Energy efficiency through model based regulation and online optimization

The aim of this project has been to exploit the methods in model-based control and online optimization to increase energy efficiency in the industry. Model based regulation is a relatively new technology, which combines information on processes (online) and systems, theoretical methods and computing power to achieve an optimum operation.

Two areas are focused:

• Cooling water systems with optimization of the interaction between cooling tower/dry cooler, process needs and circulation rates of cooling water and air, also in combination with refrigeration compressors.
• Optimal load distribution in heating or combined heat and power plants with more units

The mass and heat transfer in a cooling tower is modeled calculating outlet temperature of water based on air temperature, relative humidity, inlet temperature of water, water flow and fan speed. Together with models of dry coolers and refrigeration compressors the models can minimize electricity consumption of complex cooling systems based on online information on surrounding air conditions and cooling demand.

The second area of focus has implemented a model based control system that can minimize the production cost of heat in an industrial combined heat and power plant (CHP) consisting of 3 steam boilers and one gas turbine, with optional partly flue gas bypass of steam boiler.