China Pulverized Coal Circulating Fluidized Bed Staged Pyrolysis Gasification Technology

Advantages of pulverized coal circulating fluidized bed staged pyrolysis gasification technology1. Using lignite and low metamorphic bituminous coal at low prices;
2. High gasification intensity;
3. Flexible adjustment of production load;
4. Stable and reliable operation, high operation rate;
5. The methane content in coal gas is high and basically does not contain tar;
6. Lower gas production cost;
7. solid slag discharge structure is simple, etc.Technical process flow of pulverized coal circulating fluidized bed staged pyrolysis gasification power generation technology
(1) Raw material transportation
Qualified pulverized coal ≤6mm and a small amount of limestone and other additives are sent from the coal preparation section to the gasifier coal bunker. The coal is fed into the middle of the circulating fluidized bed of the gasifier through the screw feeder at the bottom of the coal bunker.
(2) Pyrolysis and gasification reaction
The pulverized coal entering the furnace is mixed with fast fluidized high temperature particles and gasification gas in a fluidized bed; finer particles of coal powder flow upwards and high temperature pyrolysis; coarser particles fall downwards into the bottom of the furnace, in the boiling charge , The gas and solid two phases undergo violent mass transfer and heat transfer, and the combustion reaction and water gas reaction generate CO, H2, CO2, etc., and limestone is used as a desulfurizer to remove sulfur from the gas. The temperature distribution in the dense phase section is uniform and the reaction temperature is high, which greatly reduces the tar, phenol and light oil produced by the rapid pyrolysis of coal after heating. The cracking under high temperature conditions in the bed mainly produces small molecules such as CH4. The semi-coke and ash separated by the first-stage cyclone are sent back to the bottom of the circulating fluidized bed by steam through the return device, and the fine powder separated by the second-stage cyclone is tangentially carried by the steam and air through the return device. Into the entrained bed, gasification reaction occurs, and the liquid slag and gas flow into the circulating fluidized bed.
(3) Gas purification
The separated gas first enters the waste heat boiler to recover part of the heat by-product steam, and then enters the moving bed for purification and dust removal, and then is used as industrial gas for users or power generation. The low-carbon ash and slag are discharged into a closed ash hopper through the heat exchange screw slag discharger, regularly discharged to the bottom slag car, and then dumped into the slag bin, and sent to the temporary slag storage yard via a short belt.Technical characteristics of staged pyrolysis and gasification of pulverized coal in circulating fluidized bedThe equipment has two parts: an entrained bed and a circulating fluidized bed, which realizes the staged gasification of coal; by setting up a grading separator, the entrained semi-coke enters different beds according to different particle sizes; secondly, the entrained bed is a tangential feed, liquid Slagging. It can adapt to different coal types, low residual carbon content in coal ash and high carbon utilization rate.
Syngas contains a large amount of methane, has high calorific value, and is suitable for making gas; it has high gasification intensity, small equipment volume, low steel consumption, and greatly reduced fixed investment; simple operation, convenient startup and shutdown, good continuity, and coal type adaptability Strong; realizes partial desulfurization in the reactor and simplifies the purification process; the high-temperature gas and liquid ash generated in the entrained bed provide heat for the circulating fluidized bed at the same time, and the liquid ash is converted into solid ash and discharged, and the ash discharge process is simple.