Water Injection Cooling for Pulverized Coal Drying
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Solution Overview
Problem
Existing grinding and drying installations for pulverized coal production in the metallurgical industry face issues with unscheduled process stoppages and production losses due to temperature fluctuations during startup phases, leading to suboptimal drying and the production of unusable coal slurry.
Innovation Solution
The method involves controlling the temperature of the drying gas by adjusting the volume of water injected into the gas upstream of the pulverizer, allowing for rapid temperature adjustments during startup and normal operation to maintain consistent exit temperatures, thereby reducing transition times and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the emergency cooling system is activated to cool the gas when temperature exceeds threshold, then the filter is protected from damage, but the grinding and drying installation is shut down causing production loss
Solution Approach 1:
A water injection system is introduced as an intermediary cooling mechanism between the pulverizer and filter. This system allows for rapid temperature reduction of the drying gas without requiring shutdown of the entire installation, thus protecting the filter while maintaining production continuity
Solution Approach 2:
The water injection rate is dynamically adjusted based on real-time temperature measurements at the pulverizer outlet. This dynamic control enables the system to respond quickly to temperature fluctuations and maintain operation within safe parameters without unnecessary shutdowns
2Temperature
If gas is fed through the system before raw coal is introduced to heat components, then the installation reaches working temperature, but the transition time causes production of unusable coal slurry
Solution Approach 1:
The system performs preliminary heating of the drying gas and components before raw coal introduction, but now with controlled water injection ready to immediately compensate for temperature drops, reducing the unproductive transition period
Solution Approach 2:
A feedback control system continuously monitors the temperature at the pulverizer outlet and automatically adjusts the water injection rate to maintain optimal drying temperature, eliminating the prolonged transition period where temperature is too low for effective drying
3Temperature
If water is injected to cool the gas rapidly, then temperature control is improved, but energy consumption increases
Solution Approach 1:
The system changes the thermal parameters of the drying gas by injecting water, which absorbs excess heat through evaporation. This provides rapid cooling with lower energy input compared to mechanical cooling systems
Solution Approach 2:
The water injection converts the harmful effect of excess heat into a beneficial cooling mechanism. The evaporation of water absorbs heat that would otherwise damage the filter, transforming a potential problem into an effective and energy-efficient cooling solution
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 the production of unusable coal slurry and enhances the efficiency of the grinding and drying installation by minimizing downtime and maintaining consistent pulverized coal quality.
Implementation Method 1
controlling an exit temperature of the mixture of drying gas and pulverized coal exiting the pulverizer by controlling a volume of water injected into the heated drying gas before feeding it into the pulverizer
Data Source
AI summary
Method for producing pulverized coal, the method comprising the steps of heating a drying gas, preferably an inert gas, in a hot gas generator (26) to a predefined temperature; feeding the heated drying gas into a pulverizer (20); introducing raw coal into the pulverizer (20), the pulverizer (20) grinding the raw coal to pulverized coal; collecting a mixture of drying gas and pulverized coal from the pulverizer (20) and feeding the mixture to a filter (34), the filter (34) separating the dried pulverized coal from the drying gas; and collecting the dried pulverized coal for further use and feeding part of the drying gas from the filter to a recirculation line (38) for returning at least part of the drying gas to the hot gas generator (26). According to an important aspect of the present invention, the method comprises the further step of controlling an exit temperature of the mixture of drying gas and pulverized coal exiting the pulverizer (20) by controlling a volume of water injected into the heated drying gas before feeding it into the pulverizer (20).