Schlumberger Private
Centrifugal Pump
Centrifugal Pumps
The term “centrifugal pump” has been used
to describe a wide variety of pumping
applications and designs throughout the
years.
Schlumberger Private
Centrifugal Pump
The REDA centrifugal pump
is a multistage pump,
containing a selected
number (application
Schlumberger Private
dependent) of impellers
equipped with vanes, inside
a closely fitted diffuser,
located in series an axial
shaft, driven by the electrical
motor.
Centrifugal Pump
A centrifugal pump creates pressure by
the rotation of a series of vanes in an
impeller.
Schlumberger Private
The impeller’s job is to transfer energy by
rotation to the liquid passing through it, thus
raising the kinetic energy.
Centrifugal Pump
The diffuser section then converts this energy
to potential energy, raising the discharge
pressure.
Schlumberger Private
Centrifugal Pump
From there, the rotation of
the high-speed impeller
throws the liquid into the
diffuser.
Schlumberger Private
Centrifugal Pumps
Each "stage" consists of an
impeller and a diffuser. The
impeller takes the fluid and
imparts kinetic energy to it. The
diffuser converts this kinetic
energy into potential energy
(head or pressure).
Schlumberger Private
Upthrust Washer
Impeller
Down Thrust Washer
Diffuser
HEAD
• Curves for centrifugal Head: The height
pumps are normally to which the pump
will "lift" the fluid
shown as flow versus
head in feet, meters,
or some other
Schlumberger Private
consistent unit.
Propane Water Oil
Schlumberger Private
• A centrifugal pump produces "constant
head".
– This means that, regardless of the fluid
being pumped, it will be lifted to the same
height as any other fluid for the same flow
rate.
Maximum Head-Capacity
20000
4.5" Casing
15000 5.5" Casing
7" Casing
10000
Schlumberger Private
5000
Total Dynamic Head -Feet
0
0 10000 20000 30000
Flow Rate - BPD (60 Hz)
SN2600 60 HZ / 3500 RPM Pump Performance Curve 538 Series - 1 Stage(s) - Sp. Gr. 1.00
Optimum Operating Range 1600 - 3200 bpd Shaft Brake Horsepower Limit: Standard 256 Hp
REDA Nominal Housing Diameter 5.38 inches High Strength 410 Hp
Shaft Diameter 0.875 inches Housing Burst Pressure Limit: Standard N/A psi
Shaft Cross Sectional Area 0.601 in2 Buttress 6000 psi
Rev. B Minimum Casing Size 7.000 inches Welded 6000 psi
Feet B.E.P. Hp Eff
Q = 2581
H = 46.75
60 P = 1.31 3.00 60%
E = 68.09
50 2.50 50%
40 2.00 40%
30 1.50 30%
Schlumberger Private
20 1.00 20%
10 0.50 10%
0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000
Capacity - Barrels per Day
• From this curve we can determine the head produced, brake
horsepower required and hydraulic efficiency at any flow rate.
Impeller Thrust
An Impeller has three forces acting on it.
The sum of these three forces is the total
thrust.
Schlumberger Private
Cross-Section of a Typical Impeller
Impeller Thrust – Force #1
Gravity: F=mA
Schlumberger Private
F
Is this force downward,
upward or neutral?
Impeller Thrust – Force #2
Pressure: F = Press x Area
High Pressure
Schlumberger Private
Low Pressure
Is this force downward,
upward or neutral?
Impeller Thrust – Force #3
Momentum: F = d(mass) d(velocity)
x velocity + x mass
d(time) d(time)
Schlumberger Private
Is this force downward,
upward or neutral?
Impeller Thrust
Pressure: The downward arrows represent the larger force
due to the higher pressure.
Schlumberger Private
The net difference between the
two forces is the downthrust due to
+ = pressure.
Impeller Thrust
In general, larger diameter impellers will have a
higher downthrust than smaller impellers for the
same flow rate.
Why?
Schlumberger Private
Because they have a larger surface area on which
the pressure difference can operate.
They also have more mass.
Impeller Thrust
Is it possible to affect the downthrust caused by
pressure in any way?
What if we could reduce the pressure on top of the
Schlumberger Private
impeller?
Impeller Thrust
Pressure: If we could lower the pressure on the top of the
impeller as shown, this would reduce the thrust.
Schlumberger Private
+ =
Impeller Thrust
Pressure: By using a "balance ring" between the impeller and
diffuser and drilling "balance holes" in the upper
impeller skirt, we can recirculate lower pressure
fluid over the majority of the upper surface.
Balance Low Pressure
Balance
Ring Hole
Schlumberger Private
High Pressure
Low Pressure Fluid
Schlumberger Private
Efficiency
Types of Losses
Schlumberger Private
Schlumberger Private
Pump Descriptions and Names
The series designations are defined as:
Type Series Outside Minimum
Diameter Casing Size
A 338 3.38” 4 ½”
D 400 4.00” 5 ½”
G 540 5.13” 6 5/8”
S 538 5.38” 7”
Schlumberger Private
H 562 5.63” 7”
J 675 6.75” 8 5/8”
L 738 7.25” 9 5/8”
M 862 8.63” 10 ¾”
N 950 9.5” 11 ¾”
950 10.00” 11 ¾”
P 1125 11.25” 13 3/8”
DN 1300
Pump Descriptions and Names:
• N = NiResist
• R = 5530
• V = Type 4
Schlumberger Private
• Many other letters will be used to discribe
the pump…
Pump Nomenclature:
Frequently Used Terms
Abbreviation Definition
ARZ Abrasion Resistant: Zirconia bushings and sleeves
ARZ-S Abrasion Resistant: Silicon Carbide sleeves
ARZ-SS Abrasion Resistant: Silicon Carbide bushing and sleeves
ARZ-T Abrasion Resistant: Tungsten-Carbide sleeves
ARZ-TT Abrasion Resistant: Tungsten-Carbide bushings and sleeves
ARZ-ZS Abrasion Resistant: Zirconia bushing bushings and Silicon sleeves
ARZ-ZT Abrasion Resistant: Zirconia bushing bushings and Tungsten sleeves
C Compression
CT Center Tandem
C-CT Compression-Center Tandem
C-LT Compression-Lower Tandem
CR Compression Ring
CR-CT Compression Ring-Center Tandem
CR-LT Compression Ring-Lower Tandem
ES Enhanced Stability
FL Floater
Schlumberger Private
FL-CT Floater-Center Tandem
FL-LT Floater-Lower Tandem
FL-S Floater-Single section
HB Hydraulic Balance
HSG Housing
S Single
SS Stainless Steel
SS H and B Stainless Steel Head and Base
CS Carbon Steel
M-Trim Monel Trim
Rloy Redaloy
SLB Self Lubricating bearings (Graphalloy)
HSS High Strength Shaft
Pump naming conventions
DN1400 indicates:
D = 400 series, therefore, 4.0” in diameter
N = the material of the stage, in this case ni-
Schlumberger Private
resist.
1400 = the best efficiency flow rate
(60 Hz : 3500 RPM) in barrels per day.
Pump naming conventions
A D950 indicates:
D = 400 series, or 4.0” diameter
950 = 950 bpd flow rate
Schlumberger Private
“N” is missing from the description so the
impellers are Ryton (thermo plastic)
Centrifugal Pumps
There are two types of impellers that
determine the amount flow available for the
specific design.
Schlumberger Private
Centrifugal Pumps
A radial flow
(pancake) impeller
has vane angels at
close to 90 degree,
Schlumberger Private
and therefore, are
usually found in
pump ranges for
lower flow rates.
Centrifugal Pumps
A mixed flow impeller
has vane angels at
close to 45 degree,
and therefore, are
Schlumberger Private
usually found in
pump ranges for
higher flow rates.
Pump Construction
There are two types of pump stage
construction for ESP oil field applications:
Floater - Type
Schlumberger Private
Compression - Type
2 Types of Stage Construction
Pump
Down Impeller
Thrust Thrust
Compression Carried
here
Floater
Schlumberger Private
Protector
Thrust
Bearing
Motor
Thrust
Bearing
"Compression" Pumps
In a compression pump, all the impellers are rigidly fixed to
the shaft so that if an impeller wants to move up or down, it
will take the shaft with it.
The impeller is normally sitting down on its lower diffuser
during assembly due to gravity. Because of this, the pump
Schlumberger Private
shaft is "raised" with shims in the coupling so that the impeller
is not allowed to touch the diffuser after final assembly. This
allows all thrust developed in the pump shaft to be transferred
to the protector shaft directly.
Pump
Shimming
Impeller is in full down
Schlumberger Private
position
There is a small amount of free play in the
coupling such that the pump shaft can fall
down to where the impellers ride directly on
the lower diffusers or on the downthrust
washers if available.
Pump
Shimming
Add shims so the impeller is
lifted slightly off diffuser.
Schlumberger Private
Shims placed in
coupling to raise
the shaft
Why use Compression Pumps?
• Some stages generate too much thrust to be handled by a thrust
washer in the stage.
• Some fluids (e.g. liquid propane) do not have enough lubricity to
properly lubricate a thrust washer.
• If abrasives or corrosives are present, it may be beneficial to handle
the thrust in an area lubricated by motor oil rather than well fluid.
Schlumberger Private
• Occasionally in very gassy wells, the flow volume changes so
drastically within the pump that parts of a floater pump could be in
very severe thrust while others are not so a compression pump could
be one alternative.
• Since all the thrust is handled in the protector, as long as the
protector has a great enough capacity, the pump operating range can
be extended over a much wider area without any increased wear or
reduced life.
"Floater" Pumps
Why use a floater pump?
Let's look at a floating impeller in detail.
Schlumberger Private
Floating Impellers:
Since a floating impeller is free to move up and down the shaft, the only thing
to stop it is either the upper or lower diffuser. "Thrust washers" are provided
at all mating surfaces between the impeller and diffuser to absorb any thrust
generated.
Schlumberger Private
Thrust
Washers
Floating Impellers:
The blue area shows the "upthrust" washer between
the impeller and upper diffuser.
Schlumberger Private
Upthrust is
absorbed
here
Force
Floating Impellers:
The blue area shows the "downthrust" washers between the
impeller and lower diffuser.
Force
Downthrust
is absorbed
here
Schlumberger Private
Floating Impellers:
Seal here
prevents
abrasives
from getting
Schlumberger Private
into washer
We lose efficiency in the upthrust position because of
the fluid's ability to recirculate from the high pressure
to low pressure eye area. In addition to loss in
efficiency, this can promote erosion in the diffuser in
abrasive fluids.
Schlumberger Private
Why use floater pumps?
• Since each stage handles its own thrust, a very
large number of stages can be put in a pump
without having to worry about protector bearing
capacity.
• Floaters are also very good with mild abrasives
Schlumberger Private
since they prevent material from getting into the
radial bearing area.
• Floaters are much more forgiving in
manufacturing since tolerance stack-up is not a
concern.
• Easier field assembly - no shimming required.
