Brewing - energy
Recovery of energy from vapour from wort boiling
To recover high-grade heat consider thermal or mechanical vapour recompression
- payback time on capital reduces as energy prices increase
Lowering evaporation rate reduces economic viability of these processes
Not viable to re-use heat in boiling system below an evaporation rate of 4.5%
- subject to change as energy prices increase
- may be other uses for the heat
Case Study: Optimising evaporation rate
The history of the brewing enterprise now known as Hofbrauhaus Wolters can be traced back to 1647, but in its present form it dates only from 2006, when it was refounded as an independent company following a management buyout from InBev Deutschland (which had acquired it in 2003). The recent refurbishment of its brewhouse is described. A GEA Brewery Systems "OTAS" process control system, covering all the brewhouse vessels and ancillary systems, has been installed. The wort copper has been retrofitted with a GEA "Jetstar" internal boiling heater, but also retains a heating jacket on its bottom, to enable it to boil smaller quantities of wort than the main heater can handle. This feature allows the brewery to produce speciality beers in styles for which demand is limited; these cannot be sold in the amounts required to make it economically viable to brew them in full sized batches, but can be quite profitable if produced efficiently in the low volumes for which a market is assured. Other items installed include a new wort vapour condenser, an insulated tank (to store the energy recovered by the condenser in the form of hot water) and a wort heater. This last is a heat exchanger that uses energy recovered from an earlier brew to preheat the wort of the current brew before boiling. In order to avoid generating more recoverable energy than can be used, the wort boiling process has been altered to reduce the evaporation rate (which before the refurbishment was about 10%). The optimum rate, from the viewpoint of energy efficiency, would be about 4.5%; by the time of writing, the average evaporation loss had been cut to about 5% without any detrimental effects on wort quality. The refurbishment cost about 400000 euros. At the time of installation, the reductions in both heat and electricity consumption achieved by the refurbishment were predicted to generate energy cost savings sufficient (at the prices then prevailing) to recover the whole sum invested within about 3 years.
Brauwelt, 8 July 2010, 150(27), 806-808
Research paper: Sustainable technology in the brewhouse
Examples of innovations in brewhouse equipment, all developed in Germany and designed to improve the energy efficiency of wort production, are described. They are (1) the Krones Steinecker "Shakesbeer" vibrating mash stirrer, (2) the Rolec "ESS" brewhouse vapour energy recovery system and (3) the Kaspar Schulz "SchoKo" wort boiling and unwanted volatile constituent evaporation system and its small scale variant for microbreweries, the "SchoKolino" (also called the "GentleBoil" and "GentleCraftBoil" respectively when exported to English speaking countries). The first and last of these have already been extensively described in the literature, but the "ESS" is a more recent innovation. It consists of a vapour condenser combined with a heat storage tank, the water in which is heated to 95 degrees C by the energy recovered from the vapour of each brew. When the next brew is lautered, the hot water is circulated through a heat exchanger built into the pipe that connects the lauter tun to the wort copper, thus preheating the wort from its lautering temperature of about 74 degrees C to just under 93 degrees C, so that bringing it to the boil requires only about a quarter of the energy input that would be needed to heat it directly from lautering temperature to boiling point. Wort preheating lowers the temperature of the heat storage water to about 74 degrees C, from which it is again heated to 95 degrees C when the vapour from the boiling of the preheated wort is condensed. Unlike conventional vapour energy recovery systems, in which some of the heated water is used as mashing and sparging liquor but the volume of water required to take up the recovered heat is usually significantly greater than the brewhouse's liquor consumption (so that a quantity of surplus water is generally wasted, together with its recovered energy content), the "ESS" uses all the recovered energy without any loss of water.
Dornbusch, H., New Brewer, July/Aug. 2009, 26(4), 40-45.