Alternating Stirring Modes for Rotor Life Extension
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Solution Overview
Problem
The refractory axial rod in impellers used for mechanically stirring chrome-containing molten pig-iron or steel experiences rapid erosion and melting during eccentric stirring, leading to a shortened lifespan and increased maintenance frequency of the rotor, unlike in blast furnace molten pig-iron where eccentric stirring is effective.
Innovation Solution
Implementing a method that alternates between concentric and eccentric stirring modes to form a protective hard layer on the axial rod, where concentric stirring allows self-repair through adhesion of slag and molten material, and eccentric stirring promotes material loss control, thereby extending the rotor's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If eccentric stirring is used to improve stirring efficiency and reduce impeller rotation speed, then the impeller life is prolonged, but the axial rod experiences rapid erosion and melting in chrome-containing molten iron
Solution Approach 1:
The patent applies periodic action by alternating between concentric stirring and eccentric stirring modes. During concentric stirring, the axial rod surface is repaired through adhesion of molten material and slag. During eccentric stirring, the stirring efficiency is enhanced. This periodic switching resolves the contradiction by allowing the axial rod to recover during concentric phases while maintaining high efficiency during eccentric phases, preventing continuous erosion.
2Reliability
If concentric stirring is used to allow self-repair of the axial rod through adhesion, then the axial rod is protected, but stirring efficiency decreases and rotation speed must be increased
Solution Approach 1:
The patent uses periodic action to switch between concentric and eccentric stirring modes. Concentric stirring provides periodic repair opportunities for the axial rod surface through material adhesion, while eccentric stirring provides periodic high-efficiency mixing. This time-based alternation allows both rod protection and high productivity to be achieved in different phases of the operational cycle.
Solution Approach 2:
The patent applies dynamics by making the stirring mode adjustable and changeable over time. The system transitions from a static concentric or eccentric mode to a dynamic system that can switch between modes based on operational needs. This dynamic adjustment allows optimization of both rod protection and stirring efficiency at different times during operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This alternating method significantly prolongs the life of the rotor by controlling material loss and adhesion, enhancing the efficiency and reducing costs in desulfurization and chrome recovery processes for stainless steel production.
Implementation Method 1
mechanically stirring chrome-containing molten iron (molten pig-iron or molten steel) with an impeller
Implementation Method 2
concentric stirring allows self-repair through adhesion of slag and molten material
Implementation Method 3
the refractory axial rod in impellers used for mechanically stirring chrome-containing molten pig-iron or steel experiences rapid erosion and melting during eccentric stirring
Data Source
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AI summary
[Problem] To provide an operation method for noticeably prolonging the life of "rotor" where the impeller and the axial rod are integrated with each other, in mechanical stirring of chrome-containing molten iron. [Means for Resolution] An operation method for mechanically stirring chrome-containing molten iron, which comprises a refining process of mechanically stirring chrome-containing molten iron contained in a refining vessel by the use of an impeller having a rotation axis in the vertical direction where the refining vessel is such that the horizontal cross section of the inner wall thereof is circular around the central axis of the vessel in the vertical direction and the impeller, as integrated with the axial rod covered with a refractory, rotates around the central axis of the axial rod, as the rotation axis thereof, wherein: the stirring mode is regularly or irregularly switched, as selected for each stirring charge, between "concentric stirring mode" of stirring the molten iron in a state where the rotation axis of the impeller is centered in the central axis of the vessel and "eccentric stirring mode" of stirring the molten iron in a state where the rotation axis of the impeller is decentered from the central axis of the vessel.