Case studies

Lenzing AG

Model Predictive Control (MPC) fiber-drying process - Lenzing AG

In order to maximize the product quality of the viscose fibers at minimum energy consumption VOIGT+WIPP Engineers implemented a model predictive control systems at several production lines of the Lenzing AG. Since the Lenzing AG emphasizes high energy efficiencies of its processes and qualities of its fibers, production processes are permanently assessed and analyzed. Based on the results of these analysis, optimization scenarios are developed.

The optimization of fiber-drying process in the matter of control engineering aimed at the implementation of a multi-variable model predictive control system, minimizing the deviation in fiber-moistness at a simultaneous reduction of the specific drying-energy consumption by a predictive control of the drying power.

Services delivered:

  • Development of a control-strategy ensuring ideal behavior of the drying-process.
  • Design and programming of an advanced process control solution.
  • Connection of the engineering station and several automation stations via OPC.
  • Implementation of a multi-variable model predictive control system at several production lines minimizing the deviation in fiber-moistness at reduced specific drying energy


  • Reduction of specific energy consumption by optimized temperature profiles and deliberated process settings.
  • Increase of production yield.

  • Maximization of fiber production during unsteady state operations like start-up situations, change of fiber grade or changes in the production setting.
  • Process upgrade to fully automatic operation.
  • ROI within 2 years.

Lenzing AG

Exhaust Air Treatment - Lenzing AG

In order to separate hydrogen sulphide- and carbon disulphide components from the exhaust air produced during the production of viscose fibers, an exhaust air purification plant consisting of adsorption- and recovery facilities as well as several fans was established at the production site of the Lenzing AG at Lenzing.

The Project aimed at the development of a dynamic simulation of the entire exhaust air purification plant to conduct extensive software testing of a new control system and to facilitate a change to this control system at standard operation. Furthermore it is used as an Operator Training Station OTS, helping operators to get familiar with handling the plant and preparing them for any planned and unplanned operation conditions. Through the development of this dynamic simulator an increase in quality of both, the control system software as well as the handling of the plant by the operators was achieved.

Services delivered:

  • First-principle modeling of all parts of the plant and a validation of the simulation results with historical data.
  • Programming of a comprehensive, validated, dynamic Simulation using the simulation software MiMiC©


  • Pre-testing of the new process control system and change to this system at standard operation.
  • Use as a Simulator for operator trainings, helping the operators to get familiar with the handling of the plant.
  • The Simulator is still used for education-purposes

Lenzing AG

Model Predictive Control (MPC) viscose production - Lenzing AG

In order to exploit the maximum capacity of the viscose storage tanks, a Model-Predictive-Control system controlled by the fiber production plan of the spinning machines was implemented. The level inside the storage tanks, which ensure an adequate supply of the spinning machine, is due to the viscose in- and outflow. This level should be held on a constantly high value, by adjusting the viscose inflow, which is the control variable. The viscose outflow is determined by the production plan, and hence can't be manipulated.

Since a common feedback control couldn't solve the task of holding the tank level constantly high, a Model-Predictive-Control system was engineered and installed.

Services delivered

  • Development of a control strategy, considering a default viscose-production plan and definition of expected and unexpected production changes.

  • Implementation of a MPC system, consider the production plan and the actual production.
  • Design and Creation of a control concept.
  • Commissioning and parameter tuning.


  • Control of the level inside the viscose-storage tank.
  • Predictive, automatic adjustment of the viscose production considering the production forecast.
  • Exploitation of the available tank volumes to achieve maximum viscose production.

Combustion control of a biomass plant of BioMa Energie AG

Project goals:

Setup of a new combustion control on a B&R 2005 system control using an Intouch visualization.

Delivered services:

  • Development of the control concept
  • Programming of the combustion control in B&R Automation Studio
  • Commissioning
  • Visualization 
  • Optimization of the parameters


  • Customized combustion control setup to maximize the yield of fuel
  • Automatic minimization of the fume gas losses by using an emission driven O2-control.
  • Reduction of the fluctuations of the combustion chamber's temperature

BioEnergie Kufstein

Optimization of the combustion control of the biomass power plant of BioEnergie Kufstein, Austria

Project goals:

Optimization of the existing combustion control for reducing the emissions while cutting the fluctuations of the live steam quantity, the combustion chamber's temperature and the concentration of O2 in the fume gases.

  • Optimization of the combustion for minimizing emissions (CO and NOx)
  • Increase of the combustion's degree of efficiency

Plant's data:

  • Thermal power: 28,4 MW
  • Pel of the turbine: 6,925MW
  • Live steam pressure: 64bar
  • Live steam temperature: 450°C
  • Live steam quantity: 30 t/h

Delivered services:

  • On-site analyse of the parameters
  • Development of a a new control concept for secondary air injection
  • Planning and development of an optimized combustion control


  • Integration of an automated combustion control
  • Improved combustion on the grate

Mondi Group

Optimization of the power generation at the paper mill Mondi Frantschach GmbH

The project's goals were the optimization of a fluidized bed plant (bark boiler) for mimimizing the need of external energy and increasing the plant's degree of efficiency.

Obtained results:

  • Savings in external power by a conventional control modification > 2 GWh/a
  • Total power savings on site: 7,5GWh
  • Increased steam generation of 3,5%
  • Reduction of  flue gas losses of the bark boiler > 10%
  • Increase of power generation of 3,5%
  • Reduction of fluctuations of the boiler by 20%
  • > EUR 800.000 savings by reduced external power acquisition
  • ROI < 3 months

Flash Dryer - Mondi Frantschach GmbH

Project goals:

  • Enhancement of product quality of cellulose fibers, dried in a double-stage flash dryer with exhaust-air recirculation.
  • Minimization of the specific gas consumption during the drying process by controlling the amount of air used during the process, the recirculation rate of exhaust-air and the temperature distribution inside the drying stages.

Services delivered:

  • Implementation of a soft-sensor to determine the moisture content of the dried fibers, which can’t be physically measured online.
  • Installation of a multi-variable Model-Predictive-Control system, controlling the drying-process and energy efficiency.


  • Reduction of gas consumption by 7%.
  • Reduction of moisture-fluctuation by 30%.
  • Fully automated optimization of the drying-control system.

Wien Energie

Optimization of the combustion control of a fluidized bed waste boiler of the district heating company, Vienna

The project's goals were an increase of waste throughput and the reduction of steam generation fluctuations by implementing a model based combustion control.


  • Increase of the average waste throughput by 3,5%
  • Reduction of fuel oil consumption for auxiliary firing by 30%
  • Reduction of fluctuations of the steam quantity by 40%
  • Reduction of steam pressure fluctuations by 50%
  • Reduction of flue gas losses by 5%
  • Reduced emission of CO (and CO-peaks) by 25%
  • Reduction of fluctuations of the temperature of the combustion chamber by 30%
  • Project duration: 10 months

Wien Energie

Parental control system for the steam network of a toxic waste incineration plant, Fernwärme Wien (district heating of Vienna) 

The project's goal were an increase of power generation and the minimization of the dependence on external energy. 


  • Realized steam pressure stability: +/- 1%
  • Increase of the steam's degree of efficiency by 5%
  • ROI < 18 months

Control of a peak load boiler of a biomass district heating plant at EnergieComfort Tannheim GmbH

Project's goals:

Minimization of the fuel oil consumption by performing a system integration of a B&R APROL process control system into the existing control set. We developed a solution fully satisfying the customer using X20 controllers and a Profibus-DP connection.

Plant data:

  • Performance of the bi9omass boiler: 2,5 MW thermal
  • Performance of the fuel oil boiler: 3 MW thermal


  • Savings of fuel oil of > 15% on all days with comparable external temperature.
  • Very short project duration of < 14 days on site.
  • ROI < 6 months

Development and integration of a model-predictive, smart combustion control of a 100MW biomass power plant at wodego GmbH, Neumarkt, Germany

Project tasks:

  • Development and integration of a model predictive combustion control for maximum performance and operating reliability
  • Connection of a advanced process control-PC running IPCOS model predictive control to an existing Siemens S5 system control via an INAT OPC server. 

Delivered services:

  • Development and integration of the model based combustion control
  • Planning and engineering of a fuel input measurement system
  • Commissioning and optimization of the combustion control
  • Implementation of several parental limiting controls


  • CO-emissions cut by 50%
  • Homogenization of the steam production by 30%
  • Reduction of the fluctuations of the combustion chamber's temperature by 30%
  • ROI < 12 months


Process and control engineering services for projects on power plants

INP Germany & INP Austria


  • Optimization of the plant's efficiency by developing and integrating a parental fuzzy logic control for a waste disposal system composed of 6 steam boiler and 2 steam turbines
  • Combustion control for a roller grate plant (public services of Prague)
  • Smart control for a fluidized bed combustion system fueled by sludge of heterogeneous fuel value

Delivered services:

  • Development of control concepts
  • Development and commissioning of fuzzy logic controllers
  • Parental control for boiler and turbine plants
  • Programming of flow charts for S7-software
  • Commissioning of combustion controls
  • Performance optimization of system controls


  • Successful and fast commissioning
  • Increased both performance and operational reliability