Pump

PUMP

200722120 김민수

Contents• Introduction

• Types of pumps

• Shaft seal

Introduction

Objective of Pumping System

• Transfer liquid

• Circulate liquid

• Used for

: Domestic, commercial, industrial and agricultural

: Municipal water and waster water services

Introduction

Main Pump System Components

• Pump

• Prime movers

• Piping

• Valves

• Other fittings, control, instrumentation

Introduction

Head

• The height at which a pump can raise liquid up

H : head [m]

P : pressure [kg/

SG : specific gravity

Introduction

Head

• Static head

Introduction

Head

• Friction head : Resistance to flow in pipe and

fittings

Frictionhead

Flow

Introduction

Introduction

Pump Operating Point

Flow

Head

Static head

Pump performance curve

System curve

Pump operating point

Introduction

Pump Performance Curve

Introduction

System Curve

Systemhead

Flow

Static head

Frictionhead

Systemcurve

System head

Flow

Static head

Friction head

Systemcurve

Introduction

Pump Operating Point

Flow

Head

Static head

Pump performance curve

System curve

Pump operating point

Introduction

Cavitation

• Bubbles inside the pump

• Damage & Loss of capacity

Introduction

Cavitation – How to prevent

• Lower the temperature

• Raise the level in the suction level

• Change the pump

• Reduce motor RPM if possible

Introduction

NPSH

• Net Positive Suction head

• Must be calculated to prevent cavitation

• NPSHr & NPSHa

• NPHSa > NPSHr * 1.3

Types of Pumps

Pump

Dynamic

Centrifugal

Mixed flow

Axial

Positive Displaceme

nt

Rotary

Internal gear

External gear

Lobe

Vane

Reciprocating

Types of Pumps

Dynamic

• Conversion of Energy

Positive Displacement

• Displacement

Centrifugal pump

• Rotating impeller

Centrifugal pump

• Rotating impeller

• Centrifugal force

Centrifugal pump

Specific speed ()

• The speed a geometrically similar impeller would need

to operate in order to deliver 1L/s of fluid at a head of

1m.

• Used to

- Comparing different pump designs

- Determine the efficiency of the pump

- Predict NPSHr

Centrifugal pump

Specific speed ()

N : speed of the pump in RPM

Q : flow rate (

H : total dynamic head (m)

Centrifugal pumpWHP

(water horsepower)

• The energy imparted

to the water by a

pump

BHP(brake

horsepower)

• The input power

needed at the pump

shaft

Centrifugal pump

WHP & Pump efficiency

: Discharge flow rate (

H : Head (

Centrifugal pump

36.8?

Centrifugal pump

Affinity law

Centrifugal pump

NPSHr

• Net Positive Suction head required

• The minimum pressure required to keep the

pump from cavitating

Centrifugal pump

NPSHr

• Usually determined experimentally

Centrifugal pump

NPSHa

• NPSHa = Hp + Hz – Hf + Hv – Hvp – Ha

Hp : Absolute pressure on the surface of the liquid

Hz : Vertical distance between the surface of the liquid and the

centerline of the pump

Hf : Friction losses

Hv : Velocity head ( Often not included as it’s nomarly quite small

Hvp : Absolute vapor pressure of the liquid at the pumping

temperature

Ha : Acceleration head

Rotary pump

• Rotary action

Rotary pump

• Rotary action

Reciprocating pump

• Reciprocation of piston plunger

• Viscous fluids and oil wells

Gas transportation machine

• Fan, Blower, Compressor, Vacuum pump

Gas transportation machineSpecific speed ()


Q : flow rate (

p : total pressure (mmAq)

r : specific weight (

Vacuum pump

• Device that removes gas molecules from a

sealed volume in order to leave behind a partial

vacuum.

• ]

P : pressure (torr)

S : exhaust velocity (L/s) : volumetric efficiency = ɳ

Vacuum pump

•

m : polytropic indexε : void ratio

Example 1


Q : flow rate (

H : total dynamic head (m)

Example 2

Example 3

• Piston 직경이 20cm, Crank 의 반경이 50cm 이고 , 회전수가 20rpm 인 복동식 왕복 펌프의 평균 배출량은 몇 인가 ? 단 , 체적효율은 0.98 이다 .

Example 3


: 이론상 배출량 []

D : Piston 직경 [m]

d : Rod 직경 [m]

N : Crank 의 분당 회전수

L : 피스톤이 움직인 거리

Example 3


Example 3


Example 3


ɳ

Q = ɳ

Example 4

• 10Kg/s 의 속도로 유체를 수송하고 있는 펌프가 있다 . 수송에 필요한 에너지가 114 효율이 75% 라면 펌프의 수마력과 제동마력은 각각 몇 HP 인가 ?


H : Head (

Example 4


• = 0.1

Example 4



H : Head (

•

Example 4


• 14.949 HP

• BHP = 19.932 HP

Example 5

• 20℃ 에서 1750 rpm 으로 회전하고 있는 Fan 의 전압이 155mmAq, 풍량이 240얼마인가 ? 또 이것과 닮은 Fan 을 만들어 1650 rpm 으로 회전시킨 것은 전압이 200mmAq 였다 . 이 경우 풍량은 몇 되겠는가 ?

단 , 20℃ 에서 공기의 비중량은 1.205 이다 .


Q : flow rate (

p : total pressure (mmAq)

r : specific weight (

Example 5

• 20℃ 에서 1750 rpm 으로 회전하고 있는 Fan 의 전압이 155mmAq, 풍량이 240얼마인가 ? 또 이것과 닮은 Fan 을 만들어 1650 rpm 으로 회전시킨 것은 전압이 200mmAq 였다 . 이 경우 풍량은 몇 되겠는가 ?

단 , 20℃ 에서 공기의 비중량은 1.205 이다 .

• 709

Example 6

• 1 단 왕복진공 펌프에서 최대 진공도가 얻어지는 경우의 흡입측 압력을 구하라 . 단 송출측 압력은 760mmHg abs, 간극비 ε = 0.0646, polytropic index m =1.3 이다 .

m : polytropic indexε : void ratio

Shaft seal

Shaft seal

Shaft seal

• Forms a barrier

• Influences performance

Shaft seal

Type of shaft seals

Mechanical Shaft seal




References

• UNEP(2005). Pumps & Pumping systems.

• How to design a pump system. Retrieved from

http://www.pumpfundamentals.com

• Centrifugal pumps. Retrieved from

http://www.learnengineering.org

• GRUNDFOS(2009). Mechanical shaft seals for pumps.

• Lev Nelik(1999). Centrifugal and rotary pumps : Fundamentals with applications.

• 권순홍 , 펌프공학 (2000), 유림문화사

• 이원섭 , 최신 유체기계 (2011), 학진북스

http://www.pumpfundamentals.com/

http://www.learnengineering.org/

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Pump