Today, given that customers are more and more demanding, producing a Pilsner beer requires as close to 100% consistency as possible in the appearance, odour, colour and taste of all batches. To achieve this, process parameters and the quality and characteristics of the raw materials must remain constant.
Gone are the days when laboratory controls and the opinion and advice of a panel of tasters were sufficient controls. Modern breweries ensure constant quality levels, by means of frequent laboratory testing, automated computer-driven brewing systems, in-line instrumentation and panels of trained tasters.
One Belgium brewery, Interbrew Jupille, permanently evaluates and verifies its entire process and its brewing engineers have the ability to intervene in the production process on an ongoing basis, as well as improve the quality management of the process.
Honing in on the filtration process, which includes filtering, CO2 saturation and, importantly, the addition of ingredients that improve the quality, illustrates this point. During this stage, Interbrew injects an isomerised hop extract into its beer. This requires a highly accurate dosing of quantities of less than 2 kg/h.
A frequency-driven volumetric pump adds the dosage. However, no pump is used to measure the correct dosage. Instead, the brewery decided on a second control of the output and an adjustment of the frequency drive, depending on the measured output. In this way, Interbrew achieves a closed-loop control circuit with a permanent precision-control and post-control function, which helps guarantee that the end product will always conform to the set standard.
The requirement for precision measurement, as well as cleaning in place (CIP), motivated Interbrew to select a Coriolis mass flowmeter - the Promass 83 A from Endress + Hauser. The instrumentation specialist has three Promass flowmeters for small flow rates: a meter with a tube diameter of 1 mm for measurements of up to 20 kg/h, a meter with a tube diameter of 2 mm for measurements of up to 100 kg/h, and one of 4 mm for measurements up to 450 kg/h. In this instance, the brewery selected the meter with the largest tube diameter, due to highly viscous liquid. The output signal is 4-20 mA adapted at the analog input of the PID controller that, in turn, calculates and adapts the control point via the frequency drive.
A second/third flowmeter placed in series was decided against, as increasing the number of devices, simply increases the risk of inaccuracies. Therefore, Interbrew, rather controls the use of hops, by measuring the level in the buffer vat using an Endress + Hauser capacitance level sensor. Based on the measured level, consumption is continually controlled in the PLC (programmable logic controller) and compared with the mass flowmeter.
As a lesser-quality Pilsner is out of the question, samples are still sent to the laboratory. However, the frequency has significantly dropped, since the mass flowmeter was added to the control loop. As a final control measure, each vessel of Pilsner is tasted by a group of experienced tasters before the beer is filtered.
For more information contact Grant Joyce, Endress + Hauser, 011 262 8000, [email protected], www.za.endress.com
| Tel: | +27 11 262 8000 |
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