Chlorine: a strategic chemical for modern industry
Chlorine is one of the most widely used industrial chemicals worldwide. It is produced through an electrolytic process from brine and serves as a fundamental building block in modern chemical industries.
Because of its chemical reactivity, chlorine enables the production of materials and compounds essential to water treatment, agriculture, pharmaceuticals, polymers, fuels, and numerous industrial applications.
Modern chlorine production is based on large-scale industrial electrolysis operating at high current levels. As industrial systems evolve toward greater electrification and efficiency, the performance of power conversion systems becomes increasingly relevant.
Transformer-rectifier technology remains a core component in chlor-alkali plants.
How chlorine is produced: the chlor-alkali process
In modern membrane technology, electric current passes through a sodium chloride solution, separating it into chlorine gas, hydrogen, and sodium hydroxide. [1]
The process requires a continuous supply of direct current under controlled operating conditions.
Industrial electrolysis in chlor-alkali plants typically involves:
- High DC currents
- Stable voltage levels
- Consistent operating parameters
- Rapid response to power supply variations
Electrical supply quality directly influences overall plant performance.
Power conversion as a critical enabler in chlor-alkali plants
In chlor-alkali production, power conversion infrastructure connects the electrical grid to the electrochemical process.
Transformer-rectifier systems convert grid-supplied AC power into controlled DC current, maintaining voltage and current within defined operating ranges.
Their design influences system integration, load management, and the overall electrical architecture of the plant.
Designing for safety: managing critical events
While stable operation is essential, chlor-alkali plants must also be designed to handle non-routine operating scenarios.
Grid variations, equipment faults, or emergency conditions demand a controlled and predictable system response.
Modern high-current systems are designed to:
- Reduce current rapidly when required
- Coordinate with plant protection systems
- Protect electrolysis cells from electrical stress
- Restore normal operation through controlled ramping
Load reduction features allow the DC output current to be lowered immediately upon receiving a safety signal and gradually restored once conditions return to normal.
Safety is integrated into the electrical architecture from the design stage.
Reliability as a production factor: FRIEM’s approach
In chlor-alkali plants, reliability depends on the design and integration of the rectifier system within the plant’s electrical infrastructure.
FRIEM develops high-current rectifier systems with particular attention to coordinated protection functions, controlled current reduction during shutdown scenarios, and system configurations intended to support continuous industrial operation.
In chlor-alkali applications, this includes:
- System configurations structured to ensure stable DC output across operating conditions
- Protection functions aligned with plant safety requirements
- Controlled current reduction strategies during fault or shutdown events
- Design configurations incorporating appropriate redundancy and operational margins.
Efficiency and decarbonization: the evolving role of power conversion systems
Chlor-alkali production is electricity-intensive, and energy consumption remains a defining operational parameter.
Improvements in rectifier efficiency and reduction of electrical losses directly lower specific energy consumption per tonne of product.
As chlor-alkali plants increasingly rely on electrified processes, indirect emissions become closely linked to electrical efficiency and grid carbon intensity. In this context, power conversion performance contributes not only to operational optimization, but also to the broader decarbonization pathway of electrochemical industries.
The same engineering principles applied in chlor-alkali electrolysis are increasingly relevant in green hydrogen production, where high-current power conversion systems support large-scale water electrolysis. Further information on FRIEM’s activities in hydrogen applications is available here: https://friem.com/en/our-business/hydrogen/
Reference
[1] The Chlorine Institute, Chlorine Overview and Manufacture.
https://www.chlorineinstitute.org/chlorine