Along with steam pressure control loop and airflow control loop, which other loop is associated with the automatic boiler control system?

In an automatic boiler control system, the fuel flow loop is critical because it directly affects the combustion process. The fuel flow loop helps regulate the amount of fuel being supplied to the boiler based on the operational demands and conditions. By controlling fuel flow, the system can ensure that the correct fuel-air mixture is maintained for efficient combustion. This, in turn, helps to optimize steam generation and maintain the desired steam pressure.

In the context of the other options, while temperature flow, chilled water, and water level loops are important in various systems, they do not specifically relate to the direct control of fuel input into the boiler. The water level loop, for instance, is essential for maintaining the correct water level within the boiler to prevent issues such as overheating or damage, but it operates alongside rather than as a substitute for the fuel flow loop. Therefore, the fuel flow loop is essential for the effective management of an automatic boiler control system.