Pumps
Pumps
Pumps
PUMPS
Learning Objectives
At the end of this presentation, you will be able to:
What is a Pump?
Pumps are mechanical
equipments that are used to add
energy to a fluid to move it from
one point to another. Because
energy is -the capacity to do work,
adding it to a fluid causes the fluid
to normally flow through a pipe or
rising to a higher level.
API Standard
API 610
Specifications for Overhung pumps (OH), between bearing
pumps (BB), and vertically suspended centrifugal pumps (VS)
API 674
Positive Displacement Pumps – Reciprocating
API 676
Positive Displacement Pumps – Rotary
API 682
Pumps-Shaft Sealing Systems for Centrifugal and Rotary Pumps
Classification of Pumps
HORIZONTAL
BY POSITION
VERTICAL
CENTRIFUGAL
SINGLE STAGE
BY STAGE
VERTICAL TURBINE MULTI-STAGE
DYNAMIC PUMPS
AXIAL SPLIT
BY CASE-SPLIT
SPECIAL EFFECT RADIAL SPLIT
PISTON
RECIPROCATING PLUNGER
DIAPHRAGM
POSITIVE
DISPLACEMENT
GEAR
LOBE
ROTARY SCREW
SLIDING VANE
FLEXIBLE VANE
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
Centrifugal pump converts the kinetic
energy of the fluid to pressure energy
by reducing the velocity in the volute
or diffuser. All centrifugal pump
depends on the centrifugal motion
(force) to operate.
Advantages:
• Simplicity
• Low initial cost
• Uniform flow (non pulsating)
• Small floor space required
• Low maintenance expense
• Quiet operation
• Adaptability (for motor or turbine)
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
continued…
Dis-advantages:
• Not self priming.
• Chances for Stalling.
• Less suitable for volatile
liquids/hot liquids under
atmospheric pressure.
• Less efficiency.
• Cannot handle very viscous
fluid
• For higher pressure, multi-stage
pump is needed which are
complex to construct.
Centrifugal pump
How does it work?
The energy changes occur by virtue of
two main parts, the impeller and volute
or diffuser. The impeller is the rotating
part that converts driver energy into
kinetic energy. The volute or diffuser is
the stationary part that converts the
kinetic energy into pressure energy.
There are two theories, that explain how
it works:
Energy transfer – from the shaft to the
impeller and impeller to the liquid.
Centrifugal pump
There are many classifications of centrifugal pump, one way is by
the position of the shaft:
Horizontal pump – the shaft is normally in a horizontal position. It is
sometimes overhung or placed between bearing design.
Centrifugal pump
Another way to classify a centrifugal pump is by the way how the
casing is separated:
Axial split-case pump – these are horizontally axial split casing pumps,
the casing is split along the horizontal axis of the shaft.
Radial split-case pump – these are radially split casing pumps, the
casing is split along the radius of the shaft.
Balance drum
Centrifugal pump
Casing
The Casings are generally of two types:
Volute and Circular. The impellers are
fitted inside the casings. The casing
gathers the liquid thrown from the
impeller and directs it outside the
discharge port or nozzle.
Centrifugal pump
Volute casing, is a curved funnel
increasing in area to the discharge port .
As the area of the cross-section
increases, the volute reduces the
velocity and increases the pressure of
the liquid. It also helps balance the
hydraulic pressure on the shaft of the
pump, however this is not possible at
lower capacity than the manufacturer’s
recommendation, thus increasing wear
and tear on the seals, bearing and shaft.
Centrifugal pump
Circular casing, have stationary diffusion vanes surrounding the
impeller periphery that convert velocity energy to pressure
energy. Conventionally, the diffusers are applied to multi-stage
pumps.
DIFFUSION VANES
Centrifugal pump
Nozzles
Part of the casing itself which directs the
transfer of liquid from and through the
pipelines. They can be:
Centrifugal pump
Shaft and Sleeve
Used to transfer energy from the motor
to the impeller. Most common shaft
materials are HC steel and stainless
steel. To protect the shaft from
damage , a shaft sleeve can be
installed. It carries the rotating parts of
the mechanical seal.
Bearings
Each shaft is supported by bearings
that supports load along the axis of the
shaft called thrust loads, and loads
along the radius of the shaft , called
radial loads.
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
Stuffing box
Houses the packing / mechanical seal of
the pump.
Packing
Packing is made of woven fiber and some
type of lubricant placed in rings around the
shaft to control the leakage from the
stuffing box, used in non-critical fluids.
Mechanical seal
Provides a more efficient and safe sealing
for hazardous, toxic and inflammable HC
fluids.
Centrifugal pump
Coupling
Couplings are mechanical devices that
form a connection between two
rotating shafts from the driver, and the
driven, transmitting power and torque to
the impeller.
Centrifugal pump
Bearing housing
Encloses the bearings mounted on the
shaft. The bearings keep the shaft or
rotor in correct alignment with the
stationary parts under the action of
radial and transverse loads.
Centrifugal pump
Impeller
The impeller is the main rotating part that provides the centrifugal
acceleration to the fluid. The energy is transferred from the shaft to
the impeller and from the impeller to the liquid. There are three
types of impellers, based on the number of shrouds:
• Closed – has shroud in front and back of the impeller
• Semi-open – has shroud only in the back of the impeller.
• Open – no shroud
Centrifugal pump
continued…
• Open impellers are generally faster and
easier to clean and repair but more
sensitive to wear and tear of the blades.
They are usually used in smaller pumps
and pumps that handle suspended solids.
• Semi-closed impellers are usually used
with liquids or products that have solids.
Reduced efficiency is a common problem
with semi-closed impellers, but the ability
to pass solids is an important trade-off.
• Closed impellers are used primarily in
larger pumps and are commonly found in
clear liquid applications. They don't do
well with solids and are difficult to clean if
they become clogged. They require wear
rings and these wear rings present another
maintenance problem / cost.
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
continued…
Impellers can also be classified by the type of flow:
• Radial Flow: The fluid that enters along the axial plane is accelerated by the impeller and
exits at right angles to the shaft (radially). Radial-flow pump operate at higher pressures and
lower flow rates than axial and mixed-flow pumps
• Axial Flow: Axial-flow pump differ from radial-flow pump in that the fluid enters and exits
along the same direction parallel to the rotating shaft. The fluid is not accelerated but
instead "lifted" by the action of the impeller. Axial-flow pump operate at lower pressure and
higher flow rates than radial flow pump. They are sometimes called propeller type of impeller.
• Mixed Flow: Mixed-flow pump function as a compromise between radial and axial-flow
pump. The fluid experiences both radial acceleration and lift and exits the impeller
somewhere between 0 and 90 degrees from the axial direction. As a consequence mixed-
flow pump operate at higher pressures than axial-flow pump while delivering higher
discharge than radial-flow pump.
Centrifugal pump
Wear rings
With closed impellers, the impeller fits
very close to the case. As a result, the
case is worn by material passing through
the HP to the LP side of the impeller. To
protect the casing and impeller, brass or
stainless steel wear rings are used.
Centrifugal pump
Auxiliary
Auxiliary components generally
include the following piping systems
for the following services:
• Seal flushing
• Quenching system
• Barrier / Buffer fluid system
• Drain and vent piping
• Lubrication and LO cooling
systems
• Pump pedestal cooling systems
• Parameter gauges / meter
• Isolation and relief valves
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
Various forms of axial thrust balancing
• Mechanical: complete absorption of the axial
thrust via a thrust bearing (e. g. plain bearing,
rolling element bearing)
• Design-based: back-to-back arrangement of the
impellers or stages (see Back-to-back impeller
pump) and through the absorption of the residual
axial thrust via a thrust bearing
• Balancing or reduction of the axial thrust on the
individual impeller via balancing holes
• Balancing of the complete rotating assembly via
a balancing device with automatic balancing (e.
g. balance disc and balance disc seat) or partial
balancing via a balance drum and double drum
• Reduction at the individual impeller by back
vanes (dynamic effect)
PUMPS JFVILLONES, M/T (L&D)
Centrifugal pump
Various forms of axial thrust balancing
Double-entry impeller arrangement Sealing clearance and balance hole Pump with back vanes
Centrifugal pump
Various forms of axial thrust balancing
Two opposed sets of two series-coupled impellers Balancing device with balance disc
Two sets of parallel-coupled opposed impellers Balancing device with balance drum and thrust bearing
Classification of Pumps
HORIZONTAL
BY POSITION
VERTICAL
CENTRIFUGAL
SINGLE STAGE
BY STAGE
VERTICAL TURBINE MULTI-STAGE
DYNAMIC PUMPS
AXIAL SPLIT
BY CASE-SPLIT
SPECIAL EFFECT RADIAL SPLIT
PISTON
RECIPROCATING PLUNGER
DIAPHRAGM
POSITIVE
DISPLACEMENT
GEAR
LOBE
ROTARY SCREW
SLIDING VANE
FLEXIBLE VANE
PUMPS JFVILLONES, M/T (L&D)
Reciprocating pump
Reciprocating Pumps operate with a back-and-forth motion, and
consequently have a pulsating or fluctuating discharge. The
reciprocating pump is highly suitable for precise metering
purposes. The close fit tolerances of the piston and cylinder
ensure that very accurate quantities can be measured as they
are pumped. There are three classes of reciprocating pumps:
• Piston pumps
• Plunger pumps
• Diaphragm pumps
Reciprocating pump
Advantages compared to centrifugal
pump:
• Constant volume delivery against a
variable head, or discharge pressure.
• Applicable to variable pressures
without adjustment of speed – a
useful factor where the head is
uncertain.
• Ability to handle highly viscous liquids.
• In most instances are self priming and
therefore able to handle a certain
amount of air or vapor without failing
to pump.
Reciprocating pump
Dis-advantages compared to centrifugal pumps:
• Expensive compared to within the range of centrifugal pump.
• High maintenance cost due to many moving parts.
• Not suitable for dirt or abrasive laden liquids.
• The need to maintain close clearances and valve integrity.
• A high rate of wear is induced by the close fits.
• The materials of construction for these type pumps is limited.
• Reciprocating pumps are generally used for low output at high
pressures.
• Protection against overpressure and power overload is required.
• Reciprocating pumps can cause piping vibrations due to pulsating
pressures.
• Danger of damaging the pump / driver if discharge valve should
closed or pressure relief device should fail.
PUMPS JFVILLONES, M/T (L&D)
Reciprocating pump
Piston pump consists basically of a piston which moves back and
forth inside a cylinder. The movement of the piston, causes the
liquid to alternately fill and be discharged from the cylinder.
Crank Crosshead
PUMPS JFVILLONES, M/T (L&D)
Reciprocating pump
Plunger pumps are single acting.
They have the highest efficiency of
any type of pump.
In a single acting pump, the cylinder
fills with liquid on the inboard stroke
and discharges liquid on the
outboard stroke.
The volume of liquid that discharges
will equal the volume that the plunger
displaces, and is not affected by
leakage around the plunger.
Reciprocating pump
Diaphragm pump, differs from the
piston or plunger-type reciprocating
pump in that the fluid being pumped
is completely isolated from the
reciprocating mechanism by a
diaphragm, thereby eliminating
leakage along the piston rod and
plunger.
Crosshead
The crossheads connect the
connecting rods to the piston rods.
The crosshead is equipped with
shoes which permit it to slide back
and forth within the crosshead
guides.
Piston rod
The piston rods which transmit the
reciprocating motion from the
crossheads to the pump pistons pass
through a packed gland. This gland
is to contain the crankcase oil and
prevent the ingress of any
contamination.
Rotary pump
Rotary pumps, consist of a fixed casing containing gears, vanes,
screws, etc., operating with minimum clearance. Liquid
displacement in rotary pumps is achieved by means of rotating
elements within a casing. The liquid is trapped between the rotors
and the casing and is moved from the inlet to outlet by the rotary
action. Most rotary pumps are self-priming and will, if necessary,
handle entrained gas or air.
Unlike a piston pump, a rotary pump discharges a smooth flow, i.e.
no pulsation. They will handle almost any liquid that is free of hard
and abrasive solids. They can be divided into the following:
• Gear Pump
• Sliding Vane Pump
• Screw Pump
• Lobe Pump
• Flexible-vane pump
PUMPS JFVILLONES, M/T (L&D)
Rotary pump
Advantages:
• A steady output flow as compared to reciprocating pumps.
• Low maintenance in operation.
• Ability to move liquids at very low speeds.
• Ability to handle very viscous liquids such as very heavy hydrocarbons.
• More mechanically efficient than reciprocating pumps.
Dis-advantages :
• Short mechanical life. Unless a very close fit between the rotor and
casing is maintained their volumetric efficiency declines rapidly.
• Unsuitable for handling liquids which may have abrasive solids in them,
since these substances create wear very rapidly in rotary pumps.
Rotary pump
Gear pump
These are the simplest rotary type. As
the gear teeth separate on the
suction side of the pump, liquid fills the
spaces, carried around and squeezed
out as the teeth mesh. The gears may
have single, double-helical, or spur
teeth. They have two types:
• External- gear pump – turning gears
trap fluid between the gear teeth and
casing.
• Internal- gear pump – inside the casing
are two gears, one rotates within the
circumference of the other gear.
Rotary pump
Lobe pump
These resemble the gear-type pumps
in action and have two or more rotors
cut with two, three, four, or more
lobes on each rotor. The rotors are
synchronized for positive rotation by
external gears.
Rotary pump
Screw pump
These have one, two, or three suitably
threaded screws turning in a fixed
casing. A large number of designs are
available for various applications.
Single-screw pumps have a spiral rotor
turning eccentrically in an internal-helix
stator or liner.
Rotary pump
Sliding vane pump
Sliding-vane pumps use vanes that are
held against the casing bore by
centrifugal force when the rotor is
turned. Liquid trapped between two
vanes is carried around and forced out
the pump discharge.
Flexible-vane pump
The operation is similar to sliding vane
pump. However, the vanes are flexible
and sweep fluid rather than forcing it to
move.
Q&A
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