Air Gasification Coal Process Eliminates Oxygen Separation
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Solution Overview
Problem
Current coal gasification processes in China face challenges such as low efficiency and high equipment costs due to the need for pure oxygen, limited coal type adaptability, and high ash and sulfur content in syngas, which hinder efficient and clean power generation.
Innovation Solution
A coal gasification process involving grading conversion of carbon hydrogen components, dividing coal into gasifying and heat-supplying coal, with processes including carbonization, carbon monoxide production, and shift reactions, eliminating the need for pure oxygen and allowing for flexible syngas composition, using equipment like external combustion units and waste heat recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pure oxygen is used for coal gasification, then gasification efficiency is improved, but equipment investment cost increases due to air separation units
Solution Approach 1:
The patent extracts and removes the air separation unit from the coal gasification system, replacing pure oxygen gasification with air gasification. This eliminates the need for expensive oxygen separation equipment while maintaining gasification functionality through direct air injection into the gasifier.
Solution Approach 2:
The patent substitutes expensive pure oxygen with inexpensive air as the gasifying agent. Air is freely available and requires no separation equipment, effectively using a cheap, readily available resource to replace an expensive one.
2Reliability
If air separation units and waste heat boilers are added, then gasification process is improved, but equipment investment and operational costs increase
Solution Approach 1:
The patent merges the gasification process with direct air utilization, combining the functions of gasification and heat supply into a single integrated system. The exothermic gasification reactions using air provide both syngas production and process heat, eliminating the need for separate waste heat recovery equipment.
Solution Approach 2:
Air serves multiple functions simultaneously: it provides oxygen for combustion, supplies nitrogen for dilution and heat transfer, and acts as the heat source for the endothermic gasification reactions. This multi-functionality eliminates the need for separate air separation and waste heat recovery systems.
3Power
If conventional gasification processes are used, then power generation is achieved, but power generation efficiency is 10%-15% lower than natural gas plants
Solution Approach 1:
The patent changes the gasification parameters by using air instead of pure oxygen, which fundamentally alters the thermodynamic and kinetic characteristics of the gasification process. This parameter change enables higher efficiency by eliminating energy losses associated with air separation and waste heat recovery.
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 enhances gasification efficiency, reduces equipment investment, and increases coal type adaptability, achieving higher power generation efficiency and lower costs by eliminating the need for air separation and waste heat boilers, while producing syngas with varying carbon-hydrogen ratios.
Implementation Method 1
The heat-supplying coal and the high-temperature air are combusted in the external combustion unit to produce high-temperature flue gas
Implementation Method 2
the high-temperature flue gas supplies heat to the carbonization unit and the carbon monoxide-producing unit through the heat transfer units
Implementation Method 3
the carbonization process carbonizes the gasifying coal to produce a product comprising crude coke, coke-oven gas and tar
Implementation Method 4
the carbon monoxide-producing process reacts the crude coke produced in the carbonization process with carbon dioxide to produce carbon monoxide
Implementation Method 5
the shift reaction process reacts a part of the carbon monoxide produced in the carbon monoxide-producing process with water vapor to produce carbon dioxide and hydrogen
Implementation Method 6
The waste heat of the high-temperature flue gas is recovered to preheat air and produce the high-temperature air through the heat exchange unit
Data Source
AI summary
A coal gasification process is provided based on the grading conversion of carbon hydrogen components of coal, wherein the coal gasification process comprises a carbonization process, a carbon monoxide-producing process and a shift reaction process. By blending the coke-oven gas, carbon monoxide and hydrogen produced in the above processes in different ratios, coal gasification syngases with various carbon hydrogen ratios can be obtained. Further, the coal gasification process does not need pure oxygen to take part in the reactions, and has several advantages, such as high gasification efficiency, low equipment investment costs, less limitation on the types of coal and flexible adjustment of the gasification products.