Can You Show Me A Diagram Of How A Hot Cylinder Boiler Works?

There are many diagrams available on the internets which demonstrate the working of a Hot Cylinder boiler. The hot cylinder boiler also known as a fire-tube boiler is a kind of a boiler in which hot gases from the fire surpass from one end to another end via one or more tubes which are there inside the boiler.

It is said to be one of the two main kinds of boilers, the other one being water-tube boiler. A fire tube boiler is generally horizontal or vertical and is also at times referred to as "smoke-tube" boiler.

This kind of boiler was applied on nearly all steam locomotives, in the horizontal locomotive shape. It is also used on a large scale in the stationary engineering field, characteristically for low pressure steam application such as heating a building.

The Plain Cylinder Boiler

    The first real advancement in boiler design came about with the invention of the Plain Cylinder Boiler. It was a simple design and easily constructed.

    As its name implies, the Plain Cylinder Boiler is a long metal cylinder with conical (round) ends set horizontally in a brick work. Some of these boilers were 40 feet long. The cylinder was half filled with water and a fire ignited in furnace at one end.

    The fire and hot gasses are first channelled from the furnace or fire box along the bottom of the cylinder to the opposite end of the boiler. This channel is called a "flue" and is made of brick on three sides. The other side of the flue is the metal wall of the boiler. The flames and hot gasses touch the bare metal and heat the water inside the boiler.

    When the hot gasses get to the end of the first flue, they are channelled back along one side of the cylinder to the front of the boiler. From there they are again channelled back along the other side of the cylinder to the chimney. This would give a boiler 40 feet long 120 feet of heating surface.

    The speed with which the fuel burned was controlled by a damper near the chimney. Raising or lowering the damper controlled the draught or amount of air being drawn into the furnace. More air made the fuel burn faster and hotter making more steam. Less air saved fuel and produced less steam.

    Although this boiler design was far more efficient than previous boilers, and had been used for more than one-hundred years, it had two major flaws. The first was dirt. Water, especially Mississippi River water, contained dirt and this dirt remained in the boiler after the water evaporated. After a time, this dirt collected in the bottom of the cylinder and acted like an insulator preventing the heat from reaching the water. This means that more fuel had to be burned to get the same amount of steam. It also meant that the boiler had to be cleaned out very often.

    The second flaw was more dangerous. As the hot gasses travelled along the 120 foot long flue, they cooled somewhat. Not much but enough to cause the metal of the cylinder was heated to different temperatures on either of the three sides. This uneven heating of the metal caused great stress within the metal which often led to the cylinder exploding.