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REBOX® HLL is designed for customers looking for a simple, cost-effective way of optimising reheating furnaces that can be deployed on demand without any changes to the existing furnace infrastructure.
With REBOX® HLL, oxygen lances are mounted in the furnace walls next to conventional burners. These are then used to inject oxygen at high velocity into the furnace and replace most of the air used for combustion. Up to about 75% of the combustion air is thus replaced with oxygen in zones targeted by HLL. The elimination of nitrogen increases thermal efficiency, also decreasing exhaust gas volumes and reducing NOx emissions. In fact, it cuts exhaust gas volume per MW by more than 50%. Improved heat transfer also helps to reduce energy consumption. In addition, REBOX® HLL provides more uniform heating for improved billet quality. REBOX® HLL can be turned off at any time, enabling the furnace to revert back to its normal air/fuel operating mode. Hence it is an ideal way to ramp up performance temporarily, for instance to accommodate fluctuations in demand.
Customer: Ovako is a leading European producer of engineering steel for customers in the transport, manufacturing, construction and agricultural industries. Every year, it supplies two million tonnes of wear-resistant products made from low-alloy and carbon steel to rolling and bearing manufacturers, heavy vehicle and automotive players and engineering companies. Ovako Smedjebacken’s production site specialises in long steel products, and has both a melt shop to produce billets and a medium rolling mill. The billets are reheated in a walking hearth furnace, where they are heated to temperatures of up to 1180°C for approximately two hours.
Challenge: Ovako used conventional air/fuel burners in its reheating furnace for steel billets. To maintain its leading position in the European engineering steel market, the company was interested in increasing production capacity and enhancing process efficiency.
In concrete terms, Ovako was looking to upgrade its reheating system to improve safety and enable a great degree of automation. It also wanted to lower fuel consumption, improve heating efficiency and reduce carbon dioxide (CO2) and nitrogen oxide (NOx) emissions. By reducing the flue gas volume and its temperature, the company would also be able to reduce the load on the recuperators.
"With REBOX® HLL, Linde provided us with a one-stop, all-inclusive solution to increase productivity and save fuel while also reducing NOx emissions. It has given us a proven, low-CAPEX route to the flexibility we need to stay competitive in a global marketplace."
Anders Lugnet, Global Furnace and Combustion Expert of Ovako Group
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