Relative to conventional air drying, superheated steam (SHS) provides a number of benefits such as increased efficiency, reduced risk of fire and explosion, sterilization, and/or deodorization and faster drying rates. Consequently, an increased interest in SHS drying is developing. Brewer’s Spent Grain (BSG) is the by-product from beer brewing. It is a sticky material which has a tendency to foul drying equipment. This paper evaluates the drying behaviour of BSG in a rotary SHS dryer developed by Keith Engineering. The evaluation is based on measurements of sticking, product moisture content, energy consumption, and the product water quality.

The results of an experimental design for three system parameters (steam temperature, steam velocity and feed rate) are presented for two processing levels. The critical parameters with the most significant effect on the sticky deposits are the feed rate and the inlet steam temperature. A wide range of moisture contents have been attained in the experiments, indicating that practically any desired moisture content can be achieved. An evaluation of the energy consumption showed that the consumption by the pilot-scale rig was higher than would be expected based on literature values. An analysis of the condensate showed the presence of organic constituents indicating that the water could be reused after treatment. Finally, two residence time models have been modified and correlated with the experimental data.

This study has demonstrated that BSG can be dried successfully with the proposed technology and that sticking can be minimized by careful selection of the process parameters.