Advanced Process Control in fertiliser production

Advanced Process Control (APC) is a supervisory process control method based on the model predictive control algorithm. Yara International ASA, www.yara.com, has implemented APC in ammonia, nitric acid, urea and finished fertiliser plants since 2004 and currently has 20 applications in operation. 17 applications are using IPCOS, www.ipcos.com, software whereas three are using Honeywell, www.honeywell.com, technology.

This paper describes the approach, project phases and procedures we are using when implementing APC together with the external software technology supplier. Key APC signals, strategy and benefits in four different fertiliser processes, ammonia, nitric acid, urea solution and granulation plants, are described without disclosing confidential or sensitive information. The importance of a well-working regulatory control system including controller tunings and advanced regulatory control functions for e.g. input flow ratio control is emphasised. The main APC projects risks including organisational challenges, process control system changes and plant modifications are presented. Finally, current challenges and future trends including integration with real-time, non-linear optimisation and increased use of online analysers and soft-sensors are discussed.