EISELE, a leading manufacturer of pumps and mixers for the agricultural and biogas sectors, has developed a new energy-efficient series of units based on its proven GTWSB submersible mixers. These will be presented for the first time in December at the Biogas Convention & Trade Fair 2023 in Nuremberg, Germany. The slow-rotating large-propeller GTWSL and GTWSL-E devices offer maximum savings potential when mixing the substrate at speeds of up to 113 rpm.

The GTWSL series has an asynchronous motor that starts up slowly via a soft starter. In contrast, the GTWSL-E has a synchronous energy-saving motor in energy efficiency class IE5, which operates with a frequency converter. This efficiency class is currently unique worldwide for biogas agitators. The frequency converter enables stepless speed control of the GTWSL-E for optimal adaptation to different operating conditions. Unlike asynchronous motors, the IE5 energy-saving motor in the GTWSL-E achieves over 95% efficiency even at low speeds, and currently offers the highest savings potential on the market.

Most economical mixer in the world

Increased environmental awareness, rising energy costs and the trend towards sustainability mean that saving energy has become more important in recent years. The new GTWSL series guarantees a high circulation rate with low drive power, and enables very high efficiency even at low speeds.

The IE5 energy-saving motor, combined with large propeller diameters, slow speeds and low drive power, makes the GTWSL-E the most economical mixer in the world to date. As a result, biogas facility operators, plant constructors and service companies in Germany can receive a 50% grant from the German Federal Office for Economic Affairs and Export Control (BAFA) for investments in construction projects using this submersible mixer.

Also suitable for thermophilic biogas plants

The unit has two variants – each of which is also available in an IE5 version. Variant 1 has a drive power of 11 kW and a propeller diameter of 1340 mm. Variant 2 delivers 15 kW of drive power with a propeller diameter of 1430 mm. The propeller, the slide with nozzle, and installation parts are made of stainless steel (V2A) as standard. Mechanical seals in the housing are located on both the motor and medium sides. The insulation class according to IEC 34-1 (insulation class H) allows high temperatures of up to 180 °C in the motor insulation.

Robust build quality and in-house motor production guarantee the long service life typical of Eisele products. Compared to asynchronous motors, the energy-saving IE5 motor generates around 40% less heat. The weight and solid design of the unit enable low-vibration running characteristics while ensuring effective heat dissipation. The new GTWSL mixers can be used at immersion depths of up to 40 m. They are approved for substrate temperatures up to 65 °C, making them suitable for thermophilic plant operation. Numerous accessory components provide a wide range of installation and application options.