Energy-efficient drying

Drying is an essential operation in the processing industry and is a very energy-intensive process. Recovery of waste heat from drying processes would greatly enhance the energy efficiency of these processes and would lower the operating costs. 

The EELS (Energy Efficient drying using Liquid Sorption) project aims to develop a liquid sorption system that is able to capture waste heat of convective (spray) drying processes and reuse this within the production facility. The project is coordinated by ECN and carried out in a consortium consisting of end-users FrieslandCampina and Unilever, system supplier Bronswerk Heat Transfer, and materials supplier DOW.

Currently, the exhaust air of industrial spray dryers contains significant amounts of heat in the form of humid hot air, which is lost through the chimney. This heat could be recovered by condensation of the water vapor. However, in practice condensation is often not possible due to risks of fouling and product quality related issues. 

In the EELS project, a system will be developed that overcomes this problem. A liquid sorbent is used that absorbs the moisture from the air. This absorption generates heat that is used to heat up the air. This results in hot dry air that can be reused in the spray dryer. Liquid sorbents will be screened and selected based on user demands and tested on performance. An absorber system is developed and tested to verify its intended function and performance. In addition to the technical performance, the economic prospects will as well be evaluated. 

The EELS project started recently and will run for 2 years. The project is partially subsidized by the industrial energy savings program of the Topsector Energy. The Netherlands Enterprise Agency ( is executing this program for the Institute for Sustainable Process Technology (TKI-ISPT).

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