Impact of Fuel Quality on Design of Steam Generator

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Impact of Fuel Quality on Design of Steam
Generator

• P M V Subbarao
• Professor
• Mechanical Engineering Department

The Influence of Natural Resources on
Development.
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Basic The Theme Steam Generator Design

• Constrains
• Imposed by Cycle Design (pmax, Tmax, etc.)
• Fuel Combustion Related.
• Heat Transfer Related
• Safety and Reliability Related.

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Details of Basic Processes

• Flow of Air and Prepared Fuel
• Fluid Dynamics.
• Generation of Thermal Energy Using Natural
  Resources.
• Combustion Sciences.
• Transfer of Thermal Energy to working fluid.
• Science of Heat Transfer.

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Duties of A Furnace

• Dixons Theory
• Generate an environment of excited fuel and
  oxygen molecules.
• All the fuel molecules should be surrounded by
  oxygen molecules.
• Facilitate frequent collisions among excited fuel
  molecules and excited fuel molecules.
• A successful collision can lead to combustion.
• Realization of Dixons Theory using Coal is
  highly challenging.
• Many possible technologies are available to
  realize above conditions with varying levels of
  success and expenditure.
• These are called Three Ts and one S technologies.

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Five Requisites for Good Combustion

• Fuel
• MATtr Theory
• M Proper mixing of the reactants.
• A Sufficient air.
• T Conducive temperature
• t Sufficient time
• r Satisfactory density of reactant.
• Fourth DF systems contains various auxiliaries to
  satisfy MATtr theory as completely as possible.

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Realization of MATtr Theory

• Mixing Fuel preparation systems.
• Air Draught systems.
• T Preheating of fuel.
• t Dimensions of combustion chamber.
• r Turbulence generation systems.

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The Three Ts One S Practice
Technology Time Temperature Turbulence Size
Stoker large Medium Low Big
Pulverized Short High Medium Tiny
Cyclone Short V High High Medium
Fluid Bed Medium Low High Medium
Size the Coal and Add the Air !!!
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Major Components of Coal Fired Steam Generator
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Major Components of Solid Waste SG
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The Timing - 1
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The Timing - 2
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Typical 455 MWe pulverized coal-fired drum boiler
BW Carolina-type Radiant boiler
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Basic Geometry of A Furnace
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Boiler Furnace

• Structurally boiler furnace consists of the
  combustion space surrounded by water walls.
• The furnace is designed to perform two functions
  simultaneously, namely
• Release of the chemical energy of fuel by
  combustion
• The first task of combustion technology is
• to burn the fuel efficiently and steadily,
• to consume controlled excess air (as little as
  possible),
• To generate a flame with controlled shape which
  will generate lowest amount of pollutants.
• Transfer of heat from the furnace to the working
  fluid inside the water walls.
• The important task of furnace heat removal is to
  produce a controlled Furnace Exit Gas Temperature
  (FEGT).
• FEGT is an important aspect of boiler safety.

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