The modern, modular pump system concept of Oerlikon Leybold for vacuum technology in steel degassing has proven its effectiveness as Siemens Metals Technologies has ordered another mechanical vacuum system which will be used by an end customer in Mexico.

This vacuum system with an effective pumping speed of almost 600,000 m³/h, is the largest vacuum system built by Leybold in its 164-year history to date. The Siemens VAI customer Altos

Hornos de Mexico., SAB de C.V. (AHMSA) extended the product range of the converter steel mill No. 2 to steel grades for oil and gas industries.

The treatment capacity of the 150-tonne double-RH vacuum degassing should be around two million metric tonnes of liquid steel per year, in approximately 50 batches per day.

With this new plant, AHMSA will be able to produce special steel grades with a very low hydrogen content, as they are required for applications in the oil and gas industries. The commissioning of the new RH plant is planned for October 2015.

The required vacuum technology is covered by systems of Oerlikon Leybold Vacuum. Essential functions of RH degassing systems include the removal of hydrogen, the forced decarburisation and the chemical heating of the liquid steel. The treatment of the molten steel is carried out under vacuum conditions, reducing the carbon content by means of oxygen injection in a first step. Afterwards the pressure is further lowered and the dissolved hydrogen content in the steel is lowered to the target value. A low hydrogen content is the essential prerequisite for the production of these high-strength steel grades.

The increasing demand for higher-quality steels triggers the need for innovative and efficient steel degassing. The traditional steam ejector systems have a number of disadvantages such as high energy consumption and significant CO2 emissions. In addition, the metallurgical processes see increased cost due to a very complex wastewater treatment and sometimes also by the expensive operation of steam boilers. Therefore, modern, mechanical vacuum systems are a real alternative, functionally as well as economically.

Especially in comparison with steam ejectors and liquid ring vacuum pumps, innovative, mechanical vacuum pump system for steel degassing offer a rugged, reliable and powerful vacuum supply with a stable vacuum level independent of external disturbances such as the water temperature. This is particularly important with regard to the ever increasing demands on cost of ownership and CO2 reductions.

Using modern, robust, dry compressing screw type vacuum pumps and Roots pumps such systems are nowadays used even for the most demanding degassing processes.

“The future lies in handling not only the manufacturing aspects of the industrial processes in question, but also in managing the increasing environmental demands. The energy balance and the intelligence of the components used to build up systems will drive future markets,” explains Dr. Martin Fuellenbach, CEO Oerlikon Leybold Vacuum, “The chance to control and monitor systems facilitates the optimisation and maintenance of the production process. This certainly represents a cost advantage.”