SMOOTH-SURFACE MOTORS IN THE MALT HOUSE A knowledgeable specialist in this field, Nord Drivesystems has configured clean and resilient systems based on efficient smooth-surface motors for a Czech malt house. Traditionally, beer brewers used to prepare their own malt. Now, specialized malt houses often handle this job for them. The processes in these facilities are largely automated and carried out with state-of-the-art equipment. One large, modern malt house can be found in Nymburk near Prague, the Czech capital. The people of this region remain very committed to the high standards that make Czech beer famous all around the world. In the first phase of processing, grain is steeped in water until it is ready to germinate. Next, the grain is placed in a so-called Saladin box, where it sprouts leaves and roots. Enzymes are formed and enriched. They convert the starch into malt sugar. All the while, the grain is regularly raked and aired. After about five days, the green malt is transferred to a drying kiln. Retrofit with over 100 new drives Before the advent of automation, turning the barley and clearing the malting floor were strenuous physical tasks that took many hours to complete. Modern malt houses have long ago switched to large mechanical turners, which enable production volumes of tens of thousands of tons per year. When the Nymburk malt house required a full-scale retrofit of these machines, they turned to Moravské potravinárské strojírny (MOPOS), a Czech OEM for the food industry with a particular focus on malt house and bakery machinery. Eight turners, each over seven metres wide and weighing over 7.5 tons, were refurbished. A total of 120 drives had to be replaced with new, stateof the-art systems. Each turner includes a main drive which moves the machine on rails that span the length of the Saladin box – over 53 metres. These boxes are about two metres deep. In addition, there are 14 individually driven vertical screws per turner. These rake the germinating grain once or twice per day as needed to keep it 22 September 2017 cool and aerated. Finally, a scraper mounted on the machine serves to discharge the green malt. New smooth-surface motors preferred In this project, Nord Drivesystems was the single source of drive solutions. Nord supplied 112 geared motors for the screw agitators as well as eight main drives with drive electronics for speed control. The drive manufacturer’s Czech subsidiary, Nord-Pohánêcí technika, s. r. o., worked closely with their long-time customer MOPOS to configure these systems to suit the application. The ambient conditions in the malt house are tough. The atmosphere is saturated with 100% humidity. Moreover, water vapor reacting with carbon dioxide also leads to the permanent presence of weak carbonic acid (H2CO3). Given these very tough operating conditions, MOPOS selected smooth-surface motors, which Nord has been manufacturing since 2013, for the very first time. In contrast to conventional motor types, the casings of these motors have no cooling fins, which eliminates typical dirt traps and surfaces prone to attract condensation moisture. The standard versions of these systems already provide IP66 ingress protection. Their terminal boxes are filled with solid resin. Both the rotors and stators are treated with a special, moisture-resistant lacquer. Efficient thermal management The smooth cases of the motors provide extra resistance against harmful influences as noted above. However, this design requires careful thermal management, especially since the drives in the MOPOS machine run in continuous operation. The smooth-surface motors on the screw agitators feature a temperature sensor and a cooling fan. This allows for smaller sized motors without a risk of overheating. The motor on the main drive is non-ventilated and therefore solely cooled ENGINEERING IN FOOD & BEVERAGE In the selection and configuration of drives for the food and beverage industry, food safety is only the most obvious major concern. Various other issues must also be addressed with common challenges including adverse environmental conditions that must be kept under control from the outset. In modern malt houses, automation is reshaping production processes with century-old traditions
ENsep17-eMag
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