What is the most economical method for partially loading a small steam turbine?

The most economical method for partially loading a small steam turbine is to use the minimum number of hand-controlled steam nozzles feasible. This approach allows for precise control over the steam input and optimizes the use of available energy without wasting excessive steam or thermal energy. By carefully managing the number of nozzles in operation, the turbine can be adjusted to match the demand for power more closely, which helps in maintaining efficiency and reducing operational costs.

This method stands in contrast to other options. Operating the turbine at full capacity intermittently can lead to inefficiencies and increased wear on the system due to the frequent changes in load and the potential for thermal shock. Reducing the steam supply pressure may not be ideal, as it could negatively affect the turbine's performance and efficiency, leading to less effective energy conversion. Utilizing automatic control systems is beneficial, but they can sometimes introduce complexities and costs that may not align with the goal of maximizing economical operation for smaller loads, especially if manual control can achieve similar or better results in specific scenarios. Overall, the use of a minimum number of hand-controlled nozzles represents a straightforward and effective method for reducing operational costs while maintaining performance in a partially loaded scenario.