Is it necessary to add a cosolvent to water-coal slurry?
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Is it necessary to add a solubilizer to water-coal slurry? The reason for adding it is to ensure smooth slag discharge from the gasification furnace when there are fluctuations in the ash melting point of the raw coal. The reason against adding it is that many companies that produce water-coal slurry have found, through years of experience, that whether a solubilizer is added or not makes no difference. Please share your opinions!
Whether to use it or not depends on the ash fusion point of the coal you are using. Generally, due to limitations in the heat resistance of the materials, it is recommended to use a flux for coals with an ash fusion point above 1400 degrees. The type and amount of flux are determined based on the characteristics of the coal quality; generally, limestone or iron oxide is used as a flux.
Whether to use a cosolvent depends mainly on the quality of the coal being used. The addition of solubilizers is primarily aimed at reducing the ash fusion point of coal and altering the composition of the ash in coal. The ash fusion point of coal is determined mainly by substances such as SiO2, Al2O3, and TiO2 present in the coal ash. The CaO added acts together with SiO2 in the coal ash to form eutectic compounds, thereby reducing the ash fusion point and changing the viscosity-temperature properties of the ash, which facilitates the liquid discharge of slag. If the SiO2 content in the coal is relatively low, and the levels of CaO, Fe2O3, MgO, Na2O, and K2O are appropriate, then no solubilizer is needed; this is especially true for coals with low ash content and a low ash melting point. According to experience. It is sufficient for the total amount of CaO, Fe2O3, MgO, Na2O, and K2O in the ash to be 20-25%.