1. Definition of Boilers Boiler
Vessel that heats water to become hot water or steam
At atmospheric pressure water volume increases 1,600 times
Hot water or steam used to transfer heat to a process

2. Types of Boilers Fire Tube Boiler Water Tube Boiler Packaged Boiler
Fluidized Bed (FBC) Boiler
Stoker Fired Boiler
Pulverized Fuel Boiler
Waste Heat Boiler
Thermic Fluid Heater (not a boiler!)

3. Boilers for Various Applications

4. Boilers Babcock and Wilcox Benson Cochran Cornish Lamont Lancashire
Stirling
Velox

5. Boilers based on Firing
1. Fire Tube Boiler is
Relatively small steam capacities (12,000 kg/hour)
Low to medium steam pressures (18 kg/cm2)
Operates with oil, gas or solid fuels
To begin with, we will look at the fire tube boiler:
This is generally used for relatively small steam capacities and at low to medium steam pressures.
The steam rates for fire tube boilers are up to 12,000 kg/hour with pressures of 18 kg/cm2.
Fire tube boilers can operate on oil, gas or solid fuels.
The figure illustrates how a fire tube boiler works. The fuel is burned and heats up the water to steam which is turn channeled to the process. Today, most fire tube boiler are in a packaged construction for all fuels.
(Light Rail Transit Association)

6. Type of Boilers 2. Water Tube Boiler is
Used for high steam demand and pressure requirements
Capacity range of 4,500 – 120,000 kg/hour
Combustion efficiency enhanced by induced draft provisions
Lower tolerance for water quality and needs water treatment plant
In a water tube boiler, boiler feed water flows through the tubes and enters the boiler drum. The circulated water is heated by the combustion gases and converted into steam at the vapour space in the drum. These boilers are selected when the steam demand as well as steam pressure requirements are high as in the case of process cum power boiler / power boilers.
Most modern water boiler tube designs are within the capacity range 4,500 – 120,000 kg/hour of steam, at very high pressures. Many water tube boilers are of “packaged” construction if oil and /or gas are to be used as fuel. Solid fuel fired water tube designs are available but packaged designs are less common.
The features of water tube boilers are:
Forced, induced and balanced draft provisions help to improve combustion efficiency.
Less tolerance for water quality calls for water treatment plant.
Higher thermal efficiency levels are possible
(Your Dictionary.com)

7. Assessment of a Boiler Heat Balance
Balancing total energy entering a boiler against the energy that leaves the boiler in different forms
12.7 %
BOILER
Heat loss due to dry flue gas
8.1 %
Heat loss due to steam in flue gas
100.0 %
1.7 %
Heat loss due to moisture in fuel
Heat balance is an attempt to balance the total energy that enters a boiler against the energy that leaves it. This figure illustrates the different typical losses that occurs while generating steam.
(Question) Does anyone have any suggestions of what the two major heat losses are? (Discussion)
(Click once and answer reveals) They are dry fly gas that represents a heat loss of 12.7% and heat loss as a result of steam in the flue gas of 8.1%.
(Click once for other heat losses to appear) Other heat losses are due to moisture in the fuel and in the air, as well as unburnts in residue and radiation.
(Click once) This leaves 73.8% of heat that goes to steam.
Fuel
0.3 %
Heat loss due to moisture in air
2.4 %
Heat loss due to un-burnts in residue
1.0 %
Heat loss due to radiation & other unaccounted loss
73.8 %
73.8 %
Heat in Steam

8. Mountings and Accessories
Fitting and devices which are necessary for the safety and control are knows as boiler mountings
Fitting or devices which are provided to increase the efficiency of the boiler and help in the smooth working of the plant are knows as boiler accessories

10. Fittings - Safety Water level indicators Safety valves
Combined high steam and low water safety valve
Fusible plug

11. Fittings - Control Pressure gauge Junction or stop valve
Feed check valve
Blow-off cock
Man hole and Mud Box