This factsheet considers steam boilers. Steam boilers are a widely used technology across all industry sectors. They generate steam, which may be used as a heat carrier, a carrier of chemicals or as a driver of a mechanical process via turbines. TNO (2019) estimates that 94% of the natural gas in the Dutch industry sector is consumed in natural gas boilers. Boilers can produce saturated steam, superheated steam or supercritical steam at increasing pressures and temperatures, depending on the requirements on the end-use side. Industrial boilers may have different purposes depending on the industries and facilities they are installed and may have a wide range of sizes. Industries with high steam demand, such as primary metals and pulp and paper, predominantly make use of large boilers, whereas more heterogeneous industries such as food processing and chemical manufacturing make use of both small and large boilers (Ecodesign, 2014).
The two most commonly used boilers are fire-tube boilers and water-tube boilers, which are described in this factsheet. In fire-tube boilers, hot gases pass through tubes that heat water in a shell. This water is converted into steam. Fire-tube boilers are competitive for relatively small steam capacities (<28,000 kg/hour) and low to medium steam pressures (<30 bars) (Ecodesign, 2014). In water-tube boilers, water flows through the tubes that enter a boiler drum, where it is heated by the combustion gases and converted into steam. Water-tube boilers can reach higher steam demands and very high steam pressures. Fire-tube boilers are more commonly used than water-tube boilers.
In 2019, natural gas was responsible for 188 PJ out of 420 PJ (45%) of the industrial heat demand in the Netherlands. The combustion of natural gas in boilers for own use is the main source of heat for the industry sector (ECN&CBS, 2020)