Thermal energy-driven mechanical compression humidification-dehumidification water purification

Patent metadata

Field	Value
Publication number	US-10472258-B2
Application number	US-201515323376-A
Country	US
Kind code	B2
Filing date	Jun 29, 2015
Priority date	Jun 30, 2014
Publication date	Nov 12, 2019
Grant date	Nov 12, 2019

Abstract

A carrier gas is directed through a humidification chamber in a humidifier, where the carrier gas flow is directly contacted with a feed liquid to humidify the carrier gas with water evaporated from the feed liquid, producing a humidified gas flow. The humidified gas flow is then compressed in a compressor and then directed through a dehumidification chamber in a dehumidifier, where the compressed humidified gas flow is dehumidified to condense water from the compressed humidified gas flow. The dehumidified gas flow is then expanded in an expander, wherein the expansion of the dehumidified gas flow generates motion (e.g., rotation of a shaft), and wherein the motion generated in the expander is transferred to the compressor, where the motion compresses the humidified gas flow. Heat is also removed from the expanded dehumidified gas flow and transferred to compressed dehumidified gas flow upstream from the expander.

First claim

What is claimed is:

1. A method for purifying water via thermal-energy-driven mechanical compression humidification-dehumidification, comprising:
directing a flow of a feed liquid into a feed-liquid input and out of a feed-liquid output for a humidification chamber in at least one humidifier;
directing a flow of a carrier gas into a carrier-gas input and out of a carrier-gas output for the humidification chamber in the at least one humidifier;
directly contacting the carrier gas flow with the feed liquid in the humidification chamber to humidify the carrier gas with water evaporated from the feed liquid, producing a humidified gas flow;
directing the humidified gas flow through a humidified-carrier-gas conduit to a carrier-gas input for a dehumidification chamber in at least one dehumidifier;
compressing the humidified gas flow in a compressor in or coupled with the humidified-carrier-gas conduit;
directing the compressed humidified gas flow into the carrier-gas input and out of a carrier-gas output for the dehumidification chamber in the at least one dehumidifier;
dehumidifying the compressed humidified gas flow in the dehumidification chamber to condense purified water from the compressed humidified gas flow; then
directing the dehumidified compressed gas flow from the carrier-gas output of the dehumidifier through a dehumidified-carrier-gas conduit;
using a heater to heat the dehumidified compressed gas flow in the dehumidified-carrier-gas conduit;
expanding the heated and dehumidified compressed gas flow in an expander in or coupled with the dehumidified-carrier-gas conduit, wherein the expansion of the heated and dehumidified gas flow generates motion, and wherein the motion generated in the expander is transferred to the compressor via a mechanical connection, where the compressor uses the transferred motion to compress the humidified gas flow; then
using a heat recovery system to extract heat from expanded dehumidified gas flow after leaving the expander;
using the heat recovery system to transfer the heat extracted from expanded dehumidified gas flow to the dehumidified compressed gas flow in the dehumidified-carrier-gas conduit after the dehumidified compressed gas flow leaves the dehumidification chamber but before the dehumidified compressed gas flow enters the expander; and
releasing an expanded gas flow without closed-loop recycling of the released gas flow through the above steps.

2. The method of claim 1 , wherein the motion is a rotation.

3. The method of claim 2 , wherein the rotation is transferred from the expander to the compressor via the mechanical connection, the mechanical connection being a shared shaft rotated by the expansion of the dehumidified gas flow in the expander.

4. The method of claim 1 , further comprising flowing the feed liquid through the at least one dehumidifier before introducing the feed liquid into the at least one humidifier, wherein the compressed humidified gas flow is dehumidified by transferring heat from the compressed humidified gas flow to the feed liquid in the at least one dehumidifier.

5. The method of claim 1 , further comprising heating the feed liquid en route to the at least one humidifier from the at least one dehumidifier with heat transferred from the expanded dehumidified gas flow after the expanded gas flow transfers heat to the dehumidified compressed gas flow.

6. The method of claim 4 , further comprising extracting feed liquid from an intermediate stage in the at least one humidifier and injecting the extracted feed liquid into the feed liquid flowing through the at least one dehumidifier at an intermediate stage in the at least one dehumidifier.

7. A system for purifying water via thermal-energy-driven mechanical compression humidification-dehumidification, comprising:
a humidifier including a carrier-gas input and a carrier-gas output and a feed-liquid input and a feed-liquid output;
a dehumidifier including a carrier-gas input and a carrier-gas output;
a humidified-carrier-gas conduit coupling the carrier-gas output of the humidifier and the carrier-gas input of the dehumidifier for gas flow therebetween;
a dehumidified-carrier-gas conduit coupled with the carrier-gas output of the dehumidifier;
a compressor in or coupled with the humidified-carrier-gas conduit and configured to compress the carrier gas passing from the humidifier to the dehumidifier;
an expander in or coupled with the dehumidified-carrier-gas conduit and configured to expand the carrier gas exiting the dehumidifier, wherein the expander is mechanically coupled with the compressor and is configured to generate motion with the expansion of the carrier gas and to transfer the motion to the compressor, and wherein the compressor is configured to compress the carrier gas via the transferred motion;
a heater configured to heat dehumidified carrier gas in the dehumidified-carrier-gas conduit between the dehumidifier and the expander; and
a heat recovery system configured to extract heat from carrier gas leaving the expander and to transfer the extracted heat to carrier gas in the dehumidified-carrier-gas conduit between the dehumidifier and the expander,
wherein the system for purifying water is configured to release carrier gas without closed-loop recycling of the released carrier gas after the carrier-gas expansion in the expander.

8. The system of claim 7 , wherein the expander is mechanically coupled with the compressor via a shaft configured for axial rotation.

9. The system of claim 7 , further comprising pumps configured to flow carrier gas and feed liquid through the conduits.

10. The system of claim 7 , further comprising:
a feed-liquid conduit extending between the humidifier and the dehumidifier; and
a heat exchanger configured to transfer heat from carrier gas in the dehumidified-carrier-gas conduit downstream from the expander to feed liquid in the feed-liquid conduit between the humidifier and the dehumidifier.

11. The system of claim 7 , further comprising an intermediate exchange conduit extending between an intermediate stage in the humidifier and an intermediate stage in the dehumidifier and configured to extract feed liquid from the intermediate stage in the humidifier and to inject the extracted feed liquid into the intermediate stage of the dehumidifier.

Assignees

• Massachusetts Inst Technology
• Univ King Fahd Pet & Minerals
• Univ King Fahd Pet & Minerals

Inventors

• Al-Qutub Amro
• Govindan Prakash Narayan
• Lienhard John H

Classifications

• C02F1/04

  by distillation or evaporation · CPC title

• C02F1/10 Primary

  by direct contact with a particulate solid or with a fluid, as a heat transfer medium · CPC title

• C02F1/041

  by means of vapour compression · CPC title

• B01D3/346

  the gas being used for removing vapours, e.g. transport gas · CPC title

• B01D1/28

  with vapour compression · CPC title