Production managers of urea plants are under pressure to maximize profitability due to global competition, tightening legislation on ecosphere load, and fluctuation of oil/gas prices. The joint Stamicarbon-IPCOS Sirius@Max®optimization solutions for urea plants relieve these pressures and increase the plant efficiency.
Optimizing urea plants often means maximizing the production and/or minimizing the energy consumption.
A prerequisite for every urea plant to maximize production and minimize the energy consumption is obtaining a maximum yield in the reactor. Azeotropic controls in the reactor together with water management control are the key elements, which dictate this optimal reaction yield.
All urea stripping plants are characterized by a high degree of interaction among the process variables. Any change at the back-end will affect the synthesis and vice versa.
Mostly the Urea process is controlled by traditional single-input single-output PID-control strategies, in which plant oscillations in urea yield and production, are inevitable.
Further, the process is characterized by a significant process dead-time, which is a significant source of instability and oscillations:
- A disturbance entering the process will not be detected until after a significant period of time
- The control actions are taken on basis of the last measurements, not the actual process situation
- The control action will also take some time to show its effect in the process.
The Sirius@Max® provides a multivariable dynamic and layered approach to the process control. This Advanced Process Control (APC) application optimizes the operation of the urea plant minute by minute and every hour of the day. Resulting in improved reliability of the operation. Sirius@Max® reduces the variability in the key process parameters significantly, resulting in increased production rates of 1 to 4%, together with an increased energy efficiency of >0.5% in comparison with conventional operator driven operation control.
The layered approach of the Sirius@Max® allows you to achieve optimal operation of your urea plant, by simply pushing the plant closer towards the active constraints like:
- Condensation capacity in LP-section
- Condensation capacity in the synthesis section
- Available CO2 compression capacity
- Available CO2 production in ammonia plant
- Stripper flooding.
The Sirius@Max® solution is implemented using a phased methodology. The first phase focuses on the optimization of the base layer controls, whilst the second phase focuses on the implementation of the Advanced Process Control solution. Optimized base layer control provides more stable operation throughout the entire urea plant and helps reduce the impact of disturbances on the plant with minimal operator intervention.
