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20. MUD PUMPS

INDEX

HIGH PRESSURE MUD PUMPS20.1 PRINCIPLES20.2 NOMENCLATURE20.3 TYPES AND CHARACTERISTICS20.4 ACCESSORIES20.5 FLOW RATE AND EFFICIENCY CALCULATION20.6 POWER AND EFFICIENCY CALCULATION

LOW PRESSURE MUD PUMPS (Centrifugal Pump)20.7 FUNCTION20.8 NOMENCLATURE20.9 PUMP PERFORMANCE CURVES

HIGH PRESSURE MUD PUMPS20.1 PRINCIPLES

- Duplex Pump / Triplex pump

Hi-pressure mud pumps:

In a Duplex Pumpthepiston discharges mud onone side of the piston and atthe same time takes mud in

on other side.

In a Triplex pumpthepiston discharges mud onlywhen it moves forward inthe liner.

In the Oilfield, duplexpumps have been replacedby triplex pumps.

Triplex pumps of the same

power, are smaller andlighter than duplex pumps.

They also provide anuniform flow.

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20.2 NOMENCLATURE

Pistons are moved with a shaft byan electrical engineor a dieselengine.

The pumpis divided in 2 parts:

- POWER END

- FLUID END

POWER END

- POWER END Schematic 1

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- POWER END Schematic 2

- POWER END Schematic 3

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FLUID END

- FLUID END Schematic 1

- FLUID END Schematic 2 - Fluid end type " L"

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20.3 TYPES AND CHARACTERISTICS

Performance Data

- NATIONAL OILWELL 10-P-130

- NATIONAL OILWELL 12-P-160

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- NATIONAL OILWELL 14-P-220

- Type P Mud Pump Specification and Dimensions

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20.4 ACCESSORIES

- Pulsation Dampeners- Pressure Relief Valve (Safety Valve)- Pump Stroke Counter

Accessories

Pulsation Dampeners

- Function

Alternating movement of thepistons produces an irregular flux(See right).

Pulsation dampener reducesvibrations of pumps and lines(See right).

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- Installation examples

- Pulsation dampener on discharge line - Pulsation dampener on suction line

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- PULSATION DAMPENER HYDRIL TYPE K

- Characteristics

Pulsation Dampeners areusually installed on dischargeline.

It is a bottle with a diaphragminside and pre-charged withNitrogen at maximum 1000psi.

It absorbs pressure variations,reduces peak pressures,permits slightly higher pumpoutput and increases discharge

line life.

- Movement and Components

- Diaphragm movement duringoperation

- Diaphragm section - Diaphragm

- Pressure Relief Valve

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20.5 FLOW RATE AND EFFICIENCY CALCULATION

- Theoretical Flowrate

where

Pt = theoretical flow rate (l/min)D= Liner diameter in mmL = Length of stroke in mmVliq = Output volume per strokeSPM = strokes per minute

- Efficiency

Real flow rate must be calculated with the pump efficiency, which varies according to the state ofthe valves, the supercharging and the type of fluid.

In the best case it is 0.98 for a supercharged triplex pump.

Usually a normal average is between 0.95 - 0.97

20.6 POWER AND EFFICIENCY CALCULATION

- Hydraulic Power Calculation

wherePt = Real Flow rate (theoretical flow rate x efficiency)HHP = Hydraulic power in HPP = output pressure in kg/cm2

- Mechanical Horse Power :

- Efficiency Real flow rate must be calculated with the pump efficiency.Usually efficiency is between E = 0.95 - 0.97