Water tube boilers have higher efficiencies than fire tube boilers. There are several ways to improve the efficiency of a water tube boiler, including reducing stack temperature, minimizing radiation and convection losses through improved insulation, controlling excess air, increasing heating surface area, optimizing boiler blow down, preventing fouling, using economizers to preheat feedwater, and employing more efficient water level controls. Proper ratios of fuel and air are also important for complete combustion. Water tube boilers are widely used in industries such as garment manufacturing, chemical processing, pulp and paper production, refineries, marine applications, and railways.

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2. How To Improve the efficiency of water
tube boiler
GROUP MEMBERS:
NAME REG. NO:
Md. Toufiqur Rahman -2012334058
Md. Rabiul Hasan -2012334059
Sunny Saha -2012334060
Md. Muhibur Rahman -2012334061
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3. • To know about water tube boiler & it’s specifications
• To acquire knowledge about the working principles variations of
water tube boiler
• To analyze how to increase the efficiency of a water tube boiler
• To sort out the applications of water tube boiler
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objectives

4. •A boiler is a closed vessel in which water or
other fluid is heated.
• The heated or vaporized fluid exits the boiler for use in various
processes or heating applications, including water
heating, central heating, boiler-based power
generation, cooking, and sanitation.
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Boiler:

5. Classification of Steam Boiler:
Fire-tube
Boiler
Water-tube Boiler
The water is heated inside
tubes and the hot gasses
surround them.
Hot gasses are passes
through tubes which are
surrounded by water.
There are two general types of boilers:
Boiler
Fire-
Tube
Water-
Tube
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6. Water tube boiler:
A water tube boiler is such kind of boiler
where the water is heated inside tubes and
the hot gasses surround them.
Specifications:
 Are available in sizes far greater than a fire-
tube design , up to several million pounds-
per-hour of steam
 Are able to handle higher pressures up to
5,000 psig
 Recover faster than their fire-tube cousin
 Have the ability to reach very high
temperatures 6

7. Water-tube Boiler Sections
Furnace or Radiant
section
 Walls of the furnace section
are lined with finned tubes.
 Having an open area
accommodating flame(s)
from the burner(s).
 Finned tubes are used to
absorb the radiant heat from
the flame.
 Flames were allowed to
come into contact with the
boiler tubes.
Convection section
 Designed to absorb the heat
from the hot gases by
conduction and convection.
 Have several tube banks in
series.
 Tube banks for gaining
maximum energy from the hot
gases.
The energy from the heat source may be extracted in the
form of radiation, convection or conduction.
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8. Boiler Mountings:
 Water level indicator
 Safety valve
 Pressure gauge
 Steam stop valve
 Feed check valve
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9. Working principle:
• It consists of mainly two drums, one is upper
drum called steam drum other is lower drum
called mud drum
• These drums connected by two tubes namely
down-comer and riser tubes
• Water in the lower drum is heated and steam
is produces
• Steam stored above the water surface the
boiler system
• The colder water is fed from feed water inlet
at upper drum
• the colder water push the hotter water
upwards through the riser
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10. Water-tube Boiler:
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11. Classifications of Water Tube
Boiler:
There are many types of water tube boiler .
 Horizontal Straight Tube Boiler.
 Bent Tube Boiler.
 Cyclone Fired Boiler
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12. Classifications of Water Tube Boiler
Horizontal Straight Tube Boiler again can be sub-divided into
two different types, such as
 Longitudinal Drum Boiler
 Cross Drum Boiler.
Bent Tube Boiler also can be sub-divided into four different types,
such as
 Two Drum Bent Tube Boiler.
 Three Drum Bent Tube Boiler.
 Low Head Three Drum Bent Tube Boiler.
 Four Drum Bent Tube Boiler.
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13. Design Variations
i) D-type boiler
 the most common type of small- to medium-
sized boilers
 used in both stationary and marine applications
ii) Cross Drum Water Tube Boiler
 In Cross Drum Boiler the steam drum is placed
at cross ways to the heat source
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14. Design Variations
iii) Stirling boiler
 The Stirling boiler has near-vertical, almost-straight
water tubes that zig-zag between a number of
steam and water drums.
 They are mainly used as stationary boilers, owing to
their large size, although the large grate area does
also encourage their ability to burn a wide range of
fuels.
iv) Babcock – Wilcox Water Tube Boiler
 It is also known as Longitudinal Drum Boiler or
Horizontal Tubes Boiler
 one cylindrical drum is longitudinally placed above
the heat chamber
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15. Efficiency of A Boiler
 The ratio of percentage of the total absorption
heating value of outlet steam to the total supply
of heating value.
 In other word, it is a rate how the boiler runs
efficiently
 Boiler efficiency= Steam value per hour
Fuel consumption per hour
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16. Method of Calculating Boiler
Efficiency
There are two method to measure the boiler
efficiency :
 Direct method
 Indirect Method
 Direct Method:
Boiler efficiency simply relates energy output to
energy input, usually in percentage terms.
Boiler Efficiency % =
(Heat Exported in Steam / Heat provided By
the Fuel) x 100
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17. Method of Calculating Boiler
Efficiency:
Indirect Method
 The indirect method applies the heat balance,
which considers stack temperature and losses, excess
air levels, blowdown, and radiation and convection
losses.
 Therefore, the heat balance calculation for fuel-to-
steam efficiency is:
Efficiency % 100 - (Sum of the Losses%)
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18. Way to Increase Efficiency of
A Water Tube boiler:
 The efficiency of a water tube boiler can be increased by
following two major ways.
 One is to identify the control parameters that should be
improved. And the other is to identify the challenges related
to increase the efficiency.
 When it is possible to increase the performance of control
parameters of the water tube boilers, the efficiency will
increase.
 Similarly, Once the challenges are identified, it is possible
to take account these points from the very beginning of the
process.
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19. Way to Increase Efficiency of
A Water Tube boiler
1. Construction of Stack in Boiler:
 Stack is a equipment to take out the product of
combustion at a sufficiently high elevation
 It is used to prevent disturbance caused by ash,
low flying smoke, and soot and to disperse the
combustion
 To perform flue gas flow through steam boiler
room until be discharged to atmosphere, requires
a certain amount of draft
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20.  Draft can be generated by fan either force draft fan
or induced draft fan
 Excessive heat temperature of stack decreases the
efficiency of the boiler.
 So, if it is possible to reduce stack temperature,
the efficiency of the boiler will increase.
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21. 2. Reducing Radiation and
Convection Losses:
The external surface of an operating steam boiler is
hotter than its surroundings and therefore loses
heat by both radiation and convection
 Radiation and convection losses will vary with boiler
type, size, and operating pressure.
 The losses become a larger percentage loss as the
firing rate decreases
 Poor insulation can increase the radiation and
convection rate.
 Thus a good insulation system should be introduced
for better efficiency
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22. 3. Excess Air:
 Accurate control of the amount of air is essential to
boiler efficiency:
 To much air will cool the furnace, and carry away
useful heat.
 To little air will result in incomplete combustion;
therefore, unburned fuel will be carried over and
smoke may be produced
 The quantity of fuel and air would be in a perfect
ratio to provide perfect combustion with no unused
fuel or air
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23.  Excess air requirements as the firing rate of the boiler
decreases leading to lower efficiency
 To complicate matters, most boilers operate on the
lower end of the firing range
 So selecting a boiler that has optimal excess air
throughout the firing range is important.
 This will ensure that the boiler is always operating at
high efficiencies
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24. Heating Surface:
 Boilers with higher heating surface per boiler
horsepower tend to be more efficient
 Many packaged boilers are offered with 0.46
square meter (5 square feet) of heating surface
per boiler horsepower as an optimum design for
peak efficiency
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25. 5. Boiler Blow Down Control:
 Removal of water from a boiler
 Used for controlling boiler water parameters within prescribed
limits
 Also used to remove suspended solids present in the system
 Required Blowdown is the ratio of measured concentration of the
selected chemical in the feed water to the measured
concentration of the same chemical in the blowdown
Required Boiler Blow Down :
where C feed water= the measured concentration of the selected
chemical in the feed water
C blow down= the measured concentration of the same chemical in
the blow down
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26. 6. Prevention of Fouling:
Fouling is the accumulation of unwanted material on
solid surfaces to the detriment of function
 Fouling on the external tube surfaces of a water
tube boiler lower the efficiency
 Water-side deposits resulting from inadequate
water also decrease efficiency of the water tube
boiler
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27. 7) Uses of Economizer:
 Flue gas heat exchangers used for water
heating are known as "economizers".
 Economizer help to avoid the higher cost of fuels
 Large quantity of water is required to cool the flue
gas which is minimized by using economizers.
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28. 8) Preheated feed water:
 preheating feed water in an economizer
recovering waste heat from flue gas
 In general, an increase in feed water temperature of
6°C (11°F) will result in 1% less fuel being burned
at the boiler.
Source: ‘’IMPROVING
STEAM BOILER
OPERATING EFFICIENCY’’ ENERCON
National Energy Conservation Center
ENERCON Building, G-5/2, Islamabad
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29. SWOT Analysis:
High working properties
Less danger of injuries
Improve the quality of steam
 Improve the efficiency of
economizer
More efficient water level control
is required
High quality feed required
Improper ratio of fuel and
air.
 Higher energy radiation and
heat loss
strength weakness
opportunity threat
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30. Application:
 Garments industry
 Chemical processing divisions
 Pulp and Paper manufacturing plants
 Refining units
 Marine Industry
 Electric transmission in Railway
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31. Owing to superb working properties, the use of water tube
boilers is highly preferred. There are many scopes to increase
the efficiency of the water tube boiler. Increasing the
efficiency of the water tube boilers causes the better
productivity of the industries.
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32. THANKS TO ALL