MECHANICAL THEORY

High-Pressure Boilers: Benson Boiler, Lamont Boiler-Working, Adv&Disadv

High-Pressure Boilers: Benson Boiler, Lamont Boiler-Working, Adv&Disadv: In this article, we can discuss Benson Boiler, Lamont boiler along with working, components and construction which comes under High-Pressure boilers.

High-Pressure Boilers: The unique features of the high-pressure boiler are as follows.

  1. Method of water circulation
  2. Type of tubing and drums
  3. An improved method of heating

The explanation of the above features is as follows.

1.Method of water circulation:

The circulation of water through a boiler may be natural or Forced type. In all modern high-pressure boiler plants, water circulation is with the help of Pump i.e. by means of Forced Circulation.

2.Type of tubing and drums:

To avoid large resistance to the flow of water, these boilers have a parallel set of an arrangement of tubes.

high-pressure boilers are characterized by the use of very small steam separating drum or by a complete absence of any drum.

3.An improved method of heating:

Above the critical pressure, Saving of heat takes place by the evaporation of water.


Benson Boiler: Explanation, Working, Advantages:

Explanation of Benson Boiler:

In the Lamont boiler, the main difficulty experienced is the formation and attachment of bubbles on the inner surface of the heating tubes. The attached Bubbles to the tube surfaces reduce the heat flow and steam generation, as it offers high thermal resistance than Water film.

Benson in 1922, argued that, if the boiler pressure was raised to critical pressure, the steam and water have the same density and therefore, the danger of bubble formation can be eliminated.

The Benson boiler also makes use of forced circulation but has a unique characteristic of the absence of the steam separating drum. Its main principle is that, at the critical pressure, the steam and water coexist at the same density and heat is zero.

The water thus transforms into steam, without boiling and passes quickly from liquid to Vapor, without changing in volume.

The figure above shows the representation of a Benson boiler.

BENSON BOILER
BENSON BOILER

Working of Benson Boiler:

The components of Benson boiler is as follows.

  • Feed Pump
  • Economizer
  • Radiant Parallel tube section
  • Transit section
  • Convection Superheater
  • Steam to the prime mover

The working of Benson boiler w.r.t. the above components are as follows.

Firstly, The feedwater passes through the economizer.The function of Economizer is to increases the temperature of the feedwater(preheating) by absorbing the heat from the flue gases before they are sent to the atmosphere.

The feed water after circulation through the economizer flows through the Radiant parallel tube section to evaporate partly.

The steam-water mixture produced then moves to the transit section where this mixture is converted into steam.

The steam is now passed through the Convection superheater and finally supplied to the prime mover in order to drive the turbine.

Advantages of Benson Boiler:

  • It can be erected in a comparatively small floor area.
  • It is light in weight and hence the low cost of the boiler.
  • It can be started very quickly due to welded joints
  • Transfer of parts is easy as no drums are required.
  • The explosion hazards are less as it has only tubes of small diameter and has less storage capacity.

As superheater is an integral part of the process circulation system, no special starting arrangement for superheating is required

depending on the size and pressure required the boiler can be put into service within 10 to 15 minute


Lamont Boiler-Construction, Explanation, Working, Advantages and Disadvantages:

What is a Lamont Boiler?

Lamont boiler is a high-pressure water tube boiler with internally fired furnace and the circulation is of forced type. An external agency(pump) is used to circulate throughout the tubes of the boiler. This boiler was invented in 1925 by the famous person Walter Douglas La-Mont.

Construction of Lamont Boiler:

The Lamont boiler consists of the following parts.

  • Feed Water
  • Feed Pump
  • Economizer
  • Steam separating Drum
  • Radiant Evaporator (Tube Evaporating section)
  • Superheater

Explanation of Lamont Boiler:

This Lamont boiler works on the concept of forced circulation i.e. by the application of pump, the water is sent to various sections of the boiler unit and the circulation is maintained by means of a centrifugal pump which is driven by a steam turbine.

In this case, the steam from the boiler is used to drive a turbine and generate electricity or for doing any mechanical work.

And for emergency purpose, the pump which is driven electrically was also installed.

lamont boiler
Lamont boiler

Working of Lamont Boiler:

The feedwater passes through the economizer to the drum from which it is drawn by the circulating pump.

The function of Economizer is to increases the temperature of the feedwater(preheating) by absorbing the heat from the flue gases before they are sent to the atmosphere.

The centrifugal pump delivers the feed water to the evaporating section or the Radiant Evaporator which in turn sends a mixture of steam and water to the drum.

The steam generated by the radiant evaporator is the saturated steam. If it is directly used in the steam turbine, it can cause the blades by the effect of corrosion. So the saturated steam sends to the superheater where it can increase the temperature of the steam.

The superheated steam obtained from the superheater is supplied to the prime mover or turbine to do the mechanical work and later this work is to be converted to Electrical energy.

These boilers have been built to generate 45 to 50 tonnes of superheated steam at a pressure of 130 bar and a temperature of 500-degree centigrade.

This is the explanation of the Lamont Boiler.

Advantages of the Lamont Boiler:

  • It has a high heat transfer rate.
  • Its design is simple.
  • It can be easily started.
  • High steam generation (about 50 tonnes per hour)
  • Can be reassembled with the natural circulation boilers.

Disadvantages of the Lamont Boiler:

Bubble formation on a surface of the tube reduces the heat transfer rate.

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