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Engineering Steel Belgium is saving EUR45,000 (GBP39,415) per annum on the operation of three cooling pumps on one of its electrical steel furnaces since the installation of WEG motors and drives.

WEG distributor Leclercq Energy supplied three WEG W22 132kW, IE2 high-efficiency motors, controlled by WEG CFW-09 variable speed drives to Processautomation, which supplied and commissioned the complete energy saving package, including control panel with drives, softstarters, PLC, and process supervision via Profibus-DP.

Engineering Steel Belgium (ESB) produces steel and related products for transport, energy generation, and aeronautics industries in Belgium.

Its products include carbon and lightly alloyed steel, in the form of cylindrical continuous cast blooms, and bottom-poured ingots for the manufacturers of open and closed die forgings, seamless rolled rings, train wheels, seamless tubes, and extruded parts, as well as bar rolling mills.

Steel making is an energy intensive process where even small efficiency gains can result in substantial energy savings and reductions in operating costs.

ESB is aware of this, and also of the need to cut energy consumption to reduce its overall carbon footprint.

One of the primary focuses of the company’s energy reduction programme is its electric UHP (85 MVA) arc furnaces.

These are cooled in a closed-circuit cooling system, which includes three large pumps driven by 132kW motors.

Aware that the total cost of owning a pump is 90 per cent energy consumption, ESB decided to replace the existing standard motors with three of WEG’s W22 high-efficiency machines.

The W22 motors are said to exceed the energy performance requirements of the IEC60034-30 energy efficiency standard, reducing losses by between 10 per cent and 40 per cent compared with typical motors.

Although W22 motors made a significant contribution on their own to reducing the energy consumption of the three pumps, further potential for saving energy was prevented by the motor control system, which was achieved using contactors.

This meant that the pumps were usually running at full speed, irrespective of the varying demands placed upon them.

ESB appointed Processautomation to undertake a complete analysis of the kiln cooling process, with the goal of maximising the energy-saving potential of the application.

Processautomation began by conducting an audit of the operating hours of the pump system.

This comprised three parts: normal weekday operation of two pumps (the third is a standby) totalling 94 hours a week; weekend operation, which occurred on six weekends a year to counteract the threat of frost; and operation during the Christmas shutdown, for a total of 16 days, also due to the threat of frost.

During all these operating periods the pumps were run at 100 per cent speed, even during the frost-susceptible periods when intermittent operation would have been more appropriate.

Based on these operating hours, Processautomation calculated that the total annual cost for operating the pumps on the cooling system was EUR117,000; this figure was based on an energy cost of EUR0.09/kWh.

On the basis of this figure, Processautomation calculated that further energy savings could be achieved by the application of variable speed drives to the pump motors, in conjunction with a PLC-based process automation system.

The WEG CFW-09 132kW inverter drives selected for the motor control task are matched to the W22 motors, producing the optimum operating characteristics for high-efficiency operation.

The CFW09’s self-tuning feature automatically matches the drive to the motor and load, relieving the user of the task of entering a motor map.

Following installation, normal weekday operation between 15:00-20:00 requires the operation of one pump, and this running at 70 per cent of maximum speed, due to the variable control provided by the WEG CFW-09 drive.

From 20:00-11:00, two pumps are in operation, running at 89.2 per cent of maximum speed, also due to variable speed drive control.

At weekends and the Christmas shutdown, when frost could be a problem, two pumps are still required, operating at 89.2 per cent of maximum speed.

However, with the flexible control provided by the WEG variable speed drives, the pumps are only required to run for five minutes in every 30 minutes, achieving substantial energy savings.

This contribution, plus the major savings from normal weekday operation, mean that the total annual energy cost for operating the pump cooling system is reduced to EUR72,000, based on an energy cost of EUR0.09/kWh.

The resulting annual savings of EUR45,000 – or 38.5 per cent – for ESB are a contribution both to the company’s bottom line and to the cost of the energy-saving system itself, guaranteeing a fast return on investment on the system outlay.

WEG Electric Motors

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