PRODUCTS & SERVICES  > Technology                                                                                       ENG GER

Advanced Process Control (APC)

Advanced Process Control (APC) has proven to be the most cost and time effective means to increase the profitability of the production. Analysts estimate that leading oil refiners gain 2 $/ton more from APC over average users, for a mid-sized plant an extra of ~10 million $/year! Other industries like Chemicals have lower product throughput but much higher margins and thus the potential gains are similar.

APC technologies are still underutilized because they are often considered as complex and difficult to use, requiring extra computer platforms plus hefty priced software. However, special approaches exist: ACT offers technologies that are extremely simple and easy to use, run all right in the DCS and can bring substantial benefits for the plant.

>> Click here for a brochure about our advanced control technologies.

Model Based Predictive Control (MBC)

MBC handles difficult process dynamics (long deadtime, high controllability ratio, inverse response etc.) with ease. It delivers highest performance which leads to higher product yield, quality or plant capacity, to lower emission or energy consumption.

MBC also can act smoother on the process, important for tightly integrated plants and sensitive equipment, often reducing the consumption of the resource. For temperature control e.g. typical savings from reduced use of the heating medium are ~ 1k€ / MW - is not difficult to achieve: Using our AMC controller (and the identification features of TOPAS), ACT has developed in one case a complete feedback + feedforward application in just one day!

AMC delivers top performance at a fraction of the cost and effort of complex approaches and has some more advantages:

·    Extremely simple, easy to learn, to use and to maintain, immediate operator acceptance

·    Robustness against model errors and process non-linearity

·    Separate tuning for load upsets and setpoint changes, much easier and faster than tuning a
     PID - see the brochure!

·    Easy extension to adaptive control.

Constraint control

This technique drives a target variable as far as possible in the desired direction, allows to approach limits closer than the operators, detects chances and threats much earlier and allows so deeper exploitation of equipment and resources. Examples are throughput maximization, maximization of product yield, tower pressure minimization etc. In the left picture below the throughput through a cooler is maximized subject to constraints in the cooling water temperature and the valve position.

This can be done right in the DCS, e.g. for distillation tower pressure minimization: The lower the pressure, the less energy is needed and this means less cost and also less pollution. 3–5 % savings are typical (~ 800 €/year and m3/h) – with two to three days of development effort!  

Optimization in real time

Just as MBC, optimization is considered by many as complex, difficult and impossible without heavy math. Yet, model-free optimization is none of this: It is a simple technique that probes the process to find the best operating point for to the given objective. Only a small algorithm is required that runs in the DCS. Applications aim at maximum product preheating (or cool-down) with parallel heat exchangers, efficiency maximization of furnaces, energy-yield optimization for distillation columns, etc.

A case worth mentioning is the total yield maximization for products that are produced by different units and processes. Such an application is delivering since over 20 years more than a million Euros per year. Every year! It is one of our smallest ever developed and the effort was just two weeks.

For all our technologies, the license fee is paid only once per DCS, but they can be used in that system over and over again, just like the PID!

All three techniques are also provided in our software package TOPAS. They can be tried out and learned. Furthermore, TOPAS helps to develop these applications in shortest time.

>> Click here for a brochure about our advanced control technologies.