Coal Gasification Reactor with Segmented Zones
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Solution Overview
Problem
Existing gasification methods of coal-bearing raw materials often result in high tar content and inert components in the final gas, which hampers complete carbon conversion and efficient energy production.
Innovation Solution
The method involves a co-current system with alternating homogeneous and heterogeneous reaction zones, using steam, hydrocarbon vapors, and oxygen injections to maintain temperatures below 1000°C, promoting turbulent gas flow and continuous solid-phase contact to minimize tar production and maximize carbon conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional gasification methods are used, then gas production is achieved, but high tar content and inert components are produced which hamper complete carbon conversion
Solution Approach 1:
The gasification process is divided into multiple sequential zones (drying zone, pyrolysis zone, gasification zone, and combustion zone) arranged vertically in the shaft reactor. Each zone performs a specific function: drying removes moisture, pyrolysis decomposes organic matter, gasification converts carbon to syngas, and combustion provides heat. This segmentation allows optimized conditions in each zone, preventing tar formation while maximizing carbon conversion efficiency.
Solution Approach 2:
Different regions of the reactor are provided with locally optimized conditions: the lower zone maintains high temperature (800-1000°C) for complete gasification and combustion, while upper zones have progressively lower temperatures suitable for pyrolysis and drying. The gasifying agent distribution and solid fuel feeding rates are also locally adjusted to match the specific requirements of each zone, ensuring minimal tar production throughout the process.
2Productivity
If higher gasification temperatures are used, then carbon conversion efficiency improves, but sulphate reduction to sulphur dioxide increases
Solution Approach 1:
The process operates at an optimized temperature range of 800-1000°C in the gasification zone, which is sufficient for complete carbon conversion to syngas but below the threshold that causes extensive sulphate decomposition. The temperature profile is carefully controlled with a gradient from the combustion zone (highest temperature) to the drying zone (lowest temperature), maintaining conditions that favor carbon gasification while limiting sulphur transformation to harmful SO2.
3Object-generated harmful factors
If conventional counter-current gasification is used, then process simplicity is maintained, but tar content in the final gas remains high
Solution Approach 1:
The shaft reactor is divided into distinct functional zones with different operating conditions and gas-solids flow patterns. The drying zone operates with counter-current flow, the pyrolysis zone uses co-current flow, and the gasification zone employs a combination of both patterns. This segmentation of flow patterns within the vertical shaft allows tar minimization through optimized contact between gasifying agents and carbonaceous material at each stage, while maintaining a relatively simple overall reactor structure.
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 achieves virtually tar-free synthesis gas with high carbon conversion efficiency, reducing sulphate reduction and heavy metal vapor pressure, while utilizing lower gasification temperatures.
Implementation Method 1
gasification of carbonaceous material with the use of gasifying agents selected from the group consisting of steam, carbon dioxide, mixtures of steam and carbon dioxide, hydrocarbon vapours and mixtures thereof
Implementation Method 2
a shaft reactor equipped with means for introducing the gasifying agents and means for introducing solid fuel into the shaft reactor in a continuous manner
Implementation Method 3
drying zone, pyrolysis zone, gasification zone and combustion zone
Data Source
Figure 1~3
Figure 4
AI summary
A method of gasification according to the invention characterized by conducting it in a cocurrent system with an advantageously turbulent gas flow in alternating homogeneous 1 and heterogeneous 2 reaction zones with a mixture of steam, hydrocarbon vapours and/or combustible gases, with an oxygen or oxygen with steam injection into the homogeneous reaction zone. Fine-grained, preferably below 2 mm, degassed coal or coal-bearing material, as the feed, is mechanically distributed throughout the heterogeneous reaction zone, preferably with a set of helically fitted shelves, assuring the development of the contact surface of the dissipated solid phase with carbon dioxide and steam. The gas temperature between successive heterogeneous reaction zones is raised to a temperature of no higher than 1000°C via the oxygen or oxygen with steam injection, adjusted for each homogeneous reaction zone, while the gases from the homogeneous reaction zone are given an advantageous rotational motion when passing to the heterogeneous reaction zone.