The Modulatic® Steam Generator is a once through watertube boiler with a positive displacement pump to provide a constant supply of feedwater. The burner management system controls the amount of feedwater admitted to the coils by regulating the speed of the pump, based on the steam pressure set point compared to the actual reading.
The fuel-air ratio curve changes the amount of fuel and combustion air in direct proportion to the flow of water being sent to the coils. Dry steam is then produced in the steam separator where approximately ninety percent of the water is converted into steam. The water remaining is removed by a steam trap.