Steel Strip Pickling Headers for High-Turbulence Oxide Removal
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Solution Overview
Problem
The steel industry faces challenges in efficiently removing oxide layers, particularly fayalite, from steel surfaces during the pickling process, which slows down production and requires reduced strip speeds due to the low solubility of fayalite in hydrochloric acid pickling liquor.
Innovation Solution
A pickling installation and method that utilizes a combination of high turbulence water pillow cooling (WPC) and high turbulence low pressure (HTLP) principles, along with the addition of abrasive particles, to create a highly turbulent acid solution environment that enhances the chemical and mechanical removal of oxides, increasing pickling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional acid pickling is used to remove oxide scale from steel surfaces, then pickling treatment is applied, but pickling time increases and strip speed must be reduced
Solution Approach 1:
The patent applies high turbulence flow conditions to the pickling liquor, creating intense mechanical agitation and vortex patterns that enhance mass transfer between the liquid and steel surface. This mechanical action accelerates oxide removal by continuously renewing the acid solution at the steel surface and disrupting the protective oxide layers more effectively than conventional stagnant or slow-flow pickling methods.
Solution Approach 2:
The patent modifies key parameters of the pickling process by increasing the turbulence intensity and flow velocity of the pickling liquor to extreme levels. By changing the hydrodynamic conditions from conventional low-turbulence flow to high-turbulence flow with specific velocity ranges (0.5-2.0 m/s), the pickling rate is dramatically increased, allowing faster processing while maintaining effective oxide removal.
2Reliability
If pickling speed is reduced to ensure sufficient pickling time for removing oxide layer, then oxide removal is improved, but productivity decreases
Solution Approach 1:
The high turbulence flow creates intense mechanical agitation and vortex patterns that enhance mass transfer between the liquid and steel surface. This mechanical action accelerates oxide removal by continuously renewing the acid solution at the steel surface and disrupting the protective oxide layers more effectively than conventional stagnant or slow-flow pickling methods, thereby reducing required pickling time while maintaining quality.
Solution Approach 2:
The patent implements a continuous high-turbulence flow system where fresh pickling liquor is constantly supplied and circulated through the treatment zone. This continuous renewal of highly active acid solution at the steel surface maintains maximum pickling effectiveness throughout the process, eliminating the need for prolonged exposure times required by batch or intermittent pickling methods.
3Ease of operation
If conventional acid concentration and temperature are used, then pickling process is simple to operate, but oxide dissolution rate is limited
Solution Approach 1:
The patent modifies key parameters of the pickling process by increasing the turbulence intensity and flow velocity of the pickling liquor to extreme levels. By changing the hydrodynamic conditions from conventional low-turbulence flow to high-turbulence flow with specific velocity ranges (0.5-2.0 m/s), the pickling rate is dramatically increased, allowing faster processing while maintaining effective oxide removal.
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 approach significantly reduces pickling time by increasing the turbulence of the acid solution and incorporating mechanical action from abrasive particles, effectively removing hard-to-remove oxides like fayalite, thereby improving the overall efficiency and speed of the pickling process.
Implementation Method 1
Pickling of a steel strip is a chemical process based on the dissolution of oxides in acid (with HCl concentration usually between 30 and 180 g/l)
Implementation Method 2
increasing turbulence to refresh more rapidly the free acid in the electric double layer directly increases the pickling process efficiency
Data Source
Figure 1
Figure 2A~2C
Figure 3
AI summary
The present invention relates to a pickling installation for applying a pickling treatment to a steel strip (10) in continuous movement, said pickling treatment using an acid solution possibly containing abrasive particles, wherein, in a first treatment tank configuration (1A), each of the first header (2A) and the second header (2B) have an internal flat surface (6) intended to be parallel respectively to the first and second faces of metal strip (10), and at a distance thereof, defining a first gap (5A) and a second gap (5B) respectively, said first header (2A) and said second header (2B) comprising each a plurality of holes (3) drilled through the internal flat surface (6) according to a defined 2D-pattern, for spraying the acid solution to the metal strip (10) in straight jets (4), under conditions suitable to create in use at the surface of the metal strip (10) a highly turbulent liquid cushion (5').