Requirements of direct liquefaction technology for coal quality
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This post was last edited by jordan569 on 2013-1-6 at 20:24. Considering normal production operations, investment, economic benefits, etc., coal liquefaction has certain requirements regarding coal quality, as follows: 1. The ash content in coal should be low: The ash content in coal generally should be less than 5%, and the composition of the ash also affects the liquefaction process. Elements such as iron, cobalt, and molybdenum in the ash are beneficial for liquefaction and act as catalysts in this process； Elements such as silicon, arsenic, calcium, and magnesium are not conducive to liquefaction; they tend to cause scaling, which affects heat transfer and hinders normal operation. They can also lead to pipe blockages and wear. It is necessary to wash and sort the raw coal to produce refined coal, which is then liquefied. 2. The coal must have good grindability: For the direct liquefaction of coal, it first needs to be ground into coal powder with a particle size of around 200 mesh and dried to a moisture content of less than 2%, after which it is converted into oil-coal slurry; this slurry is then subjected to hydrogenation reactions under high temperature and pressure. Grindability is primarily related to energy consumption and component wear, etc., in order to minimize production and investment costs. 3. High hydrogen content: The lower the oxygen content in coal, the higher the hydrogen content, which allows for a reduction in the amount of hydrogen required and lowers the volume of wastewater generated during production, thereby improving economic and environmental benefits. 4. Low content of heteroatoms: It is essential that the nitrogen and sulfur contents in coal be low, in order to reduce the costs associated with processing and upgrading oil products. 5. Coal lithology: Generally, the vitrine fraction in coal contains high amounts of hydrogen and is easy to liquefy, whereas the inertinite fraction is difficult to liquefy. 6. Low moisture content: This reduces the energy required for drying and also facilitates grinding. . Note $ # , $ $
Are the requirements for residue oil and coal the same?
When the ash content in coal is high, coking tends to occur. Is this similar to the mechanism by which rain forms in the atmosphere? Rain forms because dust particles in the air act as adsorbents or carriers; similarly, does ash serve as an adsorbent or carrier for the formation of coke?
I haven’t found in the literature any information regarding what requirements the residue should meet when it is analyzed Do you know?
Reply to 4# Jian@Beibei: Residue is generally the bottom product of atmospheric and vacuum distillation towers; it is semi-solid at room temperature and contains a certain amount of solids, so it is not fed into a fixed-bed reactor for hydrogenation. The Petroleum University has done a lot of work on residue hydrogenation. Also, I still don’t understand what you’re saying; it sounds a bit awkward to me
This post was last edited by defeil on 2011-3-28 at 10:08. Reply to 1# coal2011: “5. Coal lithology: Generally, the vitrine fraction in coal contains high amounts of hydrogen and is easy to liquefy, while the inertinite fraction is difficult to liquefy.” ”It seems like this sentence isn’t correct, right? The organic microscopic components of coal are divided into: vitrinite, fusinite, and liptinite. The stability of the three components increases in sequence; therefore, it can be concluded that a high vitrinite content and a low inertinite content indicate good liquefaction properties of the coal.
In the books I read, there are the vitrinite group, the stable group, and the inert group; the vitrinite group is the one that is easiest to liquefy