Special Screw Feeder for Metering Green Malt BRIESS Malt in Chilton, WI

General Description

BRIESS Malt is a privately owned company that has been in business since 1876. BRIESS produces and sells malts and specialty malts to the brewing industry. The BRIESS Malt plant in Chilton, WI contacted KWS about a problem application where a feeder screw was moving less than half of the design capacity of green malt from a hopper to a bucket elevator and therefore, limiting production capability. Multiple changes from the original design were directly contributing to the productivity reduction. The original design had a variable pitch feeder screw that was later incorrectly replaced with a standard full pitch screw that was incapable of metering green malt evenly from the hopper.

In addition, the diverter inside the hopper and above the screw was also removed adding additional headload pressure to the pipe of the screw causing deflection and broken coupling shafts. In an attempt to decrease the pressure, the hopper size was reduced to lower the head load on the screw. To make matters worse, green malt was sticking to the pipe on the screw which limited the amount of material being metered. These combined factors caused the motors on the screw feeder to draw excessive current and “amp out”, resulting in major production problems at the plant. KWS partnered with Motion Industries to provide a long term, cost effective solution.

Design Parameters

KWS Advantages

KWS made a joint call with Motion Industries at BRIESS to evaluate several problem areas that were limiting production. After seeing the application, the KWS team discussed performance deliverables with the BRIESS Malt Maintenance Supervisor. Once the operational needs were determined, capacity and horsepower calculations were performed to determine the proper diameter, pitch, speed and horsepower of the new screw feeder. Engineers at KWS generated approval drawings to confirm critical dimensions. KWS replaced the problematic screw feeder with a 304 stainless steel variable pitch ribbon screw feeder to meter the sticky green malt into the bucket elevator. The ribbon type sectional screw is excellent for conveying sticky materials and the variable pitch screw feeder is designed to evenly unload the entire hopper. In addition, the open spacing between the flights and pipe eliminates collection and build-up of the material. The new design has BRIESS Malt once again producing at a high level.

Special Features

KWS added a 304 stainless steel diverter or “hogback” above the screw feeder to reduce the headload pressure on the screw, extending equipment life and improving performance. BRIESS Malt coordinated with KWS to modify the internal design of the screw feeder and “hogback” so that green malt would not accumulate and spoil inside the hopper and screw feeder. After performing torsion and bending calculations to determine proper shaft sizing, KWS increased the shaft diameter of the screw feeder to accommodate the slower screw speed and increased torque. The new Dodge drive unit is operating very well without drawing excessive current and “tripping” out the motor.