Heat Treatment Furnace Carbon Potential Control
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Solution Overview
Problem
Conventional heat treatment furnaces experience significant drops in carbon potential (CP) due to air entering when the furnace is opened or closed, leading to unstable control responses, overshooting, and prolonged times to reach target values during carburization processes.
Innovation Solution
A heat treatment method and apparatus that involves controlling the supply flow rates of transforming gas and enriched gas within the furnace, including stopping feedback control during furnace opening and closing, and increasing the supply flow rates of these gases to maintain stable carbon potential, thereby preventing CP disturbances and ensuring efficient carburization treatment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is continuously performed during furnace opening/closing, then carbon potential can be maintained, but control response becomes unstable and causes overshooting
Solution Approach 1:
The control system performs preliminary actions by stopping feedback control before the furnace opening is fully opened and before the atmosphere outside begins to flow into the furnace. This prevents the control system from reacting to transient conditions caused by opening/closing operations, thereby avoiding overshooting and instability while maintaining carbon potential stability during normal operation.
2Ease of operation
If furnace opening is opened for carrying workpiece in or out, then workpiece handling is enabled, but air enters and decreases carbon potential largely
Solution Approach 1:
The system increases the supply flow rate of transforming gas before the furnace opening is opened and maintains this increased flow rate after closing. This preliminary preparation ensures that when the opening is opened for workpiece handling, the carbon potential is already protected from significant drops, allowing easy workpiece handling without compromising carbon potential stability.
Solution Approach 2:
The transforming gas acts as an intermediary substance that compensates for the harmful effect of air entering during furnace opening. By increasing its supply flow rate, the system creates a protective atmosphere that prevents direct contact between air and the workpiece, thereby maintaining carbon potential stability during necessary opening operations for workpiece handling.
3Reliability
If supply flow rate of transforming gas is increased to prevent CP decrease, then carbon potential stability improves, but gas consumption increases
Solution Approach 1:
The system dynamically adjusts the supply flow rate of transforming gas based on the operational state of the furnace opening. The flow rate is increased before and after opening/closing operations when carbon potential is at risk, and returned to normal levels when the furnace is closed and stable. This dynamic adjustment maintains carbon potential stability while minimizing unnecessary gas consumption during normal 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 approach effectively stabilizes carbon potential inside the furnace, preventing CP drops and maintaining stable control, which enhances the efficiency and reliability of carburization treatments by preventing CP instability and ensuring consistent carbon concentration in treated steel products.
Implementation Method 1
controlling CP (carbon potential) in a heat treatment atmosphere... based on CP during carburization heat treatment
Implementation Method 2
feedback control such as proportional control, PID control or the like
Data Source
AI summary
In a heat treatment method for supplying transforming gas and enriched gas inside a furnace and heat treating a workpiece inside the furnace, feedback control of carbon potential is performed by operating a supply flow rate of the enriched gas based on carbon potential inside the furnace, the feedback control is stopped before an opening of the furnace is opened and supply flow rates of the transforming gas and the enriched gas are increased from supply flow rates thereof immediately before the feedback control is stopped; and the supply flow rate of the transforming gas is returned to the supply flow rate thereof immediately before the feedback control is stopped and the feedback control is resumed after the opening of the furnace is closed.