Treatment of heat exchanger surfaces

Claim 1

IN AN APPARATUS FOR TREATING AND CLEANING HEAT EXCHANGER SURFACES OF DIRECT-FIRED POWER BOILERS TO INHIBIT CORROSIVE ATTACK AND THE FORMATION OF DENSE ADHERENT STAG DEPOSITS THEREON, THE COMBINATION COMPRISING A PLURALITY OF SOOT BLOWERS POSITIONED ON THE EXTERIOR OF THE BOILER AT SPACED INTERVALS, EACH OF SAID SOOT BLOWERS COMPRISING A FRAME, A LANCE TUBE INCLUDING DISCHARGE NOZZLES AT THE FORWARD END THEREOF FOR DISCHARGING A BLOWING MEDIUM AGAINST THE HEAT EXCHANGER SURFACES, SAID LANCE TUBE ROTATABLY AND LOGITUDINALLY MOVABLE ON SAID FRAME TO AND FROM A RETRACTED POSITION OUT OF THE PATH OF THE HOT COMBUSTION GASES AND A PROJECTED POSITION DISPOSED IN THE INTERIOR OF THE BOILER, AND POWER MEANS FOR ROTATING AND FOR MOVING SAID LANCE TUBE TO AND FROM SAID POSITIONS, FIRST CONDUIT MEANS CONNECTED TO SAID LANCE TUBE OF EACH OF SAID SOOT BLOWERS FOR SUPPLYING A PRESSURIZED BLOWING FLUID THERETO, SECOND CONDUIT MEANS CONNECTED TO SAID LANCE TUBE OF EACH OF SAID SOOT BLOWERS FOR SUPPLYING AN AQUEOUS TREATING SLURRY THERETO, SUPPLY MEANS INCLUDING A SUPPLY TANK AND THIRD CONDUIT MEANS CONNECTED TO EACH OF SAID SECOND CONDUIT MEANS, PUMPING MEANS FOR RECIRCULATING SAID TREATING SLURRY THROUGH SAID THIRD CONDUIT MEANS IN AN AMOUNT IN EXCESS OF THAT DISCHARGED THROUGH SAID LANCE TUBES AND RETURNING SAID EXCESS TO SAID SUPPLY TANK, MEANS FOR PURGING SAID SECOND CONDUIT MEANS WITH WATER AT THE COMPLETION OF A SEQUENTIALLY PHASED OPERATING CYCLE OF SAID SOOT BLOWERS, ACTUATING MEANS ON EACH OF SAID SOOT BLOWERS OPERABLE IN RESPONSE TO MOVEMENT OF SAID LANCE TUBE THEREOF FROM SAID RETRACTED POSITION TOWARD SAID PROJECTED POSITION TO INTRODUCE SAID BLOWING FLUID A PREDETERMINED INTERVAL BEFORE SAID TREATING SLURRY IS INTRODUCED AND FOR STOPPING THE FLOW OF SAID BLOWING FLUID A PREDETERMINED INTERVAL AFTER SAID TREATING SLURRY IS STOPPED RESPONSIVE TO MOVEMENT OF SAID LANCE TUBE FROM SAID PROJECTED POSITION TOWARD SAID RETRACTED POSITION, AND CONTROL MEANS FOR AUTOMATICALLY ACTUATING SAID POWER MEANS OF SELECTED ONES OF SAID SOOT BLOWERS IN ACCORDANCE WITH A PRESELECTED SEQUENTIALLY PHASED OPERATING CYCLE.