Dry Centrifugal Slag Granulation Cooling Control
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Solution Overview
Problem
Current dry centrifugal granulation of liquid blast furnace slag faces challenges in maintaining the rotating shaft temperature within a safe range, achieving uniform particle diameter distribution, and effectively handling accidents during the granulation process, leading to inefficiencies and potential equipment damage.
Innovation Solution
A control system comprising a granulator cold-air control unit and a feeding unit, which includes temperature measurement components, a cold-air supply system, and an accident diversion spout, allows for precise temperature control of the rotating shaft, adjustment of particle diameter, and safe handling of non-granulated slag during accidents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the liquid slag temperature is maintained high for efficient granulation, then the granulation effectiveness is improved, but the rotating shaft temperature increases causing equipment damage risk
Solution Approach 1:
The cooling system is segmented into multiple independent cooling air channels, each equipped with separate control valves. This allows differential cooling control - more cooling air to the rotating shaft and less to the granulator body, enabling the granulator to maintain high temperature for effective granulation while the rotating shaft is kept at safe operating temperatures through targeted cooling
Solution Approach 2:
Different regions of the system are assigned different thermal characteristics. The granulator body is designed to retain heat for optimal granulation, while the rotating shaft receives concentrated cooling air supply through dedicated cooling channels. This local quality differentiation allows the system to simultaneously maintain high temperature zones for productivity and low temperature zones for reliability
2Productivity
If the motor power is increased to enhance granulation capability, then the granulation productivity is improved, but the rotating shaft temperature increases further
Solution Approach 1:
Cooling air is supplied to the rotating shaft before it becomes overheated. The cooling channels are positioned to provide preemptive cooling, and the control system monitors temperature trends to increase cooling air flow in advance, preventing temperature buildup before it reaches critical levels even during high-power operation
Solution Approach 2:
Cooling air acts as an intermediary substance that transfers heat away from the rotating shaft. The cooling air channels serve as intermediary pathways that allow thermal energy to be removed from the system without directly cooling the granulation zone, enabling the motor to operate at high power while the shaft temperature is controlled through this thermal intermediary
3Productivity
If the granulator speed is increased to improve granulation efficiency, then the productivity is improved, but the particle diameter distribution becomes less uniform
Solution Approach 1:
The system dynamically adjusts operating parameters based on real-time conditions. The motor speed can be varied within a range to optimize both productivity and particle uniformity, and the cooling air flow rates are dynamically controlled based on temperature feedback. This dynamic adjustment capability allows the system to maintain optimal performance across varying production rates
4Temperature
If water quenching is used to cool the liquid slag, then the cooling efficiency is improved, but water resource waste and harmful gas emission increase
Solution Approach 1:
The patent replaces the water-based cooling system with an air-based cooling system. Instead of using water quenching that causes vapor generation and water loss, the system uses controlled air flow through cooling channels to remove heat from the rotating shaft and granulator body, eliminating the harmful effects associated with water consumption and vapor emission while maintaining effective cooling
Solution Approach 2:
The system uses air as the cooling medium, creating an inert atmosphere that prevents the chemical reactions and vapor generation associated with water quenching. The air cooling channels provide a controlled environment for heat removal without introducing water into the high-temperature slag environment, thereby preventing harmful gas emissions and water resource waste
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
The system ensures stable operation, optimal granulation, and efficient waste heat recovery by maintaining the rotating shaft temperature and particle diameter within desired ranges, while providing a safe and efficient method for handling accidents, reducing equipment damage and operational risks.
Implementation Method 1
the small droplets make a forced convection heat transfer with the heat transfer medium (generally being air) in the space, for realizing the radiation heat transfer with the ambient environment
Implementation Method 2
the small droplets make a forced convection heat transfer with the heat transfer medium (generally being air) in the space, for realizing the radiation heat transfer with the ambient environment
Implementation Method 3
the temperature of the small droplets rapidly decreases and a phase change happens, thereby forming the solidified layer
Implementation Method 4
the liquid slag drops to the surface of the rotary table which rotates in a high speed, and then is spun out under the effects of centrifugal force and friction force
Implementation Method 5
small droplets are formed under the effect of the surface tension of the liquid slag
Data Source
AI summary
A control system and method for dry centrifugal granulation of liquid slag are provided. The control system includes a granulator cold-air control unit and a feeding unit. The granulator cold-air control unit includes a granulator, a rotating shaft, a motor, and a cold-air supply unit. The granulator is fixed to the motor; the cold-air supply unit includes a shaft cooling air channel and an annular cooling air channel; the shaft cooling air channel consists of an inner duct sleeve and a shaft sleeve; the annular cooling air channel consists of the inner duct sleeve and an outer duct sleeve arranged at periphery of the inner duct sleeve, which have different external diameters; the feeding unit includes a slag dropping pipe arranged above the granulator; a sliding gate is arranged at a lower section of the slag dropping pipe, and an accident diversion spout is equipped.