Electrochemical method for producing pure-oxygen gas and oxygen-lean gas from oxygen-containing gas mixtures

Patent metadata

Field	Value
Publication number	US-10017865-B2
Application number	US-201415034058-A
Country	US
Kind code	B2
Filing date	Nov 4, 2014
Priority date	Nov 5, 2013
Publication date	Jul 10, 2018
Grant date	Jul 10, 2018

Abstract

The present invention relates to an electrochemical method for continuously producing a pure-oxygen gas and an oxygen-lean gas from an oxygen-containing gas mixture. At least two water electrolyzer units and two power supply units are used, of which each former solely corresponds to each latter, respectively. The two power supply units are at least one power supply unit of recycling hydrogen energy and an externally-connected power supply unit. The power supply unit of recycling hydrogen energy consists of hydrogen fuel cells, and the externally-connected power supply unit is comprised of at least one of the following cells and/or power supply, e.g. (a) solar cell(s), (a) direct methanol fuel cell(s), and/or an AC grid. In terms of the electrical circuit, each power supply unit is solely connected with the corresponding water electrolyzer unit. Hydrogen produced by all the water electrolyzer units is delivered to feed the hydrogen fuel cells as a fuel, and oxygen produced by the water electrolyzer units is the pure oxygen of target product. A negative electrode and a positive electrode of the hydrogen fuel cells of the power supply unit of recycling hydrogen energy are fed by the hydrogen gas and an oxygen-containing gas mixture, respectively. The inlet hydrogen gas is connected with a cathode of hydrogen chamber of the water electrolyzer unit through a pipe. A gas-liquid separation is performed at the outlet of positive electrode, of which the outlet gas is produced as an oxygen-lean gas. By means of the present invention, a high-purity oxygen gas can be stably and continuously produced from air at low cost for any indoor and outdoor sites or a remote area.

First claim

The invention claimed is:

1. An electrochemical method for producing a pure-oxygen gas and an oxygen-lean gas from an oxygen-containing gas mixtures, the method comprising:
using at least two water electrolyzer units and at least two power supply units, of which each former solely corresponds to each latter, respectively;
wherein the at least two power supply units are at least one power supply unit of recycling hydrogen energy and one externally-connected power supply unit; the power supply unit of recycling hydrogen energy consists of hydrogen fuel cells, and the externally-connected power supply unit is comprised of at least one of the following cells and/or power supply: (a) solar cell(s), (a) direct methanol fuel cell(s), and/or an external alternating current grid;
in terms of an electrical circuit of the at least two water electrolyzers units, each power supply unit is solely connected with the corresponding water electrolyzer unit;
hydrogen produced by all the water electrolyzer units is gathered through a hydrogen pipe, and delivered to feed the hydrogen fuel cells as a fuel, and oxygen produced by all the water electrolyzer units is gathered and flows out through an oxygen pipe, so that the pure oxygen gas is produced;
a negative electrode and a positive electrode of the hydrogen fuel cells of the power supply unit of recycling hydrogen energy are fed by the hydrogen gas from the hydrogen pipe and an oxygen-containing gas mixture, respectively; the inlet hydrogen gas is connected with a cathode chamber of the water electrolyzer unit through a pipe, and a gas-liquid separation is performed at the outlet of positive electrode of the hydrogen fuel cell(s), of which the outlet gas is produced as an oxygen-lean gas and;
a main unit consists of at least one hydrogen fuel cell and one water electrolyzer;
a first auxiliary unit consists of at least one water electrolyzer, which is electrically connected with the externally-connected power supply unit, and is used for supplying hydrogen for the hydrogen fuel cells;
a second auxiliary unit consists of at least hydrogen fuel cells, which is used for further deoxygenating the oxygen-lean gas; and
the main unit, the first auxiliary unit and the second auxiliary unit are only in connection with each other by gas path, but not in electrical circuit connection with each other; the second auxiliary unit and the first auxiliary unit ( 1 ) are only connected by hydrogen gas path; a positive electrode of the hydrogen fuel cells of the second auxiliary unit is connected with that of the hydrogen fuel cells of the main unit through a gas-liquid separator to supply the oxygen-lean gas; and the hydrogen gas path of the first auxiliary unit of the water electrolyzer at the cathode is connected with the negative electrode of the fuel cells of the second auxiliary unit; and
the hydrogen fuel cells and the water electrolyzers constituting the main unit are in electrical circuit connection with each other in one-to-one correspondence; and
an external circuit of an auxiliary hydrogen fuel cell of the second auxiliary unit is only connected with an amperometer for monitoring a current or a load, and is not in circuit connection with any water electrolyzer;
wherein a further deoxygenated gas is obtained from the second auxiliary unit or if no current passes through the external circuit, it indicates that the inlet gas of the positive electrode of the second auxiliary unit hydrogen fuel cell is an oxygen-free gas.

2. The electrochemical method of claim 1 , characterized in that:
an anode and the cathode of said water electrolyzer units are separated by an electrolyte membrane, and are connected with a positive electrode and a negative electrode of the power supply unit, respectively.

3. The electrochemical method of claim 1 , characterized in that;
the positive electrode and the negative electrode of the hydrogen fuel cells of said power supply unit are separated by an electrolyte membrane to form two gas chambers; the gas chamber at the negative electrode is connected with the hydrogen pipe allowing the hydrogen produced by the water electrolyzer unit to flow in, and the gas chamber at the positive electrode is fed by the oxygen-containing gas mixture to satisfy the oxygen demanded by the hydrogen fuel cells using a fan or an air pump;
at least one of the following steps can be performed on the outlet oxygen-lean gas of the gas chamber at the positive electrode of the hydrogen fuel cells after gas-liquid separation, (1) to be vented to the outside, or used as a protective inert gas, and (2) to be further deoxygenated to obtain an oxygen-free gas.

4. The electrochemical method of claim 1 , characterized in that:
for the purpose of recycling water, water produced at the positive electrode of the hydrogen fuel cells of the power supply unit flows into a gas-liquid separator along with the outlet gas, and after gas-liquid separation the water flows back to the cathode and/or anode of the water electrolyzer.

5. The electrochemical method of claim 1 , characterized in that:
the cathode and anode of one of the at least two water electrolyzer of the water electrolyzer units are connected with the negative electrode and the positive electrode of the hydrogen fuel cells.

6. The electrochemical method of claim 1 , characterized in that:
a power supply unit of the direct methanol fuel cells produces and supplies power to the water electrolyzer by using methanol as a fuel to flow in a negative electrode, and using an oxygen-containing gas as an oxidizer to flow in a positive electrode; alternatively,
a power supply unit of the solar cells produces and supplies power to the water electrolyzer by directly using a commercial product of solar cells that is compatible with the water electrolyzers in terms of voltage and power; alternatively,
a power supply unit of the alternating current grid produces and supplies power to the water electrolyzer by directly using a commercial product of a direct current power supply to convert the alternating current grid, which is compatible with the water electrolyzer in terms of voltage and power.

7. The electrochemical method of claim 1 , characterized in that:
the externally-connected power supply unit uses the solar cells and the alternating current grid, or the solar cells and the direct methanol fuel cells simultaneously.

Assignees

• Univ Dalian Tech

Inventors

• Zhu Xiaobing
• Zhu Weikun
• Zhu Aimin
• Liu Jinglin
• Li Xiaosong

Classifications

• C25B15/08

  Supplying or removing reactants or electrolytes; Regeneration of electrolytes · CPC title

• C25B1/04 Primary

  by electrolysis of water · CPC title

• Y02E60/366

  Cross-Sectional Technologies · mapped topic

• Y02P20/132

  Cross-Sectional Technologies · mapped topic

• C25B9/18

  Chemistry & Metallurgy · mapped topic