Abstract
For the implementation of existing optimisation potentials in industry, commerce and district heating, it is important to expedite the reduction of waste energy and consequently of the primary energy demand as well as CO2 emissions and additionally to integrate renewable energy technologies. To reach these goals, complex optimisation principles are needed, due to the fact that heat and cold demand and availability vary in time and need to be aligned. Furthermore, continuous as well as batch processes which can be found in all industry sectors have to be considered. For this reason heat and cold storages are indispensable and necessary for increasing the resource and energy efficiencies in complex energy systems.
It has been proven that the pinch analysis is a very suitable method for the design of an optimised overall energy system (Muster-Slawitsch et al., 2011a; Varbanov and Klemes, 2010; Brunner et al., 2008). This methodology has been already implemented in several tools used for continuous processes without storages (Klemes et al., 2010). For minimising the external energy demand of non-continuous processes some approaches for ideal scheduling including heat integration have been formulated. Several authors worked with algorithms including batch processes and storages in the pinch analysis which are able to deal with single storages and optimise them (Krummenacher and Farvat, 2001; Nemet and Klemes, 2011; Atkins et al., 2010; Majozi, 2009; Chen and Ciou, 2008). But until now no software tools for the purpose of designing complex storage systems under practical considerations are available.
To close this gap, a new planning tool SOCO (Storage Optimisation Concepts) is being developed that is able to plan and design complex storage systems on the basis of real life process data coming from the industries, commerce and district heating businesses. The application will enhance possibilities of demand reduction (heat integration), increases the measures on energy efficiency and boosts the implementation of economically and technically reasonable renewable energy technologies, with a special attention on solar process heat. Included in SOCO is a pinch analysis on the basis of real life data with varying heat load profiles and the possibility to create heat exchanger networks. Based on the illustration of the residual load profile with its different temperature levels the best possible way of integrating renewable energy technology (solar process heat) can be shown. Furthermore, one of its main topics is the design of storage systems with regards on the heat exchanger network, previously calculated within the pinch analysis, and with regards on the possibility to implement renewable energies. SOCO optimises the amount, style, dimension and design of these storage systems as type of storage, insulation, connections, charging and discharging of the storages. This way, a holistic optimisation concept for storage systems and heat exchangers and their energy saving potential are displayed. The main fields of application are industries where several complex heat and cold streams occur, like producing industry, commerce and district heating businesses. SOCO is being developed based on measurements and monitoring data of 10 storages and the connected processes in industrial plants and district heating networks with which the present state has been modelled and analysed. Three of these storages will be the basis for detailed analysis of processes where holistic energy concepts have been developed: In an Austrian brewery the existing interconnections of processes (continuous and batch) with heat and cold demand at varying temperature levels and operating times in a water storage as well as an energy storage have been modelled and evaluated. The results show that the processes have been generally well integrated. On the one hand hot water from the wort cooler supplied the water demand of the brew house, the heating net and the fresh water over a water storage tank. On the other hand the lautering process and the vapour condenser of the wort copper (Pfaduko) are connected in an energy storage. But the integration of the storages could have been optimised. Based on the data of the three case studies the SOCO tool will be tested, evaluated and improved. The paper will present the structure of the algorithm and results of the optimisation within the case studies. By this way, the potential of the SOCO tool for reducing the primary energy demand by an optimised storage concept can be shown.
