Boiler Mounting and Accessories

Boiler Mountings-

1. Water level indicator
2. Pressure gauge
3. Safety valves
4. Stop valve
5. Blow off cock (Blow off valve)
6. Feed check valve

Boiler Accessories-

1. Air pre-heater
2. Superheater
3. Feed pump

Boiler Mountings

Water level indicator- 

• Water level indicator is used to check the instantaneous water level present in the boiler
• The construction of the water level indicator is like a glass manometer.
• It is fitted in front of the boiler and generally presents two in number.
• Some small steel balls are provided in the path of water opening because of opening water flows at high velocity.

Pressure gauge-

• The pressure gauge is used to measure the pressure of steam leaving the boiler 
• It is also present in front of the boiler.
• The pressure gauge is made of the bourdon tube.

Safety valves-

• The main function of the safety valve is to exhaust all steam in case of an explosion.
• It always takes care of the internal steam pressure if it exceeded then the safety valve opens the valve to prove a path to release the pressure
• Generally, two safety valves are present on a boiler.

Stop valve-

Stop valve isolates the steam boiler and its pressure from the process or plant.

i.e. it controls the flow of steam from the boiler.

Blow off a cock-

• It is fitted at the bottom of the boiler drum.
• The functions of blow-off cock are to discharge the scale, mud, and sediments which gets
• collected at the bottom of the boiler.

Feed check valve-

• The main feature of FCV is to prevent the backflow of water from the boiler in case of failure.
• It is fitted to the shell slightly below the normal water

 

Fusible plug-

• It is fitted to the crown plate of the furnace.
• It is a safety device which prevents the  level of water from going down from the critical level
• It is made from the material of a low melting point.

Boiler Accessories

Air pre-heater-

• It is a waste heat recovery device, It is used to recover heat from the exhaust gases
• The function of air preheater is to increase the temperature of the air before enters the furnace.
• It is generally placed after the economizer
• Preheated air accelerates the combustion and facilitates the burning of coal.

Superheater-

• The Steam Superheater is a coil type heat exchanger which is used to produce superheated steam or to convert the wet steam to dry steam, generated by a boiler.
• It is placed in the path of hot flue gases from the furnace.

Benefits of Superheaters in Boilers-

• Increase in efficiency of the steam power plant
• Minimized erosion of turbine blade
• Less steam consumption
• Reduction of condensation loss in the boiler steam pipes
• Increases the temperature of saturated steam by removing entrained water particles from turbines steam

Types of Superheater in Boiler

1. Radiant Superheater
2. Convective Superheaters

Economizer-

It is a device in which the waste heat of the flue gases is utilized for heating the feed water.

The exhaust from the boilers is generally in the temperature range of 200°C – 250°C, so there are a huge amount of losses from the boiler if any heat recovery devices are not installed after it.

Advantages -

• The temperature range between various parts of the boiler is reduced which results in the reduction of stresses due to unequal expansion.
• If the boiler is fed with cold water it may result in chilling the boiler metal.
• the Evaporative capacity of the boiler is increased.
• The overall efficiency of the plant is increased.