FACTORS AFFECTING CHOICE OF A PUMP
Many different factors can influence the final choice of a pump for a particular operation. The following list indicates the major factors that govern pump selection.
· The amount of fluid that must be pumped. This factor determines the size of pump (or pumps) necessary.
· The properties of the fluid. The density and the viscosity; of the fluid influence the power requirement for a given set of operating conditions, corrosive properties of the fluid determine the acceptable materials of construction. If solid particles are suspended in the fluid, this factor dictates the amount of clearance necessary and may eliminate the possibility of using certain types of pumps.
· The increase in pressure of the fluid due to the work input of the pumps. The head change across the pump is influenced by the inlet and downstream reservoir pressures, the change in vertical height of the delivery line, and frictional effects. This factor is a major item in determining the power requirements.
· Type of flow distribution. If no pulsating flow is required, certain types of pumps, such as simple reciprocating pumps, may be unsatisfactory. Similarly, if operation is intermittent, a self-priming pump may be desirable, and corrosion difficulties may be increased.
· Type of power supply. Rotary positive-displacement pumps and centrifugal pumps are readily adaptable for use with electric-motor or internal-combustion-engine drives; reciprocating pumps can be used with steam or gas drives.
· Cost and mechanical efficiency of the pump.
Specification sheet for P-1
Objective To pump Naphtha feed stock to the convection section
Type Centrifugal single stage pump
Mass flow rate 12630 kg/hr of Naphtha
Height to which the fluid is to be pumped 9 meters
Pressure to be developed 506 KPa
Density of fluid 830 kg/m3
Viscosity of fluid 0.6 centipoise
By Bernoulli’s equation, total head 0.7 KJ/Kg
Actual horsepower 4.1 KW
Recommended horsepower 4.5 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals
Mechanical
Specification sheet for P-2
Objective To pump boiler feed water to the steam drum of the TLX
Type Centrifugal multi stage pump employing 14 stages
Mass flow rate 16500 kg/hr of Naphtha
Height to which the fluid is to be pumped 7 meters
Pressure to be developed 12.1 MPa
Density of fluid 999.6 kg/m3
Viscosity of fluid 1 centipoise
By Bernoulli’s equation, total head 12.13 KJ/Kg
Head developed per impeller 0.867 KJ/Kg
No. of impellers required 14
Actual horsepower 79 KW
Recommended horsepower 80 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals
Mechanical
Specification sheet for P-3
Objective To pump heavy oil (25°API) to the primary fractionator
Type Centrifugal Single stage pump
Mass flow rate 306610 kg/hr of Naphtha
Height to which the fluid is to be pumped 7.6 meters
Pressure to be developed Slightly above atmospheric
Density of fluid 900 kg/m3
Viscosity of fluid 0.9 mN.s/m2
By Bernoulli’s equation, total head 76.3 KJ/Kg
Actual horsepower 9.25 KW
Recommended horsepower 10 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals Mechanical
Specification sheet for P-4
Objective
To pump light naphtha & water to decanter of water quench tower
Type Centrifugal single stage pump
Mass flow rate 122315 kg/hr of Naphtha
Height to which the fluid is to be pumped 3 meters
Pressure to be developed Slightly above atmosphere
Density of fluid 900 kg/m3
Viscosity of fluid 0.95 centipoise
By Bernoulli’s equation, total head 44 J/Kg
Actual horsepower 1.32 KW
Recommended horsepower 1.5 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals
Mechanical
Specification sheet for P-5
Objective To pump water quench tower
Type Centrifugal single stage pump
Mass flow rate 116160 kg/hr of Naphtha
Height to which the fluid is to be pumped 12 meters
Pressure to be developed Slightly above atmosphere
Density of fluid 998 kg/m3
Viscosity of fluid 1.0 centipoise
By Bernoulli’s equation, total head 132 J/Kg
Actual horsepower 6.1 KW
Recommended horsepower 6.5 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals Mechanical
Specification sheet for P-6
Objective To pump light naphtha reflux to primary fractionator
Type Centrifugal single stage pump
Mass flow rate 6900 kg/hr of Naphtha
Height to which the fluid is to be pumped 11 meters
Pressure to be developed Slightly above atmosphere
Density of fluid 830 kg/m3
Viscosity of fluid 0.6 centipoise
By Bernoulli’s equation, total head 127 J/Kg
Actual horsepower 0.45 KW
Recommended horsepower 0.6 KW
Material of construction
Casing Cast iron
Impeller Hard bronze
Shaft Stainless Steel
Types of seals Mechanical
Specification sheet for P-7
Objective To pump caustic recycle to the caustic scrubbing tower
Type Centrifugal single stage pump
Mass flow rate 16613 kg/hr of Naphtha
Height to which the fluid is to be pumped 10 meters
Pressure to be developed Negligible
Density of fluid 1138 kg/m3
Viscosity of fluid 2.0 centipoise
By Bernoulli’s equation, total head 1432 J/Kg
Actual horsepower 6.7 KW
Recommended horsepower 11 KW
Material of construction
Casing Stainless Steel
Impeller Stainless Steel
Shaft Stainless Steel
Types of seals Mechanical
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