Steel Ball Heat Transfer for Slag Granulation and Sludge Drying
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Solution Overview
Problem
Existing methods for treating blast furnace slag are inefficient in addressing the residual heat recovery and sludge drying, and the water quenching method cannot fundamentally change the water-consuming characteristic of the slag granulation process, leading to waste of high-quality residual heat, excessive water consumption, environmental pollution, and low recovery rate of the residual heat, and limited utilization of the recovered heat.
Innovation Solution
An integrated process for dry granulation of molten slag and drying of sludge using steel balls as a heat transfer medium, where high temperature molten slag is cooled and granulated, and the residual heat is used to dry sludge, forming a cyclic treatment system for efficient heat recovery and utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If water quenching method is used to cool and granulate blast furnace slag, then the slag can be rapidly cooled and transformed into water granulated slag for producing cement and other products, but a huge amount of water is consumed (0.8-1.2 tons of fresh water per ton of slag) and high-quality residual heat is wasted as water vapor is discharged into the atmosphere
Solution Approach 1:
The patent introduces air as an intermediary heat transfer medium between the molten slag and the environment. Instead of directly quenching slag with water, the hot slag is exposed to air cooling which reduces its temperature while recovering the residual heat. This intermediary approach allows for heat recovery before any potential water quenching, significantly reducing water consumption and energy waste.
Solution Approach 2:
The patent changes the thermal parameters of the slag by controlling the cooling process in stages. First, air cooling reduces the slag temperature from its initial high state (1350-1450°C) to a lower temperature range, recovering residual heat in the process. This parameter change approach allows optimization of both cooling efficiency and heat recovery, avoiding the extreme temperature drop that would waste energy.
2Productivity
If water quenching method is used to cool blast furnace slag, then the slag can be granulated efficiently, but the emission of SO2, H2S and other pollutants during the process pollutes the air and affects the working environment
Solution Approach 1:
The patent converts the harmful rapid cooling process into a beneficial controlled cooling process. By using air cooling instead of water quenching, the process eliminates the generation of harmful gases (SO2, H2S) that occur during water-slag reactions. The same cooling function is achieved without the harmful byproducts, turning a harmful process into a clean one.
3Loss of substance
If dry slag pit cooling method is used to cool molten slag, then water consumption is reduced, but the cooling process is slow and requires large cooling area, and harmful gases are still emitted during subsequent water cooling
Solution Approach 1:
The patent replaces the passive thermal conduction-based dry slag pit cooling with an active forced air cooling system. Instead of relying on natural heat dissipation through large slag piles, the system uses mechanical air circulation (fans, blowers) to actively remove heat from the slag. This substitution of cooling mechanism dramatically improves cooling efficiency while maintaining low water consumption, as the mechanical air flow can rapidly extract heat without requiring massive slag storage areas.
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 process effectively recovers and utilizes residual heat from molten slag for low-cost sludge drying, addressing the challenges of high water consumption and environmental pollution, while providing a stable and continuous treatment of both molten slag and sludge, enhancing the recovery rate of residual heat and expanding the treatment and resource utilization of urban sludge.
Implementation Method 1
the high temperature molten slag and steel balls are fully and evenly mixed and heat exchanged by tumbling the high temperature molten slag and steel balls
Implementation Method 2
the steel balls absorb heat from the high temperature molten slag
Implementation Method 3
the sludge drying device is driven by a driving device to rotate so that the sludge and steel balls in the sludge drying device tumble, and fully and evenly mix and exchange heat, whereby the sludge is dried by the steel balls having absorbed heat
Implementation Method 4
the sludge is dried by the steel balls having absorbed heat
Data Source
Figure 1~2
Figure 3~4
AI summary
An integrated drying process and device for dry granulated slag and sludge. The process comprises the following steps: 1) slag ball mixing and soaking: high-temperature slag and steel balls are fully mixed and exchange heat therebetween, the high-temperature slag is cooled because the heat thereof is quickly absorbed by the steel balls and is crushed to form granular slag, and the temperature of the steel balls rises because the steel balls absorb the heat of the high-temperature slag; and 2) sludge drying: the high-temperature steel balls are conveyed to a sludge drying device to be mixed with injected sludge, the sludge is dried, the steel balls are separated from the sludge when the water content of the sludge reaches a set value, and the steel balls and the sludge are separately discharged. In the present invention, high-temperature slag waste heat is used for heating steel balls, and sludge is dried by means of the heated steel balls, thus achieving the cooperative treatment of slag cooling, granulation and sludge drying, solving two difficult problems of slag cooling and sludge drying, and greatly increasing the waste heat recycling rate of high-temperature slag.