What is one consequence of a decrease in boiler firing rate?

The consequence of a decrease in boiler firing rate is indeed associated with the water level and boiling point dynamics within the boiler system. When the firing rate is reduced, the heat input into the boiler decreases, which leads to a lower rate of steam generation. As a result, the water level in the steam drum can increase because there is less steam being produced to occupy the space previously filled by water.

Additionally, a lower firing rate causes the water temperature to increase at a slower pace, which can initially increase the boiling point of the water due to the increased pressure in the system, but in practical terms, the relationship is influenced by the overall dynamics of the boiler and the saturation temperature of the steam at a given pressure. The changes in boiler operation can also result in a higher liquid volume for a given pressure condition, affecting the water level management as steam generation is reduced.

While the other options may relate to different operational conditions in a boiler, the increase in water level and changes in boiling conditions as a result of a reduced firing rate are directly relevant to how boiler systems manage heat transfer and steam production.