What is an Air Preheater?Explain its working applications,types and advantages

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What is an Air Preheater?Explain its working
applications,types and advantages
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Index

• What is Air preheater
• Working applications of air preheater
• Types of air preheaters
• Advantages of air preheaters

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Air Preheater
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Air preheaters

• Air preheaters are classified as any kind of
  device that is used to heat the air to a certain
  temperature. The heated air is then then utilized
  as a primary source of energy to increase the
  thermal efficiency of the following process.
• Air-preheaters are placed at the beginning of the
  process and are used individually or to replace
  heat-exchangers already in place.

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How does an Air-Preheater works?

• Air Preheaters are designed on the basis of the
  kind of medium and the temperature required for
  the application. A small sized preheater is
  designed in such a way that more heating takes
  place in a smaller case.
• This is achieved by arranging a group of smooth
  surfaced tubes through which the media can flow
  through.
• However, it is found out that Air-Preheaters
  function in a more efficient way when a number of
  them are used collectively. Depending on the type
  of flow in the pre-heater, the design of the
  pre-heater will change.
• Usually a standard pre-heater will have counter
  flow, co-current flow, co-current flow-counter
  current or cross-counter current or
  cross-co-current flow type media.

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What are the different types of Air-Preheater

• On the basic level there are two types of
  Air-Preheaters namely,
• Tubular or Recuperative Type
• Feed Water or Regenerative Type

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Tubular Type Air-Preheater

• Tubular preheaters are preferred in smaller and
  medium sized boilers. Here the construction of
  the preheater restricts the flow of the media to
  be carried in tube shaped walls.
• The media is separated by these tubes and the air
  to be heated is passed through these tubes by
  force.
• The heat exchange takes place between the heated
  media and the air after which the air is carried
  out for its further process.

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Feed Water Type Air-Preheater

• A feed water preheater has a stationary rotating
  hood. The heat exchange between air and the media
  takes place by alternate heating and cooling of
  the ceramic or metallic plates which rotate
  continuously.
•  

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What are the advantages of using an Air-Preheater

• From pre-heating the air to be it far more
  effective an air-heater has several other
  advantages. These include increasing the thermal
  efficiency of the entire system, improving the
  strength of the combustion chamber (If used in IC
  engines) and easy use with all types of fuels and
  can easily be fitted in most existing systems.
• What are the applications of an Air-Preheater?
• Industrial steam boilers
• Industrial drying processes
• Refinery petro chemical furnaces
• Incinerators

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•  
• What is an adiabatic cooling system?
• Adiabatic cooling is the process of reducing the
  temperature of a process through a change in air
  pressure caused by volume expansion. The use of
  adiabatic process enables free cooling methods
  which can be used freely as they are available in
  a natural phenomenon to regulate temperature.

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What is a Desuperheater Water heater and what are
its applications

• A Desuperheater is a device which has the
  capability to transfer heat to or from the
  ground, which can be later utilized for any
  purpose. It uses the earth all the time without
  the need of any heat source (Usually in the
  winter) or a heat sink (In the summers).
• This process takes advantage of the moderate
  temperatures in the ground for boosting
  efficiency and reducing the operational costs of
  heating and cooling systems which when combined
  with solar heating  form a geosolar system with
  even a greater efficiency. A Desuperheater can
  have a variety of uses from heating the in your
  storage to other household related applications.

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What is the desuperheating theory

• Superheated steam is a steam which is at a
  temperature higher than the saturation
  temperature for the steam pressure. If further
  heated is added to this batch of steam, then the
  steam will,
• Will be at a higher temperature then the
  saturation temperature
• Contain more energy than the saturated steam
• Has a greater specific volume than the saturated
  steam
• The relationship between these three properties
  is referred to as the desuperheating theory.

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How are the desuperheaters installed

• The total installed length of a desuperheated
  will vary in size and length but is typically
  about 7.5m.
• Depending on the type of flow, desuperheaters
  should be installed in the opposite direction,
  i.e if the flow is upwards then the
  desuperheater should be installed vertically.

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What are the different types of desuperheaters

• Here are some types of desuperheaters that are
  used more commonly,
• Venturi type desuperheater
• Steam atomising desuperheater
• Variable Orifice desuperheater
• Combined pressure control valve superheater

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What are some applications of superheaters

• Power generation
• Process controllability
• Thin pipes and lighter flanges
• Prevents lubrication degradation
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