Component fluctuation issue in four-nozzle gasifier
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Two gasification furnaces are in operation; coal slurry is produced from the same coal. In Furnace A, the methane level is consistently maintained between 800 and 1000, and the composition is satisfactory. In Furnace B, the methane level was initially around 800 as well, but the composition remained somewhat high – online analyses and sample tests showed that CO accounted for approximately 51% of the composition. Upon on-site inspection, it was found that there wasn’t severe slag clogging; only a slight amount of stringy slag was present, and the slag volume was within normal limits； The ingredients just haven’t been good. There are no major issues with the coal quality; the coal from the lower layers is slightly inferior, but high-quality coal is used in combination with that from the lower layers as well ； The oxygen ratio at the center was kept at around 15.5%; the amount of coal slurry used per burner was approximately 15 m3, with an oxygen supply of 7400 Nm3/H ； After the composition deteriorated, methane levels were kept around 400. Occasionally the composition improved (but very rarely), yet both online analyses and sample tests still showed a level of 48% ； The control pressure of the gasifier is around 6.3 MPa. I would like to ask the experts: what are the reasons for poor ingredient quality?
Based on what you said, I personally think that coal from before had a higher melting point than cinder coal. 1. Under the same conditions, the former exhibits drawing. 2. Under the same conditions, the former has a higher methane content, indicating that its temperature is lower than that of the latter. (ps: Differences in ash content and volatile matter are not considered) 1. The reason for the higher CO content in the former case is the low temperature, which leads to a reduction in the size of the slag outlet and thus a decrease in the cross-sectional area through which the syngas flows; the most obvious manifestation of this is an increase in the pressure difference at the slag outlet. The reduction of the slag outlet lengthens the residence time of the syngas, increasing gasification and the reduction of CO2, thus resulting in a high CO content. 2. After adding the bottom coal, the CO level was high; it is suspected that an increase in the slurry concentration led to more carbon entering the furnace. With the residence time remaining unchanged, more carbon reacted with CO2 to produce CO.