Tag Archives: hop cones

806–815 A. Rybka, P. Heřmánek and I. Honzík
Effect of rotors on the parameters of hop drying in belt dryers
Abstract |

Effect of rotors on the parameters of hop drying in belt dryers

A. Rybka*, P. Heřmánek and I. Honzík

Czech University of Life Sciences Prague, Faculty of Engineering, Department of Agricultural Machines, Kamýcká 129, CZ165 00 Praha 6 – Suchdol, Czech Republic
*Correspondence: rybka@tf.czu.cz

Abstract:

This article contains a design and verification for a technical solution aimed at optimising the hop drying process in belt dryer and at increasing the quality of the final product. Above the first belt of our belt dryer two evenly distributed double-arm rotors were installed and tested in operation to improve the permeability of the drying air through a flattened hop layer, as well as to improve the speed of drying. The measurements carried out in operation and comparing the drying process with the rotors switched on and off concluded that by inclusion of rotors the hop layer becomes more permeable, and when switched on, the rotors have a positive effect on faster reduction of the relative humidity and on increase of the drying air temperature. With rotors switched on, the percentage drop in the drying air relative humidity at the third inspection window of the first belt, compared to the first inspection window, was 41% on average (values obtained from data loggers and fixed sensors), the drying air temperature increased by 29%, and the hop moisture content decreased by 12%. Whereas with rotors switched off, the drop in the drying air relative humidity was only by 26% on average, the drying air temperature increased only by 14%, and the hop moisture content decreased by 12%. Based on long-term monitoring of fuel consumption during the whole harvesting season starting 2011 until 2017 inclusive, the average annual consumption of LFO (2011–2014) results in 494 L t-1 operating without rotors, and 431 L t-1 when operating with rotors (2015–2017). This implies that due to the implementation of rotors, the fuel saving being 13% is significant.

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221-229 A. Rybka, P. Heřmánek and I. Honzík
Analysis of Hop Drying in Chamber Dryer
Abstract |
Full text PDF (749 KB)

Analysis of Hop Drying in Chamber Dryer

A. Rybka*, P. Heřmánek and I. Honzík

Czech University of Life Sciences Prague, Faculty of Engineering, Department of
Agricultural Machines, Kamýcká 129, CZ165 00 Praha 6 – Suchdol, Czech Republic
*Correspondence: rybka@tf.czu.cz

Abstract:

This article is aimed at the analysis of the hop drying process that has been carried out
in the chamber dryer of Rakochmel Co. Ltd. in Kolešovice with the Saaz hop variety. The values
measured by means of dataloggers as well as fixed sensors show an identical trend. When the
hops fall over from one slat box onto another, the drying air temperature declines and the relative
humidity rises. A sharp increase in the relative humidity gradually decreases starting with the first
slat box and finishing with the emptying conveyor, which points to a gradual levelling of the
relative humidity and hop moisture. The hop moisture content, determined from laboratory
samples, logically decreases depending on the measurement time. In comparison to belt dryers,
chamber dryers clearly ensure continuous and more gentle drying during which the hops are not
overdried and a moisture content of 10% is achieved practically only at the outlet of the dryer
prior to conditioning.

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