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58 years of service

Published by
World Coal,

Termoelektarna Šoštanj d.o.o. (TES), a Slovenian power plant operator, has been using Voith variable speed fluid couplings for 58 years. The couplings are used in Block 1 and Block 2 of the Šoštanj coal-fired power plant. They control the speeds of the boiler feed pumps – and have been doing it since 1956 without unplanned downtime.

Using the speed control capability of the boiler feed pump, the main control component of a power plant, the operator can easily match its process to the fluctuating energy demand of its customers. In 1956, TES elected to install the Voith hydrodynamic variable speed fluid coupling (type 510 SVL) to control the speed of the pump at Šoštanj. The fill level of this fill-controlled coupling can be changed during operation. This allows precise, stepless speed control. As a result, the boiler feed pump is always operating in the optimum speed control range, helping TES save energy and benefit from lower operating costs.

Although the power plant operator has long since had to recondition the surrounding components in the driveline, the variable speed fluid coupling in the Šoštanj power plant has been operating reliably for 58 years. With its compact, robust design, the coupling is especially well suited to extreme ambient conditions such as heat and cold. It uses the hydrodynamic principle, that is, the force is transmitted without wear. The coupling lifetime is consequently many times that of a variable frequency drive. This saves the operator maintenance and service costs.

At the same time, the variable speed fluid coupling provides the operator with additional advantages. Thanks to the mechanical separation of the drive side from the driven side, the coupling protects the entire driveline against vibrations and impacts. In addition, the motor runs up to speed without load and the driven machine accelerates gently. This reduces the load on the driveline and extends the lifetime of the individual components. The variable speed fluid coupling increases the availability of the entire system while avoiding the costs and loss of revenue that come with unplanned downtime.

The Šoštanj power plant in Slovenia is currently being expanded by another block. This block will provide 600 MW of power. Voith is supplying three Vorecon variable speed planetary gears and eight geared variable speed couplings for the new block.

Written by Voith Turbo.

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