Yeast, the microorganism responsible for fermentation, also greatly influences a beer’s flavor and character. In the latter stages of beer production, brewers remove the spent yeast from fermented beer through the use of a yeast separator. The fermented beer is processed downstream and the spent yeast is processed for resale.
In addition to their battle to gain the favor of consumers, attaining operational efficiencies has always been essential for brewers. Beer and yeast separation and recovery is one aspect of the brewing process where using a yeast separator with a cyclone can realize greater efficiencies.
Separating Yeast From Beer
Separators have been essential equipment in beer brewing for decades. They ensure economical operation, a higher quality of beer, and efficient reclamation of beer and spent yeast. Over a period of time, however, a working separator starts to lose its efficiency due to yeast packing, and the bowl of the separator must be discharged of packed yeast. The bowl discharge of the separator is called a “shoot.” The objective of controlling the shoots is to clean the separator bowl of caked yeast and also minimize the amount of beer that is lost when the separator bowl is open.
When the separator bowl shoots, it discharges the beer and yeast mixture into the top of the cyclone, tangentially to the sidewall. The yeast/beer slurry decelerates and collects in the bottom of the cyclone. The spent yeast is then pumped out of the bottom of the cyclone by means of a positive displacement or peristaltic pump and enters a yeast decanter or thermalizer. Any beer that is discharged with the shoot is lost.
The cyclone also acts as a surge vessel between the separator bowl and the spent yeast storage, located below the pump. When the bowl shoots, additional beer will be discharged with the yeast into the cyclone.
Level Measurement for Yeast Separators
One Magnetrol® customer, a major U.S. brewer, had controlled the level in 64 cyclones throughout its breweries by using a competitor’s point level capacitance probe. The probe measured high level only and indicated when the cyclone was full of yeast/beer slurry. The brewer wanted to use a more precise measurement technique to capture more information about the cyclone.
MAGNETROL worked with one of the company’s breweries to prove that continuous level measurements could be made in a cyclone using guided wave radar (GWR) technology.
With the MAGNETROL Eclipse® GWR transmitter, the probe rod can be bent, enabling the brewer to measure down the sidewall, down the cone at the bottom of the cyclone, and into the discharge piping below the cyclone. By measuring level down to the outlet, the brewer can determine when there is slurry in the bottom of the cyclone and initiating pumping into the spent yeast cyclone. When the level is low, the pump will be stopped. This operation controls the discharge of the cyclone during separator shoots.
During normal separation of yeast (clarification of the beer), the separator bowl remains closed – not discharging slurry into the cyclone. However, the bowl of a separator is sealed by an elastomeric gasket. That gasket is prone to leakage, allowing good beer to be discharged at a low rate into the cyclone.
Using a guided wave radar transmitter, this brewer now monitors the cyclone level between shoots of the separator. If the separator bowl seal is leaking, the level in the cyclone will slowly increase. Therefore, by monitoring the level between shoots, the “health” of the separator bowl seal is monitored. If a leak is identified, the yeast separator is scheduled to have the bowl seal replaced.
Magnetrol now has 64 ECLIPSE transmitters installed to provide continuous cyclone measurement throughout the company’s breweries.
If this brewer can save one tenth of one percent of the beer by utilizing GWR, this translates into saving tens of thousands of gallons of beer per year! To learn more about guided wave radar and its other applications, visit radar.magnetrol.com.