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ECN publication
Heat storage systems for use in an industrial batch process: (results of) a case study
Published by: Publication date:
ECN Energy Efficiency in Industry 1-7-2006
ECN report number: Document type:
ECN-RX--06-087 Conference Paper
Number of pages: Full text:
14 Download PDF  

Presented at: 10th International Conference on Thermal Energy Storage, ECOSTOCK, Stockton, NJ, USA, 31 mei 2006-2 juni 2006.

Thermal energy storage can be an attractive technology to enable re-use of waste-heat, especially for batch processes. A case study was carried out to evaluate the technical and economical feasibility of an industrial heat storage system. The study focused on integration of a heat storage system within an existing production facility of organic surfactants. Three different thermal storage systems with operating temperatures between 110°C to 160°C were designed to store the heat released during the exothermic reaction phase and re-use the heat for preheating of the reactants in the following batch. The first system uses a Phase Change Material (PCM) contained in metal balls with an assumed phase change temperature at 140°C. The second system uses a concrete volume as a sensible heat storage material and the third system is also based on concrete, but with a doubling of the storage capacity. A dynamic simulation was performed of a reference cycle of a batch reactor coupled with a thermal storage system to calculate energy savings for preheating of the reactants. It was required to oversize the storage capacity of the PCM system, in order to obtain a heat transfer rate that matches with the conditions of the actual process. The calculated energy savings for heating of the batch reactors is 50 to 70%, resulting in financial savings of 26 to 38 k€ on an annual basis. The total capital investment of the storage systems is estimated at 440 to 540 k€. Simple pay out time is higher than 10 years, with the best result for the concrete heat storage. The bare cost of the thermal buffer is 15% to 30% of the total capital investment. Because the cost of integration of the storage system in an existing facility are a large part of the total cost, it is recommended to evaluate the use of thermal storage systems for grass-roots situations.

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