Steam Boilers

The use of steam as an energy carrier is particularly common in most of plants such as power stations, refineries and chemical plants. Steam boilers are also vital to the food industry, textile industry and many other industry sectors.
Steam boilers are used to create steam that has a higher steam pressure than atmospheric conditions. The boiling temperature and energy content of the steam also increase in addition to the pressure.
The various boiler types can be differentiated either by their design, combustion system or fuel type.
Steam boilers are found in nearly all areas of industry and there are primarily two types of steam boiler:

Shell boilers

Fire-tube boilers up to 25MW / 2500HP power and 25bar / 360psi pressure for hot water and steam applications represent the most commonly used type of boiler today. There are several designs, which are pretty much the same. The primary difference is how many times the flue-gases change direction inside the boiler and how many tubes there are. Boilers of the most common three-pass design feature two assemblies of tubes.
There is no turn at the rear of the furnace back to the door since the flue-gases pass into first tube assembly then turn 180° and enter the second tube assembly before exiting through stack.
The two-pass design is a single tube assembly. The flue-gases make a 180° turn at the rear of furnace back towards the door before entering the tubes and exhausting to the rear.

Water-tube boilers
Water tube boilers are usually used in large industrial and power generation situations where extremely high heat transfer rates are required to produce large quantities of steam. The water is heated in tubes and the fire (combustion process) is contained in the space around the tubes.
The watertube boiler design uses tubes to direct the boiler water through the hot gases from the combustion process, allowing the hot gases to transfer its heat through the tube wall into the water. The boiler water flows by convection from the lower drum to the upper drum.
Water tube type boiler systems are generally preferred in cases where fire tube type boilers cannot provide the required capacity, pressure and temperature and in applications that require rapid steam generation.

Water tube boilers are consisted of water tube panel walls. These walls are produced by in house automated panel wall welding machine with complete penetration and consisted of pipe-plate-pipe structure.