2. WHAT IS BOILER
• A boiler is a closed vessel in which fluid (generally water) is heated.
The fluid does not necessarily boil.
• 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,
process heating.
• The generation part of a steam system uses a boiler to add energy
to a feed water supply to generate steam.
• The energy is released from the combustion of fossil fuels or from
process waste heat.
• Anywhere you are creating heat and/or steam, you will probably
find a boiler.
3. TYPES OF BOILER
• Based on what flows through the boiler tubes :
1) Fire or smoke or shell-type boilers – Flue gases are inside
and water is Outside .
2) Water tube boilers – Water is inside and flue gases are outside
• Based on construction:
1) Package boilers
2) Field erected boilers
WE HAVE SHELL TYPE FIRE TUBE BOILER.
4. BOILER WORKING PRINCIPLE
• Hot gases are formed by burning fuel in the
furnace.
• These gases are made to come in contact with the
water vessel, the point where the heat transfer
takes place between the steam and water.
• Thus, the boiler's basic principle is to convert water
into steam with heat energy .
• The main function of a boiler is to heat water to
generate steam. Steam produced in a boiler can be
used for a variety of purposes including space
heating, sterilization, drying, humidification and
power generation.
5. BOILER BURNER UNIT
• Burner is the heart of the boiler
• There are three types of burners:
1) Oil Burner – Oil used as fuel
2) Gas Burner – Gas used as fuel
3) Dual Burner - Gas is primary fuel
whether oil is secondary.
FIRE = AIR + FUEL + IGINATION
7. VAPL BOILER
• Boiler Type :- HORIZONTAL , SHELL TYPE BOILER WITH
INTEGRAL WET BACK FURNACE
• Make :- Ashwani
• Capacity :- 12.4 TPH
• Pressure :- 12.5 Kg
• Fuel Firing :- FO/HHC
• Set point :- 5.5Kg
• Cut off :- 6.5Kg
9. FEED WATER PUMP
• Take the water from the feed water tank & supply the water
to boiler.
• Two feed water pumps are provided, one working and one
standby.
• The pumps are vertical, multistage, centrifugal types.
• The pump is operated on off, by the water level controller
(Mobrey).
10. COMBUSTION FD FAN
• Air required for Combustion is provided by forced draught fan mounted
separately.
• This fan is designed to supply air at required pressure and quantity.
Pressure is decided on the basis of burner pressure drop and
combustion chamber pressure drop.
• The fan is driven by a directly coupled 3 Phase induction motor.
• It is recommended to provide a flexible leather/canvas bellow between
burner and fan to avoid transfer of vibrations if developed by the fan.
Medium :- Ambient air .
Type :- Centrifugal
FD FAN Air Flow :- 5.4m3/sec
Air Pressure :- 570mmwc
11. MODULATION UNIT
Drive Motor.
Type : Capacitor type of motor with electromagnetic brake.
AC Voltage : 230 Volts; Standard (110 V on request).
Power Input : 90 Watts
Load on shaft : 300 kg cm.
Running time : 32 Seconds for 180 Degree Rotation.
Feed back potentiometer : 135 Ohms or100 Ohms.
Limit Switches.
Four nos. micro switches are provided for controlling the limiting position for low fire and high fire.
Gear Assembly
It is of a high torque design. It is driven by the servomotor. A clutch is provided in the fear train which
permits the turning of the end shaft fitted with control drum and cam disc by hand.
Air regulating drum.
For adjustment of the air damper by mechanical transmission to the air flap shaft. The regulating drum is
provided with 16 adjusting screws. On these screws a steel band is provided. The shape of the steel band
controls the air flap shaft by a conducting arm.
Flame Tube. This is provided to give proper shape to the flame.
12. FLAME SENSOR
• Safety device in combustion chamber.
• It can be capable to detect fire and explosions within 3-4 millisecond, a time
delay of 2-3 seconds
• Flame Sensor uses a Light Dependent Resistor (LDR) for sensing Flame.
• The Flame sensor essentially senses the "Light" emitted by lame.
• It is usually suited only for oil burners in Boilers.
• It is not suitable for Furnaces, where background fefractory brich glows.
• These sensor senses all types of light, including Sun light and rays emitted
by electric bulb tube light
13. IGINATION TRANSFORMER
Step up transformer-Input=220v, Output= 14.5KV
ignites the fuel spray to nozzle tip.
• Supply is given to the ignition transformer through
the sequence controller.
• Output having high tension cable to the burner
ignition electrodes having
air gap of 5-6 mm.
• The high voltage generates the spark at the
electrodes tip to establish flame.
14. AIR PRE HEATER
• Installed between boiler and chimney.
• Utilize the heat of the flue gases in
preheating of combustion air.
• Inlet air can be heated up to 110° C.
• Increases the boiler efficiency by 4%.
Air Preheaters (APH) is the Shell and tube type Heat Exchangers used for preheating
the air which is fed to the boiler or furnaces/kilns for combustion of fuels. Air Pre
heater's primary objective is to extract the waste heat from the flue gases leaving
the boiler.
The purpose of the air preheater is to recover the heat from the boiler flue gas which
increases the thermal efficiency of the boiler by reducing the useful heat lost in the
flue gas. It also allows control over the temperature of gases leaving the stack.
15. SEQUANCE CONTROLLER
Model :- 107-S-FO (Controller for Furnace Oil)
False Flame Check:
If the flame is sensed during Steps I and II, all outputs are shut off. The Lock Out
terminal (13) is energized for Alarm Annunciation. Manual RESET is required to
restart the Sequence.
Unsafe Operating Conditions (Safety Loop OPEN):
The Safety Loop is typically formed by connecting Pressure/ Temperature switch
contacts in series across Terminals 6 and 7. The contacts MUST BE POTENTIAL FREE.
Mains supply is provided internally by the Sequence Controller.
If the Safety Loop is OPEN at the end of Step I OR at any time during normal operation,
then all circuits are turned OFF except the Blower. The Blower is turned OFF after a Post
Purge time of 15 seconds.
The Sequence Controller now waits for SAFE operating conditions to return and starts
the sequence from Step II. During the wait period the RUN indicator is ON.
17. BOILER OPERATION SEQUANCE
Step No Time in Secs* Operation Term Sequence controller Ref.
Step-1 t = 0 Run Indicator ON (3)
Blower ON (8)
Step-2 t = 1 Oil Pump ON (9)
Ignition ON (10)
Step-3 t = 1 + 30 Main Solenoid valve OPEN (11)
Setp-4 t = 1 + 30 + 7 High Flame valve OPEN (12)
Ignition OFF (10)
18. FLOAT SWITCH AND MAGNETIC FLOAT SWITCH
Float Switch :-
A float switch detects the level of a liquid in a tank or container. It floats on top of the
liquid surface and acts as a mechanical switch as the liquid level goes up or down .
Magnetic Float switch :-
A float switch is a device used to sense the level of liquid within a tank. When the float ball
rises or falls with the liquid to the level of the switch, The magnetic force of magnet which
inside of the float ball will cause the reed switch to turn ON .
19. MOBERY SWITCH
• Make top mounted float operated level transmitters or level transducers are used
to measure the level of a liquid or bulk solid material (as well as slurries) within a
specified space, and to provide electrical output about these measurements that
are proportional to the input level.
• Level transmitters are designed to measure level based on either a point level or
continuous level readings. Point level transmitters provide output when a specific
level measurement is reached.
• This output is generally in the form of an audible alarm or an electrical charge to
actuate a switch. Multiple point level transmitters can be integrated together to
give a stepped version of continuous level. Continuous level transmitters, measures
level within a specified range and provide output as a continuous reading of the
level. Level transmitters can operate through a wide range of temperatures,
pressure, vapor gas mixtures, and process conditions
20. BOILER SAFETY VALVE
MAKE -M/S.FAINGER LESER VALVES (P) LTD
TYPE -- SPRING LOADED
NOZZLE -- A-351 CF8M - SS
DISC -- A-479 316 - SS
BONNET TYPE -- BONNET CLOSED
LIFTING LEVER -- PLAIN
BODY & BONNET MATERIAL -- SA216 GR. WCB
SPRING MATERIAL -- 1.8159 / 1.7102 / FDSiCr - CORBON STEEL
SET PRESSURE Kscg 12
In steam systems, safety valves are typically used for boiler overpressure
protection and other applications such as downstream of pressure
reducing controls. Although their primary role is for safety, safety
valves are also used in process operations to prevent product damage
due to excess pressure
24. PID CONTROLLER
• Completely Correspond to any kind of input signal like Thermo couple , RTDPT100, DC4
to 20ma, 0-5v.etc
• Satisfy any request for output mode like DC4-20ma, 0-5V, Voltage , current & the
relay output of capacity 8A.
• It provides with 3 features of controller , signal converter and alarm monitor .
• It can be change the signal of mV , V ,RTD to the output of voltage &Current 4-20ma
instead of the signal converter .
• Separately design for signal circuit and power circuit on PC board , effectively restrain
the external interference of electric wave .
25. PRINCIPLE OF OPERATION
• When water is heated, it increases in volume and becomes lighter. This warmer water,
now lighter, rises and the cooler water drops to take its place. The steam bubbles that
eventually form break the surface of the water and enter the steam space.
• The addition of tubes inside the drum containing the water increases the heating
surface. The heating surface is the part of the boiler with water on one side and the
gases of combustion on the other. By increasing the heating surface, more heat is
extracted from the gases of combustion by the surrounding water.
• This results in a more rapid water circulation and faster formation of steam bubbles.
When larger quantities of steam are released, the thermal efficiency of the boiler
increases. Thermal efficiency is the ratio of the heat absorbed by the water to the heat
supplied from the fuel.
• Modern fire tube boilers with improved design and heat transfer rates have achieved
thermal efficiency as high as 80% to 85%. Placing an internal furnace within the boiler
shell greatly increases the heating surface allowing for maximum absorption of heat
thus reducing the time to create steam.
26. BOILER OPERATION SEQUANCE AND INTERLOCKING
• Extra low water level
• Low water Level
• Steam Pressure High
• Stack Temp High
• Oil Heater controller
• Steam controller
• Oil Low temp controller
• Stack temp controller
Safety ok
1
2
3
4
5
1. FD Fan
2. Oil pump
3. Ignition Transformer
4. Main SOV
5. Photo cell
28. BOILER EFFICENCY
This is also known as input-output method due to the fact that it needs only the useful output (steam) and the
heat input (i.e. fuel) for evaluating the efficiency. This efficiency can be evaluated using the formula:
Boiler Efficiency = Heat Output / Heat Input
32. MAJOR SAFETY INTERLOCK OF BOILER
• OIL PUMP – OIL PUMP NOT START BOILER WILL TRIP OR WILL NOT START .
• LEVEL - IF WATER LEVEL IN STORAGE TANK IS LOW, EXTRA LOW , BOILER WILL TRIP .
• MOBERY - IF LEVEL INSIDE DRUM FALL BELOW SET POINT BOILER WILL TRIP .
• STACK TEMP – FLUE GASES RAISE ABOVE 270deg BURNER WILL TRIP .
• COMBUSTION AIR SWITCH INTERLOACK FOR COMBUSTION BLOWER .
• PRESSURE SWITCH - IF PRESSURE INSIDE THR DRUM IS HIGH ,BOILER WILL CUT OFF .
• PHOTO CELL – IF FLAME IS NOT GENRATED IN BURNER , BOILER WILL TRIP .
• MODULATION UNIT – IF MODULATION UNIT FEED BACK IS NOT RECEIVED , BOILER TRIP .
• OIL HEATER – OIL TEMPURATURE INTERLOCK FOR FIRING .
33. BOILER PERFORMANCE
Performance of the boiler, like efficiency and evaporation ratio reduces with time,
due to poor combustion, heat transfer fouling and poor operation and maintenance.
Deterioration of fuel quality and water quality also leads to poor performance of
boiler.
Efficiency testing helps us to find out how far the boiler efficiency drifts away from
the best efficiency.
Any observed abnormal deviations could therefore be investigated to pinpoint the
problem area for necessary corrective action. Hence it is necessary to find out the
current level of efficiency for performance evaluation, which is a pre requisite for
energy conservation action in industry.
Purpose of the Performance Test
• To find out the efficiency of the boiler
• To find out the Evaporation ratio
34. FACTOR AFFECTING BOILER PERFORMANCE
The various factors affecting the boiler performance are listed below:
• Periodical cleaning of boilers
• Periodical soot blowing
• Proper water treatment programmed and blow down control
• Draft control
• Excess air control
• Percentage loading of boiler
• Steam generation pressure and temperature
• Boiler insulation
• Quality of fuel
35. POWER SAVING FROM BOILER
Install economizer in Boiler for preheating feed water where in the temperature is raised
from 70 Degrees to 120 Degrees. This results in 3% saving in fuel and power .
Improve the efficiency of boiler by soot blowing and controlling excess air. This results in
2% increase in boiler efficiency. Always monitor the exit flue gas temperature, it should
be in the range of 170 degrees to 190 degrees.
Use variable speed drives on large boiler combustion air fans with variable flows .
Boiler steam condense water recovery system reduce water consumption .
Inspect oil heaters for proper oil temperature , Clean burners, nozzles, strainers, etc.
Improve oxygen trim control (e.g. -- limit excess air to less than 10% on clean fuels).
(5% reduction in excess air increases boiler efficiency by 1% or: 1% reduction of residual oxygen in
stack gas increases boiler efficiency by 1%.)
