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CHAPTER 4: PUMPS & PUMPING SYSTEM - Coggle Diagram
CHAPTER 4: PUMPS & PUMPING SYSTEM
Introduction
Pumps is a mechanical device used to
add energy to a liquid
in order
to move it from one location to another
.
Pumps are used to keep the fluid mechanics in a useful way in a fluid system.
Pumps are not needed to transfer the liquid (gravity flow) in some situation.
Main components of a pumping system:
Piping
Valves
Prime movers
End-use equipment
Pumps
Types of Pumps
Dynamics
Centrifugal
Used in chemical plant & refineries
Basic Operation:
Operates on the principle of centrifugal force
Spinning impellers inside a shell casing propels liquid outwards
Advantages
More cheaper
Less maintenance & space
Constant head pressure
Disadvantages
Respond poor to viscous material
Main components:
1) Impeller
Circular metallic disc attached to the shaft with a built-in passage for the flow of fluid
Type of impeller:
1) Closed
2) Semi-open
3) Open
Made from:
Bronze
Polycarbonate
Cast iron
Stainless steel
2) Shaft
Transfer the torgue from the motor ro the impeller during the start up & operation of then pump
5) Casing
To enclose the impeller at suction & delivery ends
To provide a supporting & bearing medium for the shaft & impeller
4) Gland
Two pieces of metal at the back to support packing
3) Packing
Composed fiber & graphite to control leakage
6) Suction
Inlet where the fluid enters
7) Wear rings
Minimize leakage between the internal discharge & suction
8) Volute
Gathers the water thrown from impeller
9) Discharge
Outlet where the fluid comes out
Design
Vertical
Refer to shaft position
Horizontal
Single-stage
Refer to the number of impellers
Multi-stage
Axial
Can be mounted vertically and horizontally
Frequently found in pipeline services and as primary transfer device on loop reactors
Consists of propeller(in axial impeller) in a pipe in which the propeller can be driven directly by motor or engines.
Design pressure
Design to accelerate & transfer fluid un axial (straight line)
Design temperature
Main components
:
1) Propeller
2) Mechanical seal
3) Trust and radial bearings
4) Coupling
5) Driver
Accelerate liquids axially or centrifugal
Operates at high speed to generate flow rate at low discharge pressure
Used in high volumes are required
Positive displacement
Rotary
Types of rotary pumps:
3) Internal Gear
Operates with only 2 moving parts: a power gear driving & internal ider geat
Internal gear pumps require very little maintenance
Material:
Stainless steel
Carbon steel
Cast iron
4) Sliding vane
Consists of vane attached to a rotor, or impeller that rotates inside an oversized circular casing
Used with the process liquids that have good lubricating qualities
Basic Operation:
As the rotor rotates, liquis is swept into the vane slots
Small cavity is formed inside the pumping chamber that the vane extend into
As the liquid nears the discharge port, it is compressed and released at the discharge port.
2) External Gear
Have 2 gears that rotates parallel each other
One of the gear is idler gear & the other is attached to a driver and is referred to as power gear
The rotation of the driver gear turns the idler gear, trapping fluid & displacing it
The discharge of an external gear pump remains constant unless the shaft speed is changed.
5) Flexible vane
Rotor is composed of a soft elastomer impeller
Speeds are typically low
Frequently used in vacuum service
Basic operation:
Vacuum is created in the suction side that enlarges the volume between the blades ad this causes the product suction
The rotor is spinning and the product is carried from the suction side to the discharge side
1) Screw Pumps
Basic Operation:
These cavities/voids progress axially from the suction casing to the discharge outlet
During operation, the cavities/voids fill with water
When rotor turns, cavities/voids, are formed between the rotor & the stator.
This type of pumps is used for heavy/viscous fluid. Solid content of the process fluid does not affect the effectiveness of the pump
6) Lobe pump
Have 2 rotating lobe-shaped screw
Both lobes do not touch with each other during the operation
Basic Operation:
The pumping action of the lobes moves the fluid in 2 steams around the lobes in the close space between the casing and lobes
The streams combine at the discharge port
Reciprocating
Types of reciprocating pumps:
2) Piston pumps
Use a piston and a back-and -forth motion to displace fluid
Basic Operation:
When the piston pulls out the cylinder, it creates a low-pressure vacuum in the cylinder, causing the discharge valve to close and the suction line to open, filling the cylinder.
When the piston pulls in the cylinder, the suction valve close, amd the fluid is forced out the discharge valve
3) Plunger pumps
Advantages: Components in this pump can be replace without major breakdown of equipment
Operate with back-and-forth motion & a device called a plunger to displace controlled amount of liquid.
1) Diaphragm pumps
Use flexible sheet (diaphragm) to displace fluid
Can be used to pump a variety of chemicals
Basic Operation:
As the eccentric wheel starts the rotation, the diaphragm connecting rod goes up & down.
This reciprocating motion creates a pumping action that displace fluid.
Transfer liquid using a rotary motion that displace liquid on each rotation/stroke
Used in condition where relatively small but precise volumes are required
Factors that influence the choice of pump
The head against which the liquid is to be pumped
The nature of the liquid to be pumped
The quality of liquid to be handled
The nature of power supply