Lignite Upgrading via Sequential Dry Sorting and Drying
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Solution Overview
Problem
Current methods for upgrading lignite face challenges such as high energy consumption, unstable interfaces after drying, easy re-adsorption of water, and inability to achieve both deashing and sorting efficiently, particularly due to lignite's high moisture content and low calorific value, which complicates its use and storage.
Innovation Solution
A collaborative optimization process that first applies dry sorting to reduce ash content and then drying, using relational expressions to assess calorific value and production cost, and selecting appropriate equipment like X-ray, composite, or fluidized-bed dry sorting and drying methods to achieve efficient lignite upgrading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If wet sorting process is used to upgrade lignite, then deashing can be achieved, but drying cannot be achieved and operation becomes complicated with high energy consumption
Solution Approach 1:
The upgrading process is segmented into two independent stages: dry sorting for deashing followed by drying for moisture removal. This segmentation allows each process to be optimized independently, avoiding the complexity of combined wet sorting and drying operations while achieving both deashing and drying objectives efficiently
Solution Approach 2:
The conventional sequence of drying first then sorting is inverted to sorting first then drying. This inversion is crucial because lignite degrades in water, making dry sorting necessary before any moisture removal. The inverted sequence simplifies operation by eliminating the need for wet sorting followed by drying, directly achieving both deashing and drying in a straightforward two-stage process
2Loss of substance
If dry sorting is used to remove ash from lignite, then deashing can be achieved, but the process requires strict control of surface moisture
Solution Approach 1:
A preliminary drying stage is implemented before dry sorting to reduce surface moisture to the required level. This preliminary action prepares the lignite for effective dry sorting by ensuring surface moisture is sufficiently low, thereby achieving deashing without the need for strict continuous moisture control during sorting
Solution Approach 2:
The preliminary drying process acts as an intermediary between the raw lignite and the dry sorting process. It mediates the moisture content to an optimal range that enables effective dry sorting while simplifying operational requirements, bridging the gap between high initial moisture and the strict moisture requirements of dry sorting
3Quantity of substance
If single drying process is applied to lignite, then partial water removal can be achieved, but energy consumption is high and re-adsorption occurs
Solution Approach 1:
The drying process is segmented into multiple stages with different drying intensities and methods. This includes preliminary drying before sorting and final drying after sorting, allowing moisture removal to be achieved in steps rather than a single high-energy process, thereby reducing overall energy consumption while preventing re-adsorption through proper sequencing
Solution Approach 2:
The drying action continues throughout the entire upgrading process rather than being a separate post-processing step. Drying occurs before sorting, after sorting, and is integrated into the workflow, ensuring continuous moisture removal that prevents re-adsorption and achieves thorough drying without excessive energy consumption
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 process simplifies operations, reduces energy consumption and production costs, enhances lignite quality by effectively removing moisture and ash, and increases calorific value, resulting in improved coal quality and economic benefits.
Implementation Method 1
first feeding the lignite to X-ray dry sorting equipment, composite dry sorting equipment or fluidized-bed equipment for initial gangue removal
Implementation Method 2
X-ray dry sorting equipment... for initial gangue removal to remove gangue partially
Implementation Method 3
allowing the lignite after the gangue removal to enter microwave, vibrating mixed-flow or fluidized-bed equipment for drying
Implementation Method 4
The water on the surface of lignite is easily affected by temperature, so after the coal enters the drying equipment, the free water on the surface of the lignite is quickly removed
Implementation Method 5
allowing the lignite after the gangue removal to enter microwave, vibrating mixed-flow or fluidized-bed equipment for drying
Implementation Method 6
allowing the lignite after the gangue removal to enter microwave, vibrating mixed-flow or fluidized-bed equipment for drying
Data Source
AI summary
The present invention is directed towards a process for upgrading lignite comprising: prior to production pre-assess the calorific value of the coal, by selecting a relational expression between a calorific value of lignite and a degree of metamorphism, a moisture content and an ash content thereof based on a ratio of the ash content to the moisture content, pre-assess the calorific value of the coal; combining a relational expression between a production cost and the ash content and moisture content to make a cost budget; determining degrees of deashing and drying; selecting and implementing a lignite ash reduction pretreatment process; and implementing dry sorting first and then drying. The upgrading process has high sorting efficiency, high drying efficiency and low production cost, and meets the requirement for the surface moisture of the raw coal in the dry sorting operation.