CZ224491A3 - Electrolytic source of pressurized hydrogen - Google Patents

Abstract

An electrolytic source for the preparation of highly pure pressurised hydrogen, formed by a pressure vessel (1) with release valves (7, 8), filled with electrolyte (2), in which there are submerged electrodes (3,4), from which the negative overpressure porous diffused electrode (4) is connected by its hydrogen outlet (5), separated from the inner space of the pressure vessel (1), with the hydrogen tank (6). Simultaneously the equation Vo d'1/2VH is valid, where Vo represents the volume of the space in the pressure vessel above the electrolyte, filled with oxygen, and Vx the volume of the hydrogen tank.<IMAGE>

Description

Technical field

The invention relates to pure pressurized hydrogen

an electrolytic source for preparing the hydrogen.

BACKGROUND OF THE INVENTION

In pressurized electrolysers producing hydrogen and oxygen, the chalice construction of cells connected electrically in series is used. The individual cells consist of a pressure vessel divided by a vertical partition into two parts, with an opening for the free movement of the electrolyte through which the cell is filled between the lower edge of the partition and the bottom of the pressure vessel. In the electrolyte, a negative hydrogen electrode is immersed in one compartment of the pressure vessel and a positive oxygen electrode is immersed in the other compartment. In the lid of the pressure vessel, outlets for hydrogen and oxygen are provided above the respective compartments, provided with discharge valves. When the voltage is connected to the electrodes, both gases are generated. Their increased overpressure is achieved by closing the outlet valves, and the gases must be taken proportionally so that the pressures in both parts of the vessel are the same. Otherwise, an electrolyte spill would occur in the electrolyser system, i.e. a decrease in its level in an area with a higher gas pressure and, conversely, an increase in the electrolyte level in an area with a lower gas pressure level. Lowering the electrolyte level in one part of the vessel below the lower level of the partition would then result in mixing of the two gases. Ensuring the safe operation of these electrolyzer designs requires relatively complex control and safety systems that must maintain the same pressure of the individual gases with the higher the accuracy, the greater the pressure. The maximum allowable pressure difference is approx. 1 kPa, which corresponds to a 10 cm water column. The disadvantage of these electrolytic sources is furthermore a high oxygen content in the extracted hydrogen and vice versa. If high purity of gases is required, it is necessary to purify them.

At the same time, a considerable amount of electrolyte aerosol is contained in the off-gases, which is additionally separated in separators.

Another device for generating hydrogen under positive pressure is a liquid diffusion porous electrode. Oxygen is a waste of this type of generator and is released freely into the surrounding atmosphere, so that pressure control is not required. The disadvantage, however, is the low hydrogen overpressure, which in this case is limited by the capillary pressure in the pores of the electrode coating layers and reaches a maximum value of 200 kPa.

SUMMARY OF THE INVENTION

These drawbacks are overcome by an electrolytic source of pressurized hydrogen, consisting of a pressure vessel with discharge valves, filled with an electrolyte in which the electrodes are immersed. The principle of the solution is that the negative positive pressure porous diffusion electrode is connected with its hydrogen outlet, separated from the inner space of the pressure vessel, to the hydrogen reservoir, whereby the following applies:

V <1/2 V ,, where

O ri

V represents the volume of the pressure vessel space above the electrolyte, filled with oxygen and

V ^ | volume of hydrogen reservoir.

The electrolytic source according to the invention allows the removal of hydrogen under positive pressure, the value of which is substantially limited only by the strength of the pressure vessel, the hydrogen reservoir and their accessories. Another distinctive feature of the source is the generation of completely pure hydrogen without the addition of oxygen and electrolyte aerosol.

When the inequality V <1 / 2V _{U is} fulfilled, where equality is the limit by π condition, the oxygen pressure in the pressure vessel rises faster than the pressure of the reservoir, as the volumes of hydrogen and oxygen evolved are always in the ratio: 1. Necessary oxygen pressure is controlled by intermittent periodic discharge so that the condition is still present

BBBB ^ SSS ^ 5S95EES BBKHHMHHW where

P is the capillary electrode pressure

P _H hydrogen pressure in reservoir a

P _Q oxygen pressure in the pressure vessel (above the electrolyte).

The oxygen pressure may then vary within the range given by the capillary pressure P 1. From the above it is clear that the demands on control accuracy are up to two orders of magnitude lower compared to the known solution, which significantly improves the reliability of the system.

The requirement of the pressure difference range of the two gases results from the fact that in the case where <θ <(P ^ -P ^) is valid, hydrogen leaks through the pores of the electrode cover layer into the electrolyte.

If the condition of the left side of the unevenness is not met, ie, when P _Q P _H , an emergency condition occurs in which the electrolyte leaks through the electrode coating layers into its interior space and further through the electrode outlet to the hydrogen reservoir.

Overview of the drawings

An electrolytic source of pressurized hydrogen according to the invention is schematically shown in the figure.

DETAILED DESCRIPTION OF THE INVENTION

The device consists of a pressure vessel 7 filled with an electrolyte 2 in which the positive oxygen electrode 3 ^{and the} negative hydrogen electrode 6 are immersed. The hydrogen liquid porous diffusion electrode is connected with its hydrogen outlet to a hydrogen reservoir 6 which is provided at the outlet with a hydrogen discharge valve 7. The pressure vessel 7 has an outlet with an oxygen outlet valve 8 in its upper part in the space above the electrolyte 2. The control of both valves 8, 8 is controlled by a control system (not shown).

Industrial applicability

The electrolytic source of the invention can be used to obtain highly pure pressurized hydrogen.

? 2Z4Y - 97 A /

Claims (1)

PATENT CLAIMS An electrolytic source of pressurized hydrogen, consisting of a pressure vessel provided with drain valves and filled with electrolyte, in which the positive and negative electrodes are immersed, is characterized in that the negative positive pressure porous diffusion electrode (4) is connected by its hydrogen outlet (5) separated from the interior pressure receptacles (1), with a reservoir (6) of hydrogen, the following shall apply: V 1/2 Vj, o H where V _q ... the volume of oxygen-filled space of the pressure vessel (1) above the electrolyte (2) V. hydrogen tank capacity (6) league ί ΑΛ3Γ80V ^: I, λΖ31γΝλΛ OHd I avgn l 6 HA '8 L Wfl C t T ť c o