The problem of adding CaO to lower the ash melting point when coal-water slurry is formed into a propeller
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CWS gasification technology has certain requirements for ash melting point. When coal with high ash melting point is encountered, calcium oxide is usually added to lower the ash melting point. Where is the relationship between the amount of addition, ash content and ash melting point? Please enlighten me. This post was last edited by liuze78 on 2008-3-14 10:57 ]
I remember that technicians from Lunan and Weihua have published technical papers on ash melting point. The empirical calculation formulas are introduced in the article. You can check it out.
Generally, it is added before the mill is fed. The specific proportion should be determined by coal quality analysis and slurry test. After the equal proportion adjustment is determined, the addition amount should be determined according to the amount of coal added, and a conveyor belt of considerable size should be equipped. However, since the melting point of coal ash is not very high in current devices, they are generally backup systems and are not usually added.
Generally measured by the acid-base ratio, the acid-base ratio = (W sio2 + W al2o3) / (W fe2o3 + Wcao + Wmgo). When the ratio is between 1 and 5, it is easy to melt, and when it is greater than 5, it is refractory. Therefore, adding alkaline substances such as calcium oxide or iron oxide can effectively reduce the ash melting point without introducing new components and has no impact on the chemical properties. The amount of calcium oxide added is about 20-25% of the total ash content, which can effectively reduce the ash melting point. If iron oxide is added, about 15% is enough. I hope the above reply can answer your questions, and everyone can communicate more.
The flux added to coal ash cannot be CaO. If CaO is added, the slurry will not flow and will just become coal slime. It should be said that dolomite is mainly calcium carbonate and magnesium carbonate. It is best to determine the amount of ash melting point added through experiments. There is still a difference between theoretical calculation data and actual data.
I agree with what the 5th floor said, it is better to determine the co-solvent in a pilot test.