pump on ship

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Pumps

Sistem Dan Permesinan Kapal

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References:

Centrifugal Pump Handbook ’third edition’ Winterthur,

Switzerland, Sulzer Pump Ltd Handbook of pumps & Pumping, Brian Nesbit, Elsevier

Science & Technology books

Pump Handbook ”third edition” McGraw Hill

Pumps System ‘Energy Efficiency Ref. Guide”, CEATY

International

Introduction to Marine Engineering

Marine Auxiliary Machinery

Maritime Engineering Reference Handbook


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Introduction

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Pumps : sebuah alat yang berfungsi

untuk menambah energy ke suatu

cairan atau yang menyebabkan

penambahan tekanan dan

memungkinkan terjadinya gerakan dari

fluida tersebut

Energi yang ditambahkan oleh pompake fluida yang lewat dinamakan total

head

Pumps Functions

Transfer liquid

Circulate liquid

Components of apumping system

are:

Pumps

Prime movers

Piping Valves,

Other fittings,controls andinstrumentation

End-useequipment,


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Head atau energy per-unit

mass flow rate fluidaumunya terdiri dari

Pressure head karena

gaya per-unit area fluida

Dynamic / velocity head

yang diukur dari energy

keinetik fluida Potential atau static head

karena ketinggian cairan


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Bernoulli Equation

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Flow rate depend on friction

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General Pumping Fundamental

Pressure is needed to

pump the liquid through

the system at a certain

rate. This pressure has to

be high enough to

overcome the resistance of

the system, which is also

called “head”. The totalhead is the sum of static

head and friction head.

Static head

Static head is the

difference in height

between the source and

destination of the

pumped liquid

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Static head consists of:

Static suction head (hS): resulting from lifting

the liquid relative to the pump center line. The

hS is positive if the liquid level is above pumpcenterline, and negative if the liquid level is

below pump centerline (also called “suction lift)

Static discharge head (hd): the vertical distance

between the pump centerline and the surface of

the liquid in the destination tank

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Friction head:

This is the loss needed to overcome that is caused by the resistance to flow in

the pipe and fittings.

It is dependent on size, condition and type of pipe, number and type of pipe

fittings, flow rate, and nature of the liquid.

In most cases the total head of a system is a combination of static head and friction head

Total head = Static head + friction head

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Pump performance curve :

The head and flow rate determine the performance of a pump.

The figure shows a typical curve of a centrifugal pump where the headgradually decreases with increasing flow.

As the resistance of a system increases, the head will also increase.

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Typical characteristic curve of centrifugal pumpTypical characteristic curve of

rotodynamic & positive displacement pump


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Pump Operating Point

The rate of flow at a certain head is called the duty point. The pump performance

curve is made up of many duty points.

The pump operating point is determined by the intersection of the system curveand the pump curve

The Best Efficiency Point (BEP) is the pumping capacity at maximum impeller

diameter, in other words, at which the efficiency of the pump is highest. All points

to the right or left of the BEP have a lower efficiency

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Pump efficiency & diameter of pumpCombined pump & system curve


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Reynolds Number

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Head loses in straight pipe

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Head loses in fitting

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+ + + =

+

+ +

+

Total Head Pompa (hp)


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Net Positive Suction Head


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Pump connected


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Contoh: Karakteristik Unjuk kerja pompa sentrifugal


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Selecting the right pump

Oversized pump

Requires flow control(throttle valve or by-passline)

Provides additional head

System curve shifts toleft

Pump efficiency isreduced

Solutions if pump alreadypurchased

Variable Speed Drives ortwo-speed drives

Lower RPM

Smaller impeller

The Best Efficiency Point (BEP) is the pumping capacity at maximum impeller diameter,

in other words, at which the efficiency of the pump is highest.

All points to the right or left of the BEP have a lower efficiency.

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Developed

Head

Impeller

Diameter

Efficiency

Flow Rate

NPSH

Horsepower

http://capsicum.me.utexas.edu/ChE354/resources.html

Pump Performance Curves


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Calculate the pipe loss in a 2 meter pipe with the diameter

d=32 mm and a flow of Q = 10 m³/h

The pipe is made of galvanized steel with a roughness of 0.15,

and the fluid is water at 20ºC.

Contoh

Soal 1

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Contoh

Soal 2

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Unit Penggerak Pompa

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Umumnya unit penggerak pompaterdiri dari 3 jenis penggerak

Motor bakar

Motor listrik

turbin

Yang menjadi pertimbangan dalam

memilih penggerak pompa adalah

efisiensi tenaga pembangkit,

transmisi bahan bakar ke penggerak

pompa,

mudah pemeliharaannya,

beaya bahan bakar, modal,

flexibility ,

independensi operasi, dan

pengawasan.

Penggerak tipe motor bakar danturbin sangat tidak ekonomis untuk

perencanaan pompa karena

konstruksinya berat, besar dan

memerlukan system penunjang

misalnya pelumasan, pendinginan dan

pembuangan gas hasil pembakaran Sistem penggerak motor listrik lebih

sesuai dimana konstruksinya kecil dan

sederhanan sehingga dapat

digabungkan mejadi satu unit kesatuan

dalam rumah pompa


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Dasar-dasar Pemilihan Pompa

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Didasarkan pada system ekonomisnya,yakni keuntungan dan kerugian jika

pompa tersebut digunakan dan dapat

memenuhi kebutuhan pemindahan

fluida sesuai dengan kondisi yang

direncanakan.

Yang perlu diperhatikan dalampemilihan jenis pompa adalah fungsi

terhadap instalasi pemipaan, kapasitas,

head, viskositas, temperature kerja dan

jenis motor penggerak.

Kondisi yang diinginkan dalamperencanaan

Kapasitas dan head pompa harus

mampu dipenuhi.

Fluida yang mengalir secara

kontinu.

Pompa yang dipasang padakedudukan tetap.

Konstruksi sederhana

Menmpunyai effisiensi yang tinggi

Harga awal relative murah juga

perawatannya


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Selection & Application ofpump

Fluid Properties

• pH, operating T, SolidConcentration,specific gravity,vapour P, viscosity,

End use requirement

• Design pump capacity

• End use processrequirement

• Total system head

Environmental factor

• Ambient T, humidity,operating P

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Pompa displasment

Cair an atau gasdipindahkan dari

pengisapan ke

pengeluaran dengan

variasi mekanis volume

dari sebuah ruang atau

beberapa ruang(chamber ).

Pompa Sentrifugal

Aliran melewati pompa

disebabkan oleh gaya

sentrifugal yang

diberikan ke cair an

dengan putaran sebuah

impeller atau beberapa

impeller .

Klasifikasi Pompa


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Pengeluaran berbanding

langsung dengan kecepatan

Pengeluaran sedikit berkurang

saat tekanan bertambah,

biasanya akan lebih banyak slip

pada fluida yang encer (less

viscous)

Pompa dibuat dengan tekanan

pengeluaran sama dengan

hambatan yang muncul,

mengabaikan kecepatan

Pompa ini adalah self priming

Displacement


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Screw pump

Rotary piston pump

Peristaltic pump

A vacuum is created by the rollerscompressing the hose and moving

along

Liquid is drawn into vacuum

Rollers capture liquid between

them and move liquid towards

discharge

Displacement - Rotary Pump


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Vane pump

Not suitable for high viscosity products

Such liquids include LPG, ammonia, solvents, alcohol, fuel oils, gasoline, and

refrigerants.

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Lope pump

Lobe pumps can handle solids.

A gentle pumping action minimizes product emulsification.

Can operate dry for brief periods of time.

Can handle viscous products

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External gear pumps (below) come in

single or double configurations. Handle viscous and watery-type

liquids.

Reduced speeds with high-viscosity

liquids results in greater efficiency.

Two gears come into and out of mesh

to produce flow. Uses two identical gears rotating

against each other.

gear pump

For each revolution of an internal gear

pump, (below) the gears have a fairly

long time to come out of mesh

allowing the spaces between gear

teeth to completely fill and not

cavitate.

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Displacement - Reciprocating Pump


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Piston, Plunger Pump

All reciprocating pumps (and some rotary pumps) depend on check valves (sometimes

Known as non-return valves)

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Diaphragm pump

perfect sealing

high mechanical efficiency,

since flexing a diaphragm

involves much less friction

then sliding a piston with

seals up and down a

cylinder

diaphragms need to be

high quality rubber

a diaphragm pump is

similar to a large diameter

piston pump with a short

stroke

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Dynamic pumps are used inconditions where high

volumes required and a

change in flow is not a

problem.

As the discharge pressure

on a dynamic pump is

increased, the quantity of

water pumped is reduced

Dynamic


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Pompa centrigugal berfungsi berfungsi

mengubah energi (external driving force)

ke energi kinetik di fluida denganmemberikan impuls ke fluida dengan

bantuan impeller.

Sebuah difuser atau volute mengubah

seluruh energi kinetik ke dalam

tekanan atau dengan kata lain mesin ini

menggunakan hukum dasar (Bernoulli )

konversi energi potensial ke energi

kinetik dan sebaliknya

Dalam hal kecepatan pompa konstran,

maka:

Head bervariasi dengan kuadratdiameter

Kapasitas bervariasi dengan

diameter

Power bervariasi dengan diameter

pangkat tiga

Dalam hal kecepatan pompa adalahsebuah variabel, maka:

Head bervariasi dengan kecepatan

kuadrat

Kapasitas bervariasi langsung

dengan kecepatan

Power bervariasi dengan kecepatan

pangkat tiga, karena fungsi dari head

dan kapasitas

Dynamic - Centrifugal Pump


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Electric

Motor

Suction

Nozzle

DischargeNozzle

Bearing

housing

Volute

casing

Shaft


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Classification of impeller by flow

Radial impeller

Semi axial impeller

Axial propeller

Thicker the Impeller- More Water

Larger the DIAMETER - More Pressure

Increase the Speed - More Water and Pressure

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Gas lift pump Hydraulic Ram Pump

Dynamic - Special Effect Pump


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Jet (Eductor) Pump Electromagnetic Pump

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Type, duties and capacities of centrifugal & displacement pump


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Pump used inmarineshipboard

applications

Diesel

propulsionvessel

Engine fresh water & seawater cooling pump

Single stage Centrifugalpump

Fuel oil transfer pumpsMultiple screw or rotary

pumps

Fuel oil supply & boosterpumps

Multiple screw or gearpumps

Lubricating oil pumpsMultiple screw or gear

pumps

Ships

service

Hydraulic System pumps Positive displacement pump

Bilge, ballast& Fire pumps Single stage centrifugalpump

Hotelservices

Single stage centrifugalpumps

Cargo

Single stage centrifugal pump

Multiple screw , lobe typerotary, sliding vane pump

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pump on ship

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