How many positions can a soot blower's revolving arm take during operation?

A soot blower's revolving arm is designed for efficient operation in various industrial applications, particularly in power generation and refining processes. The correct answer is that the revolving arm can take a full rotation of 360 degrees. This capability allows the soot blower to effectively clean the surfaces of heat exchangers and boilers by reaching and clearing away accumulated soot and other deposits from multiple angles.

The design of the soot blower incorporates a full circular movement, enabling it to maximize its cleaning coverage and efficiency. A complete 360-degree rotation ensures that the arm can extend to every necessary position required for thorough cleaning, making it an essential feature for maintaining optimal equipment performance.

In contrast, the other answer choices, such as 180 degrees or 120 degrees, would limit the functionality of the soot blower, as they do not provide the necessary range to cover all areas that require maintenance. A limit of 900 degrees is not practical, as it exceeds the full circle and does not correspond to typical mechanical design for such devices. Thus, understanding the 360-degree rotation is crucial for the effective operation of a soot blower in industrial settings.