Study On Coal Structure And Gasification Activity

Due to ash melting point, ash and sulfur content is high in Guizhou coal,at the same time, the metal elements content also is high,the Guizhou coal gasification efficiency is low.Guizhou coal that with different metamorphic grade have various functional groups,the macromolecular structure and molecular forces between the small molecules is different.So we need to study the characteristics of the structure in Guizhou coal, so that we can utilize it cleanly and converse it efficiently.This paper took the two Guizhou anthracite from Tongzi and Guiyang,and two kinds of bituminous coal from Liupanshui which is named Hongqi and Xiaoheqiao as the raw material.Then four kinds of Guizhou coals was studied by industrial analysis and elemental analysis, 13 C-NMR, XRD, FT-IR and so on. Their CO2 gasification activity of coals was tested by the fixed reactor.The main conclusions are as follows:1.Four experimental coal samples was tested by scanning electron microscopy/spectroscopy, X-ray diffraction(XRD), Fourier infrared spectrum, X-ray photoelectron spectroscopy and solid 13 C nuclear magnetic resonance(NMR).The various elements content and half quantitative results, microcrystalline structure parameters, the functional groups, atomic(including C, O, N, S) valence state and the information such as content, carbon distribution and aromaticity in coal are obtained.It found that all kinds of microcrystalline structure parameters, the functional groups of coal, atomic(including C, O, N, S) valence state distribution and aromaticity and content, carbon atoms are significantly different, these shows that the structure parameters in different coal have their characteristics.2.By using the analysis of test data,we can use Chemoffice 2004 software to draw the various structure model of coal(TZ, GY, HQ, XHQ),their model molecular formula is C136H76O16N2 S, C138H102O22N2S3, C136H100O29N2, C121H74O25N2 respectively.All of the elements content in model are very close to the experimental data.3. Using Materials Studio 6.0 software to get all sorts of coal sample structure model optimized, by geometrical optimization and energy minimum after simulation, we make the coal structure more reasonable.The structural model built shows that TZ, GY, HQ, XHQ aromatic carbon atoms in the structure of coal form mainly exists in the form of naphthalene, anthracene and pyrene, and a small amount in the form of a ring of impurity atoms.Fat carbon mainly plays a role of connecting the aromatic structure unit. Oxygen mainly exists in the form of phenolic hydroxyl and carbonyl oxygen, there is also a small amount of carboxyl, may be caused by weathering. Nitrogen mainly exists in the form of pyridine and pyrrole,it illustrate the two forms is stable in coal. Sulfur mainly exists in the form of mercaptan sulfur ether and thiophene.4. In fixed bed reactor was designed for four kinds of guizhou coal and pickling coal samples of CO2 gasification activity determination, at the same time combined with XRD analysis data and the mathematical models of the structure of coal, the research of coal structure model and the reason of the difference of gasification activity, in the temperature of the experimental section, the higher the reaction temperature, the higher the coal gasification activity, at 1150 ℃, four coal gasification activity of maximum, TZ, GY, HQ, XHQ char CO2 gasification activity can reach 40.8%, 42%, 48.4% and 42% respectively, TZ, GY, HQ, XHQ pickling char CO2 gasification activity can reach 35.6%, 38.7%, 45% and 38.7% respectively, that after reducing the ash content of coal, CO2 gasification activity declined slightly.The right amount of ash content of coal gasification and have a certain role in promoting.Under the same reaction temperature, as the reaction progresses, four coal gasification activity of the sample, there is a modest decline.Through the analysis of 950 ℃, 1050 ℃, 1150 ℃ under the condition of various XRD chart of coal tar, the results showed that under high temperature, Ca O and other minerals in low temperature eutectic occur together, reduced the coal ash melting point.XRD figure shows a small amount of more complex silicon at high temperature aluminum compound formation, the silicon aluminum compound to improve the coal ash melting point, will reduce the efficiency of coal gasification.Quinone and phenolic hydroxyl groups would hinder the generation of carbon monoxide.The existence six yuan benzene ring would hinder CO 2 gasification reactivity of coal.In addition, the presence of sulfur minerals make the minerals in coal catalysis deactivated.The presence of these factors will reduce the activity of the CO2 gasification of coal in Guizhou.