With its LiquiSonic measurement system, SensoTech addresses the need for continuous concentration monitoring in sulfuric acid production. The system measures sulfuric acid and oleum directly during the ongoing process and is designed for use in drying towers, absorption towers, condensers, dilution units, as well as in blending and delivery lines.
In sulfuric acid plants using the double-contact process (DCDA) or the contact process (WSA), the exact acid concentration affects the absorption efficiency, product yield, emissions, and corrosion load. Particularly with highly concentrated and aggressive media, delayed laboratory readings are often insufficient to reliably reflect dynamic process changes. Fluctuating gas qualities, changes in water addition, or temperature effects can alter the concentration within a short period of time.
Measurement Principle and Integration
LiquiSonic is based on measuring the speed of sound in the medium and additionally incorporates the process temperature into the analysis. Since the speed of sound in sulfuric acid is highly concentration-dependent, a clear measurement signal is generated in the range of 70 to 100 wt%. SensoTech emphasizes that the measured value can thus be clearly identified in the highly concentrated range. The achievable accuracy is up to ± 0.03 wt%.
The system measures inline in the pipeline or, alternatively, in a bypass. A LiquiSonic controller can be connected to up to four sensors, allowing multiple measurement points to be monitored in parallel. The measured values can be displayed and documented on-site and transmitted to the process control system via serial interfaces, fieldbus, or Ethernet. This allows concentration measurement to be integrated into existing processes for monitoring, alarms, dilution control, or release decisions.
Use in Corrosive Media
For operators of sulfuric acid plants, suitability for aggressive process media is crucial—in addition to measurement accuracy. The measurement system operates without consumables and is designed for maintenance-free operation. All parts in contact with the process medium are available in special materials such as Hastelloy or PFA. This supports use in highly concentrated sulfuric acid and oleum, as well as high plant availability.
Notable trends and critical deviations become apparent earlier than with laboratory analyses. This allows for a timely response to, for example, declining absorption performance, incorrect water addition, or an impending drop below the corrosion protection window. At the same time, the effort required for manual sampling from hot acid streams is reduced.
The solution is designed for operators of DCDA and WSA plants, sulfuric acid manufacturers and distributors, as well as fertilizer producers, mining, and smelting operations. Inline monitoring of acid concentration can also be relevant in plants with chlorine and synthesis gas drying systems, gas scrubbers, and etching and pickling baths.