Hygienic processes
Needless to say, beer isn’t a modern-day invention. In Ancient Egypt, beer was already being brewed. Simple means were employed back then, while today beer of the highest quality is brewed, using modern hygienic processes. Various machines and materials are required to produce beer, not only knowledge of the art of brewing. In Germany, beer is produced according to the Reinheitsgebot (German purity law), the oldest food law. As such, the main focus for valves is onhygiene.
Valves are used in numerous positions of the brewing process – from the brewhouse to the fermenting cellar to filling. In numerous process steps beer is won from water, barley, hops and yeast. “The soluble, filtered extract gained from the malt when mashing is heated,” explains the valve manufacturer Gemü. This hot wort is then cooled down. Fermentation is the next important step. “For this purpose, yeast and sterile air / oxygen is added to the cooled wort. The oxygen serves to activate the yeast cells. This green beer is piped into the fermentation tanks. The yeast attenuates the extract / sugar in alcohol and carbon dioxide, releasing heat”. Furthermore, the typical beer flavour is created in this main fermentation phase.
Regulating excess CO2
It takes around seven days until the extract content is nearly broken down. The green beer is pumped into storage tanks to mature and continue fermenting for three weeks, at a temperature of 0-1°C. “The yeast deposited in the fermentation tanks is then withdrawn from the coneat the bottom of the container, washed and can beused for a new fermentation process in part,” explains Gemü.
A complex stainless-steel pipeline system is used to feed the wort into the fermentation tank, withdraw the yeast after fermentation, and move the green beer to the maturing tanks. In order to adhere to the operating parameters, various process variables need to be regulated. In particular, the pressure in the fermentation tank which comes into being because of carbon dioxide build-up must be kept. The saturation of the green beer with CO2 and hence the later beer quality is critically dependent on the pressure,” reports Gemü. However, if the pressure is too high, fermentation is slowed down. A controlled discharge of excess CO2 is therefore necessary. It can also be fed into a CO2 extraction plant, making it available for other processes.
Butterfly and diaphragm valves
“The feeding of the wort to the fermentation tank, shifting the green beer and emptying it from the storage tank later can be carried out using commercially available stainless steel butterfly valves,” emphasises Gemü. The company mounts switchboxes directly on the valve actuators, for actuation and monitoring. Next to the pneumatic pilot valves used to control the butterfly valves, they also allow electrical position feedback to a control room.
Pressure in the fermentation tank is regulated using positioners and process controllers. These controllers are also placed directly on the actuators of the butterfly valves. “They are allocated the specification of set values ‘W’ from the system control unit’s PLC”. Diaphragm valves with electrical position indicators can be used in smaller systems for feeding yeast and ventilating wort.
Higher-quality stainless steel and PEEK
Producers of beer manufacturing equipment thus require numerous valves for demanding tasks. “Weuse high-alloyed steels and process optimisations to fulfil the requirements,” states Dietmar Pallasch, head of German sales, Mankenberg. This includes new materials like PEEK (Polyetheretherketone), higher quality stainless steel and polishing of valves.
Valves made by Mankenberg are mainly used in secondary cycles, for pressure reduction of water, steam and various gases. Furthermore, swimmer valves are used. Vent valves are used inwater treatment plants. Around 30 percent of Mankenberg’s standard valves initially fulfil the requirements of the beverage industry for secondary cycles.