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Conférence Internationale LOREXP-2021 : « Chaines de Valeurs et Transformations

Conférence Internationale LOREXP-2021 : « Chaines de Valeurs et Transformations Intégrales des Ressources Locales », Ngaoundéré, Cameroun, 20 au 23 Avril 2021. LOREXP-2021 International Conference: “Value Chains and Integral Transformation of Local Resources”, April 20 to 23, 2021, Ngaoundere, Cameroon. The wort boiling techniques and energy requirements: A Review Les techniques d'ébullition du moût et les besoins énergétiques : État des lieux Desobgo Z. S. C.1,* 1 Department of Food Processing and Quality Control of University Institute of Technology (UIT) of The University of Ngaoundéré, P.O. Box 455 UIT, Cameroon. * Corresponding author: desobgo.zangue@gmail.com ; +237 697 160 004 ABSTRACT: For several decades, the developers of equipment and technologies intended for wort boiling have declared for commercial and technical reasons any kind of performance of their systems in order to interest the breweries. For most of them, there was not enough information in literature to verify their claim. Thus, the aim of this paper was to conduct a review of some of these technologies and estimate the specific energy requirements during wort boiling. The comparison between theoretical calculation results obtained and some manufacturer data for their wort boiling equipment has revealed a slight difference. Thus, at the end of this work, and under equal conditions (without taking into account the recovery of energy), Ecostripper Meura system could be considered to be the most economical in terms of energy requirements and considering only usual boiling equipment. More generally, the theory of the abolition of wort boiling could be considered to be the most economical and with some adjustments should be taken into account by manufacturers and brewers. Keywords: Wort, Boiling, Stripping, Energy requirements, Calculation, Equipment RÉSUMÉ : Depuis plusieurs décennies, les développeurs d'équipements et de technologies destinés à l'ébullition du moût ont déclaré pour des raisons commerciales et techniques tout type de performance de leurs systèmes afin d'intéresser les brasseries. Pour la plupart d'entre eux, il n'y avait pas suffisamment d'informations dans la littérature pour vérifier leur affirmation. Ainsi, le but de cet article était de mener une revue de certaines de ces technologies et d'estimer les besoins énergétiques spécifiques pendant l'ébullition du moût. La comparaison entre les résultats de calculs théoriques obtenus et certaines données des fabricants pour leur équipement d'ébullition du moût a révélé une légère différence. Ainsi, à l'issue de ces travaux, et à conditions égales (sans tenir compte de la récupération d'énergie), le système Ecostripper Meura pourrait être considéré comme le plus économique en termes de besoins énergétiques et en ne considérant que les équipements d'ébullition usuels. Plus généralement, la théorie de l'abolition de l'ébullition du moût pourrait être considérée comme la plus économique et avec quelques ajustements devrait être prise en compte par les fabricants et les brasseurs. Mots clés : Moût, Ébullition, Volatilisation, Besoins énergétiques, Calcul, Équipement The 1st International Conference on Local Resource Exploitation www.lorexp.org / info@lorexp.org REF: LOREXP_2021_A1070 Pages: 1218-1238 Conférence Internationale LOREXP-2021 : « Chaines de Valeurs et Transformations Intégrales des Ressources Locales », Ngaoundéré, Cameroun, 20 au 23 Avril 2021. LOREXP-2021 International Conference: “Value Chains and Integral Transformation of Local Resources”, April 20 to 23, 2021, Ngaoundere, Cameroon. 1. INTRODUCTION Literature indicates that breweries are energy intensive industries and, during brewing, wort boiling consumes 33.7 % of the total energy consumption in brewery by itself (Scheller et al., 2008). In a general process of making efforts to reduce energy costs for brewing to be competitive in strict accordance with the environment, developers have thus proposed various equipment which they claim have better performance in terms of energy consumption reduction and increase the quality of the wort. Thus, different techniques of boiling wort have appeared on the market with different approaches. The purpose of these wort boiling techniques was also to fix the physicochemical profile of the wort to the desire of the brewer (Narziss, 1978; Hough, Briggs, Stevens, & Young, 1982; Miedaner, 1986; Willaert et al., 2001a; Wilkinson, 2003; Kunze et al., 2014). The equipment used for wort boiling was classified according to the heating techniques used. These heating techniques were classified into two classes. The first class is “usual boiling systems” and takes into consideration the equipment and techniques developed by the manufacturers like vacuum boiling, atmospheric pressure boiling, low pressure boiling, high temperature wort boiling, as well as combinations (Miedaner, 1986; Miedaner et al., 1986; Narziss, 1986; Narziss et al., 1992; Herrmann, 1998; Willaert et al., 2001b; Schwill-Miedaner et al., 2002; Bühler, Michel, Kantelberg, Baumgärtner, et al., 2003; Willaert et al., 2005) etc… The second class is “unusual boiling systems” and takes into consideration trials which were not developed on industrial scale like gas sparging and wort boiling abolition techniques (Mitani et al., 1999) and wort boiling abolition techniques (Maule et al., 1985). But more information which would permit better understanding of manufacturer’s contributions to technical knowledge are missing. Thus, the aim of this paper is to review some of these apparatus by providing a brief description of the boiling systems and a theoretical estimation of the energy consumed during the use of each of the boiling systems for comparison purposes i.e. comparing the boiling systems with the classical method. 2. WORT BOILING TECHNIQUES This part of the paper as stated in the introduction is concerned with a brief description of the boiling system and its theoretical energy estimations. It is classified as non-conventional and conventional systems. 2.1. Non-conventional system 2.1.1. Boiling with inert gas sparging Inert gas sparging trials (Picture 1) used in wort boiling process was introduced by Mitani et al. in 1999. In that technique, the wort was boiled for 80 min using an internal heater and with the nitrogen gas jet portion mounted just beside it. Inert gas sparging (N2) at 41 L/min started 30 min after the boiling point is reached. This gas sparging allowed to gain 25 min (Mitani et al., 1999) of the remaining boiling time (50 min) to obtain the same wort quality than boiling without sparging. Knowing that the wort boiling conditions were 150 MJ/m3/h and 80 min (Mitani et al., 1999), the specific energy requirement without sparging is estimated at 31.8 MJ/hL. When using inert gas sparging, that specific energy requirement is estimated at 25.5 MJ/hL. Hence the energy reduction is estimated then at 6.3 MJ/hL as obtained by Mitani et al., in Conférence Internationale LOREXP-2021 : « Chaines de Valeurs et Transformations Intégrales des Ressources Locales », Ngaoundéré, Cameroun, 20 au 23 Avril 2021. LOREXP-2021 International Conference: “Value Chains and Integral Transformation of Local Resources”, April 20 to 23, 2021, Ngaoundere, Cameroon. 1999. So, the sparging technique could permit an energy savings of 34.3 % (Table 1) compared to the classical boiling. Picture 1: Gas sparging and boiling kettle (Mitani et al., 1999) Table 1: Estimated heat requirements for non-conventional boiling system compared to classical wort boiling non-conventional boiling system Classical wort boiling Gas Sparging Wort boiling abolition Kettle full amount (hL) 100.0 100.0 100.0 Estimated mass (kg) 10000.0 10000.0 10000.0 Temperature before heating (°C) 72.0 72.0 72.0 Temperature before boiling (°C) 100.0 93.0 100.0 ∆T (°C) 28.0 21.0 28.0 Heat capacity Cp (kJ/kg) 4.2 4.2 4.2 Calculated energy requirement heating up Q1 (MJ) 1176.0 882.0 1176.0 Evaporation related to kettle full (%) 150 MJ/m3/h with 55 min boiling Mitani et al., 1999 6.0 12.0 Amount of total evaporation (kg) No wort boiling Maule and Clark, 1985 1200.0 Boiling temperature (°C) 100.0 Enthalpie related to the boiling temperature (kJ/kg) 2256.4 Calculated energy requirement for boiling Q2 (MJ) 1375.0 0.0 2707.7 Total calculated energy requirement Q (MJ) 2551.0 882.0 3883.7 Specific requirement Qs (MJ/hL) 25.5 8.8 38.8 Energy savings compared to conventional boiling 34.3 77.3 / Conférence Internationale LOREXP-2021 : « Chaines de Valeurs et Transformations Intégrales des Ressources Locales », Ngaoundéré, Cameroun, 20 au 23 Avril 2021. LOREXP-2021 International Conference: “Value Chains and Integral Transformation of Local Resources”, April 20 to 23, 2021, Ngaoundere, Cameroon. 2.1.2. Abolition of wort boiling Trials using boiling techniques that abolish wort boiling were introduced by Maule and Clark in 1985. In this technique, the wort was heated up to 93 °C. The heat of wort was used when doing recirculation through spray balls. This allowed to achieve 6 % evaporation and cool wort to 63 °C (Maule et al., 1985). With that technique, the energy spent should be for the heating up. The specific energy requirement in that case is estimated at 8.8 MJ/hL which could allow 77.3 % energy savings (Table 1). 2.2. Conventional boiling system 2.2.1. Vacuum boiling system Schoko: Schoko is a hybrid boiling system (Picture 2) using an atmospheric stripping combined with vacuum external boiler as flash evaporator for vacuum. It was introduced by the company Kaspar Schulz (www.kaspar-schulz.de) localized at Bamberg, Germany (Binkert et al., 2001). After the wort sparging, heating and resting for 1 h at 97.5 °C in the whirlpool, which period generates about 1 % of evaporation, the wort is pumped to the flash evaporator which steam pressure is at 300 mbar (69 °C) for stripping to achieve a total evaporation up to 8 uploads/Geographie/ the-wort-boiling-techniques-and-energy-requirements-a-review.pdf