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| DSM Nutritional Products AG; Wallis (Schwitzerland) | | Efficiently Controlled | Frequency-controlled pump drives at DSM Nutritional Products
In the Swiss canton of Wallis, the Dutch company DSM Nutritional Products AG has introduced a new concept for saving energy, in which large cooling circuits are equipped with frequency-controlled drives. The new solution not only allows more dynamic control of the plant in comparison with the previous valve control but also offers savings due to the much lower consumption of primary energy.
Among other things, DSM produces isophytol, a preproduct of vitamin E, at its Lalden factory in the Swiss canton of Wallis. In order to reduce energy costs, DSM has chosen modern system technology for the process cooling. The key components of the two optimized cooling-water systems are two redundantly designed pump drives, each of which takes over the continuous heat discharge via the giant plate heat exchangers of the two existing circuits.Expected savings of 70,000 Swiss francsThe mass flows for the cooling were previously provided by fixed-speed pumps with a valve control. However, these "throttle" large amounts of energy in the mixing mode, reducing the efficiency. In the upgrade of this plant section, variable-speed pumps were installed, the mass flow of which can be adapted by frequency converters of the Micromaster 440 type. Christoph Fux, who is responsible for the electrical engineering and automation at the factory, says, "With the new type of control, we are expecting annual energy savings in the region of 70,000 Swiss francs."The entire plant is monitored by the factory's control station, to which the frequency converters are connected via Profibus DP. The Micromaster 440s have six digital inputs, two analog inputs, and one PTC/KTYinput for monitoring the winding temperature in the motor. There is an analog pressure sensor between the feed and return in the cooling-water circuit, which monitors the pressure level. When the pressure drops, the pressure drop is reported and the frequency converter increases the pump speed. When the pressure rises, the sensor causes the electric motor to run more slowly.System thinking is all part of the serviceA new era has begun with the use of the Micromaster 440 frequency converters at DSM in Lalden. Previously, frequency converters of the Masterdrives series were mainly used. "We have had good long-term experience with these," Fux sums up. The first use of the Micromaster 440 for simpler applications also looks very promising, in Fux's opinion: "We have had no problems at all so far."Micromaster 440 Sophisticated vector control Guided commissioning High overload capability Evaluation of pulse transmitters Constant and square torque Load torque Three switchable drive data records Compound braking Integrated brake chopper up to 90 kW Free function components Four fade frequencies Automatic restart Minimal stress on motor when inverter connected to rotating motor Bus-capable PC commissioning Pluggable operating panel
Ideas 1 / 2007 | |
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