What is Babcock and Wilcox Boiler?
The Babcock and Wilcox boiler is also is known as Longitudinal Drum Boiler or Horizontal Tubes Boiler it is a water tube boiler in water tube boiler water remains inside the tube and hot gases are remains outside the tubes.
This type of boiler is generally used to produce high-pressure steam. In 1867, in Providence, Rhode Island, residents Stephen Wilcox and his partner George Herman Babcock patented the Babcock & Wilcox Non-Explosive Boiler, which used water-filled tubes and de-nucleate boiling to generate steam more safely than either under-fire or fire-tube boilers.
Babcock and Wilcox Boiler Parts
A Babcock and Willcox Boiler Parts or Construction consists of:
- Drum: This is a horizontal axis drum which contains water and steam.
- Water tubes: Water tubes are placed between the drum and furnace in an inclined position (at an angle of 10 to 15 degrees) to promote water circulation.
- Uptake and Down take Header: This are present at the front end of the boiler and connected to the front end of the drum. It transports the steam from the water tubes to the drum. And This is present at the rear end of the boiler and connects the water tubes to the rear end of the drum. It receives water from the drum.
- Grate: Coal is fed to the grate through the fire door.
- Furnace: The furnace is kept below the uptake-header.
- Baffles: The fire-brick baffles, two in number, are provided to deflect the hot flue gases.
- Superheater: It increases the temperature of saturated steam to the required temperature before discharging it from the steam stop valve.
- Mud Box: This is used to collect the mud present in the water. Mud box is provided at the bottom end of the down-take header.
- Inspection Door: Inspection doors are provided for cleaning and inspection of the boiler.
- Water Level Indicator: The water level indicator shows the level of water within the drum.
- Pressure Gauge: The pressure gauge is used to check the pressure of steam within the boiler drum.
Working of Babcock and Wilcox Boiler
The working of Babcock and Wilcox boiler is first the water starts to come in the water tubes from the drum through down take header with the help of a boiler feed pump which continues to feed the water against the drum pressure.
The water present in the inclined water tubes gets heated up by the hot flue gases produced by the burning of coal on the fire grate. These fuel gases are uniformly heated in the water tube with the help of a baffle plate which works to deflect the flues gas uniform throughout the tubes which absorbed the heating maximum from the flue gases.
As the hot flue gases come in contact with water tubes, it exchanges the heat with the heater and converts into steam. Continuous circulation of water from the drum to the water tubes and water tubes to the drum is thus maintained.
The circulation of water is maintained by convective current and it’s known as Natural Circulation. The Steam generated is moved upward, due to density difference and through the up-take header, it gets collected at the upper side in the boiler drum.
Anti-priming pipe inside the drum which works separates the moisture from the steam and sends it’s to the superheater. The superheater receives the water-free steam from an anti-priming pipe. It increases the temperature of the steam to the desired level and transfers it to the main steam stop valve of the boiler.
The superheated steam stop valve is either collected in a steam drum or send it’s inside the steam turbine for electricity generation.
Babcock And Wilcox Boiler Features
- The Steam generation capacity and operating pressure are high compared with fire tube boilers.
- In of Babcock and Wilcox Boiler components are accessible for inspection even during the operation
- Overall efficiency of of Babcock and Wilcox Boiler is higher than a fire tube boiler.
- The draught loss inside the furnace is minimum compared with another boiler.
- Damage tubes can be replaced easily in this type of boiler.
- Babcock and Wilcox Boiler tubes are kept inclined at an angle of 10 to 15 degree to promote water circulation.
- The boiler rests over a steel structure independent of brick work so that the boiler may expand or contract freely. The operating pressure lies between 11.5 to 17.5 bar.
Application of Babcock and Wilcox Boiler
The Babcock and Wilcox boiler is generally used to produce high-pressure steam in power generation industries. The high-pressure steam so generated is used to produce electricity.
Advantages of Babcock and Wilcox Boiler
- Steam generation capacity is higher than fire tube boiler It is about 2000 to 40000 kg/hr.
- Babcock and Wilcox Boiler occupied less area
- Defect can be attended easily. Babcock and Wilcox Boiler: only boiler that is used to generate large quantity of heat in power stations.
- The draught loss is minimum inside the furnace
- Inspection can be made easily during operating condition
Disadvantages of Babcock and Wilcox Boiler
- Babcock and Wilcox Boiler is high maintenance cost.
- Babcock and Wilcox Boiler is not much suitable for impure and sedimentary water. In case of impure and sedimentary water, it causes scale formation and may deposit in the tubes and this leads to overheating and bursting of tubes,