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Doctors Medicines MCQs Q&A

  1. Babcock and Wilcox boiler
  2. Cochran boiler
  3. Lancashire boiler
  4. Pulverised fuel fired boiler
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1 Answers

Option 3 : Lancashire boiler

Explanation:

Lancashire boiler:

  • It is a stationary fire tube type, internally fired, horizontal, and natural circulation boiler.
  • The maximum working pressure in a Lancashire boiler is 16 bar.
  • It is used where working pressure and power required are moderate.
  • Its steam production rate is 9000 kg/hr. Its efficiency is from 50% to 70% depending upon the type of fuel used.
  • These boilers have a cylindrical shell of 1.75 m to 2.75 m in diameter. Its length varies from 7.25 m to 9 m.

  • This type of boiler is set in brickwork forming external flue so that part of the heating surface is on the external shell.

Babcock and Wilcox Boiler:

A high-pressure water tube boiler is a type of boiler in which water circulates in tubes heated externally by a fire.

Fuel is burned inside the furnace, creating hot gas which boils water in the steam-generating tubes.

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Cochran Boiler or Vertical Multi-tubular Boiler:

  • It is one of the most efficient type of such boilers.
  • The boiler consists of an external cylindrical shell and a fire box.
  • The shell and firebox both are hemispherical.
  • The hemispherical crown of the boiler gives maximum space and strength to withstand the pressure of steam inside the boiler.
  • The hemispherical crown of the box is also advantageous for resisting intense heat.
  • The combustion chamber is line with fire bricks.
  • A manhole near the top of the crown on the shell is provided for cleaning.

 

It is one of the best type of vertical multi tubular boiler, and has a number of horizontal fire tubes.

Dimensions, working pressure, capacity, heating surface and efficiency are given below.

Shell diameter

2.75 m

Height

5.79 m

Working pressure

6.5 bar (max pressure = 15 bar)

Steam capacity

3500 kg/hr (Max. capacity = 4000 kg/hr)

Heating surface

120 m2

Efficiency

70 to 75%

 

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