Experimental investigation of the wetting ability of surfactants to coals dust based on physical chemistry characteristics of the different coal samples

To select suitable surfactant as water-spray additive to improve dust suppression efficiency, six types of coal sample (lignite, long flame coal, non-caking coal, gas coal, coking coal, and anthracite) were selected from some typical mining areas in China, the influence of the physical chemistry characteristics of coal samples on the wetting ability of surfactants to the coals dust was investigated. Their proximate composition, ultimate content, chemical structure, surface morphology, pore structure parameters, and contact angle were determined. Three kinds of anionic surfactants – Sodium Alcohol Ether Sulphate (AES), Sodium Alpha-Olefin Sulfonate (AOS), Fatty Acid Methyl Esters Ethoxylate Sulfonate (FMES) – and one kind of nonionic surfactant – Coco Diethanolamide (CDEA) – were selected to carry out sedimentation experiments on the coal samples dust, to explore the main factors influencing the wettability of the coal samples dust. Among these factors, pore size is the main factor determining the wettability of coal dust, the contact angle decreases linearly (R² = 0.96) with pore size increase. The experimental results demonstrate that the following factors produce correspondingly increased wettability: higher moisture content, lower carbon content, higher oxygen content, more oxygen-containing functional groups, and increased pore size. In addition, the wettability of the six types of the coal samples dust shows a high-low-high trend with metamorphic degree increase, lignite has the strongest wettability, and the coking coal with the highest degree of metamorphism in the selected bituminous coal sample has the weakest wettability. Moreover, compared with nonionic surfactants, anionic surfactants have stronger wetting ability, but the same anionic surfactants have different wetting abilities to coal dust with different metamorphic degrees. AOS has stronger wetting ability to the dust of long flame coal, non-caking coal, and anthracite; AES has stronger wetting ability to the dust of lignite and coking coal; and FMES has stronger wetting ability to the dust of gas coal. The research results provide a theoretical basis for different coal mines to select suitable surfactants as water-spray additives to improve dust suppression efficiency.     

Experimental investigation on the flowability properties of cohesive carbonaceous powders

The flowability properties of two carbonaceous powers (anthracite coal and petroleum coke), including angle of repose (AOR), Hausner ratio (HR) and powder compressibility (C), etc., were determined. The effects of particle size, external moisture content (MC) and power type on powder flowability properties were investigated. The results indicate that as the powder particle size increases, the AOR, HR and C decrease, respectively, and the powder flowability becomes better. As the powder external MC increases, the AOR, HR and C increase, respectively, and the powder flowability becomes worse. The anthracite coal has lower values of AOR, HR and C, and higher values of flow function (FF) than those values of petroleum coke. Therefore, anthracite coal has better flowability compared to petroleum coke. Meanwhile, there exists a good linear correlation between AOR and HR.     

Elemental analysis of organic species with electron ionization high-resolution mass spectrometry

We present a new elemental analysis (EA) technique for organic species (CHNO) that allows fast on-line analysis (10 s) and reduces the required sample size to approximately 1 ng, approximately 6 orders of magnitude less than standard techniques. The composition of the analyzed samples is approximated by the average elemental composition of the ions from high-resolution electron ionization (EI) mass spectra. EA of organic species can be performed on organic/inorganic mixtures. Elemental ratios for the total organic mass, such as oxygen/carbon (O/C), hydrogen/carbon (H/C), and nitrogen/carbon (N/C), in addition to the organic mass to organic carbon ratio (OM/OC), can be determined. As deviations between the molecular and the ionic composition can appear due to chemical influences on the ion fragmentation processes, the method was evaluated and calibrated using spectra from 20 compounds from the NIST database and from 35 laboratory standards sampled with the high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). The analysis of AMS (NIST) spectra indicates that quantification of O/C is possible with an error (average absolute value of the relative error) of 30% (17%) for individual species. Precision is much better than accuracy at +/-5% in the absence of air for AMS data. AMS OM/OC has an average error of 5%. Additional calibration is recommended for types of species very different from those analyzed here. EA was applied to organic mixtures and ambient aerosols (sampled at 20 s from aircraft). The technique is also applicable to other EI-HRMS measurements such as direct injection MS.     

热处理对无烟煤/聚苯胺复合材料电容性能的影响

先对无烟煤进行低温真空热处理,除去在无烟煤的孔隙内和外表面吸附的低分子碳氢化合物,再将苯胺引入无烟煤的孔隙和外表面上,原位聚合制备出无烟煤/聚苯胺复合材料。分别用氮气吸附仪、扫描电子显微镜(SEM)、傅立叶红外光谱仪(FTIR)、电化学工作站和电阻率测定仪对其微观结构与电容性能进行了表征,结果发现:低温真空热处理增大了无烟煤的比表面、孔容和孔径,且没有破坏煤的大分子骨架,促进了煤大分子与聚苯胺链间的氢键作用,有效地改善了复合材料的电容特性。无烟煤经140℃真空热处理150min后制得的复合材料,在表面有均匀的微纳米级聚苯胺颗粒附着,比电容达到231.60F/g(3.33A/g),且循环可逆性更好。     

Chemiluminescent method for detection of eutrophication sources by estimation of organic amino nitrogen and ammonium in water

An automatic method has been developed for the estimation of organic amino nitrogen (CH2-NH) and ammonium in water samples. We propose a continuous flow system in which nitrogen compounds react with hypochlorite reagent to produce chloramines. Subsequently, the mixture is mixed with luminol, generating a chemiluminescence signal. The signal emission at 425 nm, registered as a function of time, decreases as nitrogen concentration increases, due to the decrease on hypochlorite concentration. A large number of nitrogen compounds have been assayed and their sensitivities compared, in milligrams per liter nitrogen. The ammonium calibration graph, expressed as N, can be used for most of the assayed compounds. The linear interval was 0.24-4 mg L(-1) N, with the detection limit 0.07 mg L(-1) N. The chemiluminescence method was applied to the analysis of several kinds of real water samples, natural, lake, irrigation ditch, fountain, residual, and seawater in order to detect possible sources of eutrophication. The accuracy (% relative error) and precision were satisfactory, with mean values of 5 +/- 4 and 3 +/- 2, respectively. This procedure has been used to estimate nitrogen content in samples before and after Kjeldahl treatment. In the same samples, the N found for the untreated samples provided a good estimation of the N Kjeldahl. Sixty samples per hour can be analyzed, and the procedure can also be used for in situ monitoring.     

Development of an apparatus for on-line analysis of unburned carbon in fly ash using laser-induced breakdown spectroscopy (LIBS)

The level of unburned carbon in fly ash is an important criteria for evaluating the combustion efficiencies of boilers, as well as the commercial value of the produced fly ash. In this work, an automated prototype laser-induced breakdown spectroscopy (LIBS) apparatus comprising an isokinetic sampler, a sample preparation module, and a LIBS module has been developed for possible application to power plants for on-line analysis of unburned carbon in fly ash without being affected by the type of coal burned. Emphasis is placed on the structure and operation of the LIBS apparatus, the optimum suction capacity selection, the analytical methods for estimation of the exact C line intensity, and the proper calibration model established for minimizing the matrix effects, which enable the minimization of matrix effects and obtaining more accurate compositional measurements. Good agreement has been found between the laboratory measurement results from the LIBS method and those from the traditional method. The measurement accuracy presented here for unburned carbon analysis is estimated to be 0.26%, while the average relative error is 3.81%.     

Single-pass attenuated total reflection Fourier transform infrared spectroscopy for the prediction of protein secondary structure

Principal component regression (PCR) was applied to a spectral library of proteins in H2O solution acquired by single-pass attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy. PCR was used to predict the secondary structure content, principally alpha-helical and the beta-sheet content, of proteins within a spectral library. Quantitation of protein secondary structure content was performed as a proof of principle that use of single-pass ATR-FT-IR is an appropriate method for protein secondary structure analysis. The ATR-FT-IR method permits acquisition of the entire spectral range from 700 to 3900 cm(-1) without significant interference from water bands. An "inside model space" bootstrap and a genetic algorithm (GA) were used to improve prediction results. Specifically, the bootstrap was utilized to increase the number of replicates for adequate training and validation of the PCR model. The GA was used to optimize PCR parameters, particularly wavenumber selection. The use of the bootstrap allowed for adequate representation of variability in the amide A, amide B, and C-H stretching regions due to differing levels of sample hydration. Implementation of the bootstrap improved the robustness of the PCR models significantly; however, the use of a GA only slightly improved prediction results. Two spectral libraries are presented where one was better suited for beta-sheet content prediction and the other for alpha-helix content prediction. The GA-optimized PCR method for alpha-helix content prediction utilized 120 wavenumbers within the amide I, II, A, B, and IV and the C-H stretching regions and 18 factors. For beta-sheet content predictions, 580 wavenumbers within the amide I, II, A, and B and the C-H stretching regions and 18 factors were used. The validation results using these two methods yielded an average absolute error of 1.7% for alpha-helix content prediction and an average absolute error of 2.3% for beta-sheet content prediction. After the PCR models were developed and validated, they were used to predict the alpha-helix and beta-sheet content of two unknowns, casein and immunoglobulin G.     

An a posteriori method based on photo-acoustic cell information to correct for lidar transmitter spectral shift: application to atmospheric CO(2) differential absorption lidar measurements

An a posteriori corrective method based on photo-acoustic cell (PAC) information is proposed to correct for laser transmitter spectral shift during atmospheric CO(2) measurements by 2 microm heterodyne differential absorption lidar (HDIAL) technique. The method for using the PAC signal to retrieve the actual atmospheric CO(2) absorption is presented in detail. This issue is tackled using a weighting function. The performance of the proposed corrective method is discussed and the various sources of error associated with the PAC signal are investigated. For 300 shots averaged and a frequency shift (from the CO(2) absorption line center) lower than the CO(2) absorption line half-width, the relative error on HDIAL CO(2) mixing ratio measurements is lower than 1.3%. The corrective method is validated in absolute value by comparison between HDIAL and in situ sensor measurements of CO(2).     

溶胶—凝胶法制备基于荧光猝灭原理的光纤氧传感器在线监测水中溶解氧

利用氧分子对金属钌化合物的荧光具有猝灭作用的特性,构造出基于荧光猝灭原理的光纤氧传感器。就用于水中溶解氧在线监测的光纤光谱仪的搭建、传感器探头的设制及传感膜的制作过程进行探索,并对传感器的响应性能进行考察。结果表明以联吡啶钌等作为荧光指示剂以溶胶-凝胶法制备的传感膜对溶解氧的响应具有良好的可逆性,稳定性,较快的响应时间和较长的使用寿命。与标准法相对照,用本仪器系统测定了不同盐度的人工海水中的溶解氧浓度,两种方法在不同浓度水平下的溶解氧测定值均无显著性差异。本法的日内和日间RSD在1.7％～5.0％之间。     

A comparative study of the characteristics of baked carbon mixes employing different filler materials

A study of the physical characteristics of baked carbon mixes employing calcined petroleum coke, coal-tar pitch coke, metallurgical coke and anthracite coal has been made to explore their relative suitability and area of application. It is revealed that petroleum coke and pitch coke lead to a carbon product of almost the same density and electrical resistivity. However, the crushing strength of the product employing pitch coke is 1 1/2 times that of the one employing petroleum coke. The carbon product produced from the metallurgical coke is found to be slightly inferior in respect of density and electrical resistivity and slightly superior in respect of crushing strength when compared with that made from petroleum coke. The use of anthracite coal results in a carbon product of significantly lower density and much higher electrical resistivity than that of the product using the petroleum coke. However, the strength of the anthracite coal-based carbons is found to be nearly double that of the petroleum coke-based carbons. Thus, the significance of the present study lies in the fact that the above findings help one to estimate a possible filler composition for a carbon product possessing the desirable critical characteristics.     

金属化合物对煤岩显微组分所制活性炭吸附性能的影响

研究了Ni2O3,Fe2O3等金属化合物对太西无烟煤和大同烟煤分离富集镜质组、丝质组所制活性炭吸附性能的影响。研究结果表明：金属化合物能显著加快太西无烟煤显微组份的活化反应速度，部分金属化合物可以提高太西无烟煤显微组分所制活性炭的吸附性能，但对大同烟煤显微组分所制活性炭的性能影响不大，其因在于大同烟煤的反应性高于太西无烟煤。加入金属化合物提高无烟煤显微组份活化反应速度的主要原由是金属化合物对碳与水蒸气活化反应有一定的催化作用，使活化活性点增加，进而提高了活化反应效率；而能否提高活性炭的吸附性能则与金属化合物和煤岩显微组分的性质有关。     

Spectrally constrained chromophore and scattering near-infrared tomography provides quantitative and robust reconstruction

A multispectral direct chromophore and scattering reconstruction technique has been implemented for near-infrared frequency-domain tomography in recovering images of total hemoglobin, oxygen saturation, water, and scatter parameters. The method applies the spectral constraint of the chromophores and scattering spectra directly in the reconstruction algorithm, thereby reducing the parameter space of the inversion process. This new method was validated by use of simulated and experimental data, and results show better robustness and stability in the presence of higher levels of noise. The method suppresses artifacts, especially those significant in water and scatter power images, and reduces cross talk between chromophore and scatter parameters. Variation in scattering was followed by this spectral approach successfully in experimental data from 90-mm-diameter cylindrical phantoms, and results show linear variation in scatter amplitude and reduced scattering coefficient (micro(s)'), with total hemoglobin, oxygen saturation, and water remaining constant and quantitatively accurate. Similar experiments were carried out for varying oxygen saturation and total hemoglobin. Accurate quantification was obtained with a mean error of 7.7% for oxygen saturation and 6.2% for total hemoglobin, with minimal cross talk between different parameters.     

Holographic data storage using an optimized phase mask

Abstract

A method for reducing the reconstruction error and improving the spectral distribution in holographic data storage has been proposed. An optimized phase mask is introduced into the optical system. By using the phase mask, the reconstruction error and uniformity of the spectral distribution can be optimized. The relative importance between reconstruction error and uniformity can be emphasized with an adjustable weight factor. The phase mask can be designed by using amplitude-phase retrieval algorithms. Simulation results have shown the merits of the proposed method. The feasibility of optical realization is investigated briefly.     

Absorption spectroscopy of N(2)O with phase-diffusion-noise sidebands on a lead-salt tunable diode laser

The broad phase-diffusion-noise spectrum of a lead-salt tunable diode laser (TDL) has been exploited for the detection of absorbances produced from low-pressure N(2)O vapor in the 4.47-μm spectral region. This effect has previously been observed in the detection of electronic transitions in rubidium, cesium, and molecular oxygen with anAlGaAs TDL operating in the 0.700-0.800-μm region. For the first time to our knowledge, this paper presents evidence of this phenomenon when a midinfrared rovibrational absorption line is monitored. The technique is also compared with traditional TDL spectroscopic methods for its applicability to trace-vapor monitoring.     

兰炭在600 MW无烟煤“W”火焰锅炉上的掺烧应用研究

通过对兰炭粉末和设计无烟煤详细的煤质特性分析和对比,系统分析了兰炭在某600 MW无烟煤“W”火焰锅炉上掺烧的可行性。结果显示某电厂掺烧兰炭技术上是可行的,在保证带负荷能力的前提下掺配兰炭的上限是3台磨煤机专磨。考虑到兰炭极强的磨损特性,在掺烧前需要对磨煤机、煤粉分离器、煤粉管道、燃烧器等设备、部件进行防磨改造,并做好后续的运行维护。掺烧兰炭不会降低锅炉热效率,而且由于燃料综合含尘量、含硫量的大幅降低,带来了很大的环保效益和经济收益。当兰炭与原煤的价格差小于220元/t时,掺烧兰炭有收益,而且差值越小,收益就越大。     

Determination of oxygen and water vapour in modified atmosphere packages for meat sausages with and without an oxygen absorber

A gas chromatographic method has been developed that measures both the residual oxygen concentration and the level of relative humidity during the same run in modified atmosphere packages (N₂/CO₂) with and without an oxygen absorber. A processed meat product with a high content of water served as the foodstuff in those packages. The chromatographic system consists mainly of a loop-injector connected to capillary columns coupled in series and a thermocouple detector. The introduction of an oxygen absorber seems to be attractive, since the concentrations obtained for the residual amount of oxygen in the packages with an oxygen absorber varied between 0.0043 and 0.029%. For packages without an absorber, the oxygen concentrations were much higher and fluctuated between 0.26 and 0.56%. The whole measuring period lasted for 27 days. The relative humidity, also a factor that can cause food deterioration, was 100%. © 1997 John Wiley & Sons, Ltd.     

Measurement of the oxygen isotopic composition of nitrate in seawater and freshwater using the denitrifier method

We report a novel method for measurement of the oxygen isotopic composition (18O/16O) of nitrate (NO3-) from both seawater and freshwater. The denitrifier method, based on the isotope ratio analysis of nitrous oxide generated from sample nitrate by cultured denitrifying bacteria, has been described elsewhere for its use in nitrogen isotope ratio (15N/14N) analysis of nitrate. (1) Here, we address the additional issues associated with 18O/16O analysis of nitrate by this approach, which include (1) the oxygen isotopic difference between the nitrate sample and the N20 analyte due to isotopic fractionation associated with the loss of oxygen atoms from nitrate and (2) the exchange of oxygen atoms with water during the conversion of nitrate to N2O. Experiments with 18O-labeled water indicate that water exchange contributes less than 10%, and frequently less than 3%, of the oxygen atoms in the N20 product for Pseudomonas aureofaciens. In addition, both oxygen isotope fractionation and oxygen atom exchange are consistent within a given batch of analyses. The analysis of appropriate isotopic reference materials can thus be used to correct the measured 18O/16O ratios of samples for both effects. This is the first method tested for 18O/16O analysis of nitrate in seawater. Benefits of this method, relative to published freshwater methods, include higher sensitivity (tested down to 10 nmol and 1 microM NO3-), lack of interference by other solutes, and ease of sample preparation.     

Optimization of the process of plasma ignition of coal

Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.     

基于离散频谱校正的差分吸收光谱数据处理方法研究

差分吸收光谱法(DOAS)常利用傅里叶变换滤波法来滤除光谱数据中的噪声, 但因其频率分辨率的限制,致其幅值误差较大,从而影响气体的测量精度。提出了一种离散频谱校正的差分吸收光谱数据处理方法,利用离散频谱主瓣内的谱线重心求出峰值的坐标,对幅值误差进行补偿,提高气体的测量精度。对不同浓度的SO2气体进行了浓度反演实验,结果表明:频谱校正法的反演误差小于5%,相对于传统的最小二乘法和傅里叶变换滤波法误差分别减少0.36%和0.88%;在谱线漂移两个采样间隔为0.28nm时,传统最小二乘法的平均误差为31.8%,频谱校正法的最大误差则为3.8%,效果明显优于前者。     

近红外漫反射光谱法快速检测火药吸收药混合液中黑索今组分含量

研究了采用近红外( NIR)漫反射光谱技术快速检测火药吸收药混合液中黑索今( RDX)组分含量的方法。将装有混合液样品的烧杯置于光谱仪主机光源窗口上方,直接采集样品光谱图。通过分析纯RDX和样本的近红外光谱,确定908~945 nm、1094~1253 nm和1577~1678 nm作为建模谱区。通过比较不同的光谱预处理办法的效果,选择标准正态变换( SNV )＋一阶导数＋谱线平滑对原始光谱进行预处理。采用偏最小二乘方法(PLS)对RDX组分建立了定量线性校正模型。结果表明：模型的交叉验证决定系数(R2cv)为0.9879,交叉验证均方根误差(RMSECV)为0.2420,预测均方根误差(RMSEP)为0.2127,预测结果的平均相对误差为0.5661％,25 s内完成样品分析。该方法可给改性双基火药的连续自动化生产提供技术支持。