ECN publication
Kristallisatie : een belangrijke processtap in de productie van een vaste-stof/damp reactor
Published by: Publication date:
ECN Energy Efficiency in Industry 1-12-2001
ECN report number: Document type:
ECN-I--01-019 Other
Number of pages: Full text:
44 Download PDF  

The physical form of the solid sorbent and the design of the sorption reactor are the key factors for the performance of solid sorption systems used for the production of heat or cold. Particle size, size distribution and shape of the solid sorbent must be such that an optimum in both heat and mass transfer is reached. This requires knowledge and skills on how to prepare solid sorption materials.Metal salts are applied as sorbents in the solid sorption systems that are being developed at ECN. These sorbents are generally prepared via crystallisation processes. The report describes the theoretical aspects of crystallisation processes, such as thermodynamics, nucleation and crystal growth, transport processes and crystal size distribution. Also the practical aspects of crystallisation processes and operations are treated. The consequences of both theoretical and practical aspects of crystallisation are interpreted for the relevant metal salts. This study clarifies that certain parameters of crystallisation processes must be well controlled to obtain the desired crystal size of the product. For the sorbent materials involved this means that batch crystallisation by means of cooling of an aqueous solution of the salt is the most ap-propriate way. In-situ crystallisation of the sorbent in the solid sorption reactor leads to limited control of the crystallisation process parameters, therefore ex-situ crystallisation is to be pre-ferred. Quantifying the critical parameters in the crystallisation process requires for each sorbent well-controlled laboratory experiments. Since the range of attainable crystal sizes by common crystallisation processes is limited, proc-esses for size or shape modifications of the crystallised product are sometimes necessary.

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