Online determination of quality variables

Production plants in the process industry today rely on regular and extremely time-consuming laboratory analyses for quality control purposes (new measured values typically every 8 to 24 hours). Or they use very expensive and high-maintenance online analyzers (new values typically every 20 to 60 minutes). In order to raise productivity and run the process up to its full capacity while maintaining the required quality, it is necessary to measure product quality online with a refresh rate of between 0.5 and 3 minutes. This ensures that the controller responds at the right time and the product specifications are maintained.

The plant operator is usually responsible for complete or partial process control. Weak points in process control are also reflected by changes in product quality or in the utilization of production capacity. Since no quality values are known during a conversion, the production specifications do not correspond to the quality requirements over longer periods.

These problems can be solved by using soft sensors. Soft sensors are calculation procedures which determine non-measurable quality variables on the basis of measurable process values (pressures, flow rates, temperatures, levels, etc.) in cycles of between 0.5 and 3 minutes. The calculation is made on the basis of a (non-)linear parametric model generated from historic plant data or through dedicated tests. The high-speed soft sensor predictions can be consolidated by laboratory analyses or values from online analyzers.

The soft sensor predictions enable the frequency of laboratory analyses and the use of online analyzers to be reduced. They raise product quality while at the same time reducing operating costs.

INCA Sensor is a tool for designing, parameterizing and operating soft sensors. It makes it easier to master complex plant dynamics, and enables operating conditions to be optimized so that the quality of the end product is assured.

Note:

INCA Sensor can be used together with SIMATIC PCS 7 V7.1, V8.0, V8.1 and V8.2. In SIMATIC PCS 7 V8.2, INCA MPC or INCA Sensor can be integrated via the APC (Advanced Process Control) coupling module of the SIMATIC PCS 7 Industry Library as of V8.2 Update 1.