Rapid growth creates new requirements – this was also evident for the craft breewers of the Tröegs Brewing Company in Hershey, Pennsylvania, USA. They did not move into their new brewing facility until 2011, but after a short time it became clear that their successful beer variety and sought-after experimental brews required a larger and more flexible filtration system. The partner companies corosys Prozeßsysteme und Sensoren GmbH from Hofheim/Germany, and M&L Consulting GmbH, St. Gallen/Switzerland, were able to remedy this situation …
Im Jahre 1996 begannen die Brüder John und Chris Trogner damit, ihr erstes eigenes Bier zu brauen. Ihre Geschichte setzt sich bis heute als ein Paradebeispiel für Amerikas Craftbeer-Szene fort. Gegründet als Kleinbrauerei in Harrisburg, Pennsylvania, wuchs das Unternehmen stetig, sodass ab 2010 der Brauereineubau in Hershey realisiert wurde.
Mitten im Hersheypark, einem bekannten Vergnügungspark, entstand die neue Produktionsstätte auf mehr als 8000 m2. Das rasche Wachstum der Brauerei fußt unter anderem auf der großen Biervielfalt. Die experimentelle Bierschiene bei Tröegs findet sich unter dem Namen „Scratch Beer“, das neben den althergebrachten US-Sorten wie IPA, Stout oder Lager erfolgreich vertrieben wird. Natürlich ist eigens für die Scratch Beer-Produktion eine Kleinbrauerei im großen Neubau installiert worden. Mit dem Erfolg der Biere und dem steigenden Umsatz musste sich zwangsläufig auch die technische Seite der gerade erst gebauten Brauerei anpassen.
Modern filtration system for best quality
The Trogners quickly realized that the filtration system originally planned and installed had become too small and inflexible for the amount of types and output. In order to no longer risk quality losses or the physical-chemical stability of the beers, Tröegs decided to expand the existing filter with a completely new automatic filtration system from corosys and M&L Consulting. The old precoat layer filter had a capacity of 65 – 80 hl/h and was operated with the use of the filter aids cellulose and perlite. Both sides, customer and supplier, worked intensively on the planning of the new filter plant with the common goal of improving filter service life and quality characteristics.
The result is a state-of-the-art kieselguhr candle filter with a throughput of 65 – 108 hl/h (depending on the beer type). The filter’s ASME (American Society of Mechanical Engineers) certified boiler has 111 stainless steel candles, each measuring 32.5 x 1.850 mm. This results in a metallic surface of 20.6 m2. This in turn results in a maximum specific flow rate of 5.2 hl/m2*h. The maximum diatomaceous earth load of the filter is indicated as 204 kg (3.2 l/kg). Alternatively, a maximum of 145 kg (4.5 l/kg) of perlite can be precoated as filter aid. The manufacturer’s specifications range from 1360 hl (100 g/hl) to 2040 hl (150 g/hl) with the corresponding average diatomaceous earth dosage. Included are an automatic diatomaceous earth dosing system and Stabi dosing vessels including stirrer and pump technology.
A Fristam centrifugal pump is used for precoating, while peristaltic pumps from Bredel are used for dosing. A membrane filter vessel corresponding to the diatomaceous earth filter is used to ensure the filtration result. Its inner consist of eight pleated polypropylene membrane filter cartridges with 10 µm absolute pore size. To support the effective filtration, the existing centrifuge remained in front of the filter line, which was equipped with an automation for turbidity control. For user-friendly handling, the automatic dosage of additives, the pressure tanks for filtrate and the production steps of the filtration, such as start and stop, type change and cleaning, were completely automated. All in all, the filtration achieved a longer service life and the costs for kieselguhr consumption were reduced.
Related process technology
corosys supplied the necessary process technology for all aspects of filtration. In order to maintain the quality of a (filtered) beer, it is not sufficient to only deaerate the filter, but it is also recommended to avoid the subsequent entry of oxygen. Since Tröegs wanted a complete solution without compromises, the installation of a water deaeration system including oxygen measurement was absolutely necessary. The column deaeration operated under vacuum has proven to be an economical process and achieves low oxygen values with minimum CO2 consumption.
With the plant type VWD, 100 hl per hour water with guaranteed residual oxygen values of 10 ppb will be degassed in Hershey from now on. The deaerated water is used, among other things, for filter line pushouts during start and stop, type changes or (fine) blending. The filter system is followed by a fully automatic carbonation unit with alcohol trimming. With the plant type BCS all produced beers can be mixed with up to 35 hl/h water. The range of carbonation ranges from 3.0 – 6.5 g/l. At this point, Anton Paar’s measuring technology allows highly accurate control of the inline trimming and carbonation process by precisely measuring CO2 and original wort or alcohol. All systems, filters, degassing and blending equipment, as well as the pressure tank cellar control were automated and visualized by corosys.
The automation structure of the entire filter area includes one CPU, one motor control cabinet and a field cabinet for each area. The internal communication runs via ET200S with Profibus. A Siemens Microbox is used as CPU, which is operated by a 22″ touch panel. The scope of delivery of the automation also included the software with user licenses and their installation. Via an integrated VPN modem, service, process-technical support or an adjustment of the software can be carried out at any time. After the automation of the entire filter cellar, other brewery areas were gradually added and were also integrated by corosys into the existing filter and cellar control and software WinCC Step 7.
In order to complete the filter cellar, Tröegs has now also added a flash pasteurizer, a dosing system and a nitrogen dosing system. The nitrogen dosing system type CCNS was integrated into the existing carboblender. Here 0 – 40 mg/l nitrogen can be dosed into the beer by mass flow measurement and dissolved directly.
The corosys flash pasteurizer type FPS delivers a maximum of 175 hl/h and can cover a pasteurization range from 10 – 200 PU. Sugar solution and yeast suspension are dosed directly into the beer via the dosing system type ADS. The plant is divided into two dosing stations at the inlet and outlet of the flash pasteurizer. Sugar is pre-dosed, pasteurized in the flash pasteurizer and then mixed with yeast suspension. This enables targeted secondary fermentation in the bottle. The remaining oxygen after bottling is converted by the fermentation and the beer is all the more stable in taste. In terms of control technology, all new systems were integrated into the existing hardware and software. Tröegs is already planning the next expansion steps in order to keep pace with market developments and to be prepared for future trends and ideas in the world of craftbrewers.
Managing director corosys Prozßsysteme und Sensoren GmbH, Hofheim am Taunus
Project manager corosys Prozßsysteme und Sensoren GmbH, Hofheim am Taunus