Microwave Pyrolysis of Non-Coking Coal Pellets
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Solution Overview
Problem
Conventional methods for producing metallurgical coke from non-coking coal are inefficient and costly due to high energy consumption and the need for susceptors to enhance microwave absorption, making them uneconomical for large-scale production.
Innovation Solution
A method involving the densification of non-coking coal into pellets, which are then heated in a microwave oven under an inert atmosphere without susceptors, allowing for pyrolysis and conversion to metallurgical coke with reduced power usage and processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional microwave coking methods are used with susceptors, then microwave absorption is enhanced and operating temperatures are increased, but energy consumption increases and operating costs increase
Solution Approach 1:
The patent introduces a susceptor-free approach where the coal matrix itself is modified through pre-treatment processes (crushing, screening, and blending with specific coal types) to enhance its intrinsic microwave absorption capabilities. This eliminates the need for external susceptor materials while achieving effective microwave heating at required temperatures for metallurgical coke production.
Solution Approach 2:
The patent modifies the physical and chemical parameters of the coal feedstock through pre-treatment processes, including size reduction to specific particle size ranges (0.5-10mm), blending ratios of different coal types, and moisture content control. These parameter changes optimize the coal matrix's dielectric properties for direct microwave absorption without susceptors, reducing energy consumption while maintaining effective heating.
2Adaptability or versatility
If low rank coal is used to produce metallurgical coke, then non-coking coal availability is improved, but heating duration must be extended to over an hour and power requirements increase to 8 kW and above
Solution Approach 1:
The patent applies pre-treatment processes to the low rank coal before microwave heating, including crushing to specific particle sizes, screening to remove fines, and blending with coking coal in optimized ratios. These preliminary actions prepare the coal matrix to achieve effective microwave absorption and rapid heating, reducing the heating duration from over an hour to significantly shorter times while maintaining coke quality.
Solution Approach 2:
The patent creates a composite coal matrix by blending low rank non-coking coal with coking coal in specific ratios. This composite approach combines the advantages of both coal types: the abundance and cost-effectiveness of non-coking coal with the caking and structural properties of coking coal, enabling successful metallurgical coke production from low rank coal with reduced heating time.
3Speed
If rapid heating with microwaves is applied to non-coking coal, then heating rate is increased to 30-35°C/min, but process complexity increases with multiple heating and loading steps
Solution Approach 1:
The patent combines multiple process steps into a more integrated flow: pre-treatment (crushing and screening) is followed by direct microwave heating in a single continuous process. The optimized coal matrix formulation allows rapid heating at 30-35°C/min to be achieved without requiring separate susceptor addition steps, multiple loading/unloading cycles, or complex temperature control sequences, thereby reducing overall process complexity while maintaining high heating rates.
4Reliability
If conventional coking coal is used, then coke quality is maintained, but availability is limited and costs increase due to scarcity
Solution Approach 1:
The patent modifies the coal matrix parameters through pre-treatment processes and optimized blending ratios to compensate for the inferior properties of non-coking coal. By controlling particle size distribution, moisture content, and blend composition, the coal matrix is transformed to achieve effective microwave absorption and produce coke with quality comparable to conventional coking coal, thereby expanding coal availability while maintaining product reliability.
Solution Approach 2:
The optimized coal matrix formulation acts as an intermediary that bridges the gap between non-coking coal and traditional coking coal requirements. Through specific blending ratios and pre-treatment, the matrix properties are adjusted to enable non-coking coal to fulfill the structural and chemical requirements for metallurgical coke production, effectively substituting scarce coking coal with abundant non-coking coal resources.
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 produces metallurgical coke with desired properties for use in blast furnaces, reducing energy consumption and processing time while eliminating the need for susceptors, thereby improving the economic viability of coke production.
Implementation Method 1
heating the pellets in a microwave oven at a predetermined temperature under an inert atmosphere at atmospheric pressure, wherein the pellets undergo pyrolysis during the heating
Implementation Method 2
wherein the pellets undergo pyrolysis during the heating
Data Source
AI summary
The present disclosure relates to a method for producing metallurgical coke from non-coking coal. The method comprising, densifying, the non-coking coal to form pellets. The densified pellets will be placed in a microwave oven within plurality of bricks and are subjected for pyrolysis. For carrying our pyrolysis, the pellets are carried out by heating, the pellets in the microwave oven at a predetermined temperature under an inert atmosphere at atmospheric pressure, and then the pellets are cooled in the microwave oven under the inert atmosphere. This process coverts non-coking coal to the metallurgical coke in a quicker time, and without use of any susceptors.