Thermal water purification system and method for operating said system

Patent metadata

Field	Value
Publication number	US-10702830-B2
Application number	US-201716083731-A
Country	US
Kind code	B2
Filing date	Mar 15, 2017
Priority date	Mar 16, 2016
Publication date	Jul 7, 2020
Grant date	Jul 7, 2020

Abstract

A thermal water purification system and a related method including distilling units consecutively flowed through by raw feed liquid, each having a boiling liquid section and a vapor section, and including a heat exchanger cavity adapted to transfer thermal energy to the raw feed liquid before entering the boiling liquid section of a first distilling unit. Heat exchanger tubes in fluidic communication with the heat exchanger cavity extend through the boiling liquid section of the first distilling unit to transfer thermal energy from a medium in the tubes to cause the raw feed liquid to boil. Preheating tubes extend through the vapor section of each distilling unit to heat the raw feed liquid before entering the boiling sections using thermal energy from vapor condensing against external surfaces of the preheating tubes, which produces the distillate liquid that flows through a discharge port and a conduit supplying a storage tank.

First claim

The invention claimed is:

1. A thermal water purification system for producing a distillate liquid from a raw feed liquid, comprising:
a plurality of distilling units which are consecutively flowed through by the raw feed liquid, wherein the plurality of distilling units includes a first distilling unit and a plurality of consecutive distilling units;
wherein each distilling unit comprises a boiling liquid section and a vapor section adjacent thereto;
wherein the boiling liquid section of each distilling unit comprises a plurality of inlet ports and outlet ports, through which respectively enters and exits the raw feed liquid; and
wherein any two consecutive distilling units, respectively an upstream distilling unit and a downstream distilling unit, are implemented such that the boiling liquid section of the downstream distilling unit is separated from the vapor section of the upstream distilling unit by a liquid-tight and vapor-tight separation plate, and separated from the vapor section of the downstream distilling unit by a liquid-tight and vapor-permeable membrane;

a heat exchanger cavity adapted to transfer thermal energy to the raw feed liquid before the raw feed liquid enters into the boiling liquid section of the first distilling unit;
a plurality of heat exchanger tubes in fluidic communication with the heat exchanger cavity and extending through the boiling liquid section of said first distilling unit, said heat exchanger tubes being configured to transfer thermal energy from a hot medium contained thereinside to the raw feed liquid flowing thereoutside, thus leading the raw feed liquid to boil inside the boiling liquid section of the first distilling unit;
a plurality of preheating tubes extending through the vapor section of each distilling unit, said preheating tubes being consecutively flowed through by the raw feed liquid before said raw feed liquid flows inside the boiling liquid sections of the distilling units and being configured to heat the raw feed liquid contained thereinside by using thermal energy transferred by vapor contained inside the vapor sections of the distilling units when said vapor condenses against external surfaces of the preheating tubes, thus producing a distillate liquid that flows outside of the vapor section of each distilling unit, each distilling unit having a distillate discharge port through which the distillate liquid flows; and
a distillate conduit in fluidic communication with each distillate discharge port, said distillate conduit supplying a storage tank with the distillate liquid.

2. The thermal water purification system according to claim 1 , wherein said first distilling unit is positioned upstream from the plurality of consecutive distilling units of the thermal water purification system, thus leading to a decrease of the temperature of the raw feed liquid when it flows from said first distilling unit to said plurality of consecutive distilling units.

3. The thermal water purification system according to claim 1 , wherein a plurality of heat exchanger tubes further extends through each boiling section of i further consecutive distilling units amongst the plurality of consecutive distilling units, i being an integer greater than 0.

4. The thermal water purification system according to claim 1 , wherein any two consecutive distilling units, respectively an upstream distilling unit and a downstream distilling unit, are implemented such that the inlet ports of the boiling liquid section of the downstream distilling unit are in fluidic communication with the outlet ports of the boiling liquid section of the upstream distilling unit.

5. The thermal water purification system according to claim 1 , wherein any two consecutive distilling units, respectively an upstream distilling unit and a downstream distilling unit, are implemented such that the outlet ports of the boiling liquid section of the upstream distilling unit are in fluidic communication with at least one internal boiling tube extending through the vapor section of said upstream distilling unit and such that the inlet ports of the boiling liquid section of the downstream distilling unit are in fluidic communication with said at least one internal boiling tube.

6. The thermal water purification system according to claim 1 , wherein the separation plate separating the vapor section of an upstream distilling unit from the boiling liquid section of a downstream distilling unit is configured to heat the raw feed liquid contained inside said boiling liquid section by using thermal energy transferred by the vapor contained inside said vapor section when said vapor condenses against a condensation surface of said separation plate, thus leading the raw feed liquid to boil inside said boiling liquid section.

7. The thermal water purification system according to claim 1 , wherein the preheating tubes are provided with projecting fins and ribs arranged along their periphery, said fins and ribs enhancing the heat transfer between the outside of each preheating tube and the inside thereof.

8. The thermal water purification system according to claim 3 , wherein i+1 represents less than 40% of the total number of the distilling units of the thermal water purification system.

9. The thermal water purification system according to claim 4 , wherein the inlet ports of the boiling liquid section of the downstream distilling unit are in fluidic communication with the outlet ports of the boiling liquid section of the upstream distilling unit via a throttle or flash valve.

10. The thermal water purification system according to claim 5 , wherein the inlet ports of the boiling liquid section of the downstream distilling unit are in fluidic communication with said at least one internal boiling tube via a throttle or flash valve.

11. A method for operating the thermal water purification system according to claim 1 , comprising the steps of:
a) channeling the raw feed liquid having initially a first temperature towards the boiling liquid section of the first distilling unit through the plurality of preheating tubes so as to increase the temperature of the raw feed liquid from said first temperature to a second temperature;
b) channeling the raw feed liquid having initially said second temperature towards the boiling liquid section of said first distilling unit through the heat exchanger cavity so as to increase the temperature of the raw feed liquid from said second temperature to a third temperature using the thermal energy transferred from the hot medium;
c) channeling the raw feed liquid having initially said third temperature, or a temperature slightly lower than said third temperature, into the boiling liquid section of said first distilling unit and, thereafter, into the boiling liquid sections of the plurality of consecutive distilling units;
d) heating said raw feed liquid with the plurality of heat exchanger tubes extending through the boiling liquid section of said first distilling unit, so as to boil the raw feed liquid flowing inside the boiling liquid section of the first distilling unit, with a decrease in the temperature of the raw feed liquid due to the drop of pressure inside the boiling liquid section of the first distilling unit from the inlet ports thereof to the outlet ports thereof;
e) passing the vapor produced by the raw feed liquid boiling in the boiling liquid section of each distilling unit through the liquid-tight and vapor-permeable membrane into the vapor section adjacent thereto;
f) condensing said vapor into said vapor section to produce the distillate liquid; and
g) channeling said distillate liquid into the storage tank.

12. The method according to claim 11 , furt

Assignees

• Ecole Polytechnique Fed Lausanne Epfl

Inventors

• Ong Chin Lee
• Thome John R

Classifications

• B01D61/364 Primary

  Membrane distillation · CPC title

• Y02A20/124

  Water desalination · CPC title

• B01D61/366

  Apparatus therefor · CPC title

• C02F2301/08

  Multistage treatments, e.g. repetition of the same process step under different conditions · CPC title

• C02F2103/08

  Seawater, e.g. for desalination · CPC title