Distillation method and apparatus

Claim 1

IN A MULTI-EFFECT FLIM EVAPORATOR HAVING A PLURALITY OF EFFECTS OPERABLE AT SUCCESSIVE LOWER TEMPERATUR S AND PRESSURES WITH EACH EFFECT INCLUDING HEAR EXCHANGE TUBE MEANS FOR PASSING A VAPOR AND A FEED LIQUID IN HEAT EXCHANGE RELATION TO VAPORIZE AT LEAST A PORTION OF THE FEED LIQUID AND TO CONDENSE 000AT LEAST A PORTION OF THE VAPOR, MEANS FOR DELIVERING THE UNEVAPORATED LIQUID IN EACH EFFECT EXCEPT THE LAST TO THE HEAT EXCHANGE TUBE MEANS OF SUCCEEDING EFFECTS TO COMPRISE AT LEAST THE PORTION OF THE FEED LIQUID THEREOF AND MEANS FOR DELIVERING THE EVAPORATED LIQUID IN EACH EFFECT EXCEPT THE LAST AS THE VAPOR TO BE CONDENSED IN THE NEXT SUCCEEDING LOWER TEMPERATURE EFFECT, MEANS FOR OPERATING A FIRST FROUP OF SAID EFFECTS AT SEQUENTIALLY LOWER TEMPERATURE ABOVE A PREDETERMINED TEMPERATURE AD A SECOND GROUP OF SAID EFFECTS AT SEQUENTIALLY LOWER TEMPERATURES BELOW SAID PREDETERMINED TEMPERATURE, THE IMPROVEMENT COMPRISING: FORST FREED LIQUID DELIVERY MEANS COUPLED TO THE EFFECTS OF SAID FIRST GROUP FOR DELIVERY MEANS FOR DELIVERING FREED A SECOND FEED LIQUID DELIVERY MEANS FOR DELIVERING FEED LIQUID TO EFFECR OF SAID SECOND GROUP OF EFFECTS, FIRST CHEMICAL TREATING MEANS INCLUDING A SORCE OF A FIRST MATERIAL TAKEN FROM THE GROUP CONSISTING OF ACID AND AN ACID SALT, COUPLED TO THE FRIST FREED LIQUID DELIVERY MEANS FOR TREATING THE FREED LIQUID THEREIN WITH SAID FIRST MATERIAL WHICH IS OPERABLE TO PREVENT SCALE FORMATION AT TEMPERATURES ABOVE SAID PREDETERMINED TEMPERATURE, SECOND CHEMICAL TREATIN MEANS INCLUDING A SOURCE OF POLYPHOSPHATE COUPLED TO THE SECOND FREED LIQUID DELIVERY MEANS FOR TREATING THE FEED LIQUID THEREIN WITH SAID POLYPHOSPHATE WHICH IS OPERABLE TO PREVENT SCALE FORMATION BELOW SAID PREDETERMINED TEMPERATURE, SAID POLYPHOSPHATE BEING INOPERATIVE TO PREVENT SCALESCALE FORMATION ABOVE SAID PREDETERMINED TEMPERTURE, THE FLOW PATHS OF SAID FEED LIQUID IN SAID FIRST AND SECOND FEED LIQUID DELIVERY MEANS BEING ISOLATED FROM EACH OTHER BETWEEN SAID FIRST AND SECOND CHEMICAL TREATING MEANS AND SAID GROUPS OF CORRESPONDING EFFECTS.

Claim 13

A method of distilling liquid which includes the steps of placing feed liquid and vapor in a heat exchange relation in each effect of a multi-effect evaporator so that a portion of the feed liquid is evaporated and the vapor is condensed as the product distillate of the system, providing an initial quantity of feed liquid to the initial one of the effects and separate quantities of feed liquid to each of the other effects, providing the vaporized portion of the liquid in each effect except the last to a succeeding effect as the heating vapor thereof and passing the unevaporated liquid in each effect except the last to a succeeding lower temperature effect, the improvement comprising; operating a first group of said effects at sequentially lower temperatures above a predetermined temperature and a second group of effects at sequentially lower temperatures below said predetermined temperature, preheating the feed liquid provided to the first group of effects to temperatures in excess of said predetermined temperature and feeding the thus preheated feed to said first group of effects, preheating the remaining feed liquid to temperatures below said predetermined temperature and feeding the thus preheated feed to said group of effects, adding to the feed liquid provided to the first group of effects an acid which is operable to suppress the formation of alkaline scales at temperatures above said predetermined temperature, and adding to the remaining feed liquid polyphosphate operable to suppress alkaline scale formation below said predetermined temperature but ineffective to prevent such formation above said temperature.

Claim 14

A method of distilling liquid which includes the steps of placing feed liquid and vapor in a heat exchange relation in each effect of a multi-effect evaporator so that a portion of the feed liquid is evaporated and the vapor is condensed as the product distillate of the system, providing an initial quantity of feed liquid to the initial one of the effects and separate quantities of feed liquid to each of the other effects, providing the vaporized portion of the liquid in each effect except the last to a succeeding effect as the heating vapor thereof and passing the unevaporated liquid in each effect except the last to a succeeding lower temperature effect, the improvement comprising; operating a first group of said effects at sequentially lower temperatures above a predetermined temperature and a second group of effects at sequentially lower temperatures below said predetermined temperature, preheating the feed liquid provided to the first group of effects to temperatures in excess of said predetermined temperature and feeding the thus preheated feed to said first group of effects, preheating the remaining feed liquid to temperatures below said predetermined temperature and feeding the thus preheated feed to said group of effects, adding to the feed liquid provided to the first group of effects an acid which is operable to suppress the formation of alkaline scales at temperatures above said predetermined temperature, and adding to the remaining feed liquid polyphosphate operable to suppress alkaline scale formation below said predetermined temperature but ineffective to prevent such formation above said temperature.

Claim 16

A method of distilling liquid in a multi-effect evaporator having a plurality of effects wherein feed liquid and vapor are placed in a heat exchange relation in each effect so that a portion of the feed liquid is evaporated and the vapor is condenseD, and wherein the unevaporated feed liquid in each effect is conducted to the next succeeding lower temperature effect and the evaporated feed liquid in each effect is conducted to the next succeeding lower temperature effect as the vapor therein, the improvement comprising: operating a first plurality of said effects at sequentially lower temperatures above about 195*F and operating a second plurality of said effects at sequentially lower temperatures below said temperature, heating a first quantity of feed liquid above said temperature, providing said first quantity of feed liquid to at least one of the first plurality of effects, heating a second quantity of feed liquid to a temperature below said temperature, providing said second quantity of feed liquid to at least one of the second plurality of effects, treating said first quantity of feed liquid with an acid operable to prevent the formation of alkaline scale at temperatures above said temperature, and treating said second quantity of feed liquid with polyphosphate operable to prevent the formation of alkaline scale at temperatures below said temperature, said polyphosphate being ineffective to prevent scale formation above said temperature.

Claim 17

A method of distilling liquid in a multi-effect evaporator having a plurality of effects wherein feed liquid and vapor are placed in a heat exchange relation in each effect so that a portion of the feed liquid is evaporated and the vapor is condenseD, and wherein the unevaporated feed liquid in each effect is conducted to the next succeeding lower temperature effect and the evaporated feed liquid in each effect is conducted to the next succeeding lower temperature effect as the vapor therein, the improvement comprising: operating a first plurality of said effects at sequentially lower temperatures above about 195*F and operating a second plurality of said effects at sequentially lower temperatures below said temperature, heating a first quantity of feed liquid above said temperature, providing said first quantity of feed liquid to at least one of the first plurality of effects, heating a second quantity of feed liquid to a temperature below said temperature, providing said second quantity of feed liquid to at least one of the second plurality of effects, treating said first quantity of feed liquid with an acid operable to prevent the formation of alkaline scale at temperatures above said temperature, and treating said second quantity of feed liquid with polyphosphate operable to prevent the formation of alkaline scale at temperatures below said temperature, said polyphosphate being ineffective to prevent scale formation above said temperature.

Claim 18

A method of distilling liquid including the steps of placing liquid and vapor in a heat exchange relation in each effect of a multi-effect evaporator so that a portion of the liquid is evaporated and the vapor is condensed as the product distillate of the system, maintaining said effects at successively lower temperatures for sequential flow of liquid therethru heating a first quantity of feed liquid above a temperature of about 195*F, providing said first quantity of feed liquid to each of said effects whose temperature is above said temperature, heating a second quantity of feed liquid below said temperature, providing said second quantity of feed liquid to each of said effects operating below said temperature, treating said first quantity of feed liquid with a first chemical agent taken from a group consisting of acid and an acid salt to prevent the formation of alkaline scale at temperatures above said temperature and treating said second quantity of feed liquid with a polyphosphate to prevent the formation of alkaline scale at temperatures below said temperature.

Claim 19

A method of distilling liquid including the steps of placing liquid and vapor in a heat exchange relation in each effect of a multi-effect evaporator so that a portion of the liquid is evaporated and the vapor is condensed as the product distillate of the system, maintaining said effects at successively lower temperatures for sequential flow of liquid therethru heating a first quantity of feed liquid above a temperature of about 195*F, providing said first quantity of feed liquid to each of said effects whose temperature is above said temperature, heating a second quantity of feed liquid below said temperature, providing said second quantity of feed liquid to each of said effects operating below said temperature, treating said first quantity of feed liquid with a first chemical agent taken from a group consisting of acid and an acid salt to prevent the formation of alkaline scale at temperatures above said temperature and treating said second quantity of feed liquid with a polyphosphate to prevent the formation of alkaline scale at temperatures below said temperature.