MACO Pilot – Optimisation of online concentration monitoring and control in stainless steel mixed acid pickling plants / Projectdetails / BFI VDEh-Betriebsforschungsinstitut GmbH

Initial situation

Increasing economic pressure in the European steel sector calls for highly flexible and cost-effective production processes
The pickling process is of particular importance in stainless steel production
High process flexibility requires rapid adjustment of defined concentrations in industrial pickling baths to maintain consistently high product quality and plant productivity
The RFCS FLEXPROMUS project successfully developed an innovative measurement technology for the continuous online analysis of HF-HNO₃ acid mixtures
Initial prototype tests on stainless steel strip pickling lines showed very promising results

Project targets

Optimisation of online measurement technology for continuous concentration monitoring in HNO₃-HF pickling acid mixtures
Optimisation of concentration monitoring and control in stainless steel pickling plants
Test installations of online measurement technology prototypes on a stainless steel strip pickling line, a stainless steel wire pickling plant and a mixed acid regeneration plant
Optimisation of pickling process control in a mixed acid wire pickling plant using a pickling programme management model

Innovative process approaches

Continuous online concentration monitoring in HF-HNO₃ pickling acid mixtures based on a model-based measurement method
Development of a closed-loop concentration control model for stainless steel strip pickling lines based on online concentration data
Development of a pickling programme management model for stainless steel wire pickling lines
Concept development for the optimisation of existing European mixed acid pickling lines using innovative online concentration monitoring and control

Latest results (as of December 2019)

Optimised prototype setup for online measurement technology (upgrade from TRL5 to TRL7)
Successful installation and operation of the online measurement technology on a stainless steel strip pickling line, including a regeneration tank, and a stainless steel wire pickling line, in combination with sample flow pre-filtration technology
Concentration calculation models for various HNO₃-HF mixed acid applications; deviations between online measurement and BFI laboratory reference analysis predominantly
< ± 5 g/L for free HF + total metals and < ± 8 g/L for free HNO₃ concentrations under optimal measurement conditions
Advanced “closed-loop” and “open-loop” concentration control models based on high-density concentration data enable improved stabilisation of pickling bath process conditions, reduced acid consumption and emissions, as well as cost savings
A reduction in manual sampling for reference analyses enables improved working conditions and safety
An innovative pickling programme management model enables more optimal and safer operation of stainless steel wire pickling plants

Outlook

Further optimisation of concentration calculation models (software and hardware modifications)

Finalisation of the online measurement technology, from prototype version to commercially available system

Presentations from the international workshop on 13 November 2019