What is the most common method used to increase steam pressure in a boiler?

The most common method used to increase steam pressure in a boiler is through the adjustment of gas pressure. In a high-pressure boiler, the combustion process is key to generating steam. Increasing the gas pressure enhances the efficiency and intensity of combustion, resulting in a higher temperature and pressure of the steam produced.

When fuel gas is delivered at a higher pressure, it allows for a more complete and rapid combustion process. This increased energy input directly correlates with a rise in steam pressure, making it a critical operation in maintaining the required pressure levels for efficient boiler operation.

Using gas pressure is particularly effective because it influences the heat release rate, enabling better control of boiler output. In this context, the other methods, such as increasing water temperature, reducing outlet size, and adjusting feed water flow, do not directly influence steam pressure in the same way. These actions may affect overall boiler efficiency or steam quality but do not serve as the primary means of raising steam pressure.