Classical and conventional wort boiling systems are reviewed and the evolution of modern systems is traced. Breweries have been slow to give up conventional wort boiling methods but the burden of increased energy costs has forced the industry to look for energy savings in a process which can account for up to 40% of conventional brewhouse energy consumption. In the late 1960's external wort boiling was adopted. New developments in hops charging and the availability of hop powder and extract made possible closed boiling and allowed narrow pipe construction on heat exchangers. It was proved that build up of counter pressure and elevated temperatures of 105 to 112 degrees resulted in better coagulation, isomeration and evaporation rate with reduced boiling time and without any compromise on quality. Further energy saving may be achieved by compromise on quality. Further energy saving may be achieved by compressing the exhaust vapour from wort boiling and feeding the recovered heat back to the heating system of the external heater. Saving on primary energy is high and this pressureless wort boilings system may be adopted without technological risks, but investment and operation costs are high. A typical installation of this type operates with 8% evaporation at 106 degrees and 1 h boiling time. The best results on energy saving are with continuous high temperature wort boiling (CHTW). Here continuity of product flow is a necessity, otherwise efficiency of heat recovery and quality of product suffer. Heat is recovered from the flash vapour of product operation and used to heat wort entering the system so that steam requirement is reduced from 21 to 7 kg per hl of wort. Wort is passed through 2 heat exchangers and its temperature raised sequentially from 70 degrees C to 90 degrees C to 112 degrees C. In the 3rd exchanger, a tubular type, wort temperature is brought to 140 degrees C using live steam at 6 bar and held for 150 to 180 sec. Wort is cooled and heat recovered in 2 flash vessels. A big advantage of the system is low energy load at constant steam consumption. The environmental load of the brewery is reduced as there is no surplus of hot water. A similar system with variable evaporation of 4% to 16% operates at a maximum temperature of 120 degrees C with a hold time of 11 min.
Keywords: brewing continuous process pressure survey wort boiling