Abstract
Cooling towers have a significant share in the consumption of electrical energy at chemical production sites and the optimal operation of these pieces of equipment has a large potential for energy savings. The properties of the cooling water that is provided by the cooling towers (temperature and pressure or flow rate) strongly influence the plants to which the cooling water is delivered. The cooling water supply usually has to fulfil certain requirements, e.g. a maximum temperature. In order to fulfil these requirements even under difficult conditions, like hot days in the summer, the cooling towers are overdesigned. If the operational regime is not properly adapted, the number of active towers or sections is higher than necessary which results in a too high consumption of electric power. To overcome this problem, an optimization and operator support system was developed in a collaboration of INEOS Köln and TU Dortmund, in the framework of the EU project MORE (“Real-time Monitoring and Optimization of Resource Efficiency in Integrated Processing Plants”). As a basis for the optimization, a cooling tower model that is based on lumped mass and energy balances was developed. The optimisation uses this model to compute a baseline which takes the ambient conditions and the specified cooling water quality into account. The current cooling tower performance is then rated versus the baseline and this reveals the potential for energy savings for the operators.
The first step of the decision support is the analysis of the trade-off between the cooling water temperature and the utilization of electric energy. The second step is the prediction of the cooling tower performance based upon an open online weather forecast. This enables the operators to act in anticipation and to foresee limitations in the cooling capacity. Consequently, the plants can shift production capacity to times where there is more available cooling power, e.g. to the night. The decision support system (DSS) will be set up as a web service at the production site of INEOS Köln and will be accessible to the operators and plant managers via standard web browsers, which provides a convenient and flexible utilisation.
