caldeiras

Caldeiras is a term in Portuguese that can refer to boilers—steam-generating pressure vessels used in heating and industrial processes—or to volcanic calderas, large depressions formed by the collapse of a volcano after an eruption. In industrial contexts, caldeiras are designed to produce steam for heating, power, or processing. They typically consist of a pressure vessel containing water, a heat source such as a burner, a heat exchanger, and safety and control systems to regulate water level, pressure, and steam quality.

Industrial caldeiras are commonly categorized by their heat transfer mechanism and construction. Fire-tube boilers have hot gases passing through tubes surrounded by water; water-tube boilers have water circulating through tubes heated by combustion, allowing higher pressures and capacities. There are also electric boilers and various fuels, including gas, oil, coal, and biomass, as well as waste-heat boilers that recover energy from other processes. Configurations can be horizontal or vertical, and capacities range from small domestic units to large industrial plants.

Operation and safety concerns focus on reliable fuel supply, combustion control, water chemistry, and steam quality. Critical safety devices include pressure relief valves, low-water cutoffs, and flame safeguard systems. Regular maintenance and inspections, water treatment, and energy-efficiency measures such as insulation and economizers are common requirements.

Applications of caldeiras span district heating, power generation, and industrial processes in chemical, food, paper, and manufacturing sectors. Marine boilers, used on ships, are another important subtype.

In geology, caldeiras denote volcanic calderas, large depressions formed by the collapse of a magma chamber following explosive eruptions. They may host lakes and later volcanic activity through resurgence or new vents. Caldeiras are monitored for deformation, gas emissions, and seismicity due to eruption hazards, with notable examples including Yellowstone Caldera in the United States and Furnas Caldera on São Miguel Island, Azores.