Baffle Tower Coal Drying Inert Atmosphere VOC Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current coal upgrading technologies face challenges in efficiently drying coal while minimizing volatile organic compound (VOC) liberation, achieving consistent product quality, and reducing environmental and operational costs, particularly when processing low-rank coals, due to issues with dustiness, spontaneous ignition, bulk density, and high maintenance requirements.
Innovation Solution
The apparatus comprises a baffle tower with alternating rows of inverted v-shaped baffles, a coal intake bin, and cooling augers, which allows for controlled drying and mixing of coal with process gas, ensuring even gas-to-solids contact and minimizing VOC evolution, while maintaining a closed system for efficient coal upgrading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If coal is dried using conventional technologies, then moisture content is reduced and apparent rank increases, but volatile organic compound liberation increases and environmental compliance costs increase
Solution Approach 1:
The patent uses an inert atmosphere (nitrogen or carbon dioxide) to displace oxygen during the drying process, preventing oxidation and reducing volatile organic compound liberation. The inert gas is circulated through the coal bed at controlled rates to remove moisture while maintaining an oxygen-free environment that minimizes harmful emissions.
Solution Approach 2:
The patent implements continuous drying operation where inert gas is continuously circulated through the coal bed over extended periods (days to weeks). This continuous action allows thorough moisture removal while maintaining controlled conditions that prevent VOC liberation, unlike batch or intermittent processes.
2Reliability
If high-grade compliance coals are used to meet optimal operational specifications, then combustion efficiency is maintained, but capital costs for plant refitting or new plant construction increase
Solution Approach 1:
The patent changes the physical and chemical parameters of low-rank coal through controlled drying, reducing moisture content and increasing apparent rank. This transforms the coal's properties to meet combustion specifications without requiring expensive plant modifications or new construction, thereby maintaining combustion efficiency while avoiding capital costs.
Solution Approach 2:
The patent uses an intermediary processing step (inert atmosphere drying) between coal mining and combustion. This intermediary process upgrades low-rank coal to meet high-grade specifications, serving as a mediator that eliminates the need for expensive direct plant modifications or new construction.
3Ease of manufacture
If low-rank coals are used without alteration, then capital investment is minimized, but productive capacity of existing power plant facilities is reduced
Solution Approach 1:
The patent applies parameter changes (moisture reduction, apparent rank increase) to low-rank coal through inert atmosphere drying, enabling the coal to be used in existing power plant facilities without capital investment while maintaining or improving productive capacity. The transformed coal meets combustion specifications that allow full utilization of existing facilities.
4Ease of operation
If lower rank coals are burned without upgrading, then operational simplicity is maintained, but efficiency of the combustion system is reduced and hazardous pollutant quantities increase
Solution Approach 1:
The patent performs preliminary action by drying and upgrading the coal before combustion. The inert atmosphere drying process pre-treats low-rank coal to reduce moisture and increase apparent rank, so that the coal is ready for efficient combustion without requiring complex combustion system modifications or operational changes.
5Device complexity
If mineral impurities are not removed from coal, then processing complexity is minimized, but quantities of sulfur dioxide, particulates and other pollutants increase
Solution Approach 1:
The patent uses an inert atmosphere during drying to prevent oxidation of mineral impurities and reduce the formation of sulfur dioxide and other pollutants. The nitrogen or carbon dioxide environment prevents chemical reactions that would generate harmful emissions, allowing coal with mineral impurities to be processed without complex pollution control systems.
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 enables coal to be dried at a controlled rate, reducing VOC liberation, maintaining product quality, and enhancing cleaning efficiency, with lower operational and environmental impacts, and allows for the processing of coal without significant size reduction, thus addressing the limitations of existing technologies.
Implementation Method 1
process gas enters the baffle tower from the inlet plenum via baffle holes in one of the side walls of the baffle tower; wherein the process gas dries the coal that enters the baffle tower
Implementation Method 2
the dried coal from the baffle tower is mixed with non-dried coal from the coal intake tubing in the cooling augers
Implementation Method 3
baffle tower with alternating rows of inverted v-shaped baffles, a coal intake bin, and cooling augers, which allows for controlled drying and mixing of coal with process gas, ensuring even gas-to-solids contact and minimizing VOC evolution
Data Source
AI summary
A method for using an apparatus for upgrading coal comprising a baffle tower, inlet and exhaust plenums, and one or more cooling augers. The baffle tower comprises a plurality of alternating rows of inverted v-shaped inlet and outlet baffles. The inlet and outlet plenums are affixed to side walls of the baffle tower. Process gas enters the baffle tower from the inlet plenum via baffle holes in the side wall and dries the coal in the baffle tower. Process exhaust gas exits the baffle tower into the exhaust plenum via baffle holes in a different side wall of the baffle tower. Coal that outers the baffle tower descends by gravity downward through the baffle tower and enters a cooling auger, where the dried coal from the baffle tower is mixed with non-dried coal.