What type of steam generators are classified as large steam generators?

The classification of large steam generators primarily refers to their design and operational characteristics. Water tube type steam generators are recognized as large steam generators because they can handle higher pressures and larger volumes of steam compared to other types.

In water tube boilers, water circulates through tubes that are heated externally by combustion gases. This design allows for efficient heat transfer and the ability to produce steam quickly and in large quantities. They are particularly effective in industrial applications where large amounts of steam are required, allowing for larger boiler sizes and higher efficiency.

Additionally, water tube boilers can operate at higher pressures due to the design constraints of the tubes, making them suitable for utility and large-scale power generation. This capability aligns with the operational demands of facilities needing significant steam output for energy production or heating processes.

Conversely, fire tube boilers, while also used for steam generation, are typically smaller and less capable of producing large volumes of steam due to their design. Single pass types and electric types serve different applications and do not match the capacity of water tube boilers for large-scale steam generation. Therefore, water tube type is correctly identified as the classification of large steam generators.