贫瘦煤对Shell粉煤气化过程积灰影响研究

为了探究PSM煤对Shell煤气化过程积灰的影响,考察了掺烧PSM煤后合成气冷却器进出口温荷变化情况,从飞灰的烧失量、粒度分布、化学组成、表观形貌方面阐述改善积灰的原因。结果表明:掺烧PSM煤后合成气冷却器进出口温荷波动相对较为平缓,并且温荷值相对掺烧前偏低;飞灰烧失量增加,粒度变大、比表面积减小,铁、钙、钾钠含量降低,飞灰球形颗粒表观变化都证明了掺烧PSM煤后飞灰粘附性变差,积灰现象得到明显改善。     

粉煤灰合成人造沸石除磷效果的研究

以粉煤灰为原料,在微波场下水热合成人造沸石,可缩短结晶时间.将这种人造沸石应用于污水处理实验,处理城市景观用水,控制水体富营养化的氮、磷指标.氨氮的去除机理主要为离子交换,而磷的去除机理的研究目前尚缺乏相关资料.合成沸石中含磷量较低时,不影响在污水处理中的应用.     

Effect of pretreatment conditions on the determination of major and trace elements in coal fly ash using ICP-AES

Microwave-assisted acid digestion (MW-AD) followed by atomic spectrometries such as inductively coupled plasma-atomic emission spectrometry (ICP-AES) was examined for the determination of major and trace elements in coal fly ash (CFA). Effective digestion conditions were studied using four certified reference materials of CFA, with particular focus on the composition of acid mixture and the removal of HF after MW-AD. When MW-AD was conducted without using HF (HNO₃+H₂O₂), the tested elements yielded fairly poor recoveries. When MW-AD with HF (HNO₃+HF+H₂O₂) was carried out, two methods for HF removal were attempted, H₃BO₃ addition and evaporation of acids. In the former method, while the recoveries of major elements (Al, Ca, Fe, and Mg) were satisfactory, those of trace elements were not satisfactory; in particular, the recovery of Pb was fairly low. In the latter method, the recoveries of Al, Ca, and Mg were extremely poor; however, those of other elements including the trace elements (Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) were satisfactory. In this paper, the optimization of the digestion method for ICP-AES is discussed. Further, the advantages and limitations of ICP-AES in the determination of elements in CFA are assessed.     

粉煤灰农业利用研究进展

评述粉煤灰农业利用研究进展情况,并讨论其中存在的问题.对未来研究工作进行了展望.     

Volatility of fly ash and coal

The volatilization of fly ash has been examined by a number of techniques including TGA—DTA, Knudsen cell mass spectrometry, volatilization of neutron-activated fly ash, and X-ray fluorescence analysis of sized fly ash, low-temperature ash, and the parent coal. At low temperatures, H₂O, CO₂, SO₂, and a number of organic compounds are the primary volatile species as determined by mass spectrometry. Analysis of the volatiles collected from activated fly ash heated to temperatures up to 1400 °C shows that Hg, Se, As, Br, and I are nearly completely volatilized. The analysis of the bulk and size fractions of fly ash, and parent coal, is consistent with this and provides evidence for volatilization of 15 elements during coal combustion. Comparison of coal and fly ash compositions also shows that significant amounts of Se are still present in the gas phase at the precipitators and more than 50 wt % of the Se is contained in the stack emissions. The results are consistent with present models for fly ash formation and trace element enrichment.     

微波助溶从粉煤灰提取氧化铝新工艺研究

针对从粉煤灰提取氧化铝传统方法中存在的某些缺点，采用高温烧结一微波辐射的联合操作工艺，从粉煤灰中提取氧化铝。就这一方法的工艺路线及影响氧化铝溶出率的相关因素进行了实验研究，探讨了微波对粉煤灰的作用机制。研究结果表明，这一方法不仅加快了氧化铝从粉煤灰中溶出的速率，缩短了反应历程，同时使产品的溶出率提高到95％以上，产品纯度提高到96％以上。这一工艺具有潜在的应用前景。     

煤气化飞灰特性的研究进展

在对煤气化飞灰的物理化学性质、微观形貌、气化反应活性和粘附特性归纳分析的基础上,讨论了气化飞灰的形成机理及其气化过程中的结渣倾向性,并对气化过程中避免飞灰在气化炉内的结渣和在合成气冷却器积灰结垢的措施进行了介绍。最后对气化飞灰的研究热点问题进行了展望。     

Investigations on Cr mobility from coal fly ash

Coal fly ash, which is a source of metals emission to environment, was researched. Investigations on Cr chemical fractions and their environmental mobility in ash-solution system were carried out. In order to obtain results repeatedly, the conditions of sequential extraction of Cr from coal fly ash were optimized. It was found that Cr in coal fly ash occurs in the following fractions (mg kg⁻¹): exchangeable (2.5), associated to carbonates (4.0), associated to organic matter and sulfides (8.5), associated to Fe-Mn oxides (16.0), and residual (41.6). Mobility fractions of Cr contain 8.2% of its total concentration in the fly ash in environmental conditions. The obtained results indicate that coal fly ash is a source of environmental contamination by Cr especially, in soils where its utilization is inadequate.     

烟气及飞灰组分对溴改性飞灰脱汞特性的影响

燃煤飞灰中的未燃碳（unburned carbon,UBC）和金属氧化物因对汞有一定的吸附和氧化作用而被认为是燃煤电厂廉价的潜在脱汞吸附剂,但效率有待提高。文章选取两种UBC含量不同的飞灰,采用质量分数1%的NH₄Br溶液对其浸渍改性,利用固定床汞吸附实验台探究了烟气组分（O₂、SO₂和NO）以及飞灰中无机金属氧化物对汞吸附和氧化的影响,以期获得高效脱汞吸附剂吸附机理。结果表明,O₂对于溴素改性飞灰氧化汞有较小的促进效果,SO₂具有一定的抑制作用,NO促进Hg⁰的氧化效果明显;溴素改性飞灰中的Fe₂O₃和TiO₂对Hg⁰的氧化起着主要作用,原因在于溴素改性增加了金属氧化物Fe₂O₃和TiO₂中的晶格氧含量,促进了Hg⁰的催化氧化,主要遵循Mars-Maessen机理。另外,UBC含量对飞灰脱除Hg⁰的影响很大,溴素嵌入飞灰表面的UBC时,会使其邻域的活性加强,从而增强碳质表面对Hg⁰的吸附能力,促进了后续反应的进行。     

Production of glass from coal fly ash

The coal fly ash from a Chinese thermal power plant was vitrified after the addition of ∼10 wt% Na₂O. The glass products have suitable viscosity at 1200 °C and displayed a good chemical durability. The heavy metals of Pb, Zn, Cr and Mn were successfully immobilized into the glass as determined by the toxicity characteristic leaching procedure method. Results indicate an interesting potential for the coal fly ash recycling to produce useful materials.     

Acidolysis of coal fly ash by Aspergillus niger

The kinetics of aluminium extraction were investigated, using as-received and calcined fly ash samples and a pure culture of Aspergillus niger. This fungus metabolized sucrose to citric and oxalic acids, which were involved in the acidolysis of fly ash. Aluminium extraction from as-received fly ash was only 5–8%, whereas from calcined fly ash it was up to 93.5%. The order of reaction and the overall reaction rate constant were determined by the van't Hoff technique with respect to the concentration of calcined fly ash. A linearized form of a modified Monod expression was applied to the experimental data to assess the kinetic constants for the acidolysis process. Statistically designed experiments were carried out with calcined fly ash and synthetic solutions containing citric and oxalic acids to determine the optimum leaching conditions. The acidolysis reaction mechanism is discussed.     

一种新型板结飞灰预处理系统

针对现有板结飞灰预处理系统存在割袋装置易卡顿、破碎效果差、人工参与度高、效率低等问题,我公司设计一种新型板结飞灰预处理系统工艺,智能化控制,实现板结飞灰吨袋自动上料、破袋、挤压卸料的自运行工序,大大降低减少人工参与工作量,实现平均每小时处理12袋约7.2 t板结飞灰,满足用户安全高效无害化处置要求。     

Humidity-control assists high-efficient coal fly ash removal by PTFE membrane

In the present study, the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene (PTFE) membranes were investigated. The intergranular force of particulate matter at different RH conditions was measured by analyzing the critical angle between particles. Effects of humidity (from 30% to 70%) on filtration pressure drop and membrane fouling conditions were characterized. It was found the membrane showed optimal filtration resistance of 530 Pa at RH of 60% and the gas permeance can be maintained at 1440 m³·m^-2·h^-1·kPa^-1. Moreover, to optimize the operation parameters for this filtration system, effects of fly ash concentration, diameter, membrane pore size, and gas velocities were systematically investigated.     

活性炭/粉煤灰处理含铜废水的研究

采用活性炭/粉煤灰处理模拟含铜废水,考察pH、吸附时间、吸附温度、投加量、质量比、活性炭、粉煤灰粒径、铜离子浓度等对吸附效果的影响。结果表明,单纯粉煤灰的吸附效果较差,但100目的粉煤灰与100目的活性炭混合,其吸附效果接近于纯活性炭。活性炭/粉煤灰处理100 m L、30 mg/L模拟含铜废水的最佳吸附条件为:吸附时间3 h,pH 6,吸附温度45℃,活性炭/粉煤灰(质量比1∶1)投加量2.5 g,活性炭和粉煤灰粒径均为100目。在此条件下,铜离子去除率可达97.33%,处理后水中铜离子浓度(0.811 4 mg/L)低于国家二级排放标准(1.0 mg/L)。     

High capacity cation exchanger by hydrothermal zeolitization of coal fly ash

During; hydrothermal treatment in NaOH medium coal fly ash partially transformed to zeolite P and/or hydroxysodalite, while quartz slowly dissolved and mullite remained stable. Residual coal favored the formation of zeolite P. The relative proportion of the two zeolites could be changed by seeding. During fusion of fly ash with NaOH an endothermic reaction at 170–180°C occurred, resulting in formation of an unreported Na aluminosilicate with approximate composition Na₁₅Si₄Al₃0₂₀ and major XIRD reflections at 4.793, 3.828, 3.000, 2.854, 2.578, and 2.524 Å. The product of fusion interacted with water giving aluminosilicate gel, which yielded zeolite P upon hydrothermal treatment at 100°C without aging and zeolite X after aging in water for 12 hours at room temperature. Cation exchange capacity was 420 and 400 meq/ 100 g for zeolite P and zeolite X respectively.     

活性炭/粉煤灰处理含铜废水的研究

采用活性炭/粉煤灰处理模拟含铜废水,考察pH、吸附时间、吸附温度、投加量、质量比、活性炭、粉煤灰粒径、铜离子浓度等对吸附效果的影响。结果表明,单纯粉煤灰的吸附效果较差,但100目的粉煤灰与100目的活性炭混合,其吸附效果接近于纯活性炭。活性炭/粉煤灰处理100 m L、30 mg/L模拟含铜废水的最佳吸附条件为:吸附时间3 h,pH 6,吸附温度45℃,活性炭/粉煤灰(质量比1∶1)投加量2.5 g,活性炭和粉煤灰粒径均为100目。在此条件下,铜离子去除率可达97.33%,处理后水中铜离子浓度(0.811 4 mg/L)低于国家二级排放标准(1.0 mg/L)。     

Heavy metal characterization of CFB-derived coal fly ash

The present study investigates the heavy metal content of coal fly ash (FA) samples coming from three different sampling points (secondary cyclone, cooler and filter) of a pilot plant combustion facility. The combustion experiments were carried out in a 0.1 MW Circulated Fluidized Bed (CFB) boiler using South African coal, with the addition of limestone for sulfur capture. FA was tested for the presence of selected heavy metals using inductively coupled plasma optical emission spectrometry (ICP-OES); batch leaching tests were conducted as well. The samples were also characterized in terms of their microstructure, chemical and mineralogical composition, total surface area and particle size distribution. Most of the studied metals (Cd, Cr, Cu, Ni, Mn, Zn) showed enrichment in the fine, filter FA particles, while Pb was mostly concentrated in the cooler sample. Regarding leaching characteristics of the examined samples, Cr was found to occur in considerable amounts. Although the use of CFB technology for the combustion of solid fuels steadily gets bigger worldwide, only a very limited number of studies have environmentally assessed CFB-coal FAs to date. Thus, the current study aims to contribute toward building a more integrated knowledge on the environmental impact of this abundant power production by-product.     

Hydrothermal synthesis of zeolites from coal fly ash

The fly ash, from the combustion of coal to produce energy and heat, is an industrial waste, in which large accumulations represent a serious environmental threat. To reduce the environmental burden and improve the economic benefits of energy production, the science and industry focus on the transformation of coal combustion byproducts into new functional materials. The fly ash was studied by modern analytical methods. As a result of the hydrothermal reaction, several types of zeolites were synthesised from the fly ash: analcime, faujasite (zeolite X) and gismondine (zeolite P). It was shown that the experimental conditions (temperature, reaction time and alkali concentration) have a significant influence on the type of zeolite and its content in the reaction products. The series of experiments resulted in building approximate crystallisation field of zeolites and other phases as the first stage of the formation of ceramic membrane and other materials.     

Characteristics of coal fly ash and adsorption application

Several fly ash samples were collected and their physico-chemical properties were characterised using N₂ adsorption, XRD, SEM, and pH titration. These fly ash samples were applied as low-cost adsorbents for removal of methylene blue and humic acid from aqueous solution. It is found that the adsorption has a close relationship with surface area and pore volume. Higher surface area and pore volume of fly ash will result in higher adsorption of methylene blue (MB) and humic acid (HA). The adsorption of MB and HA on various fly ash samples can reach 7 and 10 mg/g, respectively. Solution pH will also influence humic acid adsorption on fly ash and higher pH will result in lower adsorption. Ionic strength will also influence HA adsorption.     

改性粉煤灰矿物组成变化特性试验研究

以低硫兖州煤为试验煤种,开展了低硫煤增钙粉煤灰矿物组成特性试验研究。试验结果表明：改性粉煤灰矿物组成接近贝利特水泥熟料矿物组成,但矿物组成中没有硅酸盐水泥熟料矿物3CaO·SiO2。