Staged Coal Solvent Extraction for Longer Residence Time
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Solution Overview
Problem
Conventional solvent extraction of coal is limited by short coal residence times in the extraction reactor, leading to low yields and unsatisfactory extract characteristics, and is not continuous, resulting in inefficiencies and low conversion to desirable products.
Innovation Solution
A continuous-flow extraction apparatus with a scaffolded stationary assembly and rotating stir shaft assembly, featuring horizontal plates that divide the reactor into stages with periodic alignment of openings, combined with agitators to promote coal-solvent contact and decouple mixing from settling, allowing extended coal residence times up to 4 hours or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional solvent extraction techniques are used with short coal residence times (1 hour or less), then the extraction process is faster, but the yields of extracts are very low and the extracts do not meet specifications
Solution Approach 1:
The extraction reactor is divided into multiple stages with stationary plates and rotatable plates creating distinct zones. Coal slurry flows through openings in these plates, allowing segmented contact with solvent across different stages, which extends residence time while maintaining continuous operation.
Solution Approach 2:
The system employs rotatable plates with openings that can rotate to different positions, dynamically controlling the flow path and residence time of coal slurry. This dynamic adjustment allows optimization between extraction efficiency and processing speed.
2Device complexity
If conventional semi-batch extraction is used, then the equipment complexity is lower, but the process efficiency and conversion to desirable products are low
Solution Approach 1:
The system is designed for continuous counter-current extraction where coal slurry continuously flows through the staged reactor while solvent is introduced at the bottom and flows upward. This continuous operation eliminates idle periods between batches and maximizes conversion efficiency.
Solution Approach 2:
The rotatable plates with adjustable openings provide dynamic control over the extraction process, allowing optimization of residence time and contact efficiency without requiring complex batch operation procedures.
3Speed
If short coal residence times are used, then the processing speed is higher, but the characteristics of extracts do not meet specifications such as asphalt additive specifications
Solution Approach 1:
The multi-stage reactor with stationary and rotatable plates creates segmented extraction zones that progressively treat the coal slurry. This segmentation allows controlled extension of residence time through each stage, ensuring extract characteristics meet specifications while maintaining overall processing speed.
Solution Approach 2:
The rotatable plates can be rotated periodically to adjust opening positions, creating periodic variations in flow patterns that enhance mass transfer and extraction efficiency, ensuring consistent product quality.
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 apparatus enables higher yields and enhanced characteristics of coal extracts by allowing longer residence times, improving the extraction of volatiles and other products, and facilitating continuous counter-current extraction.
Implementation Method 1
coal particles pass through the openings in the stationary members and the openings in the rotatable members as the openings in the rotatable members rotate into alignment with the openings in the stationary members
Implementation Method 2
The apparatus further includes a plurality of members for agitating materials passing through the apparatus, the members for agitating materials coupled to the rotatable shaft
Implementation Method 3
Coal is utilized in industry as both a fuel and as a source of chemicals. Such fuels and chemicals can be produced from coal by coal liquefaction or solvent extraction. Coal liquefaction and solvent extraction rely on tetralin or aromatic oils to react with the coal macrostructure to break it down into smaller molecules.
Data Source
AI summary
Embodiments of the present disclosure generally relate to apparatus for solvent extraction of coal and to processes for solvent extraction of coal. In an embodiment, an apparatus for solvent extraction of coal is provided. The apparatus includes a plurality of stationary members coupled to a stationary shaft, each stationary member having a stationary member opening. The apparatus further includes a rotatable shaft extending through the plurality of stationary members. The apparatus further includes a plurality of rotatable members coupled to the rotatable shaft, each rotatable member paired with a stationary member, and each rotatable member has a rotatable member opening configured to rotate relative to the stationary member opening. The apparatus further includes a plurality of members for agitating materials passing through the apparatus, the members for agitating materials coupled to the rotatable shaft, each member for agitating materials positioned between the paired stationary members and rotatable members.