RU2508419C1 - Apparatus for electrolysis of water under pressure and method for operation thereof - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to an apparatus for electrolysis of water under pressure, which consists of an electrolysis cell with a water feed line connected to a supply unit, which is electrically connected to a control unit, receivers connected to the electrolysis cell through hydrogen and oxygen lines for accumulating hydrogen and oxygen, said receivers being fitted with hydrogen and oxygen pressure sensors, electrically connected to the control unit, valves for releasing hydrogen and oxygen from the apparatus fitted on the hydrogen and oxygen lines; each receiver is equipped with a water filling line, a water draining line and a sensor for measuring the amount of water, wherein the water filling and draining lines are fitted with valves, and the sensor for measuring the amount of water and the valves on the water draining lines are electrically connected to the control unit. The invention also relates to a method of operating the apparatus for electrolysis of water under pressure, which involves feeding water and electric current to the electrolysis cell, accumulating hydrogen and oxygen in the receivers, monitoring process parameters, levelling gas pressure and delivering the obtained gases to a consumer, wherein before the beginning of the operating cycle, the hydrogen and oxygen receivers are filled with water in amount of 15% to 30% of the volume of the corresponding receiver, and during operation, the amount of water is controlled, hydrogen and oxygen pressure is recorded and if the pressure drop of hydrogen and oxygen exceeds an allowable value, water is drained from that receiver where gas pressure is higher until pressure in the receivers levels.EFFECT: increasing cost-effectiveness of the apparatus by 15-20% by preventing loss of gases, high safety of operation by eliminating the possibility of mixing gases.3 cl, 1 dwg

Description

The invention relates to electrochemistry and can be used in electrolysis plants operating under pressure and containing receivers for the accumulation of working gases.

The electrolysis elements of these plants contain thin membranes on the surface of which an electrochemical reaction occurs. These membranes, according to the strength conditions, operate at a gas pressure difference of not more than several tens of kPa, which requires special equalization of the working gas pressures during the operation of electrolysis plants.

Electrolysis plants are known in which during their operation the pressure equalization of gases is carried out by releasing from the installation the gas whose pressure is higher. For this installation, they are equipped with appropriate valves (patents of the Russian Federation No. 2111285, 05/20/1998, IPC: С25В 1/12; No. 2102535, 01/20/1998, IPC: С25В 1/12; application JP 2006249496 (A), 09/14/2006, IPC : Н04В 7/26 (2006.01); Н04М 1/00 (2006.01); H04Q 7/38 (2006.01)). However, in the case when the gases produced by the electrolyzer — hydrogen and oxygen — must accumulate in the own receivers of the electrolysis unit, this method of regulation leads to gas losses, i.e. reduces installation efficiency.

Electrolysis plants are also known in which pressure equalization is carried out by using separators of electrolyzers as communicating vessels (for example, EP 2014799 (A1), 01/14/2009, IPC: C25B 1/12 (2006.01), C25B 15/08 (2006.01), patent RF №2219291, December 20, 2003, IPC: С25В 1/04 (2006.01)). Separators in the amount of two pieces are part of the electrolyzer and are designed to separate the corresponding gas - hydrogen or oxygen - from a mixture of gas and water coming from a battery of electrolysis cells. Water in the lower part of the separators under the influence of a differential pressure of gases can flow from one separator to another, thereby compensating for the differential pressure. The disadvantage of these inventions is that with a large pressure drop or when any line is depressurized, all water can pass into one separator, and then hydrogen and oxygen mix with the formation of detonating gas. Thus, the operation of such electrolysis plants is not safe enough.

Closest to the proposed technical solution is the pressure equalization system in the electrolyzer according to the patent US 7097748 (B2), 08/29/2006, IPC: С25В 9/20 (2006.01), Н01М 8/06 (2006.01), Н01М 8/18 (2006.01), C25B 1/08 (2006.01), selected for the prototype.

The patent describes an installation for electrolysis of water under pressure, which includes an electrolyzer with a water supply line connected to a power supply unit, which is electrically connected to the control unit, two receivers connected to the electrolyzer through hydrogen and oxygen lines for storing reaction water and part of hydrogen and oxygen with hydrogen and oxygen pressure sensors installed on them, a gas accumulator for storing another part of hydrogen and oxygen, valves for the release of hydrogen and oxygen from the installation, located on the hydrogen lines and oxygen, a differential pressure regulator in the lines of hydrogen and oxygen. Water is supplied to the electrolyzer by pumps from one or two receivers. The prototype method of operating an electrolysis installation under pressure consists in supplying water and electric current to the electrolysis cell, accumulating hydrogen and oxygen in the receivers, monitoring process parameters, equalizing gas pressures, and then delivering the resulting gases to the consumer. The equalization of gas pressures in the electrolysis unit is carried out using water-communicating vessels, a gas pressure regulator and a flexible partition between hydrogen and oxygen inside the battery. The receiver vessels communicating through water are formed by a water line connecting the receivers to each other and designed to level the water levels in the receivers. Water can flow between the receivers by gravity or by means of a leveling pump. Pressure equalization occurs by changing the volume of the receivers by moving water from the receiver with high pressure to the receiver with less pressure.

Gas pressure regulator, based on the release of gas from the installation with a higher pressure. When a part of the gas is released from the line with high pressure, pressure equalization occurs.

The flexible partition between hydrogen and oxygen inside the accumulator changes pressure during a pressure differential and thereby changes the ratio of gas volumes and evens out gas pressures.

The disadvantages of the electrolysis installation and its operation are:

- the presence of vessels communicating through water, as in analogues, which can lead to the fact that with a large pressure drop or when any line is depressurized, all water can go into one receiver, and then hydrogen and oxygen mix with the formation of an explosive mixture. This is all the more likely that there are no sensors for the amount of water in the receivers in the installation;

- loss of part of hydrogen or oxygen when the gas pressure regulator is triggered (for example, for an installation with a pressure of 35 MPa, gas loss due to an uneven increase in pressure during compression is 15-20% of the produced gas);

- the possibility of explosion of the resulting detonating gas in case of damage to the flexible partition used in the gas accumulator and separating explosive gases - hydrogen and oxygen, which are at high pressure.

The objective of the invention is to eliminate the above disadvantages of the prototype and that during operation of the installation for water electrolysis, with the accumulation of gases in the unit’s own receivers, equalize the gas pressures by changing the gas volumes of the receivers by controlled discharge of pre-filled water from them.

The technical result of the invention is to increase the efficiency of the installation by 15-20 percent by eliminating the loss of gases, as well as increasing the safety of its operation by eliminating the possibility of mixing gases.

The technical result is achieved by the fact that in the installation for electrolysis of water under pressure, consisting of an electrolyzer with a water supply line connected to a power supply unit, which is electrically connected to a control unit connected to the electrolyzer through hydrogen and oxygen lines of receivers for the accumulation of hydrogen and oxygen with installed on them pressure sensors of hydrogen and oxygen, electrically connected to the control unit, valves for the release of hydrogen and oxygen from the installation, located on the lines of hydrogen and oxygen, each p The receiver is equipped with a water filling line, a water drain line and a water quantity sensor, while valves are installed on the water filling and drain lines, and water quantity sensors and valves on the water drain lines are electrically connected to the control unit.

In addition, one of the receivers is equipped with a water supply line to the electrolyzer with a valve electrically connected to the control unit, while the electrolyzer is located at a level below this receiver.

The technical result is also achieved due to the fact that in the method of operation of the installation for electrolysis of water under pressure, which consists in supplying water and electric current to the electrolyzer, the accumulation of hydrogen and oxygen in the receivers, monitoring the process parameters, equalizing the gas pressures and subsequent delivery of the obtained gases to the consumer, before the start of the work cycle, the hydrogen and oxygen receivers fill with water from 15% to 30% of the volume of the corresponding receiver, and during the work, the amount of water in the receivers is controlled, the pressure is recorded ix hydrogen and oxygen in the respective receivers, and in case of exceeding the permissible differential pressures of hydrogen and oxygen produces water draining from the receiver, where the gas pressure is higher before the pressure equalization in the receiver.

The invention is illustrated in the drawing, which shows a diagram of the proposed installation for electrolysis of water under pressure.

It includes an electrolyzer 1 with a water supply line 6 connected to a power supply 24, which is electrically connected to a control unit 9, connected to the electrolyzer 1 through lines of hydrogen 4 and oxygen 5 receivers for the accumulation of hydrogen 2 and oxygen 3 with sensors installed on them the pressure of hydrogen 7 and oxygen 8, electrically connected to the control unit 9, valves for the release of hydrogen 10 and oxygen 11 from the installation, located on the lines of hydrogen 4 and oxygen 5. Each receiver 2 and 3 is equipped with a water filling line 12 and 13, a drain line 16 and 17 and a water quantity sensor 20 and 21, while valves 14 and 15 are installed on the water supply lines 12 and 13, respectively, valves 18 and 19 are installed on the water discharge lines 16 and 17, and water quantity sensors 20, 21 and valves 18, 19 are installed electrically connected to the control unit. The electrolyzer 1 and the control unit 9 are supplied with power from the power supply 24. Pressure sensors 7 and 8, water quantity sensors 20 and 21, as well as valves 18, 19, 23 are electrically connected to the control unit 9. Valves 10, 11, 14, 15 are controlled manually.

The installation may contain one or two independent lines for supplying water to the electrolysis cell 1. It is preferable to supply water from the hydrogen receiver 2 through line 22 with valve 23. In addition, water can be supplied to the electrolyzer 1 from an external line through water supply line 6.

Installation works as follows.

Before the start of the operation cycle, the electrolyzer 1, the control unit 9 and the power supply 24 are turned off, all the valves are closed, the overpressure of the gases in the receivers 2 and 3 is small or absent, there is no or little water in them. The total volume of the hydrogen receiver 2 together with the hydrogen line 4 should exceed the total volume of the oxygen receiver 3 together with the oxygen line 5 by about half, since the gas volumes are distributed in this proportion during electrolysis of water.

The work cycle begins by turning on the power supply 24 and the control unit 9. Then manually open the valves 14 and 15. Receivers 2 and 3 begin to fill with water along lines 12 and 13. The volume of water in each receiver after refueling should be from 15 to 30 % of the volume of the corresponding receiver. The amount of water in the receivers 2 and 3 is controlled using the sensors of the amount of water 20 and 21, respectively, and the control unit 9. After filling the water valves 14 and 15 are closed.

Then, the water supply to the electrolyzer 1 is turned on via line 22 (preferably) or along the line 6 and the power supply of the electrolyzer 1 is turned on from the power supply 24. In this case, hydrogen begins to fill the receiver 2 through line 4 and the receiver 3 begins to fill the oxygen through line 5. hydrogen and oxygen are measured using pressure sensors 7 and 8, respectively, and the associated control unit 9.

Due to the non-ideal compression of dissimilar gases between the pressures in receivers 2 and 3, a pressure drop occurs, which may approach the allowable limit. This limit is determined by the strength of the cells and is usually about 50 kPa. When this limit is reached, the control unit 9 opens the water drain valve from the receiver, the pressure of which is greater. If the pressure in the receiver 2 exceeds the pressure in the receiver 3, the valve 18 opens and the water from the receiver 2 is discharged from the unit via line 16. As soon as the pressure in the receivers is equal, the control unit 9 closes the valve 18. Similarly, if the pressure in the receiver 3 exceeds the pressure in receiver 2, valve 19 opens and water from the receiver 3 is discharged from the unit through line 17. During operation, the amount of water in the receivers 2 and 3 is constantly monitored using water quantity sensors 20 and 21. If the water in any of the receivers runs out, the electrolyzer 1 coma Nde control unit 9 is turned off. If the gas pressure in the receivers by pressure sensors 7 or 8 reaches the maximum permissible, the cell 1 is also turned off. The process of managing water discharge is carried out in such a way that by the time the maximum pressure is reached in one of the receivers, usually in a hydrogen receiver, a minimum amount of water remains. To drain excessively charged water, both valves 18 and 19 can open simultaneously.

The amount of initially refilled water depends on the ultimate gas pressure and the exact ratio of receiver volumes. For real (non-ideal) gases, the calculation shows that the hydrogen pressure during electrolysis increases faster than the oxygen pressure. When the volume ratio of the receivers is 2: 1 and the hydrogen pressure is reached, for example, 35 MPa, the oxygen pressure will be 30 MPa, i.e. For pressure equalization, it is necessary that by this moment the volume of water equal to 16% of the volume of the receiver remain in the oxygen receiver, and the water should be completely drained in the hydrogen receiver. If the volume ratio of the receivers is other than 2: 1, for example 2.3: 1, the volume of water drained from both receivers by the end of the process will be approximately equal. Therefore, the exact amount of water poured into the receivers is established during the testing of a particular installation.

It is advisable, although not necessary, to use water discharged from one of the receivers in the electrolyzer to produce gases. This greatly simplifies the water supply scheme, since the receivers and the electrolyzer are under the same pressure. To implement this scheme, the electrolyzer should be located below the water level in the receiver, and the installation should be equipped with a water supply line 22 to the electrolyzer 1 with a valve 23 connected to the control unit 9. To produce hydrogen and oxygen with a maximum pressure of 35 MPa in one operation cycle of the electrolyzer a quantity of water equal to 25% of the volume of the hydrogen receiver is required. Therefore, it is advisable to fill in the receivers a little more, for example 30% of the water, and in the process, most of the water should be supplied to the electrolyzer from the hydrogen receiver, and the rest of the water should be used for precise pressure control.

Valves 10 and 11 are used to supply hydrogen and oxygen to external consumers.

Structurally, line 12 and valve 14 can be combined with line 16 and valve 18, and line 13 and valve 15 with line 17 and valve 19.

As sensors for the amount of water 20 and 21, level sensors of any type or weight sensors in the supports of the receivers can be used.

Claims (3)

1. Installation for electrolysis of water under pressure, consisting of an electrolyzer with a water supply line connected to a power supply unit, which is electrically connected to a control unit connected to the electrolyzer via hydrogen and oxygen lines of receivers for the accumulation of hydrogen and oxygen with hydrogen pressure sensors installed on them and oxygen electrically connected to the control unit, valves for the release of hydrogen and oxygen from the installation, located on the lines of hydrogen and oxygen, characterized in that each receiver is equipped with a line water filling, a water drain line and a water quantity sensor, while valves are installed on the water filling and drain lines, and water quantity sensors and valves on the water drain lines are electrically connected to the control unit. 2. Installation according to claim 1, characterized in that one of the receivers is equipped with a water supply line to the electrolyzer with a valve electrically connected to the control unit, while the electrolyzer is located at a level below this receiver. 3. The method of operation of the installation for electrolysis of water under pressure, which consists in supplying water and electric current to the electrolysis cell, accumulating hydrogen and oxygen in the receivers, monitoring process parameters, equalizing gas pressures and subsequently delivering the obtained gases to the consumer, characterized in that before starting the operation cycle hydrogen and oxygen receivers fill with water from 15% to 30% of the volume of the corresponding receiver, and during operation they control the amount of water in the receivers, record the pressure of hydrogen and oxygen in accordance with vuyuschih receivers and in case of exceeding the permissible differential pressures of hydrogen and oxygen produces water draining from the receiver, where the gas pressure is higher before the pressure equalization in the receiver.

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