CO₂ Absorbers for Stabilizing Water Quality in Steam Generation Systems

Introduction

In both municipal and industrial plants, the chemical stability of process media is a crucial factor for safe and economical operation.
A frequently underestimated source of disturbance is the ingress of carbon dioxide (CO₂) from the ambient air. Even small amounts can cause pH shifts in alkaline solutions, lead to carbonate formation, and introduce impurities into the water. This not only causes operational difficulties but can also negatively impact plant availability.

This is particularly critical in the treatment of boiler and feedwater for steam generators. High water quality standards are required here to ensure operational safety, regulatory compliance, and plant efficiency. Natural raw water or municipal supply water cannot meet these requirements without additional treatment.

Task

Stadtwerke Flensburg GmbH approached Kwerk GmbH with the requirement to implement a solution for stabilizing conductivity in deionized water tanks.
The key objective was not to improve water quality, but to prevent CO₂ ingress — and thus to avoid an increase in conductivity.
The chosen solution was pressure-loss-optimized CO₂ absorbers of type SDA400-CO₂, designed for an air flow rate of 50 m³/h.
These units are equipped with DN100 flange connections, allowing them to be easily retrofitted onto the deionized water tanks.

Process of CO₂ Removal

The CO₂ absorption granulate used reacts chemically with the CO₂ contained in the air.
In an exothermic reaction, the hydroxides in the granulate are converted into carbonates and water, permanently binding the CO₂.
The Kwerk absorbers are filled with medical-grade absorption granulate. This ensures complete removal of CO₂ from the incoming air so that the demineralized water in the tanks remains free from contamination.

A practical advantage: Towards the end of its service life, the granulate indicates exhaustion by a distinct color change from white to violet.
Since the absorbers are equipped with a transparent PVC-U outer tube, this color change is visible from the outside at any time.
Optionally, the absorbers can be equipped with sterile filter cartridges to reliably retain bacteria, spores, fungi, and other microorganisms.

Conclusion

The CO₂ absorbers installed by Kwerk provide a simple, safe, and economical method for preventing CO₂ ingress.
In this specific application, the conductivity increase caused by open storage of the make-up water was completely eliminated.

This resulted in a significant improvement in water chemistry, faster start-up processes, and a reduction in auxiliary steam consumption.
In addition, a positive effect on corrosion processes can be expected – further contributing to the efficiency and service life of the steam generation systems.

👉 This application example demonstrates how targeted CO₂ absorption can sustainably improve operational safety, cost efficiency, and water chemistry.