Design of Triplex Plunger Pump

Abdullah Al-JubranAli Al-Qahtani

Haitam Al-Mubarak

Project Advisor: Dr. Emad Tanbour

A Design Project Submitted in Partial Fulfillment of the Requirements for the Course

Assessment III: Graduation Project

College of EngineeringDepartment of Mechanical Engineering

Statement of Purpose

� To design a triplex plunger pump that can bemanufactured using locally available resources and manufacturing techniques

� To practice the application of computer-aided design program in the design of machines

College of EngineeringDepartment of Mechanical Engineering

Table of Contents

� Introduction� Scope of Project� Pumps Classification� Triplex Pump Basics/Concept� Calculations� Crankshaft Diameter� Bearings� Triplex Pump Prototype

College of EngineeringDepartment of Mechanical Engineering

Introduction

Triplex Plunger Pump� Positive Displacement Pump� Three Plungers in parallel� High -Pressure Low -Capacity Application

� hydrostatic testing� water blasting� surface preparation� car washing� pipe and tube cleaning� oil drilling

College of EngineeringDepartment of Mechanical Engineering

Scope of Project

Designing of Triplex Plunger PumpDischarge Pressure: 350 bar (5,076 psi)Flow Rate: 24 li/min (6.3 gpm)

� Crankshaft� Bearings� Material Selection� Fasteners

Making of Digital Prototype

College of EngineeringDepartment of Mechanical Engineering

Design Approach

� Group Brainstorming� Gather Literatures from the web� Design Conceptualization� Identification of Critical Components� Sizing and Strength Calculations� Prototyping by CAD Solidworks

College of EngineeringDepartment of Mechanical Engineering

Triplex Pump Design GANTT Chart

College of EngineeringDepartment of Mechanical Engineering

Positive Displacement Pump versus Centrifugal Pump

Classification Diagram of Displacement Pumps

Classification Diagram of Displacement Pumps

Reciprocating Positive Displacement Pumps

1. Piston Pump 2. Plunger Pump 3. Diaphragm Pump� Higher Pressure � Suitable for Chemicals� Good packing life

� Expensive� Good for slurries � Easier to maintain

Ways to Achieve Reciprocating Motion

1. Crankshaft with crank pin

2. Crankshaft with eccentric sheave or strap

Slider Crank Mechanism

The offset between the shaft center and eccentric sheave center determines the pump stroke

Plunger Pump with Eccentric Sheave

Critical Components

a. Crankshaftb. Eccentric Sheavec. Crankshaft Support Bearingd. Eccentric Sheave Bearinge. Wrist Pinf. Wrist Pin Bearing g. Fluid End Plunger

Design Calculations

Criteria: Displacement: 24 li/minDischarge Pressure: 350 bar# of Plungers: 3

Computation to determine required power

kW = Q × Ptd / 36 × ME

Where Q = delivered capacity, m3/h

Ptd = differential pressure (discharge – suction), barME = mechanical efficiency, %

At 24 liters/minute, 350 bar and typical efficiency of 88%,

(24 liters/min)(60min/hr)(1m3/1000liters)(350bar)

(36×0.88)kW =

kW = 15.91 kilowatts, or 21.33 Hp

Computation to determine Pump Speed and Plunger Spe ed

Q = A × m × n × s × 6× 10-8

Sp = s × n / 30,000

From Pump Handbook, 3 rd edition, pages 3.4, 3.6

Where Q = displacement, m 3/hSp = plunger speed, m/sA = cross-sectional area of plunger, mm 2

M = number of plungersn = rpm of pumps = stroke of pump, mm

Preselected Plunger Bore and Stroke

Plunger Bore Size : 18, 19, 20, 21 and 22 mm

Plunger Stroke : 21, 22, and 23 mm

Plunger Bore, mm Plunger Stroke, mm

Pump Speed, rpm Plunger Speed, m/s

18

21 1,497 1.0522 1,429 1.0523 1,367 1.05

19

21 1,344 0.9422 1,283 0.9423 1,227 0.94

20

21 1,213 0.8522 1,158 0.8523 1,107 0.85

21

21 1,100 0.7722 1,050 0.7723 1,004 0.77

22

21 1,002 0.7022 957 0.7023 915 0.70

Table 1 Pump Speed at Different Plunger Bore and St roke

The obtained plunger speeds above are in accordance with the industry standard

Computation to determine Pump Required TorqueFrom Pump Handbook, 3 rd edition, page 3.8

M = p × 9.549 / nWhere M = pump torque, N·m

n = speed, rpmp = power, W

Plunger Bore, mm Plunger Stroke, mm

Pump Speed, rpm Torque, N·m

1821 1,497 10222 1,429 10623 1,367 111

1921 1,344 11322 1,283 11823 1,227 124

2021 1,213 12522 1,158 13123 1,107 137

2121 1,100 13822 1,050 14523 1,004 151

2221 1,002 15222 957 15923 915 166

a. Calculation to Determine Crankshaft Diameter

a. Calculation to Determine Crankshaft Diameter

Where D = shaft diameter, mmKt = shock and endurance factor applied to computed twi sting

moment (Table 14-2 Machine Design Data Book, 2 nd ed. page 14.18)

Mt = twisting moment or torque, N·mτyd = design yield stress, Pa

From Machine Design Data Book, 2 nd edition, page 14.3

16

πτyd

Kt × MtD =⅓× 1000

For rotating shafts with dynamic load, dynamic effe ct taken indirectly into consideration

The diameter of shaft subjected to simple torsion

From Machine Design Data Book, 2 nd edition, page 14.18

Using AISI 1020 steel which has a yield strength of about 206 MPa, and using a design factor of 1.5,

τmax = 206 MPa × 10^6 Pa/MPa(2 × 1.5)

τmax = 68,666,666 Pa

From Shigley's Mechanical Engineering Design, 8 th Edition, page 212

τmax = Sy / 2n

Where τmax = maximum shear stress, PaSy = yield stress, Pan = design factor

163.1415 × 68,666,666

1.5 × MtD =⅓

× 1000

Plunger Bore, mm

Plunger Stroke, mm

Pump Speed, rpm

Pump Torque, Nm

Computed Shaft

Diameter, mm

1821 1,497 102 22.422 1,429 106 22.823 1,367 111 23.1

1921 1,344 113 23.322 1,283 118 23.623 1,227 124 24.0

2021 1,213 125 24.122 1,158 131 24.423 1,107 137 24.8

2121 1,100 138 24.922 1,050 145 25.323 1,004 151 25.6

2221 1,002 152 25.622 957 159 26.023 915 166 26.4

Table 1: Computed Shaft Diameter at Different Plung er Bore and Stroke

b. Calculation to Determine Eccentric Sheave Diamet er

Sd2 = (s/2) + (D/2) + sw

Where Sd = eccentric sheave diameter, mms = plunger stroke, mmD = shaft diameter, mmsw = minimum sheave width, mm

- pre-selected to be 4.7625 mm (3/16 inch) to facili tate easywelding of the eccentric sheave to the shaft

Plunger Bore, mm

Plunger Stroke, mm

Computed Shaft Diameter, mm

Ecc. Sheave Diameter, mm

1821 22.4 53.022 22.8 54.323 23.1 55.7

1921 23.3 53.822 23.6 55.123 24.0 56.5

2021 24.1 54.622 24.4 56.023 24.8 57.3

2121 24.9 55.422 25.3 56.823 25.6 58.2

2221 25.6 56.222 26.0 57.623 26.4 59.0

Table 2: Eccentric Sheave Diameter at Different Sha ft Size

c. Calculation to Determine Strength of Eccentric S heave Weldment

Stresses in welded joints in torsion

τ" = Mr / J

Where τ” = shear or torsional stress, PaM = torsional moment, N·mr = distance from the centroid of the weld group to the point in the weld

of interest, mJ = second polar moment of area, m 4

For circular fillet welds

Ju = 2 × π × r3

The distance from the centroid of the weld group to the point in the weld of interest, r, can be taken as the radius of the shaft.

The force exerted by the plunger

Fp = Pressure × Plunger Cross-Sectional Area

Example, 22mm plunger bore

Fp = (350 bar) × (100KPa/bar) × (1000Pa/Kpa) × (1N/m2/Pa) × π ×(22mm/1000mm/m) 2/4

Fp = 13,304 N

Maximum moment = Fp × (stroke/2). For 23mm stroke,

M = 13,304 N × (23mm/1000mm/m) ÷ 2

M = 153 N·m

J = 0.707hJu

By using the results above, the stress on the 3/16 inch fillet weld can be calculated.

(153Nm)(27mm/1000mm/m) ÷2

(0.707)(3/16in.)(1m/39.37in.)(2 ×3.1415)((27mm/1000mm/m) ÷2)3τ" =

τ" = 39,682,448 N/m2 or 39.7 MPa (5.473 ksi)

c. Calculation to Determine Crankshaft Bearing

Bearing Catalog Load Rating

C10 =1/a

FDLDnD60

LRnR60

Where C10 = catalog load rating, kN

FD = desired radial load, kNLD = desired life, hoursnD = desired speed, rev/minLR = rating life, hoursnR = rating speed, rev/mina = constant; a = 3 for ball bearings, a = 10/3 for roller bearings

For most bearing manufacturers LRnR60 = 106

C10 =1/a

FDLDnD60

106

Forces acting on the crankshaft bearing

Total maximum force acting on the bearing

Fb1 = 12

Fp2 + 34

Fp1

Fb1 = 54

Fp

Where Fp = Pressure × Plunger Cross-Sectional Area

Fp = (350 bar) × (100KPa/bar) × (1000Pa/Kpa) × (1N/m2/Pa) × π ×(bore in mm/1000mm/m) 2/4

= Fbmax

Plunger Bore, mm

18 19 20 21 22

FP, k·N 8.91 9.92 11.0 12.12 13.30

Fbmax 11.13 12.40 13.74 15.15 16.63

Table 3: Maximum Bearing Load at Different Plunger Bore Sizes

Plunger Bore, mm18 19 20 21 22

FP, (kN) 8.91 9.92 11.0 12.12 13.30Fbmax, (kN) 11.13 12.40 13.74 15.15 16.63nD, (rpm) 1,497 1,344 1,213 1,100 1,002

LD, (hours) 5,000 5,000 5,000 5,000 5,000C10, (kN)

(ball bearing) 85.25 91.64 98.12 104.71 111.40

C10, (kN)(roller bearing) 69.55 75.03 80.61 86.31 92.11

Computed Shaft Dia, (mm) 23.1 24.0 24.8 25.6 26.4

Std. Shaft Dia., (mm) 25 25 25 30 30

AvailableBearing - - - - -

Table 4: Shaft Bearing Load Rating

Plunger Bore, mm18 19 20 21 22

FP, (kN) 8.91 9.92 11.0 12.12 13.30Fbmax, (kN) 11.13 12.40 13.74 15.15 16.63nD, (rpm) 1,497 1,344 1,213 1,100 1,002

LD, (hours) 5,000 5,000 5,000 5,000 5,000C10, (kN)

(ball bearing) 85.25 91.64 98.12 104.71 111.40

C10, (kN)(roller bearing) 69.55 75.03 80.61 86.31 92.11

Computed Shaft Dia, (mm) 23.1 24.0 24.8 25.6 26.4

Initial Std. Shaft Dia., (mm) 25 25 25 30 30

Adjusted Std. Shaft Dia., (mm) 30 30 30 30 30

AvailableBearing, SKF

NU 2306NJ 2306

NU 2306NJ 2306

NU 2306NJ 2306

- -

Table 4: Shaft Bearing Load Rating

Available SKF Bearing for the crankshaft

Plunger Bore, mm18 19 20

FP, (kN) 8.91 9.92 11.0nD, (rpm) 1,497 1,344 1,213

LD, (hours) 5,000 5,000 5,000C10, (kN)

(ball bearing) 68.20 73.31 78.50

C10, (kN)(roller bearing) 55.64 60.02 64.49

Eccentric Sheave Internal Dia., (mm) 30 30 30

Eccentric Sheave Outside Dia., (mm) 60 60 60

Available Bearing, SKF

NKIS 60NA 4912

NKI 60/35

NKIS 60NA 4912

NKI 60/35

NKIS 60

Table 5: Eccentric Sheave Bearing Load Rating

e. Pump Driver Selection

e. Pump Driver Selection

e. Pump Driver Selection

Manufacturer Hp Speed, rpmEfficiency,

%Cost, $ Cat. No.

GE25 1,200 91.7 2,312 S279

25 1,200 93.0 2,800 M7549

Baldor 25 1,200 93.0 5,090 ECP4111T

Siemens 25 1,200 91.7 2,4801LE29313AC116AA3

TECO Westinghouse

25 1,200 91.7 3,438 N0256

25 1,200 93.0 4,456 EP0256

25 1,200 93.0 4,635 HH0256

Table 6: List of Applicable Drive Motors

e. Pump Driver Selection

Manufacturer Hp Speed, rpmEfficiency,

%Cost, $ Cat. No.

GE25 1,200 91.7 2,312 S279

25 1,200 93.0 2,800 M7549

Baldor 25 1,200 93.0 5,090 ECP4111T

Siemens 25 1,200 91.7 2,4801LE29313AC116AA3

TECO Westinghouse

25 1,200 91.7 3,438 N0256

25 1,200 93.0 4,456 EP0256

25 1,200 93.0 4,635 HH0256

Table 6: List of Applicable Drive Motors

Plunger Bore,mm

Plunger Stroke, mm

Speed, rpm Remarks

18

21 1,497Disregarded. Motor speed is only1,200 rpm.

22 1,429

23 1,367

19

21 1,344Disregarded. Motor speed is only1,200 rpm.

22 1,283

23 1,227

20

21 1,213 Disregarded. Motor speed is only 1,200 rpm

22 1,158 Selected Plunger Bore & Stroke

23 1,107 Disregarded. Not optimal.

21

21

Disregarded. No crankshaft bearing available.22

23

22

21

Disregarded. No crankshaft bearing available.22

23

Selected Plunger Bore and Stroke

Since the standard shaft diameter chosen is 30mm, a nd the eccentric sheave diameter is 60mm, the minimum sheave thickne ss, sw, is recalculated.

Sd2 = (s/2) + (D/2) + sw

From

sw =Sd - s - D

2

sw =60 - 22 - 30

2= 4 mm

f. Calculation to determine wrist pin size

AISI 1030 steel is chosen because of higher yield s trength than AISI 1020 steel.

Based on maximum shear stress theory, the maximum a llowable shear stress,

τmax = Sy / 2n

Where the yield strength, Sy, for 1030 steel is equal to 260 Mpa. Using a design factor of 1.5,

τmax = 260 / (2×1.5) = 86.7 Mpa

f. Calculation to determine wrist pin size (cont’d)

Wrist pin will fail by shearing on sections a and b .

τmax = Fp / (Aa + Ab)

But since the cross-sectional area of the wrist pin is the same, therefore Aa=Ab, then,

Where A = cross-sectional area of wrist pin.

τmax = Fp / 2A = Fp ÷ 2(πdw2/4) ; dw = wrist pin diameter

By transposing the equation above

dw = (4Fp/2π τmax)1/2

4×11kN×1000N/kN

2×3.1415×86.7Mpa×106Pa/Mpadw =

dw = 0.00899m or 8.99mm

The next preferred size is chosen which is 10 mm.

g. Computation to determine the wrist pin bearing

The bearing size is selected based on the static loa d rating, C0, because the wrist pin

Basic static load rating C0

a. makes a slow oscillating or alignment movements u nder loadb. rotates under load at very low speed

C0 = S0 P0

Where C0 = basic static load rating, k·N

P0 = equivalent static bearing load, k·N

S0 = static safety factor

Based on SKF guideline, for non-rotating roller bea ring with normal operations, S0=1. Since P0=11kN, then

C0 = 1×11k·N

C0 = 11k·N

From SKF catalogue, a drawn cup needle roller beari ng with C0=11.4k·N is available. The bearing designation is HN1010.

h. Bill of Materials

Item Description Specifications Quantity1 Crankshaft 30 mm O.D., AISI 1020 steel 1

2Crankshaft Suppport Bearing

SKF NU 2306 or NJ 2306 2

3 Eccentric Sheave 60 mm I.D., AISI 1030 steel 34 Eccentric Sheave Bearing SKF NKIS 60 35 Wrist Pin 10 mm O.D., AISI 1030 16 Wrist Pin Bearing SKF HN 1010 17 Motor GE M7549 1

j. Triplex Pump Solidworks Digital Prototype

j. Triplex Pump Solidworks Digital Prototype

j. Triplex Pump Solidworks Digital Prototype

j. Triplex Pump Solidworks Digital Prototype

i. Triplex Pump Solidworks Digital Prototype

j. Triplex Pump Solidworks Digital Prototype