宝日希勒褐煤在合成气与复合溶剂系统下的液化性能研究

在合成气（CO+H₂）与复合溶剂（水+有机溶剂）液化系统下研究了气氛、温度、催化剂类型对宝日希勒褐煤转化率、油气水产率和CO转化率等液化特征的影响,从而探讨其液化性能。结果表明,在高含水复合溶剂系统中,合成气气氛、反应温度430-450℃适宜宝日希勒褐煤液化转化,转化率可达到81.15%,油气水产率达到71.53%。该液化系统下,含铁、碱和硫复合型催化剂能有效地提高液化转化率和油气水产率,在430℃催化液化下褐煤转化率达92.27%,油气水产率达79.39%。该催化剂有效促进了煤中大分子的裂解和系统中水煤气变换反应进程,沥青质减少,油含量增多。液化油中多环芳烃衍生物在催化液化过程中向单环芳烃衍生物和烷烯烃转化,分子量降低,提高了油品质量。     

热预处理影响褐煤热解行为研究

采用固定床反应器研究了不同气氛热预处理对内蒙胜利褐煤结构的改变,及其对后续热解行为的影响。结果表明,与原煤相比,热预处理后煤中羟基含量和芳香氢与脂肪氢的比减少,脂肪氢的相对含量增加。与未经处理的煤热解相比,N2、N2+O2、CO2气氛下热预处理后热解水收率下降,热解气收率增加,热解气中CO2含量增高,导致高位热值下降。过热水蒸气热预处理后,焦油质量收率提高3～4个百分点。热解焦油组成的变化与预处理气氛、温度密切相关,过热水蒸气200℃下预处理使得焦油中轻质组分的含量(沸点低于360℃的馏分)比原煤焦油提高了约27个百分点;水蒸气和模拟烟气混合气氛下在200℃及250℃预处理后,其热解焦油中轻油和酚油含量分别提高约60和42个百分点。     

有机钙作用下褐煤SO2、NO析出及燃烧特性

在管式炉上研究了醋酸调制白云石产物、醋酸钙、丙酸钙等有机钙作用下龙口褐煤燃烧时SO₂、NO的析出特性,并在热分析系统上考察了相应的燃烧特性。合适的工况条件下有机钙能有效抑制SO₂、NO的析出。在973~1 273 K下,有机钙均能有效抑制SO₂的析出,而当温度继续升高,除醋酸钙外,其他有机钙抑制效果下降。在973~1 173 K时,有机钙促进了NO的析出,而当温度高于1 173 K时,醋酸钙和丙酸钙的抑制效果明显。随着钙硫比的增加,有机钙对SO₂、NO抑制效果普遍增强,而醋酸调制白云石产物在钙硫比为2.0~2.5时却促进NO的析出。当钙硫比为2.0时,褐煤着火性能明显提高,着火点降低10~33 K,但其燃尽时间稍有延长。     

Quantification of the inorganic phase of the pelagic aggregates from an iron contaminated lake by means of Raman spectroscopy

A semi-quantitative investigation of the inorganic phase of pelagic, iron-rich aggregates (iron snow, IS) formed in an iron polluted aquatic environment was performed by means of Raman spectroscopy. IS samples were collected from two basins of an acidic lignite mine lake and at two different water depths. Although the water chemistry differed at all four sites with respect to oxygen, pH, and, Fe(II) concentrations, the Raman analyses showed that the main mineral formed was schwertmannite (ideal formula: Fe₈O₈(OH)₆SO₄) with concentrations of more than 88% in all IS samples. To determine potential differences in the microbial communities of the IS samples we used denaturing gradient gel electrophoresis. Microbial communities differed between two basins, but showed similarities between redoxcline and deeper water layers of IS samples from the same basin. Surprisingly, these microbiological differences did not lead to strikingly qualitative similarities in the mineral composition, although the initial step in mineral formation, the oxidation of Fe(II) to Fe(III), is a pure microbial process at low pH. Thus, a semi-quantitative method was necessary to elucidate differences in the consecutive mineralization process which is apparently more controlled by water geochemical conditions.     

Microbial desulfurization of different coals

Coal is the most important nonrenewable energy source of fossil origin. It is also the most common fuel in thermal power plants. However, during coal incineration in power plants, high sulfur content of coal poses serious environmental problems owing to sulfur dioxide emission. We studied the application of microbial methods for removal of sulfur from three types of high sulfur coals—two samples collected from Assam and Rajasthan in India and one from Libiaz, Poland. These coal samples were desulfurized using indigenous Acidithiobacillus sp. After investigation of the effect of various parameters, the conditions optimized for the maximum removal of total sulfur (91.87% for lignite, 63.13% for Polish coal, and only 9.44% for Assam coal) were as follows: initial pH of 1.5 (2.5 in the case of Assam coal), particle size of 45 μ, pulp density of 2% (w/v), incubation period of 30 d at −35°C in presence of 44.2 g/L of ferrous sulfate in the media with shaking at 140 rpm. Poor removal of sulfur in the case of Assam coal was owing to extensive precipitation of jarosites. In addition, the sulfur in Assam coal is mostly found in organic form, which is difficult to remove with Acidithiobacillus sp. The removal of sulfur from the three coal samples was demonstrated with photomicrographic studies.     

Investigation of the influence of pressure on the combustion of Alpagut lignite

This research presents the combustion behavior of lignite under different reaction pressures. Lignite from Alpagut, Çorum of Turkey was combusted in its run off mine (ROM) condition under three different pressure levels of 172, 345, 517 kPa (25, 50, 75 psi). Experiments were done in a fully controlled temperature regime in an isolated combustion tube that operated in coordination with a continuous gas analyzer. Combustion behavior of lignite under different pressures was characterized by effluent gas analysis method. The changes in the amounts of consumed oxygen, evolved carbon oxides as well as variations in the temperature were assessed. The combustion efficiency and effectiveness of lignite was evaluated in terms of thermal features, from the viewpoint of reaction kinetics and by the computation of instantaneous fuel consumption at critical points. It was seen that combustion of lignite tended to turn from a steady profile to a considerably rapid one with increase in pressure, proving to be highly sensitive to the applied pressure level. Also, different levels of pressure resulted in distinctive combustion behavior not only from the view of thermal characteristics, but also in terms of reaction kinetics.     

Thermal characterization of humic acids and other components of raw coal

Over the ages, the deposits of dead vegetation buried by rock and mudflows, compacted and compressed out all of the moisture; it slowly carbonized and became coal. Humic acids are natural organic acids — brown coloured biological macromolecules, formed in coal by biochemical changes (decomposition, pyrolysis) of lignocellulosic matter. From lignite coal bed, the humates were extracted in alkaline medium and isolated from the residual fraction. Humic acids were obtained by treating humantes’ solutions with HCl. Thermal analysis (TG, DTG, DTA and DSC) was used in order to establish the decomposition and thermal effects of lignite, humates, humic acids and residual matter extracted from Rovinari mines in Romania. A non-isothermal linear temperature regime was imposed to reveal all decomposition steps.     

胜利褐煤燃烧中未反应残留物结构特性及铁的添加效应

利用TGA确定胜利褐煤盐酸脱灰煤和添加铁组分脱灰煤的着火温度,在着火温度进行燃烧反应,收集燃烧反应一定时间后的未反应残留物,利用FT-IR、XPS、XRD和Raman等对其进行表征,研究了胜利褐煤燃烧过程中铁的影响规律。结果表明,铁的加入降低脱灰胜利褐煤的着火温度,当添加量为3.50%时,着火温度降低的幅度最大。在着火温度燃烧反应一定时间后未反应残留物的FT-IR表明,其有机官能团结构无显著变化,说明铁的添加并不影响其有机官能团结构特性,有机官能团不会对燃烧性能产生太大的影响。添加铁使SL+在燃烧过程中未反应残留物结构芳香度下降,晶面间距增大,晶体结构中缺陷位相对增加,石墨化程度降低,烷基侧链增多,碳氧结构迅速减少,说明铁组分的加入改变了其燃烧过程中碳氧结构转化特性,抑制了石墨化转化速率与程度,即在燃烧反应过程中改变了其未反应残留物的微结构,从而改变了其反应历程,加速燃烧反应速率。     

褐煤模型化合物与异丙醇进行醇解的反应性研究

采用密度泛函理论对褐煤模型化合物与异丙醇醇解的反应特性进行了研究。估算了醇解反应的热力学参数。提出一种将希什菲尔德电荷分布和福井函数相结合的改良方法,用以确定反应物的初始构型。将线性协同转化方法和二次同步转变法相结合用于搜索过渡态,并同时对反应物和产物的构型进行优化。经过计算发现,反应焓随温度升高而降低;反应过程中出现亲核基团;异丙醇是常用醇类中最活泼的醇解剂。因此可认为褐煤醇解反应是放热反应,反应机理为亲核加成机理。     

胜利褐煤和小龙潭褐煤在甲醇中的热溶及热溶物分析

研究了胜利褐煤(SL)和小龙潭褐煤(XLT)在甲醇中的热溶行为,并利用傅里叶变换红外光谱、气相色谱/质谱(GC/M S)和大气压固体分析探针/飞行时间质谱(ASAP/TOF-M S)对320℃热溶物的组成和结构特征进行了分析。两种褐煤热溶物产率均随温度升高而增加,但240℃后XLT热溶物(SPXLT)产率明显高于SL热溶物(SPSL)。GC/MS分析表明,两种褐煤热溶物以含氧化合物为主,尤其酚类的相对含量超过49%;与SPXLT相比,SPSL中烯烃、芳烃、醚类、羧酸、酯类和有机硫化合物(OSCs)含量较高,而烷烃、酚类、酮类和有机氮化合物含量较低;SPSL中的OSCs以噻吩为主,而SPXLT中的OSCs以硫醇为主。ASAP/TOF-M S可检测出热溶物中大量GC/M S无法检测出的较强极性和难挥发化合物;与SPXLT相比,SPSL中CHO和CHS族分含量较低,而CHN、CHNO、CHOS、CHNS和CHNOS族分含量较高;两种褐煤热溶物中化合物的碳数和双键数(double bond equivalent,DBE)主要分布在3-15和0-10,SPXLT中化合物的碳数和DBE分布相对集中。