RU2470096C1 - High-pressure water cell and method of its operation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to hydrogen power engineering and may be used at hydrogen filling stations for future-technology motor transport running on fuel cells. Proposed cell comprises fuel-cell battery consisting of, at least, two units differing in quantity of fuel cells, each being provided with their separate pipelines with water feed valves and those to discharge from said units. Note here that oxygen is discharged beyond the casing while hydrogen is discharged therein. Said casing is divided into, at least, two different-strength sections by tight partition. Stronger section accommodates units with smaller cells. Method of operation comprises water feed into fuel-cell battery composed of two sections to decompose electrolysis gases, discharging the latter, cutting off supply of cells after reaching maximum tolerable pressure. Note here that hydrogen communication between two sections allows cut off, first, one section with larger quantity of cells in due time and, then, that with smaller quantity of cells.

EFFECT: optimised hydrogen generation, safe operation.

2 cl, 2 dwg

Description

The invention relates to hydrogen energy and can be used at hydrogen fueling stations of promising fuel cell vehicles.

Many gas-dynamic plants include two units of the same type, sequentially performing the same function in different ranges of the operating parameter. Such installations include, for example, compressors having several stages for gas compression or vacuum installations, including a foreline pump and a deep vacuum pump. Any of these traditional designs can be considered as an analogue of the proposed solution (especially regarding the principle of operation).

Known two-stage gas compressor, close to the proposed electrolytic water (EV) high pressure (VD). Its disadvantages (in comparison with the electrolyzer) are obvious and are determined by the complexity of the design of the compressors and the presence of moving parts in them (high cost, low resource, complexity of maintenance, etc.).

In addition, for the compressor to work, a supply of the working fluid, hydrogen, is required, while the EV receives hydrogen from ordinary water, which is safer.

The electrolyzer was selected as a prototype (patent No. 2258099 dated 08/10/05; IPC7: С25В 1/12), the main element of which is a battery of electrolysis cells (BEY), equipped with a cooling system and placed in a rugged airtight housing having an internal partition and pipelines with valves for supplying reaction (intended for decomposition) water and removal of electrolysis gases of hydrogen and oxygen.

The electrolyzer prototype works as follows. After turning on the water supply system and supplying power to the battery of electrolysis cells (BEY), the decomposition of water by current begins. The accumulation of electrolysis gases in the battery is carried out separately, without the formation of an explosive mixture. In the process, the battery is cooled due to the internal circulation of the electrolyte solution, which is carried out thanks to the special sectioning of the cell cavity.

The disadvantage of the prototype is its unsuitability for work in systems for refueling vehicles with hydrogen, where it takes a minimum time to produce a given and a sufficiently large amount of hydrogen. To realize the large productivity of the electrolyzer, a correspondingly large BEI with a cooling system and, accordingly, a large-sized robust housing capable of accommodating both the battery itself and its service systems are required. The mass, volume and cost of such a vessel, designed for high pressure, will be very large.

In addition, the large-sized high-pressure vessel necessary in this case is explosive and requires special maintenance regulations. All this complicates the operation of the electrolyzer.

When operating such an electrolytic cell at high pressures (this occurs at the final stages of refueling), a decrease in productivity is required, since at high refueling speeds, overheating of the refueling tank and the cell itself is possible. This is especially significant when refueling with hydrogen, which has the highest thermal conductivity among gases. The design of the prototype does not allow for performance adjustment.

The objective of the proposed technical solution is the development of a high-pressure water electrolysis cell (HPHM), having a minimum explosion hazard and a minimum time to produce a given amount of high-pressure hydrogen (up to ~ 400 atm.) Pressure.

The technical result of the invention is the optimization of the hydrogen generation mode for the operating conditions of a hydrogen gas station (high pressure level, minimum operating time), as well as improving the safety of the electrolyzer.

The technical result is achieved due to the fact that in the electrolytic cell of high pressure water, consisting of a sealed housing, a battery of electrolysis cells and a partition placed inside the housing, pipelines with valves connected to the battery of electrolysis cells for its water supply and for separate removal of hydrogen and oxygen from it , the battery of electrolysis cells consists of at least two blocks, different in number of cells, each of which has its own pipelines with valves for water supply and for separate drainage gases from the blocks, with oxygen being discharged outside the housing, and hydrogen inside the housing, while the housing is divided by a sealed partition into at least two different-strength sections connected by a pipeline to the valve, one of which contains a unit with fewer cells, and in the other, less durable, a block with a large number of cells equipped with a cooling system, while the more durable section is equipped with a pipeline with a valve for the removal of hydrogen.

The technical result is also achieved by the fact that in the method of operating the high-pressure water electrolyzer, including supplying water and power to the battery of electrolysis cells, decomposing water by current, issuing electrolysis gases, as well as turning off the power to the electrolysis cells after reaching the maximum allowable pressure, the battery of electrolysis cells and the housing is divided into at least two different in the number of unit cells and into two sections, respectively, while the decomposition of water is carried out first in all electrolysis cells cells and in the presence of pneumatic hydrogen communication between the sections, after reaching the pressure maximum permissible for the section in which the unit with a large number of cells is located, the operation of this unit stops and the section is sealed, and after reaching the pressure maximum permissible for the electrolyzer, they turn off and the section in which the block with fewer cells is located.

The essence of the invention is as follows (both for the device and for the method of its operation).

The operation of the electrolyzer with high productivity in a wide pressure range is problematic, since the fast "pumping" of cylinders (consumer cylinders or plant own cylinders) leads to their overheating, especially in the high pressure region and especially for hydrogen. Therefore, with a high productivity and, accordingly, with a cooling system, the electrolyzer operates only at the beginning of the process. For this purpose, a large block with high performance is mainly used, which is placed together with its auxiliary equipment in a larger section of the housing. The small block of cells also works, while the sections of the body are pneumatically connected through hydrogen.

Subsequently, at high pressures, it is necessary to reduce the rate of hydrogen generation, and for this you can use only a small block of cells operating without cooling and located in the second section of the housing, which has a small volume.

The design of this electrolyzer allows you to provide:

- minimum operating time (minimum time to generate a given amount of hydrogen), that is, the minimum consumer refueling time;

- the maximum explosion safety of the operation, since only a small part of the electrolyzer is located under high pressure (the explosion safety of the vessel is estimated by the product of its volume and maximum working pressure. This assessment is used, in particular, by the Gorgostekhnadzor).

The invention is illustrated by drawings: in Fig.1 shows the basic design of the cell; figure 2 - graphs of the time variation of the pressure in the cell and the flow rate of the generated gases.

Accepted designations:

1 - sealed housing;

2 - block with a large number of electrolysis cells (EJ);

3 - block with a smaller amount of EE;

4, 5 - sections of the body;

6 - sealed partition;

7 - cooling system of the unit with a large number of EE;

8 - pipeline for supplying water to the unit with a large amount of EE;

9 - pipeline for supplying water to the unit with a smaller amount of EE;

12 - pipeline for the removal of oxygen from the block with a large number of EE;

13 - pipeline for the removal of oxygen from the block with a smaller amount of EE;

16 - pipeline for removal from the block with a large amount of EH of hydrogen;

17 - pipeline for removal from the block with a smaller amount of EH of hydrogen;

18 - connecting pipe of hydrogen;

20 - pipeline for the removal of hydrogen from the sealed enclosure;

10, 11, 14, 15, 19, 21 - valves;

22 - pressure change in the housing section with a larger number of cells;

23 - pressure change in the housing section with fewer cells.

The sealed housing (1) of the electrolyzer is divided by a partition (6) into sections (4) and (5) with different volumes and working pressures. A larger (and less durable) section (4) contains a block (2) with more cells and a cooling system (7). Block (2) has a pipeline for supplying water (8) with a valve (10), as well as pipelines for the release of oxygen (12) with a valve (14) and the release of hydrogen (16). The hydrogen output from the BAY (2) is produced inside the section (4).

In the smaller (and more durable) section (5) of the housing (1) there is a smaller BEI (3), also equipped with a pipeline for supplying water (9) with a valve (11), pipelines for oxygen supply (13) with a valve (15) and the release of hydrogen (17) into the section (5).

Sections (4), (5) of the housing (1) are pneumatically connected by a pipeline (18) to a valve (19). Hydrogen is dispensed from the cell through a pipe (20) with a valve (21).

The "two-stage" electrolyzer operates as follows. First, both BEY (2), (3) work in sections (4), (5). In this case, oxygen is released via pipelines (12), (13) with valves (14) and (15) open, respectively. Hydrogen is discharged from the cavity of the smaller section (5) through the pipeline (20) with the valve (21) open. At the same time, from both BEY (2), (3) hydrogen leaves inside the corresponding sections, the pressure in which remains the same, since the valve (19) is open on the connecting pipe (18). In Fig.2, this corresponds to the joint arrangement of lines (22) and (23). At this time, the cooling system also works (7). After reaching the maximum pressure for section (4), the block of cells (2) is turned off and sealed, the valves (14, 19) of this section are closed, and only the cell section (5) continues to work. In figure 2, this corresponds to the point of divergence of lines (22, 23).

After reaching the maximum working pressure of the electrolyzer, the cell block (3) is also turned off, the valves (15), (21) of the section (5) are closed, the electrolyzer stops working, the valves (10), (11) are closed on the water supply pipelines (8), ( 9).

Thus, the proposed "two-stage" electrolyzer of high pressure water allows the most safe and fast to refuel with high pressure cylinders hydrogen.

Claims (2)

1. High pressure water electrolyzer, consisting of a sealed enclosure, a battery of electrolysis cells and a partition placed inside the housing, pipelines with valves connected to the battery of electrolysis cells for its water supply and for separate removal of hydrogen and oxygen from it, characterized in that the electrolysis battery cells consists of at least two different in number of cell blocks, each of which has its own pipelines with valves for water supply and for the separate removal of gases from the blocks, and oxygen e is discharged beyond the outer borders of the casing, and hydrogen is discharged into the casing, while the casing is divided by a sealed partition into at least two different-strength sections connected by a pipeline to the valve, in one of which there is a block with fewer cells, and in the other, less durable , - a block with a large number of cells equipped with a cooling system, while the more robust section is equipped with a pipeline with a valve for hydrogen output. 2. A method of operating a high-pressure water electrolyzer, including supplying water and power to the battery of electrolysis cells, decomposing water by current, dispensing electrolysis gases, turning off the power to the electrolysis cells after reaching the maximum allowable pressure, characterized in that the battery of electrolysis cells and the housing are separated by at least at least two different in the number of unit cells and into two sections, respectively, while the decomposition of water is carried out first in all electrolysis cells and in the presence of pneumatic hydrogen communication between the sections, after reaching the pressure maximum permissible for the section in which the unit with a large number of cells is located, the operation of this unit stops and the section is sealed, and after reaching the pressure maximum permissible for the cell, the section in which the unit is located with fewer cells.

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