Lecture 04_PPE_Unit 2: High Pressure Boilers

Program: Diploma (Mechanical)
Class: TY (ME) Semester: V
Course: Power Plant Engineering
Code: 22566Code: 22566
LECTURE 04:
Unit: 2. High Pressure Boilers

02
wwwwwwwwwwww....ssssaaaannnnddddiiiippppffffoooouuuunnnnddddaaaattttiiiioooonnnn....oooorrrrggggMechanical Engineering Department, Sandip Polytechnic, NashikMechanical Engineering Department, Sandip Polytechnic, NashikMechanical Engineering Department, Sandip Polytechnic, NashikMechanical Engineering Department, Sandip Polytechnic, Nashik
Name of theName of theName of theName of the Trainer : Prof. Rushikesh Deoram SonarTrainer : Prof. Rushikesh Deoram SonarTrainer : Prof. Rushikesh Deoram SonarTrainer : Prof. Rushikesh Deoram Sonar
Years ofYears ofYears ofYears of Experience : 10Experience : 10Experience : 10Experience : 10
DomainDomainDomainDomain Expertise : Mechanical EngineeringExpertise : Mechanical EngineeringExpertise : Mechanical EngineeringExpertise : Mechanical Engineering
Qualification: M.E. (Design Engineering)Qualification: M.E. (Design Engineering)Qualification: M.E. (Design Engineering)Qualification: M.E. (Design Engineering)
Contact Details:Contact Details:Contact Details:Contact Details:
+91 9890481959+91 9890481959+91 9890481959+91 9890481959
rushikesh.sonar@sandippolytechnic.orgrushikesh.sonar@sandippolytechnic.orgrushikesh.sonar@sandippolytechnic.orgrushikesh.sonar@sandippolytechnic.org

03Unit II: High Pressure Boilers
TOPICS COVERED IN PREVIOUS LECTURE (03):-
2222....1111 Introduction to Boilers, types of Boilers
2222....2222 High Pressure Boilers - Classification
2.32.32.32.3 Construction and principle of working of :-
1. La-mont boiler
TOPICS TO BE COVERED IN THIS LECTURE (04):-
2.32.32.32.3 Construction and principle of working of :-
2. Benson Boiler
3. Loeffler Boiler
4. Schmidt- Hartmann Boiler

2.3.2 : BENSON BOILER : DIAGRAM & BASICS
Types of boiler: Forced circulation, High
Pressure boiler, supercritical boiler
Water tube, Also called ‘Once through boiler’
Steam Generating Capacity: 136 tones/hour
Pressure: 225 Kg/cm2
Pressure: 225 Kg/cm2
Temp.: 650°C

2.3.2 : BENSON BOILER : DIAGRAM & WORKING PRINCIPLE
Benson boiler works on the basic principle of
critical pressure of water.
If the boiler pressure is raised above critical
pressure(225 atm) , the steam and water have same
density so bubbles will not be formed.
Hence, the difficulty experienced in case of Lamont
boiler as danger of bubbles formation can be easily
boiler as danger of bubbles formation can be easily
eliminated.
It is also called as Once Through Boiler.

2.3.2 : BENSON BOILER : MAJOR COMPONENTS
Various part of boiler:
Feed pump
Economizer
Evaporator tube
Super heater
Furnace
Combustion Chamber
Combustion Chamber
Grate
Air preheater

It is also called as onceonceonceonce throughthroughthroughthrough boilerboilerboilerboiler, because
water is fed into the boiler at one end and
superheated steam discharge through other end,
withoutwithoutwithoutwithout useuseuseuse ofofofof drumdrumdrumdrum....
The feed water supplied by feed pump at a pressure
higher than 225 atm.
2.3.2 : BENSON BOILER : WORKING
This water passed through economizer then radiant
evaporator , where most of water is evaporated.
The remaining water is evaporated in convective
evaporator and converted into steam.
The steam is passed through the superheated and
finally supplied to the prime mover.

2.3.2 : BENSON BOILER : PATH OF FLOW
COMBUSTION
CHAMBER
RADIANT
EVAPORATOR
SUPERHEATER
CONVECTIVE
EVAPORATOR
ECONOMIZER
AIR
PRE-HEATER
CHIMNEY ATMOSPHERE
FLUE GAS PATH
WATER/ STEAM PATH
HOT WELL
FEED
WATER
PUMP
ECONOMIZER
RADIANT
EVAPORATOR
CONNECTIVE
EVAPORATOR
SUPERHEATER
STEAM
TURBINE

2.3.2 : BENSON BOILER : ADVANTAGES
Critical pressure so do not required any evaporator drum.
There is no drum, so total weight of the boiler is reduced and cost is also reduced.
Can be started very quickly in 10 – 15 minutes only.
Erection of the boiler is easier and quicker.
Operated economically by varying temperature and pressure with
High generation rate of steam.

2.3.2 : BENSON BOILER : DISADVANTAGES
Danger of overheating of tubes, when water flow is in sufficient.
Salt and sediments are deposited on the inner surface of water tubes which reduce the
heat transfer and steam generating capacity.
It requires frequent cleaning due to small deposits.
The water softening plant is required.

2.3.3 : LOEFFLER BOILER : DIAGRAM & BASICS
Pressure boiler, Water tube boiler
Water tube, Also called ‘Once through boiler’
Steam Generating Capacity: 100 tones/hour
Pressure: 140 bar
Pressure: 140 bar
Temp.: 500°C

2.3.3 : LOEFFLER BOILER : DIAGRAM & WORKING PRINCIPLE
Unlike in Lamont & Benson Boilers, the problem of
Bubbling and Salt deposition is eliminated here.
It preventing the flow of water into the boiler
tubes, as most of steam is generated outside the
tubes and in evaporating drum using parts of
superheated steam coming from the boiler.
superheated steam coming from the boiler.
In this boiler more steam circulation is used
rather than of water in other boiler, hence, steam
is heat carrying and heat absorbing medium.

2.3.3 : LOEFFLER BOILER : MAJOR COMPONENTS
Various part of boiler:
Feed pump
Economizer
Evaporating Drum
Radiant Super heater
Combustion Chamber
Convective Super heater
Steam Re-heater
Steam Re-heater
Mixing Nozzles
High Pressure Steam Turbine
Low Pressure Steam Turbine

2.3.3 : LOEFFLER BOILER : WORKING
The high pressure feed pump draws water through
the economizer and deliver it into the evaporating
drum.
An evaporator drum is out side the boiler. In this feed
water is evaporated by mixing superheated steam
coming from superheated.
The stream circulating pump draws saturated stream
from the evaporator drum.
The steam passes through radiant and convective
super-heaters where it is heated to required
temperature.
Steam coming from super heater, about 1/3 of
superheated steam is supplied to steam turbine and
the remaining 2/3 superheated steam is supplied to
evaporator drum to evaporator the feed water.

2.3.2 : BENSON BOILER : PATH OF FLOW
COMBUSTION
CHAMBER
RADIANT
EVAPORATOR
CONVECTIVE
EVAPORATOR
STEAM
RE-HEATER
ECONOMIZER
AIR
PRE-HEATER
CHIMNEY ATMOSPHERE
FLUE GAS PATH
WATER/ STEAM PATH
HOT
WELL
FEED
WATER
PUMP
ECONOMIZER
EVAPORATING
DRUM
RADIANNT
EVAPORATOR
CONNECTIVE
EVAPORATOR
STEAM
TURBINE
EVAPORATING
DRUM

2.3.3 : LOEFFLER BOILER : ADVANTAGES
The evaporator tubes in this boiler carries superheated steam, therefore there is no salt
deposition on the surface of tubes.
Compact in design.
Capacity to produce 100 tonnes/hour of steam at a temperature of 500 °C and at a pressure of
140 Bar.
Suitable for marine application.

2.3.3 : LOEFFLER BOILER : DISADVANTAGES
Converts energy just using 35 percent of the generated steam, rest is re-circulated.
Evaporating drum is use, which increase the cost of boiler.
It requires frequent cleaning due to small deposits.
The water softening plant is required.

2.3.4 : SCHMIDT-HARTMANN BOILER : DIAGRAM & BASICS
Pressure boiler, Water tube boiler
Steam Generating Capacity: 25
tones/hour
Pressure: 100 bar (Primary Circuit) & 60
bar (Secondary circuit)
Temp.: 650°C

2.3.4 : SCHMIDT-HARTMANN BOILER : DIAGRAM & WORKING PRINCIPLE
The boiler have a multi circuit as primary and secondary
which reduces the problem of overheating and salt
deposition in the tubes.
Feed pump is used to supply the water to a drum which
discharged saturated steam to the super heater.
The main feed water (impure) is evaporated as a
pressure of 60 bar in the secondary circuit
pressure of 60 bar in the secondary circuit
The pure distilled water is evaporated at pressure above
100 bar in primary circuit. In this boiler, energy (heat)
exchange occurs between two fluids at different
pressure.

2.3.4 : SCHMIDT-HARTMANN BOILER : MAJOR COMPONENTS Various part of boiler:
Feed pump
Feed Pre-Heater
Evaporating Drum
Water Drum
Combustion Chamber
Primary Evaporator
Primary Separator
Super Heater
Air Pre-heater
Air Pre-heater

2.3.4 : SCHMIDT-HARTMANN BOILER : WORKING
In primary circuit, steam is produced from distilled water,
which passes through a submerged heating coil, located in an
evaporator drum.
This high pressure steam in this coil of primary circuit has a
sufficient energy to generate steam from impure water in the
evaporating drum.
The steam produced in the evaporator drum passes through
the super heater and then supplied to the steam turbine.
Due to the heat transfer, the steam of primary circuit is
condensed and falls down into the low pressure feed pre
heater on its way giving up heat to the impure feed water.
Hence temperature of feed water increases to its saturation
temperature.
Therefore, only latent heat is supplied in the evaporator drum.
The water and steam in the primary circuit flow is taken place
due to density difference.

2.3.4 : SCHMIDT-HARTMANN BOILER : ADVANTAGES
It can use impure water for generation of steam.
No requirement of water softening plant ultimately reduces cost
Any deposits in the evaporator drum due to impure water can easily brushed off.
Wide fluctuations of load are easily taken by this boiler.

2.3.4 : SCHMIDT-HARTMANN BOILER : DISADVANTAGES
Evaporating drum is use which increase size of plant by cost.
Due to deposits in the evaporator drum because of impure water plant has to stop frequently
for cleaning.

In this lesson, We have learnedIn this lesson, We have learnedIn this lesson, We have learnedIn this lesson, We have learned
2.2.2 Construction, Working, Adv. & Disadv. of Benson Boiler
2.2.3 Construction, Working, Adv. & Disadv. of Loeffler Boiler
SUMMARY
2.2.3 Construction, Working, Adv. & Disadv. of Loeffler Boiler
2.2.4 Construction, Working, Adv. & Disadv. of Schmidt- Hartmann
Boiler

Our Next Video Lecture Topic
2.2 Construction And Working Principle of Boilers
5: Velox Boiler
6: Ramsin Boiler
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Lecture 04_PPE_Unit 2: High Pressure Boilers

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Lecture 04_PPE_Unit 2: High Pressure Boilers