金属镁在炉外脱硫中的技术探讨

镁作为一种强脱硫剂,在铁水预处理中应用较为广泛.对镁在铁水中的脱硫机理作了简要的叙述,分析了镁脱硫剂的种类以及金属镁脱硫工作的进展及金属镁脱硫有待研究的问题,并提出了采用镁基脱硫剂是对我国发展优质钢材、提高企业竞争力的良好机遇.     

Mineralogy of clean coal combustion by-products

Coal combustion technologies are changing in order to burn coal more cleanly. Many “clean combustion“ and postcombustion technologies are developed to remove SO2 and NOx gases, particulate matter during combustion, or from the flue gases leaving the furnace. This paper focuses on three types of fly ash (flue gas desulfurization (FGD) residuals, atmospheric fluidized bed combustion (AFBC) residuals and sorbent duct injection (SDI) residuals) which produced by “the clean combustion“ and postcombustion technologies. The residuals formed by FGD are PCFA (pulverized coal fly ash) grains entrained with reacted and unreacted sorbent and have lower bulk densities than PCFA grains because it contains higher concentrations of calcium and sulfur, and lower concentrations of silicon, aluminum and iron than PCFAs. AFBC residuals consist of spent bed which is a heterogeneous mixture of coarse-grained bed material and irregularly shaped, unfused, spherical PCFAs. The main crystalline phases in AFBC residuals are anhydrite (reacted sorbent), quartz and lime (unreacted sobent), calcite, hematite, periclase, magnetite and feldspars.The residuals produced by SDI contained 65%-70% PCFA with the larger sizes material being irregularly shaped, fused or roughedged. The reaction products of sorbent (portlandite and lime) included calcium sulfate (anhydrite) and calcium sulfate. The chemical properties of these residuals are similar to those of high calcium PCFAs because of the high alkalinity and high pH of these residuals.     

烟气脱硫产物亚硫酸铵非催化氧化动力学

采用搅拌反应器,通过改变初始亚硫酸铵浓度、pH值、空气流量、温度以及硫酸铵浓度、不加催化剂,对氨法烟气脱硫产物亚硫酸铵氧化反应动力学进行了研究。实验结果表明:在硫酸铵浓度为0.15 mol/L、温度为35～60℃的溶液中、氧化空气流量为150～400 L/h时,亚硫酸铵的氧化速率随着pH值增加而下降,随着温度和空气流量的增加而增大;当硫酸铵浓度增大时,亚硫酸铵的氧化速率下降;在pH值为5.5时反应的活化能为31.88 kJ/mol。     

Adsorptive desulfurization and denitrogenation of model fuel by mesoporous adsorbents (MSU-S and CoO-MSU-S)

Adsorption of heterocyclic sulfur- and nitrogen-containing compounds by mesostructure adsorbent (MSU-S) and its modified form with cobalt oxide is studied using model fuel. The results of characteristic tests (XRD, N₂ adsorption–desorption, FTIR, and SEM) indicate that CoO impregnation causes a negative impact on mesoporous structure, crystalline phase, and particle shape along with a positive effect on surface ion exchange. CoO modification increased the adsorption loadings of DBT and BT to about 33.6% and 45.7%, respectively. For nitrogen compounds adsorption with the model fuel, adsorption loadings of quinoline and carbazole increase by 6.7% and 8.6%, respectively. Data fitting for carbazole, DBT, and BT is achieved better by the Langmuir model than the Freundlich model, and the data of quinoline fitted very well to the Freundlich model for CoO-MSU-S.     

微波脱硫中有机氧赋存形态的XPS分析

采用X射线光电子能谱(XPS)法分析了微波脱硫前后山西某矿高硫煤中有机氧(COO、C=O和C-O等)赋存形态的变化。研究结果表明:脱硫后煤样的O含量由17.97%上升至24.39%,C含量由70.49%下降到58.05%,同时n(O)/n(C)由0.26增至0.42。脱硫前后C1s图谱的拟合数据表明:煤样中C-H、C-C和C-O单键的含量分别从41.41%和28.74%下降到35.54%和7.10%,羰基和羧基含量分别由0.11%和0.21%增至10.38%和5.03%。     

Decomposition Characteristics of an Artificial Biogas in a Low‐Pressure DC Glow Discharge

The decomposition characteristics of an artificial biogas, which is a mixture of CH ₄, CO ₂, and H ₂ S, using a low‐pressure DC glow discharge have been investigated. It is found that H ₂, CO, C ₂ H ₂, H ₂ O, CS ₂, and COS are produced from the artificial biogas in the glow discharge. About 65% of the hydrogen atoms in CH ₄ are converted into H ₂ at an input energy of 800 J, at which CH ₄ is completely decomposed, and the decomposition characteristics of the artificial biogas are minimally dependent on the H ₂ S additive. Further, H ₂ S has a tendency to be decomposed earlier than the other components of the artificial biogas. When the glow discharge is generated in the artificial biogas with H ₂ S, some of the carbon atoms are found to deposit on the electrodes and the wall of the discharge chamber. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(1): 26–33, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22304     

Fast Oxidative Removal of Refractory Aromatic Sulfur Compounds by a Magnetic Ionic Liquid

Magnetic ionic liquids (MIL) are extensively used in extraction and catalytic processes. Here, a series of MIL, i.e., 1‐n‐butyric acid‐3‐methylimidazolium chloride/xFeCl₃ ([C₃H₆COOHmim]Cl/xFeCl₃; x = 0.5, 1, 1.5, 2), were synthesized and characterized by infrared spectroscopy, visible absorption spectrometry, and electrospray ionization mass spectrometry. The MIL [C₃H₆COOHmim]Cl/2FeCl₃ was found to be highly active for the extraction and catalytic oxidative desulfurization of a model oil under mild conditions. Of note, the removal of benzothiophene, which has been regarded as a refractory aromatic sulfur compound, could be achieved at up to 100 % in 10 min. After reaction, the MIL could be easily separated from the model oil by applying an external magnetic field, due to its paramagnetic properties.     

Dual‐Layer Hollow Fibers for Sulfur Removal from Fuels

Emission of sulfur compounds to the atmosphere is universally recognized as one key target to be reduced. For membrane pervaporation which is considered as a potential purification process of fuels, dual‐layer polyurethane (PU)/polyethersulfone hollow‐fiber membranes were prepared. A novel fabrication technique is proposed using a quadruple spinneret to produce the fiber with such morphology by simultaneous spinning of two polymer solutions in the presence of two corresponding precipitation media. Activated carbon was added into the PU solution to improve the transport properties of the selective layer. Resulting hollow‐fiber membranes showed very good adhesion between the selective layer and its support, in addition to an effective removal of a sulfur compound such as 2‐methyl thiophene from a typical model fuel, an indication of good prospects for both the fabrication technique and for sulfur removal by pervaporation of fuels.     

Dissolution of multicomponents during hydrothermal leaching of LF desulfurization slag

In light of the multicomponent dissolution equilibrium during the hydrothermal leaching of LF desulfurization slag, thermodynamic calculations were made and the dissolution equilibrium curves of calcium, aluminum and sulfur were plotted to analyze the interactions between these components and their influence on sulfur leaching. Furthermore, slag leaching experiments were conducted to investigate variation of pH and concentration of major components in the leaching solution. The results show that CaS(s) is easily soluble in water, and when pH>11. 4, CaS(s) dissolves to form Ca(OH)2(s). Use of hydrothermal leaching for sulfur removal from LF desulfurization slag is theoretically feasible. CaSO4(s) is difficult to dissolve and its solubility is always lower than that of CaS(s); therefore, slag oxidation affects negatively sulfur leaching. However, when the pH of the leaching environment is controlled to be above 12. 3, CaSO4(s) is gradually transformed into Ca(OH)2(s). Al2(SO4)3(s) is easily soluble, and it is unlikely that Al will react with sulfur in the solution to form a precipitate. The pH of the leaching solution rises with time and remains at about 12. Calcium concentration in the leaching solution is high, while Al concentration is low. Sulfur concentration in the solution increases with time, and Al in the slag has little effect on sulfur leaching. It is thus concluded that hydrothermal leaching is effective in removing sulfur from LF desulfurization slag.