Once-through vapor generator variable pressure start-up system

Claim 1

A ONCE-THROUGH VAPOR GENERATOR COMPRISING A MAIN FLOW PATH INCLUDING A PLURALITY OF HEATING SURFACES AND A CONDENSATE SYSTEM IN SERIES; A START-UP SYSTEM INCLUDING FIRST AND SECOND BY-PASS LOOPS LEADING FROM A FIRST POINT INTERMEDIATE SAID HEATING SURFACES TO THE CONDENSATE SYSTEM; THE FIRST BY-PASS LOOP INCLUDING SEPARATING MEANS FOR SEPARATING A MIXED PHASE FLOW INTO A VAPOR STREAM AND A LIQUID STREAM, A VAPOR LINE TO RETURN THE VAPOR STREAM TO A SECOND POINT INTERMEDIATE THE HEATING SURFACES BUT DOWNSTREAM OF THE FIRST POINT; A SHUT-OFF VALVE IN THE MAIN FLOW PATH INTERMEDIATE THE FIRST AND SECOND POINTS; THE SECOND BY-PASS LOOP INCLUDING A CONDUIT, A PRESSURE REDUCING VALVE IN THE CONDUIT ADAPTED TO MAINTAIN PRESSURE IN THE HEATING SURFACES AND TO DIVERT A VARIABLE FLOW TO SAID CONDENSATE SYSTEM.