Method and apparatus for the multistage flash distillation of a liquid

Claim 1

IN THE METHOD OF EVAPORATING LIQUIDS IN AND OPERATING A MULTIPLE-STAGE EVAPORATOR INCLUDING A PLURALITY OF STAGES IN SERIES IN WHICH EACH STAGE INCLUDES A FLASH ZONE AND A CONDENSING ZONE ASSOCIATED WITH THE FLASH ZONE FOR CONDENSING THE VAPORS FLASHED IN THE FLASH ZONE, MAINTAINING THE FLASH ZONES AT PROGRESSIVELY HIGHER PRESSURES AND TEMPERATURES IN ONE DIRECTION THROUGH THE SERIES OF STAGES, THE STAGES BEING SO INTERRELATED THAT FEED LIQUID AT SATURATION TEMPERATURE CORRESPONDING TO THE PRESSURE IN THE FLASH ZONE OF ONE STAGE FLOWS TO THE FLASH ZONE OF THE NEXT STAGE AT A LOWER PRESSURE AND ARRIVES IN SAID NEXT STAGE AT A TEMPERATURE HIGHER THAN THE SATURATION TEMPERATURE CORRESPONDING TO SAID LOWER PRESSURE SO THAT A PORTION OF THE FEED LIQUID FLASHES INTO VAPOR WHICH IS LED OFF TO THE CONDENSING ZONE FOR SAID STAGE, CONDUCTING INTAKE FEED LIQUID TO BE EVAPORATED THROUGH THE CONDENSING ZONES OF THE SERIES OF STAGES IN HEAT EXCHANGE WITH BUT OUT OF CONTACT WITH THE VAPORS THEREIN IN A DIRECTION TO HEAT THE INTAKE FEED LIQUID TO PREGRESSIVELY HIGHER TEMPERATURES, CONDUCTING THE HEATED FEED LIQUID FROM THE CONDENSING ZONE OF HIGHEST TEMPERATURE INTO THE FLASH ZONE ASSOCIATED THEREWITH AND CONDUCTING FEED LIQUID THEREFROM IN SUCCESSION THROUGH THE REMAINING FLASH ZONES OF THE SERIES OF STAGES IN A DIRECTION OPPOSITE TO THE DIRECTION OF FLOW OF THE INTAKE FEED LIQUID THROUGH THE CONDENSING ZONES OF THE SERIES OF STAGES, SAID FEED LIQUID BEING CONDUCTED AT A POINT IN ITS FLOW THROUGH THE PLURALITY OF STAGES FROM ONE CONDENSING ZONE TO THE NEXT CONDENSING ZONE AT A TEMPERATURE ABOUT EQUAL TO THE TEMPERATURE OF THE UNVAPORIZED FEED LIQUID AT THE FLASH ZONE OF LOWEST TEMPERATURE IN THE SERIES OF STAGES, WITHDRAWING FEED LIQUID FROM THE FLASH ZONE OF LOWEST TEMPERATURE IN THE SERIES OF STAGES AND MIXING FEED LIQUID WITHDRAWING FROM SAID FLASH ZONE WITH THE INTAKE FEED LIQUID PASSING THROUGH THE CONDENSING ZONES OF THE SERIES OF STAGES AT SAID POINT WHERE THE TEMPERATURE OF THE INTAKE FEED LIQUID IS ABOUT EQUAL TO THE TEMPERATURE OF THE LIQUID WITHDRAWN FROM SAID FLASH ZONE OF LOWEST TEMPERATURE, THE WITHDRAWN FEED LIQUID BEING RECIRCULATED THROUGH A PLURALITY OF THE CONDENSING ZONES AND THEN THROUGH THE FLASH ZONES OF THE STAGES AFTER BEING MIXED WITH THE INTAKE FEED LIQUID, AND THE INTAKE FEED LIQUID BEING CONDUCTED THROUGH SEVERAL OF THE CONDENSING ZONES OF THE SERIES OF STAGES WITHOUT RECIRCULATED LIQUID UNTIL IT IS HEATED TO A TEMPERATURE ABOUT EQUAL TO THE TEMPERATURE OF THE LIQUID WITHDRAWN FROM SAID FLASH ZONE OF LOWEST TEMPERATURE.