What Is LaMont Boiler?- Parts, Working and Uses

What is LaMont Boiler?

A LaMont boiler is a type of forced circulation water-tube boiler in which the boiler water is circulated through an external pump through long closely spaced tubes of small diameter. The mechanical pump is employed in order to have adequate and positive circulation in steam and hot water boilers.

Martin Benson was the first to work on the idea of forced circulation drum boilers. In 1918, Walter Douglas La Mont [de] brought the forced circulation boiler from concept into existence. La Mont was a Lieutenant Commander and an engineer in the US Navy. He died of a heart attack in 1942 in New York.

La Mont’s initial designs confirmed the lighter, safer, and higher rates of heat transfer and evaporation per square foot as compared to that of the standard water tube boilers, also the circulation of vaporized water at a differential pressure of 2.5 bar was 8 to 10 times greater.

The time needed for a La Mont Boiler to be able to deliver an evaporation rate of 100,000 pounds per hour was between 15 and 20 minutes. During World War II the U.S. Navy mainly relied upon Babcock & Wilcox boilers which were used commonly at the time. On the other hand, thousands were built in Europe and several German and Japanese ships used La Mont boilers.

Parts Of Lamont Boiler

These are the main parts of the Lamont Boiler:

LaMont Boiler
  1. Feed Pump: Feed Pump supply water into the boiler from hot well.
  2. Economizer: Economizer is used to increase the temperature of feed water to some extent.
  3. Centrifugal Pump: Centrifugal pump is used to circulate water inside the Lamont Boiler as it is a forced circulation boiler. The pump is driven by a steam turbine and the steam for this turbine is taken by the boiler. This boiler uses its own steam to drive its pump that circulate water in it.
  4. Steam Separating Drum: Role of this part of Lamont Boiler is indicated by its name. It separates steam from water.
  5. Super Heater: Steam generated from the evaporator is saturated steam and if used in steam turbine can cause corrosion on the turbine. So, the saturated steam is sent to the super heater where it converts into superheated steam and this superheated steam is sent to turbine.
  6. Radiant Evaporator: Radiant Evaporator heats the water with help of radiation. It is located near furnace.
  7. Convective Evaporator: Convective Evaporator is located above the Radiant Evaporator. It heats the water by convection process.
  8. Air preheater: Air preheater is present near the top of the Lamont Boiler. Its main function is to improve thermal efficiency of boiler by preheating the air from coming from the blower and this preheated air is sent to the furnace.
  9. Blower: It blows the air into the air preheater which further is sent to furnace to increase the efficiency of boiler.


The circulation of water and steam mixture takes with the help of an external pump which supplies water at a higher pressure than in a natural circulation boiler.

Working Of LaMont boiler

A centrifugal pump that forms the heart of this boiler is responsible to circulate water within the boiler system. It receives water from the drum and delivers this water to a distribution header as shown in the diagram here. The number of headers may differ in numbers and depends on the size and boiler design of each boiler.

The boiler heating surfaces include a number of tubes arranged in a parallel form and the inlet ends are welded to the distributors or the headers. A circulation pressure is to be provided during the installation of the pump as per the boiler design and it should be sufficient to overcome the resistance offered by the tubes.

An even circulation takes place with the help of the inlet nozzles provided at the inlet of tubes which creates the differential pressure adequate to cover the variations occurring at fluctuating loads or uneven firing conditions. The riser tubes outlet is welded to the collector headers and also directly to the drum containing steam and water.

Features of Lamont Boiler

  • An advanced steam circulation and water circulation system exist.
  • It has excellent tubing process.
  • The boiler has an advance heating process.

Advantages of Lamont Boiler

  • This boiler can be started easily.
  • It transfers the heat at a higher rate.
  • The Lamont boiler has a high steam generation capacity of about 50 tons/hour.
  • It can be easily reassembled with the natural circulation boiler.
  • Simple in design.
  • It is a high-pressure boiler.

Disadvantages of Lamont Boiler

  • The bubbles are formed on the surfaces of the tubes in this boiler.
  • This decreases the heat transfer rate for steam.