Dryers

Claim 1

IN A HIGH VELOCITY AIR DRYER FOR REMOVING MOISTURE FROM CONTINOUSLY MOVING WEBS OF MATERIAL: (A) A HOT AIR HEATER COMPRISING AND AIR HEATING CHAMBER AND A TUBE TYPE HEAT EXCHANGER IN SAID CHAMBER; (B) A DUCT FOR CONDUCTING HOT AIR FROM SAID CHAMBER TO THE MATERIAL TO BE DRIED; (C) A HEATING UNIT INCLUDING A TUBE TYPE HEAT EXCHANGER (D) SUPPLY AND RETURN CONDUITS ESTABLISHING FLUID COMMUNICATION BETWEEN SAID HEAT EXCHANGERS AND TOGETHER WITH SAID HEAT EXCHANGERS CONSTITUTING A CIRCULATIN SYSTEM; (E) A LIQUID HAVING A BOILING POINT OF NOT LESS THAN ABOUT 500* F. IN SAID SYSTEM; (F) MEANS FOR EFFECTING CIRCULATION OF SAID LIQUID AT A SUBSTANTIALY CONSTANT RATE THROUGH SAID CIRCULATION SYSTEM; (G) A FIRST BYPASS CONDUIT ESTABLISHING FLUID COMMUNICATION BETWEEN SAID SUPPLY AND RETURN CONDUITS AND CONNECTED IN PARALLEL WITH THE HEAT EXCHANGER IN SAID AIR HEATER; (H) MEANS RESPONSIVE TO THE TEMPERATURE OF THE AIR IN SAID HOT AIR DUCT FOR PORPORTIONING THE FLOW OF SAID LIQUID BETWEEN SAID FIRST BYPASS CONDUIT AND THE AIR HEATER HEAT EXCHANGER TO MAINTAIN THE AIR FLOWING THROUGH DUCT AT A SUBSTANTIALY UNIFORM TEMPERATURE; (I) A SECOND CIRCULATION MAINTAINING BYPASS CONDUIT ESTABLISHING FLUID COMMUNICATION BETWEEN SAID SUPPLY AND RETURN CONDUITS AND CONNECTED TO SAID SUPPLY AND RETURN CONDUITS CLOSELY ADJACENT THE INLET OF THE HEATING UNIT HEAT EXCHANGER AND THE INTAKE OF THE LIQUID CIRCULATING MEANS, RESPECTIVELY; AND (J) MEANS RESPONSIVE TO THE PRESSURE DIFFERENTIAL BETWEEN THE INLET AND OUTLET SIDES OF SAID LIQUID CIRCULATING MEANS FOR DIVERTING FLOW THROUGH SAID SECOND CIRCULATING MAINTAINING BYPASS TO THE HEAT EXCHANGER IN THE HEATING UNIT IN PORPORTION TO DECREASE IN FLOW THROUGH THE CIRCULATIN SYSTEM TO MAINTAIN A SUBSTANTIALLY CONSTANT FLOW OF LIQUID THROUGH SAID HEAT EXCHANGER AND THEREBY PREVENT OVERHEATING OF THE CIRCULATING FLUID.