The disclosure is directed to a saturated water spraying system configured to rapidly respond to rapid load changes by implementing a single integrated DCS control block. The integrate DCS control block may include a plurality of process control routines that are necessary to control the operation of the spraying system. For example, upstream and downstream PID control routines may determine and output control variables, and other control routines may be provided as necessary to handle disturbances within a boiler affecting the outlet and spray steam temperatures, and to ensure that the steam temperatures do not fall into the saturation region during operation of the boiler. Because the routines are part of the same control block, the common storage for the control block may be accessed by each of the routines without the necessity of establishing additional communication links for transferring the information as is required when using cascaded function blocks.