Secondary cooling in continuous casters

Steel producers all over the world are feeling the pressure from new competitors due to the trend of globalization. On the one hand, they are forced to reduce production costs, while on the other they have to meet demands for new high-quality steel grades. In order to succeed in this environment, it is essential that all processes are optimized – including secondary cooling.

Three factors lead you to the optimum cooling of your continous casting processes:

• Lechlers' unique range of products and solutions
  The ultimate cooling solution for all requirements does not exist. Instead each process has individual demands for every installation type, every steel format and every steel grade. Due to multiple possibilities, standard solutions are usually not suitable. Therefore we analyse the specific situation of our customers in detail.
• Lechlers' decades of experience
  In view of the complexity of the task, we always take into account the overall process when developing our solutions. Our know-how and decades of experience in continuous casting form the basis for products and cooling solutions that ensure increased productivity and quality in steel production in the long term.
• Lechlers' individual advice
  Each customer has his own requirements and goals. That is why we take time to listen first of all. We then clarify any open questions together with you. When developing your custom solution, we use state-of-the-art measuring techniques in order to precisely determine liquid distribution and cooling performance. Close cooperation with our customers is a high priority for us.

The main purpose of nozzles in continuous casting processes is the cooling of the strand surface. This spray water cooling is the only controllable part of the secondary cooling process and is therefore a major factor in determining maximum productivity and optimum quality of continuous casting processes.

In the secondary cooling process the spray nozzle arrangement and process parameters determine the characteristics of spray water cooling. The spray nozzle arrangement defines the area on the strand surface where spray cooling occurs. Process parameters such as operating pressures and flow rates determine the cooling intensity and distribution on the strand surface.

Heat extraction from the strand surface is a result of both, nozzle arrangement and process parameters which therefore define the cooling and solidification process. As a premium nozzle manufacturer Lechler does not only supply prime quality nozzles, systems and accessories; Lechler also provides detailed engineering and measurement knowledge and services in the areas of both nozzle arrangement and process parameter optimization.

The optimization potentials in nozzle arrangement include nozzle alignment, header and segment pipe design and liquid distribution optimization for new and existing systems. For process parameters optimization potentials lie in the choice of the atomization type (air-mist or water only), spray kinetics, spray impact and the correlated cooling efficiency (measured surface heat transfer coefficient).

The requirements on secondary cooling of the casting processes are varying with section size and steel grade. Therefore special nozzle types are available to meet the multiple requirements and provide the optimum cooling solution for each secondary cooling system.

In addition Lechler provides capabilities in continuous casting process simulation which can be utilized for secondary cooling process optimization, e.g. by optimizing the steel grade specific spray plan or predicting the maximum casting speed for an upgraded secondary cooling system.

For example full cone and oval cone nozzles have been optimized in terms of liquid distribution and flow rates to meet the challenges of long product casting processes.

Also special nozzle series have been developed for long and flat product casting processes:

• „„Billetcooler Series for long product casting
• „„Mastercooler Series for flat product casting
• „„Mastercooler Hard-Hard Cooling for thin slab casting processes
• „„high quality nozzle technology
• „„long term experience in the field of secondary cooling
• „„caster life-cycle support
• „„process optimization