Multiple-effect multi-stage flash evaporation process and apparatus for demineralizing water

Claim 2

A DESALTING PROCESS FEED SALINE WATER CONTAINING-SCALE FORMING MATERIALS INCLUDING CALCIUM SULFATE, WHEREIN SALINE WATER FED TO A MULTIPLE EVAPORATOR EFFECTS IS PREHEATED IN MULTISTAGE FLASH EVAPORATORS HAVING FLASH CHAMBERS, AND IS EVAPORATED AND CONCENTRATED IN THE MULTIPLE EVAPORATOR EFFECTS TO PRODUCE DESALTED WATER, WHICH PROCESS COMPRISES: FLASHING FEED SALT WATER IN A FIRST FLASH EVAPORATOR UNDER A REDUCED PRESSURE TO PRODUCE VAPOR AND BRINE, WHILE TRANSFERRING THE LATENT HEAT OF THE VAPOR TO THE FEED SALINE WATER BY INDIRECT HEAT EXCAHNGE THEREWITH AND SIMULTANEOUSLY CONDENSING THE VAPOR TO PRODUCE PRODUCT DESALTED CONDENSATE, ALL AT A TEMPERATURE ABOVE WHICH ANHYDRITE CALCIUM SULFATE PRECIPITATES; EVAPORATING A PORTION OF THE BRINE FROM THE FIRST FLASHING STEP IN A FIRST EVAPORATOR EFFECT BY THE LATENT HEAT OF CONDENSATION OF OTHER VAPOR TO PRODUCE FURTHER VAPOR FROM SAID PORTION OF THE FIRST BRINE TO PRODUCE ENRICHED BRINE, WHILE CONDENSING THE OTHER VAPOR TO PRODUCE OTHER CONDENSATE, ALL AT A TEMPERATURE ABOVE WHICH ANHYDRITE CALCIUM SULFATE PRECIPITATES; INTRODUCING THE ENRICHED BRINE PRODUCED IN SAID EVAPORATING STEP DIRECTLY INTO THE FLASHING CHAMBER OF A SECOND FLASH EVAPORATOR

Claim 3

The desalting process in accordance with claim 1, wherein the temperature of the feed salt water introduced into the first flashing step is kept below that at which hemihydrite calcium sulfate within the feed salt water precipitates.

Claim 4

The desalting process in accordance with claim 1, further including the step of introducing a portion of the brine from the first flash evaporator of said first flashing step directly into a subsequent flashing step at a lower pressure.

Claim 5

The desalting process in accordance with claim 1, further comprising the step of introducing a portion of the brine froM the first flash evaporator of said first flashing step directly into the flashing chamber of the second flash evaporator of said additional flashing step.

Claim 6

The desalting process in accordance with claim 1, further comprising the step of returning the brine enriched in the subsequent evaporator effect to the same flash evaporator from which it was withdrawn, while maintaining the temperature of the said subsequent evaporator effect and the flash evaporator from which the brine was withdrawn for evaporating in the subsequent evaporator effect and into which the thus enriched brine was returned, both at a temperature lower than the temperature at which anhydrite calcium sulfate precipitates.

Claim 7

Desalting apparatus for saline water containing scale forming materials including calcium sulfate, comprising: a plurality of evaporator effects, each having a vapor condensing chamber having therein heat exchange means for conducting brine to be at least partially evaporated by the latent heat of condensation of vapor condensing on the exterior of the heat exchange means within the vapor chamber to transfer the latent heat of condensation to the brine to produce vapor from the brine within the heat exchange means through indirect heat exchange, and further including means for separating the thus formed vapor and enriched brine obtained within the heat exchange means; pipe means between said evaporator effects for directly transferring the separated vapor from one evaporator effect to the vapor chamber of a subsequent evaporator effect to be condensed in the subsequent evaporator effect; a plurality of flash evaporators, each being provided with a flashing chamber wherein salt water is flash evaporated at reduced pressure to produce vapor and brine, each of said flash evaporators further having preheater heat exchange means having its exterior in contact with the vapor within the flashing chamber to produce desalted condensate water on its exterior while preheating saline feed water passing through its interior with the vapor latent heat of condensation; first means for conducting only a portion of the brine from within the flashing chamber of one of said flash evaporators into the heat exchange means of the highest temperature one of said evaporator effects; second means for conducting the brine separated within said highest temperature evaporator effect directly into the flashing chamber of a second lower temperature one of said flash evaporators; means for maintaining said second flash evaporator at a lower pressure than the pressure within said one flash evaporator; and means for introducing a portion of the brine from the flashing chamber of said one flash evaporator directly into the flashing chamber of another flash evaporator; and means for maintaining said another flash evaporator at a lower pressure and temperature than said one flash evaporator.

Claim 8

Desalting apparatus for saline water containing scale forming materials including calcium sulfate, comprising: a plurality of evaporator effects, each having a vapor condensing chamber having therein heat exchange means for conducting brine to be at least partially evaporated by the latent heat of condensation of vapor condensing on the exterior of the heat exchange means within the vapor chamber to transfer the latent heat of condensation to the brine to produce vapor from the brine within the heat exchange means through indirect heat exchange, and further including means for separating the thus formed vapor and enriched brine obtained within the heat exchange means; pipe means between said evaporator effects for directly transferring the separated vapor from one evaporator effect to the vapor chamber of a subsequent evaporator effect to be condensed in the subsequent evaporator effect; a plurality of flash evaporators, each being provided with a flashing chamber wherein salt water is flash evaporated at reduced pressure to produce vapor and brine, each of said flash evaporators further having preheater heat exchange means having its exterior in contact with the vapor within the flashing chamber to produce desalted condensate water on its exterior while preheating saline feed water passing through its interior with the vapor latent heat of condensation; first means for conducting only a portion of the brine from within the flashing chamber of one of said flash evaporators into the heat exchange means of the highest temperature one of said evaporator effects; second means for conducting the brine separated within said highest temperature evaporator effect directly into the flashing chamber of a second lower temperature one of said flash evaporators; means for maintaining said second flash evaporator at a lower pressure than the pressure within said one flash evaporator; and means for introducing a portion of the brine from the flashing chamber of said one flash evaporator directly into the flashing chamber of another flash evaporator; and means for maintaining said another flash evaporator at a lower pressure and temperature than said one flash evaporator.

Claim 9

The desalting apparatus of claim 6, further comprising means, which includes said first mentioned heat exchange means, for liquid serially connecting, in order of descending pressure and temperature, the flashing chambers of said flash evaporators for directly transferring the brine within a flashing chamber at one pressure into the flashing chamber of the next subsequent flash evaporator maintained at a lower pressure.

Claim 10

The desalting apparatus of claim 7, further comprising brine conduit means for all of the evaporator effects operating at temperatures above the temperature at which anhydrite calcium sulfate will precipitate from their brine, for transferring brine from the flashing chamber of a flash evaporator through a corresponding evaporator effect and returning the thus enriched brine to the next subsequent flash evaporator maintained at a lower pressure.

Claim 11

The desalting apparatus of claim 8, further comprising conduit means for the evaporator effects that will operate at temperatures below the temperature at which anhydrite calcium sulfate precipitates from their brine, for conducting brinE from a flashing chamber to a corresponding evaporator effect and returning the thus enriched brine to the same flash evaporator from which it was withdrawn at substantially the same temperature.

Claim 12

Desalting apparatus for saline water containing scale forming materials including calcium sulfate, comprising: a plurality of evaporator effects, each having a vapor condensing chamber having therein heat exchange means for conducting brine to be at least partially evaporated by the latent heat of condensation of vapor condensing on the exterior of the heat exchange means within the vapor chamber to transfer the latent heat of condensation to the brine to produce vapor from the brine within the heat exchange means through indirect heat exchange, and further including means for separating the thus formed vapor and enriched brine obtained within the heat exchange means; pipe means between said evaporator effects for directly transferring the separated vapor from one evaporator effect to be condensed in the subsequent evaporator effect; a plurality of flash evaporators, each being provided with a flashing chamber wherein salt water is flash evaporated at reduced pressure to produce vapor and brine, each of said flash evaporators further having preheater heat exchange means having its exterior in contact with the vapor within the flashing chamber to produce desalted condensate water on its exterior while preheating saline feed water passing through its interior with the vapor latent head of condensation; first means for conducting at least a portion of the brine from within the flashing chamber of one of said flash evaporators into the heat exchange means of the highest temperature one of said evaporator effects; second means for conducting the brine separated within said highest temperature evaporator effect directly into the flashing chamber of a second lower temperature one of said flash evaporators; means for maintaining said second flash evaporator at a lower pressure than the pressure within said one flash evaporator; conduit means for the evaporator effects that will operate at temperatures below the temperature at which anhydrite calcium sulfate precipitates from their brine, for conducting brine from a flashing chamber other than said one flash evaporator to a corresponding evaporator effect and returing the thus enriched brine to the same flash evaporator from which it was withdrawn at substantially the same temperature; and means for maintaining each flashing chamber supplying and receiving brine from a single evaporator effect at a lower pressure and temperature than said one flash evaporator.

Claim 13

Desalting apparatus for saline water containing scale forming materials including calcium sulfate, comprising: a plurality of evaporator effects, each having a vapor condensing chamber having therein heat exchange means for conducting brine to be at least partially evaporated by the latent heat of condensation of vapor condensing on the exterior of the heat exchange means within the vapor chamber to transfer the latent heat of condensation to the brine to produce vapor from the brine within the heat exchange means through indirect heat exchange, and further including means for separating the thus formed vapor and enriched brine obtained within the heat exchange means; pipe means between said evaporator effects for directly transferring the separated vapor from one evaporator effect to be condensed in the subsequent evaporator effect; a plurality of flash evaporators, each being provided with a flashing chamber wherein salt water is flash evaporated at reduced pressure to produce vapor and brine, each of said flash evaporators further having preheater heat exchange means having its exterior in contact with the vapor within the flashing chamber to produce desalted condensate water on its exterior while preheating saline feed water passing through its interior with the vapor latent head of condensation; first means for conducting at least a portion of the brine from within the flashing chamber of one of said flash evaporators into the heat exchange means of the highest temperature one of said evaporator effects; second means for conducting the brine separated within said highest temperature evaporator effect directly into the flashing chamber of a second lower temperature one of said flash evaporators; means for maintaining said second flash evaporator at a lower pressure than the pressure within said one flash evaporator; conduit means for the evaporator effects that will operate at temperatures below the temperature at which anhydrite calcium sulfate precipitates from their brine, for conducting brine from a flashing chamber other than said one flash evaporator to a corresponding evaporator effect and returing the thus enriched brine to the same flash evaporator from which it was withdrawn at substantially the same temperature; and means for maintaining each flashing chamber supplying and receiving brine from a single evaporator effect at a lower pressure and temperature than said one flash evaporator.