Blast Furnace Response Control for Temperature and Output Stability
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Solution Overview
Problem
In the blast furnace process, controlling hot metal temperature while maintaining pig iron producing speed at or near the target value is challenging due to variations in reducing material ratios, particularly when increasing the pulverized coal ratio, which affects the burning velocity of coke and descending raw material velocity.
Innovation Solution
A method that calculates free responses, first responses, and second responses of control variables to determine operation amounts of manipulated variables such as coke ratio, blast volume, and pulverized coal flow rate to maintain predetermined target values for hot metal temperature and pig iron producing speed, using a dynamic model that accounts for physical phenomena like iron ore reduction and heat exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pulverized coal ratio is increased to control hot metal temperature, then fuel cost is reduced, but the burning velocity of coke decreases and pig iron producing speed decreases
Solution Approach 1:
The patent calculates free responses and step responses in advance to predict future furnace heat and control variable behavior. By performing these calculations beforehand, the system can determine optimal manipulated variable operations that maintain pig iron producing speed while controlling hot metal temperature, even when pulverized coal ratio is increased.
Solution Approach 2:
The patent dynamically adjusts manipulated variables (coke ratio, blast volume, pulverized coal flow rate) based on calculated responses and predicted furnace heat. This dynamic adjustment allows the system to maintain productivity while controlling temperature variations caused by changing reducing material ratios.
2Temperature
If the reducing material ratio is adjusted to control hot metal temperature, then temperature control is achieved, but pig iron producing speed varies from target value
Solution Approach 1:
The patent uses calculated free responses and step responses to predict how control variables will respond to manipulated variable changes. This predictive feedback mechanism allows the system to adjust manipulated variables to maintain both hot metal temperature and pig iron producing speed at target values simultaneously.
Solution Approach 2:
The patent changes multiple parameters (coke ratio, blast volume, pulverized coal flow rate) in a coordinated manner based on calculated responses. By adjusting these parameters together rather than individually, the system can control hot metal temperature while maintaining pig iron producing speed at the target value.
3Temperature
If multiple manipulated variables are changed simultaneously to control hot metal temperature, then temperature control improves, but control complexity increases
Solution Approach 1:
The patent segments the control problem into distinct response calculations: free response (when all manipulated variables are constant), first response (when one manipulated variable changes), and second response (when two manipulated variables change simultaneously). This segmentation simplifies the complex control problem into manageable calculation components.
Data Source
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AI summary
A method of controlling a process includes a free response calculating step that calculates free responses in a case where operation amounts of all manipulated variables are constant for a predetermined period from a current time, a first response calculating step that calculates first responses in a case where an operation amount of a first manipulated variable among the manipulated variables is changed in step for the predetermined period, a second response calculating step that calculates second responses in a case where an operation amount of a second manipulated variable other than the first manipulated variable among the manipulated variables is changed in step simultaneously with the operation amount of the first manipulated variable for the predetermined period, and an operation amount determining step that determines the operation amounts of the manipulated variables in accordance with the free responses, the first responses, and the second responses.