Pre-treatment of coal – Drying of pulverized coal
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When developing the circulating fluidized bed gasification technology for pulverized coal (0–10 mm), we encountered a problem: most coal is currently extracted using mechanical methods, and water is required to be sprayed during extraction. Additionally, water is also sprayed during the transportation of pulverized coal to prevent dust pollution. As a result, the moisture content of this coal can reach 15–20%, which poses significant difficulties in feeding it into the system (this technology uses spiral feeders for feeding). Bridge formation occurs in the coal hopper, leading to poor coal supply and ultimately overheating, which forces the shutdown of the furnace. Friends in the forum, has anyone learned about coal drying? What technologies are used, and what are their advantages and disadvantages? We are currently using the fluidized bed drying method.
Fluidized bed drying should be fairly effective, but bridging still occurs afterward. Check the temperature of the coal powder after fluidized drying to see if any tar has precipitated; moreover, the subsequent cooling process will also affect the dispersion of the material
We kept the temperature in our fluidized bed dryer below 200°C; sampling and analysis showed no tar deposition.
Our company’s sample hot blast stoves produce inert gas with a temperature of less than 350 degrees and an oxygen content of less than 8%; this gas is fed into the coal grinder for the drying of coal
The main controls are oxygen content and temperature. For the drying of some of our projects, we use hollow-paddle dryers; there is no need to consider other factors, only the production volume and gas consumption.