Method and apparatus for controlling a forced flow steam generator

Claim 1

METHOD FOR CONTROLLING A FORCED FLOW STEAM GENERATOR WHEREIN WATER IS SUPPLIED TO A TUBE SYSTEM INCLUDING AN EVAPORATING SECTION COMPRISING A PLURALITY OF TUBE LINES ARRANGED IN PARALLEL RELATION WITH RESPECT TO THE FLOW OF THE OPERATING MEDIUM AND WHEREIN THE WATER IS CONVERTED TO STEAM CONTAINING SOME WATER WHICH IS SEPARATED FROM THE STEAM IN A SEPARATOR DOWNSTREAM OF THE EVAPORATING SECTION, THE EVAPORATING SECTION INCLUDING A CONTROL TUBE LINE WHEREIN THE OPERATING MEDIUM IS SLIGHTLY THROTTLED AND WHICH DISCHARGES SLIGHTLY SUPERHEATED STEAM, THE METHOD COMPRISING MEASURING THE RATE OF FLOW OF WATER FED INTO THE TUBE SYSTEM AND PRODUCING A FEEDWATER FLOW SIGNAL CORRESPONDING TO THE MEASURED RATE OF FEEDWATER FLOW, MEASURING THE WATER SEPARATED IN AND FLOWING FROM THE SEPARATOR AND PRODUCING A BLOWDOWN SIGNAL CORRESPONDING TO THE RATE OF FLOW OF WATER FROM THE SEPARATOR, COMPARING THE TWO SIGNALS AND PRODUCING A FIRST CONTROL SIGNAL CORRESPONDING TO THE DIFFERENCE BETWEEN THE AMOUNT OF FEEDWATER FED INTO THE TUBE SYSTEM AND THE AMOUNT OF WATER FLOWING FROM THE SEPARATOR, SMOOTHING SAID FIRST CONTROL SIGNAL, MEASURING THE STEAM TEMPERATURE AT THE OUTLET OF THE CONTROL TUBE LINE AND PRODUCING A SECOND CONTROL SIGNAL CORRESPONDING TO SAID TEMPERATURE, COMBINING THE FIRST CONTROL SIGNAL AND THE SECOND CONTROL SIGNAL AND PRODUCING A MAIN CONTROL SIGNAL, AND CONTROLLING THE AMOUNT OF FEEDWATER FED INTO THE TUBE SYSTEM ACCORDING TO SAID MAIN CONTROL SIGNAL WHEREBY THE AMOUNT OF FEEDWATER IS INCREASED UPON A DECREASE OF THE AMOUNT OF WATER FLOWING FROM THE SEPARATOR RELATIVE TO THE AMOUNT OF FEEDWATER FED INTO THE TUBE SYSTEM AND UPON AN INCREASE OF THE TEMPERATURE OF THE STEAM LEAVING THE CONTROL TUBE LINE, AND VICE VERSA.