How are tube sheets supported in a fire tube boiler?

In a fire tube boiler, tube sheets are critical components that separate the combustion gases from the water. Their support is essential for maintaining the structural integrity of the boiler and ensuring safe and efficient operation. The correct method of supporting tube sheets involves the use of the shell, stays, and bolts.

The shell provides the primary structural support, acting as the main body that houses the boiler components. Stays are tension members that help in stabilizing the tube sheets against pressure forces; they prevent displacement or deformation during operation. Bolts serve to securely attach the tube sheets to the shell and maintain the necessary alignment and integrity under varying operational pressures and temperatures. This configuration effectively supports the tube sheets while allowing for the thermal expansion that occurs as the boiler heats up.

In contrast, other options may suggest components that are either not typically used for this specific application or do not provide the necessary support features needed for the tube sheets in a fire tube boiler. For instance, straps or frames might provide support but lack the specific function and effectiveness of stays and bolts in this context.