Safety is always a top priority when working with industrial boilers, at least it should be. Fortunately, safety has become less of an issue with more modern water tube boilers. Compared to traditional fire tube boilers, water tube boilers are far safer, almost to the point where you don’t have to worry about a catastrophic explosion taking place.
Boilers with low water volumes require a minimum flow requirement to prevent localized boiling and subsequent heat exchanger damage in a low to zero water flow situation. Minimum flow requirement varies by boiler design. Regardless if a boiler itself has a minimum flow requirement, every hydronic heating system needs to be designed to carry the energy being created away from the boiler to avoid high temperature shut down.
The choice between a steam system or a thermal fluid system is governed by the process requirements. The range or process temperature is a deciding factor. If the system’s required temperature is above the freezing point of water (0°C) and below approximately 160°C, the choice is usually steam. However, if the required temperature is above 160°C, thermal fluid may be a better solution. Thermal oil heater systems can be designed with maximum operating temperatures to 325°C.
A fire tube steam boiler is a boiler where the combustion gases from the burner are channeled through tubes that are surrounded by the fluid to be heated. The boiler body is the pressure vessel and contains the fluid. In most cases, this fluid is water that will circulate for heating purposes or become steam for use in processing.
Each set of tubes through which the combustion gas passes, before making a turn, is considered a "step". Consequently, a three-step boiler will have three sets of pipes with the outlet located at the rear of the boiler.
In a water tube steam boiler, unlike a fire tube, water circulates inside the tubes. The heat that is generated and the combustion gases that surround the tubes heat the water that circulates inside them. Many water-tube boilers operate according to the principle of natural water circulation.
The capacity of this type of boiler can be enhanced by increasing the number of tubes in the boiler.
The action of starting up a fire tube boiler for the first time is already a cold start. As a result, the mechanical load in this type of boiler is much greater, as the main characteristic of cold starts is the absence of boiling water and greater stress on the connection and anchorage elements of the boiler.
To make this start a bit easier for the boiler, the boiler operator should reduce the burner load to a boiling point.
In superheated industrial water boilers, the water is pressurized and boiled to 100°C producing steam. These boilers are pyrotubular, with a high volume of water and a large temperature exchange zone. The designs can adapt to temperatures and pressures according to needs.
