Method for operating an electrolysis plant

Abstract

The invention relates to a method for operating an electrolysis plant (01), wherein deionized water (05) provided by a water treatment device (04) is split into hydrogen and oxygen in an electrolyzer (06). Waste heat generated in the electrolyzer (06) is fed to a cooling device (07) via a cooling circuit. To support the cooling, ion-containing waste water (02) accumulated in the water treatment device (04) is fed to the cooling device (07).

Description

Technical Field

[0001] The present invention relates to an electrolysis facility having an electrolyzer for generating hydrogen by means of an electric current, wherein a cooling device with a cooling circuit is used so that waste heat generated in the electrolyzer during the process can be extracted. Background Technology

[0002] Electrolysis facilities are known from the prior art in various implementations. The central functional block in an electrolysis facility is the electrolyzer, which typically uses either a so-called alkaline electrolyzer or a so-called PEM electrolyzer. In both cases, it is necessary to supply the electrolyzer with as little conductive pure water as possible for electrolysis. For this purpose, a water treatment unit with a deionization device is typically used. Inevitably, a more strongly charged ionized wastewater is generated during deionization, and this wastewater is also discharged as such "wastewater".

[0003] Waste heat is generated during electrolysis, so the electrolyzer is usually circulated with a coolant. The coolant is then cooled again in a cooling device.

[0004] Significant waste heat is generated in larger facilities, creating a requirement for sufficient cooling capacity in the cooling system.

[0005] To address these problems, electrically operated ventilation systems can be used, for example, to support convection. However, this has the disadvantage of additional current consumption due to electrolysis. Furthermore, ambient temperature limits the achievable temperature of the coolant, which can be problematic, especially in areas with typically high external temperatures.

[0006] An advantageous method of utilizing the heat accumulated during electrolysis is described in WO 2013 / 113631A1. It is proposed here that the waste heat from the electrolyzer be directly supplied to a water treatment unit. Thus, the supplied raw water is heated by the waste heat to support deionization. Depending on site conditions, the large water consumption in this solution may be advantageous or disadvantageous. In this regard, the solution can be meaningfully used when additional water can be supplied to other applications.

[0007] In alternative implementations, a vaporization cooling device is preferred, thereby achieving high cooling power without a large energy input. In particular, it is therefore feasible to cool the coolant to below ambient temperature. Obviously, this requires the supply of water to achieve wet cooling.

[0008] Electrolysis facilities are particularly suitable when electricity generated using renewable energy sources, especially photovoltaics, is available. Correspondingly, larger electrolysis facilities are used especially in areas with high solar radiation. This is typically associated with high ambient temperatures and low water availability. This leads to the problem that convection cooling results in high power losses due to the ventilation systems used. Furthermore, the desired low temperature of the coolant is sometimes unattainable by convection cooling. Therefore, vaporization cooling is often used, which, however, exacerbates the water shortage problem and incurs high water costs. Summary of the Invention

[0009] The object of this invention is to improve hydrogen production in a cost-effective manner.

[0010] A method for operating an electrolysis facility according to the invention, with improved efficiency, is provided herein. Advantageous embodiments are the subject of the following description.

[0011] These electrolysis facilities include an electrolyzer as a main component, in which electrical energy is used to produce hydrogen and oxygen from water during operation of the electrolysis facility.

[0012] Therefore, a water supply system is first required to provide industrial water. Due to the high requirements for purity and minimum conductivity, a water treatment system is also needed. Correspondingly, the water treatment system is connected to the water supply system so that industrial water is delivered to the water treatment system during the operation of the electrolysis facility. In the water treatment system, the industrial water is purified where necessary and deionized in all cases. Correspondingly, deionized ultrapure water—hereinafter referred to as deionized water—is produced.

[0013] It should be noted that deionized water is not necessarily pure H2O. Rather, deionized water has the following qualities, which are necessary for its use in electrolysis, requiring a certain level of purity and, in particular, the presence of as few conductive ions as possible.

[0014] In the process of deionization to separate ions from industrial water, ion-containing wastewater inevitably accumulates.

[0015] The water treatment unit is obviously connected to the electrolyzer, in which deionized water is supplied to the electrolyzer during the operation of the electrolysis facility.

[0016] In addition, these electrolysis facilities have cooling devices. During operation, the electrolyzer generates waste heat, which must be removed. For this purpose, the electrolyzer is connected to a cooling device so that the waste heat generated in the electrolyzer can be removed by the cooling device.

[0017] According to the present invention, the water treatment apparatus is also connected to a cooling apparatus, wherein ion-containing wastewater accumulated in the water treatment apparatus is supplied to the cooling apparatus for cooling purposes.

[0018] To date, it has been unacceptable, in principle, to refuse the continued use of ionized wastewater accumulated in water treatment units within electrolysis facilities, as the quality is considered completely inadequate.

[0019] However, in accordance with this, the solution according to the invention uses ion-containing wastewater for cooling. This reduces water consumption in the electrolysis facility, thereby improving acceptance of the electrolysis facility, especially in areas with water shortages, and significantly reducing the cost of water supply.

[0020] To facilitate cooling, a cooling circuit is used, connecting the electrolyzer to a cooling device. A cooled coolant is supplied to the electrolyzer, which becomes heated during operation. The heated coolant is then transported in the circuit to the cooling device, where it is cooled again before being conducted back to the electrolyzer.

[0021] In the methods used to operate electrolysis facilities, it is particularly advantageous to consider the higher load caused by ion-containing wastewater. For this purpose, it is advantageous to shorten the maintenance interval by at least 20% from the comparative time period. The comparative time period here refers to the theoretical maintenance interval, which is appropriate when industrial water is used directly for cooling without the use of ion-containing wastewater, given that the existing facility technology is the same.

[0022] It can be suggested that other measures be taken to extend the maintenance interval, but if industrial water is used directly, these other measures are not required. In this case, facilities with other measures can still be considered for determining the comparison time period.

[0023] While shorter maintenance intervals result in higher costs and, if necessary, more frequent downtime—or consequently, higher installation costs and ongoing costs that are compensated for by other measures—the higher maintenance costs are less significant in water-scarce regions compared to the water consumption that would otherwise be required. Attached Figure Description

[0024] The following figures schematically illustrate one embodiment of an electrolysis facility according to the prior art—see Figure 1 —and the electrolysis apparatus according to the invention—see also Figure 2 . Detailed Implementation

[0025] Electrolysis facility 11 based on existing technology — Figure 1—The two embodiments, namely the electrolysis facility 01 according to the invention, include an electrolyzer 06 as a main component. Here, an electric current is used to decompose the reactant water H2O into the products hydrogen H2 and oxygen O2. Obviously, water—i.e., deionized water—is required for the process.

[0026] Therefore, the accompanying drawings schematically illustrate a supply device for industrial water 03, which leads to a water treatment unit 04. In the water treatment unit 04, the industrial water 03 is purified, and in all cases, deionized. This provides deionized water 05, which is then supplied to an electrolyzer 06.

[0027] Waste heat is generated during the electrolysis process and must be removed. For this purpose, the electrolyzer 06 is connected to a cooling device 07 via a cooling circuit. The cooling device 07 then cools the coolant that was previously heated in the electrolyzer 06.

[0028] Wastewater containing ions, such as O2 and I2, is inevitably generated in water treatment devices.

[0029] Here—as Figure 1 As schematically shown—in accordance with the standard, wastewater 12 is drawn from the electrolysis facility 11. However, for extremely effective cooling, especially in hot regions, it is necessary to supply water to the cooling unit 07, particularly for vaporization cooling. For this purpose, the cooling unit 07 is also connected to a water supply system, so that industrial water 03 is supplied to the cooling unit 07.

[0030] In contrast, according to the present invention—as in Figure 2 As shown in the diagram, from this point onward, ion-containing wastewater 02 is transported from the water preparation unit to the cooling unit 07. Here, it is generally necessary to shorten maintenance intervals, thereby reducing water consumption.

Claims

1. A method for generating hydrogen using an electrolysis facility (01), in - Hydrogen and oxygen are produced from deionized water (05) using electrical energy in an electrolyzer (06), and this... - The industrial water (03) is transported to the water treatment unit (04) by the water supply unit. - The industrial water (03) is purified and deionized in the water treatment device (04), wherein the deionized water (05) is generated and ion-containing wastewater (02) is accumulated. - The deionized water (05) is supplied to the electrolyzer (06). And at the same time - The ion-containing wastewater (02) is discharged from the water treatment device (04) and transported to the cooling device (07). And among them - The waste heat generated in the electrolyzer (06) is extracted by means of the cooling device (07).

2. The method according to claim 1, The coolant is heated in a loop in the electrolyzer (06) and cooled in the cooling device (07).

3. The method according to claim 1 or 2, The cooling device (07) mentioned therein includes a vaporization cooling device.

4. The method according to claim 1 or 2, In the cooling device (07), deposits are removed at regular maintenance intervals, wherein the maintenance intervals are shortened by at least 20% of the duration of a comparative time period, wherein the comparative time period is the interval after which deposits are removed when only industrial water (03) is supplied to the cooling device (07).

5. The method according to claim 3, In the cooling device (07), deposits are removed at regular maintenance intervals, wherein the maintenance intervals are shortened by at least 20% of the duration of a comparative time period, wherein the comparative time period is the interval after which deposits are removed when only industrial water (03) is supplied to the cooling device (07).

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