Fluidized Bed Coal Cleaning for Sulfur and Mercury Removal
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Solution Overview
Problem
Current methods for separating coal particles with organic sulfur from those largely free of sulfur are inefficient due to similar specific gravities, and existing scrubber technologies are costly and not effective for all coal ranks, especially for removing mercury, which requires pre-combustion thermal processes that are capital intensive and leave residual mercury in coal.
Innovation Solution
A fluidized bed system with a scrubber assembly that uses a conveyor to process coal at low temperatures without mechanical or chemical additives, separating denser and larger contaminants like sulfur and mercury by density and size, allowing for continuous processing and further separation of non-contaminated particulates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional washing devices using water and specific gravity separation are used, then coal particles can be cleaned to remove ash, but organic sulfur cannot be effectively removed because it is closely bound to carbon and has similar specific gravity
Solution Approach 1:
The invention changes the separation parameter from specific gravity (conventional washing) to particle size and density differentiation through fluidized bed aeration. By controlling air flow rates and fluidization conditions, the system separates fine particulate sulfur from larger coal particles, achieving effective sulfur removal that conventional water-based washing cannot accomplish due to similar specific gravities.
Solution Approach 2:
The invention replaces the mechanical water-based washing system with a pneumatic fluidized bed system. Instead of using water density differences for separation, the system uses upward air flow to fluidize the coal particles, allowing finer sulfur-containing particulates to be carried away while heavier coal particles remain in the bed, achieving separation based on aerodynamic properties rather than specific gravity.
2Reliability
If pre-combustion thermal processes are used to remove mercury, then mercury levels can be reduced, but the process is capital intensive and leaves residual mercury in coal
Solution Approach 1:
The invention extracts mercury and other contaminants from coal during the fluidized bed processing stage, before combustion. By using controlled aeration and fluidization, volatile contaminants including mercury are separated and removed with the fine particulate matter, eliminating the need for separate pre-combustion thermal treatment processes and reducing both complexity and capital requirements.
Solution Approach 2:
The invention combines the sulfur removal function with mercury and other contaminant removal in a single fluidized bed processing step. Instead of requiring separate thermal processes for different contaminants, the unified fluidized bed system simultaneously separates all fine particulate contaminants including sulfur, mercury, and ash, simplifying the overall process while achieving comprehensive purification.
3Object-affected harmful factors
If expensive scrubber technologies are installed post-combustion to prevent pollution, then SO2, NOx, and fly ash can be controlled, but the cost is high and effectiveness varies by coal rank
Solution Approach 1:
The invention performs preliminary removal of sulfur, mercury, and other contaminants from coal before combustion through fluidized bed processing. By eliminating sulfur and other harmful constituents upfront, the system prevents formation of SO2, NOx, and fly ash at the source, eliminating or reducing the need for post-combustion scrubber technologies and associated costs, while improving effectiveness across all coal ranks.
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 method effectively separates coal contaminants by density and size, reducing the need for expensive scrubber technologies post-combustion and enhancing coal processing efficiency while minimizing residual mercury and sulfur levels in coal.
Implementation Method 1
The material mixture travels along a downwardly sloped screen support and is suspended by upwardly directed pneumatic pulses
Implementation Method 2
upwardly directed pneumatic pulses
Implementation Method 3
A conveyor is operatively disposed in the fluidized bed for conveying the non-fluidized particulate to the non-fluidized particulate exit
Implementation Method 4
separating denser and larger material containing contaminants or other undesirable constituents from the rest of the coal or other organic material
Implementation Method 5
concentrating the denser and/or larger material for removal and further processing or disposal
Data Source
AI summary
An apparatus for segregating particulate by density and/or size including a fluidizing bed having a particulate receiving inlet for receiving particulate to be fluidized. The fluidized bed also includes an opening for receiving a first fluidizing stream, an exit for fluidized particulate and at least one exit for non-fluidized particulate. A conveyor is operatively disposed in the fluidized bed for conveying the non-fluidized particulate to the non-fluidized particulate exit. A collector box is in operative communication with the fluidized bed to receive the non-fluidized particulate. There is a means for directing a second fluidizing stream through the non-fluidized particulate as while it is in the collector box to separate fluidizable particulate therefrom.