Question

In boilers equipped with multiple nozzle burners for high-low firing, what are the functions of the two pressure controls, namely the "operating limit pressure control" and the "high-low fire control," and how do they operate in relation to the burner's firing rate?

Answer 1

The operating limit pressure control sets the maximum safe boiler pressure and shuts off the burner when this limit is reached, while the high-low fire control adjusts the burner's firing rate to meet steam demand efficiently.

Step-by-step explanation:

In boilers with multiple nozzle burners that utilize high-low firing techniques, the operating limit pressure control and high-low fire control are essential in regulating the firing rate and maintaining efficiency and safety within the boiler system. The operating limit pressure control is designed to set the maximum pressure at which the boiler can safely operate. When the pressure in the boiler reaches this set point, the control will shut off the burner to prevent excessive pressure build-up which could lead to equipment damage or hazardous situations.

The high-low fire control works to adjust the burner's firing rate. During periods when less steam is needed, the control will switch the burner to a lower firing rate, thus conserving fuel while still maintaining the required pressure and steam output. Conversely, when more steam is required, the control switches the burner to a higher firing rate, ensuring that the boiler can meet the demand for steam. Both controls work together to maintain an efficient and safe operation of the boiler, responding dynamically to the system's requirements and preventing any potential overpressure conditions.