Water electrolysis for hydrogen production – basic knowledge in the petrochemical industry

Thread Content

By immersing two electrodes that are close to each other in water and applying a direct current voltage between them, electrolysis of the water takes place; hydrogen is released near the cathode, while oxygen is released near the anode. The industrial production device for water electrolysis is the electrolyzer. To improve the electrical conductivity of water and reduce power consumption, the liquid in the electrolyzer is usually not pure water, but a KOH aqueous solution of a certain concentration. Currently, in domestic electrolyzers, the cell voltage is ≤ 2 V, and the maximum hydrogen production rate per unit is 300 Nm³·h⁻¹. The operating pressure of these electrolyzers can reach 410 MPa (for electrolyzers with a hydrogen production rate of ≤ 40 Nm³·h⁻¹, the operating pressure can reach 510 MPa). The temperature of the gas exiting the electrolyzer is around 90 °C, and after separation of alkaline solutions and moisture, the purity of hydrogen can reach 99.19%, while the purity of oxygen can reach 99.15%. If further processed by a purification device, the highest purity of hydrogen can reach 99,19999%. Main consumption quotas: raw desalinated water 0 1 82 kg, electricity 5 1 5 kW·h.