Production of phosphoric acid

Claim 1

THE METHOD OF PRODUCING PHOSPHORIC ACID OF AT LEAST 75% STRENGTH FROM ELEMENTAL PHOSPHOROUS, WHICH CONSISTS ESSENTIALLY OF BURNING PHOSPHROUS IN A THIN-WALLED UNLINED, STAINLESS STEEL TOWER TO PRODUCE PHOSPHORUS PENTOXIDE IN VAPOR PHASE INSIDE SAID TOWER, INTRODUCING AN AQUEOUS PHOSPHORIC ACID SOLUTION OF APPROXIMATELY 75% STRENGTH INTO SAID TOWER AND FLOWING SAID ACID IN A THIN FILM ALONG THE INNER WALLS OF SAID TOWER COVERING THE WALLS OF SAID TOWER FROM THE TOP TO THE BOTTOM THEREOF, INTRODUCING WATER INTO SAID TOWER, VAPORIZING WATER IN SAID TOWER FROM THE WATER INTRODUCED INTO SAID TOWER AND FROM THE FILM OF PHOSPHOSIC ACID ALONG THE WALLS OF SAID TOWER, AND HYDRATING AND ABSORBING SAID PHOSPHORIC PENTOXIDE VAPORS INTO THE FLOWING PHOSPHORIC ACID FILM ON THE WALLS OF SAID TOWER WHILE FLOWING WATER ALONG THE OUTSIDE OF SAID TOWER TO PROVIDE ADDITIONAL HEAT TRANSFER FROM THE ACID FLOWING ALONG THE INSIDE WALLS OF SAID TOWER AND MAINTAIN THE WALLS OF SAID TOWER AT A TEMPERATURE OF ABOUT 70 TO 80* C. AND BELOW THE TEMPERATURE AT WHICH PHOSPHORIC ACID OF 75% STRENGTH CORRODES STAINLESS STEEL, REMOVING THE UNCONDENSED GASES FROM THE TOWER AT APPROXIMATELY 75* C. REMOVING ACID FROM THE TOWER AT APPROXIMATELY 70* C., AND RECIRCULATING THE ACID ALONG THE INNER WALLS OF SAID TOWER.

Claim 2

THE METHOD OF PRODUCING PHOSPHORIC ACID OF AT LEAST 75% STRENGTH FROM ELEMENTAL PHOSPHOROUS, WHICH CONSISTS ESSENTIALLY OF BURNING PHOSPHROUS IN A THIN-WALLED UNLINED, STAINLESS STEEL TOWER TO PRODUCE PHOSPHORUS PENTOXIDE IN VAPOR PHASE INSIDE SAID TOWER, INTRODUCING AN AQUEOUS PHOSPHORIC ACID SOLUTION OF APPROXIMATELY 75% STRENGTH INTO SAID TOWER AND FLOWING SAID ACID IN A THIN FILM ALONG THE INNER WALLS OF SAID TOWER COVERING THE WALLS OF SAID TOWER FROM THE TOP TO THE BOTTOM THEREOF, INTRODUCING WATER INTO SAID TOWER, VAPORIZING WATER IN SAID TOWER FROM THE WATER INTRODUCED INTO SAID TOWER AND FROM THE FILM OF PHOSPHOSIC ACID ALONG THE WALLS OF SAID TOWER, AND HYDRATING AND ABSORBING SAID PHOSPHORIC PENTOXIDE VAPORS INTO THE FLOWING PHOSPHORIC ACID FILM ON THE WALLS OF SAID TOWER WHILE FLOWING WATER ALONG THE OUTSIDE OF SAID TOWER TO PROVIDE ADDITIONAL HEAT TRANSFER FROM THE ACID FLOWING ALONG THE INSIDE WALLS OF SAID TOWER AND MAINTAIN THE WALLS OF SAID TOWER AT A TEMPERATURE OF ABOUT 70 TO 80* C. AND BELOW THE TEMPERATURE AT WHICH PHOSPHORIC ACID OF 75% STRENGTH CORRODES STAINLESS STEEL, REMOVING THE UNCONDENSED GASES FROM THE TOWER AT APPROXIMATELY 75* C. REMOVING ACID FROM THE TOWER AT APPROXIMATELY 70* C., AND RECIRCULATING THE ACID ALONG THE INNER WALLS OF SAID TOWER.