heat transfer 01

8/3/2019 Heat Transfer 01

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POWERSYSTEMS

BOILER BASIC

DESIGN

Marine Engineering-ITS

By: Rahardhian and Dwi BagusPramono

May 1st, 2010


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Heat Transfer

Heat always moves from a warmer place to a coolerplace.

Hot objects in a cooler room will cool to room

temperature.

Cold objects in a warmer room will heat up to roomtemperature.


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Question

If a cup of coffee and a red popsickle were left on thetable in this room what would happen to them? Why?

The cup of coffee will cool until it reaches room

temperature. The popsickle will melt and then the liquidwill warm to room temperature


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Heat Transfer Methods

Heat transfers in three ways:

Conduction

ConvectionRadiation


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Conduction

Heat transfer across through fixed (solid) material

When you heat a metal strip at one end, the heat travelsto the other end.

As you heat the metal, the particles vibrate, thesevibrations make the adjacent particles vibrate, and so onand so on, the vibrations are passed along the metaland so is the heat. We call this?

Conduction


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Convection

Tranportation and exchange of heat due to the mixingmotion of different parts of a fluid

The particles spread out and become less dense. Cooler, more dense, fluids sink through warmer, less dense

fluids. In effect, warmer liquids and gases rise up.

Cooler liquids and gases sink. Natural convection and forced convection


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Radiation

Transfer radiant energy from a source to a receiver(without medium = electromagnetic wave)

Luminous radiation and non-luminous radiation

?


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Heat Transfer in the Boiler Pressure Parts

RadiantSH

Spaced

SH

Evap.

Econ.

Furnace

Furnace

radiation mode

Radiant (Plattent) Superheater

luminous radiation mode non-luminous radiation mode

convection mode

Convective (Spaced) Superheater

non-luminous radiation mode convection mode

Evaporator (Boiler Bank)

convection mode

Economizer

convection mode


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What factors will impact to heat transfer ?

Temperature different Heat source

Heating surface area

Physical properties thermal conductivity heat transfer coefficient emisivity wall thickness

slag or ash layer internal scales or sludge layer


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HEATING STEAM FOR INDUSTRIAL NORMALLY TAKEN FROM MIXED AREA TO THE UPPER LIMIT LINE(LUL) --> SATURATED STEAM

THE SUPERHEATED STEAM AREA WILL BE USED FOR STEAM TURBINE

THE ADVANTAGES OF SUPERHEATED STEAM :

INCREASE TURBINE EFFICIENCYPREVENT DAMAGING AT THE LOW STEAM TURBINE BLADES DUE TO CONDENSATIONLESS CONDESATION WHEN TRAVEL THROUGH A LONG PIPE LINE

GENERATIVE (PREHEATED) PROCESS TO THE FEEDWATER WILL INCREASE BOILER EFFICIENCY

T

00C

E

A B

CD

O

K

P3

P1

P2

DC

O-A: ICE WARMING A-O : ICE COOLING

A-B: ICE MELTING B-A : ICE FREEZING

B-C: WATER HEATING C-B : WATER COOLING

C-D: WATER BOILING D-C: STEAM CONDENSING

D-E: STEAM SUPERHEATING E-D : STEAM EXPANDING

THE HIGHER PRESSURE PROVIDED TO THE PROCESS WILL RESULT INHIGHER BOILING TEMPERATURE

B-E : PROCESS IN THE BOILER

E-D : PROCESS IN THE STEAM TURBINED-C: PROCESS IN THE CONDENSOR

C-B : WATER FROM CONDENSOR BACK TO THE BOILER

K : CRITICAL POINT = 3208 Psia, STEAM & WATER

PROPERTIES ARE IDENTICAL


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Combine Cycle Power Plant Arrt

Overview of Typical Combined Cycle Plant

Gas Turbine

Heat Recovery Steam Generator Steam Turbine

Balance of Plant


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Overview of Typical Combined Cycle Plant


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Combined Cycle Principle


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Combined Cycle Plant Arrangements

Plant Power Output Number and Type of Gas Turbines

Number of Gas Turbines for Each Steam Turbine 1 on 1 (Multiple Shaft or Single Shaft) 2 on 1

3 on 1

Gas Bypass System

Steam Bypass System

Number of Pressure Levels Steam Pressure, Temperature, and Flow

HRSG Fired or Unfired


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Gas Turbine


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Heat Recovery Steam Generator


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Heat Recovery Steam Generator

Generally Capable of Accepting Gas Turbine Exhaustwithout Restriction Follows Gas Turbine Loading

Restrictions are Required when a Diverter Damper is

Present - HRSG cannot accept Full GT Flow andTemperature Instantaneously

Steam Generated Must be Permitted to go Somewhere

Superheater and Reheater Drains Opened During StartUp to Drain Condensate

Steam Vents Opened During Start Up to Ensure SteamFlow Through HRSG


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Steam Turbine


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