In a bottom-supported boiler, how is the steam drum usually supported?

In a bottom-supported boiler, the steam drum is typically supported by the water tubes, which are integral to the boiler's design and functionality. This method of support is effective because the water tubes not only carry water and steam but also provide structural integrity to the steam drum. The water tubes are designed to withstand pressure and temperature changes, enabling them to support the steam drum securely.

This configuration allows for a compact design, as the steam drum is positioned high enough to facilitate steam separation while still relying on the strength of the water tubes to hold it in place. The system also facilitates proper flow and circulation of the water and steam, essential for efficient boiler operation.

Other support methods, such as using overhead girders or piers, could complicate the boiler system and are not typically utilized in this straightforward design. Additionally, supporting the steam drum between the center line of the unit might not provide the necessary structural support or stability required for safe and effective operation.