How does size of boiler relate to pressure?
Why not use a 50 cc two wheeler engine to drive an 80 ton Mach truck? It is horses for courses.
When you talk about a boiler's size, you are usually talking about it capacity to produce steam in pounds per hour. The capacity of a boiler is determined by the need of the system to produce steam. You can have a 100 psi boiler that produces 50,000 pounds of steam an hour or a 650 psi boiler that produced 50,000 pounds of steam an hour. In other words, the pressure and capacity are not linked.
only on as far that larger boilers will require stronger construction/ thicker materials compared with smaller boilers at the same pressure.
Two main factors determine boiler size. One, the steam flow rate that is needed for a process or electricity production, more steam, larger boiler. Two, the fuel (typically coal) may have a low heating value and a large boiler is needed to contain a larger hot gas space. For example, a lignite boiler (burning brown coal) can have almost twice the volume of a boiler burning bituminous coal (steam coal). These factors are independent of the pressure, although, for efficiency's sake, most companies building a large boiler will select the highest pressure that fits the type of steam cycle they design.
