Press Facts

Efficient furnaces for hot dip galvanizing

Zink KÖRNER cuts energy consumption in galvanizing by 15 percent

Controlled waste gas flow takes the heat in the furnace exactly where it is needed.

Hagen, Germany, May 9, 2017    The new RECU-CHANNEL recuperative heat exchanger system may achieve energy savings of more than 15 percent in batch-parts, wire and small-parts galvanizing. In typical batch-parts galvanizing plants, this may result in approx. 30,000 euros saved on natural gas costs every year.

For galvanizing at temperatures between 450 and 460 °C, Zink KÖRNER has developed its new RECU-TEC hot dip galvanizing technology, which allows the input energy to be recovered directly in the furnace. These furnaces are equipped with a steel tank and natural-gas fired flat flame burners.

Innovative recuperation technology

The new RECU-CHANNEL recuperative heat exchanger system heats the kettle very uniformly and exactly to the required temperatures. Operation of the furnace requires more than 15 percent less energy than traditional systems. Thus, more than 30,000 euros per year can be saved on natural gas costs, for example, in case of a batch galvanizing plant with an average through-put rate of 6 tons per hour.

While in conventional systems without RECU-CHANNEL technology the waste gas collects at the top, RECU-CHANNEL systems suck the waste gas from below in a controlled way allowing the waste gas to flow downwards past the outside surface of the kettle wall. Thus the waste gas transfers to the lower part of the tank exactly that amount of energy that is required for the process.

The channels are arranged at both long sides of the furnace extending along their complete length. Thus the waste gas travels long distances, giving it more time for the heat transfer. Using the residual heat in the RECU-CHANNEL to preheat the combustion air leads to a further increase in furnace efficiency.

The result: While the waste gas temperature of furnaces without RECU-TEC usually reaches 550 °C or more, the waste gas temperatures of the new furnaces are always below 400 °C, even in case of full load operation. This is a clear indication that the input energy is extremely efficiently used.

Highly efficient burner technology

Zink KÖRNER has developed the modulated KÖRNER FL 15/80 flat flame burners specifically for the heating of steel kettles. These burners feed just as much energy to the galvanizing furnace as necessary at any point in time.

Unlike intermittent burners, they operate with a combustion air ratio λ of only 1.10 – hence with much less surplus air than usual. Their efficiency is 10 to 20 percent higher and gas consumption correspondingly lower than that achievable by burners operating with a ratio of, let’s say, 1.20.

Additionally, the modulating operation avoids short-term consumption peaks. This saves on gas procurement costs as the gas suppliers calculate their provision fees based on the peak load of the furnace.

The burners are installed along the long sides of the furnace at two thirds of the furnace height (from the bottom). At that position, the heat requirement is highest due to the heat loss at the bath level.

Wire galvanizing 2018

Low maintenance costs with low energy consumption

At WIRE 2018 this year, technology leader KÖRNER will be presenting a new type of wire galvanizing furnace in hall 9 Booth A78.

There will be a presentation of different design examples of this wire galvanizing furnace, which meets all requirements and is characterised by very low maintenance costs and very low energy consumption levels. These claims are supported by operating experience itself.

Thanks to new energy-saving burner technology, KÖRNER can heat up highly sturdy and durable wire galvanizing furnaces with ceramic baths, without using immersed burners, which are susceptible to breaking.

The latest plant designed and set up by KÖRNER is a wire galvanizing furnace with a throughput capacity of 6.3 to/h, for a major international steel group.

Galvanizing plant for Tochinvest

Hagen, Germany, 21^st May 2013
In 2012, Tochinvest Zinc, a leading manufacturer of steel parts in Russia, installed a new hot-dip galvanizing furnace from Zink KÖRNER. Last February, Zink KÖRNER received the FAC for the plant.

The successful operation of the first galvanizing shop was reason for JSC Tochinvest to establish the Tochinvest Zinc division in 2011. This event also marked the kick-off of a new project, namely the construction of a further galvanizing plant in Ryazan, some 100 km to the southeast of Moscow.

For this project, Zink KÖRNER supplied the galvanizing furnace, complete with the housing, and the drying furnace. The tank is 13.0 m long, 1.8 m wide and 3.2 m deep. The new facilities were started up at the beginning of 2013. With trial operation running smoothly, already in February Tochinvest issued the Final Acceptance Certificate for the new plant.

Tochinvest Zinc specializes in the manufacture of crash barriers and bridge railings. The company also offers job galvanizing services for steel parts as diverse as lamp posts, traffic signs, barriers and customized steel structures for use in road construction.

The new furnace can galvanize up to 15 t/h. Assuming three-shift operation during 250 days of the year, Tochinvest Zinc will be able to produce 80,000 t annually. This makes Tochinvest Zinc the most productive galvanizing plant in Russia.

Already in 2007, Tochinvest, a leading manufacturer of steel parts in Russia, had built a hot-dip galvanizing plant. Also for that plant, Zink KÖRNER had supplied the galvanizing furnace, including the housing, and the drying furnace. That furnace is 7.0 m long, 1.5 m wide and 2.5 m deep. Right from the first day of operation, the galvanizing quality had been in compliance with the Russian GOST 9.307-89 standard and the international standard ISO 9001:2000.

29t furnace on its way to Omsk

Hagen, Germany, 2^nd April 2012
Zink KÖRNER has shipped a hot-dip galvanizing furnace to Omsk Electromechanical Factory in the Russian city of Omsk. This is already the sixth Zink Körner galvanizing furnace going to customers in Russia. Thus, every fifth galvanizing furnace installed in Russia during the last ten years is from Zink KÖRNER.

The new furnace has a zinc bath that is 13 m long, 1.7 m wide and 3 m deep. It will be primarily used to galvanize transmission masts and polygonal poles with a zinc coating that will protect the material against corrosion for several decades. The furnace will heat some 450 t of zinc to a temperature of 460 °C. Up to 12.5-m-long poles will be dipped into the bath of molten zinc.

As the furnace weighs 29 t, a heavy-load vehicle is needed to transport it over a distance of 5,100 km to the Russian city of Omsk, which is located almost 1,000 km east of the Urals. The journey is scheduled to take ten days. Two cranes were needed to handle the weight of the furnace during loading.

A total of 55 batch galvanizing furnaces are in operation in Russia, about 30 of which have been installed during the last ten years. Despite the long distances from Germany, Zink Körner supplied six of these furnaces – which is a share of almost 20 percent.

Peter Kordt, Managing Owner of Zink KÖRNER, explains this success: “In designing our furnaces, we exploit all available potentials for extremely efficient energy use and eco-friendly operation. This is not only important in Western Europe. Also Russian companies have become very conscious about environmental protection. The great number of orders from Russia shows that our Russian customers have recognized our role as a pioneer in efficient energy use. Moreover, also in Russia ‘Engineering made in Germany’ has a good reputation.”

By implementing modulating, infinitely adjustable flat flame burners, a wall construction with less heat transfer and a novel reflecting refractory coating, Zink Körner significantly increases the energy efficiency of batch galvanizing. The sum of all these measures brings down the energy costs for a typical furnace by approx. 25,000 euros per year.

The furnace for Omsk is designed for throughput rates of up to 10 t/h. It is equipped with ten flat flame burners of the FL 20/50 type, which Zink Körner specially developed for batch galvanizing furnaces. While using the relatively low-cost natural gas as fuel, these burners provide the same smooth and mild heating as previously only achievable by electrically heated furnaces.

The burners achieve an efficiency of 75 percent. This makes Zink KÖRNER one of the market leaders in terms of energy efficiency. Unlike burners commonly used in the past, these innovative burners operate in a modulating mode. They are infinitely adjustable within a range of 1:10. Through this, the power is being constantly adjusted to match the furnace throughput. Consequently, the furnace consumes exactly the amount of energy required in the specific moment. This regulating mode also avoids abrupt temperature changes, which may cause excessive stresses in the galvanizing tank structure.

In addition to these features, Zink KÖRNER implements further efficiency-enhancing measures. Diffusor plates mounted on the burners direct the gas flow along the inner furnace wall. This produces a combination of radiant and convective heat, which has the positive effect that a high input of heat into the galvanizing tank is achieved at relatively low furnace temperatures. The multi-layer, 300-mm-thick insulation reduces heat loss and the innovative ceramic coating applied to the fibrous insulation additionally reflects the radiant heat towards the interior of the furnace.