BOILERS PUMPS & VALVES
he history of the blast furnace process is a long story of great innovations and technical improvements. Again and again, there have been courageous innovators who were willing to question common methods in order to further optimise the production process of pig iron. In the 18th century, for example, Abraham Darby succeeded in using coke instead of charcoal. As a result, blast furnaces became considerably larger and more efficient. In the 19th century, Edward Alfred Cowper managed an innovation leap with the newly emerging blast preheaters. Today the so-called “Cowpers” are part of every blast furnace plant.
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Utilising the “sequence impulse process with induced shock waves”, the blast furnace has now reached the next stage in its evolution. Behind the SIP are thyssenkrupp
AT.PRO tec GmbH and its present managing director, Dr Rainer Klock. As a team, they developed the technology over a period of more than 10 years in such a way that its use at the blast furnace became possible at all. Today the employees at
AT.PRO tec bundle highly specialised expert knowledge from science and industry for the use of gases in melting processes.
The basic concept of the new process is to activate the areas deeper inside the furnace. In the standard process technology, a cone of coke is created - the so- called “dead man”. Incompletely reacted fine particles block this coke bed. The gas flow and heat cannot penetrate deeply enough into the furnace. The solution: strong intermittent impulses to enable the necessary deep penetration of the technical oxygen. This leads to a short-term, local surplus of oxygen and a more complete chemical conversion of the fine particles – even deep inside the coke bed. The shock waves associated with the impulses break open blockages at this point and mix the contents by means of strong turbulences. They ensure a more homogeneous gas distribution and a better flow-off of the molten metal and the slag.
REVOLUTIONARY OXYGEN IMPULSE TECHNOLOGY FOR STEEL PRODUCTION
From exper ment to l large-scale industrial use — th om experiment ti arge-scale industrial use — yssenkrupp
AT.PRO
tec GmbH is well known for the development of the sequence impulse process. When used on cupola furnaces, it considerably increased their cost-effectiveness in the past. In over 10 years of development work with Schubert & Salzer as their partner, Dr Rainer Klock and the team at
AT.PRO tec succeeded in getting the SIP technology to work on blast furnaces, too, with the help of sliding gate valves. The story of a researcher on the way to becoming a plant manufacturer.
PHASE 1: ASIPGO – THE COLLABORATIVE RESEARCH PROJECT OF THYSSENKRUPP AND RWTH AACHEN (2007- 2011)
The technology has been working successfully for years on a smaller scale in cupola furnaces and enables a considerable increase in cost- effectiveness. Use on the much larger blast furnaces was, however, still completely unresearched. When
AT.PRO tec approached RWTH Aachen and the Institute of Ferrous Metallurgy (IEHK) situated there with the subject, Rainer Klock had just completed his degree thesis. RWTH looked for research associates for the new research project, which was supported by thyssenkrupp as the industrial partner. “That was the perfect opportunity for me. Not only was I able to write my doctorate thesis directly following my degree, the project also offered me the possibility to work on one of
the largest blast furnaces in Europe”, said Dr Klock later. “The ASIPGO project was intended to pursue two goals over a period of three years: firstly to improve the use of SIP on cupola furnaces through automation and secondly to enable the use of SIP on blast furnaces.”
Within the framework of his doctorate thesis, Rainer Klock focused on research into use on the blast furnace. First of all, the physical and chemical processes were examined that made the SIP successful on the cupola furnace. The research group, consisting of employees from thyssenkrupp
AT.PRO tec, thyssenkrupp Steel Europe and RWTH Aachen, wanted to understand the processes in the raceway zone of a blast furnace and how they would probably be affected by oxygen impulses in order to be able to transfer the technology from the cupola furnace to the blast furnace with the collected knowledge. On the basis of these findings at the IEHK, a SIP test system for blast furnaces was finally constructed. Compared to the SIP system for cupola furnaces, significantly larger nominal diameters and pressures were now used. The system therefore had to be adapted and equipped with suitable components. One of the main focal points was the so-called pulse valves. These had to be capable of generating the strongest possible shock wave. Following a long series of investigations with different types of valve, the sliding gate valve from Schubert & Salzer was selected. The principle of this valve was fascinatingly simple: two slotted discs that slide over each other and seal against each other. A sealing plate, fixed perpendicular to the direction of flow on which another movable disc with the same slot arrangement is moved, changes the flow cross- section. The applied pressure difference presses the movable disc against the fixed disc and thus contributes to leak-tightness. The short opening times achievable by this principle and the pressure resistance with large nominal diameters were ultimately decisive.
12 JUNE 2023 | FACTORY&HANDLINGSOLUTIONS
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