Boilers have many applications in industrial sector and hotel industry mainly for comfort and process heating. Boiler system consists of pressure vessel, piping, valves, operation and safety controls and pollution controls such as economizers or super heaters. Mainly industrial and other large scale boilers use oil or gas as fuel. In Sri Lanka furnace fuel is widely used as boiler fuel. Coal is also used in many countries while electricity is also used.
There are three major classes of boilers according to its output
1. Hot water
2. Low Pressure Steam (0 – 15 psi)
3. High Pressure Steam (> 15 psi)
Boilers also can be divided into two major categories by installation procedure.
1. Field – Erected - the custom made boiler system which can be installed in very flexible and suitable way to our requirements.
Advantage – Less operation cost, less maintenance, greater flexibility
Disadvantage – High initial cost
2. Shop Assembled – packaged boiler system which has few categories ac cording to some standard sizes.
Advantages – low initial cost and simple installation
Disadvantages – high operating cost, more maintenance, less flexibility
According to heat transfer method there are two major types of boilers
- Fire tube Boilers
- Water Tube Boilers
Fire tube Boilers
This type is often used for hot water and low pressure steam applications. In this configuration combustion gas and fire flames are flow thro’ tubes while water and steam contained in a large shell surrounds them.
2. Relatively Cheap
1. The output of the boiler is limited.
Water tube Boilers
In this type water flow thro’ tubes and tubes are heated from surrounding.
1. Large heating surface can be obtained
2. Heat transfer is efficient and high due to motion of water streams.
1. Scaling is highly occurred
2. More maintenance relatively to fire tube.