Hydrochloric acid cycles
Concentrated aqueous hydrochloric acid is fed to the electroIyzer within a temperature range of 65 - 70°C. The process has hydrochloric acid recycles for anolyte and catholyte. The two compartments receive aqueous acid feeds of different concentrations, the anode compartment approx. 23% (wt.) and the cathode approx. 21% (wt.). Chlorine and hydrogen are generated inside the cell. Depleted hydrochloric acid with a concentration of 17% (wt.) leaves both compartments of the cell. The anolyte acid flows through the anode chambers connected in parallel and the catholyte acid flows similarly through the cathode chambers. Any solid impurities are retained by filters, while the heat balance of the process is maintained using heat exchangers. A partial stream of the 17% (wt.) acid feedstock is diverted from the catholyte recycle, re-concentrated with hydrogen chloride to approx. 28% (wt.) in the absorption unit, and then fed back to both electrolyte cycles.
Benefits of thyssenkrupp Uhde Chlorine Engineers‘s diaphragm electrolysis technology
- Careful use of resources considering ecological responsibility.
- Diaphragm Electrolysis produces H2 and has no need of O2 (compared to HCl-ODC).
- Significant interest to make business independent from HCl & Cl2 market prices and caustic market situation.
- Risks of Chlorine transport avoided.
- No costs related to hydrochloric acid neutralization or disposal.
- Wide & flexible plant operating window eases adaptations to the needs of related production processes.
- Electrolyzer design ensures optimal maintenance flexibility and eases potential capacity increases.
- High robustness and durability under corrosive conditions.
- Contribution of the collaboration with Covestro in terms of lab and test facilities.
- Proven and reliable technology.