What are steam boilers?

Steam production equipment

As we discussed in our article on steam, boilers are equipment specifically designed to produce the precious and essential steam for industries.

In this equipment, heat from any form of energy (e.g. gaseous fuels, liquids, biomass, etc.) is used to convert water from a liquid to a gaseous state and then transport the energy to the consuming equipment.

Therefore, in short, a boiler is a type of heat exchanger.

Parts of a boiler

The basic problem in the design of a boiler is to arrange the total heat absorption surface in such a way that the heat extraction from the heat input used, i.e. the fuel, is optimized as much as possible.

It is therefore important to obtain the highest possible yield at the lowest possible cost.

To obtain an economically optimal design, all parts of the boiler must be carefully dimensioned so that the overall design is balanced.

In general, the parts of a boiler include:

• The pressurized body itself
• Home
• Gas or fluid tubes
• The combustion equipment
• The ash collection and transportation system, if available
• The water supply system
• The purge system
• Regulation and control accessories.
• Safety accessories

Although the pressure parts of the boilers (bottoms, tube sheets, manifolds, tubes, casings, tie rods, etc.) are sometimes highlighted as the most important, we must not forget that all parts are important and that, in order to avoid failures, all boiler operations must be carried out with precision, safety and the utmost care.

Heat sources

In boilers, heat can be obtained from different sources:

• Combustion of fuels (solid, liquid or gaseous)
• Fluids resulting from an industrial process
• Electric power
• Nuclear energy
• Etc

Depending on the heat source, the transmission of heat to the medium contained in the boiler will be by radiation, convection, conduction or a combination of the three systems.

The direct heating surface consists of all those surfaces that are in contact on the one hand with the flame, with the products of combustion or heat transfer fluids, and on the other hand with the liquid or steam contained in the boiler.

A distinction must be made between the radiation surface and the convection surface. Following what was explained above about the different heat transfer systems, the radiation surface will be all that which is in direct contact with the flame obtained in combustion or in contact with high temperature gases.

The convection surface will be any surface that is in contact with the gases resulting from combustion, generally outside the firebox.