Thursday 10 March 2011

PUMPS



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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