A1258150264NWxQb

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Chapter 5. HEATING PRODUCTION EQUIPMENT AND
SYSTEMS
5.4 What is the chief limitation preventing air
furnaces from being used in heating systems for
large buildings?
5.5 When might steam boilers be preferable to
hot-water boilers for a large building system ?
5.6 Name several factors that should be
considered in locating a central boiler plant for
a large building?
5.8 What characteristics of a water tube boiler
should be considered in selection for a building
application?
5.9 What characteristics of a cast-iron sectional
boiler should be should be considered in
selection for a building application?
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5.10 Describe some advantages and disadvantages
of power burners in comparison with atmospheric
burners.
5.14 What is the purpose of boiler blowdown?
5.17 Which of the fire tube and water tube
boilers are more responsive to load changes, and
why?
5.21 What are the major chemical components of
natural gas?
5.23 What are the four basic principles of water
treatment?
5.30 What factors are considered in deciding the
height of a flue stack?
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• 5.3.1 Type of Furnaces
• Type of fuel or energy
• Gas / Oil / Gas-Oil / Electricity
• Process of combustion
• Open Combustion chamber / Sealed chamber
  (Impulse)
• Design and construction
• Design Cabinet configuration (vertical /
  horizontal), Air-flow (up flow / down
  flow), Air-delivery (ducted delivery /
  free delivery)
• Construction Indoor / Outdoor / Pad-mounted /
  Rooftop-mounted
• Services
• Heating only combined / Heating and cooling
  combined

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• 5.4.3 Water Tube Boiler
• Water is on the inside of the tubes and the
  combustion gases pass around the outside of the
  tubes
• Water tube boilers are available in all sizes
• The water tube boiler is less than a fire-tube
  of equivalent capacity
• The Water tube boiler is respond quickly to load
  fluctuation

How steam engines work(Water tube boiler)
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• 5.4.4 Cast-Iron Sectional Boiler
• Consisting of a series of vertical cast-iron
  sections filled with water
• These boilers are used primary in residential and
  small to medium-size commercial buildings
• They can be assembled in the field, section by
  section
• It is not applicable to high-pressure systems
  owing to limited strength
• Pressure
• Steam 1kg/cm2
• Water 7kg/cm2

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• 5.6 SELECTION OF MEDIUM AND EQUIPMENT
• 5.6.1 Selection of medium Steam versus Hot-Water
  Generation
• Hot water is practical owing to its simplicity of
  design and lower maintenance when compared with
  steam.
• Hot water system
• Low Temperature hot-Water system (LTW) 82C -
  115C.
• Medium Temperature hot-Water system (MTW)
  115C - 176C
• High Temperature hot-Water system (HTW ) over
  176C

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• 5.7 AUXILIARY SYSTEM
• 5.7.1 Burners
• Burners are designed to mix fuel air and ignite
  the mixture for
• combustion within the boilers.
• Atmospheric burners
• They are used for small and medium-size gas
  boilers
• Depend on the natural draft provided by the stack
  for the
• introduction of combustion air
• They are the simplest available and operate on
  low-gas
• Power burners
• They allow the use of smaller-diameter breechings
  and stacks,
• which must be gastight because they are under
  positive pressure

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• 5.7.2 Boiler Blow-down
• It is the process of draining water from the
  boiler to reduce the concentration of dissolved
  solids, remove sludge from the bottom of the
  boiler shell
• Blow-down is prevent the scale and the corrosion
  of inside
• Intermittent Blow-down
• This is implemented with a quick-opening valve at
  the boiler blow-down outlet, piped in series with
  a slow-opening valve
• Continuous Blow-down
• It is common in large systems and serves to
  remove suspended materials from the surface of
  the boiler water
• The quantity of blow-down is controlled manually
  or automatically

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• 5.7.5 Combustion Air
• Air is a vital part of the combustion process
• Combustion is the result of the following
  chemical reactions between oxygen(O) and the
  combustibles
• Air contains approximately 21 oxygen by volume
• Air must be supplied to the combustion chamber in
  excess of the theoretical quantity required to
  ensure proper combustion
• It is between 1015 of excess air is necessary
  to ensure proper mixing of fuel with air
• When large amounts of combustion air are
  introduced into the boiler room, the space may
  become extremely cold during the winter, even to
  the point where it causes localized freezing of
  water piping and other components

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• 5.7.7 Flue Gas Handling
• The products of combustion from boilers and
  furnaces are called flue gas
• Flue gas toxic and must be ducted and vented to
  the outdoors through flue stacks or chimneys
• Flue Gas Temperature
• Flue Gas Velocities
• Draft
• Mechanical Draft
• Flue Stack Height

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• 5.7.8 Water Treatment
• Principles of Treatment
• Removal of Solids in Water
• Its Zeolite ion exchange process through Ca is
  transformed Na
• Action of the Blow-down
• Removal of Oxygen
• Its by heating boiler feed-water is an effective
  way to remove oxygen
• Reduction of acidity in water
• Acidity is another cause of corrosion. Therefore
  10.5pH(alkalinity) desired
• Inhibition
• Chromate can not be used, it produces the
  carcinogen(cancer-causing)
• Sodium nitrite is used instead of Chromate
• Planning
• Water Treatment is desirable for steam and
  closed-circuit hot-water
• It is need to planning by the proper types and
  quantities of chemicals are used

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• 5.9 BOILER PLANT DESIGN
• 5.9.1 Location of the Plant
• The heating plant may be located at the lower
  levels(ground level or basement) or upper
  levels(top floor or penthouse) of the building,
  or in a separate or attached building
• Heating and cooling plants are integrated and
  thus should be in the same location