Auxiliary Boilers (D-type or cylindrical)

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Do you know the difference between D-type and cylindrical auxiliary (watertube) boilers?

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  1. D-type Boiler:
  • Structure: A D-type boiler has a design resembling the letter “D”, with two drums located at the top and bottom of the boiler connected by water tubes. The bottom drum, known as the water drum, is filled with water, while the top drum, the steam drum, is where steam is collected.
  • Operation: The combustion process occurs in the area between the drums, and the hot gases flow over the tubes, heating the water inside and producing steam. The steam rises into the steam drum, from where it is transferred to the piping system.
  • Efficiency: Due to the design and flow pattern, D-type boilers are generally highly efficient, capable of achieving very high pressure and temperature.
  1. Cylindrical Boiler (Fire-tube Boiler):
  • Structure: Fire-tube boilers have a cylindrical shape. They have a large number of tubes running through the boiler shell. The tubes are surrounded by water, and the combustion gases are passed through the tubes.
  • Operation: The heat from the combustion gases transfers through the walls of the tubes to the water, heating it and producing steam. This steam rises and collects at the top of the boiler before being transferred in the piping system.
  • Efficiency: These types of boilers are generally less efficient than water-tube boilers like the D-type. They’re easier to maintain due to their simpler design.
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