Furnace upgrade exceeds expectations


Modernizing existing melting furnaces can pay off quickly. „Vesak brook“ from Southern Bohemia, a foundry and manufacturer of car parts, has recently seen just how quickly. Together with StrikoWestofen, the company completed a comprehensive modernization project to bring its StrikoMelter shaft melting furnace from 1998 on par with the state of the art. The results have exceeded all expectations: for example, energy consumption is down 20%, melting performance up 40%. The investment paid off in the first year.

 Even after 17 years of use, the Česká zbrojovka foundry in Strakonice, Czech Republic, still had a reliable partner in its StrikoMelter. The company decided, therefore, that it could be modernized rather than replaced. For this, Česká zbrojovka drew on the know-how of furnace expert StrikoWestofen. The main objective of the project was to increase productivity and energy efficiency in order to reduce operating costs. 

The focus of the upgrade was on the heart of the furnace: the lining. Depending on operational demands and wear, relining is an unavoidable fixture in a furnace system’s life. The flow guidance, and with it the structure of the lining, are critical to the energy efficiency of any melting furnace. That’s why StrikoWestofen focuses in particular on the geometry of the lining and the materials used. For the relining at Česká zbrojovka, latest technical advances were applied to unlock significant energy savings while also increasing melting performance. The relining paid for itself within a short time.

Bridging the gap: tailored leasing of melting capacity

To ensure that customers don’t suffer periods of downtime during modernization projects, StrikoWestofen offers a special service: depending on requirements, customers can lease melting capacity to bridge the gap. In the case of Česká zbrojovka, this was not necessary, as the downtime needed for the upgrade had been scheduled beforehand. 

As part of the modernization, a shaft fill level laser was retrofitted to the old StrikoMelter. It allows charging cycles to be optimized, ensuring the shaft has the optimal fill level at all times. Thereby, the ETAMax principle of integrated heat recovery can work to its full effect: through the intelligent use of waste heat in the melting shaft, fuel consumption and metal loss are reduced considerably compared to other technologies on the market. 

The experts from StrikoWestofen also installed a new charging unit. In addition to increasing operational reliability, this also makes a considerable contribution to the overall efficiency and performance of the system. 

Only 52m3 of natural gas per tonne of aluminium

The energy reduction target for the upgrade was to lower energy consumption of the furnace to 670 kWh/t. The actual result exceeded this goal by some stretch, bringing energy consumption down to only 520 KWh/t, i.e. only around 52m3 of natural gas per tonne of molten aluminium. 

Despite this reduction in input energy, it was possible to increase the furnace’s melting performance by 40% - from one tonne per hour to about 1.4 tonnes. 

“We didn’t think this was possible! And thanks to the smooth project management, we had next to no downtime and were able to take the furnace back into operation after a short time,” says Petr Havelec, the director of the metallurgy division at Česká zbrojovka. 

The modernized furnace can now match the performance of a new installation. Due to the success of the project, Česká zbrojovka is now looking into upgrading their second StrikoMelter in the same way. 

Holger Stephan, manager of the Service and Spare Parts division of StrikoWestofen, says: “We are delighted to see more and more aluminium foundries realizing that investment in existing, tried-and-tested systems can be worthwhile. If these are made in co-operation with us as the OEM, we are often able to retrofit our very latest developments. This can unlock considerable increases in performance and efficiency. After each completed project, we notice a rise in inquiries about equipment modernizations – so the results are clearly speaking for themselves.”

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