrainment in the pump suction
VARIOUS ITEMS
Quick guide
Viscosity
ASME max. pressure allowable
DYNAMIC VISCOSITY
F  K dv
dy
  K dv  1 dv
A dy
A dy
K
  1 dv
 dy
THE EFFECT OF VISCOSITY ON PUMP
PERFORMANCE