Ejectors pump hot dirty gases out of the molten steel and evacuate them through the ejector stages and interondensers.
Ejectors are the established pumping systems for vacuum degassing of steel because of high gas handling capacities at low pressures. Nash provides the right solution and system for your steel degassing requirements. Learn more by reviewing our portfolio of ejector vacuum systems.
Vacuum degassing of steel takes place after the molten steel has left the furnace and before the steel is poured into ingots or processed through a caster. The main objectives of steel degassing are:
After leaving the furnace, molten steel is moved in a ladle to the degassing area and positioned inside the degasser. The ladle is covered with a layer of slag that is penetrated approximately 18” deep by the snorkels.
As the snorkels are inserted, the NASH steam ejectors create a vacuum of 0.5 mm HgA and draw the steel into the chamber. The lower partial pressure within the vacuum chamber removes both hydrogen and nitrogen gases from the liquid steel, which are both vented as the steel is continuously circulated. The evacuation time is usually five minutes or less.
There are three basic types of vacuum degassers: steam, recirculation, and ladle. The system choice is determined by many factors, including the primary objective of the degassing capital investment costs, operating costs, temperature losses, tonnage, throughput, space availability, and turnaround time.
All types of systems take place in a vacuum chamber, and the vacuum is created by multis-stage NASH steam jet ejectors, often in combination with a NASH liquid ring vacuum pump.
Steam jets work on a constant mass flow basis, while liquid ring vacuum pumps work on a constant volume basis. Used together, an economic break-even point may be reached to take advantage of the best characteristics of each. Our degassing system is designed to meet specific requirements and your Nash engineer can help you determine the optimal solution. The steel degassing process requires:
In order to design your degassing system, you will need the following information:
With over 110 years of liquid ring vacuum pumps and steam jet ejector design experience, Nash is the premier provider for your systems and solutions.
Backed by our NASH CERTIFIED™ Service offering, as well as a full range of OEM parts, spare, and aftermarket services, we can act as your trusted partner; protecting your investment and providing you with total peace of mind.