Hierarchical gasification technology

Personally, I think staged gasification is more suitable for coal-to-natural gas, IGCC, etc

Slurry coal is still the better option. Beijing DaliKe mainly focuses on the gasification of slurry coal. Below is a brief introduction: Dividing the continuous gasification process of coal into two stages (or multiple stages) was proposed based on an analysis of existing problems and research into the underlying mechanisms, which is a scientific approach. For a continuous gasification process, the actual gasification also takes place in stages sequentially: first is the evaporation of water and the removal of volatiles, followed by the ignition and combustion of the coal particles as well as the gasification process. This process proposes to initiate the combustion of coal particles before proceeding with classification. The main combustion process takes place in the first stage, while in the second stage, some oxygen is added to complete the entire combustion and gasification processes. As a result, the chemical reaction of coal goes through five stages: dehydration and volatilization → combustion → gasification → re-combustion → re-gasification, rather than the traditional sequence of dehydration and volatilization → combustion → gasification only. In the first stage, the amount of oxygen added is controlled to keep the temperature below the ash melting point of the coal; in the second stage, the addition of oxygen raises the temperature above the ash melting point, thereby enabling non-slagging and slagging classified gasification of coal. Due to the addition of secondary oxygen, the temperature level at the lower part of the gasifier increases, resulting in a more uniform temperature distribution throughout the gasifier from top to bottom. The average temperature level rises as well, enabling more complete gasification reactions. The increase in the lower temperature facilitates smoother slag discharge from the gasification furnace. The key to this process is the temperature control in the non-slagging section and the slagging section. By introducing oxygen in stages, and by adding oxygen simultaneously to the first and second sections, it is possible to reduce the temperature near the nozzle of the gasification furnace and increase the temperature at the lower part of the furnace. This results in a more balanced temperature distribution within the gasification furnace and extends the lifespan of the nozzle. By combining staged oxygen addition, some CO2, N2, water vapor, or other gases can also be introduced in the first stage as regulating agents to control the degree of premixing between oxygen and water-coal slurry, thereby regulating the speed and extent of the chemical reaction. The chemical reaction itself is utilized to control the distance between the flame center and the nozzle tip, as well as the temperature in the flame center area, thus further reducing the temperature in the nozzle region and enabling precise control over the temperature distribution within the gasification furnace. This post was last edited by zhangwei643 on 2008-1-19 11:15.]